Liquid dispensing device, liquid dispensing method, and program

Abstract

To provide a liquid discharge device, a liquid discharge method and a program which can achieve halftone making both granularity and banding resistance compatible.SOLUTION: The liquid discharge device, which performs image formation, on one line in a main scanning direction, by discharging ink in multiple times of scanning, comprises an obtaining part that obtains image data, an image processing part that generates printing data by halftone processing using a dither mask, and a control part that controls movement of a discharge head and control of discharging ink. At a shadow side, the control part performs control so that a ratio of the number of dots of ink that is continuously discharged in the main scanning direction, of the total number of dots of ink that is discharged by one-time scanning is larger than at a highlight side, with respect to the one line in the main scanning direction; and at the shadow side, performs control so that a ratio of positions where dots of ink are superposingly discharged to a position on the same coordinate by the one-time scanning and another scanning, of all positions of the one line in the main scanning direction, is larger than at the highlight side.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a liquid ejection device, a liquid ejection method, and a program.

Background Art

[0002] Conventionally, as a liquid ejection device used in an office environment, an inkjet printer or the like that ejects ink from an inkjet head and performs image processing by attaching the ejected ink to a recording medium is known. In such an inkjet printer, in image processing, it has a halftone mask and a rendering mask separately, and after performing halftone processing (half-tone processing), it performs a rendering process of allocating ejection nozzles for each scan. However, there is a problem that if the accuracy of the landing position of ink dots between scans is low, the granularity deteriorates significantly or banding occurs.

[0003] As a technique related to the ejection control of such an inkjet printer, in order to expand the color gamut of low-brightness portions, generation means for generating black colorant data for arranging dots of black colorant on a recording medium and a plurality of colored colorant data for arranging dots of each of the plurality of colored colorants on the recording medium from input image data, and forming means for forming an image on the recording medium using the black colorant and the plurality of colored colorants based on the black colorant data and the plurality of colored colorant data. The generation means generates colorant data for arranging a plurality of dots having different sizes, and there is a case where the colorant data is generated so that dots of the black colorant and dots of the plurality of colored colorants are arranged with different sizes of the other dots adjacent to the size of one dot (for example, Patent Document 1).

[0004] Furthermore, in order to reduce banding, there is an image forming apparatus that has a first recording head and a second recording head having a plurality of nozzles along a predetermined direction, and uses the first recording head and the second recording head connected so that a predetermined number of nozzles overlap in a predetermined direction, and includes a printing control means that controls dot formation from a predetermined number of nozzles such that, in the overlap region where dots are formed by a predetermined number of nozzles, the recording density of dots and the number of consecutive dots in a direction perpendicular to the predetermined direction are smaller at the ends of each recording head in a predetermined direction than at the center of the overlap region in a predetermined direction (for example, Patent Document 2). [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, while the technology described in Patent Document 1 discloses the operation of overlapping dots, it lacks details on how the dots are overlapped through multiple scans, thus failing to achieve an ejection operation that balances granularity and banding resistance. Furthermore, the technology described in Patent Document 2 only suppresses banding in the junction area between recording heads and does not contribute to the occurrence of banding due to poor accuracy of the impact position.

[0006] The present invention has been made in view of the above, and aims to provide a liquid dispensing device, a liquid dispensing method, and a program that can achieve an intermediate consistency that balances granularity and banding resistance. [Means for solving the problem]

[0007] To solve the above-mentioned problems and achieve the objective, the present invention provides a liquid ejection device that forms an image on one line in the main scanning direction of a recording medium by ejecting ink from a nozzle during multiple scans of the ejection head in the main scanning direction, comprising: an acquisition unit that acquires image data to be printed; an image processing unit that generates print data by halftone processing using a dither mask on the image data; and a control unit that controls the movement of the ejection head and the ejection of ink based on the print data, wherein the control unit ejects ink on one line in the main scanning direction of the recording medium with a single scan of the ejection head in the shadow side gradation shown in the print data. Color 1 Of the total number of ink dots, those ejected continuously in the main scanning direction The color of 1 above The ratio of ink dots is controlled to be greater than that of the highlight gradation, and in the shadow gradation shown in the print data, out of all positions on one line in the main scanning direction on the recording medium, one scan of the ejection head and another scan of the recording medium occur at the same coordinate on the recording medium. The color of 1 above The invention is characterized by controlling the proportion of overlapping ink dots that are ejected to be greater than the gradation on the highlight side. [Effects of the Invention]

[0008] According to the present invention, it is possible to achieve an intermediate texture that balances granularity and resistance to banding. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an external perspective view of a liquid dispensing device according to an embodiment. [Figure 2] Figure 2 shows an example of the main components of a liquid dispensing device according to the embodiment. [Figure 3] Figure 3 shows an example of the heater configuration of a liquid dispensing device according to the present invention. [Figure 4] Figure 4 shows an example of the hardware configuration of a liquid dispensing device according to the embodiment. [Figure 5]Figure 5 illustrates how the discharge characteristics are changed according to the grayscale in the liquid dispensing device according to the embodiment. [Figure 6] Figure 6 illustrates the distinction between the dot portions of each scan in the case of 1 / 6 interlacing and 2-pass in the liquid dispensing device according to the embodiment. [Figure 7] Figure 7 shows an example of a dot pattern in a conventional liquid dispensing device. [Figure 8] Figure 8 shows an example of a dot pattern produced by continuous discharge control of a liquid dispensing device according to an embodiment. [Figure 9] Figure 9 shows an example of a dot pattern obtained by dot overlapping control of a liquid dispensing device according to the embodiment. [Figure 10] Figure 10 shows an example of the configuration of the functional block of the control unit of the liquid dispensing device according to the embodiment. [Figure 11] Figure 11 is a flowchart showing an example of the image processing and printing process flow of a liquid dispensing apparatus according to an embodiment. [Figure 12] Figure 12 shows an example of a dither mask used in the halftone processing of a liquid dispensing apparatus according to the embodiment. [Figure 13] Figure 13 illustrates the printing process for 100% grayscale image data in a liquid dispensing device according to an embodiment. [Figure 14] Figure 14 illustrates the printing process for 50% grayscale image data in a liquid dispensing device according to an embodiment. [Figure 15] Figure 15 is a flowchart showing an example of the flow of the mask setting process for a liquid dispensing device according to an embodiment. [Figure 16] Figure 16 illustrates the first loop of the iterative process for setting the mask of the liquid dispensing device according to the embodiment. [Figure 17] Figure 17 illustrates the second loop of the iterative process for setting the mask of the liquid dispensing device according to the embodiment. [Figure 18]Figure 18 illustrates the third loop of the iterative process for setting the mask of the liquid dispensing device according to the embodiment. [Figure 19] Figure 19 illustrates the fourth loop of the iterative process for setting the mask of the liquid dispensing device according to the embodiment. [Modes for carrying out the invention]

[0010] The liquid dispensing device, liquid dispensing method, and program according to the present invention will be described in detail below with reference to the attached drawings. Furthermore, the present invention is not limited by the following embodiments, and the components in the following embodiments include those that are easily conceivable to those skilled in the art, substantially identical, and so-called equivalents. Moreover, various omissions, substitutions, modifications, and combinations of components can be made without departing from the spirit of the following embodiments.

[0011] In addition, computer software refers to programs related to the operation of a computer, as well as other information used for processing by a computer that conforms to a program (hereinafter, computer software is referred to as software). Application software is a general term for software used to perform specific tasks among the classifications of software. On the other hand, an operating system (OS) is software that controls a computer and enables application software and the like to utilize computer resources. The operating system performs basic management and control of a computer, such as control of input / output, management of hardware such as memory and hard disks, and management of processes. Application software operates by utilizing the functions provided by the operating system. A program is a command for a computer, which is combined so that a single result can be obtained. In addition, what conforms to a program refers to something that does not constitute a direct command for a computer and thus cannot be called a program, but has properties similar to those of a program in terms of defining computer processing. For example, a data structure (a logical structure of data represented by the mutual relationship between data elements) corresponds to something that conforms to a program.

[0012] (Overall Configuration of Liquid Discharge Device) FIG. 1 is an external perspective view of a liquid discharge device according to an embodiment. FIG. 2 is a diagram showing an example of the main part configuration of the liquid discharge device according to the embodiment. The overall configuration of the liquid discharge device 1 according to the present embodiment will be described while referring to FIGS. 1 and 2.

[0013] The liquid discharge device 1 according to the present embodiment is a multi-pass serial printer. Note that the liquid discharge device 1 may be a small inkjet serial printer or a laminated printing printer, etc., as long as it is a multi-pass system. As shown in FIGS. 1 and 2, the liquid discharge device 1 includes a device main body 10, a support base 11 that supports the device main body 10, and a control unit 100.

[0014] As shown in Figures 1 and 2, the main body of the device 10 includes a cartridge loading section 2, a maintenance and recovery mechanism 3, side plates 10a and 10b, a guide rod 12, a guide stay 13, a sub-sheet metal guide 14, a carriage 15, a main scanning mechanism 16, an optical sensor 21, liquid discharge heads 23a, 23b and 23c (discharge heads), a supply tube 24, a paper feeding means 40, a transport guide plate 191, and a platen 192.

[0015] The cartridge loading section 2 is a loading section that can detachably install ink cartridges 22a, 22b, and 22c of each color. When referring to any of the ink cartridges 22a, 22b, and 22c, or collectively, they shall simply be referred to as "ink cartridge 22". The ink filled in the ink cartridges 22 is supplied to the sub-tanks of the carriage 15 via supply tubes 24 of each color by a supply pump unit (not shown). The ink cartridges 22 may also include ink cartridges of other colors, such as white.

[0016] The maintenance and recovery mechanism 3 is a mechanism for maintaining and recovering the state of the liquid discharge heads 23a, 23b, and 23c, which are mounted in the non-printing area on one side of the carriage 15 in the main scanning direction. The maintenance and recovery mechanism 3 includes a cap 31 for capping the nozzle surfaces of each of the liquid discharge heads 23a, 23b, and 23c, and a wiping unit 32 for wiping the nozzle surfaces. A replaceable waste liquid tank for containing the waste liquid generated by the maintenance and recovery operation is provided below the maintenance and recovery mechanism 3.

[0017] The side plates 10a, 10a are plate members for which the guide rod 12 and guide stay 13, which are guide members, are to be placed.

[0018] The guide rod 12 and guide stay 13 are guide members that slidably hold the carriage 15 in the main scanning direction. The sub-sheet metal guide 14 is a guide member that supports the back surface of the device body 10.

[0019] The carriage 15 is a component that moves in the main scanning direction (direction A shown in Figure 1) by the main scanning mechanism 16. Specifically, the carriage 15 moves in the main scanning direction via a timing belt 20 that is rotationally driven by the main scanning motor 17. The carriage 15 is also equipped with sub-tanks to supply ink of each color to the liquid discharge heads 23a, 23b, and 23c.

[0020] The main scanning mechanism 16 is a mechanism that moves the carriage 15 back and forth in the main scanning direction (direction A). As shown in Figure 1, the main scanning mechanism 16 includes a main scanning motor 17, a drive pulley 18, a driven pulley 19, and a timing belt 20.

[0021] The main scanning motor 17 is located on one side of the main scanning direction and is a motor that rotates the timing belt 20. The drive pulley 18 is a pulley on which the timing belt 20 is stretched and is rotationally driven by the main scanning motor 17. The driven pulley 19 is a pulley on which the timing belt 20 is stretched and is located on the other side of the main scanning direction. The driven pulley 19 is tensioned outward (away from the drive pulley 18) by a tension spring. The timing belt 20 is a traction member that is stretched between the drive pulley 18 and the driven pulley 19 and rotates by the rotational drive of the main scanning motor 17.

[0022] The optical sensor 21 is installed on the carriage 15 and is an optical sensor that detects the edge of the paper 41 (recording medium).

[0023] The liquid ejection heads 23a, 23b, and 23c are mounted on the carriage 15 and are recording heads that eject ink of each color, such as black (K), yellow (Y), magenta (M), and cyan (C), from their nozzle rows, depending on the ink cartridge 22. When referring to any of the liquid ejection heads 23a, 23b, and 23c, or collectively, they will simply be referred to as "liquid ejection head 23". The liquid ejection head 23 has multiple nozzle rows arranged in the B direction (sub-scanning direction). Here, the sub-scanning direction is the direction in which the paper 41 is transported (direction B shown in Figure 1), and is perpendicular to the main scanning direction. The liquid ejection head 23 is installed on the carriage 15 such that the ink ejection direction from the nozzle rows is downward (towards the paper 41). The liquid ejection heads 23a, 23b, and 23c are each installed offset in the sub-scanning direction.

[0024] The supply tube 24 is a tube for supplying the ink filled in the ink cartridge 22 to the sub-tank of the carriage 15.

[0025] The paper feeding means 40 is a mechanism for transporting the paper 41 on the platen 192 in the sub-scanning direction.

[0026] The transport guide plate 191 is a guide member that guides the paper 41 as it is transported on the platen 192. The platen 192 is the component on which the paper 41 is transported by the paper feeding means 40.

[0027] The control unit 100 is a controller that controls the operation of the liquid dispensing device 1. In Figure 2, the control unit 100 is shown outside the main body of the device 10, but it may also be mounted inside the main body of the device 10, or it may be a separate external device from the liquid dispensing device 1.

[0028] (Heater configuration of liquid dispensing device) Figure 3 shows an example of the heater configuration of the liquid dispensing device according to this embodiment. The heater configuration of the liquid dispensing device 1 according to this embodiment will be described with reference to Figure 3. In the example shown in Figure 3, some of the liquid dispensing heads 23 have been omitted from the description in order to simplify the explanation.

[0029] As shown in Figure 3, the liquid dispensing device 1 includes a conveyor roller 160, a fan 180, and a heater 190.

[0030] The transport rollers 160 are a pair of rollers for transporting the recording medium P (corresponding to the paper 41 shown in Figure 1) from the transport guide plate 191 to the platen 192 in the sub-scanning direction (direction B). Once the recording medium P is transported onto the platen 192 by the transport rollers 160, an image is formed by the ejection of ink from the liquid ejection head 23.

[0031] The fan 180 is a blower that promotes convection of air inside the liquid discharge device 1 and prevents excessive temperature rise due to the stagnation of heated air at the top of the liquid discharge device 1.

[0032] The heater 190 includes a preheater 190a, print heaters 190b and 190c, a postheater 190d, and a drying heater 190e. Each of these heaters is equipped with a temperature sensor, such as a thermistor, for temperature control.

[0033] The preheater 190a is a heater that preheats the recording medium P to a temperature suitable for image formation. For example, the preheater 190a is an aluminum foil cord heater. The preheater 190a is installed on the back surface of the transport guide plate 191 upstream of the platen 192, and heats the recording medium P by heating the transport guide plate 191 itself.

[0034] The print heaters 190b and 190c are heaters that keep the recording medium P warm when an image is formed on the recording medium P. For example, the print heaters 190b and 190c are cord heaters embedded in the platen 192, which is made of aluminum. The print heaters 190b and 190c warm the recording medium P by warming the platen 192 itself.

[0035] The post-heater 190d is a heater that warms the image-formed recording medium P in order to dry and fix the ink. For example, the post-heater 190d is an aluminum foil cord heater. The post-heater 190d is installed on the back surface of the transport guide plate 191 downstream of the platen 192, and warms the recording medium P by warming the transport guide plate 191 itself.

[0036] The drying heater 190e is a heater that warms the image-formed recording medium P in order to dry and fix the ink. For example, the drying heater 190e is an infrared heater. The drying heater 190e dries the recording medium P by emitting infrared rays onto the image-forming surface. The drying heater 190e may also be configured to include a fan to blow hot air onto the image-forming surface of the recording medium P.

[0037] (Hardware configuration of the liquid dispensing device) Figure 4 shows an example of the hardware configuration of the liquid dispensing device according to this embodiment. The hardware configuration of the liquid dispensing device 1 according to this embodiment will be described with reference to Figure 4.

[0038] As shown in Figure 4, the liquid dispensing device 1 includes a control unit 100, an operation panel 120, a sensor 130, a head driver 140, a main scanning motor 17, a sub-scanning motor 150, a fan 180, and a heater 190.

[0039] The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an NVRAM (Non-Volatile RAM) 104, an ASIC (Application Specific Integrated Circuit) 105, a printing control unit 106, a motor drive unit 107, an I / O 108, a host I / F 109, a fan control unit 110, and a heater control unit 111.

[0040] The CPU 101 is an arithmetic unit that controls the entire liquid dispensing device 1. The ROM 102 is a non-volatile memory device that stores fixed data such as programs executed by the CPU 101. The RAM 103 is a volatile memory device that serves as the work area for arithmetic processing by the CPU 101. The RAM 103 also temporarily stores image data and other data.

[0041] NVRAM104 is a non-volatile memory device that retains data even when the power supply to the liquid dispensing device 1 is cut off. ASIC105 is an integrated circuit that processes various signal processing and sorting operations on image data, as well as input / output signals for controlling the entire liquid dispensing device 1.

[0042] The print control unit 106 is a control circuit that controls the ejection operation of the liquid ejection head 23 via the head driver 140. The print control unit 106 transfers data for driving the liquid ejection head 23 to the head driver 140. For example, the print control unit 106 transfers image data as serial data and outputs a transfer clock, latch signal, control signal, etc., required for transferring the image data to the head driver 140. Based on the image data corresponding to one line of the liquid ejection head 23 that is input serially, the head driver 140 selectively supplies drive pulses that constitute the drive waveform received from the print control unit 106 to the pressure generating means of the liquid ejection head 23, thereby driving the liquid ejection head 23 and ejecting ink. By selecting some or all of the pulses that constitute the drive waveform, or some or all of the waveform elements that form the pulses, it is possible to print dots of different sizes, such as large, medium, and small droplets.

[0043] The motor drive unit 107 is a drive circuit that controls the operation of the main scanning motor 17 and the sub-scanning motor 150. The main scanning motor 17 moves the carriage 15 in the main scanning direction according to the control of the motor drive unit 107. The sub-scanning motor 150 rotates the transport roller 160 to transport the recording medium P in the sub-scanning direction according to the control of the motor drive unit 107.

[0044] I / O108 is an interface circuit for acquiring information from sensor 130 and extracting information used for controlling each part of the liquid dispensing device 1. Sensor 130 is a group of sensors such as a photosensor, temperature sensor, and encoder sensor.

[0045] The host I / F 109 is an interface circuit that transmits and receives data and signals between the host 170, which is an information processing device such as a client PC (Personal Computer), an image reading device, or an imaging device. Specifically, the host I / F 109 transmits and receives data and signals from the host 170 via cable or network. The print data stored in the host I / F 109's receive buffer is analyzed by the CPU 101, image processing and data rearrangement are performed by the ASIC 105, and the print control unit 106 transfers it to the head driver 140 as ejection data.

[0046] The fan control unit 110 is a control circuit that controls the output of the fan 180 so that air is blown at a predetermined temperature and volume.

[0047] The heater control unit 111 is a control circuit that controls the heater 190 to reach a set temperature.

[0048] The control panel 120 is a device for inputting and outputting various types of information.

[0049] Note that the hardware configuration of the liquid dispensing device 1 shown in Figure 4 is an example, and it is not necessary to include all of the components shown in Figure 4, or other components may be included.

[0050] Furthermore, the configuration is not limited to transporting the recording medium P in the sub-scanning direction by the sub-scanning motor 150. The carriage 15 may be moved not only in the main scanning direction but also in the sub-scanning direction. In other words, the configuration may alternately perform the operation of ejecting ink when the carriage 15 moves in the main scanning direction and the operation of moving the carriage 15 by a predetermined amount in the sub-scanning direction.

[0051] (Operation overview of the liquid dispensing device) Figure 5 illustrates how the dispensing characteristics are changed according to the grayscale in the liquid dispensing device according to the embodiment. Figure 6 illustrates how the dot portions of each scan are distinguished in the case of 1 / 6 interlacing and 2-pass in the liquid dispensing device according to the embodiment. Figure 7 shows an example of a dot pattern of a conventional liquid dispensing device. Figure 8 shows an example of a dot pattern by continuous dispensing control of the liquid dispensing device according to the embodiment. Figure 9 shows an example of a dot pattern by dot overlapping control of the liquid dispensing device according to the embodiment. Referring to Figures 5 to 9, an overview of the operation of the liquid dispensing device 1 according to this embodiment will be described.

[0052] In this embodiment, the printing conditions for the liquid ejection device 1 will be described as, for example, a 1 / 6 interlace and 2-pass method, i.e., an operation in which an image is formed by scanning 12 times. Figure 6 shows the distinction of gradation in the dot portion in each scan (scan (1) to scan (12)) of the 12 scans, indicated by the shades of gray. In this case, in the prior art, in order to prioritize frequency characteristics, as shown in Figure 7, the printing is granular with a 1-on-1-off base from the highlight side to the shadow side of the gradation. However, if the ink landing is off-target, the coverage rate decreases, leading to banding. In particular, the effect of banding is greater on the shadow side, where the proportion of the image filled with dots is relatively large, than on the highlight side, where the proportion is relatively small.

[0053] Therefore, in the liquid ejection device 1 according to this embodiment, in the shadow side where banding is likely to occur, the image is formed by a halftone dot pattern with banding resistance. On the highlight side, where banding hardly occurs, the image is formed by a halftone dot pattern that has excellent frequency characteristics and is specialized for granularity. In other words, as shown in Figure 5, the liquid ejection device 1 according to this embodiment performs image formation that prioritizes banding resistance as it moves towards the shadow side, and image formation that prioritizes granularity as it moves towards the highlight side. Specifically, in order to perform image formation that prioritizes banding resistance on the shadow side, the liquid ejection device 1 performs the following two types of ink ejection control.

[0054] First, as the first ink ejection control, the liquid ejection device 1 performs control on the shadow side to make the dot pattern continuous with each scan in order to improve banding resistance (hereinafter sometimes referred to as continuous ejection control). Specifically, as shown in Figure 8, the liquid ejection device 1 controls the ratio of the number of dots ejected continuously in the main scanning direction on the recording medium to the total number of ink dots ejected onto the recording medium in one scan on the shadow side to be greater than on the highlight side. As a result, granularity is ensured on the highlight side, while on the shadow side, banding resistance can be improved by the continuity of the dot pattern due to the continuous ejection control.

[0055] Next, as a second ink ejection control, the liquid ejection device 1 utilizes a multi-pass printing function to eject multiple ink dots at the same coordinate position on the recording medium on the shadow side (hereinafter sometimes referred to as overlapping ejection control). Specifically, as shown in Figure 9, the liquid ejection device 1 controls the shadow side so that the proportion of positions on the recording medium where ink dots are ejected at the same coordinate position on the recording medium in one scan and another scan is greater than on the highlight side. As a result, on the shadow side, the overlapping ejection control improves robustness against deviations in the landing position of the ink dots and improves resistance to banding.

[0056] As described above, the liquid dispensing device 1 according to this embodiment performs continuous dispensing control and overlapping control according to the gradation of the input print image (image data), thereby ensuring granularity on the highlight side and improving panning resistance on the shadow side. The configuration and operation of the functional blocks for realizing this control of the liquid dispensing device 1 will be described in detail below.

[0057] (Configuration and operation of the functional block of the liquid dispensing device's control unit) Figure 10 shows an example of the configuration of the functional block of the control unit of the liquid dispensing device according to this embodiment. The configuration and operation of the functional block of the control unit 100 of the liquid dispensing device 1 according to this embodiment will be described with reference to Figure 10.

[0058] As shown in Figure 10, the control unit 100 of the liquid dispensing device 1 includes a master setting unit 201, an acquisition unit 202, an image processing unit 203, and an output unit 204.

[0059] The master setting unit 201 is a functional unit that sets the dither mask used in the halftone processing in image processing by the acquisition unit 202, which will be described later. By performing halftone processing using the dither mask set by the master setting unit 201, it becomes possible to generate dot data (print data) that realizes the continuous ejection control and overlapping print control described above. The mask setting process for setting the dither mask by the master setting unit 201 will be described later in Figures 15 to 19.

[0060] The acquisition unit 202 is a functional unit that acquires print jobs containing image data from a host 170 such as a client PC via the host I / F 109. The acquisition unit 202 outputs the image data contained in the acquired print job to the image processing unit 203.

[0061] The image processing unit 203 is a functional unit that performs image processing to convert image data output from the acquisition unit 202 into dot data (dot pattern) for printing. In the halftone processing of image processing, the image processing unit 203 uses the dither mask set by the master setting unit 201. The image processing unit 203 outputs the dot data generated by image processing to the output unit 204. The image processing by the image processing unit 203 will be described later in Figure 11.

[0062] The output unit 204 is a functional unit that outputs the dot data output from the image processing unit 203 to the print control unit 106 and the motor drive unit 107.

[0063] The master setting unit 201, acquisition unit 202, image processing unit 203, and output unit 204 described above are implemented, for example, by a program executed by the CPU 101 shown in Figure 4. Note that some or all of these functional units may be implemented not by a software program, but by hardware circuits (integrated circuits) such as FPGAs (Field-Programmable Gate Arrays) or ASICs.

[0064] Furthermore, the functional units of the control unit 100 of the liquid dispensing device 1 shown in Figure 10 are conceptual representations of their functions and are not limited to this configuration. For example, the multiple functional units shown as independent functional units in the control unit 100 of the liquid dispensing device 1 shown in Figure 10 may be configured as a single functional unit. On the other hand, the functions of a single functional unit in the control unit 100 of the liquid dispensing device 1 shown in Figure 10 may be divided into multiple functions and configured as multiple functional units.

[0065] Furthermore, the functional unit that controls the print control unit 106 and the functional unit that controls the motor drive unit 107 may be implemented by program execution, and the print control unit 106 and the motor drive unit 107 themselves may be implemented by program execution.

[0066] (Image processing and printing process flow for liquid dispensing equipment) Figure 11 is a flowchart showing an example of the image processing and printing process flow of the liquid dispensing apparatus according to the embodiment. Figure 12 is a diagram showing an example of a dither mask used in halftone processing of the liquid dispensing apparatus according to the embodiment. Figure 13 is a diagram illustrating the printing process for 100% grayscale image data in the liquid dispensing apparatus according to the embodiment. Figure 14 is a diagram illustrating the printing process for 50% grayscale image data in the liquid dispensing apparatus according to the embodiment. The image processing and printing process flow of the liquid dispensing apparatus 1 according to this embodiment will be explained with reference to Figures 11 to 14. It is assumed that a dither mask, such as the one shown in Figure 12, has been set in advance by the master setting unit 201 as a dither mask to realize the continuous dispensing control and overlapping control described above.

[0067] <Step S1> The acquisition unit 202 of the control unit 100 of the liquid dispensing device 1 acquires (inputs) a print job including image data (print image) from a host 170 such as a client PC via the host I / F 109. Here, the image data acquired by the acquisition unit 202 is, for example, sRGB or AdobeRGB RGB data. The acquisition unit 202 outputs the image data included in the acquired print job to the image processing unit 203. Then, the process proceeds to step S2.

[0068] <Step S2> The image processing unit 203 performs an image resolution scaling process, which scales the resolution of the image data received from the acquisition unit 202 to a resolution corresponding to the liquid discharge device 1. For example, the image processing unit 203 converts the image data from a resolution of 72 [dpi] to a resolution of 600, 1200, or 2400 [dpi] through the image resolution scaling process. Then, the process proceeds to step S3.

[0069] <Step S3> The image processing unit 203 performs a color matching process to convert the image data (RGB data) whose resolution has been scaled by the image resolution scaling process into CMYK data or CMYKOG data in a color space that can be handled by the print control unit 106. This color matching process ensures consistent color reproduction even when using printers or recording media with different color reproduction characteristics. Then, the process proceeds to step S4.

[0070] <Step S4> The image processing unit 203 performs gamma correction processing, which is a fine-tuning of the color (gradation correction) according to the output characteristics of the head driver 140 and the liquid ejection head 23, on the CMYK data or CMYKOG data obtained by the color matching process. The data generated by the gamma correction processing is set to CMYK data or CMYKOG data. Then, the process proceeds to step S5.

[0071] <Step S5> The image processing unit 203 performs an image rendering process that converts the CMYK data or CMYKOG data obtained by gamma correction processing into grayscale data that determines how to move the liquid ejection head 23 and the recording medium P and which nozzle to eject the ink from. Then, it proceeds to step S6.

[0072] <Step S6> The image processing unit 203 performs halftone processing, converting the gradation data obtained from the image rendering process into dot data using a dither mask set by the master setting unit 201 (for example, the dither mask shown in Figure 12). For example, the image processing unit 203 converts 8-16 bit gradation data into 1-2 bit quantized dot data through halftone processing. The image processing unit 203 outputs the dot data generated by the halftone processing to the output unit 204. Then, the process proceeds to step S7.

[0073] <Step S7> The output unit 204 outputs the dot data output from the image processing unit 203 to the print control unit 106 and the motor drive unit 107. The print control unit 106 controls the ejection operation of the liquid ejection head 23 via the head driver 140 based on the dot data output from the output unit 204. The motor drive unit 107 also controls the movement of the carriage 15 on which the liquid ejection head 23 is mounted in the main scanning direction and controls the transport of the recording medium P in the sub-scanning direction based on the dot data.

[0074] Here, we will describe the printing process performed on the recording medium P using dot data obtained by image processing including halftone processing using the dither mask shown in Figure 12. In the matrix showing the dither mask shown in Figure 12, "-1" indicates an unused flag. Here, the liquid ejection device 1 is described as performing image formation using a 1 / 2 interlace and 2-pass method, i.e., by scanning four times, as the printing conditions.

[0075] First, the example shown in Figure 13 describes the operation when image data with 100% gradation (i.e., shadow gradation, with a gradation value of 255) is input, halftone processing is performed by the dither mask shown in Figure 12, and printing is performed using the resulting dot data. The nozzle row of the liquid ejection head 23 is assumed to consist of 10 nozzles, Nos. 1 to 10. First, in scan (1), the threshold value of the dither mask corresponding to each nozzle Nos. 1 to 3 is compared with the gradation value of the image data line corresponding to each nozzle. In the line where the value is greater than the threshold, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. In the example shown in Figure 13, for printing shadow gradation, as shown in Figure 13, the continuous ejection control described above results in a portion where ink dots are continuously ejected on the same line. After ink ejection by scan (1), the recording medium P is transported 5 pixels in the transport direction (sub-scanning direction) according to the 1 / 2 interlace and 2-pass method.

[0076] Next, in scan (2), the threshold value of the dither mask corresponding to each nozzle No. 1 to 5 is compared with the grayscale value of the line in the image data corresponding to each nozzle. In the line where the value is greater than the threshold value, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. After the ink is ejected by scan (2), the recording medium P is similarly transported by 5 pixels in the transport direction (sub-scanning direction).

[0077] Next, in scan (3), the threshold value of the dither mask corresponding to each nozzle No. 2 to 8 is compared with the grayscale value of the line in the image data corresponding to each nozzle. In the line where the value is greater than the threshold value, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. In the example shown in Figure 13, for printing the grayscale on the shadow side, as a result of the overlapping control described above, as shown in Figure 13, an area is formed where ink dots are ejected in overlapping positions (hatched area in Figure 13). After the ink ejection by scan (3), the recording medium P is similarly transported by 5 pixels in the transport direction (sub-scanning direction).

[0078] Then, in scan (4), the threshold value of the dither mask corresponding to each nozzle No. 5 to 10 is compared with the grayscale value of the line in the image data corresponding to each nozzle. In the line where the value is greater than the threshold value, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. In this way, the formation of an image for 5 lines on the recording medium P is completed by the 4 scans from scan (1) to scan (4). Subsequently, the image is formed by ejecting ink onto the recording medium P through a similar operation. As a result, as shown in Figure 13, for the grayscale image data on the shadow side, the proportion of areas where dots are continuous and areas where dots are ejected overlapping at the same position is greater than on the highlight side due to continuous ejection control and overlapping ejection control, thereby improving banding resistance.

[0079] Next, the example shown in Figure 14 describes the operation when image data with 50% gradation (i.e., a gradation between the shadow and highlight sides, with a gradation value of 128) is input, halftone processing is performed by the dither mask shown in Figure 12, and printing is performed using the resulting dot data. First, in scan (1), the threshold value of the dither mask corresponding to each nozzle No. 1 to 3 is compared with the gradation value of the line in the image data corresponding to each nozzle. In the line where the value is greater than the threshold value, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. In the example shown in Figure 14, because the printing is of a gradation between the shadow and highlight sides, as shown in Figure 14, at this point, no area where ink dots are continuously ejected on the same line is formed. After the ink is ejected by scan (1), the recording medium P is transported by 5 pixels in the transport direction (sub-scanning direction) according to the 1 / 2 interlace and 2-pass method.

[0080] Next, in scan (2), the threshold value of the dither mask corresponding to each nozzle No. 1 to 5 is compared with the grayscale value of the line in the image data corresponding to each nozzle. In the line where the value is greater than the threshold value, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. As shown in Figure 14, even at this point, no area where ink dots are ejected continuously on the same line has been formed. After the ink ejection by scan (2), the recording medium P is similarly transported by 5 pixels in the transport direction (sub-scanning direction).

[0081] Next, in scan (3), the threshold value of the dither mask corresponding to each nozzle No. 2 to 8 is compared with the grayscale value of the line in the image data corresponding to each nozzle. In the line where the value is greater than the threshold value, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. As shown in Figure 14, at this point, a section is formed in the same line where ink dots are ejected continuously (at the threshold values ​​"32" and "208" for nozzle No. 7). After the ink ejection by scan (3), the recording medium P is similarly transported in the transport direction (sub-scanning direction) by 5 pixels.

[0082] Then, in scan (4), the threshold value of the dither mask corresponding to each nozzle No. 5 to 10 is compared with the grayscale value of the line in the image data corresponding to each nozzle. At the position on the line where the value is greater than the threshold value, the liquid ejection head 23 moves in the head scanning direction (main scanning direction) and ejects ink from each nozzle. In this way, the formation of an image for 5 lines on the recording medium P is completed by the 4 scans from scan (1) to scan (4). Subsequently, the image is formed by ejecting ink onto the recording medium P through a similar operation. As shown in Figure 14, at this point, the area where ink dots are ejected continuously on the same line has increased compared to scan (3), but it is still less than the area where dots are ejected continuously as shown in Figure 13 above. Also, because of the printing of grayscales between the shadow and highlight sides, as shown in Figure 14, at this point as well, no area where ink dots are ejected overlapping at the same position has been formed.

[0083] In this way, continuous output control and overprinting control are performed according to the gradation of the input image data, ensuring granularity on the highlight side and improving panning resistance on the shadow side.

[0084] (Flowchart for setting the mask of a liquid dispensing device) Figure 15 is a flowchart illustrating an example of the mask setting process flow of the liquid dispensing device according to the embodiment. Figure 16 is a diagram illustrating the first loop of the iterative process of the mask setting process of the liquid dispensing device according to the embodiment. Figure 17 is a diagram illustrating the second loop of the iterative process of the mask setting process of the liquid dispensing device according to the embodiment. Figure 18 is a diagram illustrating the third loop of the iterative process of the mask setting process of the liquid dispensing device according to the embodiment. Figure 19 is a diagram illustrating the fourth loop of the iterative process of the mask setting process of the liquid dispensing device according to the embodiment. Referring to Figures 15 to 19, the flow of the mask setting process flow for setting the dither mask used in the halftone process to realize the printing process by continuous dispensing control and overlapping control described above in the liquid dispensing device 1 according to this embodiment will be explained. Here, as shown in Figure 16, the operation of setting the dither mask from a mask matrix with dimensions of 4 horizontally and 10 vertically will be explained.

[0085] <Step S11> The master setting unit 201 of the control unit 100 of the liquid dispensing device 1 performs initialization processing on the mask matrix for setting the dither mask. Specifically, as shown in Figure 16, the master setting unit 201 resets the mask threshold used to set the threshold for the mask matrix to 0, and sets each component constituting the mask matrix to "-1", which indicates an unused flag. Then, it proceeds to steps S12, S14, and S16.

[0086] <Step S12> The master setting unit 201 generates a full scan image (first image) using a mask matrix. Here, the full scan image refers to dot data of the size of an image completed by four scans by a liquid discharge head 23 having 10 nozzles using a 1 / 2 interlace and two-pass method. Specifically, it is dot data with 4 horizontal and 5 vertical pixels, consisting of the first line printed by nozzles No. 1 and No. 6 in two passes, the second line printed by nozzles No. 4 and No. 9 in two passes, the third line printed by nozzles No. 2 and No. 7 in two passes, the fourth line printed by nozzles No. 5 and No. 10 in two passes, and the fifth line printed by nozzles No. 3 and No. 8 in two passes. The master setting unit 201 generates the full scan image by placing dots at pixels corresponding to thresholds set in the mask matrix. In the example shown in Figure 16, all components of the mask matrix initialized in step S11 are set to "-1", indicating an unused flag. Therefore, the full scan image contains dot data with no dots placed in it. Then, the process proceeds to step S13.

[0087] <Step S13> The master setting unit 201 calculates a score (first score) for the dot placement candidates using the generated full scan image. Specifically, the master setting unit 201 uses the distance (e.g., Manhattan distance) from the dots placed in the full scan image generated in step S12 as the score and places it on the corresponding pixels in the full scan image. In the example shown in Figure 16, since no dots are placed in the full scan image generated in step S12, the master setting unit 201 places 0 as the score to be placed on each pixel in the full scan image. Then, the process proceeds to step S17.

[0088] <Step S14> The master setting unit 201 generates a scan unit image (second image) using a mask matrix. Here, the scan unit image refers to dot data with an image size corresponding to the size of the mask matrix (width: 4, height: 10). The master setting unit 201 generates the scan unit image by placing dots on pixels corresponding to the threshold set in the mask matrix. In the example shown in Figure 16, all components of the mask matrix initialized in step S11 are set to "-1", indicating an unused flag, so the scan unit image will be dot data with no dots placed on it. Then, the process proceeds to step S15.

[0089] <Step S15> The master setting unit 201 calculates a score (second score) for the dot placement candidates using the generated scan unit image. Specifically, the master setting unit 201 uses the distance from the dots placed in the scan unit image generated in step S14 (for example, the Manhattan distance) as the score and places it on the corresponding pixels in the scan unit image. In the example shown in Figure 16, since no dots are placed in the scan unit image generated in step S14, the master setting unit 201 places 0 as the score to be placed on each pixel in the scan unit image. Then, the process proceeds to step S17.

[0090] <Step S16> The master setting unit 201 calculates the banding resistance score (third score) using the mask matrix. Specifically, in an image the same size as the scan unit image (third image), the master setting unit 201 places a score of 1 on the pixels adjacent to each threshold set in the mask matrix in the main scanning direction, and places 0 on all other pixels. Note that the scores placed on adjacent pixels are not limited to 1, and scores of other values ​​may be placed. Then, the process proceeds to step S17.

[0091] In other words, steps S12 and S13, steps S14 and S15, and step S16 are executed as parallel processes.

[0092] <Step S17> The master setting unit 201 sums the scores for the dot placement candidates based on the entire scan image calculated in step S13, the scores for the dot placement candidates based on the scan unit image calculated in step S15, and the banding resistance score calculated in step S16 for each corresponding pixel. In the example shown in Figure 16, the master setting unit 201 finds that the scores for the dot placement candidates based on the entire scan image, the scores for the dot placement candidates based on the scan unit image, and the banding resistance score are all 0, so the sum of the scores for each corresponding pixel is also 0. Then, the process proceeds to step S18.

[0093] <Step S18> The master setting unit 201 determines the position of the dot to be placed at the location with the highest score among the summed scores. In the example shown in Figure 16, since all the summed scores are 0, the master setting unit 201 determines the position of an arbitrary pixel (the lower left pixel in the example of Figure 16) to be placed as the dot. Of the summed scores, for the banding resistance score in step S16, a score of 1 is placed at the pixels adjacent to each threshold pixel in the main scanning direction. Therefore, as the master threshold increases, the likelihood of new thresholds being set adjacent to the threshold increases. Consequently, when ink dots are ejected onto the recording medium P, the frequency of dots being ejected consecutively and dots being ejected overlapping at the same coordinate positions increases on the shadow side. Then, the process proceeds to step S19.

[0094] <Step S19> The master setting unit 201 updates the mask matrix by placing a mask threshold in the component of the mask matrix corresponding to the dot placement position determined in step S18. In the example shown in Figure 16, the master setting unit 201 determined the position of the lower left pixel to be the dot placement position, so as shown in Figure 17, it updates the mask matrix by placing a mask threshold "0" in the component of the mask matrix corresponding to that dot placement position. Then, it proceeds to step S20.

[0095] <Step S20> The master setting unit 201 increments the current mask threshold to create a new mask threshold. In the example shown in Figure 17, the master setting unit 201 set the mask threshold "0" in the mask matrix in step S19, so it increments it to "1" to create a new mask threshold. Then it proceeds to step S21.

[0096] <Step S21> The master setting unit 201 determines whether the current mask threshold has reached its maximum value. If the mask threshold has reached its maximum value (step S21: Yes), the master setting unit 201 sets the mask matrix, which has been updated by the mask threshold, as the final dither mask. On the other hand, if the mask threshold has not reached its maximum value (step S21: No), the process returns to steps S12, S14, and S16.

[0097] Thus, after the initialization process in step S11, the dither mask is completed by repeatedly performing steps S12 to S21 to set incremented thresholds on the mask matrix. The operation shown in Figures 17 to 19 shows the state in which, after the positions of the dot placements were determined in Figure 16 and thresholds were set on the components of the mask matrix corresponding to those positions, the incremented thresholds are sequentially set on the mask matrix by repeatedly performing steps S12 to S21. In steps S13 and S15, the distance from the placed dot is used as the score, but this is not limited to this, and the score may be calculated using a filter that has a high correlation with granularity. In addition, the banding resistance score is calculated by placing a score of 1 on the pixels adjacent to the pixels in the main scanning direction of the pixel corresponding to the threshold set in the mask matrix, but the score may be calculated by taking other factors into consideration. Also, in the summation of scores in step S17, the scores calculated in steps S13, S15 and S16 are simply added together, but this is not limited to this, and the calculated scores may be weighted before summation. For example, in the highlight stage with a low number of repetitions (steps S12-S21), the weight of the banding resistance score may be reduced, while in the shadow stage with a high number of repetitions, the weight of the banding resistance score may be increased, and these values ​​may be added together. This makes it possible to set the dither mask to further improve granularity on the highlight side and further improve panning resistance on the shadow side.

[0098] As described above, in the liquid ejection device 1 according to this embodiment, one line in the main scanning direction on the recording medium P is formed by the ejection of ink from the nozzle during multiple scans in the main scanning direction of the liquid ejection head 23, the acquisition unit 202 acquires image data to be printed, the image processing unit 203 generates dot data by halftone processing using a dither mask on the image data, and the control unit 100 controls the movement of the liquid ejection head 23 and the ejection of ink based on the dot data, the liquid ejection head 23 is controlled so that the number of ink dots ejected continuously in the main scanning direction is greater than the number of ink dots ejected in the highlight side gradation in the shadow side gradation indicated by the dot data, and the liquid ejection head 23 is controlled so that the number of positions in which ink dots are ejected overlapping at the same coordinate position on the recording medium P is greater than the number of ink dots ejected in the highlight side gradation in the shadow side gradation indicated by the dot data. More specifically, the control unit 100 controls the shadow-side gradation indicated by the dot data so that, for one line in the main scanning direction on the recording medium P, the ratio of ink dots ejected continuously in the main scanning direction to the total number of ink dots ejected by one scan of the liquid ejection head 23 is greater than that of the highlight-side gradation. Similarly, for the shadow-side gradation indicated by the dot data, the control unit 100 controls the ratio of positions where ink dots are ejected overlapping at the same coordinate on the recording medium P by one scan and another scan of the liquid ejection head 23 is greater than that of the highlight-side gradation. By performing this control according to the gradation of the input image data, granularity can be ensured on the highlight side, and panning resistance can be improved on the shadow side. In other words, it is possible to achieve midtones that balance both granularity and banding resistance.

[0099] Furthermore, each of the functions of the above-described embodiments can be realized by one or more processing circuits. Here, "processing circuit" includes processors programmed to execute each function by software, such as processors implemented by electronic circuits, as well as devices such as ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), FPGAs (Field-Programmable Gate Arrays), SoCs (System on a Chip), GPUs (Graphics Processing Units), and conventional circuit modules designed to execute each of the above-described functions.

[0100] Furthermore, in the above-described embodiment, if at least one of the functional units of the liquid dispensing device 1 is realized by program execution, the program is provided pre-installed in ROM or the like. Also, in the above-described embodiment, the program executed by the liquid dispensing device 1 may be configured to be provided as an installable or executable file recorded on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), flexible disk (FD), CD-R (Compact Disk-Recordable), DVD, or SD (Secure Digital) card. Also, in the above-described embodiment, the program executed by the liquid dispensing device 1 may be configured to be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. Also, in the above-described embodiment, the program executed by the liquid dispensing device 1 may be configured to be provided or distributed via a network such as the Internet. Furthermore, in the above-described embodiment, the program executed by the liquid dispensing device 1 has a module configuration that includes at least one of the above-described functional units, and in actual hardware, the CPU reads the program from the above-described storage device and executes it, thereby loading and generating the above-described functional units on the main memory. [Explanation of Symbols]

[0101] 1 Liquid discharge device 2. Cartridge loading section 3. Maintenance and recovery mechanisms 10 Main unit of the device 10a, 10b side plate 11 Support stand 12 Guide Rods 13 Guidestay 14 Sub-Sheet Metal Repair Guide 15 Carriage 16 Main scanning mechanism 17 Main scanning motor 18 Drive pulley 19 Driven pulley 20 Timing belt 21 Optical Sensors 22, 22a~22c Ink Cartridges 23, 23a~23c Liquid dispensing head 24 supply tubes 31 caps 32 Wiping Unit 40 Paper feeding means 41 sheets 100 Control Unit 101 CPU 102 ROM 103 RAM 104 NVRAM 105 ASIC 106 Printing Control Unit 107 Motor drive unit 108 I / O 109 Host I / F 110 Fan Control Unit 111 Heater control unit 120 Control Panel 130 sensors 140 Head Driver 150 Sub-scanning motor 160 Conveyor Rollers 170 hosts 180 fans 190 Heater 190a Preheater 190b, 190c Print Heater 190d Post Heater 190e Drying Heater 191 Conveyor guide plate 192 Platen 193 Image forming unit 201 Master Setting Section 202 Acquisition Department 203 Image Processing Unit 204 Output section P recording medium [Prior art documents] [Patent Documents]

[0102] [Patent Document 1] Japanese Patent Publication No. 2013-035209 [Patent Document 2] Japanese Patent Publication No. 2011-116096

Claims

1. A liquid ejection device that forms an image on a recording medium by ejecting ink from a nozzle during multiple scans in the main scanning direction of the ejection head, An acquisition unit that acquires image data to be printed, An image processing unit that generates print data by halftone processing using a dither mask on the aforementioned image data, A control unit that controls the movement of the ejection head and the ejection of ink based on the print data, Equipped with, The control unit, In the shadow gradation shown in the print data, the ratio of the number of ink dots of a single color ejected continuously in the main scanning direction to the total number of ink dots of a single color ejected in one scan of the ejection head for one line in the main scanning direction of the recording medium is controlled to be greater than that of the highlight gradation. A liquid ejection device that controls the proportion of positions in which ink dots of color 1 are ejected at the same coordinate on the recording medium during one scan and another scan of the ejection head, out of all positions in one line in the main scanning direction of the recording medium, to be greater than that of the highlight side gradation.

2. The liquid dispensing apparatus according to claim 1, further comprising a setting unit for setting the dither mask, which enables the control of the dispensing head by the control unit.

3. The setting unit is, In a first image having the size of an image completed by scanning the ejection head, the distance from each other pixel to a pixel corresponding to a threshold set in the mask matrix is ​​calculated as a first score. In a second image with an image size corresponding to the size of the mask matrix, the distance from each other pixel to the pixel corresponding to the threshold set in the mask matrix is ​​calculated as a second score. In a third image of the same size as the second image, a predetermined value is placed as the third score in the pixels adjacent to the pixel corresponding to the threshold set in the mask matrix in the main scanning direction, and 0 is placed as the third score in the pixels other than those adjacent to the first image. The first score, second score, and third score of the corresponding pixels in the first image, second image, and third image are summed up. The liquid dispensing device according to claim 2, wherein the dither mask is set by placing a threshold value in the component of the mask matrix corresponding to the position of the highest score among the summed scores.

4. The liquid dispensing apparatus according to claim 3, wherein the setting unit makes the weights of the third scores, which are placed in the pixels adjacent to the pixels in the main scanning direction of the pixel corresponding to the threshold corresponding to the shadow side in the mask matrix, greater than the weights of the third scores, which are placed in the pixels adjacent to the pixels in the main scanning direction of the pixel corresponding to the threshold corresponding to the highlight side, in the third image, and then adds up the first score, the second score, and the third score.

5. A liquid ejection method that forms an image on a recording medium by ejecting ink from a nozzle during multiple scans in the main scanning direction of the ejection head, wherein one line in the main scanning direction of the recording medium is formed by ejection of ink. Acquisition step to obtain image data to be printed, Image processing step of generating print data by halftone processing using a dither mask on the aforementioned image data, A control step that controls the movement of the ejection head and the ejection of ink based on the print data, It has, In the control step described above, In the shadow gradation shown in the print data, the ratio of the number of ink dots of a single color ejected continuously in the main scanning direction to the total number of ink dots of a single color ejected in one scan of the ejection head for one line in the main scanning direction of the recording medium is controlled to be greater than that of the highlight gradation. A liquid ejection method that controls the proportion of positions in which dots of the first color of ink are ejected at the same coordinate on the recording medium during one scan and another scan of the ejection head, out of all positions in one line in the main scanning direction of the recording medium, to be greater than that of the highlight side gradation.

6. A computer program that forms an image on a recording medium by ejecting ink from a nozzle during multiple scans in the main scanning direction of the ejection head, To the aforementioned computer, Acquisition step to obtain image data to be printed, Image processing step of generating print data by halftone processing using a dither mask on the aforementioned image data, A control step that controls the movement of the ejection head and the ejection of ink based on the print data, Make it run, In the control step described above, In the shadow gradation shown in the print data, the ratio of the number of ink dots of a single color ejected continuously in the main scanning direction to the total number of ink dots of a single color ejected in one scan of the ejection head for one line in the main scanning direction of the recording medium is controlled to be greater than that of the highlight gradation. A program for controlling the shadow-side gradation shown in the print data so that the proportion of positions where ink dots of color 1 are ejected at the same coordinate on the recording medium during one scan and another scan of the ejection head is greater than that of the highlight-side gradation.

Images