JP2019119052A - Discharge setting method, data processing apparatus, inkjet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ejection setting method, a data processing device and an inkjet recording apparatus capable of setting an ink ejection setting capable of outputting an image with an appropriate image quality more effectively in a line head. A method for setting ejection of ink from each of nozzles in a line head having a plurality of head modules and having nozzles 27 partially overlapping in a predetermined width direction between the head modules. A step of performing halftone processing using the dither matrix 53 to generate halftone data, and ejecting ink from each nozzle using the distribution matrix 54 for each dot position in the overlapping region of the nozzle arrangement range in the halftone data. The spatial frequency intensity peak of the distribution matrix is lower than the spatial frequency intensity peak of the dither matrix, including the step of determining the presence or absence. [Selection diagram] Fig. 3

Description

  The present invention relates to an ejection setting method, a data processing apparatus, and an inkjet recording apparatus.

  There is an inkjet recording apparatus which ejects ink from a nozzle onto a medium to record an image or the like. In the inkjet recording apparatus, an image is recorded by performing halftone processing on image data to control the presence or absence of discharge from each nozzle and the discharge amount.

  In an inkjet recording apparatus, high speed is achieved by discharging ink from the plurality of recording heads while transporting the medium in a direction intersecting the width direction to a line head in which the plurality of recording heads are arranged in a predetermined width direction. There is a technology to record an image on The distance between the nozzles is very narrow, on the order of tens to hundreds of micrometers. Therefore, in this line head, it is difficult to assemble a plurality of recording heads with exact positional relationship. However, when the nozzle spacing becomes non-uniform at the joint of the recording head, there is a problem that the image quality is deteriorated at the joint. On the other hand, there is a technique of defining a dither matrix relating to halftone processing so as to compensate for the deterioration of the image quality at the joints of the recording head (Japanese Patent Application Laid-Open No. 2001-147118).

JP, 2009-18479, A

  However, the dither matrix is appropriately set to reduce artifacts and the like in the output image. Therefore, when trying to make both effects compatible in one dither matrix, there is a problem that the image as a whole becomes an average image and the effects are not sufficient for each.

  The object of the present invention is to provide an ejection setting method, a data processing apparatus and an inkjet recording apparatus capable of performing ink ejection setting capable of outputting an image with more appropriate image quality more effectively at both joints of a recording head and non-joints. It is to do.

In order to achieve the above object, the invention according to claim 1 is
In a line head having a plurality of head modules in which nozzles are arranged at different positions in a predetermined width direction, and the arrangement range of the nozzles in the adjacent head modules in the width direction is partially overlapped in the width direction A discharge setting method related to the ink discharge from each of the nozzles, wherein
Halftone processing is performed on the multi-gradation data using the first matrix that determines the presence or absence of ink ejection for each dot position based on the threshold value corresponding to the gradation value of the multi-gradation data to generate halftone data Halftone processing step,
Ink discharge from each of the nozzles using a second matrix that distributes which nozzle is to be used to discharge ink to each dot position in the overlapping area of the arrangement range among the generated halftone data Distribution step to determine presence or absence,
Including
The intensity peak of the spatial frequency according to the second matrix is set lower than the intensity peak of the spatial frequency according to the first matrix.

The invention according to claim 2 is the discharge setting method according to claim 1.
The halftoning step is
A process setting step of determining, for each dot area corresponding to the gradation value, a setting ratio between the threshold and the predetermined plural stages of ink ejection amounts corresponding to the ink ejection rate corresponding to the gradation value;
A discharge amount setting step of determining the discharge amount of the ink for each dot position determined to discharge the ink based on the set ratio determined;
Including
The setting ratio is set such that the ink ejection rate is equal to or less than a predetermined value less than 100%.

The invention according to claim 3 is the discharge setting method according to claim 2.
In the halftoning step, the setting of the threshold value and the setting ratio according to the ink ejection rate corresponding to the gradation value is selected according to the medium to which the ink is to be ejected from among a plurality of predetermined types. It features.

In the invention according to claim 4, in the discharge setting method according to claim 2 or 3,
In the distribution step, distribution is performed on a range of a predetermined number of dot positions of 100 or less in the width direction in the overlapping region, and it is characterized by selectively determining from which nozzle the ink is to be ejected. Do.

In the invention according to claim 5, in the discharge setting method according to any one of claims 1 to 4,
The medium to be subjected to the ink discharge includes a cloth.

In the invention according to claim 6, in the discharge setting method according to any one of claims 1 to 5,
The halftoning step may be performed using a dither method.

The invention according to claim 7 is the discharge setting method according to any one of claims 1 to 6,
The intensity peak of the spatial frequency according to the first matrix and the intensity peak of the spatial frequency according to the second matrix are each determined isotropically.

The invention according to claim 8 is
In a line head having a plurality of head modules in which nozzles are arranged at different positions in a predetermined width direction, and the arrangement range of the nozzles in the adjacent head modules in the width direction is partially overlapped in the width direction A setting unit configured to perform discharge setting relating to ink discharge from each of the nozzles;
The setting unit is
Halftone processing is performed on the multi-gradation data using the first matrix that determines the presence or absence of ink ejection for each dot position based on the threshold value corresponding to the gradation value of the multi-gradation data to generate halftone data And
Ink discharge from each of the nozzles using a second matrix that distributes which nozzle is to be used to discharge ink to each dot position in the overlapping area of the arrangement range among the generated halftone data Determine the presence or absence
The data processing apparatus is characterized in that an intensity peak of spatial frequency according to the second matrix is set lower than an intensity peak of spatial frequency according to the first matrix.

The invention according to claim 9 is
A data processing apparatus according to claim 8;
Said line head,
An inkjet recording apparatus comprising:

  According to the present invention, it is possible to perform the ink discharge setting capable of outputting an image with an appropriate image quality more effectively at both the seams and the non-seams of the recording head.

FIG. 1 is an overall perspective view of an inkjet recording apparatus. It is a bottom view showing the field which counters the conveyance side of a head unit. FIG. 2 is a block diagram showing a functional configuration of the inkjet recording apparatus. 5 is a flowchart showing a control procedure by a control unit of drive image conversion processing executed by the inkjet recording apparatus. It is a figure explaining gradation dot corresponding information. It is the figure which showed the spreading | diffusion of the ink on a cloth typically. It is a figure explaining the characteristic of a dither matrix and a distribution matrix. FIG. 6 is a view showing an example of ink discharge setting of each nozzle in each head module determined by halftone processing and distribution processing. FIG. 6 is a diagram showing an example of ink landing positions when ink is ejected from the two head modules distributed. It is a figure which shows the example of the setting of the distribution rate in a duplication area | region.

Hereinafter, embodiments of the present invention will be described based on the drawings.
FIG. 1 is an overall perspective view of an inkjet recording apparatus 100 according to an embodiment of the present invention.

  The inkjet recording apparatus 100 has a plurality of line heads and can eject a single-pass ink to perform recording of a color image. The inkjet recording apparatus 100 includes a conveyance unit 10, an image recording unit 20, and the like. , An ink storage unit 30, a control unit 40 (see FIG. 3), and the like.

  The conveyance unit 10 includes a drive roller 11, a conveyance drive unit 12, a conveyance belt 14, and the like. The conveyance drive unit 12 includes a rotation motor that causes the drive roller 11 to rotate at a predetermined speed. The endless conveyance belt 14 is wound around the driving roller 11 together with a driven roller (not shown), and the conveyance belt 14 is circularly moved by the rotation of the driving roller 11. The recording medium is placed on the conveyance surface with the outer surface of the conveyance belt 14 as the conveyance surface, and the recording medium is conveyed in the conveyance direction as the conveyance belt 14 circulates. The recording medium is not particularly limited, but here, the wound long fabric is sequentially fed out and conveyed. The type of the fabric is not particularly limited, such as cotton, wool, polyester, etc., and various types can be used.

  The image recording unit 20 includes a carriage 22, a carriage elevating unit 23, and the like, and the combination of the carriage 22 and the carriage elevating unit 23 is provided in a number (here, eight) according to the number of ink colors (plural colors). ing. The carriages 22 respectively extend in a direction intersecting the conveyance direction (x direction) of the recording medium by the conveyance unit 10, here, in a width direction (y direction) orthogonal to that of the conveyance surface of the recording medium by the conveyance unit 10 A plurality of head units 21 are fixed so as to be able to eject ink droplets from the openings of the nozzles over the entire width of the recording medium which is disposed above (z direction) and transported to form a line head structure. The number of nozzles of each head unit 21 is appropriately determined according to the recording resolution, the size of the recording head 211, and the like. The plurality of carriages 22 are provided at mutually different positions in the transport direction. The carriage 22 is provided so as to be capable of changing the distance from the transport surface upward (in the direction of moving away) by the carriage lifting unit 23. The distance from the transport surface of the head unit 21 is also changed as the carriage 22 moves.

The carriage elevating unit 23 changes the distance from the transport surface of the carriage 22. The carriage lifting unit 23 includes a lifting motor 232, an electromagnetic brake 233, a beam member 234, a support portion 235, and the like.
Two beam members 234 are provided substantially in parallel in the direction (here, the direction orthogonal to the transport direction, that is, the width direction) intersecting the transport direction on the upper portion (the transport surface side of the recording medium) of the transport belt 14. Support parts 235 are fixed to both ends respectively. A lift motor 232, an electromagnetic brake 233 and a carriage 22 are attached to the support portion 235.
The carriage 22 is moved up and down according to the operation of the lift motor 232 and the electromagnetic brake 233 driven based on the control signal from the control unit 40 (see FIG. 3), and the position is determined.

  The elevation motor 232 moves the carriage 22 at a predetermined elevation speed. As the elevation motor 232, for example, a servomotor or a stepping motor is used.

  The electromagnetic brake 233 maintains the fixed state of the carriage 22. When the fixed state is released according to the drive signal, the movement of the carriage 22 by the lift motor 232 is temporarily enabled. That is, in the normal state including the time of power supply disconnection, the electromagnetic brake 233 fixes the carriage 22. For example, a disc brake is used as the electromagnetic brake 233.

  The ink storage unit 30 stores the ink of each color used for image recording, and supplies the ink to the recording head 211. The ink storage unit 30 includes an ink tank 31 and a rack 32 for exclusive use, and the ink tank 31 is connected to the image recording unit 20 through a pipe such as a tube. The ink storage unit 30 is not particularly limited, but for example, inks of a plurality of colors (here, eight colors) including C (cyan), M (magenta), Y (yellow) and K (black) are ink tanks respectively. 31 are supplied to the recording heads 211 attached to the carriages 22 respectively. The color and type of the ink connected and supplied to the recording head 211 may be replaceable.

  FIG. 2 is a bottom view showing the surface of the ink jet recording apparatus 100 according to the present embodiment, the surface facing the transport surface of the head unit 21. As shown in FIG.

  As shown in FIG. 2A, on the bottom of the head unit 21, eight head modules 210 are arranged in a zigzag form. The head modules 210 each have two recording heads 211. At the bottom of each recording head 211, nozzle openings 27a (nozzles) are arranged in a staggered pattern at different positions in the width direction such that the spacing is twice the predetermined nozzle spacing dp. The two recording heads 211 in each head module 210 are arranged with a gap between the nozzles in the width direction, and the plurality of nozzle openings 27 a (nozzles) have a nozzle spacing dp in the width direction in the entire head module 210. It is arranged (arranged) as different positions.

  As shown in FIG. 2B, in the nozzle arrangement range in which the nozzle openings 27a are arranged in each head module 210, partial overlap is made in the width direction between the head modules 210 adjacent in the width direction. is there. That is, in this overlapping portion (overlapping region), one nozzle opening belonging to each of the two head modules 210 with respect to the same position in the width direction (dot position, which may actually include minute relative positional deviation) The ink can be discharged from 27a. As described later, in this overlapping portion, distribution is performed such that ink can be ejected from any of the nozzles.

Next, the functional configuration of the inkjet recording apparatus 100 according to the present embodiment will be described.
FIG. 3 is a block diagram showing the functional configuration of the inkjet recording apparatus 100. As shown in FIG.
The inkjet recording apparatus 100 includes a control unit 40 (setting unit, data processing apparatus), a storage unit 50, a communication unit 60, and a display / operation reception unit 70 in addition to the above-described transport drive unit 12 and image recording unit 20. And the bus 90 etc.

  The image recording unit 20 includes a plurality of nozzles 27, a head drive unit 25 that discharges ink from the plurality of nozzles 27, a carriage drive unit 24, and the like.

  The carriage drive unit 24 outputs a drive signal to the electromagnetic brake 233 and the lift motor 232 according to the control signal from the control unit 40 to loosen the electromagnetic brake 233 and operate the lift motor 232 to move the carriage to a desired position. Or stop the lift motor 232 and fix the carriage by the electromagnetic brake 233.

  The head drive unit 25 operates the mechanism that applies pressure to the ink in the ink flow path that receives the supply of the ink from the ink tank 31 and communicates with the nozzles 27 to flow the ink. For example, the head drive unit 25 generates and outputs a drive voltage signal to a piezoelectric element that deforms a wall surface of a pressure chamber provided in the ink flow path. The head drive unit 25 selects a voltage waveform pattern stored in advance based on a control signal from the control unit 40, generates a drive voltage signal obtained by power amplification, and generates each according to the image data input from the storage unit 50. Whether to output the drive voltage signal to the piezoelectric element is switched. Due to the deformation of the piezoelectric element, the pressure chamber is deformed and pressure fluctuation is applied to the ink in a predetermined pattern, and accordingly, a desired amount of ink droplets are ejected from the nozzle opening 27a at a desired speed. Here, the storage unit 50 stores a plurality of voltage waveform patterns and amplitude settings of the drive voltage such that the amount of ink droplets to be ejected can be changed into a plurality of steps, for example, three steps.

  The control unit 40 controls the overall operation of the inkjet recording apparatus 100 and controls the operation of each unit. The control unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), and the like.

  The CPU 41 performs various arithmetic processing, and controls conveyance of a recording medium in the inkjet recording apparatus 100, supply of ink, discharge of ink, maintenance operation, and the like. Further, the CPU 41 performs various processes related to image recording based on image data, status signals of respective units, clock signals, and the like according to a program read from the storage unit 50.

  The RAM 42 provides a working memory space to the CPU 41 and stores temporary data. The RAM 42 may include a non-volatile memory, and the data stored in the non-volatile memory and the data stored in the storage unit 50 are appropriately allocated.

  The storage unit 50 stores job data related to image recording acquired from the outside via the communication unit 60, control programs related to various control operations of the control unit 40, setting data, and the like. As a configuration for temporarily storing job data and its processing data, a DRAM is mainly used, and as a configuration for storing control programs and setting data, an HDD (Hard Disk Drive), a non-volatile memory, etc. are used. It is not limited to. For example, job data may be stored in a non-volatile memory, and an initial program, initial setting data and the like may be stored in a mask ROM which can not be rewritten and updated. The control program includes a conversion processing program 51 that converts image data acquired as job data into driving image data for each nozzle.

  Further, in the data stored in the storage unit 50, the gradation dot correspondence information 52 referred to when executing the conversion processing program 51, the dither matrix 53 (first matrix) and the distribution matrix 54 (second matrix) are included. included. In each of the dither matrix 53 and the distribution matrix 54, one natural number equal to or less than the number of elements is arranged in a predetermined pattern for each element of the predetermined number of matrices.

  The communication unit 60 is a communication interface that controls communication operation with an external device. As the communication interface, for example, one or more corresponding to various communication protocols such as a LAN card are included. The communication unit 60 acquires image data to be recorded and setting data (job data) related to image recording from an external device based on control of the control unit 40, and transmits status information and the like to the external device. Can.

  The display / operation reception unit 70 displays a status of the inkjet recording apparatus 100, an operation menu, and the like as a display unit according to a control signal from the control unit 40. In addition, the display / operation reception unit 70 receives an operation of the user as an operation reception unit and outputs the operation to the control unit 40. The display / operation reception unit 70 has, for example, a touch sensor as the operation reception unit, and has a display screen such as a liquid crystal screen provided to overlap with the touch sensor as the display unit. The control unit 40 causes the display screen to display various menus and the like for receiving an instruction by the status and the touch sensor. The control unit 40 associates the information of the contents and the position of the displayed menu with the information of the type and the position of the touch operation of the user accepted as the operation accepting unit, and executes the processing according to the operation. A control operation to be performed by each part of 100 is performed. In addition to these, the display / operation reception unit 70 may include an LED lamp or the like as a display unit, and may include a push button switch, a numeric keypad, or the like as an operation reception unit.

  The bus 90 is a signal transmission path electrically connected between the control unit 40 and each of the above-described configurations to exchange signals.

  Next, an image recording operation in the inkjet recording apparatus 100 will be described.

  Here, the image data included and acquired in the job data has multi-valued (for example, 256 gradations) density gradations for each color such as RGB or CMYK at each pixel position determined according to the image resolution. The value is defined data. The control unit 40 converts the image data into driving data for each nozzle and outputs the data to the head driving unit 25 so as to eject ink from the nozzles 27 set as the driving target at an appropriate timing.

  In the inkjet recording apparatus 100 of the present embodiment, when recording an image, no ink is ejected, ejection of small droplets, ejection of medium droplets having a larger appropriate amount of liquid than small droplets, to each nozzle 27 as driving data. One of four types of large droplets having a larger amount of liquid volume than the middle droplets is selected and set.

  FIG. 4 is a flowchart showing a control procedure by the control unit 40 of the drive image conversion process executed by the inkjet recording apparatus 100. The drive image conversion process included in the conversion process program 51 is started when an image recording command related to job data is acquired.

  When the drive image conversion process is started, the control unit 40 divides the image data included in the job data into color gradation data of each ink color that can be ejected from the image recording unit 20 (step S101). If the image data and the ink color can not be simply divided, for example, in the case of a combination of different colors, the control unit 40 converts the image data into data of color tone values of each color according to the ink color. I do. The control unit 40 refers to the gradation dot correspondence information 52 described in detail later, and acquires the correspondence between the predetermined gradation value, the threshold value, and the ratio. The control unit 40 responds to the tone value for each setting area (dot area corresponding to a certain tone value, corresponding to the above-mentioned pixel area) related to halftone processing according to each color tone data (multi-tone data). Set a threshold value for binarization, and set a ratio (setting ratio) among small droplets, medium droplets, and large droplets (ink discharge amounts in a plurality of stages) for each setting region (step S102; Process setting step).

The control unit 40 refers to and applies the dither matrix 53 to separately halftone process the image data of each color with a threshold value set using the dither method to generate halftone data (step S103). The control unit 40 discharges the ink, and compares the threshold value with the value of each element of the dither matrix 53 for each dot position where the ink lands. When the element value is equal to or more than the threshold value, it is determined that the ink is discharged. If is less than the threshold value, it is determined that there is no ink discharge by not discharging ink. Thereby, the image data is converted into binary data relating to the presence or absence of the discharge of the ink to each dot position. The control unit 40 determines the ink ejection amount (large droplet, medium droplet, small droplet) for each dot position set to be ejected in accordance with the ratio between the set ink ejection amounts, ie, four values, ie, The 2-bit data is set (step S104; discharge amount setting step). The relationship between binary values and the presence or absence of ink ejection and the correspondence relationship between quaternary values and droplet sizes are separately determined.
The processes of steps S102 to S104 constitute a halftone process step of the drive image conversion process which is an embodiment of the discharge setting method.

  The control unit 40 refers to the distribution matrix 54 to select any head for each dot position for the overlapping portion of the nozzle arrangement range of the head module 210 in the generated 2-bit image data (halftone data) of each color. Whether ink is to be ejected from the nozzles of the module 210 is distributed, and the nozzles for ejecting the ink are determined (step S105; distribution step). The control unit 40 compares the threshold according to the distribution ratio with the value of each element of the distribution matrix 54 for each dot position where ink is ejected, and corresponds to the dot position if the value of the element is equal to or more than the threshold The ink is ejected from the nozzle of one head module 210, and when the value of the element is less than the threshold value, the ink is ejected from the nozzle 27 of the other head module 210 corresponding to the dot position. Thereby, the control unit 40 generates drive image data for each nozzle for each head module 210 of each head unit 21.

  The control unit 40 sends the generated driving image data to the head driving unit 25 at a timing according to the conveyance speed of the recording medium and the ink ejection interval in the conveyance direction for each predetermined line (for example, every line) in the conveyance direction. It outputs (step S106). Then, the control unit 40 ends the driving image conversion process.

FIG. 5 is a diagram for explaining the gradation dot correspondence information 52. As shown in FIG.
The coverage area of the ink in the recorded image, that is, the number of ejected dots per unit area increases as the density gradation value (tone value) set in the image data increases. The ratio of the number of ejected dots to the total number of dots (ink ejection rate) is determined according to the magnitude of the threshold with respect to the dither matrix 53 described above. Further, when the density gradation value is low, the ejection dot is composed of only small droplets, but the proportion of large droplets increases as the density gradation value increases. Therefore, the number of ejected dots (threshold value) does not simply increase in proportion to the density gradation value.

  In the inkjet recording apparatus 100 according to the present embodiment, in the gradation dot correspondence information 52, a plurality of such correspondence relationships are held. As compared with the correspondence 1 shown in FIG. 5 (a), in the correspondence 2 shown in FIG. 5 (b), the transition to a droplet of a size larger than that of the increase in density gradation value is faster. . That is, in the correspondence relationship 2, the increase in the number of ejected dots in the low gradation to medium gradation region is small, and the ratio to the maximum number of ejectable dots is less than 100% until all the ink ejections become large droplets. The density gradation is expressed with a small number of dots in a range which is equal to or less than the predetermined value Rth (70%, for example, as a value taking into consideration the occurrence of overlap between ink immediately after landing). The gradation dot correspondence information 52 stores information related to the threshold according to the ink ejection rate to the density gradation value and the ratio between the ink ejection amounts (between large droplets, medium droplets, and small droplets). Be done.

FIG. 6 is a view schematically showing the spread of the ink on the fabric.
In the case of a fabric, the landed ink, particularly dye-based ink, tends to dust and spread around while rapidly penetrating inside. When the number of ejected dots per unit area is large, as shown in FIG. 6A, the ink droplets adjacent to each other immediately after landing on the recording medium overlap, so that they are provided at different positions particularly in the transport direction. When ink droplets land at different timings from the nozzles, uniform penetration is adversely affected to cause unevenness such as black streaks, and image quality is likely to deteriorate. On the other hand, as shown in FIG. 6B, if the number of ejected dots is decreased to increase the appropriate amount of each droplet, it becomes difficult to overlap between adjacent ink droplets immediately after landing, and then the fabric is used as a fabric. Since the infiltrated ink will overlap at the spreading stage, it is difficult to cause deterioration of the image quality associated with such unevenness. The surface area of the ink immediately after landing depends on the type of recording medium, particularly in the case of a fabric, the yarn direction, density, material and the like, but it tends to spread mainly along the direction in which the yarn density is higher.

  The control unit 40 may select from among a plurality of types of correspondence relationships held in the gradation dot correspondence information 52 in accordance with the type of the recording medium (medium of ink discharge target). That is, when the recording medium is a fabric, one having a predetermined value Rth lower than the correspondence applied to ordinary paper, coated paper or the like is selected, and three or more kinds of correspondence are maintained. Further, ones having different predetermined values Rth may be selected according to the type of fabric. The information related to the type of recording medium may be included in job data, or may be set based on an input operation to the display / operation reception unit 70.

FIG. 7 is a diagram for explaining the characteristics of the dither matrix 53 and the distribution matrix 54. As shown in FIG.
As described above, the control unit 40 performs halftone processing by dithering using the dither matrix 53. Further, the distribution matrix 54 is used to distribute the discharge nozzles in the overlapping portion. That is, although the dither matrix 53 and the distribution matrix 54 are matrices having similar numerical arrangement characteristics, the numerical arrangement is set separately.

  The dither matrix 53 is a colored noise, for example, a blue noise, and in particular, a peak of the spectral intensity of the frequency (spatial frequency) related to the spatial structure on the high frequency side ) Is included. When such dither matrix 53 is applied and halftone processing is performed, for example, as shown by the spatial frequency characteristic of FIG. 7A, the obtained halftone image has a spatial frequency corresponding to the intensity peak. It becomes an image having characteristics (here, a peak of spectral intensity at about 90 cycles per cm). As a result, conversion to a halftone image of natural image quality is performed, such as suppression of a feeling of roughness likely to occur due to white noise and the like.

  On the other hand, the distribution matrix 54 is determined so that the intensity peak of the spatial frequency is lower than the dither matrix 53. This peak is defined in the range of spatial wavelengths shorter than the spatial wavelength at which human beings can discriminate the structure. Thereby, the distribution of the ink ejection presence / absence finely distributed by the dither matrix 53 is, for example, as shown by the spatial frequency characteristic of FIG. A mass of a plurality of nozzle units is distributed to any of the head modules 210 so as to have a peak of spectral intensity. That is, ink ejection to a plurality of adjacent dot positions can be easily allocated to one head module 210 collectively.

  The dither matrix 53 and the distribution matrix 54 can be determined such that the frequency of the peak of the spectral intensity related to the distribution of ink ejection becomes a non-integer multiple of the frequency of the peak of the spectral intensity related to the distribution. Here, although the spatial frequency related to the dither matrix 53 and the spatial frequency related to the distribution matrix 54 (at least the frequency of the intensity peak) are determined isotropically, they may have anisotropy. In the case of having anisotropy, the intensity peak of the spatial frequency related to the presence or absence of ink ejection may be determined on the higher frequency side than the intensity peak of the spatial frequency related to the distribution destination for each direction component.

FIG. 8 is a view showing an example of ink discharge setting of each nozzle in each head module 210 determined by halftone processing and distribution processing.
As shown in FIG. 8A, the presence or absence of ink ejection is determined for each dot position according to the dither matrix 53 by the threshold value determined according to the predetermined density gradation (step S103). Next, as shown in FIG. 8B, the droplet size in each of the ink discharge nozzles is determined at a ratio determined according to the predetermined density gradation (step S104).

  As shown in FIGS. 8C and 8D, the presence or absence of ink discharge from the nozzles in each head module 210 is distributed according to the distribution matrix 54 (step S105). As a result, in the overlapping area, the original head module 210 that discharges ink for each block based on the spatial frequency of the distribution matrix 54 is switched.

FIG. 9 is a view showing an example of the ink landing position when ink is ejected from the two distributed head modules 210.
Even if there is a relative misalignment between the two head modules 210 (which is drawn here in an exaggerated manner and can actually be adjusted to a smaller relative misalignment), at each head module 210 The discharge range is set as a mass, and positional displacement occurs for each mass. In other words, relative displacement does not occur in the mass. As a result, there is no relative position shift at high frequency (short wavelength), so that occurrence of a situation where an artificial pattern (artifact) corresponding to such position shift is visually recognized is suppressed. In addition, the occurrence position of relative positional deviation between adjacent ink dots is reduced. That is, by such two-stage filtering processing, it is possible to suppress the deterioration of the image quality subjected to the halftone processing with a preferable image quality.

  The ratio of allocation to each head module 210 in the overlapping area may be sequentially switched depending on which head module 210 is closer to the end.

FIG. 10 is a diagram showing an example of setting of the distribution rate in the overlapping area.
As shown in FIG. 10A, in the vicinity of the end of the head module 210a, the ratio (distribution ratio Ra) of the nozzles to be distributed as ink discharge from the nozzles of the head module 210a is determined to be smaller. The distribution ratio Ra increases as the center of the head module 210a is approached. Similarly, near the end of the head module 210b, the distribution ratio Rb of the nozzles for ejecting ink in the head module 210b is small, and the distribution ratio Rb increases as it approaches the center of the head module 210b. As a result, the influence of the difference in the characteristics relating to the ink ejection between the head modules 210 and the relative positional deviation is smoothly transferred.

  Note that there is no need to distribute to the nozzles of both head modules 210 in the entire overlapping region, and as shown in FIG. 10B, the number of nozzles in the width direction and a part of the overlapping portion is predetermined The distribution ratio is changed within a range (for example, 70 to 100 etc.) or less and ink is selectively ejected by any of the nozzles, and on the outside thereof, the nozzles of one head module 210 even in the overlapping portion It may be determined to be distributed only to Generally, nonuniformity in the width direction between the head modules 210 is more noticeable when the nozzle spacing is smaller, so the predetermined number may be appropriately determined according to the nozzle spacing and the like.

As described above, the drive image conversion process according to the embodiment of the discharge setting method includes a plurality of head modules 210 in which the nozzles 27 (nozzle openings 27a) are arranged at different positions in a predetermined width direction and adjacent in the width direction An ejection setting method relating to ink ejection from each of the nozzles 27 in the head unit 21 in which the disposition range of the nozzles 27 in the matching head module 210 is disposed so as to partially overlap in the width direction. A halftone processing step of performing halftone processing on the multi-gradation data using a dither matrix 53 that determines the presence or absence of ink ejection for each dot position based on a threshold value corresponding to the value; At each dot position in the overlapping area of the arrangement range of the nozzles 27 in the halftone data And the distribution step of determining the presence or absence of the ink discharge from each of the nozzles 27 using the distribution matrix 54 for distributing which nozzles 27 are to perform the ink discharge, and the intensity peak of the spatial frequency related to the distribution matrix 54 is It is determined to be lower than the spatial frequency intensity peak related to the dither matrix 53.
As described above, the dither matrix 53 used for halftone processing and the matrix 54 for distributing the nozzles in the overlapping portion are prepared separately, and the intensity peak of the spatial frequency related to the distribution matrix 54 corresponds to the spatial frequency related to the dither matrix 53. By shifting to a lower frequency side than the intensity peak, the optimum halftone processing by the dither matrix 53 is not hindered. Further, by discontinuing discontinuities associated with positional deviation between the head modules 210 and deviation of the driving voltage pattern, etc. in units of plural dot positions, positional deviation and uneven density are not generated at the spatial frequency related to halftone processing, Does not cause noticeable image quality deterioration. In addition, since relative positional deviation itself between adjacent dots is reduced, image quality degradation is reduced. Therefore, when recording an image using the head unit 21 in which a plurality of head modules 210 (recording heads 211) are arrayed, it is possible to output an image with more appropriate image quality more effectively at both the seams and non-seams of the array It is possible to generate image data for driving the recording head 211 which has been set for the proper ink ejection. Further, by holding the dither matrix 53 and the distribution matrix 54 independently, it is necessary to respectively generate and update a processing matrix considering both of them according to the arrangement of the head modules 210 in each ink jet printing apparatus 100. Since it is not, it is possible to perform setting processing and updating processing of the processing matrix much more easily without degrading the image quality.

In the halftone processing step, for each dot area corresponding to the gradation value, a threshold value corresponding to the ink ejection rate corresponding to the gradation value, and setting between large droplets, medium droplets and small droplets The process setting step of determining the ratio, and the discharge amount setting step of determining the discharge amount of the ink for each dot position determined to discharge the ink based on the set ratio set, the setting ratio being the ink discharge rate It is set to be equal to or less than a predetermined value less than 100%.
In this discharge setting method, when it is possible to discharge droplets of a plurality of sizes, the droplet size is set larger than the gradation value to set the ratio of the ink discharge nozzles lower, so that the ink can be discharged immediately after the ink is landed. Reduce overlap between ink droplets on the media. As a result, it is possible to reduce the occurrence of black streaks and color unevenness caused by the overlapping and to prevent the deterioration of the image quality. Such a process can significantly suppress the deterioration of the image quality, particularly where the overlap is likely to occur due to the relative positional deviation as in the overlap area.

  Also, in the halftoning step, the setting of the threshold and the set ratio among the plurality of droplet sizes according to the ink ejection rate corresponding to the gradation value is made according to the medium to which the ink is to be ejected among a plurality of predetermined types. To select. Thus, with this discharge setting method, the number of ink discharge nozzles per set area (ink discharge rate) is set by increasing the droplet size for ink that is likely to spread immediately before ink droplets penetrate immediately after landing. It is possible to reduce the image quality effectively.

  Further, in the distribution step, distribution is performed on a range of a predetermined number of dot positions of 100 or less in the width direction in the overlapping region, and which nozzle is used to selectively determine which ink is to be ejected. That is, when the overlapping area is wide, distribution is not performed on the whole, and distribution is performed only on the width of a predetermined number of dot positions, and ink ejection by the nozzles of one head module 210 starts from the other head module 210 Switch to the ink discharge by the nozzle of. By defining the distribution processing range in this manner, distribution is effectively performed within an appropriate width with respect to the spatial period of the distribution related to distribution of the nozzles, and the influence of positional deviation in the width direction is appropriately reduced. Can. Further, since the ink discharge operation is performed only from the nozzles 27 of one head module 210 on the outside thereof, it is not necessary to consider such positional deviation in a wider range than necessary. Therefore, the setting concerning coexistence with processing amount and suppression of image quality degradation can be streamlined.

  Further, the medium to which ink is to be ejected includes a cloth. By applying the above-described discharge setting method to a cloth or the like in which the thread size is coarse and the ink easily penetrates, it is possible to significantly suppress the deterioration of the image quality in particular.

  Also, the halftoning step is performed using the dither method. That is, since the distribution matrix is generated separately from the dither matrix in the halftoning process, the advantages of the dither matrix can be fully utilized to enable high-speed and appropriate image quality processing.

  Further, the intensity peak of the spatial frequency related to the dither matrix 53 and the intensity peak of the spatial frequency related to the distribution matrix 54 used for distributing the discharge nozzles between the head modules 210 are respectively determined isotropically. As a result, the deterioration of the image quality can be appropriately suppressed in the entire two-dimensional image, and the processing can be performed efficiently.

Further, the control unit 40 according to the present embodiment includes, as the setting unit, a plurality of head modules 210 in which the nozzles 27 (nozzle openings 27a) are arranged at different positions in the predetermined width direction. Ejection setting regarding ink ejection from each of the nozzles 27 in the head unit 21 in which the arrangement range of the nozzles 27 in the second embodiment is partially overlapped in the width direction is performed. The control unit 40 performs halftoning processing on the multi-gradation data using the dither matrix 53 that determines the presence or absence of ink ejection for each dot position based on the threshold value corresponding to the gradation value of the multi-gradation data. The tone data is generated, and from which nozzles the ink ejection is to be performed is distributed to each dot position in the overlapping area of the arrangement range among the generated halftone data, using the distribution matrix 54 from each of the nozzles 27 The presence or absence of ink ejection is determined, and the spatial frequency intensity peak related to the distribution matrix 54 is set lower than the spatial frequency intensity peak related to the dither matrix 53.
In a data processing apparatus capable of performing such processing by the control unit 40, the optimum halftone processing by the dither matrix is not impeded, but the noticeable image quality deterioration is not caused. In addition, since relative positional deviation itself between adjacent dots is reduced, image quality degradation is reduced. Therefore, when recording an image using the head unit 21 in which a plurality of head modules 210 (recording heads 211) are arrayed, it is possible to output an image with more appropriate image quality more effectively at both the seams and non-seams of the array It is possible to generate image data for driving the recording head 211 which has been set for the proper ink ejection. Further, by holding the dither matrix and the distribution matrix independently, there is no need to generate and update processing matrices in consideration of both according to the arrangement of the head modules 210 in each ink jet printing apparatus 100. It is possible to perform setting processing and updating processing of the processing matrix much more easily without degrading the image quality.

  Further, the inkjet recording apparatus 100 according to the present embodiment includes the data processing apparatus described above and a head unit 21. Therefore, the high quality image can be recorded at high speed based on the driving image data set easily and at high speed as described above.

The present invention is not limited to the above embodiment, and various modifications are possible.
For example, the unit size (the number of matrices) corresponding to the dot area of the dither matrix 53 to be applied may be different from the unit size of the distribution matrix 54. When a plurality of head units 21 are provided, different dither matrices 53 and distribution matrices 54 may be set for each head unit 21 or both or any one of them may be shared by a plurality of head units 21. It is also good. In addition, the common dither matrix 53 and the distribution matrix 54 may be rotated for each head unit 21 and used.

  Further, in the above embodiment, the plurality of head modules 210 arranged in a staggered pattern have been described as an example, but the plurality of head modules 210 in which the nozzle arrangement is provided to be inclined with respect to the width direction The arrangement pattern of the plurality of head modules 210 and the arrangement pattern of the nozzle openings 27a (nozzles 27) according to this are arbitrary in the range having a configuration in which overlapping portions are partially in the width direction.

  In the above embodiment, the case where the ink can be ejected in any of the large droplet, medium droplet, and small droplet sizes has been described, but it may be possible to eject only one type of droplet size. Alternatively, it may be capable of discharging in two or four or more steps. When the droplet size is only one type, the setting of the setting ratio is unnecessary. Further, in this case, the setting of the predetermined value Rth or the like, which is the upper limit of the ink ejection rate according to the medium type, may not be performed.

  Further, the colored characteristics of the dither matrix 53 and the distribution matrix 54 are not particularly limited as long as the frequency peak related to the spatial distribution falls within an appropriate range. Moreover, it does not exclude what has a plurality of peaks.

  Further, in the above-described embodiment, the range in which the ink discharge is distributed among the head modules 210 is limited. However, the allocation may be performed with respect to the entire overlapping range and may not be limited.

  Further, in the above embodiment, the dye-based ink to be discharged to the fabric is described as an example, but the invention is not limited thereto, and various inks to be discharged to various media may be used. .

In the above embodiment, although the control unit 40 of the inkjet recording apparatus 100 performs the processing, the processing is performed by an external server or a computer terminal, and the processed data is output to the inkjet recording apparatus 100 or the like. It is also good.
In addition, specific details such as the contents of the process and the process procedure described in the above embodiment can be appropriately changed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 conveyance part 11 drive roller 12 conveyance drive part 14 conveyance belt 20 image recording part 21 head unit 210, 210a, 210b head module 211 recording head 22 carriage 23 carriage raising / lowering part 232 raising / lowering motor 233 electromagnetic brake 234 beam member 235 support 24 carriage Drive unit 25 Head drive unit 27 Nozzle 27a Nozzle opening 30 Ink storage unit 31 Ink tank 32 Rack 40 Control unit 41 CPU
42 RAM
50 storage unit 51 conversion processing program 52 gradation dot correspondence information 53 dither matrix 54 distribution matrix 60 communication unit 70 display / operation reception unit 90 bus 100 inkjet recording apparatus

Claims (9)

In a line head having a plurality of head modules in which nozzles are arranged at different positions in a predetermined width direction, and the arrangement range of the nozzles in the adjacent head modules in the width direction is partially overlapped in the width direction A discharge setting method related to the ink discharge from each of the nozzles, wherein
Halftone processing is performed on the multi-gradation data using the first matrix that determines the presence or absence of ink ejection for each dot position based on the threshold value corresponding to the gradation value of the multi-gradation data to generate halftone data Halftone processing step,
Ink discharge from each of the nozzles using a second matrix that distributes which nozzle is to be used to discharge ink to each dot position in the overlapping area of the arrangement range among the generated halftone data Distribution step to determine presence or absence,
Including
The intensity setting of the spatial frequency according to the second matrix is determined to be lower than the intensity peak of the spatial frequency according to the first matrix. The halftoning step is
A process setting step of determining, for each dot area corresponding to the gradation value, a setting ratio between the threshold and the predetermined plural stages of ink ejection amounts corresponding to the ink ejection rate corresponding to the gradation value;
A discharge amount setting step of determining the discharge amount of the ink for each dot position determined to discharge the ink based on the set ratio determined;
Including
The discharge setting method according to claim 1, wherein the setting ratio is set so that the ink discharge rate is equal to or less than a predetermined value less than 100%.   In the halftoning step, the setting of the threshold value and the setting ratio according to the ink ejection rate corresponding to the gradation value is selected according to the medium to which the ink is to be ejected from among a plurality of predetermined types. The discharge setting method according to claim 2 characterized by the above.   In the distribution step, distribution is performed on a range of a predetermined number of dot positions of 100 or less in the width direction in the overlapping region, and it is characterized by selectively determining from which nozzle the ink is to be ejected. The discharge setting method according to claim 2 or 3.   5. The discharge setting method according to any one of claims 1 to 4, wherein the medium to be subjected to the ink discharge includes a cloth.   The discharge setting method according to any one of claims 1 to 5, wherein the halftoning step is performed using a dither method.   The intensity peak of the spatial frequency according to the first matrix and the intensity peak of the spatial frequency according to the second matrix are respectively determined isotropically. The discharge setting method according to one item. In a line head having a plurality of head modules in which nozzles are arranged at different positions in a predetermined width direction, and the arrangement range of the nozzles in the adjacent head modules in the width direction is partially overlapped in the width direction A setting unit configured to perform discharge setting relating to ink discharge from each of the nozzles;
The setting unit is
Halftone processing is performed on the multi-gradation data using the first matrix that determines the presence or absence of ink ejection for each dot position based on the threshold value corresponding to the gradation value of the multi-gradation data to generate halftone data And
Ink discharge from each of the nozzles using a second matrix that distributes which nozzle is to be used to discharge ink to each dot position in the overlapping area of the arrangement range among the generated halftone data Determine the presence or absence
A data processing apparatus, wherein an intensity peak of spatial frequency according to the second matrix is set lower than an intensity peak of spatial frequency according to the first matrix. A data processing apparatus according to claim 8;
Said line head,
An inkjet recording apparatus comprising: