JP4133014B2 - Printing pattern printing method for transport deviation detection - Google Patents

Description

[0001]
The present invention relates to an ink jet type image forming apparatus that prints an image on a printing material by ejecting ink from nozzles formed on a print head. Printing method for detecting printing deviation of printed material About.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an output device such as a computer or a workstation, an ink jet image forming apparatus (referred to as an ink jet image forming apparatus) that discharges ink to form an image on a printing material such as paper is known. The ink jet image forming apparatus generally includes a print head on which nozzles for ejecting ink are formed, a carriage on which the print head is mounted and reciprocating in a predetermined direction, and a direction perpendicular to the predetermined direction (conveyance of a printing material). And a printing material conveyance device for conveying the printing material in the direction).
[0003]
When an image is formed on a sheet, the sheet being conveyed by the printing material conveying apparatus is temporarily stopped, and the carriage is reciprocated in the predetermined direction, and the nozzle is based on the image signal including image information. Ink is ejected, and an image for one band is formed on a portion of the paper that is located in an image forming region facing the nozzle outlet (ink ejection port). Thereafter, the paper is transported by a width corresponding to one band, stopped, and again, the ink is ejected from the nozzles based on the image signal while reciprocating the carriage in the predetermined direction described above. An image is formed at a newly located portion. By repeating such an operation, an image is formed on the sheet.
[0004]
In an image forming apparatus that ejects ink, such as the above-described ink jet type image forming apparatus, after printing for the print width of the print head, that is, the nozzle width (corresponding to the length of the nozzle row), the print material is set to the nozzle. Since the operation of carrying the width and printing again for the nozzle width is repeated, due to the conveyance error, if the paper conveyance amount for the nozzle width is too large, a gap is generated at the joint of the band, If it is too small, there is a problem that the joints overlap. Even in multi-pass printing, if there is a conveyance error, the dots are displaced from the target pixel, resulting in image unevenness. As described above, while the printing material conveying apparatus has a predetermined tolerance, the nozzle width of the head also has a predetermined tolerance, which may cause the above-described problems.
[0005]
Recently, the resolution of the inkjet image forming apparatus has become finer, and the adjustment can be made finer.
[0006]
On the other hand, conventionally, every time the head or the medium is replaced, the user adjusts the conveyance amount of the printing material by the conveyance deviation detection print pattern.
[0007]
[Problems to be solved by the invention]
By the way, in recent years, the amount of adjustment has become finer as the resolution of the paper conveyance amount improves. For example, the conveyance adjustment amount, which has conventionally been about 1 dot to 1/2 dot, has been improved to about 1/7 dot. However, in such an apparatus capable of fine adjustment of the conveyance amount, it is difficult for the user to detect the optimum value even if the printing pattern for detecting the conveyance deviation is printed, and the selection of the adjustment value is not always accurate. There was no case. In addition, it can be said that there is no problem if the conveyance deviation is not recognized by human eyes in the conveyance deviation detection print pattern, but depending on the image or pattern to be printed, the conveyance deviation may be recognized more remarkably. Therefore, in order to effectively use the miniaturization of the conveyance adjustment amount, more accurate conveyance deviation adjustment is desired.
[0008]
An object of the present invention is to provide a printing pattern for detecting a conveyance deviation that can easily recognize a conveyance deviation of a printing material. The law It is to provide.
[0009]
The printing pattern printing method for conveying deviation detection according to the present invention includes: The print head for ejecting ink is scanned a plurality of times on a predetermined area of the printing material, and the printing material is conveyed by the width of the predetermined area between the scans to form an image. In an inkjet image forming apparatus, Above Conveying material to be printed Slip A method of printing a conveyance deviation detection print pattern for detecting The first divided portion and the second divided portion are formed on the print head by three or more scans of the print head and the conveyance of the printing material performed between the scan of the print head and three or more times. The first step of forming the conveyance deviation detection print pattern shifted in the scanning direction is different from the conveyance amount of the printing material conveyed when the print head is scanned three times or more. The second step of repeating the first step to form a plurality of conveyance deviation detection print patterns in which the first divided portion and the second divided portion have different relative deviation amounts with respect to the conveyance direction of the printing material. In the first step, the printing is performed between the scan of the print head forming the first divided portion and the scan of the print head forming the second divided portion. Performed between three or more scans of the head Serial is interposed a plurality of times the transfer of the print material, not recorded in the scanning other than the scanning of the print head to form a scanning and the second split portion of the print head to form a first divided portion It is characterized by that.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0023]
First, with reference to FIG. 1, an external configuration of a main part of a plotter which is an example of the inkjet image forming apparatus of the present invention will be described. FIG. 1 is a perspective view showing a schematic configuration of a plotter.
[0024]
The plotter 10 includes a platen 14 on which a sheet (printed material) 12 conveyed in the direction of arrow A is placed. Two scanning rails (guide rails) 16 are spanned above the platen 14 in parallel to the platen 14. A carriage 20 that reciprocates in the directions of arrows B and C (direction orthogonal to the direction of arrow A) by a motor (not shown) and a belt 18 is attached to the scanning rail 16 via a slide bearing (not shown). Yes.
[0025]
The carriage 20 is equipped with four print heads 22K (black), 22C (cyan), 22M (magenta), and 22Y (yellow) having ink discharge ports (nozzle outlets, not shown) for discharging ink. Has been. In front of the ink ejection opening is an image forming area 23 where an image is formed. Ink is ejected from the ink ejection port to a portion of the paper 12 that is located in the image forming area 23, whereby an image is formed in this portion.
[0026]
In forming an image on a sheet 12 such as roll paper, the sheet 12 is placed on the platen 14, and the conveyance roller 24 that exposes a part of the outer peripheral surface from the opening formed in the platen 14, and the sheet 12. The paper 12 is conveyed by rotating the conveyance roller 24 by a conveyance motor (not shown) while pinching the paper 12 by the pinch roller 26 that presses both ends of the sheet from above. The carriage 20 is reciprocated above the paper 12 in the directions of arrows B and C to generate image signals carrying image information transmitted from the print control unit 102 (see FIG. 2) to the print heads 22K, 22C, 22M, and 22Y. Based on this, ink is ejected from the nozzles, and an image is formed on a portion of the paper 12 located in the image forming area 23. When the image formation is completed, a cutter (not shown) mounted on the carriage 20 is ejected to a predetermined position, and the paper 12 is cut into a predetermined size.
[0027]
FIG. 2 is a block diagram showing a configuration of control hardware of the plotter shown in FIG. The plotter shown in the figure includes a print control unit 102 and a head 22, and the print control unit 102 includes a linear scale sensor 19, a main scanning motor (carriage motor) 105, a sub-scanning motor (conveyance motor) 118, and other various sensors. Etc. are connected. The print control unit 102 can be connected to an external device 101 such as an image scanner, a personal computer, or a CAD device.
[0028]
The plotter forms an image on a sheet using the head 22 based on the image data IN_DATA transferred from the external apparatus 101. The print control unit 102 generates signals necessary for this purpose. The print control unit 102 includes a memory control unit 107, an image memory 108, a data mask unit 109, a mask memory unit 110 (110a, 110b), a linear scale count unit 111, a print trigger generation unit 112, a head control signal generation unit 113, The scanning motor control signal generation unit 114, the CPU 115, the memory 116, and the sub-scanning motor control signal generation unit 117 are configured. Among them, the CPU 115 performs an interface with the external apparatus 101 to which image data is transferred, and controls the operation of the entire print control unit 102 such as the memory 116 and I / O.
[0029]
More specifically, when image data IN_DATA is transferred from the external device 101, image data for several bands is temporarily stored in the image memory 108 via the memory control unit 107 under a command from the CPU 115. The memory control unit 107 also determines an instruction for printing the conveyance deviation detection print pattern of the present invention.
[0030]
By storing the image data for several bands in the image memory 108 by the data processing described above, printing scan is started, and reading of the image data from the image memory 108 is sequentially started. At this time, the memory control unit 107 performs a bus selection process of the image memory 108 for performing time-division input of image data from the external device 101 and reading of image data to the head 22.
[0031]
In the present embodiment, the linear scale is arranged as described above, and the two-phase signals LINSCL_A / LINSCL_B, which are output from the linear scale sensor 19 in synchronization with the scanning of the carriage 20, are shifted by 90 degrees. These are used to synchronize print control such as output of image data OUT_DATA and head drive signal generation, carriage position management, and speed control of the main scanning motor. Further, the carriage movement direction is detected from the phase relationship of the two-phase signals LNSCL_A / LINSCL_B. Further, the linear scale count unit 111 counts the amount of carriage movement from these two-phase signals, and based on the position information specified by the CPU 115, an area for reading data from the image memory 108 and an area for generating a head control signal A signal (WINDOW) is generated. The print trigger generation unit 112 generates a print timing signal (HSYNC) from the two-phase signals output from the linear scale sensor 19 as in the linear scale count unit 111. The memory control unit 107 and the head control signal generation unit 113 read image data from the image memory 108 and generate a head control signal at a timing when both the WINDOW signal and the HSYNC signal are enabled.
[0032]
The image data read from the image memory 108 is subjected to data mask processing for multi-pass printing by a data mask unit 109 constituting a data mask unit. Therefore, before starting the page printing, the CPU 115 writes the mask pattern corresponding to the number of print passes to the mask memory unit 110a via the data mask unit 109. After the printing starts, when the carriage 20 is driven and the head 22 reaches the printing area, the image data is read from the image memory 108 and the mask data is simultaneously read from the mask memory unit 110 in synchronization with the HSYNC signal. The data mask unit 109 controls the image data to be masked according to the mask data and output to the head 22. In addition, a mask pattern for detecting a carrier deviation for printing a printing pattern for detecting a carrier deviation in the present embodiment is provided as a mask memory unit 110b. In the present specification, the term “conveyance deviation” is used including deviation due to the tolerance of the nozzle width of the print head.
[0033]
In response to the WINDOW signal and the HSYNC signal, the head control signal generation unit 113 generates signals necessary for ink ejection of the selection signal BENB for each block of the head and the heater driving pulse signal HENB. In this example, since the head 22 composed of 1280 nozzles is divided into 24 blocks and used, there are 24 block enable signals BENB. The head control signal generation unit 113 also has a function of a nozzle mask unit that performs nozzle masking in units of nozzle regions divided into the number of passes in the present invention. The image data OUT_DATA output from the data mask unit 109, the block enable signals BENB0 to 23 output from the head control signal generation unit 113, the heater driving pulse signal HENB, and the like are transferred to the head 22 for control within the head 22. In the circuit, heaters are turned on only for the nozzles for which each image data OUT_DATA and enable signals (BENB, HENB) are enabled, ink droplets are ejected and adhere to the printing paper, and an image for one band is obtained in a plurality of passes. Form.
[0034]
An example of multi-pass printing will be described with reference to FIG. 3 by taking the case of four-pass printing using a single ink color head as an example. In this example, one band corresponding to the recording width of the head is divided into four nozzle areas I, II, III, and IV, and the paper is conveyed by a movement amount of a quarter band. In the first pass printing after the start of printing, the inner position corresponding to the margin M at the leading edge of the paper is positioned so as to coincide with the boundary between the head areas I and II. At this time, only the region I is activated and the regions II, III, and IV are invalidated (that is, all nozzle masks). Further, the area I is masked with print data by the first mask pattern (the logical product of the print data and the mask data is taken). This print data is the first quarter data of the first band.
[0035]
In the second pass printing, the paper is advanced by ¼ band, and only regions I and II are activated. The area I print data is masked with the first mask pattern, and the area II print data is masked with the second mask pattern. The print data in the areas I and II at this time is the data of the first quarter of the first band.
[0036]
In the third pass printing, the paper is further advanced by ¼ band, and only the regions I, II, and III are activated. At this time, the print data in area I is masked by the first mask pattern, the print data in area II is masked by the second mask pattern, and the print data in area III is the third mask. A pattern mask is applied. The print data in the areas I, II, and III at this time is the first three quarters of the first band.
[0037]
In the fourth pass printing, the paper is further advanced by ¼ band, and thereafter, the entire area I, II, III, IV of the head is activated. At this time, the print data in area I is masked by the first mask pattern, the print data in area II is masked by the second mask pattern, and the print data in area III is the third mask. A mask by the pattern is applied, and the print data in the area IV is applied by the mask by the fourth mask pattern. The print data in the areas I, II, III, and IV at this time is all the data in the first band.
[0038]
The first to fourth mask patterns for normal printing thin out part of the original print data, and the set of dots that do not overlap each other and pass through the mask of each mask pattern is the original print data To match. As a mask pattern generation method, there are a method using a predetermined fixed mask pattern and a method using a random master pattern in which recording dots and non-recording dots are randomly arranged. The print data in the regions I, II, III, and IV at this time is the entire data of the first band. Specific examples of the first to fourth mask patterns for printing the conveyance deviation detection print pattern will be described later.
[0039]
In any case, with multi-pass printing, printing is performed using a plurality of different nozzles for one line (horizontal line in the band), eliminating the influence of nozzle formation accuracy and achieving high quality with reduced density unevenness. An image can be formed. In other words, the image in the image area having a width of one pass on the paper is divided into image parts (dot group units) that complement each other for the number of passes, and each image part is a nozzle area I, II, III of the head. , IV is divided and printed. Which image portion is printed in each pass is determined by the mask pattern. In multipass printing, the effect of printing while drying ink can be achieved at the same time.
[0040]
The outline of multi-pass printing will be described with reference to the multi-pass schematic diagrams of FIGS.
[0041]
FIG. 4 is a schematic print completion diagram of one band corresponding to the nozzle width of the head 22, and a in the drawing indicates a print dot (actually a print dot group). FIG. 5 is a diagram for explaining a printing procedure for performing multi-pass printing for one band shown in FIG. Here, as in FIG. 3, an example of four-pass printing is shown. In FIG. 5, B and C indicate the carriage operation direction, A indicates the paper feed direction, and D indicates the paper feed amount at one time. In addition, (1) to (4) indicate the nozzle numbers (not actually corresponding to a plurality of nozzles) of print heads (not shown) used for printing.
[0042]
Normally, when a predetermined paper feed D is repeated as shown in FIG. 4 and an image is formed by one carriage operation for this paper feed once, the dots of FIG. 4 are formed by 4-pass multi-pass printing. In order to do this, as an example, each print dot in FIG. 4 has a relationship such as a use nozzle as shown in FIG.
[0043]
In FIG. 6 and subsequent figures, a specific method for adjusting the sheet transport amount according to the present embodiment will be described.
[0044]
FIG. 6A schematically shows a proper print image in which the first-pass image (first divided portion) 51 and the second-pass image (second divided portion) 52 match in the paper transport direction. FIG. The shift amount d1 is zero. FIG. 6B is the same image as FIG. 6A, but shows a state in which the first pass image 51 and the second pass image 52 are shifted in the paper transport direction due to an error in the paper feed amount. ing. The shift amount d2 is non-zero.
[0045]
Normally, if the paper feed is not appropriate as shown in FIG. 6B, a completed image is a dirty image due to black or white streaks between lines. However, as described above, since the output resolution of the current inkjet image forming apparatus is very fine, even if the shift is small, even if the shift is small in the first pass and the second pass, It has become very difficult to determine an appropriate value. Furthermore, it is difficult to confirm the paper feed state in a state where n-pass overprinting is performed in normal n-pass printing.
[0046]
Therefore, in this embodiment, the printing pattern for detecting the transport deviation is not printed in the first pass and the second pass, but a difference of two passes or more is provided. For example, in this example, the first pass and the fourth pass are provided. A printing pattern for detection of conveyance deviation was printed. As a result, as shown in FIG. 7, in the first pass image 51 and the fourth pass image 54, if the shift amount d3 is the same as that in FIG. Will be. The enlargement ratio corresponds to the difference between the paths used. That is, when the n-th pass and the m-th pass (m> n) are used, an enlargement ratio that is (mn) times that in the case of a 1-pass difference is obtained. In the present invention, a path to be used is selected so that (mn) is 2 or more.
[0047]
FIG. 8 shows the printing result of the conveyance deviation detection print pattern when the correction amount in the conveyance direction is changed stepwise (from −2 to +2) based on the unit correction amount. This printing instruction can be given from the outside or from the operation panel (not shown) of the plotter. This conveyance deviation detection print pattern is obtained by printing the conveyance deviation detection print pattern 50 a plurality of times while changing the correction value of the conveyance amount of the plotter stepwise so that the conveyance deviation can be easily recognized visually. In the figure, the dotted line portion 55 indicates the correction value switching timing. (This dotted line portion 55 is for explanation, and is not actually printed.) The printing result in FIG. 8 shows a case where the conveyance deviation is 0, and the correction value is 1 at the position of 0. The pass image 51 and the fourth pass image 54 have the same height (conveyance direction position). On the other hand, when the same output result of FIG. 9 is seen, the heights of the first-pass image 51 and the fourth-pass image 54 are the same for the conveyance deviation detection print pattern with the correction value of +1. This indicates that there is a conveyance shift corresponding to the correction value +1. In the case of manual correction, for example, by inputting or selecting the correction value, the user can inform the plotter of an appropriate correction amount and correct the conveyance deviation appropriately.
[0048]
Note that the characters (−2, −1, 0, +1, +2) of “correction value” in the figure may be a sheet printed in advance at a predetermined position, or a mask pattern as will be described later with reference to FIG. May be provided with a character print area, and an identifier (number or the like) representing a correction value may be printed in a predetermined pass.
[0049]
In this example, when an optimum value is found by checking the deviation by 4-pass feed, when the actual printing mode is 2-pass printing, the value measured in 4 passes is doubled and printed in 8 passes. In some cases, a value of ½ can be obtained by calculation, and optimal paper feed correction (carrying amount correction) is possible regardless of the number of printing passes during actual multi-pass printing.
[0050]
In this adjustment method, the n-pass is the first pass of 4-pass printing and the m-pass is the fourth pass of 4-pass printing. However, the number of passes that can be used in the present invention is not limited to 4 passes, It is sufficient if it is 3 passes or more. In addition, it is preferable to use the first and last paths from the viewpoint of increasing the enlargement rate of conveyance deviation, but it is sufficient to use at least two paths or more. The maximum number of passes used for conveyance deviation detection pattern printing need not be the upper limit of the maximum number of printing passes used for printing on the main body.
[0051]
FIG. 10 shows an example of a mask pattern 90 for detecting transport deviation stored in the mask memory unit 110b. The mask pattern 90 is for forming a linear image extending in the head scanning direction as a conveyance deviation detection print pattern, and has a size of 1280 dots × 512 dots. The vertical length of 1280 dots corresponds to the total number of nozzles in the head. The entire area of the mask pattern is equally divided into four lines for 4-pass printing, and each line is divided into two equal parts. Only the left-side area 91 of the first pass and the right-side area 92 of the fourth pass which are divided in this way are set as non-mask areas, and the other areas are set as mask areas. However, the non-mask areas of the areas 91 and 92 do not necessarily require that all dots in the areas be in an unmasked state. The mask patterns in the first pass and the fourth pass have a complementary relationship, but the mask patterns in the region 91 and the region 92 may be the same. (The types of hatches in the figure are merely to represent differences in the paths.) The mask patterns of the regions 91 and 92 may be all-dot non-masks or have a predetermined density (for example, 50). %) Halftone mask. As print image data, if this mask pattern is used to print a so-called solid image with all dots ON corresponding to a 1/4 band corresponding to the carry amount for one pass, using this mask pattern, the print head will follow the scanning direction of the print head. An extending linear image (length 320 × width 256 dots) is obtained. However, when there is a conveyance shift, the first divided portion and the second divided portion of the image are shifted up and down. That is, the left-side area 91 for the first pass and the right-side area 92 for the fourth pass correspond to the first and second divided portions of the linear image extending in the scanning direction of the print head. In the example of FIG. 10, the entire areas 91 and 92 are used for outputting a linear image, but only a part thereof (for example, only a height corresponding to several vertical dots) may be used. That is, the thickness of the “linear image” is arbitrary within the range of the area width of ¼ pass. In that case, it is necessary to match the positions in the areas 91 and 92.
[0052]
By using the mask pattern for detection of conveyance deviation as shown in FIG. 10 and printing in the same manner as normal printing, the printing pattern for detection of conveyance deviation as shown in FIG. 7 can be printed easily. Further, by using this conveyance deviation detection mask pattern while changing the correction value step by step, a conveyance deviation detection print pattern as shown in FIGS. 8 and 9 can be printed.
[0053]
Next, another example of the mask pattern for detection of conveyance deviation stored in the mask memory unit 110b will be described as the second embodiment of the present invention. The configuration of the plotter body is the same as that of the first embodiment. The method for printing the conveyance deviation detection print pattern by enlarging the conveyance deviation is the same.
[0054]
FIG. 11 shows a configuration example of a mask pattern 70 for detecting transport deviation used in the present embodiment. In contrast to the mask pattern 70 of FIG. 10 in the first embodiment, the mask pattern 70 represents a paper feed shift by a linear image (horizontal line) extending in the head scanning direction (horizontal direction). In this embodiment, the paper feed deviation can be expressed by a surface. In this mask pattern, the entire area is divided into four equal areas corresponding to four passes, and the areas in each line are divided into equal four columns. In the example of the figure, each column constitutes a character print area 71, a reference area 72, a comparison area 73, and a reference area 74. The height of one row is 320 dots, and the width of one column is 128 dots. The hatched portion in the figure is a non-mask area. However, as described above, even if it is a non-mask region, it is not necessary to be in an undotted state of all dots in the region. Here, a region that is important for the purpose of conveyance deviation detection is the comparison region 73. The comparison area 73 is further equally divided into four rows inside. The height of each row is 80 dots. The divided parts 731 and 732 correspond to the first divided part in the present invention, and the divided parts 733 and 734 correspond to the second divided part. Other areas other than the comparison area 73 are not necessarily required, but by providing the reference area 72 adjacent to at least one side in the horizontal direction with respect to the comparison area 73, this is caused by a conveyance shift in the comparison area 73. Recognition of image unevenness is facilitated. In the illustrated example, two reference regions 72 and 74 are provided so as to sandwich the comparison region 73 from both the left and right sides. In the example of FIG. 11, a character print area 71 is further provided in each line. This position is the top position of the line in the figure, but is not limited to this. For example, it may be the last position in the line. This character area 71 is used to print an identifier (here, a number) representing the correction value when printing a plurality of conveyance deviation detection print patterns whose correction values are changed in stages. In this case, the print data used for the character area 71 is not solid images but font data representing the identifier. For the reference areas 72 and 74 and the comparison area 73, a so-called solid image of all dots ON for ¼ band corresponding to the carry amount for one pass is used.
[0055]
When the printing pattern for transport deviation detection is printed using the mask of FIG. 11, the reference areas 72 and 74 form an image in one pass, so that the pattern becomes uniform. On the other hand, the comparison region is formed so that the first pass and the fourth pass are combined to form a uniform pattern. Therefore, a uniform pattern cannot be formed if there is a conveyance shift.
[0056]
FIG. 12 and FIG. 13 show enlarged print examples schematically showing only the comparison part of the conveyance deviation detection print pattern when the correction value is changed stepwise. In the figure, the hatched portion is an area printed in the first pass, and the vertical hatched portion is an area printed in the fourth pass. Here, a case where there is no conveyance deviation is shown. That is, the image density in the comparison area is uniform with the correction value 0. It can be seen that when the correction value is other than 0, overlap and separation of the planar images occur, and this is image unevenness. When there is a conveyance deviation, image unevenness is eliminated with respect to a printing pattern having a correction value corresponding to the deviation amount. Therefore, the correction value of the print pattern without image unevenness becomes the target correction value.
[0057]
FIG. 14 shows an example in which a plurality of conveyance deviation detection print patterns are printed using the conveyance deviation detection mask pattern shown in FIG. Here, the correction value is changed stepwise from −4 to +4. Here, a case where there is no conveyance deviation (correction value 0, uniform density) is shown. In this figure, “correction value switching timing” is not shown, but it is the same as FIG. 8 and FIG.
[0058]
Although it is easy to visually check the appropriate correction value for such a conveyance deviation detection print pattern, a sensor that can detect the print density is attached to the carriage, etc., and the print area is scanned to obtain the optimum correction value for density comparison. It is also possible to determine automatically.
[0059]
In addition, in the adjustment method according to the present invention, when adjustment is performed by complementing the images of the first pass printing and the last pass printing, carriage scanning (and printing by the head) between the passes is unnecessary, so the middle The printing time can be shortened by only feeding the paper and omitting the carriage scanning.
[0060]
The preferred embodiments of the present invention have been described above, but various modifications and changes can be made without departing from the scope of the claims. For example, although the plotter has been described, the present invention can be applied to any image forming apparatus having a multipass printing function. In addition, specific various numerical values, numbers, orders, and the like in the above-described embodiments are merely examples, and the present invention is not necessarily limited thereto. The print patterns shown in FIGS. 8, 9, and 14 may be repeatedly formed in the head scanning direction.
[0061]
【The invention's effect】
According to the present invention, a conveyance pattern for detecting a conveyance deviation is divided into a first divided portion and a second divided portion, and printing is performed in separate passes that are separated by two or more passes. It is possible to print with an enlarged shift. This makes it easier to obtain a more appropriate conveyance deviation correction value whether visually or automatically.
[0062]
Further, by using a mask function for multi-pass printing built in the inkjet image forming apparatus, printing of a conveyance deviation detection print pattern can be easily performed.
[0063]
Further, if the printing material is only transported without performing the carriage operation from the printing of the first divided portion to the printing of the second divided portion, the printing time of the printing pattern for detecting the conveyance deviation is shortened. You can also.
[0064]
Furthermore, printing is performed with several nozzles in the most upstream area in the paper conveyance direction of the nozzle array of the head, and after the paper has been conveyed for several passes, it is complemented with the image previously printed with several nozzles in the most downstream area of the nozzle array of the head. By printing in this way, if there is a conveyance deviation, it can be enlarged and confirmed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of a plotter according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of control hardware of the plotter shown in FIG.
FIG. 3 is an explanatory diagram of four-pass printing using a single ink color head.
4 is a schematic completed print of one band corresponding to the nozzle width of the head of the plotter of FIG.
5 is a diagram for explaining a printing procedure for performing multi-pass printing for one band shown in FIG. 4; FIG.
FIGS. 6A and 6B are diagrams for explaining examples (a) and (b) in which the first-pass image (first divided portion) and the second-pass image (second divided portion) are shifted in the paper transport direction.
FIG. 7 is an explanatory diagram of a transport misalignment print pattern for printing with enlarged transport misalignment according to the first embodiment of the present invention.
8 is a diagram showing a printing result of the conveyance deviation detection print pattern of FIG. 7 when the correction amount in the conveyance direction is changed stepwise (from −2 to +2) based on the unit correction amount. .
9 is a diagram illustrating a printing result of a conveyance deviation detection print pattern corresponding to FIG. 8 when there is a conveyance deviation. FIG.
10 is a diagram showing an example of a mask pattern for detection of conveyance deviation stored in the mask memory unit 110b of FIG.
FIG. 11 is a diagram illustrating a configuration example of a transport deviation detection mask pattern used in the second embodiment of the present invention.
FIGS. 12A and 12B are print examples (a), (b), (c), and (d) schematically illustrating only an enlarged comparison part of the print pattern for detecting transport deviation in FIG. 11 when the correction value is changed stepwise. It is a figure which shows (e).
13 is a diagram illustrating print examples (a), (b), (c), and (d) schematically illustrating only a comparison portion of a print deviation detection print pattern with a correction value different from that in FIG. 12; FIG.
FIG. 14 is a diagram illustrating an example in which a plurality of conveyance deviation detection print patterns are printed using the conveyance deviation detection mask pattern shown in FIG. 11 and changing correction values in a plurality of stages.
[Explanation of symbols]
10 Plotter
20 Carriage
22, 22K, 22C, 22M, 22Y Print head
70, 90 Mask pattern for detection of conveyance deviation
101a, 101b mask memory section
102 Print controller
105 Main scanning motor
107 Memory control unit
109 Data mask part
113 Head control signal generator
114 Main scanning motor control signal generator
115 CPU
117 Sub-scanning motor control signal generator
118 Sub-scanning motor (conveyance motor)

Claims (2)

An ink jet that causes a print head for ejecting ink to scan a predetermined area of a printing material a plurality of times and conveys the printing material by a width of the predetermined area between the scans to form an image In the image forming apparatus,
Wherein there is provided a method of printing a conveyance deviation detection printing pattern for detecting a conveyance deviation of the print material,
The first divided portion and the second divided portion are formed on the print head by three or more scans of the print head and the conveyance of the printing material performed between the scan of the print head and three or more times. A first step of forming the conveyance deviation detection print pattern which is shifted in the scanning direction;
The first step is repeated with different amounts of conveyance of the printing material to be performed for three or more scans of the print head, and the first divided portion and the second divided portion are A second step of forming a plurality of the conveyance deviation detection print patterns having different relative deviation amounts with respect to the conveyance direction of the printing material,
In the first step, the print head is scanned three times or more between the scan of the print head forming the first divided portion and the scan of the print head forming the second divided portion. In a scan other than the scan of the print head that forms the first divided portion and the scan of the print head that forms the second divided portion by interposing the conveyance of the printing material performed several times during A printing pattern printing method for detecting a conveyance deviation, wherein recording is not performed . Of the three or more scans of the print head forming the first divided portion and the second divided portion, the first divided portion is formed by the first scan, and the second divided portion is formed by the last scan. The printing pattern printing method for transport deviation detection according to claim 1, wherein divided portions are formed.

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