Recording device and recording method

Abstract

To provide a recording device preventing a dark part color gamut of a color reproduction region from becoming narrow.SOLUTION: A recording device comprises determination means for determining, when using fluorescent ink to record an image, the order of recording with the fluorescent ink and recording with light-emission suppression ink suppressing light emission of fluorescent ink for each of a plurality of scans. The determination means determines the order of the recording with the fluorescent ink and the recording with the light-emission suppression ink so that the fluorescent ink forms a layer below the light-emission suppression ink in a dark part region of the image.SELECTED DRAWING: Figure 28

Description

[Technical field]

[0001] The present invention relates to a recording apparatus and a recording method for recording an image by applying ink droplets from a recording means onto a recording medium. [Background technology]

[0002] There is known a recording device that records an image on a recording medium using fluorescent ink and non-fluorescent ink. In such a recording device, the use of fluorescent ink makes it possible to record a bright, highly saturated image. Bright, highly saturated fluorescent images are highly eye-catching and are used for posters, point-of-purchase advertising (POP advertising) in retail store promotions, and the like.

[0003] Patent Document 1 describes a method for improving the color development of an image recorded using fluorescent ink. It states that when recording using fluorescent ink and non-fluorescent ink, the color development of an image recorded using fluorescent ink can be improved by controlling the ink amount per pass and the droplet deposition order of each ink. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 139272 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, although a bright, highly saturated, color-developing image can be obtained in the light areas of the color reproduction range using fluorescent ink, the color gamut may become narrow in the dark areas of the color reproduction range.

[0006] An object of the present invention is to provide a recording apparatus and a recording method that prevent the narrowing of the dark color gamut. [Means for solving the problem]

[0007] In order to solve the above problems, a recording apparatus according to the present invention is a recording apparatus that records an image by reciprocating a recording means provided with a nozzle array in a transport direction of the recording medium in a scanning direction intersecting the transport direction of the recording medium and depositing ink droplets from the nozzles of the recording means onto the recording medium, the recording means comprising: Absorbs light at the excitation wavelength and emits light at the emission wavelength a nozzle row corresponding to a fluorescent ink; By absorbing at least one of the light of the excitation wavelength and the light of the emission wavelength, a nozzle row corresponding to a light emission suppressing ink that suppresses the light emission of the fluorescent ink; The recording device includes: a recording control means for controlling the movement of the recording means and the transportation of the recording medium so as to record an image by a plurality of scans of the recording means; a color conversion means for converting image data representing the image into ink data representing the application amounts of the fluorescent ink and the luminescence suppressing ink when the fluorescent ink is used in recording the image; a determination unit that determines an order of recording with the fluorescent ink and recording with the luminescence suppressing ink in the plurality of scans when the fluorescent ink is used in recording the image, the light absorbed by the luminescence suppressing ink is light corresponding to a wavelength near a peak in a spectral spectrum, the fluorescent ink is used in recording the image in a color region between a black point and a maximum saturation point on a color space surface of the image, and the color conversion means converts the image data into the ink data such that an amount of the fluorescent ink applied increases as the distance from the black point approaches the maximum saturation point, The recording control means performs the control based on the order determined by the determination means, and the determination means When the image of the color region is recorded based on the ink data converted by the color conversion means, The order of recording with the fluorescent ink and the luminescence suppressing ink is determined so that the fluorescent ink is recorded in a lower layer than the luminescence suppressing ink. Effect of the Invention

[0008] According to the present invention, it is possible to prevent the dark color gamut from being narrowed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a configuration of a printing system. [Diagram 2] FIG. 2 is a diagram illustrating a recording head. [Diagram 3] FIG. 4 is a diagram showing the arrangement of nozzle rows. [Figure 4] FIG. 13 is a diagram showing excitation intensity and emission intensity when fluorescent pink ink is used for recording. [Diagram 5]FIG. 1 is a diagram showing the angular reflection characteristics of fluorescent ink and subtractive ink. [Figure 6] 1A to 1C are diagrams for explaining an image formation process in an ink accumulation model. [Figure 7] 1A and 1B are diagrams for explaining an image formation process in an ink penetration model. [Figure 8] FIG. 2 is a schematic three-dimensional diagram showing a color reproduction gamut. [Figure 9] 11A and 11B are diagrams for explaining color reproduction when fluorescent pink ink is not used. [Figure 10] FIG. 11 is a diagram showing a color reproduction range when fluorescent pink ink is used. [Figure 11] 13A and 13B are diagrams illustrating the characteristics of fluorescent pink ink when the printing order is changed. [Figure 12] FIG. 11 is a diagram for explaining a recording process under divided recording control. [Figure 13] FIG. 2 is a diagram for explaining a recording state on a recording medium. [Figure 14] FIG. 11 is a diagram for explaining a color reproduction range under divisional recording control. [Figure 15] FIG. 13 is a diagram showing an example of printing in two passes for each ink. [Figure 16] FIG. 13 is a diagram showing another example of a recording head. [Figure 17] FIG. 2 is a diagram for explaining nozzle division of a print head. [Figure 18] FIG. 11 is a diagram for explaining a recording process under divided recording control. [Figure 19] FIG. 2 is a diagram for explaining a recording state on a recording medium. [Figure 20] FIG. 11 is a diagram for explaining a recording process under divided recording control. [Figure 21] FIG. 2 is a diagram for explaining a recording state on a recording medium. [Figure 22] FIG. 11 is a diagram for explaining a color reproduction range under divisional recording control. [Figure 23] FIG. 2 is a diagram for explaining nozzle division of a print head. [Figure 24]FIG. 11 is a diagram for explaining a recording process under divided recording control. [Diagram 25] FIG. 2 is a diagram for explaining a recording state on a recording medium. [Figure 26] FIG. 11 is a diagram for explaining a recording process under divided recording control. [Figure 27] FIG. 2 is a diagram for explaining a recording state on a recording medium. [Figure 28] 13 is a flowchart showing a recording control process. [Figure 29] 13 is a flowchart showing a recording control process. [Diagram 30] 13 is a flowchart showing a recording control process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] [First embodiment] The terms used in this specification are defined as follows. In this specification, "recording" refers not only to the formation of meaningful information such as characters and figures, but also to any information that is meaningful or insignificant, and whether it is visible to humans or not. It also broadly refers to the formation of images, designs, patterns, etc. on a recording medium, or the processing of the medium.

[0012] "Recording medium" refers not only to paper used in general recording devices, but also broadly to anything that can accept ink, such as cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc.

[0013] The term "ink" should be interpreted broadly in the same way as the definition of "recording" above. It refers to a liquid that can be applied to a recording medium to form an image, design, pattern, etc., or to process the recording medium, or to treat the ink. Here, the treatment of the ink refers to, for example, solidification or insolubilization of the coloring material in the ink applied to the recording medium.

[0014] Unless otherwise specified, the term "nozzle" collectively refers to an ejection port, a liquid path communicating with the ejection port, and an element that generates energy used to eject ink.

[0015] In order to record on a recording medium, a recording head scans the recording medium to perform recording. Here, the term "scanning" refers to head movement during acceleration and deceleration for recording or related to recording.

[0016] "Color reproduction range" is also called color reproduction range, color gamut, or gamut. Generally, it refers to the range of colors that can be reproduced in any color space. In addition, color gamut volume is an index that indicates the width of this color reproduction range. Color gamut volume is a three-dimensional volume in any color space. The chromaticity points that make up the color reproduction range may be discrete. For example, a specific color reproduction range may be represented by 729 points on the CIE-L*a*b*, and the points between them may be calculated using known interpolation calculations such as tetrahedral interpolation and cubic interpolation. In such a case, the corresponding color gamut volume can be calculated and accumulated to use the volume of the tetrahedron or cube that makes up the color reproduction range on the CIE-L*a*b* in accordance with the interpolation calculation method.

[0017] Although the color reproduction range and color gamut in this specification are not limited to a specific color space, the color reproduction range in the CIE-L*a*b* space is used as an example for explanation in this specification. Similarly, the numerical values ​​of the color reproduction range in this specification indicate the volume when cumulatively calculated in the CIE-L*a*b* space on the premise of tetrahedral interpolation.

[0018] <Entire system of records> FIG. 1 is a block diagram showing the configuration of a printing system according to the present embodiment. A host PC or a tablet PC is used as the PC 101. The CPU 102 reads out a program stored in the HDD 104 into a RAM 103 as a work area and executes the program to execute various processes. For example, the CPU 102 generates recording data that can be recorded by the recording device 108 and transfers the data to the recording device 108 according to a command received from a user via a HID (Human Interface Device) I / F 106 or a touch panel (not shown) or a program stored in the HDD 104. The CPU 102 also performs a predetermined process on the recording data received from the recording device 108 via the data transfer I / F 107 according to a program stored in the HDD 104, and displays the results and various information on a display (not shown) via a display I / F 105.

[0019] In the recording device 108, the CPU 111 reads out a program stored in the ROM 113 into the RAM 112 as a work area and executes the program, thereby controlling the recording device 108 in an overall manner. The image processing accelerator 109 is hardware capable of executing image processing faster than the CPU 111. The image processing accelerator 109 is started by the CPU 111 writing parameters and data required for image processing to a predetermined address in the RAM 112. After reading the parameters and data, the image processing accelerator 109 executes image processing on the data. However, the image processing accelerator 109 is not an essential element, and equivalent processing may be executed by the CPU 111. The parameters may be stored in the ROM 113, or may be stored in a storage (not shown) such as a flash memory or a HDD.

[0020] Here, we will explain the image processing performed by the CPU 111 or the image processing accelerator 109. The image processing is, for example, processing that generates data indicating the ink dot formation positions in each scan by the print head 115 based on the received print data. The CPU 111 or the image processing accelerator 109 performs color conversion processing and quantization processing on the received print data.

[0021] The color conversion process is a process of separating colors into ink densities handled by the recording device 108. For example, the received recording data includes image data showing an image and fluorescent data for fluorescent printing. When the image data is data showing an image in color space coordinates such as sRGB, which is the display color of the monitor, the data showing the image in the sRGB color coordinates (R, G, B) is converted into subtractive ink data (CMYK) handled by the recording device 108 or ink data (CMYKF) containing fluorescent ink colors. The fluorescent data is converted into fluorescent ink data. Furthermore, when there are both data showing an image in sRGB color coordinates (R, G, B) and fluorescent data, the data is converted into both subtractive ink data (CMYK) and fluorescent ink data. Alternatively, the data is converted into both ink data (CMYKF) containing fluorescent ink colors and fluorescent ink data. In that case, the fluorescent ink data is generated in two planes. The color conversion method is realized by a matrix calculation process, a process using a three-dimensional LUT (lookup table), a four-dimensional LUT, or the like.

[0022] The recording device 108 of this embodiment uses black (K), cyan (C), magenta (M), yellow (Y), and fluorescent (F) inks as an example. Therefore, the image data and fluorescent data of the RGB signal are converted into image data consisting of 8-bit color signals of K, C, M, Y, and F. The color signals of each color correspond to the amount of each ink applied. Although five colors, K, C, M, Y, and F, are given as an example of the number of ink colors, other ink colors such as light cyan (Lc), light magenta (Lm), and gray (Gy) inks with low density may be used to improve image quality. In that case, ink signals corresponding to those colors are generated. In this embodiment, light cyan (Lc), light magenta (Lm), and gray (Gy) inks will be described as subtractive color inks. Furthermore, achromatic color inks such as black (K) and gray (Gy) will be described as subtractive color inks.

[0023] After the color conversion process, a quantization process is performed on the ink data. The quantization process is a process for reducing the number of gradation levels of the ink data. In this embodiment, quantization is performed using a dither matrix in which threshold values ​​for comparison with the ink data value for each pixel are arranged. After the quantization process, binary data is ultimately generated that indicates whether or not a dot will be formed at each dot formation position.

[0024] After image processing, the binary data is transferred to the recording head 115 by the recording head controller 114. At the same time, the CPU 111 performs recording control via the recording head controller 114 to operate a carriage motor that operates the recording head 115, and further to operate a transport motor that transports a recording medium (paper). The recording head 115 scans over the recording medium, and at the same time, the recording head 115 deposits ink droplets onto the recording medium, thereby forming an image.

[0025] When printing by multiple scans, a predetermined image processing is performed, followed by a scan order determination process. The scan order determination process is a process of thinning out images by using a mask pattern or the like on the data after quantization processing in order to generate data corresponding to each scan. At this time, the image processing accelerator 109 may be used to speed up the process.

[0026] The PC 101 and the recording device 108 are connected via a communication line 100. In this embodiment, a local area network is described as an example of the communication line 100, but it may be a wireless communication network using a USB hub or a wireless access point, a connection using a Wifi Direct communication function, or the like.

[0027] In the following description, the recording head 115 is assumed to have five recording nozzle rows in total, one for each of four color inks, cyan (C), magenta (M), yellow (Y), and black (K), and one for each of fluorescent inks, fluorescent pink (FP). The fluorescent ink may be fluorescent red (FR), fluorescent yellow (FY), fluorescent green (FG), or fluorescent blue (FB), in addition to fluorescent pink.

[0028] <Regarding the recording head of the recording device> FIG. 2 is a diagram for explaining the print head 115 in this embodiment. In this embodiment, an image is printed on a unit area of ​​one nozzle row by multiple scans N times. The print head 115 has a carriage 116, nozzle rows 115k, 115c, 115m, 115y, and 115FP, and an optical sensor 118. The carriage 116 carrying the five nozzle rows 115k, 115c, 115m, 115y, and 115FP and the optical sensor 118 can be moved back and forth along the X direction (main scanning direction) in the figure by the driving force of a carriage motor transmitted via a belt 117. As the carriage 116 moves in the X direction relative to the print medium, ink droplets are ejected from each nozzle of the nozzle row in the direction of gravity (-z direction in the figure) based on print data. As a result, an image of 1 / N main scans is printed on the print medium placed on the platen 119. When one main scan is completed, the recording medium is transported in a transport direction that intersects with the main scanning direction (-y direction in the figure) a distance corresponding to the width of 1 / Nth of a main scan. Through these operations, an image with a width equivalent to one nozzle row is recorded over N multiple scans. By alternating between such main scanning and transport operations, an image is gradually formed on the recording medium.

[0029] The printing resolution in the X direction is determined by the ejection frequency and the moving speed of the carriage. The printing resolution in the Y direction is determined by the nozzle resolution of the print head 115. In this embodiment, for example, both printing resolutions are set to 600 dpi. Therefore, the ejected ink dots are printed at a resolution of 600 dpi in both the vertical and horizontal directions. The optical sensor 118 performs a detection operation while moving together with the carriage 116, thereby determining whether a printing medium is present on the platen 119.

[0030] <Description of the recording head> FIG. 3 is a diagram showing the arrangement of nozzle rows when the recording head 115 is viewed from the top surface (-z direction) of the recording device 108. In the recording head 115, five nozzle rows are arranged at different positions in the X direction. That is, a nozzle row 115C corresponding to C ink, a nozzle row 115M corresponding to M ink, a nozzle row 115Y corresponding to Y ink, a nozzle row 115K corresponding to K ink, and a nozzle row 115FP corresponding to FP ink are arranged. Ink droplets of C ink are ejected from the nozzles of the nozzle row 115C. Ink droplets of M ink are ejected from the nozzles of the nozzle row 115M. Ink droplets of Y ink are ejected from the nozzles of the nozzle row 115Y. Ink droplets of K ink are ejected from the nozzles of the nozzle row 115K. Ink droplets of FP ink are ejected from the nozzle row 115FP. In each nozzle row, a plurality of nozzles for ejecting ink droplets are arranged at a predetermined pitch along the Y direction.

[0031] <Characteristics of fluorescent inks and subtractive inks> A fluorescent coloring material is a coloring material that changes from a ground state to an excited state by absorbing light of an excitation wavelength, and then emits light of an emission wavelength and returns to the ground state to develop color. Figure 4 is a graph showing the intensity of an excitation wavelength 401 and the intensity of an emission wavelength 402 when fluorescent pink ink is recorded on a recording medium. The horizontal axis of Figure 4 indicates the wavelength of light, and the vertical axis indicates the intensity. The graph in Figure 4 shows the intensity of each light when the wavelength of light irradiated on a recording sample and the wavelength of light received from the sample are respectively changed and detected.

[0032] The emission wavelength 402 represents the intensity of light received from the recording sample when the recording sample is irradiated with light of an exciting wavelength for each wavelength. FIG. 4 shows the case where the recording sample is irradiated with light of 480 nm. The excitation wavelength 401 represents the intensity of light received when the wavelength of the light irradiated to the recording sample is changed while the wavelength of the light received is fixed. FIG. 4 shows the case where the wavelength of the light received is fixed at 600 nm. As shown in FIG. 4, the wavelength range of excitation of the fluorescent ink recorded on the recording medium overlaps with the wavelength range of emission and is on the short wavelength side. In addition, the excitation wavelength 401 has strengths and weaknesses for each wavelength, and there are wavelengths that emit light efficiently and wavelengths that do not. In addition, since the fluorescent coloring material emits light, the reflectance at the emission wavelength often exceeds 1. In this embodiment, a coloring material having the above-mentioned characteristics is called a fluorescent coloring material.

[0033] In the above, the excitation and emission of the fluorescent pink ink have been described, but in this embodiment, fluorescent inks that emit light of other wavelengths may be used. For example, fluorescent blue ink that emits light in the blue region (450 nm to 500 nm) may be used, or fluorescent green ink that emits light in the green region (500 nm to 565 nm) may be used. Furthermore, fluorescent yellow ink that emits light in the yellow region (565 nm to 590 nm) may be used, or fluorescent orange ink or fluorescent red ink that emits light in the red region (590 nm to 780 nm) may be used. Furthermore, fluorescent inks that are a combination of the above may be used. For example, fluorescent yellow ink that emits light in a region that combines the yellow region and the red region may be used. Furthermore, fluorescent inks with different excitation wavelength intensities may be combined to adjust the color tone. For example, fluorescent pink that emits light in the orange region, with weak excitation in the blue region and strong excitation in the green region, may be used.

[0034] In this embodiment, non-fluorescent ink is called subtractive ink. In other words, ink that absorbs light of a specific wavelength among light incident thereon and does not emit light is called subtractive ink. For example, subtractive ink has the spectral reflectance shown by cyan ink 403, magenta ink 404, and yellow ink 405 in FIG. 4. Note that the graph in FIG. 4 shows the results measured using a method for measuring the spectral reflectance. Unlike fluorescent ink, subtractive ink only absorbs light, so the reflectance does not exceed 1.

[0035] Next, mixing of fluorescent ink and subtractive ink on a recording medium will be described with reference to Fig. 4. When fluorescent pink ink and yellow ink 405 are mixed, the yellow ink absorbs light in the wavelength range of the excitation wavelength 401 of the fluorescent pink ink. Therefore, the fluorescent pink ink cannot be sufficiently excited because the exciting light is absorbed by the yellow ink, and light emission is suppressed.

[0036] When fluorescent pink ink and cyan ink 403 are mixed, the cyan ink absorbs light in the wavelength range of the fluorescent pink ink's emission wavelength 402. Therefore, the light emitted by the fluorescent pink ink is absorbed by the cyan ink, and the emission is suppressed.

[0037] When fluorescent pink ink and magenta ink 404 are mixed, the magenta ink absorbs light in the wavelength range to which the fluorescent pink ink has a high excitation sensitivity. As a result, the fluorescent pink ink cannot be sufficiently excited, and its emission is suppressed. Furthermore, the light emitted by the fluorescent pink ink is absorbed by the magenta ink, and its emission is also suppressed.

[0038] When fluorescent pink ink and black ink (not shown) are mixed, the black ink absorbs light in the wavelength range of the excitation wavelength 401 of the fluorescent pink ink, and also absorbs light in the wavelength range of the emission wavelength 402. As a result, the fluorescent pink ink cannot be sufficiently excited, and emission of light is also suppressed.

[0039] In other words, when fluorescent pink ink and subtractive ink are mixed, the contribution rate of the fluorescent pink ink to color development decreases. This characteristic is also greatly affected by the positional relationship between the fluorescent ink and the subtractive ink on the recording medium. Compared to when an ink layer of fluorescent ink is located above an ink layer of subtractive ink, an ink layer below the ink layer of fluorescent ink is more strongly influenced by the subtractive ink. As a result, the contribution rate of the fluorescent pink ink to color development is also smaller when the fluorescent ink is located below the subtractive ink compared to when the fluorescent ink is located above the subtractive ink.

[0040] The angular reflectance characteristics of fluorescent ink and subtractive ink are explained with reference to FIG. 5. In FIG. 5, the solid line indicates the fluorescent ink and the dashed line indicates the subtractive ink, and the bidirectional reflectance distribution function for the angular reflectance characteristics of each ink is shown. For example, the angular reflectance characteristics can be measured by irradiating a sample recorded on a recording medium with vertical light and detecting the reflected light at different angles. As shown in FIG. 5, the angular reflectance characteristics of fluorescent ink show that light is scattered isotropically compared to the angular reflectance characteristics of subtractive ink. This is because the fluorescent ink absorbs light, is excited, and emits light, so that the incident light has no directionality and is strongly dependent on the directionality of the fluorescent ink's emission. Thus, fluorescent ink has a tendency to scatter light more strongly than subtractive ink.

[0041] <About fluorescent ink> Next, the fluorescent ink used in this embodiment will be described. In this embodiment, fluorescent ink is used that is created by mixing a dispersion of a coloring material having fluorescent properties with a solvent and an activator. The dispersion of the fluorescent coloring material used in this embodiment is a dispersion of a coloring material having fluorescent properties as described above. For example, NKW-3207E (fluorescent pink water dispersion: Nippon Kinko Kagaku Co., Ltd.) or NKW-3205E (fluorescent yellow water dispersion: Nippon Kinko Kagaku Co., Ltd.), but any dispersion of a coloring material having fluorescent properties will do.

[0042] The fluorescent colorant dispersion is combined with a known solvent and an activator to disperse the fluorescent colorant dispersion, thereby forming an ink. The dispersion method of the fluorescent colorant dispersion is not particularly limited. For example, a fluorescent colorant dispersion dispersed with a surfactant, a resin-dispersed fluorescent colorant dispersion dispersed with a dispersion resin, etc. can be used. Of course, it is also possible to use fluorescent colorant dispersions with different dispersion methods in combination. The surfactant can be an anionic, nonionic, cationic, or amphoteric activator. Any resin that is water-soluble or water-dispersible can be used as the dispersion resin, but it is particularly preferable that the weight-average molecular weight of the dispersion resin is 1,000 or more and 100,000 or less, and further 3,000 or more and 50,000 or less. The solvent is preferably an aqueous medium containing, for example, water and a water-soluble organic solvent.

[0043] In this embodiment, for example, five colors of pigment inks, namely black (K), cyan (C), magenta (M), yellow (Y), and fluorescent pink (FP), are used as the inks.

[0044] <Recording Media> The recording medium in this embodiment has a base material and at least one ink receiving layer. In this embodiment, for example, a recording medium for recording by an inkjet recording method is used. In this embodiment, for example, glossy paper is used as the recording medium, and pigment ink is used as the coloring material.

[0045] <Image formation process on recording media: Ink deposition model> The image formation process on a recording medium will be described with reference to Fig. 6. Fig. 6 is a diagram for explaining the image formation process in an ink deposition model in which ink that has landed on a recording medium is deposited on the recording medium. This corresponds to the image formation process when recording on glossy paper, for example, in which the voids present on the recording medium surface are smaller than the particle diameter of the coloring material particles that contribute to color development in the pigment ink. The ink deposition model is a model of the image formation process in which the particle diameter of the coloring material particles that contribute to color development in the ink is larger than the voids on the recording medium surface, and the coloring material particles are deposited above the recording medium surface to form an ink layer and form an image.

[0046] The image formation is carried out as shown in FIG. 6(a) to FIG. 6(d).

[0047] As shown in FIG. 6(a), pigment ink G1 is applied onto a recording medium P. Then, as shown in FIG. 6(b), pigment ink G1 lands on the recording medium P and accumulates. Furthermore, subsequent pigment ink G2 is applied. Then, as shown in FIG. 6(c), pigment ink G2 lands on the already accumulated pigment ink G1. Then, as shown in FIG. 6(d), pigment ink G2 accumulates on the already accumulated pigment ink G1 to form a layer. In this way, in the ink accumulation model, an image is formed in which subsequent dots remain on the upper layer of the recording medium. For example, when glossy paper is used as the recording medium and pigment ink is used as the coloring material, an image is formed by the ink accumulation model. In this embodiment, a recording medium of the ink accumulation model is used.

[0048] <Color reproduction of fluorescent pink ink> The color reproduction of fluorescent pink ink (FP) will now be described. Fig. 8 is a diagram showing the color reproduction range as a schematic solid. In this color solid, the gray line from white point W to black point K is at the center, and the R, Y, G, C, B, and M points are maximum saturation points for each of the R, Y, G, C, B, and M hues. Hereinafter, the maximum saturation points in this color solid will be called primaries.

[0049] The WMK surface involving fluorescent pink ink will be described. First, as a comparison, the case where fluorescent pink ink is not used will be described. FIG. 9(a) is a diagram for explaining the color reproduction of the WMK surface when fluorescent pink ink is not used, on the chroma C*-lightness L* of CIE L*a*b*. Here, C*=√(a*^2+b*^2). As shown in FIG. 9(a), it can be seen that the color reproduction gamut WMK is a triangle shape surrounded by almost straight lines. FIG. 9(b) is a diagram showing how to use inks (color separation) on the WMK line to achieve this color reproduction. As shown in FIG. 9(b), the amount of M ink increases from the white point W toward the primary M, and the amount of K ink increases from the primary M to the black point K.

[0050] Meanwhile, the thick line in Fig. 10(a) shows the conventional color reproduction range when fluorescent pink ink is used. The area shown by vertical hatching is bright and saturated due to the color gamut expansion effect of fluorescent pink ink. However, in the dark color area shown by horizontal hatching, hollowing out occurs and the color gamut is narrower than when fluorescent pink ink is not used. Fig. 10(b) is a diagram showing how to use inks (color separation) on the WMK lines to achieve this color reproduction. As shown in Fig. 10(b), the amount of fluorescent pink ink increases from the white point W toward the primary M, and the amount of K ink increases from the primary M to the black point K.

[0051] <Fluorescent pink ink recording order and color reproduction> Fig. 11(a) is a diagram showing the change in lightness when fluorescent pink ink is applied in different amounts to a constant amount of 150% K ink. Fig. 11(a) shows the change in lightness when the printing order is changed. As shown in Fig. 11(a), when the fluorescent pink ink is printed as the upper layer on the printing medium, it can be seen that the lightness L* becomes brighter as the amount of colorant of the fluorescent pink ink applied increases.

[0052] FIG. 11B shows the reflection spectrum at that time. FIG. 11B shows the reflection spectrum when 75% of fluorescent pink ink is added to 150% of K ink. When the fluorescent pink ink is printed on the upper layer of the recording medium, the reflection is strong near 590 [nm] where the emission spectrum of the fluorescent pink ink peaks, and it can be seen that the emission effect of the fluorescent pink ink remains even in such a dark area. From the above, it can be seen that the cause of the hollowing out of the color area in the dark area when the fluorescent pink ink is used is that the fluorescent pink ink is printed on the upper layer, and the luminous effect of the fluorescent pink ink is expressed. In this embodiment, the emission effect of the fluorescent pink ink can be reduced by controlling the printing order of the inks with respect to the hollowing out of the color area in the dark area when the fluorescent pink ink is used.

[0053] As shown in Fig. 11(a), when the fluorescent pink ink is printed on the recording medium at the bottom, the lightness L* can be kept almost constant regardless of the amount of coloring material of the fluorescent pink ink. In the reflection spectrum of Fig. 11(b), when the fluorescent pink ink is printed on the recording medium at the bottom, there is no peak even at around 590 [nm], and reflection can be suppressed over the entire spectrum.

[0054] This is because the light emitted from the fluorescent pink ink on the recording medium is absorbed by the black ink, which is located in a layer above the fluorescent pink ink and has an absorption effect at the emission wavelength of the fluorescent pink ink of about 590 [nm] and has an effect of suppressing light emission. Note that other inks may be used as the light emission suppressing ink as long as they have an absorption effect at the emission wavelength of 590 [nm] of the fluorescent pink ink. For example, as shown in the spectrum for each ink in FIG. 4, light emission suppression is possible even with cyan ink 403. Also, with gray (Gy) ink, like K ink, reflection can be suppressed over the entire spectrum, and light emission suppression is possible.

[0055] As shown in Fig. 11(a), when fluorescent pink ink and K ink are mixed and recorded in the same ink layer, it is possible to suppress the increase in lightness L* when the amount of coloring material in the fluorescent pink ink is increased. In the reflection spectrum of Fig. 11(b), when fluorescent pink ink and K ink are mixed and recorded in the same ink layer, the peak at 590 [nm] is suppressed to a very small amount, and reflection is largely suppressed across the entire spectrum.

[0056] This is thought to be because the K ink, which has an absorption effect around 590 [nm] and has the effect of suppressing luminescence, is adjacent to the fluorescent pink ink and absorbs part of the isotropic luminescence from the fluorescent pink ink on the recording medium. This type of mixed recording in the same ink layer also makes it possible to suppress the increase in lightness L* when the fluorescent pink ink is added.

[0057] For the above reasons, in this embodiment, in order to prevent narrowing of the color area in the dark portion, printing is performed by controlling so that the fluorescent pink ink is mixed or is in the lower layer of the printing medium.

[0058] Fig. 28 is a flowchart showing the recording control process in this embodiment. The process in Fig. 28 is realized, for example, by the CPU 111 of the recording device 108 reading a program stored in the ROM 113 into the RAM 112 and executing it. In this embodiment, in order to prevent the color area of ​​the dark parts from narrowing, recording is performed by controlling so that fluorescent pink ink is mixed or becomes the lower layer of the recording medium.

[0059] In S101, the CPU 111 receives recording data transmitted from the PC 101. The recording data includes RGB data and fluorescent data. In S102, the CPU 111 determines whether or not fluorescent ink is to be used for image formation. This determination may be made based on whether the user has specified a fluorescent mode or a fluorescent non-fluorescent mode as the recording mode of the recording device 108. For example, if the user manually sets either of these modes and uses them, the determination is made in conjunction with the user's manual setting. Alternatively, it may be determined that fluorescent ink is to be used when fluorescent data is received as separate data in addition to RGB data. If it is determined that fluorescent ink is to be used, the process proceeds to S103, and if it is determined that fluorescent ink is not to be used, the process proceeds to S105.

[0060] In S104, CPU 111 determines the position on the input RGB color space for each pixel from the received recording data. That is, CPU 111 determines whether or not the pixel of the recording data is located between the maximum saturation point and the black point on the RGB color space surface. For example, the determination may be made based on whether at least one of (R, G, B) is 0. If it is determined that the pixel is located between the maximum saturation point and the black point on the RGB color space surface, the process proceeds to S104. On the other hand, if it is determined that the pixel is not located between the maximum saturation point and the black point on the RGB color space surface, the process proceeds to S105.

[0061] In S104, the CPU 111 sets a mask for controlling the printing order for each ink color. In multi-pass printing in which the print head 115 prints in the same image area multiple times in a thinned-out manner, mask processing is performed using a thinning pattern (hereinafter, mask pattern). This mask pattern is a pattern in which ON / OFF is determined for each pixel in each scan (pass), and printing can be performed only when ON in each pass to thin out the print dots. The mask pattern may be stored in the ROM 113 of the printing device 108, or may be acquired from the HDD 104 of the PC 101. The mask processing is a process for determining which nozzle of the print head 115 will print in which pass for the quantized image data. In this embodiment, the mask processing is used to control changing the printing order of the inks, and the mask setting is switched for each color. In S104, the CPU 111 sets a pre-deposit mask for fluorescent ink, which prints on the upstream side. Furthermore, the CPU 111 sets a post-printing mask for printing on the downstream side for the light emission suppressing ink, and sets pre-printing and post-printing masks for printing on the entire upstream and downstream sides combined for the other inks.

[0062] In S105, the CPU 111 sets masks in the same way as in S104, but sets pre-print and post-print masks for printing on the entire upstream and downstream sides for all ink colors. S103 to S105 are repeated for each pixel.

[0063] In S106, the CPU 111 generates color separation data from the print data received in S101. The color separation data may be generated by, for example, reading a 3DLUT (lookup table) stored in the ROM 113 into the RAM 112 and performing an interpolation operation such as tetrahedral interpolation by the image processing accelerator 109. In S107, the CPU 111 performs output gamma correction according to the dot coverage on the print medium. In S108, the CPU 111 performs quantization processing. As a result of the quantization processing, binary data corresponding to the ON / OFF of dots at the output resolution is generated. In S109, the CPU 111 compares the quantized data with the mask for each color set in S104 or S105, and determines the nozzles to be used for printing each scan. In S110, the CPU 111 scans the carriage and controls the print head 115 to print dots from the determined nozzles.

[0064] <Control of ink printing order> In this embodiment, in order to prevent the color region of the dark portion from narrowing, the printing order is controlled so that the fluorescent pink ink is mixed in the same ink layer or is the lower layer of the recording medium. In order to print the fluorescent pink ink so that it is mixed in the same ink layer or is the lower layer of the recording medium, the nozzle array of the print head 115 is divided into two groups, upper and lower, and divided printing control is performed in which the nozzles are scanned back and forth to print.

[0065] 12 is a diagram for explaining the recording process of divided recording control on a recording medium by the recording head 115, K ink nozzles 115K, and fluorescent pink ink nozzles 115FP. For the sake of explanation, two inks are taken up here: fluorescent pink ink that emits light and K ink that suppresses light emission, and the case where ink is ejected from all applicable nozzles is explained. Normally, the recording medium is transported relative to the recording head 115 for recording, but for the sake of explanation below, the recording medium is in a fixed position and the recording head 115 moves.

[0066] 12 is a diagram for explaining divided printing control in which fluorescent pink ink is deposited first to form a lower layer on the printing medium, and K ink is deposited later to form an upper layer on the printing medium. The nozzles of the print head 115 are divided into upper and lower nozzles along the sub-scanning direction for use. The fluorescent pink ink nozzles 115FP are half the width of the full nozzles upstream in the transport direction (corresponding to the sub-scanning direction) shown with diagonal lines. The K ink nozzles 115K are half the width of the full nozzles downstream in the transport direction, shown with black lines.

[0067] The printing operation will be described in detail. In the forward main scan (1), on the upstream side of the print head 115, printing is performed with fluorescent pink ink at 1 / 2 the width of a full nozzle. At that time, on the downstream side, printing is performed with K ink at 1 / 2 the width of a full nozzle. Then, sub-scan (1) is performed, which is a transport of 1 / 2 the width of a full nozzle. The position of the print head on the print medium after the sub-scan (1) operation is position 1201. In the upstream part of the return main scan (2), the fluorescent pink ink arrives first on the blank part of the print medium and is printed. In the downstream part of the return main scan (2), the K ink is printed on top of the print medium where the fluorescent pink ink arrived first in the main scan (1). This series of operations is repeated to print on the entire print medium. In FIG. 12, area 1202 does not indicate the start or end of printing, but indicates an area where the above repetition is in a steady state. After the recording medium is transported in the sub-scanning (2), the K ink is printed on top of the fluorescent pink ink that has already landed on the recording medium in the downstream portion of the main scanning (3) in the forward direction. The same process is repeated below.

[0068] Fig. 13(a) is a diagram for explaining the recording state on the recording medium obtained by the divided recording operation of Fig. 12. Normally, the recording medium is transported to the recording head 115 and recording is performed, but for the sake of explanation, the following will be explained as a diagram in which the recording medium is fixed in position and the recording head 115 moves. Also, for the sake of explanation, the ink recording order and the ink layers that are formed will be explained as being ejected from all of the targeted nozzles.

[0069] The printing state in the first pass is shown in printing state 1301. The blackened areas indicate areas printed with K ink, and the shaded areas indicate areas printed with fluorescent pink ink. As shown in printing state 1301, by main scanning (1) in the forward direction, printing with K ink (blackened areas) is performed on white paper downstream of the first pass. In addition, the shaded areas indicate that printing with fluorescent pink ink is performed on white paper upstream of the first pass.

[0070] The state in which a second pass is printed over the first pass is shown in a printing state 1302. As shown in the printing state 1302, by main scanning (2) in the return direction, downstream of the second pass, printing is performed in K ink (blackened area) over the area (shaded area) that has already been printed in fluorescent pink ink in the first pass. Additionally, upstream of the second pass, printing is performed in fluorescent pink ink on white paper (shaded area).

[0071] The printing state of the third pass is shown in printing state 1303. As shown in printing state 1303, by main scanning (3) in the forward direction, downstream of the third pass, printing (blackened area) is performed in K ink over the area (shaded area) that has already been printed in advance with fluorescent pink ink in the second pass. Additionally, upstream of the third pass, printing (shaded area) is performed in fluorescent pink ink on white paper.

[0072] The printing operation in which K ink is printed (blackened area) on top of an area already printed with fluorescent pink ink (shaded area) is repeated in a second pass, a third pass, and so on. The area in which this repeated steady-state printing is performed is area 1202 in Figure 12. From the above, in the steady-state area 1202, the fluorescent pink ink arrives first on the print medium and becomes the lower layer, and the K ink follows and becomes the upper layer of the print medium.

[0073] For the sake of explanation, the control of the ink printing order and the ink layers formed have been described assuming that all target nozzles eject ink. However, in reality, the printing duty of the fluorescent pink ink and the K ink differs depending on the color to be printed. The printing duty for each ink in this embodiment for the WMK lines of the color solid in FIG. 8 is shown in FIG. 10(b). That is, the printing duty is determined so that the amount of fluorescent pink ink increases as it approaches the primary M from the white point W, and the amount of K ink increases from the primary M to the black point K.

[0074] Fig. 13(b) is a diagram showing all combinations of the printing states of ink layers on a printing medium when the divided printing control of Fig. 12 is performed with the printing duty shown in Fig. 10(b). As shown in Fig. 13(b), all possible combinations include a state in which two layers are overlapped, with fluorescent pink ink as the lower layer and K ink as the upper layer, a state in which there is only one layer of fluorescent pink ink, and a state in which there is only one layer of K ink. In this way, in this embodiment, the printing order is controlled so that the fluorescent pink ink is mixed in the same ink layer or is the lower layer of the printing medium.

[0075] Fig. 14 is a diagram for explaining the color reproduction range by the divided print control of this embodiment. The dark color range by conventional print control is shown by the dotted line M'-K, and the dark color range by the print control of this embodiment is shown by the thick line M'-K. As shown in Fig. 14, the dotted line M'-K is hollowed out and convex upward, whereas the thick line M'-K by the print control of this embodiment is closer to a straight line. In other words, the divided print control of this embodiment can suppress the above-mentioned "hollowing out" and prevent the dark color range from narrowing.

[0076] In the division printing control of this embodiment, an example has been described in which the print head 115 is divided into two, transported by 1 / 2 nozzle width per main scan, and the number of scans (number of passes) is two. However, the number of passes does not necessarily have to match the number of divisions, and the number of passes for each ink may be greater than the number of divisions. For example, FIG. 15 is a diagram showing an example in which the print head 115 is divided into two, transported by 1 / 4 nozzle width per main scan, and the number of passes is four. As shown in FIG. 15, the print head 115 performs four passes as a whole, but the fluorescent pink ink and the K ink are each printed in two passes. With such a configuration, it is possible to reduce band unevenness caused by unevenness or twisting of the nozzles of the print head 115, and perform high-quality printing.

[0077] As an image formation by ink on a recording medium, the division control in which the nozzle use range of the recording head 115 is divided equally into two groups, upper and lower, and controlled has been described. The division control of this embodiment is sufficient as long as it can control the landing order of the inks to be recorded. Therefore, the division method does not have to be equal division, and for example, division may be performed such that K ink is divided into 2 / 3 and fluorescent pink ink is divided into 1 / 3. With such a configuration, recording can be performed at a higher speed when recording in which K ink is used more. In addition, the number of divisions does not have to be 2, and may be 3 or more. By dividing the number of divisions into 3, for example, nozzles may be assigned to the bottom layer of the recording medium, K ink to the middle layer, and clear ink for overcoat to the top layer. By dividing the number of divisions into 3 in this way, not only can narrowing of the color area of ​​the dark part of the fluorescent pink ink be prevented, but also other image quality controls such as gloss control can be performed in parallel.

[0078] Also, although an example of division within one print head 115 has been described, for example, two print heads may be used to divide the print heads into a preceding print head and a succeeding print head, and the print heads may be used to perform printing. FIG. 16 is a diagram for explaining a print head unit using two print heads. A print head unit 1601 is composed of a print head 115H used for printing on the upstream side in the sub-scanning direction, and a print head 115L used for printing on the downstream side. Using multiple print heads in this way enables high-speed printing using the full nozzle width for each.

[0079] In addition, the ink landing order control may be performed by a control different from the divided printing control described in this embodiment. For example, printing may be performed with fluorescent pink ink during odd-numbered printing scans, and with K ink during even-numbered printing scans. With such a configuration, the variation in the frequency of nozzle use can be reduced, and the life of the print head 115 can be extended.

[0080] [Second embodiment] The second embodiment will be described below focusing on the differences from the first embodiment. In this embodiment, the luminous properties of the fluorescent pink ink are utilized to expand the color gamut in the bright color region while controlling printing to prevent narrowing of the color gamut in the dark color region.

[0081] In this embodiment, in the color regions of the bright parts, the fluorescent pink ink is recorded in the same ink layer as the other subtractive color inks or in the upper layer of the recording medium, thereby realizing an expansion of the color gamut by making use of the luminescence. Also, in the color regions of the dark parts, the fluorescent pink ink is recorded in the same ink layer as the luminescence suppressing inks or in the lower layer of the recording medium, thereby reducing the influence of the luminescence and preventing the narrowing of the color regions of the dark parts.

[0082] Fig. 29 is a flowchart showing the process of recording control in this embodiment. The process in Fig. 29 is realized, for example, by the CPU 111 of the recording device 108 reading out a program stored in the ROM 113 into the RAM 112 and executing it. In this embodiment, in the color region of the bright part, the fluorescent pink ink is controlled to be mixed with other subtractive color mixing inks or to be in the upper layer of the recording medium, thereby realizing an expansion of the color gamut making use of the luminescence. In addition, in the color region of the dark part, the fluorescent pink ink is controlled to be mixed with the luminescence suppressing inks or to be in the lower layer of the recording medium, thereby suppressing the influence of the luminescence and preventing the narrowing of the color region of the dark part.

[0083] In S201, the CPU 111 receives print data transmitted from the PC 101. In S202, the CPU 111 determines whether or not fluorescent ink is to be used for image formation. If it is determined that fluorescent ink is to be used, the process proceeds to S203, and if it is determined that fluorescent ink is not to be used, the process proceeds to S207.

[0084] In S203, CPU 111 determines the position on the input RGB color space for each pixel from the received recording data. That is, CPU 111 determines whether or not the pixel of the recording data is located between the maximum saturation point and the black point on the RGB color space surface. If it is determined that the pixel is located between the maximum saturation point and the black point on the RGB color space surface, the process proceeds to S205. On the other hand, if it is determined that the pixel is not located between the maximum saturation point and the black point on the RGB color space surface, the process proceeds to S204.

[0085] In S205, the CPU 111 sets masks for controlling the printing order for each ink color. In S205, the CPU 111 sets pre-printing and post-printing masks for fluorescent ink, which print over the entire area including both the upstream and downstream sides. The CPU 111 also sets post-printing masks for luminescence suppressing ink, which prints on the downstream side. The CPU 111 also sets pre-printing and post-printing masks for other inks, which print over the entire area including both the upstream and downstream sides. After S205, the process proceeds to S208.

[0086] In S204, CPU 111 determines the position on the input RGB color space for each pixel from the received recording data. That is, CPU 111 determines whether or not the pixel of the recording data is located between the white point and the maximum saturation point on the RGB color space surface. If it is determined that the pixel is located between the white point and the maximum saturation point on the RGB color space surface, the process proceeds to S206. On the other hand, if it is determined that the pixel is not located between the white point and the maximum saturation point on the RGB color space surface, the process proceeds to S207.

[0087] In S206, the CPU 111 sets masks for controlling the printing order for each ink color. In S206, the CPU 111 sets pre-printing and post-printing masks for fluorescent ink that print on the entire upstream and downstream sides. The CPU 111 also sets pre-printing masks for subtractive color ink that print on the upstream side. The CPU 111 also sets pre-printing and post-printing masks for other inks that print on the entire upstream and downstream sides. After S206, the process proceeds to S208.

[0088] In S207, the CPU 111 sets pre-print and post-print masks for printing on the entire upstream and downstream sides for all colors of ink. S203 to S207 are repeated for each pixel.

[0089] In S208, CPU 111 generates color separation data from the print data received in S201. In S1012, CPU 111 performs output gamma (OutPutGamma) correction according to the dot coverage on the print medium. In S210, CPU 111 performs quantization processing. As a result of the quantization processing, binary data corresponding to the ON / OFF of dots at the output resolution is generated. In S211, CPU 111 compares the quantized data with the mask for each color set in S205, S206, or S207, and determines the nozzles to be used for printing in each scan. In S212, CPU 111 scans the carriage and controls print head 115 to print dots from the determined nozzles.

[0090] <Control of ink printing order> In this embodiment, the printing order of fluorescent pink ink is controlled differently for the light color region and the dark color region. In this embodiment, the ink printing order is controlled based on the nozzle division printing of the print head 115 in Fig. 18 and the color separation in Fig. 22(b) and Fig. 22(c).

[0091] FIG. 17 is a diagram for explaining the nozzle division of the print head 115 in this embodiment. Here, as an example, the fluorescent pink ink, the K ink as the luminescence suppressing ink, and the Y ink as another subtractive color ink will be explained. As shown in FIG. 17, the nozzle division is performed for each ink as follows. For the fluorescent pink ink nozzle 115FP, a full nozzle is used as shown by the diagonal lines. For the K ink nozzle 115K, a nozzle portion having a width of 1 / 2 of the full nozzle downstream in the transport direction shown by the black dots is used. For the Y ink nozzle 115Y, a nozzle portion having a width of 1 / 2 of the full nozzle upstream in the transport direction shown by the hatching with dots is used.

[0092] Fig. 22(b) is a diagram showing the printing duty (color separation) for each ink for the WMK line of the color solid in Fig. 8. As shown in Fig. 22(b), the amount of fluorescent pink ink increases as it approaches the white point W toward the primary M, and decreases from the primary M to the black point K. From the primary M, the amount of M ink increases as a color component of the dark color area replacing the fluorescent pink ink, and after reaching a peak, decreases toward the black point K. The amount of K ink increases sequentially from the primary M to the black point K. In this manner, the printing duty of the WMK line is determined.

[0093] Fig. 22(c) is a diagram showing the print duty for each ink for the W-Or-K line of the color solid in Fig. 8. As shown in Fig. 22(c), from the white point W, the fluorescent FP ink and Y ink increase as it approaches the primary Or, and then decrease from the primary M to the black point K. From the primary Or, M ink increases as a color component in the dark area that replaces the fluorescent pink ink, and after reaching a peak, decreases towards the black point K. K ink increases sequentially from the primary M to the black point K. In this way, the print duty for the W-Or-K line is determined.

[0094] In this embodiment, in order to reduce the luminescence influence in the dark color regions and prevent narrowing of the range, in addition to controlling the printing order of the fluorescent pink ink, the amount of fluorescent ink applied in the dark color regions is also suppressed. In other words, by suppressing the amount of fluorescent pink ink applied in the dark color regions and using M ink, which is a subtractive color mixing ink, it is possible to limit the range of the luminescence influence in the dark color regions.

[0095] 22(b) and 22(c), the luminescence suppressing ink K is not used in the bright color region from the white point W to the primary. On the other hand, the luminescence suppressing ink K is used in the dark color region from the primary to the black point K.

[0096] In this embodiment, the printing order of the fluorescent pink ink and other inks is made different between the white point to primary and the primary to black point, due to the nozzle division in Fig. 17 and the color separation in Fig. 22(b) and Fig. 22(c). That is, from the white point to the primary, the fluorescent pink ink is printed so as to be mixed in the same ink layer with the Y ink, which is the other subtractive color ink, or to be the upper layer of the recording medium. On the other hand, from the primary to the black point, the fluorescent pink ink is printed so as to be mixed in the same ink layer with the K ink, which is a luminescence suppressing ink, or to be the lower layer of the recording medium.

[0097] <White point W~Control of primary ink recording order> 18 is a diagram for explaining the recording process of divided recording control on a recording medium by the recording head 115, the Y ink nozzles 115Y, and the fluorescent pink ink nozzles 115FP. For the sake of explanation, we will focus on two inks, the fluorescent pink ink that emits light and the Y ink, which is a subtractive color ink, and explain the case where ink is ejected from all of the target nozzles.

[0098] 18 is a diagram for explaining divided printing control in the case where Y ink is deposited first to form a lower layer on the printing medium, and fluorescent pink ink is deposited later to form an upper layer on the printing medium. The nozzles of the print head 115 are divided into upper and lower nozzles along the sub-scanning direction. The fluorescent pink ink nozzles 115FP are full nozzles, as indicated by diagonal lines. Furthermore, the Y ink nozzles 115Y are nozzles that are half the width of the full nozzles upstream in the transport direction, as indicated by hatching with dots.

[0099] The printing operation will be described in detail. In the forward main scan (1), printing is performed with fluorescent pink ink at the downstream side of the print head 115 with a width of 1 / 2 of a full nozzle. At that time, printing is performed with Y ink and fluorescent pink ink at the upstream side with a width of 1 / 2 of a full nozzle. Then, sub-scan (1) is performed, which is a transport of 1 / 2 the width of a full nozzle. The position of the print head after the operation of sub-scan (1) is position 1801. In the upstream part of the return main scan (2), the fluorescent pink ink and the Y ink are mixed in the same ink layer and are printed first on the blank part of the print medium. In the downstream part of the return main scan (2), the fluorescent pink ink is printed on top of the print medium on which the fluorescent pink ink and the Y ink have first arrived in the main scan (1). This series of operations is repeated to print on the entire print medium. In FIG. 18, an area 1802 indicates not the start or end of printing, but a steady state of the above repetition. After the recording medium is transported in the sub-scan (2), the fluorescent pink ink is recorded on top of the fluorescent pink ink and Y ink that have already arrived in the downstream portion of the main scan (3) in the forward direction. The same process is repeated thereafter.

[0100] FIG. 19(a) is a diagram for explaining the printing state on a printing medium obtained by the divided printing operation of FIG. 18. The printing state in the first pass is as shown in printing state 1901. The diagonal line area indicates the area printed with fluorescent pink ink, and the hatched area in a vertical and horizontal grid indicates the area printed with both fluorescent pink ink and Y ink mixed in the same ink layer. As shown in printing state 1901, by main scanning (1) in the forward direction, mixed printing is performed in the same ink layer with fluorescent pink ink and Y ink on white paper upstream of the first pass, as shown in the hatched area in a vertical and horizontal grid. Also, downstream of the first pass, printing is performed with fluorescent pink ink on white paper, as shown in the hatched area.

[0101] The state where the second pass printing is performed over the first pass printing is the printing state 1902. As shown in the printing state 1902, by main scanning (2) in the return direction, downstream of the second pass, printing with fluorescent pink ink (diagonal line area) is performed over the area already printed with fluorescent pink ink and Y ink in the first pass (vertical and horizontal checkered hatched area). Also, upstream of the second pass, mixed printing (vertical and horizontal checkered hatched area) is performed on white paper with fluorescent pink ink and Y ink in the same ink layer.

[0102] The printing state of the third pass is shown in printing state 1903. As shown in printing state 1903, by main scanning (3) in the forward direction, downstream of the third pass, printing with fluorescent pink ink (shaded area) is performed over an area (hatched area with a vertical and horizontal grid) where mixed printing with fluorescent pink ink and Y ink has already been performed in the same ink layer in the preceding second pass.

[0103] The printing operation in which the fluorescent pink ink is printed (shaded area) on top of an area (hatched area with a vertical and horizontal grid) where the fluorescent pink ink and Y ink have already been mixed and printed in the same ink layer is repeated in a second pass, a third pass, and so on. The area in which this repeated steady-state printing is performed is area 1802 in Figure 18. From the above, in the steady-state area 1802, the fluorescent pink ink and Y ink arrive first on the printing medium and form the lower layer, and the fluorescent pink ink follows and forms the upper layer of the printing medium.

[0104] For the sake of explanation, the control of the ink printing order and the ink layers formed have been described assuming that all target nozzles are ejecting. However, in reality, the printing duties of the fluorescent pink ink and the Y ink differ depending on the color to be printed. For the W-Or-K color solid in FIG. 8, the printing duties of each ink in this embodiment are determined as shown in FIG. 22(c).

[0105] FIG. 19(b) is a diagram showing all combinations of the printing states of ink layers on a printing medium when the divided printing control of FIG. 18 is performed with the printing duty shown in FIG. 22(c). As shown in FIG. 19(b), all possible combinations are a state in which two layers are overlapped with Y ink as the lower layer and fluorescent pink ink as the upper layer, a state in which there are two layers or only one layer of fluorescent pink ink, and a state in which there is only one layer of Y ink. Thus, in this embodiment, the printing order is controlled so that in the color region of the light portion, the fluorescent pink ink is mixed in the same ink layer as the subtractive color ink or is the upper layer of the printing medium. As a result, it is possible to realize an expansion of the color gamut by making use of luminescence.

[0106] <Control of ink recording order from primary to black point K> 20 is a diagram for explaining divided printing control in which fluorescent pink ink is deposited first to form a lower layer on the printing medium, and K ink is deposited later to form an upper layer on the printing medium. The nozzles of the print head 115 are divided into upper and lower nozzles along the sub-scanning direction. The fluorescent pink ink nozzles 115FP are full nozzles, as indicated by diagonal lines. Furthermore, the K ink nozzles 115K are nozzles that are half the width of the full nozzles downstream in the transport direction, as indicated by black lines.

[0107] The printing operation will be described in detail. In the forward main scan (1), on the upstream side of the print head 115, printing is performed with fluorescent pink ink at 1 / 2 the width of a full nozzle. At that time, on the downstream side, printing is performed with K ink and fluorescent pink ink at 1 / 2 the width of a full nozzle. Then, sub-scan (1) is performed, which is a transport of 1 / 2 the width of a full nozzle. The position of the print head on the print medium after the sub-scan (1) operation is position 2001. In the upstream part of the return main scan (2), the fluorescent pink ink arrives first on the blank part of the print medium and is printed. In the downstream part of the return main scan (2), the fluorescent pink ink and K ink are printed in a mixed state on the print medium area where the fluorescent pink ink arrived first in the main scan (1). This series of operations is repeated to print on the entire print medium. In FIG. 20, area 2002 does not indicate the start or end of printing, but indicates an area where the above repetition is in a steady state. After the recording medium is transported in the sub-scan (2), in the downstream portion of the main scan (3) in the forward direction, the fluorescent pink ink and the K ink are mixed and recorded on top of the recording medium on which the fluorescent pink ink has landed first, and the same process is repeated thereafter.

[0108] FIG. 21(a) is a diagram for explaining the printing state on a printing medium obtained by the divided printing operation of FIG. 20. The printing state in the first pass is shown as printing state 2101. The diagonal line area indicates an area printed with fluorescent pink ink, and the diagonal grid hatched area indicates an area printed with both fluorescent pink ink and K ink mixed in the same ink layer. As shown in printing state 2101, by main scanning (1) in the forward direction, mixed printing in the same ink layer with fluorescent pink ink and K ink (diagonal grid hatched area) is performed on white paper downstream of the first pass. Furthermore, upstream of the first pass, printing with fluorescent pink ink (diagonal grid area) is performed on white paper.

[0109] The state in which the second pass printing is performed following the first pass printing is the printing state 2102. As shown in the printing state 2102, by main scanning (2) in the return direction, mixed printing (diagonal checkered hatched area) is performed in the same ink layer using both fluorescent pink ink and K ink, overlaying the area (hatched area) that has already been printed with fluorescent pink ink in the first pass, downstream of the second pass. Also, upstream of the second pass, printing with fluorescent pink ink (hatched area) is performed on white paper.

[0110] The printing state of the third pass is shown in printing state 2102. As shown in printing state 2102, by main scanning in the forward direction (3), mixed printing (diagonal grid hatched area) of fluorescent FP ink and K ink is performed in the same ink layer downstream of the third pass, overlaying the area (hatched area) that has already been printed with fluorescent pink ink in the second pass.

[0111] The printing operation in which mixed printing (diagonal checkered hatched area) of fluorescent pink ink and K ink is performed in the same ink layer on top of an area (hatched area) already printed with fluorescent pink ink is repeated in a second pass, a third pass, and so on. The area in which this repeated steady-state printing is performed is area 2002 in Figure 20. From the above, in the steady-state area 2002, the fluorescent pink ink arrives first on the printing medium and becomes the lower layer, and then the fluorescent pink ink and K ink are printed in the same ink layer and become the upper layer of the printing medium.

[0112] For the sake of explanation, the control of the ink printing order and the ink layers formed have been described assuming that all target nozzles are ejecting ink. However, in reality, the printing duties of the fluorescent pink ink and the K ink differ depending on the color to be printed. For the W-M-K lines and the W-Or-K lines of the color solid in FIG. 8, the printing duties of each ink in this embodiment are determined as shown in FIG. 22(b) and FIG. 22(c).

[0113] Fig. 21(b) is a diagram showing all combinations of the printing states of ink layers on a printing medium when the divided printing control of Fig. 20 is performed with the printing duties shown in Fig. 22(b) and Fig. 22(c). As shown in Fig. 21(b), all possible combinations include a state in which two layers are overlapped, with fluorescent pink ink as the lower layer and K ink as the upper layer, a state in which there are two layers or only one layer of fluorescent pink ink, and a state in which there is only one layer of K ink. In this way, in this embodiment, the printing order is controlled so that the fluorescent pink ink is mixed in the same ink layer as the luminescence suppressing ink or is the lower layer on the printing medium.

[0114] As described above, in this embodiment, the recording order of the fluorescent pink ink and the other inks is controlled to be different between the white point-primary and primary-black point. In the white point-primary, the recording order is controlled so that the fluorescent pink ink is mixed in the same ink layer as the other subtractive color inks or is an upper layer on the recording medium. On the other hand, in the primary-black point, the recording order is controlled so that the fluorescent pink ink is mixed in the same ink layer as the luminescence suppressing ink or is a lower layer on the recording medium.

[0115] Fig. 22(a) is a diagram for explaining the color reproduction range by the divided recording control of this embodiment. The color range of the dark part by conventional recording control is indicated by the dashed line P'-K, and the color range of the dark part by this embodiment is indicated by the thick line P'-K. As shown in Fig. 22(a), the dashed line P'-K is hollowed out and convex upward, whereas the thick line P'-K by the recording control of this embodiment is closer to a straight line. In other words, the divided control of this embodiment can suppress the above-mentioned "hollowing out" and prevent the color range of the dark part from narrowing.

[0116] As described above, in this embodiment, in the case of a recording medium on which an image is formed using an ink deposition model, the recording order of each ink is controlled. That is, from the white point to the primary, the recording order of the fluorescent pink ink is controlled so that it is mixed in the same ink layer as the other subtractive color inks or is recorded in the upper layer of the recording medium. On the other hand, from the primary to the black point, the recording order of the fluorescent pink ink is controlled so that it is mixed in the same ink layer as the luminescence suppression ink or is recorded in the lower layer of the recording medium. This makes it possible to realize an expansion of the color gamut in the color region of the light area and prevent the color region of the dark area from narrowing.

[0117] [Third embodiment] The third embodiment will be described below with respect to the differences from the first and second embodiments. In this embodiment, printing control having the same effect as that in the second embodiment described with respect to the ink deposition model printing medium is performed with respect to the ink penetration model printing medium.

[0118] In this embodiment, coated paper is used as the recording medium, and dye ink is used as the coloring material. The coated paper in this embodiment is made of two layers: a pulp base layer and an ink receiving layer made of silica particles. The ink receiving layer is made of coarse silica particles applied to the pulp base, and has gaps between the silica particles and even smaller pores within the silica particles themselves, allowing the dye ink to penetrate and be retained in the large and small capillaries that these form. In this embodiment, an image formation process is performed using an ink penetration model.

[0119] <Image formation process on recording media: Ink penetration model> The image formation process on a recording medium will be described with reference to FIG. 7. FIG. 7 is a diagram for explaining the image formation process in an ink penetration model in which ink that has landed on a recording medium penetrates into the recording medium. This corresponds to the image formation process, for example, when recording pigment ink on plain paper with larger voids than the colorant particles, or when recording dye ink on plain paper or glossy paper with smaller voids than the colorant particles. The ink penetration model is a model of the image formation process in which the colorant particle size that contributes to color development in the ink is smaller than the gaps on the recording medium surface, so that the colorant penetrates into the recording medium below the recording medium surface and forms an ink layer below the recording medium surface.

[0120] The image formation is carried out as shown in FIG. 7(a) to FIG. 7(d).

[0121] As shown in FIG. 7(a), the dye ink S1 is applied onto the recording medium P. Then, as shown in FIG. 7(b), the dye ink S1 lands on the recording medium P and permeates into the recording medium. Furthermore, the subsequent dye ink S2 is applied. Then, as shown in FIG. 7(c), the dye ink S2 lands on the dye ink S1 that has already permeated and occupies the voids in the surface layer of the recording medium. Then, as shown in FIG. 7(d), since the dye ink S1 that arrived first occupies the voids in the surface layer of the recording medium, the dye ink S2 permeates around it and permeates into a lower layer of the recording medium. As a result, the upper layer of the recording medium is the dye ink S1, and the lower layer of the recording medium is the dye ink S2. Thus, in the ink penetration model, the relationship between the landing order and the image formation layer order is reversed from that in the ink deposition model, and image formation is performed in which the subsequent dots remain in the lower layer of the recording medium.

[0122] In this embodiment, as in the second embodiment, the recording order is controlled to take advantage of the luminous properties of the fluorescent pink ink and expand the color gamut in the bright color region while preventing narrowing in the dark color region. In the bright color region, the fluorescent pink ink is recorded so that it is mixed in the same ink layer as the other subtractive color inks or is the upper layer of the recording medium, thereby realizing an expansion of the color gamut by utilizing the luminous properties. In the dark color region, the fluorescent pink ink is recorded so that it is mixed in the same ink layer as the luminous inhibition inks or is the lower layer of the recording medium, thereby suppressing the luminous effects in the dark region and preventing narrowing of the color region in the dark region.

[0123] The following describes the differences from the second embodiment with regard to the ink recording order control that arises due to the difference in the image forming process from the second embodiment.

[0124] Fig. 30 is a flowchart showing the printing control process in this embodiment. The process in Fig. 30 is realized, for example, by the CPU 111 of the printing device 108 reading out a program stored in the ROM 113 into the RAM 112 and executing it. In this embodiment, an ink penetration model different from the ink deposition model in the second embodiment is assumed. Therefore, the printing order and the layer order of the ink layers in which an image is formed as a result of printing are reversed from those in the second embodiment. In this embodiment, the same layer order of the ink layers as in the second embodiment is realized by controlling the printing order to be reversed from that in the second embodiment.

[0125] 30 are the same as those in S201 to S204, S207, and S208 to S212 in FIG. 29, and therefore the description thereof will be omitted.

[0126] If it is determined in S303 that the pixel is located between the maximum saturation point and the black point on the input RGB color space surface, then in S305 the CPU 111 sets masks for controlling the printing order for each ink color. In S305, the CPU 111 sets pre-deposit and post-deposit masks for fluorescent ink that perform printing on the entire upstream and downstream sides. The CPU 111 also sets pre-deposit masks for luminescence suppressing ink that perform printing on the upstream side. The CPU 111 also sets pre-deposit and post-deposit masks for other inks that perform printing on the entire upstream and downstream sides.

[0127] If it is determined in S303 that the pixel is located between the white point and the maximum saturation point on the input RGB color space surface, then in S306 the CPU 111 sets pre-deposit and post-deposit masks for fluorescent ink that perform printing on the entire upstream and downstream sides. The CPU 111 also sets post-deposit masks for subtractive ink that perform printing on the downstream side. The CPU 111 also sets pre-deposit and post-deposit masks for other inks that perform printing on the entire upstream and downstream sides.

[0128] <Control of ink printing order> In this embodiment, the printing order of fluorescent pink ink is controlled differently for the light color region and the dark color region. In this embodiment, the ink printing order is controlled based on the nozzle division printing of the print head 115 in Fig. 24 and the color separation in Fig. 22(b) and Fig. 22(c).

[0129] FIG. 23 is a diagram for explaining the nozzle division of the print head 115 in this embodiment. Here, as an example, the fluorescent pink ink, the K ink as the luminescence suppressing ink, and the Y ink as another subtractive color ink will be explained. As shown in FIG. 23, the nozzle division is performed for each ink as follows. For the fluorescent pink ink nozzle 115FP, a full nozzle is used as shown by the diagonal lines. For the K ink nozzle 115K, a nozzle portion having a width of 1 / 2 of the full nozzle downstream in the transport direction shown by the black dots is used. For the Y ink nozzle 115Y, a nozzle portion having a width of 1 / 2 of the upstream in the transport direction shown by the hatching with dots is used.

[0130] 22(b) and 22(c), the K ink, which is an luminescence suppressing ink, is not used in the light color area from the white point W to the primary. On the other hand, the K ink, which is an luminescence suppressing ink, is used in the dark color area from the primary to the black point K.

[0131] In this embodiment, the printing order of the fluorescent pink ink and other inks is made different between the white point to primary and the primary to black point, due to the nozzle division in Fig. 23 and the color separation in Fig. 22(b) and Fig. 22(c). That is, from the white point to the primary, the fluorescent pink ink is printed so as to be mixed in the same ink layer as the Y ink, which is the other subtractive color ink, or to be the upper layer of the recording medium. On the other hand, from the primary to the black point, the fluorescent pink ink is printed so as to be mixed in the same ink layer as the K ink, which is a luminescence suppressing ink, or to be the lower layer of the recording medium.

[0132] <White point W~Control of primary ink recording order> 24 is a diagram for explaining the recording process of divided recording control on a recording medium by the recording head 115, the Y ink nozzles 115Y, and the fluorescent FP ink nozzles 115FP. For the sake of explanation, we will focus on two inks, fluorescent pink ink that emits light and Y ink, which is a subtractive color ink, and explain the case where ink is ejected from all of the target nozzles.

[0133] Fig. 24 shows divided recording control in the case where fluorescent FP ink is deposited first to form an image of an ink layer on the upper layer of the recording medium, and Y ink is deposited later to form an image on the lower layer of the recording medium. The nozzles of the recording head 115 are divided into upper and lower nozzles along the sub-scanning direction. The fluorescent pink ink nozzles 115FP are full nozzles, as indicated by the diagonal lines. Furthermore, the Y ink nozzles 115Y are nozzles that are half the width of the full nozzles downstream in the transport direction, as indicated by the hatching with dots.

[0134] The printing operation will be described in detail. In the forward main scan (1), printing is performed with fluorescent pink ink on the upstream side of the print head 115 with a width of 1 / 2 of a full nozzle. At that time, printing is performed with Y ink and fluorescent pink ink on the downstream side with a width of 1 / 2 of a full nozzle. Then, sub-scan (1) is performed, which is a transport of 1 / 2 the width of a full nozzle. The position of the print head after the operation of sub-scan (1) is position 2401. In the upstream part of the return main scan (2), the fluorescent pink ink arrives first on the blank part of the print medium and is printed. In the downstream part of the return main scan (2), the fluorescent pink ink and the Y ink are subsequently superimposed on the print medium on which the fluorescent pink ink arrived first in the main scan (1), and are printed mixed in the same ink layer. This series of operations is repeated to print on the entire print medium. In FIG. 24, an area 2402 indicates not the start or end of printing, but the area in the steady state of the above repetition. After the recording medium is transported in the sub-scanning (2), the fluorescent pink ink and the Y ink are subsequently superimposed on the recording medium on which the fluorescent pink ink has landed first in the downstream portion of the main scanning (3) in the forward direction, and are recorded mixed in the same ink layer.

[0135] FIG. 25(a) is a diagram for explaining the printing state on a printing medium obtained by the divided printing operation of FIG. 24. The printing state in the first pass is as shown in printing state 2501. The diagonal line indicates the area printed with fluorescent pink ink, and the hatched area in a vertical and horizontal grid indicates the area printed with both fluorescent pink ink and Y ink mixed in the same ink layer. As shown in printing state 2501, by main scanning (1) in the forward direction, printing is performed with fluorescent pink ink on white paper upstream of the first pass, as shown in the diagonal line. Furthermore, downstream of the first pass, mixed printing is performed with fluorescent pink ink and Y ink on white paper in the same ink layer, as shown in the hatched area in a vertical and horizontal grid.

[0136] A printing state 2502 is a state in which a second pass is printed over the first pass. As shown in printing state 2502, main scanning (2) in the return direction prints a mixed printing (vertical and horizontal checkered hatched area) of fluorescent FP ink and Y ink in the same ink layer downstream of the second pass after the area (shaded area) that was previously printed with fluorescent pink ink in the first pass. However, in the case of an ink penetration model, the first-arriving dots occupy the upper layer of the printing medium, and the subsequent dots penetrate into the lower layer of the printing medium, so that the area (shaded area) already printed with the first-arriving fluorescent pink ink occupies the upper layer of the printing medium. Also, upstream of the second pass, printing (shaded area) is performed with fluorescent pink ink on white paper.

[0137] The printing state of the third pass is as shown in printing state 2503. As shown in printing state 2503, by main scanning in the forward direction (3), downstream of the third pass, mixed printing (vertical and horizontal checkered hatched area) of fluorescent FP ink and Y is performed in the same ink layer following the area (shaded area) that has already been printed with fluorescent pink ink in the second pass. Here too, the printing state on the printing medium is dominated by the area (shaded area) that has already been printed with the fluorescent pink ink that arrived first.

[0138] Following the area already printed with fluorescent pink ink (shaded area), the printing operation in which fluorescent FP ink and Y ink are mixed and printed in the same ink layer (vertical and horizontal checkered hatched area) is repeated in the second pass, third pass, and so on. The area in which this repeated steady-state printing is performed is area 2402 in Figure 24. As described above, in area 2402, printing is performed such that the fluorescent pink ink arrives first and becomes the upper layer of the printing medium, and the fluorescent pink ink and Y ink follow and sink into the lower layer of the printing medium.

[0139] For the sake of explanation, the control of the ink printing order and the ink layers formed have been described assuming that all target nozzles are ejecting ink. However, in reality, the printing duty differs between the fluorescent pink ink and the Y ink depending on the color to be printed. For the W-Or-K line of the color solid in FIG. 8, the printing duty for each ink in this embodiment is determined as shown in FIG. 22(c).

[0140] FIG. 25(b) is a diagram showing all combinations of the printing states of ink layers on a printing medium when the divided printing control of FIG. 24 is performed with the printing duty shown in FIG. 22(c). As shown in FIG. 25(b), all possible combinations are a two-layer overlap state with Y ink as the lower layer and fluorescent pink ink as the upper layer, a state with two layers or only one layer of fluorescent pink ink, and a state with only one layer of Y ink. Thus, in this embodiment, the printing order is controlled so that in the color region of the light part, the fluorescent pink ink is mixed in the same ink layer as the subtractive color ink or is the upper layer of the printing medium. As a result, it is possible to realize an expansion of the color gamut by making use of luminescence.

[0141] <Control of ink recording order from primary to black point K> 26 is a diagram for explaining divided printing control when K ink is deposited first to form an image of an ink layer on the upper layer of the printing medium, and fluorescent FP ink is deposited later to form an image on the lower layer of the printing medium. The nozzles of the printing head 115 are divided into upper and lower nozzles along the sub-scanning direction. As shown by the diagonal lines, the fluorescent FP ink nozzles (115FP) which are fluorescent ink are full nozzles. Also, as shown by the black lines, the K ink nozzles 115K which are luminescence suppressing ink are nozzles which are half the width of the full nozzles on the upstream side in the transport direction.

[0142] The printing operation will be described in detail. In the forward main scan (1), the K ink and the fluorescent pink ink are printed on the upstream side of the print head 115 with a width of 1 / 2 of a full nozzle. In the downstream side, the fluorescent pink ink is printed on with a width of 1 / 2 of a full nozzle. Then, the sub-scan (1) is performed, which is a conveyance of 1 / 2 the width of a full nozzle. The position of the print head on the print medium after the sub-scan (1) operation is position 2601. In the backward main scan (2), the fluorescent pink ink and the K ink are printed on the upstream side of the print medium, while being mixed in the same ink layer, and are printed on the blank portion of the print medium first. In the backward main scan (2), the fluorescent pink ink is printed on the downstream side of the print medium, where the fluorescent pink ink and the K ink are printed on the upstream side of the print medium, while being mixed in the same ink layer, with the fluorescent pink ink being printed on the downstream side of the print medium, while being mixed in the same ink layer with the main scan (1). This series of operations is repeated to print on the entire print medium. In FIG. 26, an area 2602 indicates not the start or end of printing, but a steady state of the above repetition. After the recording medium is transported in the sub-scan (2), the fluorescent pink ink is printed on top of the recording medium where the fluorescent pink ink and the K ink have already arrived in the downstream portion of the main scan (3) in the forward direction, and the same process is repeated thereafter.

[0143] Fig. 27(a) is a diagram for explaining the printing state on a printing medium obtained by the divided printing operation of Fig. 26. The printing state in the first pass is shown as printing state 2701. The diagonal line area indicates an area printed with fluorescent pink ink, and the diagonal lattice hatched area indicates an area printed with both fluorescent pink ink and K ink mixed in the same ink layer. As shown in printing state 2701, by main scanning (1) in the forward direction, mixed printing in the same ink layer with fluorescent pink ink and K ink (diagonal lattice hatched area) is performed on white paper upstream of the first pass. Also, downstream of the first pass, printing with fluorescent pink ink (diagonal lined area) is performed on white paper.

[0144] A state in which the second pass printing is performed following the first pass printing is shown as a printing state 2702. As shown in the printing state 2702, by main scanning (2) in the return direction, downstream of the second pass, printing with fluorescent pink ink (hatched area) is performed following the area where the fluorescent pink ink and K ink have been mixedly printed in the same ink layer in the first pass (hatched area with diagonal grid). However, in the ink penetration model, the ink layer that arrived first occupies the upper layer of the recording medium, and the subsequent ink layer bypasses the first ink and permeates into the lower layer of the recording medium, so that on the recording medium, the mixed printing area of ​​the fluorescent ink and K ink that arrived first in the same ink layer occupies the upper layer of the recording medium. Also, upstream of the second pass, mixed printing with the fluorescent pink ink and K ink in the same ink layer (hatched area with diagonal grid) is performed on white paper.

[0145] The printing state of the third pass is shown in printing state 2703. As shown in printing state 2703, by main scanning (3) in the forward direction, downstream of the third pass, printing with fluorescent pink ink (diagonal line area) is performed following an area (hatched area with diagonal grid) that has already been printed in the same ink layer with fluorescent pink ink and K ink in the previous pass.

[0146] The printing operation in which fluorescent pink ink is printed (diagonal line area) following an area where fluorescent pink ink and K ink have already been mixed and printed in the same ink layer (hatched area) is repeated in the second and third passes. The area where this repeated steady-state printing is performed is area 2602 in FIG. 26. From the above, in area 2602, the first-arrived ink layer occupies the surface layer of the printing medium compared to the subsequent ink layers, so the area where fluorescent pink ink and K ink are mixed and printed in the same ink layer becomes the upper layer of the printing medium. Then, the fluorescent pink ink subsequently penetrates and becomes the lower layer of the printing medium.

[0147] For the sake of explanation, the control of the ink printing order and the ink layers formed have been described assuming that all target nozzles are ejecting ink. However, in reality, the printing duties of the fluorescent pink ink and the K ink differ depending on the color to be printed. The printing duties of each ink in this embodiment for the WMK lines and W-Or-K lines of the color solid in FIG. 8 are as shown in FIG. 22(b) and FIG. 22(c).

[0148] Fig. 27(b) is a diagram showing all combinations of the printing states of ink layers on a printing medium when the divided printing control of Fig. 26 is performed with the printing duties shown in Fig. 22(b) and Fig. 22(c). As shown in Fig. 27(b), all possible combinations include a state in which two layers are overlapped with fluorescent pink ink as the lower layer and K ink as the upper layer, a state in which there are two layers or only one layer of fluorescent pink ink, and a state in which there is only one layer of K ink. In this way, in this embodiment, the printing order is controlled so that the fluorescent pink ink is mixed in the same ink layer as the luminescence suppressing ink or is the lower layer on the printing medium.

[0149] As described above, even when using an ink penetration model recording medium, the recording order of the fluorescent pink ink and other inks can be controlled to be different between white point-primary and primary-black point, as in the second embodiment. That is, from white point to primary, the recording order of the fluorescent pink ink is controlled so that it is mixed with other subtractive color inks or is in the upper layer of the recording medium. On the other hand, from primary to black point, the recording order of the fluorescent pink ink is controlled so that it is mixed with the same ink layer as the luminescence suppressing ink or is in the lower layer of the recording medium. Also, the same effect as that described in FIG. 22(a) can be achieved.

[0150] In the above, the combination of coated paper and dye ink has been exemplified as a combination of a recording medium and ink to which the ink penetration model is applied. However, the combinations in which the image formation process according to the ink penetration model is realized are not limited to this, and include combinations of plain paper, Japanese paper, and art paper with pigment ink. In the case of plain paper or Japanese paper, ink penetration occurs with the gaps between pulp fibers as large capillaries and the pulp itself as small capillaries. In the case of art paper, ink penetration occurs with the gaps between silica particles as large capillaries and the silica particles themselves as small capillaries, as in the case of coated paper. The size of these gaps is sufficiently larger than the pigment colorant particle diameter of 100 [nm], so the image formation process by penetration is realized even with pigment ink.

[0151] As described above, even when using an ink penetration model recording medium, the recording order of each ink is controlled. That is, from the white point to the primary, the recording order is controlled so that the fluorescent pink ink is mixed in the same ink layer as the other subtractive color inks or is recorded in the upper layer of the recording medium. On the other hand, from the primary to the black point, the recording order is controlled so that the fluorescent pink ink is mixed in the same ink layer as the luminescence suppressing ink or is recorded in the lower layer of the recording medium. This makes it possible to expand the color gamut in the light area and prevent the color gamut in the dark area from narrowing.

[0152] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0153] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0154] 101 PC: 108 Recording device: 102, 111 CPU: 109 Image processing accelerator

Claims

1. A recording device that records an image by reciprocating a recording means provided with a nozzle row in a recording medium transport direction in a scanning direction intersecting the recording medium transport direction and depositing ink droplets from the nozzles of the recording means onto the recording medium, the recording means has a nozzle row corresponding to a fluorescent ink that absorbs light of an excitation wavelength and emits light of an emission wavelength, and a nozzle row corresponding to an emission suppressing ink that suppresses emission of the fluorescent ink by absorbing at least one of the light of the excitation wavelength and the light of the emission wavelength, The recording device includes: a recording control means for controlling the movement of the recording means and the transportation of the recording medium so as to record an image by a plurality of scans of the recording means; a color conversion means for converting image data representing the image into ink data representing the application amounts of the fluorescent ink and the luminescence suppressing ink when the fluorescent ink is used in recording the image; a determination unit that determines an order of printing with the fluorescent ink and printing with the luminescence suppressing ink in the plurality of scans when the fluorescent ink is used in printing the image; Equipped with the light absorbed by the luminescence suppressing ink corresponds to a wavelength near a peak in a spectroscopic spectrum, In recording the image, the fluorescent ink is used in a color region between a black point and a maximum saturation point on a color space surface of the image, the color conversion means converts the image data into the ink data such that the amount of the fluorescent ink applied increases as the color approaches the maximum saturation point from the black point; the recording control means performs the control based on the order determined by the determination means, and when recording the image of the color region based on the ink data converted by the color conversion means, the determination means determines an order of recording with the fluorescent ink and the luminescence suppressing ink so that the fluorescent ink is recorded in a lower layer than the luminescence suppressing ink. A recording apparatus comprising:

2. the nozzle row corresponding to the fluorescent ink and the nozzle row corresponding to the luminescence suppressing ink are each divided into a plurality of groups in which the nozzles are adjacent to each other so as to correspond to each scan; the determining means determines an order of recording with the fluorescent ink and recording with the luminescence suppressing ink by setting whether or not to perform mask setting for each of the divided groups.

2. The recording apparatus according to claim 1,

3. The luminescence suppressing ink is a black ink, the recording means has a nozzle array corresponding to subtractive color mixture ink, the determining means determines an order of recording with the fluorescent ink and recording with the subtractive ink in the plurality of scans when the fluorescent ink is used in recording the image, the determining means determines an order of recording with the fluorescent ink and the subtractive color ink such that, in a color region between the maximum saturation point and the white point on the color space surface of the image, the fluorescent ink is recorded in the same layer as the subtractive color ink, or the fluorescent ink is recorded in an upper layer than the subtractive color ink.

3. The recording apparatus according to claim 1, wherein the recording apparatus is a recording medium.

4. The nozzle row corresponding to the subtractive color ink is divided into a plurality of groups in which the nozzles are adjacent to each other so as to correspond to each scan, the determining means determines an order of printing with the fluorescent ink and printing with the subtractive color mixing ink by setting whether or not to set a mask for each of the divided groups.

4. The recording apparatus according to claim 3.

5. 5. The recording device according to claim 3, wherein the recording medium includes a first recording medium on which, when a second ink droplet lands on the recording medium after a first ink droplet lands, the second ink droplet is deposited on the first ink droplet, and a second recording medium on which the first ink droplet penetrates under the second ink droplet.

6. 6. The recording apparatus according to claim 5, wherein a group for which a mask is set is different between when the first recording medium is used and when the second recording medium is used.

7. A recording device described in any one of claims 1 to 6, characterized in that the wavelength range of the excitation wavelength overlaps with the wavelength range of the emission wavelength and is on the short wavelength side.

8. A recording method for recording an image by reciprocating a recording means provided with a nozzle array in a recording medium transport direction in a scanning direction intersecting the recording medium transport direction and depositing ink droplets from the nozzles of the recording means onto the recording medium, the method comprising: the recording means has a nozzle row corresponding to a fluorescent ink that absorbs light of an excitation wavelength and emits light of an emission wavelength, and a nozzle row corresponding to an emission suppressing ink that suppresses emission of the fluorescent ink by absorbing at least one of the light of the excitation wavelength and the light of the emission wavelength, The recording method includes: a recording control step of controlling the movement of the recording means and the transportation of the recording medium so as to record an image by a plurality of scans of the recording means; a color conversion step of converting image data representing the image into ink data representing the application amounts of the fluorescent ink and the luminescence suppressing ink when the fluorescent ink is used in recording the image; a determination step of determining an order of recording with the fluorescent ink and recording with the luminescence suppressing ink in the plurality of scans when the fluorescent ink is used in recording the image; having the light absorbed by the luminescence suppressing ink corresponds to a wavelength near a peak in a spectroscopic spectrum, In recording the image, the fluorescent ink is used in a color region between a black point and a maximum saturation point on a color space surface of the image, In the color conversion step, the image data is converted into the ink data such that the amount of the fluorescent ink applied increases as the color approaches the maximum saturation point from the black point; In the recording control step, the control is performed based on the order determined in the determination step; In the determination step, when the image of the color region is recorded based on the ink data converted in the color conversion step, the order of recording with the fluorescent ink and the recording with the luminescence suppressing ink is determined so that the fluorescent ink is recorded in a lower layer than the luminescence suppressing ink. A recording method comprising:

Images