JP2018094886A - Printer controller, printing control method, and medium recorded with printing control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain density even when a defective nozzle exists.SOLUTION: After specifying a first dot position becoming a discharge failure by a first defective nozzle in printing data, a specification section specifies a third dot position different from the first dot position based on priority information with the first dot position as a reference so as to cause ink droplets not to be discharged to the first dot position. Further, the specification section takes a second dot position where a position to be allocated becomes a discharge failure by a second defective nozzle into account, avoids it and specifies the third dot position. A data correction section corrects the printing data corresponding to allocation processing for allocating information of discharge of the ink droplets to the first dot position to the third dot position.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a print control apparatus, a print control method, and a medium on which a print control program is recorded, in which a print head having a large number of nozzles is moved relative to the print medium for printing.

Ink jet recording apparatuses are required to have a small nozzle diameter for the purpose of improving quick-drying and high definition. By reducing the diameter of the nozzle, the nozzle is likely to be clogged due to ink coagulation. When a nozzle is clogged and ink cannot be ejected, white streaks occur at positions corresponding to the nozzle.
In Patent Document 1, there is provided output data changing means for changing the output data of the output memory by taking the logical sum of the output data of the nozzle and the output data of any one of the nozzles adjacent to the nozzle. ing. As a result, even if the clogged dot is not attached due to nozzle clogging, the dot is attached to the adjacent position. That is, even when output data is lost due to a clogged defective nozzle (discharge failure), the output data of the missing portion is printed by the adjacent nozzle, so that the output data of the missing portion can be held.

Japanese Patent Laid-Open No. 9-118023

According to the conventional technique described above, when the output data of the defective nozzle is “1” and the output data of the adjacent nozzle that is not defective is “1”, the output data of the adjacent nozzle after taking the logical sum is “1”. No more. Therefore, the complementary effect on the output data of the defective nozzle is lost. Specifically, the expected concentration cannot be expressed.
In addition, there is still room for improvement in measures against nozzle omission in the ink jet recording apparatus using multi-size dots.

  Further, when there are a plurality of defective nozzles, the output data of the adjacent nozzle is set to “1” with the output data being “1” with the first defective nozzle as a reference. However, if the adjacent nozzles are also defective nozzles, even if a logical sum is taken, the adjacent nozzles that are originally defective nozzles do not eject ink, so nothing is output even if the output data of the adjacent nozzles becomes “1”. does not change. Therefore, the complementary effect on the output data of the defective nozzle is lost. Specifically, the expected concentration cannot be expressed.

  The present invention provides a print control apparatus, a print control method, and a medium on which a print control program is recorded, which can maintain density even when there are a plurality of defective nozzles.

  The present invention has at least a position information acquisition unit that acquires the positions of the first defective nozzle and the second defective nozzle among a plurality of nozzles that discharge ink to the medium, and a dot position that discharges ink droplets to the medium. A data generation unit that generates print data; and a first dot position that is printed on a medium by ejecting ink droplets when the first defective nozzle is not defective in the print data; When the defective nozzle is not defective, the second dot position to be printed on the medium by ejecting ink droplets is specified, and the priority order is determined in a predetermined area for each pixel with reference to the first dot position. Based on the set priority information, a specifying unit that specifies a third dot position different from the first dot position and the second dot position, and ejection of ink droplets to the first dot position Information It is constituted comprising a data correction unit for the correction of the print data corresponding to the allocation process to allocate the third dot position.

  In the above configuration, the position information acquisition unit acquires the positions of the first defective nozzle and the second defective nozzle among the plurality of nozzles that eject ink onto the medium. The data generation unit generates print data having at least dot positions for ejecting ink droplets onto the medium. The specifying unit specifies a first dot position to be printed on the medium by ejecting an ink droplet when the first defective nozzle is not defective in the print data, and the second defective nozzle is not defective. Priority information in which a second dot position printed on a medium by ejecting ink droplets is specified, and a priority order is set in a predetermined area in units of pixels with the first dot position as a reference Based on the above, a third dot position different from the first dot position and the second dot position is specified. Then, the data correction unit corrects the print data corresponding to the allocation process for assigning the information on the ejection of ink droplets to the first dot position to the third dot position.

  That is, when the first dot position that causes ejection failure with the first defective nozzle is specified, priority information based on the first dot position is used so that ink droplets are not ejected to the first dot position. Based on the above, a third dot position different from the first dot position is specified. Further, the third dot position is specified by taking into consideration the second dot position at which the assigned position is an ejection failure at the second defective nozzle, and avoiding this.

  According to the present invention, when there are a plurality of defective nozzles, a print control apparatus, a print control method, and a print control program capable of ejecting ink droplets to be ejected by the defective nozzles at positions where they can be reliably ejected. Can be provided.

1 is a block diagram of a printing system to which the present invention is applied. It is a block diagram of a serial printer. It is a figure which shows the flow of print data. It is a figure which shows nozzle row decomposition | disassembly and path | pass decomposition | disassembly. It is a figure which shows the priority in specification of the position to allocate. It is a figure which shows the process of the allocation process using a specific example. It is a figure which shows the process of the allocation process with respect to the next missing pixel. It is a flowchart when reflecting in the program which a computer runs. It is a figure which shows the odd-numbered priority information and the even-numbered priority information. It is a figure which shows correction of the priority information in the case of falling into another defective nozzle. It is a flowchart when reflecting in the program which a computer runs. It is a flowchart when reflecting in the program which a computer runs. It is a figure which shows operation which avoids the missing pixel of another defective nozzle.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a printing system to which the present invention is applied.
In the figure, a print head 11 of a printer (droplet discharge device) 10 discharges four or six color inks supplied from an ink tank from nozzles. The print heads 11a to 11d are fixed at predetermined positions, and the platen 12 is rotationally driven by the platen motor 13 so that the paper is conveyed across the print heads 11a to 11d. The print heads 11a to 11d are zigzag arranged in a zigzag pattern in the longitudinal direction, and the nozzles face the paper over the entire width in the paper width direction. Accordingly, it can be said that the print heads 11a to 11d move relatively on the paper.

The feed motor 14 drives a paper feed roller 15 that supplies paper stored in a predetermined paper stacker. The type of printer in which the print heads 11a to 11d are stationary and move relatively in accordance with the conveyance of the paper is called a line printer.
The control circuit 20 is configured by combining dedicated ICs and functionally includes a CPU, a ROM, and a RAM. The control circuit 20 controls driving of the print heads 11a to 11d, the platen motor 13, and the feed motor 14. An operation panel / display unit 16 is attached to the control circuit 20, and a predetermined operation by a user is received on the operation panel / display unit 16 and a predetermined display is performed. The hardware is generically called a printing mechanism.

When the printer 10 is connected to the network 30 and acquires print data from the PC 40 or the like via the network 30, the printer 10 executes printing corresponding to the print data.
In the case of a line printer, if one of the nozzles is clogged and no longer ejects ink droplets, and the paper is transported and printed, ink droplets will not adhere to the dot positions facing the clogged nozzles. It appears as white streaks. Note that whether each nozzle is a clogged defective nozzle can be determined using a confirmation chart, and can be determined by supplying a predetermined drive signal to the drive element of each nozzle. it can.

The number of defective nozzles is not limited to one, and there may be a plurality of defective nozzles. Accordingly, white stripes are generated by the number of defective nozzle rows. However, when they are adjacent to each other, the appearance is one. In the case of a line printer, white streaks occur in parallel with the paper transport direction. The direction in which the white stripes are aligned is the same as the direction in which the nozzles are aligned.
Such white streaks occur not only in line printers but also in serial printers.

FIG. 2 is a schematic block diagram of this serial printer.
The print head 17 in which the nozzles are oriented in the paper feeding direction is reciprocated within a predetermined range by a belt 19 driven by a carriage motor 18. The type of printer in which the print head 17 reciprocates in accordance with the conveyance of the paper is called a serial printer here, although there are various ways of calling it.
In the case of a serial printer, when a nozzle is clogged, white streaks may occur in the width direction of the paper on which the print head 17 is driven.

  The control circuit 20 outputs a drive signal for ejecting ink droplets by the print heads 11 and 17, and ejects a plurality of ink droplets having different sizes such as small dots, medium dots, and large dots. Several methods for discharging such multi-size dots have been realized, but in the present invention, there are no particular limitations on the method for realizing them. On the other hand, small dots, medium dots, and large dots are selected based on print data that represents the amount of ink. Regardless of expressions such as ink amount, density, or dot diameter, they are based on quantitative control similar to density. The size of the ink droplet is ejected.

  In the case of a serial printer, it is possible to make the dot pitch finer than the nozzle pitch by paper feeding in addition to printing in which the actual nozzle pitch and dot pitch match. In the former case, the nozzle position of the defective nozzle corresponds to the dot position as it is. In other words, the nozzle that ejects ink droplets to the dot position adjacent to the dot position corresponding to the defective nozzle is actually a nozzle adjacent to the defective nozzle.

  However, when the dot pitch is made finer than the nozzle pitch, that is, when all the printing area is covered by multiple passes, ink droplets are ejected to the dot position adjacent to the dot position of the defective nozzle in consideration of the print pass. The nozzle to be used must be determined. Specifically, the dot position of the defective nozzle is obtained based on the print data, the contents of the pass decomposition, and the information of the defective nozzle, and the nozzle corresponding to the dot position near the same dot position is specified. .

FIG. 3 is a diagram showing the flow of print data.
When selecting a printing process from an application, many applications output RGB multivalued data. This RGB multi-value print data is input to the OS and printer driver. In some cases, the printer 10 may receive a print instruction from a tablet, a smart phone, or the like. In this case, there is no OS or printer driver, and the printer 10 may directly input RGB multi-value data.

  In any case, RGB multi-value data is first converted into CMYK (cyan, magenta, yellow, black) multi-value data corresponding to each of the dot pitch and ink color through resolution conversion / color conversion processing CC. The In the case of six-color ink that employs dark and light colors for cyan and magenta, multi-value data of Cl and Ml (light cyan, light magenta) is also added. In the case of multi-value data, it represents 8-bit 256 gradation or 10-bit 1012 gradation depending on the number of bits of the allocated data. In the case of the multi-dot size, the ink droplets are not binary, but are multi-values of two or more gradations, but are usually not called multi-value data, and are only in the halftone category.

The CMYK multilevel data is converted into CMYK binary data through the halftone process HT. Since it is a multi-dot size, it is actually 2-bit, 4-gradation data. It is sufficiently small compared with the process gradation value such as 256 gradations, and as a result, it represents on / off of ink droplets of each size, and is also referred to as binary data for convenience.
This CMYK binary data includes dot positions that are dot positions when ink droplets are printed on a print medium, and the amount of ink ejected to the dot positions. That is, the CMYK binary data corresponds to print data in which the dot position and the amount of ink ejected at the dot position are associated with each other. It can also be said that it has at least dot positions for ejecting ink droplets onto the medium. Therefore, the process of generating CMYK binary data based on RGB multi-value data corresponds to the data generation unit. In this example, since the application generates RGB multi-value data, the above-described process is performed. However, the data generation unit includes various variations, such as the application may generate CMYK multi-value data. . In this case, conversion processing from CMYK multi-value data to CMYK binary data is applicable. Further, if the CMYK binary data is supplied directly via the network, the process of inputting the CMYK binary data corresponds to the data generation unit.

FIG. 4 is a diagram illustrating nozzle row decomposition and pass decomposition shown in FIG.
When the CMYK binary data is obtained, it is decomposed into data corresponding to the nozzle rows along the direction in which white stripes are generated. As described above, the line printer generates white streaks in the paper transport direction. Depending on the data generated by the printer driver, if the CMYK binary data is raster data in the paper width direction, the print data supplied to each nozzle is orthogonal because it is in the paper feed direction. At this time, the process of specifying print data to be supplied for each nozzle is called nozzle array decomposition. By dividing the nozzle row, the actually adjacent dot positions correspond to the print data corresponding to each dot position. Of course, if the printer driver generates print data along the paper feed direction, the nozzle array is disassembled if the print data is cut out based on the position of the nozzles. The print data corresponding to the nozzle numbers 1, 2, 3,... Are print data of a, i, c,.

On the other hand, in the serial printer, if the CMYK binary data is raster data in the paper width direction, it matches the arrangement direction of the print data supplied to each nozzle. Therefore, if the print data A, A, C,... Are simply cut out based on the nozzle numbers 1, 2, 3,.
In the case of a serial printer, if the nozzle pitch matches the dot pitch, all the dot positions in the print area can be printed in one pass, but the nozzle pitch does not match the dot pitch. Thus, all the dot positions in the print area can be printed in a plurality of passes. When printing in multiple passes, print data corresponding to the nozzles for printing in each pass is extracted from the raster data, and print data for each pass is generated. This process is called path decomposition.

  In the figure, the paper feed width for each pass is 5 dots. In this case, with respect to the nozzle numbers 1, 2, 3, 4 and 5, the raster data is the nozzle number of the first pass in the first row, the nozzle number 4 of the second pass in the first row, and 1 in the third row. The nozzle number 2 for the second pass, the nozzle number 5 for the second pass is the nozzle number 5 for the second pass, and the nozzle number 3 for the first pass is the fifth line. This process corresponds to path decomposition.

In the case of printing in a plurality of passes, the physical nozzle adjacency situation and the dot position adjacency situation when ink droplets are ejected can be specified in consideration of this pass decomposition. In other words, the ink droplets ejected from the nozzle adjacent to the defective nozzle are usually not necessarily adjacent to the dot position to which the ink droplet is attached when the defective nozzle is normal, and adjacent to the defective nozzle. The ink droplets ejected from the nozzles that have not been arranged are adjacent to the dot positions to which the ink droplets are attached when the defective nozzle is normal.
Nozzle array decomposition performs a process of specifying print data that will actually be adjacent to each other regardless of whether it is a single pass or multiple passes. For example, adjacent to the dot positions ejected by nozzle number 2 are the dot positions ejected by nozzle number 4 and nozzle number 5.

  Next, if there is a defective nozzle, the nozzle is identified and the following allocation process is executed. A technique is known in which a defective nozzle is specified by supplying a signal for inspection to a driving element of each nozzle, for example, a piezo element. Alternatively, print data for printing a predetermined print pattern may be generated and printed, the print result may be checked to identify that a specific nozzle is clogged, and the nozzle number may be input. For the input, the operation panel / display unit 16 may be used, or data may be input via a PC or the like and input via a USB memory or the like. It is also possible to read the print result with a scanner, identify clogged nozzles, generate data, and input this data. Each of these methods corresponds to a position information acquisition unit that acquires the position of a defective nozzle (of defective ejection) among a plurality of nozzles that eject ink onto a medium.

The position of the defective nozzle acquired by the position information acquisition unit is not limited to one.
This allocation process includes two elements, i.e., specifying the position to be allocated and calculating the amount of ink to be allocated.

First, an assignment process in the case where one defective nozzle or a plurality of defective nozzles exist but they are sufficiently separated will be described.
FIG. 5 shows the priorities in specifying the positions to be assigned, where (a) is for odd-numbered pixels and (b) is for even-numbered pixels. The odd and even numbers are the order of the dot positions from the print start position.
In this example, a priority is set for a range (area) of 2 × 5 pixels. If the position of the dot row discharged from the defective nozzle is the third row, the dots in the third row are missing. This is called a missing pixel. The ink amount of the missing dot due to the missing pixel in the left column of the third row is sequentially assigned to the neighboring dot positions based on the priority. Assigning to a neighboring dot position means increasing the amount of ink of print data supplied to the nozzle while specifying an actual nozzle that attaches an ink droplet to that dot position. Different priorities are assigned for the following reasons. Since each dot position has an upper limit on the ink amount, even if the ink amount is increased to neighboring dot positions, it cannot be divided beyond the upper limit. For this reason, when the dot position with high priority cannot cover the premium, the dot position with low priority is sequentially identified, and the ink amount that can be increased at the dot position is increased. In this process, the two elements of specifying the position to be allocated and calculating the ink amount to be allocated are executed.

In this embodiment, a 2 × 5 pixel range is set, and the allocation process is performed in this range (area). The range (area) of 2 × 5 pixels is merely an example, and can be changed in consideration of the influence such as the size and density of ink droplets and the ease of infiltration of a medium. In general terms, it can be said that the allocation process is performed in a range of n × m pixels in which ink droplets are attached as dots.
Here, n is an integer of 5 or more and is the number of pixels in the direction intersecting the nozzle row direction in the print data, and m is a natural number and the number of pixels in the nozzle row direction in the print data.

  In this embodiment, 2 is set as m. It is also possible to change in consideration of the influence such as the size and density of the ink droplet and the ease of soaking of the medium. As an example, m is preferably about 2 as a range in which the amount of ink can be allocated to prevent the change in density from being felt.

In the example shown in FIG. 5A, with reference to the pixel in the third row and the left column,
First priority pixel: one pixel above,
Second priority pixel: pixel below one pixel,
3rd priority pixel: right pixel above 1 pixel,
4th priority pixel: right pixel below 1 pixel,
5th priority pixel: pixel above 2 pixels,
Sixth priority pixel: pixel two pixels below,
Seventh priority pixel: right pixel above two pixels,
Eighth priority pixel: This is the right pixel two pixels below. In general, with the pixel in the left column of the third row as a reference, the priority is lowered while alternately allocating up and down.
The priority information is such that the priority of each pixel becomes higher in the order closer to the missing pixel (first position).

  As described above, when a defective nozzle is specified, first, print data corresponding to this nozzle is assigned to the center row (third row) of 2 × 5 pixels. The dot position ejected from the defective nozzle is the left column in the third row, and this pixel position is taken as the first dot position. In other words, when the defective nozzle is not defective (normal), the position where the ink droplet is ejected and printed on the medium is the first dot position.

  If priority information is applied to each defective nozzle and the allocation process is performed, even if priority information is applied in a range of n × 2 pixels with a certain missing pixel as a reference, another defective nozzle is included in this range. If it exists, it will not be assigned. When priority information is applied based on the first dot position of the first defective nozzle, a missing pixel due to another defective nozzle that falls within this range is referred to as a second dot position. The destination dot position to be assigned is called a third dot position.

Next, a third dot position different from the first dot position is identified based on the priority information shown in FIG. This priority is set for each pixel. In this way, the third dot position based on the priority is specified based on the position of the missing dot, and this process corresponds to the specifying unit.
The priority in (a) and the priority in (b) are set so that the top and bottom are reversed. As a result, the dot position with the priority of 1 is positioned above in the odd-numbered position and positioned below in the even-numbered position. If this is not done, the missing dot ink amount will always be assigned to the upper position with respect to the missing pixel, but if the odd number and even number are reversed, they will be assigned in order up and down. A tendency arises and unnaturalness can be eliminated.

FIG. 6 shows the process of allocation processing using a specific example.
FIG. 4A shows the original data. This is print data that has been divided into nozzle rows, and is print data that is supplied to each nozzle that discharges dots applied to the medium. If the nozzle arrangement matches the dot position on the medium, it matches the print data for the actual nozzle row.
Since the nozzle corresponds to the multi-dot size, 0 = no dot, 1 = small dot, 2 = medium dot, 3 = large dot. Hereinafter, for each dot position, the right direction is the x direction, the lower direction is the y direction, and the pixels are specified by (x, y) coordinates with the upper left pixel as a reference. The upper left pixel position is (1, 1), and the lower right pixel is (7, 5).

  If the middle row (y = 3) is a row corresponding to a defective nozzle, (1,3)-(7,3) is missing and becomes a pixel. Although the first missing pixel is (1, 3) and the original data is “3”, the print data is equal to “0” because an ink droplet cannot be ejected because it is a clogged defective nozzle. . That is, the density corresponding to the difference between 3 and 0 is insufficient.

The ink amount may not only indicate a pure volume but also a stepwise guide value such as large, medium, and small. In the following, it is assumed that the dot values (0 to 3) used in the print data are treated equally as indicating the ink amount.
Since the x-coordinate value is 1, it is an odd number, and referring to the priority information in FIG. 5A, the priority is high (in the figure, 1 is the highest priority and 8 is the highest priority). (Low) is the pixel (1, 2). That is, when the pixel of the missing pixel (1, 3) is set as the first dot position, the pixel of (1, 2) is specified as the third dot position based on the priority information.

Originally, we would like to allocate the insufficient ink amount “3”, but the original data of the pixels (1, 2) is “1” and the maximum value is “3”.
In the ink amount calculation process, the following steps 1 to 6 are executed.
Step 1: Acquisition of ink amount at the first dot position (currently insufficient ink amount)
Step 2: Acquisition of the ink amount at the third dot position Step 3: Add the ink amount at the first dot position and the ink amount at the third dot position (added value)
Step 4: The sum of the added value and “3”, whichever is smaller, is used as the ink amount at the third dot position after addition. Step 5: The ink amount at the third dot position after addition is subtracted from the added value. Step 6: Set the ink amount at the first dot position to “0” By the above process, the process corresponds to the process of assigning the ink amount at the first dot position to the third dot position. Of course, this is realized by a technique called correction of print data. Executing this processing corresponds to a data correction unit.

When the above processing is specifically executed on the original data, it is as follows. The adjacent pixel refers to a pixel having the next highest priority based on priority information.
A: Dot value of missing pixel (first dot position) = 3
B: Dot value (before addition) of adjacent pixel (third dot position) = 1
B ′: dot value (after addition) of an adjacent pixel (third dot position) = (Min (3, A + B) = 3
C: remainder dot value = (A + B) −B ′ = 1
In this way, the ink amount at the third dot position is increased from “1” to “3”, and “1” that does not compensate for the shortage amount is the remaining dot value.
The dot value at the first dot position is set to “0” in step 6. This is because, if the defective nozzle detection itself is incorrect, if the original data remains, the defective nozzle is ejected from the nozzle considered as a defective nozzle, and the ink amount is doubled. Normally, it may be “0”, but a value that substantially does not attach ink droplets is also included. In this way, the data correction unit sets the amount of ink at the first dot position as the amount of ink that does not attach ink droplets.

FIG. 6B shows the result of the above allocation process.
The fact that the remaining dot value is a positive value means that the ink amount at the first dot position cannot be covered by the third dot position alone, and therefore the density is insufficient. Therefore, the fourth dot position having the next highest priority is specified based on the priority information shown in FIG. Then, it can be seen that the pixel (1, 4) is the fourth dot position.
It should be noted that the fourth dot position with respect to the third dot position has a relationship of the dot position of the subsequent order with respect to the dot position of the previous order. Hereinafter, the fifth dot position with respect to the fourth dot position is referred to as the subsequent or next order dot position with respect to the preceding dot position.

  This process corresponds to the specifying unit specifying a subsequent dot position (fourth dot position) different from the previous dot position (third dot position) based on the priority information. After specifying, the data correction unit assigns an ink amount that cannot be allocated to the preceding dot positions (an ink amount that cannot be allocated by assigning the first ink amount at the first dot position to the third dot position). Then, the corresponding print data is corrected so that the process is assigned to the dot position (fourth dot position) in the subsequent order.

The assignment of the ink amount to the fourth dot position is substantially the same as the assignment of the ink amount from the first dot position to the third dot position. That is,
Step 7: Acquisition of the last remaining area (currently insufficient ink amount)
Step 8: Obtain the ink amount of the next priority dot position (ex. Fourth dot position) based on the previous dot position Step 9: The next priority dot position based on the previous dot position ( ex.Adding the ink amount at the fourth dot position and the ink amount at the fourth dot position) (added value)
Step 10: The sum of the added value and “3”, whichever is smaller, is set as the ink amount of the next priority dot position (ex. Fourth dot position) after the addition. The ink amount at the priority dot position (ex. 4th dot position) is subtracted, and if it is positive, it is carried over as a remainder value. The above processing is performed on the original data after the previous correction (FIG. 6B). When executed, it will be as follows.

C: Last remainder dot value = 1
B: Dot value (before addition) of adjacent pixel (fourth dot position) = 3
B ′: dot value (after addition) of the adjacent pixel (fourth dot position) = (Min (3, C + B) = 3
C: the remainder dot value of this time = (C + B) −B ′ = 1
FIG. 6C shows the result of the above allocation process.
Although the fourth dot position is specified, the print data already has the maximum ink amount and cannot accept the shortage amount, so the dot value does not decrease too much.
This process is repeated until there are no more dot values or the pixel has the lowest priority.

When the above processing is specifically executed on the original data after the previous correction (FIG. 6C), the following processing is performed.
C: Last remainder dot value = 1
B: Dot value of adjacent pixel (fifth dot position) (before addition) = 3
B ′: dot value (after addition) of an adjacent pixel (fifth dot position) = (Min (3, C + B) = 3
C: the remainder dot value of this time = (C + B) −B ′ = 1

FIG. 6D shows the result of the above allocation process.
Since there is a surplus dot value, it is as follows when it is specifically executed on the original data after correction (FIG. 6D).
C: Last remainder dot value = 1
B: Dot value of adjacent pixel (sixth dot position) (before addition) = 2
B ′: Dot value (after addition) of the adjacent pixel (sixth dot position) = (Min (3, C + B) = 3
C: Current remainder dot value = (C + B) −B ′ = 0

FIG. 6E shows the result of the above allocation processing.
Since there are no more dot values, no further processing is performed. Since there are 8 pixels to be allocated, the process can be repeated up to 8 times.
When the number of times exceeds eight, the process of allocating beyond the initially set range of 5 × 2 pixels is performed. However, in this embodiment, even if a surplus dot value occurs, the process of allocating beyond the 5 × 2 pixel range is not performed. This is done in consideration of shortening the processing time by limiting the number of repetitions and the actual degree of effect.

FIG. 7 shows the process of allocation processing for the next missing pixel (2, 3).
Referring to FIG. 7A, since the x coordinate value is 2, it is an even number, and referring to the priority information in FIG. 5B, the pixel with the highest priority is the pixel (2, 4). It is. That is, when the missing pixel (2, 3) pixel is the first dot position, the (2, 4) pixel is specified as the third dot position based on the priority information.

We want to allocate the insufficient ink amount “2”, but since the original data of the pixel (2, 4) is “3”, there is no ink amount that can be allocated to this pixel. When the processing of step 1 to step 6 is performed, the following occurs.
A: Dot value of missing pixel (first dot position) = 2
B: Dot value of adjacent pixel (third dot position) (before addition) = 3
B ′: dot value (after addition) of an adjacent pixel (third dot position) = (Min (3, A + B) = 3
C: remainder dot value = (A + B) −B ′ = 2
In the first original data, the ink amount at the third dot position is “2”. However, as a result of the allocation process of the ink amount of the first missing pixel, the original amount at the time when the processing of the next missing pixel is started. The data has been corrected. Specifically, the ink amounts of the pixels (2, 2) and (2, 4) are increased from “2” to “3”, and the insufficient ink amount cannot be assigned to these pixels.

As shown in FIG. 7B, the same applies to the pixel of (2, 2) whose priority is “2”.
Then, when the dot value becomes 2 in the pixel of (3, 4) with the priority “3”, Step 7 to Step 11 are executed, and the shortage ink amount can be covered for the first time. At this time,
C: Last remainder dot value = 2
B: Dot value of adjacent pixel (fourth dot position) (before addition) = 2
B ′: dot value (after addition) of the adjacent pixel (fourth dot position) = (Min (3, C + B) = 3
C: the remainder dot value of this time = (C + B) −B ′ = 1
It becomes. The result is shown in FIG.

Further, since the pixel of (3, 2) with the priority “4” also has a dot value of 2, it is possible to cover the insufficient ink amount by executing Steps 7 to 11. At this time,
C: Last remainder dot value = 1
B: Dot value of adjacent pixel (fifth dot position) (before addition) = 2
B ′: dot value (after addition) of an adjacent pixel (fifth dot position) = (Min (3, C + B) = 3
C: Current remainder dot value = (C + B) −B ′ = 0
It becomes. The result is shown in FIG.
When the remainder dot value becomes 0, the allocation process is finished.

FIG. 8 shows a flowchart when the above allocation processing is reflected in a program executed by the computer. However, the following allocation processing includes processing corresponding to a plurality of defective nozzles. It also appears in the data flow of FIG.
First, in step S100, information on defective nozzles is acquired. The number of defective nozzles is not limited to one, and if there is a plurality of information, it is stored in a predetermined storage area. For convenience of processing, it is assumed that defective nozzles are numbered in the order of nozzle rows from one end.

  In step S105, “1” is set to the variable i in order to specify a plurality of defective nozzles. In step S110, it is determined whether there is an i-th defective nozzle. If there is no i-th defective nozzle, the following processing is not performed and the processing is terminated. If there is only one defective nozzle, the following processing is repeated once, and if there are two defective nozzles, the following processing is repeated twice.

  The first dot position is determined based on the i-th defective nozzle. If it is an odd number, the odd-numbered priority information is acquired through steps S115 and S120, and if it is an even-numbered, the even-numbered priority information is acquired through steps S115 and S125. It is possible to apply a calculation method that minimizes the bias between the odd number and the even number. As an example, column numbers can be employed as described above. However, when there are a plurality of defective nozzles, they are the same. In order to avoid this, the i-th information is referred to, and even if it is an odd-numbered column, if i of the defective nozzle is an even number, A thing different from the column number may be referred to. FIG. 10 described later is applied by this method.

In step S130, it is determined whether there is another defective nozzle. The determination as to whether it corresponds to another defective nozzle is made based on the following requirements.
First, it is determined whether there are other defective nozzles before and after the i-th reference.
Also, it is determined whether or not the defective nozzle is included in the priority information range in which the missing pixel due to the i-th defective nozzle is applied as the first dot position.

FIG. 9 shows the odd-numbered priority information and the even-numbered priority information used in the following description, and is in the range of nx1 pixels for the convenience of understanding.
FIG. 10 is a diagram illustrating correction of the priority information when it corresponds to another defective nozzle.

FIG. 10A shows a case where two defective nozzles are adjacent (5th row and 6th row). If two defective nozzles are adjacent,
“When there is a first defective nozzle (fifth row), there is a second defective nozzle (sixth row) before and after that”, “second defective nozzle (sixth row) Eye) is included in the priority information range (5 × 1 pixel range) in which the missing pixel from the first defective nozzle (fifth row) is applied as the first dot position ”.
Accordingly, in step S135, the priority information is corrected so as to avoid missing pixels. Specifically, the priority information for the first defective nozzle (fifth row) is acquired, and the missing pixel row (sixth row) by the second defective nozzle (sixth row) corresponds to the pixel. (4th row from the top in the range of 5 × 1 pixels), and the pixel range is expanded in a direction away from the missing pixel by skipping the same pixel. In this example, the sixth line of priority information is skipped, the sixth line is moved to the seventh line, and the seventh line is moved to the eighth line. Excluding missing pixels, the pixel ranges to which the priority information is applied are the third and fourth rows and the seventh and eighth rows.

That is,
-Specify the pixel range of the pixel of the missing pixel (first dot position) priority information by the first defective nozzle,
-Specify whether the pixel of the missing pixel (second dot position) by the second defective nozzle is included in the pixel range of the priority information,
The same pixel (second dot position) is skipped, and the pixel range of the priority information is extended in a direction away from the missing pixel (first dot position) of the first defective nozzle.
Thus, based on the second dot position, the priority information area is expanded and corrected so as not to overlap with the second dot position.

  In this example, the direction away from the missing pixel is downward, but when the defective nozzle in the sixth row (which becomes the first defective nozzle) is used as a reference, the other nozzles are in the fifth row. This becomes a defective nozzle (this is the second defective nozzle), and the pixel range of the priority information is expanded in a direction away from the missing pixel by skipping the pixels in the fifth row. Then, since the second row from the top in the 5 × 1 pixel range of the priority information becomes the fifth row, the fifth row is skipped and the fifth row of the priority information is moved to the fourth row. The fourth line is moved to the third line.

In FIG. 10A, two pieces of priority information are displayed in the first column. The left one is priority information applied to the defective nozzle in the fifth row, and the right one is priority information applied to the defective nozzle in the sixth row. The priority information, both of which are in the range of 5 × 1 pixels, is extended outward so as to skip missing pixels.
Next, in FIG. 10B, the first defective nozzle is in the fifth row, and the second defective nozzle is in the seventh row. In this case, specifically, priority information for the first defective nozzle (fifth row) is acquired, and a missing pixel row (seventh row) by the second defective nozzle (seventh row) is obtained. The corresponding pixel is specified (in the 5 × 1 pixel range, the fifth row from the top), and the pixel range is expanded in a direction away from the missing pixel by skipping the pixel. In this example, the seventh line of priority information is skipped and the seventh line is moved to the eighth line. Excluding missing pixels, the pixel ranges to which the priority information is applied are the third and fourth rows and the sixth and eighth rows.

  When the defective nozzle in the seventh row is the first defective nozzle, the second defective nozzle is in the fifth row. In this case, specifically, priority information for the first defective nozzle (seventh row) is acquired, and a missing pixel row (fifth row) by the second defective nozzle (fifth row) is obtained. The corresponding pixel is specified (in the 5 × 1 pixel range, the first line from the top), and the pixel range is expanded in a direction away from the missing pixel by skipping the same pixel. In this example, the fifth line of priority information is skipped and the fifth line is moved to the fourth line. Excluding missing pixels, the pixel ranges to which the priority information is applied are the fourth and sixth rows and the eighth and ninth rows.

  Next, in FIG. 10C, the first defective nozzle is in the fifth row, and the second defective nozzle is in the eighth row. In this case, specifically, priority information for the first defective nozzle (fifth row) is acquired, and a missing pixel row (eighth row) by the second defective nozzle (eighth row) is obtained. The corresponding pixel is determined, but the eighth row does not fall within the range of 5 × 1 pixels based on the fifth row. Therefore, the pixel range of the priority information is not expanded. Excluding missing pixels, the pixel ranges to which the priority information is applied are the third and fourth rows and the sixth and seventh rows.

  When the defective nozzle in the eighth row is the first defective nozzle, the second defective nozzle is in the fifth row. In this case, specifically, priority information for the first defective nozzle (eighth row) is acquired, and a missing pixel row (fifth row) by the second defective nozzle (fifth row) is obtained. The corresponding pixel is determined, but the fifth row does not fall within the range of 5 × 1 pixels based on the eighth row. Therefore, the pixel range of the priority information is not expanded. Excluding missing pixels, the pixel ranges to which the priority information is applied are the sixth and seventh rows and the ninth and tenth row ranges.

In this example, the priority information ranges overlap in the seventh and eighth rows. However, since any pixel can eject ink droplets, the process is not wasted if an allocation process is performed to change the ink amount.
That is,
After specifying the pixel range of the pixel of the missing pixel (first dot position) priority information by the first defective nozzle,
The pixel of missing pixels (second dot position) by the second defective nozzle is not included in the pixel range of priority information,
“The pixel range of the priority information is not extended in the direction away from the pixel (first dot position) of the first defective nozzle by skipping the same pixel (second dot position)”.

Even in the example of FIG.
The “missing pixel pixel (second dot position) by the second defective nozzle is not included in the priority information pixel range”.
In this example, the priority information ranges overlap in the seventh row. However, since the pixels in the seventh row can also eject ink droplets, the process is not wasted if the process of assigning and transferring the ink amount is performed.
Even in the example of FIG.
The “missing pixel pixel (second dot position) by the second defective nozzle is not included in the priority information pixel range”.
In this example, the priority information ranges do not overlap. Therefore, if the allocation process is performed to change the ink amount, the process is not wasted.

If the priority information is corrected in step S135, it is determined in step S140 whether there is an insufficient ink amount. In the above-described allocation process, in the case of print data in which ink droplets are attached to the positions of missing pixels, the ink amount is insufficient due to the fact that ink droplets are not attached, and the ink is placed at the next pixel position according to the priority information. Assign the amount. For this reason, if it is determined in step S140 that there is a shortage of ink, the next assigned dot position is specified based on the priority information in step S145, and in step S150, the entire ink amount is added to the dot position. Alternatively, it is determined whether there is room to allocate a part, and if there is room, processing for assigning the ink amount is performed in step S155. The allocated ink amount is subtracted from the insufficient ink amount. The above processing is repeated until there is no ink shortage or there is no dot position of the next order based on the priority information.
When the allocation process is completed, the value of the variable i is increased by “1” in step S160, and the process returns to step S110 to determine whether there is another defective nozzle.

In this case, steps S100 to S135 and S160 correspond to the specifying unit, and steps S140 and S155 correspond to the data correction unit.
Note that a print control apparatus is configured by hardware and software that execute each of the processes, and the process steps executed by the print control apparatus correspond to a print control method. A program executed by the control circuit 20 or the PC 40 in accordance with the processing procedure corresponds to a print control program, and a medium such as a ROM or a hard disk for recording the program corresponds to a medium for recording the print control program.

(Second Embodiment)
In the first embodiment, the missing pixels are assigned to the periphery in consideration of the ink amount that is insufficient by performing the assignment process. On the other hand, as the allocation process, it is possible not to consider the ink amount. In this case, if ink drops are to be attached to missing pixels, the assigned dot position of the next rank is specified based on the priority information, and if the dot position is not to attach ink drops, Instead, ink droplets are attached.

FIG. 11 shows a flowchart when this allocation process is reflected in the program executed by the computer, as in FIG. The process of steps S200 to S235 is the same as the process of steps S100 to S135.
In steps S240 to S255, the ink droplets of the missing pixels are moved to another dot position based on the priority information in steps S240 to S255, which reflected the ink amount based on the multivalued data in steps S140 to S155. It becomes processing.

  That is, in step S240, if ink droplets are to be added to missing pixels according to the print data, it is determined whether or not there are insufficient dot candidates. If there are insufficient dot candidates, priority is given in step S245. Based on the degree information, the next assigned dot position is specified. In step S250, if ink droplets are not to be applied to the dot positions according to the print data, it is determined that dot allocation is possible, and dot allocation is performed in step S255. If dot allocation is performed, the information on insufficient dots is subtracted and there are no missing dot candidates in the same manner as the ink amount is subtracted in step S155. This may be repeated until it is determined that dot assignment is possible at the next assigned dot position.

(Third embodiment)
In the first embodiment and the second embodiment, the priority information is expanded in advance and the allocation process is performed. However, the priority information is not expanded, and the second dot position is avoided and the third dot is allocated. It is also possible to specify the position.
FIG. 12 shows a flowchart when this allocation process is reflected in the program executed by the computer, as in FIG. The process of steps S300 to S325 is the same as the process of steps S100 to S125.

In the present embodiment, the priority information correction performed in steps S130 and S135 is not performed.
On the other hand, in the allocation process, after specifying the next assigned dot position based on the priority information in step S345, it is determined in step S346 whether there is another defective nozzle, and the other defective nozzle is determined. If there is, in step S347, the assigned dot position of the next order is specified so as to avoid missing pixels corresponding to other defective nozzles.

As shown in FIG. 13, if the fifth row is the first defective nozzle, the pixel range to which the priority information is applied is not affected by the sixth row being the second defective nozzle. The third line to the seventh line. That is, the priority information is not corrected so as to avoid the sixth row which is the second defective nozzle.
However, since the dot position of the second order marked with “2” in the priority information is the position of the missing pixel of the second defective nozzle, in step S345, the next rank dot position is determined based on the priority information. When the sixth line is specified as the allocated dot position, the presence / absence of another defective nozzle is determined in step S346, and if it is determined that there is a missing pixel, the missing pixel corresponding to the other defective nozzle is determined in step S347. The next assigned dot position is specified so as to avoid it. Accordingly, since the sixth row is a missing pixel corresponding to another nozzle, the third row, which is the assigned dot position of the next order to avoid this, becomes the assigned dot position of the next order.

As described above, the allocation processing is performed from the priority information based on the first dot position (fifth row) corresponding to the first defective nozzle and the second dot position information (sixth row). An inapplicable pixel (6th row) is specified, and the pixel to be assigned (next 3rd row) is specified by skipping the pixel.
The above processing is repeated until there is no ink shortage or there is no dot position of the next order based on the priority information.

Needless to say, the present invention is not limited to the above embodiments. It goes without saying for those skilled in the art,
-Applying the combination of the mutually replaceable members and configurations disclosed in the above-described embodiments as appropriate-The above-described embodiments are not disclosed in the above-described embodiments, but are publicly known techniques. The members and structures that can be mutually replaced with the members and structures disclosed in the above are appropriately replaced, and the combination is changed and applied. It is an embodiment of the present invention that a person skilled in the art appropriately replaces the members and configurations that can be assumed as substitutes for the members and configurations disclosed in the above-described embodiments, and changes the combination to apply. It is disclosed as.

DESCRIPTION OF SYMBOLS 10 ... Printer (droplet discharge apparatus), 11 (11a-11d) ... Print head, 12 ... Platen, 13 ... Platen motor, 14 ... Feed motor, 15 ... Paper feed roller, 16 ... Operation panel and display part, 17 ... Print head, 18 ... carriage motor, 19 ... belt, 20 ... control circuit, 30 ... network, 40 ... PC.

Claims (7)

A position information acquisition unit that acquires positions of the first defective nozzle and the second defective nozzle among the plurality of nozzles that eject ink onto the medium;
A data generation unit that generates print data having dot positions for ejecting ink droplets on a medium;
In the print data, when the first defective nozzle is not defective, an ink droplet is ejected to specify a first dot position printed on the medium, and when the second defective nozzle is not defective, the ink droplet is discharged. Based on priority information in which a priority order is set in a predetermined area in each pixel unit with reference to the first dot position, the third dot position to be ejected and printed on the medium is specified, A specifying unit for specifying a third dot position different from the first dot position and the second dot position;
A print control apparatus comprising: a data correction unit configured to correct the print data corresponding to an allocation process for assigning information on ejection of ink droplets to the first dot positions to the third dot positions; .   2. The printing according to claim 1, wherein the specifying unit expands and corrects the priority information area based on the second dot position so as not to overlap the second dot position. Control device.   The specifying unit specifies a pixel to which the assignment process cannot be applied, based on the priority information based on the first dot position corresponding to the first defective nozzle and the information on the second dot position. The printing control apparatus according to claim 1, wherein the pixel to be assigned is specified by skipping the pixel.   The priority information is different between first priority information corresponding to the first defective nozzle and second priority information corresponding to the second defective nozzle. The print control apparatus according to claim 1. The print data generated by the data generation unit is print data in which the dot position and the amount of ink ejected to the dot position are associated with each other.
The allocation process is a process of allocating the ink amount at the first dot position to the third dot position;
The specifying unit specifies a dot position of a subsequent rank different from the dot position of the previous rank based on the priority information;
The data correction unit corrects the print data corresponding to a process of allocating an ink amount that cannot be allocated to the preceding dot positions to the subsequent dot positions. The printing control apparatus according to claim 1. Obtaining a position of a first defective nozzle and a second defective nozzle among a plurality of nozzles that eject ink onto the medium;
Generating print data having dot positions for ejecting ink droplets on a medium;
In the print data, when the first defective nozzle is not defective, an ink droplet is ejected to specify a first dot position printed on the medium, and when the second defective nozzle is not defective, the ink droplet is discharged. Based on priority information in which a priority order is set in a predetermined area in each pixel unit with reference to the first dot position, the third dot position to be ejected and printed on the medium is specified, Identifying a third dot position different from the first dot position and the second dot position;
And a step of correcting the print data corresponding to an allocating process for assigning ink droplet ejection information to the first dot position to the third dot position. A function of acquiring positions of a first defective nozzle and a second defective nozzle among a plurality of nozzles that eject ink to a medium;
A function of generating print data having dot positions for ejecting ink droplets on a medium;
In the print data, when the first defective nozzle is not defective, an ink droplet is ejected to specify a first dot position printed on the medium, and when the second defective nozzle is not defective, the ink droplet is discharged. Based on priority information in which a priority order is set in a predetermined area in each pixel unit with reference to the first dot position, the third dot position to be ejected and printed on the medium is specified, A function of specifying a third dot position different from the first dot position and the second dot position;
A print control program for causing a computer to realize a function of correcting the print data corresponding to an allocation process for allocating ink droplet ejection information to the first dot position to the third dot position. The medium that recorded.

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