JP2011245703A - Printer, program, and printing method - Google Patents

Abstract

Print data of a printing method having a transition process between a normal process and a lower end process is created.
When normal processing is continued after normal processing instead of lower-end transition processing, a virtual position that is a position on the medium of dots that can be formed by a nozzle is calculated, and lower-end transition processing is continued after normal processing. In this case, the actual position, which is the position on the medium of the dot that can be formed by the nozzle, is calculated, and the lower end transition processing nozzle that can form a dot at a position that matches the virtual position is set as the used nozzle, and the pixel data A printer that creates print data by assigning to the used nozzles.
[Selection] Figure 13

Description

  The present invention relates to a printing apparatus, a program, and a printing method.

  As one of printing apparatuses, an image forming operation for forming an image by ejecting ink from a nozzle to a medium while a head provided with a nozzle for ejecting ink moves in the moving direction, and a relative position of the head and the medium An ink jet printer (hereinafter referred to as a printer) that repeats the operation of moving in a direction crossing the moving direction is known.

  The printer performs printing based on the print data created by the printer driver. In creating print data, the printer driver extracts pixel data to be assigned to each nozzle from matrix image data composed of a plurality of pixel data, and rearranges the pixel data in the order of assignment to each nozzle (nozzle assignment) Process). Therefore, for each image forming operation, a process of associating the nozzle with the position of the raster line (dot row along the moving direction) to be formed by the nozzle is performed.

JP 2006-264054 A

For example, in order to make the arrangement of dot rows formed by overlap nozzles (nozzles that perform a part of the functions performed by one nozzle) in the center and upper and lower ends of the medium the same as normal processing There is a printer that performs a printing method in which a transition process is provided between upper and lower end processes.
Since the print data creation method described in Patent Document 1 is a process corresponding to a printing method without a transition process between the normal process and the lower end process, printing in which a transition process is provided between the normal process and the lower end process. The method cannot be applied to the creation of print data.
Therefore, an object of the present invention is to create print data of a printing method having a transition process between the normal process and the lower end process.

The main invention for solving the above problems is: (A) a head including a nozzle row in which nozzles that eject ink to a medium are arranged in a predetermined direction; and (B) the medium and the head based on print data. An image forming operation for ejecting ink from the nozzles while relatively moving the relative position in a direction crossing the predetermined direction; and an operation for moving the relative position of the head with respect to the medium in one direction of the predetermined direction; (B1) A top end process for printing an upper end portion that is an end portion on the other direction side in the predetermined direction of the medium and a center portion in the predetermined direction of the medium are normally printed. Before the medium and between the normal process and the lower end process of printing the lower end part which is the end of the one direction side of the medium in the predetermined direction. Print data of a printing method for performing a transition process in which the relative movement amount of the head in the predetermined direction is not less than the relative movement amount of the upper end process and the lower end process and not more than the relative movement amount of the normal process (B2) When the normal process is continued instead of the lower end transition process, which is the transition process between the normal process and the lower end process, can be formed by the nozzle after the normal process. An actual position that is a position on the medium of dots that can be formed by the nozzles when a virtual position that is a position on the medium is calculated and the lower end transition process is continued after the normal process The nozzle of the lower end transition process capable of forming a dot at a position coinciding with the virtual position is calculated by comparing the virtual position with the actual position. A printing apparatus comprising: (C3) a control unit configured to set the used nozzle to be used, and (B3) assigning pixel data constituting image data to the used nozzle to create the print data; is there.
Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

1 is an overall configuration block diagram of a printer. 2A is a schematic sectional view of the printer, and FIG. 2B is a schematic top view of the printer. It is a figure which shows arrangement | positioning of the some head in a head unit. It is a figure explaining a virtual head. It is a figure explaining the printing method of a comparative example. It is the printing method of this embodiment. It is a figure which shows a virtual head information table. 8A to 8D are diagrams for explaining the virtual head table creation process for pass 1 of the upper end process. It is a figure explaining the creation processing of the virtual head table of pass 1 of upper end processing. FIG. 10A to FIG. 10E are diagrams for explaining the virtual head table creation process of pass 5 of the upper edge transition process. It is a figure explaining the creation processing of the virtual head table of pass 7 of normal processing. It is a figure explaining a dummy table. FIG. 13A to FIG. 13C are diagrams showing how the nozzles used in the scheduling table are determined. FIG. 14A to FIG. 14D are diagrams showing a state in which the lower POL nozzle of the lower end transition process is determined. FIG. 15A and FIG. 15B are diagrams for explaining the virtual head table creation process of pass 14 of the lower edge transition process. FIG. 16A to FIG. 16E are diagrams for explaining a scheduling table for lower end processing. FIG. 17A and FIG. 17B are diagrams for explaining the virtual head table creation process of pass 16 of the lower end process. FIG. 18A is a diagram for explaining a parameter table related to the head configuration, and FIG. 18B is a diagram for explaining processing for replacing a virtual head table with an actual head table. FIG. 19A is a diagram showing image data (image data after halftone processing) in which pixels are arranged in a matrix, and FIG. 19B is a diagram showing raster data rearranged for each head 41. It is a figure which shows the printing method of another comparative example without a transfer process. It is a figure which shows another printing method of this embodiment. FIG. 22A shows a dummy table used in the lower end transition process, and FIG. 22B shows a dummy table used in the lower end process.

=== Summary of disclosure ===
At least the following will become apparent from the description of the present specification and the accompanying drawings.

That is, (A) a head including a nozzle row in which nozzles that eject ink to a medium are arranged in a predetermined direction; and (B) a relative position of the medium and the head intersects the predetermined direction based on print data. A controller that repeatedly executes an image forming operation for ejecting ink from the nozzle and an operation for moving the relative position of the head with respect to the medium in one direction of the predetermined direction while relatively moving in the direction; (B1) Between the upper end process for printing the upper end part which is the end part on the other direction side of the medium in the predetermined direction and the normal process for printing the center part in the predetermined direction of the medium, and the normal The relative movement of the head in the predetermined direction with respect to the medium between the processing and the lower end processing for printing the lower end that is the end on the one direction side in the predetermined direction of the medium. When creating print data of a printing method for performing a transition process in which the amount is greater than or equal to the relative movement amount of the upper end process and the lower end process and less than or equal to the relative movement amount of the normal process, (B2 ) Positions on the medium of dots that can be formed by the nozzle when the normal process is continued instead of the lower end transition process, which is the transition process between the normal process and the lower end process, after the normal process. When the lower end transition process is continued after the normal process, an actual position that is a position on the medium of dots that can be formed by the nozzle is calculated, and the virtual position is calculated. And the actual position, set the nozzle of the lower end transition process that can form a dot at a position that coincides with the virtual position, the use nozzle used for printing, The pixel data constituting the B3) image data, are assigned to the used nozzles, and a control unit for creating the print data, a printing apparatus characterized by having (C).
According to such a printing apparatus, it is possible to create print data of a printing method having a transition process between the normal process and the lower end process.

In this printing apparatus, the control unit is configured to perform an upper end process that is the transition process between the upper end process and the normal process rather than the nozzle of the upper end process that can form dots at a certain position on the medium. The nozzle for transition processing, wherein the nozzle capable of forming dots at the certain position is preferentially set as the used nozzle, and the nozzle for top transition processing capable of forming dots at the certain position Rather than setting the nozzle for normal processing capable of forming dots at the certain position as the nozzle to be used preferentially, the nozzle for lower end processing capable of forming dots at another position on the medium Rather than setting the nozzle in the lower end transition process capable of forming dots at the other position as the use nozzle, the nozzle of the lower end transition process capable of forming dots at the other position. Than nozzle, setting the nozzles capable of forming the usual processing dots on the use nozzles preferentially to said other position.
According to such a printing apparatus, it is possible to prevent double dots from being formed, and it is possible to form dot rows that are continuously arranged in a predetermined direction using different nozzles.

In this printing apparatus, when the normal process is continued instead of the lower end transition process after the normal process, the virtual position that is a position on the medium of dots that can be formed by the nozzles is displayed as a table. The virtual position that coincides with the position on the medium of the dot formed by the nozzle used in the lower end transition process among the virtual positions stored in the table is deleted from the table. Thereafter, the virtual position stored in the table is compared with the position of the dot that can be formed by the nozzle in the lower end processing on the medium, and a dot can be formed at a position that matches the virtual position. The nozzle for the lower end process is set as the used nozzle.
According to such a printing apparatus, dots that cannot be formed by the normal process and the lower end transition process can be formed by the lower end process.

This printing apparatus is a printing method for performing the transition process between the upper end process and the normal process, and between the normal process and the lower end process, and the predetermined number of the nozzle rows A dot row along the intersecting direction between an upper end nozzle that is an end nozzle on the other direction side in the direction and a lower end nozzle that is an end nozzle on the one direction side in the predetermined direction of the nozzle row. When creating print data of a printing method to be formed, the virtual position that matches the position on the medium of the dots formed by the nozzles used in the lower end transition process among the virtual positions stored in the table The position of the dot formed by the lower end nozzle in the lower end transition process on the medium is stored in the table after the position is deleted from the table. Setting the active nozzles of the said possible form dots at the same position as the position on the medium bottom processing of dots formed by the lower nozzle of the lower end transition process to the upper end nozzle.
According to such a printing apparatus, it is possible to set the nozzle for the lower end processing that forms the dot row together with the lower end nozzle for the lower end transition processing as the use nozzle (upper end nozzle).

In this printing apparatus, the position on the medium of dots that can be formed by the nozzle in an image forming operation of the upper end transition process that is the transition process between the upper end process and the normal process, and the upper end transition The upper end transition process capable of comparing dots on the medium that can be formed by the nozzles in the image forming operation after the certain image forming operation of the processing and forming dots at the matching positions. The nozzle of the certain image forming operation is set to an unused nozzle that is not used for printing.
According to such a printing apparatus, it is possible to prevent double dots from being formed.

In this printing apparatus, a plurality of the heads are arranged in the predetermined direction, and the number of nozzles that is the number of the nozzles belonging to the nozzle row included in each of the heads, and the plurality of heads in the predetermined direction. The control unit stores a plurality of heads as one virtual head, the nozzle of the virtual head used for printing during a certain image forming operation, and the or by the nozzle. The positions of the dots formed during the image forming operation on the medium correspond to each other, and the nozzles of the actual head correspond to the nozzles of the virtual head based on the number of nozzles and the head interval. In addition, the positions of the dots formed during the certain image forming operation by the nozzles of the actual head are acquired on the medium, and the acquired positions are obtained. Zui with the given image forming operation of the pixel data to be used for printing to be extracted from the image data, to create the print data for implementing the given image forming operation.
According to such a printing apparatus, it is possible to create print data for a printer having a plurality of heads.

Further, (A) the ink is ejected from the nozzle while relatively moving the relative position between the head having the nozzle row in which the nozzles for ejecting the ink are arranged in a predetermined direction with respect to the medium and the medium in a direction intersecting the predetermined direction. A program for causing a computer to create print data of a printing apparatus that repeatedly executes an image forming operation to be ejected and an operation of moving the relative position of the head with respect to the medium in one direction of the predetermined direction. (B) between the upper end process for printing the upper end part, which is the end part on the other direction side of the medium in the predetermined direction, and the normal process for printing the central part of the medium in the predetermined direction; During the processing and the lower end processing for printing the lower end which is the end of the one direction side in the predetermined direction of the medium, the head of the head with respect to the medium Create print data of a printing method for performing a transition process in which a relative movement amount in a fixed direction is equal to or greater than the relative movement amount of the upper end process and the lower end process and equal to or less than the relative movement amount of the normal process. (C) When the normal process is continued instead of the lower end transition process, which is the transition process between the normal process and the lower end process, after the normal process, the dots that can be formed by the nozzle Calculating a virtual position that is a position on the medium; and (D) an actual position that is a position on the medium of dots that can be formed by the nozzle when the lower end transition process is continued after the normal process. And (E) comparing the virtual position with the actual position, and comparing the virtual position with the actual position, and forming the dot at a position that coincides with the virtual position. Set the print nozzle to the use nozzle used for printing, (F) assign the pixel data constituting the image data to the use nozzle, create the print data, and execute (G) on the computer It is a program to make it.
According to such a program, it is possible to create print data of a printing method having a transition process between the normal process and the lower end process.

Further, (A) the ink is ejected from the nozzle while relatively moving the relative position between the head having the nozzle row in which the nozzles for ejecting the ink are arranged in a predetermined direction with respect to the medium and the medium in a direction intersecting the predetermined direction. A printing apparatus that repeatedly executes an image forming operation to be ejected and an operation of moving the relative position of the head with respect to the medium in one direction of the predetermined direction is (B) another direction in the predetermined direction of the medium. Between the upper end process for printing the upper end part, which is the side end part, and the normal process for printing the center part in the predetermined direction of the medium, and the one direction side in the predetermined direction of the normal process and the medium Relative to the medium, the relative movement amount of the head in the predetermined direction relative to the medium is the relative value of the upper end process and the lower end process. A printing method for performing a transition process that is greater than or equal to a movement amount and less than or equal to the relative movement amount of the normal process, wherein (C) the transition between the normal process and the lower end process after the normal process. When the normal process is continued instead of the lower end transition process that is a process, a virtual position that is a position on the medium of dots that can be formed by the nozzle is calculated, and the lower end transition is performed after the normal process. When the processing is continued, calculating an actual position that is a position on the medium of dots that can be formed by the nozzle, comparing the virtual position with the actual position, and The nozzle of the lower end transition process capable of forming dots at the matching position is set as a use nozzle used for printing, and pixel data constituting image data is set as the use nozzle. Based on the print data created by allocating Le, a printing method characterized by having a ejecting ink from the nozzle.
According to such a printing method, for example, in the upper and lower end processing, dot rows continuously arranged in a predetermined direction can be formed with different nozzles, and image quality deterioration can be suppressed.

=== About the printing system ===
FIG. 1 is a block diagram of the overall configuration of the printer 1, FIG. 2A is a schematic cross-sectional view of the printer 1, and FIG. 2B is a schematic top view of the printer 1. Hereinafter, an embodiment will be described by taking a printing system in which an inkjet printer (printer 1) and a computer 60 are connected as an example. The computer 60 is communicably connected to the printer 1 and outputs print data for printing an image to the printer 1.

  The controller 10 is a control unit for controlling the printer 1. The interface unit 11 is for transmitting and receiving data between the computer 60 and the printer 1. The CPU 12 is an arithmetic processing unit for controlling the entire printer 1. The memory 13 is for securing an area for storing a program of the CPU 12, a work area, and the like. The CPU 12 controls each unit by the unit control circuit 14. The detector group 50 monitors the situation in the printer 1, and the controller 10 controls each unit based on the detection result.

  The transport unit 20 transports the medium S from the upstream side to the downstream side in the direction in which the medium S continues (transport direction). The roll-shaped medium S before printing is supplied to the printing area by the conveyance roller 21 driven by a motor, and then the printed medium S is wound into a roll shape by a winding mechanism. Note that the medium S can be held at a predetermined position by vacuum suction of the medium located in the print area during printing.

  The drive unit 30 freely moves the head unit 40 in the X direction corresponding to the transport direction of the medium S and the Y direction corresponding to the paper width direction of the medium S. The drive unit 30 includes an X-axis stage 31 that moves the head unit 40 in the X direction, a Y-axis stage 32 that moves the head unit 40 in the Y direction, and a motor (not shown) that moves them. Yes.

  The head unit 40 is for forming an image and has a plurality of heads 41. On the lower surface of the head 41, a plurality of nozzles that are ink discharge portions are provided, and each nozzle is provided with a pressure chamber filled with ink. The ink ejection method from the nozzle may be a piezo method in which ink is ejected by applying a voltage to the drive element (piezo element) to expand and contract the pressure chamber, or bubbles are generated in the nozzle using a heating element. Alternatively, a thermal method may be used in which ink is discharged and ink is ejected by the bubbles.

  FIG. 3 is a diagram showing the arrangement of the plurality of heads 41 in the head unit 40. In addition, the arrangement of the head 41 and the nozzle is virtually seen from the upper surface of the head unit 40. Here, it is assumed that the head unit 40 includes fifteen heads 41 (1) to 41 (15). On the nozzle surface of each head 41, a yellow nozzle row Y for discharging yellow ink, a magenta nozzle row M for discharging magenta ink, a cyan nozzle row C for discharging cyan ink, and a black nozzle row for discharging black ink. K is formed. Each nozzle row includes 360 nozzles, and the 360 nozzles are aligned at a constant interval (360 dpi) in the paper width direction. As shown in the drawing, small numbers (positive integer numbers) are assigned in order from the nozzles on the back side in the paper width direction (# 1 to # 360).

  Due to manufacturing problems and the like, the plurality of heads 41 are arranged in a staggered manner in the head unit 40. That is, the heads (eg, 41 (1) and 41 (2)) adjacent in the paper width direction are arranged so as to be shifted in the transport direction. For the sake of explanation, the first head 41 (1), the second head 41 (2),...

  And ten nozzles at the ends of two heads (for example, 41 (1) and 41 (2)) adjacent in the paper width direction overlap. Specifically, of the two heads (41 (1), 41 (2)) adjacent in the paper width direction, ten nozzles # 351 to 351 at the front end of the back head (41 (1)). The position in the paper width direction of # 360 is the same as the position in the paper width direction of the ten nozzles # 1 to # 10 at the back end of the front head (41 (2)). Therefore, in the head unit 40, a plurality of nozzles are arranged at a constant interval (360 dpi) in the paper width direction over the width of the head unit 40.

  Next, a printing procedure will be described. First, the medium S is supplied to the printing area by the transport unit 20. Then, the X-axis stage 31 moves the head unit 40 in the X direction (corresponding to the medium transport direction and the intersecting direction) while discharging ink from the nozzles, and the Y-axis stage 32 causes the X-axis stage 31 to move. The operation of moving the head unit 40 in the Y direction (corresponding to the paper width direction and the predetermined direction) is repeated. As a result, dots can be formed by a subsequent image forming operation at positions different from the dot positions formed by the previous image forming operation, and a two-dimensional image is printed on the medium S located in the printing area. can do. When printing on the medium S located in the print area is completed in this way, the medium portion not yet printed by the transport unit 20 is supplied to the print area, and an image is printed on the medium in the print area. In the following description, one image forming operation (an operation for forming an image while moving the head unit 40 in the X direction) is referred to as “pass”.

=== Virtual head ===
FIG. 4 is a diagram illustrating a virtual head in which two heads 41 are regarded as one head. As shown in FIG. 3, the printer 1 includes 15 heads 41, but the following description will be made using two heads 41 for the sake of simplicity. In addition, the number of nozzle rows included in each head 41 is 1, and the number of nozzles belonging to the nozzle rows is 7 (# 1 to # 7). Then, two nozzles # 6 and # 7 on the front side in the Y direction of the first head 41 (1) (corresponding to one direction side) and the back side in the Y direction of the second head 41 (2) (other directions). It is assumed that the two nozzles # 1 and # 2 are equivalent to each other.

  Here, a head that is regarded as one large head by combining the first head 41 (1) and the second head 41 (2) is referred to as a “virtual head”. Since the number of nozzles of each head 41 is seven and the number of overlapping nozzles is two, the number of nozzles belonging to the virtual head is twelve (## 1 to ## 12). For example, the virtual head nozzle ## 1 corresponds to the nozzle # 1 of the first head 41 (1), the virtual head nozzle ## 6 corresponds to the nozzle # 6 of the first head 41 (1), and the first Corresponds to nozzle # 1 of two heads 41 (2). In the present embodiment, only one of the two overlapping nozzles of the first head 41 (1) and the second head 41 (2) is used. For example, the nozzle # 6 of the first head 41 (1) is used, but the nozzle # 1 of the second head 41 (2) corresponding thereto is not used, and the nozzle # 7 of the first head 41 (1) is used. Although not, nozzle # 2 of the 2nd head 41 (2) corresponding to it is used.

=== Printing Method of Comparative Example ===
FIG. 5 is a diagram illustrating a printing method of a comparative example. FIG. 5 is a diagram showing the positional relationship of the virtual head (FIG. 4) in each path. In the figure, the nozzle pitch is “2D” (360 dpi in FIG. 3), and the raster line (dot rows along the X direction) arranged in the Y direction (hereinafter referred to as “inter-nozzle pitch”) corresponds to the printing resolution in the Y direction. ) Is “D”. In the printing method of the comparative example, “upper end processing” is performed at the start of printing, “normal processing” is performed thereafter, and “lower end processing” is performed at the end of printing. The upper end process is a process of printing the end (upper end) of the medium in the Y direction, and the lower end process is a process of printing the end (lower end) of the medium in the Y direction. While the transport amount of the head unit 40 in the normal process to the front side in the Y direction is “5D”, the transport amount of the head unit 40 in the upper end process and the lower end process is “D”, which is smaller than that in the normal process. . Therefore, the amount of protrusion of the head unit 40 with respect to the medium can be reduced at the start and end of printing. In FIG. 5, the upper end process corresponds to pass 1 to pass 4, and the lower end process corresponds to pass 13 to pass 16.

  “Horizontal position (1 or 2)” is set for each pass. A unit area on a medium on which one dot is formed is called a “pixel area”, and the pixel area corresponds to pixel data. The horizontal position is information indicating the position of the pixel area to be assigned to the corresponding path among the pixel areas arranged in the X direction. That is, in the pass where the horizontal position is set to 1, dots are formed in the pixel area where the horizontal position is 1, and in the pass where the horizontal position is set to 2, dots are formed in the pixel area where the horizontal position is 2. . In FIG. 5, the virtual head of the path whose horizontal position is 1 is indicated by diagonal lines, and the virtual head of the path whose horizontal position is 2 is indicated by white.

  Further, in the printing method of the comparative example, the end nozzles on the rear side and the front side in the Y direction of the virtual head are configured to perform the same function as the other one nozzle (so-called partial overlap printing). That is, a nozzle that is not an end nozzle with respect to a pixel area at a certain horizontal position forms dots with one nozzle, whereas an end nozzle with respect to a pixel area at the same horizontal position is on the far side in the Y direction and in front. Dots are formed by the two end nozzles on the side. In the virtual head, the end nozzle on the back side in the Y direction is “upper POL nozzle (equivalent to overlap nozzle / upper nozzle)”, and the end nozzle on the front side in the Y direction is “lower POL nozzle (overlap nozzle / lower end nozzle)” The upper POL nozzle and the lower POL nozzle perform the same function as the other one nozzle. In normal processing, the two end nozzles (## 1, ## 2) on the back side in the Y direction of the virtual head are defined as “upper POL nozzles”, and the two end nozzles (on the front side in the Y direction of the virtual head) ( ## 11, ## 12) are defined as “lower POL nozzles”. In FIG. 5, the upper POL nozzle is indicated by “Δ”, the lower POL nozzle is indicated by “□”, and the other nozzles (normal nozzles) are indicated by “◯”. In FIG. 5, “used nozzles” used for printing are indicated by black nozzles (for example, ●), and “unused nozzles” not used for printing are indicated by white-colored nozzles (for example, ◯).

  Further, the position in the Y direction of the raster line formed on the medium is referred to as “raster position”. The raster lines constituting the image are numbered in order from the back in the Y direction. In the printing method of the comparative example, the print start position is the 0th raster position (L0), and the print end position is the 64th raster position (L64).

  In the printing method of the comparative example, for example, the normal nozzle (●) in pass 7 and the normal nozzle (●) in pass 9 are associated with the 29th raster position (L29). The horizontal position of pass 7 is 2, and the horizontal position of pass 9 is 1. As a result, a dot is formed in the pixel area whose horizontal position is 2 by the normal nozzle in pass 7, and a dot is formed in the pixel area whose horizontal position is 1 by the normal nozzle in pass 9.

  On the other hand, the lower POL nozzle (■) in pass 6, the normal nozzle (●) in pass 8, and the upper POL nozzle (▲) in pass 10 are associated with the 28th raster position (L28). The horizontal position of pass 6 and pass 10 is the same 2, and the horizontal position of pass 8 is 1. As a result, the lower POL nozzle in pass 6 and the upper POL nozzle in pass 10 form dots in the pixel area whose horizontal position is 2, and the normal nozzle in pass 8 forms dots in the pixel area whose horizontal position is 1. The

  As described above, in the printing method of the comparative example, a raster line (for example, L29, hereinafter referred to as “normal raster”) in which dots are formed by one nozzle for a pixel region having a horizontal position of 1 or 2, and the horizontal position is Raster lines (for example, L28, hereinafter referred to as “POL raster”) formed by two nozzles are mixed for one or two pixel regions. In the POL raster, even if one nozzle causes a discharge failure and cannot form a dot, the other nozzle forms a dot. For this reason, it is possible to suppress the formation of streaks along the X direction on the image due to defective ejection nozzles.

  In the normal process, the nozzles ## 1 and ## 2 of the virtual head are set to the upper POL nozzle (▲), and the nozzles ## 11 and ## 12 are set to the lower POL nozzle (■). Therefore, the POL raster and the regular raster are regularly arranged in an area printed by the normal process (hereinafter referred to as a normal print area). For the sake of explanation, in FIG. 5, a raster line corresponding to the transport amount 5D of the head unit 40 during normal processing, that is, five raster lines is defined as one block. In the figure, each block is surrounded by a thick line. For example, at the 28th to 32nd raster positions, the POL raster, normal raster, POL raster, normal raster, and normal raster are arranged in this order from the back in the Y direction. The POL raster and normal raster are arranged in the same order in the other thick frames.

  However, the raster lines at the start and end of printing are not arranged in the order of arrangement of the POL raster and the normal raster in the normal print area. For example, the 0th raster line at the start of printing is the third raster line from the front side in the Y direction in the block. Therefore, in order to arrange the POL raster and the normal raster with the same regularity as the normal printing area, the 0th raster line needs to be a POL raster. However, in the printing method of the comparative example, the 0th raster line is a normal raster.

  The 63rd raster line at the end of printing is the first raster line from the back in the Y direction in the block. Therefore, in order to arrange the POL raster and the normal raster with the same regularity as the normal printing area, the 63rd raster line needs to be a POL raster. However, in the printing method of the comparative example, the 63rd raster line is a normal raster.

  This is because the upper POL nozzle and the lower POL nozzle are not set in the upper end process and the lower end process, but the upper POL nozzle (▲) in the normal process is set as the lower POL nozzle (■). This is because the lower end processing nozzle, which is the opposite of the normal processing lower POL nozzle (■), is set to the upper POL nozzle (▲). A nozzle that is compatible with a certain nozzle is a nozzle that is associated with the same position as the raster position and the horizontal position associated with the certain nozzle.

  As described above, in the printing method of the comparative example, the area printed by the upper end / lower end process does not follow the regularity of the arrangement order of the POL raster and the normal raster in the normal print area. In other words, in the upper end / lower end process and the normal process, the upper POL nozzle and the lower POL nozzle are not associated with the raster position at a constant cycle. In this case, there is a difference in image color between an area with regularity in the arrangement order of the POL raster and the normal raster (normal printing area) and an area with no regularity (upper and lower end printing areas), and the image quality deteriorates. There is a fear.

=== Printing Method of the Present Embodiment ===
FIG. 6 shows a printing method according to this embodiment. Similarly to the printing method of the comparative example (FIG. 5), also in the printing method of the present embodiment (FIG. 6), the nozzle pitch is 2D and the nozzle pitch is D. The transport amount of the head unit 40 for normal processing is set to “5D”, and the transport amount of the head unit 40 for upper end / lower end processing is set to “D”, which is shorter than that during normal processing. By doing so, it is possible to suppress the jumping amount of the head unit 40 with respect to the medium at the start and end of printing.

  In the printing method of the comparative example, the normal process is performed immediately after the upper end process, and the lower end process is performed immediately after the normal process. On the other hand, in the printing method of the present embodiment, a transition process (pass 5 to pass 6) is provided between the upper end process and the normal process, and a transition process (pass 14 to pass 15) is performed between the normal process and the lower end process. Is provided. The carry amount “3D” of the head unit 40 in the transition process is a carry amount between the carry amount 5D of the head unit 40 in the normal process and the carry amount D of the head unit 40 in the upper end / lower end process. In principle, the transfer amount of the transition process is a transfer amount between the transfer amount of the normal process and the transfer amount of the upper end / lower end process. However, depending on the printing conditions, the transport amount for the upper end / lower end process and the transport amount for the transition process may be the same, or the transport amount for the normal process and the transport amount for the transition process may be the same. That is, it can be said that the transfer amount of the transition process is not less than the transfer amount of the upper end / lower end process and not more than the transfer amount of the normal process, and at least one of the transfer amount of the upper end / lower end process and the transfer amount of the normal process. It's different.

  In the normal processing of the printing method of the present embodiment, the nozzles ## 1 and ## 2 of the virtual head are set to the upper POL nozzle (▲), and the nozzles ## 11 and ## 12 are set to the lower POL nozzle (■). Set to. On the other hand, in the upper end process, the upper POL nozzle (▲) is not set, and the upper end process nozzle that is compatible with the upper POL nozzle (▲) in the subsequent pass is set as the lower POL nozzle (■). For example, nozzles ## 7 and ## 8 in pass 3 of the upper end process are nozzles that are compatible with nozzles ## 1 and ## 2 in pass 7 of the normal process, and are set as the lower POL nozzle (■). Yes. On the other hand, in the lower end processing, the lower POL nozzle (■) is not set, and the lower end processing nozzle that is compatible with the lower POL nozzle (■) in the previous pass is set as the upper POL nozzle (▲).

  In the upper end side transition processing (hereinafter referred to as upper end transition processing), the upper POL nozzle (▲) is set, and the upper POL nozzle (▲) of the normal processing is the lower POL nozzle. Set to (■). In the lower end side transition processing (hereinafter referred to as lower end transition processing), the lower POL nozzle (■) is set, and the lower end transition processing nozzle that is compatible with the lower POL nozzle (■) in the normal processing is set as the upper POL nozzle (▲). ). Then, an upper end processing nozzle (for example, nozzle ## 4 for pass 1) which is the opposite of the upper POL nozzle (for example, nozzle ## 1 for pass 5) set in the upper end transition processing is set as the lower POL nozzle, and the lower end transition is performed. The lower end processing nozzle (for example, nozzle ## 8 for pass 18), which is the opposite of the lower POL nozzle (for example, nozzle ## 11 for pass 14) set in the processing, is set as the upper POL nozzle.

  As a result, in the printing method of the present embodiment, the normal raster and the POL raster in the block (L0 to L3) at the start of printing surrounded by a thick frame in FIG. It can be arranged in the order of POL raster. Specifically, in both the block at the start of printing and the block in the normal printing area, the bottom raster line and the second raster line from the bottom are normal rasters, and the third raster line from the bottom is the POL raster. Become. Further, the normal raster and the POL raster in the blocks (L63 to L64) at the end of printing can be arranged in the order of the normal raster and the POL raster in the block of the normal print area. Specifically, in both the block at the end of printing and the block in the normal printing area, the top raster line is the POL raster, and the second raster line from the top is the normal raster.

  That is, according to the printing method of the present embodiment, the POL raster and the normal raster are arranged according to regularity in the entire image area from the print start position (L0) to the print end position (L64). In other words, the upper POL nozzle and the lower POL nozzle are associated with the raster position at a constant cycle. Therefore, it is possible to prevent the color from being different depending on the position of the image, and to suppress image quality deterioration.

  In the printing method of the comparative example (FIG. 5), since there is no transition process, only two nozzles can be associated with the raster positions at the start and end of printing. For example, the nozzle ## 3 for pass 2 and the nozzle ## 2 for pass 4 are associated with the 0th raster position. Therefore, in the printing method of the comparative example, the raster line at the start and end of printing cannot be a POL raster.

  Therefore, in the printing method of the present embodiment, the upper end transition process is provided between the upper end process and the normal process, the lower end shift process is provided between the normal process and the lower end process, and some rasters at the start of printing and at the end of printing. Three nozzles can be associated with the position. Further, the upper POL nozzle (▲) is set in the upper end transition process, and the lower POL nozzle (■) is set in the lower end transition process. By doing so, at the start of printing and at the end of printing, the POL raster and the normal raster can be formed according to the same regularity as that during the normal processing.

=== Printer driver ===
The computer 60 is installed with a program (printer driver) for converting image data output from the application program into print data and outputting the print data to the printer 1. The printer driver is recorded on a recording medium (computer-readable recording medium) such as a CD-ROM or can be downloaded to a computer via the Internet. The printer driver executes the following processing using hardware resources of the computer 60 according to the program stored in the memory.

  The print data creation flow will be described below. First, the printer driver performs resolution conversion processing. The resolution conversion process is a process for converting image data output from an application program into a resolution for printing on a medium. Note that the image data after the resolution conversion process is multi-gradation (for example, 256 gradations) RGB data represented by an RGB color space. The image data is composed of pixel data relating to the pixels constituting the print image.

  Next, the printer driver performs a color conversion process. The color conversion process is a process of converting RGB data into CMYK data represented by a CMYK color space in accordance with the color of ink that the printer 1 has so that the printer 1 can perform printing. Thereafter, the printer driver performs halftone processing. The halftone process is a process of converting high gradation number data into gradation number data that can be formed by the printer 1. For example, data indicating 256 gradations is converted into 2-bit data indicating 4 gradations by halftone processing. Pixel data after halftone processing is data relating to dots formed in the pixel region. For example, in the case of pixel data of four gradations, “large dot formation”, “medium dot formation”, “small dot formation”, or “no dot” is indicated.

  Finally, the printer driver performs “nozzle assignment processing”. The nozzle allocation process is a process of rearranging image data composed of pixel data arranged in a matrix in the order of data to be transmitted to the printer 1. That is, in the nozzle allocation process, pixel data to be allocated to each nozzle is determined for each pass (details will be described later). Then, the printer driver transmits the print data created through these processes to the printer 1. The printer 1 performs printing based on the received print data.

=== Nozzle assignment processing ===
FIG. 7 is a diagram showing a virtual head information table. The printer driver performs a process of creating a virtual head table and an extraction / sorting process as the nozzle allocation process. For this purpose, the printer driver refers to the virtual head information table of FIG. The virtual head information table is a table in which parameters related to printing are stored. Each table stores the transport amount of the head unit 40, the start nozzle and the end nozzle, the start raster position and the end raster position, and the horizontal position. Note that “start nozzle” and “end nozzle” indicate the range of nozzles that can be used for printing, and “start raster position” indicates the nozzle ## of the virtual head in the start pass of each process (for example, upper end process). 1 is the corresponding raster position, and the “end raster position” is the raster position corresponding to the nozzle ## 1 of the virtual head in the end pass of each process. These values vary depending on the print mode and paper size. This virtual head information table may be stored in the memory 13 on the printer 1 side, or may be stored in the memory on the computer 60 side when the printer driver is installed in the computer 60.

  In order to extract pixel data to be used for printing for each pass from the image data and rearrange the pixel data in the order of assignment to each nozzle, the printer driver firstly, for each pass, each nozzle ## 1 of the virtual head. ~ ## 12 determines whether or not the nozzle is used for printing, and the nozzle used for printing determines the raster position where the dot is to be formed. Therefore, in this embodiment, the printer driver creates a “virtual head table (described later)” for each pass. Hereinafter, a method of creating a virtual head table for each process (upper end process, upper end shift process, normal process, lower end shift process, and lower end process) related to the printing method of FIG. 6 will be described.

<Upper end processing>
FIG. 8A to FIG. 8D and FIG. 9 are diagrams for explaining the virtual head table creation processing for pass 1 of the top end processing. The printer driver creates a virtual head table for each pass in order from the top end pass 1. As shown in FIG. 8A, the virtual head table stores the head position, the horizontal position, and the nozzle types of the nozzles ## 1 to ## 12 of the virtual head. The “head position” is a raster position to which the nozzle ## 1 of the virtual head in the corresponding path corresponds. The “horizontal position” indicates the position in the X direction of the pixel area where dots are formed in the corresponding pass. “Nozzle type” indicates whether each of the nozzles ## 1 to ## 12 is a “use nozzle” used for printing or a “non-use nozzle” that is not used for printing. Further, in the printing method in which the upper POL nozzle and the lower POL nozzle are set as in the printing method shown in FIG. 6, it is indicated that the nozzle type is the upper POL nozzle or the lower POL nozzle.

  Hereinafter, the creation of the virtual head table for pass 1 will be described as an example. The printer driver refers to the virtual head information table regarding the upper end process in FIG. 7 and determines the head position and the horizontal position of pass 1. The head position of pass 1 is “−6” because it corresponds to the start raster position of the virtual head information. Therefore, the printer driver stores the head position in the virtual head table of pass 1 as -6 (FIG. 8A). In the virtual head information, the horizontal position is stored as “2, 1, 1, 2”. The horizontal position may be assigned in order from the smallest path, and the horizontal position of the path 1 is “2”. Therefore, the printer driver stores the horizontal position in the virtual head table as 2. The head position after pass 2 can be calculated by “start raster position + (transport amount / nozzle pitch) × (corresponding pass−pass 1)”.

  Next, the printer driver refers to the start nozzle (## 1) and end nozzle (## 12) in the virtual head information table related to the upper end process, and determines that nozzles ## 1 to ## 12 are used nozzles. To do. Therefore, the printer driver stores the nozzle types of all the nozzles ## 1 to ## 12 as “used nozzles” in the virtual head table, as shown in the center diagram of FIG. 8A.

  Since the head position of pass 1 is located behind the print start position (0th raster position) in the Y direction, the printer driver determines the nozzle to which the raster position outside the print area is assigned as “unused nozzle”. . For example, the start nozzle in the print area can be calculated by “(print start position−head position) / number of pitches between nozzles + 1”. The number of pitches between nozzles is the number of raster lines located within the nozzle pitch (2D). The start nozzle in the printing area in pass 1 is calculated as “## 4 (= (0 − (− 6)) / 2 + 1)”. Therefore, the printer driver changes the nozzle type of the nozzles ## 1 to ## 3 to “unused nozzle” as shown in the right diagram of FIG. 8A. In the virtual head of pass 1 in the left diagram of FIG. 8A, the unused nozzle is indicated by a white circle (◯) and the used nozzle is indicated by a black circle (●).

  In the printing method shown in FIG. 6, priority is given to dots that can be formed in subsequent passes (upper end transition processing and normal processing) over dots that can be formed in a certain pass of upper end processing. That is, among nozzles associated with the same dot formation position, nozzles for subsequent processing (upper end transition processing and normal processing nozzles) are preferentially set as used nozzles over the upper end processing nozzles. Therefore, the printer driver performs a comparison process between the raster position and horizontal position associated with the nozzle of a certain pass in the upper end process and the raster position and horizontal position associated with the nozzle of the subsequent pass, and the positions match. The upper end processing nozzle is determined as an unused nozzle. By doing so, it is possible to prevent double dots from being formed.

  As shown in FIG. 8B to FIG. 8D, the printer driver firstly uses the raster positions and horizontal positions associated with the used nozzles of the corresponding pass 1 and the used nozzles of passes 2 to 4 in the upper end processing subsequent to pass 1. A comparison is made with each raster position and horizontal position associated with. The printer driver can determine the range of the upper end process based on “end raster position (−3)” in the virtual head information table (FIG. 7) regarding the upper end process. In addition, the printer driver can calculate each raster position associated with the used nozzles in passes 2 to 4 in the subsequent upper end processing based on the head position and the number of nozzle pitches in each pass.

  As shown in FIG. 8B, the raster positions associated with the used nozzles in pass 1 do not match the raster positions associated with the used nozzles in pass 2, and the horizontal positions do not match in pass 1 and pass 2. . Therefore, the virtual head table of pass 1 does not change from the right diagram of FIG. 8A. Further, as shown in FIG. 8C, the raster positions associated with the used nozzles in pass 1 and the raster positions associated with the used nozzles in pass 3 match, but the horizontal positions do not match in pass 1 and pass 3. . Therefore, the virtual head table of pass 1 does not change from the right diagram of FIG. 8A. As illustrated in FIG. 8D, the raster positions associated with the used nozzles in pass 1 do not match the raster positions associated with the used nozzles in pass 4. Therefore, the virtual head table of pass 1 does not change from the right diagram of FIG. 8A.

  In the printing method shown in FIG. Therefore, the printer driver next refers to the virtual head information table (FIG. 7) regarding the upper end transition process, and each raster position and horizontal position associated with the used nozzle of the corresponding pass 1 and the upper end subsequent to pass 1. A comparison is made with each raster position and horizontal position associated with the nozzles used in the pass of the transition process. As shown in FIG. 9, the printer driver determines that nozzle ## 1 in pass 5 is the upper POL nozzle (Δ) based on the virtual head information table (FIG. 7) regarding the upper POL nozzle in the upper edge shifting process, and shifts the upper edge. It is determined from the virtual head information table (FIG. 7) relating to the processing that the nozzles ## 2 to ## 12 in pass 5 are normal use nozzles (◯). The raster positions associated with the used nozzles of pass 1 and the raster positions associated with the used nozzles of pass 5 match, and the horizontal positions of pass 1 and pass 5 match. Therefore, the printer driver changes the used nozzles ## 5 to ## 12 of pass 1 associated with the same raster position as the normal nozzle (◯) of pass 5 to unused nozzles in the virtual head table.

  In the printing method of FIG. 6, the upper end processing nozzle that is the opposite of the upper POL nozzle in the upper end transition processing is set as the lower POL nozzle. The nozzle ## 4 in the corresponding pass 1 has the same raster position and the same horizontal position as the upper POL nozzle (Δ) in pass 5. Therefore, the printer driver changes the nozzle ## 4 of pass 1 to the lower POL nozzle in the virtual head table. By so doing, it is possible to form dots by sharing the upper horizontal POL nozzle and the lower POL nozzle with respect to the pixel region at the same horizontal position.

  The printer driver performs comparison processing until the raster position range associated with the used nozzle in pass 1 does not overlap with the raster position range associated with the used nozzle in the pass subsequent to pass 1. To do. Thus, the virtual head table of pass 1 is determined to be the virtual head table shown in FIG. The printer driver creates a virtual head table in the same manner for other upper end processing passes 2 to 4.

<Upper end transition process>
FIG. 10A to FIG. 10E are diagrams for explaining the virtual head table creation process of pass 5 of the upper edge transition process. Here, the creation process of the virtual head table in the first pass 5 of the upper end transition process will be described as an example. The printer driver determines the head position and the horizontal position with reference to the virtual head information table (FIG. 7) regarding the upper edge transition process. The method for calculating the head position and the method for determining the horizontal position are the same as those in the upper end process. In the virtual head table, the head position in pass 5 is stored as 0, and the horizontal position in pass 5 is stored as 2.

  Next, the printer driver refers to the start nozzle and the end nozzle of the virtual head information table (FIG. 7) regarding the upper POL nozzle in the upper end transition process, and determines that nozzle ## 1 in pass 5 is the upper POL nozzle. Therefore, the printer driver stores the nozzle type of nozzle ## 1 in pass 5 as “upper POL nozzle” in the virtual head table. Similarly, the printer driver refers to the start nozzle and the end nozzle of the virtual head information table related to the upper end transition process, and determines that the nozzles ## 2 to ## 12 in pass 5 are used nozzles. Therefore, the printer driver stores the nozzle types of nozzles ## 2 to ## 12 in pass 5 as “used nozzles” in the virtual head table.

  In the printing method of FIG. 6, the dots that can be formed in the subsequent pass (normal processing) are given priority over the dots that can be formed in the corresponding pass of the upper edge transition process. That is, among the nozzles associated with the same dot formation position, the nozzle for the subsequent process (the nozzle for the normal process) is set as the use nozzle preferentially over the nozzle for the upper end transition process. Therefore, the raster position and horizontal position associated with the used nozzle (including the upper POL nozzle) of the corresponding pass in the upper end transition process, and the raster position and horizontal position associated with the used nozzle of the subsequent pass after the corresponding pass Perform a comparison process.

  As shown in FIGS. 10B to 10D, the raster positions and horizontal positions associated with the used nozzles of the corresponding pass 5 coincide with the raster positions and horizontal positions corresponding to the used nozzles of the subsequent passes 6 to 8. do not do. Therefore, the virtual head table of pass 5 does not change from FIG. 10A. Further, the raster position and horizontal position associated with the upper POL nozzles ## 1 and ## 2 in the subsequent normal process pass 9 and the raster position and horizontal position associated with the used nozzles ## 10 and ## 11 in pass 5 are used. The position matches. In the printing method of FIG. 6, the nozzle for the upper end transition process, which is the opposite of the upper POL nozzle for the normal process, is set as the lower POL nozzle. Therefore, the printer driver stores the nozzle type of the nozzles ## 10 and ## 11 in pass 5 as “lower POL nozzle” in the virtual head table. Further, the raster position and horizontal position associated with the used nozzle ## 12 in pass 5 coincide with the raster position and horizontal position associated with the normal used nozzle ## 3 in pass 9. Therefore, the printer driver changes the nozzle ## 12 in pass 5 to an unused nozzle in the virtual head table.

  The printer driver performs comparison processing until the raster position range associated with the used nozzle in pass 5 does not overlap with the raster position range associated with the used nozzle in the pass subsequent to pass 5. To do. Thus, the virtual head table of pass 5 of the upper end transition process is determined to be the virtual head table shown in FIG. 10E. The printer driver creates a virtual head table in the same manner for the path 6 of other upper end transition processing.

  By the way, in the printing method of FIG. 6, the POL raster and the normal raster are formed according to the same regularity as the normal printing area even in the area printed by the upper edge process and the upper edge transition process (hereinafter referred to as the upper edge printing area). To. That is, the normal raster and the POL raster are arranged in the same order in the block at the start of printing (thick frame in FIG. 6) and the block in the normal print area. The lower POL nozzle for the upper end transition process is naturally determined according to the upper POL nozzle for the normal process. On the other hand, the upper POL nozzle for the upper end transition process must be set in the upper end transition process so that the arrangement order of the normal raster and the POL raster follows the regularity because the upper end nozzle is compatible.

  In normal processing, the nozzles ## 1 and ## 2 are fixed to the upper POL nozzle. However, the transport amount of the head unit 40 in the upper end transition process is different from the transport amount of the head unit 40 in the normal process. Further, since it is determined in order from the raster line at the print start position whether the POL raster or the normal raster is to be selected, the nozzle ## for the upper end transition process is not necessarily required depending on the head position of the upper end transition process with respect to the print start position. 1, ## 2 cannot be set as the upper POL nozzle. That is, the number of upper POL nozzles in the upper end transition process cannot be made constant at two. For example, as shown in FIG. 6, the number of upper POL nozzles is 1 in pass 5 of the upper end transition process, and the number of upper POL nozzles is 2 in pass 6.

  Therefore, in the present embodiment, the range of the upper POL nozzles in the upper end transition processing pass 5 and pass 6 is stored in the virtual head information table regarding the upper POL nozzle in the upper end transition processing shown in FIG. As described above, the printer driver refers to the start nozzle and the end nozzle of the virtual head information table related to the upper POL nozzle in the upper end transition process, and the upper POL nozzle in pass 5 is nozzle ## 1, and the upper POL in pass 6 The nozzles are determined to be nozzles ## 1 and ## 2.

  The head position of the upper end transition process with respect to the print start position does not vary regardless of the medium or the image size. For example, the position of nozzle ## 1 in pass 5 of the upper edge transition process is always the 0th raster position (L0), which is the print start position. In addition, in order from the raster line at the print start position, it is determined whether to use the POL raster or the normal raster. For example, in order to align a POL raster and a normal raster according to regularity, the 0th raster line needs to be a POL raster, and nozzle ## 1 of pass 5 associated with the 0th raster position is set as the upper POL nozzle. Decide what to set.

  As described above, the range of the upper POL nozzle in the upper end transition process can be fixedly set regardless of the medium and the image size. Therefore, the range of the upper POL nozzle is stored in the virtual head information table related to the upper POL nozzle in the upper end transition process shown in FIG. By doing so, the printer driver can set the upper POL nozzle for the upper end transition process for each page without calculating the number of the upper POL nozzles for the upper end transition process, thereby facilitating the virtual head table creation process. I can do it.

  When creating the virtual head information table related to the upper POL nozzle in the upper end transition process, it is preferable to virtually transition the normal process from the first pass 7 of the normal process to the paths 5 and 6 of the upper end transition process. . Then, it is preferable to set the actual upper end transition processing nozzle corresponding to the upper POL nozzles ## 1 and ## 2 of the normal processing virtually transitioned to the passes 5 and 6 side as the upper POL nozzle.

  For example, the raster positions associated with the upper POL nozzles ## 1 and ## 2 in the first pass 7 of the normal process are L8 and L10. Then, in the virtual pass 6 that is changed from the first pass 7 of the normal process to the normal process, the raster positions associated with the upper POL nozzles ## 1 and ## 2 are L3 and L5. Therefore, it is preferable to set the nozzles ## 1 and ## 2 associated with the raster positions L3 and L5 to the upper POL nozzle in pass 6 in pass 6 of the actual upper end transition process. Further, in the virtual pass 5 that is further transitioned from the virtual pass 6 by the normal process, the raster positions associated with the upper POL nozzles ## 1 and ## 2 are L-2 and L0. Therefore, it is preferable to set the nozzle of the actual pass 5 to which the raster positions L-2 and L0 are associated with each other in the upper end transition processing pass 5 as the upper POL nozzle. However, since there is no actual pass 5 nozzle corresponding to the raster position L-2, only the actual pass 5 nozzle ## 1 associated with the raster position L0 is set as the upper POL nozzle.

<Normal processing>
FIG. 11 is a diagram for explaining the virtual head table creation process of pass 7 of the normal process. Here, the creation process of the virtual head table in the first pass 7 of the normal process will be described as an example. First, the printer driver refers to the virtual head information table (FIG. 7) relating to normal processing, determines the head position (8 for pass 7) and the horizontal position (1 for pass 7), and stores them in the virtual head table.

  Next, the printer driver refers to the start nozzle and the end nozzle of the virtual head information table (FIG. 7) regarding the upper POL nozzle in the normal process, and in the virtual head table, the nozzle type of nozzles ## 1, ## 2 in pass 7 Is stored as the upper POL nozzle. Similarly, the printer driver refers to the start nozzle and end nozzle of the virtual head information table related to normal processing, and stores the nozzle types of nozzles ## 3 to ## 10 in pass 7 as used nozzles in the virtual head table. Further, the printer driver refers to the start nozzle and the end nozzle of the virtual head information table related to the lower POL nozzle in the normal processing, and sets the nozzle type of the nozzles ## 11 and ## 12 in pass 7 as the lower POL nozzle in the virtual head table. Let me remember.

  In the printing method of FIG. 6, dots that cannot be formed by the normal process are formed by the upper end / lower end process and the transfer process, and the dots that can be formed by the normal process are more than the dots that can be formed by the upper end / lower end process and the transfer process. Prioritize. Therefore, when creating the virtual head table for normal processing, unlike the above-described upper end processing and upper end transition processing, the comparison processing with the raster position that can be formed by the nozzles used in the subsequent passes is not performed.

<Bottom transition process>
FIG. 12 is a diagram for explaining the dummy table. FIGS. 13A to 13C are diagrams showing how the nozzles used in the scheduling table are determined. FIGS. 14A to 14D show the lower POL nozzles in the lower end transition process. It is a figure which shows a mode that it determines. In the lower-end transition process and the lower-end process, dots that are formed when the normal process is continued in the area printed by the lower-end transition process and the lower end process (lower end print area) are formed. In other words, since the dots that cannot be formed by the normal process are formed by the lower end transition process and the lower end process, the normal process nozzles associated with the same position on the medium are given priority over the lower end process and the lower end transition process nozzles. It can be said that it is set to the nozzle used. Therefore, the printer driver creates a dummy table in which raster positions and horizontal positions where dots are formed when normal processing is continued after the last pass 13 of normal processing are registered. Then, the printer driver determines the nozzle for the lower end transition process that can form dots at the raster position and the horizontal position registered in the dummy table as the use nozzle.

  By the way, in this embodiment, the printer driver creates a virtual head table for each pass, and when the pixel data used in each pass is rearranged, the printer driver sequentially transmits the data to the printer 1. By doing so, printing can be started earlier than when the pixel data used in all passes is rearranged and then the data is transmitted to the printer 1. However, in the lower-end transition process and the lower-end process, since the nozzles to be used are determined by creating a dummy table or the like, it takes time to determine the nozzles to be used. Therefore, before starting printing, the nozzles used for the lower end transition process and the lower end process are determined. In the present embodiment, a scheduling table as shown in FIG. 13C is created. In the scheduling table, the head position, the horizontal position, the range of used nozzles (start nozzle / end nozzle), and the range of lower POL nozzles (start nozzle / end nozzle) are stored for each path of the lower end transition process. .

  When creating the scheduling table, the number of lower POL nozzles is calculated for each pass of the lower edge transition process. In the printing method of FIG. 6, the POL raster and the normal raster are formed in the lower end print area in accordance with the same regularity as the normal print area. In normal processing, the nozzles ## 11 and ## 12 can be fixedly set to the lower POL nozzle. That is, in the normal process, the number of lower POL nozzles can be kept constant at two. However, since the transport amount of the head unit 40 is different in the normal process and the lower end transition process, the number of lower POL nozzles cannot be made constant in the lower end transition process.

  Furthermore, since the raster position as the print end position varies depending on the medium and the image size, the head position of the lower end transition process with respect to the print end position varies. Therefore, the upper POL nozzle range can be fixedly set in the upper end transition process, and the upper POL nozzle range can be stored in the virtual head information table of FIG. Accordingly, the range of the lower POL nozzle varies. Therefore, in the lower end transition process, the number of lower POL nozzles is calculated for each page according to the print end position that varies depending on the medium and the image size. Then, the range of the lower POL nozzle is stored in the scheduling table.

  First, creation of a dummy table will be described. The printer driver refers to the virtual head information table (FIG. 7) regarding the dummy process, and the raster position and the horizontal position of the virtual path 14 ′ in which the normal process is continued from the last pass 13 of the normal process instead of the lower-end transition process. Is registered in the dummy table. In the normal processing, the horizontal positions are associated in the order of 1, 2, 2, 1 for each path. Since the horizontal positions are associated with the paths 12 and 13 at the end of the normal processing in the order of 2 and 2, the horizontal positions are associated with the virtual paths 14 'in the order of 1, 1, 2 and 2, in that order. Further, since the head position of the last pass 13 of the normal process is 38 and the transport amount of the head unit 40 of the normal process is 5D, as shown in the start raster position of the virtual head information table related to the dummy process, as shown in FIG. The head position of the pass 14 ′ is 43.

  In the normal process, the nozzles ## 1 to ## 12 of the virtual head are set as the use nozzles (including the POL nozzle), whereas in the dummy process, the nozzles ## 1 to ## of the virtual head. 10 is set as a use nozzle, and nozzles ## 11 and ## 12 are set as non-use nozzles. If the raster position formed by the nozzles ## 11 and ## 12 in the virtual pass is also registered in the dummy table, it is formed by the nozzles ## 1 and ## 2 corresponding to the upper POL nozzle in the normal process. Two raster positions that are the same as the first raster position are registered in the dummy table. In the normal process, two nozzles ## 11 and ## 12 are set as the lower POL nozzles, whereas in the lower end transition process, the number of lower POL nozzles varies. For this reason, there is a possibility that two nozzles associated with two registered raster positions will become normal use nozzles, and double dots will be formed.

  Then, the printer driver calculates a raster position associated with each of the used nozzles ## 1 to ## 10 of the virtual pass 14 ′ based on the head position 43 of the virtual pass 14 ′ and the nozzle pitch number 2. . However, in the printing method of FIG. 6, since the print end position is the 64th raster position, the raster position larger than the 64th is not registered in the dummy table.

  In this way, as shown in FIG. 12, with respect to the virtual path 14 ', the horizontal position is 1, and every second raster position from the 43rd to the 61st is registered in the dummy table. Similarly, the virtual path 15 ′ after the virtual path 14 ′ is also a path in which the normal process has been changed, and the printer driver uses the horizontal position (1) associated with the used nozzles ## 1 to ## 10 of the virtual path 15 ′. ) And raster positions (L48 to L64) are registered in the dummy table. The printer driver registers the raster position and the horizontal position in the dummy table until the raster position associated with the used nozzle of the virtual pass for which the normal process is changed becomes larger than 64th. At the raster position and horizontal position registered in the dummy table, the nozzles used for the lower end transition process and the lower end process form dots.

  Next, the printer driver creates a scheduling table (FIG. 13C). The printer driver refers to the virtual head information table (FIG. 7) regarding the lower end transition process, and stores the head position and the horizontal position of the path of the lower end transition process in the scheduling table. After that, the printer driver detects the raster position and horizontal position (corresponding to the actual position) associated with the nozzles that can be used in the lower-end transition processing pass, and the raster position and horizontal position (imaginary position) registered in the dummy table. Equivalent). Then, the nozzle for the lower end transition process that matches the raster position and the horizontal position of the dummy table is determined as the used nozzle, and the nozzle that does not match is determined as the unused nozzle.

  More specifically, the printer driver refers to the virtual head information table related to the lower end transition process, and determines the raster position and the horizontal position associated with the nozzles ## 1 to ## 12 that can be used in the path 14 of the lower end transition process. calculate. As illustrated in FIG. 13A, the raster position and the horizontal position associated with the nozzles ## 1 to ## 11 in pass 14 coincide with the raster position and the horizontal position registered in the dummy table. Therefore, the printer driver stores the start nozzle of pass 14 as “## 1” and the end nozzle as “## 11” in the scheduling table. Then, the printer driver deletes from the dummy table the data that matches the raster position and the horizontal position that are associated with the actual nozzles used (in FIG. 13A, the data of the matching dummy table is marked with an X). As for the pass 15, as shown in FIG. 13B, the raster position and the horizontal position associated with the nozzles ## 2 to ## 10 coincide with the data registered in the dummy table. Therefore, the printer driver stores the start nozzle of pass 15 as “## 2” and the end nozzle as “## 10” in the scheduling table.

  Next, the printer driver calculates the number of lower POL nozzles in each pass of the lower edge transition process. As described above, in the lower end transition process, the number of lower POL nozzles cannot be made constant. Further, in the lower end transition process, unlike the upper end transition process, the number of lower end POL nozzles cannot be fixed and set according to the print end position corresponding to the size of the image or data. Therefore, the printer driver calculates the number of lower POL nozzles for each page in the lower-end transition process.

  The number of lower POL nozzles in the lower end transition process can be calculated by the following formula. The calculation formula for the number of lower POL nozzles differs between the first pass of the lower end transition process (pass 14 in FIG. 6) and the second and subsequent passes of the lower end transition process (pass 15 in FIG. 6). The number of lower end POL nozzles in normal processing is “Oo”, the number of raster lines corresponding to the transport amount of the head unit 40 in normal processing is “F1” (5 in FIG. 6), and transport of the first pass of lower end transition processing is performed. The number of raster lines corresponding to the amount is “F2” (5 in FIG. 6), and the number of raster lines corresponding to the transport amount after the second pass of the lower end transition process is “F3” (3 in FIG. 6). The number of raster lines corresponding to the nozzle pitch (that is, the number of pitches between nozzles) is “P” (2 in FIG. 6). The number of unusable nozzles at the end (lower end) on the front side in the Y direction in the nozzle row for normal processing is “N1”, and the unusable nozzles on the end portion (lower end) on the front side in the Y direction in the nozzle row for lower end transition processing Let it be “N2”.

  The number of raster lines corresponding to the carry amount is the number of raster lines located at a length corresponding to the carry amount, and can be calculated by “convey amount / nozzle pitch”. For example, in the normal process, the carry amount is 5D, and the pitch between nozzles (intervals in the Y direction of the raster lines) is D. Therefore, the number of raster lines F1 corresponding to the carry amount of the normal process is 5. Further, in the printing method of FIG. 6, alignment is performed at the print end position in the first pass of the lower edge transition process. That is, the transport amount (5D in FIG. 6) of the first pass 14 in the lower end transition process is determined so that the position of the nozzle in the first pass 14 in the lower end transition process reaches the print end position. In principle, the transport amount (3D) for the lower end transition process is set to the transport amount between the normal process transport amount (5D) and the lower end process transport amount (D). Since the position adjustment is performed, the conveyance amount between the normal process and the lower end process may not be achieved. Therefore, the number of raster lines “F2” corresponding to the transport amount of the first pass in the lower end transition process may be different from the number of raster lines “F3” corresponding to the transport amount in the second and subsequent passes of the lower end transition process.

  An unusable nozzle is a nozzle that is determined not to be used for printing from the beginning, and an end nozzle (end nozzle of a virtual head) in the nozzle row is set as an unusable nozzle. That is, it is different from the unused nozzles determined during the creation of the virtual head table (for example, nozzles ## 1 to ## 3 in FIG. 8A). In this embodiment, as shown in FIG. 4, the end nozzle ## 1 (nozzle # 1 of the first head 41 (1)) to the end nozzle ## 12 (second head 41 (2)) of the virtual head. Since the nozzles up to nozzle # 7) are usable nozzles, the number N1 of unusable nozzles for normal processing and the unusable nozzle N2 for lower end transition processing are both zero. However, the present invention is not limited to this, and the end nozzles in the nozzle row are likely to vary in ejection characteristics as compared with other nozzles. Also, when adjusting the number of usable nozzles according to the printing resolution and the carry amount, the nozzles are set to unusable nozzles in order from the end nozzles of the nozzle row. The unusable nozzles N1 and N2 do not include nozzles located outside the printing area.

The number O (1) of the lower POL nozzles in the first pass of the lower end transition process can be calculated by the following equation.
O (1) = Oo-{(F1-F2) / P- (N1-N2)} Formula 1
The number O (n) of the lower POL nozzles in the pass n after the second pass of the lower-end transition process can be calculated by the following equation. Note that the number of lower POL nozzles in the (n−1) th pass of the lower end transition process is “O (n−1)”.
O (n) = O (n−1) − {(F1−F3) / P} Equation 2
It should be noted that the raster position associated with a part of the nozzles of the virtual pass (for example, the virtual pass 14 ′ in FIG. 12) transitioned from the last pass 13 of the normal processing to the lower end from the last pass 13 of the normal processing. It is assumed that the raster positions associated with some nozzles in the actual pass that has been transitioned in the transition process are equal. Also, it is assumed that the number of unusable nozzles does not change between passes of the lower end transition process.

  Further, here, the transport amounts F1 to F3 of the head unit 40 (corresponding to the relative movement amount of the head in the nozzle array direction with respect to the medium) are represented by the number of raster lines, and the nozzle pitch (corresponding to a predetermined interval) is also represented by the number of raster lines. Therefore, the number of nozzles (for example, (F1-F2) / P) to be subtracted from the number of lower POL nozzles Oo during normal processing is calculated as an integer. However, if the lengths (units) corresponding to the transport amounts F1 to F3 and the nozzle pitch P are the same, the number of raster lines is not limited.

  In the printing method of FIG. 6, printing is performed so that the normal raster and the POL raster are arranged in accordance with the same regularity over the entire area of the image. Therefore, the nozzles for the lower end transition process corresponding to the lower POL nozzles ## 11 and ## 12 when the normal process is continued instead of the lower end transition process from the last pass of the normal process are set as the lower POL nozzles. By doing so, the normal raster and the POL raster can be formed according to regularity even if the conveyance amounts of the normal process and the lower end transition process are different.

  The transport amount of the normal process is larger than the transport amount of the lower end transition process (at least the transport amount after the second pass of the lower end transition process). Therefore, there is a nozzle that exists when the normal process is continued from the last pass 13 of the normal process, but does not exist when the lower end transition process is continued from the last pass 13 of the normal process. Therefore, the number of nozzles that are present when the normal process is continued but are not present when the lower end transition process is continued are calculated by a part “(F1−F2) / P” of the above-described formula 1. The nonexistent nozzle calculated in this way cannot be set as the lower POL nozzle in the lower end transition process. For this reason, the number of nozzles that do not exist when the lower end transition process is continued from the lower POL nozzle number Oo of the normal process (F1−F0) by the part “Oo − {(F1−F2) / P}” of the above-described formula 1. F2) / P is subtracted.

  For example, when the number N2 of unusable nozzles in the lower end transition process is larger than the number N1 of unusable nozzles in the normal process, the lower POL nozzle is set in the lower end transition process by the amount of the unusable nozzles. The number of nozzles that can be reduced. Conversely, when the number N2 of unusable nozzles in the lower end transition process is smaller than the number N1 of unusable nozzles in the normal process, the number of unusable nozzles is subtracted from the number of lower POL nozzles Oo in the normal process. The number of nozzles can be reduced. Therefore, the calculation formula for the number of lower POL nozzles O (1) in the first pass of the lower-end transition processing is “Oo − {(F1−F2) / P− (N1−N2)}”.

  In the present embodiment, it is assumed that the number of unusable nozzles does not change between the lower-end transition processing passes. In Equation 1, the difference between the number N1 of unusable nozzles for normal processing and the number N2 of unusable nozzles for lower end transition processing is considered. Therefore, in the second and subsequent passes of the lower end transition process, the lower POL nozzle may be set as the lower POL nozzle when the lower POL nozzle set in the previous pass n-1 is shifted by the transport amount of the normal process. Therefore, in the second and subsequent passes of the lower end transition processing, the lower end transition is performed from the number of lower POL nozzles O (n−1) calculated in the previous pass n−1 due to the difference in the transport amount between the lower end transition processing and the normal processing. What is necessary is just to subtract the number ((F1-F2) / P) of the nozzle which does not exist when making a transition by processing.

When the number of unusable nozzles is changed between passes in the lower end transition process, the number of lower POL nozzles “O (n)” in the second and subsequent passes in the lower end transition process may be calculated by the following equation. . The number of unusable nozzles at the lower end in the nozzle row of the previous pass n−1 is “N3”, and the number of unusable nozzles at the lower end in the nozzle row of the corresponding pass n is “N4”.
O (n) = O (n-1)-{(F1-F3) / P- (N3-N4)}

  Specifically, calculation of the number of lower POL nozzles in the lower end transition process of the printing method of FIG. 6 will be described. FIG. 14A shows how the number of lower POL nozzles in the first pass 14 of the lower end transition process is calculated. The number of lower POL nozzles for normal processing is 2, the number of raster lines F1 corresponding to the transport amount for normal processing is 5, the number of raster lines F2 corresponding to the transport amount for pass 14 is 5, The number of unusable nozzles N1 for processing is 0, and the number of unusable nozzles N2 for bottom transition processing is 0. Therefore, the number O (1) of the lower POL nozzles in the first pass 14 of the lower end transition process is calculated as “2-{(5-5) / 2− (0-0)} = 2”. The printer driver calculates the lower portion in order from the nozzle ## 12 closest to the Y direction in the Y direction among the nozzles ## 1 to ## 12 of the virtual head excluding the unusable nozzles. The number of POL nozzles is set as the lower POL nozzle. Here, since there are no unusable nozzles, the printer driver determines that the two nozzles ## 12 and ## 11 from the front side in the Y direction of the virtual head should be set as the lower POL nozzles.

  In pass 14, the conveyance amount of the head unit 40 is the same as the conveyance amount of the normal process for alignment to the print end position. Therefore, there are zero nozzles that are present when the normal process is continued from the last pass 13 of the normal process, but are not present when the lower end transition process is continued. There are no unusable nozzles. Therefore, as shown in FIG. 14A, the lower POL nozzles ## 11 and ## 12 of the virtual pass 14 ′ that has continued the normal process from the last pass 13 of the normal process are shifted to the lower end from the last pass 13 of the normal process. This corresponds to the nozzles ## 11 and ## 12 in the actual pass 14 in which the processing is continued. This also shows that the number of lower POL nozzles in the pass 14 is O (1).

  However, in the scheduling table, the end nozzle of pass 14 is nozzle ## 11, and nozzle ## 12 is located outside the printing area. That is, nozzle ## 12 in pass 14 is set as a lower POL nozzle if it is located within the print area, but is set as an unused nozzle because it is located outside the print area. Therefore, the printer driver stores the start nozzle and the end nozzle of the lower end POL nozzle as nozzle ## 11 in the scheduling table. This indicates that only nozzle ## 11 in pass 14 is set as the lower POL nozzle. As described above, the printer driver calculates the number of lower POL nozzles in the lower-end transition processing pass, sets the lower POL nozzles in order from the nozzles on the front side in the Y direction of the virtual head, and then sets the lower POL nozzles located outside the print area. Change the POL nozzle to an unused nozzle. By doing so, it is possible to prevent ink from being ejected from the nozzles located outside the printing region.

  Here, referring to FIG. 6, the raster position (No. 63) associated with the lower POL nozzle ## 11 of the pass 14 is located at the top in the block (in the thick frame). The uppermost raster line in the block of the normal printing area is the POL raster. Therefore, by setting the nozzle ## 11 of pass 14 to the lower POL nozzle, the uppermost raster line can be made the POL raster in the block in the lower end printing area as in the normal printing area. Further, the nozzle ## 12 of pass 14 is set as the lower POL nozzle if it is located in the printing area. The raster position (No. 65) associated with nozzle ## 12 in pass 14 is the third position from the top in the block. Therefore, if the nozzle ### 12 in pass 14 is set as the lower POL nozzle if it is within the printing area, the third raster line from the top is set to the POL raster in the block in the lower end printing area as in the normal printing area. Can be made. Also from this, by setting the lower POL nozzle of the lower end transition processing pass based on the above-described formula for calculating the number of lower POL nozzles, the POL raster and the normal raster are regulated in the lower end print area as in the normal print area. It can be seen that it can be formed.

  FIG. 14B shows how the number of lower POL nozzles O (n) in the second pass 15 of the lower end transition process is calculated. The number of lower POL nozzles O (n−1) calculated in the pass 14 immediately before the pass 15 is 2, the number of raster lines F1 corresponding to the transport amount of the normal processing is 5, and the transition to the lower end The raster line number F3 corresponding to the transport amount after the second pass of the process is 3, and the inter-nozzle pitch number P is 2. Therefore, the number O (n) of the lower POL nozzles in the second pass 15 of the lower end transition process is calculated as “2-{(5-3) / 2)} = 1”. Therefore, in the second pass 15 of the lower end transition process, the printer driver is the frontmost side (lower end side) in the Y direction among the nozzles excluding the used additional nozzles from the nozzles ## 1 to ## 12 of the virtual head. No. ## 12) to one nozzle ## 12 is set as the lower POL nozzle. However, the printer driver refers to the scheduling table, and determines that the nozzle ## 12 is located outside the print area because the end nozzle of the pass 15 is the nozzle ## 10. Therefore, the printer driver stores that information in the scheduling table, assuming that there is no nozzle to be set as the lower POL nozzle in pass 15.

  The transport amount (3D) of the path 15 is shorter than the transport amount (5D) of the normal process. Therefore, as shown in FIG. 14B, the actual pass 15 in which the lower end transition process is continued from the actual pass 14 corresponds to the nozzle ## 12 in the virtual pass 15 ′ in which the normal process is continued from the actual pass 14. No nozzle is present. Nozzle ## 12 in the virtual pass 15 'is set to the lower POL nozzle, although it is outside the printing area in the pass 14 described above. However, in the actual pass 15, there is no nozzle corresponding to the nozzle ## 12 of the virtual pass 15 '. This also shows that the number of lower POL nozzles in pass 15 is “1”, which is one less than the number (two) of lower POL nozzles in pass 14.

  Referring to FIG. 6, the raster position (No. 68) associated with the lower POL nozzle ## 12 (nozzle outside the printing area) in pass 15 is located at the top in the block. The uppermost raster line in the block of the normal printing area is the POL raster. Therefore, by setting the nozzle ## 12 of pass 15 as the lower POL nozzle if it is within the printing area, the top raster line is changed to the POL raster in the block of the lower end printing area as in the normal printing area. I can do it. The raster position (No. 66) associated with the nozzle ## 11 that is not set as the lower POL nozzle in the pass 15 is the fourth position from the top in the block. Even in the block of the normal printing area, the fourth raster line from the top is the normal raster. Therefore, the nozzle ## 11 in pass 15 is not set as the lower POL nozzle, so that the fourth raster line from the top in the block in the lower end print area can be set as the normal raster as in the normal print area.

  FIG. 14D is a diagram illustrating the number O (1) of the lower POL nozzles in the first pass of the lower end transition process when there are unusable nozzles. In the figure, the nozzles of the virtual pass where the normal process is continued from the last pass of the normal process and the nozzles of the actual pass where the lower end transition process is continued from the last pass of the normal process are shown. The number of lower POL nozzles for normal processing is set to 4, the number of raster lines F1 corresponding to the transport amount for normal processing is set to 5, and the number of raster lines F2 corresponding to the transport amount for the first pass of the lower end transition processing is set to 3. The nozzle pitch number P is 2. Then, the number of unusable nozzles N1 in the normal process is 1 (nozzle ## 12), and the number of unusable nozzles N2 in the lower end transition process is 2 (nozzles ## 11, ## 12). When these values are substituted into the above equation, the number of lower POL nozzles O (1) in the first pass of the lower end transition process is “4-{(5-3) / 2− (1-2)} = 2”. Is calculated. Therefore, in the virtual head, two nozzles ## 9 and ## 10 from the lower end side among the nozzles excluding the two unusable nozzles ## 11 and ## 12 from the nozzle ## 12 at the lowermost end side. Set to the lower POL nozzle. As shown in FIG. 14D, the two lower POL nozzles ## 8 and ## 9 of the virtual pass that has continued the normal process from the last pass of the normal process, and the lower end transition process from the last pass of the normal process are continued. The actual pass nozzles ## 9 and ## 10 correspond to each other. This also shows that the number of lower POL nozzles O (1) is two.

  In this way, the printer driver creates a scheduling table (FIG. 14C) for the lower edge transition process before starting printing. By doing so, it is not necessary to create a dummy table (FIG. 12) or calculate the number of lower POL nozzles during printing, so that it is possible to prevent the printing processing speed from being reduced.

  FIG. 15A and FIG. 15B are diagrams illustrating the virtual head table creation process of the path 14 of the lower end transition process. After creating the above-described scheduling table for the lower end transition process, the printer driver creates a virtual head table in order from the upper end process pass, rearranges the pixel data used in each pass, and transmits it to the printer 1. Then, the printer driver refers to the scheduling table and creates a virtual head table in order to transmit the pixel data of the lower-end transition processing pass to the printer 1. First, the printer driver stores the head position (43 in pass 14) and the horizontal position (1 in pass 14) stored in the scheduling table in the head position and horizontal position of the virtual head table. After that, the printer driver refers to the start nozzle (## 1) and end nozzle (## 11) of the scheduling table and the start nozzle and end nozzle (## 11) of the lower POL nozzle. The nozzle types ## 1 to ## 10 are stored as used nozzles, the nozzle type of nozzle ## 11 is stored as a lower POL nozzle, and the nozzle type of nozzle ## 12 is stored as an unused nozzle.

  In the lower end transition process, a nozzle that is a counterpart of the lower POL nozzle in the normal process is set as the upper POL nozzle. Therefore, as shown in FIG. 15B, the printer driver performs the raster position and horizontal position associated with the used nozzles in pass 14, and the raster position and horizontal position of the lower POL nozzle associated with the normal processing pass before pass 14. Compare with the horizontal position. The printer driver performs comparison processing for the lower POL nozzles from pass 10 to pass 13 included in the range of raster positions associated with the used nozzles of pass 14. As a result, it can be seen that the nozzles ## 1 and ## 2 in pass 14 become the nozzles opposite to the lower POL nozzles ## 11 and ## 12 in pass 10. In this case, the printer driver changes the nozzle type of the nozzles ## 1 and ## 2 to the upper POL nozzle in the virtual head table.

  In this way, the virtual head table in the path 14 of the lower end transition process is determined as the virtual head table shown in FIG. 15B. The printer driver creates a virtual head table in the same manner with respect to the path 15 of the other lower edge transition processing.

<Lower end processing>
FIG. 16A shows a dummy table in which data of raster positions and horizontal positions at which dots are to be formed in the lower end transition process and the lower end process is registered, and FIG. 16B shows a raster that can be formed from the dummy table in FIG. 16A by the lower end transition process. FIG. 16C shows a dummy table in which data associated with the lower POL nozzle in the lower end transition process is restored, and FIG. 16D shows each pass of the lower end process. It is a figure which shows a mode that a use nozzle is determined, and FIG. 16E is a figure explaining the scheduling table of a lower end process. Similar to the lower end transition process, the nozzle used for the lower end process is determined based on a dummy table (corresponding to a table). Therefore, the printer driver creates a scheduling table related to the lower end process before starting printing. By doing so, it is possible to prevent the printing processing speed from being slowed down.

  First, a process for creating a scheduling table related to the lower end process will be described. The printer driver uses the virtual pass 14 ′ to pass 18 ′ in which the normal process is continued instead of the lower end shift process after the last pass 13 of the normal process, as in the lower end shift process (FIG. 12). The raster position and the horizontal position associated with are registered in the dummy table (FIG. 16A).

  Next, the printer driver refers to a scheduling table (FIG. 14C) regarding the lower end transition process, and calculates a raster position and a horizontal position associated with the used nozzles (including the lower POL nozzle) for the lower end transition process. Then, the printer driver searches the dummy table of FIG. 16A for the raster position and horizontal position data associated with the calculated nozzle used for the lower end transition process, and if there is a match, the printer driver stores the data in the dummy table. Delete from the list. That is, dots that cannot be formed by the lower end transition process are formed by the lower end process. Therefore, it can be said that, among the nozzles associated with the same dot formation position, the nozzle for the lower end transition process is set as the use nozzle with priority over the nozzle for the lower end process.

  Thereafter, the printer driver refers to the scheduling table for the lower end transition process and determines whether the lower POL nozzle is set in the lower end transition process. The lower POL nozzle in the lower end transition processing is compatible with the subsequent lower end processing nozzle, and forms dots by sharing the pixel region at the same horizontal position. For this reason, if the raster position and the horizontal position associated with the lower POL nozzle in the lower end transition process are still deleted from the dummy table from the dummy table, the lower end process nozzle that is the opposite of the lower POL nozzle in the lower end transition process is deleted. It is determined that the nozzle is not used. In the present embodiment, as shown in FIG. 14C, nozzle ## 11 in pass 14 is set as the lower POL nozzle. Therefore, as shown in FIG. 16C, the data of the raster position (L63) and the horizontal position (1) associated with the nozzle ## 11 in pass 14 are restored to the dummy table. By doing so, it is possible to determine the nozzle for the lower end process which is the opposite of the lower POL nozzle for the lower end transition process as the use nozzle. However, the present invention is not limited to this. For example, the upper POL nozzle of the lower end process which is the opposite of the lower POL nozzle of the lower end transition process is determined, and the information of the upper POL nozzle of the lower end process is registered in the scheduling table related to the lower end transition process. (FIG. 14C).

  Next, as illustrated in FIG. 16D, the printer driver refers to the virtual head information table (FIG. 7) regarding the lower end process, and the raster position and the horizontal position associated with the used nozzles ## 1 to ## 12 for the lower end process. And comparison processing of the raster position and the horizontal position registered in the dummy table of FIG. 16C. Then, the printer driver determines the nozzle in the lower end processing pass whose position matches the data registered in the dummy table as the used nozzle, and determines the nozzle whose position does not match as the unused nozzle. Note that the printer driver deletes the data with the matching position from the dummy table. The printer driver performs a comparison process between the dummy table data and the raster position and the horizontal position associated with the nozzle used for the lower end process until the dummy table data disappears. As a result, as shown in FIG. 16D, nozzles ## 4 to ## 9 are determined to be used nozzles in pass 16, nozzles ## 6 to ## 9 are determined to be used nozzles in pass 17, and nozzles are passed in pass 18 ## 8 is determined as the nozzle to be used.

  The printer driver stores the start nozzle and the end nozzle among the used nozzles of each pass thus determined in the scheduling table (FIG. 16E). In the lower end transition process, the lower POL nozzle is set, whereas in the lower end process, the lower POL nozzle is not set. Therefore, information indicating the range of the lower POL nozzle is not stored in the scheduling table for the lower end process.

  FIG. 17A and FIG. 17B are diagrams illustrating the virtual head table creation process of the path 16 of the lower end process. The printer driver stores the head position (47 for pass 16) and the horizontal position (2 for pass 16) and the horizontal position (2 for pass 16) of the scheduling table (FIG. 16E) regarding the lower end processing as the head position and horizontal position of the virtual head table. Thereafter, the printer driver refers to the start nozzle and the end nozzle of the scheduling table, and stores the nozzle type in the virtual head table. In the virtual head table of pass 16, nozzles ## 1 to ## 3 and nozzles ## 10 to ## 12 are stored as unused nozzles, and nozzles ## 4 to ## 9 are stored as used nozzles.

  In the lower end process, a nozzle that is a counterpart of the lower POL nozzle in the normal process and the lower end shift process is set as the upper POL nozzle. Therefore, as illustrated in FIG. 17B, the printer driver performs a comparison process between the raster position and horizontal position of the used nozzle in pass 16 and the raster position and horizontal position of the lower POL nozzle in the pass before pass 16. In pass 16, nozzles ## 4 and ## 5 are compatible with the lower POL nozzles ## 11 and ## 12 in pass 12, so the printer driver uses the nozzles ## 4 and ## 5 in the virtual head table. The nozzle type is changed to the upper POL nozzle.

  Thus, the virtual head table of the lower end process pass 16 is determined to be the virtual head table shown in FIG. 17B. The printer driver creates a virtual head table in the same manner for other lower end processing passes 17 to 18. Note that the raster position and horizontal position data associated with the lower POL nozzle ## 11 in the pass 14 of the lower end transition process, and the data (L63) restored in the dummy table of FIG. 16C is the nozzle # in the pass 18 It matches the raster position and horizontal position associated with # 8. Therefore, nozzle ## 8 in pass 18 is set as the upper POL nozzle.

  As described above, when the scheduling table for the lower end process is created, after the raster position and the horizontal position associated with the used nozzle of the virtual pass that has continued the normal process from the last pass of the normal process are registered in the dummy table, the lower end transition is performed. Raster position and horizontal position data where dots are formed by processing are deleted from the dummy table. By doing so, in the lower end processing, it is possible to form dots that are not formed by the normal processing and the lower end transition processing. In other words, in the lower end processing, dots are not formed at positions where dots are formed in the lower end transition processing, so that double dots can be prevented from being formed.

  Note that during the lower end processing, the printer driver creates a dummy table (FIG. 16A) in which dot positions formed in a virtual pass in which normal processing is continued from the last pass of normal processing is registered. Absent. The printer driver may create the scheduling table for the bottom edge processing using the data (for example, FIG. 13B) of the dummy table after the scheduling table is created during the bottom edge transition processing.

<Extraction / Sort Processing>
FIG. 18A is a diagram for explaining a parameter table regarding the configuration of the first head 41 (1) and the second head 41 (2), and FIG. 18B is a diagram for explaining a process for replacing the virtual head table with an actual head table. It is. FIG. 19A is a diagram showing image data (image data after halftone processing) in which pixels are arranged in a matrix, and FIG. 19B is a diagram showing raster data rearranged for each head 41. The squares (small squares) in FIG. 18A indicate pixels constituting the image, and the numbers written in the pixels correspond to pixel data, indicating the presence / absence of dot formation and the type of dot. One raster line is printed by the pixel data arranged in the X direction. This group of pixel data arranged in the X direction is referred to as “raster data”. And a small number is attached | subjected sequentially from the raster data located in the Y direction back side. Among the image data, the raster data located on the farthest side in the Y direction corresponds to the 0th raster data at the print start position.

  So far, the process of creating a virtual head table for each pass by the printer driver has been described. After creating a virtual head table for a path, the printer driver extracts raster data (all or a part) to be used for the path from the image data based on the created virtual head table, and uses each head 41. The rearrangement process is performed so as to correspond to the nozzles. Note that image data is created for each ink color (YMCK). Therefore, the printer driver performs raster data extraction and rearrangement processing for each color.

  By the way, the printer driver creates a virtual head table indicating information related to a virtual head in which the first head 41 (1) and the second head 41 (2) are combined. Therefore, it is necessary to associate the nozzle type for the nozzle of the virtual head stored in the virtual head table with the nozzle of the actual head 41. Further, it is necessary to replace the information indicating the position where the nozzle of the virtual head should form the dot with the information indicating the position where the nozzle of the actual head 41 should form the dot. Therefore, in the present embodiment, as shown in FIG. 18B, the first head table and the second head table are created based on the virtual head table.

  The first head table and the second head table store a head position, a horizontal position, a start nozzle and an end nozzle, and an address to the nozzle type. The head position indicates the raster position associated with the actual nozzle # 1 of each head 41, and the horizontal position indicates the position (1 or 2) of the pixel area to be formed by the nozzles used in each head 41. The start nozzle indicates the nozzle with the smallest number among the nozzles that can be used in each head 41 (that is, the nozzle on the back side in the Y direction), and the end nozzle has the number among the nozzles that can be used with each head 41. The largest nozzle (that is, the nozzle on the front side in the Y direction) is shown. The address to the nozzle type indicates the nozzle number of the virtual head to which the actual start nozzle of the head 41 corresponds.

  The printer driver refers to the parameter table regarding the head configuration shown in FIG. 18A in order to create the first head table and the second head table from the virtual head table. The parameter table relating to the head configuration stores the number of nozzles belonging to each head 41, the interval in the Y direction of each head 41, and the number of unused nozzles in the overlapping region. From the table of FIG. 18A, it can be seen that the number of nozzles belonging to the first head 41 (1) is seven, and the number of nozzles belonging to the second head 41 (2) is also seven. Note that this parameter table may be stored in the memory 13 of the printer 1 or the memory of the computer 60.

  In this embodiment, the Y-direction interval (head interval) between the first head 41 (1) and the second head 41 (2) is represented by the number of nozzles. As shown in FIG. 4, the two nozzles (# 6, # 7) at the end of the first head 41 (1) on the front side in the Y direction and the end of the second head 41 (2) on the back side in the Y direction. The two nozzles (# 1, # 2) of the part overlap. Therefore, in the parameter table of FIG. 18A, the head interval is stored as “2”. The first head 41 (1) and the second head 41 (2) do not overlap. For example, the nozzle # 1 of the second head 41 (2) is replaced with the nozzle # 7 of the first head 41 (1). If the nozzle pitch is positioned on the near side in the Y direction, the head interval is set to zero. Further, when the nozzle # 1 of the second head 41 (2) is positioned on the front side in the Y direction by an integer multiple of the nozzle pitch than the nozzle # 7 of the first head 41 (1), the head interval Is a negative number of nozzles.

  When the first head 41 (1) and the second head 41 (2) are overlapped, two overlapping nozzles can be used, and one of the two overlapping nozzles can be used. Only nozzles can be used. Therefore, the number of unused nozzles in the overlapping area is stored in the parameter table in FIG. 18A. In the first head 41 (1), the number of unused nozzles on the near side of the overlapping area is stored as “1”. This means that one nozzle # 7 on the front side in the Y direction among the nozzles # 6 and # 7 in the overlapping area of the first head is set as an unused nozzle. Similarly, in the second head 41 (2), the number of unused nozzles on the far side of the overlapping area is stored as “1”, so the nozzles # 1, # in the overlapping area of the second head 41 (2) are stored. 2, one nozzle # 1 on the back side in the Y direction is an unused nozzle. That is, it is possible to determine whether to use both two overlapping nozzles or only one nozzle based on the number of unused nozzles in the overlapping region.

  FIG. 18B shows a state in which the first head table and the second head table are created from the virtual head table in pass 7 of the normal process. Since the nozzle ## 1 of the virtual head corresponds to the nozzle # 1 of the first head 41 (1), the printer driver stores the head position “8” of the virtual head table in the head position of the first head table. Next, the printer driver determines the second head 41 (2) based on the number of nozzle pitches (2), the number of nozzles belonging to the first head 41 (1) (7), and the number of overlapping nozzles (2). The head position is calculated. The head position of the second head 41 (2) can be calculated by the formula “head position of the first head + number of pitches between nozzles × (number of nozzles belonging to the first head−number of overlapping nozzles)”. In FIG. 18B, the head position of the second head 41 (2) is calculated as “18 {= 8 + 2 × (7-2)}”. Further, the printer driver stores the horizontal position (1 in FIG. 18B) stored in the virtual head table in the first head table and the second head table.

  Next, the printer driver refers to the parameter table of FIG. 18A and determines the start nozzle and the end nozzle based on the number of nozzles belonging to each head 41 and the number of unused nozzles in the overlapping area. In the first head 41 (1), one nozzle # 7 on the front side in the Y direction among the seven nozzles # 1 to # 7 is an unused nozzle. Therefore, in the first head table, the start nozzle is “# 1” and the end nozzle is “# 6”. On the other hand, in the second head 41 (2), one nozzle # 1 on the far side in the Y direction among the seven nozzles # 1 to # 7 is an unused nozzle. Therefore, in the second head table, the start nozzle is “# 2” and the end nozzle is “# 7”.

  Next, the printer driver associates the nozzle number (## i) of the virtual head with the nozzle number (#i) of the actual head 41, and calculates an address to the nozzle type. As shown in FIG. 4, the nozzle numbers (## 1 to ## 12) of the virtual head are the numbers of the second head 41 (2) in order from the nozzle # 1 on the back side in the Y direction of the first head 41 (1). It is added up to nozzle # 7 on the front side in the Y direction. That is, the back side in the Y direction is the reference position. Therefore, the printer driver first determines that the nozzle number (that is, the address to the nozzle type) of the virtual head corresponding to the start nozzle # 1 of the first head 41 (1) corresponds to “## 1”. Therefore, the printer driver stores the address to the nozzle type of the first head table as “## 1”.

  Next, the printer driver calculates the nozzle number of the virtual head corresponding to the start nozzle # 2 of the second head 41 (2). The nozzle number of the virtual head corresponding to the start nozzle #i of the Nth head from the back in the Y direction is expressed by the equation “N−1 total number of nozzles belonging to the first head−total nozzles in the overlapping area up to the Nth head. Number + 1 + (start nozzle # i−nozzle # 1) ”. The nozzle number of the virtual head corresponding to the start nozzle # 2 of the second head is calculated as “## 7 (= 7−2 + 1 + (2-1))”. Therefore, the printer driver stores the address to the nozzle type of the second head table as “## 7”. Thus, the printer driver creates the first head table and the second head table from the virtual head table.

  Thereafter, as shown in FIG. 19B, the printer driver extracts raster data (all or a part) corresponding to the used nozzles of each head 41 from the image data, and rearranges the raster data in the order of transfer to the printer 1. . For this purpose, the computer 60 is provided with a storage area (buffer) for storing raster data of the nozzles # 1 to # 7 for each head 41 (for each nozzle row).

  First, the printer driver refers to the address ### 1 to the start nozzle # 1 and nozzle type of the first head table and the nozzle type of the virtual head table corresponding to the address to the nozzle type. As a result, the printer driver determines that the nozzle # 1 of the first head 41 (1) is the “upper POL nozzle”. Therefore, the printer driver refers to the head position (8) of the first head table, determines that the raster data assigned to the nozzle # 1 of the first head 41 (1) is the eighth raster data, and the image data. The eighth raster data is extracted from the list. Then, the printer driver refers to the horizontal position (1) of the first head table, and determines that nozzle # 1 of the first head 41 (1) forms a dot in the pixel area where the horizontal position is 1, and extracts it. Multiply the raster data by the mask for horizontal position 1. The mask for the horizontal position 1 is changed to data that does not form dots even if the pixel data corresponding to the pixel region having the horizontal position 2 is data that forms dots. Furthermore, nozzle # 1 is an upper POL nozzle. Therefore, it suffices to form dots in a part of the pixel area having a horizontal position of 1, and the printer driver further adds the upper POL to the data obtained by multiplying the eighth raster data by the mask for horizontal position 1. Multiply with a mask. Thereafter, the printer driver stores the masked eighth raster data in the storage area corresponding to the nozzle # 1 of the first head 41 (1).

  In this way, the printer driver sequentially assigns the nozzles of the virtual head indicated by the address to the nozzle type in order from the start nozzle # 1 of the first head 41 (1). The printer driver determines that the nozzle # 2 of the first head 41 (1) next to the start nozzle # 1 corresponds to the nozzle ## 2 of the virtual head, and determines that the nozzle # 2 is also an upper POL nozzle. The raster position corresponding to the actual nozzle #i of the head 41 can be calculated by the formula “head position + number of pitches between nozzles × (nozzle # i−nozzle # 1)”. The raster position corresponding to nozzle # 2 is calculated as “10th raster position (= 8 + 2 × (2-1))”. Therefore, the printer driver extracts the tenth raster data from the image data, and stores the tenth data subjected to the predetermined mask process in the storage area corresponding to the nozzle # 2 of the first head 41 (1). Remember me.

  In this way, the printer driver extracts raster data corresponding to each nozzle from the image data up to the end nozzle # 6, and stores the extracted data in a storage area corresponding to each nozzle. Note that a normal nozzle that is not a POL nozzle is multiplied by only the mask for horizontal position 1 on the extracted raster data, as in data corresponding to nozzle # 2 of the first head 41 (1) shown in FIG. 19B. The printer driver determines that nozzle # 7 is an unused nozzle because the end nozzle is up to nozzle # 6, and forms a dot in the storage area corresponding to nozzle # 7 of first head 41 (1). The data (NULL data) not to be stored is stored. Thus, in pass 7, the rearrangement of data allocated to the nozzles # 1 to # 7 of the first head 41 (1) is completed. Even when the nozzle type stored in the virtual head table is an unused nozzle (for example, nozzle ## 1 in FIG. 9), “NULL data” is stored in the storage area corresponding to the nozzle.

  Similarly, the printer driver rearranges data allocated to the nozzles # 1 to # 7 of the second head 41 (2). Among the nozzles of the second head 41 (2), there is a nozzle set as the lower POL nozzle. The lower POL nozzle is multiplied by the extracted raster data by a lower POL mask different from the upper POL mask so that dots are formed at positions different from the upper POL nozzle.

  With the above processing, the printer driver ends the nozzle allocation processing for pass 7. The data rearranged for each head 41 (FIG. 19B) is transmitted to the printer 1 by the printer driver. The printer 1 controls printing of the first head 41 (1) and the second head 41 (2) in pass 7 based on the received data. As a result, the printing method shown in FIG. 6 can be realized.

  As described above, in the printer 1 having the plurality of heads 41, the virtual head table is created by regarding the plurality of heads 41 as one virtual head, and then the head table corresponding to the actual head 41 is created. 41 nozzle allocation processes can be performed. Further, in order to determine the nozzle to be used, the virtual head is compared with the case where each actual head 41 is compared with the dot formation position in the subsequent pass or compared with the dot formation position registered in the dummy table. The process can be simplified by determining the nozzle to be used. Further, in the virtual head, nozzle numbers are set in order from the nozzles on the back side in the Y direction regardless of the nozzles in the overlapping region (referred to as serial number nozzles). Therefore, even in the printer 1 in which the ends of the heads 41 adjacent in the Y direction overlap, it is not necessary to consider the nozzles in the overlapping area when creating the virtual head table, and the virtual head table creation process is easy. can do.

  In the present embodiment, the printer driver performs the calculation of the number of lower POL nozzles in the lower end transition process, the nozzle allocation process in the lower end process, and the like. Therefore, the computer 60 in which the printer driver is installed and the controller 10 of the printer 1 correspond to the “control unit”, and the printing system in which the printer 1 and the computer 60 are connected corresponds to the “printing apparatus”. However, the present invention is not limited to this, and the controller 10 in the printer 1 may execute the processing of the printer driver. In this case, the controller 10 of the printer 1 corresponds to the control unit (computer), and the printer 1 alone serves as the printing apparatus. Applicable.

=== Modification ===
In the above-described embodiment, the number of the lower POL nozzles in the lower end transition process is calculated by the above-described Expression 1 and Expression 2. Of the nozzles excluding the unusable nozzles in the virtual head, the calculated number of nozzles is set as the lower POL nozzle in order from the nozzle on the near side in the Y direction. Not limited to this, in this modified example, the raster position associated with the lower POL nozzle of the virtual pass that has continued the normal process from the last pass of the normal process and the lower end transition process from the last pass of the normal process are continued. A comparison process is performed with the raster position associated with the actual use nozzle in the pass, and the actual use nozzle in the pass that matches the position is set as the lower POL nozzle.

  For example, as shown in FIG. 14A, the printer driver assumes a virtual pass 14 ′ in which normal processing is continued from the last pass 13 of normal processing, and lower POL nozzles ## 11 and ## 12 in the virtual pass 14 ′. Raster positions L63 and L65 associated with are calculated. Next, the printer driver calculates each raster position of the used nozzles of the actual pass 14 that has been transitioned from the last pass 13 of the normal processing in the lower end transition processing, and is associated with the lower POL nozzle of the virtual pass 14 ′. Compare with positions L63 and L65. As a result, if there is a nozzle with a matching position, the nozzle is set as the lower POL nozzle. In FIG. 14A, since the raster position associated with the nozzle ## 11 and nozzle ## 12 in the actual pass 14 matches the raster position associated with the lower POL nozzle in the virtual pass 14 ′, the printer driver uses the nozzle #. It can be determined that # 11 and ## 12 should be set to the lower POL nozzle. However, nozzle ## 12 outside the printing area is an unused nozzle.

  Similarly, in the next pass, as shown in FIG. 14B, the printer driver assumes a virtual pass 15 ′ in which normal processing is continued after the virtual pass 14 ′, and the lower POL nozzle in the virtual pass 15 ′. Raster positions L68 and L70 associated with ## 11 and ## 12 are calculated. Next, the raster positions associated with the used nozzles of the actual pass 15 in which the lower end transition processing is continued from the actual pass 14 are calculated, and the raster positions L68 and L70 associated with the lower POL nozzles of the virtual pass 15 ′. Compare with As a result, in FIG. 14B, the raster position of the nozzle ## 12 in the actual pass 15 matches the raster position of the lower POL nozzle in the virtual pass 15 '. Therefore, the printer driver can determine that it is only necessary to set the nozzle ## 12 of the actual pass 15 as the lower POL nozzle. However, nozzle ## 12 is a nozzle outside the printing region.

  As described above, the comparison process between the raster position associated with the lower POL nozzle of the virtual pass for which the normal process has been continued in the lower end transition processing area and the raster position associated with the used nozzle in the actual lower end transition process pass is performed. May be used to set the lower POL nozzle for the lower end transition process. Also in this case, the POL raster and the normal raster can be regularly formed in the lower end print area as in the normal print area.

  However, the processing time of the printer driver can be shortened by calculating the number of the lower POL nozzles for the lower end transition processing and setting the lower POL nozzles according to Equations 1 and 2 as in the above-described embodiment. Therefore, the scheduling table creation time can be shortened and printing can be started early.

=== Nozzle assignment processing in another printing method ===
<Another printing method>
FIG. 20 is a diagram illustrating a printing method of another comparative example that does not have a migration process. For the sake of explanation, the number of nozzles belonging to a virtual head obtained by combining a plurality of heads 41 is assumed to be 11. In the figure, the nozzle pitch is 2D, and the inter-nozzle pitch is D. In normal processing, the transport amount of the head unit 40 is set to 5D, one nozzle ## 1 on the rear side in the Y direction is set as the upper POL nozzle (▲), and one nozzle ## 11 on the front side in the Y direction is set as the lower POL. Nozzle (■). In order to reduce the amount of protrusion of the head unit 40 with respect to the medium at the start and end of printing, upper end processing and lower end processing are performed. Let D be the transport amount of the head unit 40 in the upper end process and the lower end process.

  Here, it is assumed that nozzle ## 6 is a defective nozzle and has different ejection characteristics from the other nozzles. In the upper end process and the lower end process, the transport amount of the head unit 40 is short, and in the printing method of this comparative example, raster lines associated with the defective nozzle ## 6 are continuously arranged in the Y direction. For example, in the upper end printing area, the defective nozzle ## 6 is associated with the fifth raster position (L5) to the seventh raster position (L7). In the lower end printing area, the defective nozzle ## 6 is associated with the raster position 52 (L54) from the raster position 52 (L52). As described above, when raster lines associated with defective nozzles are continuously arranged, the portions are conspicuous, and the image quality of the printed image is deteriorated. For example, when the nozzle ## 6 is a non-ejection nozzle, the portion of the raster position where the nozzle ## 6 is continuously associated appears as a light colored streak on the image.

  FIG. 21 is a diagram illustrating another printing method according to the present embodiment. Similar to the printing method of FIG. 6 described above, a transition process (upper end transition process) is provided between the upper end process and the normal process, and a transition process (lower end transition process) is provided between the normal process and the lower end process. . In the normal process, the transport amount of the head unit 40 is set to 5D, nozzle ## 1 is set as the upper POL nozzle, and nozzle ## 11 is set as the lower POL nozzle. The conveyance amount for the upper end process and the lower end process is D. Then, the transport amount 3D of the upper end transition process and the lower end transition process is a transport amount between the transport amount 5D of the normal process and the transport amount D of the upper end / lower end process.

  In the printing method of FIG. 6 described above, when the process shifts from the normal process to the lower edge transition process (pass 14 in FIG. 6), the print end position is aligned, whereas in the printing method of FIG. When shifting from the lower end transition process to the lower end process (pass 17 in FIG. 20), alignment to the print end position is performed. In the printing method of FIG. 21, the upper POL nozzle is not set in the upper end transition process, and the lower POL nozzle is not set in the lower end transition process. However, the upper end transition processing nozzle which is the opposite of the normal processing upper POL nozzle (▲) is set as the lower POL nozzle, and the lower end transition processing nozzle which is the opposite of the normal processing lower POL nozzle (■) is the upper POL nozzle. Set to.

  By providing the transition process, the nozzles of the transition process are also associated with the raster position with which the defective nozzle ## 6 is associated with the upper end / lower end process. Then, in the upper end printing region of the printing method of FIG. 21, the nozzles in the subsequent passes are set as the use nozzles with priority, and the nozzles in the upper end transition process are set as the use nozzles with priority over the nozzles in the upper end process ( Note that the nozzle for the normal process is set as the used nozzle in preference to the nozzle for the upper end transition process). On the other hand, in the lower end printing area, the nozzles in the previous pass are preferentially set as the used nozzles, and the nozzles in the lower end transition process are set as the used nozzles in preference to the nozzles in the lower end process (note that the lower end transition process Nozzle of normal processing is prioritized over the nozzle of the present, and is set as the used nozzle).

  For example, among the nozzles ## 6, ## 5, and ## 2 associated with the fifth raster position (L5), the nozzle “## 5” for the upper end process and the nozzle “## 2” for the upper end transition process are included. Among the nozzles ## 7, ## 6, ## 4, and ## 1 that are set as the use nozzles and are associated with the sixth raster position (L6), the nozzles “## 4, ## 1” of the upper end transition process "Is set as the nozzle to be used. Similarly, in the lower end printing area, the nozzles “## 9, ## 6” of the lower end transition process are used among the nozzles ## 9, ## 6, ## 5 associated with the 53rd raster position (L53). Among the nozzles ## 11, ## 8, ## 6, and ## 5 that are set as the nozzles and correspond to the 54th raster position (L54), the nozzles “## 11, ## 8” of the lower end transition process Is set as the nozzle to be used. As described above, in the printing method of FIG. 21, the defective nozzles ## 6 are not continuously associated with the raster positions arranged continuously.

  In summary, in the printing method of FIG. 21, between the upper end / lower end process and the normal process, the transport amount (3D) between the upper end / lower end process transport amount (D) and the normal process transport amount (5D). ) And the transition process nozzles (and the normal process nozzles) are preferentially set as the use nozzles over the upper end / lower end process nozzles. In the upper end / lower end processing, since the transport amount is short, the same nozzle is associated with successive raster positions. On the other hand, in the transfer process, since the carry amount is longer than the carry amount in the upper end / lower end process, different nozzles are associated with successive raster positions. That is, compared with the printing method of the comparative example, the printing method of FIG. 21 can increase the number of nozzles that can be used to form each raster line. Then, by setting the nozzle for transition processing (and the nozzle for normal processing) as the use nozzle with priority over the upper end / lower end processing, the probability that nozzles associated with successive raster positions will be different nozzles increases. . That is, in the upper end printing area and the lower end printing area, it is possible to prevent the defective nozzles (here, nozzle ## 6) from being continuously associated as the use nozzles with the raster positions arranged continuously. In other words, defective nozzles associated with continuously arranged raster positions can be set as unused nozzles (◯) that are not used for printing. As a result, it is possible to suppress the raster lines printed by the defective nozzles from being continuously arranged, and it is possible to suppress the image quality deterioration of the printed image. In other words, it is possible to reduce the use ratio of defective nozzles when forming each raster line, to form a raster line having the same density as other raster lines, and to deteriorate the image quality of the printed image. Can be suppressed.

<Nozzle assignment processing for lower end transition processing and lower end processing>
As in the previous embodiment, the printer driver creates a virtual head table when creating print data, and performs pixel data extraction and rearrangement processing based on the virtual head table. In the upper end processing and upper end transition processing (and normal processing) of the printing method shown in FIG. 21, the nozzles in the subsequent passes are preferentially set as the use nozzles. Therefore, when the printer driver creates the virtual head table for the upper end process and the upper end shift process, the raster position and the horizontal position associated with the used nozzles of the corresponding pass, as in the above-described embodiment (for example, FIG. 8). And the raster position and the horizontal position associated with the used nozzles of the subsequent passes are compared, and the nozzles of the corresponding passes whose positions match may be set as unused nozzles. Also, when creating a virtual head table for normal processing, it may be created with reference to a virtual head information table (for example, FIG. 7), as in the previous embodiment.

  FIG. 22A shows a dummy table used when creating the scheduling table for the lower end transition process, and FIG. 22B shows a dummy table used when creating the scheduling table for the lower end process. Similar to the above-described embodiment, the printer driver creates a scheduling table related to the lower-end transition process and the lower-end process before starting printing. For this purpose, as shown in FIG. 22A, the dot positions formed when the normal process is continued after the last pass 12 of the normal process are registered in the dummy table. At this time, the nozzle ## 11 corresponding to the lower POL nozzle in the normal processing is set as an unused nozzle so that the dots are not formed in a double manner. Then, the printer driver compares the dot positions that can be formed by the nozzles used for the lower end transition process with the dot positions registered in the dummy table, determines the nozzle for the lower end transition process that matches the position as the used nozzle, and sets the scheduling table. Create Also, the data with the matching position is deleted from the dummy table.

  Thereafter, the printer driver creates a virtual head table based on the scheduling table. At the time of creating the virtual head table, the printer driver sets the nozzle for the lower end transition process, which is the opposite of the lower POL nozzle for the normal process, to the upper POL nozzle. In the printing method of FIG. 21, the lower POL nozzle is not set in the lower end transition process. For this reason, the processing for calculating the number of lower POL nozzles as in the above-described embodiment (FIG. 14) is not performed.

  Thereafter, when creating the scheduling table for the lower end process, the printer driver is formed when the normal process is shifted after the last pass 12 of the normal process, as shown in the left diagram of FIG. 22B. The dot position is registered in the dummy table. The dot positions registered in the dummy table are dot positions to be formed by the lower end transition process and the lower end process. Thereafter, the printer driver deletes the dot position data (center part of FIG. 22B) formed by the lower edge transition process from the dummy table of the left figure of FIG. 22B, and creates the dummy table of the right figure of FIG. 22B. .

  Then, the printer driver compares the dot positions that can be formed with the nozzles used for the lower end processing with the dot positions registered in the dummy table in the right diagram of FIG. Determine and create a scheduling table. Thereafter, the printer driver creates a virtual head table based on the scheduling table.

  In the printing method of FIG. 21, the lower POL nozzle is not set in the lower end transition process. For this reason, after deleting the data of the center diagram of FIG. 22B from the dummy table of the left diagram of FIG. 22B, the process of restoring the dot position formed by the lower POL nozzle in the lower end transition process to the dummy table is not performed.

=== Other Embodiments ===
Each of the above embodiments is described mainly for a printing system having an ink jet printer, but includes disclosure of a method for creating print data. The above-described embodiments are for facilitating understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the printer>
In the above-described embodiment, the operation of forming an image while moving the head unit 40 in the medium conveyance direction and the operation of moving the head unit 40 in the paper width direction are repeated on the continuous paper conveyed to the printing area. However, the present invention is not limited to this. For example, a printer that forms an image and then transports a medium portion that has not yet been printed to a printing area is exemplified. For example, a printer that repeats an operation of forming an image on a cut sheet while moving the head in the moving direction and an operation of transferring the cut sheet to the head in a conveying direction that intersects the moving direction may be used. In the above-described embodiment, as shown in FIG. 3, the printer 1 having a plurality of heads 41 is taken as an example. However, the present invention is not limited to this, and the head 41 may be a single printer. If the head 41 is a single printer, it is not necessary to perform the nozzle assignment process by regarding the plurality of heads 41 as one virtual head as shown in FIG.

1 Printer, 10 Controller, 11 Interface section,
12 CPU, 13 memory, 14 unit control circuit,
20 transport units, 21 transport rollers,
30 drive unit, 31 X-axis stage, 32 Y-axis stage,
40 head units, 41 heads,
50 detector groups, 60 computers

Claims (8)

(A) a head including a nozzle row in which nozzles that eject ink to a medium are arranged in a predetermined direction;
(B) an image forming operation for ejecting ink from the nozzle while relatively moving the relative position of the medium and the head in a direction intersecting the predetermined direction based on the print data; and the relative of the head to the medium An operation for moving the position in one direction of the predetermined direction repeatedly,
(B1) Between the upper end process that prints the upper end part that is the end of the medium in the other direction in the predetermined direction, and the normal process that prints the center part of the medium in the predetermined direction, and the normal process And a lower end process for printing a lower end portion that is an end portion on the one direction side in the predetermined direction of the medium, the relative movement amount of the head with respect to the medium in the predetermined direction is the upper end process and the upper end process. When creating print data of a printing method that implements a transition process that is greater than or equal to the relative movement amount of the lower end process and less than or equal to the relative movement amount of the normal process,
(B2) After the normal process, not the lower end transition process that is the transition process between the normal process and the lower end process, but the dots that can be formed by the nozzles when the normal process is continued on the medium Calculate the virtual position that is the position at
When the lower end transition process is continued after the normal process, an actual position that is a position on the medium of dots that can be formed by the nozzle is calculated,
The virtual position and the actual position are compared, and the nozzle in the lower end transition process that can form dots at a position that matches the virtual position is set as a use nozzle used for printing,
(B3) a control unit that assigns pixel data constituting image data to the nozzles to be used and creates the print data;
A printing apparatus comprising (C). The printing apparatus according to claim 1,
The controller is
The nozzle for the upper end transition process, which is the transition process between the upper end process and the normal process, rather than the nozzle for the upper end process capable of forming dots at a certain position on the medium. The nozzle capable of forming a dot at a position is preferentially set as the use nozzle,
The nozzle for the normal process capable of forming a dot at the certain position is set as the use nozzle preferentially over the nozzle for the upper end transition process capable of forming a dot at the certain position,
The nozzle for the lower end transition process capable of forming dots at the different position is set as the used nozzle with priority over the nozzle for the lower end process capable of forming dots at another position on the medium. ,
Setting the nozzle in the normal process capable of forming dots in the different position as the used nozzle preferentially over the nozzle in the lower end transition process capable of forming dots in the different position;
Printing device. The printing apparatus according to claim 1 or 2, wherein
After the normal process, when the normal process is continued instead of the lower edge transition process, the virtual position that is a position on the medium of dots that can be formed by the nozzle is stored in a table,
After the virtual position stored in the table is deleted from the table, the virtual position that coincides with the position on the medium of the dots formed by the nozzles used in the lower end transition process,
Comparing the virtual position stored in the table with the position on the medium of the dot that can be formed by the nozzle in the lower end processing, the lower end capable of forming a dot at a position that matches the virtual position Set the nozzle of the process to the nozzle used;
Printing device. The printing apparatus according to claim 3,
A printing method that performs the transition process between the upper end process and the normal process, and between the normal process and the lower end process,
The upper end nozzle that is an end nozzle on the other direction side in the predetermined direction of the nozzle row intersects with the lower end nozzle that is an end nozzle on the one direction side in the predetermined direction of the nozzle row. When creating print data of a printing method that forms dot rows along the direction,
Of the virtual positions stored in the table, after deleting from the table the virtual position that coincides with the position on the medium of the dots formed by the nozzles used in the lower edge transition process, the lower edge The position on the medium of the dot formed by the lower end nozzle of the transfer process is stored in the table,
Setting the used nozzle of the lower end processing as the upper end nozzle capable of forming a dot at the same position as the position on the medium of the dot formed by the lower end nozzle of the lower end transition processing;
Printing device. The printing apparatus according to any one of claims 1 to 4, wherein:
The position on the medium of dots that can be formed by the nozzles in a certain image forming operation of the upper end transition process, which is the transition process between the upper end process and the normal process, and the certain image formation of the upper end transition process Compare the position on the medium of the dots that can be formed by the nozzle in the image forming operation after the operation,
Setting the nozzle of the certain image forming operation of the upper end transition process capable of forming dots at the matching position to an unused nozzle that is not used for printing;
Printing device. The printing apparatus according to any one of claims 1 to 5, wherein
A plurality of the heads are arranged side by side in the predetermined direction,
Storing the number of nozzles that is the number of the nozzles belonging to the nozzle row included in each of the heads, and the head interval that is the interval between the plurality of heads in the predetermined direction;
The controller is
The plurality of heads are regarded as one virtual head, the nozzles of the virtual head used for printing during a certain image forming operation, and the positions on the medium of dots formed by the nozzles during the certain image forming operation ,
Based on the number of nozzles and the head interval, each nozzle of the actual head is associated with the nozzle of the virtual head, and formed by the actual nozzle of the head during the certain image forming operation. Obtaining the position of the dot on the medium;
Based on the acquired position, the pixel data used for printing during the certain image forming operation is extracted from the image data, and the print data for executing the certain image forming operation is created.
Printing device. (A) The ink is ejected from the nozzle while the relative position between the head having the nozzle row in which the nozzles that eject ink to the medium are arranged in a predetermined direction and the medium are relatively moved in the direction intersecting the predetermined direction. A program for causing a computer to create print data of a printing apparatus that repeatedly executes an image forming operation and an operation of moving the relative position of the head with respect to the medium in one direction of the predetermined direction,
(B) Between the upper end process that prints the upper end part that is the end part on the other direction side of the medium in the predetermined direction and the normal process that prints the center part of the medium in the predetermined direction, and the normal process And a lower end process for printing a lower end portion that is an end portion on the one direction side in the predetermined direction of the medium, the relative movement amount of the head with respect to the medium in the predetermined direction is the upper end process and the upper end process. When creating print data of a printing method that implements a transition process that is greater than or equal to the relative movement amount of the lower end process and less than or equal to the relative movement amount of the normal process,
(C) After the normal process, not the lower end transition process that is the transition process between the normal process and the lower end process, but the dots that can be formed by the nozzles when the normal process is continued on the medium Calculating a virtual position that is a position at
(D) When the lower end transition process is continued after the normal process, calculating an actual position that is a position on the medium of dots that can be formed by the nozzle;
(E) Comparing the virtual position with the actual position, and setting the nozzle in the lower end transition process capable of forming dots at a position coinciding with the virtual position as a use nozzle used for printing When,
(F) assigning pixel data constituting image data to the use nozzles to create the print data;
A program for causing a computer to execute (G). (A) The ink is ejected from the nozzle while the relative position between the head having the nozzle row in which the nozzles that eject ink to the medium are arranged in a predetermined direction and the medium are relatively moved in the direction intersecting the predetermined direction. A printing apparatus that repeatedly executes an image forming operation and an operation of moving a relative position of the head with respect to the medium in one direction of the predetermined direction;
(B) Between the upper end process that prints the upper end part that is the end part on the other direction side of the medium in the predetermined direction and the normal process that prints the center part of the medium in the predetermined direction, and the normal process And a lower end process for printing a lower end portion that is an end portion on the one direction side in the predetermined direction of the medium, the relative movement amount of the head with respect to the medium in the predetermined direction is the upper end process and the upper end process. A printing method for performing a transition process that is equal to or greater than the relative movement amount of the lower end process and equal to or less than the relative movement amount of the normal process,
(C) After the normal process, not the lower end transition process that is the transition process between the normal process and the lower end process, but the dots that can be formed by the nozzles when the normal process is continued on the medium Calculating a virtual position that is a position at
When the lower end transition process is continued after the normal process, calculating an actual position that is a position on the medium of dots that can be formed by the nozzle;
Comparing the virtual position with the actual position, and setting the nozzle in the lower end transition process capable of forming dots at a position that matches the virtual position as a use nozzle used for printing;
Discharging ink from the nozzles based on print data created by allocating pixel data constituting image data to the used nozzles;
A printing method characterized by comprising:

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