Liquid ejecting apparatus, liquid ejecting method, storage medium, and computer apparatus

Abstract

The present invention relates to a liquid ejecting apparatus, a liquid ejecting method, a storage medium, and a computer device, and aims at improving image quality. The liquid ejecting apparatus includes: a printing section that performs a multi-pass printing process of alternately implementing a main scanning movement operation of ejecting liquid while moving a printing head with respect to a recording medium in a main scanning direction and a sub scanning movement operation of relatively moving the printing head with respect to the recording medium in a sub scanning direction in a state of not ejecting liquid; a first quantization processing section that converts an input image printed by the printing section into dot data; and a second quantization processing section that converts the dot data into scanning data for each main scanning movement operation through an operation of a division mask having a bit number of two or more and the dot data, the first quantization processing section converts the input image into dot data including at least two or more kinds of dots, and the second quantization processing section changes a division method of the dots in accordance with a kind of the dots included in the dot data.

Description

TECHNICAL FIELD

[0001] The present application relates to a liquid ejection apparatus, a liquid ejection method, a storage medium, and a computer apparatus. BACKGROUND

[0002] It is known that a mask process of scanning an image with a mask pattern for dot data subjected to halftone processing is a printing method of a serial type inkjet printer. The prior art proposes a technical solution for the mask process, such as JP Laid-Open No. 2004-209943, which proposes setting a plurality of threshold values on the density level of dot data subjected to halftone processing, and switching a mask pattern according to the threshold values, thereby changing a division method for each gray scale.

[0003] However, the above technical solution has a problem that the quality can deteriorate, particularly in an image like a gradual change of a color tone, because the division method is changed for each gray scale by the threshold values. SUMMARY

[0004] The present application proposes the following technical solution in view of the above problem, and aims to provide a liquid ejection apparatus, a liquid ejection method, a storage medium, and a computer apparatus capable of suppressing deterioration of the quality.

[0005] To solve the above problem and achieve the above object, the liquid ejection apparatus of the present application includes: a printing section that performs a multi-pass printing process, the multi-pass printing process alternately implementing a main scanning movement action and a sub scanning movement action, the main scanning movement action being a movement of a print head in a main scanning direction orthogonal to a sub scanning direction with respect to a recording medium while ejecting a liquid, the sub scanning movement action being a movement of the print head with respect to the recording medium or the recording medium with respect to the print head in the sub scanning direction without ejecting the liquid; a first quantization processing section for converting an input image to be printed by the printing section into dot data; and a second quantization processing section for converting the dot data into scanning data for each of the main scanning movement actions by an operation of a division mask having a bit number of two or more and the dot data, the first quantization processing section converting the input image into the dot data including two or more kinds of dots, the second quantization processing section changing a division method of the dots according to the kind of the dots included in the dot data.

[0006] The present application has an effect of improving the quality. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a perspective view of an inkjet printer as an example of an image forming apparatus relating to the first embodiment.

[0008] Figure 2is a front view of an inkjet printer device as an example of an image forming apparatus (liquid ejecting apparatus) of the first embodiment.

[0009] Figure 3 is a plan view of the inkjet printer device of the first embodiment.

[0010] Figure 4 is a plan view of an example nozzle arrangement of a print head possessed by the inkjet printer device of the first embodiment.

[0011] Figure 5 is a hardware structure block diagram of an image forming system related to the first embodiment.

[0012] Figure 6 is a flowchart of an example multi-pass printing process of the inkjet printer device related to the first embodiment.

[0013] Figure 7 is a schematic view of an example scan data generation process of the inkjet printer device related to the first embodiment.

[0014] Figure 8 is a schematic view of an example dot division method for each gray scale of the inkjet printer device related to the first embodiment.

[0015] Figure 9 is a schematic view of an example effect of changing the dot division method for each droplet type possessed by the inkjet printer device related to the first embodiment.

[0016] Figure 10 is a schematic view of an example dot division method revision process of the inkjet printer device related to the first embodiment.

[0017] Figure 11 is a schematic view of an example dot division method revision process of the inkjet printer device related to the first embodiment.

[0018] Figure 12 is a schematic view of an example dot division method revision process of the inkjet printer device related to the second embodiment.

[0019] Figure 13 is a schematic view of an example dot division method revision process of the inkjet printer device related to the second embodiment.

[0020] Figure 14 is a schematic view of an example dot division method revision process of the inkjet printer device related to the second embodiment.

[0021] Figure 15 is a schematic view of an example dot division method revision process of the inkjet printer device related to the third embodiment.

[0022] Figure 16 is a schematic view of a point division method change process of an inkjet printing apparatus according to the third embodiment.

[0023] Figure 17 is a schematic view of a point division method change process of an inkjet printing apparatus according to the fourth embodiment.

[0024] Figure 18 is a schematic view of a point division method change process of an inkjet printing apparatus according to the fourth embodiment. DETAILED DESCRIPTION

[0025] Embodiments of a liquid ejecting apparatus, a liquid discharge method, a storage medium, and a computer apparatus will be described in detail below with reference to the drawings.

[0026] <First Embodiment>

[0027] Figure 1 is a perspective view of an inkjet printing apparatus as an example of an image forming apparatus according to the first embodiment.

[0028] The inkjet printing apparatus 10 has a carriage 200 and a work table 13 on which a recording medium 101 is placed. The carriage 200 is provided with a print head unit 300 (see Figure 5 ) which is an inkjet type image forming section provided with a plurality of print heads (liquid ejecting heads) having a plurality of nozzles. The inkjet printing apparatus 10 forms an image by ejecting liquid from the nozzles of the print heads (print head sections). The nozzles of the print heads are provided on a surface opposite to the work table 13. The liquid in the present embodiment is, for example, ink having ultraviolet hardening properties.

[0029] An irradiation unit 400 which is a light source that irradiates ultraviolet rays is provided on the surface of the work table 13 opposite to the carriage 200. The irradiation unit 400 (an example of an irradiation section) irradiates light of a wavelength that hardens the liquid ejected from the nozzles of the print heads.

[0030] Guide rods 19 are provided on the left and right side plates 18a, 18b. The guide rods 19 hold the carriage 200 so that it can move in the X direction (main scanning direction).

[0031] The carriage 200, the guide rods 19, and the side plates 18a, 18b are integrated and can move in the Y direction (sub scanning direction) along guide rails 29 provided in the lower portion of the work table 13. The carriage 200 is held so that it can move in the Z direction (up and down direction).

[0032] As shown in Figure 1 , the work table 13 on which the recording medium is placed is fixed. Figure 1The inkjet printing apparatus 10 shown repeatedly alternates between main scanning and sub-scanning actions to form an image. The main scanning action involves moving the print head in the main scanning direction while simultaneously ejecting ink from the nozzles onto the recording medium 101. The sub-scanning action involves moving the print head in the sub-scanning direction. In other words, in this embodiment, the carriage 200, guide rod 19, and guide rail 29 in the inkjet printing apparatus 10 serve as a single printing unit performing multi-pass printing, alternately performing the main scanning and sub-scanning actions.

[0033] Here, the main scan action is an example of a main scan movement action, in which the print head moves relative to the recording medium 101 in the main scan direction (X direction) orthogonal to the sub-scan direction (Y direction) while discharging liquid. The sub-scan action is an example of a sub-scan movement action, in which the print head moves relative to the recording medium 101 or the recording medium 101 moves relative to the print head in the sub-scan direction without discharging liquid.

[0034] Figure 2 This is a front view of an example inkjet printing apparatus of the image forming apparatus (liquid jet apparatus) according to the first embodiment. Figure 3 This is a plan view of an example inkjet printing apparatus according to the first embodiment. Figure 2 and Figure 3 In the middle, apart from the shape around the carriage and Figure 1 Aside from the different shapes, their other functions are the same as... Figure 1 They are roughly the same.

[0035] exist Figures 1 to 3 During the sub-scanning operation, the printhead 300K to 300W mounted on the carriage 200 moves relative to the recording medium 101 in the sub-scanning direction.

[0036] As a variation of the image forming apparatus of this embodiment, the stage 13 on which the recording medium 101 is placed may also be configured as a movable structure. In this case, the stage 13 becomes a moving part in the sub-scanning direction, which moves (transports) the recording medium 101 relative to the printheads 300K to 300Y in the sub-scanning direction during the sub-scanning operation.

[0037] Figure 2 An example of a printhead array is shown, in which one printhead 300K to 300Y is set in the sub-scanning direction, but multiple printheads can also be set in the sub-scanning direction in a printhead array.

[0038] Figure 4 This is a top view of an example of the nozzle arrangement in the printhead of the inkjet printing apparatus according to the first embodiment.

[0039] like Figure 4As shown, the carriage 200 has a print head that can have a color ink ejection head 221 and a base color ink ejection head 222. The color ink ejection head 221 and the base color ink ejection head 222 are provided with a plurality of nozzles 221a, 222a that eject ink. In each of the ejection heads, the nozzles 221a, 222a are arranged in a sub-scanning direction.

[0040] In the overlapping region Ro, the color ink ejection head 221 and the base color ink ejection head 222 are arranged so that the nozzles 221a, 222a of each ejection head are in register in the sub-scanning direction. The overlapping region Ro is a region in which the color ink ejection head 221 and the base color ink ejection head 222 overlap. That is, in the overlapping region Ro, the nozzles 221a, 222a of the color ink ejection head 221 and the base color ink ejection head 222 are arranged in register in the main scanning direction.

[0041] The ejection state of ink droplets ejected from the color ink ejection head 221 and the base color ink ejection head 222 is controlled by drive pulses applied to drive elements arranged in correspondence with the nozzles 221a, 222a of each ejection head. A piezoelectric element such as a PZT can be used as the drive element.

[0042] Hereinafter, the hardware configuration of an image forming system including an image forming apparatus (inkjet printing apparatus 10) will be described using Figures 1 to 3 , Figure 5 .

[0043] Figure 5 is a hardware configuration block diagram of an example of an image forming system to which the first embodiment relates. In Figure 5 the image forming system shown in Figures 1 to 3 , an image forming apparatus (inkjet printing apparatus 10) that forms an image by mechanical configuration is connected to a PC 2 that is an external device, and image processing is performed by the PC 2. However, the functions related to the image processing performed by the PC 2 can also be provided inside the image forming apparatus.

[0044] As shown in Figure 5 , the image forming apparatus (inkjet printing apparatus 10) of the present embodiment has a controller unit 3, a detection group 414, a conveyance unit 100 that is a conveyance section, a carriage 200, a print head unit 300, an irradiation unit 400, and a maintenance unit 500.

[0045] The controller unit 3 includes a unit control circuit 31, a memory 32, a CPU (Central Processing Unit) 33, and an I / F 34.

[0046] I / F 34 is an interface for connecting the image forming apparatus (inkjet printing apparatus 10) with an external PC (Personal Computer) 2. The connection of the image forming apparatus (inkjet printing apparatus 10) and the PC 2 can be any manner, for example, connection through a network and a manner of directly connecting both by a communication cable, and the like.

[0047] The detection group 414 is, for example, various sensors and the like provided in the inkjet printing apparatus 10.

[0048] The CPU 33 controls the actions of the units of the inkjet printing apparatus 10 by the unit control circuit 31 using the memory 32 as a work area. Specifically, the CPU 33 controls the actions of the units based on the recording data received from the PC 2 and the data detected by the detection group 414 to form an image as a liquid-applied surface 102 on the recording medium 101 (also referred to as a base material or the like). In the present embodiment, the CPU 33 has a color chart division data generation section 511, a first quantization processing section 512, and a second quantization processing section 513. The actions of each of the color chart division data generation section 511, the first quantization processing section 512, and the second quantization processing section 513 will be described later.

[0049] A printer driver is installed in the PC 2, with which recording data transmitted to the inkjet printing apparatus 10 is generated from image data. The recording data includes instruction data for causing the conveyance unit 100 and the like of the inkjet printing apparatus 10 to act and pixel data on an image (liquid-applied surface 102). Each pixel in the pixel data is composed of two-bit data, which is expressed by four gray scales.

[0050] Next, the mechanical structure of the image forming apparatus will be described with reference to Figure 2 , Figure 3 , Figure 5 The conveyance unit 100 has a table 13 and a suction mechanism 120. The suction mechanism 120 has a plurality of suction holes 100a provided on the fan 110 and the table 13. The suction mechanism 120 temporarily fixes the recording medium 101 on the conveyance unit 100 by sucking the recording medium 101 from the suction holes 100a by driving the fan 110. The suction mechanism 120 can suck paper by electrostatic suction. The conveyance unit 100 controls the movement in the Y-axis direction (sub-scanning direction) based on a drive signal from the CPU 33 (unit control circuit 31).

[0051] Figure 2 , Figure 3 , Figure 5In the embodiment, the conveyance unit 100 has a conveyance control section 210, a roller 105, and a motor 104. The conveyance control section 210 rotates the roller 105 by driving the motor 104, and enables the recording medium 101 to move in the Y-axis direction (sub-scanning direction).

[0052] As shown in FIG. 1, the conveyance unit 100 can also move the carriage 200 instead of the recording medium 101 in the Y-axis direction (sub-scanning direction). That is, the conveyance unit 100 relatively moves the recording medium 101 and the carriage 200 in the Y-axis direction (sub-scanning direction). Figure 1

[0053] As shown in the right side of FIG. 2, for example, the conveyance unit 100 has a side plate 407b that supports two guide rails 201 for guiding the carriage 200 in the X-axis direction (main scanning direction), a table 406 that supports the side plate 407b, a belt 404 fixed to the table 406, a driving wheel 403 and a driven wheel 402 that are wound with the belt 404, a motor 405 that drives the driving wheel 403, and the conveyance control section 210. Figure 2

[0054] Further, as shown in the left side of FIG. 3, the conveyance unit 100 has a side plate 407a that supports the two guide rails 201 for guiding the carriage 200 in the X-axis direction (main scanning direction), a table 408 that slidably supports the side plate 407a, and a groove 409 that is formed on the table 408 and guides the side plate 407a in the sub-scanning direction. Figure 2 The conveyance unit 100 drives the motor 405 with the conveyance control section 210, drives the driving wheel 403 to rotate, and moves the belt 404 in the Y-axis direction (sub-scanning direction). The table 406 that supports the carriage 200 moves in the Y-axis direction (sub-scanning direction) along with the movement of the belt 404, and thus the carriage 200 can be moved in the Y-axis direction (sub-scanning direction). The side plate 407a moves in the Y-axis direction (sub-scanning direction) along the groove 409 of the table 408 along with the movement of the table 406 in the Y-axis direction (sub-scanning direction).

[0055] As shown in FIG. 4, the print head unit 300 is composed of print head arrays (print heads) 300K, 300C, 300M, 300Y, 300CL, 300W that respectively discharge UV hardening type inks (one example of liquid) of K, C, M, Y, CL, W, and is provided on the lower surface of the carriage 200.

[0056] Figure 2 Each of the print head arrays 300K to 300W has one or a plurality of print heads. When the print head array is composed of a plurality of print heads, the plurality of print heads can be arranged in a staggered manner or in a line.

[0057]

[0058] ​​​​Each of the print heads has a piezoelectric element as a driving element, and when a driving signal is applied to the piezoelectric element by the CPU 33 (unit control circuit 31), the piezoelectric element generates a contraction motion, and a pressure change is generated by the contraction motion to eject the UV-curable ink onto the recording medium 101. In this way, the liquid coated surface 102 (one example of a liquid coated surface) is formed on the recording medium 101.

[0059] The UV-curable ink suitable for the present embodiment is, for example, an ink containing a methacrylate-based monomer. The methacrylate-based monomer has the advantage of having weak skin sensitivity, but has the characteristic of having a large hardening shrinkage scale compared to ordinary ink.

[0060] The irradiation unit 400 is provided on the side surface (X-axis direction surface) of the carriage 200, and irradiates UV light according to a driving signal from the CPU 33 (unit control circuit 31). The irradiation unit 400 is mainly composed of a UV irradiation lamp that irradiates UV light.

[0061] The carriage 200 controls movement in the Z-axis direction (height direction) and the X-axis direction (main scanning direction) according to a driving signal from the CPU 33 (unit control circuit 31).

[0062] The carriage 200 moves in the main scanning direction (X-axis direction) along the guide rail 201. The scanning section 206 has a driving wheel 203, a driven wheel 204, a transmission belt 202, and a motor 205. The carriage 200 is fixed to the transmission belt 202 that is stretched between the driving wheel 203 and the driven wheel 204. The motor 205 drives the transmission belt 202 to move the carriage 200 left and right in the scanning direction. The guide rail 201 is supported by side plates 211A and 211B of the device main body.

[0063] The height adjustment section 207 has a motor 209 and a slide 208. The height adjustment section 207 drives the motor 209 to move the slide 208 up and down, thereby moving the guide rail 201 up and down. By moving the guide rail 201 up and down, the carriage 200 moves up and down, and the height of the carriage 200 with respect to the recording medium 101 can be adjusted.

[0064] Next, the image forming operation of the inkjet printing device 10 shown in the drawing will be described. Figure 1 The recording medium 101 is moved to an initial position for forming an image (liquid coated surface 102) in the Y-axis direction (sub-scanning direction) according to a driving signal from the CPU 33 (unit control circuit 31) by the conveyance unit 100.

[0065] Next, the carriage 200 moves to a height at which the printhead unit 300 ejects the UV-curable ink (for example, a height at which the lower surface of each printhead in the printhead array 300K-W of the printhead unit 300 is 1 mm from the head-to-medium gap of the recording medium 101) in accordance with a drive signal from the CPU 33 (unit control circuit 31). The height of the printhead unit 300 is detected by the height sensor 41, and the CPU 33 is thereby informed.

[0066] Next, the carriage 200 moves back and forth in the X-axis direction (main scanning direction) in accordance with a drive signal from the CPU 33 (unit control circuit 31), and, during this back-and-forth movement, the printhead unit 300 ejects the UV-curable ink in accordance with a drive signal from the CPU 33 (unit control circuit 31). In this way, an image of one scan (liquid-applied surface 102) is formed on the recording medium 101.

[0067] Next, after an image of one scan (liquid-applied surface 102) has been formed on the recording medium 101, the conveyance unit 100 moves by an amount of one scan in the Y-axis direction (sub-scanning direction) in accordance with a drive signal from the CPU 33 (unit control circuit 31).

[0068] Next, the operation of forming an image of one scan (liquid-applied surface 102) and the operation of moving the conveyance unit 100 by an amount of one scan in the Y-axis direction are alternately performed until the formation of the image (liquid-applied surface 102) is complete.

[0069] After the formation of the image (liquid-applied surface 102) on the recording medium 101 is complete, the UV-curable ink is leveled (hereinafter referred to as "leveling time"), and then the irradiation unit 400 performs irradiation of UV light.

[0070] Figure 6 is a flowchart of an example of the multi-pass printing process of the inkjet printing device according to the first embodiment. An example of a multi-pass printing process flow of the inkjet printing device 10 according to the present embodiment will be described below with reference to Figure 5 、 Figure 6

[0071] After the image data to be printed is input, the color separation data generation section 511 generates color separation data for each color of ink installed in the inkjet printing device 10 based on the input image data (an example of input image) (step S801). For example, in the case where the inkjet printing device 10 performs printing using CMYK ink, the color separation data generation section 511 generates color separation data for each color of CMYK based on the input image data.

[0072] ​Next, the first quantization processing section 512 generates dot data from the color separation data generated by the color separation data generation section 511 using a dot data generation mask (step S802). Here, the dot data generation mask is, for example, a dither mask provided with a threshold value for halftone processing. That is, the first quantization processing section 512 functions to convert the image data into dot data. At this time, the CPU 33 converts the image data into dot data containing at least two or more kinds of dots. The dot data includes at least two or more kinds of dots, a small droplet dot and a large droplet dot having a droplet amount larger than that of the small droplet dot. The dot data can also include a medium droplet dot having a droplet amount larger than that of the small droplet dot but smaller than that of the large droplet dot.

[0073] Next, the second quantization processing section 513 generates scan data from the dot data generated by the first quantization processing section 512 using a division mask (step S803). Specifically, the second quantization processing section 513 determines which of the nozzles 221a, 222a forms a dot at each dot of the dot data at the time of scanning in the main scanning direction by the printhead at one time. Here, the division mask is a mask having two or more bits.

[0074] In the present embodiment, the second quantization processing section 514 is an example of a section for converting the dot data (main scanning pass) into scan data for each scan by an operation of the division mask and the dot information. At this time, the second quantization processing section 514 changes the division method of the dot depending on the kind of dot included in the dot data. This makes it possible to continuously change the division method of the dot without switching the division method of the dot depending on the gray scale. As a result, it is possible to suppress deterioration of the image quality, particularly in an image in which the gradation is gradually changed.

[0075] Then, the unit control circuit 31 transmits the generated scan data to the drive circuit inside the printhead and performs printing of the image on the recording medium 101 based on the scan data.

[0076] Figure 7 is a schematic view of an example of a scan data generation process of the inkjet printing apparatus according to the first embodiment. Next, an example of a scan data generation process of the inkjet printing apparatus 10 according to the present embodiment will be described with reference to Figure 7 , with the first and third scans of the printhead when performing multiple scans in 2-pass 1 / 2 interlaced scanning being described below, and the second and fourth scans being generated in the same manner.

[0077] First, as shown in Figure 7 , the second quantization processing section 513 extracts pixels present at the scan positions of the nozzles 221a, 222a in the first and third scans of the printhead from the dot data (nozzle position dot data in the first and third scans). Specifically, Figure 7The dashed lines represent the scanning positions of nozzles 221a and 222a in the first and third scans, respectively. The second quantization processing unit 513 extracts the pixels present at the scanning positions (nozzle position data in the first and third scans).

[0078] Next, the second quantization processing unit 513 performs mask processing on the extracted pixels using a partitioning mask (first and third scan masks), thereby generating scan data for the first and third scans respectively (first and third scan data). For example, Figure 7 As shown, the second quantization processing unit 513 generates scan data for the point data of the first and third scans using the respective partitioning masks of the first and third scans.

[0079] At this time, the second quantization processing unit 513 generates scan data, which indicates that among the pixels of the dot data, liquid is sprayed onto pixels corresponding to "1" in the dividing mask, while no liquid is sprayed onto pixels corresponding to "0" in the dividing mask. Here, a dividing mask is set for each scan of the print head, and the dividing mask indicates the position of the pixel from 222a that sprays liquid in that scan, i.e., the dot configuration position. The dividing mask is, for example, as shown below. Figure 7 The figure shows binary data representing each point nozzle 221a and whether liquid is ejected from nozzles 221a and 222a.

[0080] In the case of multiple scans using 2-pass 1 / 2 interlaced scanning, the partitioning masks used to generate scan data for the repeated positions of nozzles 221a and 222a in the sub-scanning direction are complementary. Therefore, by using the complementary partitioning masks to perform mask processing on the dot data, the second quantization processing unit 513 can decompose the dot data into scan data equivalent to the number of scans of the print head.

[0081] The following is for reference. Figure 8 This describes an example of a grayscale division method for the inkjet printing apparatus 10 involved in this embodiment. Figure 8 This is a schematic diagram illustrating an example of a method for dividing each grayscale point implemented in the inkjet printing apparatus according to the first embodiment. Figure 8 In this process, lighter-colored areas receive less injection than darker-colored areas. The injection amount corresponds to the proportion of points in the origin data that are hit on the recording medium 101 during each scan. First, the segmentation methods applicable to low-grayscale and high-grayscale regions are explained respectively.

[0082] Low grayscale areas are more prone to uneven density compared to high grayscale areas. One of the main reasons for this uneven density is that the dot diameter at the tip of the printhead (hereinafter referred to as the printhead tip region) differs from the others. Therefore, it is best to reduce the injection volume of mask A in the printhead tip region.

[0083] On the other hand, in high grayscale regions, the concentration reaches saturation, making it difficult to observe uneven concentration. However, as the amount of adhesive increases, surface unevenness easily occurs, and gloss unevenness becomes significant (especially noticeable in UV inks). As with mask A, when there is a drastic change in the injection amount, differences in surface condition occur in the areas where the injection amount changes, resulting in gloss unevenness. Therefore, in high grayscale regions, mask B, with its smaller variation in injection amount, is preferable.

[0084] Based on the above, a compromise solution for the optimal mask shape can be found between high grayscale regions and low grayscale regions. Therefore, the second quantization processing unit 513 changes the partitioning method according to the grayscale. This improves image quality.

[0085] Next, use Figure 9 This embodiment will explain the effect of a method for changing the dot division based on the type of dot (hereinafter referred to as droplet type) implemented in the inkjet printing apparatus. Figure 9 This is a schematic diagram illustrating the effect of a method for dividing droplet types into different points implemented in the inkjet printing apparatus according to the first embodiment. Figure 9 In the diagram, the horizontal axis represents the input (input grayscale), and the vertical axis represents the output (injection volume of each droplet type).

[0086] In this embodiment, the second quantization processing unit 513 uses a method for dividing the points of change according to droplet type. Typically, such as... Figure 9 The method illustrates the substitution of droplet types used in printing. For example, if the input grayscale of the input image is 50%, the second quantization processing unit 513 converts the dot data into a composition containing 50% large droplets and 50% small droplets. Figure 9 As shown, the first quantization processing unit 512 converts the input image into dot data, such that in the low grayscale region, the proportion of small droplets is larger than that of large droplets compared to the high grayscale region. Then, the second quantization processing unit 513 converts the dots containing small droplets into scan data using a mask (mask A) with a lower injection amount at the end of the printhead than at the middle of the printhead. The second quantization processing unit 513 also converts the dots containing large droplets into scan data using a mask B with a smaller rate of change of injection amount than that of mask A used for small droplets.

[0087] Here, for example, in the case of Figure 9As shown in the drawing, the large droplet uses the mask B, and the small droplet uses the mask A. As the input gray scale increases, the injection amount of the mask B increases continuously. In addition, for example, in the case of the input gray scale of 50%, the second quantization processing section 513 uses the mask A of 50%, and uses the mask B of 50%. As a result, the second quantization processing section 513 can change the division method by the droplet kind change point, and can continuously change the division method according to the concentration, and particularly, can suppress the deterioration of the image quality in the gradation transition image.

[0088] Figure 10 and Figure 11 is a schematic view of the point division method change processing of the inkjet printing apparatus according to the first embodiment. In Figure 10 In the point data (RIP data) shown in the drawing, 00 indicates the void, 01 indicates the small droplet, 10 indicates the medium droplet, and 11 indicates the large droplet.

[0089] In the present embodiment, the second quantization processing section 513 performs the second quantization processing using the division mask and the operation table prepared in advance, and converts the point data into the scan data for each scan. Here, the operation table is a table in which the point data and the division mask suitable for the point data are associated with each other. Figure 10 The division mask shown in the drawing is a division mask in which the kinds of the points are three, and the number of bits is three, and for example, can be a division mask of 1 px in the horizontal direction, 8 px in the vertical direction, and 3 bits. The point data can be, for example, point data of 8 px in the horizontal direction, 8 px in the vertical direction, and 2 bits. The second quantization processing section 513 can perform the calculation of the division mask and the RIP data using the operation table as shown in the drawing, and generate the scan data (see Figure 10 ). Figure 11 ).

[0090] As described above, the inkjet printing apparatus 10 according to the first embodiment can continuously change the division method of the points according to the concentration without switching the points between specific gray scales. As a result, particularly, in the gradation transition image, the deterioration of the image quality can be suppressed.

[0091] <Second Embodiment>

[0092] The present embodiment is an example in which the number of bits in which the point data and the division mask are operated is different depending on the kinds of the points included in the point data. The description of the same configuration as the first embodiment will be omitted below.

[0093] Figures 12 to 14is a schematic view of a change process of a division method of a dot of an inkjet printing apparatus according to the second embodiment. In the present embodiment, the second quantization processing section 513 can adopt different numbers of bits operated in the division mask for different kinds of dot data (droplet kinds). Here, the number of bits of the division mask is equal to or more than the number of kinds of dot data. In this case, the second quantization processing section 513 can adopt different division methods for the corresponding dots among all the droplet kinds of the dots included in the dot data.

[0094] For example, as shown in Figure 12 , Figure 13 , the second quantization processing section 513 determines 0 (non-ejection) and 1 (ejection) with values of four bits for large droplets, two bits for medium droplets, and one bit for small droplets. In this way, the second quantization processing section 513 generates scan data as shown in Figure 14 .

[0095] Thus, the inkjet printing apparatus 10 according to the second embodiment can obtain the same effects as those of the first embodiment.

[0096] <Third Embodiment>

[0097] The present embodiment is an example in which the number of bits of the division mask is smaller than the number of kinds of dots included in the dot data. Hereinafter, the description of the same parts as those of the first embodiment will be omitted.

[0098] Figure 15 and Figure 16 is a schematic view of a change process of a division method of a dot of an inkjet printing apparatus according to the third embodiment. In the present embodiment, the number of bits of the division mask is smaller than the number of kinds of dots. In this way, the number of droplet kinds in which the division method is different can be reduced, and thus the processing speed of the conversion process from the dot data to the scan data can be increased. Then, as shown in Figure 15 , the second quantization processing section 513 performs the operation of the division mask and the RIP data using the operation table. In this way, the second quantization processing section 513 generates scan data as shown in Figure 16 .

[0099] As described above, according to the inkjet printing apparatus 10 of the third embodiment, since the number of droplet kinds in which the division method is different can be reduced, the processing speed of the conversion process from the dot data to the scan data can be increased.

[0100] <Fourth Embodiment>

[0101] In the present embodiment, it is exemplified that the injection amount of the end portion of the printhead is lower than that of the central portion for the dots included in the dot data that constitute a low gray scale portion, and the change rate of the injection amount of the dots is smaller than that of the low gray scale portion for the dots included in the dot data that constitute a high gray scale portion. Hereinafter, the description of the same parts as those of the above-described embodiments will be omitted.

[0102] Figure 17 and Figure 18 Fig. 16 is a diagram illustrating an example of a change process of a division method of a dot performed by the inkjet printing apparatus according to the fourth embodiment. In the division mask of the present embodiment, for the dots included in the dot data that constitute the low-gradation part, the division amount of the end portion of the printhead is smaller than the division amount of the central portion. In this way, it is possible to reduce the amount of injection of the end portion of the printhead in the low-gradation area, and to suppress uneven density.

[0103] The division mask of the present embodiment is one in which the rate of change of the amount of injection for the dots that constitute the high-gradation part is smaller than that of the low-gradation part. In this way, it is possible to suppress a sharp change in the amount of injection in the high-gradation area, and to suppress the generation of uneven gloss. For example, in the case of the drop categories illustrated in Fig. 15, the second quantization processing section 513 uses the uneven density suppression mask A for the small drops, and the uneven gloss suppression mask B for the large drops, as illustrated in Fig. 16. Figure 17 Figure 18

[0104] As described above, the inkjet printing apparatus 10 according to the fourth embodiment is able to reduce the amount of injection of the end portion of the printhead in the low-gradation area, and to suppress uneven density, by changing the division method in accordance with the gradation level, and is able to suppress a sharp change in the amount of injection in the high-gradation area, and to suppress the generation of uneven gloss.

[0105] The program executed by the inkjet printing apparatus 10 of the present embodiment is provided in advance in a ROM or the like. In addition to this, the program executed by the inkjet printing apparatus 10 of the present embodiment is also provided in a file in an installable form or an executable form on a computer-readable recording medium such as a CD-ROM, a floppy disk (FD), a CD-R, a DVD (Digital Versatile Disk), or the like.

[0106] Furthermore, the program executed by the inkjet printing apparatus 10 of the present embodiment can also be stored in a computer connected to a network such as the Internet, and provided by downloading via the network. Furthermore, the program executed by the inkjet printing apparatus 10 of the present embodiment can be provided or distributed via a network such as the Internet.

[0107] The program executed in the inkjet printing apparatus 10 of the present embodiment is a module structure including the above-described sections (color-separation division data generation section 511, first quantization processing section 512, second quantization processing section 513), and the CPU 33 (an example of a processor) reads out the program from the above-described memory 32 such as a ROM and executes it, thereby up-loading the above-described sections to the main storage device, and generating the color-separation division data generation section 511, the first quantization processing section 512, and the second quantization processing section 513 on the main storage device.

[0108] ​​Reference Signs

[0109] 3 controller unit

[0110] 31 unit control circuit

[0111] 32 memory

[0112] 33 CPU

[0113] 34 I / F

[0114] 10 inkjet printing apparatus

[0115] 19 guide rod

[0116] 29 guide rail

[0117] 200 carriage

[0118] 300 print head unit

[0119] 300K, 300C, 300M, 300Y, 300CL, 300W print head

[0120] 511 color plane division data generating section

[0121] 512 first quantization processing section

[0122] 513 second quantization processing section

Claims

1. A liquid ejection apparatus, comprising: a printing section that performs a multi-pass printing process that alternately implements a main scan movement action and a sub-scan movement action, the main scan movement action being a movement of a print head in a main scan direction orthogonal to a sub-scan direction relative to a recording medium while ejecting liquid, the sub-scan movement action being a movement of the print head relative to the recording medium or the recording medium relative to the print head in the sub-scan direction without ejecting liquid; a first quantization processing section that converts an input image to be printed by the printing section into dot data; and, a second quantization processing section that converts the dot data into scan data for each of the main scan movement actions by an operation of a division mask having a bit number of two or more and the dot data, the first quantization processing section converting the input image into the dot data including two or more kinds of dots, the second quantization processing section changing a division method for the dots included in the dot data in accordance with the kind of the dots, wherein the second quantization processing section converts the dot data into the scan data using an operation table of the division mask prepared in advance and the dot data, the division mask being a mask in which an amount of injection of an end portion of the print head is lower than a central portion for dots included in the dot data that constitute a low gray scale portion, and a rate of change in the amount of injection of the dots is smaller than that of the low gray scale portion for dots included in the dot data that constitute a high gray scale portion.

2. The liquid ejecting device of claim 1, wherein, the second quantization processing section using a bit number of the division mask in which the operation is performed with the dot data, which is different for the kind of the dots included in the different dot data.

3. The liquid ejection apparatus according to claim 1 or 2, wherein: the bit number of the division mask is larger than the number of the kinds of the dots included in the dot data, the second quantization processing section uses a different division method for the corresponding dots among all the kinds of the dots included in the dot data.

4. The liquid ejecting device of claim 1 or 2, wherein the bit number of the division mask is smaller than the number of the kinds of the dots included in the dot data.

5. The liquid ejection apparatus according to claim 1 or 2, wherein: the dot data includes two or more kinds of dots of small droplet dots and large droplet dots having a larger amount of droplets than the small droplet dots, the second quantization processing section converts the dot data into the scan data using a first mask in which an amount of injection of an end portion of the print head is lower than a central portion of the print head for the small droplet dots included in the dot data, and converts the dot data into the scan data using a second mask smaller than the first mask for the large droplet dots included in the dot data.

6. A liquid ejection method performed by a liquid ejection apparatus, comprising: A first quantization processing step converts an input image to be printed by a printing section performing a multi-pass printing process, which alternately performs a main scanning movement operation of moving a printing head relative to a recording medium in a main scanning direction orthogonal to a sub scanning direction while ejecting liquid and a sub scanning movement operation of moving the printing head relative to the recording medium or the recording medium relative to the printing head in the sub scanning direction without ejecting liquid, into dot data; and, A second quantization processing step converts the dot data into scan data for each of the main scanning movement operations by an operation of a division mask having a bit number of two or more and the dot data, In the first quantization processing, the input image is converted into the dot data including two or more kinds of dots, In the second quantization processing, a division method is changed for each kind of dot included in the dot data; wherein, in the first quantization processing, the dot data is converted into the scan data using an operation table of the division mask prepared in advance and the dot data; the division mask is a mask in which, for dots included in the dot data that constitute a low gray scale portion, an injection amount of an end portion of the printing head is lower than a central portion, and for dots included in the dot data that constitute a high gray scale portion, a change rate of the injection amount of the dot is smaller than that of the low gray scale portion.

7. A computer-readable recording medium in which a program is stored, the program causing a computer to have functions of, a first quantization processing section for converting an input image to be printed by a printing section performing a multi-pass printing process, which alternately performs a main scanning movement operation of moving a printing head relative to a recording medium in a main scanning direction orthogonal to a sub scanning direction while ejecting liquid and a sub scanning movement operation of moving the printing head relative to the recording medium or the recording medium relative to the printing head in the sub scanning direction without ejecting liquid, into dot data; and a second quantization processing section for converting the dot data into scan data for each of the main scanning movement operations by an operation of a division mask having a bit number of two or more and the dot data, the first quantization processing section converts the input image into the dot data including two or more kinds of dots, the second quantization processing section changes a division method for each kind of dot included in the dot data; wherein the second quantization processing section converts the dot data into the scan data using an operation table of the division mask prepared in advance and the dot data; the division mask is a mask in which, for dots included in the dot data that constitute a low gray scale portion, an injection amount of an end portion of the printing head is lower than a central portion, and for dots included in the dot data that constitute a high gray scale portion, a change rate of the injection amount of the dot is smaller than that of the low gray scale portion.

8. A computer device comprising a memory and a processor, said memory holding a program which is executed by said processor to realize the following functions: a first quantization processing section for converting an input image to be printed by a printing section which performs a multi-pass printing process into dot data, said multi-pass printing process alternately performing a main scanning movement operation and a sub scanning movement operation, said main scanning movement operation moving a print head relative to a recording medium in a main scanning direction orthogonal to a sub scanning direction while ejecting liquid, said sub scanning movement operation moving said print head relative to said recording medium or said recording medium relative to said print head in said sub scanning direction without ejecting liquid; and a second quantization processing section for converting said dot data into scanning data for each of said main scanning movement operations by an operation of said dot data and a division mask having a bit number of two or more, said first quantization processing section converts said input image into said dot data including two or more kinds of dots, said second quantization processing section changes a division method for a dot included in said dot data in accordance with a kind of the dot, wherein said second quantization processing section converts said dot data into said scanning data using an operation table of said division mask prepared in advance and said dot data, said division mask is a mask in which an amount of injection of an end portion of said print head is lower than a central portion for a dot included in said dot data which constitutes a low gray scale portion, and a rate of change of the amount of injection of the dot is smaller than that of said low gray scale portion for a dot included in said dot data which constitutes a high gray scale portion.

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