JP4850306B2 - Image processing method, program, image processing apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to an image processing method, a program, an image forming apparatus, an image processing apparatus, and an image forming apparatus.

  2. Related Art As an image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine of these, for example, an ink jet recording apparatus using a droplet discharge head as a recording head is known. An ink jet recording apparatus is a paper (not limited to paper, including OHP, which means that ink droplets, other liquids, etc. can adhere to the recording medium or recording medium, recording paper, The recording liquid is also ejected onto recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously).

  In order for such an ink jet recording apparatus to spread from the personal area to the office area, the following two major problems must be solved. One is the recording speed. Except for special industrial types, in a general ink jet recording apparatus, recording is performed by a recording head that is much smaller than the recording paper repeatedly scanning the paper and spraying ink droplets. This is a so-called “line” recording method, which is considerably disadvantageous in terms of recording speed as compared to an electrophotographic image forming apparatus that performs recording on a sheet (page) basis, that is, “surface”.

  In order to eliminate this disadvantage of printing speed, it is possible to improve the scanning speed by increasing the period of ejecting ink droplets, to reduce the number of scans by increasing the size of the recording head or bidirectional recording, and to record image data Increasing the efficiency of the scanning sequence such as the shortest control in which only the region is scanned has been adopted. As a result, it is possible to realize a recording speed higher than that of electrophotography when printing small to medium copies.

  The second problem is dealing with plain paper as a cost-related problem. When special paper is used, inkjet recording images can reproduce images with extremely high quality, and with recent inkjet recording apparatuses for personal use, it has become possible to obtain image quality that can be mistaken for photographs. Yes.

  However, these dedicated papers are generally expensive and difficult to introduce when strict cost control is required in companies, etc., and in images output for office use, image quality up to that point is not required, Disadvantages increase if high-quality images can only be formed using special paper.

  Therefore, in order to cope with plain paper, the ink composition will be improved. For example, the development of a low penetrating dye ink, the use of a fixing aid, the development of a pigment-based ink, etc. have been attempted, and the latest With respect to the models, it has become possible to form an image having the same quality as that of an electrophotographic image forming apparatus even on plain paper generally used in offices and paper generally used as copy paper.

  As described above, due to the improvement in speed and image quality, the ink jet recording apparatus has become a very attractive product even in the office. In particular, since it has a high cost advantage compared to laser printers and is easy to downsize, it is also being used on desktops.

  However, unlike image forming apparatuses such as laser printers and offset printing that have a mechanism for fixing a colorant to the surface of the paper, the problem associated with this penetration process is in ink jet recording that uses the penetration of the colorant into the paper. And restrictions always follow.

  That is, there is a problem of cockling in which the paper is swollen by the moisture contained in the ink and the deformed paper comes into contact with the recording head and soils the recording surface. In order to increase the accuracy of the ink droplet ejection position, it is necessary to reduce the gap between the recording head and the paper as much as possible. Unlike ordinary inkjet paper, plain paper used in the office has no measures against swelling. Therefore, if the gap is set too small, contact between the swollen paper and the head may occur, leading to defective image output.

  In addition, the ink that has landed on the paper surface rubs against the member of the transport mechanism while it is undried, the ink adhering to the member stains the surface of the paper, and the undried ink on the discharged paper surface is then discharged. In some cases, the backside of the printed paper may become dirty.

  For these problems, conventionally, the gap (distance) between the recording head and the paper is increased to reduce the physical contact surface, the printing sequence is optimized to ensure the drying time, or the drying is forcibly performed. Means, such as providing a heater for making it, were taken.

  However, increasing the gap between the recording head and the paper causes a drop in dot position accuracy. In addition, if a stop or the like is performed in order to ensure the drying time, the throughput is reduced. Furthermore, in addition to increasing costs, it is necessary to pay attention to safety when installing the heater. In some cases, the heated paper may curl and lead to jams and the like.

  Therefore, in recent years, measures have been advanced from the aspect of ink prescription, and it has become possible to perform recording on plain paper without degrading print quality without using special means as described above. For example, by increasing the permeability to the paper, ink does not stay on the surface of the paper, and the ink can be rapidly penetrated. Therefore, it is possible to prevent secondary transfer due to contact with parts and paper. With such improvements, the ink jet recording apparatus has been able to realize a recording speed comparable to that of a laser printer in “single-sided recording” (single-sided printing).

  The reason for limiting to “single-sided recording” is that it is still necessary to ensure the drying time in double-sided recording (double-sided printing), and this waiting time takes much longer than “single-sided recording”. is there. The reason for ensuring the drying time is to prevent secondary transfer in reloading (resetting) of the paper. In general, in the paper transport mechanism, there are roller-shaped components such as a pressure roller and a pressing roller that send out the paper under pressure for the purpose of preventing the paper from floating or misaligned. When the recording surface of the undried paper passes under the pressure roller, the undried ink is transferred to the surface of the pressure roller as if by offset printing, and the ink is retransferred to the surface of the paper by the rotation of the roller. It will be. At the contact level, ink that has penetrated into the paper will not be retransferred to these parts, but under pressure rollers, the ink in the paper will be forcibly squeezed out. Transcription easily occurs.

  In order to reduce this waiting time, a method for suppressing the amount of ink used during double-sided recording has been conventionally proposed. For example, Patent Document 1 describes that the amount of ink used is suppressed by thinning out in addition to adjusting the waiting time for drying according to the type of recording paper. This is also intended to prevent secondary transfer and show-through, that is, prevent ink recorded on the front side from penetrating to the back side due to permeation and degrading the image quality of double-sided recording.

  Japanese Patent Application Laid-Open No. 2004-228561 describes that whether the image data to be output is a character or a character is determined, and if it is not a character, the amount of moisture adhering to the paper is suppressed by adjusting the ink discharge amount. Yes.

  Further, Patent Document 3 describes that the ink adhesion amount is limited by γ correction.

Japanese Patent No. 2879872 Japanese Patent Laid-Open No. 09-123431 JP 2005-053087 A

  However, in the methods described in Patent Documents 1 to 3 described above, the amount of ink that actually adheres to the paper can be limited, but the effect of the limitation extends to the entire image, so that the image density is lowered overall. There is a problem.

  For example, in the case of image data of only the primary color, ink of a single color solid or more is not used at the maximum, and this single color solid ink amount is not necessarily used in double-sided recording, although it depends on the image data. It's not impossible. Nevertheless, by restricting the ejection amount and performing the thinning-out process, the image quality deteriorates because it is forced to suppress the hue to a maximum color gamut.

  The present invention has been made in view of the above-described problems, and an object thereof is to suppress degradation of image quality as much as possible while shortening a waiting time for drying.

In order to solve the above problems, an image processing method according to the present invention includes:
In an image processing method for generating and processing image data to be sent to an image forming apparatus capable of double-sided printing, which is equipped with a recording head for discharging recording liquid droplets and forms an image on a sheet based on input data,
Performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The correction coefficient for each hue is a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed in duplex printing for the hue.

  Further, the correction coefficient may be switched for each object constituting the image data.

The program according to the present invention is:
In a program for causing a computer to perform processing for generating image data to be sent to an image forming apparatus that forms an image by mounting a recording head that discharges droplets of recording liquid based on input data.
Performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The correction coefficient for each hue is a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed in duplex printing for the hue.

An image processing apparatus according to the present invention includes:
In an image processing apparatus that generates and processes image data to be sent to an image forming apparatus capable of double-sided printing, which is equipped with a recording head that discharges recording liquid droplets and forms an image based on input data.
Means for performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The correction coefficient for each hue is a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed in duplex printing for the hue.

An image forming apparatus according to the present invention includes:
In an image forming apparatus for forming an image by mounting a recording head for discharging recording liquid droplets based on input data,
Means for performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The correction coefficient for each hue is a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed in duplex printing for the hue.

  According to an image processing method, a program, an image processing apparatus, an image forming apparatus, and an image forming system according to the present invention, a color space conversion process for converting input data into a color space value for the image forming apparatus is performed, and the color space In the conversion process, when performing double-sided printing, a value obtained by multiplying the output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing, and the correction coefficient for each hue is Since it is configured to be a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed at the time of duplex printing in the hue, while shortening the waiting time for drying, A decrease in image quality can be suppressed.

1 is a schematic configuration diagram of a mechanism unit of an ink jet recording apparatus showing an example of an image forming apparatus. It is principal part plane explanatory drawing of the mechanism part. It is a perspective explanatory view explaining the head unit composition of the device. It is explanatory drawing explaining an example of the conveyance belt of the apparatus. FIG. 6 is an explanatory diagram for explaining an image forming operation by the apparatus. It is a block diagram which shows the outline | summary of the control part of the apparatus. FIG. 2 is a block diagram functionally illustrating an example of a configuration of a printer driver according to the present invention in an image processing apparatus according to the present invention. FIG. 6 is a block diagram functionally illustrating another example of the configuration of the printer driver according to the present invention. FIG. 3 is a block explanatory diagram illustrating details of a flow of image processing in a printer driver. It is a flowchart with which it uses for description of the color space conversion process which concerns on one Embodiment of this invention. It is a flowchart with which it uses for description of the color space conversion process which concerns on other embodiment of this invention. It is explanatory drawing with which it uses for description of the malfunction by the correction method at the time of the conventional double-sided printing. It is explanatory drawing with which it uses for description when similarly seeing as a color gamut. It is explanatory drawing with which it uses for description of the correction coefficient in the color space conversion process in this invention. It is explanatory drawing with which it uses for description when the case where the color space conversion process in this invention is performed is seen in a color gamut. It is explanatory drawing with which it uses for description of the three-dimensional lookup table which comprises a CMM parameter.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an ink jet recording apparatus as an image forming apparatus will be described with reference to FIGS. 1 is a schematic configuration diagram of the entire mechanism of the recording apparatus, FIG. 2 is an explanatory plan view of the main part of the recording apparatus, FIG. 3 is a perspective explanatory view illustrating the head configuration of the recording apparatus, and FIG. FIG. 3 is a schematic cross-sectional explanatory diagram of a conveyance belt of a recording apparatus.

  This ink jet recording apparatus has an image forming unit 2 and the like inside the apparatus main body 1, and a paper feed tray 4 on which a large number of recording media (hereinafter referred to as “paper”) 3 can be stacked below the apparatus main body 1. The sheet 3 fed from the sheet feeding tray 4 is taken in, and a required image is recorded by the image forming unit 2 while the sheet 3 is conveyed by the conveying mechanism 5, and then mounted on the side of the apparatus main body 1. The paper 3 is discharged to the paper discharge tray 6.

  In addition, the inkjet recording apparatus includes a duplex unit 7 that can be attached to and detached from the apparatus main body 1. When performing duplex printing, the sheet 3 is transported in the reverse direction by the transport mechanism 5 after completion of one-side (front) printing. The sheet is taken into the duplex unit 7, reversed, and sent to the transport mechanism 5 again as the other side (back side) as a printable side, and the sheet 3 is discharged to the discharge tray 6 after the other side (back side) printing is completed.

  Here, the image forming unit 2 slidably holds the carriage 13 on the guide shafts 11 and 12, and moves the carriage 13 in a direction orthogonal to the conveyance direction of the paper 3 (main scanning) by a main scanning motor (not shown). . The carriage 13 is equipped with a recording head 14 composed of a droplet discharge head in which nozzle holes 14n (see FIG. 3) as a plurality of discharge ports for discharging droplets are arranged. The ink cartridge 15 for supplying the ink is detachably mounted. Note that a sub tank may be mounted in place of the ink cartridge 15 so that ink is replenished and supplied from the main tank to the sub tank.

  Here, as the recording head 14, for example, as shown in FIGS. 2 and 3, droplets that eject ink droplets of each color of yellow (Y), magenta (M), cyan (C), and black (Bk). Although the four independent inkjet heads 14y, 14m, 14c, and 14k, which are ejection heads, are used, one or a plurality of heads having a plurality of nozzle arrays that eject ink droplets of each color may be used. The number of colors and the order of arrangement are not limited to this.

  As the ink-jet head constituting the recording head 14, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like as an energy generating means for discharging ink can be used.

  The paper 3 in the paper feed tray 4 is separated one by one by a paper feed roller (half-moon roll) 21 and a separation pad (not shown), fed into the apparatus main body 1 and sent to the transport mechanism 5.

  The transport mechanism 5 guides the fed paper 3 along the guide surface 23 a and guides the paper 3 fed from the duplex unit 7 along the guide surface 23 b and the paper 3. A conveying roller 24 that conveys, a pressure roller 25 that presses the sheet 3 against the conveying roller 24, a guide member 26 that guides the sheet 3 toward the conveying roller 24, and a sheet 3 that is returned when duplex printing is performed on the duplex unit 7. And a pressing roller 28 that presses the paper 3 fed from the conveying roller 24.

  Further, the transport mechanism 5 charges the transport belt 33 between the drive roller 31 and the driven roller 32 and the transport belt 33 so that the recording head 14 transports the paper 3 while maintaining the flatness of the paper 3. A charging roller 34 that is opposed to the charging roller 34, a guide member 35 (not shown) that guides the conveying belt 33 at a portion facing the image forming unit 2, and a conveying belt 33. A cleaning roller made of a porous material or the like, which is a cleaning means for removing the recording liquid (ink) adhering to the recording medium.

  Here, the conveyance belt 33 is an endless belt, and is stretched between the driving roller 31 and the driven roller (tension roller) 32 so as to circulate in the direction indicated by the arrow in FIG. 1 (paper conveyance direction). It is composed.

  The transport belt 33 can be configured as a single layer, or as shown in FIG. 4, a two-layer configuration of a first layer (outermost layer) 33a and a second layer (back layer) 33b, or a configuration of three or more layers. For example, the transport belt 33 is a surface layer that is a sheet adsorbing surface formed of a pure resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, ETFE pure material, and resistance control by carbon using the same material as the surface layer. It consists of the back layer (medium resistance layer, earth layer) performed.

  The charging roller 34 is disposed so as to come into contact with the surface layer of the transport belt 33 and to rotate following the rotation of the transport belt 33. A high voltage is applied to the charging roller 34 in a predetermined pattern from a high voltage circuit (high voltage power source) (not shown).

  Further, on the downstream side from the transport mechanism 5, a paper discharge roller 38 for sending the paper 3 on which an image is recorded to the paper discharge tray 6 is provided.

  In the image forming apparatus configured as described above, the conveyance belt 33 is circulated in the direction of the arrow, and is positively charged by coming into contact with the charging roller 34 to which a high potential application voltage is applied. In this case, the charging roller 34 is charged at a predetermined charging pitch by switching the polarity at predetermined time intervals.

  Here, when the paper 3 is fed onto the conveying belt 33 charged at this high potential, the inside of the paper 3 is in a polarized state, and the electric charge having the opposite polarity to the electric charge on the conveying belt 33 is connected to the belt 33 of the paper 3. The charge on the belt 33 and the charge on the transported paper 3 are electrostatically attracted to each other, and the paper 3 is electrostatically attracted to the transport belt 33. . In this way, the sheet 3 strongly adsorbed to the transport belt 33 is calibrated for warpage and unevenness, and a highly flat surface is formed.

  Therefore, the recording belt 14 is moved around the conveyor belt 33 and the recording head 14 is driven according to the image signal while moving and scanning the carriage 13 in one direction or in both directions, as shown in FIGS. As shown, a droplet 14i is ejected (jetted) from the recording head 14, and ink droplets, which are droplets, are landed on the stopped paper 3 to form dots Di, thereby recording one line. After the predetermined amount of paper 3 is conveyed, the next line is recorded. When the recording end signal or the signal that the rear end of the paper 3 reaches the recording area is received, the recording operation is ended. FIG. 5B is an enlarged view of the dot Di formation portion of FIG.

  In this way, the sheet 3 on which the image is recorded is discharged to the discharge tray 6 by the discharge roller 38.

Next, ink as a recording liquid used in the ink jet recording apparatus will be described.
In the present invention, as the color material of the ink used by the image forming apparatus, either a pigment or a dye can be used, or a mixture can be used.

[Pigment]
As the pigment, those listed below are preferably used. Moreover, you may use these pigments in mixture of multiple types.

  Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done.

  Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

  The particle diameter of these pigments is preferably 0.01 to 0.30 [mu] m. If the particle diameter is 0.01 [mu] m or less, the light resistance and feathering are deteriorated because the particle diameter approaches that of the dye. On the other hand, if it is 0.30 μm or more, clogging of the discharge port or clogging with a filter in the printer occurs, and the discharge stability cannot be obtained.

  The carbon black used in the black pigment ink is carbon black produced by the furnace method and the channel method, the primary particle size is 15 to 40 millimicrons, the specific surface area by the BET method is 50 to 300 square meters / g, The DBP oil absorption is preferably 40 to 150 ml / 100 g, the volatile content is 0.5 to 10%, and the pH value is 2 to 9. As such a thing, for example, no. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (Mitsubishi Chemical Corporation), Raven700, 5750, 5250, 5000, 3500, 1255 (Columbia), Regal400R, 330R, 660R, MoguL, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (manufactured by Cabot), color black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, the same V, the same 140U, the same 140V, the special black 6, the same 5, the same 4A, the same 4 (manufactured by Degussa) and the like can be used, but are not limited thereto.

Specific examples of color pigments are listed below.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

Specific examples according to color are as follows.
Examples of pigments that can be used for yellow ink include C.I. I. Pigment Yellow 1, 2, 2, 3, 12, 14, 16, 17, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 129, 151, 154, etc., but are not limited thereto.

  Examples of pigments that can be used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 123, 168, 184, 202, etc. However, it is not limited to these.

  Examples of pigments that can be used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15:34, 16, 22, 22, 60, C.I. I. Examples thereof include, but are not limited to, Bat Blue 4 and 60.

  In addition, the pigment contained in each ink used in the present invention may be newly produced for the present invention.

  The pigments listed above can be made into an inkjet recording liquid by dispersing them in an aqueous medium using a polymer dispersant or a surfactant. As a dispersant for dispersing such organic pigment powder, a normal water-soluble resin or a water-soluble surfactant can be used.

  Specific examples of water-soluble resins include styrene, styrene derivatives, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itacon. Examples thereof include block copolymers consisting of at least two monomers selected from acids, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, etc., random copolymers, or salts thereof.

  These water-soluble resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved. Among them, a resin having a weight average molecular weight of 3000 to 20000 is used as a dispersion when used in an inkjet recording liquid. It is particularly preferred because of the advantages that it can be reduced in viscosity and can be easily dispersed.

The simultaneous use of the polymer dispersant and the self-dispersing pigment is a preferable combination because an appropriate dot diameter can be obtained. The reason is not clear, but it is thought as follows.
By containing the polymer dispersant, the penetration into the recording paper is suppressed. On the other hand, since the aggregation of the self-dispersing pigment is suppressed by containing the polymer dispersant, the self-dispersing pigment can smoothly spread in the lateral direction. Therefore, it is considered that the dots spread widely and thinly and ideal dots can be formed.

  Moreover, the following are mentioned as a specific example of the water-soluble surfactant which can be used as a dispersing agent. For example, anionic surfactants include higher fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkyl ester sulfates, alkyl aryl ether sulfates, alkyl sulfonates, sulfosuccinates, alkyl allyls and alkyl naphthalene sulfonic acids. Examples thereof include salts, alkyl phosphates, polyoxyethylene alkyl ether phosphate esters, and alkyl allyl ether phosphates. Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, tetraalkylammonium salts, benzalkonium salts, alkylpyridinium salts, imidazolinium salts, and the like.

  Furthermore, examples of the amphoteric surfactant include dimethylalkyl lauryl betaine, alkyl glycine, alkyl di (aminoethyl) glycine, imidazolinium betaine and the like. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, sucrose ester, glycerin ester polyoxyethylene ether, sorbitan Examples thereof include polyoxyethylene ethers of esters, polyoxyethylene ethers of sorbitol esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, amine oxides, and polyoxyethylene alkylamines.

  Further, the pigment can be provided with dispersibility by coating with a resin having a hydrophilic group and encapsulating the pigment.

  As a method for coating a water-insoluble pigment with an organic polymer and microencapsulating, all conventionally known methods can be used. Conventionally known methods include chemical production methods, physical production methods, physicochemical methods, mechanical production methods, and the like. Specifically, interfacial polymerization method, in-situ polymerization method, submerged cured coating method, coacervation (phase separation) method, submerged drying method, melt dispersion cooling method, air suspension coating method, spray drying method , Acid precipitation method, phase inversion emulsification method and the like.

  The interfacial polymerization method is a method in which two types of monomers or two types of reactants are separately dissolved in a dispersed phase and a continuous phase, and both substances are reacted at the interface between the two to form a wall film. The in-situ polymerization method is a method in which a liquid or gas monomer and catalyst, or two reactive substances are supplied from either one of the continuous phase core particles to cause a reaction to form a wall film. The in-liquid cured coating method is a method of forming a wall film by insolubilizing droplets of a polymer solution containing core material particles in a liquid with a curing agent or the like.

  The coacervation (phase separation) method is a method in which a polymer dispersion in which core material particles are dispersed is separated into a coacervate (concentrated phase) and a dilute phase having a high polymer concentration to form a wall film. . In the liquid drying method, a liquid in which a core material is dispersed in a wall membrane material solution is prepared, and the dispersion is put into a liquid in which the continuous phase of this dispersion liquid is not miscible to form a composite emulsion to dissolve the wall membrane material. In this method, the wall film is formed by gradually removing the medium.

  The melt dispersion cooling method uses a wall film material that melts into a liquid state when heated and solidifies at room temperature. This material is heated and liquefied, and the core material particles are dispersed in it and cooled to fine particles. This is a method of forming a wall film. The suspension-in-air coating method is a method of forming a wall membrane by suspending powder core material particles in the air with a fluidized bed and suspending them in an air stream while spraying and mixing the coating solution of the wall membrane material. It is.

  The spray drying method is a method in which an encapsulated stock solution is sprayed and brought into contact with hot air to evaporate and dry volatile components to form a wall film. The acid precipitation method means that at least a part of the anionic group of the organic polymer compound containing an anionic group is neutralized with a basic compound to give water solubility and kneading in an aqueous medium together with a coloring material. After that, neutralization or acidification with an acidic compound is performed, and organic compounds are precipitated and fixed to a coloring material, and then neutralized and dispersed. The phase inversion emulsification method refers to a mixture containing an anionic organic polymer having dispersibility in water and a coloring material as an organic solvent phase, and water is added to the organic solvent phase or This is a method of charging the organic solvent phase.

  Examples of organic polymers (resins) used as the material constituting the microcapsule wall membrane material include polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, urea resin, melamine resin, phenol resin, and polysaccharide. , Gelatin, gum arabic, dextran, casein, protein, natural rubber, carboxypolymethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethyl cellulose, methyl cellulose, nitrocellulose, hydroxyethyl cellulose, acetic acid Cellulose, polyethylene, polystyrene, (meth) acrylic acid polymer or copolymer, (meth) acrylic acid ester polymer or copolymer, (meth) acrylic acid (Meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, styrene-maleic acid copolymer, sodium alginate, fatty acid, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, albumin, etc. .

  Among these, organic polymers having an anionic group such as a carboxylic acid group or a sulfonic acid group can be used. Nonionic organic polymers include, for example, polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate or their (co) polymers, and 2-oxazoline cationic ring-opening polymers. Is mentioned. In particular, a complete saponified product of polyvinyl alcohol is particularly preferable because it has low water solubility and is easily dissolved in hot water but difficult to dissolve in cold water.

  Further, the amount of the organic polymer constituting the wall membrane material of the microcapsule is 1% by weight or more and 20% by weight or less based on the water-insoluble colorant such as an organic pigment or carbon black. By setting the amount of the organic polymer within the above range, the content of the organic polymer in the capsule is relatively low so that the pigment develops due to the organic polymer covering the pigment surface. Can be suppressed. If the amount of the organic polymer is less than 1% by weight, it is difficult to exert the effect of encapsulation. Conversely, if the amount exceeds 20% by weight, the color developability of the pigment is significantly reduced. In consideration of other characteristics, the amount of the organic polymer is preferably in the range of 5 to 10% by weight based on the water-insoluble colorant.

  That is, since a part of the color material is exposed without being substantially covered, it is possible to suppress a decrease in color developability, and conversely, a part of the color material is not substantially exposed without being exposed. Since it is coated, it is possible to simultaneously exhibit the effect that the pigment is coated. The number average molecular weight of the organic polymers is preferably 2000 or more from the viewpoint of capsule production. Here, “substantially exposed” means not the partial exposure associated with defects such as pinholes and cracks, but a state where it is intentionally exposed.

  Furthermore, if an organic pigment or self-dispersing carbon black, which is a self-dispersing pigment, is used as a colorant, the dispersibility of the pigment is improved even if the content of the organic polymer in the capsule is relatively low. In addition, since sufficient storage stability of the ink can be secured, it is more preferable for the present invention.

  It is preferable to select an organic polymer suitable for the microencapsulation method. For example, in the case of interfacial polymerization, polyester, polyamide, polyurethane, polyvinyl pyrrolidone, epoxy resin and the like are suitable. In the case of using the in-situ polymerization method, a polymer or copolymer of (meth) acrylic acid ester, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, Polyvinyl chloride, polyvinylidene chloride, polyamide and the like are suitable. In the case of the liquid curing method, sodium alginate, polyvinyl alcohol, gelatin, albumin, epoxy resin and the like are suitable. In the case of the coacervation method, gelatin, celluloses, casein and the like are suitable. In addition, in order to obtain a fine and uniform microencapsulated pigment, it is possible to use all conventionally known encapsulation methods other than those described above.

  When the phase inversion method or the acid precipitation method is selected as the microencapsulation method, anionic organic polymers are used as the organic polymers constituting the wall membrane material of the microcapsules. The phase inversion method is a composite or composite of an anionic organic polymer having self-dispersibility or solubility in water and a colorant such as a self-dispersion organic pigment or self-dispersion carbon black, or a self-dispersion method. A mixture of a colorant such as a dispersible organic pigment or self-dispersing carbon black, a curing agent, and an anionic organic polymer is used as an organic solvent phase, and water is added to the organic solvent phase, or the organic solvent is submerged in water. In this method, a solvent phase is introduced and microencapsulation is performed while self-dispersion (phase inversion emulsification) is performed. In the above phase inversion method, there is no problem even if the organic solvent phase is mixed with a recording liquid vehicle or additives. In particular, it is more preferable to mix a liquid medium of a recording liquid because a dispersion liquid for recording liquid can be directly produced.

  On the other hand, in the acid precipitation method, a part or all of the anionic group of the anionic group-containing organic polymer is neutralized with a basic compound, and a colorant such as a self-dispersing organic pigment or self-dispersing carbon black, A water-containing cake obtained by a production method comprising a step of kneading in an aqueous medium and a step of neutralizing and acidifying an acidic compound to precipitate an anionic group-containing organic polymer and fixing it to a pigment, This is a method of microencapsulation by neutralizing a part or all of an anionic group using a compound. By doing in this way, the aqueous dispersion containing the anionic microencapsulated pigment which is fine and contains many pigments can be manufactured.

  Examples of the solvent used for microencapsulation as described above include alkyl alcohols such as methanol, ethanol, propanol and butanol; aromatic hydrocarbons such as benzol, toluol and xylol; methyl acetate Esters such as ethyl acetate and butyl acetate; Chlorinated hydrocarbons such as chloroform and ethylene dichloride; Ketones such as acetone and methyl isobutyl ketone; Ethers such as tetrahydrofuran and dioxane; Cellosolves such as methyl cellosolve and butyl cellosolve Etc. The microcapsules prepared by the above method are once separated from these solvents by centrifugation or filtration, and then stirred and redispersed with water and the necessary solvent, and used for the intended present invention. A recording liquid that can be used is obtained. The average particle diameter of the encapsulated pigment obtained by the above method is preferably 50 nm to 180 nm.

  By coating the resin in this way, the pigment adheres firmly to the printed material, whereby the scratching property of the printed material can be improved.

〔dye〕
As the dye used in the recording liquid, dyes classified into acid dyes, direct dyes, basic dyes, reactive dyes, and food dyes in the color index are used which have excellent water resistance and light resistance. These dyes may be used as a mixture of a plurality of types, or may be used as a mixture with other color materials such as pigments as necessary. These colorants are added within a range that does not impair the effects of the present invention.

(A) As an acid dye and a food dye,
C. I. Acid Yellow 17, 23, 42, 44, 79, 142
C. I. Acid Red 1,8,13,14,18,26,27,35,37,42,52,82,87,89,92,97,106,111,114,115,134,186,249,254 289
C. I. Acid Blue 9, 29, 45, 92, 249
C. I. Acid Black 1, 2, 7, 24, 26, 94
C. I. Food Yellow 3, 4
C. I. Food Red 7, 9, 14
C. I. Food Black 1, 2

(B) As a direct dye,
C. I. Direct yellow 1,12,24,26,33,44,50,86,120,132,142,144
C. I. Direct Red 1,4,9,13,17,20,28,31,39,80,81,83,89,225,227
C. I. Direct orange 26, 29, 62, 102
C. I. Direct blue 1,2,6,15,22,25,71,76,79,86,87,90,98,163,165,199,202
C. I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171

(C) As a basic dye,
C. I. Basic yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 64, 65 67, 70, 73, 77, 87, 91
C. I. Basic Red 2,12,13,14,15,18,22,23,24,27,29,35,36,38,39,46,49,51,52,54,59,68,69,70 73, 78, 82, 102, 104, 109, 112
C. I. Basic blue 1,3,5,7,9,21,22,26,35,41,45,47,54,62,65,66,67,69,75,77,78,89,92,93 , 105, 117, 120, 122, 124, 129, 137, 141, 147, 155
C. I. Basic Black 2,8

(D) As a reactive dye,
C. I. Reactive Black 3, 4, 7, 11, 12, 17
C. I. Reactive Yellow 1,5,11,13,14,20,21,22,25,40,47,51,55,65,67
C. I. Reactive Red 1,14,17,25,26,32,37,44,46,55,60,66,74,79,96,97
C. I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95, etc. can be used.

[Additives and physical properties common to dyes and pigments]
In order to make the recording liquid used in the image forming apparatus according to the present invention have desired physical properties or to prevent clogging of the nozzles of the recording head due to drying, a water-soluble organic solvent is used in addition to the coloring material. It is preferable to do. The water-soluble organic solvent includes a wetting agent and a penetrating agent. The wetting agent is added for the purpose of preventing clogging of the nozzles of the recording head due to drying.

  Specific examples of the wetting agent include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, 1,3-propanediol, and 2-methyl-1,3-propane. Diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 1,2 Polyhydric alcohols such as 1,4-butanetriol, 1,2,3-butanetriol, and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene Polyhydric alcohol alkyl ethers such as glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether Forehead: Nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; formamide, N-methylformamide, Amides such as formamide and N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethyl And amines such as ruamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination with water.

  Further, the penetrant is added for the purpose of improving the wettability between the recording liquid and the recording material and adjusting the penetration speed. As the penetrant, those represented by the following formulas (I) to (IV) are preferable. That is, a polyoxyethylene alkylphenyl ether surfactant of formula (I) below, an acetylene glycol surfactant of formula (II), a polyoxyethylene alkyl ether surfactant of formula (III) below and formula (IV) The polyoxyethylene polyoxypropylene alkyl ether-based surfactant (1) can reduce the surface tension of the liquid, so that the wettability can be improved and the penetration rate can be increased.

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, k is 5 to 20)

(M and n are 0 to 40)

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, n is 5 to 20)

(R is a hydrocarbon chain having 6 to 14 carbon atoms, m and n are numbers of 20 or less)

  Other than the compounds of the above formulas (I) to (IV), for example, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl Use alkyl and aryl ethers of polyhydric alcohols such as ethers, nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymers, fluorine-based surfactants, lower alcohols such as ethanol and 2-propanol However, diethylene glycol monobutyl ether is particularly preferable.

  The surface tension of the recording liquid used in the image forming apparatus according to the present invention is preferably 10 to 60 N / m, and 15 to 30 N from the viewpoint of achieving both wettability with the recording medium and droplet formation. More preferably, it is / m.

  Similarly, the viscosity of the recording liquid is preferably in the range of 1.0 to 20 mPa · s, and from the viewpoint of ejection stability, it is preferably in the range of 5.0 to 10 mPa · s.

  The pH of the recording liquid is preferably in the range of 3 to 11, and more preferably in the range of 6 to 10 from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

  Further, the recording liquid can contain an antiseptic / antifungal agent. By containing the antiseptic / antifungal agent, the growth of bacteria can be suppressed, and the storage stability and the image quality stability can be improved. As antiseptic / antifungal agents, benzotriazole, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, isothiazoline compounds, sodium benzoate, sodium pentachlorophenol, and the like can be used.

  Further, the recording liquid can contain a rust inhibitor. By containing a rust preventive agent, a coating can be formed on the metal surface in contact with the liquid, such as a head, and corrosion can be prevented. As the rust inhibitor, for example, acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like can be used.

  Further, the recording liquid can contain an antioxidant. By containing an antioxidant, even when radical species that cause corrosion are generated, the antioxidant can be prevented by eliminating the radical species.

  Typical examples of the antioxidant include phenolic compounds and amine compounds. Examples of the phenolic compounds include hydroquinone and gallate compounds, 2,6-di-tert-butyl-p-cresol, and stearyl. -Β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl- 6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-4-hydroxybenzyl) benzene, Hindered materials such as lith (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [methylene-3 (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane Phenol compounds are exemplified, and amine compounds include N, N′-diphenyl-p-phenylenediamine, phenyl-β-naphthylamine, phenyl-α-naphthylamine, N, N′-β-naphthyl-p-phenylene. Examples include diamine, N, N′-diphenylethylenediamine, phenothiazine, N, N′-di-sec-butyl-p-phenylenediamine, 4,4′-tetramethyl-diaminodiphenylmethane, and the like. Further, as the latter, sulfur compounds and phosphorus compounds are representative, but as sulfur compounds, dilauryl thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dithiol. Examples include myristyl thiodipropionate, distearyl β, β′-thiodibutyrate, 2-mercaptobenzimidazole, dilauryl sulfide and the like, and phosphorus compounds include triphenyl phosphite, trioctadecyl phosphite, tridecyl. Examples include phosphite, trilauryl trithiophosphite, diphenylisodecyl phosphite, trinonylphenyl phosphite, distearyl pentaerythritol phosphite.

  The recording liquid can contain a pH adjusting agent. Examples of the pH adjuster include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, Examples include alkali metal carbonates such as sodium carbonate and potassium carbonate, amines such as diethanolamine and triethanolamine, boric acid, hydrochloric acid, nitric acid, sulfuric acid, and acetic acid.

Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. This figure is an overall block diagram of the control unit.
The control unit 100 includes a CPU 101 that controls the entire apparatus, a ROM 102 that stores programs executed by the CPU 101 and other fixed data, a RAM 103 that temporarily stores image data, and the like, while the apparatus is powered off. In addition, a non-volatile memory (NVRAM) 104 for holding data, image processing for performing various signal processing, rearrangement, and the like (including a part of image processing described later in some cases) and other overall devices are controlled. And an ASIC 105 for processing input / output signals.

  The control unit 100 also includes an I / F 106 for transmitting and receiving data and signals to and from the host 90 such as a personal computer (hereinafter also referred to as “PC”) including the image processing apparatus according to the present invention, A head drive control unit 107 and a head driver 108 for driving and controlling the recording head 14, a main scanning motor driving unit 111 for driving the main scanning motor 110, and a sub scanning motor driving for driving the sub scanning motor 112. , An environmental sensor 118 for detecting environmental temperature and / or environmental humidity, an I / O 116 for inputting detection signals from various sensors (not shown), and the like.

  The control unit 100 is connected to an operation panel 117 for inputting and displaying information necessary for the apparatus. Furthermore, the control unit 100 performs on / off switching and output polarity switching control of the high-voltage circuit (AC bias supply unit) 114 that applies a high voltage to the charging roller 34.

  Here, the control unit 100 receives print data including image data from the host 90 side such as a data processing device such as a personal computer, an image reading device such as an image scanner, and an imaging device such as a digital camera via a cable or a network. Received by the I / F 106. The print data is generated and output to the control unit 100 by the printer driver 91 according to the present invention on the host 90 side.

  Then, the CPU 101 reads out and analyzes the print data in the reception buffer included in the I / F 106, and the ASIC 105 may be configured to include data rearrangement processing (part of other image processing described later). Etc.) to transfer the image data to the head drive control unit 107. Note that the conversion of print data for image output into bitmap data is performed by developing the image data into bitmap data by the printer driver 91 on the host 90 side and transferring it to this apparatus as described above. For example, font data may be stored in the ROM 102.

  When the head drive control unit 107 receives image data (dot pattern data) corresponding to one line of the recording head 14, the dot pattern data for one line is serialized to the head driver 108 in synchronization with the clock signal. Data is sent out, and a latch signal is sent to the head driver 108 at a predetermined timing.

  The head drive control unit 107 includes a ROM (can be configured by the ROM 102) storing pattern data of a drive waveform (drive signal) and D / A-converted D of drive waveform data read from the ROM. A waveform generation circuit including an A converter and a drive waveform generation circuit including an amplifier and the like are included.

  The head driver 108 also receives a clock signal from the head drive control unit 107 and serial data as image data, and a latch circuit that latches the register value of the shift register using a latch signal from the head drive control unit 107. A level conversion circuit (level shifter) that changes the output value of the latch circuit, an analog switch array (switch means) that is controlled to be turned on / off by the level shifter, and the like, and controls on / off of the analog switch array. In this way, a required drive waveform included in the drive waveform is selectively applied to the actuator means of the recording head 14 to drive the head.

  Next, different examples of the configuration of the image processing apparatus (data processing apparatus) according to the present invention including the printer driver according to the present invention on the host side that transfers image data to form an image by the image forming apparatus. This will be described with reference to FIGS. These image processing apparatuses and the image forming apparatus described above constitute an image forming system according to the present invention.

  First, in the example shown in FIG. 7, the host printer driver 91 converts the image data 130 supplied from the application software or the like from the monitor display color space to the color space for the recording apparatus (RGB color system → CMM (Color Management Module) processing unit 131, which is a color space conversion processing unit according to the present invention that performs CMY color system, BG / UCR (black generation / Under Color Removal) that performs black generation / under color removal from CMY values ) A processing unit 132, a γ correction unit 133 that performs input / output correction reflecting the characteristics of the recording device and user's preference, a zooming unit 134 that performs an enlargement process in accordance with the resolution of the recording device, and image data from the recording device A halftone processing unit 135 including a multi-value / low-value matrix to be replaced with a pattern arrangement of dots to be ejected is included.

  In the example shown in FIG. 8, the host printer driver 91 converts the image data 130 supplied from application software or the like from a monitor display color space to a recording device color space (RGB color system → CMY). CMM (Color Management Module) processing unit 131 that performs color system), BG / UCR (black generation / Under Color Removal) processing unit 132 that performs black generation / under color removal from CMY values, characteristics of the recording apparatus and user A γ correction unit 133 that performs input / output correction reflecting the preference is included.

  In the case of the configuration of FIG. 8, the control unit 100 on the image forming apparatus side receives the output data after performing the γ correction process, and performs an enlargement process on this data in accordance with the resolution of the recording apparatus. A zooming unit 134 to perform, and a halftone processing unit 135 including a multi-value / low-value matrix that replaces image data with a pattern arrangement of dots ejected from the recording apparatus are included.

  Note that FIG. 7 is a “cheap machine” in which all image processing is performed on the PC side, and FIG. 8 is a “high-speed machine” in which a part of the processing is shared by an ASIC built in the image forming apparatus. In the configuration example of FIG. 8, since the image processing can be shared between the host side and the image forming apparatus, not only the time required for the image processing can be shortened but also the opening of the host PC can be accelerated. . However, since it is necessary to mount a higher performance ASIC (in some cases, a large-capacity memory), the price setting generally tends to be higher than that of the “cheap machine”.

Next, the flow of image processing by the printer driver 91 on the host side will be described with reference to the block diagram shown in FIG.
When a “print” instruction is issued from application software running on a data processing apparatus such as a personal computer, the printer driver 91 determines the type of object in the object determination process 201 for the input 200, and for each object, that is, Data is transferred for each of the character image data 202, the line drawing image data 203, the graphics image data 204, and the image image data 205, and processing is performed through the respective routes.

  That is, the color adjustment process 206 is performed on the character 202, the line drawing 203, and the graphics 204. Then, color matching processing 207, BG / UCR processing 209, total amount regulation processing 211, and γ correction processing 213 are performed for characters, and further character dither processing (halftone processing) 215 is performed. In addition, color matching processing 208, BG / UCR processing 210, total amount regulation processing 212, and γ correction processing 214 are performed on line drawings and graphics, and graphics dither processing (halftone processing) 216 is performed.

  On the other hand, the image 205 is subjected to color determination and compression method determination processing 221, and in a normal case, after color adjustment processing 222 and color matching processing 223, BG / UCR processing 224, total amount regulation processing 225, γ correction processing 226 is performed, and error diffusion processing (halftone processing) 227 is further performed. In the case of two colors or less, after performing image thinning processing 231, color adjustment processing 232, color matching processing 233a or indexless processing (processing without color matching) 233b, BG / UCR processing 224, total amount regulation Processing 225 and γ correction processing 226 are performed, and error diffusion processing (halftone processing) 227 is further performed.

  Note that line drawings and graphics may branch before reaching the color adjustment process 206, and may proceed to the color matching process 232 in the case of an image via the ROP process 241.

  The image data processed for each object in this way is combined with the original image data and delivered to the image forming apparatus.

The image processing method according to the present invention performs a color matching process, and converts input data from a monitor display color space to a color space for an image forming apparatus (RGB color system → CMY color system). Processing ".
In one embodiment of the present invention, as shown in FIG. 10, CMM processing is performed using a reference color space processing conversion table (for single-sided printing) to determine whether double-sided printing or single-sided printing is performed. Sometimes the value obtained by the CMM process is multiplied by a correction coefficient, and the multiplied value is used as a CMM value. When single-sided printing is performed, the value obtained by the CMM process is directly used as the CMM value, and the next BG / UCR process is performed. I try to migrate. In this example, the process combining the normal single-sided CMM process and the correction coefficient multiplication process is the “color space conversion process” in the present invention.

  In another embodiment of the present invention, as shown in FIG. 11, a single-sided color space processing conversion table and a double-sided color space processing conversion table obtained by multiplying this by a correction coefficient are prepared in advance. CMM processing (single-sided CMM processing) using a single-sided color space processing conversion table is performed for single-sided printing, and CMM using a double-sided color space processing conversion table for double-sided printing. After performing the process (double-sided CMM process), the obtained result is set as a CMM value, and the process proceeds to the next BG / UCR process.

  In this way, by changing the CMM processing for single-sided printing and double-sided printing, the recording liquid adhesion amount and the color reproduction range for each hue are taken into consideration, and the hue reaching the recording liquid adhesion amount that becomes an obstacle during double-sided printing is suppressed. By not performing suppression for hues that are not so, it is possible to maximize the color gamut during double-sided printing and minimize the reduction in color gamut compared to single-sided printing. Can be suppressed.

  In other words, if the “thinning process” and “discharge amount suppression” employed in the conventional double-sided printing described above are performed, the thinning process is performed on the original image of FIG. As shown in FIG. 4B, the image information is lost due to the thinning pattern, resulting in an apparent deterioration of the image quality. When the discharge amount is suppressed, the image information is displayed as shown in FIG. Although no omission occurs, the overall image density is lowered.

  When this is viewed in the color gamut, as shown in FIG. 13, the color gamut is as shown in FIG. 13A during single-sided printing, but when the above-described conventional correction is performed, FIG. As shown, the color reproduction range is uniformly reduced. The color gamut reproduced in each hue direction varies depending on the composition of the ink used and the restriction of the total amount of ink that can be deposited per unit area. In terms of ink adhesion amount, the closer to the primary color expressed by one ink color, the smaller the ink adhesion amount, and the closer the hue between the primary colors, the greater the ink adhesion amount. In the conventional correction process, the correction effect is uniformly applied to all hues regardless of the adhesion amount for each hue, so that the color space is reduced in a similar form as compared with single-sided printing.

  Here, for example, if the maximum value of the ink adhesion amount that does not cause a problem during double-sided printing is allowed up to the solid color adhesion amount of the primary color, the primary hue is during double-sided printing in which ink adheres to both sides. Even so, it should be possible to perform color reproduction equivalent to that for single-sided printing. Further, in the hue close to the primary color, the color gamut suppressed by the correction is very small, and the impression that the image quality has deteriorated can be minimized.

  Therefore, in the present invention, a correction coefficient is calculated based on the ink adhesion amount for each hue, and the output value from the CMM process is multiplied by this correction coefficient, thereby allowing the maximum allowable even during duplex printing. It is possible to secure a limited color gamut. For example, in the example shown in FIG. 14, if the ink adhesion amount allowed during double-sided printing is limited, even if the magenta (M) is allowed to adhere to an allowable value, no problem occurs, so the correction coefficient is 1.0 ( No correction), orange (O) has a correction coefficient of 0.73, and red (R) has a correction coefficient of 0.55. As a result, when viewed in the color reproduction gamut, as shown in FIG. 15, the color gamut during double-sided printing is dissimilar to the color gamut during single-sided printing.

  At this time, since the change in the hue and the change in the ink adhesion amount from the primary color to the secondary color correspond to each other, even if the correction coefficient multiplication process (correction process) corresponding to the adhesion amount is applied, The continuity of gradation and saturation will be maintained.

  In the example shown in FIG. 14, the amount of ink admissible during double-sided printing is calculated as 1.1 times the primary color solid, but this is only an example and is not necessarily limited to this ratio. . Since this ratio also varies depending on the paper and the system configuration, correction is performed so that “the amount of adhered ink after conversion = the maximum amount of adhered ink defined under double-sided printing conditions”.

  However, in terms of image quality, we want to guarantee a solid primary color. More preferably, “primary color maximum ink deposition amount ≦ ink deposition amount after conversion ≦ maximum ink deposition amount defined under duplex printing conditions” To correct.

  Since the CMM parameter is usually configured by a three-dimensional lookup table (LUT) as shown in FIG. 16, the correction coefficient also has a three-dimensional configuration. As to how to apply the correction, as described above, the output value through the CMM parameter is multiplied by the coefficient of the correction lookup table (example in FIG. 10). Either a printing CMM parameter or a single-sided printing CMM parameter is prepared and used by switching (example in FIG. 11).

  Note that the CMM parameter or the correction coefficient for multiplication to be switched at the time of both sides is not necessarily limited to one type. In other words, since various types of paper are available on the market, there are papers that are less likely to fail even when more ink is used during double-sided printing, and papers that are more restrictive. A plurality of CMM parameters or correction coefficients can be switched according to a user's selection or according to an automatic discrimination result by a paper discrimination means mounted on the image forming apparatus.

  Here, as an automatic paper discrimination means, a photo sensor or an image reading device incorporated in the image forming apparatus main body or the image forming system is used to discriminate based on information such as paper density, brightness, and color tone. And a method of reading information such as a bar code written on a part of a sheet. In addition, by providing a paper feed tray (paper feed means) in which paper brands are designated in advance, that is, by associating the paper with the paper feed means, when the paper is output from a remote image forming apparatus via a network, It is possible to perform the corresponding double-sided printing.

  Further, in the office environment, the output of so-called business documents in which text and graph images are mixed is mainly performed. In the image data mainly composed of text, the ink adhesion amount per unit area becomes small, so that the restriction on the ink adhesion amount at the time of duplex printing can be relaxed.

  Therefore, by switching the CMM parameter or the correction coefficient for each object constituting the image data, that is, text, fine line, graphic, photo, etc., the text and fine line are clear and the graphic and photo part do not have a defect. The maximum color gamut can be secured in the range.

  In the above embodiment, the image processing apparatus is configured such that the printer driver as the program according to the present invention causes the computer to execute the image processing method according to the present invention. Means for performing the method may also be provided. In addition, an application specific integrated circuit (ASIC) for executing the image processing method according to the present invention can be mounted on the image forming apparatus.

DESCRIPTION OF SYMBOLS 2 ... Image formation part 3 ... Paper 5 ... Conveyance mechanism part 14 ... Recording head 33 ... Conveyance belt 90 ... Host (image processing apparatus)
91: Printer driver (program)
131 ... CMM processing (color space conversion processing)
207, 208, 233a, 223 ... Color matching processing

Claims (5)

In an image processing method for generating and processing image data to be sent to an image forming apparatus capable of double-sided printing, which is equipped with a recording head for discharging recording liquid droplets and forms an image on a sheet based on input data,
Performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The correction coefficient for each hue is a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed at the time of duplex printing in the hue. .   The image processing method according to claim 1, wherein the correction coefficient is switched for each object constituting the image data. In a program for causing a computer to perform processing for generating image data to be sent to an image forming apparatus that forms an image by mounting a recording head that discharges droplets of recording liquid based on input data.
Performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The program according to claim 1, wherein the correction coefficient for each hue is a value calculated by gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed at the time of duplex printing in the hue. In an image processing apparatus that generates and processes image data to be sent to an image forming apparatus capable of double-sided printing, which is equipped with a recording head that discharges recording liquid droplets and forms an image based on input data.
Means for performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The correction coefficient for each hue is a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed at the time of duplex printing in the hue. . In an image forming apparatus for forming an image by mounting a recording head for discharging recording liquid droplets based on input data,
Means for performing color space conversion processing for converting input data into color space values for the image forming apparatus;
In the color space conversion process, when performing double-sided printing, a value obtained by multiplying an output value obtained by color space conversion by a correction coefficient for each hue is used as an output value at the time of double-sided printing,
The correction coefficient for each hue is a value calculated by the gradation value / maximum gradation value corresponding to the maximum recording liquid adhesion amount allowed at the time of duplex printing in the hue. .