JP4081999B2 - Correction of recording position misalignment during bidirectional printing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for printing an image on a print medium while performing main scanning in both directions, and more particularly to a technique for correcting a recording position shift between an outward path and a return path.
[0002]
[Prior art]
In recent years, inkjet printers are widely used as computer output devices. Some inkjet printers can perform so-called “bidirectional printing” in order to improve printing speed.
[0003]
In bidirectional printing, there is a problem that the recording position in the main scanning direction in the forward path and the backward path is shifted due to backlash of the driving mechanism in the main scanning direction, warpage of the platen that supports the printing medium below, and the like. It is likely to occur. As a technique for solving such misalignment, for example, a technique described in Japanese Patent Laid-Open No. 5-69625 disclosed by the present applicant is known. In this prior art, a positional deviation amount (print deviation) in the main scanning direction is registered in advance, and the recording positions in the forward path and the backward path are corrected based on this positional deviation amount.
[0004]
The correction value for positional deviation during bidirectional printing is usually determined by printing a test pattern. Such a test pattern is printed on a ROM built in the printing apparatus.
[0005]
By the way, the influence on the image quality due to the positional deviation during bidirectional printing depends on the printing mode (also referred to as “recording mode”). Here, the “print mode” refers to a plurality of print parameters (for example, print resolution, sub-scan feed amount during printing, ink amount of ink droplets, and dot recording on the main scan line is completed by the number of main scans. This means a printing method that is determined according to whether or not to make it. Therefore, when the print mode that can be used in the printer is changed for some reason, it is preferable to reset the correction value of the positional deviation at the time of bidirectional printing. The test pattern is also preferably printed according to the printing mode that is actually used.
[0006]
[Problems to be solved by the invention]
However, conventionally, since the test pattern is burned into the ROM built in the printing apparatus, it is difficult to print the test pattern according to the actually used printing mode.
[0007]
The present invention has been made to solve the above-described problems in the prior art, and provides a test pattern for determining a correction value for misregistration during bidirectional printing according to the actually used print mode. An object is to provide a technique capable of printing.
[0008]
[Means for solving the problems and their functions and effects]
In order to achieve the above object, a printing apparatus according to the present invention is a printing apparatus that performs bidirectional printing by recording ink dots on a print medium while moving a print head in a main scanning direction,
A main scanning drive unit that moves the print head in the main scanning direction;
A sub-scanning drive unit that moves the print medium in a sub-scanning direction;
A head drive unit that ejects ink droplets from the plurality of nozzles during main scanning of the print head;
A control unit for controlling the main scanning driving unit, the sub-scanning driving unit, and the head driving unit;
With
The print head has a plurality of nozzles arranged in the sub-scanning direction at a nozzle pitch k times (k is an integer of 2 or more) in the sub-scanning direction substantially perpendicular to the main scanning direction. Yellow and magenta And N (N is an integer greater than or equal to 2) nozzles for each color, and a color nozzle row in which a yellow nozzle group, a magenta nozzle group, and a cyan nozzle group are arranged in a row along the sub-scanning direction And
The N nozzles of each color are arranged as continuous nozzles in the sub-scanning direction, and the nozzle pitch of each color so that the nozzle pitch of the joint portion of each color nozzle group is the same value as the nozzle pitch of each color. Is placed,
The controller is
(A) As a test pattern for determining a correction value of a recording position deviation along the main scanning direction during bidirectional printing, a test pattern including a plurality of color patches respectively printed using different correction values It is possible to print according to the interlace recording mode,
(B) When performing printing, the recording position deviation is corrected according to a correction value set according to the printing result of the test pattern,
The plurality of color patches are gray patches reproduced by composite black,
The controller, when printing the test pattern,
(I) After performing (k−1) sets of scans composed of one main scan and a sub-scan feed of a first feed amount equal to the dot pitch in the sub-scan direction, Performing a main scan and a sub-scan feed of a second feed amount equal to {N × k− (k−1)} times the dot pitch;
(Ii) The test pattern is printed by repeatedly executing the main scanning and the sub-scanning in (i).
[0016]
The present invention can be realized in various forms. For example, a recording position shift correction method and apparatus during bidirectional printing, a recording position control method and apparatus during bidirectional printing, a printing method, and the like Apparatus, printing control apparatus and method for controlling printing apparatus, computer program for realizing the method and apparatus, recording medium recording the computer program, data signal embodied in a carrier wave including the computer program, It can implement | achieve in various forms, such as.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. Overall configuration of the device:
B. General procedure for bi-directional printing misalignment correction:
C. Details on how to print test patterns and determine correction values:
D. Test pattern print signal configuration:
E. Variation:
[0018]
A. Overall configuration of the device:
FIG. 1 is a block diagram showing the configuration of a printing system as an embodiment of the present invention. This printing system includes a computer 90 and a color inkjet printer 20. The printing system including the printer 20 and the computer 90 can be called a “printing apparatus” in a broad sense.
[0019]
In the computer 90, an application program 95 operates under a predetermined operating system. A video driver 91 and a printer driver 96 are incorporated in the operating system, and print data PD to be transferred to the printer 20 is output from the application program 95 via these drivers. The application program 95 that performs image retouching or the like performs desired processing on the image to be processed, and displays an image on the CRT 21 via the video driver 91.
[0020]
When the application program 95 issues a print command, the printer driver 96 of the computer 90 receives the image data from the application program 95 and converts it into print data PD to be supplied to the printer 20. The printer driver 96 includes a resolution conversion module 97, a color conversion module 98, a halftone module 99, a rasterizer 100, a user interface display module 101, a test pattern supply module 102, and a color conversion lookup table LUT. And are provided.
[0021]
The resolution conversion module 97 plays a role of converting the resolution of the color image data formed by the application program 95 into the print resolution. The image data thus converted in resolution is still image information composed of three color components of RGB. The color conversion module 98 converts RGB image data into multi-tone data of a plurality of ink colors that can be used by the printer 20 for each pixel while referring to the color conversion lookup table LUT.
[0022]
The color-converted multi-gradation data has, for example, 256 gradation values. The halftone module 99 performs so-called halftone processing to generate halftone image data. The halftone image data is rearranged in the order of data to be transferred to the printer 20 by the rasterizer 100, and output as final print data PD. The print data PD includes raster data indicating the dot formation state during each main scan and data indicating the sub-scan feed amount.
[0023]
The user interface display module 101 has a function of displaying various user interface windows related to printing, and a function of receiving user input in these windows.
[0024]
The test pattern supply module 102 reads from the hard disk 92 a test pattern print signal TPS used to determine a correction value for a recording position shift (also simply referred to as “bidirectional print shift”) during bi-directional printing. 20 is provided. When the test pattern print signal TPS is stored as compressed data, the test pattern print signal TPS has a function of expanding the compressed data.
[0025]
The printer driver 96 corresponds to a program for realizing a function of supplying the print data PD and the test pattern print signal TPS to the printer 20. A program for realizing the function of the printer driver 96 is supplied in a form recorded on a computer-readable recording medium. Such recording media include flexible disks, CD-ROMs, magneto-optical disks, IC cards, ROM cartridges, punch cards, printed matter on which codes such as bar codes are printed, computer internal storage devices (such as RAM and ROM). A variety of computer-readable media such as a memory) and an external storage device can be used. It is also possible to download such a computer program to the computer 90 via the Internet.
[0026]
A computer 90 having a printer driver 96 functions as a print control device that supplies the print data PD and the test pattern print signal TPS to the printer 20 to perform printing.
[0027]
FIG. 2 is a schematic perspective view showing the main configuration of the color inkjet printer 20. The printer 20 includes a paper stacker 22, a paper feed roller 24 driven by a step motor (not shown), a platen 26, a carriage 28, a carriage motor 30, a traction belt 32 driven by the carriage motor 30, and a carriage. And a guide rail 34 for 28. A print head 36 having a large number of nozzles is mounted on the carriage 28.
[0028]
The printing paper P is taken up by the paper feed roller 24 from the paper stacker 22 and fed on the surface of the platen 26 in the sub-scanning direction. The carriage 28 is pulled by a pulling belt 32 driven by a carriage motor 30 and moves in the main scanning direction along the guide rail 34. The main scanning direction is perpendicular to the sub-scanning direction.
[0029]
FIG. 3 is a block diagram showing an electrical configuration of the inkjet printer 20. The printer 20 includes a reception buffer memory 50 that receives a signal supplied from a computer 90, an image buffer 52 that stores print data, a system controller 54 that controls the overall operation of the printer 20, a main memory 56, and an EEPROM 58. And. The system controller 54 is further connected to a main scanning drive circuit 61 that drives the carriage motor 30, a sub-scanning drive circuit 62 that drives the paper feed motor 31, and a head drive circuit 63 that drives the print head 36. Yes.
[0030]
The main scanning drive circuit 61, the carriage motor 30, the traction belt 32 (FIG. 2), and the guide rail 34 constitute a main scanning drive mechanism. The sub-scanning drive circuit 62, the paper feed motor 31, and the paper feed roller 24 (FIG. 2) constitute a sub-scanning drive mechanism (or “feed mechanism”).
[0031]
The print data transferred from the computer 90 is temporarily stored in the reception buffer memory 50. In the printer 20, the system controller 54 reads necessary information from the print data from the reception buffer memory 50, and sends control signals to the drive circuits 61, 62, and 63 based on the read information.
[0032]
The image buffer 52 stores print data of a plurality of color components received by the reception buffer memory 50. The head drive circuit 63 reads the print data of each color component from the image buffer 52 in accordance with a control signal from the system controller 54 and drives the nozzle array of each color provided in the print head 36 in response to this.
[0033]
FIG. 4 is an explanatory diagram showing the nozzle arrangement on the lower surface of the print head 36. The print head 36 has a black nozzle row and a color nozzle row arranged on a straight line along the sub-scanning direction SS. In this specification, the “nozzle row” is also referred to as “nozzle group”.
[0034]
The black nozzle row (indicated by white circles) has 180 nozzles # 1 to # 180. These nozzles # 1 to # 180 are arranged at a constant nozzle pitch k · D along the sub-scanning direction. Here, D is the dot pitch in the sub-scanning direction SS, and k is an integer. The dot pitch D in the sub-scanning direction is equal to the pitch of the main scanning line (raster line). Hereinafter, the integer k representing the nozzle pitch k · D is simply referred to as “nozzle pitch k”. The unit of the nozzle pitch k is [dot], which means the dot pitch in the sub-scanning direction.
[0035]
In the example of FIG. 4, the nozzle pitch k is 4 dots. However, the nozzle pitch k can be set to an arbitrary integer of 2 or more.
[0036]
The color nozzle array includes a yellow nozzle group Y (indicated by white triangles), a magenta nozzle group M (indicated by white squares), and a cyan nozzle group C (indicated by white rhombuses). In this specification, the nozzle group for chromatic ink is also referred to as a “chromatic nozzle group”. Each chromatic nozzle group has 60 nozzles # 1 to # 60. Further, the nozzle pitch of the chromatic nozzle group is the same as the nozzle pitch k of the black nozzle row. The nozzles of the chromatic color nozzle group are arranged at the same sub-scanning position as the nozzles of the black nozzle row.
[0037]
At the time of printing, ink droplets are ejected from each nozzle while the print head 36 is moving at a constant speed in the main scanning direction together with the carriage 28 (FIG. 2). However, depending on the printing method, not all nozzles are always used, and only some nozzles may be used.
[0038]
In black and white printing, almost all 180 black nozzles are used. On the other hand, in color printing, 60 nozzles are used for each color of CMY, and 60 black nozzles are also used. The 60 black nozzles used in color printing are, for example, nozzles # 121 to # 180 arranged at the same sub-scanning position as the 60 cyan nozzles.
[0039]
FIG. 5 is a block diagram showing a main configuration related to correction of bidirectional printing misalignment. The EEPROM 58 of the printer 20 includes a correction value number storage area 200 and a correction value table 210. In the correction value number storage area 200, a number indicating a preferable correction value is stored. The correction value table 210 is a table that stores the relationship between correction value numbers and correction values.
[0040]
The system controller 54 has a function as a positional deviation correction execution unit 220 for correcting bidirectional printing deviation. When the positional deviation correction execution unit 220 receives a signal indicating the origin position of the carriage 28 from the position sensor 39 in the return path, the signal for instructing the recording timing of the head according to the correction value supplied from the correction value table 210. (Delay amount setting value ΔT) is supplied to the head drive circuit 63. The head drive circuit 63 supplies a drive signal to each nozzle of the print head 36, and adjusts the print position of the return path according to the print timing (that is, the delay amount setting value ΔT) given from the position deviation correction execution unit 220. To do. As a result, the recording position of each nozzle row is adjusted with the same correction value in the return path.
[0041]
B. General procedure for bi-directional printing misalignment correction:
As will be described below, the bi-directional printing misalignment is corrected before shipment of the printer 20 and can be corrected by the user after shipment.
[0042]
FIG. 6 is a flowchart showing the procedure of bidirectional printing misalignment correction before the printer 20 is shipped. In step S1, printing modes scheduled to be used by the printer 20 are sequentially selected. FIG. 7 shows an example of the print mode. Here, six print modes are shown, and these are classified into three sets according to the print resolution. The print resolution of the two low resolution print modes PM1a and PM1b is 720 × 720 dpi. In this specification, the printing resolution is expressed by (printing resolution in the main scanning direction) × (printing resolution in the sub-scanning direction). In the low resolution printing modes PM1a and PM1b, the first variable size dot VSD1 including three types of dots having ink weights of 6.5 ng, 10 ng, and 20 ng can be used. The difference between the two low-resolution printing modes PM1a and PM1b is in the paper feed mode (sub-scan feed mode) and the nozzle row to be used. That is, the first low-resolution printing mode PM1a is a printing mode for color printing, and the color mode 1 described later is used as the paper feed mode. On the other hand, the second low-resolution printing mode PM1b is a printing mode for monochrome printing, and uses a monochrome mode 1 described later as the paper feed mode. The other print modes PM2a, PM2b, PM3a, and PM3b are different from the low-resolution print modes PM1a and PM1b in any of the print parameters.
[0043]
In step S2, a test pattern is printed according to the selected print mode. FIG. 8 shows an example of a test pattern using color patches. In this example, a test pattern including three color patches having different positional deviation correction values δ is shown. The correction value number (also referred to as “patch number”) printed beside each color patch is associated in advance with the positional deviation correction value δ. However, the positional deviation correction value δ is drawn for convenience only and is not actually printed. Each color patch is a gray patch in which a gray region having a uniform density is reproduced with composite black using CMY inks. Such a gray patch reflects both bidirectional printing misalignment and misalignment between dots of each color. Since the actual image quality of printed matter affects not only bidirectional printing deviation but also deviation between dots of each color, it is preferable to use a gray patch reproduced with composite black as a test pattern from the viewpoint of improving the image quality. .
[0044]
However, various other patterns can be used as the test pattern. For example, other types of color patches can be used. In the present specification, “color patch” means an image area reproduced in a substantially uniform color. Details of the test pattern printing method will be described later.
[0045]
In this specification, “composite black” means a gray color reproduced using inks of three hues of CMY, and may be reproduced using three or more types of inks. For example, when dark ink and light ink can be used for cyan and magenta, it is also possible to reproduce composite black using these four types of ink and five types of yellow ink.
[0046]
FIG. 9 shows an example of a test pattern using vertical ruled lines. In this test pattern, a plurality of pairs of ruled lines recorded respectively on the forward path and the return path are printed. In each ruled line pair, the recording timing on the return path is different from each other by a certain amount. This difference in recording timing corresponds to a correction value number (that is, a positional deviation correction value).
[0047]
As a test pattern, a color patch as shown in FIG. 8 may be used, or a ruled line as shown in FIG. 9 may be used. However, an example in which a test pattern using color patches is mainly used will be described below.
[0048]
In step S3 of FIG. 6, the color patch with the highest image quality is selected from the plurality of printed color patches, and the correction value number is set in the EEPROM 58 (FIG. 3) of the printer 20. In the example of FIG. 8, white stripes are generated in the uppermost color patch, and black stripes are generated in the lowermost color patch. Therefore, the correction value number of the central color patch without such image quality deterioration is stored in the EEPROM 58. The correction value set by the inspection before shipment is referred to as “reference correction value”.
[0049]
In step S4, it is determined whether or not steps S1 to S3 have been completed for all print modes scheduled to be used by the printer 20, and if not, the process returns to step S1. Here, “all print modes scheduled to be used by the printer 20” means types of print modes that can be selected by the user in the property window of the printer driver 96 (FIG. 1). In this way, the reference correction value for bidirectional printing misalignment is set for all types of printing paper.
[0050]
FIG. 10 is a flowchart showing a procedure of bidirectional printing misalignment correction by the user. In step S11, the user selects a print mode, and in step S12, a test pattern is printed by inputting a test pattern print command. FIG. 11 is an explanatory diagram illustrating an example of a user interface window W1 that allows a user to issue a test pattern print instruction. This window W1 is a utility window in the printer properties, and is provided with a button B1 for inputting a print instruction for a test pattern for bidirectional printing timing adjustment. When the user clicks the button B1, the test pattern supply module 102 (FIG. 1) reads the test pattern print signal TPS from the hard disk 92 and supplies it to the printer 20, and the printer 20 prints the test pattern accordingly. This test pattern may be the same as the test pattern (FIG. 8) used for bidirectional printing misalignment correction before shipment, or may be a different test pattern. In this embodiment, it is assumed that the test pattern shown in FIG. 8 is also used for bidirectional printing misalignment correction by the user. The configuration of the test pattern print signal TPS will be described later.
[0051]
In step S13 of FIG. 10, a color patch with the highest image quality is selected from a plurality of printed color patches, and the correction value number is set. FIG. 12 is an explanatory diagram showing an example of a user interface window W2 that allows the user to set a preferable correction value number. This window W2 is automatically displayed by the user interface display module 101 (FIG. 1) when the test pattern is printed. The window W2 is provided with a plurality of buttons B11 to B13 for selecting a preferable correction value number. When the user clicks one of these buttons B11 to B13, a preferable correction value number is set in the EEPROM 58 (FIG. 3) of the printer 20. The correction value number may be registered in the EEPROM 58 as a replacement for the reference correction value set in step S3 in FIG. 6, or may be registered in the EEPROM 58 as a value for further correcting the reference correction value. The correction value number indicating the correction value by the user may be registered in the printer driver 96 instead of the EEPROM 58.
[0052]
In step S14 of FIG. 10, actual printing is executed in accordance with a user instruction. At this time, the circuit shown in FIG. 5 controls the ink ejection operation from the print head 36 in accordance with the correction value set in step S13.
[0053]
C. Details on how to print test patterns and determine correction values:
FIG. 13 shows an example of paper feed used when printing a test pattern in step 2 of FIG. 6 and step S12 of FIG. Here, the positions of the print head 36 in the sub-scanning direction in the five passes 1 to 5 are shown. Here, “pass” means one main scan. In FIG. 13, for convenience of illustration, the print head 36 has a small number of nozzles, the number of black nozzles (indicated by white circles) is nine, and the number of chromatic nozzles for one color is three. It is said that. Further, since the composite black gray patch shown in FIG. 7 is reproduced, nine black nozzles are not used. In other words, three nozzles are used for three colors of CMY.
[0054]
The odd-numbered paths (paths 1, 3, and 5) are forward paths, and the even-numbered paths (paths 2 and 4) are paths on the return path. Note that white figures (white triangles, white squares, and white rhombuses) indicate nozzles that record dots in the forward path. Black figures (black triangles, black squares, and black diamonds) indicate nozzles that record dots on the return path.
[0055]
Here, since the nozzle pitch k is 4 dots, there is a gap of 3 lines between raster lines (main scanning lines) recorded in one pass. The paper feed amounts F1, F2, and F3 after passes 1, 2, and 3 are each one dot. Therefore, in passes 2 to 4, three lines of gaps that were not recorded in pass 1 are recorded. The raster line position recorded in passes 1 to 4 is shown at the right end of FIG. As can be understood from this, in the passes 1 to 4, twelve continuous lines are recorded with one color of ink. Here, the twelve lines recorded in yellow are referred to as “yellow color band YCB”. Similarly, twelve lines recorded in magenta are called “magenta color band MCB”, and twelve lines recorded in cyan are called “cyan color band CCB”. These color bands are the same as the raster lines printed in one pass for each ink using a virtual dense nozzle row having 12 nozzles arranged with a nozzle pitch k of 1 dot. In other words, passes 1 to 4 are equivalent to a single pass using a dense nozzle array as shown at the right end of FIG.
[0056]
The paper feed amount F4 after pass 4 is 9 dots. By this paper feed, the uppermost nozzle of the yellow nozzle of the print head 36 is positioned at the uppermost end of the area where no yellow dot is recorded. The same applies to the nozzles at the upper ends of the other inks. Such a recording method is substantially equivalent to a recording method in which the virtual dense nozzle row shown at the right end of FIG. 13 is used and paper is fed by a bandwidth Lc1 for one color for each pass. I understand that. Therefore, paper feeding as shown in FIG. 13 is called “pseudo band feeding”.
[0057]
The feed amount F4 after pass 4 is equal to the value obtained by subtracting the total value (= 3 dots) of the previous three feed amounts F1 to F3 from the band width Lc1 for one color. Therefore, the total ΣFi of the feed amounts F1 to F4 for four times is equal to the band width Lc1 for one color. Note that the band width Lc1 for one color is equal to the range of one chromatic color nozzle array, which is a value N × k (== multiplying the number of nozzles N (= 3) and the nozzle pitch k (= 4). 12).
[0058]
In FIG. 13, for convenience of explanation, the number N of nozzles per color is set to 3, but the number N of nozzles per color is actually several tens or more. FIG. 14 shows an example of the paper feed amount used for actual printing using the print head 36 shown in FIG. Such an actual paper feed amount is preset in the printer driver 96. FIG. 14A shows an example of pseudo band feeding. In the color mode 1, the three feed amounts F1 to F3 are 1 dot, and the fourth feed amount F4 is 237 dots. The total of these four feed amounts F1 to F4 is equal to the band width N × k (= 240) for one color. The number N of nozzles used for one color is 60. FIG. 13 is a simplified drawing of the color mode 1 paper feed.
[0059]
In monochrome mode 1 in FIG. 14A, 180 black nozzles are used. The third feed amount F1 to F3 is 1 dot, and the fourth feed amount F4 is 717 dots. The total of these four feed amounts F1 to F4 is equal to the black nozzle bandwidth N × k (= 720).
[0060]
FIG. 14B shows an example of the paper feed amount in the normal interlace recording mode printing that is not pseudo band feeding. Here, “interlace recording mode” means a printing method in which a gap is generated between raster lines recorded in one pass. In other words, a printing method using a print head having a nozzle pitch k of 2 dots or more corresponds to the “interlace recording mode”.
[0061]
In the example of FIG. 14B, each feed amount Fi is set to a constant integer value equal to the number N of used nozzles and relatively prime to the nozzle pitch k. Here, when two integers are “relative to each other”, it means that there is no common divisor other than 1. In the color mode 2 in FIG. 14B, since the number N of used nozzles is 59, one of the 60 nozzles of each color is not used. In monochrome mode 2, since the number of used nozzles N is 179, one of the 180 black nozzles is not used. In this specification, sub-scanning in which the paper feed amount Fi is a constant value is referred to as “regular feed”. It is also possible to use “anomalous feed” that employs a plurality of different values as the paper feed amount Fi.
[0062]
The pseudo band feed shown in FIG. 14A is a paper feed that is most frequently used when printing an actual printed matter in the printer 20 having the print head 36 shown in FIG. Therefore, printing the test pattern using the pseudo band feed shown in FIG. 14A is preferable in the sense that the test pattern is printed using the paper feed most frequently used in actual printing as it is.
[0063]
The test pattern print signal TPS representing the test pattern is registered in the printer driver 96 (FIG. 1) and stored as a file for the printer driver 96 in the hard disk 92 of the computer 90. The test pattern print signal TPS has the same format as the print data PD (including raster data and paper feed amount) transmitted from the printer driver 96 to the printer 20. However, the test pattern print signal TPS is preferably stored in a data-compressed format. When the user gives an instruction to print a test pattern, the test pattern print signal TPS is called by the test pattern supply module 102, decompressed as necessary, and transferred to the printer 20. Thus, in this embodiment, the test pattern printing signal TPS is registered in the printer driver 96 in a format that can be transferred to the printer 20 as it is, so that there is an advantage that the test pattern can be printed in a short time. . This advantage is particularly remarkable when a test pattern having a two-dimensional spread is used, such as the color patch shown in FIG.
[0064]
In this embodiment, since the test pattern print signal TPS is stored as a file of the printer driver 96, when the specification of the printer driver 96 is changed, the test pattern print signal TPS is simultaneously sent together with the printer driver 96. There is an advantage that the version can be upgraded. Therefore, it is possible to use the test pattern printed in accordance with the printing mode actually used by the printer driver 96 for correcting the bi-directional printing misalignment. Further, it is possible to improve the image quality by correcting the bidirectional printing misalignment with a correction amount suitable for the actual print mode.
[0065]
D. Test pattern print signal configuration:
FIG. 15 shows a method for printing a test pattern color patch. The virtual dense nozzle row 36a shown in FIG. 13 is shown on the left side of FIG. As described with reference to FIG. 13, the dense nozzle row 36a is constituted by four passes. The nozzles that record dots in the forward pass are shown as white graphics, and the nozzles that record dots in the return pass are shown as black graphics. It can be considered that the dense nozzle row 36a is sub-scan fed by the band width Lc1 for one color.
[0066]
In the right half of FIG. 15, using such a dense nozzle row 36a, there is a raster data configuration representing the recording state of dots in four rows of pixels # 1 to # 4 on 12 raster lines L1 to L12. It is shown. According to this raster data, dots are recorded in the forward path at odd pixel positions # 1, # 3... On odd-numbered raster lines L1, L3. Also, dots are recorded in the backward path at even pixel positions # 2, # 4,... On even-numbered raster lines L2, L4,. In the example of FIG. 15, Y, M, and C dots are formed on the same pixel position, but they may be recorded at different positions.
[0067]
FIG. 16 shows an example of a test pattern print signal for reproducing the patch with the correction value number = 2 shown in FIG. Here, for convenience of illustration, only the Y component of the raster data RD2 is shown. FIG. 17 shows an example of a test pattern print signal for reproducing the patch with the correction value number = 1. In the raster data RD1 included in this print signal, the dot recording position in the return path is shifted to the left by one pixel compared to FIG. Each patch shown in FIG. 8 can be printed by adjusting the dot recording position in the return path (or forward path) in this way.
[0068]
FIG. 18 is an explanatory diagram of a configuration example of a test pattern print signal. The print signal for each patch includes a paper feed amount, raster data, and a dot type. In the first example shown in FIG. 18A, the print signals for each patch have different raster data. The paper feed amount is common to the three patches, and the dot type is also common in that only the medium dots of the first variable size dot VSD1 are used.
[0069]
In the second example shown in FIG. 18B, the print signal for each patch includes a positional deviation correction value in addition to the paper feed amount, raster data, and dot type. The raster data in the print signal for each patch is the same, but the positional deviation correction values are different from each other. As the raster data, the data RD2 having no positional deviation shown in FIG. 16 is used.
[0070]
Each of the print signals in FIGS. 18A and 18B can print the three patches shown in FIG. However, as shown in FIG. 18A, when printing each patch using raster data simulating the positional deviation during bidirectional printing, the unit of the positional deviation correction value to be set is the main scanning direction. It is limited to an integer multiple of the pixel pitch. On the other hand, as shown in FIG. 18B, when the raster data is the same and each patch is printed using the positional deviation correction value, the unit of the positional deviation correction value is finer than the pixel pitch in the main scanning direction. Can be set in units.
[0071]
E. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0072]
E1. Modification 1:
In the above embodiment, a color ink jet printer has been described. However, the present invention can also be applied to a monochrome printer, and can also be applied to printers other than the ink jet system. The present invention is generally applicable to a printing apparatus that records an image on a print medium, and can also be applied to, for example, a facsimile machine and a copier.
[0073]
E2. Modification 2:
In the above-described embodiment, an example in which the print head 36 (FIG. 4) in which the chromatic nozzle rows are aligned in the sub-scanning direction has been described. However, the present invention includes a print head having an arbitrary nozzle arrangement. Applicable to printing devices.
[0074]
E3. Modification 3:
In the above embodiment, the correction value is determined by one type of test pattern, but the correction value may be determined by using a plurality of types of test patterns. For example, the coarse correction value may be determined using the first test pattern for coarse adjustment, and the final fine correction value may be determined using the second test pattern for fine adjustment. For example, a coarse correction value can be set at an interval of 10 steps, and a fine correction value can be set at an interval of 1 step. In this way, if a plurality of adjustments are performed, it is possible to efficiently determine a fine correction value.
[0075]
E4. Modification 4:
In the above embodiment, the gray patch reproduced with composite black is used as the color patch of the test pattern. However, a color patch other than this can be used. For example, it is also possible to use a gray patch reproduced only with black ink, or a single color patch reproduced with cyan ink or magenta ink. Alternatively, it is also possible to use secondary color patches that are reproduced using two of the three colors of cyan, magenta, and yellow. As the ink used for reproducing the color patch, an ink having a color component for which image quality improvement is desired by correcting bidirectional printing misalignment is selected. That is, if a color patch is reproduced using ink of a color component whose image quality is to be improved by correcting bidirectional printing misalignment, the ink is often used by correcting the bidirectional printing misalignment using the color patch. It is possible to improve the image quality.
[0076]
E5. Modification 5:
In the above embodiment, the correction value is determined by observing the test pattern by human beings, but instead, the image quality of the test pattern is mechanically measured, and the image quality of the bidirectional printing misalignment is obtained. The correction unit may correct the dot formation timing during bidirectional printing according to the actual measurement result. In this way, it is possible to appropriately correct the bi-directional printing misalignment without requiring manual work.
[0077]
E6. Modification 6:
In the above embodiment, printing is performed according to the interlaced recording mode, but the present invention can also be applied to the case where printing is performed according to the non-interlaced recording mode. The “non-interlaced recording mode” means a printing method performed using nozzles arranged at a nozzle pitch equal to the dot pitch in the sub-scanning direction (that is, the main scanning line pitch).
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of a printing system as an embodiment of the present invention.
FIG. 2 is a schematic perspective view showing a main configuration of the color inkjet printer 20;
FIG. 3 is a block diagram showing an electrical configuration of the printer 20;
4 is an explanatory diagram showing a nozzle arrangement on the lower surface of the print head 36. FIG.
FIG. 5 is a block diagram showing a main configuration related to correction of bidirectional printing misalignment.
FIG. 6 is a flowchart showing a procedure for correcting misalignment of bidirectional printing before shipment of the printer.
FIG. 7 is an explanatory diagram illustrating an example of a print mode.
FIG. 8 is an explanatory diagram showing an example of a test pattern using color patches.
FIG. 9 is an explanatory diagram showing an example of a test pattern using vertical ruled lines.
FIG. 10 is a flowchart illustrating a procedure for correcting bidirectional printing misalignment by a user.
FIG. 11 is an explanatory diagram showing an example of a user interface window W1 that allows a user to issue a test pattern print instruction;
FIG. 12 is an explanatory diagram showing an example of a user interface window W2 that allows a user to set a correction value number.
FIG. 13 is an explanatory diagram illustrating an example of paper feeding used when printing a test pattern.
FIG. 14 is an explanatory diagram showing an example of paper feeding when the print head of FIG. 4 is used.
FIG. 15 is an explanatory diagram illustrating a method for printing a test pattern.
FIG. 16 is an explanatory diagram showing the contents of a print signal for a patch with correction value number 2;
FIG. 17 is an explanatory diagram showing the contents of a print signal for a patch with correction value number 1;
FIG. 18 is an explanatory diagram showing a configuration example of a test pattern print signal.
[Explanation of symbols]
20 ... Inkjet printer
21 ... CRT
22 ... Paper stacker
24. Paper feed roller
26 ... Platen
28 ... Carriage
30 ... Carriage motor
31 ... Paper feed motor
32 ... Traction belt
34 ... Guide rail
36 ... Print head
36a ... dense nozzle array
39 ... Position sensor
50: Receive buffer memory
52 ... Image buffer
54 ... System controller
56 ... Main memory
58… EEPROM
61. Main scan driving circuit
62 ... Sub-scanning drive circuit
63. Head drive circuit
90 ... Computer
91 ... Video driver
92: Hard disk
95 ... Application program
96 ... Printer driver
97 ... Resolution conversion module
98 ... Color conversion module
99 ... Halftone module
100 ... Rasterizer
101 ... User interface display module
102 ... Test pattern supply module
200: Correction value number storage area
210 ... Correction value table
220: Position misalignment correction execution unit

Claims (3)

A printing apparatus that performs bidirectional printing by recording ink dots on a print medium while moving a print head in a main scanning direction,
A main scanning drive unit that moves the print head in the main scanning direction;
A sub-scanning drive unit that moves the print medium in a sub-scanning direction;
A head drive unit that ejects ink droplets from the plurality of nozzles during main scanning of the print head;
A control unit for controlling the main scanning driving unit, the sub-scanning driving unit, and the head driving unit;
With
The print head has a plurality of nozzles arranged in the sub-scanning direction at a nozzle pitch k times (k is an integer of 2 or more) in the sub-scanning direction substantially perpendicular to the main scanning direction. Yellow and magenta And N (N is an integer greater than or equal to 2) nozzles for each color, and a color nozzle row in which a yellow nozzle group, a magenta nozzle group, and a cyan nozzle group are arranged in a row along the sub-scanning direction And
The N nozzles of each color are arranged as continuous nozzles in the sub-scanning direction, and the nozzle pitch of each color so that the nozzle pitch of the joint portion of each color nozzle group is the same value as the nozzle pitch of each color. Is placed,
The controller is
(A) As a test pattern for determining a correction value of a recording position deviation along the main scanning direction during bidirectional printing, a test pattern including a plurality of color patches respectively printed using different correction values It is possible to print according to the interlace recording mode,
(B) When performing printing, the recording position deviation is corrected according to a correction value set according to the printing result of the test pattern,
The plurality of color patches are gray patches reproduced by composite black,
The controller, when printing the test pattern,
(I) After performing (k−1) sets of scans composed of one main scan and a sub-scan feed of a first feed amount equal to the dot pitch in the sub-scan direction, Performing a main scan and a sub-scan feed of a second feed amount equal to {N × k− (k−1)} times the dot pitch;
(Ii) printing the test pattern by repeatedly performing main scanning and sub-scanning in (i);
Printing device. Correction of recording position misalignment along the main scanning direction in bidirectional printing in a printing apparatus that performs bidirectional printing by recording ink dots on a print medium while moving a print head having a plurality of nozzles in the main scanning direction A method,
(A) A test pattern including a plurality of color patches each printed using different correction values is predetermined as a test pattern for determining a correction value of a recording position shift along the main scanning direction during the bidirectional printing. Printing according to the interlaced recording mode of
(B) When printing an image in the predetermined interlaced recording mode, the recording position deviation along the main scanning direction during bidirectional printing is corrected according to the correction value set according to the printing result of the test pattern. And a process of
With
The print head has a plurality of nozzles arranged in the sub-scanning direction at a nozzle pitch k times (k is an integer of 2 or more) in the sub-scanning direction substantially perpendicular to the main scanning direction. Yellow and magenta And N (N is an integer greater than or equal to 2) nozzles for each color, and a color nozzle row in which a yellow nozzle group, a magenta nozzle group, and a cyan nozzle group are arranged in a row along the sub-scanning direction And
The N nozzles of each color are arranged as continuous nozzles in the sub-scanning direction, and the nozzle pitch of each color so that the nozzle pitch of the joint portion of each color nozzle group is the same value as the nozzle pitch of each color. Is placed,
The plurality of color patches are gray patches reproduced by composite black,
The step (a)
(I) After performing (k−1) sets of scans composed of one main scan and a sub-scan feed of a first feed amount equal to the dot pitch in the sub-scan direction, Performing a main scan and a sub-scan feed of a second feed amount equal to {N × k− (k−1)} times the dot pitch;
(Ii) printing the test pattern by repeatedly executing the step (i);
including,
Correction method. Using a print head having a plurality of nozzles arranged in the sub-scanning direction at a nozzle pitch k times (k is an integer of 2 or more) in the sub-scanning direction substantially perpendicular to the main scanning direction. Computer program for causing a printing apparatus that performs bidirectional printing by recording ink dots on a print medium while moving in the main scanning direction to correct a recording position shift along the main scanning direction during bidirectional printing Because
(A) A test pattern including a plurality of color patches each printed using different correction values is predetermined as a test pattern for determining a correction value of a recording position shift along the main scanning direction during the bidirectional printing. Printing according to the interlaced recording mode of
(B) When printing an image in the predetermined interlaced recording mode, the recording position deviation along the main scanning direction during bidirectional printing is corrected according to the correction value set according to the printing result of the test pattern. And a process of
Including a program for causing the computer to realize
The print head has a plurality of nozzles arranged in the sub-scanning direction at a nozzle pitch k times (k is an integer of 2 or more) in the sub-scanning direction substantially perpendicular to the main scanning direction. Yellow and magenta And N (N is an integer greater than or equal to 2) nozzles for each color, and a color nozzle row in which a yellow nozzle group, a magenta nozzle group, and a cyan nozzle group are arranged in a row along the sub-scanning direction And
The N nozzles of each color are arranged as continuous nozzles in the sub-scanning direction, and the nozzle pitch of each color so that the nozzle pitch of the joint portion of each color nozzle group is the same value as the nozzle pitch of each color. Is placed,
The plurality of color patches are gray patches reproduced by composite black,
The step (a)
(I) After performing (k−1) sets of scans composed of one main scan and a sub-scan feed of a first feed amount equal to the dot pitch in the sub-scan direction, Performing a main scan and a sub-scan feed of a second feed amount equal to {N × k− (k−1)} times the dot pitch;
(Ii) printing the test pattern by repeatedly executing the step (i);
including,
Computer program.

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