JP2006159588A - Manufacturing method for printing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a printing head which has few constraints on manufacture and is suitable for reducing irregularities of printing characteristics. <P>SOLUTION: First, a plurality of the printing heads are manufactured. A density characteristic of each nozzle N which constitutes the printing head is measured for each printing head. Density characteristic information showing the measured density characteristics is stored in a density characteristic information storage part. Next, on the basis of the density characteristic information of the density characteristic information storage part, an average value of the density values of the nozzles N which constitute the printing head is calculated as a density value of the printing head for each printing head. The printing heads of a pair one of which has the density value not smaller than a total average value and the other of which has the density value smaller than the total average value are selected. Then, the printing heads of the selected pair are arranged opposite to each other in a paper send direction, whereby a line head is manufactured. The line head is incorporated in a line head type printer and shipped. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a system, a program, and a method for performing printing by an inkjet printer or the like, and more particularly, to a method for manufacturing a print head that has few manufacturing restrictions and is suitable for reducing variations in print characteristics.

Ink jet printers employing the ink jet method are generally widely used not only in offices but also in general users with the spread of personal computers, digital cameras, and the like because inexpensive and high-quality color prints can be easily obtained.
There are two types of inkjet printers, a multi-pass type printer and a line head type printer. Both types perform printing by forming dots on printing paper by ejecting ink from each nozzle of the print head. At present, it is difficult to make the density characteristics of the nozzles uniform due to the limit of manufacturing accuracy. If nozzles having variations in density characteristics are mounted on the same ink jet printer, density unevenness occurs, causing image quality deterioration.

Conventionally, as a technique for reducing density unevenness generated in an ink jet printer, for example, a nozzle block manufacturing method disclosed in Patent Document 1 is known.
The invention described in Patent Document 1 is a method of manufacturing a nozzle block including a plurality of nozzle units. The nozzle units are manufactured, and the manufactured nozzle units are ranked into predetermined ranks based on ink discharge amounts. A nozzle block is manufactured by combining the divided nozzle units for each rank.
JP 2001-38892 A

However, in the invention described in Patent Document 1, since one nozzle block is manufactured by combining nozzle units of the same rank, when there is no nozzle unit to be combined, the nozzle block cannot be manufactured. There was a problem that manufacturing restrictions were large.
Such a problem is assumed not only in the case of reducing the density unevenness but also in the case of reducing the variation in other print characteristics.

  Therefore, the present invention has been made paying attention to such an unsolved problem of the conventional technology, and has a print head suitable for reducing variations in print characteristics with few manufacturing restrictions. The object is to provide a manufacturing method.

[Mode 1] In order to achieve the above object, a method of manufacturing a print head according to mode 1 includes:
A print head manufacturing method for manufacturing a print head, comprising:
A print characteristic measuring step for measuring a print element constituting the print head or a print characteristic of the print head; and
A print head selection step of selecting a plurality of the print heads based on the measurement result of the print characteristic measurement step;
A print head arrangement step of arranging a plurality of print heads selected in the print head selection step so that dots are formed at the same position of the print medium by the print heads.

Thus, if printing is performed while selecting the print head at a predetermined frequency, it is possible to reduce the variation in print characteristics. Further, since it is not necessary to select print heads having the same print characteristics, it is possible to obtain an effect that the manufacturing restrictions are eased as compared with the conventional case.
Here, the print head arrangement step arranges a plurality of print heads so that dots can be formed at the same location on the print medium, but the dots may not necessarily be accurately formed at the same location due to manufacturing accuracy. In many cases, dots of a plurality of print heads are formed in the vicinity as a result of the arrangement.
The print characteristics include, for example, image quality characteristics (density, color gamut, resolution, graininess, glossiness, etc.) and weather resistance characteristics (light resistance, gas resistance, water resistance, friction resistance, durability, etc.). . The same applies to the method for manufacturing the print head according to the sixth embodiment.

[Mode 2] Further, the method for manufacturing the print head according to mode 2 is the method for manufacturing the print head according to mode 1,
The print head selection step selects a plurality of the print heads in which the print characteristic values are dispersed with a predetermined value as a boundary.
As a result, since the print characteristic values of the print heads are dispersed at a predetermined value, if printing is performed while selecting the print heads at a predetermined frequency, the print characteristic values realized by the print heads are set to the predetermined values. Can be approached. Therefore, since the printing characteristics are made uniform, it is possible to reduce the variation in printing characteristics.

[Mode 3] Furthermore, the method for manufacturing the print head according to mode 3 is the method for manufacturing the print head according to mode 2,
The print head selecting step selects a plurality of print heads having the same or similar difference between the print characteristic value and the predetermined value.
Thus, printing can be performed while selecting the print heads at a similar frequency in order to set the print characteristic values realized by the print heads to a predetermined value. Therefore, it is possible to reduce the variation in printing characteristics and to obtain the effects of suppressing the occurrence of banding.

[Mode 4] Furthermore, the method for manufacturing a print head according to mode 4 is the method for manufacturing a print head according to any one of modes 2 and 3,
The predetermined value is an average value of print characteristics of the plurality of print heads.
Thereby, since the printing characteristics are averaged, it is possible to reduce the variation in printing characteristics and to obtain an effect that the printing characteristics can be averaged.

[Mode 5] Furthermore, the method for manufacturing a print head according to mode 5 is the method for manufacturing a print head according to any one of modes 1 to 4,
The printing characteristic measuring step is characterized in that a printing density of dots printed when the printing head is controlled with a predetermined control value is measured.
Thereby, the effect that the variation in density characteristics can be reduced is obtained.

[Mode 6] Furthermore, the method for manufacturing the print head of mode 6 includes:
A print head manufacturing method for manufacturing a print head, comprising:
A printing characteristic measurement step for measuring the printing characteristic of the printing element;
A printing element selection step of selecting a plurality of the printing elements based on the measurement result of the printing characteristic measurement step;
A print head manufacturing step of manufacturing the print head by arranging a plurality of print elements selected in the print element selection step so that dots are formed at the same location of the print medium by the print elements. And

Thus, if printing is performed while selecting printing elements at a predetermined frequency, it is possible to reduce the variation in printing characteristics. Further, since it is not necessary to select printing elements having the same rank in printing characteristics, there is an effect that manufacturing restrictions are eased as compared with the conventional case.
Here, in the print head manufacturing step, a plurality of printing elements are arranged so that dots can be formed at the same location on the print medium. However, even if the dots are not necessarily formed accurately at the same location due to manufacturing accuracy. In many cases, dots of a plurality of printing elements are formed in the vicinity as a result of the arrangement.

[Mode 7] Furthermore, the method for manufacturing the print head according to mode 7 is the method for manufacturing the print head according to mode 6,
The printing element selection step is characterized in that a plurality of the printing elements whose printing characteristic values are dispersed with a predetermined value as a boundary are selected.
As a result, the printing characteristic values of the printing elements are dispersed at a predetermined value, so if printing is performed while selecting the printing elements at a predetermined frequency, the printing characteristic values realized by the printing elements are set to the predetermined values. Can be approached. Therefore, since the printing characteristics are made uniform, it is possible to reduce the variation in printing characteristics.

[Embodiment 8] Furthermore, the manufacturing method of the print head of Embodiment 8 is the manufacturing method of the print head of Embodiment 7,
The printing element selection step is characterized in that a plurality of printing elements having the same or approximate difference between the printing characteristic value and the predetermined value are selected.
Thus, printing can be performed while selecting the printing elements with the same frequency so that the value of the printing characteristic realized by the printing elements becomes a predetermined value. Therefore, it is possible to reduce the variation in printing characteristics and to obtain the effects of suppressing the occurrence of banding.

[Embodiment 9] Further, the manufacturing method of the print head of Embodiment 9 is the manufacturing method of the print head of any one of Embodiments 7 and 8,
The predetermined value is an average value of printing characteristics of the plurality of printing elements.
Thereby, the same effect as in the fourth aspect is obtained.

[Mode 10] Furthermore, the method for manufacturing a print head according to mode 10 is the method for manufacturing a print head according to any one of modes 6 to 9,
The printing characteristic measurement step is characterized in that a printing density of dots printed when the printing element is controlled with a predetermined control value is measured.
Thereby, the same effect as in the fifth aspect is obtained.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 to 8 are views showing a first embodiment of a method of manufacturing a print head according to the present invention.
In the present embodiment, the print head manufacturing method according to the present invention is applied to the case of reducing density unevenness occurring in printing with a line head type printer 100 as shown in FIG.

First, an outline of functions of a line head type printer 100 to which the present invention is applied will be described with reference to FIG.
FIG. 1 is a functional block diagram showing an outline of functions of the line head type printer 100.
As shown in FIG. 1, the line head type printer 100 includes a line head 10 in which a plurality of print heads are arranged, a paper sending unit 12 that sends printing paper onto the line head 10, and the line head 10 and the paper sending unit 12. And a printing control unit 14 for controlling the printing.

FIG. 2 is a diagram illustrating the structure of the line head 10.
As shown in FIG. 2, the line head 10 includes a black nozzle group 50 in which a plurality of nozzles N that eject black (K) ink are linearly arranged, and a nozzle N that ejects yellow (Y) ink is linear. A plurality of yellow nozzle groups 52 arranged in a row, a magenta nozzle group 54 in which nozzles N that eject magenta (M) ink are arranged in a straight line, and a plurality of nozzles N that eject cyan (M) ink in a straight line. The arranged cyan nozzle groups 56 are provided in a direction in which printing paper is sent out by the paper sending unit 12 (hereinafter referred to as a paper sending direction).

FIG. 3 is a diagram illustrating the structure of the black nozzle group 50.
As shown in FIG. 3, the black nozzle group 50 comprises a head block 1 in which print heads H _{11 to} H _n1 each having a plurality of nozzles N are linearly arranged in a direction perpendicular to the paper feed direction. The print heads H _{12 to} H _n2 having a plurality of nozzles N are linearly arranged in a direction orthogonal to the paper feed direction to form a head block 2. The two nozzles N form dots at the same location on the printing paper. As described above, the head blocks 1 and 2 are provided in the paper feeding direction.

For a pair of print heads arranged in the paper feed direction (for example, print heads H ₁₁ and H ₁₂ ), the density value of one print head is the overall average value (the average value of the density values of all manufactured nozzles N). The same applies hereinafter.) The density value of the other print head is less than the overall average value. In the present embodiment, the density value of the print head is adopted as the average value of the density values of the nozzles N constituting the print head.

The yellow nozzle group 52, the magenta nozzle group 54, and the cyan nozzle group 56 are configured in the same manner as the black nozzle group 50.
Returning to FIG. 1, the line head type printer 100 further includes a density characteristic information storage unit 16 that stores density characteristic information indicating the density characteristic of each nozzle N, a print data acquisition unit 18 that acquires print data, and a density characteristic. Based on the density characteristic information in the information storage unit 16, the nozzle selection unit 20 selects any one of a pair of nozzles N arranged in the paper feed direction.

The print control unit 14 performs printing using the nozzles N selected by the nozzle selection unit 20 based on the print data acquired by the print data acquisition unit 18.
Next, a method for manufacturing the line head type printer 100 will be described.
FIG. 4 is a process flowchart showing a method for manufacturing the line head type printer 100.
First, as shown in FIG. 4, a plurality of print heads are manufactured through step S100.

  Next, through steps S102 and S104, for each manufactured print head, the density characteristic of each nozzle N constituting the print head is measured, and density characteristic information indicating the measured density characteristic is stored in the density characteristic information storage unit 16. save. In the measurement of density characteristics, the density value of the ink ejected when each nozzle N is controlled with a predetermined control value is measured. Ideally, the density value should be constant, but the density value of each nozzle N varies due to the limit of manufacturing accuracy. Moreover, as a measuring method, a well-known measuring method can be utilized.

  Next, through step S106, based on the density characteristic information in the density characteristic information storage unit 16, for each manufactured print head, the average value of the density values of the nozzles N constituting the print head is calculated as the density value of the print head. Calculate as Then, a pair of print heads in which one density value is equal to or higher than the overall average value and the other density value is less than the overall average value is selected from the plurality of manufactured print heads.

Next, through step S108, the selected pair of print heads are arranged facing the paper feed direction to manufacture the nozzle groups 50 to 56, and the nozzle groups 50 to 56 are combined to manufacture the line head 10.
FIG. 5 is a diagram for explaining a process of manufacturing the line head 10.
As a result of the measurement of the density characteristics, it is assumed that the density values of the print heads 1 to 6 (the print heads identified by the head numbers 1 to 6; the same applies hereinafter) are as follows. The overall average value is “100”.

Print head 1 200
Print head 2 180
Print head 3 50
Print head 4 150
Print head 5 80
Print head 6 50

Next, the print heads 1 to 6 are rearranged in order from the lowest density value. As a result, it becomes as follows.

Print head 3 50
Print head 6 50
Print head 5 80
Print head 4 150
Print head 2 180
Print head 1 200

Then, a pair of print heads in which one density value is equal to or greater than the overall average value and the other density value is less than the overall average value is selected. When there are a plurality of candidates for the combination, a pair of print heads having the same or similar difference between the density value and the overall average value is selected.

First, since the density value of the print head 3 is “50” and the difference from the overall average value is 100−50 = 50, the print head whose difference is “50” is searched. As a result, the density value of the print head 4 is “150”, and the difference from the overall average value is 150−100 = 50. Therefore, the print heads 3 and 4 are selected as a pair of print heads.
Next, since the density value of the print head 6 is “50” and the difference from the overall average value is 100−50 = 50, the print head whose difference is “50” is searched. As a result, since the corresponding print head does not exist, a print head having a close difference is searched. As a result, the density value of the print head 2 is “180”, and the difference from the overall average value is 180−100 = 80, so the combination of the print heads 6 and 2 is likely to be good. However, when the remaining combination is the print heads 5 and 1, the difference between the print heads 6 and 2 (hereinafter simply referred to as deviation) is 80-50 = 30, whereas the deviation of the print heads 5 and 1 is 100. −20 = 80. As the deviation is larger, the printing head usage frequency is biased. Therefore, the difference in deviation between the pair of printing heads is preferably as small as possible. Therefore, other combinations are also considered. Other combinations include a combination of print heads 6 and 1 and a combination of print heads 5 and 2. In this case, the deviation of the print heads 6 and 1 is 100-50 = 50, and the deviation of the print heads 5 and 2 is 80-20 = 60. This combination is preferable because there is no combination with an excessively large deviation.

Accordingly, the print heads 6 and 1 are selected as a pair of print heads, and the print heads 5 and 2 are selected as a pair of print heads.
As shown in FIG. 5, the selected pair of print heads are arranged to face each other in the paper feeding direction. In the example of FIG. 5, the print heads 3 and 4, the print heads 6 and 1, and the print heads 5 and 2 are arranged facing each other.

When the line head 10 is manufactured in this way, the manufactured line head 10 is assembled to the line head type printer 100 through steps S110 and S112, and the line head type printer 100 is shipped.
Next, the configuration of the line head type printer 100 will be described in detail.
FIG. 6 is a block diagram illustrating a hardware configuration of the line head type printer 100.

  As shown in FIG. 6, the line head type printer 100 includes a CPU 30 that controls operations and the entire system based on a control program, a ROM 32 that stores a control program for the CPU 30 in a predetermined area, and a ROM 32 that reads out from the ROM 32. The RAM 34 stores data and calculation results required in the calculation process of the CPU 30, and an I / F 38 that mediates input / output of data to / from an external device. These are used to transfer data. Are connected to each other via a bus 39 which is a signal line.

The I / F 38 includes, as external devices, an operation panel 40 including a touch panel that can input and display data as a human interface, a storage device 42 that stores data, tables, and the like as files, a line head 10, and paper A sending unit 12 and a printer cable 199 are connected.
The storage device 42 constitutes the density characteristic information storage unit 16 and stores a density characteristic information registration table 400 in which density characteristic information is registered.

FIG. 7 is a diagram illustrating a data structure of the density characteristic information registration table 400.
In the density characteristic information registration table 400, one record is registered for each nozzle N as shown in FIG. Each record includes a field 402 for registering the head block number, a field 404 for registering the nozzle N number, and a field 406 for registering the density value of the nozzle N. The density characteristic information is registered in the step S104.

In the example of FIG. 7, “1” is registered as the head block number, “1” as the nozzle number, and “150” as the density value in the first row record. This indicates that the density value of the first nozzle N from the left of the print head H ₁₁ is 150, and 50 variations occur from the overall average value.
The CPU 30 includes a microprocessing unit and the like, starts a predetermined program stored in a predetermined area of the ROM 32, and executes a printing process shown in the flowchart of FIG. 8 according to the program.

FIG. 8 is a flowchart showing the printing process.
The printing process is a process for printing in response to a print request. When the printing process is executed by the CPU 30, the process first proceeds to step S200 as shown in FIG.
In step S200, it is determined whether or not a print request has been received. When it is determined that a print request has been received (Yes), the process proceeds to step S202. When it is determined that this is not the case (No), a print request is received. Until it is received in step S200.

In step S202, print data is received, the process proceeds to step S204, and binarization processing is executed based on the received print data. In the binarization processing, binary data indicating whether or not to print a dot for each color of each pixel by converting the pixel value of each pixel into CMYK in an image composed of print data and performing error diffusion processing or the like. Convert to
Next, the process proceeds to step S206, where the head (left end) print heads H ₁₁ and H ₁₂ of the head blocks 1 and 2 of the same color are set as processing targets, and the process proceeds to step S208 to start from the processing target print head. The first pair of nozzles N is selected, and the density values of the selected pair of nozzles N are read from the density characteristic information registration table 400, and the process proceeds to step S210.

  In step S210, it is determined whether or not all of the read density values are equal to or greater than the overall average value. When it is determined that any of the density values is less than the overall average value (No), the process proceeds to step S212. Thus, it is determined whether or not all of the read density values are less than the overall average value. When it is determined that any of the density values is greater than or equal to the overall average value (No), the process proceeds to step S214.

In step S214, for the selected pair of nozzles N whose density value is equal to or greater than the overall average value (hereinafter referred to as high discharge nozzle N), the density value of the selected pair of nozzles N is less than the overall average value. According to the difference between the density value of the high discharge nozzle N and the overall average value for the low discharge nozzle N at a frequency according to the difference between the density value of the thing (hereinafter referred to as the low discharge nozzle N) and the overall average value. The selection frequency (the number of selections) of the high discharge nozzle N and the low discharge nozzle N is set so as to be selected at different frequencies. When the overall average value is D _AV , the high discharge nozzle N density value is D _H , and the low discharge nozzle N density value is D _L , the high discharge nozzle N selection frequency X and the low discharge nozzle N selection frequency Y are: And can be calculated by the following equation (1).

(D _H −D _AV ) X = (D _AV −D _L ) Y (1)

  In the example of FIG. 7, for the nozzle 1, the density value of the nozzle 1 of the head block 1 is “150”, and the density value of the nozzle 1 of the head block 2 is “50”. When the overall average value is “100”, the selection frequencies X and Y of the nozzle 1 are (100−50) X = (150−100) Y according to the above equation (1), which is 1: 1. Therefore, the nozzles 1 of the head blocks 1 and 2 are selected with a selection frequency of 1: 1.

  Next, the process proceeds to step S216, and the set selection frequency is stored in the storage device 42 in association with the nozzle number and the like. The process proceeds to step S218, and steps S210 to S216 are performed for all nozzles of the print head to be processed. It is determined whether or not the processes of S230 and S232 have been completed. If it is determined that the processes have been completed for all nozzles (Yes), the process proceeds to step S220.

In step S220, it is determined whether or not the processing of steps S210 to S218, S230, and S232 has been completed for all print heads of the same color nozzle group, and when it is determined that the processing has been completed for all print heads (Yes) ) Proceeds to step S222.
In step S222, it is determined whether or not the processing of S210 to S220, S230, and S232 has been completed for all color nozzle groups. If it is determined that the processing has been completed for all nozzle groups (Yes), step S224 is performed. Migrate to

  In step S224, a print control process is executed based on the binarized print data. In the print control process, when controlling the pair of nozzles N, the selection frequency corresponding to this is read from the storage device 42, and printing is performed while selecting the pair of nozzles N at the read selection frequency. In the above example, for the nozzle 1, for example, when printing an odd line, printing is performed by the nozzle 1 of the head block 1, and when printing an even line, printing is performed by the nozzle 1 of the head block 2. . More specifically, print data for the head block 1 and print data for the head block 2 may be generated, and printing may be performed while the head blocks 1 and 2 are synchronized. A switch may be provided, and each nozzle N may be switched every predetermined number of times while measuring the number of ejections of the nozzle N.

When the process of step S224 ends, the series of processes ends and the original process is restored.
On the other hand, when it is determined in step S222 that the process has not been completed for all the color nozzle groups (No), the other color nozzle groups are set as processing targets, and the process proceeds to step S206.
On the other hand, when it is determined in step S220 that the processing has not been completed for all the print heads of the same color nozzle group (No), the process proceeds to step S226, and the next block of the head blocks 1 and 2 of the same color. The print head is set as a processing target, and the process proceeds to step S208.

On the other hand, when it is determined in step S218 that the processing has not been completed for all the nozzles of the print head to be processed (No), the process proceeds to step S228 to start the next pair of nozzles N from the print head to be processed. The density value of the selected pair of nozzles N is read from the density characteristic information registration table 400, and the process proceeds to step S210.
On the other hand, when it is determined in step S212 that all of the read density values are less than the overall average value (Yes), the process proceeds to step S230, and the larger one of the selected pair of nozzles N is selected. The frequency is set to “1” and the selection frequency with the smaller density value is set to “0”, respectively, and the process proceeds to step S216.

On the other hand, if it is determined in step S210 that all of the read density values are equal to or greater than the overall average value (Yes), the process proceeds to step S232, and the smaller one of the selected pair of nozzles N is selected. The frequency is set to “1” and the selection frequency with the larger density value is set to “0”, respectively, and the process proceeds to step S216.
Next, the operation of the present embodiment will be described.

When the line head printer 100 receives print data together with a print request, the binarization process is executed based on the received print data through step S204.
First, through steps S206 and S208, the first print head of the head blocks 1 and 2 of the same color is set as a processing target, and the first pair of nozzles N is selected from the processing target print heads. The density value is read out. When the density values of the pair of nozzles N are dispersed with the whole average value as a boundary, the selection frequency of the pair of nozzles N is set through step S214. The selection frequency is a frequency corresponding to the difference between the density value of the low ejection nozzle N and the overall average value for the high ejection nozzle N, and the density value and the overall average value of the high ejection nozzle N for the low ejection nozzle N. Are set at a frequency corresponding to the difference between the two. Therefore, when the pair of nozzles N is used at the set selection frequency, density unevenness can be reduced and density characteristics are easily averaged.

If the density values of the pair of nozzles N are both less than the overall average value, the density value of the pair of nozzles N having the larger density value is “1” and the density value is small through step S230. The selection frequency is set to “0”. Thereby, since the nozzle N whose density value is close to the overall average value is used, the density characteristics are easily averaged.
If the density values of the pair of nozzles N are all equal to or higher than the overall average value, the density value of the pair of nozzles N having the smaller density value is set to “1” and the density value is large after step S232. The selection frequency is set to “0”. Thereby, since the nozzle N whose density value is close to the overall average value is used, the density characteristics are easily averaged.

Steps S210 to S218, S230, and S232 are performed for each of the nozzles N of the pair of print heads to be processed, then for each print head, and further for each color nozzle group.
Then, through step S224, based on the binarized print data, a pair of nozzles N is selected at a set selection frequency, and printing is performed.

  In the example of FIG. 7, for the nozzle 1, the difference between the density value and the overall average value is both “50”, so printing is performed using the nozzles 1 of the head blocks 1 and 2 alternately. Further, since the density values of the nozzles 2 are both “100”, one or both of the nozzles 2 of the head blocks 1 and 2 are alternately used for printing. From the viewpoint of suppressing the occurrence of banding, both are preferably used alternately. For nozzle 3, since the density value of nozzle 3 of head block 2 is “100”, only nozzle 3 of head block 2 is used for printing.

In this way, in the present embodiment, the density characteristics of the nozzle N are measured, a pair of print heads is selected based on the measurement result, and the selected pair of print heads are printed on the same print paper by the print heads. Arrange so that dots are formed at the locations.
Accordingly, density unevenness can be reduced by performing printing while selecting a pair of print heads at a predetermined frequency. In addition, since it is not necessary to select print heads having the same density characteristic, manufacturing restrictions are eased as compared with the conventional case.

Further, in the present embodiment, a pair of print heads in which density values are dispersed with the overall average value as a boundary is selected.
As a result, the density values of the pair of print heads are dispersed with respect to the overall average value, so if printing is performed while selecting the pair of print heads at a predetermined frequency, the density values realized by these print heads are It can be close to the average value. Therefore, the density characteristics are averaged, so that density unevenness can be reduced and the density characteristics can be averaged.

Further, in the present embodiment, a pair of print heads having the same or similar difference between the density value and the overall average value is selected.
Thus, printing can be performed while selecting the print heads at a similar frequency so that the density value realized by the print heads becomes an overall average value. Therefore, uneven density can be reduced and banding can be suppressed.

Further, in the present embodiment, one of the paired nozzles N is selected based on the density characteristic information indicating the density characteristic of each nozzle N, and printing is performed by the selected nozzle N based on the print data. It has become.
Thereby, since the nozzle N is selected based on the density value, density unevenness can be reduced. Further, since the nozzle N is only selected based on the density characteristic information, the processing load is less than that in the case of correcting the print data, and the printing speed can be improved.

Furthermore, in the present embodiment, the nozzle N is selected so that the density value realized by the selected nozzle N becomes the overall average value.
As a result, the density characteristics are averaged, so that density unevenness can be reduced and the density characteristics can be averaged.
Furthermore, in the present embodiment, for the high discharge nozzle N, the frequency according to the difference between the density value of the low discharge nozzle N and the overall average value, and for the low discharge nozzle N, the density value of the high discharge nozzle N Each is selected at a frequency corresponding to the difference from the overall average value.

As a result, the density characteristics are easily averaged, so that density unevenness can be further reduced.
Further, in the present embodiment, when the density values of the pair of nozzles N are all equal to or higher than the overall average value, the smaller one of the pair of nozzles N is selected.
As a result, when the density values of the pair of nozzles N are equal to or greater than the overall average value, the nozzle N closest to the overall average value is selected, and thus the density characteristics are easily averaged. Therefore, the density unevenness can be further reduced.

Further, in the present embodiment, when the density values of the pair of nozzles N are both less than the overall average value, the higher one of the pair of nozzles N is selected.
As a result, when the density values of the pair of nozzles N are both less than the overall average value, the nozzle N closest to the overall average value is selected, so that the density characteristics are easily averaged. Therefore, the density unevenness can be further reduced.

  In the first embodiment, step S102 corresponds to the print characteristic measuring step of form 1 or 5, step S106 corresponds to the print head selection step of form 1 to 3, and step S108 is of form 1. Corresponding to the print head arrangement step, the printing paper corresponds to the printing medium of form 1. The nozzle N corresponds to the printing element of form 1, the density characteristic corresponds to the printing characteristic of forms 1 to 4, and the overall average value corresponds to the average value of form 4.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a diagram showing a second embodiment of a method for manufacturing a print head according to the present invention.
In the present embodiment, the print head manufacturing method according to the present invention is applied to a case where density unevenness generated in printing by the line head printer 100 is reduced, and is different from the first embodiment. This is because the print head is manufactured by selecting the nozzle N.

Next, a method for manufacturing the line head type printer 100 will be described.
FIG. 9 is a process flowchart showing a method for manufacturing the line head type printer 100.
First, as shown in FIG. 9, a plurality of nozzles N are manufactured through step S300.
Next, through steps S302 and S304, the density characteristic of each manufactured nozzle N is measured, and density characteristic information indicating the measured density characteristic is stored in the density characteristic information storage unit 16.

Next, through step S306, based on the density characteristic information in the density characteristic information storage unit 16, a pair of nozzles N in which one density value is greater than or equal to the overall average value and the other density value is less than the overall average value is manufactured. The plurality of nozzles N are selected.
Next, through steps S308 and S310, a pair of print heads is manufactured using the pair of nozzles N so that the selected pair of nozzles N are arranged to face each other in the paper feed direction, and the pair of prints thus manufactured is printed. The nozzle groups 50 to 56 are manufactured by arranging the heads so as to face the paper feed direction, and the line head 10 is manufactured by combining the nozzle groups 50 to 56.

Then, after steps S312 and S314, the manufactured line head 10 is assembled to the line head type printer 100, and the line head type printer 100 is shipped.
In the present embodiment, since the density values are dispersed with respect to the overall average value for each pair of nozzles N, the processing in steps S110, S112, S130, and S132 is not necessary.
In this way, in the present embodiment, the density characteristic of the nozzle N is measured, and a pair of nozzles N is selected based on the measurement result. Arrange so that dots are formed at the locations.

Accordingly, density unevenness can be reduced by performing printing while selecting a pair of nozzles N at a predetermined frequency. In addition, since it is not necessary to select nozzles N having the same rank in density characteristics, restrictions on manufacturing are eased as compared with the conventional case.
Further, in the present embodiment, a pair of nozzles N in which density values are dispersed with the overall average value as a boundary is selected.

As a result, the density values of the pair of nozzles N are dispersed with respect to the overall average value. Therefore, if printing is performed while the pair of nozzles N is selected at a predetermined frequency, the density values realized by these nozzles N are all set. It can be close to the average value. Therefore, the density characteristics are averaged, so that density unevenness can be reduced and the density characteristics can be averaged.
Further, in the present embodiment, a pair of nozzles N with the same or similar difference between the density value and the overall average value is selected.

Thus, in order to make the density value realized by the nozzles N become the overall average value, printing may be performed while selecting the nozzles N with the same frequency. Therefore, uneven density can be reduced and banding can be suppressed.
In the second embodiment, step S302 corresponds to the print characteristic measuring step of form 6 or 10, step S306 corresponds to the print element selection step of form 6 to 8, and step S308 is of form 6. It corresponds to the print head manufacturing step.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a diagram showing a third embodiment of a method for manufacturing a print head according to the present invention.
In this embodiment, the print head manufacturing method according to the present invention is applied to a case where density unevenness generated in printing by the line head type printer 100 is reduced, and the first and second embodiments described above are applied. The difference from the mode is that the first and second embodiments average the density characteristics in a single dot unit, whereas the density characteristics are averaged in a block unit composed of a plurality of dots. is there.

First, a printing process executed by the line head type printer 100 will be described.
In step S214, D _AV an overall average value, the density value of the high discharge nozzle N _i D _Hi, when the density value of the low discharge nozzle N _i was D _Li, selection frequency X _i and low high-discharge nozzle N _i The selection frequency Y _i of the discharge nozzle N _i can be calculated by the following equation (2).

In the above formula (2), M is an integer of 2 or more, and indicates the number of dots constituting the block. A nozzle _Ni represents M × j (j = 0, 1,...) + I-th nozzle N from the head (left end). Further, j indicates the number of times of transition from step S218 to step S210.
FIG. 10 is a diagram illustrating a data structure of the density characteristic information registration table 400.

  In the example of FIG. 10, the density values of the nozzles 1 are all “150”, and the density values of the head block 2 are all “150”. In this case, even if the density characteristics are averaged in units of single dots as in the first embodiment, the density characteristics change regardless of the selection frequency of the nozzles 1 and 2. I can't let you. Therefore, it is considered to average density characteristics in units of 2 dots with M = 2. In the case of M = 2, when the density values of the nozzles 1 and 2 are substituted into the above equation (2), the following equation (3) is obtained.

50X ₁ + 50X ₂ = 50Y ₁ + 50Y ₁ (3)

From the above formula (3), X ₁ : X ₂ : Y ₁ : Y ₁ = 3: 1: 1: 1. Therefore, the nozzle 1 of the head blocks 1 and 2 and the nozzle 2 of the head blocks 1 and 2 are selected with a selection frequency of 3: 1: 1: 1. Thereby, when one block is comprised with the nozzles 1 and 2, a density | concentration characteristic can be averaged per the block unit.

Note that the processing in steps S210 to S218, S230, and S232 is performed for each nozzle N in the first embodiment, whereas in the present embodiment, the processing is performed in units of M nozzles N. For example, when M = 2, the nozzles 1 and 2 are processing targets in the first loop, and the nozzles 3 and 4 are processing targets in the second loop.
In this way, in the present embodiment, a plurality of nozzles N constitute one block, and the nozzles N are selected so that the density values of the blocks realized by the selected nozzles N become the overall average value. It has become.

Thereby, even when the density characteristics cannot be averaged in a single dot unit, the density characteristics can be averaged in a plurality of dot units.
In the first to third embodiments, the pair of print heads are arranged in a straight line with the head positions aligned. However, the present invention is not limited to this. For example, it can be arranged as shown in FIG.

FIG. 11 is a diagram illustrating an arrangement structure of print heads.
In the example of FIG. 11A, a pair of print heads are arranged with their head positions shifted by a half pitch. In the example of FIG. 11B, odd-numbered ones of the pair of print heads are arranged obliquely in the right direction, and even-numbered ones are arranged obliquely in the left direction.
In the first to third embodiments, the example in which the number of the array heads and the array position of the print heads are the same is shown. However, the present invention is not limited to this. For example, the array heads are produced at the factory. The density characteristics of all the print heads may be measured, and a combination of print heads may be selected so that the overall average value is “100”. In this case, the nozzle selection unit 20 is not required, and density unevenness can be reduced simply by alternately discharging the head blocks. As a result, there is no need to use processing time and unnecessary resources, and density unevenness can be easily reduced.

In the first to third embodiments, the average value of the density values of the nozzles N for selecting the print head is calculated for each print head as the density value of the print head. However, the present invention is not limited to this. Instead, the print head may be selected based on another statistical value based on the density value of each nozzle N.
In the first to third embodiments, the density average is measured by a nozzle block in which a predetermined number of nozzles N are combined, not for each nozzle N and for each print head. Based on the density average, The print head or nozzle N may be selected.

  In the first to third embodiments, the density average for each print head is measured and the print head is configured. However, the present invention is not limited to this, and the density “100” is most determined from the combination of the discharge densities of the nozzles N. It is also possible to obtain an optimum value of the combination so as to be “and to configure the print head according to the optimum value. Also in this case, the nozzle selection unit 20 is not necessary, and density unevenness can be reduced if the nozzles N that can be discharged at the same position are discharged alternately. The combination method of the nozzles N is a combination optimization problem, and therefore a combination can be obtained using a known technique.

  In the first to third embodiments, the processes in steps S206 to S222 and S226 to S232 are executed for each printing. However, the present invention is not limited to this, and these processes depend on the print data. Therefore, the selection frequency can be set by executing it only once at the time of startup or the like, and printing can be performed based on the selection frequency of the storage device 42 for each printing.

Thereby, the printing speed can be further improved.
In the third embodiment, the density value is registered in the density characteristic information registration table 400 for each nozzle N. However, the present invention is not limited to this, and one block is formed by M nozzles N. And a representative density value of each block is registered for each block, and for each block, either one of the nozzles N of the head blocks 1 and 2 is set so that the density value of the block becomes an overall average value. It can also be configured to select.

  In the first to third embodiments, the present invention is applied to the line head type printer 100. However, the present invention is not limited to this and can be applied to a multi-pass type printer. With the line head type printer 100, it is possible to obtain a high-quality printed matter in one pass, in which white streaks and dark streaks are hardly noticeable even if a flying bend phenomenon occurs. In addition, since the number of reciprocating operations can be reduced with a multi-pass type printer, higher-speed printing is possible than before.

FIG. 12 shows respective printing methods by the line head type printer 100 and the multi-pass type printer.
As shown in FIG. 12A, when the width direction of the rectangular printing paper is the main scanning direction of the image data and the longitudinal direction is the sub-scanning direction of the image data, the line head type printer 100 uses FIG. ), The line head 10 has a length corresponding to the paper width of the printing paper, and the line head 10 is fixed and the printing paper is moved in the sub-scanning direction with respect to the line head 10. Printing is completed with a pass. It is also possible to perform printing while fixing the printing paper like a so-called flatbed scanner and moving the line head 10 in the sub-scanning direction or moving both in the opposite direction. is there.

  On the other hand, as shown in FIG. 12C, the multi-pass type printer has a print head that is much shorter than the length of the paper width in the direction perpendicular to the main scanning direction, and this is the main scanning direction. Printing is performed by moving the printing paper by a predetermined pitch in the sub-scanning direction while reciprocally moving it many times. Therefore, the latter multi-pass type printer has a drawback that it takes more printing time than the line head type printer 100, but the print head can be repeatedly positioned at an arbitrary position. Some reduction of white streaking is possible.

In the first to third embodiments, the present invention is applied to an ink jet printer that performs printing by ejecting ink in dots. However, the present invention is not limited to this, and a print head in which printing elements are arranged in a line. The present invention can also be applied to other printing apparatuses using the printer, for example, thermal head printers such as thermal transfer printers and thermal printers.
In the first to third embodiments, the case where the control program stored in advance in the ROM 32 is executed in executing the processing shown in the flowchart of FIG. 8 is not limited to this. The program may be read from the storage medium storing the program showing these procedures into the RAM 34 and executed.

  Here, the storage medium is a semiconductor storage medium such as RAM or ROM, a magnetic storage type storage medium such as FD or HD, an optical reading type storage medium such as CD, CDV, LD, or DVD, or a magnetic storage type such as MO. / Optical reading type storage media, including any storage media that can be read by a computer regardless of electronic, magnetic, optical, or other reading methods.

  In the first to third embodiments, the print head manufacturing method according to the present invention is applied to the case of reducing density unevenness generated in printing by the line head type printer 100. The present invention is not limited, and can be applied to other cases without departing from the gist of the present invention.

2 is a functional block diagram showing an outline of functions of the line head type printer 100. FIG. 1 is a diagram showing a structure of a line head 10. FIG. FIG. 3 is a diagram showing the structure of a black nozzle group 50. 4 is a process flowchart illustrating a method for manufacturing the line head type printer 100. FIG. 4 is a diagram for explaining a process of manufacturing the line head 10. 2 is a block diagram showing a hardware configuration of a line head type printer 100. FIG. 6 is a diagram illustrating a data structure of a density characteristic information registration table 400. FIG. It is a flowchart which shows a printing process. 4 is a process flowchart illustrating a method for manufacturing the line head type printer 100. 6 is a diagram illustrating a data structure of a density characteristic information registration table 400. FIG. It is a figure which shows the arrangement structure of a print head. The respective printing methods of the line head type printer 100 and the multi-pass type printer are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Line head type printer, 10 ... Line head, 12 ... Paper sending part, 14 ... Print control part, 16 ... Density characteristic information storage part, 18 ... Print data acquisition part, 20 ... Nozzle selection part, 30 ... CPU, 32 ... ROM, 34 ... RAM, 38 ... I / F, 39 ... bus, 40 ... operation panel, 42 ... storage device, 199 ... printer cable

Claims (10)

A print head manufacturing method for manufacturing a print head, comprising:
A print characteristic measuring step for measuring a print element constituting the print head or a print characteristic of the print head; and
A print head selection step of selecting a plurality of the print heads based on the measurement result of the print characteristic measurement step;
A print head arrangement step comprising: arranging a plurality of print heads selected in the print head selection step so that dots are formed at the same position of the print medium by the print heads. . In claim 1,
The method of manufacturing a print head, wherein the print head selection step selects a plurality of the print heads in which values of the print characteristics are dispersed with a predetermined value as a boundary. In claim 2,
The method of manufacturing a print head, wherein the print head selection step selects a plurality of print heads having the same or similar difference between the print characteristic value and the predetermined value. In any one of Claim 2 and 3,
The print head manufacturing method, wherein the predetermined value is an average value of print characteristics of the plurality of print heads. In any one of Claims 1 thru | or 4,
The method for manufacturing a print head, wherein the print characteristic measurement step measures a print density of dots printed when the print head is controlled with a predetermined control value. A print head manufacturing method for manufacturing a print head, comprising:
A printing characteristic measurement step for measuring the printing characteristic of the printing element;
A printing element selection step of selecting a plurality of the printing elements based on the measurement result of the printing characteristic measurement step;
A print head manufacturing step of manufacturing the print head by arranging a plurality of print elements selected in the print element selection step so that dots are formed at the same location of the print medium by the print elements. A manufacturing method of a print head. In claim 6,
The method of manufacturing a print head, wherein the printing element selection step selects a plurality of the printing elements in which values of the printing characteristics are dispersed with a predetermined value as a boundary. In claim 7,
The method of manufacturing a print head, wherein the printing element selection step selects a plurality of printing elements having the same or approximate difference between the printing characteristic value and the predetermined value. In any one of Claims 7 and 8,
The print head manufacturing method, wherein the predetermined value is an average value of print characteristics of the plurality of print elements. In any one of Claims 6 thru | or 9,
The method of manufacturing a print head, wherein the print characteristic measurement step measures a print density of dots printed when the print element is controlled with a predetermined control value.

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