JP2012051272A - Printer, method for controlling printer, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform density adjusting operation for a printer in accurate timing by determining timing to perform the density adjusting operation without influencing printing operation of the printer without adding a special pattern to a printed matter.SOLUTION: An inspection part CPU 5001 extracts an area in which density measurement is performed from printing data to be printed in a printer part 300, and decides expected density in the extracted area. When a printing medium processed to be printed in the printer part 300 is conveyed, the inspection part CPU 5001 reads image data from the printing medium, calculates actually measured density in an area corresponding to the density measured area in the read image data, calculates a density difference between the expected density in the area corresponding to the density measured area and the actually measured density in the area corresponding to the density measured area, and determines on the basis of the calculated density difference whether or not to perform adjusting operation for adjusting the printing density of the printer part 300.

Description

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

2. Description of the Related Art Conventionally, an apparatus for inspecting whether printing has been properly performed on a printed material has been known.
In Patent Document 1, an image printed on a paper surface or the like is read by a color sensor, an original image input to a printer device at the time of printing is compared with the read image, and whether the printed image is appropriate or not is determined. It is described that it can be inspected.

  By the way, in an image forming apparatus such as an electrophotographic system, it is generally known that the obtained image density fluctuates when there are fluctuations in each part of the apparatus due to environmental changes and long-term use. In particular, in the case of a color image forming apparatus, even if a slight environmental change occurs, the image density may change, and the color balance may be lost. Therefore, the color image forming apparatus generally has an adjustment function for maintaining a constant image density.

  In Patent Document 2, a reference toner image pattern for density detection is formed on a photoconductor or an intermediate transfer body so that a constant image density and gradation characteristics can be obtained even if fluctuations of each part of the image forming apparatus occur. A method of forming and detecting the density of the pattern with an optical sensor is disclosed.

  In addition, when performing an image inspection of a printed matter as in Patent Document 1, it is considered that the inspection does not pass due to variations in each part of the apparatus (the inspection result is always NG (printing failure)). The timing for adjusting the image density is important.

  In Patent Document 3, an inspection pattern is formed on a recording material, and the density is detected optically to detect a density difference and determine whether to adjust image forming conditions based on the density difference. An image forming apparatus is disclosed.

JP-A-11-39492 JP-A-11-231384 JP 2006-201613 A

  However, in the image forming apparatus described in Patent Document 3, since it is necessary to provide an inspection pattern on the recording material, the inspection pattern is printed on the final printed matter, or a blank area is set and cut. It becomes necessary to be restricted.

  Note that, as in the image forming apparatus described in Patent Document 2, it is conceivable to form an inspection pattern on a transfer material carrier or an intermediate transfer body and determine whether to adjust the apparatus. In this case, it is necessary to temporarily interrupt the printing operation performed by the apparatus.

  Therefore, it has been desired to develop an apparatus that can determine the timing for adjusting the apparatus without affecting the printing operation performed by the apparatus and without adding a special inspection pattern to the final printed matter.

  The present invention has been made to solve the above problems. An object of the present invention is to provide a mechanism that makes it possible to determine the timing for performing a density adjustment operation without giving a special pattern to a printed matter and without affecting the printing operation of the apparatus.

  The present invention relates to a printing unit that performs a printing process on a print medium based on print data, an extraction unit that extracts an area for density measurement from print data printed by the printing unit, and an area extracted by the extraction unit. A determining unit that determines an expected density indicating a density expected to be printed; a reading unit that reads image data from a printing surface of a print medium that has been printed by the printing unit; and an image that is read by the reading unit An actual density calculating means for calculating an actual density in an area corresponding to the density measurement area in the data; a density between the expected density in the area corresponding to the density measurement area and the actual density in the area corresponding to the density measurement area; A density difference calculating means for calculating a difference, and an adjustment operation for adjusting a print density of the printing means based on the density difference calculated by the density difference calculating means. And having a determining means for determining whether or not to execute the.

  According to the present invention, it is possible to determine the timing for performing the density adjustment operation without giving a special pattern to the printed matter and without affecting the printing operation of the apparatus.

1 is a cross-sectional view illustrating a configuration of a printing system to which a printing apparatus according to an embodiment of the present invention is applied. 3 is a block diagram showing an internal configuration of a controller unit 400. FIG. 3 is a block diagram showing an internal configuration of an inspection unit 500. FIG. FIG. 5 is an image diagram showing an arrangement of reading units in an inspection unit 500. 5 is a flowchart illustrating an example of density measurement region extraction control in an inspection unit 500. It is an image figure which shows the relationship between a filling area | region and a measurement area | region. It is an image figure which shows an example of a density | concentration measurement area | region management table. 4 is a flowchart illustrating an example of print control in a controller unit 400. It is an image figure which shows a gamma correction. 5 is a flowchart illustrating an example of density measurement control in an inspection unit 500. It is an image figure for demonstrating the average value calculation process in a density | concentration measurement area | region. It is an image figure which shows a density | concentration measurement result table. It is an image figure which shows transition of a density difference. 10 is a flowchart illustrating an example of adjustment control (S305 in FIG. 8) in the controller unit 400. It is an image figure which shows an example of an adjustment pattern. It is an image figure which shows an example of a specific color adjustment pattern. It is an image figure which shows an example of a difference adjustment pattern. 10 is a flowchart illustrating an example of inspection unit initialization control in the inspection unit 500 according to the second embodiment. It is an image figure which shows the test | inspection setting menu which concerns on Example 2. FIG.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

First, a system configuration, a controller unit configuration, and an inspection unit configuration in the present embodiment will be described with reference to the drawings.
〔System configuration〕
FIG. 1 is a cross-sectional view showing a configuration of a printing system to which a printing apparatus according to an embodiment of the present invention is applied.

  In FIG. 1, reference numeral 100 denotes a printing system to which the printing apparatus of the present invention is applied. The printing system 100 includes an operation unit 200, a printer unit 300, a controller unit 400, an inspection unit 500, and a paper discharge tray unit 600.

  When image formation is performed, the controller unit 400 sends YMCK color signals, which are toner colorants of the color image forming apparatus, to the exposure control units (303Y, 303M, 303C, and 303K), respectively.

  The exposure control units (303Y, 303M, 303C, 303K) turn on and output laser light in accordance with the YMCK color signal. By irradiating the photosensitive drums (301Y, 301M, 301C, 301K) charged by four chargers (302Y, 302M, 302C, 302K) with the laser light, the photosensitive drums (301Y, 301M, 301C, 301K) An electrostatic latent image corresponding to the image signal is formed on the top.

  The photosensitive drums (301Y, 301M, 301C, 301K) are rotated counterclockwise by a motor (not shown). The electrostatic latent images formed on the photosensitive drums (301Y, 301M, 301C, 301K) are developed by developing units (305Y, 305M, 305C, 305K). Further, the developing units (305Y, 305M, 305C, 305K) are connected to toner cartridges (304Y, 304M, 304C, 304K), and are configured so that toner is constantly supplied.

  The intermediate transfer member 306 is in contact with the photosensitive drums (301Y, 301M, 301C, 301K), and rotates clockwise with the rotation of the photosensitive drums (301Y, 301M, 301C, 301K) to develop the developed toner image. Is transferred from the photosensitive drum. The toner image transferred onto the intermediate transfer member 306 is transferred by a transfer roller 307 to a print medium (hereinafter referred to as a recording material) conveyed from one of the cassettes 311 and 312. A cleaning unit 309 is provided after the transfer roller 307 in order to clean the toner remaining on the intermediate transfer member 306. In addition, a density sensor 310 is disposed for observing the density of the toner image on the intermediate transfer member 306.

  The recording material onto which the toner image has been transferred is then conveyed to the fixing unit 308. In the fixing unit 308, the toner image transferred by heat and pressure is melted and fixed by an internal heater and a pressure roller.

  The recording material that has passed through the fixing unit 308 is once guided from a path 313 to a path 314 by a flapper (not shown), and after the trailing end of the recording material has passed through the path 313, the recording material is switched back and discharged from the path 315. Lead to 317. As a result, the surface onto which the developer has been transferred can be turned downward (face down) and discharged from the printer unit 300 by the discharge roller 317.

  Also, when image formation is performed on both sides of the recording material, the recording material is guided from the fixing unit 308 to pass 313 and pass 314, and the recording material is switched back immediately after the rear end of the recording material passes through the path 313, not shown The paper is guided to a duplex conveyance path 316 by a flapper. The electrostatic latent image is transferred again to the recording material guided to the duplex conveyance path 316 by the transfer unit 307 and subjected to fixing processing by the fixing unit 308. The printed output (recording material) discharged from the discharge roller 317 is sent to the inspection unit 500.

  When the inspection unit 500 detects the recording material sent from the printer unit 300 by the sensor 530, the image data is read by the reading unit 505 (the reading unit A5051a and the reading unit B5051b) from the printing surface of the recording material. The read image data is sent to the inspection apparatus control unit 510. After the image data is read, the recording material is sent as it is to the paper discharge tray unit 600 or to the NG tray 520 according to the inspection result by the inspection device control unit 510. More specifically, the inspection apparatus control unit 510 controls the recording material to be sent to the paper discharge tray unit 600 when the inspection result is OK, while the recording material is sent to the NG tray 520 when the inspection result is NG. .

[Controller configuration]
FIG. 2 is a block diagram showing an internal configuration of the controller unit 400.
The controller unit 400 is connected to the printer unit 300, which is an image forming device, the operation unit 200, and an external I / F such as a LAN, and processes and controls image information and device information.
The CPU 4301 executes various programs such as a control processing routine described later. The ROM 4302 stores (stores) a computer-readable boot program for operating the CPU 4301. The RAM 4303 is used as a work area or an image memory that is a temporary storage location for image data when the CPU 4301 executes various programs. The NVRAM 4304 is a nonvolatile RAM that stores various control parameters.

  A network unit 4305 is connected to the LAN 700 and performs various network controls such as transmission / reception of electronic mail and input / output of PDL (Page Description Language) data from the host. In addition, an NVRAM (not shown) is connected to the network unit 4305 and holds various parameters related to the network unit 4305 such as a MAC address.

  The operation unit I / F 4306 is an I / F that performs communication with the operation unit 200. A printer communication I / F 4307 is an I / F unit for communicating with a CPU (not shown) of the printer unit 300. The power control I / F 4308 instructs the power control unit 4500 to stop various power sources according to a command from the CPU 4301.

  The timer 4309 internally holds the current time and monitors whether a set time has elapsed. The ACC I / F 4317 is an I / F for communicating with the inspection unit 500. The HDD I / F 4318 is an I / F for communicating with the magnetic storage device (HDD 4100). The above devices are arranged on the system bus 4319.

  The Image Bus I / F 4310 is a bridge that connects the system bus 4319 and an image bus 4311 that transfers image signals. An image compression unit 4312, an image rotation unit 4313, a raster image processor (RIP) unit 4314, and a printer I / F unit 4316 are arranged on the image bus 4311.

  The image compression unit 4312 performs JPEG, JBIG, MMR, and MH compression / decompression processing. The image rotation unit 4313 performs image data rotation processing. A raster image processor (RIP) unit 4314 expands the PDL code into a bitmap raster image. The printer I / F unit 4316 performs printer image processing such as printer correction and resolution conversion on the print output image data, and transfers the print data to the printer unit 300.

[Inspection Department Configuration]
FIG. 3 is a block diagram illustrating an internal configuration of the inspection unit 500.
As illustrated in FIG. 3, the inspection unit 500 includes an inspection device control unit 510, a reading unit A 5051 a and a reading unit B 5051 b that are reading devices for recording materials discharged from the printer unit 300, and an HDD 5011. The inspection apparatus control unit 510 is a part that processes image information and controls each device in the inspection unit.

  In the inspection apparatus control unit 510, the CPU 5001 executes various programs such as a control processing routine described later regarding control of the inspection unit. The ROM 5002 stores (stores) a computer-readable start program for operating the CPU 5001. The RAM 5003 is used as a work area or an image memory that is a temporary storage location for image data when the CPU 5001 executes various programs.

  An HDD I / F 5004 is an I / F for communicating with a magnetic storage device (HDD 5011). The reading I / F_A 5052a and the reading I / F_B 5052b control the reading unit A5051a and the reading unit B5051b provided on the recording material conveyance path to read the recording material and receive the read image data. The reading unit A 5051a and the reading unit B 5051b are configured by a sensor array and are arranged on the recording material conveyance path as shown in FIG. 4 so that the entire area of the conveyed recording material can be read.

FIG. 4 is an image diagram showing the arrangement of the reading unit in the inspection unit 500.
A read image processing unit 5008 performs scaling processing, gamma correction processing, and the like on the image data sent from the reading I / F_A 5052a and the reading I / F_B 5052b, and transfers the processing result to the RAM 5003.

  A motor control unit 5009 controls various motors in the inspection unit 500. The sensor control unit 5010 detects the state of various sensors in the inspection unit 500 and notifies the CPU 5001 of it. For example, the sensor control unit 5010 notifies the CPU 5001 that the recording material sent from the printer unit 300 by the sensor 530 has been detected.

The HOST I / F 5007 is connected to the ACC I / F 4317 in the controller unit 400, and transmits and receives print setting information and image data.
The image processing unit 5006 includes image data (hereinafter, expected image data) stored in a magnetic storage device (HDD 5011) and image data (hereinafter, inspection image data) read by the reading unit A 5051a and the reading unit B 5051b and stored in the RAM 5003. Is read. The image processing unit 5006 performs a position correction process on these image data, and then performs a comparison process on these image data. The above devices are arranged on the system bus 5005.

  The reading unit A 5051a and the reading unit B 5051b are configured by a CCD sensor with a white LED and an RGB filter. The reading unit A 5051a and the reading unit B 5051b irradiate the recording material to be conveyed with light, separate the reflected light into RGB three color components using a filter, and send the data to the inspection apparatus control unit 510 as read data.

In the above configuration, the control flow of the present invention will be described below.
Note that the printing system 100 receives image data for printing from the network unit 4305 as a job. Based on the received print data, the printing system 100 performs control in the order of density measurement region extraction control (FIG. 5), print control (FIG. 8), density measurement control (FIG. 10), and adjustment control (FIG. 14). Execute. Hereinafter, each control is demonstrated using a flowchart.

[Density measurement area extraction control]
First, density measurement region extraction control in the inspection unit 500 will be described with reference to FIG.
FIG. 5 is a flowchart illustrating an example of density measurement region extraction control in the inspection unit 500. The control of this flowchart is realized by the CPU 5001 of the inspection unit 500 (hereinafter referred to as the inspection unit CPU 5001) reading out and executing a program recorded in the ROM 5002 so as to be readable by a computer.

  Upon receiving print data from the controller unit 400 via the HOST I / F 5007 (S101), the inspection unit CPU 5001 stores the received print job data in the HDD 5011, and advances the process to S102. This print job data is transferred from the controller unit 400 in S201 of FIG. 8 described later. In the description of the present embodiment, the print data received by the inspection unit 500 is described as PDL data, but the present invention is not limited to this. In practicing the present invention, the print data need not be PDL data.

In step S102, the inspection unit CPU 5001 acquires one drawing command from the print data received in step S101.
Then, the inspection unit CPU 5001 determines whether or not the drawing command acquired in S102 is a command accompanied by painting (S103). If it is determined that the drawing command acquired in S102 is not a paint command (No in S103), the inspection unit CPU 5001 shifts the process to S108.

On the other hand, when it is determined that the drawing command acquired in S102 is a paint command (Yes in S103), the inspection unit CPU 5001 advances the process to S104.
In S104, the inspection unit CPU 5001 calculates the area of a region to be filled with the drawing command acquired in S102 (hereinafter, “filled region”). Next, the inspection unit CPU 5001 compares the area of the paint area calculated in S104 with a threshold value that is held in advance, and the area of the paint area is determined according to whether or not the area of the paint area exceeds the threshold value. It is determined whether or not the area is sufficient (S105). Note that the threshold value (that is, an area sufficient for density measurement) is determined in advance by the accuracy of the reading unit 505, such as resolution, and is stored in the ROM 5002 or the HDD 5011.

Here, the comparison determination process in S105 will be described with reference to FIG.
FIG. 6 is an image diagram showing the relationship between the filled area and the measurement area.
Since the border portion of the filled area is not suitable for accurate density measurement because it is affected by surrounding pixels in the printing unit 300 and the reading unit 505, as shown in FIG. 6, it has a size larger than the actual size of the measurement region. A filled area is required. In this embodiment, the measurement area is 32 pixels × 32 pixels, the non-measurement part is 32 pixels, and the threshold is 96 (= 32 + 32 + 32) pixels × 96 pixels. Therefore, in S105, it is confirmed whether or not the area of the filled region is larger than 96 pixels × 96 pixels.

If it is determined in S105 that the area of the painted area does not exceed the threshold (No in S105), the inspection unit CPU 5001 shifts the process to S108.
On the other hand, if it is determined in S105 that the area of the filled region is larger than the threshold (Yes in S105), the process proceeds to S106.
In S106, the inspection unit CPU 5001 performs color space conversion from RGB to CMYK on the density information (hereinafter referred to as “fill density”) of each component in the RGB space of the fill attribute specified by the drawing command acquired in S102. (S106). That is, the fill density, which is density information in the RGB space, is converted into density information in the color space having the printing agent color (CMYK) used by the printer unit 300 as a color component. Here, the table used for color space conversion is a table used by the controller unit 400 during printing. When the printing system 100 is activated and initialized, the inspection unit CPU 5001 receives the table from the controller unit 400 in advance and stores it in the RAM 5003 or the HDD 5011.

  Subsequently, the inspection unit CPU 5001 registers, as a density measurement area, information related to the paint area in the drawing command acquired in S102 in the HDD 5011 (S107). Here, a table (density measurement area management table) as shown in FIG. 7 is created and stored in the HDD 5011 as expected density, appearance page, and start position.

  Specifically, the inspection unit CPU 5001 calculates the start position of the measurement area (FIG. 6) from the filled area in the drawing command acquired in S102. When the non-measurement part is for 32 pixels, a position (x + 32, y + 32) obtained by adding (32, 32) to the start position (x, y) of the filled area is calculated as the measurement area. Further, the inspection unit CPU 5001 manages the density measurement area using the fill density after the CMYK conversion in S106, the appearance page of the drawing command, and the calculated start position of the measurement area as the expected density, the appearance page, and the start position. Save in the table (FIG. 7).

FIG. 7 is an image diagram illustrating an example of the density measurement region management table of the present embodiment.
For example, the calculated measurement region start position (X, Y) is (764, 311), the appearance page of the rendering command is “1” page, and the fill density (C, M, Y, K) after CMYK conversion is ( In the case of 0, 255, 255, 0), it is registered as a density measurement region as 601 in FIG.

When the density measurement region registration process in S107 ends, the inspection unit CPU 5001 advances the process to S108.
In step S108, the inspection unit CPU 5001 determines whether or not the processing in steps S102 to S107 has been performed for all the drawing commands in the data received in step S101 (end of the drawing command). If it is determined that there is a drawing command that has not been processed yet (the drawing command is not finished) (No in S108), the inspection unit CPU 5001 returns the process to S102 and shifts the process to the next drawing command. Let
On the other hand, when it is determined that the above process has been completed for all the drawing commands (drawing command is completed) (Yes in S108), the inspection unit CPU 5001 ends the density measurement region extraction control.

(Print control)
Next, print control in the controller unit 400 will be described with reference to FIG.
FIG. 8 is a flowchart illustrating an example of print control in the controller unit 400. The control of this flowchart is realized by the CPU 4301 of the controller unit 400 (hereinafter referred to as the controller unit CPU 4301) reading out and executing a computer-readable program recorded in the ROM 4302.

When the controller unit CPU 4301 receives print job data via the network unit 4305 (S201), the process proceeds to S102.
In step S202, the controller unit CPU 4301 transfers the print job data received in step S201 to the inspection unit 500 via the ACC I / F 4317. This print job data is received in S101 of FIG.

  Next, the controller unit CPU 4301 takes out print job data for one page from the print job data received in S201. In order to print the print job data, the controller unit CPU 4301 develops the extracted print job data for one page into bitmap data in the RIP unit 4314 (print data creation) (S203).

  Next, the controller unit CPU 4301 determines whether or not an adjustment operation is necessary (adjustment timing) (S204). Specifically, the controller unit CPU 4301 determines whether or not the inspection unit 500 has issued an adjustment request in S314 of FIG. 10 to be described later, and whether or not the timing set in advance and stored in the HDD 4100 or the like has been reached. Note that the timing set in advance and stored in the HDD 4100 or the like indicates, for example, a timing once per 1000 sheets or a timing once a month (a specific cycle). When it is determined that the timing corresponds to any one of the above, it is determined that it is the adjustment timing.

If it is determined that the adjustment operation is necessary (adjustment timing) (Yes in S204), the controller unit CPU 4301 executes the adjustment operation (S205). Details of the adjustment control will be described later with reference to FIG. When the adjustment operation in S205 ends, the controller unit CPU 4301 advances the process to S206.
On the other hand, when it is determined that the adjustment operation is not necessary (adjustment timing) (No in S204), the controller unit CPU 4301 advances the process to S206 as it is.

In S206, the controller unit CPU 4301 confirms whether the printer unit 300 and the inspection unit 500 are ready, and waits until printing can be started (S206).
Then, when the printer unit 300 and the inspection unit 500 are in a ready state (Yes in S206), the controller unit CPU 4301 executes a printing process (S207). Specifically, the controller unit CPU 4301 sends the print data (bitmap data) expanded into the bitmap data in S203 to the printer unit 300 via the printer I / F unit 4316. The non-volatile memory in the printer I / F unit 4316 stores a density conversion table (hereinafter referred to as a gamma (γ) table) as shown in FIG. 9 for each color of CMYK. The printer I / F unit 4316 uses this gamma table to correct density data (print data) so that the printer unit 300 has ideal density characteristics ((C, M, Y, K) → (C ′, M ′, Y ′, K ′)) to the printer unit 300.

FIG. 9 is an image diagram illustrating gamma correction according to the present embodiment.
For example, when the printer I / F unit 4316 performs gamma correction using the gamma table of FIG. 9B on the density data before gamma correction of FIG. 9A, the gamma correction result is as shown in FIG. The density data after gamma correction of 9 (c) is obtained. This gamma table is stored in a nonvolatile memory in the printer I / F unit 4316 for each color of CMYK.
Returning to the flowchart of FIG.

When the printing process of S207 is completed, the controller unit CPU 4301 advances the process to S208.
In step S208, the controller unit CPU 4301 determines whether there is a page in the print job data received in step S201 that has not been subjected to the processing in steps S203 to S207 (there is a next page). If it is determined that there is a page that has not yet been processed (there is a next page) (“Yes” in S208), the controller unit CPU 4301 returns the process to S203 and shifts the process to the next page. .
On the other hand, when it is determined that the above process has been completed for all pages (no next page) (“None” in S208), the controller unit CPU 4301 ends the print control.

[Density measurement control]
First, density measurement control in the inspection unit 500 will be described with reference to FIG.
FIG. 10 is a flowchart illustrating an example of density measurement control in the inspection unit 500. Note that the control of this flowchart is realized by the inspection unit CPU 5001 reading and executing a program recorded in the ROM 5002 so as to be readable by a computer.

  When the inspection unit CPU 5001 detects that the recording material has been conveyed from the printer unit 300 via the sensor control unit 5010 (S301), the inspection unit CPU 5001 displays a density adjustment request flag held in the RAM 4303 in a step (not shown). It is initialized to OFF, and the process proceeds to S302. Note that the inspection unit CPU 5001 counts the number of recording materials conveyed from the printer unit 300 and stores the counted number in the RAM 5003. As a result, the inspection unit CPU 5001 can recognize the page number corresponding to the recording material to be conveyed.

  In step S302, the inspection unit CPU 5001 controls the reading unit A 5051a and the reading unit B 5051b from the reading I / F_A 5052a and the reading I / F_B 5052b to read the recording material and acquire the read image data of the recording material. Note that image data acquired from the reading I / F_A 5052a and the reading I / F_B 5052b is stored in the RAM 5003 after reading correction such as scaling processing and gamma correction processing in the reading image processing unit 5008.

  Next, the image processing unit 5006 detects a shift amount in the image processing unit 5006 in order to compare the read image data and the expected image data (S303). Since there is a shrinkage of the recording material due to the fixing heat of the printer unit 300 and a deviation between the reading unit 5051 in the inspection unit 500 and the recording material, it is necessary to align the positions of the read image data and the expected image data. As a method of detecting the deviation amount, a method of printing a predetermined pattern for detection or a method of calculating a point having the smallest difference by comparing with read data using expected image data is generally used. Are known. In the present invention, the method of detecting the deviation amount is not limited, and any method may be used.

  Further, the image processing unit 5006 performs position correction using affine transformation on the read image data based on the shift amount detected in S303, and obtains read image data in which the shift is corrected (S304). Note that the processing of S303 and S304 is executed by the image processing unit 5006 in accordance with an instruction from the inspection unit CPU 5001.

  Next, the inspection unit CPU 5001 refers to the density measurement area table (FIG. 7) stored in the HDD 5011 and determines whether there is a measurement area on the page corresponding to the recording material detected in S301 (S305). For example, when the pages corresponding to the recording material (double-sided printing) detected in S301 are one page and two pages, in the example of FIG. 7, the measurement area corresponding to 601 to 603 on the first page and 604 on the second page. It is determined that there is a measurement region corresponding to. Note that the inspection unit 500 determines whether the recording material is single-sided printing or double-sided printing from the print job data received in S101 of FIG.

  If it is determined that there is no measurement region on the page corresponding to the recording material detected in S301 (No in S305), the inspection unit CPU 5001 ends the density measurement control as it is.

On the other hand, if it is determined that the measurement area is on the page corresponding to the recording material detected in S301 (Yes in S305), the inspection unit CPU 5001 advances the process to S306.
In step S306, the inspection unit CPU 5001 selects one measurement area from the measurement areas in the page, and extracts an area corresponding to the measurement area from the read image data after the position correction. Here, 32 × 32 pixels are extracted from the start point registered in the density measurement region table (FIG. 7).

  Next, in S307, the inspection unit CPU 5001 calculates an average value of the density (actual density) for each pixel in the region extracted in S306 (actual density calculation process). In the extracted region, as shown in FIG. 11, since the density is measured for each pixel of each RGB color, the average value of each pixel in the region is calculated for each RGB color.

  FIG. 11 is an image diagram for explaining the average value calculation processing in the density measurement region according to the present embodiment. In FIG. 11, the measurement density of each pixel in the measurement region is shown in hexadecimal for each RGB color.

  In step S308, the inspection unit CPU 5001 performs color space conversion from RGB to CMYK on the average value calculated in step S307 as in step S106 of density measurement region control in FIG. Calculate (density difference calculation processing).

Next, the inspection unit CPU 5001 calculates the density difference of each color of CMYK between the actually measured density calculated in S308 and the expected density stored in the table of FIG. 7 (S309).
Next, the inspection unit CPU 5001 compares the density difference of each color of CMYK calculated in S309 with a threshold value set in advance and held in the HDD 5011 of the inspection unit 500, and the density of any color of CMYK. It is determined whether the difference exceeds a threshold value (S310). The expected density, the density difference calculated in S309, and the determination result in S310 are recorded in the density field, density difference field, and determination field for each color (CMYK) of the table as shown in FIG. It is stored in the RAM 5003.

FIG. 12 is an image diagram illustrating a density measurement result table according to the present embodiment.
FIG. 13 is an image diagram showing the transition of the density difference according to the present embodiment.
If it is determined that the density difference of any of the CMYK colors calculated in S309 exceeds the threshold (Yes in S310), the inspection unit CPU 5001 advances the process to S311.

  In S311, the inspection unit CPU 5001 determines that a density adjustment operation (adjustment operation for adjusting the print density of the printer unit 300) is necessary, sets the density adjustment request flag to ON (S311), and advances the process to S312.

  On the other hand, if it is determined that the density difference of any of the CMYK colors calculated in S309 does not exceed the threshold (No in S310), the inspection unit CPU 5001 advances the process to S312.

  In S312, the inspection unit CPU 5001 determines whether or not there is an area that has not yet been subjected to the processing in S306 to S311 in all the measurement areas determined to exist in S305 (there is a next area). If it is determined that there is a measurement area that has not been processed yet (there is a next area) (Yes in S312), the inspection unit CPU 5001 returns the process to S306 and transitions the process to the next measurement area. Let

On the other hand, if it is determined that the above process has been completed for all measurement areas (there is no next area) (No in S312), the inspection unit CPU 5001 advances the process to S313.
In step S313, the inspection unit CPU 5001 determines whether or not the density adjustment request flag is ON. If it is determined that the density adjustment request flag is ON (Yes in S313), the inspection unit CPU 5001 requests the controller unit 400 for an adjustment operation (S314). This request is determined in S204 of FIG. And this density | concentration measurement control is complete | finished.

On the other hand, when it is determined that the density adjustment request flag is OFF (No in S313), the inspection unit CPU 5001 ends the density measurement control as it is.
(Adjustment control)
Next, adjustment control (S305 in FIG. 8) in the controller unit 400 will be described with reference to FIG.

  FIG. 14 is a flowchart illustrating an example of adjustment control (S305 in FIG. 8) in the controller unit 400. The control of this flowchart is realized by the controller unit CPU 4301 reading and executing a program recorded in the ROM 4302 so as to be readable by a computer.

  The controller unit CPU 4301 checks whether or not the inspection unit 500 is connected when performing the adjustment operation (S401). And when it determines with the test | inspection part 500 not being connected (it is No at S401), a process is advanced to S402.

  In step S <b> 402, the controller unit CPU 4301 determines the timing of periodic adjustment of the device (for example, once every 1000 printed sheets). Then, the controller unit CPU 4301 acquires the pattern data of the adjustment pattern as shown in FIG. 15 from the HDD 4100 for each color of CMYK, and prepares to print the adjustment patterns of all the colors of CMYK as shown in FIG. Then, the process proceeds to S408.

FIG. 15 is an image diagram illustrating an example of an adjustment pattern according to the present embodiment.
In the example shown in FIG. 15, the density 0xD0 (208), 0xB0 (176), 0x90 (144), 0x70 (112), 0x50 (80), 0x40 (64), 0x30 (48), 0x20 (for each color of CMYK) 32) and 0x10 (16). Note that “0x” indicates hexadecimal notation, and parentheses indicate decimal notation.
Returning to the flowchart of FIG.

  In step S <b> 408, the controller unit CPU 4301 confirms whether the printer unit 300 is ready and waits until the printer unit 300 is ready. When the printer unit 300 is ready (Yes in S408), the controller unit CPU 4301 transmits the pattern data of the adjustment pattern (FIG. 15) to the printer unit 300 for printing processing (S409). At this time, in this embodiment, the recording material is not conveyed, and the toner image of the adjustment pattern formed on the intermediate transfer member 306 shown in FIG. It is assumed that density data for adjustment is measured by using and reading. When the printing process in S409 is completed, the controller unit CPU 4301 advances the process to S410.

  In step S410, the controller unit CPU 4301 compares the density data (measurement result) sampled in the printing process in step S409 with the pattern data of the adjustment pattern so that a predetermined density characteristic is obtained. The gamma table of 4316 is corrected. When the gamma table correction process in S410 is completed, the controller unit CPU 4301 ends the adjustment control.

In S401, if the controller unit CPU 4301 determines that the inspection unit 500 is connected (Yes in S401), the process proceeds to S403.
In step S403, the controller unit CPU 4301 requests and obtains (receives) the density measurement result table (FIG. 12) from the inspection unit 500 via the ACC I / F 4317. Note that the inspection unit CPU 5001 transmits a concentration measurement result table (FIG. 12) stored in the HDD 5011 to the controller unit 400 in response to a request from the controller unit 400.

  In step S <b> 404, the controller unit CPU 4301 confirms whether the adjustment control factor is due to regular adjustment or a request from the inspection unit 500. If it is determined that the factor of the adjustment control is not a periodic adjustment but a request from the inspection unit 500 (No in S404), the controller unit CPU 4301 advances the process to S405.

  In step S <b> 405, the controller unit CPU 4301 uses a color with a large density difference in the density measurement result table acquired from the inspection unit 500 based on the pattern data of the adjustment pattern stored in the HDD 4100 (hereinafter, a color with a determination result of NG “×”) The pattern data only for the specific color)) is generated, and the specific color adjustment pattern is prepared for printing. In the example shown in FIG. 12, since the determination result is NG “x” at the density “119” of cyan C, the pattern of the adjustment pattern (specific color adjustment pattern) only for cyan C as shown in FIG. Generate data.

FIG. 16 is an image diagram illustrating an example of the specific color adjustment pattern.
Then, the process proceeds to S408. In addition, since the process after S408 is the same, description is abbreviate | omitted.
By preparing the specific color adjustment pattern as in S405 above, the pattern corresponding to the color component that has been inspected by the inspection unit 500 is omitted, and unnecessary adjustment operation is omitted, and the adjustment operation is executed quickly. Thus, the influence on the printing operation of the printer unit 300 can be suppressed.

  If the controller unit CPU 4301 determines in S404 that the adjustment control factor is due to regular adjustment (Yes in S404), the controller unit CPU 4301 advances the process to S406.

  In step S <b> 406, the controller unit CPU 4301 acquires pattern data of all color adjustment patterns from the HDD 4100. Further, the controller unit CPU 4301 has a density difference of density corresponding to the density of the pattern data in which the density measured by the inspection unit 500 stored in the density measurement result table matches the density of the pattern data of all the adjustment patterns. Is small (the determination result is OK “◯”).

  Then, it is determined that the density measured by the inspection unit 500 matches the density of the pattern data of all the adjustment patterns, and the density difference of the density corresponding to the density of the pattern data is small (the determination result is OK “◯”). If it is (Yes in S406), the controller unit CPU 4301 ends the adjustment control. As a result, it is possible to prevent unnecessary adjustment operations from being performed and to prevent an influence on the printing operation of the printer unit 300.

  On the other hand, the density measured by the inspection unit 500 does not match the density of the pattern data of all the adjustment patterns, or the density difference corresponding to the density of the pattern data is large (determination result is NG “◯”). If it has been (No in S406), the controller unit CPU 4301 advances the process to S407. That is, when the measurement pattern in the inspection unit 500 is small and insufficient, or when the density difference is large, the process proceeds to S407.

  In step S407, the controller unit CPU 4301 prepares an adjustment pattern for a difference from the density measurement result table based on the density measurement result in the inspection unit 500 stored in the density measurement result table. Here, pattern data (difference pattern data) of an adjustment pattern in which a pattern having the same color and the same density as the expected density whose determination result is OK is generated in the density measurement result table from the pattern data of all the adjustment patterns. The difference adjustment pattern is prepared for printing. In the example shown in FIG. 12, the determination result is OK “◯” for cyan C density 32 (0x20), yellow Y density 32 (0x20), and black K density 32 (0x20). Are included in the adjustment pattern shown in FIG. Therefore, as shown in FIG. 17, pattern data of a difference adjustment pattern is generated by omitting the patterns of cyan C density “0x20”, yellow Y density “0x20”, and black K density “0x20”.

FIG. 17 is an image diagram illustrating an example of a difference adjustment pattern.
Then, when the difference pattern preparation process of S407 ends, the controller unit CPU 4301 advances the process to S408. In addition, since the process after S408 is the same, description is abbreviate | omitted.

  By preparing the difference adjustment pattern as in S407 above, the pattern corresponding to the density that is inspected by the inspection unit 500 is omitted, the unnecessary adjustment operation is omitted, and the adjustment operation is executed quickly. The influence on the printing operation of the printer unit 300 can be suppressed.

  In this embodiment, as described above, the density measurement is performed by forming the adjustment pattern image on the intermediate transfer member 306 and reading the toner image on the intermediate transfer member 306 by the density sensor 310. However, a configuration in which a recording material is fed, the adjustment pattern image is actually printed on the recording material, and density data for adjustment is measured using the reading unit 5051 in the inspection unit 500 may be used.

  As described above, according to the present exemplary embodiment, the timing for performing the density adjustment operation is determined without giving a special pattern to the printed matter and without affecting the printing operation of the printer unit 300, and is appropriately applied. The density adjustment operation of the apparatus can be performed at a precise timing.

Embodiment 2 of the present invention will be described below. The description of the same configuration as that of the first embodiment is omitted.
The printing system 100 according to the second exemplary embodiment receives image data for printing from the network unit 4305 as a job. Based on the received print data, the printing system 100 performs inspection unit initialization control (FIG. 18 described later), print control (FIG. 8), density measurement control (FIG. 10), and adjustment control (FIG. 14) in this order. Execute control. Since print control, density measurement control, and adjustment control are the same as those in the first embodiment, here, the inspection unit initialization control will be described with reference to the flowchart shown in FIG.

[Inspection part initialization control]
FIG. 18 is a flowchart illustrating an example of inspection unit initialization control in the inspection unit 500. Note that the control of this flowchart is realized by the inspection unit CPU 5001 reading and executing a program recorded in the ROM 5002 so as to be readable by a computer.

  Upon receiving print data from the controller unit 400 via the HOST I / F 5007 (S501), the inspection unit CPU 5001 stores the received print job data in the HDD 5011, and advances the process to S502. In this embodiment, it is assumed that inspection setting information is included (added) in the print data received by the inspection unit CPU 5001 in S501. The contents of the inspection setting information can be set by the user from a user interface as shown in FIG. 19 of a printing device driver (printer driver) installed in a device that generates a print job, for example, a personal computer (PC). When a print job is generated by the PC, the print device driver stores the print job data, and the print job data is transmitted from the PC to the printing system 100. Further, the print job data is transferred from the controller unit 400 to the inspection unit 500 in step S201 of FIG. 8 and is received in step S501.

FIG. 19 is an image diagram illustrating an inspection setting menu according to the present embodiment.
In FIG. 19, reference numeral 1701 denotes a character quality inspection level setting field. For example, “strict”, “normal”, “sweet”, and “no inspection” can be set as the character quality inspection level. In accordance with the character quality inspection level set in the character quality inspection level setting field 1701, the inspection device control unit 510 inspects (inspects) whether printing has been properly performed on the recording material, and the recording material according to the inspection result. Is conveyed to the paper discharge tray unit 600 or the NG tray 520.

  Reference numeral 1702 denotes a density unevenness inspection level setting column. For example, “severe”, “normal”, “sweet”, and “no inspection” can be set as the density unevenness inspection level. In accordance with the density unevenness inspection level set in the density unevenness inspection level setting field 1702, the inspection unit initialization control of FIG. 18 is executed.

Note that S502 to S508 are the same processes as S102 to S108 of the density measurement region extraction control in FIG.
If the inspection unit CPU 5001 determines that the processing of S502 to S507 has been completed for all the rendering commands in the data received in S501 (end of the rendering command) (Yes in S508), the processing proceeds to S509.

In step S509, the inspection unit CPU 5001 confirms the content of the inspection setting information included in the print data received in step S501.
Next, the inspection unit CPU 5001 changes the threshold held in the HDD 5011 of the inspection unit 500 according to the density unevenness inspection level in the inspection setting confirmed in S509 (S510), and performs this inspection unit initialization control. finish.

  For example, the threshold value is changed to “10” when the density unevenness inspection level of the inspection setting is “strict”, the threshold value is changed to “20” when it is “normal”, and the threshold value is set to “30” when it is “sweet”. , And in the case of “no inspection”, the threshold value is changed to “40”. As described above, in this embodiment, the threshold value used in the density measurement control (S310 in FIG. 10) is changed according to the inspection level set in the print job. Thereby, since the threshold value for density adjustment is changed according to the inspection setting, the adjustment timing can be changed according to the user's requested level.

  Note that the examination setting menu as shown in FIG. 19 may be displayed on the display unit of the operation unit 200 and the examination setting may be received from the operation unit 200. In this case, the controller unit CPU 4301 holds the inspection setting information set from the operation unit 200 in the HDD 4100 or the like, and adds the inspection setting information to the print job in S202 of FIG. Good.

  Further, the inspection setting information set from the operation unit 200 may be transferred to the inspection unit 500 by the controller unit CPU 4301, held in the HDD 5011 of the inspection unit 500, and used in the density threshold value changing process of S510 in FIG. .

  As described above, according to the present embodiment, the threshold for determining the timing for performing the density adjustment operation (the determination level for determining the density difference in S310 in FIG. 10) is appropriately changed according to the user setting. Thus, the density adjustment operation of the apparatus can be performed at an appropriate timing. For example, when a user prints a printed matter that requires a high-quality image, the density unevenness inspection level is raised (for example, set to “strict”) and printed before the density difference becomes large. Density adjustment is performed, and as a result, a high-quality printed matter can be obtained. Also, when printing a print that does not require a high-quality image, set the density unevenness inspection level lower (for example, set to “sweet”) and print until the density difference becomes extremely large. Density adjustment is not performed, and printing can be performed with minimal interruption.

It should be noted that the configuration and contents of the various data described above are not limited to this, and it goes without saying that the various data and configurations are configured according to the application and purpose.
Although one embodiment has been described above, the present invention can take an embodiment as, for example, a system, apparatus, method, program, or storage medium. Specifically, the present invention may be applied to a system composed of a plurality of devices, or may be applied to an apparatus composed of a single device.
Moreover, all the structures which combined said each Example are also contained in this invention.

(Other examples)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or a processor such as a CPU or MPU) of the system or apparatus executes the program. It is a process to read and execute.

Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device.
The present invention is not limited to the above-described embodiments, and various modifications (including organic combinations of the embodiments) are possible based on the spirit of the present invention, and these are excluded from the scope of the present invention. is not. That is, the present invention includes all the combinations of the above-described embodiments and modifications thereof.

  As described above, according to the present invention, it is possible to determine the timing for performing the density adjustment operation without giving a special pattern to the printed matter and without affecting the printing operation of the apparatus. This makes it possible to adjust the density of the apparatus.

200 Operation unit 300 Printer unit 400 Controller unit 500 Inspection unit 510 Inspection control unit

Claims (10)

Printing means for performing print processing on a print medium based on print data;
Extraction means for extracting a density measurement area indicating an area for density measurement from print data printed by the printing means;
Determining means for determining an expected density indicating a density expected to be printed in the density measurement region extracted by the extracting means;
Reading means for reading image data from a printing surface of a printing medium printed by the printing means;
An actually measured density calculating means for calculating an actually measured density of an area corresponding to the density measuring area in the image data read by the reading means;
A density difference calculating means for calculating a density difference between the expected density of the area corresponding to the density measurement area and the actually measured density of the area corresponding to the density measurement area;
Determination means for determining whether or not to perform an adjustment operation for adjusting the print density of the printing means based on the density difference calculated by the density difference calculation means;
A printing apparatus comprising:   The determination means compares the density difference calculated by the density difference calculation means with a threshold value, and determines that the adjustment operation is to be executed when the density difference exceeds the threshold value. The printing apparatus as described in.   The printing apparatus according to claim 2, further comprising a changing unit that changes the threshold according to a determination level of a density difference added to the print data. Setting means for setting a judgment level of density difference;
Changing means for changing the threshold according to the determination level set by the setting means;
The printing apparatus according to claim 2, further comprising: The extraction means extracts, when the print data includes a fill command having an area exceeding a specific area, a region within the fill region specified by the fill command as a region for performing the density measurement. And
5. The determination unit according to claim 1, wherein the determination unit determines the expected density from a fill density specified by the fill command corresponding to the area extracted by the extraction unit. Printing device. Adjusting means for executing the adjusting operation;
In the adjusting operation, a pattern having a plurality of densities is formed by a printing agent color used by the printing unit on a printing medium or a transfer body for transferring an image to the printing medium by the printing unit, and the pattern is measured by the measuring unit. Measuring and adjusting the printing density of the printing means based on the measurement result of the measuring means,
The expected density and the actually measured density are density information of a color space having each printing agent color used by the printing unit as a component,
The density difference is calculated for each printing agent color,
When the determination unit determines that the adjustment operation is to be executed by the determination unit and executes the adjustment operation, the adjustment unit forms the pattern only for the printing agent color having the density difference exceeding the threshold value. The printing apparatus according to claim 2, wherein the printing apparatus is a printer. The adjusting means includes
When it is determined that the adjustment operation is performed by the determination unit, and at a specific cycle, the adjustment operation is performed.
When the adjustment operation is executed in the specific cycle, a pattern having the same density and the same density as the expected density in which the density difference from the measured density does not exceed the threshold value from the plurality of density patterns of the printing agent color. The printing apparatus according to claim 6, wherein an omitted pattern is formed.   The adjusting means includes all the printing agents used by the printing means when the extracting means, the determining means, the reading means, the actually measured density calculating means, the density difference calculating means, and the determining means are not present. The printing apparatus according to claim 6, wherein the plurality of density patterns are formed with colors. A method for controlling a printing apparatus,
A printing step in which the printing means performs a printing process on the print medium based on the print data;
An extraction step for extracting a density measurement region indicating a region for density measurement from the print data printed in the printing step;
A determination step for determining an expected density indicating a density expected to be printed in the density measurement region extracted in the extraction step;
A reading step for reading image data from a printing surface of the printing medium printed in the printing step;
An actually measured density calculating means for calculating an actually measured density of an area corresponding to the density measuring area in the image data read in the reading step;
A density difference calculating means for calculating a density difference between the expected density of the area corresponding to the density measurement area and the measured density of the area corresponding to the density measurement area; and a determination means comprising the density difference A determination step for determining whether to perform an adjustment operation for adjusting the print density of the printing unit based on the density difference calculated in the calculation step;
A control method for a printing apparatus, comprising:   The program for functioning the processor provided in the printing apparatus as a means of the printing apparatus as described in any one of Claims 1 thru | or 8.

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