JP2017042928A - Inkjet recording device and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device that can record a high-quality image where a bleeding is suppressed even if the recording medium has low-permeability or no permeability, and to provide an inkjet recording method.SOLUTION: In inkjet recording of recording an image using three or more types of ink, two kinds of ink colors are mixed on a recording medium to control an imparting timing of ink depending on an imparting amount of the two kinds of inks with respect to a prescribed region on the recording medium.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a recording apparatus and a recording method for forming an image by discharging a plurality of types of ink.

  In recent years, high-speed recording has been demanded in image recording apparatuses such as inkjet recording apparatuses. When an image is formed at high speed using a plurality of types of ink, a bleed phenomenon may occur. In particular, a bleed phenomenon is likely to occur in a recording medium having low or no ink permeability. Bleed is a phenomenon in which one or more ink droplets are in a liquid state before they penetrate on the recording medium, while ink droplets of different color materials come into contact with each other and the other color material is mixed on one side. As a result, the boundary between ink droplets of different color materials is mixed. Sometimes called “bleeding” between different colors of the color material. In general, “bleeding” occurs from an ink droplet side having a low surface tension to an ink droplet side having a high surface tension. As a conventional method for suppressing such “bleeding”, for example, Patent Document 1 discloses a method of applying ink in which the difference in surface tension of all inks is controlled to 1.0 mN / m or less. Yes.

JP 2010-64478 A

  However, it may be insufficient depending on the type of the recording medium to control the difference in the surface tension of all inks to 1.0 mN / m or less as in the method disclosed in Patent Document 1. For example, when an image is formed on a recording medium with low ink permeability such as OK top coat + paper, a bleed phenomenon may occur even if there is a slight difference in surface tension between inks of different color materials. There is. On the other hand, in order to suppress the bleed phenomenon even in a recording medium with low ink permeability, it is considered that the difference in the surface tension of the ink is controlled to a smaller value (for example, 0.5 mN / m) or less. In this case, it is very difficult to produce ink and the production cost is increased.

  The present invention has been made to solve such problems. The object is to provide an ink jet recording method capable of suppressing the bleeding phenomenon even in a recording medium having low or no ink permeability by controlling the timing of ink application based on the amount of ink applied. There is to do.

The inkjet recording apparatus of the present invention includes at least a first ink, a second ink, and a third ink, and forms an image of the first ink and an image of the second ink adjacent to each other on a recording medium. In this case, the first ink oozes into the second ink image at an adjacent boundary between the first ink image and the second ink image, and the third ink image and the second ink image. When the second ink image is formed on the recording medium adjacently, the second ink is converted into the third ink image at an adjacent boundary portion between the third ink image and the second ink image. An ink jet recording apparatus that forms an image by causing a recording head capable of ejecting three or more types of ink to spread to scan a predetermined region on a recording medium a plurality of times,
Based on a distribution pattern for each of the three or more types of ink, and having discharge data distribution means for distributing the discharge data for discharging the three or more types of ink to a plurality of scans;
The ejection data distribution unit is configured to form the first ink and the third ink for the predetermined area when forming an image including a mixed color image of the first ink and the third ink in the predetermined area. According to the application amount, a distribution pattern set composed of the first ink distribution pattern and the third ink distribution pattern is switched.

  According to the present invention, the bleed phenomenon can be suppressed even in a recording medium with low or no permeability.

It is a figure which shows typically an example of the inkjet recording device applicable to 1st Embodiment. It is a schematic diagram which shows the ink drop which the bleed phenomenon produced. It is a figure which shows the mode of the image which the image bad effect produced by the bleed phenomenon, and the mode of the image which reduced the bleed phenomenon by forming an image by mixing light cyan ink and cyan ink. It is a graph which shows the change of surface tension when the addition amount of zonyl FSO-100 is increased with respect to cyan ink. It is a figure which shows the mask from which ink is discharged by the latter half scan among several scans. It is a figure which shows the mask from which an ink is discharged by intermediate | middle scanning among several scans, and the mask from which ink is discharged by the first half of scanning. It is an ink profile showing the amount of light cyan ink and cyan ink applied in each gradation from white to cyan. It is a figure which shows the mask from which an ink is discharged by the equal ratio in all the scans. FIG. 2 is a block diagram illustrating a configuration of a control system of the recording system according to the first embodiment. 6 is a flowchart of image processing and mask set selection processing in the first embodiment. It is a figure which shows a mask with a high ratio with which ink is ejected by the latter half scan among a plurality of scans, and a mask with a high ratio with which ink is ejected by the first half scan. It is a figure which shows the mask with a high ratio by which ink is discharged by the first half scan among several scans. It is a flowchart which registers the optimal mask set corresponding to each RGB value using the bleed value adjustment pattern in 4th Embodiment. It is a figure which shows the bleed value adjustment pattern in 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram schematically illustrating an example of an ink jet recording apparatus applicable to the present embodiment.

  The recording head unit 22 includes recording heads 22K, 22C, and 22M that discharge black (K), cyan (C), magenta (M), yellow (Y), light cyan (Lc), and light magenta (Lm) inks, respectively. 22Y, 22Lc, and 22Lm. The recording heads 22K, 22C, 22M, 22Y, 22Lc, and 22Lm are arranged in parallel in the main scanning direction (arrow B direction). Each recording head is formed with an ejection port array in which 1280 ejection ports (nozzles) are arranged at a density of 1200 dpi along a sub-scanning direction (arrow A direction) orthogonal to the main scanning direction. The amount of ink ejected from each ejection port at a time is about 4.5 ng. Recording is performed by ejecting ink to the recording medium 1 from these ejection openings.

  The ink tank unit 21 includes ink tanks 21K, 21C, 21M, 21Y, 21Lc, and 21Lm that store ink for the recording heads 22K, 22C, 22M, 22Y, 22Lc, and 22Lm, respectively. The ink tank unit 21 and the recording head unit 22 can reciprocate in the main scanning direction.

  The cap unit 20 includes caps 20K, 20C, 20M, 20Y, 20Lc, and 20Lm for capping the ink ejection surfaces of the recording heads 22K, 22C, 22M, 22Y, 22Lc, and 22Lm, respectively. When the recording head unit 22 and the ink tank unit 21 do not perform recording, the recording head unit 22 and the ink tank unit 21 return to the home position where the cap unit 20 is located and stand by. When the standby of the recording head unit 22 at the home position reaches a certain time, the recording head unit is used to prevent the ink discharge surface (discharge port forming surface) of the recording head unit 22 from drying. 22 is capped.

  Note that the recording head unit 22 and the ink tank unit 21 used here may be integrally configured, or may be configured to be separable from each other.

  In the present embodiment, the inkjet recording apparatus employs a multi-pass recording method in which an image is formed by scanning a predetermined area on a recording medium a plurality of times. In addition, a plurality of types of ink used for image formation are prepared so that the surface tensions are roughly aligned.

<Ink composition>
Next, the ink used in this embodiment will be described. Hereinafter, “parts” and “%” are based on mass unless otherwise specified.

Preparation of black 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] is prepared. 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.

  Then, 600 g of the polymer solution, 100 g of carbon black, and 300 g of ion-exchanged water are mixed and mechanically stirred for a predetermined time, and then the non-dispersed material including coarse particles is removed by centrifugal treatment to obtain a black dispersion liquid. To do. The resulting black dispersion had a pigment concentration of 10% by mass.

(2) Preparation of ink Ink preparation uses the above black dispersion. The following components are added to the above black dispersion, and after sufficiently mixing and stirring, pressure filtration is performed with a micro filter having a pore size of 2.5 μm to prepare a pigment ink having a pigment concentration of 5 mass%. Thus, the black ink used in this embodiment was produced.
Black dispersion 50 parts Zonyl FSO-100 (manufactured by DuPont) 0.05 parts Glycerin 10 parts Triethylene glycol 10 parts Acetylene glycol EO adduct 0.5 parts Triethanolamine 0.5 parts Ion-exchanged water remainder

-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. Mix and dilute with ion exchange water to make a homogeneous 50 wt% polymer aqueous solution.

  200 g of the polymer solution, C.I. I. 100 g of 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 including coarse particles is removed by a centrifugal separation process to obtain a cyan dispersion. The obtained cyan dispersion had a pigment concentration of 10% by mass.

(2) Preparation of ink For the preparation of ink, the above cyan dispersion is used. The following components are added to the cyan dispersion, and after sufficiently mixing and stirring, pressure filtration is performed with a microfilter having a pore size of 2.5 μm to prepare a pigment ink having a pigment concentration of 2 mass%. Thus, the cyan ink used in this embodiment was produced.
Cyan dispersion 20 parts Zonyl FSO-100 (manufactured by DuPont) 0.05 parts Glycerin 10 parts Diethylene glycol 10 parts Acetylene glycol EO adduct 0.5 part Triethanolamine 0.5 part Ion-exchanged water remainder

-Preparation of magenta 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 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 wt% polymer aqueous 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. The obtained magenta dispersion had a pigment concentration of 10% by mass.

(2) Preparation of ink The ink is prepared using the magenta dispersion. The following components are added to the above magenta dispersion, and after sufficiently mixed and stirred, pressure filtration is performed with a micro filter having a pore size of 2.5 μm to prepare a pigment ink having a pigment concentration of 4% by mass. Thus, the magenta ink used in this embodiment was produced.
Magenta dispersion 40 parts Zonyl FSO-100 (manufactured by DuPont) 0.05 parts Glycerin 10 parts Diethylene glycol 10 parts Acetylene glycol EO adduct 0.5 parts Triethanolamine 0.5 parts

Preparation of yellow ink (1) Preparation of dispersion First, the anionic polymer P-1 is neutralized with an aqueous potassium hydroxide solution and diluted with ion-exchanged water to prepare 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. The resulting yellow dispersion had a pigment concentration of 10% by mass.

(2) Preparation of ink The following components are mixed, sufficiently stirred and dissolved / dispersed, followed by pressure filtration through a microfilter having a pore size of 1.0 μm to prepare a pigment ink having a pigment concentration of 4% by mass. Thus, the yellow ink used in this embodiment was produced.
Yellow dispersion 40 parts Zonyl FSO-100 (manufactured by DuPont) 0.05 parts Glycerin 9 parts Ethylene glycol 10 parts Acetylene glycol EO adduct 1 part Triethanolamine 0.5 part Ion-exchanged water remainder

-Production of Light Cyan Ink (1) Production of Dispersion A cyan dispersion having a pigment concentration of 10% by mass is produced by the same raw material and production method as described for the production of the cyan ink of this embodiment.

(2) Preparation of ink For the preparation of ink, the above cyan dispersion is used. The following components are added to the cyan dispersion, and after sufficiently mixing and stirring, pressure filtration is performed with a microfilter having a pore size of 2.5 μm to prepare a pigment ink having a pigment concentration of 0.4 mass%. Thus, the light cyan ink used in this embodiment was produced. The light cyan ink has the same color material as the cyan ink and has a different color material density from the cyan ink.
Cyan dispersion liquid 4 parts Zonyl FSO-100 (manufactured by DuPont) 0.025 parts Glycerin 10 parts Diethylene glycol 10 parts Acetylene glycol EO adduct 0.5 parts Triethanolamine 1.0 part Ion-exchanged water remainder

-Production of Light Magenta Ink (1) Production of Dispersion A magenta dispersion having a pigment concentration of 10% by mass was produced by the same raw material and production method as described for the production of the magenta ink of this embodiment.

(2) Preparation of ink The ink is prepared using the magenta dispersion. The following components are added to the above magenta dispersion, and after sufficiently mixing and stirring, pressure filtration is performed with a micro filter having a pore size of 2.5 μm to prepare a pigment ink having a pigment concentration of 0.8% by mass. Thus, the light magenta ink used in this embodiment was produced. Light magenta ink has the same color material as magenta ink and has a different color material density from magenta ink.
Magenta dispersion 8 parts Zonyl FSO-100 (manufactured by DuPont Co., Ltd.) 0.025 parts Glycerin 10 parts Diethylene glycol 10 parts Acetylene glycol EO adduct 0.5 parts Triethanolamine 1.0 part Ion-exchanged water balance Table 1 The value of the surface tension of the ink produced as described above and used in this embodiment is shown.

  In the ink used in this embodiment, in order to solve the problem of the bleeding phenomenon, the amount of the fluorosurfactant is adjusted so that the surface tension is as uniform as possible. In general, a surfactant is used as a penetrating agent in order to improve the penetrability of the ink with respect to a recording medium dedicated for inkjet. As the amount of the surfactant added is increased, the property of lowering the surface tension of the ink becomes stronger, and the wettability and permeability of the ink with respect to the recording medium are improved. Among the surfactants, the fluorosurfactant exhibits an excellent surface active effect with a small addition amount, and thus realizes lower surface tension and excellent wettability.

  In this embodiment, 0.05 mass% of FSO-100 is added to cyan ink, magenta ink, yellow ink, and black ink, and 0.025 mass% of FSO-100 is added to light cyan ink and light magenta ink. All of the prepared inks have a surface tension of about 27 to 29 dyn / cm. This has the effect of suppressing beading. If ink with high surface tension is used on a recording medium that has very low or no penetrability of water-based ink such as printing paper or PVC sheet, the ink does not spread easily on the surface of the recording medium. It occurs remarkably. Therefore, the preferable surface tension of the ink used for the recording medium having a considerably low or no permeability is 30 dyn / cm or less.

  The light cyan ink and the light magenta ink have a low surface tension even though the added FSO-100 is 0.025% by mass as compared with other inks. This is because light cyan ink and light magenta ink have a smaller amount of color material than other inks.

<Recording medium>
A description will be given of a printing paper having a very low water-based ink permeability as compared with an inkjet paper. The printing main paper is a paper used for the main printing in the offset printing. The main printing paper is made from pulp and used as it is. The coated paper is made by smoothly coating the surface of the paper with a white pigment or the like. Of these, coated paper is more prominent in image recording and drying effects due to ink overflow in ink jet recording. The coating layer is a sizing agent (synthetic resin, etc.) that restricts the liquid absorption of the gaps between pulps and prevents bleeding of the aqueous pen, and a filler (kaolin, etc.) that improves opacity, whiteness, smoothness, etc. This is a mixed paint such as a paper strength enhancer (starch or the like) applied around several to 40 g / m ² . The coated paper has capillaries with a normal distribution centered around a radius of about 0.06 μm, and moisture is infiltrated by a large number of capillaries (capillary phenomenon). However, since the pore volume is much smaller than that of ink-jet dedicated paper, the permeability of water-based ink is low, and ink overflows on the surface of the paper, and image problems and drying problems become prominent. In this embodiment, OK top coat + EF paper (manufactured by Oji Paper Co., Ltd., basis weight 157.0 g / m ² ), which is one of printing coated papers, is used as a recording medium with low water-based ink permeability.

  Next, a description will be given of a PVC sheet that has no permeability at all as compared with the ink jet dedicated paper. A vinyl chloride sheet is a soft sheet produced by adding a plasticizer using vinyl chloride resin as a main raw material. PVC sheets are used in many products such as tarpaulins, canvases, and wallpaper because they are excellent in printability and embossing properties (such as embossing by embossing) in gravure printing and screen printing. Since vinyl chloride resin is the main raw material, there is no penetrability of water-based ink, and the ink overflows on the surface of the paper, causing image problems and drying problems to be prominent. In this embodiment, white glossy vinyl chloride adhesive (gray glue) (manufactured by Kimoto Co., Ltd., thickness 100 μm) is used as a recording medium having no water-based ink permeability.

  As a method for evaluating the permeability of the ink to the recording medium, the JAPAN TAPPI paper pulp test method No. 1 was used. 51, “Bristow method” described in “Method for testing liquid absorbency of paper and paperboard”. The outline is as follows.

A certain amount of ink is poured into a holding container having an opening slit of a predetermined size, and is brought into contact with a recording medium that is processed into a strip shape and wound around a disk through the slit. While the position of the holding container is fixed, the disk is rotated and the area (length) of the ink band transferred to the recording medium is measured. The transfer amount (ml / m ² ) per unit area can be calculated from the area of the ink band. This transfer amount (ml / m ² ) indicates the amount of ink absorbed by the recording medium in a predetermined time. Here, the predetermined time is defined as a transition time. The transition time (millisecond ^1/2 ) corresponds to the contact time between the slit and the recording medium, and is converted from the speed of the disk and the width of the aperture slit.

The transfer amount with respect to the water-based ink, which is measured for a general printing coated paper by the Bristow method, is less than 20 ml / m ² at a transfer time of 1 second. In particular, in the case of OK top coat + EF paper, a value slightly smaller than 10 ml / m ² is obtained.

The recording medium to which the recording method of the present embodiment is applied includes a recording medium with low ink permeability (low-absorbing recording medium) such as this print-coated paper, and a recording medium without ink permeability such as a vinyl chloride sheet. However, the present invention is not limited to this, and other recording media may be used. For example, many ink-jet dedicated papers have an ink transfer amount measured by the Bristow method of 30 ml / m ² or more, but some transfer amounts are lower than 20 ml / m ^2. It can be said that it is a low-absorbency recording medium although it is an inkjet-only paper. Even for such a recording medium, the effect can be obtained by using the recording method of the present embodiment.

<Bleed phenomenon>
When an image is formed on a recording medium having low or no ink permeability, a bleed phenomenon appears remarkably. The mechanism of the bleed phenomenon is considered to be related to the difference in surface tension between the inks. The ink absorption amount and ink absorption speed of the recording medium are limited for each type of recording medium. Therefore, if an ink exceeding the limit is absorbed, a plurality of ink droplets exist in a liquid state before being absorbed by the recording medium, and when these ink droplets come into contact with each other, the surface from the ink droplet side having a low surface tension is observed. Ink flows into the ink droplet side with high tension. This is because surface tension and the like work to make the interface energy uniform. The ink flows in a short time so that the ink with low interfacial energy (ink with low surface tension) covers the ink with high interfacial energy (ink with high surface tension).

  FIG. 2 is a diagram illustrating an ink droplet in which a bleed phenomenon occurs. This phenomenon can be easily confirmed when two types of inks having different surface tensions are dropped simultaneously on a glass as a non-absorbing recording medium so that the edges of the ink droplets come into contact with a dropper. FIG. 2A shows the state of the ink droplet in which the bleed phenomenon has occurred, and FIG. 2B shows the state of the ink droplet viewed from the side. Such bleed phenomenon due to ink absorbability and ink absorption speed appears remarkably in a recording medium having a considerably low permeability or no penetrability as compared with ink jet dedicated paper.

  FIG. 3 is a diagram showing the state of an image in which image defects are caused by the bleed phenomenon, and the state of an image in which the bleed phenomenon is suppressed by forming an image by mixing light cyan ink and cyan ink. Here, an image is formed on OK topcoat + paper by a multi-pass recording method, and after the ink is fixed and dried, the image is observed from above. The ink application amount (Duty) is defined as 100% duty when one dot of ink is applied to an area of 1/1200 inch square (1200 dpi square).

  FIG. 3A shows a case where a solid image A (single color 100% duty) using cyan ink and a solid image B (single color 100% duty) using yellow ink form an adjacent image. The cyan ink image A flows into the cyan ink image A side so that the yellow ink bleeds from the adjacent boundary portion of the solid image A (hereinafter referred to as cyan ink image A) using cyan ink and the solid image B (hereinafter referred to as yellow ink image B) using yellow ink. You can see how bad things happened. As described above, the surface tension of cyan ink and yellow ink is about 28 to 29 dyn / cm. Specifically, as shown in Table 1, the surface tension of cyan ink is 29.2 dyn / cm, and the surface tension of yellow ink is 28.0 dyn / cm. This is a value adjusted so that the bleed phenomenon does not substantially occur in the ink jet dedicated paper. However, in a recording medium with low ink permeability such as OK top coat + paper, bleeding occurs due to this slight difference.

  The evaluation method of the bleed phenomenon includes not only visual measurement but also a method of quantifying the bleed length L using a personal image quality evaluation system Personal IAS (Quality Engineering Associates) (based on ISO 13660). In this embodiment, this method is adopted, and the bleed phenomenon is evaluated by the bleed length L. In the present embodiment, the bleeding length (bleed length L) from the adjacent boundary between the cyan ink image A and the yellow ink image B shown in FIG. 3A to the end where the yellow ink flows into the cyan ink image A is calculated. Called the bleed length. The bleed length varies depending on the difference in surface tension between inks.

  Table 2 shows the measurement result of the bleed length L in FIG. 3A when the surface tension of the cyan ink is changed. An image in which a solid image using cyan ink (monochromatic 100% duty) with a changed surface tension and a yellow ink image B (monochromatic 100% duty) are adjacent to each other is formed on an OK topcoat + paper by a multi-pass recording method. After the ink is fixed and dried, the bleed length L is measured. According to the surface tensions of the cyan ink used of 20.1, 25.9, and 29.2 dyn / cm, solid images with cyan ink are referred to as cyan ink images A_1, A_2, and A_3.

  Here, the surface tension of the cyan ink was changed by changing the addition amount of Zonyl FSO-100 (manufactured by DuPont), which is a fluorine-based surfactant. As described above, this generally utilizes the property that the surface tension of the ink decreases as the amount of the surfactant added to the ink increases. FIG. 4 is a graph showing changes in surface tension when the amount of zonyl FSO-100 added to cyan ink is increased. In the present embodiment, the difference in the amount of the surfactant contained in the ink mainly causes the level relationship of the surface tension. In general, even if the surfactant is included in the same amount, there may be a slight difference in the surface tension depending on the type and amount of the coloring material, solvent, polymer, and the like included in the ink.

  From Table 2, when the surface tension of cyan ink is lower, the ink flows from the cyan ink image to the yellow ink image, and when the surface tension is higher for cyan ink, the ink from the yellow ink image to the cyan ink image is obtained. Can be seen. In this way, it can be confirmed that when the relationship between the levels of the surface tension is reversed, the direction in which the ink flows due to the bleed phenomenon also changes in the opposite direction. It can also be confirmed that the bleed length L increases as the difference in surface tension increases.

  In general, it is considered that the bleed phenomenon occurs when there is a difference in surface tension between inks. However, on the other hand, a bleed phenomenon may occur between inks having the same surface tension, and it is considered that a driving force that causes the bleed phenomenon is acting in addition to the surface tension. In addition, the surface tension can be measured only from the liquid ink, and the surface tension of the image formed on the recording medium can only be estimated from the liquid ink. However, since the surface tension includes a static surface tension and a dynamic surface tension, it may be considered that the surface tension of the ink in the liquid state does not match the bleed phenomenon of the image on the recording medium.

  In this embodiment, the force that causes the bleeding phenomenon is expressed as “bleed value”, and the bleeding phenomenon is suppressed by optimizing the bleeding value of the image formed on the recording medium.

<Bleed value>
Hereinafter, the bleed value will be specifically described.

  In FIG. 3A, the yellow ink image B flows into the cyan ink image A, and a bleed phenomenon occurs. At this time, the cyan ink image A into which the yellow ink has flowed is expressed as having a low bleed value, and the yellow ink image B into which the yellow ink has flowed toward the cyan ink image A is expressed as having a high bleed value.

  For each ink used in the present embodiment, a solid image as shown in FIG. 3A was formed on the recording medium, the bleed length was measured, and the relationship between the bleed values was confirmed. The result was as follows. In order of increasing bleed value, light magenta ink≈light cyan ink >> yellow ink >> black ink≈magenta ink> cyan ink. Accordingly, with the yellow ink having the middle bleed value as a reference, the ink used in the present embodiment is classified into an ink group having a lower bleed value than the yellow ink and an ink group having a higher bleed value than the yellow ink. Then, black ink, cyan ink, and magenta ink are classified into an ink group having a low bleed value, and light cyan ink and light magenta ink are classified into an ink group having a high bleed value. For simplicity, ink classified into an ink group having a low bleed value is referred to as ink having a low bleed value, and ink classified into an ink group having a high bleed value is referred to as ink having a high bleed value.

  Effectiveness of optimizing the bleed value of an image formed on a recording medium by using yellow ink as a standard for ink group classification, light cyan ink as a high bleed ink, and cyan ink as a low bleed ink The sex will be explained.

  As shown in FIG. 3A, as described above, when an image in which the cyan ink image A and the yellow ink image B are adjacent to each other is formed on the OK top coat + paper by the multi-pass recording method, an image defect occurs due to the bleeding phenomenon. It is a figure which shows the mode of an image. In FIG. 3A, the yellow ink flows from the adjacent boundary between the cyan ink image A and the yellow ink image B to the cyan ink image A side having a low bleed value.

  On the other hand, in FIG. 3B, instead of forming the cyan ink image A having a low bleed value, the bleed phenomenon is caused by forming a mixed color image AA by mixing the cyan ink and the light cyan ink having a high bleed value. The state of the suppressed image is shown. The cyan ink image A becomes a mixed color image AA having a bleed value increased by using light cyan ink, and is balanced with the bleed value of the yellow ink image B, so that the bleed phenomenon is suppressed.

<Bleed value adjustment by ink application timing control>
Further, the amount of light cyan ink applied to balance the yellow ink image B with the bleed value varies depending on the timing at which the light cyan ink is applied. In the present embodiment, an image is formed using a multi-pass printing method. By switching the mask (distribution pattern of binary image data for ejecting ink from the recording head to a plurality of scans) used in multi-pass printing, the timing at which ink is applied is controlled.

  Hereinafter, the light cyan ink application amount and the mask in which the bleed values of the mixed color image AA and the yellow ink image B are balanced will be described in detail.

  5 and 6 are diagrams showing masks used in multi-pass printing. Here, an image is formed by eight recording scans for a predetermined area of 5 × 5 dots. Masks A, B, C, and D in which eight mask patterns corresponding to the first to eighth printing scans are arranged are shown in FIGS. 5 (a), 5 (b), 6 (a), and 6 (b), respectively. Has been. Each mask pattern shows the area where ink is ejected in black, and each mask is set so that ink is ejected at 100% duty when all eight mask patterns are overlaid. By performing a logical product (AND) process of a part of binary image data (size of 5 × 5 dots) for ejecting ink from the print head and a mask pattern corresponding to each print scan (each pass) In addition, it is possible to generate ejection data for each scan for ejecting ink in each recording scan.

  In both “mask A” in FIG. 5A and “mask B” in FIG. 5B, ink is ejected only in the last four printing scans out of a total of eight printing scans, and the first four printings are performed. This is a sorting mask that does not eject ink during scanning. A case where “mask A” in FIG. 5A is set for cyan ink and “mask B” in FIG.

  Next, a case where “mask A” in FIG. 5A is set for cyan ink and “mask C” in FIG. In mask set 2, cyan ink is ejected in the fifth, sixth, seventh and eighth recording scans out of a total of eight recording scans, and light cyan ink is used in the third, fourth, fifth and sixth recording scans in a total of eight recording scans. Are ejected in the recording scan. Accordingly, only the light cyan ink is ejected in the second and third printing scans, and both cyan ink and light cyan ink are ejected in the same scanning in the second and sixth printing scans.

  Furthermore, a case where “mask A” in FIG. 5A is set for cyan ink and “mask D” in FIG. In the mask set 3, the light cyan ink is ejected only in the first four recording scans out of the total eight recording scans, and is not ejected in the latter four recording scans. Therefore, the cyan ink and the light cyan ink are not ejected in the same scan, and the cyan ink is ejected after all the ejection of the light ink is completed.

  Table 3 shows the measurement result of the bleed length LL when the light cyan ink is mixed with 0 to 20% duty with cyan ink (100% duty) using the mask sets 1 to 3. Here, the direction of ink flow from the yellow ink image B to the mixed color image AA is “+”, the direction of ink flow from the mixed color image AA to the yellow ink image B is “−”, and the bleed length LL is expressed. The magnitude of the length LL is determined by the absolute value of the numerical value.

  From Table 3, when the mask set 1 is used, the bleed length LL when the light cyan ink is applied with 5% duty is as short as 0.1. In other words, when a distribution mask is used in which light cyan ink is ejected in the same recording scan as cyan ink, if a mixed color image AA is formed by mixing light cyan ink with 5% duty color, the bleed value is balanced with the yellow ink image B. Is suppressed.

  Next, when the mask set 2 is used, the bleed length LL when the light cyan ink is applied with 10% Duty is as short as 0.1. That is, in the case of using a distribution mask that is ejected in the same recording scan only twice among the four recording scans in which each of cyan ink and light cyan ink is ejected, the mixed color image AA is formed by mixing light cyan ink with 10% duty. , The bleeding phenomenon is suppressed.

  Further, when the mask set 3 is used, the bleed length LL when the light cyan ink is applied with 15% duty is as short as 0.2. That is, when using a sort mask that is not ejected in the same recording scan among the four recording scans in which cyan ink and light cyan ink are ejected, if the mixed color image AA is formed by mixing light cyan ink with 15% duty color, The phenomenon is suppressed.

  Summarizing the duty and distribution mask of light cyan ink to be mixed with cyan ink (100% duty), the following results are obtained. When the mask set 1 is used, when the light cyan ink is 5% Duty, the formed mixed color image AA has a bleed value balanced with the yellow ink image B (single color 100% Duty). When the mask set 2 is used, when the light cyan ink is 10% Duty, the formed mixed color image AA has a balanced bleed value with the yellow ink image B. When the mask set 3 is used, when the light cyan ink is 15%, the formed mixed color image AA has a balanced bleed value with the yellow ink image B.

  From the above results, the following was confirmed. When a predetermined amount of light cyan ink (ink with high bleed value) is mixed with cyan ink (ink with low bleed value) to form an image, the bleed phenomenon can be suppressed by balancing with the bleed value of the yellow ink image. Furthermore, the predetermined amount of light cyan ink required for balancing the yellow ink image and the bleed value varies depending on the timing at which the light cyan ink is applied. This is because the light cyan ink and the cyan ink are more easily mixed with each other in the same recording scan, and the bleed value of the mixed-color image AA matches the bleed value of the yellow ink image B with a small amount of light cyan ink. It is.

  In the present embodiment, the above phenomenon is utilized to suppress the bleed phenomenon. That is, the timing (ink application timing) at which cyan ink (ink having a low bleed value) and light cyan ink (ink having a high bleed value) are applied is controlled according to the ink profile. The ink profile is a table that determines the application amount of each of a plurality of types of ink according to the RGB values in a predetermined area of the image to be formed. When the ink application timing control in the present embodiment is performed, the bleed phenomenon can be suppressed while using a general ink profile as it is. That is, it is not necessary to create a new ink profile in consideration of conditions such as lowering the ink application amount in a predetermined region or limiting a specific ink application amount, and the bleed phenomenon can be suppressed.

  Hereinafter, the ink application timing control in the present embodiment will be described more specifically using yellow ink, cyan ink, and light cyan ink.

  When the mixed color image AA and the yellow ink image B using the light cyan ink and cyan ink shown in FIG. 3B are formed adjacent to each other, bleeding is likely to occur at an adjacent boundary portion particularly in a low-absorbing or non-absorbing recording medium. Therefore, the bleeding at the adjacent boundary between the mixed color image AA and the yellow ink image B is suppressed by controlling the timing of ejecting the respective inks according to the ink profiles of the light cyan ink and the cyan ink.

  FIG. 7 is an ink profile showing light cyan ink and cyan ink application amount (%) in each gradation from White to Cyan. The gradation value of White, which is the point of the RGB value (255, 255, 255), is 0, and the gradation value of the RGB value (0, 255, 255) with the strongest Cyan taste is 255. The dotted ink profile indicates the amount of light cyan ink applied, and the solid ink profile indicates the amount of cyan ink applied. From FIG. 7, since the light cyan ink and the cyan ink are applied to the same predetermined area after the gradation value becomes 64 or more, the ink application timing control of this embodiment is performed in the ink profile section where the gradation value is 64 or more. Is called.

  Table 4 confirms when the yellow ink (100% duty) image is adjacent to the predetermined area of each gradation value and when the cyan ink and the light cyan ink are applied, the bleeding is most suppressed. Results are shown. In order to obtain the result of Table 4, the mask set 1, 2, and 3 shown in Table 3 is set for light cyan ink and cyan ink in each gradation to form the image of FIG. The bleed length LL is compared. Thereby, it is confirmed which bleed phenomenon with the yellow ink image B is most suppressed when any of the mask sets 1, 2, 3 is set.

  As shown in the results of Table 4, the bleed length LL is minimized when the mask set 3 shown in Table 3 is set in the section 1 (gradation value of 64 or more and less than 184). When the gradation value is 184, the amount of ink applied in the predetermined area is 10% Duty for Lc ink and 55% Duty for C ink. Therefore, the ratio of the Lc ink amount to the total ink amount applied to the predetermined area is About 15%. In the section 1 in which the ratio of the Lc ink amount to the total ink amount applied to the predetermined region is about 15% or more and less than 100%, the ratio of the Lc ink amount to the total ink amount applied to the predetermined region is relatively high. The influence of Lc ink having a high bleed value is large.

  FIG. 8 is a diagram showing a mask to which ink is applied at an equal ratio in all recording scans. When normal recording using a mask as shown in FIG. 8 is performed, the influence of Lc ink having a high bleed value is large, so that the ink flows from the mixed color image AA of C ink and Lc ink to the adjacent yellow ink image B. Bleed occurs. Therefore, in the present embodiment, in order to reduce the influence of the Lc ink having a high bleed value, the application of the Lc ink is completed in the scan before the C ink, and the Lc ink is not applied in the same recording scan as the C ink. Set 3 By performing such ink application timing control for the section 1, bleeding is suppressed.

  Next, in section 2 (grayscale value 184 or more and less than 218), when mask set 2 shown in Table 3 is set, bleed length LL is minimized. The respective ink application amounts in the predetermined area at the gradation value 218 are 5% Duty for Lc ink and 94% Duty for C ink. Therefore, the ratio of the Lc ink amount to the total ink amount applied to the predetermined area is About 5%. In the section 2 in which the ratio of the Lc ink amount to the total ink amount applied to the predetermined region is 5% or more and less than 15%, the ratio of the Lc ink amount to the total ink amount applied to the predetermined region is relatively high. The effect of Lc ink having a high bleed value is slightly large. Therefore, in the present embodiment, the mask set 2 is set so that the Lc ink and the C ink are ejected in two identical recording scans so that the influence of the Lc ink having a high bleed value is slightly reduced. By performing such ink application timing control for the section 2, bleeding is suppressed.

  Further, in section 3 (gradation value 218 or more and 255 or less), when mask set 1 shown in Table 3 is set, bleed length LL is minimized. Accordingly, in this embodiment, the Lc ink and the C ink are subjected to four identical printing scans in the section 3 in which the ratio of the Lc ink amount to the total ink amount applied to the predetermined region is 0% or more and less than 5%. The mask set 1 to be discharged is set.

  As described above, in the present embodiment, by controlling the number of times the Lc ink and the C ink are ejected in the same recording scan according to the ratio of the Lc ink amount to the total ink amount applied to the predetermined region. , Suppress bleed. More specifically, when the ratio of the Lc ink amount to the total ink amount applied to the predetermined area is relatively high, the Lc ink is ejected in the first recording scan and the C ink is ejected in the second recording scan. When the ratio of the Lc ink amount to the total ink amount applied to the predetermined area decreases, the number of times that the Lc ink and the C ink are ejected in the same recording scan is increased. By performing such ink application timing control, the bleed value of the mixed color image composed of the ink having a relatively high bleed value and the ink having a relatively low bleed value is used as the reference for the ink group classification of the bleed value. Balance with the bleed value of the resulting image.

<Configuration of control system of recording system>
FIG. 9 is a block diagram showing the configuration of the control system of the recording system in the present embodiment.

  The recording system in the present embodiment includes a host computer 91 and an ink jet recording apparatus 90.

  The host computer (image input unit) 91 transmits RGB multi-valued image data stored in various storage media such as a hard disk to the image processing unit of the inkjet recording apparatus 90.

  The image processing unit of the ink jet recording apparatus 90 includes an MPU 901 (Micro Processor Unit), an ASIC 902, and the like which will be described later. Multi-value image data can also be received from an image input device such as a scanner or a digital camera connected to the host computer 91. The image processing unit performs image processing to be described later on the received multi-value image data. That is, binary image data (ejection data) for ejecting a plurality of types of ink from the recording head is generated by color conversion and binarization processing. By mask pattern processing for distributing binary image data to a plurality of printing scans, ejection data for each scan in a format that can be transferred to the printing head is generated.

  The image output unit of the inkjet recording apparatus 90 forms an image by applying ink to a recording medium based on ejection data for each scan of at least three or more types of ink generated by the image processing unit. The image output unit is controlled by the MPU 901 in accordance with a program stored in the ROM 903. The RAM 904 is used as a work area or temporary data storage area for the MPU 901. The MPU 901 controls the carriage drive system 907, the recording medium transport drive system 908, the printhead recovery drive system 909, and the printhead drive system 910 via the ASIC 902. The MPU 901 is configured to be able to read / write from / to the print buffer 905 and the mask buffer 906 that can be read / written from the ASIC 902.

  The print buffer 905 temporarily stores binary image data (ejection data) converted into a format that can be transferred to the recording head.

  The mask buffer 906 temporarily stores a predetermined mask pattern to be AND-processed as necessary for the binary image data transferred from the print buffer 905 when transferred to the recording head. A plurality of sets of mask patterns that can be selected for mask pattern processing are prepared in the ROM 903, and the corresponding mask patterns are read from the ROM 903 and temporarily stored in the mask buffer 906 during actual recording.

  In the present embodiment, the image processing unit is configured in the inkjet recording apparatus 90, but the image processing unit may be configured in the host computer 91. Alternatively, the image processing unit may be configured as an image processing device that can communicate with the host computer 91 and the image output unit of the inkjet recording apparatus 90.

<Image processing>
FIG. 10A is a flowchart of image processing in the present embodiment.

  First, multivalued image data in RGB format is input from the host computer (image input unit) 91 to the image processing unit. In step S1001, the image processing unit converts multi-valued image data in RGB format into multiple values corresponding to each of a plurality of types of ink (C, M, Y, K, Lc, and Lm ink) used for image formation by color conversion. Convert to image data.

  Next, in step S1002, the image processing unit develops multi-value image data corresponding to various inks into binary image data of various inks according to the stored pattern. Thereby, binary image data for ejecting each of a plurality of types of ink is generated.

  In step S1003, the image processing unit selects a mask set (distribution pattern set) according to the ink image data in the predetermined region. Details of the process of selecting a mask set (mask pattern selection process) will be described later with reference to FIG. This step can be executed in parallel with step S1002.

  In step S1004, the image processing unit sets the mask set selected in step S1003 to the binary image data of the C, M, Y, K, Lc, and Lm ink generated in step S1002. Based on the set mask set, mask pattern processing (discharge data distribution) for distributing binary image data (discharge data) to a plurality of printing scans is performed. By the mask pattern processing, ejection data for each scan in a format that can be transferred to the recording head is generated.

  In step S1005, the recording head 22 forms an image on the recording medium based on the ejection data for each scan transferred from the image processing unit.

  FIG. 10B is a flowchart of the mask set selection process performed in step S1003.

  In this embodiment, each of the inks used for image formation is classified into an ink group having a high bleed value and an ink group having a low bleed value based on yellow ink. A high-bleed and low-bleed ink is applied for each predetermined area so that the mixed color image formed with high and low bleed inks and the image with yellow ink as the ink group classification balance with the bleed value. Different timing. In this embodiment, a multi-pass printing method is used for image formation, and the timing at which ink is applied is controlled by switching the mask used in multi-pass printing. With the flow chat shown in FIG. 10B, a mask set is selected according to the amount of ink applied in a predetermined region.

  In step S1011, the image processing unit determines which section of the ink profile the predetermined area corresponds to based on the multi-value image data corresponding to each ink in the predetermined area. Taking the ink profile in which Lc and C inks are ejected as shown in FIG. 7 as an example, the predetermined area is determined from the amount of Lc and C ink applied to the predetermined area. It is determined which of the other sections corresponds. An ink profile as shown in FIG. 7 is stored in the ROM 903.

  In steps S1012 to S1015, the image processing unit selects a mask set shown in Table 3 according to the determined ink profile section. The selected mask set is temporarily stored in the mask buffer 906.

  In this way, the bleed value of a predetermined region is optimized by controlling the timing of applying ink according to the ink profile. Specifically, when a plurality of images are formed adjacent to each other, the bleed value of the plurality of adjacent images is reduced by controlling the number of times the ink having a high bleed value and the low ink are ejected in the same scan. Adjust equally. Thereby, the remarkable bleeding phenomenon can be suppressed in the low absorption paper.

  In this embodiment, the cyan ink and the light cyan ink have been described as examples. However, with respect to the magenta ink and the light magenta ink, the bleed phenomenon can be suppressed by a similar method.

  In this embodiment, a multi-pass printing method is adopted in which an image is completed by 8 printing scans, but the number of printing scans is not limited to this. If the number of recording scans is large, a higher quality image is formed, and if the number of recording scans is small, an image can be formed in a shorter time. An ink profile section and a mask set corresponding to the ink profile section may be set so as to suppress the bleeding phenomenon according to the number of recording scans.

  In this embodiment, a multi-pass printing method is used, and a mask is used as a method for distributing ink ejection data to each printing scan. However, other distribution methods may be used.

  In this embodiment, each ink image is formed adjacently on a recording medium, and the bleed length is measured. Although the magnitude relationship between the bleed values can be obtained with high accuracy based on the measured bleed length, the surface tension value of the ink and the bleed value are often correlated. Even in the ink used in this embodiment, an image formed from an ink having a low surface tension has a high bleed value, and an image formed from an ink having a high surface tension has a low bleed value. Therefore, depending on the ink used, the ink application timing control may be performed by classifying the ink based on the value of the surface tension of the ink without measuring the bleed length.

[Second Embodiment]
In the first embodiment, the ink application timing control is performed by adjusting the number of times the light cyan ink is ejected in the same printing scan as the cyan ink. In the present embodiment, the ink application timing is controlled by adjusting the amount of light cyan ink ejected in the same recording scan as the cyan ink. Description of the same parts as those of the first embodiment is omitted.

<Bleed value adjustment by ink application timing control>
A difference from the first embodiment is that a mask E shown in FIG. 8 is used in this embodiment instead of the mask C in FIG. 5A set for the light cyan ink in the mask set 2 in Table 3. In the mask E shown in FIG. 8, light cyan ink is ejected in all of the eight recording scans. Compared to the mask C, the amount of ink ejected in one printing scan is about half in the mask E compared to the mask C.

  In this embodiment, the mask set 4 is set when the mask A in FIG. 5A is set for cyan ink and the mask E in FIG. 8 is set for light cyan ink. In the mask set 4, the amount of light cyan ink ejected in the same printing scan as that of cyan ink is 50% Duty at maximum. Also in the mask set 2, the amount of light cyan ink ejected in the same recording scan as that of the cyan ink is 50% Duty at maximum, which is almost the same as that of the mask set 4.

  Table 5 shows the bleed length LL of the mixed color image AA and the yellow ink image B shown in FIG. 3B when the light cyan ink is mixed with 0 to 20% duty with cyan ink (100% duty) using the mask set 4. The measurement results are shown. The bleed length LL is represented by “+” for the ink flow direction from the yellow ink image B to the mixed color image AA and “−” for the ink flow direction from the mixed color image AA to the yellow ink image B. The magnitude is determined by the absolute value.

  From Table 5, even in the case of the mask set 4 using the mask E instead of the mask C, the bleed length LL is the smallest when the light cyan ink is ejected by 10% Duty similarly to the mask set 2. That is, when the mask set 4 is used, similarly to the case of using the mask set 2, when the light cyan ink is mixed with 10% duty to form the mixed color image AA, the bleed value is balanced with the yellow ink image B, and the bleed phenomenon is suppressed. .

  Therefore, in the present embodiment, only “set mask set 2” in step S1013 in FIG. 10B is changed to “set mask set 4”, and everything else is the same as the image processing of the first embodiment. It is.

  When the mask C is set for the light cyan ink and when the mask E is set, if the bleed suppression effect is almost the same, the mask E has no deviation in the nozzle use area of the recording head, so that the head is used rather than the mask C. It is advantageous in terms of life. Further, since the amount of light cyan ink ejected together with cyan ink in one scan is smaller in the mask E than in the mask C, the same result is not obtained in the mask C and the mask E depending on the dot arrangement of the ink set and the sorting mask. Cases are also conceivable. Therefore, the mask set may be appropriately set in consideration of the head life and the bleed suppressing effect according to the ink set and the dot arrangement of the sorting mask.

  In the present embodiment and the first embodiment, a mask pattern having a recording scan in which no ink is ejected or a mask pattern in which ink is ejected at an equal rate in a plurality of scans in which the ink is ejected is used. Although used, it is not limited to this. For example, the mask G shown in FIG. 11A may be used instead of the mask A shown in FIG. 5A, and the mask H shown in FIG. 11B may be used instead of the mask D shown in FIG. Good. The mask G in FIG. 11A has a high ratio of ink ejected in the previous recording scan among the eight recording scans necessary to complete the image, and the mask H in FIG. This is a mask pattern in which the ratio of ink ejected by scanning is high. In this way, the bleed value of the mixed-color image is adjusted by biasing the ink ejection ratio to the previous scan and the subsequent scan. Further, the mask G and the mask H are advantageous in terms of the life of the nozzle because the nozzle use area of the recording head is wider than the mask A and the mask D.

[Third Embodiment]
In the first embodiment, ink in which the amount of the fluorosurfactant is adjusted so that the surface tension is as uniform as possible is used. In the present embodiment, an ink is used in which the amount of the fluorosurfactant is adjusted so that a surface tension difference between the inks is created. Description of the same parts as those of the first embodiment is omitted.

<Ink composition>
The composition of the black ink, cyan ink, magenta ink, and yellow ink of the present embodiment is the same as that of the first embodiment, and is therefore omitted. Hereinafter, the composition of light cyan ink and light magenta ink different from those of the first embodiment will be described.

-Production of Light Cyan Ink (1) Production of Dispersion A cyan dispersion having a pigment concentration of 10% by mass is produced by the same raw material and production method as described for the production of cyan ink in the first embodiment.

(2) Preparation of ink For the preparation of ink, the above cyan dispersion is used. The following components were added to the above cyan dispersion, mixed and stirred thoroughly, and then filtered under pressure 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 0.4 mass%. To do. Thus, the light cyan ink used in this embodiment was produced.
Cyan dispersion 4 parts Zonyl FSO-100 (DuPont fluorosurfactant) 0.05 parts Glycerin 10 parts Diethylene glycol 10 parts Acetylene glycol EO adduct (manufactured by Kawaken Fine Chemicals Co., Ltd.) 0.5 part Triethanolamine 1 0.0 part Ion-exchanged water balance

-Production of Light Magenta Ink (1) Production of Dispersion A magenta dispersion having a pigment concentration of 10% by mass is produced by the same raw material and production method as described for the production of magenta ink in the first embodiment.

(2) Preparation of ink The ink is prepared using the magenta dispersion. The following components are added to the above magenta dispersion, mixed and stirred thoroughly, and then filtered under pressure 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 0.8% by mass. To do. Thus, the light magenta ink used in this embodiment was produced.
Magenta dispersion 8 parts Zonyl FSO-100 (DuPont fluorine surfactant) 0.05 parts Glycerin 10 parts Diethylene glycol 10 parts Acetylene glycol EO adduct (manufactured by Kawaken Fine Chemical Co., Ltd.) 0.5 parts Triethanolamine 1 0.0 part Ion-exchanged water balance Table 6 shows the values of the surface tension of the ink used in this embodiment.

  In the ink used in this embodiment, light cyan (Lc) ink and light magenta (Lm) ink contain more fluorine-based surfactant Zonyl FSO-100 that has the effect of reducing the surface tension of the ink than in the first embodiment. It is added. In general, it is considered that the surface tension between the inks is as close as possible to the suppression of bleed, but in the ink application timing control of the present embodiment, the surface tension difference between the inks should be positively added. It can be set so that the deviation of the nozzle use area is reduced. Therefore, it is an advantage of this embodiment that bleeding can be suppressed while extending the life of the head. In this embodiment, the surface tension of light cyan ink and light magenta ink is adjusted to be lower than that of other inks (cyan, magenta, yellow, black). As a result, the surface tension in the first embodiment was 27.3 mN / m in the light cyan ink, whereas 23.8 mN / m in the present embodiment, and 27.4 mN / m in the light magenta ink in the first embodiment. In contrast to m, this embodiment is 24.5 mN / m.

<Bleed value adjustment by ink application timing control>
When the ink set of this embodiment is used, a distribution mask that suppresses the bleeding phenomenon in each gradation of the ink profile shown in FIG. 7 is examined. The result is as follows. In section 1 shown in FIG. 7, the bleed length LL is minimized when the same mask set 3 (mask A for cyan ink and mask D for light cyan ink) is set as in the first embodiment. In section 2 shown in FIG. 7, the bleed length LL was minimized when the mask set 5 (mask A shown in FIG. 5A for cyan ink and mask F shown in FIG. 12 for light cyan ink) was set. In section 3 shown in FIG. 7, the bleed length LL was minimized when mask set 4 (mask A shown in FIG. 3A for cyan ink and mask E shown in FIG. 8 for light cyan ink) was set. The above examination results are shown in Table 7 together with the results of the first embodiment for comparison.

  In section 1 shown in FIG. 7, since the ratio of the light cyan ink to the ink forming the predetermined area is relatively high, it is possible to suppress the bleeding phenomenon that the ratio of the light cyan ink ejected in the same printing scan as the cyan ink is low. Leads to. Therefore, the bleed value can be optimized by setting the light cyan ink in the previous scan and the mask pattern for ejecting the cyan ink in the subsequent scan as in the mask set 3, respectively.

  Subsequently, in the section 2 shown in FIG. 7, bleeding is suppressed when the mask F from which ink is ejected in the first to sixth passes is used for the light cyan ink. In the mask set 2 set in section 2 in the first embodiment, light cyan ink is ejected in the third to sixth passes, and in the fifth and sixth passes, it is ejected in the same printing scan as the cyan ink. Therefore, about 50% of the light cyan ink is ejected in the same recording scan as the cyan ink. On the other hand, when the mask set 5 is used, the light cyan ink is ejected in the first to sixth passes, and in the fifth and sixth passes, it is ejected in the same recording scan as the cyan ink, and about 33% of the light cyan ink is the cyan ink. Ejected in the same recording scan. When the mask F is used compared to the mask C, the amount of light cyan ink ejected in the same printing scan as the cyan ink is reduced. However, since the surface tension of the light cyan ink is adjusted to be low in this embodiment, the same effect as the light cyan ink in the section 2 of the first embodiment can be obtained even if the amount of ink ejected in the same recording scan is small. The mask F is advantageous in terms of nozzle life since the nozzle use area of the recording head is wider than the mask C.

  Further, in the section 3 shown in FIG. 7, bleeding is suppressed by using the mask E from which ink is ejected in all printing scans of 1 to 8 passes as light cyan ink. In the mask set 1 set in the section 3 in the first embodiment, since both the light cyan ink and the cyan ink are ejected in the printing scans in the 5th to 8th passes, the total amount of the light cyan ink applied to the predetermined area is cyan. It is ejected in the same recording scan as ink. On the other hand, in the mask set 4, light cyan ink is ejected in the 1st to 8th pass and cyan ink is ejected in the 5th to 8th pass printing scans. Is done. When the mask E is used compared to the mask B, the amount of light cyan ink ejected in the same recording scan as the cyan ink is reduced. However, as described above, the surface tension of the light cyan ink is adjusted to be low in this embodiment. The same effect as B can be obtained. Compared with the mask B, the mask E that ejects ink in all recording scans is advantageous in terms of head life because there is no bias in the nozzle use area of the recording head.

[Fourth Embodiment]
In the first to third embodiments, in order to suppress the bleed phenomenon between adjacent images, an ink profile that determines the applied amount of each ink in accordance with the relationship of the bleed value of each ink examined in advance and the RGB value is set. Based on this, the timing for applying the ink to the recording medium is determined. In this embodiment, a “bleed value adjustment pattern” is formed on a recording medium, and the actually generated bleed phenomenon is visually evaluated and acquired manually or automatically using a sensor or the like. The timing for applying each ink to the recording medium is determined for each region. Description of the same parts as those in the first to third embodiments is omitted.

  In the present embodiment, as a test output, a “bleed value adjustment pattern” is formed on the recording medium, and the actually generated bleed phenomenon is visually evaluated and acquired manually or automatically using a sensor or the like. Based on the above, the optimum mask of the image of each RGB value is determined. In the first to third embodiments, the optimal mask set is determined by calculation based on the ink bleed value and the ink profile. In the present embodiment, the bleed phenomenon actually occurring in the recording medium is evaluated. Based on the result, an optimal mask set is determined. Therefore, the bleed phenomenon can be more accurately suppressed. Hereinafter, the cause will be described in detail.

  The bleed phenomenon is that while one or more ink droplets permeate on a recording medium in a liquid state, ink droplets of different color materials come into contact with each other and the other color material mixes on one side. In other words, the boundary between ink droplets of different color materials is mixed. Therefore, when the same ink is compared under the same recording conditions, the bleed length is small for a recording medium with good permeability and the bleed length is large for a recording medium with poor permeability. This is because the ink droplet on the recording medium with good permeability is quickly absorbed by the recording medium, so that the bleeding phenomenon (movement of the coloring material) stops in a short time.

  Further, when comparing the same ink with the same recording medium, the bleed length is small when the number of scans until the completion of the image of the multi-pass printing method is large, and the bleed length is large when the number of scans is small. This is because when the number of scans is large, the number of dots of ink ejected in one scan is small (because the dot density is low), absorption into the recording medium and evaporation into the air proceed rapidly, and the bleed phenomenon ( This is because the movement of the coloring material stops in a short time.

  Further, for example, when comparing the same ink with the same recording medium and the same recording method, the bleed length is small in recording in a high temperature and low humidity environment, and the bleed length is large in recording in a high temperature and humidity environment. This is because in a high temperature and low humidity environment, the absorption to the recording medium and the evaporation to the air proceed more rapidly, so that the bleed phenomenon (movement of the coloring material) stops in a short time. For the same reason, for example, the bleed length is small when a dryer using air, hot air, or a heater is used.

  In the present embodiment, an adjustment pattern for checking the bleed phenomenon is formed on the recording medium under various actual recording conditions, and the bleed length and the optimum level of the bleed phenomenon are evaluated by visual observation or a sensor etc. Determine the optimal mask set for the RGB value image. As a result, the bleed value can be adjusted according to actual various recording conditions, and the bleed phenomenon can be more accurately suppressed.

  The use of the adjustment pattern is similar to “registration adjustment” that corrects ink dot landing deviation and “color calibration” that corrects the difference in color development due to changes in the ejection performance of the head. It is preferable to carry out under various conditions.

<Use of adjustment pattern>
FIG. 13 is a flowchart for registering an optimal mask set corresponding to each RGB value using the “bleed value adjustment pattern” in the present embodiment.

  First, in step S <b> 1301, the image processing unit of the inkjet recording apparatus 90 reads image data used for image formation of a “bleed value adjustment pattern” registered in advance from the ROM 903. Here, the read image data is multi-value image data in RGB format.

  In step S1302, the image processing unit develops multi-value image data corresponding to each ink into binary image data in accordance with the stored pattern. Thereby, binary image data for ejecting each of a plurality of types of ink is generated. Note that the image data read in step S1301 may be binary image data. In that case, this step is unnecessary.

  In step S1303, the image processing unit sets mask sets 1, 2, and 3 for binary image data of each ink. For each set mask set, mask pattern processing for distributing binary image data to a plurality of print scans is performed, and discharge data for each scan in a format that can be transferred to the print head is generated.

  In step S1304, the image output unit of the inkjet recording apparatus 90 forms a “bleed value adjustment pattern” on the recording medium based on the ejection data for each scan generated in step S1303. In this way, a total of three images are acquired: output result 1 when mask set 1 is selected, output result 2 when mask set 2 is selected, and output result 3 when mask set 3 is selected. .

  In step S1305, the user visually evaluates the output results 1 to 3 of the “bleed value adjustment pattern” acquired in step S1304, and manually inputs the evaluation result from an input unit such as a button of an inkjet recording apparatus. The image processing unit registers various setting values in the ROM 903 based on the input evaluation result. The various setting values are mask sets (corresponding information) corresponding to RGB values set so that the bleeding phenomenon is most suppressed. Alternatively, it is automatically evaluated by a sensor or the like, and various setting values for this time are registered in the ROM 903 based on the evaluation result.

  FIG. 14 is a diagram showing a “bleed value adjustment pattern” used in the present embodiment. The block A is configured such that each cyan gradation patch 40 (mixed color patch using cyan ink and light cyan ink) and a patch 41 of yellow ink (for example, 100% duty) are adjacent to each other. The patch 40 is eight patches (column 1 to column 8) other than white, in which the gradation from white to cyan is divided into nine levels. The yellow ink patch 41 is a repetition of the same patch (for example, 100% duty, RGB value (255, 255, 0)). In the block B, each magenta gradation patch 42 (mixed color patch using magenta ink and light magenta ink) and a patch 43 of yellow ink (for example, 100% Duty, RGB value (255, 255, 0)) are adjacent to each other. It is configured. The patches 42 are eight patches (column 1 to column 8) other than white, in which the gradation from white to magenta is divided into nine levels.

  Table 8 shows the RGB values of the patch 40 and the patch 42.

  After the “bleed value adjustment pattern” of FIG. 14 is formed on the recording medium in step S1304, the user visually evaluates the bleed performance, for example. The evaluation is performed by selecting a patch having the shortest bleed length, that is, the bleed phenomenon that is least noticeable in the column 1 of the block A among the output results 1 to 3 of the “bleed value adjustment pattern” formed on the recording medium. Thus, a mask set in which the bleed phenomenon of the RGB value (224, 255, 255) image and the yellow ink image is most inconspicuous is determined. For the remaining columns 2 to 8 of the block A and the columns 1 to 8 of the block B, the patch with the least noticeable bleeding phenomenon is selected. Based on the selected patch, an optimal mask set of each RGB value image shown in Table 8 is determined (corresponding information acquisition). Based on these mask sets, an optimal mask set of an image of another RGB value may be complemented. Alternatively, the same evaluation may be performed by increasing the number of patches formed on the recording medium so as to adjust the bleed value more accurately.

  14 may be automatically evaluated using a sensor or the like after the “bleed value adjustment pattern” of FIG. 14 is formed on the recording medium in step S1304. In this case, the carriage (not shown) on which the recording head 22 is mounted also includes a color sensor for measuring the color patch and detecting the recording medium. A color sensor generally acquires RGB values as measured values. The bleed length is measured as a change in color with this color sensor, and a mask pattern that is predicted to have the least noticeable bleed phenomenon may be selected. In addition, the personal image quality evaluation system Personal IAS (Quality Engineering Associates) (ISO 13660 compliant) described above may be used.

[Other Embodiments]
In the first to fourth embodiments, the description of the range of the image for which the ink application timing control is performed is omitted. The entire region) is preferred. However, in consideration of the life of the recording head and the like, the effect can be obtained even if the ink application timing control is performed only on the inner side (end) of the boundary between adjacent images.

  Further, in the mask set 1, the mask A and the mask B shown in FIG. 5 are used, in which ink is ejected by four recording scans out of all eight recording scans. However, the mask pattern is not limited to this. For example, the mask E shown in FIG. 8 in which ink is ejected in all printing scans of 1 to 8 passes may be applied to both cyan ink and light cyan ink.

  The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 1 Recording medium 22 Recording head part 90 Inkjet recording device

Claims (15)

The first ink includes at least the first ink, the second ink, and the third ink, and the first ink image and the second ink image are formed on a recording medium adjacent to each other. The first ink oozes into the second ink image at an adjacent boundary between the image of the second ink and the image of the second ink, and the image of the third ink and the image of the second ink are adjacent to each other. When forming on a recording medium, three or more kinds of inks that the second ink bleeds into the third ink image at an adjacent boundary between the third ink image and the second ink image An inkjet recording apparatus that forms an image by causing a dischargeable recording head to scan a predetermined area on a recording medium a plurality of times.
Based on a distribution pattern for each of the three or more types of ink, and having discharge data distribution means for distributing the discharge data for discharging the three or more types of ink to a plurality of scans;
The ejection data distribution unit is configured to form the first ink and the third ink for the predetermined area when forming an image including a mixed color image of the first ink and the third ink in the predetermined area. An ink jet recording apparatus, wherein a distribution pattern set including the distribution pattern of the first ink and the distribution pattern of the third ink is switched according to the applied amount. At least a first ink, a second ink, and a third ink, wherein the first ink has a lower surface tension than the second ink, and the third ink has a surface tension higher than that of the second ink. An inkjet recording apparatus that forms an image by scanning a predetermined area on a recording medium a plurality of times with a high recording head capable of ejecting three or more types of ink,
Based on a distribution pattern for each of the three or more types of ink, and having discharge data distribution means for distributing the discharge data for discharging the three or more types of ink to a plurality of scans;
The ejection data distribution unit is configured to form the first ink and the third ink for the predetermined area when forming an image including a mixed color image of the first ink and the third ink in the predetermined area. An ink jet recording apparatus, wherein a distribution pattern set including the distribution pattern of the first ink and the distribution pattern of the third ink is switched according to the applied amount. Based on a plurality of distribution pattern sets, a mixed color patch of the first ink and the third ink in which the amount of ink applied per unit area changes stepwise is adjacent to the second ink patch. Output means for outputting on a recording medium and obtaining a plurality of output results;
Corresponding information acquisition means for acquiring correspondence information between the ink application amount per unit area that changes stepwise and an optimum distribution pattern set according to the application amount based on the plurality of output results. And
3. The inkjet according to claim 1, wherein the ejection data distribution unit switches a distribution pattern set according to an application amount of the first ink and the third ink based on the correspondence information. Recording device.   4. The number of times that the first ink and the third ink are ejected in the same scan among the plurality of scans is adjusted by switching the distribution pattern set. 2. An ink jet recording apparatus according to item 1.   2. The method according to claim 1, wherein the distribution pattern set is changed to adjust an ink amount for ejecting the first ink and the third ink in the same scan among the plurality of scans. The inkjet recording apparatus according to any one of 3.   The predetermined area where the image is formed with the three or more types of ink is the first area adjacent to the entire mixed-color image area of the first ink and the third ink or the image of the second ink. 6. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is an end portion of a mixed color image of ink and the third ink.   The inkjet according to any one of claims 1 to 6, wherein the third ink has the same color material as the first ink and has a color material density different from that of the first ink. Recording device.   The amount of the first ink and the third ink applied to the predetermined area is determined based on a gradation value corresponding to the color material of the first ink and the third ink. The ink jet recording apparatus according to claim 7.   The ink jet recording apparatus according to claim 1, wherein a surface tension of the three or more types of ink is 30 (mN / m) or less. The ink jet recording according to any one of claims 1 to 9, wherein the recording medium is a recording medium having an ink transfer amount by Bristow method of less than 20 ml / m ^{2 with} respect to the three or more types of ink. apparatus.   The inkjet recording apparatus according to claim 1, wherein the recording medium is print-coated paper. The first ink includes at least the first ink, the second ink, and the third ink, and the first ink image and the second ink image are formed on a recording medium adjacent to each other. The first ink oozes into the second ink image at an adjacent boundary between the image of the second ink and the image of the second ink, and the image of the third ink and the image of the second ink are adjacent to each other. When forming on a recording medium, three or more kinds of inks that the second ink bleeds into the third ink image at an adjacent boundary between the third ink image and the second ink image An inkjet recording method for forming an image by causing a dischargeable recording head to scan a predetermined region on a recording medium a plurality of times,
A discharge data distribution step of distributing discharge data for discharging the three or more types of ink to a plurality of scans based on the distribution pattern for each of the three or more types of ink;
In the ejection data distribution step, when forming an image including a mixed color image of the first ink and the third ink in the predetermined area, the first ink and the third ink for the predetermined area are formed. An ink jet recording method, wherein a distribution pattern set composed of a distribution pattern of the first ink and a distribution pattern of the third ink is switched according to an applied amount. At least a first ink, a second ink, and a third ink, wherein the first ink has a lower surface tension than the second ink, and the third ink has a surface tension higher than that of the second ink. An inkjet recording method for forming an image by scanning a predetermined area on a recording medium a plurality of times with a high recording head capable of discharging three or more types of ink,
A discharge data distribution step of distributing discharge data for discharging the three or more types of ink to a plurality of scans based on the distribution pattern for each of the three or more types of ink;
In the ejection data distribution step, when forming an image including a mixed color image of the first ink and the third ink in the predetermined area, the first ink and the third ink for the predetermined area are formed. An ink jet recording method, wherein a distribution pattern set composed of a distribution pattern of the first ink and a distribution pattern of the third ink is switched according to an applied amount. Based on a plurality of distribution pattern sets, a mixed color patch of the first ink and the third ink in which the amount of ink applied per unit area changes stepwise is adjacent to the second ink patch. An output process for outputting on a recording medium and obtaining a plurality of output results;
A correspondence information acquisition step of acquiring correspondence information between the ink application amount per unit area that changes stepwise and an optimal distribution pattern set according to the application amount based on the plurality of output results; ,
14. The inkjet according to claim 12, wherein the ejection data distribution step switches a distribution pattern set according to the application amount of the first ink and the third ink based on the correspondence information. Recording method.   The program for making a computer perform the inkjet recording method of any one of Claims 12 thru | or 14.