Recording device and recording method

Abstract

To suppress inversion unevenness of colors.SOLUTION: A recording device includes vertically arranged recording heads. In a case where images are recorded by executing plural times of main-scanning on a band region in a medium with forward scanning of the recording heads, sub-scanning, and backward-scanning of the recording heads, when a range of first nozzles adjacent to each other in the second direction in a first nozzle group relative to a second nozzle group corresponding to a first chromatic color whose discharge ratio for recording the image of liquid of the plurality of chromatic colors is lowest is a first range, and a range of the first nozzles adjacent to each other in the second direction in the first nozzle group relative to the second nozzle group corresponding to the chromatic color other than the first chromatic color of the plurality of chromatic colors is a second range, the recording device performs a first recording control of making the discharge ratio of the liquid of an achromatic color of the first range for recording the image higher than the discharge ratio of the liquid of the achromatic color of any second range for recording the image.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a recording apparatus and a recording method. [Background technology]

[0002] A printing device and method has been disclosed that uses a vertically arranged print head in which a color ink nozzle row in which nozzle groups for multiple color inks are arranged in series in the sub-scanning direction and a monochrome ink nozzle row are arranged in parallel (see Patent Document 1).

[0003] According to the aforementioned document 1, black ink print data for one band, equivalent to the width of one color ink nozzle group, is divided so that it is printed in a ratio of 25%:50%:25% over three alternating scans in the main scanning direction: forward pass, backward pass, forward pass, backward pass, etc. The divided black ink print data is then assigned to each range of the monochrome ink nozzle array corresponding to the cyan, magenta, and yellow color nozzle groups for printing. As a result, while the printing order of color inks and black ink is reversed in adjacent band-unit printing areas, the total amount of black ink is roughly the same between the forward pass and the backward pass. This reduces color inversion unevenness that occurs when the printing order of each color ink is different. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-195902 Summary of the Invention [Problem to be solved by the invention]

[0005] When recording is performed using the vertically arranged head as described above, there is room for further improvement in order to suppress uneven color inversion. [Means for solving the problem]

[0006] The recording device includes a recording head having a plurality of nozzle groups in which a plurality of nozzles capable of ejecting liquid onto a medium are arranged in a first direction, a transport unit that transports the medium, and a control unit that controls movement of the recording head and ejection of liquid by the recording head, wherein the recording head has, as the plurality of nozzle groups, a first nozzle group in which a plurality of first nozzles that eject achromatic liquid are arranged, and a plurality of second nozzle groups in which a plurality of second nozzles that eject chromatic liquid are arranged, the second nozzle groups ejecting liquid of different chromatic colors from each other, the plurality of second nozzle groups being arranged along the first direction, and the first nozzle group and the second nozzle group being arranged along a second direction intersecting the first direction, and the control unit controls a forward scan that is a main scan that causes the recording head to eject liquid as the recording head moves forward along the second direction, and a control unit that controls a movement of the recording head and the medium in the first direction. When an image is recorded by performing the main scan multiple times on a band region of the medium using a sub-scan that is a relative movement in the second direction, and a return scan that is a main scan that causes the recording head to eject liquid as the recording head moves back along the second direction, a first recording control is performed in which, when a range of adjacent first nozzles in the second direction in the second nozzle group for the second nozzle group corresponding to a first chromatic color that has the lowest ejection rate for recording the image among the plurality of chromatic color liquids is defined as a first range, and a range of adjacent first nozzles in the second direction in the second nozzle group for the second nozzle group corresponding to a chromatic color other than the first chromatic color among the plurality of chromatic colors is defined as a second range, a first recording control is performed in which the ejection rate of the achromatic color liquid in the first range for recording the image is made higher than the ejection rate of the achromatic color liquid in any of the second ranges for recording the image.

[0007] a recording method for a recording device having a recording head having a plurality of nozzle groups, each of which has a plurality of nozzles capable of ejecting liquid onto a medium, arranged in a first direction, and a transport unit that transports the medium, wherein the recording head has, as the plurality of nozzle groups, a first nozzle group in which a plurality of first nozzles that eject achromatic liquid are arranged, and a plurality of second nozzle groups in which a plurality of second nozzles that eject chromatic liquid are arranged, the second nozzle groups ejecting liquid of different chromatic colors from each other, the plurality of second nozzle groups being arranged along the first direction, and the first nozzle group and the second nozzle group being arranged along a second direction that intersects the first direction; and a recording step of controlling movement of the recording head and ejection of liquid by the recording head to perform recording, the recording step including a forward scan that is a main scan that causes the recording head to eject liquid as the recording head moves forward along the second direction; When an image is recorded by performing a plurality of main scans on a band region of the medium using a sub-scan, which is a relative movement between the head and the medium in the first direction, and a return scan, which is a main scan that causes the recording head to eject liquid as the recording head moves return along the second direction, and when a range of adjacent first nozzles in the first nozzle group in the second direction for the second nozzle group corresponding to a first chromatic color having the lowest ejection rate for recording the image among the plurality of chromatic color liquids is defined as a first range, and a range of adjacent first nozzles in the first nozzle group in the second direction for the second nozzle group corresponding to a chromatic color other than the first chromatic color among the plurality of chromatic colors is defined as a second range, the ejection rate of the achromatic color liquid in the first range for recording the image is made higher than the ejection rate of the achromatic color liquid in any of the second ranges for recording the image. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a simplified configuration of an apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a simplified view of the relationship between a medium, a recording head, etc., from above. [Figure 3] 10 is a flowchart showing a recording control process. [Figure 4] 4A and 4B are diagrams for explaining an example in which an image is recorded on a medium under the first recording control. [Figure 5] 5A and 5B are diagrams for explaining an example in which an image is recorded on a medium under the first recording control. [Figure 6] 10 is a flowchart showing a recording control process according to a modified example. [Figure 7] 10A and 10B are diagrams for explaining an example in which an image is recorded on a medium under second recording control. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are merely examples for explaining the present embodiment. Because the drawings are examples, the proportions, shapes, and shading may not be accurate, may not match each other, and some parts may be omitted.

[0010] 1. Brief description of the device configuration: 1 shows a simplified configuration of a recording device 10 according to this embodiment. The recording device 10 executes the recording method of this embodiment. The recording device 10 includes a control unit 11, a display unit 13, an operation reception unit 14, a memory unit 15, a communication IF 16, a transport unit 17, a carriage 18, and a recording head 19. IF stands for interface. The control unit 11 includes one or more ICs having a CPU 11a as a processor, a ROM 11b, a RAM 11c, and other non-volatile memories.

[0011] In the control unit 11, a processor, i.e., a CPU 11a, executes arithmetic processing in accordance with a program 12 stored in a ROM 11b or other memory, using a RAM 11c or the like as a work area, thereby realizing various functions such as a recording mode determination unit 12a, a recording data generation unit 12b, an allocation determination unit 12c, and a recording control unit 12d. The processor is not limited to a single CPU, and may be configured to perform processing using multiple CPUs or hardware circuits such as ASICs, or may be configured to perform processing in cooperation with a CPU and a hardware circuit.

[0012] The display unit 13 is a means for displaying visual information and is configured, for example, by a liquid crystal display, an organic EL display, or the like. The display unit 13 may be configured to include a display and a drive circuit for driving the display. The operation reception unit 14 is a means for receiving input from a user and is realized, for example, by physical buttons, a touch panel, a mouse, a keyboard, or the like. Of course, the touch panel may be realized as one function of the display unit 13. The display unit 13 and the operation reception unit 14 may be collectively referred to as the operation panel of the recording device 10. The display unit 13 and the operation reception unit 14 may be part of the configuration of the recording device 10, or may be peripheral devices external to the recording device 10.

[0013] The storage unit 15 is, for example, a hard disk drive, a solid state drive, or other memory storage means. Part of the memory of the control unit 11 may be regarded as the storage unit 15. The storage unit 15 may also be regarded as part of the control unit 11. The communication IF 16 is a general term for one or more IFs that allow the recording device 10 to communicate with external devices via wired or wireless connections in accordance with a predetermined communication protocol, including known communication standards. Examples of external devices include communication devices such as personal computers, servers, smartphones, and tablet terminals.

[0014] The transport unit 17 is a means for transporting the medium 30 in a predetermined transport direction under the control of the control unit 11. The transport unit 17 includes, for example, rollers that rotate to transport the medium 30, and a motor as a power source for the rotation. The transport unit 17 may also be a mechanism that transports the medium 30 by placing the medium 30 on a belt or pallet that is driven by a motor. The medium 30 is, for example, paper, but may also be any medium that can be subjected to liquid recording, and may be made of materials other than paper, such as film or fabric.

[0015] The carriage 18 is a moving means that moves back and forth along a predetermined main scanning direction by the power of a carriage motor (not shown) under the control of the control unit 11. The main scanning direction and the transport direction intersect. The carriage 18 carries a recording head 19. The recording head 19 is a means for performing recording by ejecting a liquid onto a medium 30 using an inkjet method under the control of the control unit 11. The liquid is mainly ink, but the recording head 19 can also eject liquids other than ink.

[0016] Recording device 10 may be realized by a single printer, or may be realized by a system having multiple devices connected to each other so that they can communicate with each other. For example, recording device 10 may be a system including an information processing device that functions as control unit 11, and a printer that performs recording under the control of the information processing device, including transport unit 17, carriage 18, and recording head 19. In this case, the information processing device can be understood as a recording control device, image processing device, etc.

[0017] 2. Recording head description: FIG. 2 shows a simplified view from above of the relationship between the medium 30, the recording head 19, etc. The recording head 19 mounted on the carriage 18 can move forward and backward along the main scanning direction D2 together with the carriage 18. In other words, the movement of the carriage 18 and the movement of the recording head 19 are synonymous. There is no need to distinguish between the carriage 18 and the recording head 19, and they may be collectively referred to as the recording head 19. For convenience, movement by the carriage 18 from the minus side to the plus side in the main scanning direction D2 will be called "forward movement," and movement from the plus side to the minus side in the main scanning direction D2 will be called "return movement."

[0018] The recording head 19 has a plurality of nozzles 20 for ejecting liquid such as ink. Each of the white circles shown in FIG. 2 is an individual nozzle 20. A droplet ejected from a nozzle 20 is called a dot. The recording head 19 has a group of nozzles for each type of liquid. The recording head 19 can eject ink of multiple colors, such as cyan (C), magenta (M), yellow (Y), and black (K). The recording head 19 may also be called a liquid ejection head, a print head, a printing head, an inkjet head, etc.

[0019] As shown in FIG. 2, the nozzle groups are roughly divided into an achromatic nozzle group 21 and a chromatic nozzle group 22. The chromatic nozzle group 22 is configured by arranging multiple nozzle groups 22C, 22M, and 22Y corresponding to different chromatic color liquids along the transport direction D1. The recording head 19 can be considered a vertically arranged head because it has such a chromatic nozzle group 22. Each nozzle group corresponding to one color of ink is configured by arranging multiple nozzles 20 with a constant or nearly constant nozzle pitch, which is the distance between the nozzles 20 in the transport direction D1. The transport direction D1 and the main scanning direction D2 are perpendicular or nearly perpendicular to each other. In the example of FIG. 2, the transport direction D1 corresponds to the "first direction," and the main scanning direction D2 corresponds to the "second direction."

[0020] The achromatic nozzle group 21 is a nozzle group consisting of a plurality of nozzles 20 that eject K ink, and corresponds to the "first nozzle group." Each nozzle 20 that constitutes the achromatic nozzle group 21 corresponds to the "first nozzle." In addition to K ink, other achromatic liquids that the recording head 19 can eject include, for example, gray ink and light black ink.

[0021] Nozzle group 22C is a nozzle group consisting of a plurality of nozzles 20 that eject C ink. Similarly, nozzle group 22M is a nozzle group consisting of a plurality of nozzles 20 that eject M ink, and nozzle group 22Y is a nozzle group consisting of a plurality of nozzles 20 that eject Y ink. Each of nozzle groups 22C, 22M, and 22Y in the chromatic nozzle group 22 corresponds to a "second nozzle group," and each nozzle 20 that constitutes each of nozzle groups 22C, 22M, and 22Y corresponds to a "second nozzle." Note that the chromatic color liquids that can be ejected by the recording head 19 are not limited to the three colors of C, M, and Y, but may be two colors, or four or more colors.

[0022] 2, the direction in which the nozzles 20 constituting a common nozzle group are arranged (hereinafter referred to as the nozzle arrangement direction) is parallel to the first direction, i.e., the transport direction D1. However, the configuration of the recording head 19 may be such that the nozzle arrangement direction intersects the first direction obliquely. Even if the nozzle arrangement direction intersects the first direction obliquely, as long as the nozzle pitch between the nozzles 20 in the first direction is constant or approximately constant, the multiple nozzles 20 are considered to be arranged in the first direction. In FIG. 2, each of the nozzle groups 21, 22C, 22M, and 22Y is a single nozzle row in which the nozzles 20 are arranged in a straight line, but naturally, each of the nozzle groups 21, 22C, 22M, and 22Y may be composed of multiple nozzle rows.

[0023] The transport unit 17 transports the medium 30 from upstream to downstream in the transport direction D1. The upstream and downstream in the transport direction D1 are also simply referred to as upstream and downstream. The achromatic nozzle group 21 and the chromatic nozzle group 22 of the recording head 19 are aligned along the main scanning direction D2 and are positioned at the same position in the transport direction D1. The achromatic nozzle group 21 and the chromatic nozzle group 22 can also be understood to have the same length in the transport direction D1, and the nozzle groups 22C, 22M, and 22Y within the chromatic nozzle group 22 can also be understood to have the same length in the transport direction D1.

[0024] The length of each of the nozzle groups 22C, 22M, and 22Y in the transport direction D1 is also referred to as the "band width." In FIG. 2, the range of nozzles 20 in the achromatic nozzle group 21 that are adjacent to nozzle group 22C in the main scanning direction D2 is indicated by reference symbol 21K1. The range of some of the nozzles 20 in a nozzle group is simply referred to as a range or a nozzle range. Similarly, the range of nozzles 20 in the achromatic nozzle group 21 that are adjacent to nozzle group 22M in the main scanning direction D2 is indicated by reference symbol 21K2, and the range of nozzles 20 in the achromatic nozzle group 21 that are adjacent to nozzle group 22Y in the main scanning direction D2 is indicated by reference symbol 21K3. The ranges that are adjacent in the main scanning direction D2 refer to ranges that share the same position in the transport direction D1. Therefore, the length of each of the nozzle ranges 21K1, 21K2, and 21K3 in the achromatic nozzle group 21 in the transport direction D1 also corresponds to the band width.

[0025] The control unit 11 causes the recording head 19 to eject liquid onto the medium 30 based on recording data that represents an image. As is known, the recording head 19 is provided with a drive element for each nozzle 20, and by controlling the application of a drive signal to the drive element of each nozzle 20 in accordance with the recording data, each nozzle 20 ejects or does not eject a dot, thereby recording the image represented by the recording data onto the medium 30.

[0026] The liquid ejection by the recording head 19 as the carriage 18 moves along the main scanning direction D2 is called a "main scan" or a "pass." Main scanning performed by the forward movement of the carriage 18 is called "forward scanning," and main scanning performed by the backward movement of the carriage 18 is called "backward scanning." Recording performed by both forward scanning and backward scanning is called bidirectional recording. Furthermore, the relative movement between the recording head 19 and the medium 30 in the first direction is called "sub-scan." In the configuration of Figure 2, sub-scanning is performed by the transport unit 17 transporting the medium 30 in the transport direction D1.

[0027] The control unit 11 records an image represented by the print data on the medium 30 using these forward scans, sub-scans, and return scans. A single sub-scan between main scans, known as a paper feed, transports the paper a distance equivalent to the band width. As shown in FIG. 2, the control unit 11 can complete printing with CMYK inks on a "band area"—an area on the medium 30 that is equivalent to one band width—by executing three main scans and paper feeds between those main scans. In FIG. 2, one band area BD is indicated by a two-dot chain line. However, completing printing with three main scans per band area is merely an example; for example, two main scans may be performed for printing one chromatic color, completing printing on the band area with a total of six main scans.

[0028] 3. Recording control process: 3 is a flowchart showing the recording control process executed by the control unit 11 in accordance with the program 12. The flowchart shows the recording method according to this embodiment.

[0029] In step S100, the recording data generation unit 12b of the control unit 11 acquires image data representing an image to be recorded. For example, the recording data generation unit 12b acquires image data specified through a user operation of the operation reception unit 14 from an image data storage location such as the storage unit 15 or a memory inside or outside the recording device 10. Alternatively, the recording data generation unit 12b receives and acquires image data transmitted from an external device via the communication IF 16.

[0030] In step S110, the print data generation unit 12b performs various processes, such as resolution conversion, color conversion, and halftone processing, on the image data acquired in step S100 as needed to generate print data for use by the print head 19 to print an image. For example, color conversion converts the values ​​of each pixel constituting the image data into gradation values ​​that represent the ink amounts of each CMYK ink used by the print head 19. While the color system used by the image data is not particularly limited, for example, if the image data is RGB image data having red (R), green (G), and blue (B) gradation values ​​for each pixel, the print data generation unit 12b refers to a lookup table that defines the conversion relationship between RGB and CMYK and converts each RGB gradation value for each pixel of the image data into each CMYK gradation value. The gradation values ​​are expressed, for example, in 256 gradations from 0 to 255.

[0031] The print data generation unit 12b converts each CMYK gradation value that the color-converted image data has for each pixel into a value that represents a dot-on or dot-off for each CMYK ink by halftone processing using a dithering method, error diffusion method, or the like. A dot-on means that a dot is ejected, and a dot-off means that a dot is not ejected. As a result, print data that specifies a dot-on or dot-off for each CMYK ink for each pixel is generated.

[0032] In step S120, the allocation determination unit 12c determines a "first chromatic color" that has the lowest ejection rate for printing an image from among the multiple chromatic color liquids, based on the print data generated in step S110. The ejection rate is the amount of liquid ejected per certain area, and may also be called a printing rate or duty. The allocation determination unit 12c determines a first chromatic color for each band image. A band image is an image of a size that is printed in one band area within an image of one page represented by the print data. Because the size of a band image is known, the allocation determination unit 12c simply divides the image represented by the print data into multiple band images and determines a first chromatic color for each band image.

[0033] The method for determining the first chromatic color for one band image will now be described. The allocation determination unit 12c calculates, for each of C, M, and Y, the ratio of the number of pixels that define dot-on to the number of pixels that make up the band image, and sets these as the ejection rates for each chromatic color in the band image. For example, if C ink is dot-on in half of the pixels that make up the band image, the ejection rate for C in this band image is 50%. The allocation determination unit 12c determines the color among C, M, and Y that has the lowest calculated ejection rate as the first chromatic color of the band image.

[0034] The ejection rate for each chromatic color in a band image may be calculated based on the print data before halftone processing. Specifically, the allocation determination unit 12c may determine the ejection rate for one chromatic color as the ratio of the sum of the gradation values ​​of one chromatic color possessed by each pixel in the band image to the value obtained by multiplying the number of pixels constituting the band image by the maximum gradation value of 255, and similarly calculate the ejection rate for each chromatic color. In this way, the first chromatic color is determined for each band image, but if adjacent band images in the image represented by the print data have similar colors, the first chromatic color determined for each of these band images will also be the same color.

[0035] In step S130, the allocation determination unit 12c determines, in accordance with the first chromatic color, a range within the achromatic nozzle group 21 to which the plane (hereinafter, K print data) that defines the dot-on or dot-off of K ink for each pixel, among the planes for each CMYK that make up the print data generated in step S110, is to be allocated. The determination in step S130 is also performed for each band image. Specifically, the allocation determination unit 12c determines the allocation destination of the K print data of a band image to be a range of nozzles 20 within the achromatic nozzle group 21 that are adjacent in the main scanning direction D2 to the second nozzle group corresponding to the first chromatic color of the band image. The range within the achromatic nozzle group 21 determined in step S130 is also referred to as the "first range." Furthermore, the range within the achromatic nozzle group 21 other than the first range corresponds to the "second range."

[0036] For example, suppose the first chromatic color of a certain band image is Y. According to FIG. 2, the range of achromatic nozzle group 21 adjacent to nozzle group 22Y, which is the second nozzle group for ejecting Y ink, is nozzle range 21K3. Therefore, the K recording data of that band image is assigned to nozzle range 21K3, with nozzle range 21K3 corresponding to the first range and nozzle ranges 21K1 and 21K2 corresponding to the second range. Similarly, if the first chromatic color of a certain band image is M, the K recording data of that band image is assigned to nozzle range 21K2 adjacent to nozzle group 22M, with the other nozzle ranges 21K1 and 21K3 corresponding to the second range.

[0037] Needless to say, for any band image, of the CMYK plates that make up the print data, the plate (C print data) that defines whether to turn on or off a dot of C ink for each pixel is assigned to nozzle group 22C. Similarly, the plate (M print data) that defines whether to turn on or off a dot of M ink for each pixel is assigned to nozzle group 22M, and the plate (Y print data) that defines whether to turn on or off a dot of Y ink for each pixel is assigned to nozzle group 22Y.

[0038] In step S140, the recording control unit 12d executes a process for outputting the recording data. That is, the recording control unit 12d controls the transport unit 17 to transport the medium 30 as needed, and transfers the C, M, Y, and K recording data for each band image to each of the assigned nozzles 20 in accordance with the allocation determined above. As a result, as each process is executed sequentially, for example, forward scanning, paper feeding, backward scanning, paper feeding, forward scanning, etc., each color dot is ejected from each nozzle 20 onto the medium 30 in accordance with the recording data, and the image represented by the recording data is sequentially recorded on the medium 30 in units of band images.

[0039] Step S140 and steps S120 and S130 for executing step S140 correspond to a "recording process" that controls the movement of the recording head 19 and the discharge of liquid by the recording head 19 to perform recording. The recording process of steps S120 to S140 is also referred to as "first recording control." That is, the control unit 11 performs first recording control that makes the discharge rate of the achromatic liquid from the first range for recording an image higher than the discharge rate of the achromatic liquid from any second range for recording an image. As explained above, in the first recording control, the control unit 11 limits the first nozzles that discharge the achromatic liquid for recording an image to the first range.

[0040] 4. Specific example: 4A is a diagram for explaining how image IM1 is recorded on medium 30 based on recording data using the first recording control, and shows the recording head 19 and a portion of medium 30. In FIG. 4A, the recording head 19 is simplified more than in FIG. 2. In FIG. 4A, the carriage 18 and nozzles 20 are omitted, and among the achromatic nozzle group 21 in the recording head 19, a rectangle marked with the symbol K1 indicates a nozzle range 21K1. Similarly, a rectangle marked with the symbol K2 indicates a nozzle range 21K2, and a rectangle marked with the symbol K3 indicates a nozzle range 21K3. Among the chromatic nozzle group 22 in the recording head 19, a rectangle marked with the symbol C indicates nozzle group 22C, a rectangle marked with the symbol M indicates nozzle group 22M, and a rectangle marked with the symbol Y indicates nozzle group 22Y.

[0041] Furthermore, the numbers 1 through 6 written in parentheses next to reference numeral 19 indicate the number of the main scan, and Fig. 4A shows the recording head 19 at each stage of the first through sixth main scans. Furthermore, the white arrows written near reference numeral 19 indicate the direction of the main scan, and according to Fig. 4A, the first, third, and fifth odd-numbered main scans are forward scans, while the second, fourth, and sixth even-numbered main scans are backward scans. In Fig. 4A, the recording head 19 appears to move upstream in the transport direction D1 with each main scan, but in reality, the medium 30 is transported downstream by the width of the handle during paper feed between main scans, changing the positional relationship between the recording head 19 and the medium 30 in the transport direction D1.

[0042] FIG. 4A shows four band regions BD1, BD2, BD3, and BD4 aligned along the transport direction D1 on the medium 30. Image IM1 is a uniform, solid-color image across multiple band images, with the print data specifying the C, M, and K ink ejection rates of C=50%, M=40%, Y=0%, and K=30%. Simply put, image IM1 is a dark blue image. When printing this image IM1, in step S120, Y, which has the lowest ejection rate among C, M, and Y, is determined as the first chromatic color for each band image. In step S130, the nozzle range 21K3 adjacent to nozzle group 22Y is determined as the destination of K print data, i.e., the first range, for each band image. In FIG. 4A, the portion of the print head 19 to which print data is assigned is colored gray. It should be noted that for colors with a discharge rate of 0%, that is, all pixel dots off, this is essentially the same as not allocating print data to the print head 19, and therefore is excluded from the targets for applying gray within the print head 19.

[0043] 4A, as a result of step S140, band area BD1 on medium 30 is recorded by the ejection of C ink by nozzle group 22C in the forward scan, which is the first main scan, the ejection of M ink by nozzle group 22M in the backward scan, which is the second main scan, and the ejection of K ink by nozzle range 21K3 in the forward scan, which is the third main scan. Similarly, band area BD2 on medium 30 is recorded by the ejection of C ink by nozzle group 22C in the backward scan, which is the second main scan, the ejection of M ink by nozzle group 22M in the forward scan, which is the third main scan, and the ejection of K ink by nozzle range 21K3 in the backward scan, which is the fourth main scan. 4A, only the nozzles 20 in the nozzle range 21K3 of the achromatic nozzle group 21 eject K ink in accordance with the K print data, and therefore in all of the band regions BD1, BD2, BD3, and BD4, the order of ejection of each color ink onto the medium 30 is C, M, and K. Therefore, color inversion unevenness that occurs when the ejection order of each color ink differs does not occur between band regions, and uniform, high-quality print results can be obtained.

[0044] FIG. 4B is a diagram for explaining how image IM2 is recorded on medium 30 based on recording data using the first recording control, and shows recording head 19 and a portion of medium 30. FIG. 4B and the later-described FIGS. 5A, 5B, and 7 should be interpreted in the same way as FIG. 4A. Therefore, the explanation of FIG. 4A applies mutatis mutandis to FIGS. 4B, 5A, 5B, and 7, as appropriate.

[0045] Image IM2 is a solid color image that is uniform across multiple band images, and the print data specifies the ejection rates of the CMYK inks as follows: C=40%, M=0%, Y=50%, and K=30%. Simply put, image IM2 is a dark green image. When printing image IM2, in step S120, M, which has the lowest ejection rate among CMY, is determined as the first chromatic color for each band image, and in step S130, nozzle range 21K2 adjacent to nozzle group 22M is determined as the destination for K print data, i.e., the first range, for each band image.

[0046] 4B, as a result of step S140, band area BD1 on medium 30 is recorded by the ejection of C ink by nozzle group 22C in the forward scan, which is the first main scan, the ejection of K ink by nozzle range 21K2 in the backward scan, which is the second main scan, and the ejection of Y ink by nozzle group 22Y in the forward scan, which is the third main scan. Similarly, band area BD2 on medium 30 is recorded by the ejection of C ink by nozzle group 22C in the backward scan, which is the second main scan, the ejection of K ink by nozzle range 21K2 in the forward scan, which is the third main scan, and the ejection of Y ink by nozzle group 22Y in the backward scan, which is the fourth main scan. 4B, only the nozzles 20 in the nozzle range 21K2 of the achromatic nozzle group 21 eject K ink in accordance with the K print data, and therefore in all of the band regions BD1, BD2, BD3, and BD4, the order of ejection of each color ink onto the medium 30 is C, K, and Y. Therefore, color inversion unevenness that occurs when the ejection order of each color ink differs does not occur between band regions, and uniform, high-quality print results can be obtained.

[0047] FIG. 5A is a diagram illustrating how image IM3 is recorded on medium 30 based on print data using the first print control, showing print head 19 and a portion of medium 30. Image IM3 is a uniform, solid image across multiple band images, and the print data specifies the ejection rates of the CMYK inks as follows: C=0%, M=50%, Y=40%, and K=30%. Simply put, image IM2 is a dark reddish image. When printing image IM3, in step S120, C, which has the lowest ejection rate among CMY, is determined as the first chromatic color for each band image. In step S130, nozzle range 21K1 adjacent to nozzle group 22C is determined as the destination for K print data, i.e., the first range, for each band image.

[0048] 5A, as a result of step S140, band area BD1 on medium 30 is recorded by the ejection of K ink from nozzle range 21K1 during the forward scan, which is the first main scan, the ejection of M ink from nozzle group 22M during the backward scan, which is the second main scan, and the ejection of Y ink from nozzle group 22Y during the forward scan, which is the third main scan. Similarly, band area BD2 on medium 30 is recorded by the ejection of K ink from nozzle range 21K1 during the backward scan, which is the second main scan, the ejection of M ink from nozzle group 22M during the forward scan, which is the third main scan, and the ejection of Y ink from nozzle group 22Y during the backward scan, which is the fourth main scan. 5A, only the nozzles 20 in the nozzle range 21K1 of the achromatic nozzle group 21 eject K ink in accordance with the K print data, and therefore in all of the band regions BD1, BD2, BD3, and BD4, the order of ejection of each color ink onto the medium 30 is K, M, and Y. Therefore, color inversion unevenness that occurs when the ejection order of each color ink differs does not occur between band regions, and uniform, high-quality print results can be obtained.

[0049] FIG. 5B is a diagram illustrating how image IM4 is recorded on medium 30 based on print data using the first print control, showing print head 19 and a portion of medium 30. Image IM4 is a uniform, solid image across multiple band images, and the print data specifies the ejection rates of the CMYK inks as follows: C=35%, M=35%, Y=25%, and K=20%. Simply put, image IM4 is a dark gray image. When printing image IM4, in step S120, Y, which has the lowest ejection rate among CMY, is determined as the first chromatic color for each band image. In step S130, nozzle range 21K3 adjacent to nozzle group 22Y is determined as the destination for K print data, i.e., the first range, for each band image.

[0050] 5B, as a result of step S140, band area BD1 on medium 30 is recorded by the ejection of C ink by nozzle group 22C in the forward scan, which is the first main scan, the ejection of M ink by nozzle group 22M in the backward scan, which is the second main scan, the ejection of Y ink by nozzle group 22Y in the forward scan, which is the third main scan, and the ejection of K ink by nozzle range 21K3 in the same third main scan. Meanwhile, band area BD2 on medium 30 is recorded by the ejection of C ink by nozzle group 22C in the backward scan, which is the second main scan, the ejection of M ink by nozzle group 22M in the forward scan, which is the third main scan, the ejection of K ink by nozzle range 21K3 in the backward scan, which is the fourth main scan, and the ejection of Y ink by nozzle group 22Y in the same fourth main scan.

[0051] 5B, only the nozzles 20 in the nozzle range 21K3 of the achromatic nozzle group 21 eject K ink in accordance with the K print data. In band areas BD1 and BD3 printed by a forward scan, a backward scan, and a forward scan, the order of ejection of the color inks is C, M, Y, K, and in band areas BD2 and BD4 printed by a backward scan, a forward scan, and a backward scan, the order of ejection of the color inks is C, M, K, Y. In other words, the ejection order of Y ink and K ink is reversed between odd-numbered band areas and even-numbered band areas.

[0052] Therefore, in the example of Figure 5B, it is difficult to completely eliminate the color inversion unevenness that occurs between odd-numbered band regions and even-numbered band regions. However, in image IM4, Y ink is the first chromatic color, which has the lowest ejection rate among the chromatic colors, and its impact on the color tone of the printed result is smaller than that of the other chromatic colors. Therefore, even if the ejection order of the first chromatic color and K is reversed between band regions, the degree of visible color inversion unevenness can be reduced compared to when the ejection order of chromatic colors other than the first chromatic color and K is reversed between band regions. Note that Figure 5B and Figure 7 (described below) clearly show that color inversion unevenness can occur between band regions on medium 30, but in reality, the unevenness is not so obvious.

[0053] 5. Summary: As described above, according to this embodiment, the recording device 10 includes a recording head 19 having a plurality of nozzle groups in which a plurality of nozzles 20 capable of ejecting liquid onto a medium 30 are arranged in a first direction, a transport unit 17 that transports the medium 30, and a control unit 11 that controls the movement of the recording head 19 and the ejection of liquid by the recording head 19. The recording head 19 has, as the plurality of nozzle groups, a first nozzle group in which a plurality of first nozzles that eject achromatic liquid are arranged, and a plurality of second nozzle groups in which a plurality of second nozzles that eject chromatic liquid are arranged, the second nozzle groups ejecting liquids of different chromatic colors, the plurality of second nozzle groups being arranged along the first direction, and the first nozzle group and the second nozzle group being arranged along a second direction that intersects the first direction. The control unit 11 performs a plurality of main scans on a band region of the medium 30 to record an image, using the following: an outward scan, which is a main scan that causes the recording head 19 to eject liquid as the recording head 19 moves outward in the second direction; a sub-scan, which is relative movement between the recording head 19 and the medium 30 in the first direction; and a backward scan, which is a main scan that causes the recording head 19 to eject liquid as the recording head 19 moves backward in the second direction. In this case, the control unit 11 performs a first recording control in which, for a second nozzle group corresponding to a first chromatic color having the lowest ejection rate for recording the image among the plurality of chromatic color liquids, a range of adjacent first nozzles in the first nozzle group in the second direction is defined as a first range, and for a second nozzle group corresponding to a chromatic color other than the first chromatic color among the plurality of chromatic colors, a range of adjacent first nozzles in the first nozzle group in the second direction is defined as a second range, so that the ejection rate of the achromatic color liquid in the first range for recording the image is higher than the ejection rate of the achromatic color liquid in any of the second ranges for recording the image.

[0054] According to the first printing control, the ejection rate of the achromatic liquid in the first range for printing an image is higher than the ejection rate of the achromatic liquid in any of the second ranges for printing the image, thereby suppressing color inversion unevenness between band regions.

[0055] Furthermore, according to this embodiment, in the first recording control, the control unit 11 limits the first nozzles that eject achromatic liquid for image recording to the first range, i.e., sets the ejection rate of achromatic liquid in the second range to 0. With this configuration, the ink ejection order tends to be the same for each band area, which can reduce or eliminate color inversion unevenness between band areas. Furthermore, because the ejection of achromatic liquid onto a band area is performed only within the first range, ejection of achromatic liquid onto one band area is completed with a single main scan. This makes it possible to avoid image quality degradation in band areas due to misalignment of liquid landing positions between forward and backward scans and paper feed errors, particularly degradation of characters and ruled lines printed using a large amount of K ink.

[0056] Depending on the comparison results of the chromatic color ejection rates, there may be multiple chromatic colors with the lowest ejection rate. For example, if the ejection rates of C and M are the same and lowest for a certain band image, the allocation determination unit 12c may expediently determine either C or M as the first chromatic color for that band image in step S120 and proceed to step S130 and subsequent steps. However, when an image contains successive band images of similar color tones, if one of the chromatic colors with the same and lowest ejection rates is determined as the first chromatic color for a certain band region, it is preferable to determine the same chromatic color as the first chromatic color for the other band regions as well.

[0057] According to this embodiment, for example, the chromatic color nozzle group 21 is configured with second nozzle groups corresponding to three or more odd chromatic colors. As shown in Fig. 2, the chromatic color liquids are the three colors of CMY ink. The chromatic colors ejected by the chromatic color nozzle group 21 may be, for example, five colors, including CMY inks plus light cyan ink and light magenta ink.

[0058] Up to this point, we have mainly described a case in which the first nozzles that eject achromatic liquid for image recording are limited to the first range in the first recording control, but the control unit 11 does not have to prohibit the first nozzles in the second range from ejecting achromatic liquid. That is, in step S130, the allocation determination unit 12c may determine the allocation destination of the K recording data to the first range of positions corresponding to the first chromatic color and the second range of positions corresponding to chromatic colors other than the first chromatic color.

[0059] For example, suppose the first chromatic color of a certain band image is Y. In this case, for that band image, the nozzle range 21K3 adjacent to the nozzle group 22Y in the achromatic nozzle group 21 is the first range, and the nozzle range 21K1 and the nozzle range 21K2 are the second range. Therefore, the allocation determination unit 12c determines that a predetermined percentage of pixels in the K recording data of that band image will be allocated to the nozzle range 21K3, which is the first range, and that the remaining pixels in the K recording data other than the predetermined percentage of pixels will be allocated to the nozzle range 21K1 and / or the nozzle range 21K2, which are the second range, and proceeds to step S140. The "predetermined percentage" here means a percentage that is at least more than half, but in the spirit of this embodiment, it can be considered to be a percentage that does not reach 100% but is somewhat close to 100%. For example, 90% of the pixels in the K recording data of a band image are assigned to the first range, nozzle range 21K3, and the remaining 10% of the pixels are assigned entirely to either the second range, nozzle range 21K1 or nozzle range 21K2, or half are assigned to nozzle range 21K1 and half to nozzle range 21K2.

[0060] This embodiment discloses inventions in various categories, such as not only devices and systems, but also methods executed by devices and systems, and programs 12 that cause a processor to execute the methods. For example, a recording method using a recording device 10 having a recording head 19 having a plurality of nozzle groups in which a plurality of nozzles 20 capable of ejecting liquid onto a medium 30 are arranged in a first direction, and a transport unit 17 that transports the medium 30, in which the recording head 19 has, as the plurality of nozzle groups, a first nozzle group in which a plurality of first nozzles that eject achromatic liquid are arranged, and a plurality of second nozzle groups in which a plurality of second nozzles that eject chromatic liquid are arranged, the second nozzle groups ejecting liquids of different chromatic colors, the plurality of second nozzle groups being arranged along the first direction, and the first nozzle group and the second nozzle group being arranged along a second direction that intersects the first direction, and the method includes a recording step of controlling the movement of the recording head 19 and the ejection of liquid by the recording head 19 to perform recording. In the recording process, an image is recorded by executing multiple main scans on a band region of the medium 30 using an outward scan, which is a main scan that causes the recording head 19 to eject liquid as the recording head 19 moves outward in the second direction, a sub-scan that is relative movement between the recording head 19 and the medium 30 in the first direction, and a backward scan, which is a main scan that causes the recording head 19 to eject liquid as the recording head 19 moves backward in the second direction. In this case, when a range of first nozzles in the first nozzle group that are adjacent in the second direction to a second nozzle group corresponding to a first chromatic color that has the lowest ejection rate for recording the image among the multiple chromatic colors is defined as a first range, and a range of first nozzles in the first nozzle group that are adjacent in the second direction to a second nozzle group corresponding to a chromatic color other than the first chromatic color among the multiple chromatic colors is defined as a second range, the ejection rate of the achromatic liquid in the first range for recording the image is made higher than the ejection rate of the achromatic liquid in any of the second ranges for recording the image.

[0061] 6. Variations: Modifications included in this embodiment will be described below. Naturally, combinations of the modifications are also included in this embodiment.

[0062] First variant: If there is little difference in the ejection rates of multiple chromatic colors in an image, allocating the K print data to either the first range or the second range has little effect on suppressing color inversion unevenness. In other words, if the difference in the ejection rates of chromatic colors is small, executing the first print control is meaningless. In consideration of this situation, as a first modification, the control unit 11 may perform the first print control when the difference in the ejection rates of multiple chromatic color liquids for image printing exceeds a predetermined threshold. If the difference is equal to or less than the threshold, the control unit 11 may perform the "second print control," in which the range adjacent to the multiple second nozzle groups in the second direction, which constitute the first nozzle group, is used to eject achromatic color liquid for image printing. In the configuration of FIG. 2, the transport direction D1 is the sub-scanning direction in which the medium 30 is displaced relative to the print head 19.

[0063] FIG. 6 is a flowchart showing a recording control process according to a modified example, which is executed by the control unit 11 in accordance with the program 12. Regarding FIG. 6, descriptions common to the flowchart in FIG. 3 will be omitted where appropriate. After step S110, in step S115, the recording mode determination unit 12a determines whether the first recording control or the second recording control should be executed. If the first recording control should be executed, the determination is "Yes" and the process proceeds to step S120. On the other hand, if the second recording control should be executed, the determination is "No" and the process proceeds to step S135. As described above, steps S120, S130, and the subsequent step S140 correspond to the first recording control. On the other hand, step S135 and the subsequent step S140 correspond to the second recording control.

[0064] The first recording control may be referred to as the first recording mode, and the second recording control may be referred to as the second recording mode. Therefore, it can be said that the recording mode determination unit 12a determines and selects the recording mode to be executed in step S115. In step S115, the recording mode determination unit 12a determines whether the difference in the ejection rates of the liquids of the multiple chromatic colors exceeds a predetermined threshold based on the recording data. Specifically, it determines whether the difference in the ejection rates between the chromatic color with the highest ejection rate and the chromatic color with the lowest ejection rate exceeds a threshold. If this difference exceeds the threshold, it determines that the first recording control should be executed, and the process proceeds to step S120. On the other hand, if the difference is equal to or less than the threshold, it determines that the second recording control should be executed, and the process proceeds to step S135.

[0065] There are various settings for the threshold value used in step S115. For example, suppose the threshold value is 9% and the CMYK ejection rates in the image are C=40%, M=35%, Y=40%, and K=20%. In this case, the difference of 5% between the C or Y ejection rate of 40% and the M ejection rate of 35% is below the threshold value, so the result in step S115 is "No" and the second print control is performed. As explained above, the determination in step S115 is also performed for each band image. That is, each band image is printed using either the first print control or the second print control. However, since the determination result in step S115 is the same for each area of ​​the image with similar color tones, either the first print control or the second print control is performed in the same way.

[0066] In step S135, the allocation determination unit 12c determines the range within the achromatic nozzle group 21 to which the K print data is to be allocated as the range upstream in the sub-scanning direction among the multiple nozzle ranges 21K1, 21K2, and 21K3 in the achromatic nozzle group 21, i.e., nozzle range 21K1 in the example of Figure 2. Hereinafter, nozzle range 21K1 will also be referred to as the "most upstream range."

[0067] FIG. 7 is a diagram illustrating how image IM5 is recorded on medium 30 based on print data using the second print control, showing print head 19 and a portion of medium 30. Image IM5 is a uniform, solid image across multiple band images, and the print data specifies the CMYK ink ejection rates of C=40%, M=35%, Y=40%, and K=20%. Because the difference in the chromatic ink ejection rates for this type of image IM5 is small, "No" is selected for each band image in step S115, meaning the second print control is selected. Therefore, when printing image IM5, nozzle range 21K1, which is the most upstream range, is determined to be the allocation destination for the K print data for each band image in step S135.

[0068] 7, as a result of step S140 following step S135, band area BD1 on medium 30 is recorded by the ejection of C ink by nozzle group 22C in the forward scan, which is the first main scan, the ejection of K ink by nozzle range 21K1 in the same first main scan, the ejection of M ink by nozzle group 22M in the backward scan, which is the second main scan, and the ejection of Y ink by nozzle group 22Y in the forward scan, which is the third main scan. Meanwhile, band area BD2 on medium 30 is recorded by the ejection of K ink by nozzle range 21K1 in the backward scan, which is the second main scan, the ejection of C ink by nozzle group 22C in the same second main scan, the ejection of M ink by nozzle group 22M in the forward scan, which is the third main scan, and the ejection of Y ink by nozzle group 22Y in the backward scan, which is the fourth main scan.

[0069] In the example of Figure 7, only the nozzles 20 in the nozzle range 21K1 eject K ink in accordance with the K print data. In the band areas BD1 and BD3 printed during the forward scan, backward scan, and forward scan, the ejection order of the color inks is C, K, M, Y, while in the band areas BD2 and BD4 printed during the backward scan, forward scan, and backward scan, the ejection order of the color inks is K, C, M, Y. In other words, the ejection order of the C ink and K ink is reversed between the odd-numbered band areas and the even-numbered band areas. For this reason, it is difficult to completely eliminate the color inversion unevenness that occurs between the odd-numbered band areas and the even-numbered band areas in Figure 7.

[0070] However, with the second print control, allocating the K print data to the most upstream range provides advantages different from those of the first print control. That is, by allocating the K print data to the most upstream range, the K ink can be ejected onto each band area in the earliest possible order. This minimizes the bleeding of achromatic ink that occurs when the achromatic ink is ejected onto the chromatic ink, stabilizing the achromatic color in each band area. This is particularly effective in preventing deterioration in the quality of characters and ruled lines that are printed using a large amount of achromatic ink. Thus, with the first modification, the first print control is executed when the effects of the first print control are easily achieved, and the second print control is executed when the effects of the first print control are difficult to achieve, thereby enabling the effects of the second print control to be enjoyed.

[0071] A supplementary explanation will be given regarding the first modified example. Even if the difference in the ejection rates of multiple chromatic color liquids is below the threshold, if the ejection rate of the chromatic color with the lowest ejection rate is 0%, then exceptionally, the print mode determination unit 12a may determine in step S115 that the first print control should be executed and proceed to step S120. For example, consider a case where the ejection rates of C, M, Y, and K in an image are C=7%, M=5%, Y=0%, and K=30%. In this case, the difference of 7% between the C ejection rate of 7% and the Y ejection rate of 0% is below the threshold, but if K print data is assigned to the nozzle range 21K3 adjacent to the nozzle group 22Y corresponding to Y, the ink ejection order in each band area will be C, M, and K, and the effect of the first print control will be properly achieved.

[0072] Second variant: It can be said that when the medium 30 used for recording is of a type that is prone to liquid bleeding, color inversion unevenness is more noticeable, and conversely, when the liquid is of a type that is less prone to bleeding, color inversion unevenness is less noticeable. Therefore, as a second modified example, the control unit 11 may perform a first recording control when the type of medium 30 is of a type that is more prone to liquid bleeding than a predetermined standard, and when the type of medium 30 is of a type that is less prone to liquid bleeding than the standard, perform a second recording control in which, of multiple ranges that are adjacent in the second direction to the multiple second nozzle groups that make up the first nozzle group, a range upstream in the sub-scanning direction where the medium 30 is displaced relative to the recording head 19 by the sub-scanning is used to eject achromatic liquid for recording an image.

[0073] The second modified example will also be described with reference to the flowchart of FIG. In step S115, the recording mode determination unit 12a determines whether the first recording control or the second recording control should be executed, and if the first recording control should be executed, the determination is "Yes" and the process proceeds to step S120, and if the second recording control should be executed, the determination is "No" and the process proceeds to step S135. The first recording control and the second recording control have already been described.

[0074] In the second modified example, in step S115, the recording mode determination unit 12a determines whether the type of medium 30 being transported by the transport unit 17 is a "first type," which indicates that the medium 30 is more susceptible to bleeding than a predetermined standard, or a "second type," which indicates that the medium 30 is less susceptible to bleeding than the predetermined standard. Because the groups of media 30 that fall under the first type and the second type are predetermined, the recording mode determination unit 12a simply acquires the type of medium 30 being transported by the transport unit 17 and determines whether the acquired type falls under the first type or the second type. The method for acquiring the type of medium 30 is not particularly important. For example, the recording mode determination unit 12a acquires the type of medium 30 through user input via the operation reception unit 14, or acquires the type of medium 30 in response to a detection signal from a media sensor (not shown) provided on a tray where the medium 30 is stored before transport or on the transport path of the medium 30 by the transport unit 17.

[0075] If the type of medium 30 is the first type, the recording mode determination unit 12a determines that the first recording control should be executed, and proceeds to step S120. On the other hand, if the type of medium 30 is the second type, the recording mode determination unit 12a determines that the second recording control should be executed, and proceeds to step S135. Thus, according to the second modified example, the first recording control is executed when the situation is such that the effect of the first recording control is easily obtained, and the second recording control is executed when the situation is such that the effect of the first recording control is difficult to obtain, thereby making it possible to enjoy the effect of the second recording control.

[0076] It is also possible to combine the first and second modified examples. For example, the print mode determination unit 12a may determine "Yes" in step S115 if the type of medium 30 is the first type and the difference in the ejection rates of the multiple chromatic color liquids based on the print data exceeds a predetermined threshold, and may determine "No" in step S115 if the type of medium 30 is the second type or the difference in the ejection rates of the multiple chromatic color liquids is equal to or smaller than the threshold.

[0077] Third variant: In addition to reciprocating along the main scanning direction D2, the carriage 18 may also be capable of reciprocating along a sub-scanning direction intersecting the main scanning direction D2. The sub-scanning direction is a first direction. Up until now, the sub-scanning between main scanning passes was performed by the transport unit 17 feeding the medium 30 downstream. However, instead, the sub-scanning may be performed by the carriage 18 moving upstream in the transport direction D1 a distance equal to the band width between main scanning passes. In other words, the carriage 18 may complete recording of multiple band areas by moving two-dimensionally within a plane parallel to the surface of the stationary medium 30, then return to its original position, the transport unit 17 transports the medium 30 by the amount corresponding to the multiple band areas, and then start moving two-dimensionally again to record the multiple band areas.

[0078] Furthermore, in a configuration in which carriage 18 moves two-dimensionally along the main scanning direction and sub-scanning direction relative to stationary medium 30 to perform recording for multiple band areas, the direction in which medium 30 is transported by transport unit 17 may be parallel to main scanning direction D2 rather than direction D1 as shown in Figure 2. [Explanation of symbols]

[0079] 10...recording device, 11...control unit, 12...program, 12a...recording mode determination unit, 12b...recording data generation unit, 12c...allocation determination unit, 12d...recording control unit, 13...display unit, 14...operation reception unit, 15...storage unit, 16...communication IF, 17...conveyance unit, 18...carriage, 19...recording head, 20...nozzle, 21...achromatic nozzle group, 21K1, 21K2, 21K3...nozzle range, 22...chromatic nozzle group, 22C, 22M, 22Y...nozzle group, 30...medium, BD, BD1, BD2, BD3, BD4...band area, IM1, IM2, IM3, IM4, IM5...image

Claims

1. a print head having a plurality of nozzle groups in which a plurality of nozzles capable of ejecting liquid onto a medium are arranged in a first direction; a conveying unit that conveys the medium; a control unit that controls movement of the recording head and ejection of liquid by the recording head, the recording head has, as the plurality of nozzle groups, a first nozzle group in which a plurality of first nozzles that eject achromatic liquid are arranged, and a plurality of second nozzle groups in which a plurality of second nozzles that eject chromatic liquid are arranged, the second nozzle groups ejecting chromatic liquids that are different from each other; the second nozzle groups are arranged along the first direction, the first nozzle group and the second nozzle group are arranged along a second direction intersecting the first direction, The control unit When an image is recorded by executing a plurality of main scans on a band area of ​​the medium, the main scans being an outward scan that causes the recording head to eject liquid as the recording head moves outward along the second direction, a sub-scan that causes the recording head and the medium to move relatively in the first direction, and a return scan that is a main scan that causes the recording head to eject liquid as the recording head moves back along the second direction, When a range of the first nozzles in the second nozzle group that are adjacent in the second direction to the second nozzle group corresponding to a first chromatic color having the lowest ejection rate for recording the image among the plurality of chromatic color liquids is defined as a first range, and a range of the first nozzles in the first nozzle group that are adjacent in the second direction to the second nozzle group corresponding to a chromatic color other than the first chromatic color among the plurality of chromatic colors is defined as a second range, a first recording control that makes the ejection rate of the achromatic liquid in the first range for recording the image higher than the ejection rate of the achromatic liquid in any of the second ranges for recording the image.

2. The control unit performing the first recording control when a difference in ejection ratio of the plurality of chromatic color liquids relating to the recording of the image exceeds a predetermined threshold value; 2. The recording device according to claim 1, wherein, when the difference is equal to or less than the threshold value, a second recording control is performed in which, of the multiple ranges that are adjacent in the second direction to the multiple second nozzle groups that constitute the first nozzle group, a range upstream in the sub-scanning direction in which the medium is displaced relative to the recording head by the sub-scanning is used to eject the achromatic liquid for recording the image.

3. The control unit performing the first recording control when the type of the medium is one that is more susceptible to bleeding of the liquid than a predetermined standard; 3. The recording device according to claim 1, wherein, when the type of medium is one that is less susceptible to bleeding of the liquid than the standard, a second recording control is performed in which, of the multiple ranges that are adjacent to the multiple second nozzle groups constituting the first nozzle group in the second direction, a range upstream in the sub-scanning direction in which the medium is displaced relative to the recording head by the sub-scanning is used to eject the achromatic liquid for recording the image.

4. The recording device according to any one of claims 1 to 3, characterized in that, in the first recording control, the control unit limits the first nozzles that eject the achromatic liquid for recording the image to the first range.

5. A recording method using a recording apparatus having a recording head having a plurality of nozzle groups, each of which has a plurality of nozzles capable of ejecting liquid onto a medium and arranged in a first direction, and a transport unit that transports the medium, the method comprising: the recording head has, as the plurality of nozzle groups, a first nozzle group in which a plurality of first nozzles that eject achromatic liquid are arranged, and a plurality of second nozzle groups in which a plurality of second nozzles that eject chromatic liquid are arranged, the second nozzle groups ejecting chromatic liquids that are different from each other; the second nozzle groups are arranged along the first direction, the first nozzle group and the second nozzle group are arranged along a second direction intersecting the first direction, a recording step of controlling the movement of the recording head and the ejection of liquid by the recording head to perform recording; In the recording step, When an image is recorded by executing a plurality of main scans on a band area of ​​the medium, the main scans being an outward scan that causes the recording head to eject liquid as the recording head moves outward along the second direction, a sub-scan that causes the recording head and the medium to move relatively in the first direction, and a return scan that is a main scan that causes the recording head to eject liquid as the recording head moves back along the second direction, When a range of the first nozzles in the second nozzle group that are adjacent in the second direction to the second nozzle group corresponding to a first chromatic color having the lowest ejection rate for recording the image among the plurality of chromatic color liquids is defined as a first range, and a range of the first nozzles in the first nozzle group that are adjacent in the second direction to the second nozzle group corresponding to a chromatic color other than the first chromatic color among the plurality of chromatic colors is defined as a second range, a rate at which the achromatic liquid is ejected in the first range for recording the image is set higher than a rate at which the achromatic liquid is ejected in any of the second ranges for recording the image.

Images