Printing device and printing method

Abstract

The present invention discloses a printing device and a printing method. The printing device includes: an ink application unit, a reaction liquid application unit, a control unit configured to control the amount of reaction liquid applied by the reaction liquid application unit; and a recognition unit configured to identify pixels included in a line portion based on image data indicating an image to be formed on a print medium. The control unit controls the amount of reaction liquid applied so that the amount of reaction liquid applied per unit area to an area where a line portion formed on the print medium by pixels recognized by the recognition unit is to be printed is less than the amount of reaction liquid applied per unit area to an area where an image including pixels not recognized by the recognition unit is to be formed.

Description

Technical Field

[0001] The present invention relates to a printing device and a printing method. Background Art

[0002] There is known a printing apparatus that prints an image on a printing medium by fixing the ink using a reaction liquid that reacts with the ink.

[0003] Japanese Patent Application Publication No. 2016-147418 discusses a technique in which the amount of reaction liquid applied in the boundary portion is increased in order to prevent loosening of lines in the boundary portion between an image and a space due to non-application of the reaction liquid to ink in the boundary portion.

[0004] However, in the method of Japanese Patent Application Laid-Open No. 2016-147418, image quality may deteriorate. Summary of the Invention

[0005] According to one aspect of the present invention, a printing device includes: an ink application unit configured to apply ink including a coloring material to a print medium; a reaction liquid application unit configured to apply a reaction liquid to the print medium for promoting the curing of the ink by reacting with the ink; a control unit configured to control the amount of reaction liquid applied by the reaction liquid application unit; and an identification unit configured to identify pixels included in a line portion based on image data indicating an image to be formed on the print medium. The printing device forms an image by applying ink from the ink application unit in accordance with the image data. The control unit controls the amount of reaction liquid applied so that the amount of reaction liquid applied per unit area to an area on the print medium where a line portion formed by pixels identified by the identification unit is to be printed is less than the amount of reaction liquid applied per unit area to an area where an image including pixels not identified by the identification unit is to be formed.

[0006] Further features of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a perspective view of a printing apparatus according to an exemplary embodiment.

[0008] Figure 2 is a schematic cross-sectional view illustrating a printing apparatus according to an exemplary embodiment.

[0009] Figure 3 is a schematic diagram showing a print head viewed from the ejection port side in the exemplary embodiment.

[0010] Figure 4 is a schematic diagram illustrating a print control system in the exemplary embodiment.

[0011] Figure 5 is a diagram illustrating data processing stages in an exemplary embodiment.

[0012] Figure 6A 、 Figure 6B and Figure 6C is a diagram illustrating a page description language (PDL) format and drawing commands in the exemplary embodiment.

[0013] Figure 7 is a diagram illustrating multi-pass printing in the exemplary embodiment.

[0014] Figure 8A and Figure 8B is a diagram illustrating color conversion processing in the exemplary embodiment.

[0015] Figure 9A-1 、 Figure 9A-2 、 Figure 9B-1 and Figure 9B-2 is a graph showing the application amount of ink in the exemplary embodiment.

[0016] Figure 10 is a graph illustrating line quality degradation caused by ink bleeding in an exemplary embodiment.

[0017] Figure 11 is a diagram illustrating data processing stages in an exemplary embodiment.

[0018] Figure 12A 、 Figure 12B-1 and Figure 12B-2 is a graph showing image density and coloring material point contact ratio in the exemplary embodiment.

[0019] Figure 13 is a diagram illustrating reaction liquid application control based on the density and edge amount of an image in an exemplary embodiment. DETAILED DESCRIPTION

[0020] Before the coloring material ink is fixed by reacting with the reaction liquid, when the coloring material ink and the reaction liquid come into contact with each other, bleeding may occur due to the coloring material ink flowing into the reaction liquid. Figure 10 As shown in FIG. 1 , when there is a difference between the positions of the K (black) coloring ink dots (filled circles) and the reaction ink dots (unfilled solid color circles), the coloring ink flows into the reaction ink, increasing the bleeding of the coloring ink. If this bleeding occurs in the printed line portion, deterioration in image quality is easily observed.

[0021] The present invention aims to prevent image quality degradation in line portions.

[0022] The following describes a printing device using an inkjet printing method as an example. The printing device may be, for example, a single-function printer having only a printing function, or a multifunction printer having multiple functions (e.g., a printing function, a fax function, and a scanner function). For example, the printing device may be a device for manufacturing any of color filters, electronic devices, optical devices, and microstructures using a predetermined printing method.

[0023] (1) Configuration of inkjet printing device

[0024] A first exemplary embodiment of the present invention will be described below. Figure 1 The external appearance of an inkjet printing apparatus (hereinafter also referred to as a printing apparatus or printer) 100 according to the present exemplary embodiment is shown. This printing apparatus is of a serial type and prints an image on a printing medium P by scanning a print head 9 in a scanning direction (X direction) intersecting (orthogonal to) the transport direction (Y direction) of the printing medium P.

[0025] Will refer to Figure 1 The configuration of the inkjet printing device 100 and the outline of the printing operation are described. Initially, the inkjet printing device 100 is printed by the conveying roller 14 (see FIG. 1 ) driven by the conveying motor (not shown) through the gear. Figure 2 ) and pinch roller 15 (see Figure 2 ), the printing medium P is taken out from the holding portion 13 (see Figure 2 ) is transported to the platen 4 supporting the print medium P. On the platen 4, the print medium P is transported in the Y direction. When the print medium P is transported to a predetermined transport position facing the carriage 2, the carriage 2 is driven by a carriage motor (not shown) to perform reciprocating scanning (reciprocating movement) along the guide shaft 8 extending in the X direction. The print head 9 (see Figure 2) is attached to the carriage 2, and the print head 9 has ejection ports through which ink is ejected. Ink tubes 19, 45 are used to supply ink from the ink tank to the print head 9. At a timing based on the position signal obtained by the encoder, as the carriage 2 reciprocates, ink is ejected from the ejection ports of the print head 9 to print an image on the print medium P. The encoder obtains the position signal by detecting the scale 7 by a sensor (not shown) provided on the carriage 2. The area in which the carriage 2 performs scanning and printing in one direction is a bandwidth area corresponding to the array range of the ejection ports. The scanning speed is variable and can be scanned at a speed of 10 to 70 inches per second. The printing resolution is also variable and the ejection operation can be performed at 300 to 2400 dots per inch (dpi). In this exemplary embodiment, scanning is performed at a scanning speed of 40 inches per second, and the ejection operation is performed at a printing resolution of 1200 dpi (at intervals of 1 / 1200 inch). When printing of one bandwidth is completed, the print medium P is conveyed a predetermined amount in the Y direction, and printing of the next bandwidth is performed. The printing medium P is wound around the winding shaft 6 while being conveyed in the Y direction.

[0026] A carriage belt can be used to transmit the driving force from the carriage motor to the carriage 2. Other types of drive systems can be used instead of the carriage belt. These examples include a system that includes a lead screw extending in the X direction and driven for rotation by the carriage motor, and an engaging portion provided in the carriage 2 and engaged with a lead screw groove.

[0027] Figure 2 is a schematic cross-sectional view showing the internal structure of the printing device 100. Figure 1 Although not shown, the printing device 100 of this exemplary embodiment includes a heating unit comprising a heater 10 and a heater cover 11. The heater 10 heats and dries the ink applied to the print medium P after printing by the print head 9. The heating unit also has the function of heating water-soluble resin particles (described below) to form a film for coating. The water-soluble resin particles are a resin that forms a thin film upon heating after being applied to the print medium, thereby improving the wear resistance of the image.

[0028] A heater 10, supported by a frame (not shown), is arranged in a curing area downstream of the position where the print head 9 mounted on the carriage 2 performs reciprocating scanning in the transport direction, and dries liquid ink on the print medium P using heat. The heater 10 is covered by a heater cover 11, and the heater cover 11 has the function of effectively applying the heat of the heater 10 to the print medium P, as well as the function of protecting the heater 10. After printing by the print head 9, the print medium P is wound around the reel 6 and forms a roll-shaped wound medium 12. Specifically, a sheathed heater, a halogen heater, or the like can be used for the heater 10.

[0029] In the printing method of this exemplary embodiment, the heating temperature of the heating unit in the curing zone is preferably equal to or greater than the lowest film-forming temperature of the water-soluble resin particles. Furthermore, the heating unit evaporates most of the liquid components in the ink, such as the water-soluble organic solvent, during heating. Therefore, it is desirable to provide a heating period that ensures sufficient energy for evaporating most of the liquid components. This setting is determined by taking into account film-forming characteristics and evaporation, as well as the productivity and heat resistance of the print medium P.

[0030] As the heating means of the heating unit in the curing area, heating by hot air ventilation from above, heating by a contact-type thermal conduction heater from below the print medium, etc. can be used. In addition, in the present exemplary embodiment, the heating means of the heating unit in the curing area is arranged at one position, but if a configuration is provided in which the temperature measured on the print medium P by a radiation thermometer (not shown) does not exceed the value set for the heating temperature, the heating means may be arranged at two or more positions.

[0031] (2) Print head configuration

[0032] Figure 3 The ejection port surface of the print head 9 according to this exemplary embodiment is shown. The print head 9 includes an ejection port array 22K for ejecting black ink (K), an ejection port array 22C for ejecting cyan ink (C), an ejection port array 22M for ejecting magenta ink (M), and an ejection port array 22Y for ejecting yellow ink (Y). Each ink contains a coloring material. Since these black ink (K), cyan ink (C), magenta ink (M), and yellow ink (Y) each contain a coloring material, for simplicity, they may also be referred to as coloring material inks in the following description.

[0033] The print head 9 further includes an ejection port array 22RCT for ejecting a reactive liquid ink (RCT) that does not contain a coloring material. This reactive liquid ink does not contain a coloring material but contains a reactive component that reacts with the coloring material contained in the coloring material ink and can reduce bleeding by contacting the coloring material ink on the print medium.

[0034] In the print head 9, the ejection port arrays 22K, 22C, 22M, 22Y, and 22RCT are arranged in this order from left to right in the X direction. The ejection port arrays 22K, 22C, 22M, 22Y, and 22RCT are formed by arranging 1280 ejection ports 30 for ejecting the corresponding inks at a density of 1200 dpi in the Y direction (array direction). In this exemplary embodiment, the amount of ink ejected from one of the ejection ports 30 at a time is approximately 4.5 pl.

[0035] The ejection port arrays 22K, 22C, 22M, 22Y, and 22RCT are each connected to an ink tank (not shown) storing a corresponding ink, and are each supplied with ink. The print head 9 and the ink tank used in this exemplary embodiment may be configured integrally or may be configured in a detachable manner.

[0036] The detailed composition of each of the black ink (K), the cyan ink (C), the magenta ink (M), the yellow ink (Y), and the reactive liquid ink (RCT) will be described below.

[0037] Water-soluble resin particles that form a film by heat and improve the wear resistance of printed materials can be included in the coloring material of each ink color, or can be included in the transparent emulsion ink (Em), which is a third ink that does not contain a coloring material and is different from the coloring material ink and the reaction liquid ink.

[0038] In this case, the print head 9 may include an ejection port array 22Em for ejecting transparent emulsion ink.

[0039] (3) Printing system configuration

[0040] Figure 43 is a block diagram showing a schematic configuration of a control system of the printing apparatus 100 in this exemplary embodiment. The main control unit 300 includes a central processing unit (CPU) 301, a read-only memory (ROM) 302, a random access memory (RAM) 303, and an input / output (I / O) port 304. The CPU 301 performs processing operations and printing operations, including calculations, selections, determinations, and controls. The ROM 302 stores control programs to be executed by the CPU 301, etc. The RAM 303 serves as a buffer for print data, etc. The memory 313 stores mask patterns, etc., described below. Drive circuits 305, 306, 307, and 308 are connected to the input / output port 304, and the drive circuits 305, 306, 307, and 308 serve as actuators for the conveying motor 309 for driving the conveying roller 14, the carriage motor 310 for the scanning carriage 2, the print head 9, and the heater 10. Furthermore, the main control unit 300 is connected to a host (host personal computer (PC)) 312 via an interface circuit 311 .

[0041] (4) Image processing

[0042] Figure 5 1 is a block diagram showing the flow of image data conversion processing. Image processing in the printing system of this example is performed by each of the host PC 312 and the printing apparatus 100. Through the image data conversion processing, data indicating the ink dot formation position in each print scan is generated from the input print data.

[0043] (4-1) Host Image Processing

[0044] Programs running on the operating system of the host PC 312 include applications and printer drivers. Examples of such applications include applications for creating computer-aided design (CAD) drawings. In application process J01, the application executes a process for generating image data corresponding to an image to be printed by the printing device 100. The image data generated by application process J01 is passed to the printer driver.

[0045] The printer driver of the host PC 312 generates image data in the page description language (PDL) format. Image data in the PDL format will be referred to as "PDL data" hereinafter. Known examples of PDL include "PDF" and "PostScript" produced by Adobe, and "HPGL / 2" produced by Hewlett-Packard. PDL is widely used as an image format in which not only bitmaps but also vector data such as straight lines and characters can be described. The printer driver performs a generation process J02 for generating image data for a printing device from the image data received from the application. The image data for the printing device is PDL data, and the printer driver adds a header portion such as print-related setting information set via the user interface (UI) of the host PC 312 to the received image data, and generates image data for the printing device. The generated image data for the printing device is sent to the printing device 100 via the interface circuit 311 of the printing device 100 and received by the printing device 100, and then stored in the RAM 303 used as a data buffer.

[0046] Figure 6A An example of the PDL format is shown. The PDL format includes a job management and printer setting command 601, an image data drawing command 602, and a job end command 605. The image data drawing command 602 includes a bitmap portion 603 and a vector command portion 604, and its format can represent not only bitmaps but also graphics (such as characters and lines). Figure 6B There is shown an image data drawing command 602. The image data drawing command 602 has a configuration in which a plurality of series of drawing commands 602 (referred to as a display list (DL)) per a specific unit (here, 64 KB) are combined.

[0047] Figure 6C A command table showing the breakdown of the drawing commands 602 is shown. The drawing commands 602 are broadly classified into bitmap drawing commands and vector drawing commands. Furthermore, vector drawing commands are broadly classified into "line drawing commands" for pen color, line width, and drawing, "character drawing commands" for specifying character fonts and the characters themselves, and "fill drawing commands" for specifying fill type and fill density. This PDL-formatted image data is transmitted from the host PC 312 to the printing apparatus 100.

[0048] (4-2) Processing in the Printing Device

[0049] Will describe Figure 5The image data analysis processing J03 and subsequent processing shown in FIG. The CPU 301 reads the computer-executable program stored in the ROM 302, serving as a storage area, into the RAM 303, serving as working memory, and executes the read program, thereby performing the series of processing shown here. After the host computer 312 transmits a print command including image data in PDL format, a series of print command data is first received via the interface circuit 311 and the I / O port 304 and stored in the RAM 303, serving as working memory. In addition to the image data, the print command data also includes the size of the image data and the print mode used to print the image data. Based on the results of analyzing this information, the image processing described below is performed.

[0050] CPU 301 executes Figure 5 The image data analysis process J03 shown in FIG. In the image data analysis process J03, the image data in the PDL format is sequentially read out from the RAM 303 used as a working memory. The CPU 301 interprets the drawing commands included in the PDL data and expands the image data in the PDL format (PDL data) into raster image data in a bitmap-like form. The raster image data is stored in the RAM 303 used as a working memory. In this exemplary embodiment, the raster image data is multi-valued data of R (red), G (green), and B (blue).

[0051] Next, the CPU 301 performs a color conversion process J04. The color conversion process J04 is a process of converting the print data into image data including a color signal of ink in the printing device 100. For example, in the case where image data indicating an image is included in the input print data and the image data indicates an image in coordinates of a color space such as sRGB representing monitor colors, the color coordinates (R, G, B) of the sRGB are converted into ink color data (C, M, Y, K) of the printing device 100. The conversion method thereof is implemented by a known technique, such as a process using matrix arithmetic processing and a three-dimensional lookup table (LUT). The printing device 100 in this example uses black (K), cyan (C), magenta (M) and yellow (Y) inks so as to convert image data having an RGB signal into image data formed by 8-bit color signals of K, C, M and Y. The color signal of each ink corresponds to the amount of application of each ink. The number of ink colors is not limited to four of K, C, M and Y. When using inks other than KCMY inks, for example, light cyan (Lc) ink having a lower density than cyan (C), light magenta (Lm) ink having a lower density than magenta (M), and gray (Gy) ink are used, and color signals corresponding to these inks are generated.

[0052] Next, the CPU 301 executes Figure 5The halftone process J05 shown is shown. The halftone process J05 is performed on the image data including the color signal that has undergone the color conversion process J04. This halftone process J05 is a process for reducing the number of tone levels of the image data. In this example, the halftone process J05 is performed using a dither matrix, in which a threshold value for comparison with the value of the image data is arranged for each pixel. Binary data indicating whether an ink dot is formed in each pixel is ultimately generated by the halftone process J05. In the case of adopting the multi-pass printing method described below, the process of determining the pixels to be injected in each scan is performed by performing a mask process on the data after the halftone process using a mask pattern or the like to thin out the ink used for printing in one scan.

[0053] Next, the CPU 301 executes Figure 5 The print data generation process J06 is shown. Print data generation process J06 generates print data in which print control information is added to print image data containing 1-bit dot data. The generated print data is stored in RAM 303, which serves as working memory. The CPU 301 sequentially reads the binary print data stored in RAM 303, which serves as working memory, and inputs it to the head drive circuit 307, which then executes drive process J07. The 1-bit print data for each ink color input to the head drive circuit 307 is converted into drive pulses for the print head 9, which is then driven by the head drive circuit 307 to eject ink at predetermined timings based on the drive pulses.

[0054] The lookup tables referenced in the color conversion process and the dither matrix referenced in the halftoning process are prepared in advance in a plurality of sets in the ROM 302, which serves as a storage area, according to the type of print medium and the print mode. In response to receiving print command data, the main control unit 300 analyzes the received print command data, selectively reads out the lookup table corresponding to the print command from the ROM 302, which serves as a storage area, loads the read lookup table into the RAM 303, which serves as a working memory, and uses the lookup table.

[0055] In the present exemplary embodiment, the processes J01 and J02 are executed in the host computer 312, and the process J03 and subsequent processes are executed in the printing apparatus 100. However, the processes J01 to J06 may be executed in the host computer 312.

[0056] (5) Multi-pass printing method

[0057] In this exemplary embodiment, an image is printed by multi-pass printing, in which printing is performed by scanning a predetermined area on a printing medium multiple times using each ink of K, C, M, Y, and RCT. General multi-pass printing will be described below.

[0058] Figure 7 is a diagram illustrating a general multi-pass printing method. Here, an image is formed by ejecting ink from each of six ejection port groups A1 to A6 formed by respective ejection port arrays 22 divided in the Y direction to a predetermined area. In other words, the predetermined area is scanned six times. In practice, in response to completion of one scan by the print head 9, the print medium P is transported downstream in the Y direction and the next scan is performed. However, for simplicity, in Figure 7 , the print head 9 is shown as if moving upstream in the Y direction between scans.

[0059] Initially, in the first scan, the print head 9 is driven to perform scanning in a positional relationship in which a predetermined area 80 on the print medium P and the ejection opening group A1 in the ejection opening array 22 face each other. During the first scan, ink is ejected from the ejection opening group A1 to the predetermined area 80 based on the print data corresponding to each type of ink corresponding to the first scan. In response to the completion of the first scan, the print medium P is transported in the Y direction by a distance corresponding to one ejection opening group. Subsequently, a second scan is performed, and ink is ejected from the ejection opening group A2 to the predetermined area 80. Thereafter, transport of the print medium P and ejection from the print head 9 are alternately performed to perform ink ejection from the ejection opening groups A3 to A6 to the predetermined area 80 in the third to sixth scans. Thus, multi-pass printing of the predetermined area 80 is completed.

[0060] (6) Ink composition

[0061] The details of each ink of the ink set used in this exemplary embodiment will be described. Unless otherwise specified, the following "part" and "%" represent a mass basis.

[0062] (6-1) Composition of each ink

[0063] The composition of each ink will be described in detail below. The coloring material inks (C, M, Y, K) and the reaction liquid ink (RCT) used in this exemplary embodiment all contain a water-soluble organic solvent. In terms of wettability and moisture retention of the surface of the print head 9, it is desired that the boiling point of the water-soluble organic solvent be above 150°C and below 300°C. In terms of the function of a film-forming aid for fine resin particles and the swelling / dissolution properties of the recording medium forming the resin layer, a heterocyclic compound having a lactam structure is particularly ideal. Representative heterocyclic compounds are: ketone compounds such as acetone and cyclohexanone; propylene glycol derivatives such as tetraethylene glycol dimethyl ether, N-methylpyrrolidone and 2-pyrrolidone.

[0064] From the viewpoint of ejection performance, the content of the water-soluble organic solvent is desirably 3 wt % or more and 30 wt % or less. Specific examples of the water-soluble organic solvent include: alkyl alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol; amides, such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols, such as acetone and diacetone alcohol; ethers, such as tetrahydrofuran and dioxane; polyalkylene glycols, such as polyethylene glycol and polypropylene glycol; ethylene glycol or an alkylene glycol having 2 to 6 carbon atoms, such as propylene glycol, butylene glycol, tris(2-hydroxy-4-ol)ol, and diisopropyl alcohol. Ethylene glycol, 1,2,6-hexanediol, thiodiglycol, hexylene glycol, and diethylene glycol; lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate; glycerol; lower alkyl ethers of polyols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether; polyols such as trimethylolpropane and trimethylolethane; and N-methyl-2-pyrrolidone, 2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. The above water-soluble organic solvents can be used alone or as a mixture.

[0065] Deionized water is preferably used as the water. The content of the water-soluble organic solvent in the reaction solution ink (RCT) is not particularly limited. However, in addition to the above-mentioned components, surfactants, defoaming agents, preservatives, mildew inhibitors, etc. may be appropriately added to the coloring material inks (C, M, Y, K) to provide the desired physical properties as needed.

[0066] The coloring material inks (C, M, Y, K) and the reactive liquid ink (RCT) used in this exemplary embodiment all contain surfactants. Surfactants act as penetrants to improve the permeability of inks used in inkjet printing-specific printing media. The greater the amount of surfactant added, the stronger the ability to reduce the surface tension of the ink, thereby improving the wettability and permeability of the ink to the printing medium. In this exemplary embodiment, a small amount of acetylene-ethylene glycol (EO) adduct, etc., is added as a surfactant, and adjustments are made so that the surface tension of each ink is 30 dyn / cm or less, and the surface tension difference between the inks is 2 dyn / cm or less. More specifically, the surface tension of each ink is adjusted to approximately 22 to 24 dyn / cm. Surface tension is measured using a fully automatic surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.). As long as the surface tension of the ink can be measured, the measuring device is not limited to the measuring device in this example.

[0067] The pH of each ink in this exemplary embodiment is stable on the alkaline side, with a value of 8.5 to 9.5. The pH of each ink is desirably 7.0 or higher and 10.0 or lower in order to prevent dissolution and degradation of components in contact with each ink in the printing device and print head, and to prevent a decrease in the solubility of the dispersed resin in the ink. The pH values ​​were measured using a pH meter F-52 manufactured by HORIBA Corporation. The measuring device is not limited to this example as long as the pH of each ink can be measured.

[0068] (6-2) Reaction Liquid Ink

[0069] In the present exemplary embodiment, a printing system using a reaction liquid for insolubilizing part or all of the solid components of the coloring material ink is employed to solve image-related problems such as bleeding and beading.

[0070] The reaction solution is intended to make the dissolved dye and the dispersed colorant and resin insoluble. Therefore, examples of the reaction solution include solutions containing polyvalent metal ions (examples of such solutions include magnesium nitrate, magnesium chloride, aluminum sulfate, and ferric chloride). As one type of such polymerization using cations, for the purpose of charge neutralization of water-soluble resin particles and insolubilization of anionic soluble substances, a low molecular weight cationic polymer used in a polymerization agent can be used.

[0071] Another reaction system is a system in which insolubilization is achieved by utilizing a pH difference in a reaction solution.

[0072] As mentioned above, most coloring inks used in inkjet printing are generally stable in alkaline environments due to the characteristics of the coloring material. The pH is typically around 7 to 10, and there are many examples where, from an industrial perspective and taking into account the influence of external environments, the pH is typically set to around 8.5 to 9.5. To aggregate and solidify this type of coloring ink, the stable state is disrupted by mixing with an acid solution and changing the pH, thereby aggregating the dispersed components. Acidic solutions can also be used as the reaction liquid for this reaction.

[0073] (6-3) Water-soluble resin particles

[0074] The coloring material ink of this exemplary embodiment contains water-soluble resin particles, which are used to improve the wear resistance (fixability) of the printed image by bringing the print medium and the coloring material into close contact with each other. The resin particles are melted by heat to form a resin particle film, and the solvent contained in the ink is dried by a heater. In this exemplary embodiment, the "resin particles" are polymer particles dispersed in water.

[0075] Specific examples of resin particles include: acrylic resin particles synthesized by emulsion polymerization of monomers such as (meth) alkyl acrylates and (meth) alkyl amides of acrylic acid; styrene-acrylic resin particles synthesized by emulsion polymerization of (meth) alkyl acrylates or (meth) alkyl amides of acrylic acid and styrene monomers; and polyethylene resin particles, polypropylene resin particles, polyurethane resin particles, and styrene-butadiene resin particles. The examples further include: core-shell resin particles, each including a core and a shell made of polymers having different combinations; and resin particles produced by emulsion polymerization using pre-synthesized acrylic particles as seeds for controlling particle size. Examples also include mixed resin particles produced by chemically bonding different types of resin particles (e.g., acrylic resin particles and polyurethane resin particles).

[0076] The water-soluble resin fine particles are not necessarily contained in the coloring material, and may be contained in the transparent emulsion ink (Em), which is a third ink that does not contain a coloring material and is different from the coloring material ink and the reaction liquid ink.

[0077] (7) Printing media

[0078] The printing device in this exemplary embodiment can print on low-permeability print media that is not easily permeable to water. Low-permeability print media herein refers to media that does not absorb water or absorbs very little water. Therefore, it is difficult to form images using ink that does not contain an organic solvent because the ink is repelled. In contrast, low-permeability print media is superior in terms of water resistance and weather resistance and is therefore suitable as a medium for forming printed products for outdoor use. Print media with a water contact angle of 45° or greater, preferably 60° or greater, at 25°C are generally used as media for forming printed products for outdoor use.

[0079] Low-permeability printing media is a printing medium with a plastic layer formed on the outermost surface of a substrate, without an ink-receiving layer formed on the substrate. Examples include sheets of glass, YUPO (registered trademark), or plastic, films of glass, YUPO, or plastic, or banners of glass, YUPO, or plastic. Examples of these plastics for coating include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. These low-permeability printing media are superior in water resistance, light resistance, and abrasion resistance, and are therefore commonly used for printing on outdoor display objects.

[0080] The Bristow method described in the Japanese TAPPI Paper and Pulp Test Method Standard No. 51, "Bristow Method for Test Method for Liquid Absorption of Paper and Paperboard," can be used as an example of a method for evaluating the permeability of a printing medium. In the Bristow method, a predetermined amount of ink is injected into a storage container having a slit with a predetermined opening size. Through the slit, the ink comes into contact with a printing medium that has been processed into a strip shape and then wound on a disk. While the position of the storage container is fixed, the disk is rotated, and the area (length) of the ink strip transferred to the printing medium is measured. The amount of transfer per unit area per second (ml·m-2) can be calculated based on the area of ​​the ink strip. In this exemplary embodiment, a printing medium in which the amount of ink transferred (amount of water absorbed) within 30 milliseconds 1 / 2 by the above-mentioned Bristow method is less than 10 ml·m-2 is considered to be a low-permeability printing medium.

[0081] (8) Seepage control

[0082] Will refer to Figure 8A The color conversion processing in the present exemplary embodiment is described. Figure 8A It is shown in Figure 5 This diagram shows a lookup table used in the color conversion process J04. The horizontal axis indicates the input signal value in the color conversion process J04, and here, indicates achromatic tones (R=G=B) from white (R=G=B=255) to black (R=G=B=0). The vertical axis indicates the output signal value from the color conversion process J04. The greater the amount of K ink applied, the higher the density of the input image. As the amount of K ink applied increases, the amount of reactive liquid ink (RCT) applied increases, accelerating the increase in ink viscosity to fix the K ink to the print medium and control bleeding.

[0083] On the contrary, in the case of printing lines, since lines generally have high density, when performing Figure 8A During the color conversion process, a large amount of reaction liquid is applied. Figure 10 As shown, if there is a difference in the landing position between the coloring material ink and the reactive liquid ink, the ink flows (bleeding) in a small area due to the contact between the coloring material ink dots and the reactive liquid dots. As the line becomes narrower, this small bleeding becomes more visually noticeable, thereby reducing the line quality.

[0084] Therefore, in this exemplary embodiment, if Figure 8B As shown, the color conversion process of preventing the reactive liquid ink from being applied to the line is performed in order to control the generation of minute bleeding caused by the contact between the above-mentioned coloring material ink and the reactive liquid ink.

[0085] Hereinafter, a method of forming a high-definition line pattern by controlling bleeding of lines will be described in more detail.

[0086] (Line detection)

[0087] First, a method of detecting lines will be described.

[0088] exist Figure 5 When the vector data is drawn as RGB data in the image data analysis process J03 shown in FIG, the CPU 301 obtains line attributes from the vector data and generates a line attribute plane (α channel) indicating whether the data is a line or not, pixel by pixel. More specifically, by determining and applying Figure 6C Pixels corresponding to the coordinates of “draw one stroke while moving the coordinates” in the portion of the line drawing command in the illustrated PDL are line pixels, and the CPU 301 recognizes the line pixels.

[0089] (Processing of line parts)

[0090] Next, control of the line portion will be described.

[0091] The following will be described in detail Figure 5 In the color conversion process J04 of this exemplary embodiment, color separation LUT switching control is further performed. Here, based on the result of line determination performed by the image data analysis process J03, control for switching to the lookup table to be used in the color conversion process J04 is performed pixel by pixel.

[0092] If the target pixel is a line pixel, the color separation LUT switching control unit reads a lookup table for line pixels from a plurality of lookup tables pre-stored in the ROM 302 as a storage area, and supplies the read lookup table to the color conversion process J04. On the other hand, if the target pixel is not a line pixel, the color separation LUT switching control unit reads a lookup table for non-line pixels from a plurality of lookup tables pre-stored in the ROM 302 as a storage area, and supplies the read lookup table to the color conversion process J04. The color conversion process J04 converts the received RGB signal into a CMYK signal based on the supplied lookup table.

[0093] In this exemplary embodiment, the Figure 8A Each example shown in is used as a lookup table for non-line pixels (normal pixels), using Figure 8B The example shown in performs processing as a lookup table of line pixels.

[0094] In either example, the horizontal axis indicates the input signal value in the color conversion process J04 and indicates achromatic tones (R=G=B) from white (R=G=B=255) to black (R=G=B=0). On the other hand, the vertical axis indicates the output signal value in the color conversion process J04.

[0095] In the case where the target pixel is not a line pixel, Figure 8ADuring the color conversion process using the lookup table shown, image data for applying the reaction liquid is generated. This ensures that the reaction liquid is applied to non-linear objects. Ink is applied to locations adjacent to the non-linear objects, so if the reaction liquid is not applied, significant bleed would occur. Therefore, for non-linear objects, the viscosity of the coloring material ink increases rapidly by applying the reaction liquid, thereby controlling bleed. With the coloring material's viscosity increased, the print medium passes through heater 10, causing the ink to fuse at the current location, completing image formation with controlled bleed.

[0096] On the contrary, in the case where the target pixel is a line pixel, based on Figure 8B The lookup table for line pixels shown in the figure generates image data without the application of reaction liquid during the color conversion process. Consequently, the amount of reaction liquid applied to the area for printing the line portion including the target pixel becomes zero. Even if the positions of the ink and reaction liquid on the print medium shift, bleeding due to the application of reaction liquid does not occur, allowing for the formation of high-quality fine lines.

[0097] Figure 9A-1 、 Figure 9A-2 、 Figure 9B-1 and Figure 9B-2 The amount of reaction liquid applied when each of the line image and the non-line image is printed is shown. Figure 9A-1 shows a line image to be printed using K ink, Figure 9A-2 The reaction liquid to be applied in this printing is shown. Figure 9B-1 shows a non-line image to be printed using K ink, Figure 9B-2 The reaction liquid to be applied in this printing is shown. For line images, use Figure 8B The lookup table in generates image data without applying the reaction liquid, so if Figure 9A-2 As shown, no reaction solution was applied.

[0098] On the contrary, in case of non-line images, use Figure 8A The lookup table shown generates image data, so if Figure 9B-2 As shown in FIG. 1 , the reaction liquid is applied to 50% of the pixels in the area where the K ink is applied. When the area of ​​5 pixels (1 / 300 inch) in the vertical direction and 1 pixel (1 / 1200 inch) in the horizontal direction is the unit area, Figures 9A-1 to 9B-2 In each of the line image and the non-line image shown in , K ink having a density of 100% is applied per unit area. The amount of reaction liquid applied per unit area in the line image is smaller than that in the non-line image.

[0099] As described above, the amount of the reaction liquid is appropriately controlled for each area according to the type of image. Therefore, even if the printing medium is a low-permeability printing medium, the degradation of image quality can be suppressed by controlling the bleeding of fine lines while fixing the coloring material ink to the printing medium.

[0100] The above description describes a form in which data is generated so that the reaction liquid is not applied to pixels in the linear portion. However, if the amount of reaction liquid applied per unit area in the linear portion is smaller than that applied per unit area in the non-linear portion, the effect of controlling bleeding can be achieved.

[0101] (According to the line width processing)

[0102] Incidentally, even if the thick line is a line portion, in the case where the reaction liquid is not applied to the thick line (an object having a large area), a large amount of ink still exists in a wide range, as with the non-line object. Therefore, if the reaction liquid is not applied because the thick line is a line portion, the ink in the center portion of the thick line in particular is not successfully fixed to the print medium, so when the print medium is tilted, the ink may flow. On the contrary, in the case where the reaction liquid is applied to the thick line, in the edge portion at the boundary between the line portion and the non-line area, minute oozing occurs as a phenomenon due to the contact between the coloring material ink and the reaction ink. However, the minute oozing is associated with the thick line and is therefore less likely to be visually noticed. Therefore, it is desirable to control the application of the reaction liquid so that the reaction liquid is not applied to thin lines having a specific width or less, and the reaction liquid is appropriately applied to thick lines having a specific width or more in a manner similar to the case of non-line pixels.

[0103] Specifically, it is possible to determine whether a line is a thin line or a thick line based on the line width information obtained from the "pen line width setting" of the line drawing command in the PDL. If the line width of the drawing command is less than a predetermined width, the line is determined to be a thin line; if the line width of the drawing command is greater than a predetermined width, the line is determined to be a thick line. This control is performed so that if the target pixel is a thin line, the color conversion process is applied. Figure 8B The lookup table for line drawing in , and if the target pixel is a thick line or non-line, it is applied in the color conversion process Figure 8A Lookup table for non-line drawing (for normal pixels).

[0104] The above description describes a process where the amount of reaction liquid applied to thin lines is zero. However, the amount of reaction liquid applied does not need to be zero, and can be controlled to gradually decrease as the line becomes thinner using line width information. When drawing a line with a line width that changes from thin to thick, if a large amount of reaction liquid is suddenly applied when the line width exceeds a certain width, sudden and noticeable seepage will occur. Therefore, by gradually changing the amount of reaction liquid applied according to the line width, the boundary between the part with seepage and the part without seepage is less obvious, and seepage can be suppressed in thin lines.

[0105] For example, signal value conversion for generating image data may be performed so that as the line width becomes smaller, the image data becomes closer to the applied image data. Figure 8B The lines in the image are drawn using the lookup table data, and as the line width increases, it is closer to Figure 8A For example, Figure 8A The lookup table for non-line drawing in is applied to thick lines with a predetermined line width or above, while Figure 8B The lookup table used for line drawing in is applied to thin lines with a predetermined line width or less. For line widths in between, the lookup table can be used based on the line width defined in . Figure 8A Non-line drawing lookup table and Figure 8B Color conversion processing is performed using signal values ​​obtained by performing linear interpolation processing between the line drawing lookup tables in the image.

[0106] The interfacial tension and wettability of ink droplets vary depending on the print medium, and the droplet's wet spreading pattern and speed also differ. Changing the thin line determination threshold (the aforementioned predetermined width) for each print medium or print speed allows for optimal control of the reactive liquid application for each print medium.

[0107] (Color line situation)

[0108] While the case of a single-color thread using K ink has been described so far, similar control is also effective for color threads using other color inks (e.g., C ink, M ink, and Y ink). Furthermore, for example, for threads generated using secondary colors made of M and Y inks, such as red threads, controlling the amount of reaction liquid to decrease allows for controlled bleeding and improved thread quality.

[0109] (In the case of raster data)

[0110] In this exemplary embodiment, the case where the input data is vector data for CAD drawing or the like has been described, but the input data may be raster data such as photo images and poster images. A method of detecting lines and line widths in this case will be described.

[0111] In the case of raster data (such as RGB images), the edge amount and directivity are extracted in the filtering process, and the possibility of the line can be estimated based on this. More specifically, a typical edge extraction filter and pattern matching technology for determining directivity can be used.

[0112] However, it is desirable to set a filter size appropriate for the line width to be detected. If an excessively wide filter size is set, objects of large width that are not intended to be thin lines may be mistakenly determined as thin lines. For example, if you want to detect lines ranging from 1 pixel above to 5 pixel below, setting a 7×7 pixel group around the target pixel as the filter size is appropriate. By setting the filter size in this way, when the probability that the target pixel is a thin line is greater than a predetermined value, the target pixel is determined to be a thin line.

[0113] The interfacial tension and wettability of ink droplets vary depending on the print medium, leading to different droplet spreading patterns and speeds. The filter size can be adjusted for each print medium or print speed. This allows for controlled application of the reaction liquid based on the print medium type.

[0114] The following describes a second exemplary embodiment of the present invention. While the first exemplary embodiment describes the control of reactive liquid application for thin lines, applying reactive liquid to isolated ink dots other than thin lines can also induce ink flow and cause ink bleeding. The second exemplary embodiment describes a case where the reactive liquid application control described in the first exemplary embodiment is extended to control isolated ink dots. Similar portions to those in the first exemplary embodiment may be omitted.

[0115] If a coloring ink dot is isolated, applying the reaction liquid to the same location as or adjacent to the isolated dot can cause coloring ink bleeding due to contact between the coloring ink dot and the reaction liquid dot. If this phenomenon occurs at a single point, it is less likely to be visually detected. However, if such minute bleeding occurs dispersedly over a large area, the image may appear to have degraded granularity.

[0116] In the first exemplary embodiment, vector data for CAD drawing is described as an example. In this exemplary embodiment, a form in which granularity degradation greatly affects image quality, such as a picture or a poster, will be described as an example. Figure 11 1 is a block diagram illustrating image processing according to the present exemplary embodiment. In this example, the input image is raster data (RGB image).

[0117] (Point Isolation Estimation)

[0118] Will describe Figure 11 The isolation estimation process J08 in the process J01, J02 and J04 to J07 is similar to the combined Figure 5Processes J01, J02, and J04 to J07 have been described, so their description will be omitted here. Initially, isolation estimation process J08 calculates the average density of a predetermined area. This can be directly used as the average number of dots of the coloring material ink in the predetermined area. Here, the predetermined area is an area of ​​8×8 pixels.

[0119] Figure 12A The relationship between the pixel size in image processing and the dot diameter of the coloring material ink dot on the paper plane, as well as the presence or absence of point contact for each dot of the coloring material ink, is shown. The resolution in image processing is 1200 dpi, and the size of one pixel is approximately 21 μm. The ink droplet ejected by one ejection is 4.5 pl, and the dot diameter of the ink dot on the paper plane is approximately 40 μm. Therefore, as Figure 12A As shown, in the present exemplary embodiment, if the number of coloring material ink dots in a predetermined area is approximately 25% or less, there is a possibility that the coloring material ink dots are not in contact with each other, that is, all the coloring material ink dots are isolated dots. In contrast, if the density of the input image is 50% or higher, the coloring material ink dots are likely to be in contact with each other in all directions, and isolated ink dots are unlikely to exist. Figure 12B-1 The point contact rate with respect to the density of the input image is shown in the form of a curve. The point isolation probability is the opposite of the contact probability. Figure 12B-2 The isolation probability estimation process J08 estimates the isolation probability of the points in the region.

[0120] Furthermore, when the isolation degree is higher than a predetermined threshold, the isolation degree estimation process J08 determines that the target pixel is an isolated point, and when the isolation degree is equal to or lower than the predetermined threshold, the target pixel is determined not to be an isolated point. Here, the predetermined threshold is 30%, and when the isolation degree is higher than 30%, the isolation degree estimation process J08 determines that the target pixel is an isolated point.

[0121] (Reactive ink control based on dot isolation)

[0122] Next, a method of controlling the amount of reactive liquid ink applied based on dot isolation will be described. Figure 11 In the color conversion process J04, the reaction liquid ink application amount control is executed.

[0123] Next, the amount of reaction liquid applied can be corrected by a method similar to the method described in the first exemplary embodiment. In the case where the point is not an isolated point, the amount of reaction liquid applied can be corrected by a method similar to the method described in the first exemplary embodiment. Figure 8A A lookup table for normal pixels to which the reaction liquid is applied is used, and color conversion processing J04 is performed. Contact between the coloring material inks occurs frequently, so significant ink flow (bleeding) is likely to occur. However, by sufficiently applying the reaction liquid to increase the viscosity of the coloring material ink, the occurrence of bleeding can be controlled. On the contrary, in the case where the dot is an isolated dot, the coloring material ink is used. Figure 8B Color conversion processing J04 is applied without applying a lookup table for the reaction liquid. Since there is no contact between the coloring material inks and between the coloring material inks and the reaction liquid ink, the isolated dots do not flow and are heated by heater 10 without bleeding. Consequently, the ink can be fixed to the print medium without disrupting the dot arrangement.

[0124] As described above, according to the second exemplary embodiment, dot isolation is estimated based on the estimation result and the reactive ink is appropriately controlled so that an image can be formed while controlling bleeding without compromising the granularity of low-density areas regardless of the density of the image.

[0125] (Line situation)

[0126] The above-mentioned isolated point control is also effective for line parts.

[0127] In the case of a line portion, it is important whether the line is independent of other objects. In the case of a black line on a white background, ink is not applied to the portion around the black line, so the average density of the predetermined area is low, and the independence (isolation) of the determined line is high. Therefore, using Figure 8B The control is performed using a lookup table in to reduce the application of the reaction liquid, thereby controlling the seepage through contact with the reaction liquid.

[0128] On the contrary, in the case of a black line on a colored background, the coloring material ink is applied to the colored background portion, and therefore, the ink of the object of the non-line portion is applied around the black line. Therefore, the average density of the predetermined area is high, and the independence (isolation) of the determined line is low. Therefore, using Figure 8A and apply the reaction liquid sufficiently to control the bleed-through between the line and the color background.

[0129] In the thick line, the isolation is determined to gradually increase from the inside to the outside. Therefore, when the reaction liquid application portion is closer to the outside, the amount of reaction liquid applied is reduced. In the ink inside the line, the viscosity is increased by the action of the reaction liquid, so that seepage can be controlled. For the ink on the edge of the thick line, the amount of reaction liquid to be applied is very small, but the ink on the edge is pulled by the internal ink with increased viscosity, so the ink on the edge does not flow to the white part outside the edge. Therefore, while controlling the seepage by reducing the amount of reaction liquid applied to the edge portion of the thick line, the seepage can be controlled by applying a sufficient amount of reaction liquid to the center portion of the thick line, thereby controlling the seepage of the entire thick line and preventing the image quality from deteriorating. In addition, the reaction liquid is not applied to unnecessary parts, thereby reducing the consumption of the reaction liquid.

[0130] (Grayscale condition)

[0131] When using grayscale images, switching between applying and not applying the reactive ink can present new problems, depending on whether the dots are isolated dots as described above. If a large amount of reactive ink is suddenly applied at a constant grayscale, from low to high concentration, the continuity of concentration and particle size may be disrupted, potentially leading to false contours.

[0132] By gradually changing the amount of reaction liquid according to the degree of isolation, singularities are eliminated without disrupting continuity. This can be achieved by multiplying the reaction liquid application amount data (RCT data) generated after the color conversion process using the lookup table in the color conversion process J04 by a correction coefficient based on the degree of point isolation. Specifically, the following numerical formula can be used for correction:

[0133] RCT data (after correction) = RCT data (before correction) × (100% - point isolation).

[0134] When the point isolation is 0% (when the contact ratio between points is 100%), RCT data (after correction) = RCT data (before correction), which results in Figure 8A The reaction solution shown was applied thoroughly to the area.

[0135] In contrast, when the point isolation is 100% (when the contact ratio between points is 0), the RCT data (after correction) = 0, which results in Figure 8B The reaction liquid is shown not to be applied to this area.

[0136] When the point isolation is 50%, RCT data (after correction) = RCT data (before correction) × (100% - 50%) = RCT data (before correction) × 0.5. In other words, the application of the Figure 8A The lookup table output in is half of the amount of reactant applied.

[0137] This can also be achieved by using a method of using a linear interpolation lookup table described in the first exemplary embodiment instead of the above-described method of multiplying by a correction coefficient.

[0138] (Character / Padding)

[0139] Both fill patterns and characters are collections of thin lines, but the average concentration can be about 50%. If a reaction liquid is applied in this case, the thin lines spread, and the image quality of the fill and characters will be impaired. Therefore, a method for controlling the reaction liquid by determining whether the target object is an object whose shape will remain independent of the surrounding environment (such as a fill pattern or character) and by estimating the isolation of the target pixel in addition to the point contact probability estimated based on the average concentration will be described.

[0140] Figure 13 An outline of this control is shown.

[0141] Examples of methods for determining whether a target object is an object whose shape is to be preserved include methods for determining whether a shape exists by edge extraction, and methods for determining whether an image signal is noise by determining the directionality of an image using a directional filter. More specifically, edges of a predetermined area including the target pixel are extracted, and the total edge volume of the area is calculated. Areas with a total edge volume greater than a specific amount are estimated to be characters or fill areas. Such an area is determined to be highly independent of the surrounding environment.

[0142] The degree of isolation is estimated based on a combination of the point contact probability estimated from the average concentration and the degree of independence from the surrounding environment, and the amount of reaction liquid applied is controlled based on the degree of isolation so that an image can be formed without damaging small characters or filling details.

[0143] By using attribute information indicating line attributes and character attributes obtained from the drawing command in the PDL described in the first exemplary embodiment, and combining it with the above-described point contact probability, the accuracy can be further improved.

[0144] As described above, in the second exemplary embodiment, the degree of dot or object isolation is estimated, and the amount of reactive ink applied is appropriately controlled based on the result of this estimation. This enables the formation of high-definition images while controlling bleeding in broad, high-density areas on the print medium without compromising the granularity of low-density areas, and also maintaining high resolution for delicate objects.

[0145] Other exemplary embodiments

[0146] While the method described above estimates dot isolation from a multi-valued image and controls the amount of reaction liquid based on the estimated dot isolation, a method can also be used to determine dot isolation based on dot data immediately before printing and control the amount of reaction liquid applied based on the determined dot isolation. For binary dot data immediately before printing, the amount of reaction liquid applied can be controlled by thinning out the reaction liquid dots. For example, this can be done by thinning out the reaction liquid dots at the edge of a line, or by identifying isolated dots of coloring material ink and thinning out the dots around them. Directly correcting the dot data, while still in the binary state indicating whether or not ink should be applied, allows for more precise correction on a dot-by-dot basis.

[0147] More specifically, the initial determination of whether a dot is an isolated dot is based on the number of neighboring dots. This is achieved by calculating the total number of dots in a 3×3 area surrounding the target pixel. If there is only one dot, the target pixel, then that dot is considered an isolated dot. At this point, if printing is done using only K, only the K dots are counted. If printing is done using CMYK, the dots for each of the CMYK colors are counted.

[0148] If the number of points is two or more, the probability of contact between the points increases. Figure 12A to Figure 12B-2 As described above, the contact ratio (the degree of non-isolated points) can be calculated based on the number of printed points. The inverse of the contact ratio is the point isolation degree. If the determination is made using point data, isolated points can be determined more accurately.

[0149] In this way, the amount of reaction liquid applied can be controlled based on the calculated isolation degree. The amount of reaction liquid applied can be controlled by thinning the reaction liquid dots by performing mask processing pixel by pixel using a mask pattern corresponding to the isolation degree.

[0150] It is difficult to determine the line in the binary image, but the binary point data image is added in a predetermined area and easily restored to a multi-value image (binary-to-multi-value conversion). Then, the line determination method described in the first exemplary embodiment is used to determine whether the target is a line, so that it can also be determined in the point data whether the target is a line. For line pixels, all reaction liquid dots are removed, and for non-line parts, mask processing is performed using a mask pattern corresponding to the isolation degree, and the reaction liquid dots are sparse. Therefore, the mask pattern to be used is changed according to the line part or the non-line part so that an appropriate amount of reaction liquid can be applied to each of the line part and the non-line part.

[0151] (Change the correction intensity for each color)

[0152] A configuration can be employed in which correction strength is increased for important colors in the image. For example, black lines are particularly important in CAD drawings. For example, the following control can be performed. First, the pure black of RGB (0, 0, 0) in the RGB image is determined from the input image, and a line that is only black is identified. Subsequently, if the line is a pure black line, all reaction liquid dots are removed.

[0153] Compared to black monochromatic lines, lines with colors other than black or secondary colors may have a larger amount of ink. For such lines, the amount of colorant ink applied to the line itself is large, and without the presence of reaction liquid, the ink overflows, causing bleeding. In contrast, as described above, the correction intensity is made variable for each color, the reaction liquid is thinned only for the black monochromatic lines, and the reaction liquid is applied to the lines of other colors in a similar manner to the non-line portions. This configuration ensures optimal quality for all lines.

[0154] (Change the correction intensity for each medium)

[0155] Depending on the printing medium, the interfacial tension of the ink droplets is different, and the wet spreading mode of the droplets is also different. For a single printing medium, it is effective to change the way the reaction liquid dots are thinned.

[0156] As described above, by using the method described in this exemplary embodiment, high-definition images can be formed while controlling bleeding in a wide high-density area on a printing medium without compromising the granularity of a low-density area and also maintaining high resolution of delicate objects.

[0157] In the exemplary embodiment described above, an image is printed on a print medium using an inkjet method that ejects ink from ejection ports. However, other types of printing devices can also be used if they have a configuration that allows the amount of reactive liquid applied to the print medium to be varied. In any type of device, there may be a mismatch between the timing of applying the reactive liquid ink and the timing of applying the ink containing the coloring material from the unit that applies the ink to the print medium, resulting in possible misalignment in the landing position. By applying the present invention to such a device, bleeding can be controlled, thereby preventing degradation in image quality.

[0158] The present invention may also be implemented by providing a program for implementing one or more functions of the exemplary embodiments described above to a system or device via a network or storage medium, and causing one or more processors in a computer of the system or device to read and execute the program. The present invention may also be implemented by a circuit (e.g., an application-specific integrated circuit (ASIC)) that implements one or more functions.

[0159] According to the present exemplary embodiment, it is possible to prevent the image quality of the line portion from being degraded.

[0160] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A printing device, comprising: an ink applying unit configured to apply ink including a coloring material to a printing medium; a reaction liquid applying unit configured to apply a reaction liquid for promoting ink curing by reacting with the ink to the printing medium; a control unit configured to control an application amount of the reaction liquid applied by the reaction liquid applying unit; as well as an identification unit configured to identify pixels included in the line portion based on image data indicating an image to be formed on a printing medium, wherein the printing device forms an image by applying ink from an ink applying unit according to image data, and In which, the control unit controls the amount of reaction liquid applied so that the amount of reaction liquid per unit area applied to the area where the line portion on the printing medium is to be printed, where pixels identified by the recognition unit as being included in the line portion are formed, is smaller than the amount of reaction liquid per unit area applied to the area where an image including pixels not identified by the recognition unit as being included in the line portion is formed.

2. The printing device according to claim 1, further comprising: a width determination unit configured to determine a width of a line portion including pixels recognized as a line portion by the recognition unit, In which, when the width determination unit determines that the width of the line portion formed on the printing medium by the pixels identified by the recognition unit is less than the predetermined width, the control unit controls the amount of reaction liquid applied so that the amount of reaction liquid per unit area to be applied to the area identified as the line portion is smaller than the amount of reaction liquid per unit area to be applied to the area in which an image including pixels not identified as the line portion by the recognition unit is to be formed.

3. The printing device according to claim 2, wherein: The control unit controls the amount of reaction liquid applied so that, when the width determined by the width determination unit is less than the predetermined width, the amount of reaction liquid per unit area applied to the area corresponding to the line portion whose width has been determined to be less than the predetermined width is less than the amount of reaction liquid per unit area applied to the area corresponding to the line portion whose width has been determined not to be less than the predetermined width when the width determined by the width determination unit is less than the predetermined width.

4. The printing device according to claim 2, wherein: A value that differs according to the type of printing medium is set as the predetermined width.

5. The printing device according to claim 2, wherein: The control unit controls the amount of reaction liquid applied so that the amount per unit area of ​​the reaction liquid applied to the line portion having the first width when the width determined by the width determination unit is a first width equal to or less than the predetermined width is greater than the amount per unit area of ​​the reaction liquid applied to the line portion having the second width when the width determined by the width determination unit is a second width less than the first width. The printing device according to claim 1 , wherein: The control unit controls an application amount of the reaction liquid so that the reaction liquid is not applied to a line portion formed on the printing medium by the pixels recognized by the recognition unit.

7. The printing device according to claim 1, wherein The identification unit is configured to identify pixels included in the line portion through filtering processing.

8. The printing device according to claim 1, further comprising: a conversion processing unit configured to perform conversion processing of converting data corresponding to a color space of an image into data corresponding to a color space supported by the printing apparatus using a lookup table, Here, the conversion processing unit switches to a lookup table to be used in the conversion processing, depending on whether the pixel to be subjected to the conversion processing is a pixel identified as a line portion by the identification unit.

9. The printing device according to claim 1, in, The ink applying unit is configured to apply a plurality of different colors of ink, The printing apparatus further includes a color determination unit configured to determine a color of the line portion if the pixel of the line portion is identified as a pixel of the line portion by the identification unit, and Here, when the pixels of the line portion are recognized as pixels of the line portion by the recognition unit, the control unit controls the amount of the reaction liquid to be applied based on the color of the line portion determined by the color determination unit.

10. The printing device according to claim 9, in, The ink applying unit is configured to apply a plurality of kinds of ink including black ink and ink of a color other than black, and In which, the control unit controls the amount of reaction liquid applied so that the amount of reaction liquid per unit area to be applied to the line portion including pixels identified as a line portion by the identification unit and determining that the color of the line portion is a color printed using only black ink is smaller than the amount of reaction liquid per unit area to be applied to the line portion including pixels identified as a line portion by the identification unit and determining that the color of the line portion is a color printed using ink of a color other than black.

11. A printing device comprising: an ink applying unit configured to apply ink including a coloring material to a printing medium; a reaction liquid applying unit configured to apply a reaction liquid for promoting ink curing by reacting with the ink to the printing medium; a control unit configured to control an application amount of the reaction liquid to be applied by the reaction liquid applying unit; as well as a determining unit configured to determine the degree of isolation of dots to be printed in a predetermined area on the printing medium based on image data indicating an image to be formed on the printing medium, In which, the control unit controls the amount of reaction liquid applied, so that the amount of reaction liquid per unit area applied to the predetermined area when the isolation degree of the predetermined area determined by the determination unit is higher than the predetermined degree is less than the amount of reaction liquid per unit area applied to the predetermined area when the isolation degree is below the predetermined degree.

12. The printing device according to claim 11, wherein The size of the predetermined area varies depending on the type of printing medium.

13. The printing device according to claim 11, wherein The determination unit determines the degree of isolation based on a value of at least one of an average density of the predetermined area, an edge amount of the predetermined area, and attribute information indicating that a pixel of the predetermined area is a line or a character.

14. The printing device according to claim 11, wherein When a line portion having a width greater than a predetermined width is to be printed, the control unit controls the amount of reaction liquid applied so that the amount of reaction liquid per unit area to be applied to the edge portion of the line portion is smaller than the amount of reaction liquid per unit area to be applied to the center portion of the line portion.

15. The printing apparatus according to claim 11 , further comprising: a conversion processing unit configured to perform conversion processing of converting data corresponding to the color space of the image into data corresponding to the color space supported by the printing apparatus using a lookup table, in, The conversion processing unit switches to a lookup table to be used in the conversion process according to whether the degree of isolation determined for the predetermined area by the determination unit is a predetermined value or more.

16. The printing device according to any one of claims 11 to 14, further comprising: a processing unit configured to perform masking processing of masking binary image data indicating whether ink is applied using a mask pattern and determining a position of ink to be applied on a printing medium, The processing unit changes a mask pattern to be used in the mask processing based on the degree of isolation determined by the determining unit.

17. The printing device according to any one of claims 1 to 15, wherein: The printing medium is a low-permeability printing medium that does not absorb water or absorbs very little water.

18. The printing device according to any one of claims 1 to 15, further comprising: Carriage that carries the ink application unit and reaction liquid application unit: a moving unit configured to move the carriage in a first direction; a conveying unit configured to convey the printing medium in a direction intersecting with the first direction, Here, while the moving unit moves the carriage, an image is formed on the printing medium by applying ink and reaction liquid from the ink applying unit and the reaction liquid applying unit to the printing medium.

19. The printing device according to any one of claims 1 to 15, in, The ink applying unit has an ejection port for ejecting ink, and The reaction liquid applying unit has a spraying port for spraying the reaction liquid.

20. A printing method, comprising: forming an image by applying ink and a reaction liquid to a printing medium according to image data using an ink applying unit configured to apply ink including a coloring material to the printing medium and a reaction liquid applying unit configured to apply a reaction liquid for promoting curing of the ink by reacting with the ink to the printing medium; identifying pixels included in the line portion based on image data indicating an image to be formed on a print medium; as well as Control is performed so that the amount of reaction liquid per unit area applied to an area where a line portion is to be formed on a printing medium using pixels recognized as a line portion is to be printed is smaller than the amount of reaction liquid per unit area applied to an area where an image including pixels not recognized as a line portion is to be formed.

21. A printing method, comprising: forming an image by applying ink and a reaction liquid to a printing medium according to image data using an ink applying unit configured to apply ink including a coloring material to the printing medium and a reaction liquid applying unit configured to apply a reaction liquid for promoting curing of the ink by reacting with the ink to the printing medium; determining, based on image data indicating an image to be formed on the print medium, a degree of isolation of dots to be printed in a predetermined area on the print medium; and Control is performed so that when the isolation degree of the predetermined area is determined to be higher than a predetermined degree, the amount of reaction liquid applied to the predetermined area per unit area is smaller than the amount of reaction liquid applied to the predetermined area per unit area when the isolation degree is lower than the predetermined degree.

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