JP2001080081A - Inspection of print head having a plurality of nozzle arrays and manufacture of printer - Google Patents

Abstract

(57) [Problem] To provide a printing apparatus capable of performing high-quality printing in consideration of an ink landing position error due to a manufacturing error of a print head. SOLUTION: A first plurality of dot rows formed respectively by using a plurality of nozzle rows of a target print head to be inspected are inspected, and a positional deviation of the first plurality of dot rows in the main scanning direction is determined. The measurement determines the inter-column landing error for the target print head. In addition, the second plurality of dot rows formed using the plurality of nozzle rows of the target print head are inspected, and the dots in the main scanning direction in each dot row of the second plurality of dot rows are mutually inspected. By measuring the misalignment, the in-row impact error for the target printhead is determined. Then, the pass / fail of the target print head is determined based on the inter-row impact error and the in-row impact error,
Assemble the printing device using the passed print head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to inspection of a print head having a plurality of nozzle arrays for ejecting ink, and manufacturing of a printing apparatus using the print head.

[0002]

2. Description of the Related Art In recent years, as an output device of a computer,
A color printer that discharges several colors of ink from a head is widely used. Such a color printer usually includes a print head having a plurality of nozzle rows for discharging a plurality of inks.

[0003]

In printing, dots are formed on a print medium by ink ejected from a print head. At this time, the ink landing position may deviate considerably from the ideal position (design position) due to a manufacturing error of the print head. It is not preferable to use a print head having a large ink landing position error because the image quality deteriorates.

The present invention has been made to solve the above-mentioned problems in the prior art, and can perform high-quality printing in consideration of an error in ink landing position due to a manufacturing error of a print head. It is an object to provide a print head and a printing device.

[0005]

SUMMARY OF THE INVENTION In order to solve at least a part of the above-mentioned problems, according to the present invention, a plurality of nozzle arrays formed using a plurality of nozzle arrays of a target print head to be inspected are provided. Inspection of one of the plurality of dot rows and measurement of positional deviation between the first plurality of dot rows in the main scanning direction determine an inter-column landing error for the target print head. In addition, the second plurality of dot rows formed using the plurality of nozzle rows of the target print head are inspected, and the dots in the main scanning direction in each dot row of the second plurality of dot rows are mutually inspected. By measuring the misalignment, the in-row impact error for the target printhead is determined. Then, the print head is inspected by determining whether or not the target print head is acceptable based on the inter-row impact error and the in-row impact error. A print head that passes this inspection is used for assembling the printing apparatus.

[0006] The inter-row landing error and the in-row landing error represent an error in the position of the dot on the print medium. Therefore,
By assembling a printing apparatus using one having these errors within an allowable range, it is possible to obtain a printing apparatus capable of performing high-quality printing.

[0007] As a criterion, there are a first criterion for judging the acceptability of a first type of print head which ejects a single density ink for each of a plurality of hues;
A second determination criterion for determining the acceptability of a second type of print head that ejects a plurality of types of inks having substantially the same hue and different densities for at least one hue may be set. At this time, for the target print head, a pass / fail determination as the first type print head according to a first determination criterion, and a pass / fail determination as the second type print head according to a second determination criterion, Execute

In this case, it is possible to determine and use a print head suitable for each of two types of print heads having different purposes.

It is preferable that the second criterion is set to have a narrower allowable range than the first criterion.

In a so-called halftone region (a relatively low-density image region having a density of about 50% or less), image quality deterioration due to misalignment of dots formed by relatively low-density ink tends to be conspicuous. Therefore, the second type of print head using a plurality of types of inks having substantially the same hue and different densities is more permissible than the determination standard for the first type of print head using a single density of ink for each hue. Is set narrow, it is possible to suppress the image quality deterioration without significantly reducing the yield of the print head.

The present invention can be realized in various modes such as a method of manufacturing a printing apparatus and a method of inspecting a print head.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described based on examples in the following order. A. Configuration of printing device: Occurrence of printing position shift between nozzle arrays: Example steps: Modified example

A. Configuration of Printing Apparatus: FIG. 1 is a schematic configuration diagram of a printing system including an inkjet printer 20 as an embodiment of the present invention. The printer 20 includes a sub-scanning feed mechanism that conveys the printing paper P in the sub-scanning direction by a paper feed motor 22, and a carriage motor 24 that moves the carriage 30 in the axial direction of the platen 26 (main scanning direction).
A main scanning feed mechanism for reciprocating the head, a head driving mechanism for driving a print head unit 60 (also referred to as a “print head assembly”) mounted on the carriage 30 to control ink ejection and dot formation, and Paper feed motor 22, carriage motor 24, print head unit 60
And a control circuit 40 for exchanging signals with the operation panel 32. The control circuit 40 includes a connector 56
Is connected to the computer 88 via the.

The sub-scan feed mechanism for conveying the printing paper P includes:
A gear train (not shown) for transmitting the rotation of the paper feed motor 22 to the platen 26 and a paper transport roller (not shown) is provided. The main scanning feed mechanism for reciprocating the carriage 30 includes an endless drive belt 36 provided between the carriage motor 24 and a slide shaft 34 erected in parallel with the axis of the platen 26 and slidably holding the carriage 30. And a position sensor 39 for detecting the origin position of the carriage 30.

FIG. 2 is a block diagram showing the configuration of the printer 20 with the control circuit 40 at the center. Control circuit 40
Is a CPU 41 and a programmable ROM (PROM)
43, a RAM 44, and a character generator (CG) 45 storing a character dot matrix. This control circuit 4
Reference numeral 0 further denotes an I / F dedicated circuit 50 for exclusively interfacing with an external motor or the like, and a head drive circuit 52 connected to the I / F dedicated circuit 50 for driving the print head unit 60 to eject ink. And paper feed motor 2
2 and a motor drive circuit 54 for driving the carriage motor 24. The I / F dedicated circuit 50 has a built-in parallel interface circuit.
Print signal PS supplied from the computer 88 via the
Can receive.

FIG. 3 is an explanatory diagram showing the configuration of the print head unit 60. As shown in FIG. 3, the print head unit 60 has a substantially L-shape, and is capable of mounting a black ink cartridge and a color ink cartridge (not shown), and a partition plate for partitioning both cartridges. 31 are provided.

On the upper end surface of the print head unit 60, a head ID seal 100 indicating head identification information (also referred to as "head ID") assigned in advance according to the characteristics of the print head unit 60 is attached. The contents of the head ID displayed on the head ID seal 100 will be described later.

The entire configuration of FIG. 3 including the print head 28 and the mounting portion of the ink cartridge is referred to as a "print head unit 60" because the print head unit 60 is attached to and detached from the printer 20 as one component. Because. That is, when the print head 28 is to be replaced, the print head unit 60 is replaced.

At the bottom of the print head unit 60, an introduction pipe 71 for guiding ink from an ink container to the print head 28 is provided.
To 76 are erected. When the black ink cartridge and the color ink cartridge are mounted on the print head unit 60 from above, the introduction pipes 71 to 76 are inserted into the connection holes provided in each cartridge.

FIG. 4 is an explanatory diagram for explaining a mechanism for discharging ink. When the ink cartridge is mounted on the print head unit 60, the ink in the ink cartridge is sucked out through the introduction pipes 71 to 76, and is provided below the print head unit 60 as shown in FIG. It is guided to the print head 28.

The print head 28 has a plurality of nozzles n provided in a row for each color, and an actuator circuit 90 for operating a piezo element PE provided for each nozzle n. The actuator circuit 90 is a part of the head drive circuit 52 (FIG. 2), and controls on / off of a drive signal given from a drive signal generation circuit (not shown) in the head drive circuit 52. That is, the actuator circuit 90
Latches data indicating ON (discharges ink) or OFF (does not discharge ink) for each nozzle according to the print signal PS supplied from the computer 88, and outputs a drive signal to the piezo element PE only for ON nozzles. Is applied.

FIG. 5 is an explanatory diagram showing the principle of driving the nozzle n by the piezo element PE. The piezo element PE is installed at a position in contact with the ink passage 80 that guides ink to the nozzle n. In the present embodiment, by applying a voltage having a predetermined time width between the electrodes provided at both ends of the piezo element PE, the piezo element PE rapidly expands as shown in FIG. Deform one side wall. As a result, the volume of the ink passage 80 contracts in accordance with the expansion of the piezo element PE, and the ink corresponding to the contraction becomes particles Ip and is discharged at high speed from the tip of the nozzle n.
The paper P on which the ink particles Ip are mounted on the platen 26
, The printing is performed.

FIG. 6 is an explanatory diagram showing the correspondence between a plurality of rows of nozzles provided on the print head 28 and a plurality of actuator chips. The printer 20 performs printing using six color inks of black (K), dark cyan (C), light cyan (LC), dark magenta (M), light magenta (LC), and yellow (Y). A nozzle array for each ink. Note that dark cyan and light cyan are cyan inks having substantially the same hue and different densities. The same applies to dark magenta ink and light magenta ink.

The actuator circuit 90 includes a first actuator chip 91 for driving the black nozzle row K and the dark cyan nozzle row C, and a second actuator chip 92 for driving the light cyan nozzle row LC and the dark magenta nozzle row M. , Light magenta nozzle row LM and yellow nozzle row Y
And a third actuator chip 93 for driving the same.

FIG. 7 is an exploded perspective view of the actuator circuit 90. Three actuator chips 91 to 93
Are adhered on the laminate of the nozzle plate 110 and the reservoir plate 112 with an adhesive. The connection terminal plate 1 is provided on the actuator chips 91 to 93.
20 is fixed. An external circuit (specifically, the I / F dedicated circuit 50 in FIG. 2) is provided at one end of the connection terminal plate 120.
An external connection terminal 124 for electrical connection with is formed. On the lower surface of the connection terminal plate 120, an internal connection terminal 122 for electrical connection with the actuator chips 91 to 93 is provided. Further, a driver IC 126 is provided on the connection terminal plate 120. In the driver IC 126, a circuit for latching a print signal given from the computer 88, an analog switch for turning on / off a drive signal in accordance with the print signal, and the like are provided. The driver IC 12
The wiring between the terminal 6 and the connection terminals 122 and 124 is not shown.

FIG. 8 is a partial sectional view of the actuator circuit 90. Here, the first actuator chip 9
1 and only the cross section of the connection terminal plate 120 thereabove, the other actuator chips 92 and 93 have the same structure as the first actuator chip 91.

The nozzle plate 110 has nozzle openings for each ink. Reservoir plate 112
Is a plate-like body for forming an ink storage section (reservoir). The actuator chip 91 is connected to the ink passage 8.
0 (FIG. 5), a piezo element PE disposed above the ceramic sintered body 130 via a wall surface, and a terminal electrode 132. When the connection terminal plate 120 is fixed on the actuator chip 91, the connection terminals 122 provided on the lower surface of the connection terminal plate 120 are provided.
And the terminal electrode 132 provided on the upper surface of the actuator chip 91 are electrically connected. The wiring between the terminal electrode 132 and the piezo element PE is not shown.

B. Occurrence of printing position shift between nozzle rows: When bidirectional printing is performed using the color printer 20, printing position shift may occur between nozzle rows. First, the occurrence of such a shift in the recording position between the nozzle rows will be described below.

FIG. 9 is an explanatory diagram showing the positional deviation during bidirectional printing for different nozzle arrays. The nozzle n moves bidirectionally and horizontally above the printing paper P, and forms a dot on the printing paper P by discharging ink on each of the outward path and the homeward path. Here, the case where the black ink K is ejected and the case where the cyan ink C is ejected are illustrated in an overlapping manner. Black ink K
Is assumed to be ejected vertically downward at an ejection speed V _K , while cyan ink C is assumed to be ejected at a lower ejection speed V _C than black ink. The combined speed vectors CV _K and CV _C of the respective inks are the downward ejection speed vector and the main scanning speed vector V of the nozzle n.
and s. The black ink K and the cyan ink C have different downward ejection speeds V _K and V _C , and therefore the magnitudes and directions of the combined speeds CV _K and CV _C are different from each other.

In this example, regarding the black dot,
Correction is made so that the positional deviation in bidirectional printing becomes zero. However, the synthetic velocity vector CV _C of the cyan ink _C
Is different from the composite speed vector CV _K of the black ink K, and if the cyan ink C is ejected at the same timing as the black ink K, a large deviation occurs on the printing paper P with respect to the recording position of the cyan dot. In addition, it can be seen that the relative positional relationship (the left-right relationship) between the black dot and the cyan dot on the outward route is opposite to the positional relationship on the backward route.

FIG. 10 is a plan view showing a deviation of the recording position shown in FIG. Here, a case is shown in which vertical ruled lines along the sub-scanning direction y are recorded on the outward path and the return path using the black ink K and the cyan ink C, respectively. The vertical ruled line recorded on the outward pass using black ink has a position in the main scanning direction x that matches the vertical ruled line recorded on the return pass. On the other hand, the vertical ruled line recorded on the outward path using cyan ink is recorded on the right side of the black vertical ruled line, and the vertical ruled line recorded on the return path is recorded on the left side of the black vertical ruled line.

As described above, when the deviation between the recording positions in the forward path and the return path is corrected only for the black nozzle row, the deviation in the recording position may not be corrected properly for the other nozzle rows.

The ejection speed of ink droplets ejected from each nozzle row changes depending on various factors as described below. (1) Manufacturing error of the actuator chip. (2) Physical properties (eg, viscosity) of the ink. (3) Ink drop weight.

When the main factor of the ejection speed of the ink droplet is a manufacturing error of the actuator chip, the ejection speed of the ink droplet ejected from the same actuator chip is almost the same. Therefore, in this case, it is preferable to correct the deviation of the recording position in the main scanning direction for each group of nozzle rows driven by different actuator chips.

On the other hand, if the physical properties of ink and the weight of ink droplets also have a significant effect on the ejection speed, the deviation of the dot recording position in the main scanning direction is determined for each ink or nozzle row. It is preferable to correct.

In many cases, two factors, the manufacturing error of the actuator chip and the weight of the ink droplet, are considered to be the main factors of the ejection speed of the ink droplet. The weight of the ink drop is
By appropriately shaping the drive waveform supplied to the piezo element, it is possible to control the amount to an appropriate amount. Therefore, in the present embodiment, as described below, the deviation of the recording position due to the manufacturing error of the actuator chip is measured, and the pass / fail judgment of the print head unit 60 is performed.

C. Steps of Embodiment: FIG. 11 is a flowchart showing a procedure for inspecting a print head unit and assembling it to a printing apparatus according to an embodiment of the present invention. In Step T1, the print head unit 60 (FIG. 3) is attached to the head inspection device.

FIG. 12 is a conceptual diagram showing the head inspection apparatus 300. The head inspection apparatus 300 includes a stage 302 simulating a platen of a printer, and a stage 302.
Transport roller 3 for transporting printing paper P moving above
04, 306, CCD camera 310, control device 33
0. The print head unit 60 and the CCD camera 310 are connected to the stage 302 by the support unit 320.
Is fixed above.

The control device 330 is composed of a general computer system including a CPU and a memory. The control device 330 supplies a drive signal to the print head unit 60 to eject ink to print a test pattern on the printing paper P. And a function of causing the CCD camera 310 to image the test pattern. An image processing unit 33 that performs image processing on the captured test pattern image
It also has a function as 2.

When the print head unit 60 is mounted on the support 320, the distance PG between the lower surface of the nozzle plate 110 (ie, the surface of the nozzle hole) and the stage 302 is determined by the distance between the nozzle plate 110 of the printer 20 and the platen. 26 (FIG. 1). This distance PG is called a “platen gap”.

At step T2 in FIG. 11, the landing error between columns is measured. FIG. 13 is a flowchart showing the procedure for measuring the landing error between rows. In step T21, first,
Print a test pattern for measuring the landing error between rows.

FIG. 14 shows a test pattern for measuring the landing error between columns. This test pattern is composed of six dot rows. When printing the test pattern, the six nozzle arrays shown in FIG. 6 are used one by one while moving the printing paper P at a constant speed Vs in the main scanning direction x of the head inspection device 300 (FIG. 12). Then, at predetermined time intervals, the ink is simultaneously ejected from the 48 nozzles in each row. Since the nozzles in each row are arranged at a nozzle pitch of several dots in the sub-scanning direction y, 48 dots recorded by one row of nozzles are arranged at substantially constant intervals along the sub-scanning direction y. I have. The ink droplets may be simultaneously ejected from the six nozzle arrays without a time interval between the ink ejections of the nozzle arrays.

The test pattern shown in FIG. 14 is printed using one type of ink (eg, cyan ink) in common for six nozzle rows. However, even when inspecting the head,
The same ink (that is, black, cyan, light cyan, magenta, light magenta, and yellow) supplied to each nozzle row when mounted on the printer 20
May be supplied to each nozzle row.

The size of the dots constituting the test pattern is preferably the dot size most frequently used in a halftone area (image area having a density of about 10 to about 50%). The reason for this is that image quality deterioration due to a landing position shift is most noticeable in a halftone area. For example, it is possible to form small dots, medium dots, and large dots with different sizes at each pixel position using one nozzle, and the medium dots are most frequently used in the halftone area. In this case, it is preferable to create a test pattern using medium dots.

In step T22, the CCD camera 320
A test pattern is imaged using (FIG. 12). In step T23, the image processing unit 332 determines the positions of the center lines C1 to C6 of the dot rows in the main scanning direction from the image of the test pattern. Center line C1-C6 of each dot row
Is determined by the average value of the barycentric positions of the 48 dots in each dot row. The center line C of each dot row
The main scanning direction positions 1 to C6 can be measured with the first center line C1 as the origin position. Note that the following processing results are the same even if an arbitrary position other than the first center line C1 is used as the origin position.

In step T24, the six center lines C1 to C1
The inter-column landing error is determined from the position of the main scanning direction C6. At this time, first, the average of the positions of the six center lines C1 to C6 in the main scanning direction is determined to determine the center lines CL of all the dot rows. Then, distances d1 to d6 from the center line CL of all dot rows to the center lines C1 to C6 of each dot row.
Are calculated respectively.

In the lower part of FIG. 14, designed center lines C1 'to C6' of six dot rows are drawn. Usually, the center lines C1 to C6 of the actual dot rows are slightly shifted from the designed center lines C1 'to C6'. That is, the actual center lines C1 to C6 of each dot row have errors δ1 to δ6 from the designed center lines C1 ′ to C6 ′, respectively. Note that the errors δ1 to δ6 are positive values when each center line is shifted to the right from the design position, and are negative values when each center line is shifted to the left from the design position. As the inter-column landing error Ea, the center lines C1 to
The maximum value max (| δi |) of the absolute values of the errors δ1 to δ6 of the positions in the main scanning direction of C6 is adopted.

The errors δ1 to δ6 of the respective dot rows for ejecting different inks may be used as they are as the row-to-row landing errors Ea for the respective inks.

As can be understood from the above description, the inter-column landing error Ea is based on the landing positions of the six nozzle rows of the print head unit 60 (that is, the center lines C1 to C of the dot rows).
6A shows the amount of deviation when the actual relative relationship deviates from the design relative relationship. That is, when the inter-row landing error Ea is large, the dot rows formed by different nozzle rows are largely displaced from each other in the main scanning direction.
Image quality deteriorates. Therefore, the smaller the inter-column landing error Ea is, the better in terms of image quality.

In step T3 of FIG. 11, the in-row impact position is measured. FIG. 15 is a flowchart showing a procedure for measuring an in-row landing error. In Step T31, first, a test pattern for measuring an in-row landing error is printed.

FIG. 16 shows a method of measuring an in-row landing error. In the measurement of the in-row landing error, a vertical ruled line as shown in FIG. 16A is printed using each nozzle row. Therefore, although not shown, the test pattern for in-row landing error measurement includes six vertical ruled lines.

One vertical ruled line is composed of a continuous dot row. When the nozzle pitch of each nozzle row is, for example, three dots, as shown in FIG. 16A, one dot feed is performed so that three consecutive dots can be printed using each nozzle. The vertical scanning is printed in three main scans by performing the sub-scan feed by the amount twice. In general, when the nozzle pitch is k dots (k is an integer), the sub-scan feed by one dot feed amount is (k−1) so that continuous k dots can be printed using each nozzle. ) Times to print vertical ruled lines in k main scans.

A test pattern for measuring an in-row landing error is also supplied with one type of ink (eg, cyan ink) commonly to the six nozzle rows. The same ink that is supplied may be used. In addition, the test pattern for measuring the landing error between rows shown in FIG. 14 can be used as the test pattern for measuring the landing error in row. Conversely, FIG.
It is also possible to use the test pattern for measuring an in-row impact error shown in FIG. 7A as a test pattern for measuring an in-row impact error. In other words, as a test pattern for measuring the landing error between rows and the landing error within a row, a pattern including ruled lines formed in a sub-scanning direction and formed by continuous dots can be used. It is also possible to use a pattern including a formed dot row extending in the sub-scanning direction.

FIG. 16A shows an ideal state where there is no shift in the in-row landing position.
As shown in (b) and (c), the vertical ruled line is often slightly bent. However, FIGS. 16B and 16C exaggerate the way of bending the vertical ruled lines. In the following, FIG.
A description will be given of a case where the in-row impact error is measured for vertical ruled lines as shown in FIGS.

In step T32, the CCD camera 320
A vertical ruled line is imaged using (FIG. 12). Step T3
In 3, the image processing unit 332 converts the image of the vertical ruled line into
The position of the center line Cave of the vertical ruled line in the main scanning direction is determined. The position of the center line Cave of the vertical ruled line is determined by the average value of the barycentric positions of a large number of dots constituting the vertical ruled line.

In step T34, a regression line RL of the position of the center of gravity of the dots forming the vertical ruled line is determined. In step T35, the center line Cave of the vertical ruled line and the regression line R
The in-row impact error Eb is determined from the deviation εi from L. Here, the deviation εi between the center line Cave of the vertical ruled line and the regression line RL is determined by the regression line R at the upper end and the lower end of the vertical ruled line.
This is the larger of the deviation amounts of L and the center line Cave in the main scanning direction. The shift amount εi may be large at the lower end of the vertical ruled line as shown in FIG. 16B, or may be larger at the upper end of the vertical ruled line as shown in FIG. Note that “i” added to the symbol “εi” indicating the amount of displacement
Represents i of the six vertical ruled lines included in the test pattern.
This means that the value is related to the vertical ruled line. As the in-row landing error Eb, the maximum value max (εi) of the shift amount εi of the regression line RL for the six vertical ruled lines is adopted.

Note that the deviation amounts ε1 to ε6 of the respective dot rows for ejecting different inks may be used as they are as the in-row landing errors Eb for the respective inks.

As can be understood from the above description, the in-row landing error E is the actual landing position of a dot formed by a plurality of nozzles in a certain nozzle row of the print head unit 60. Shows the amount of deviation when it is shifted in the main scanning direction. That is, the in-row impact error E
When b is large, dots formed by different nozzles in the same nozzle row are largely displaced from each other in the main scanning direction, and the image quality is deteriorated. Therefore, the smaller the in-row impact error Eb is, the better.

When the inter-column impact error Ea and the in-row impact error Eb are measured for one print head unit 60 in this manner, in step T4 in FIG. 11, the print head unit 60 is controlled based on these errors Ea and Eb. Pass / fail is determined.

FIG. 17 is an explanatory diagram showing an example of a criterion for judging the quality of the print head unit. The horizontal axis in FIG. 17 is the inter-row impact error Ea, and the vertical axis is the in-row impact error Eb.
The non-defective range Rcr is a range that simultaneously satisfies the following three conditions. (1) The landing error Ea between rows is equal to or less than the maximum allowable value Ea1. (2) The in-row impact error Eb is equal to or less than the maximum allowable value Eb1. (3) The point defined by the inter-row impact error Ea and the in-row impact error Eb is below the straight line connecting the two points P1 and P2.

Note that the first point P1 is the inter-column landing error Ea
Is equal to a predetermined reference value Ea2 smaller than the maximum allowable value Ea1, and the in-row impact error Eb is equal to the maximum allowable value Eb1. The second point P2 is a point where the inter-row landing error Ea is equal to the maximum allowable value Ea1 and the in-row landing error Eb is equal to a predetermined reference value Eb2 smaller than the maximum allowable value Eb1.

A landing error E between rows of a certain print head unit
If a and the in-row landing error Eb are within the range Rcr of non-defective products, it is determined to be non-defective, and if out of this range, it is determined to be defective. As described above, if the quality of the print head is determined using both the inter-column impact error Ea and the in-row impact error Eb, a print head having a large error in the ink landing position is excluded as a defective product, and only the non-defective product is determined. It can be used to produce a printer with good image quality.

The inter-column impact error Ea and the in-row impact error Eb are set for each nozzle row, and the quality of the print head is determined using the criterion set for each nozzle row. You may. The reason is that the degree of the effect of the landing error on the image quality depends on the type of ink. For example, regarding the image quality in the halftone area, when performing four-color printing of KCMY, the effect of the landing error of magenta and cyan is relatively large, and the effect of the landing error of yellow is relatively small. In this case,
It is possible to set relatively strict criteria for magenta and cyan, and relatively loose criteria for yellow. In addition, when performing six-color printing including light magenta and light cyan, the effect of landing error of light magenta and light cyan is relatively large, and the effect of landing error of yellow is relatively small. In this case, set relatively strict criteria for light magenta and light cyan,
It is possible to set comparatively mild criteria for yellow.

FIG. 18 is an explanatory diagram showing another example of the criterion for judging the quality of the print head unit. In this determination criterion, the second non-defective range Rcrr exists inside the non-defective range Rcr shown in FIG. The second non-defective range Rcrr is
Is a range defined by a stricter criterion than the non-defective range Rcr. Such two good product ranges (that is, two criteria) can be applied to print heads used in different modes. For example, a relatively gradual criterion (first non-defective range Rcr) is applied to a print head using only CMYK four-color inks, and a relatively strict criterion (second non-defective range Rcrr) is set to light cyan (LC). ) And light magenta (LM).

FIG. 20 shows an example of a print head using only four color inks of CMYK. The actuator circuit 90 of the print head 28a includes three black nozzle rows K1, K2, and K3, a cyan nozzle row C, a magenta nozzle row M, and a yellow nozzle row Y. When performing six-color printing using the print head shown in FIG. 6 described above, there is a higher demand for image quality than when performing four-color printing using the print head shown in FIG. Therefore, a stricter criterion (second non-defective range Rcrr in FIG. 34) is applied to the inspection of the print head for six-color printing.
For the inspection of the print head for four-color printing, it is preferable to apply a looser criterion (first non-defective range Rcr in FIG. 34).

As described above, if the criterion of pass / fail is changed in accordance with the use mode of the print head, the printer can be manufactured by using a print head having sufficient performance in accordance with the request in accordance with the use mode of the print head. It is possible to manufacture.

It is also possible to manufacture a printer equipped with two print heads as shown in FIG. 19, and discharge the same ink from two nozzle rows in each actuator. At this time, K,
It is possible to discharge inks of three colors C and M and discharge inks of three colors of LC, LM and Y from the second print head. In this case, a looser criterion may be applied to the first print head, and a stricter criterion may be applied to the second print head.

When a print head having the same structure can be used for both a print head for six-color printing and a print head for four-color printing, first, a stricter criterion for six-color printing is set. The inspection may be performed by applying the inspection, and a looser criterion for four-color printing may be applied to the inspection failure. In general, printhead inspection may be performed using at least one of a more stringent criterion and a looser criterion.

In step T5 in FIG. 11, a head ID is set for a print head unit determined to be non-defective. As the head ID, information indicating various characteristics related to the print head unit is set.
A method of setting the head ID related to the displacement between columns will be described.

FIG. 20 is an explanatory diagram showing the setting contents of the head ID relating to the displacement between columns. Here, six head ID values are set in accordance with the range of values of the inter-row deviations δ1 to δ6 of the six nozzle rows shown in FIG. For example,
The misalignment δi between the rows of the i-th nozzle row is −30 to −25 μm
, The head ID value of the inter-row deviation for the nozzle row is set to “A”, and the head ID value of the inter-row deviation is set to “L” in the range of 25 to 30 μm. In FIG. 20, the head ID values with circles indicate examples of six head ID values set for a certain print head unit. In this example, the inter-row deviation δ1 of the first nozzle row is in the range of −5 to 0 μm, and the inter-row deviation δ2 of the second nozzle row is in the range of 15 to 20 μm. As shown in the lower part of FIG. 20, the head ID relating to the misalignment of the print head unit between rows is as follows.
Six head ID values of “FJHGEC” are set.

The head ID of such a shift between rows can be used for correcting the shift of the landing position at the time of printing. For example, as shown in FIGS. 9 and 10, when the landing positions of black dots and cyan dots are shifted from each other during bidirectional printing, a black nozzle row and a cyan nozzle row (in the examples of FIGS. 6 and 14, 1st row and 2nd
Using the head ID values (“F” and “J” in FIG. 20) relating to the inter-column deviation of the (column), it is possible to correct the deviation during bidirectional printing.

Incidentally, the head ID value relating to the inter-column deviation does not correspond to one value of the inter-column deviation δ, but
This corresponds to the range of the inter-column deviation δ. Therefore, when correcting deviation during bidirectional printing, a difference between representative values (median values) of a range of deviation between columns corresponding to head ID values is used. For example, the relative amount of misalignment of the second nozzle array with respect to the first nozzle array can be calculated from the representative value (17.5 μm) of the range of the misalignment of the second nozzle array to the first value. The value (2) obtained by subtracting the representative value (−2.5 μm) in the range of the nozzle row misalignment
0 μm). By such a calculation, the inter-row deviation amount from the first nozzle row (black nozzle row in FIG. 6) as a reference to the second nozzle row (cyan nozzle row) is relatively easily determined. can do. Further, it is possible to correct the positional deviation during bidirectional printing using the relative positional deviation.

By using the head ID value shown in FIG. 20,
With reference to the black nozzle row, it is also possible to calculate the average inter-row deviation amount between the cyan nozzle row and the magenta nozzle row. In other words, the relative inter-row displacement of the magenta nozzle row (fourth row) based on the black nozzle row (first row) is 5 μm (= 2.5 − (− 2.5)) from FIG. Become. On the other hand, the relative inter-row deviation amount of the cyan nozzle row with respect to the black nozzle row is 20 μm as described above.
It is. Accordingly, the average amount of misalignment between the cyan nozzle row and the magenta nozzle row based on the black nozzle row is 12.5 μm. If the misalignment during bidirectional printing is corrected based on the amount of misalignment between columns, if the misalignment of cyan and magenta dots greatly affects image quality,
Image quality can be improved. Similarly, it is also possible to calculate the average amount of misalignment between the light cyan nozzle row and the light magenta nozzle row based on the black nozzle row. Since light cyan and light magenta have a particularly large effect on the image quality of the halftone area, if the shift during bidirectional printing is corrected by using these inter-row shift amounts, the effect of improving the image quality of the halftone area is great.

In general, from the head ID values for the six nozzle rows, the inter-row deviation amount for one or more arbitrary nozzle rows of the six nozzle rows is calculated, and the position deviation amount during bidirectional printing is calculated using this. It is possible to correct the displacement.

When the head ID is determined in this manner, a head ID sticker 100 indicating the head ID is attached to the upper surface of the print head unit 60 (FIG. 3). Alternatively, a nonvolatile memory (for example, a programmable ROM) may be provided in the driver IC 126 (FIG. 7) provided in the print head unit 60, and the head ID may be stored in the nonvolatile memory. In general, it is sufficient that the print head unit 60 is set so that the head ID (head identification information) can be read. If the head ID is set to be readable in the print head unit 60, a head ID suitable for the print head unit 60 can be set in the printer 20 when the print head unit 60 is assembled to the printer 20.

Print head unit 60 determined to be non-defective
Is transported to the printer assembly line. And FIG.
In one step T6, the print head unit 60 is assembled to the printer 20.

As described above, in the present embodiment, the printer 20 is manufactured using only print heads that satisfy both the inter-row landing error and the in-row landing error. It is possible to obtain a printer capable of performing high-quality printing.

F. Modifications: The present invention is not limited to the above-described examples and embodiments, and can be carried out in various modes without departing from the gist thereof. For example, the following modifications are also possible. is there.

F1. Modification Example 1 In the above embodiment, the print head unit 60 as shown in FIG. 3 is targeted for inspection. However, the print head 28 itself in a state that does not include the mounting portion of the ink cartridge may be targeted for inspection.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a printing system including a printer 20 according to a first embodiment.

FIG. 2 is a block diagram showing a configuration of a control circuit 40 in the printer 20.

FIG. 3 is a perspective view showing a configuration of a print head unit 60.

FIG. 4 is an explanatory diagram showing a configuration for ejecting ink in each print head.

FIG. 5 is an explanatory diagram showing a state in which ink particles Ip are ejected by expansion of a piezo element PE.

FIG. 6 is an explanatory diagram showing a correspondence between a plurality of rows of nozzles in a print head and a plurality of actuator chips.

FIG. 7 is an exploded perspective view of the actuator circuit 90.

FIG. 8 is a partial cross-sectional view of the actuator circuit 90.

FIG. 9 is an explanatory diagram showing a positional shift during bidirectional printing of dots recorded by different nozzle arrays.

FIG. 10 is an explanatory diagram showing the position shift shown in FIG. 9 in a plan view.

FIG. 11 is a flowchart illustrating a procedure for inspecting a print head unit and assembling the print head unit in a printing apparatus according to the embodiment of the present invention.

FIG. 12 is a conceptual diagram showing a head inspection device 300.

FIG. 13 is a flowchart showing a procedure for measuring a landing error between rows.

FIG. 14 is an explanatory diagram showing a method of measuring an inter-column landing error.

FIG. 15 is a flowchart showing a procedure for measuring an in-row landing error.

FIG. 16 is an explanatory diagram showing a method of measuring an in-row landing error.

FIG. 17 is an explanatory diagram illustrating an example of a determination criterion for accepting or rejecting a print head unit.

FIG. 18 is an explanatory diagram illustrating an example of a determination criterion for accepting or rejecting a print head unit.

FIG. 19 is an explanatory diagram showing another example of the arrangement of a plurality of rows of nozzles of the print head.

FIG. 20 is an explanatory diagram showing a setting of a head ID relating to a displacement between rows.

[Explanation of symbols]

 Reference Signs List 20 inkjet printer 22 paper feed motor 24 carriage motor 26 platen 28 print head 30 carriage 31 partition plate 32 operation panel 34 sliding shaft 36 drive belt 38 pulley 39 position sensor 40 control Circuit 41 CPU 43 PROM 44 RAM 50 I / F dedicated circuit 52 Head drive circuit 54 Motor drive circuit 56 Connector 60 Print head unit 71 to 76 Inlet tube 80 Ink passage 88 Computer 90 Actuator circuits 91 to 93 Actuator chip 100 Head ID seal 110 Nozzle plate 112 Reservoir plate 120 Connection terminal plate 122 Internal connection terminal 124 External connection terminal 130 Ceramic sintered body 132 Terminal electrode 300 Head Inspection device 302 ... Stage 304 ... Paper feed roller 306 ... Paper feed roller 310 ... CCD camera 320 ... Support unit 330 ... Control unit 332 ... Image processing unit

Claims (6)

[Claims] 1. A method for manufacturing a printing apparatus including a print head having a plurality of nozzle rows for discharging ink, comprising: (a) forming a print head using a plurality of nozzle rows of a target print head to be inspected; Inspecting the first plurality of dot rows thus determined, and measuring a positional deviation between the first plurality of dot rows in the main scanning direction, thereby determining an inter-column landing error for the target print head; (B) inspecting a second plurality of dot rows respectively formed by using a plurality of nozzle rows of the target print head, and determining a main relationship between dots in each of the second plurality of dot rows; Determining an in-row landing error for the target print head by measuring a displacement in the scanning direction;
(C) On the basis of the inter-row impact error and the in-row impact error,
A method of manufacturing a printing apparatus, comprising: a step of determining whether the target print head is acceptable or not; and (d) assembling a printing apparatus using a print head that has passed in the step (c). 2. The method of manufacturing a printing apparatus according to claim 1, wherein said step (c) comprises the steps of: (i) ejecting a single density ink for each of a plurality of hues. A first criterion for determining pass / fail of at least one
Setting a second judgment criterion for judging the acceptability of a second type of print head that ejects a plurality of types of inks having substantially the same hue and different densities for one hue, and (ii) the target printing Regarding the head, a pass / fail determination as the first type print head according to the first determination criterion, and a pass / fail determination as the second type print head according to the second determination criterion, And a step of performing at least one of the steps. 3. The method of manufacturing a printing apparatus according to claim 1, wherein the second determination criterion has a smaller allowable range than the first determination criterion. 4. A method of inspecting a print head having a plurality of nozzle rows for discharging ink, comprising: (a) a first print head formed using a plurality of nozzle rows of a target print head to be tested; Determining a row-to-column landing error for the target print head by inspecting the plurality of dot rows and measuring a positional shift in the main scanning direction between the first plurality of dot rows; and (b) The second plurality of dot rows formed using the plurality of nozzle rows of the target print head are inspected, and the positions of the dots in the main scanning direction within each dot row of the second plurality of dot rows are inspected. Determining the in-row impact error for the target print head by measuring the deviation; and (c) determining pass / fail of the target print head based on the inter-row impact error and the in-row impact error. And a printhead inspection method. 5. The printhead inspection method according to claim 4, wherein said step (c) comprises: (i) discharging a single density ink for each of a plurality of hues. A first criterion for determining pass / fail of at least one
Setting a second determination criterion for determining whether or not a second type of print head ejecting a plurality of types of inks having substantially the same hue and different densities for one hue, and (ii) the target printing Regarding the head, a pass / fail judgment as the first type print head according to the first judgment criterion, and a pass / fail judgment as the second type print head according to the second judgment criterion, Performing at least one of the following. 6. The printhead inspection method according to claim 4, wherein the second determination criterion is set to have a smaller allowable range than the first determination criterion.