JP2017013357A - Image processing device, image processing method and image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing device for recording in which generation of density irregularity is suppressed, which is caused by beading of an ink drop imparted after an ink layer formed previously.SOLUTION: Recorded data for determining discharge or non-discharge of an ink to each pixel region in charge of a plurality of pixels in a unit region are generated in each scanning, and a first ink having high dynamic surface tension and low evaporativity, and a second ink having low dynamic surface tension and high evaporativity are controlled so as to be discharged onto adjacent pixel regions in the same scanning.SELECTED DRAWING: Figure 10

Description

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

  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. An ink jet recording method for forming a film is known.

  In the above-described recording apparatus, unevenness due to so-called beading in which a plurality of ink droplets ejected at close positions in the same recording scan on the recording medium come into contact with each other may occur and image quality may deteriorate. It is known. In order to suppress the occurrence of this beading, generally, print permitting pixels permitting ink ejection in a mask pattern corresponding to each print scan used for distributing image data corresponding to a certain ink to a plurality of print scans. Are arranged so as not to be adjacent to each other. Further, in order that different inks do not cause beading in the same print scan, the print permitting pixels are adjacent to each other in the mask pattern corresponding to one ink and the mask pattern corresponding to another ink corresponding to the same print scan. It is also known to arrange so that it does not.

  On the other hand, in recent years, printed materials for various purposes have been created by the in-jet recording method, and various types of inks and recording media have been used accordingly. In Patent Document 1, an ink containing a resin emulsion and a water-soluble organic solvent and a hardly water-absorbing recording medium are used. When the ink is landed on the recording medium, heat is applied to the ink, A method of fixing by forming a resin emulsion into a film is disclosed.

JP 2005-220352 A

  However, in the case where recording is performed using the recording medium with poor water absorption as described above, depending on the ink used, the ink droplets applied later are attracted to the ink droplets applied earlier, and thus It has been found that there is a possibility that unevenness due to this pulling may occur in the obtained image.

  This problem will be described in detail below.

  FIG. 1 is a diagram schematically showing a fixing process of ink droplets 52 when ink is ejected by a recording scan on a hardly water-absorbing recording medium 3 and then further ink is ejected by a subsequent recording scan. Here, a case where ink is ejected to the pixel region 50b in the previous scan and ink is ejected to the pixel regions 50a and 50c in the subsequent scan is described.

  As shown in FIG. 1A, when ink is ejected in the previous scan and ink droplets 52 are applied to the pixel regions 50a and 50c adjacent to the pixel region 50b in which the ink layer 51 is already formed on the recording medium. As shown in FIG. 1B, the ink droplet 52 and the ink layer 51 come into contact after landing on the recording medium.

The force F _ab attracted toward the ink layer 51 occurs in the ink droplet 52 landed on the recording medium by contact with the ink layer 51. Here, when the recording medium has poor water absorption, it takes a relatively long time for the ink droplet 52 to be fixed on the recording medium. Become.

For this reason, under the influence of the force _Fab , the ink droplet 52 flows toward the ink layer 51 before being fixed on the recording medium. As a result, as shown in FIG. 1C, an ink layer 52 ′ is formed at a position shifted from the pixel regions 50a and 50c where the ink droplets 52 should originally be fixed toward the pixel region 50b.

  When the ink is fixed as shown in FIG. 1C, density unevenness occurs in the finally formed image. Specifically, there is a possibility that an image having a density lower than the density originally desired is recorded in the pixel areas 50a and 50c, and an image having a density higher than the density originally desired is recorded in the pixel area 50b.

  The present invention has been made in view of the above problems, and generates recording data for performing recording while suppressing the occurrence of density unevenness due to beading of ink droplets applied later to an ink layer formed earlier. It is intended to do.

  Therefore, the present invention ejects a plurality of inks including at least a first ink containing a pigment, a resin emulsion, and a water-soluble organic solvent, and a second ink containing the pigment, the resin emulsion, and the water-soluble organic solvent. In the unit area in each of the N scans for discharging ink while performing N (N ≧ 2) relative scans in the scanning direction with respect to the unit area on the recording medium of the recording head An image processing apparatus that generates recording data for determining whether ink is ejected or not ejected to each of pixel regions corresponding to a plurality of pixels, the image processing device performing each of the plurality of pixel regions in the unit region in the N scans. First image data for determining ejection or non-ejection of the first ink, and the plurality of pixel areas in the unit area in the N scans. The second image data for determining whether the second ink is ejected or not ejected for each of them, and the recording that corresponds to each of the N scans and that determines the ink ejection allowance. Based on the N first mask patterns in which allowed pixels and non-printing allowed pixels that determine non-permission of ink ejection are arranged, and the first image data obtained by the obtaining unit, Each of N scans generates N first print data for ejecting the first ink, and corresponds to each of the N scans. Based on the N second mask patterns in which the print permitting pixels are arranged and the second image data acquired by the acquisition unit, the second scan pattern is obtained in each of the N scans. Eject ink Generating means for generating N pieces of second recording data for the second ink, and the second ink operates under conditions of a predetermined life time and a first temperature than the first ink. The surface tension is low and the amount of evaporation under the condition of a predetermined time and the second temperature is larger than that of the first ink, and K (2 of the N first and second mask patterns). ≦ K ≦ N) Regarding the first and second mask patterns respectively corresponding to the scan of the first time, (i) print permitting pixels arranged at positions adjacent to other print permitting pixels in the first mask pattern Is less than about 1/4 times the number of print permitting pixels arranged in the first mask pattern, and (ii) adjacent to other print permitting pixels in the second mask pattern. The number of print permitting pixels arranged at the position to be The number is less than about ¼ times the number of print permitting pixels arranged in the mask pattern, and (iii) is obtained by the logical sum of the print permitting pixels arranged in the first and second mask patterns. The number of print permitting pixels adjacent to other print permitting pixels in the logical sum pattern is greater than approximately half the number of print permitting pixels arranged in the logical sum pattern.

  According to the image processing apparatus, the image processing method, and the image recording apparatus according to the present invention, recording for performing recording while suppressing occurrence of density unevenness due to beading of ink droplets applied later to the previously formed ink layer is performed. Data can be generated.

It is a figure which shows typically the fixing process of an ink drop. 1 is a perspective view of an image recording apparatus applied in an embodiment. It is sectional drawing of the internal mechanism of the image recording apparatus applied in embodiment. It is a schematic diagram of the recording head applied in the embodiment. It is a schematic diagram which shows the recording control system in embodiment. It is a figure for demonstrating a general multipass recording system. It is a schematic diagram of a mask pattern used in a general multi-pass printing method. It is a figure which shows typically the fixing process of the ink droplet in embodiment. It is a figure which shows the process of the data in embodiment. It is a schematic diagram which shows the mask pattern applied in embodiment. It is a schematic diagram which shows the mask pattern applied in embodiment. It is a figure which shows the process of the data in embodiment. It is a schematic diagram which shows the mask pattern applied in embodiment.

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

(First embodiment)
FIG. 2 is a perspective view partially showing an internal configuration of the image recording apparatus 1000 according to the present embodiment. FIG. 3 is a side view partially showing an internal configuration of the image recording apparatus 1000 according to the present embodiment.

  A housing 1 is provided inside the image recording apparatus 1000, and a platen 2 is disposed on the housing 1. A large number of suction holes 34 are formed in the platen 2 in order to prevent the recording medium 3 from adhering to the platen 2 and floating. The suction hole 34 is connected to the duct 4, and a suction fan 36 is disposed below the duct 4, and the suction fan 36 operates to attract the recording medium 3 to the platen 2.

  Further, a carriage 6 that reciprocates in the X direction (scanning direction) is supported on the main rail 5 installed in the longitudinal direction of the housing 1. The carriage 6 is equipped with an ink jet recording head 7. The recording head 7 can apply various ink jet 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 from a roller-shaped sheet feeding medium 23. The recording medium 3 is conveyed on the platen 2 in the Y direction (conveying direction) orthogonal to the X direction. The recording medium 3 is conveyed by the leading end being sandwiched between the pinch roller 16 and the conveying roller 11 and driven by the conveying roller. Further, the recording medium 3 is sandwiched between a roller 31 and a paper 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.

  In the present embodiment, liquid ink is formed by heat from the first heater 25 located at a position facing the platen 2 and the second heater 27 located downstream of the platen 2 in the Y direction and located at the position facing the platen 2. The coloring material contained in the recording medium 3 is fixed on the recording medium 3.

  The first heater 25 is covered with a first heater cover 26, and the second heater 27 is covered with a second heater cover 28. The first heater cover 26 and the second heater cover 28 record the heat of each heater. It functions to efficiently irradiate the surface of the medium and to protect each heater. The first heater 25 is provided to evaporate water contained in the ink and increase the viscosity of the ink droplet. When the ink is ejected from the recording head 7, the recording medium is already heated uniformly. Yes. In the present embodiment, the temperature of the first heater is set to a temperature at which the surface of the recording medium is 60 ° C. Note that the ink does not need to be completely fixed on the recording medium 3 at the stage of receiving heat from the first heater 25, but may be such that the viscosity increases to some extent and the fluidity of the ink on the recording medium 3 decreases. As the heating method of the first heater 25, various methods such as a hot air heater, an infrared heater, and a heat conduction heater that contacts the recording medium can be used, and an infrared heater is particularly preferable.

  Further, the second heater 27 is heated at a temperature higher than that of the first heater 25, and a later-described resin emulsion contained in the ink is formed into a film to fix the ink droplets on the recording medium 3. In this embodiment, the temperature of the recording medium is set to 90 ° C.

  In the present embodiment, the first heater 25 and the second heater 27 are used for heating in two stages. However, the present invention is not limited to this form, and is divided into three or more stages. Thus, the present invention can be applied to either a form in which heating is performed or a form in which heating is performed in only one stage.

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

  The recording head 7 has 11 ejection port arrays 22Y that can eject each of yellow (Y), magenta (M), light magenta (LM), cyan (C), light cyan (LC), and black (Bk) inks. , 22M, 22LM, 22C, 22LC, 22Bk (hereinafter, one of these discharge port arrays is also referred to as a discharge port array 22) arranged in this order in the X direction. . These ejection port arrays 22 are configured by arranging 1280 ejection ports (hereinafter also referred to as nozzles) 30 that eject the respective inks in the Y direction (predetermined direction) at a density of 1200 dpi. In addition, the discharge ports 30 located at positions adjacent to each other in the Y direction are arranged at positions shifted from each other in the X direction. Here, the amount of ink ejected at one time from one ejection port 30 in the present embodiment is about 4.5 ng.

  Each of these ejection port arrays 22 is connected to an ink tank (not shown) that stores the corresponding ink, 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.

  FIG. 5 is a block diagram showing a schematic configuration of a control system in the present embodiment. The main control unit 300 includes a CPU 301 that executes processing operations such as calculation, selection, discrimination, and control, a ROM 302 that stores a control program to be executed by the CPU 301, a RAM 303 that is used as a buffer for recording data, and an input / output Port 304 etc. are provided. The memory 313 stores image data, a mask pattern, ejection failure nozzle data, and the like, which will be described later. The input / output port 304 is connected to drive circuits 305, 306, 307, and 308 such as a conveyance motor (LF motor) 309, a carriage motor (CR motor) 310, the recording head 7, and an actuator in the cutting unit. . Further, the main control unit 300 is connected to a PC 312 which is a host computer via an interface circuit 311.

  In the present embodiment, an image is formed according to a multipass printing method. Hereinafter, a general multi-pass recording method will be described in detail.

  FIG. 6 is a diagram showing a 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 of the ejection ports 30 provided in the ejection port array 22 that ejects ink is divided into four ejection port 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. That is, the print permitting pixel is a pixel that determines the allowance of ink ejection to the corresponding pixel. In the non-recording permissible pixel, even when image data representing ink ejection is input, the recording data does not eject ink. That is, the non-recording permissible pixel is a pixel that determines non-permission of ink ejection with respect to the corresponding pixel.

  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 (recording ratio) of 100% (hereinafter also referred to as a solid image) is formed on a recording medium will be described.

  In the first printing scan (one pass), ink is ejected from the ejection port group 201 to the unit area 211 on the recording medium 3 in accordance with the mask pattern 221. As a result, ink is ejected onto the pixel area 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.

  Thereafter, the second recording scan (two passes) is performed. In the second printing scan, ink is ejected from the ejection port group 202 to the mask pattern 222 for the unit region 211 on the recording medium, and from the ejection port group 203 to the unit region 212 according to the mask pattern 221. 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 printing scan (four passes) is performed, ink ejection is completed in the pixel unit area 211 of the recording medium 3 corresponding to all pixels, and a solid image is formed. Is done.

(Inhibition of ink droplet beading on the ink layer)
In this embodiment, in order to suppress beading of ink droplets with respect to the ink layer previously formed on the recording medium, recording is performed using at least two types of inks whose ink characteristics are controlled. Specifically, the ink A and the ink B having a lower dynamic surface tension than the ink A and a larger evaporation amount (faster evaporation speed) than the ink A are used, and the ink A and the ink B are subjected to the same recording scan. Ink ejection is controlled so as to be applied to adjacent pixel regions.

  In the following description, magenta ink is used as the ink A and light magenta ink is used as the ink B.

  Here, the dynamic surface tension means a surface tension per minute time of a liquid that is in a dynamic state immediately after the interface is formed and in which the surface tension changes depending on time. When two types of ink droplets having different dynamic surface tensions come into contact, the ink having a low dynamic surface tension moves so as to cover the ink having a high dynamic surface tension. This is because the state where the surface tension is high is unstable as the surface energy, so that the liquid moves in the direction of decreasing the surface energy.

  This dynamic surface tension can be measured by using 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 the maximum bubble pressure method, when a bubble is formed at the tip of the probe, from the point when a new bubble surface is formed after the bubble leaves the tip, the maximum bubble pressure (at the bubble radius of curvature and the probe tip) The time until the radius of the part becomes equal is called the life time.

Although the reason will be described later, the ink A and the ink B used in this embodiment have a dynamic time of 5 mN / m or more under the conditions of a lifetime of 5 milliseconds (5 × 10 ⁻³ seconds) and a temperature of 25 ° C. There is preferably a difference in the surface tension.

  FIG. 8 shows adjacent pixel regions in the same recording scan using magenta ink and light magenta ink having a lower dynamic surface tension than magenta ink and a larger evaporation amount than magenta ink (fast evaporation speed). It is a figure for demonstrating the fixing process of the ink at the time of providing those inks. Note that. Here, a case where ink is ejected to the pixel area 56b in the previous scan, magenta ink is ejected to the pixel areas 56a and 56c, and light magenta ink is ejected to the pixel areas 56d and 56e, respectively.

  As shown in FIG. 8A, a magenta ink droplet 54 is applied to the pixel areas 56a and 56c adjacent to the pixel area 56b where the ink layer 53 is formed in the previous scan, and the pixel areas 56a and 56c are further applied. When the light magenta ink droplet 55 is applied to the adjacent pixel regions 56d and 56e, as shown in FIG. 8B, after landing on the recording medium, the magenta ink droplet 54 becomes the ink layer 53 and the light magenta ink. In contact with both ink drops 55.

  Here, since the light magenta ink droplet 55 has a higher evaporation speed than the magenta ink droplet 54, thickening starts at a relatively early stage after landing on the recording medium. Therefore, the light magenta ink droplet 55 is less likely to flow on the recording medium at a relatively early stage.

As described in FIG. 1, the ink droplets 54 by contact with the ink layer 53 occurs force F _ab attracted toward the ink layer 51. However, as shown in FIG. 8B, the ink droplet 54 of magenta ink also has a force F ₁₂ that attracts the ink droplets 54 and 55 to each other due to contact with the ink droplet 55 of light magenta ink having a different dynamic surface tension. Will occur. Force F ₁₂ attracting the mutually becomes stronger the larger the difference between the dynamic surface tension of the magenta ink and light magenta ink.

  As described above, the ink droplet 55 of light magenta ink is evaporated at an early stage, so that the ink droplet 55 hardly flows to the ink droplet 54. On the other hand, since the ink droplet 54 has a higher dynamic surface tension than the ink droplet 55, the ink droplet 54 is less likely to flow toward the ink droplet 55.

In the case shown in FIG. 8B, unlike FIG. 1B, not only the force F _ab that is attracted toward the ink layer 53 but also the force F ₁₂ that attracts the ink droplet 55. Will also occur. Since the ink droplet 55 becomes difficult to flow at an early stage, the force F ₁₂ works to keep the ink droplet 54 away from the ink layer 53. This force F ₁₂ cancels out the force F _ab to some extent, whereby the phenomenon that the ink droplet 54 is attracted toward the ink layer 53 can be suppressed to some extent.

  Therefore, as shown in FIG. 8C, the ink layer 54 ′ can be formed without much deviation from the pixel regions 56a and 56c after the ink is fixed. In addition, since the ink droplet 55 has a high evaporation speed, the ink layer 55 ′ does not deviate so much from the pixel regions 56 d and 56 e.

Here, when the light magenta ink has a smaller evaporation amount than the magenta ink (evaporation speed is slow), the magenta ink droplet 54 is fixed earlier than the light magenta ink droplet 55. Thus, the force F ₁₂ acts so as to approach the ink droplet 54b to be difficult to flow at an early stage of ink droplets 55. Accordingly, since the force acting to cancel the force _Fab acting on the ink droplet 54 is lost, the flow of the ink droplet 54 toward the ink layer 53 cannot be suppressed. Therefore, there is a possibility that uneven density due to beading of the ink droplets 54 on the ink layer 53 may occur.

  Further, when the dynamic surface tension of light magenta ink is higher than that of magenta ink, the flow of ink droplets 54 to the ink layer 53 side can be suppressed, but the glossiness of the obtained image is lowered. There is a fear. As described above, when the liquids are in contact with each other, the ink having a low surface tension flows toward the higher ink, so that the ink droplet 54 may flow toward the ink droplet 55 and form an integral ink. There is. In such a case, the partial thickness of the finally formed ink layer is increased, and the unevenness of the image surface is increased. Therefore, it is considered that the low gloss may be lowered.

  In view of the above points, in the present embodiment, it is possible to execute recording in which deterioration in image quality is suppressed by applying two types of inks having different dynamic surface tension and evaporation amount to adjacent regions in the same recording scan. .

  Since these two types of ink come into contact with each other in the liquid state in the same recording scan, there is a possibility that color unevenness occurs when they are mixed somewhat. Therefore, these two types of ink have substantially the same hue and are applied to adjacent areas in the same scan in the combination of magenta ink and light magenta ink, which are inks having different densities, and in the combination of cyan ink and light cyan ink. By performing the control, it is possible to record an image with little color unevenness due to mixing of inks.

  Further, in the combination of each of the two types of inks, the effect of uneven density due to beading on the ink layer described above is higher than that of magenta ink and cyan ink, which are relatively high in density, and light magenta ink, which is relatively low in density. Becomes larger. Therefore, in this embodiment, control is performed so as to suppress the beading of the ink having a relatively high density with respect to the ink layer in each combination.

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

  Each ink used in this embodiment includes a pigment, a resin emulsion, a water-soluble organic solvent, a surfactant, and the like.

  An example of a pigment that can be used in this embodiment is shown below. Specific examples of black pigments include carbon black such as furnace black, lamp black, acetylene black, and channel black. Commercially available carbon black pigments include Black Pearls L, Legal: 330R, 400R, 660R, Mogul L, Monak: 700, 800, 880, 900, 1000, 1100, 1300, 1400, 2000, Vulcan XC-72R, Stirling: MS NSX76 (manufactured by Cabot).

  Further, organic pigments are mainly used as color pigments, and for example, the following can be used. Water-insoluble azo pigments such as Toluidine Red, Toluidine Maroon, Hansa Yellow, Benzidine Yellow, and Pyrazolone Red. Water-soluble azo pigments such as Ritolol Red, Helio Bordeaux, Pigment Scarlet, and Permanent Red 2B. Derivatives from vat dyes such as alizarin, indanthrone and thioindigo maroon. Phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green. Quinacridone pigments such as quinacridone red and quinacridone magenta. Perylene pigments such as perylene red and perylene scarlet. Isoindolinone pigments such as isoindolinone yellow and isoindolinone orange. Imidazolone pigments such as benzimidazolone yellow, benzimidazolone orange, and benzimidazolone red. Pilanthrone pigments such as pyranthrone red and pyranthrone orange. Indigo pigments, condensed azo pigments, thioindigo pigments, diketopyrrolopyrrole pigments. Flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianslaquinonyl red, dioxazine violet.

  Moreover, when an organic pigment is shown by a color index (CI) number, the following are mentioned, for example. C. I. Pigment Yellow: 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 74, 75, 83, 86, 93, 95, 97, 98, 109, 110, 114, 117, 120, 125 . C. I. Pigment Yellow: 128, 129, 137, 138, 147, 148, 150, 151, 153, 154, 166, 168, 180, 185. C. I. Pigment Red: 5, 7, 9, 12, 48 (Ca), 48 (Mn), 49, 52, 53, 57 (Ca), 97, 112, 122, 123, 149, 168, 175, 176, 177, 180, 184, 192, 202, 207. C. I. Pigment Red: 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 272. C. I. Pigment Blue: 1, 2, 3, 4, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64. C. I. Bat Blue: 4, 6, 19, 23, 42.

  Since the above pigment color material is not sufficiently dispersible in an aqueous solvent, it is used after being subjected to a dispersion treatment. Depending on the difference due to the dispersion treatment of the pigment color material, it is divided into a resin dispersion type and a self-dispersion type, and both can be used in the present invention. The resin dispersion type is obtained by stably finely dispersing a colorant pigment in an aqueous solvent using a dispersant such as a water-soluble polymer compound. In the self-dispersion type, pigment particles are stably dispersed in an aqueous solvent without using a dispersant such as the above-described water-soluble polymer compound. Such a pigment is previously modified on the pigment surface, and for example, an anionic or cationic functional group is bonded to the pigment surface directly or via other atomic groups. By applying a modification treatment that imparts ionicity to the pigment surface, the affinity for a polar solvent such as water is increased, so that the pigment particles can be stably dispersed.

  In the present embodiment, the “resin emulsion” means polymer fine particles existing in a state of being dispersed in water, and has a property of forming a film by heating. Specifically, acrylic emulsion synthesized by emulsion polymerization of monomers such as (meth) acrylic acid alkyl ester and (meth) acrylic acid alkylamide; (meth) acrylic acid alkyl ester and (meth) acrylic acid alkylamide Styrene-acrylic emulsion synthesized by emulsion polymerization of styrene monomer and the like; polyethylene emulsion, polypropylene emulsion, polyurethane emulsion, styrene-butadiene emulsion and the like. In addition, core-shell type resin emulsions with different polymer compositions in the core and shell constituting the resin emulsion and acrylic fine particles synthesized in advance to control the particle size are used as seed particles and emulsion polymerization is performed around them. The resulting emulsion may be used. Furthermore, a hybrid resin emulsion in which different resin emulsions such as an acrylic resin emulsion and a urethane resin emulsion are chemically bonded may be used.

  Among the above resin emulsions, in the embodiment described below, styrene-acryl emulsion JONCRYL 790 (manufactured by BASF: average particle diameter D = 200 nm, glass transition temperature Tg = 90 ° C.) is used and diluted with water. A solution having a solid content of 20% is used as the resin solution P.

  The molecular weight of the resin emulsion used in the ink of the present invention is such that the polystyrene-equivalent number average molecular weight (Mn) obtained by GPC is 100,000 or more and 3,000,000 or less, and more preferably 300,000 or more and 2,000. 1,000 or less.

  The average particle size of the resin emulsion used in the ink of the present invention is preferably 50 nm or more and 250 nm or less. When the average particle size is less than 50 nm, the surface area of the resin emulsion particles per unit volume is increased, and the cohesive force between the particles is increased, so that the effect of improving the storage stability may not be sufficiently obtained. On the other hand, if the average particle size is larger than 250 nm, the sedimentation rate of the resin emulsion in the ink is increased, so that the effect of improving the ink ejection stability and storage stability may not be sufficiently obtained.

  The glass transition temperature (Tg) of the resin emulsion used for the ink of the present invention is preferably 40 ° C. or higher and 90 ° C. or lower. If Tg is 40 ° C. or higher, the resin has sufficient hardness, and it is easy to obtain the effect of improving scratch resistance. Further, if Tg is 90 ° C. or lower, the minimum film-forming temperature of the resin emulsion is easily lowered. Therefore, the resin applied to the recording medium is easily softened, and the image can be fixed efficiently. From these viewpoints, the resin emulsion using methyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate in which the Tg of the obtained resin emulsion is in the range of 40 ° C. or more and 90 ° C. or less. Is preferably used.

  The content (% by mass) of the resin emulsion used in the ink of the present invention is preferably 0.1% by mass or more and 10.0% by mass or less based on the total mass of the ink. Furthermore, 2.0 mass% or more and 8.0 mass% or less are more preferable. If it is less than 0.1% by mass, the effect of improving the scratch resistance of the image may not be sufficiently obtained. On the other hand, when the content is 10.0% by mass or more, the viscosity of the ink increases, and the ink ejection stability may not be sufficiently improved.

  An example of a water-soluble organic solvent that can be used in the present embodiment is shown below. Polyhydric alcohols such as glycerin and trimethylolpropane. Polyalkylene glycols such as polyethylene glycol and polypropylene glycol. Alkylene glycols having an alkylene group having 2 to 6 carbon atoms, such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, and diethylene glycol; Alkyl alcohols having 1 to 6 carbon atoms such as 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone. Urea and urea derivatives. Lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate. Amides such as dimethylformamide and dimethylacetamide. Ketones or ketoalcohols such as acetone and diacetone alcohol. Ethers such as tetrahydrofuran and dioxane.

  Among the various water-soluble organic solvents described above, the highly volatile water-soluble organic solvent suitably used in the present embodiment includes monovalent alcohols having a boiling point lower than 250 ° C., divalent alcohols, and glycol ethers. Can be mentioned. Examples of the monovalent alcohols include ethanol, isopropyl alcohol, and butanol. Examples of the divalent alcohol include propanediol, butanediol, pentanediol, and hexanediol having a linear alkyl chain. If the alkyl chain is longer than 7, the boiling point becomes high, so that it is not suitable as the highly volatile water-soluble organic solvent of the present invention. In addition, the two hydroxyl groups of the divalent alcohol are preferably one-end type alkyl alcohols that are arranged locally to some extent in the molecular structure, or alkyl alcohols that have a structure in which the arrangement of two hydroxyl groups is close to the one-end type. It is. The molecular structure is divided into a highly polar site consisting of two hydroxyl groups and a low-polarity alkyl chain site, which reduces the polarity of the molecule as a whole, weakens intermolecular hydrogen bonding, and increases volatility. It is. Specifically, one-terminal dihydric alkyl alcohols such as 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, and 1,2-hexanediol are preferable. Furthermore, examples of glycol ethers include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and triethylene glycol monomethyl ether.

  Further, as the surfactant that can be used in this embodiment, from the viewpoint of the effect of adjusting the ink surface tension, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, etc. Is mentioned. As surfactant material types, hydrocarbons, silicones, fluorines, etc. can be used. However, when ionic surfactants are used, they are balanced with the ionicity of other components used in the ink. Is selected. In particular, since the pigment coloring material dispersed in the aqueous solution has ionicity, the same ionic or nonionic surfactant is preferable from the viewpoint of ink stability.

  Specific examples of surfactants include nonionic surfactants such as ethylene oxide adducts of alkyl phenyl ethers, polyethylene oxide-polypropylene oxide copolymers, ethylene oxide adducts of acetylene glycol, sulfate and sulfonate type anions. Surfactants, polyether-modified siloxane surfactants, perfluoroalkyl ether fluorine surfactants, and the like. As the polyether-modified siloxane-based surfactant, BYK-345, BYK-346, BYK-347, BYK-348, etc. can be used. Further, as a perfluoroalkyl ether-based fluorosurfactant, DuPont Capstone (registered trademark) FS-3100, or the like can be used.

  Furthermore, as an additive component, in order to maintain the storage stability as an ink and the inkjet suitability, a pH adjuster, an antifoaming agent, a rust preventive, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, and an evaporation accelerator. Various additives such as are included as necessary.

  Using the materials described above, a plurality of types of evaluation inks for evaluating this embodiment were prepared. In this embodiment, two types of magenta inks (M1, M2) and three types of light magenta inks (LM1, LM2, LM3) are adjusted as the evaluation ink.

  A method for adjusting each ink will be described below.

  In the following description, “parts” and “%” are based on mass unless otherwise specified.

-Adjustment of magenta ink M1 Self-dispersed pigment dispersion Cab-O-Jet265M (manufactured by Cabot) was diluted with water and sufficiently stirred to obtain magenta pigment dispersion M (pigment content: 10.0% by mass). . A styrene-acrylic resin JONCRYL790 (manufactured by BASF: glass transition temperature 90 ° C.) was diluted with water to obtain a resin solution P having a solid content weight of the resin component of 20%. The following components were sufficiently stirred and then filtered under pressure with a micro filter (manufactured by Fuji Film) having a pore size of 2.5 μm to prepare a magenta ink.
Magenta pigment dispersion M 30 parts Resin solution P 20 parts Water-soluble organic solvent Triethylene glycol (boiling point 285 ° C.) 10 parts Water-soluble organic solvent 2-pyrrolidone (boiling point 245 ° C.) 5 parts Fluorine-based surfactant FS-3100 (DuPont) 1 part ion exchange water remaining

-Adjustment of magenta ink M2 The following components were blended by the same adjustment method as magenta ink M1 to adjust magenta ink M2.
Magenta pigment dispersion M 30 parts Resin solution P 20 parts Water-soluble organic solvent 2-pyrrolidone (boiling point 245 ° C.) 5 parts Water-soluble organic solvent 1,2-pentanediol (boiling point 210 ° C.) 15 parts Fluorosurfactant FS- 3100 (manufactured by DuPont) 1 part ion-exchanged water balance

-Adjustment of light magenta ink LM1 The light magenta ink LM1 was adjusted by blending the following components by the same adjustment method as that for the magenta ink M1.
Magenta pigment dispersion M 5 parts Resin solution P 20 parts Water-soluble organic solvent 2-pyrrolidone (boiling point 245 ° C.) 5 parts Water-soluble organic solvent 1,2-pentanediol (boiling point 210 ° C.) 15 parts Fluorine-based surfactant FS- 3100 (manufactured by DuPont) 1 part ion-exchanged water balance

-Adjustment of light magenta ink LM2 Light magenta ink LM2 was prepared by blending the following components in the same adjustment method as magenta ink M1.
Magenta pigment dispersion M 5 parts Resin solution P 20 parts Water-soluble organic solvent 2-pyrrolidone (boiling point 245 ° C.) 5 parts Water-soluble organic solvent Diethylene glycol monoethyl ether (boiling point 202 ° C.) 15 parts Fluorosurfactant FS-3100 ( DuPont) 1 part Ion-exchanged water The remainder

-Adjustment of light magenta ink LM3 Light magenta ink LM3 was prepared by blending the following components in the same adjustment method as magenta ink M1.
Magenta pigment dispersion M 5 parts Resin solution P 20 parts Water-soluble organic solvent Triethylene glycol (boiling point 285 ° C.) 10 parts Water-soluble organic solvent 2-pyrrolidone (boiling point 245 ° C.) 5 parts Fluorine-based surfactant FS-3100 (DuPont) 1 part ion exchange water remaining

  The dynamic surface tension, static surface tension and evaporability of the magenta inks M1, M2 and light magenta inks LM1, LM2, LM3 described above were measured.

  Here, the dynamic surface tension was measured using an automatic dynamic surface tension system (manufactured by Kyowa Interface Chemical Co., Ltd.) under the conditions of a lifetime of 10 milliseconds and a temperature of 25 ° C. according to the above-mentioned maximum bubble pressure method.

  The static surface tension was measured using a platinum plate method at a temperature of 25 ° C.

In addition, for the measurement of evaporability, a predetermined amount (0.1 g) of each adjusted ink was weighed on a glass petri dish, and the mass% decreased after passing for 10 minutes (6 × 10 ² seconds) at 60 ° C. It is evaluated by a certain ΔW. That is, the larger the ΔW, the more the ink is evaporated (the evaporation speed is faster).

  Table 1 shows the measurement results of the dynamic surface tension, static surface tension and evaporability of each ink.

  In this embodiment, the magenta inks M1 and M2 and the light magenta inks LM1, LM2, and LM3 are used to perform an image evaluation experiment described later.

  Next, the recording medium used in the present embodiment will be described in detail below.

  In this embodiment, white glossy vinyl chloride adhesive (gray glue) KSM-VS (manufactured by Kimoto Co., Ltd.) having a vinyl chloride layer formed on a substrate is used as a recording medium. The recording medium to which the present invention can be applied is not limited to a sheet made of vinyl chloride, but a particularly remarkable effect can be obtained when a recording medium that has low ink absorbability or does not absorb ink is used. . As such a recording medium, in addition to vinyl chloride, for example, polyester, water-resistant pulp sheet, printing coated paper provided with a non-water-absorbing layer on pulp, a composite of pulp and chemical fiber Etc.

(Data processing process)
FIG. 9 is a flowchart of data processing used for recording executed by the CPU according to the control program in the present embodiment.

  First, in step S801, color conversion processing is performed for converting input data in RGB format into multi-value data corresponding to the color of ink used for recording. By this color conversion processing, multi-value data represented by 8-bit 256-value information that determines the gradation in each of the plurality of pixel regions is generated.

  Next, in step S802, a quantization process for quantizing the multilevel data is performed. By this quantization processing, quantized data represented by 1-bit binary information that determines ink ejection or non-ejection for each pixel region is generated. As this quantization processing, various quantization methods such as an error diffusion method, a dither method, and an index expansion method can be applied.

  In step S803, distribution processing for distributing the quantized data to a plurality of scans is performed using a mask pattern described later. By this distribution processing, print data represented by 1-bit binary information that determines whether or not ink is ejected to each pixel area in each of a plurality of scans is generated.

  FIG. 10 is a diagram for explaining a mask pattern used in this embodiment. In this embodiment, an image is recorded by performing eight (N) recording scans on a unit area on the recording medium. Accordingly, distribution processing is performed using eight (N) mask patterns.

  In the present embodiment, the mask patterns 61 to 68 are applied to quantized data corresponding to magenta ink having a relatively high dynamic surface tension and a relatively low evaporation property among a plurality of inks. The mask patterns 61 to 68 are mask patterns for distributing quantized data to the first to eighth scans. For example, for the first scan, the quantized data distribution process corresponding to magenta ink is performed using the mask pattern 61 corresponding to the first scan.

  On the other hand, the mask patterns 71 to 78 are applied to quantized data corresponding to light magenta ink having a relatively low dynamic surface tension and a relatively high evaporation property among a plurality of inks. The mask patterns 71 to 78 are mask patterns for distributing quantized data to the first to eighth scans. For example, for the first scan, a distribution process of quantized data corresponding to the light magenta ink is performed using the mask pattern 71 corresponding to the first scan.

  Here, each of the mask patterns 61 to 68 corresponding to magenta ink is arranged so that the print permitting pixels are not adjacent to each other. In other words, in each of the mask patterns 61 to 68, there are no print permitting pixels arranged at positions adjacent to other print permitting pixels. Therefore, by using the mask patterns 61 to 68, magenta ink is ejected to adjacent pixel regions in the same scan in each of the first to eighth scans, and the magenta inks are prevented from contacting each other in the form of droplets. be able to.

  Similarly, each of the mask patterns 71 to 78 corresponding to the light magenta ink is arranged so that the print permitting pixels are not adjacent to each other. In other words, in each of the mask patterns 71 to 78, there are no print permitting pixels arranged at positions adjacent to other print permitting pixels. Therefore, by using the mask patterns 71 to 78, light magenta ink is ejected to adjacent pixel regions in the same scan in each of the first to eighth scans, and the light magenta inks come into contact with each other in a droplet state. Can be avoided.

  Here, the logical sum patterns 81 to 88 correspond to the same scanning, and are obtained by taking the logical sum of the print permission pixels arranged in the mask pattern corresponding to magenta ink and the mask pattern corresponding to light magenta ink. The pattern is shown. For example, the logical sum pattern 81 corresponding to the first scan includes the print allowable pixels arranged in the magenta ink mask pattern 61 corresponding to the first scan and the light magenta ink corresponding to the first scan. It can be obtained by taking the logical sum of the print permitting pixels arranged in the mask pattern 71.

  In each of the logical sum patterns 81 to 88, all the print permitting pixels are arranged adjacent to each other. For example, although the four print permission pixels are arranged in the logical sum pattern 81, all the four print permission pixels are adjacent to each other. Therefore, by applying a set of mask patterns 61 to 68 and mask patterns 71 to 78 that can obtain the logical sum patterns 81 to 88, the same scan is performed in each of the first to eighth scans between a plurality of inks. It can be seen that the ink drops contact each other.

  By using the magenta ink mask patterns 61 to 68 and the light magenta ink mask patterns 71 to 78 as described above, each ink is not applied to the adjacent pixel region in the same scan, and a plurality of inks are used. In between, it is given to adjacent pixel regions by the same scanning. In other words, magenta ink and light magenta ink can be applied to positions adjacent to each other in the same scan.

(Evaluation of ink)
Using the magenta inks M1 and M2 and the light magenta inks LM1, LM2, and LM3, which are the above-described evaluation inks, using the mask pattern shown in FIG. The results of sex evaluation experiments are described in detail below.

  Here, a secondary color solid image (image size: 50 mm square) was recorded by an inkjet recording apparatus with a recording duty of 200%. Here, the recording duty of 100% corresponds to a state where four inks are ejected at a resolution of 1200 dpi for an image unit area of 600 dpi.

  Further, during recording, heating was performed by the first heater 25 so that the surface temperature of the recording medium was about 60 ° C. After the recording, the second heater 27 performed heating at 120 ° C. for 5 minutes to fix the image.

The density unevenness of the image created above was evaluated visually. The image was observed from a point about 30 cm away from the printed matter, and the level of density unevenness visible was evaluated as follows.
○: Image uniformity is good and density unevenness is small.
Δ: The density unevenness can be easily visually confirmed. Small unevenness of several mm is generated.

Further, the glossiness was evaluated as follows from the 20-degree regular reflection intensity value of a reflection gloss meter.
(Circle): Glossiness 30 or more (triangle | delta): Glossiness less than 30 This evaluation result is shown in (Table 2).

  As can be seen from Table 2, density unevenness is visually recognized in the combination of magenta ink M2 and light magenta ink LM1, and in the combination of magenta ink M1 and light magenta ink LM3. This can be presumed to be because the evaporation properties of magenta ink and light magenta ink 3 hardly change in these combinations.

  Similarly, density unevenness is also observed in the combination of magenta ink M2 and light magenta ink LM3. This is because the magenta ink M2, which has a high density and has a strong effect of contributing to uneven density, has higher evaporability than the light magenta ink LM3, which has a low density and has a weak effect of contributing to uneven density, and therefore the ink layer of magenta ink M2 This is probably because the beading has occurred.

  On the other hand, in the combination of magenta ink M2 and light magenta ink LM1, and in the combination of magenta ink M2 and light magenta ink LM2, density unevenness is hardly seen. With these combinations, the light magenta ink has a low density and weakly contributes to density unevenness, and the light magenta ink has higher evaporability than the magenta ink, and the dynamic surface tension of the light magenta ink and the dynamic surface tension of the magenta ink The difference is relatively large. Therefore, it is considered that beading of ink droplets with respect to the ink layer can be suppressed by the estimation mechanism described in FIG. According to the study by the inventors, when the difference between the dynamic surface tension of magenta ink and the dynamic surface tension of light magenta ink is larger than 5 [mN / m], beading of ink droplets to the ink layer is performed. It has been experimentally found that it can be suitably suppressed.

  Regarding glossiness, there is a slight decrease in the combination of magenta ink M2 and light magenta ink LM3, and in the combination of magenta ink M2 and light magenta ink LM1. This is thought to be because the dynamic surface tension of magenta ink is less than or substantially the same as the dynamic surface tension of light magenta ink in these combinations.

  On the other hand, a combination of magenta ink M1 and light magenta ink LM1, or a combination of magenta ink M1 and light magenta ink LM2, can record a highly glossy image. This can be presumed to be because the dynamic surface tension of magenta ink is larger than the dynamic surface tension of light magenta ink.

  In view of the above points, in this embodiment, a combination of two types of inks has a relatively high dynamic surface tension and a relatively low evaporation property, and a relatively low dynamic surface tension and a relatively low evaporation property. The recording is controlled so that these inks are applied to adjacent areas on the recording medium in the same scan. This makes it possible to perform recording while suppressing beading of ink droplets on the ink layer.

(Second Embodiment)
In the first embodiment, a mode in which two types of ink are applied to adjacent pixel regions in the unit region in all scannings has been described.

  In contrast, in the present embodiment, a mode in which two types of ink are applied to adjacent pixel regions in a unit region only in a specific scan will be described.

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

  The beading of the ink droplets with respect to the ink layer does not necessarily occur uniformly in each of a plurality of scans with respect to the unit area. For example, when recording is performed by scanning N (N ≧ 2) times in a unit area, beading of ink droplets with respect to the ink layer is particularly noticeable in the latter half of the scanning (N / 2 ≦ K ≦ N) times. There is a case.

  In the first half of the multiple scans, the ink layer formed in the previous scan is relatively few. Therefore, depending on the size of the ink droplets and the ink layer, there may not be so many ink droplets in contact with the ink layer in the first half of scanning.

  On the other hand, in the second half scan, ink has already been ejected in the first half scan, so that the ink layer formed in the first scan is larger than in the first half scan. For this reason, the ink layer and ink droplets often come into contact with each other as compared with the first half of the scanning, and accordingly, beading also occurs remarkably.

  Therefore, in the present embodiment, control is performed so that two types of ink are applied to adjacent pixel regions only in the latter half of a plurality of scans. Thereby, it is possible to suitably suppress beading of the ink droplets with respect to the ink layer that can be particularly noticeably generated in the latter half of scanning.

  On the other hand, in the first half of the plurality of scans, control is performed so that two types of ink are applied to pixel regions that are not adjacent to each other. In the first half of the scan, ink droplet beading with respect to the ink layer is unlikely to occur, so two types of ink are dispersed and ejected in order to suppress beading between the ink droplets.

  FIG. 11 is a diagram for explaining a mask pattern used in the present embodiment. In this embodiment as well, an image is recorded by performing eight recording scans on the unit area on the recording medium.

  In the present embodiment, the mask patterns 61 ′ to 68 ′ are applied to quantized data corresponding to magenta ink having a relatively high dynamic surface tension and a relatively low evaporation property among a plurality of inks. The mask patterns 61 'to 68' are mask patterns for distributing quantized data to the first to eighth scans. For example, for the first scan, the distribution of quantized data corresponding to magenta ink is performed using the mask pattern 61 ′ corresponding to the first scan.

  On the other hand, mask patterns 71 ′ to 78 ′ are applied to quantized data corresponding to light magenta ink having a relatively low dynamic surface tension and a relatively high evaporation property among a plurality of inks. The mask patterns 71 'to 78' are mask patterns for distributing quantized data to the first to eighth scans. For example, for the first scan, the distribution of quantized data corresponding to light magenta ink is performed using the mask pattern 71 ′ corresponding to the first scan.

  Here, each of the mask patterns 61 ′ to 68 ′ corresponding to magenta ink is arranged so that the print permitting pixels are not adjacent to each other. In other words, in each of the mask patterns 61 ′ to 68 ′, there are no print permitting pixels arranged at positions adjacent to other print permitting pixels. Therefore, by using the mask patterns 61 ′ to 68 ′, magenta ink is ejected to adjacent pixel regions in the same scan in each of the first to eighth scans, and the magenta inks come into contact with each other in a droplet state. Can be avoided.

  Similarly, each of the mask patterns 71 ′ to 78 ′ corresponding to the light magenta ink is arranged so that the print permitting pixels are not adjacent to each other. In other words, in each of the mask patterns 71 ′ to 78 ′, there are no print permitting pixels arranged at positions adjacent to other print permitting pixels. Therefore, by using the mask patterns 71 ′ to 78 ′, light magenta ink is ejected to adjacent pixel regions in the same scan in each of the first to eighth scans, and the light magenta inks are in contact with each other in a droplet state. You can avoid doing that.

  The logical sum patterns 81 ′ to 88 ′ correspond to the same scanning with each other, and are patterns obtained by taking the logical sum of the print permission pixels arranged in the mask pattern corresponding to magenta ink and the mask pattern corresponding to light magenta ink. Is shown. For example, the logical sum pattern 81 ′ corresponding to the first scan includes the print allowable pixels arranged in the magenta ink mask pattern 61 ′ corresponding to the first scan and the light magenta ink corresponding to the first scan. It can be obtained by taking the logical sum of the print permitting pixels arranged in the mask pattern 71 '.

  Here, among the OR patterns 81 'to 88', the OR patterns 85 'to 88' corresponding to the second to fifth scans are arranged so that all the print permitting pixels are adjacent to each other. ing. For example, although four print permission pixels are arranged in the logical sum pattern 85 ′, all of the four print permission pixels are adjacent to each other. Therefore, by applying a set of mask patterns 65 'to 68' and mask patterns 75 'to 78' that can obtain logical sum patterns 85 'to 88', the fifth to eighth scans are performed between a plurality of inks. It can be seen that the ink droplets are in contact with each other in the same scanning.

  On the other hand, none of the print permission pixels is adjacent to the other print permission pixels in each of the logical sum patterns 81 ′ to 84 ′ corresponding to the first to fourth scans in the first half of the logical sum patterns 81 ′ to 88 ′. Are arranged as follows. For example, although the four print permission pixels are arranged in the logical sum pattern 81 ′, none of the four print permission pixels is adjacent to the other print permission pixels. Therefore, by applying a set of mask patterns 61 ′ to 64 ′ and mask patterns 71 ′ to 74 ′ that can obtain logical sum patterns 81 ′ to 84 ′, the first to fourth times are performed between a plurality of inks. In each of the scans, it is possible to eject ink so that the ink droplets do not contact in the same scan.

  By using the magenta ink mask patterns 61 to 68 and the light magenta ink mask patterns 71 to 78 as described above, each ink is not applied to the adjacent pixel region in the same scan, and a plurality of inks are used. In the first half scan, the same scanning is applied to non-adjacent pixel areas, and in the second half scanning, the same scanning is applied to adjacent pixel areas. In other words, it is possible to apply magenta ink and light magenta ink to positions that are not adjacent to each other in the same scan in the first half scan and to positions adjacent to each other in the same scan in the second half scan.

(Third embodiment)
In the first and second embodiments, the form in which the same mask pattern is applied to the entire area (all unit areas) on the recording medium has been described.

  On the other hand, in the present embodiment, a mode in which different mask patterns are applied depending on the unit area on the recording medium will be described.

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

  When the amount of ink ejected to a certain area on the recording medium is relatively large, the possibility of contact between the ink layer and the ink droplet increases, and therefore beading of the ink droplet to the ink layer is likely to occur. Therefore, it is better to apply two types of ink to adjacent pixel regions in the same scan.

  On the other hand, when the amount of ink discharged to a certain area is relatively small, the ink layer and the ink droplet do not contact so much, and therefore the beading of the ink droplet to the ink layer hardly occurs. Therefore, in order to suppress beading between ink droplets in a region where the amount of ink discharged is relatively small, it is preferable to apply two types of ink to pixel regions that are not adjacent in the same scan.

  In view of the above points, in the present embodiment, information regarding the ejection amount is acquired for each unit region obtained by dividing the recording medium, and two types of mask pattern groups are switched and applied according to the information.

  FIG. 12 is a flowchart of data processing used for recording executed by the CPU according to the control program in the present embodiment.

  Steps S601 and SS602 are the same as steps S801 and S802 shown in FIG.

  In step S603, information regarding the ejection amount is acquired for each unit area based on the quantized data generated by the quantization process. Here, the size and the number of unit regions may be appropriately different as long as they are regions included in one scanning region. For example, here, a pixel area corresponding to 16 pixels of 4 pixels × 4 pixels is defined as one unit area. Here, the information about the ejection amount is acquired based on the quantized data, but the information about the ejection amount may be acquired based on multi-value data after the color conversion process or input image data before the color conversion process.

  Next, in step S604, the discharge amount in each unit region is compared with a predetermined threshold value. In this embodiment, the ejection amount (printing duty = 50%) when ink is ejected to a half pixel area in the unit area is used as the threshold value.

  If it is determined that the discharge amount for a certain unit area is greater than or equal to the threshold, the process proceeds to step S605. In order to suppress ink droplet beading with respect to the ink layer, in step S605, the mask patterns 61 to 68 shown in FIG. 10 for the magenta ink quantization data corresponding to the unit area are shown in the light magenta ink quantization data. Mask patterns 71 to 78 shown in FIG.

  On the other hand, if it is determined that the discharge amount for a certain unit area is less than the threshold value, the process proceeds to step S606, and the mask patterns 61 ″ to 68 ″ shown in FIG. 13 are included in the magenta ink quantization data corresponding to the unit area. Mask patterns 71 ″ to 78 ″ shown in FIG. 13 are applied to quantized data of light magenta ink.

  Here, each of the mask patterns 61 ″ to 68 ″ corresponding to magenta ink is arranged so that the print permitting pixels are not adjacent to each other. In other words, in each of the mask patterns 61 ″ to 68 ″, there is no print permitting pixel arranged at a position adjacent to other print permitting pixels. Therefore, by using the mask patterns 61 ″ to 68 ″, magenta ink is ejected to adjacent pixel regions in the same scan in each of the first to eighth scans, and the magenta inks are in contact with each other in a droplet state. You can avoid doing that.

  Similarly, each of the mask patterns 71 ″ to 78 ″ corresponding to the light magenta ink is arranged so that the print permitting pixels are not adjacent to each other. In other words, in each of the mask patterns 71 ″ to 78 ″, there are no print permitting pixels arranged at positions adjacent to other print permitting pixels. Therefore, by using the mask patterns 71 ″ to 78 ″, the light magenta ink is ejected to adjacent pixel regions in the same scan in each of the first to eighth scans, and the light magenta inks are in a droplet state. You can avoid contact with.

  The logical sum patterns 81 ″ to 88 ″ correspond to the same scanning with each other, and are obtained by taking the logical sum of the print allowable pixels arranged in the mask pattern corresponding to magenta ink and the mask pattern corresponding to light magenta ink. The pattern that is shown. For example, the logical sum pattern 81 ″ corresponding to the first scan includes the print allowable pixels arranged in the magenta ink mask pattern 61 ″ corresponding to the first scan and the write corresponding to the first scan. This can be obtained by taking the logical sum of the print permitting pixels arranged in the magenta ink mask pattern 71 ″.

  Here, in each of the logical sum patterns 81 ″ to 88 ″, any print permission pixel is arranged so as not to be adjacent to other print permission pixels. For example, although the four print permission pixels are arranged in the logical sum pattern 81 ″, none of the four print permission pixels is adjacent to the other print permission pixels. Therefore, by applying a set of mask patterns 61 ″ to 68 ″ and mask patterns 71 ″ to 78 ″ that can obtain logical sum patterns 81 ″ to 88 ″, a plurality of inks can be obtained. In addition, in each of the first to eighth scans, it is possible to eject the ink so that the ink droplets do not contact in the same scan.

  As a result, when the ejection amount with respect to the unit region is small and beading of ink droplets with respect to the ink layer is difficult to occur, it is possible to control a plurality of types of ink not to be adjacent in the same scan.

  As described above, according to the present embodiment, since the ink ejection control is switched according to the ejection amount with respect to the unit area on the recording medium, it is possible to more suitably suppress the deterioration in image quality.

  In each of the embodiments described above, a mode in which no print permitting pixels adjacent to other print permitting pixels exist as a mask pattern for magenta ink has been described. However, implementations in other forms are also possible. In other words, it is sufficient that each mask pattern has a certain number of print permitting pixels adjacent to other print permitting pixels. Here, the number of print permitting pixels adjacent to other print permitting pixels in each mask pattern is approximately 1/4 times the number of print permitting pixels arranged in each mask pattern (quarter number). As a result of examination, it is known that a small number is preferable. Further, it is more preferable that the number is less than about 1/8 times. The same applies to the mask pattern for light magenta ink.

  Further, in each of the embodiments described above, a description has been given of a form in which all the print permission pixels in the logical sum pattern are adjacent to each other, but other forms are also possible. In other words, it is sufficient if there is a certain number of print permitting pixels adjacent to other print permitting pixels in each logical OR pattern. Here, the number of print permitting pixels adjacent to other record permitting pixels in each logical sum pattern is approximately half the number (half) of the number of print permitting pixels arranged in each logical sum pattern. As a result of examination, it is known that a larger number is preferable. Further, it is more preferable that the number is more than about 3/4 times.

  From the viewpoint of ink droplets formed as a result of recording, in order to suppress magenta ink beading on the ink layer, adjacent pixels among pixel areas to which magenta ink is applied in the same scan. It is preferable to control so that the number of pixel areas to which light magenta ink is applied is larger than that of pixel areas to which light magenta ink is not applied to adjacent pixel areas.

  Further, in each of the embodiments described above, a mode is described in which two types of ink are set in contact with each other in a mask pattern corresponding to a plurality of scans, but only two types in a mask pattern corresponding to one scan. The ink may be determined so as to come into contact.

  The present invention is not limited to a thermal jet type ink jet recording apparatus. For example, the present invention can be effectively applied to various image recording apparatuses such as a so-called piezo-type ink jet recording apparatus that discharges ink using a piezoelectric element.

  In each embodiment, an image recording method using an image recording apparatus is described. However, an image processing apparatus, an image processing method, and a program for generating data for performing the image recording method described in each embodiment are recorded in the image. The present invention can also be applied to a form prepared separately from the apparatus. Needless to say, the present invention can be widely applied to a configuration provided in a part of the image recording apparatus.

  The “recording medium” includes not only paper used in general recording apparatuses but also a wide range of cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. .

  Furthermore, “ink” is applied onto a recording medium to form an image, a pattern, a pattern, or the like, process the recording medium, or process ink (for example, the colorant in the ink applied to the recording medium). It shall represent a liquid that can be subjected to solidification or insolubilization.

3 Recording medium 7 Recording head 301 CPU
302 ROM

Claims (23)

A recording medium for a recording head that ejects a plurality of inks including at least a first ink containing a pigment, a resin emulsion and a water-soluble organic solvent, and a second ink containing a pigment, a resin emulsion and a water-soluble organic solvent Pixels corresponding to a plurality of pixels in the unit region in each of the N scans for ejecting ink while performing N (N ≧ 2) relative scans in the scanning direction with respect to the upper unit region An image processing apparatus that generates recording data that defines ink ejection or non-ejection for each region,
First image data that defines ejection or non-ejection of the first ink for each of the plurality of pixel areas in the unit area in the N scans, and the image in the unit area in the N scans. Acquisition means for acquiring second image data for determining ejection or non-ejection of the second ink for each of a plurality of pixel regions;
N first mask patterns each corresponding to each of the N scans, each having print permitting pixels that determine ink discharge allowance and non-printing allowance pixels that determine ink discharge non-permission, Based on the first image data acquired by the acquisition unit, N first print data for ejecting the first ink is generated in each of the N scans. And N second mask patterns corresponding to each of the N scans, each having print permitting pixels and non-printing allowance pixels, and the second image acquired by the acquisition unit Generating means for generating N second print data for ejecting the second ink in each of the N scans based on the data,
The second ink has a lower dynamic surface tension under the conditions of a predetermined lifetime and a first temperature than the first ink, and has a predetermined time and a second higher than that of the first ink. The amount of evaporation under temperature conditions is large,
Of the N first and second mask patterns, the first and second mask patterns respectively corresponding to the Kth (2 ≦ K ≦ N) scan,
(I) The number of print permitting pixels arranged at a position adjacent to another print permitting pixel in the first mask pattern is approximately 1 of the number of print permitting pixels arranged in the first mask pattern. / 4 less than the number,
(Ii) The number of print permitting pixels arranged at positions adjacent to other print permitting pixels in the second mask pattern is approximately 1 of the number of print permitting pixels arranged in the second mask pattern. / 4 less than the number,
(Iii) The number of print permission pixels adjacent to other print permission pixels in the logical sum pattern obtained by the logical sum of the print permission pixels arranged in the first and second mask patterns is the logical sum pattern. An image processing apparatus characterized in that the number is more than approximately ½ times the number of recordable pixels arranged in the.   The image processing apparatus according to claim 1, wherein K ≧ N / 2. Of the N first and second mask patterns, the first and second mask patterns corresponding to the same scan performed after the K-th scan,
(I) The number of print permitting pixels arranged at a position adjacent to another print permitting pixel in the first mask pattern is approximately 1 of the number of print permitting pixels arranged in the first mask pattern. / 4 less than the number,
(Ii) The number of print permitting pixels arranged at positions adjacent to other print permitting pixels in the second mask pattern is approximately 1 of the number of print permitting pixels arranged in the second mask pattern. / 4 less than the number,
(Iii) The number of print permission pixels adjacent to other print permission pixels in the logical sum pattern obtained by the logical sum of the print permission pixels arranged in the first and second mask patterns is the logical sum pattern. 3. The image processing apparatus according to claim 1, wherein the number is larger than a number that is approximately ½ times the number of recording-allowed pixels arranged in the image processing apparatus. The first and second mask patterns corresponding to the same scan performed before the K-th scan among the N first and second mask patterns,
(I) The number of print permitting pixels arranged at a position adjacent to another print permitting pixel in the first mask pattern is approximately 1 of the number of print permitting pixels arranged in the first mask pattern. / 4 less than the number,
(Ii) The number of print permitting pixels arranged at positions adjacent to other print permitting pixels in the second mask pattern is approximately 1 of the number of print permitting pixels arranged in the second mask pattern. / 4 less than the number,
(Iii) The number of print permission pixels adjacent to other print permission pixels in the logical sum pattern obtained by the logical sum of the print permission pixels arranged in the first and second mask patterns is the logical sum pattern. The image processing apparatus according to claim 3, wherein the number is less than a number that is approximately ½ times the number of pixels that are allowed to be recorded. A second acquisition unit configured to acquire information related to an ink discharge amount with respect to the unit region;
The first generation unit is configured to: (i) when the discharge amount indicated by the information acquired by the second acquisition unit is greater than a predetermined amount, the N first mask patterns and the first image N pieces of first print data are generated based on the data, and the N pieces of second print data are formed based on the N pieces of second mask patterns and the second image data. (Ii) when the discharge amount indicated by the information acquired by the second acquisition unit is smaller than the predetermined amount, each of the N scans corresponds to each of the print allowable pixels and the non-print Generating the N first recording data based on the N third mask patterns in which the allowable pixels are arranged and the first image data acquired by the acquiring unit; and , Corresponding to each of the N scans, Based on the N fourth mask patterns in which the print permitting pixels and the non-printing allowance pixels are arranged, and the second image data acquired by the acquiring unit, the N second mask patterns are obtained. Generate recorded data,
Of the N third and fourth mask patterns, the third and fourth mask patterns respectively corresponding to the Kth scan,
(I) The number of print permitting pixels arranged at positions adjacent to other print permitting pixels in the third mask pattern is approximately 1 of the number of print permitting pixels arranged in the third mask pattern. / 4 less than the number,
(Ii) The number of print permitting pixels arranged at a position adjacent to other print permitting pixels in the fourth mask pattern is approximately 1 of the number of print permitting pixels arranged in the fourth mask pattern. / 4 less than the number,
(Iii) The number of print permission pixels adjacent to other print permission pixels in the logical sum pattern obtained by the logical sum of the print permission pixels arranged in the third and fourth mask patterns is the logical sum pattern. 5. The image processing apparatus according to claim 1, wherein the number is less than about ½ times the number of recording-allowed pixels arranged in the image processing apparatus.   Dynamic surface tension of the first ink under the condition of the predetermined lifetime and the first temperature, and dynamic surface tension of the second ink under the condition of the predetermined lifetime and the first temperature. The image processing apparatus according to claim 1, wherein a difference between the surface tension and the surface tension is greater than 5 [mN / m].   The static surface tension of the first ink under the first temperature condition is substantially equal to the static surface tension of the second ink under the first temperature condition. The image processing apparatus according to claim 1.   The image processing apparatus according to claim 1, wherein the second ink has substantially the same hue as the first ink and has a lower density than the first ink. Of the N first and second mask patterns, the first and second mask patterns respectively corresponding to the Kth scan,
(I) The number of print permitting pixels arranged at a position adjacent to another print permitting pixel in the first mask pattern is approximately 1 of the number of print permitting pixels arranged in the first mask pattern. / 8 less than the number,
(Ii) The number of print permitting pixels arranged at positions adjacent to other print permitting pixels in the second mask pattern is approximately 1 of the number of print permitting pixels arranged in the second mask pattern. The image processing apparatus according to claim 1, wherein the number is less than a number of / 8 times. Of the N first and second mask patterns, the first and second mask patterns respectively corresponding to the Kth scan,
The number of print permission pixels adjacent to other print permission pixels in the logical sum pattern obtained by the logical sum of the print permission pixels arranged in the first and second mask patterns is arranged in the logical sum pattern. The image processing apparatus according to any one of claims 1 to 9, wherein the number is larger than a number approximately 3/4 times the number of permitted printing pixels. 11. The image processing apparatus according to claim 1, wherein the predetermined lifetime is 5 × 10 ⁻³ seconds, and the first temperature is 25 ° C. 11. 12. The image processing apparatus according to claim 1, wherein the predetermined time is 6 × 10 ² seconds, and the second temperature is 60 ° C. 12.   The image processing apparatus according to claim 1, wherein the dynamic surface tension of the first and second inks is a value measured by a maximum bubble pressure method.   The image processing apparatus according to claim 1, wherein the resin emulsion has a property of forming a film by heating.   The image processing apparatus according to claim 1, wherein the recording medium includes a base material and a vinyl chloride layer formed on the base material.   The image processing apparatus according to claim 1, further comprising the recording head. A recording medium for a recording head that ejects a plurality of inks including at least a first ink containing a pigment, a resin emulsion and a water-soluble organic solvent, and a second ink containing a pigment, a resin emulsion and a water-soluble organic solvent Pixels corresponding to a plurality of pixels in the unit region in each of the N scans for ejecting ink while performing N (N ≧ 2) relative scans in the scanning direction with respect to the upper unit region An image processing method for generating recording data for determining ejection or non-ejection of ink for each region,
First image data that defines ejection or non-ejection of the first ink for each of the plurality of pixel areas in the unit area in the N scans, and the image in the unit area in the N scans. Obtaining second image data that defines ejection or non-ejection of the second ink for each of a plurality of pixel regions; and
N first mask patterns each corresponding to each of the N scans, each having print permitting pixels that determine ink discharge allowance and non-printing allowance pixels that determine ink discharge non-permission, Based on the acquired first image data, N first print data for ejecting the first ink in each of the N scans is generated, and the Based on N second mask patterns each corresponding to each of N scans, each having print permitting pixels and non-printing allowance pixels, and the acquired second image data, Generating N second print data for ejecting the second ink in each of N scans;
The second ink has a lower dynamic surface tension under the conditions of a predetermined lifetime and a first temperature than the first ink, and has a predetermined time and a second higher than that of the first ink. The amount of evaporation under temperature conditions is large,
Of the N first and second mask patterns, the first and second mask patterns respectively corresponding to the Kth (2 ≦ K ≦ N) scan,
(I) The number of print permitting pixels arranged at a position adjacent to another print permitting pixel in the first mask pattern is approximately 1 of the number of print permitting pixels arranged in the first mask pattern. / 4 less than the number,
(Ii) The number of print permitting pixels arranged at positions adjacent to other print permitting pixels in the second mask pattern is approximately 1 of the number of print permitting pixels arranged in the second mask pattern. / 4 less than the number,
(Iii) The number of print permission pixels adjacent to other print permission pixels in the logical sum pattern obtained by the logical sum of the print permission pixels arranged in the first and second mask patterns is the logical sum pattern. An image processing method characterized in that the number of pixels is larger than the number of recording-permissible pixels arranged in ½. A recording head that ejects a plurality of inks including at least a first ink containing a pigment, a resin emulsion and a water-soluble organic solvent; and a second ink containing a pigment, a resin emulsion and a water-soluble organic solvent;
Scanning means for scanning the recording head relative to a unit area on the recording medium N (N ≧ 2) times;
Control means for controlling the first and second inks to be ejected from the recording head to a pixel area corresponding to a plurality of pixels in the unit area while performing scanning by the scanning means. A recording device,
The second ink has a lower dynamic surface tension under the conditions of a predetermined lifetime and a first temperature than the first ink, and has a predetermined time and a second higher than that of the first ink. The amount of evaporation under temperature conditions is large,
In the K (2 ≦ K ≦ N) -th scan among the N scans, the control means relates to a pixel region from which the first ink is ejected, and the second ink is placed in an adjacent pixel region. Controlling so that the first and second inks are ejected so that the number of ejected pixel regions is larger than the pixel region in which the second ink is not ejected in adjacent pixel regions. apparatus.   The image recording apparatus according to claim 18, wherein K ≧ N / 2.   The control means relates to a pixel region to which the first ink is ejected in each of the same scans performed after the K-th scan among the N scans. The first and second inks are controlled to be ejected so that the pixel area from which the second ink is ejected is larger than the pixel area from which the second ink is not ejected in the adjacent pixel area. The image recording apparatus according to claim 18 or 19.   Dynamic surface tension of the first ink under the condition of the predetermined lifetime and the first temperature, and dynamic surface tension of the second ink under the condition of the predetermined lifetime and the first temperature. 21. The image recording apparatus according to claim 18, wherein a difference between the surface tension and the surface tension is greater than 5 [mN / m].   The static surface tension of the first ink under the first temperature condition is substantially equal to the static surface tension of the second ink under the first temperature condition. The image recording apparatus according to any one of claims 18 to 21.   23. The image recording apparatus according to claim 18, wherein the second ink has substantially the same hue as the first ink and has a lower density than the first ink.

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