JP2015112761A - Image processing system, image recorder, and image recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a deterioration in scratch resistance of an image from being caused by a decrease in the amount of a surface-active agent distributed on an image surface, while suppressing a granular feeling, when recording is performed by using ink containing a pigment and the surface-active agent.SOLUTION: Ink discharge is controlled so that dot connectivity of ink with relatively high coefficient of dynamic friction can become higher than dot connectivity of ink with relatively low coefficient of dynamic friction.

Description

  The present invention relates to an image processing apparatus, an image recording apparatus, and an image recording method.

  A recording head in which a plurality of ejection openings for ejecting ink are arranged is scanned with respect to the recording medium, and the recording scanning for ejecting the ink and the sub-scanning for transporting the recording medium are repeated, and an image is printed on the recording medium. Conventionally, a recording method for forming an image is known. In such a recording method, a so-called multi-pass recording method in which a recording scan is performed a plurality of times on a unit area on a recording medium is generally used.

  In such a multi-pass printing method, it is generally known that a plurality of ink droplets are ejected at positions separated from each other in one scan in order to reduce the graininess of an obtained image. Patent Document 1 discloses that recording is performed using a mask pattern in which a low-frequency component of a pattern of a print-allowable pixel is smaller than a high-frequency component as a mask pattern for determining a print position in each of a plurality of scans.

  On the other hand, in recent years, various types of inks and recording media have been used in the above-described recording methods. As a combination of the ink and the recording medium, it is known to use an ink containing a pigment and a recording medium with low ink permeability in order to form an image with high brightness.

  However, when an image is recorded using the ink and the recording medium as described above, the image is recorded by fixing the ink on the surface of the recording medium, so that the scratch resistance may not be sufficient. It has been known. Patent Document 2 discloses that the scratch resistance of an image decreases when the dynamic friction coefficient of the image surface is high. This document describes that by using an ink containing a predetermined modified siloxane compound, the dynamic friction coefficient on the image surface is relatively reduced, thereby improving the scratch resistance.

JP 2006-044258 A JP 2008-214611 A

  However, in the multi-pass printing method, when performing printing by dispersing dots in one scan and ejecting ink, the dynamic friction coefficient on the image surface cannot be sufficiently reduced depending on the type of ink used, It has been found that the desired scratch resistance may not be obtained.

  This problem will be described in detail below.

  FIG. 1 is a diagram for explaining a process of fixing ink droplets 50 formed when ink containing a pigment is ejected onto a recording medium 3 having low permeability.

  FIG. 1A is a diagram showing the state of ink when ink is applied to the surface of the recording medium 3. The pigment ink is fixed by evaporating volatile components such as water contained therein. Here, since the evaporation of the volatile component occurs at the gas-liquid interface, which is the interface between the ink droplet and air, the concentration of pigment, resin, etc. contained in the ink increases rapidly in the vicinity of the gas-liquid interface. . When such a rapid increase in the pigment concentration occurs, the dispersion state of the pigment in the ink may be disrupted, and the pigment may be deposited on the gas-liquid interface. In addition, an increase in the resin concentration means that the amount of the polymer component in the ink increases, and accordingly, the viscosity at the gas-liquid interface increases. Due to the precipitation of the pigment and the increase in viscosity at the gas-liquid interface, an ink film (hereinafter also simply referred to as an ink film) is formed on the gas-liquid interface.

  FIG. 1B is a diagram showing the state of ink when the ink film 51 is formed after FIG. Since the ink film 51 is formed on the surface of the ink droplet 50 due to the precipitation of the pigment and the increase in viscosity, evaporation of volatile components remaining in the ink droplet 50 is suppressed.

  FIG. 1C is a diagram illustrating the state of ink when image recording is completed. Due to the above-described reaction, ink dots are stacked with volatile components remaining in the ink droplets 50 even after recording.

  FIG. 2 is a diagram for explaining an estimation mechanism that reduces the scratch resistance of an image when the above-described ink film is formed during image recording.

  FIG. 2A is a diagram illustrating the ink droplet 50 immediately after the ink containing the surfactant is ejected onto the recording medium.

  Immediately after the ink droplet 50 is formed, the surfactant 52 freely moves in the ink. Here, the surfactant 52 is generally composed of a hydrophilic group and a hydrophobic group. For this reason, when the surfactant 52 moves to a position where it comes into contact with air due to the above-described free movement, the surfactant is oriented in such a direction that the hydrophobic group comes into contact with air and the hydrophilic group comes into contact with the ink droplet. Stop exercise.

  FIG. 2B is a diagram illustrating the ink droplet 50 after a certain amount of time has elapsed after the ink containing the surfactant is ejected onto the recording medium.

  As described above, the surfactant 52 is oriented so that the hydrophobic group is in contact with air and the hydrophilic group is in contact with the ink droplet. In this state, pigment precipitation and viscosity increase occur, and the ink film 51 is formed. Here, for the sake of simplicity, a state in which the hydrophobic group of the surfactant 52 penetrates the ink film 51 and comes into contact with air is illustrated, but in reality, the orientation is not clearly defined as illustrated.

  FIG. 2C shows a subsequent scan at a position close to the ink droplet 50a after the ink droplet 50a formed by the previous ejection shown in FIGS. 2A and 2B is fixed on the recording medium 3. FIG. It is a figure which shows the mode of the image surface at the time of forming the ink droplet 50b by.

  In the same manner as the ink droplet 50a ejected earlier, the surfactant 52 is oriented so that the hydrophobic group is in contact with air and the hydrophilic group is in contact with the ink droplet. Thus, the ink film 51 is formed.

  Here, the ink droplet 50b formed by the subsequent ejection is formed so as to cover a part of the ink droplet 50a formed by the previous ejection. Accordingly, a part of the ink droplet 50a formed by the previous ejection is covered by the ink droplet 50b and is not exposed on the image surface.

  Therefore, one of the surfactants contained in the previous ink droplet is a surfactant 52a distributed at a position exposed on the image surface, and the other is a surfactant 52b distributed at a position not exposed on the image surface. is there.

  Furthermore, since the surfactant 52b distributed at a position where the ink 50a formed by the previous ejection is not exposed to the image surface is inhibited from moving by the ink film 51, it cannot be exposed to the image surface.

  Here, it is known that the amount of the surfactant distributed on the image surface affects the value of the dynamic friction coefficient. Specifically, when the amount of the surfactant distributed on the image surface is large, the hydrophobicity on the image surface becomes strong. For this reason, the interaction with the object in contact with the image surface is reduced, and the dynamic friction coefficient is thereby reduced. This decrease in the coefficient of dynamic friction occurs particularly remarkably when the surfactant is a fluorine-based surfactant or a silicon-based surfactant.

  For the above reasons, when an image is formed as shown in FIG. 2C, a surfactant 52b that cannot be exposed on the surface of the image is generated in the ink droplets 50a formed by the previous ejection. Therefore, for example, when using an ink containing a small amount of surfactant, the amount of surfactant exposed on the image surface is less than expected, and the dynamic friction coefficient of the image may increase accordingly. is there. Thus, when the dynamic friction coefficient is high, there is a possibility that the scratch resistance of the image is lowered.

  The present invention has been made in view of the above problems, and performs recording while suppressing a decrease in scratch resistance due to a high dynamic friction coefficient due to a decrease in the amount of surfactant exposed on the image surface. It is the purpose.

  Accordingly, the present invention provides a recording head and a recording medium that eject a plurality of inks including at least a first ink containing at least a pigment and a surfactant, and a second ink containing at least a pigment and a surfactant. Ink ejection to each of a small area corresponding to a plurality of pixels in the unit area for ejecting ink to the unit area on the recording medium while scanning the upper side a plurality of times in the scanning direction. An image processing apparatus for generating recording data for determining the first image data for determining whether or not to eject the first ink for each of the plurality of small areas in the unit area; and the unit area Acquisition means for acquiring the second image data for determining ejection or non-ejection of the second ink for each of the plurality of small regions in the plurality of small regions; Corresponding to each of the plurality of scans from a plurality of first and second mask patterns each having a print permission pixel and a non-print permission pixel, and the first and second image data. Generating means for generating a plurality of first and second recording data used for recording in each of them, and arranged adjacent to each other arranged in one mask pattern of the plurality of second mask patterns The number of the print permitting pixels in the unit when each of the print permitting pixel group composed of the plurality of record permitting pixels and the record permitting pixels not adjacent to the other record permitting pixels is set as one unit. Of the plurality of first mask patterns is larger than an average of the number of the print permitting pixels in the unit arranged in one mask pattern of the plurality of first mask patterns. The dynamic friction coefficient in the image recorded according to the plurality of recording data generated from the second image data based on the plurality of recordings generated from the first image data based on the plurality of first mask patterns. Greater than the dynamic friction coefficient in the image recorded according to the data, the generating means generates the plurality of first recording data from the first image data based on the plurality of first mask patterns; and The plurality of second recording data is generated from the second image data based on the plurality of second mask patterns.

  According to the image processing apparatus of the present invention, it is possible to perform recording while suppressing a decrease in scratch resistance due to a high dynamic friction coefficient due to a decrease in the amount of surfactant exposed on the image surface.

It is a figure for demonstrating the process in which an ink film is formed. It is a figure for demonstrating the presumed mechanism in which abrasion resistance falls. 1 is a perspective view of an image recording apparatus according to an embodiment. 1 is a side view of an image recording apparatus according to an embodiment. FIG. 2 is a schematic diagram of a recording head according to an embodiment. It is a figure for demonstrating the general multipass recording method. It is a schematic diagram of the mask pattern applied with a general multipass printing method. It is a block diagram which shows the structure of the recording control system in embodiment. It is a figure for demonstrating the presumed mechanism in which abrasion resistance does not fall. It is a figure for demonstrating the presumed mechanism which suppresses a abrasion-resistant fall. It is a figure for demonstrating the definition of the dot connection degree in embodiment. It is a figure for demonstrating the measuring method of the dynamic friction coefficient in embodiment. It is a figure for demonstrating the evaluation method of the abrasion resistance in embodiment. It is a figure for demonstrating the multipass recording system which concerns on embodiment. It is a figure for demonstrating the unit of the recording permissible pixel in embodiment. It is a figure for demonstrating the determination area | region of the mask pattern in embodiment. It is a figure which shows the mask pattern applied in embodiment. It is a block diagram which shows the process of the data in embodiment. It is a figure which shows the mask pattern applied in embodiment. It is a figure for demonstrating the dynamic surface tension of the ink used by embodiment. 1 is a perspective view of an image recording apparatus according to an embodiment.

(First embodiment)
A first embodiment of the present invention will be described in detail below with reference to the drawings.

  FIG. 3 is a perspective view partially showing an internal configuration of the image recording apparatus 1000 according to the first embodiment of the present invention. FIG. 4 is a side view partially showing an internal configuration of the image recording apparatus 1000 according to the first embodiment of the present invention.

  A platen 2 is disposed inside the image recording apparatus 1000, and a plurality of suction holes 34 are formed in the platen 2 in order to prevent the recording medium 3 from adsorbing and floating. The suction hole 34 is connected to a duct, and a suction fan 36 is disposed at the lower part of the duct. The suction fan 36 operates to suck the recording medium 3 to the platen 2.

  The carriage 6 is supported by a main rail 5 installed extending in the paper width direction, and is configured to reciprocate in the X direction (scanning direction). The carriage 6 is equipped with an ink jet recording head 7 which will be described later. The recording head 7 can employ various recording methods such as a thermal jet method using a heating element and a piezo method using a piezoelectric element. The carriage motor 8 is a driving source for moving the carriage 6 in the X direction, and the rotational driving force is transmitted to the carriage 6 by the belt 9.

  The recording medium 3 is fed by being unwound from a medium 23 wound in a roll shape. The recording medium 3 is conveyed on the platen 2 in the Y direction (conveying direction) intersecting the X direction. The recording medium 3 is nipped between the pinch roller 16 and the conveyance roller 11 at the tip, and is conveyed when the conveyance roller 11 is driven. The recording medium 3 is sandwiched between a roller 31 and a discharge roller 32 downstream of the platen 2 in the Y direction, and the recording medium 3 is wound around a winding roller 24 via a turn roller 33.

  FIG. 4 shows a recording head used in this embodiment.

  In the recording head 7, four ejection port arrays 22K, 22C, 22M, and 22Y that eject black (K), cyan (C), magenta (M), and yellow (Y) inks are arranged in parallel in the X direction. It is constituted by. Each of these ejection port arrays 22K, 22C, 22M, and 22Y is configured by arranging 1440 ejection ports 30 that eject ink in the Y direction (arrangement direction) at a density of 1200 dpi. In this embodiment, the amount of ink ejected from one ejection port 30 at a time is about 4.5 ng.

  These ejection port arrays 22K, 22C, 22M, and 22Y are connected to ink tanks (not shown) that store the corresponding ink, respectively, and ink is supplied. Note that the recording head 7 and the ink tank used in the present embodiment may be configured integrally, or may be configured such that each can be separated.

(Ink composition)
The ink used in this embodiment will be described in detail below.

  Hereinafter, “parts” and “%” are based on mass unless otherwise specified.

-Preparation of cyan ink (1) Preparation of dispersion First, using benzyl acrylate and methacrylic acid as raw materials, an AB type block polymer having an acid value of 250 and a number average molecular weight of 3000 is prepared by a conventional method and neutralized with an aqueous potassium hydroxide solution. And diluted with ion-exchanged water to prepare a homogeneous 50% polymer aqueous solution.

  200 g of the above polymer solution, C.I. I. 100 g of CI Pigment Blue 15: 3 and 700 g of ion-exchanged water are mixed and mechanically stirred for a predetermined time, and then a non-dispersed material containing coarse particles is removed by centrifugation to obtain a cyan dispersion.

(2) Preparation of ink Ink preparation uses the above-mentioned cyan dispersion liquid, and the following components are added thereto to obtain a predetermined concentration. These components are sufficiently mixed and stirred, and then pressure filtered through a micro filter (manufactured by Fujifilm) having a pore size of 2.5 μm to prepare a pigment ink having a pigment concentration of 2 mass%.
Cyan dispersion 20 parts Glycerin 10 parts Diethylene glycol 10 parts Acrylic resin Jonkrill J-683 (manufactured by Johnson Polymer Co., Ltd.) 2 parts Fluorosurfactant Zonyl FSO-100 (manufactured by DuPont) 0.03 part ion-exchanged water remaining Amount ・ Magenta ink preparation (1) Preparation of dispersion First, using benzyl acrylate and methacrylic acid as raw materials, an AB type block polymer having an acid value of 300 and a number average molecular weight of 2500 is prepared by a conventional method. Mix and dilute with ion exchange water to make a homogeneous 50% aqueous polymer solution.

  100 g of the polymer solution, C.I. I. 100 g of Pigment Red 122 and 800 g of ion-exchanged water are mixed and mechanically stirred for a predetermined time, and then a non-dispersed material containing coarse particles is removed by centrifugation to obtain a magenta dispersion.

(2) Preparation of ink Ink preparation uses the above-mentioned magenta dispersion, and the following components are added to this to obtain a predetermined concentration. Then, these components are sufficiently mixed and stirred, and then pressure-filtered with a micro filter (manufactured by Fuji Film) having a pore size of 2.5 μm to prepare a pigment ink having a pigment concentration of 4%.
Magenta dispersion 40 parts Glycerin 10 parts Diethylene glycol 10 parts Acrylic resin Joncrill J-683 (manufactured by Johnson Polymer Co., Ltd.) 2 parts Fluorosurfactant Zonyl FSO-100 (manufactured by DuPont) 0.05 part ion-exchanged water remaining Amount ・ Preparation of yellow ink (1) Preparation of dispersion First, anionic polymer P-1 [styrene / butyl acrylate / acrylic acid copolymer (polymerization ratio (weight ratio) = 30/40/30) acid value 202 , Weight average molecular weight 6500]. This is neutralized with an aqueous potassium hydroxide solution and diluted with ion-exchanged water to produce a homogeneous 10% by mass polymer aqueous solution.

  300 g of the polymer solution, C.I. I. 100 g of Pigment Yellow 74 and 600 g of ion-exchanged water are mixed and mechanically stirred for a predetermined time, and then a non-dispersed material containing coarse particles is removed by a centrifugal separation process to obtain a yellow dispersion.

(2) Preparation of ink The following components were mixed, sufficiently stirred and dissolved / dispersed, followed by pressure filtration with a micro filter (manufactured by Fuji Film Co., Ltd.) having a pore size of 1.0 μm. A pigment ink was prepared.
40 parts of the above-mentioned yellow dispersion Fluorosurfactant Zonyl FSO-100 (manufactured by DuPont) 0.025 parts glycerin 9 parts ethylene glycol 10 parts ion-exchanged water remaining-Preparation of black ink (1) Preparation of dispersion First The anionic polymer P-1 was neutralized with an aqueous potassium hydroxide solution and diluted with ion-exchanged water to prepare a homogeneous 10% by mass polymer aqueous solution.

  After mixing 600 g of the polymer solution, 100 g of carbon black, and 300 g of ion-exchanged water and mechanically stirring for a predetermined time, the non-dispersed material containing coarse particles is removed by centrifugation to remove the black dispersion liquid. To do.

(2) Preparation of ink Using the pigment dispersion obtained by the above method, components having the following composition ratios were mixed and sufficiently stirred, and then a micro filter (manufactured by Fuji Film) having a pore size of 2.5 μm was used. The mixture was filtered under pressure to prepare a pigment ink having a pigment concentration of 5% by mass.
Black dispersion 50.0 parts Glycerin 10.0 parts Triethylene glycol 1000 10.0 parts Acrylic resin Joncrill J-683 (manufactured by Johnson Polymer) 2 parts Fluorosurfactant Zonyl FSO-100 (manufactured by DuPont) ) 0.055 parts Ion-exchanged water remaining amount Ink that has landed on the surface of the recording medium if the surface tension in the liquid phase of the ink is high when ink having low permeability or non-permeability is used. The image is deteriorated by aggregating and fixing without spreading and spreading. In particular, when an ink having a surface tension of more than 30 mN / m is used for a recording medium having low ink permeability, the image quality is significantly lowered. Therefore, the surface tension of each ink is preferably 30 mN / m or less.

  In addition, each ink has a surface tension that is as close as possible to each other so as to make the ejection characteristics from the ink ejection port, such as the ejection amount and ejection speed, and the permeability on the surface of the recording medium as close as possible. It is preferable to do. More specifically, it is preferable that the surface tensions of the plurality of inks are aligned in a range of ± 5 mN / m.

  For these reasons, the respective inks used in this embodiment are adjusted so that the surface tension becomes a value from 25 mN / m to 30 mN / m in the same temperature environment.

  The above-described surface tension adjustment is performed by adding different amounts of surfactants to a plurality of inks. In the present embodiment, Zonyl FSO-100 (manufactured by DuPont), which is classified as a fluorosurfactant among nonionic surfactants, is used as the surfactant. Zonyl FSO-100 is added by 0.03% by mass for cyan ink, 0.05% by mass for magenta ink, 0.025% by mass for yellow ink, and 0.055% by mass for black ink. As a result, the surface tension of each ink is adjusted to a value from 25 mN / m to 30 mN / m.

  In the present embodiment, a fluorosurfactant is used to adjust the surface tension. However, even if a surfactant other than the fluorosurfactant is used, the surface tension can be adjusted.

  Further, the surface tension in the liquid phase of each ink in the present embodiment was measured using a Bubble Pressure Tesiometer (trade name) manufactured by KRUSS. If the surface tension in the liquid phase of the ink can be measured, not only the above-described measuring instrument but also various measuring instruments can be used.

  The recording medium used in this embodiment will be described in detail below.

  As described above, the lower the ink permeability to the recording medium, the easier it is to form an ink layer on the surface of the recording medium. Becomes prominent.

  As an example of such a recording medium having low ink permeability, there is coated paper in which the surface of plain paper is coated with a white pigment or the like.

In this embodiment, an OK top coat + (made by Oji Paper Co., Ltd., basis weight 157.0 g / m ² ), which is one of the coated papers described above, is used as the recording medium 3.

  In this embodiment, various methods can be applied as a method for evaluating the ink permeability of the recording medium. As an example of the method, JAPAN TAPPI paper pulp test method No. Evaluation of ink permeability to the recording medium by the Bristow method described in “Liquid absorbency test method for paper and paperboard” 51 is described below.

  A predetermined amount of ink is injected into a holding container having an opening slit of a predetermined size, and is contacted with a recording medium processed into a strip shape and wound around a disk through the slit, and the position of the holding container is fixed. Then, the area (length) of the ink band transferred to the recording medium by rotating the disk is measured.

A transfer amount (ml · m ⁻² ) per unit area per unit area can be calculated from the area of the ink band.

When the transfer amount with respect to the ink was measured by the Bristow method for a general printing coated paper, the transfer amount per second was 20 ml · m ⁻² or less, and in particular, the OK top coat + was more than 10 ml · m ^−2. A slightly smaller value was obtained. In the present embodiment, recording can also be performed on a recording medium with low ink permeability such as this printing coated paper.

On the other hand, the amount of transfer per second by the Bristow method for plain paper is often 30 ml · m ⁻² or more, and generally shows high ink permeability. However, even plain paper has a transfer amount of less than 20 ml · m ⁻² per second by the Bristow method. Although such a recording medium is plain paper, it can be said that it is a recording medium with low ink permeability. In the present embodiment, the present invention can be applied to such a recording medium with low ink permeability, even if it is not printed coated paper. Further, it can be used for a recording medium such as cloth or leather and having a low ink permeability. Further, a non-permeable recording medium such as a sheet formed of vinyl chloride having no ink permeability can also be used in this embodiment.

  In the present embodiment, an image is formed according to a multipass printing method. The multipass recording method will be described in detail below.

  FIG. 6 is a diagram showing a general multi-pass printing method used when printing is performed in a unit area on a printing medium by four printing scans.

  FIG. 7 is a diagram for explaining a mask pattern applied in each printing scan in the above-described multipass printing method.

  Each ejection port 30 provided in the ejection port array 22 that ejects ink is divided into four recording groups 201, 202, 203, and 204 along the sub-scanning direction.

  Each mask pattern 221, 222, 223, and 224 is configured by arranging a plurality of print permitting pixels that determine ejection of a plurality of inks and non-printing allowance pixels that determine non-ejection of ink. In FIG. 7, black portions represent print permitting pixels, and white portions represent non-print permit pixels. In the print permitting pixel, when the input image data is image data representing ink discharge, it is set as print data for discharging ink. In the non-recording permissible pixel, even when image data representing ink ejection is input, the recording data does not eject ink.

  Note that the print permitting pixels in the mask patterns 221, 222, 223, and 224 are arranged at positions that are different from each other and that have a relationship in which the respective logical sums are all pixels.

  Hereinafter, an example in which an image having a duty of 100% (hereinafter also referred to as a solid image) is formed on a recording medium will be described.

  In the first recording scan, ink is ejected from the recording group 201 to the area 211 on the recording medium 3 according to the mask pattern 221. As a result, ink is ejected onto the recording medium at the position indicated by black in FIG.

  Next, the recording medium 3 is conveyed relative to the recording head 7 by a distance of L / 4 from the upstream side in the Y direction to the downstream side.

  After this, a second recording scan is performed. In the second recording scan, ink is ejected from the recording group 202 to the mask pattern 222 to the area 211 on the recording medium, and from the recording group 203 to the mask pattern 221 to the area 212. As a result of the second recording scan, an image as shown in black in FIG. 6B is formed on the recording medium 3.

  Thereafter, the recording scan of the recording head 7 and the relative conveyance of the recording medium 3 are repeated alternately. As a result, after the fourth recording scan, the ink ejection is completed in the small area corresponding to all the pixels in the area D 211 of the recording medium 3, and a solid image is formed.

  In the following description, an area corresponding to a pixel in a recording medium may be simply referred to as “pixel”.

  FIG. 8 is a block diagram showing a schematic configuration of a recording control system in the present embodiment.

  A host computer 301 serving as an image input unit transmits RGB multi-valued image data stored in various storage media such as a hard disk to an image processing unit in the image recording apparatus 1000.

  The image processing unit includes an MPU 302, an ASIC 303, and the like which will be described later. The multi-value image data can also be received from an external image input device such as a scanner or a digital camera connected to the host computer 301. The image processing unit performs image processing, which will be described later, on the input multi-valued image data and converts it to binary image data. As a result, binary image data that is recording data for ejecting a plurality of types of ink from the recording head 7 is generated.

  The image recording apparatus 1000 that is an image output unit records an image by applying ink to the recording medium 3 based on the binary image data of the ink generated by the image processing unit. The image recording apparatus 1000 is controlled by an MPU (Micro Processor Unit) 302 according to a program recorded in the ROM 304. The RAM 305 functions as a work area and a temporary data storage area for the MPU 302. The MPU 302 controls the driving system 308 of the carriage 6, the transport driving system 309 of the recording medium 3, the recovery driving system 310 of the recording head 7, and the driving system 311 of the recording head 7 via the ASIC 303.

  The print buffer 306 temporarily stores recording data converted into a format that can be transferred to the recording head 7.

  The mask buffer 307 temporarily stores a mask pattern to be applied when recording data is transferred to the recording head 7. A plurality of mask patterns used for multi-pass printing are prepared in the ROM 304, and the corresponding mask patterns are read from the ROM 304 and stored in the mask buffer 307 during actual printing.

  In the present embodiment, the image processing unit is described as being present in the image recording apparatus 1000, but the host computer 301 may be provided with the image processing unit.

  In this embodiment, the degree of connectivity of dots formed on a recording medium by a single scan with an ink having a relatively low surfactant concentration is determined on the recording medium by an ink having a relatively high surfactant concentration. By making it larger than the connectivity of dots formed by one scan at a time, the dynamic friction coefficient of the image is suppressed from becoming lower than a predetermined threshold value, and the scratch resistance of the image is improved.

  First, an estimation mechanism in which the dynamic friction coefficient is higher than the threshold value even when recording with the first ink having a relatively high surfactant concentration at a relatively low dot connectivity is described below. .

  FIG. 9 is a diagram showing an image surface formed when the first ink is recorded with a relatively low dot connectivity. 9A shows an image surface formed when ink is ejected by the first scanning on the recording medium, and FIG. 9A ejects ink by the second scanning on the recording medium. It is a figure which respectively shows the image surface formed when performing.

  Here, as an example, the case where the concentration of the surfactant in the first ink is about twice the concentration of the surfactant in the ink shown in FIG. 2 will be described.

  When the first ink is ejected onto the recording medium 3 by the first scan and the ink droplet 60a is fixed, as shown in FIG. 9A, the ink droplet shown in FIG. The amount of the surfactant 62 is twice as much as the amount of the surfactant distributed on the gas-liquid interface. When the ink droplet 60b is fixed by ejecting ink onto the recording medium by the second scanning, as shown in FIG. 9 (b), the ink droplet 60b is moved in the same manner as in FIG. 2 (c). The ink droplet 60a is formed so as to cover a part of the surface of the ink droplet 60a. Therefore, the surfactant 62b distributed at the position covered with the ink droplet 60a of the ink droplet 60b cannot move due to the presence of the ink film 61, and therefore cannot be exposed to the image surface.

  However, since the first ink contains a large amount of the surfactant per droplet, a sufficient dynamic friction coefficient can be obtained only with the surfactant contained in the ink droplet 60b formed by the subsequent scanning. it can. For this reason, the image has sufficient scratch resistance even when the first ink is recorded with the dot connectivity being reduced.

  Next, an estimation mechanism that suppresses a decrease in the dynamic friction coefficient when recording with relatively high dot connectivity in the second ink having a relatively low surfactant concentration will be described below.

  FIG. 10 is a diagram illustrating an image surface formed when the above-described second ink is recorded with a relatively high dot connectivity. 10A shows the image surface immediately after ink is ejected onto the recording medium, and FIG. 10B shows that a certain amount of time has elapsed after ink is ejected onto the recording medium, and the ink droplets are fixed. It is a figure which shows the image surface at the time of doing, respectively.

  Here, as an example, a case where the concentration of the surfactant in the second ink is the same as the concentration of the surfactant in the ink shown in FIG. 2 will be described.

  As shown in FIG. 10A, the second ink is ejected to a position where five ink droplets 70a, 70b, 70c, 70d, and 70e formed by the same scanning on the recording medium 3 are in contact with each other. Is done. When ejected in this manner, the five ink droplets move in such a direction as to gather together and try to form one large ink droplet. At this stage, since no ink film is formed, the surfactant 72 freely moves across a plurality of ink droplets. Then, when moving to the gas-liquid boundary surface in contact with air, the hydrophobic group is oriented in the direction in which the hydrophobic group is in contact with the air and the ink droplet, and free movement is no longer performed.

  When a certain amount of time elapses after the ink is ejected, the ink is fixed on the recording medium 3 as shown in FIG. As described above, the five ink droplets 70a, 70b, 70c, 70d, and 70e shown in FIG. 10A gather together to form one large ink droplet 70. Further, an ink film 71 is formed on the gas-liquid interface between the large ink droplet 70 and air by the above-described precipitation of pigment and increase in viscosity.

  On the other hand, all the surfactants 72 are distributed on the gas-liquid interface of the large ink droplets 70. Therefore, even though the surfactant concentration of the second ink and the surfactant concentration of the ink shown in FIG. 2 are the same, the interface distributed on the image surface than the image shown in FIG. The amount of active agent can be increased. Thereby, the fall of a dynamic friction coefficient can be suppressed. Therefore, with respect to the second ink, it is possible to record an image in which the scratch resistance is suppressed by performing recording while increasing the degree of dot connection.

  Note that the dot connectivity in this embodiment is evaluated by the number of dots formed at consecutive positions on the recording medium by the same scanning.

  FIG. 11 is a diagram for explaining dot connectivity in the present embodiment.

  In this embodiment, the dot connection degree is obtained by measuring the number of connected dots that form a large dot among a plurality of dots ejected in a certain area, and calculating the average of the number of connected dots in the area. Therefore, it can be evaluated numerically.

For example, since each of the nine dots shown in FIG. 11A is formed at a position separated from each other by one scan, there are no dots connected in the region of 6 pixels × 6 pixels. Therefore, the number of connections of all dots in the area is 1. Therefore, it is evaluated that the dot connection number, which is the average of the dot connection numbers in the region, is 1. Also, the nine dots shown in FIG. 11B are formed at positions where they contact each other in one scan. After being applied on the recording medium, they are connected to form a large dot. It is evaluated that the number of connected large dots is nine. Further, since there is no dot other than the large dot in the 6 pixel × 6 pixel region, it is evaluated that the dot connection degree that is the average of the number of connected dots in the region is 9.

  A method for verifying the effect of suppressing the decrease in the dynamic friction coefficient due to the control of the dot connectivity and the effect of improving the scratch resistance associated therewith will be described below.

  First, the test method for measuring the dynamic friction coefficient is described in detail below.

  FIG. 12 schematically shows a state in which the dynamic friction coefficient of the image surface is measured using a dynamic friction coefficient measuring device.

  An arbitrary load can be applied in the vertical direction using the vertical load 114 by fixing the sample 116 on the operation stage 115 in FIG. By moving the operation stage 115 at a constant speed, the dynamic friction force load cell 118 acting between the sample 116 and the acrylic ball 113 can be detected, and the dynamic friction force during operation can be recorded by the recording unit 119.

  For example, using a load variable friction and wear tester (“HEIDON: Tribogear HHS1200” manufactured by Shinto Chemical Co., Ltd.), it is possible to measure friction with a constant load in accordance with the horizontal method of JIS P8147. In the horizontal method of JIS P8147, a method for measuring a coefficient of dynamic friction generated between paper placed on a horizontal base and paper fixed below a block-like weight is defined. In this rule, the area of the contact portion is (60 mm ± 5 mm) × (60 mm ± 5 mm), the pressure is 2.2 kPa ± 0.6 kPa, and the relative speed between the contact portion and the table is 20 mm / second ± 2 mm / second. It prescribes.

  In the image surface friction coefficient measurement test performed in the present embodiment, portions different from the JIS standard will be described with reference to FIG. First, the printed sample 116 is fixed to the operation stage 115 so that the image surface is in contact with the acrylic sphere 113. Next, an acrylic sphere to which a vertical load 73 of 50 g is applied from above is brought into perpendicular contact with the sample 116, and the sample 116 is moved together with the operating stage 115 at a speed of 2 mm / sec to generate scratches. At this time, the force applied to fix the sample 116 is removed by the balance mechanism 117. The dynamic friction coefficient of the image surface forming the image of the sample 116 is measured from the ratio between the horizontal force during movement and the force of vertical load.

  In the present embodiment, the dynamic friction coefficient of the image surface by each of the cyan ink, the magenta ink, and the black ink was measured according to the measurement method described above. The recording medium used was an OK topcoat + with low ink permeability. In addition, a sample 116 was prepared by ejecting the same color ink so that the total of 100% duty was obtained by scanning 6 times with respect to the above-described OK topcoat +. In each of the six scans, a highly dispersive mask pattern was used, and the ink ejection was controlled so that the ink droplets did not contact as much as possible (the dot connectivity was low) in the same scan. Here, a total of three samples 116 corresponding to each of cyan ink, magenta ink, and black ink were created.

  Table 1 shows the dynamic friction coefficient of each sample measured according to the above-described measurement method.

  As can be seen from Table 1, the dynamic friction coefficients in the ink images recorded so that the dot connectivity in each scan is low are 0.781 for cyan ink, 0.661 for magenta ink, and 0.545 for black ink. Met. That is, in each ink used in this embodiment, it was found that the higher the surfactant concentration, the lower the dynamic friction coefficient of the image.

  Next, a test method for evaluating the scratch resistance will be described in detail below.

  FIG. 13 is a diagram showing a test method for evaluating scratch resistance.

  In this embodiment, the scratch resistance is evaluated by the method described in ISO12647-7 Appendix A.

A sample on which the image 112 is recorded on the recording medium 3 is placed on a flat surface without unevenness, and four sheets of Sylbon paper 111 (OZU CORPORATION TOKYO “cleaning wiper daspar”) are placed on the surface of the image. A weight 110 (160 g / cm ² ) is placed thereon, and the sylbon paper 111 is slid in the direction of the arrow in FIG. 13 at a constant speed (about 15 cm / s) so that the weight 110 does not fall. The above procedure is performed 30 seconds, 60 seconds, and 90 seconds after the recording of the image 112 is completed, and the degree of disturbance of the surface of the image 112 on the recording medium 3 and the degree of retransfer to the Sylbon paper 111 are determined. evaluated. Evaluation of scratch resistance after image formation and evaluation criteria are shown below.

(Evaluation: ◎)
There is almost no change in the area where the image 112 is formed (hereinafter referred to as an image forming area). In addition, a color material is hardly dragged in a region on the sample where the image 112 is not formed (hereinafter referred to as paper white), and the color material is hardly transferred to the Sylbon paper 111.

(Evaluation: ○)
Before and after the test, some shavings are visible in the image forming area. As for paper white, several lines of 5 mm or less can be seen by dragging the color material along the direction in which the Sylbon paper 111 is dragged from the boundary between the image forming area and the paper white to the paper white. In addition, the transfer of the color material to the Sylbon paper 111 is very small, but it can be understood that the color material is transferred if observed closely.

(Evaluation: △)
Before and after the test, you can see the shavings in the image forming area. As for paper white, a large number of lines of 5 mm or more can be seen by dragging the color material along the direction in which the Sylbon paper 111 is dragged from the boundary between the image forming area and the paper white to the paper white. The border with paper white can be recognized. As for the transfer of the color material to the sillbon paper 111, the same color material as the amount of the color material remaining in the image forming area after the sillbon paper 111 is dragged is transferred to the sillbon paper 111.

  In this embodiment, the same sample as that used when measuring the dynamic friction coefficient was used, and the scratch resistance of each sample was evaluated according to the above-described evaluation method. Table 2 shows the results of the scratch resistance of each sample evaluated. Here, the scratch resistance of the image was evaluated in each state 30 seconds, 60 seconds, and 90 seconds after the image was formed.

  As shown in Table 2, in each ink used in the present embodiment, it was found that the higher the dynamic friction coefficient when recording with a lower dot connectivity, the lower the scratch resistance. It has also been clarified that the scratch resistance decreases as the time from the image formation to the evaluation of the scratch resistance becomes shorter.

  Further, the change in scratch resistance by controlling the dot connectivity will be described in detail below.

  As can be seen from Table 2, when recording is performed with a low dot connectivity, there is a case where the magenta ink and the cyan ink having relatively high dynamic friction coefficients have low scratch resistance. Therefore, in the present embodiment, for magenta ink and cyan ink, printing is performed with a high dot connectivity.

  Note that, as shown in Table 2, in the cyan ink having a higher dynamic friction coefficient than the magenta ink, the scratch resistance is more remarkably reduced. For this reason, the dot connection degree of magenta ink is set higher than the dot connection degree of black ink (the dot connection degree is medium), and an image is recorded. In addition, the dot connection degree of cyan ink is set higher than that of magenta ink (dot connection degree is high), and an image is recorded. The scratch resistance of these images was evaluated according to the evaluation method described above.

  In addition, here, the graininess in each image was similarly evaluated. Regarding the evaluation of the graininess, an image in which the graininess was hardly visually recognized was evaluated as ◎, and an image with a slight noticeable graininess was evaluated as ◯.

  Table 3 shows the evaluation results of the scratch resistance and graininess in each image.

  As for the black ink, since the concentration of the surfactant is high, the amount of the surfactant distributed on the image surface is relatively large even when recording is performed with a low dot connectivity. Accordingly, since the dynamic friction coefficient becomes relatively small, as can be seen from Table 3, the scratch resistance is evaluated after 30 seconds from the image formation even when the dot connectivity is reduced. Then, it was evaluated ◎.

  On the other hand, as described above, since the cyan ink and the magenta ink have a lower surfactant concentration than the black ink, when the dot connectivity is lowered and recording is performed, the dynamic friction coefficient does not decrease to a value indicating sufficient scratch resistance. However, since the amount of surfactant distributed on the image surface can be increased by recording with a high or medium dot connectivity, the dynamic friction coefficient can be reduced. As a result, as shown in Table 3, the scratch resistance of cyan ink and magenta ink can be evaluated as ◯ after 30 seconds from image formation, and evaluated as ◎ after 60 seconds from image formation.

  From this result, it is possible to experimentally confirm the effectiveness of increasing the dot connectivity of ink that has a relatively large dynamic friction coefficient when recording with a low dot connectivity.

  On the other hand, when recording with a large dot connectivity, an image is formed by large dots in which a plurality of continuous ink droplets are gathered, so the graininess is conspicuous in the image obtained compared to the case where the dot connectivity is reduced. End up. However, when the dot connectivity is increased, the reduction in graininess does not lead to a significant decrease in image quality. For this reason, in this embodiment, when both the graininess suppression and the scratch resistance cannot be improved, the scratch resistance is considered as a more preferential parameter.

  In view of the above points, in this embodiment, recording is performed by setting the dot connectivity of black ink, magenta ink, and cyan ink to low, medium, and high, respectively. By controlling in this way, it is possible to record an image excellent in both graininess suppression and scratch resistance with respect to the black ink. Further, with magenta ink and cyan ink, the graininess is somewhat conspicuous, but an image having excellent scratch resistance can be recorded.

  FIG. 14 is a diagram for explaining the multi-pass printing method in the present embodiment.

  In the present embodiment, a method is employed in which an image is completed for the unit area 80 on the recording medium by six recording scans. Among the recording heads 7 used in the present embodiment, 1440 discharge ports arranged in the discharge port arrays 22K, 22C, and 22M that discharge black ink, cyan ink, and magenta ink are the recording groups A1 to A6, the recording groups, respectively. Divided into six recording groups, each having a length d, of groups B1 to B6 and recording groups C1 to C6. Here, the number of ejection openings included in one recording group is 240.

  Here, the length in the Y direction of the unit area 80 on the recording medium 3 corresponds to the amount of relative movement of the recording head 7 and the recording medium 3 in the Y direction, and the divided ejection port array 22K. , 22C, and 22M, which corresponds to the length d of one recording group. The length of the unit area 80 in the X direction corresponds to the length of the recording medium 3 in the X direction.

  First, when the unit area 80 of the recording medium 3 is at the position 80a, the recording head 7 is scanned in the X direction, and at least the recording group A1 of the ejection port array 22K and the recording group B1 of the ejection port array 22C with respect to the unit area 80. The respective inks are ejected from the ejection ports belonging to the recording group C1 of the ejection port array 22M in accordance with a mask pattern described later. Thereafter, the recording medium 3 is transported in the Y direction by a distance corresponding to the distance d, and the unit area 80 is moved to the position 80b. After this conveyance, at least the ejection port while scanning the recording head 7 in the X direction with respect to the unit area 80 on the recording medium 3 on which the ink has been ejected from the ejection ports previously belonging to the recording groups A1, B1, and C1. Ink is ejected from the ejection ports belonging to the recording group A2 in the row 22K, the recording group B2 in the ejection port row 22C, and the recording group C2 in the ejection port row 22M. Thereafter, while the recording medium 3 having such a distance corresponding to the distance d is being conveyed, the recording head 7 is scanned a total of six times over the unit area 80 on the recording medium 3 to complete the image.

  In the present embodiment, a print permission pixel unit (a print permission pixel group including a plurality of print permission pixels in the mask pattern and a print permission pixel that is not adjacent to other print permission pixels as one unit ( In the following, the average of the number of recording allowable pixels in the “unit” is also controlled. The mask pattern used for black ink discharge, the mask pattern used for cyan ink discharge, and the mask pattern used for magenta ink discharge each have a different average of the number of print-allowable pixels in the unit described above, thereby Control dot connectivity. The control method will be described in detail below.

  FIG. 15 is a diagram for describing the definition of the unit of the print permission pixel and the number of print permission pixels in the unit of the print permission pixel in the present embodiment.

  As described above, the print permission pixel group includes a plurality of print permission pixels arranged at adjacent positions. For example, FIG. 15A shows a recording-allowed pixel group having a square shape, which is composed of four pixels of 2 pixels × 2 pixels. In this case, the number of recording allowable pixels in the unit is 4.

  Further, in the present embodiment, even if a print permission pixel is not adjacent to any other print permission pixel, it is referred to as a unit of print permission pixel. FIG. 15B shows a print permitting pixel having no adjacent record permitting pixel. In this case, the number of recording allowable pixels in the unit is 1.

  In addition, a plurality of print permitting pixels that are biased and continued in a specific direction are also a print permitting pixel group in the present embodiment, and are not limited to the isotropic shape as shown in FIG. FIG. 15C shows an L-shaped print permitting pixel group that is biased and continuous in a specific direction. In this case, the number of recording allowable pixels in the unit is seven.

  Further, the continuous print permitting pixels in this embodiment include not only the print permitting pixels continuous in the X direction and the Y direction but also the print permitting pixels continuous in the oblique direction. That is, there is a possibility that a total of eight print permitting pixels, two in the X direction, two in the Y direction, and four in the oblique direction, are adjacent to one print permitting pixel. FIG. 15D shows a print permission pixel group adjacent in the oblique direction. In this case, the number of recording allowable pixels in the unit is five.

  FIG. 16 is a diagram for explaining a method of calculating the average number of print permitting pixels within the unit of print permitting pixels in the present embodiment.

  In the present embodiment, for the sake of simplicity, the average of the number of recording allowable pixels in the unit of the recording allowable pixels in the determination area having the predetermined number of pixels in the unit area 80 is calculated, and the value is calculated as the recording allowable in the unit area. Used as the average of the number of pixels allowed for recording within the unit of pixels. FIG. 16 exemplifies a region composed of 25 pixels of 5 pixels in the X direction and 5 pixels in the Y direction as the mask pattern region corresponding to the determination region in the unit region. In the present embodiment, the average number of print-allowable pixels in a unit is calculated by calculating the number of units included in the mask pattern area corresponding to the determination area, and each unit in the mask pattern area corresponding to the determination area. The number of recording allowable pixels is calculated. Further, the sum of the number of print permitting pixels in each unit is calculated, and a value obtained by dividing the sum by the number of units is set as an average of the number of print permitting pixels in the unit in each mask pattern.

  For example, there are no print permitting pixels adjacent to each other in the mask pattern area corresponding to the determination area shown in FIG. In other words, in accordance with the above definition, a total of eight units having one recordable pixel in the unit are arranged. Therefore, the average number of print permitting pixels in a unit in the mask pattern shown in FIG. 16A is 8 (= 1 × 8), which is the sum of the number of print permitting pixels in each unit, as the number of units. The value divided by 8 is 1.

  On the other hand, in the mask pattern area corresponding to the determination area shown in FIG. 16B, four print permitting pixels adjacent to each other constitute the print permitting pixel units T1 and T2. Therefore, the average number of print permitting pixels in a unit in the mask pattern shown in FIG. 16B is 8 (= 4 × 2), which is the sum of the number of print permitting pixels in each unit, as the number of units. The value obtained by dividing by 2 is 4.

  The mask pattern applied in this embodiment will be described in detail below.

  FIG. 17A is a diagram showing a mask pattern applied to the ejection port array 22K that ejects black ink according to the present embodiment. FIG. 17B is a diagram showing a mask pattern applied to the ejection port array 22M that ejects magenta ink according to the present embodiment. FIG. 17C is a diagram showing a mask pattern applied to the ejection port array 22C that ejects cyan ink according to the present embodiment.

  Mask patterns from mask pattern 121 to mask pattern 126 are applied to the print groups from print group A1 to print group A6 of discharge port array 22K that discharges black ink, respectively. Note that FIG. 17 shows a mask pattern composed of 25 pixels for the sake of simplicity, but this indicates a repeating unit of the mask pattern. Actually, each mask pattern shown in the figure is repeatedly used as it advances in the X direction and the Y direction.

  Here, in each of the mask patterns from the mask pattern 121 to the mask pattern 126, substantially the same number of print permitting pixels are arranged. Note that the print permitting pixels of the mask patterns 121 to 126 are arranged at positions different from each other, and the logical sum of the print permitting pixels is all pixels.

  By applying such a mask pattern, the black ink can be ejected by almost the same amount in the first to sixth recording scans. Furthermore, black ink can be applied to all the ejectable positions in the unit area on the recording medium by the first to sixth recording scans.

  Note that these points are the same for the mask patterns 131 to 136 that are applied to the recording groups C1 to C6 of the ejection port array 22M that ejects magenta ink. is there. Further, the above-mentioned point is the same for the mask patterns 141 to 146 applied to the respective print groups from the print group B1 to the print group B6 of the discharge port array 22C that discharges cyan ink. is there.

  Here, among the mask patterns 121 to 126 corresponding to the black ink, the average number of print allowable pixels in the unit calculated according to the above-described definition in the mask patterns 121, 122, 123, 125, and 126 is 1. In addition, the average number of print permitting pixels in the unit in the mask pattern 124 is 1.25.

  On the other hand, among the mask patterns 131 to 136 corresponding to magenta ink, the average number of print allowable pixels in the unit calculated according to the above definition in the mask patterns 131, 131, 134, 135, and 136 is 2. In addition, the average number of print permitting pixels in the unit in the mask pattern 132 is 2.5. In this way, each of the mask patterns 131 to 136 corresponding to magenta ink has each print permission so that the average number of print permission pixels in the unit is larger than any of the mask patterns 121 to 126 corresponding to black ink. Pixels are arranged.

  Further, among the mask patterns 141 to 146 corresponding to the cyan ink, the average number of print allowable pixels in the unit calculated according to the above definition in the mask patterns 141, 142, 143, 145, and 146 is 4. In addition, the average number of print permitting pixels in the unit in the mask pattern 144 is five. In this way, each of the mask patterns 141 to 146 corresponding to the cyan ink has each print permission so that the average number of print permission pixels in the unit is larger than any of the mask patterns 131 to 136 corresponding to the magenta ink. Pixels are arranged.

  By applying the mask pattern described above, the ejection of ink is controlled so that the degree of dot connectivity ejected onto the recording medium in one scan is always higher in the order of cyan ink, magenta ink, and black ink. Can do.

  FIG. 18 is a flowchart for explaining the process of image processing in the image processing unit of this embodiment.

  In the color conversion processing step S31, the RGB multi-value data acquired from the host computer 301 serving as the image input unit is converted into multi-value data corresponding to the color of the ink used for recording.

  Next, in the binarization processing step S32, each of the multi-value data corresponding to the ink color converted in the color conversion processing step S31 is developed into binary image data according to the stored pattern. By this binarization processing, binary data for ejecting each of black ink, cyan ink, magenta ink, and yellow ink is generated.

  In the ink determination step S33, based on the binary data corresponding to each ink generated in the binarization processing step S32, it is determined which of the three ink groups is classified according to the surfactant concentration. . Different mask pattern processing is set for each ink group.

  First, the binary data corresponding to the black ink belonging to the ink group having the highest dynamic friction coefficient when the surfactant concentration is high and the dot connectivity is low is recorded in the dot connectivity low mask pattern setting process S34. Proceed to Here, the mask pattern shown in FIG. 17A is set as the binary data corresponding to the black ink.

  Next, binary data corresponding to magenta ink belonging to an ink group in which the surfactant concentration is medium and the dynamic friction coefficient when recording with a low dot connectivity is medium is medium dot connectivity. The process proceeds to mask pattern setting process S35. Here, the mask pattern shown in FIG. 17B is set for binary data corresponding to magenta ink.

  Further, binary data corresponding to cyan ink and yellow ink belonging to the ink group having the lowest dynamic friction coefficient when recording with a low surfactant concentration and a low dot connection degree is set as a mask pattern with a high dot connection degree. It progresses to process S36. Here, the mask pattern shown in FIG. 17C is set for binary data corresponding to cyan ink.

  Further, since the concentration of the surfactant contained in the yellow ink is lower than that of the cyan ink, in the dot connectivity high mask pattern setting process S36, binary data corresponding to the yellow ink is also shown in FIG. A mask pattern is set. Since yellow ink has higher lightness than other inks, the granularity is not so noticeable in terms of human visual characteristics even when recording is performed with a high dot connectivity. Therefore, regarding the yellow ink, even when the surfactant concentration is high, even if the dot connectivity is increased, the image quality is hardly affected.

  Further, in the mask pattern processing step S37, the respective binary data are set in the dot connectivity low mask pattern setting processing step S34, the medium dot connectivity mask pattern setting processing step S35 and the dot connectivity high mask pattern setting processing step S36. Mask pattern processing is performed using the mask pattern, and print data distributed to a plurality of scans is generated for each ink.

  Based on the generated recording data, ink is ejected from the recording head 7 of the image recording apparatus 1000 to form an image.

  According to the above configuration, it is possible to increase the dot connectivity of magenta ink and cyan ink, in which the surfactant coefficient is relatively low and the coefficient of dynamic friction increases when recording is performed with a low dot connectivity. it can. For this reason, it is possible to suppress a reduction in the scratch resistance of the magenta ink image and the cyan ink image. On the other hand, even when the surfactant concentration is sufficiently high and the dot connectivity is low, the cyan ink having a sufficiently low dynamic friction coefficient keeps the dot connectivity low. Therefore, it is possible to obtain an image excellent in both suppression of graininess and improvement in scratch resistance.

(Second Embodiment)
In the first embodiment described above, a mode has been described in which ink with a high dynamic friction coefficient is ejected in every scan when recording is performed with a low dot connectivity.

  On the other hand, this embodiment describes a mode in which, among a plurality of scans with respect to a unit region, ink is not ejected that increases the dynamic friction coefficient when printing is performed with a low dot connectivity in a specific scan.

  Note that description of the same parts as those of the first embodiment described above will be omitted.

  In the present embodiment, ink ejection is controlled so that cyan ink having the highest dynamic friction coefficient when recording is performed with a low dot connectivity is not ejected in the first and sixth scans.

  FIG. 19 is a diagram showing a mask pattern applied to the ejection port array 22C that ejects cyan ink according to the present embodiment.

  In the present embodiment, no print permitting pixels are arranged in the mask patterns 151 and 156 applied to the print groups B1 and B6 in the cyan ink ejection port arrays 22C corresponding to the first and sixth scans, respectively.

  On the other hand, the mask patterns 152 to 155 applied to the print groups B2 to B5 in the cyan ink ejection port arrays 22C corresponding to the second to fifth scans respectively include mask patterns 142 shown in FIG. More print permitting pixels than .about.145 are arranged. Further, the print permission pixels of the mask patterns 152 to 155 are located at different positions, and are arranged at complementary positions so that the logical sum of the print permission pixels becomes all pixels.

  Furthermore, the average number of print-allowable pixels in each unit is 6 for the mask patterns 142, 143, and 144 and 7 for the mask pattern 145. Therefore, in any case, the mask patterns 131 to 136 shown in FIG. 15B can be made higher than the average number of recording allowable pixels in the unit.

  According to the above configuration, cyan ink is not ejected in the first and sixth scans. On the other hand, since the amount of ink discharged in one scan in the second to fifth scans can be increased compared to the case where ink is ejected in all scans, the dot connectivity can be increased. it can. Accordingly, it is possible to further improve the scratch resistance in an image of cyan ink, which is an ink having the highest dynamic friction coefficient when recording with a high dot connectivity.

(Third embodiment)
In the first and second embodiments, a case has been described in which recording is performed using a plurality of inks having a high dynamic friction coefficient when recording is performed with a lower dot connectivity as the surfactant concentration is lower.

  On the other hand, in the present embodiment, a case will be described in which recording is performed using a plurality of inks having different dynamic friction coefficients even when the surfactant concentration is the same.

  The description of the same parts as those in the first and second embodiments described above will be omitted.

(Ink composition)
The ink used in this embodiment will be described in detail below.

  Each ink dispersion and ink preparation method are the same as those of the ink of the first embodiment. Further, the same yellow ink as that used in the first embodiment is used.

  Table 4 shows the compositions of cyan ink, magenta ink, and black ink used in this embodiment.

  In each ink used in the first and second embodiments, fluorinated surfactant Zonyl FSO-100 (manufactured by DuPont) was added as a surfactant. On the other hand, as shown in Table 4, in this embodiment, acetylenol EH (manufactured by Kawaken Fine Chemicals), which is a nonionic surfactant, is used as a surfactant. The same amount of acetylenol EH was added to each ink.

  Samples of each ink shown in Table 4 were prepared in the same manner as in the first embodiment, and the dynamic friction coefficient of each sample was measured according to the measurement method described in the first embodiment. Furthermore, the scratch resistance of each sample was evaluated according to the evaluation method described in the first embodiment using the same sample.

  Table 5 shows the dynamic friction coefficient and scratch resistance of each ink sample.

  As can be seen from Table 5, the inks used in this embodiment are printed with magenta ink, black ink, and cyan ink in order of decreasing dot connectivity, although the concentrations of the surfactants contained are the same. The coefficient of dynamic friction during the process increased. This is presumed to be because the affinity between the surfactant and the pigment or resin contained in the magenta ink is stronger than the affinity between the surfactant or the pigment or resin contained in the black ink or cyan ink. The That is, when the affinity between the magenta ink pigment or resin and the surfactant is relatively strong, a surfactant that adsorbs to the pigment or the like during free movement in the ink droplet is generated. Since such a surfactant is stabilized when adsorbed with a pigment or the like, it remains inside the ink droplet after fixing and cannot be distributed at a position exposed on the image surface. Therefore, it is considered that the dynamic friction coefficient is increased as in the magenta ink used in the present embodiment.

  As described above, each ink used in the present embodiment has a strong affinity between the surfactant and the pigment contained in the order of magenta ink, black ink, and cyan ink, and therefore the dynamic friction coefficient also increases in this order. Therefore, as shown in Table 5, the scratch resistance decreases in the order of magenta ink, black ink, and cyan ink.

  In view of the above points, in this embodiment, cyan ink has low dot connectivity, black ink has medium dot connectivity, and magenta ink has high dot connectivity for recording. Suppresses the decline. That is, for binary data corresponding to cyan ink, a mask pattern having a relatively small average number of print allowable pixels in the unit shown in FIG. 17A is set and printing is performed. Further, for binary data corresponding to black ink, printing is performed by setting a mask pattern in which the average number of print allowable pixels in the unit shown in FIG. 17B is medium. Further, for binary data corresponding to magenta ink, a mask pattern having a relatively large average number of print-allowable pixels in the unit shown in FIG. 17C is set and printing is performed. Table 6 shows the evaluation results of the scratch resistance and graininess in the image recorded as described above.

  As can be seen from Table 6, since the affinity between the contained pigment and the surfactant is relatively strong, the dynamic friction coefficient is relatively high when recording is performed with a low dot connectivity. As for black ink, it is possible to improve the scratch resistance of an image by relatively increasing the dot connectivity.

  According to the above configuration, magenta ink and cyan ink dot linking have a high dynamic friction coefficient when recording with a low dot linking degree due to the relatively strong affinity between the contained pigment and the surfactant. The degree can be increased. Thereby, it is possible to suppress a decrease in the scratch resistance of the image. On the other hand, cyan ink with a sufficiently low dynamic coefficient of friction, even when recording with a sufficiently low affinity for pigments and surfactants and a low dot connectivity, keeps the dot connectivity low and granular. An image excellent in both suppression of feeling and improvement in scratch resistance can be recorded.

(Fourth embodiment)
In the present embodiment, a case where ink having relatively high dynamic surface tension and ink having relatively low dynamic surface tension is used will be described.

  The description of the same parts as those in the first to third embodiments described above will be omitted.

  When the dynamic surface tension of the ink immediately after being applied on the recording medium is relatively low, the surface tension is lowered in a short time, so that the surfactant moves remarkably. For this reason, the surfactant distributed on the surface of the ink droplet is relatively increased. As a result, in the case of ink having a relatively low dynamic surface tension, the dynamic friction coefficient on the image surface is small even when recording is performed with a low dot connectivity, and an image with excellent scratch resistance can be recorded. On the other hand, when the dynamic surface tension of the ink is relatively high, the movement of the surfactant is hindered. As a result, the dynamic friction coefficient of the image surface increases, and the scratch resistance of the image decreases. By utilizing this, in this embodiment, the dot connectivity is controlled according to the dynamic surface tension of the ink.

  The method for measuring the dynamic surface tension of the ink and the results will be described in detail below.

  In this embodiment, the dynamic surface tension of the ink is measured by the maximum bubble pressure method. The maximum bubble pressure method is a method for determining the surface tension from the maximum pressure by measuring the maximum pressure required to release bubbles formed at the tip of a probe (capillary tube) immersed in the liquid to be measured. . In addition, the lifetime is determined from the time when the bubble is formed at the tip of the probe in the maximum bubble pressure method, from the point when a new bubble surface is formed after the bubble leaves the tip, and at the time of the maximum bubble pressure (the radius of curvature of the bubble). And the time until the radius of the probe tip becomes equal).

  In this embodiment, the dynamic surface tension of the plurality of inks was measured by the above-described maximum bubble pressure method using a Bubble Pressure Tesiometer model: BP2 (manufactured by KRUSS). In this embodiment, the same ink as that used in the first and second embodiments is used.

  FIG. 20 is a diagram showing the result of measuring the dynamic surface tension at 25 ° C. of each ink used in the present embodiment in a plurality of lifetimes from the lifetime of 10 msec to the lifetime of 1000 msec.

  As can be seen from FIG. 20, the dynamic surface tension of the black ink is smaller than the dynamic surface tension of the cyan ink and magenta ink regardless of the lifetime. In addition, the dynamic surface tension of cyan ink and magenta ink is substantially the same in the lifetime of the first several tens of milliseconds, but after that, the cyan ink has a larger dynamic surface tension than the magenta ink. Further, when about 1000 msec elapses after the ink droplet is formed on the recording medium, the interface of the ink droplet is stabilized, so that the dynamic surface tension of each ink at the lifetime of 1000 msec becomes almost the same value as the static surface tension.

  In view of the above points, in the present embodiment, the black ink having the lowest dynamic surface tension has the mask pattern shown in FIG. 17A, and the magenta ink having the middle dynamic surface tension has the mask shown in FIG. 17B. A cyan ink having the highest dynamic surface tension is recorded by applying the mask pattern shown in FIG.

  According to the above configuration, the dynamic friction coefficient can be estimated only by measuring the dynamic surface tension without measuring the dynamic friction coefficient, the surfactant content, and the like.

  Magenta ink and cyan ink increase the dot connection of the magenta ink and cyan ink, which increase the coefficient of dynamic friction when recording with a low dot connection due to the relatively strong affinity between the contained pigment and surfactant. It is possible to suppress a decrease in scratch resistance. On the other hand, cyan ink with a sufficiently low dynamic coefficient of friction, even when recording with a sufficiently low affinity for pigments and surfactants and a low dot connectivity, keeps the dot connectivity low and granular. An image excellent in both suppression of feeling and improvement in scratch resistance can be recorded.

  Here, although the embodiment has been described in which the dynamic surface tension at a plurality of lifetimes between the lifetime of 10 msec and the lifetime of 1000 msec is measured and used as an index of the dynamic friction coefficient, other embodiments are also possible. Here, as a result of the inventors conducting similar experiments on various inks, it has been found that the dynamic surface tension at the lifetime of 100 msec has the greatest influence on the dynamic friction coefficient. Therefore, only the dynamic surface tension of each ink at a lifetime of 100 msec may be measured and used as an index of the dynamic friction coefficient.

  In addition, this embodiment can be applied particularly effectively when the ink contains a plurality of surfactants or when the affinity between the surfactant and the pigment or resin is high.

(Fifth embodiment)
In the first to fourth embodiments, a method for controlling the dot connectivity of a plurality of inks in a so-called multi-pass printing apparatus that prints a unit area on a printing medium by a plurality of printing scans. Was described.

  On the other hand, in this embodiment, a plurality of recording heads corresponding to the respective inks having a length corresponding to the entire width direction of the recording medium are used. In such a recording apparatus that performs recording by performing a relative recording scan of the recording head and the recording medium once, the ejection order of a plurality of inks is controlled.

  The description of the same parts as those in the first to third embodiments described above will be omitted.

  FIG. 21 is a side view partially showing an internal configuration of the recording apparatus according to the present embodiment.

  Each of the six recording heads 600, 601, 602, 603, 604, and 605 has a predetermined number of ejection ports (not shown) that eject cyan ink, magenta ink, yellow ink, and black ink for each recording head in the Z direction. Is arranged. Therefore, six discharge port arrays for discharging a certain ink are arranged. The length of the ejection port array in the Z direction is equal to or longer than the length of the recording medium 3 in the Z direction so that recording can be performed on the entire area of the recording medium 3 in the Z direction.

  The conveyance belt 400 is a belt that conveys the recording medium 3. Further, the conveyor belt 400 is rotated in the W direction intersecting the Z direction by the feeding unit 401 and the discharging unit 402.

  The recording medium 3 is fed by the feeding unit 401 and is conveyed in the W direction by the conveying belt 400.

  In the present embodiment, the mask pattern shown in FIG. 17A is applied to each of the six ejection port arrays that eject black ink shown in FIG. 21, and the six ejection port arrays that eject magenta ink shown in FIG. The mask pattern shown in FIG. That is, the mask patterns 121 to 126 shown in FIG. 17A are applied to the discharge port arrays for discharging the black ink in the recording heads 600 to 605, and the Y direction in FIG. 17A is in the Z direction shown in FIG. Apply to correspond. Similarly, mask patterns 131 to 136 shown in FIG. 17B are applied to the ejection port arrays for ejecting magenta ink in the recording heads 600 to 605 shown in FIG. Further, mask patterns 141 to 146 shown in FIG. 17C are applied to the ejection port arrays for ejecting cyan ink in the recording heads 600 to 605 shown in FIG.

  According to the above configuration, even in a recording apparatus that performs recording in one recording scan with respect to a unit area on a recording medium, the dynamic friction coefficient when recording is performed with a low dot connectivity. Accordingly, the dot connectivity can be controlled. Thereby, it is possible to improve the scratch resistance of the image while suppressing the graininess of the image as much as possible.

  Further, since an image can be completed by one recording scan, it is possible to reduce the recording time.

  Although the length in the Z direction of the ejection port array used in this embodiment is a length corresponding to the width of the recording medium, the length can be increased by arranging a plurality of short ejection port arrays in the Z direction. It is also possible to use a so-called connecting head as a recording head.

  In each of the embodiments described above, a nonionic surfactant is used as a surfactant. However, an ink containing an anionic surfactant, a cationic surfactant, or an amphoteric surfactant is used. Even if it exists, the effect by this invention can be acquired.

  Examples of the anionic activator that exhibits the effects of the present invention particularly remarkably include fatty acid salts, alkyl sulfate esters, alkyl aryl sulfonates, alkyl diaryl ether disulfonates, and dialkyl sulfosuccinates. The same applies to alkyl phosphates, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate ester salts, glycerol borate fatty acid esters, and the like.

  Further, examples of the nonionic active agent that exhibits the effects of the present invention particularly remarkably include polyoxyethylene alkyl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, and glycerin fatty acid ester. The same applies to polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, fluorine-based, silicon-based and the like.

  In addition, examples of the cationic activator that exhibits the effects of the present invention particularly remarkably include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, and alkylimidazolium salts.

  In addition, examples of the zwitterionic activator that exhibits the effects of the present invention particularly remarkably include alkylbetaines, alkylamine oxides, and phosphadylcholines. In addition, the silicon-based surfactant here includes silicon oil. Examples of silicone oil include FZ-2104, FZ-2130, FZ-2191 (manufactured by Toray Dow Corning), KF-615A (manufactured by Shin-Etsu Chemical), TSF4452 (manufactured by Momentive Performance Materials Japan). and so on.

  In each of the above embodiments, the form in which the solvent is evaporated only by heating has been described, but other forms are also possible. For example, in order to accelerate | stimulate evaporation of a solvent, the form which ventilates in addition to a heating may be sufficient. When such air blowing is performed, the evaporation of water in the solvent at the gas-liquid boundary surface occurs remarkably, so that the time until the ink film is formed is shortened. As a result, the amount of surfactant that remains in the ink droplets and cannot be exposed on the surface of the image is increased as compared with the case where no air is blown, thereby increasing the dynamic friction coefficient of the image. Therefore, it is preferable to increase the dot connection degree when such air blowing is performed as compared with the case where air is not blown.

  Further, although each embodiment has been described using colored ink, it is not necessary that the ink is colored. For example, when a colorless ink and a colored ink are used, the colorless ink is an ink having a relatively low dynamic surface tension, and the colored ink is an ink having a relatively high dynamic surface tension. Recording can be performed by increasing the dot connectivity of colorless ink and decreasing the dot connectivity of colored ink.

  Moreover, although each embodiment described the form which divides | segments into three ink groups according to a dynamic friction coefficient, and applies the mask pattern of an appropriate dot connection degree for every ink group, implementation by another form is also possible. For example, the ink may be divided into two ink groups according to the dynamic friction coefficient. Further, it may be classified into four or more ink groups according to the dynamic friction coefficient.

  In the first to fourth embodiments described above, the dot connectivity is controlled using a mask pattern. However, the present invention can be sufficiently applied as long as it has means capable of recording for each pixel, and the means is not limited to the mask pattern. For example, the recording data for each pixel is sequentially distributed to a plurality of buffers corresponding to a plurality of recording scans by a swing circuit provided in the recording apparatus, and it is determined in which recording scan the recording of each pixel is recorded. You may do it. According to the above-described swing circuit, it is possible to control how many times the ink is ejected to each pixel. That is, if a plurality of adjacent pixels are sprinkled in the same buffer so as to be ejected in the same scan, a plurality of ink droplets can be applied to adjacent positions on the recording medium without using a mask pattern. it can. As described above, the effect of the present invention can be obtained even in a form in which the dot connectivity is controlled using the swing circuit.

3 Recording Medium 7 Recording Head 22 Discharge Port Array 51, 61, 71 Ink Film 52, 62, 72 Surfactant 80 Unit Area

Claims (15)

A recording head for discharging a plurality of inks including at least a first ink containing at least a pigment and a surfactant, and a second ink containing at least a pigment and a surfactant, and a recording medium, in the scanning direction. Recording data for determining ink ejection to each of a small area corresponding to a plurality of pixels in the unit area for ejecting ink to the unit area on the recording medium while relatively scanning a plurality of times. An image processing device to generate,
First image data that determines ejection or non-ejection of the first ink for each of the plurality of small areas in the unit area, and the second ink for each of the plurality of small areas in the unit area Acquisition means for acquiring second image data for determining ejection or non-ejection of
Corresponding to each of the plurality of scans, the plurality of first and second mask patterns in which print permitting pixels and non-printing allowance pixels are arranged, and the first and second image data, respectively. Generating means for generating a plurality of first and second recording data used for recording in each of the scans;
A print permitting pixel group composed of a plurality of print permitting pixels arranged adjacent to each other and arranged in one mask pattern of the plurality of second mask patterns, and recording not adjacent to other record permitting pixels In the case where each of the permissible pixels is defined as one unit, the average number of the permissible recording pixels in the unit is within the unit arranged in one mask pattern of the plurality of first mask patterns. More than the average of the number of pixels allowed for recording,
A dynamic friction coefficient in an image recorded according to the plurality of recording data generated from the second image data based on the plurality of first mask patterns is calculated based on the first mask pattern based on the plurality of first mask patterns. Greater than the dynamic friction coefficient in the image recorded according to the plurality of recording data generated from the image data,
The generation unit generates the plurality of first recording data from the first image data based on the plurality of first mask patterns, and the first generation data based on the plurality of second mask patterns. An image processing apparatus that generates the plurality of second recording data from two image data.   The dynamic friction coefficients in the image recorded according to the plurality of first recording data and the image recorded according to the plurality of second recording data are calculated from the second image data based on the plurality of first mask patterns. The image processing apparatus according to claim 1, wherein the image processing apparatus is smaller than a dynamic friction coefficient in an image recorded according to the plurality of generated recording data.   The amount of the surfactant distributed on the image surface in each of the image recorded according to the plurality of first recording data and the image recorded according to the plurality of second recording data is greater than a predetermined amount, respectively. The amount of the surfactant distributed on the image surface in the image recorded according to the plurality of recording data generated from the second image data based on the plurality of first mask patterns is smaller than the predetermined amount. The image processing apparatus according to claim 1, wherein:   The average of the number of print permitting pixels in the unit arranged in each of the plurality of first mask patterns is the average of the recording in the unit arranged in each of the plurality of second mask patterns. The image processing apparatus according to claim 1, wherein the number is larger than an average of the number of allowable pixels.   5. The image processing apparatus according to claim 1, wherein a concentration of the surfactant in the second ink is lower than a concentration of the surfactant in the first ink. 6. .   2. The dynamic surface tension of the second ink at 25 ° C. and a predetermined lifetime is higher than the dynamic surface tension of the first ink at 25 ° C. and the predetermined lifetime. 6. The image processing apparatus according to any one of items 1 to 5.   The image processing apparatus according to claim 6, wherein the predetermined lifetime is 100 ms.   The image processing apparatus according to claim 6, wherein the first and second dynamic surface tensions are measured by a maximum bubble pressure method. 9. The recording medium according to claim 1, wherein the recording medium has an ink transfer amount of 20 ml · m ⁻² or less per second by the Bristow method for the first and second inks. The image processing apparatus according to item.   The number of print permission pixels arranged in each of the plurality of second mask patterns is substantially equal to the number of print permission pixels arranged in each of the plurality of first mask patterns. The image processing apparatus according to claim 1.   11. The image processing apparatus according to claim 1, wherein at least one mask pattern among the plurality of second mask patterns is not provided with the print-allowable pixels. The plurality of inks further includes a third ink containing at least a pigment and a surfactant,
The acquisition means further acquires third image data for determining ejection of the third ink for each of the plurality of small regions in the unit region,
A dynamic friction coefficient in an image recorded according to the plurality of recording data generated from the third image data based on the plurality of first mask patterns is calculated based on the second mask based on the plurality of first mask patterns. Greater than the dynamic friction coefficient in the image recorded according to the plurality of recording data generated from the image data,
The generation unit corresponds to each of the plurality of scans, and generates the plurality of times from the third image data based on a plurality of third mask patterns in which print permission pixels and non-print permission pixels are arranged. A plurality of third recording data used for recording in each of the scans;
An average of the number of print permitting pixels in the unit arranged in one mask pattern of the plurality of third mask patterns is arranged in one mask pattern of the plurality of second mask patterns. 12. The image processing apparatus according to claim 1, wherein the image processing apparatus is larger than an average of the number of the print allowable pixels in the unit. A recording head that ejects a plurality of inks including at least a first ink containing at least a pigment and a surfactant; and a second ink containing at least a pigment and a surfactant;
Scanning means for scanning the recording head and the recording medium a plurality of times relatively in the scanning direction;
Control for controlling ejection of the first and second inks so that the first and second inks are ejected from the recording head to a unit area on the recording medium with scanning by the scanning unit. And an image recording apparatus comprising:
The dynamic friction coefficient in an image recorded so that the degree of dot connection in the second ink dot is smaller than a predetermined threshold value is set so that the degree of dot connection in the first ink dot is smaller than the predetermined threshold value. Larger than the dynamic friction coefficient in the image recorded in
The control means is configured such that the dot connectivity of the second ink dots formed on the unit area by the predetermined scanning is the first ink dots formed on the unit area by the predetermined scanning. An image recording apparatus, wherein the ejection of the first and second inks is controlled so as to be larger than a dot connection degree. A recording head that ejects a plurality of inks including at least a first ink containing at least a pigment and a surfactant; and a second ink containing at least a pigment and a surfactant;
Scanning means for scanning the recording head and the recording medium a plurality of times relatively in the scanning direction;
Control for controlling ejection of the first and second inks so that the first and second inks are ejected from the recording head to a unit area on the recording medium with scanning by the scanning unit. And an image recording apparatus comprising:
The amount of the surfactant exposed on the surface of the image recorded so that the dot connectivity in the second ink dot is smaller than a predetermined threshold is determined by the dot connectivity in the first ink dot. Less than the amount of the surfactant exposed on the surface of the recorded image to be smaller than a predetermined threshold,
The control means is configured such that the dot connectivity of the second ink dots formed on the unit area by the predetermined scanning is the first ink dots formed on the unit area by the predetermined scanning. An image recording apparatus, wherein the ejection of the first and second inks is controlled so as to be larger than a dot connection degree. Relative in the scanning direction is a recording head that discharges a plurality of inks including at least a first ink containing at least a pigment and a surfactant, and a second ink containing at least a pigment and a surfactant, and the recording medium. The first and second inks are ejected so that the first and second inks are ejected from the recording head to the unit area on the recording medium with the scanning. An image recording method for controlling and recording,
The dynamic friction coefficient in an image recorded so that the degree of dot connection in the second ink dot is smaller than a predetermined threshold value is set so that the degree of dot connection in the first ink dot is smaller than the predetermined threshold value. Larger than the dynamic friction coefficient in the image recorded in
The dot connectivity in the second ink dots formed on the unit area in the predetermined scan is greater than the dot connectivity in the first ink dots formed on the unit area in the predetermined scan. And controlling the ejection of the first and second inks so as to be larger.

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