Recording device and recording method

Abstract

To resolve deterioration in the graininess or reduction in the chroma in an image with a low gray-scale to intermediate tone.SOLUTION: A recording device includes: a first nozzle group comprising a plurality of nozzles configured to discharge, to a medium, a first dot that is a dot of a reaction liquid; a second nozzle group comprising a plurality of nozzles configured to discharge a second dot that is a dot of ink containing a color material that coagulates with the reaction liquid; and a control unit configured to control discharging of the first dot by the first nozzle group and discharging of the second dot by the second nozzle group. The control unit controls arrangement, on the medium, of the first dots discharged by the first nozzle group so as to be more regular than arrangement, on the medium, of the second dots discharged by the second nozzle group.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] An inkjet recording method is disclosed that includes a step of attaching a reaction liquid that aggregates or thickens components of a colored ink containing a coloring material to a recording medium, and a step of attaching the colored ink to a region to which the reaction liquid has been attached by an inkjet method (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, due to the effect of aggregation and fixing by the reaction liquid, the granularity of the dots of the ink that has reacted with the reaction liquid on the medium becomes less prominent, and it is easy to obtain good image quality with high granularity. However, if the arrangement of the dots of the reaction liquid on the medium is irregular, in the medium, the positions where the dots of the ink aggregate also become irregular, or the sizes of the dots of the ink become non-uniform, resulting in a decrease in granularity. In particular, in relatively bright low-tone to mid-tone images, such irregularities and non-uniformities cause a decrease in granularity and a decrease in chroma.

Means for Solving the Problems

[0005] The recording device comprises a first nozzle group consisting of a plurality of nozzles that eject first dots, which are dots of reaction solution, onto a medium; a second nozzle group consisting of a plurality of nozzles that eject second dots, which are dots of ink containing a colorant that aggregates with the reaction solution; and a control unit that controls the ejection of the first dots by the first nozzle group and the ejection of the second dots by the second nozzle group, wherein the control unit ensures that the arrangement of the first dots ejected by the first nozzle group on the medium is more regular than the arrangement of the second dots ejected by the second nozzle group on the medium. The arrangement of the first dot is determined by error diffusion, and the arrangement of the second dot is determined by dithering. do. Furthermore, the recording device comprises a first nozzle group consisting of a plurality of nozzles that eject first dots, which are dots of reaction liquid, onto a medium; a second nozzle group consisting of a plurality of nozzles that eject second dots, which are dots of ink containing a colorant that aggregates with the reaction liquid; and a control unit that controls the ejection of the first dots by the first nozzle group and the ejection of the second dots by the second nozzle group. The control unit controls the arrangement of the first dots ejected by the first nozzle group on the medium to be more regular than the arrangement of the second dots ejected by the second nozzle group on the medium, and when recording characters on the medium with the ink, the arrangement of the first dots becomes denser the smaller the size of the characters.

[0006] The recording method is: A recording method using a recording device having a first nozzle group consisting of a plurality of nozzles for discharging first dots, which are dots of a reaction solution, into a medium, and a second nozzle group consisting of a plurality of nozzles for discharging second dots, which are dots of ink containing a colorant that aggregates with the reaction solution, wherein the recording method comprises a recording step of controlling the discharging of the first dots by the first nozzle group and the discharging of the second dots by the second nozzle group, and in the recording step, the arrangement of the first dots discharged by the first nozzle group in the medium is made more regular than the arrangement of the second dots discharged by the second nozzle group in the medium. The arrangement of the first dot is determined by error diffusion, and the arrangement of the second dot is determined by dithering. do. Furthermore, the recording method is a recording method using a recording device having a first nozzle group consisting of a plurality of nozzles that discharge first dots, which are dots of a reaction solution, onto a medium, and a second nozzle group consisting of a plurality of nozzles that discharge second dots, which are dots of ink containing a colorant that aggregates with the reaction solution, wherein the recording method includes a recording step of controlling the discharge of the first dots by the first nozzle group and the discharge of the second dots by the second nozzle group, wherein the arrangement of the first dots discharged by the first nozzle group on the medium is controlled to be more regular than the arrangement of the second dots discharged by the second nozzle group on the medium, and when recording characters on the medium with the ink, the arrangement of the first dots becomes denser the smaller the size of the characters. [Brief explanation of the drawing]

[0007] [Figure 1] A block diagram showing a simplified configuration of the apparatus in this embodiment. [Figure 2] A simplified diagram showing the relationship between the media and the recording head, etc., from a top-down perspective. [Figure 3] A flowchart illustrating the recording control process. [Figure 4] A diagram illustrating a reaction liquid volume table. [Figure 5] A diagram illustrating reaction solution recording data and ink recording data. [Figure 6] Figure 6A is an enlarged illustration of a portion of the medium on which an image is recorded according to the first modification, and Figure 6B is an enlarged illustration of a portion of the medium on which an image is recorded according to the conventional example. [Figure 7] Figures 7A and 7B illustrate the relationship between reaction solution recording data and text, respectively. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the figures. Note that the figures are merely illustrative examples for illustrating these embodiments. Because the figures are illustrative, their proportions and shapes may not be accurate, they may not be consistent with each other, or some parts may be omitted.

[0009] 1. Outline of the device configuration: Figure 1 shows a simplified configuration of the recording device 10 according to this embodiment. The recording method of this embodiment is performed by the recording device 10.

[0010] The recording device 10 includes a control unit 11, a display unit 13, an operation reception unit 14, a storage unit 15, a communication IF 16, a transport unit 17, a recording unit 18, etc. IF stands for interface. The control unit 11 is composed of one or more ICs having a CPU 11a as a processor, ROM 11b, RAM 11c, etc., and other non-volatile memory, etc. In the control unit 11, the processor, i.e., the CPU 11a, performs arithmetic processing according to the program 12 stored in the ROM 11b or other memory, etc., using the RAM 11c etc. as a work area. The processor is not limited to a single CPU, but may be configured to perform processing using multiple CPUs or hardware circuits such as ASICs, or the CPU and hardware circuits may cooperate in performing processing.

[0011] The display unit 13 is a means for displaying visual information and is composed of, for example, a liquid crystal display or an organic EL display. The display unit 13 may also include a display and a drive circuit for driving the display. The operation reception unit 14 is a means for receiving input from the user and is implemented by, for example, physical buttons, a touch panel, a mouse, or a keyboard. Of course, a touch panel may be implemented as a function of the display unit 13. The display unit 13 and the operation reception unit 14 together may be called 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, but they may also be peripheral devices attached to the recording device 10 externally.

[0012] The storage unit 15 is, for example, a hard disk drive, a solid-state drive, or other memory-based storage means. The storage unit 15 may be considered as a part of the memory possessed by the control unit 11. Alternatively, the storage unit 15 may be considered as a part of the control unit 11. The communication IF 16 is a general term for one or more interfaces that allow the recording device 10 to communicate with an external device via wired or wireless connection in accordance with a predetermined communication protocol that includes a known communication standard. The external device is, for example, a communication device such as a personal computer, server, smartphone, or tablet terminal.

[0013] The transport unit 17 is a means for transporting the medium 30 along a predetermined transport path 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 to drive the rollers. Alternatively, the transport unit 17 may be a mechanism that transports the medium 30 by loading it onto a belt or pallet moved by a motor. The medium 30 is typically paper, but any medium that can be used for recording is acceptable, and may be made of materials other than paper, such as film or fabric.

[0014] The recording unit 18 is a means for performing recording on the medium 30 by ejecting a liquid such as ink from the nozzles 21 under the control of the control unit 11, and includes a recording head 20 described later. The droplets ejected from the nozzles 21 are called dots. The recording head 20 may be referred to as a liquid ejection head, a printing head, a printing head, an inkjet head, or the like.

[0015] The recording device 10 may be configured to be realized by a single printer, or may be realized by a system having a plurality of communicably connected devices. For example, the recording device 10 may be a system including an information processing device that plays the role of the control unit 11 and a printer that has a conveyance unit 17 and a recording unit 18 and executes recording under the control of the information processing device. In this case, the information processing device can be understood as a recording control device, an image processing device, or the like.

[0016] FIG. 2 simply shows the relationship between the medium 30 and the recording head 20 and the like from an overhead perspective. In FIG. 2, two orthogonal directions D1 and D2 are shown. The direction D1 is called the conveyance direction D1 of the medium 30 by the conveyance unit 17, and the direction D2 is called the width direction D2. The upstream and downstream in the conveyance direction D1 are simply referred to as upstream and downstream. In the example of FIG. 2, the medium 30 is conveyed from upstream to downstream on the platen 24 by the conveyance unit 17. The platen 24 is a table that supports the medium 30 and can be said to be a part of the conveyance path of the medium 30.

[0017] In FIG. 2, each circle represents each nozzle 21. The recording head 20 records an image on the medium 30 by ejecting or not ejecting dots such as ink from each nozzle 21 based on the recording data for recording the image generated by the control unit 11. As is known, in the recording head 20, a drive element (not shown) is provided for each nozzle 21, and by controlling the application of a drive signal to the drive element based on the recording data, it is possible to select dot ejection (dot on) or non-ejection (dot off) for each nozzle 21. The recording head 20 can eject various color inks such as cyan (C) ink, magenta (M) ink, yellow (Y) ink, black (K) ink, and a reaction liquid having an action of aggregating and fixing a coloring material, specifically a pigment component, contained in the ink. Of course, the recording head 20 may be configured to eject inks and liquids of other colors as well.

[0018] The recording head 20 includes a nozzle group 22 for each liquid in a configuration in which it receives the supply of a liquid such as ink from a liquid holding means (not shown) called an ink cartridge or an ink tank and ejects it from the nozzle 21. FIG. 2 shows an example of the arrangement of the nozzles 21 in the recording head 20. A nozzle group 22P1 is a nozzle group 22 composed of a plurality of nozzles 21 that eject a first reaction liquid, which is one type of reaction liquid. Also, a nozzle group 22P2 is a nozzle group 22 composed of a plurality of nozzles 21 that eject a second reaction liquid, which is one type of reaction liquid and different from the first reaction liquid. The nozzle group 22P1 and the nozzle group 22P2 each correspond to the "first nozzle group". Examples of the first reaction liquid and the second reaction liquid include a reaction liquid containing Ca propionate used for a film-based medium 30 and a reaction liquid containing Ca nitrate used for a paper-based medium 30. However, it is not essential in this embodiment that the recording head 20 can eject a plurality of types of reaction liquids, and it may be one type. The dots of the reaction liquid ejected by the nozzles 21 of the first nozzle group are referred to as "first dots" or "reaction liquid dots".

[0019] Nozzle group 22, consisting of multiple nozzles 21 that eject C ink, is nozzle group 22C. Similarly, nozzle group 22, consisting of multiple nozzles 21 that eject M ink, is nozzle group 22M; nozzle group 22, consisting of multiple nozzles 21 that eject Y ink, is nozzle group 22Y; and nozzle group 22, consisting of multiple nozzles 21 that eject K ink, is nozzle group 22K. Nozzle groups 22C, 22M, 22Y, and 22K each correspond to a "second nozzle group." The ink dots ejected by the nozzles 21 of the second nozzle group are referred to as "second dots" or "ink dots." Therefore, the control unit 11 can perform a "recording process" that controls the ejection of the first dot by the first nozzle group and the ejection of the second dot by the second nozzle group.

[0020] In the example shown in Figure 2, each nozzle group 22 is formed by multiple nozzles 21 arranged over a range that can cover the medium width, which is the length of the medium 30 in the width direction D2. The multiple nozzle groups 22P1, 22P2, 22C, 22M, 22Y, and 22K are arranged at the same position in the width direction D2 and are aligned along the transport direction D1. Furthermore, the first nozzle groups, nozzle group 22P1 and nozzle group 22P2, are arranged upstream of the second nozzle groups, nozzle groups 22C, 22M, 22Y, and 22K. Therefore, focusing on a certain position or region of the medium 30, the reaction liquid is discharged first, followed by the discharge of inks of each color.

[0021] A nozzle group 22 is formed by arranging multiple nozzles 21, the nozzle pitch being the distance between the nozzles 21 in the width direction D2, which is constant or nearly constant. In Figure 2, a nozzle group 22 is simply shown as a single nozzle row with multiple nozzles 21 arranged along the width direction D2. Of course, a nozzle group 22 may be formed by multiple nozzle rows, and the direction in which the nozzles 21 forming the nozzle group 22 are arranged may be oblique to the width direction D2. Furthermore, regardless of the arrangement of the nozzles 21 forming the nozzle group 22, the nozzle group 22 may be referred to as a nozzle row 22.

[0022] The recording head 20 is mounted on the carriage 23. In other words, the recording unit 18 includes the recording head 20 and the carriage 23. The carriage 23 is powered by a carriage motor (not shown) and is capable of reciprocating in parallel with the transport direction D1 at a predetermined height above the platen 24. The recording head 20 moves together with the carriage 23.

[0023] In the example shown in Figure 2, the control unit 11 moves the carriage 23 a certain distance from downstream to upstream while the medium 30 is stationary on the platen 24. The control unit 11 performs one recording on the medium 30 by ejecting reaction liquid and ink from each nozzle group 22 of the recording head 20 onto the medium 30 while the carriage 23 is moving upstream. After that, the control unit 11 transports the medium 30 downstream by the transport unit 17 for a distance equivalent to the one recording, and moves the carriage 23 downstream for a distance equivalent to the one recording, and then performs another recording by the recording head 20 as the carriage 23 moves upstream again. The control unit 11 can continuously record on the medium 30 by repeating this process.

[0024] Alternatively, a configuration may be adopted in which the recording head 20 moves by the carriage 23 in a direction parallel to the transport direction D1 and in a direction parallel to the width direction D2 to record onto the medium 30. Alternatively, the transport direction of the medium 30 by the transport unit 17 may be set to be parallel to the width direction D2 in Figure 2, and a configuration may be adopted in which recording is performed by alternately repeating the transport of the medium 30 and the movement of the recording head 20 by the carriage 23 parallel to the direction D1.

[0025] The recording unit 18 may be configured without a carriage 23. In other words, in the configuration shown in Figure 2, the carriage 23 may be omitted and the recording head 20 may be fixed above the platen 24. The recording may be performed by the reaction liquid or ink ejected from the recording head 20 as the medium 30, which is transported by the transport unit 17, passes downstream below the recording head 20. In any case, in this embodiment, the recording head 20 first ejects the reaction solution to the medium 30, and then ejects the ink.

[0026] 2. Recording control processing: Figure 3 shows a flowchart illustrating the recording control process executed by the control unit 11 according to the program 12. At least a portion of this flowchart corresponds to a recording method that includes a recording step.

[0027] In step S100, the control unit 11 acquires the recording conditions for recording an image. The recording conditions are specified by the user by operating the operation reception unit 14. Therefore, the control unit 11 can acquire the recording mode, media type, and various other settings related to recording as recording conditions according to the input from the user. The media type is information that refers to the type of material, such as paper, film, or fabric. There are generally two types of recording modes: one that uses a reaction solution and one that does not. In this embodiment, the following explanation will continue assuming that the recording mode using a reaction solution is specified.

[0028] In step S110, the control unit 11 acquires image data representing the image to be recorded. The user can also arbitrarily select image data and either instruct the control unit 11 to select the image data or transmit it from an external device to the recording device 10. The control unit 11 acquires the instructed image data from memory inside or outside the recording device 10, or acquires the image data transmitted from the external device via the communication IF 16. Steps S100 and S110 may be performed substantially simultaneously, or step S110 may be executed first. Alternatively, steps S100 and S110 may be performed when the recording device 10 receives image data accompanied by recording condition information from an external device.

[0029] In steps S120 and S130, the control unit 11 generates recording data for use by the recording unit 18 based on the image data acquired in step S110. The recording data generated in step S120 is "ink recording data" for ejecting ink, and the recording data generated in step S130 is "reaction solution recording data" for ejecting the reaction solution. In Figure 4, steps S120 and S130 are shown separately, but they can also be understood as a single process without separation.

[0030] First, the method for generating ink recording data in step S120 will be briefly explained. The control unit 11 performs the necessary color conversion processing according to the format and color system of the image data to convert the image data into ink amount image data, which has an ink amount for each pixel. The ink amount for each pixel is the respective CMYK gradation value for each pixel, in the case where the recording head 20 uses CMYK ink as shown in Figure 2. The gradation value is expressed in 256 gradations, for example, from 0 to 255. The gradation value indicating the ink amount for each CMYK may be normalized to a density of 0 to 100% for each CMYK and expressed accordingly.

[0031] If the image data is, for example, RGB image data with red (R), green (G), and blue (B) gradation values ​​for each pixel, the control unit 11 can perform color conversion by referring to a color conversion lookup table that pre-defines the correspondence between RGB and CMYK. Furthermore, the control unit 11 applies halftone processing using the dithering method to the ink amount image data to generate ink recording data that defines dot-on or dot-off for each pixel and each CMYK ink.

[0032] Next, the method for generating reaction solution recording data in step S130 will be described. The control unit 11 determines the amount of reaction solution to be ejected to the first nozzle group according to the ink recording data or the ink amount image data before halftone processing of the ink recording data. Figure 4 illustrates a reaction liquid volume table T1. The reaction liquid volume table T1 is stored in advance in the storage unit 15 or on an external storage medium accessible by the control unit 11. The reaction liquid volume table T1 defines the correspondence between the amount of ink and the amount of reaction liquid. In Figure 4, the reaction liquid volume table T1 is linear, but it may also be nonlinear.

[0033] As can be seen from Figure 4, the reaction liquid volume table T1 defines the correspondence between the amount of ink and the amount of reaction liquid so that the amount of reaction liquid increases in accordance with the increase in the amount of ink. The ink amount on the horizontal axis of the reaction liquid volume table T1 is the amount of ink per unit area represented by the ink recording data or ink volume image data. For example, it can be calculated as the ratio of the total number of CMYK dots in the area when the value obtained by multiplying the number of pixels constituting the area by the number of ink colors is set to 100%. The number of dots is the number of dots. Alternatively, the amount of ink per unit area may be calculated as the ratio of the total CMYK gradation values ​​of all pixels in the area before halftone processing, when the value obtained by multiplying the number of pixels constituting the area by 255 × the number of ink colors is set to 100%. Furthermore, the reaction liquid volume on the vertical axis of the reaction liquid volume table T1 is the amount of reaction liquid required per unit area. For example, it is the ratio of the number of dots of the reaction liquid when the number of pixels constituting the area is set to 100%.

[0034] The control unit 11 can refer to the reaction liquid volume table T1 and determine the amount of reaction liquid corresponding to the amount of ink indicated by the ink recording data or ink volume image data. For example, the control unit 11 can determine the amount of reaction liquid according to the amount of ink on each page represented by the image data. In this case, the area of ​​one page corresponds to the aforementioned fixed area. Alternatively, the control unit 11 may divide the page represented by the image data into a predetermined number of regions and determine the amount of reaction liquid according to the amount of ink in each divided region. In this case, the area of ​​each region corresponds to the aforementioned fixed area.

[0035] The control unit 11 may treat each object on the page represented by the image data as a region, and determine the amount of reaction solution for each region according to the amount of ink in that region. With this configuration, the amount of reaction solution can be changed according to the amount of ink in each region on the page, and the amount of reaction solution can be optimized for each region. Objects include, for example, regions corresponding to photographic images, regions corresponding to graphs, regions corresponding to text, etc.

[0036] The control unit 11 performs halftone processing on the reaction solution amount determined as described above to generate reaction solution recording data that defines whether the reaction solution dots are on or off for each pixel. At this time, the control unit 11 generates the reaction solution recording data such that the arrangement of reaction solution dots on the medium 30 is more regular than the arrangement of ink dots on the medium 30 based on the ink recording data. Regular arrangement of dots refers to a state in which the arrangement of dots is regular or the distance between dots is closer to equal.

[0037] As mentioned above, the dithering method is used for halftone processing when generating ink recording data in step S120. The dithering method is a method of binarizing the gradation value of each pixel into dot-on or dot-off by applying a dither matrix, which has various threshold values ​​randomly distributed, to the ink amount image data. As a result, the distance between the generated dots is uneven, and the arrangement of the dots is relatively irregular.

[0038] Therefore, in step S130, the control unit 11 uses, for example, the error diffusion method for halftone processing on the determined reaction solution volume. According to the error diffusion method, the error resulting from the comparison between the reaction solution volume and the threshold value at the pixel level is diffused to the surrounding pixels, and the surrounding pixels compare the reaction solution volume corrected by the diffused error with the threshold value. As a result, the arrangement of dots in the halftone processing result using the error diffusion method is more regular than when the dithering method is used. Furthermore, in the error diffusion method, it is possible to control the regularity of dot generation by adjusting how the error is diffused to the surrounding pixels.

[0039] The control unit 11 only needs to generate reaction solution recording data such that the arrangement of reaction solution dots is more regular than the arrangement of ink dots, and using the error diffusion method to generate reaction solution recording data is just one example. For example, if the amount of reaction solution in a certain area is determined to be 30%, the control unit 11 will dot on reaction solution dots at a ratio of 3 out of 10 pixels for each pixel constituting this certain area. Therefore, it is sufficient to generate reaction solution recording data in which reaction solution dots are dot on at a ratio of 3 out of 10 pixels, and at, for example, even or nearly even intervals. In addition, the control unit 11 may use the dithering method in the halftone processing of the reaction solution amount. In this case, a dither matrix with higher dispersion and regularity of the generated dots than the dither matrix used for halftone processing of ink amount image data should be used, and as a result, reaction solution recording data in which the arrangement of reaction solution dots is more regular than the arrangement of ink dots should be generated.

[0040] Figure 5 illustrates the reaction solution recording data 40 generated in step S130 and the ink recording data 41 generated in step S120. Figure 5 also shows the correspondence between each recording data 40, 41 and directions D1, D2. Each rectangle constituting each recording data 40, 41 represents an individual pixel. The reaction solution recording data 40 and the ink recording data 41 are recording data relating to the same region within the image represented by the image data acquired in step S110, and are recorded on top of each other on the medium 30.

[0041] The white circles in the pixels of the reaction solution recording data 40 represent reaction solution dots, while the gray circles in the pixels of the ink recording data 41 represent ink dots. This gray color is used to distinguish them from the reaction solution dots and is unrelated to the original color of the ink dots. As illustrated in Figure 5, the arrangement of reaction solution dots in the reaction solution recording data 40 is regular, while the arrangement of ink dots in the ink recording data 41 is irregular compared to the arrangement of reaction solution dots in the reaction solution recording data 40.

[0042] In step S140, the control unit 11 causes the recording unit 18 to perform recording according to the generated reaction solution recording data and ink recording data. The control unit 11 also controls the transport unit 17 at the necessary timing to transport the medium 30 for recording, for example, as explained with reference to Figure 2.

[0043] The control unit 11 selects whether to use the first reaction solution or the second reaction solution depending on the type of medium included in the recording conditions acquired in step S100. In this embodiment, the correspondence between the type of medium and the type of reaction solution is stored in advance in the storage unit 15, etc., and the control unit 11 only needs to refer to this correspondence and select either the first reaction solution or the second reaction solution depending on the type of medium. The control unit 11 drives the nozzle group 22, which discharges the reaction solution selected according to the type of medium, from the first nozzle group, nozzle groups 22P1 and 22P2, according to the reaction solution recording data. For example, if the first reaction solution is selected according to the type of medium, the control unit 11 discharges reaction solution dots from each nozzle 21 of nozzle group 22P1 to the medium 30 according to whether the reaction solution dots are on or off in the reaction solution recording data.

[0044] Of course, if the recording head 20 can dispense only one type of reaction solution, the step of selecting the reaction solution according to the type of media is unnecessary. As described above, if the amount of reaction solution has been determined for each area within a page, the control unit 11 will dispense a number of reaction solution dots from the first nozzle group corresponding to the amount of reaction solution for each area within the range corresponding to a page in the media 30.

[0045] The control unit 11, in conjunction with the drive control of the first nozzle group, drives each nozzle 21 of nozzle groups 22C, 22M, 22Y, and 22K according to the ink recording data. In other words, it ejects CMYK ink dots of each color according to the ink recording data from nozzle groups 22C, 22M, 22Y, and 22K onto the medium 30. As a result of step S140, a layer of reaction liquid is formed on the medium 30, and an image represented by the ink recording data is formed by the inks of each color superimposed on this layer. This concludes the flowchart in Figure 3.

[0046] As explained above, in step S140, the recording unit 18 first discharges the reaction liquid to the medium 30, and then the ink. However, under the control of the control unit 11, the recording unit 18 may discharge the ink to the medium 30 first, and then the reaction liquid. In other words, the reaction liquid may be discharged not only before the ink to the medium 30, but also so as to overlap the layer of ink discharged to the medium 30. In the example in Figure 2, if the control unit 11 discharges ink and reaction liquid from each nozzle group 22 of the recording head 20 to the medium 30 while the carriage 23 moves from upstream to downstream on the medium 30 with the medium 30 stationary on the platen 24, then the ink can be discharged to the medium 30 first, and then the reaction liquid. Furthermore, by changing the positional relationship between nozzle groups 22P1, 22P2 and nozzle groups 22C, 22M, 22Y, 22K in the recording head 20, it is also possible to discharge the ink to the medium 30 first, and then the reaction liquid.

[0047] 3. Summary: As described above, according to this embodiment, the recording device 10 comprises a first nozzle group consisting of a plurality of nozzles 21 that eject first dots, which are dots of reaction liquid, onto the medium 30; a second nozzle group consisting of a plurality of nozzles 21 that eject second dots, which are dots of ink containing a colorant that aggregates due to the reaction liquid; and a control unit 11 that controls the ejection of the first dots by the first nozzle group and the ejection of the second dots by the second nozzle group. The control unit 11 controls the arrangement of the first dots ejected by the first nozzle group on the medium 30 to be more regular than the arrangement of the second dots ejected by the second nozzle group on the medium 30.

[0048] According to the above configuration, the arrangement of the first dots, i.e., reaction liquid dots, on the medium 30 is relatively regular. Therefore, compared to the conventional method in which the arrangement of reaction liquid dots was irregular, the positions in which the second dots, i.e., ink dots, ejected onto the medium 30 react with the reaction liquid, aggregate, and fix are also regular. Furthermore, phenomena such as ink dots aggregating and connecting in biased positions due to irregularly arranged reaction liquid dots are reduced, and the dot size of the ink fixed on the medium 30 is also made relatively uniform. As a result, in low-gradation to mid-tone images and image regions where the amount of ink is relatively small, granularity is improved and saturation is improved due to the uniform distribution of ink on the medium surface, resulting in good image quality. In high-gradation images and image regions where the amount of ink is large, most or almost all of the medium surface is covered with ink dots, so granularity is hardly a problem. Therefore, as described above, this embodiment is particularly effective in improving image quality in low-gradation to mid-tone images and image regions.

[0049] Furthermore, according to this embodiment, the control unit 11 determines the arrangement of the first dots by error diffusion and the arrangement of the second dots by dithering. According to the above configuration, by using error diffusion and dithering methods interchangeably in the halftone processing to determine the placement of the first and second dots, the regularity of the placement of the first dots can be easily increased compared to the placement of the second dots.

[0050] This embodiment discloses inventions in various categories, not limited to recording devices and systems, but also including recording methods executed by these devices and systems, and programs 12 that cause a processor to execute these methods. For example, a recording method using a recording device 10 having a first nozzle group consisting of a plurality of nozzles 21 that discharge first dots, which are dots of reaction solution, onto a medium 30, and a second nozzle group consisting of a plurality of nozzles 21 that discharge second dots, which are dots of ink containing a colorant that aggregates due to the reaction solution, wherein the recording method includes a recording step of controlling the discharge of first dots by the first nozzle group and the discharge of second dots by the second nozzle group, and in the recording step, the arrangement of the first dots discharged by the first nozzle group on the medium 30 is controlled to be more regular than the arrangement of the second dots discharged by the second nozzle group on the medium 30.

[0051] 4. First variation: Modifications included in this embodiment will now be described. Descriptions of the modifications that are common to the embodiments already described will be omitted as appropriate. Combinations of each modification are also included in this embodiment. As described in step S130, the control unit 11 determines the amount of reaction solution to be discharged to the medium 30 according to the amount of ink to be discharged to the medium 30. In the first modified example, when the amount of reaction solution discharged to the medium 30 is less than or equal to a predetermined threshold, the control unit 11 increases the density of the arrangement of the first dots in either the vertical or horizontal direction of the medium 30 to a higher density than the density of the arrangement of the first dots in the other vertical or horizontal direction of the medium 30. Either direction D1 or D2 may be considered the vertical direction. For convenience, direction D2 is considered the vertical direction and direction D1 is considered the horizontal direction.

[0052] Figure 6A shows a magnified example of a portion of the medium 30 on which an image was recorded in step S140 in the first modified example. In Figure 6A, the white circles are reaction dots recorded according to the reaction solution recording data generated in step S130, and the gray circles are ink dots recorded according to the ink recording data generated in step S120. Note that the reaction dots are hardly or not visible to the user. According to Figure 6A, the reaction dots are regularly arranged in both the vertical and horizontal directions. Also, according to Figure 6A, the density of the reaction dots in the vertical direction is higher than the density of the reaction dots in the horizontal direction.

[0053] When an ink dot is ejected in a position that overlaps with a reaction solution dot, it reacts with the reaction solution and fixes to the medium 30 in a nearly circular shape. On the other hand, when an ink dot is ejected in a position that is in contact with a reaction solution dot, it is pulled in the direction of the reaction solution and deforms, fixing to the medium 30 in an elongated oval shape. Furthermore, when an ink dot is ejected in a position that is not in contact with a reaction solution dot, it bleeds more than when it reacts with the reaction solution and fixes to the medium 30 in a nearly circular shape.

[0054] As shown in Figure 6A, when the regular arrangement of reaction solution dots is dense in the vertical direction and sparse in the horizontal direction, the tendency of deformation of ink dots pulled by the reaction solution dots is almost uniformly to deformation in the horizontal direction. Therefore, in the recorded image, the shape of the ink dots is almost uniformly circular and elongated oval. Furthermore, when the regular arrangement of reaction solution dots is dense in the horizontal direction and sparse in the vertical direction, the tendency of deformation of ink dots pulled by the reaction solution dots is almost uniformly to deformation in the vertical direction, so the shape of the ink dots is almost uniformly circular and elongated oval.

[0055] Figure 6B shows a conventional example in contrast to Figure 6A, with a magnified view of a portion of the medium 30. The interpretation of Figure 6B is the same as that of Figure 6A. According to Figure 6B, the arrangement of reaction solution dots is irregular. Therefore, in the recorded image, the shape of the ejected ink dots varies, including circular, horizontally elongated oval, and vertically elongated oval. Thus, according to the first modified example, by making the density of the regular arrangement of first dots in either the vertical or horizontal direction of the medium 30 higher than the density of the regular arrangement of first dots in the other vertical or horizontal direction of the medium 30, the shape of the second dots in the medium 30 can be made as uniform as possible, and the deterioration of granularity can be suppressed.

[0056] Furthermore, in images or areas of images where the ink amount is high-gradation, a large number of reaction liquid dots are ejected in proportion to the ink amount. Therefore, when arranging the reaction liquid dots regularly, it becomes practically difficult to arrange them densely in one direction (vertical or horizontal) and sparsely in the other. Consequently, when arranging the reaction liquid dots regularly, one direction (vertical or horizontal) is arranged more densely than the other only when the amount of reaction liquid ejected onto the medium 30 is below a predetermined threshold. The threshold here is not limited, but for example, it could be a predetermined ink amount appropriate for differentiating between images with halftones and images with high gradation in a given area, or the amount of reaction liquid obtained from the reaction liquid amount table T1 corresponding to this ink amount.

[0057] 5. Second variation: As a second modification, when the control unit 11 records characters onto the medium 30 using ink, the smaller the character size, the denser the arrangement of the first dots. If the image data acquired in step S110 includes characters as objects, the control unit 11 will record the characters onto the medium 30. Compared to the conventional case where the reaction liquid dots are arranged irregularly, by improving the regularity of the arrangement of the reaction liquid dots as in this embodiment, the jaggedness of each line of the characters represented by ink dots is reduced, and the quality of the characters on the medium 30 is improved.

[0058] Figures 7A and 7B, similar to Figure 5, show examples of reaction solution recording data 40 generated in step S130. In Figures 7A and 7B, the string "ABC" is superimposed on the reaction solution recording data 40. This string is an object included in the image represented by the image data and is recorded on the medium 30 according to the ink recording data generated in step S120. The string exemplified in Figure 7A has a smaller character size than the string exemplified in Figure 7B. Therefore, in the second modification, the density of reaction solution dots in the reaction solution recording data 40 of Figure 7A is higher than the density of reaction solution dots in the reaction solution recording data 40 of Figure 7B. The density of reaction solution dots is the number of reaction solution dots per unit distance or per unit area.

[0059] As described above, the control unit 11 can determine the amount of reaction solution for each region corresponding to an object in the image data and determine the arrangement of reaction solution dots for each region. Therefore, when the control unit 11 detects a string of characters as an object from the image data, it can apply the second modification when determining the amount of reaction solution for the region containing this string of characters and determining the arrangement of reaction solution dots. According to this second modification, the smaller the character size, the denser the regular arrangement of reaction solution dots becomes, so the number of reaction solution dots per character can be kept at approximately the same number regardless of the character size, and the quality of the characters on the medium 30 can be improved regardless of the character size. [Explanation of symbols]

[0060] 10...Recording device, 11...Control unit, 12...Program, 13...Display unit, 14...Operation reception unit, 15...Storage unit, 16...Communication IF, 17...Transport unit, 18...Recording unit, 20...Recording head, 21...Nozzle, 22, 22P1, 22P2, 22C, 22M, 22Y, 22K...Nozzle group, 23...Carriage, 24...Platen, 30...Media, 40...Reaction solution recording data, 41...Ink recording data, T1...Reaction solution volume table

Claims

1. A first nozzle group comprising a plurality of nozzles that discharge first dots, which are dots of reaction solution, onto a medium, A second nozzle group consisting of multiple nozzles that eject second dots, which are ink dots containing a colorant that aggregates in the reaction solution, The system comprises a control unit that controls the discharge of the first dot by the first nozzle group and the discharge of the second dot by the second nozzle group, The control unit, The arrangement of the first dots discharged by the first nozzle group in the medium is made more regular than the arrangement of the second dots discharged by the second nozzle group in the medium. The arrangement of the first dot is determined by error diffusion method, A recording device characterized by determining the arrangement of the second dots by dithering.

2. A first nozzle group comprising a plurality of nozzles that discharge first dots, which are dots of reaction solution, onto a medium, A second nozzle group consisting of multiple nozzles that eject second dots, which are ink dots containing a colorant that aggregates in the reaction solution, The system comprises a control unit that controls the discharge of the first dot by the first nozzle group and the discharge of the second dot by the second nozzle group, The control unit, The arrangement of the first dots discharged by the first nozzle group in the medium is controlled to be more regular than the arrangement of the second dots discharged by the second nozzle group in the medium. A recording device characterized in that, when recording characters onto the medium using the ink, the smaller the size of the characters, the denser the arrangement of the first dots.

3. The control unit, The amount of the reaction solution to be discharged into the medium is determined according to the amount of the ink to be discharged into the medium. The recording device according to claim 1 or 2, characterized in that when the amount of the reaction liquid discharged to the medium is less than or equal to a predetermined threshold, the density of the arrangement of the first dots in one of the vertical or horizontal directions of the medium is made higher than the density of the arrangement of the first dots in the other of the vertical or horizontal directions of the medium.

4. A first nozzle group consisting of multiple nozzles that dispense a first dot, which is a dot of the reaction solution, onto a medium, A recording method using a recording device having a second nozzle group comprising a plurality of nozzles that eject second dots, which are ink dots containing a colorant that aggregates with the reaction solution, The system includes a recording step that controls the ejection of the first dot by the first nozzle group and the ejection of the second dot by the second nozzle group. A recording method characterized in that, in the recording step, the arrangement of the first dots is determined by error diffusion and the arrangement of the second dots is determined by dithering, such that the arrangement of the first dots discharged by the first nozzle group in the medium is more regular than the arrangement of the second dots discharged by the second nozzle group in the medium.

5. A first nozzle group consisting of multiple nozzles that dispense a first dot, which is a dot of the reaction solution, onto a medium, A recording method using a recording device having a second nozzle group comprising a plurality of nozzles that eject second dots, which are ink dots containing a colorant that aggregates with the reaction solution, The system includes a recording step that controls the ejection of the first dot by the first nozzle group and the ejection of the second dot by the second nozzle group. In the aforementioned recording process, The arrangement of the first dots discharged by the first nozzle group in the medium is controlled to be more regular than the arrangement of the second dots discharged by the second nozzle group in the medium. A recording method characterized in that, when recording characters onto the medium using the ink, the smaller the size of the characters, the denser the arrangement of the first dots.

Images