JP4165048B2 - Determining the adjustment value for dot recording position deviation using different test patterns for each printing mode - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for printing an image by forming dots on a printing medium while performing main scanning, and more particularly, to a technique for improving the quality of a printing result in each printing mode in a printing apparatus having a plurality of printing modes. .
[0002]
[Prior art]
In recent years, as an output device of a computer, there is a printer that prints an image by ejecting ink droplets from nozzles while performing main scanning to form dots on a printing medium. In addition, as a printing method, there are unidirectional printing in which printing is performed only in one of the forward path and the backward path of main scanning, and bidirectional printing in which printing is performed in both the forward path and the backward path.
[0003]
[Problems to be solved by the invention]
In printing in which ink droplets are ejected from the nozzles to form dots on the print medium, the dot deformation is caused by backlash of the drive mechanism in the main scanning direction, warpage of the platen that supports the print medium, etc. The recording position may be shifted. As a technique for solving such a positional deviation, a technique is known in which an adjustment value for canceling the dot formation positional deviation in the main scanning direction is registered in advance, and the recording position in the forward path and the backward path is corrected based on the adjustment value. It has been. Such correction of the dot formation position deviation is performed based on one adjustment value for each printing apparatus.
[0004]
However, in a printing apparatus having a plurality of printing modes, it is not always possible to perform high-quality printing in all printing modes by performing correction based on one adjustment value.
[0005]
The present invention has been made to solve the above-described problems in the prior art, and an object of the present invention is to provide a technique for improving the quality of printing results in each printing mode in a printing apparatus having a plurality of printing modes. .
[0006]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the above-described problems, in the present invention, in a printing apparatus having a plurality of printing modes that use the same type of ink droplets and have different usage ratios of the ink droplets to be used, Perform predetermined processing. The printing apparatus includes a print head having a nozzle capable of ejecting a plurality of types of ink droplets, a main scan driving unit that performs main scan for moving at least one of the print head and the print medium, and a plurality of pattern data. A pattern data storage unit to be stored, an input unit that receives external data input, and a control unit that controls printing are provided. The pattern data stored in the pattern data storage unit is a plurality of pattern data determined according to each print mode in order to print the adjustment value pattern according to each print mode, and the adjustment value according to the print mode At least one of the patterns is a pattern composed of a plurality of types of dots, and the ratio of the types of dots constituting each adjustment value pattern is different from each other.
[0007]
In such a printing apparatus, based on the pattern data corresponding to the print mode and the plurality of adjustment candidate values, a plurality of adjustment value patterns respectively corresponding to the respective adjustment candidate values are formed on the print medium. Then, based on a plurality of adjustment value patterns formed on the print medium, an adjustment value is selected from a plurality of adjustment candidate values. The selected adjustment value is input from the input unit and stored in the adjustment value storage unit of the printing apparatus. With such an aspect, it is possible to determine an appropriate adjustment value according to each print mode in which the usage ratios of a plurality of types of ink droplets are different from each other.
[0008]
In addition, in a printing apparatus having a plurality of print modes in which combinations of drive signals used for ejecting a plurality of types of ink droplets are different from each other, the following processing may be performed. In this printing apparatus, the pattern data stored in the pattern data storage unit is a plurality of pattern data determined according to each print mode in order to print an adjustment value pattern according to the print mode, and each adjustment data The ratio of the types of dots constituting the value pattern is different pattern data.
[0009]
In such a printing apparatus, based on the pattern data corresponding to the print mode and the plurality of adjustment candidate values, a plurality of adjustment value patterns respectively corresponding to the respective adjustment candidate values are formed on the print medium. Then, based on a plurality of adjustment value patterns formed on the print medium, an adjustment value is selected from a plurality of adjustment candidate values. With such an aspect, an appropriate adjustment value can be determined according to each of a plurality of print modes in which combinations of drive signals used for ejecting a plurality of types of ink droplets are different from each other.
[0010]
The plurality of printing modes can include two or more printing modes having different dot recording densities. The adjustment value determined as described above is particularly effective in improving the quality of the print result in any of such print modes.
[0011]
In addition, when the nozzles are arranged in a plurality of nozzle rows extending in the direction intersecting the main scanning direction on the print head, ink droplets from different nozzle rows are formed when the adjustment value pattern is formed. It is preferable to form each adjustment value pattern on a printing medium by discharging. With such an aspect, it is possible to determine an adjustment value that makes the dot formation position deviation of ink droplets ejected from different nozzle rows inconspicuous.
[0012]
It should be noted that when the adjustment value pattern is formed, it is also possible to form each adjustment value pattern on the print medium by ejecting ink droplets in the forward and backward passes of the main scanning. With such an aspect, it is possible to determine an adjustment value that makes the dot formation position deviation of ink droplets ejected in the forward and backward passes of main scanning inconspicuous.
[0013]
The adjustment value pattern is preferably a uniform color patch. With such an aspect, it is possible to determine an adjustment value that can improve the quality of the printing result for a uniform color portion in the printed image. The uniform color can be, for example, gray or skin color.
[0014]
Note that the present invention can be realized in various modes as described below. (1) Adjustment value determination method, printing method, printing control method.
(2) Printing device and printing control device.
(3) A computer program for realizing the above apparatus and method.
(4) A recording medium on which a computer program for realizing the above apparatus and method is recorded.
(5) A data signal embodied in a carrier wave including a computer program for realizing the above-described apparatus and method.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. Summary of embodiment:
B. First embodiment:
B1. Device configuration:
B2. Configuration and processing of head drive circuit:
B3. Occurrence of recording position deviation in the main scanning direction:
B4. Adjustment value setting:
C. Second embodiment:
D. Third embodiment:
E. Modified example
[0016]
A. Summary of embodiment:
FIG. 1 is an explanatory diagram showing an outline of an embodiment of the present invention. The printing apparatus according to the present invention uses the first printing mode and the second printing mode, which uses ink droplets common to the first printing mode, but has different usage ratios and dot recording densities. Printing can be performed. In this printing apparatus, the deviation of the dot formation position between the forward path and the backward path is eliminated by adjusting the ejection timing of the ink droplets in the backward path of the main scanning.
[0017]
When determining the adjustment values for the first print mode, as shown in FIG. 1A, the first gray patches T21 to T25 (T24, T25) each corresponding to the adjustment candidate value for the first print mode. (Not shown in FIG. 1) is formed on the printing paper based on the same pattern data D1. Then, the patch with the highest print result quality is selected from the patches, and the adjustment candidate value corresponding to the patch is set as the adjustment value of the first print mode. On the other hand, when the adjustment values for the second print mode are determined, the second gray patches T31 to T35 (T34 and T35 are not shown in FIG. 1) respectively corresponding to the adjustment candidate values for the second print mode. Are formed on the printing paper based on the same pattern data D2. Then, the patch with the highest print quality is selected from those patches, and the adjustment candidate value corresponding to the patch is set as the adjustment value of the second print mode.
[0018]
The print image specified by the image data D1 as a whole includes medium dots Dm and small dots Ds in a ratio of 1: 3. On the other hand, the print image of the image data D2 includes medium dots Dm and small dots Ds in a ratio of 1: 2. These dot mixture ratios are dot mixture ratios in which the dot formation position shift is most noticeable in each print mode. If the adjustment value is determined in this way, an adjustment value that can improve the quality of the portion where the dot formation position shift is most noticeable in the printed image can be determined for each print mode.
[0019]
B. First embodiment:
B1. Device configuration:
FIG. 2 is a schematic configuration diagram of a printing system including an inkjet printer 20 as an embodiment of the present invention. The printer 20 includes a sub-scan feed mechanism that transports the printing paper P in the sub-scan direction by the paper feed motor 22 and a main scan feed that reciprocates the carriage 30 in the axial direction (main scan direction) of the platen 26 by the carriage motor 24. A mechanism, a head drive mechanism that drives a print head unit 60 mounted on the carriage 30 to control ink ejection and dot formation, and these paper feed motor 22, carriage motor 24, print head unit 60, and operation panel 32 And a control circuit 40 that controls the exchange of signals with the. The control circuit 40 is connected to the computer 88 via the connector 56.
[0020]
The sub-scan feed mechanism that transports the printing paper P includes a gear train (not shown) that transmits the rotation of the paper feed motor 22 to the platen 26 and a paper transport roller (not shown). Further, the main scanning feed mechanism for reciprocating the carriage 30 has an endless drive belt 36 between the carriage motor 24 and a slide shaft 34 that is installed in parallel with the axis of the platen 26 and slidably holds the carriage 30. And a position sensor 39 for detecting the origin position of the carriage 30.
[0021]
FIG. 3 is a block diagram showing the configuration of the printer 20 with the control circuit 40 as the center. The control circuit 40 is configured as an arithmetic and logic circuit including a CPU 41, a programmable ROM (PROM) 43, a RAM 44, and a character generator (CG) 45 that stores a dot matrix of characters. The control circuit 40 further includes an I / F dedicated circuit 50 dedicated to interface with an external motor and the like, and a head that is connected to the I / F dedicated circuit 50 and drives the print head unit 60 to eject ink. A drive circuit 52 and a motor drive circuit 54 for driving the paper feed motor 22 and the carriage motor 24 are provided. The I / F dedicated circuit 50 incorporates a parallel interface circuit and can receive a print signal PS supplied from the computer 88 via the connector 56.
[0022]
FIG. 4 is an explanatory diagram showing a plurality of rows of nozzles provided in the print head 28. The printer 20 performs printing using six colors of ink of black (K), dark cyan (C), light cyan (LC), dark magenta (M), light magenta (LC), and yellow (Y). The apparatus includes a nozzle row for each ink extending in a direction perpendicular to the main scanning direction. Note that dark cyan and light cyan are cyan inks having substantially the same hue and different densities. The same applies to dark magenta ink and light magenta ink.
[0023]
B2. Configuration and processing of head drive circuit:
FIG. 5 is a block diagram showing a configuration of the head drive circuit 52. The head drive circuit 52 includes a plurality of mask circuits 204, an original drive signal generation unit 206, and a drive signal correction unit 230. The mask circuit 204 is provided corresponding to 48 piezo elements (not shown) for driving the nozzles n1 to n48 of the print head unit 60, respectively. In FIG. 5, the number in parentheses at the end of each signal name indicates the number of the nozzle to which the signal is supplied.
[0024]
The original drive signal generator 206 generates an original drive signal ODRV that is commonly used for the nozzles n1 to n48. This original drive signal ODRV is a signal including three pulses of a medium dot pulse W1, a small dot pulse W2, and a medium dot pulse W3 within a main scanning period for one pixel.
[0025]
The serial print signal PRT (i) input through the I / F dedicated circuit 50 is input to the mask circuit 204 together with the original drive signal ODRV output from the original drive signal generator 206 as shown in FIG. The mask circuit 204 is a gate for masking the original drive signal ODRV according to the level of the serial print signal PRT (i). That is, the mask circuit 204 passes the corresponding pulse of the original drive signal ODRV as it is and supplies it to the piezo element as the drive signal DRV for the time interval in which the serial print signal PRT (i) is at 1 level, while serial printing. For the time interval in which the signal PRT (i) is at 0 level, the corresponding pulse of the original drive signal ODRV is cut off.
[0026]
The drive signal correction unit 230 performs correction by shifting the timing of the drive signal waveform shaped by the mask circuit 204 back and forth in the entire return path. By correcting the timing of the drive signal waveform, the deviation of the ink droplet landing position in the forward path and the backward path is corrected.
[0027]
FIG. 6 is an explanatory diagram showing an original drive signal and a drive signal for one pixel section. FIG. 6A shows an original drive signal for one pixel section. At the time of printing, as shown in FIG. 6A, a medium dot pulse W1, a small dot pulse W2, and a medium dot pulse W3 are generated in this order as pulses of the original drive signal ODRV in each pixel section. The “pixel section” has the same meaning as the main scanning period for one pixel. As described above, the mask circuit 204 (see FIG. 5) passes the pulse of the original drive signal ODRV as it is when the serial print signal PRT (i) is 1 level, and when the serial print signal PRT (i) is 0 level. The pulse of the original drive signal ODRV is cut off.
[0028]
When generating a drive waveform for ejecting small ink droplets Ips for forming small dots Ds on the printing paper, as shown in FIG. 6B, pulses W1 on both sides of W2 of the original drive signal ODRV are generated. A drive waveform is formed by masking W3. Further, when generating a drive waveform for ejecting the medium ink droplet Ipm for forming the medium dot Dm on the printing paper, as shown in FIG. 6C, the drive signal after W1 of the original drive signal ODRV is generated. The drive waveform is formed by masking the pulses W2 and W3. Then, when forming the large dot Dl on the printing paper, the drive signal is formed by masking the pulse W2 as shown in FIG. 6 (d). Since the generation times of each pulse in one pixel section are different from each other, the landing position in one pixel differs along the moving direction of the head as shown on the right side of FIGS. 6 (b) to 6 (d). It becomes the position. Note that the squares on the right side of FIGS. 6B to 6D are pixels. In addition, the moving direction of the head is indicated by an arrow below the pixel. FIG. 6 illustrates the waveform of the drive signal in the main scanning forward path.
[0029]
In the main scanning return pass, the waveform of the drive signal for medium dots is different from the waveform shown in FIG. That is, in the return pass of the main scanning, the pulses W1 and W2 are masked and only W3 is left. In this way, medium dots are formed on the same side (left side in FIG. 6) in the pixel in both the forward and backward passes of main scanning.
[0030]
Note that the timing of generating the drive signal waveform in each main scan is shifted and corrected by the drive signal correction unit 230 (see FIG. 5) in the entire return path. By correcting this timing, the landing position of the ink droplet is intentionally shifted in the entire return path, and the deviation of the landing position of the ink droplet in the forward path and the return path is corrected. A method of determining a correction value that determines how much the timing is shifted will be described later.
[0031]
In the first embodiment, the printer 20 has a first print mode and a second print mode having different resolutions. In the first printing mode, for example, printing is performed at a dot recording density of 720 dpi using large dots Dl, medium dots Dm, and small dots Ds. On the other hand, in the second printing mode, for example, printing is performed at a dot recording density of 1440 dpi using only the medium dots Dm and the small dots Ds. Note that the ink droplets used in the respective printing modes are the medium ink droplet Ipm and the small ink droplet Ips. Further, in each printing mode, the formation position deviation is adjusted along the main scanning direction based on a unique adjustment value. Each adjustment value is determined based on a misregistration inspection pattern formed on the printing paper, as will be described later.
[0032]
B3. Occurrence of recording position deviation in the main scanning direction:
In the first embodiment, the recording position deviation during bidirectional printing is adjusted. Therefore, first, the occurrence of a recording position shift during bidirectional printing will be described. “Bidirectional printing” is a printing method that prints an image by forming dots on a print medium in both the forward and backward passes of main scanning while performing main scanning in both directions. On the other hand, a printing method in which dots are formed on the print medium only in one of the forward and backward passes of main scanning and an image is printed is referred to as “unidirectional printing”.
[0033]
FIG. 7 is an explanatory diagram showing misalignment during bidirectional printing. FIG. 7A is an explanatory diagram showing the dot landing position during forward printing, and FIG. 7B is an explanatory diagram showing the dot landing position during backward printing. The nozzle n moves horizontally in both directions above the printing paper P, and forms dots on the printing paper P by ejecting ink in the forward path and the backward path, respectively. It is assumed that ink is ejected vertically downward at an ejection speed Vk. The combined velocity vector CVk of each ink is a combination of the downward discharge velocity vector Vk and the main scanning velocity vector Vs of the nozzle n. Therefore, if the ink droplets are ejected when the printing paper P and the print head 28 (nozzle n) are in the same positional relationship in the forward and backward passes of the main scanning, the landing positions of the ink droplets on the print medium are shifted. End up. Therefore, the ejection timing of the ink droplets is adjusted in the forward and backward passes of the main scanning so that the landing positions of the ink droplets on the printing medium coincide.
[0034]
In FIG. 7, the dot formation position deviation is almost symmetrical with respect to the position of the nozzle during ink droplet ejection in the forward path and the backward path. However, there are elements such that the deviation is not symmetric between the forward path and the backward path, such as backlash of the driving mechanism in the main scanning direction and warping of the platen that supports the print medium below. In order to absorb the dot formation position shift caused by such elements, it is preferable to adjust the ejection timing of the ink droplets in the forward and backward passes of main scanning.
[0035]
B4. Adjustment value setting:
  FIG. 8 is a flowchart showing the entire processing in the first embodiment of the present invention. In step S2, a first misalignment inspection pattern is formed. Thereafter, in step S <b> 4, the user determines an adjustment value for the first print mode based on the first misalignment inspection pattern, and inputs the information to the printer 20. And stepS6Forms a second misregistration inspection pattern. Thereafter, in step S8, the user determines an adjustment value for the second print mode based on the second misregistration inspection pattern, and inputs the information to the printer 20. Hereinafter, each step will be described in detail. These adjustment values may be set by a user who actually uses the printer, or by an operator or a manufacturing apparatus in a factory that manufactures the printer for initial setting of the printer.
[0036]
FIG. 9 is a schematic diagram illustrating an example of the first misregistration inspection pattern T20. First, in steps S2 and S4, an adjustment value in the first print mode is determined. In step S <b> 2 (see FIG. 8), the first misalignment inspection pattern is printed using the printer 20. The printing of the first misalignment inspection pattern is performed in the first printing mode. That is, the dot recording density in the main scanning direction is 720 dpi, and the sub-scan feed is performed by a sub-scan feed pattern executed in the first printing mode. The first misregistration inspection pattern T20 is composed of a plurality of gray patches T21 to T25 that are printed using both forward and backward paths using light cyan, light magenta, and yellow nozzle arrays. Each gray patch reproduces the same color. These gray patches T21 to T25 are “adjustment value patterns” in the claims.
[0037]
In FIG. 9, each patch is drawn as a relatively large set of dots, but in actuality, it is formed with dots having a size that is not clearly visible to the eyes. In FIG. 9, dots of three sizes of large, medium, and small are described so as to be arranged vertically, but these are drawn so that the dot formation position deviation can be easily understood. It does not reflect the size or arrangement of dots. And the term “gray patch” does not mean that this patch always looks “gray” in the human eye. That is, other colors may appear depending on the misalignment of the dots.
[0038]
Each color dot constituting each patch is recorded at a fixed position in the main scanning direction for each patch in the forward path, but in the backward path, the position in the main scanning direction is sequentially shifted by 1/2880 inch for each patch. Recorded in position. Note that the dots of each color constituting each patch are shifted by a common shift amount in the return path. As a result, a plurality of gray patches T21 to T25 are printed on the printing paper P so that the relative positions of the dots formed in the forward path and the dots formed in the backward path are shifted by 1/2880 inches. The amount of shift between the forward and backward dots of each gray patch is the “adjustment candidate value” in the claims. On the left side of the gray patches T21 to T25, as shown in FIG. The deviation adjustment number has a function as correction information indicating a preferable correction state. Here, the “preferred correction state” refers to a state in which the roughness of the gray patch is minimized when the recording position (or recording timing) in the forward path or the backward path is corrected with an appropriate adjustment value. Therefore, a preferable correction state is realized by an appropriate adjustment value.
[0039]
In the example of FIG. 9, five gray patches T <b> 21 to T <b> 25 with the shift adjustment numbers 1 to 5 around the gray patch T <b> 23 with the number “3” attached are shown. In FIG. 9, the gray patch T <b> 24 with the shift adjustment number 4 indicates the most preferable correction state with the least roughness.
[0040]
Note that these gray patches T21 to T25 reproduce colors that are equal to each other, and can be composed of yellow Y, light cyan LC, and light magenta LM dots, for example. These gray patches T21 to T25 are formed based on the same pattern data D1 (see FIG. 1). The pattern data D1 that is the basis of the gray patches T21 to T25 is obtained by converting color image data representing a set of pixels having a uniform density into data representing the recording states of a plurality of ink color dots. The color image data includes medium dots Dm and small dots Ds at a ratio of 1: 3. This ratio is a dot mixture ratio in which, in the first print mode, the dot formation position shift is most likely to affect the image quality through many images. The pattern data D1 is stored in the hard disk 88a in the computer 88. The formation of these gray patches T21 to T25 is performed by the CPU 41 controlling each part of the inkjet printer 20. That is, the CPU 41 functions as an “adjustment value pattern forming unit” in the claims.
[0041]
FIG. 10 is an explanatory diagram showing a user interface screen when inputting adjustment values to the computer. In step S4 (see FIG. 8), the user observes the test pattern printed as shown in FIG. 9, and the gray having the least roughness among the gray patches T21 to T25 of the first misregistration inspection pattern T20. Select patch T24. Then, the deviation adjustment number is input to the user interface screen of the printer driver of the computer 88 (see FIG. 3). Input may be performed by operating the cursor CS as shown in FIG. 10 using a mouse, or may be performed by other methods such as through a keyboard. The input deviation adjustment number is stored in the PROM 43 (see FIG. 3) in the printer 20. The shift amount corresponding to the shift adjustment number stored in the PROM 43 is an “adjustment value” in the claims. An input device (keyboard, mouse, microphone, etc.) of the computer 88 corresponds to an “input unit” in the claims, and adjustment number storage areas 202a and 202b described later of the PROM 43 are “adjustment value storage units”. It corresponds to. The deviation adjustment number may be input through the operation panel 32 (see FIG. 3). In such an aspect, the operation panel 32 corresponds to an “input unit”.
[0042]
Next, in steps S6 and S8, an adjustment value in the second print mode is determined. In step S6, gray patches T31 to T35 are formed on the printing paper based on the pattern data D2. Printing is performed in the second print mode. That is, the dot recording density in the main scanning direction is 1440 dpi, and the sub-scan feed is performed by a sub-scan feed pattern executed in the second printing mode. Here, the unit amount for changing the dot shift amount between the gray patches T31 to T35 is 1/2880 inch, which is the same as that in step S2, but the change unit amount may be changed according to the print mode. .
[0043]
Similar to the pattern data D1, the pattern data D2 is obtained by converting color image data representing a set of pixels having a uniform density into data representing a recording state of a plurality of ink color dots. The color image data of the pattern data D2 includes medium dots Dm and small dots Ds at a ratio of 1: 2. This ratio is a dot mixture ratio in which the dot formation position shift most easily affects the image quality in many images in the second print mode. The pattern data D2 is also stored in the hard disk 88a in the computer 88. The pattern data D1 and D2 may be stored in the P-ROM 43 of the printer 20.
[0044]
In step S8, the user performs gray patches T31 to T35 (see FIG. 1) of the second misregistration inspection pattern T30 formed in the same manner as the first misregistration inspection pattern T20 (see FIGS. 9 and 1). Choose the gray patch with the least roughness. Then, the shift adjustment number is input to the computer 88. The deviation adjustment number is stored in the PROM 43 in the printer 20. After the misalignment adjustment numbers corresponding to the adjustment values of the first print mode and the second print mode are stored in the PROM 43, when the execution of printing is instructed by the user, the misalignment correction using the adjustment values is performed. Bidirectional printing is performed.
[0045]
Note that steps S2 to S8 are not necessarily performed continuously. Only steps S2 and S4 may be performed to reset only the adjustment values for the first print mode, or only steps S6 and S8 may be performed to reset only the adjustment values for the second print mode. Also good. Also, steps S6 and S8 are performed first to set the adjustment value for the second print mode first, and then steps S2 and S4 are performed to reset the adjustment value for the first print mode. May be.
[0046]
FIG. 11 is a block diagram showing a main configuration related to misalignment correction during bidirectional printing in the first embodiment. The PROM 43 in the printer 20 is provided with adjustment number storage areas 202a and 202b and an adjustment value table 206.
[0047]
In the adjustment number storage areas 202a and 202b, deviation adjustment numbers indicating preferable adjustment values in the first printing mode and the second printing mode are stored, respectively. The adjustment value table 206 is a table that stores the relationship between the deviation amount (that is, the adjustment value) of the dot recording position and the deviation adjustment number.
[0048]
In the first print mode, the shift adjustment number for the first print mode is extracted from the adjustment number storage area 202a, and the dot formation position deviation is adjusted with the corresponding adjustment value based on the adjustment value table 206. In the second print mode, the shift adjustment number for the second print mode is extracted from the adjustment number storage area 202b, and the dot formation position deviation is adjusted with the corresponding adjustment value based on the adjustment value table 206. Is called.
[0049]
An image printed in each print mode has a portion where the dot formation position shift is particularly conspicuous in a part of the image. The mixing ratio of dots in these portions is almost constant for many types of images. For example, in the first printing mode, the ratio is a mixed ratio in which the ratio of medium dots Dm and small dots Ds is 1: 3, and in the second printing mode, the ratio is medium dots Dm. This is a mixture ratio in which the ratio of small dots Ds is 1: 2. If the quality of the print result of the portion where the dot formation position shift is most conspicuous can be improved, the quality of the print result of the entire image is improved.
[0050]
In this embodiment, the adjustment value is determined so that the dot formation position deviation becomes inconspicuous at the dot mixture ratio where the dot formation position deviation is most noticeable in each printing mode. Therefore, the quality of the print result can be improved through many images in each print mode.
[0051]
In the first embodiment, a gray patch is printed using light cyan, light magenta, and yellow ink used for halftone printing, which is prone to roughening, and an adjustment value is determined. For this reason, roughness in the halftone can be reduced, and the image quality of the printed result can be effectively improved.
[0052]
Further, when printing the gray patches T21 to T25, the patch is printed by performing a feed substantially equal to the sub-scan feed performed during the actual color printing. Therefore, it is possible to determine an adjustment value that reduces the roughness of the printing result in actual color printing.
[0053]
As described above, since the adjustment value is set to an integral multiple of 1/2880 inch in the main scanning direction, this recording position (that is, recording timing) is also adjusted in units of 1/2880 inch in the main scanning direction. Is done. Here, the dots printed in the return pass are formed by shifting by 1/2880 inches, but the dots of each color constituting each of the patches T21 to T25, T31 to T35 (see FIGS. 9 and 1) are in finer units. If shifting is performed, the correction value can also be set by an integral multiple of the unit. In other words, the correction value can be determined within a more delicate range by finely setting the increment of the dot position to be printed in the return pass. The minimum value of this step is determined by printer control restrictions.
[0054]
In the first embodiment, printing is performed at 720 dpi using the large dots D1, medium dots Dm, and small dots Ds in the first print mode, and medium dots Dm and small dots are used in the second print mode. Printing was performed at 1440 dpi using only Ds. However, the print mode is not limited to this. That is, the printing mode of the printing apparatus may be a plurality of printing modes that can eject a plurality of types of ink droplets and have different usage ratios of the plurality of types of ink droplets. It should be noted that if the usage ratios of the respective ink droplets are different when the same image is printed, it corresponds to “a printing mode in which the usage ratios of a plurality of types of ink droplets are different”.
[0055]
C. Second embodiment:
The printing apparatus of the second embodiment has two types of original drive signals. In addition to the first printing mode and the second printing mode in the printing apparatus of the first embodiment, the printing apparatus has a third printing mode based on the original drive signal ODRV2. In the third print mode, as in the first and second print modes, a unique adjustment value is set based on the misregistration inspection pattern.
[0056]
FIG. 12 is an explanatory diagram showing other original drive signals and drive signals for one pixel section. FIG. 12A shows the original drive signal for one pixel section. At the time of printing, as shown in FIG. 12A, a small dot pulse W4, a medium dot pulse W5, and a large dot pulse W6 are generated in this order as pulses of the original drive signal ODRV2.
[0057]
When generating a drive waveform for ejecting the small ink droplet Ips2 in the third printing mode, as shown in FIG. 12B, the drive waveform is formed by masking the pulses on both sides of W5 of the original drive signal ODRV2. To do. Note that the portion W7 in FIG. 12B indicates that when the mask circuit is in a high impedance state, the piezoelectric element is maintained at a substantially constant voltage. The reason for this is that the piezo element functions as a capacitor. Further, when generating a drive waveform for ejecting the medium ink droplet Ipm2 in the third print mode, as shown in FIG. 12C, the drive waveform is formed by masking the pulses on both sides of W4 of the original drive signal ODRV2. Form. When generating a driving waveform for ejecting the large ink droplet Ipb2 in the third printing mode, as shown in FIG. 12D, the driving signal ODRV2 is formed by masking the pulse preceding W6. In the third printing mode, large, medium, and small dots are formed by large, medium, and small ink droplets, respectively. Since the discharge timing of each large, medium, and small ink droplet is early in the order of the medium ink droplet Ipm2, the small ink droplet Ips2, and the large ink droplet Ipb2, the landing position within one pixel is the right side of FIGS. 12 (b) to 12 (d). As shown in FIG. 3, the medium dots Dm2, the small dots Ds2, and the large dots D12 are arranged in this order from the rear to the front in the moving direction of the head. The same drive signal waveform corresponding to each dot is used in both the forward and backward passes of the main scanning. That is, the small ink droplet Ips2, the medium ink droplet Ipm2, and the large ink droplet Ipb2 ejected from one nozzle in one pixel section are ejected in the same order in the forward path and the backward path. In this way, the third printing mode for ejecting ink droplets from each nozzle differs from the first printing mode and the second printing mode in the combination of drive signals used for ejecting ink droplets. (See FIGS. 6B to 6D and FIGS. 12B to 12D).
[0058]
  FIG. 13 is a table showing the ratio of dots included in each of the pattern data D1, D2, and D3. In order to determine the adjustment value in the third printing mode, a patch similar to that shown in FIGS. 1 and 9 is printed based on the pattern data D3. The pattern data D3 has the large dots Dl2, the medium dots Dm2, and the small dots Ds2 in the third printing mode at a ratio of 1: 1: 2. Therefore, the ratio of the dots included in each of the pattern data D1, D2, and D3 is as shown in FIG. In FIG. 13, in order to make the distinction clear, the medium dot in the first and second print modes is represented by Dm1, and the small dot is represented by Ds1.In addition, if expressed including dots that are not used, the ratio of the dots included in the pattern data D1 is Dm1: Ds1: Dl2: Dm2: Ds2 = 1: 3: 0: 0: 0. The ratio of dots included in the pattern data D2 is Dm1: Ds1: Dl2: Dm2: Ds2 = 1: 2: 0: 0: 0. The ratio of dots included in the pattern data D3 is Dm1: Ds1: Dl2: Dm2: Ds2 = 0: 0: 1: 1: 1: 2.
[0059]
As described above, even in a printing apparatus having a plurality of printing modes in which combinations of drive signals used for ejecting a plurality of types of ink droplets are different from each other, the ratio of the types of dots constituting each is different Using the value pattern, it is possible to determine an adjustment value for adjusting the dot formation position deviation in the main scanning direction.
[0060]
D. Third embodiment:
FIG. 14 is a block diagram showing a main configuration related to deviation correction during printing in the third embodiment. The configuration of this block diagram is the same as the block diagram of FIG. 11 except for the configuration of the head drive circuit and the actuator chip. The printing apparatus shown in FIG. 14 is a printing apparatus that performs unidirectional printing. This printing apparatus has an independent head drive circuit 52c separate from other actuator chips for the actuator chip 93 that drives the light magenta and yellow nozzle rows. Therefore, the discharge timing of light magenta and yellow ink can be shifted with respect to the inks of other colors. Further, the printing apparatus of the second embodiment has independent head drive circuits 52a and 52b for the actuator chip 91 for driving the black and cyan nozzle rows and for the actuator chip 92 for driving the light cyan and magenta nozzle rows, respectively. have. The other points are the same as those of the printing apparatus of the first embodiment.
[0061]
Using such a printer, gray patches of uniform density are formed side by side as in FIGS. However, each patch is formed by unidirectional printing. Further, in those gray patches, light magenta and yellow dots are formed by being slightly shifted from other color dots. The amount of shift in each patch differs by 1/2880 inches. Then, the user looks at the print result, selects the patch with the least roughness, and inputs the adjustment number to the printer 20.
[0062]
When printing an image, the misregistration correction execution unit 210 (see FIG. 14) extracts the adjustment number from the adjustment number storage area 202a or 202b according to the print mode, and extracts the corresponding adjustment value from the adjustment value table 206. . Then, a signal for instructing the recording timing of the head based on the adjustment value is supplied to the head driving circuit 52c. On the other hand, a signal for correcting the dot formation position is not supplied to the head drive circuit for driving the other nozzle rows. As a result, the light magenta and yellow dot formation positions are adjusted with respect to the dots of other colors. With such an embodiment, it is possible to adjust the dot formation position deviation between nozzles in unidirectional printing.
[0063]
Although the ink droplet ejection timing is adjusted here for light magenta and yellow, the ink droplet ejection timing may be adjusted for other inks. In that case, when forming gray patches and flesh-colored patches, each patch is formed by gradually shifting the discharge timing for the ink for adjusting the discharge timing. In the embodiment shown in FIG. 14, each actuator chip drives two nozzle rows. However, if each nozzle row for ejecting ink of each color has its own actuator, the ink droplets are more finely divided. The discharge timing, that is, the dot formation position can be invited, which is more preferable.
[0064]
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.
[0065]
(1) In the embodiment, the gray patch was printed with light cyan, light magenta, and yellow ink, but the ink used is not limited to this combination. That is, when the chromatic color ink used in color printing is magenta, cyan, and yellow, the gray patch can be printed using the three colors of ink. Furthermore, when the chromatic color ink used in color printing is five colors of dark magenta, dark cyan, yellow, light magenta, and light cyan, it is not limited to three colors of yellow, light magenta, and light cyan, but other colors Patches may be printed using a combination of inks. That is, the color patch may be any combination of colors as long as it is formed using two or more single color nozzle groups. However, in the color tone called “halftone” such as gray and flesh color, since the dot formation position deviation tends to have a big effect on the quality of the printed result, it is possible to define adjustment values by forming patches with these colors preferable.
[0066]
Further, when determining an adjustment value for a certain printing mode, it is preferable that a patch is formed with other dots without using the largest dot used in the printing mode. In the print mode, the largest dot is often used when the print medium is filled with ink. When the print medium is filled with ink, the dot formation position shift is not noticeable. On the other hand, when the background color of the print medium is visible, for example, a dot formation position shift is easily noticeable in a halftone portion. Therefore, if the largest dot in the print mode is not used and a patch is formed with other dots and the adjustment value is determined, the adjustment that can improve the quality of the print result of the portion where the dot formation position shift is conspicuous A value can be defined.
[0067]
(2) Further, in the embodiment, the nozzle group for ejecting single color ink is a nozzle row composed of nozzles arranged in a row, but the arrangement of the nozzles is not limited to this. That is, any set of nozzles that eject single-color ink may be used.
[0068]
(3) In the first and second embodiments, the positional deviation is corrected by adjusting the recording position (or recording timing) of the return path. However, the positional deviation is corrected by adjusting the recording position of the forward path. You may make it do. In addition, the positional deviation may be corrected by adjusting both the forward and backward recording positions. That is, in general, it is only necessary to correct the positional deviation by adjusting at least one of the recording positions of the forward path and the backward path.
[0069]
(4) In each of the above embodiments, an ink jet printer has been described. However, the present invention is not limited to an ink jet printer, and is generally applicable to various printing apparatuses that perform printing using a print head. Further, the present invention is not limited to a method and apparatus for ejecting ink droplets, but can also be applied to a method and apparatus for recording dots by other means.
[0070]
(5) In each of the above embodiments, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced with hardware. May be. For example, some of the functions of the head drive circuits 52, 52a to 52c shown in FIGS. 11 and 14 can be realized by software.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of an embodiment.
FIG. 2 is a schematic configuration diagram of a printing system including the printer 20 of the first embodiment.
3 is a block diagram showing a configuration of a control circuit 40 in the printer 20. FIG.
FIG. 4 is an explanatory diagram showing a plurality of rows of nozzles provided in the print head.
FIG. 5 is a block diagram showing a configuration of a head driving circuit 52. FIG.
FIG. 6 is an explanatory diagram showing an original drive signal and a drive signal for one pixel section.
FIG. 7 is an explanatory diagram showing misalignment during bidirectional printing.
FIG. 8 is a flowchart showing the entire processing in the first embodiment of the present invention.
FIG. 9 is a schematic diagram showing an example of a first misregistration inspection pattern T20.
FIG. 10 is an explanatory diagram showing a user interface screen when inputting an adjustment value to a computer.
FIG. 11 is a block diagram showing a main configuration related to misalignment correction during bidirectional printing in the first embodiment.
FIG. 12 is an explanatory diagram showing another original drive signal and drive signal for one pixel section.
FIG. 13 is a table showing the ratio of dots included in each of pattern data D1, D2, and D3.
FIG. 14 is a block diagram showing a main configuration related to deviation correction at the time of printing in the third embodiment.
[Explanation of symbols]
20 ... Inkjet printer
22 ... Paper feed motor
24 ... Carriage motor
26 ... Platen
28 ... Print head
30 ... carriage
32 ... Control panel
34 ... Sliding shaft
36 ... Drive belt
38 ... pulley
39 ... Position sensor
40 ... Control circuit
41 ... CPU
43 ... PROM
44 ... RAM
50 ... I / F dedicated circuit
52, 52a to 52c... Head drive circuit
54 ... Motor drive circuit
56 ... Connector
60 ... print head unit
88 ... Computer
88a ... Hard disk
91 ... Actuator chip
92 ... Actuator chip
93 ... Actuator chip
202a, 202b ... Adjustment number storage area
204 ... Mask circuit
206 ... table
206: Original drive signal generator
210: Correction execution unit
230: Drive signal correction unit
CS ... Cursor
CVk ... Composite velocity vector
D1 Pattern data
D2 ... Pattern data
D3 ... Pattern data
DRV (i), DRV2 (i) ... drive signal
Dl, Dl2 ... large dots
Dm, Dm2 ... medium dots
Ds, Ds2 ... Small dots
Ipl2 ... Large ink droplets
Ipm, Ipm2 ... Medium ink drop
Ips, Ips2 ... small ink droplets
LC ... Light cyan nozzle row
LM ... Light magenta nozzle row
ODRV: Original drive signal
P: Printing paper
PRT: Serial printing signal
PS ... Print signal
ROM ... Programmable
T20 ... Pattern for inspection
T21 to T25 ... 1st gray patch
T30 ... Pattern for inspection
T31 to T35 ... second gray patch
Vk ... Discharge speed vector
Vs: main scanning speed vector
W1 ... Medium dot pulse
W2 ... Small dot pulse
W3 ... Medium dot pulse
W4 ... Small dot pulse
W5 ... Medium dot pulse
W6 ... Large dot pulse
Y ... Yellow nozzle row
n. n1-48 ... Nozzle

Claims (12)

It is a printing mode in which a plurality of types of ink droplets having different sizes can be ejected, and the same type of ink droplets among the plurality of types of ink droplets is used. In a printing apparatus having a plurality of printing modes having different printing modes, a main scanning direction when performing printing while performing bi-directional main scanning for moving at least one of a print head having a nozzle for ejecting ink droplets and a print medium A method for determining an adjustment value for reducing the dot formation position deviation of
(A) preparing pattern data for printing an adjustment value pattern according to each print mode according to each print mode;
(B) For each of the print modes, based on the pattern data corresponding to the print mode and a plurality of adjustment candidate values, a plurality of adjustment value patterns respectively corresponding to the adjustment candidate values are placed on a print medium. Forming, and
(C) based on a plurality of adjustment value patterns formed on the print medium, selecting the adjustment value from the plurality of adjustment candidate values,
The pattern data corresponding to each print mode includes two or more types of dots in which at least one of the adjustment value patterns of the pattern data corresponds to two or more types of ink droplets of the plurality of types of ink droplets. Data that is a pattern consisting of
In the pattern data corresponding to each print mode, the ratio of the types of the dots constituting each adjustment value pattern is:
Determined independently of the usage rate of the ink drops used in the corresponding printing mode;
Among the plurality of pattern data for the plurality of printing modes, the adjustment is performed so that the dot formation position deviation in the main scanning direction is most noticeable in the adjustment value pattern based on the pattern data corresponding to the printing mode. An adjustment value determination method in which value patterns are different from each other. In a printing apparatus having a plurality of print modes in which combinations of drive signals used to eject a plurality of types of ink droplets having different sizes from each other, a print head having a nozzle for ejecting ink droplets and a print medium A method of determining an adjustment value for reducing a dot formation position shift in the main scanning direction when performing printing while performing at least one main scanning in both directions.
(A) preparing pattern data for printing an adjustment value pattern according to each print mode according to each print mode;
(B) For each of the print modes, based on the pattern data corresponding to the print mode and a plurality of adjustment candidate values, a plurality of adjustment value patterns respectively corresponding to the adjustment candidate values are placed on a print medium. Forming, and
(C) based on a plurality of adjustment value patterns formed on the print medium, selecting the adjustment value from the plurality of adjustment candidate values,
Two or more types of dots corresponding to two or more types of ink droplets which are at least part of the plurality of types of ink droplets having different sizes, and each of the pattern data corresponding to each printing mode The ratio of the types of dots that make up the adjustment value pattern is
Determined independently of the usage rate of the ink drops used in the corresponding printing mode;
Among the plurality of pattern data for the plurality of printing modes, the adjustment is performed so that the dot formation position deviation in the main scanning direction is most noticeable in the adjustment value pattern based on the pattern data corresponding to the printing mode. An adjustment value determination method in which value patterns are different from each other. An adjustment value determination method according to claim 2,
The adjustment value determining method, wherein the plurality of print modes include two or more print modes having different dot recording densities. An adjustment value determination method according to claim 1 or 2,
The nozzles are arranged in the form of a plurality of nozzle rows extending in the direction intersecting the main scanning direction on the print head,
The step (b) includes an adjustment value determination method including a step of ejecting ink droplets from different nozzle arrays to form the respective adjustment value patterns on a print medium. An adjustment value determination method according to claim 1 or 2,
The step (b) includes an adjustment value determination method including a step of ejecting ink droplets in the forward and backward passes of the main scanning to form the respective adjustment value patterns on a print medium. An adjustment value determination method according to claim 1 or 2,
The adjustment value determination method, wherein the adjustment value pattern is a color patch having a uniform color. A printing apparatus having a plurality of printing modes in which the same type of ink droplets of a plurality of types of ink droplets having different sizes are used, wherein the usage ratio of the ink droplets to be used and the dot recording density are different from each other. And
A print head having nozzles capable of discharging a plurality of types of ink droplets having different sizes from each other;
A main scanning drive unit that performs main scanning in both directions to move at least one of the print head and the print medium;
A plurality of pattern data determined according to each print mode for printing an adjustment value pattern according to each print mode, wherein at least one of the adjustment value patterns according to the print mode is It is a pattern composed of two or more types of dots corresponding to two or more types of ink droplets among a plurality of types of ink droplets , and each adjustment value pattern is configured in the pattern data corresponding to each printing mode The dot type ratio is determined independently of the ink drop use ratio used in the corresponding print mode, and the print data is used in the plurality of pattern data for the plurality of print modes. in the adjustment value pattern by the pattern data corresponding to the mode, so the dot formation position misalignment in the main scanning direction is conspicuous most, A pattern data storage unit for storing the pattern data are different from each other in serial adjustment value between patterns,
An input unit for receiving external data input;
A control unit for controlling printing,
The controller is
Adjustment for forming a plurality of adjustment value patterns respectively corresponding to each adjustment candidate value on a print medium based on the pattern data corresponding to the print mode and a plurality of adjustment candidate values for each printing mode A value pattern forming unit;
An adjustment value storage unit that stores adjustment values that are determined from the plurality of adjustment candidate values based on a plurality of adjustment value patterns formed on the print medium and that are input from the input unit. apparatus. A printing apparatus having a plurality of print modes in which combinations of drive signals used for ejecting a plurality of types of ink droplets having different sizes are different from each other,
A print head having nozzles capable of discharging a plurality of types of ink droplets having different sizes based on a plurality of types of drive signals;
A main scanning drive unit that performs main scanning in both directions to move at least one of the print head and the print medium;
A pattern data storage unit that stores a plurality of pattern data determined according to each print mode in order to print an adjustment value pattern according to each print mode, wherein the pattern data includes the adjustment value pattern, In the pattern data corresponding to each printing mode, the pattern data is formed of two or more types of dots corresponding to two or more types of ink droplets that are at least part of the plurality of types of ink droplets having different sizes. The ratio of the types of dots constituting each adjustment value pattern is determined independently of the usage ratio of the ink droplets used in the corresponding printing mode, and the ratio of the plurality of pattern data for the plurality of printing modes is determined. in the middle, the main scanning direction of the dot formation position in the adjustment value pattern by the pattern data corresponding to the print mode Displacement so that the most prominent, a pattern data indicating that differ from each other in the adjustment value between patterns, a pattern data storage unit,
An input unit for receiving external data input;
A control unit for controlling printing,
The controller is
Adjustment for forming a plurality of adjustment value patterns respectively corresponding to each adjustment candidate value on a print medium based on the pattern data corresponding to the print mode and a plurality of adjustment candidate values for each printing mode A value pattern forming unit;
An adjustment value storage unit that stores adjustment values that are determined from the plurality of adjustment candidate values based on a plurality of adjustment value patterns formed on the print medium and that are input from the input unit. apparatus. The printing apparatus according to claim 8, wherein
The printing apparatus, wherein the plurality of printing modes include two or more printing modes having different dot recording densities. The printing apparatus according to claim 7 or 8, comprising:
The nozzles are arranged in the form of a plurality of nozzle rows extending in the direction intersecting the main scanning direction on the print head,
The adjustment value pattern forming unit discharges ink droplets from different nozzle arrays to form the adjustment value patterns on a print medium. The printing apparatus according to claim 7 or 8, comprising:
The adjustment value pattern forming unit discharges ink droplets in the forward and backward passes of the main scanning to form the adjustment value patterns on a print medium. The printing apparatus according to claim 7 or 8, comprising:
The printing apparatus, wherein the adjustment value pattern is a color patch having a uniform color.

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