JP2009113328A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise a throughput of printing in an inkjet printer which uses black of a pigment ink poor in fixability for printing and uses dyes for other colors. <P>SOLUTION: An amount of use of the pigment Bk is suppressed other than when printing of line images such as characters and CAD drawings is carried out, and a ratio of the dyes is increased, thereby making drying fast. A time when a printed object and a page printed next to it can be piled on a paper discharge tray is shortened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an ink jet printer capable of printing on both sides, wherein printing is performed using a plurality of colors of ink, and at least one of them is a pigment ink, and the other colors of ink are dyes. The present invention relates to a printing apparatus and an image printing apparatus.

  Various recording methods are known for the recording apparatus, but an ink jet method using a recording head that discharges ink as droplets is particularly useful in recent years.

  FIG. 1 is a perspective view for explaining a schematic configuration of a serial type ink jet recording apparatus. In the figure, reference numeral 4 denotes a recording head, which can eject a plurality of colors of ink.

  Before the start of recording, the carriage 7 on which the recording head 4 is mounted is located at the home position. When the recording start command is received, the carriage 7 moves in the arrow C direction (main scanning direction), and the recording head 4 ejects ink toward the recording medium S at a predetermined timing. When the recording for one scanning is completed, the recording roller S is conveyed in the direction of arrow A by a predetermined amount by rotating the conveying roller 1. Thereafter, the recording head 4 performs recording in the direction of arrow C again. An image is formed on the recording medium S by repeating the above-described one-time recording scanning and a predetermined amount of conveying operation.

  The recording medium S during recording is conveyed while being sandwiched and stretched by two pairs of rollers such as a conveying roller 1, a pinch roller 2 that follows the conveying roller 1, and a discharge roller 12 and a spur 13 that is linked to the discharging roller 12. Has been. When the image formation for one page is completed, the recording medium is discharged out of the apparatus by the discharge roller 12.

  By the way, in recent years, the use of recording apparatuses has been diversified, and the demand for so-called double-sided recording in which images are formed on both sides of a recording medium is increasing. Many such recording apparatuses have already been provided. In an inkjet recording apparatus that automatically realizes double-sided recording, after recording on one side of a recording medium is completed, the recording medium is re-feeded in the apparatus (direction B) without being discharged. Then, after reversing the front and back of the recording medium by the reversing means 16 provided in the apparatus, the recording medium is conveyed again to the recording area of the recording head in order to perform recording on the other side.

  For example, in the configuration of FIG. 1, the recording surface immediately after recording is fed to the reversing unit 16 while being in contact with the pinch roller 2. However, at this time, if the ink on the recording surface is insufficiently fixed, unfixed ink may be transferred to the pinch roller 2 or the like, and may be further transferred / contaminated to the reversed recording medium. In addition, when such double-sided recording is continuously performed on a number of recording media, the recording surfaces to which ink is applied are stacked on a discharge tray (not illustrated) in contact with each other. At this time, if either side of the ink is insufficiently dried, there is a problem that the recording surfaces of each other are stained.

  In order to cope with the above problem, in an inkjet recording apparatus that performs double-sided recording, after recording on one side is completed, the recording medium is held while holding, and the recording is performed after a period of time that is considered to be fixed. A method of refeeding the medium in the B direction is generally employed. Such a recording method is disclosed in Patent Document 1, for example.

  However, when the method described in Patent Document 1 is adopted, a large amount of time is consumed due to the influence of the standby time, and there is a problem that the output time is rather delayed as compared with single-sided recording. Double-sided recording is often performed for the purpose of low-cost and high-speed output, and it is not a preferable situation that the recording speed is unnecessarily slow for double-sided recording.

  In particular, in the case of double-sided printing, since printing is performed on both the front and back sides, the amount of water contained in the printed matter is larger than in single-sided printing in which printing is performed only on the front surface, and the waiting time required for drying is also longer.

  In addition, some inkjet printers in recent years use dyes for color inks such as cyan (hereinafter C), magenta (hereinafter M), yellow (hereinafter Y), and pigments only for black (hereinafter Bk) inks. There is something like doing.

  In this way, the characters are increased in density by the pigment Bk, and the color is improved by improving the color quality by improving the color by the dye CMY, but in general, the printed matter is printed unless the pigment ink is completely dried. It is difficult to be fixed on the surface of the film and is easy to peel off. For this reason, when printing is performed using the pigment Bk for double-sided printing, the printed matter to be stacked is rubbed and soiled unless a sufficient waiting time is taken.

For this reason, in double-sided recording, a method of reducing the amount of ink to be recorded so as to shorten the drying time is also employed (for example, Patent Document 2). According to this method, signals given to individual pixels are converted in a direction to suppress the amount of ink applied at the stage of image processing. Since the output amount of the recorded matter is reduced as compared with the case of normal single-sided recording, the drying time is shortened accordingly. As a result, the waiting time from the completion of the recording on the front surface to the start of the recording on the back surface is shortened, and an improvement in the recording speed during double-sided recording can be expected.
JP-A-6-134982 JP 07-314734 A

  However, in the above method, since the signal values of all the pixels are uniformly reduced, the density of the entire image is lowered. In such cases, image images such as landscapes and portraits, illustrations, and photo-centered posters are often not a problem, but it is difficult to read in text images with information or line drawings-centered CAD drawings. The lack of information itself was once again viewed as a problem.

  In general, when printing a photograph such as a landscape or a human figure, the amount of ink is generally larger than that of a character image or CAD drawing as described above. Therefore, it is necessary to reduce the amount of ink applied as in the above method, but the quality of printing has been uniformly reduced until it is not necessary to reduce the amount of ink applied as in character images and CAD drawings.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to perform high-speed printing without reducing the quality of character information recording even when performing double-sided printing using the pigment Bk. It is an object to provide an ink jet recording apparatus that enables a simple output.

  Means for performing double-sided printing using a plurality of colors of ink, printing means for using at least one pigment ink among the inks used for printing, and a color conversion table used for color conversion when performing double-sided printing The ink jet printer is characterized in that the time required for fixing and drying is shortened and the throughput is increased by performing printing without using pigment ink during double-sided printing.

  According to the present invention, while maintaining the output quality of text-centric documents and line drawing-centric CAD drawings, the amount of ink applied is reduced when printing photographs such as landscapes and people, and the ink is fixed in a short time. . As a result, even when performing double-sided recording, the amount of ink used is reduced only when necessary, and the recorded material can be printed at high speed without contaminating the inside of the recording device or other recorded material, and without degrading the character quality. It becomes possible to output.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  Specific embodiments relating to the present invention will be described below. In the present embodiment, the ink jet recording apparatus shown in FIG. 1 is applied.

  FIG. 2 is a block diagram for explaining an ink jet recording system including the ink jet recording apparatus of the present embodiment and a main apparatus connected to the recording apparatus and responsible for main image processing.

  A recording apparatus main control unit 101 controls the entire recording apparatus. The recording apparatus main control unit 101 includes an MPU, a ROM, a RAM, and the like. Reference numeral 107 denotes a system bus for the control mechanisms to communicate with each other. Reference numeral 105 denotes a recording apparatus I / F unit which receives image data transmitted from the main apparatus I / F unit 109. The recording apparatus main control unit 101 temporarily stores the received data in the data buffer 106 and performs processing specific to the recording apparatus. The processed data is accumulated in the recording buffer 102 as raster data for ejection by individual recording elements provided in the recording head 4.

  Reference numeral 104 denotes a paper supply / discharge motor control unit that feeds, conveys, and discharges the recording medium. In the recording apparatus of the present embodiment, double-sided recording on a recording medium can be performed, and the paper supply / discharge motor control unit 104 includes a mechanism for transporting the recording medium in a direction opposite to the transporting direction during recording, It also controls the mechanism for automatically reversing the front and back surfaces. Reference numeral 113 denotes a carriage motor control unit that performs control when the carriage 7 on which the recording head 4 is mounted is moved and scanned in the main scanning direction. The recording apparatus main control unit 101 conveys the recording medium by controlling the paper supply / discharge motor control unit 104, and scans the recording head 4 in the main scanning direction by controlling the carriage motor control unit 113. At this time, according to the raster data stored in the recording buffer 102, ink is ejected from the recording head 4, thereby forming an image for one line on the recording medium.

  On the other hand, 108 is a main device main control unit that controls the entire main device. The main device main control unit 108 includes an MPU, a ROM, a RAM, and the like. Reference numeral 112 denotes a system bus for the control mechanisms to communicate with each other. In the ink jet recording system of the present embodiment, the main device performs main image processing on an image to be recorded. The main apparatus main control unit 108 transfers the image data processed in the main apparatus to the I / F unit 105 of the ink jet recording apparatus via the main apparatus I / F unit 109. In the ink jet recording system of this embodiment, a user interface is provided in the main device. For this reason, the main apparatus includes a display unit 110 for notifying the user of the type of recording method and the recording status, and an operation unit for the user who has confirmed the display to set a recording mode and to input a print purpose. 111 is provided. The display unit 110 may be any display unit such as a CRT that can display information such as the purpose of printing, the printing quality, and single-sided printing or double-sided printing as shown in FIG. The operation unit 111 may be anything that can input information, such as a mouse or a keyboard.

  FIG. 3 is a flowchart for explaining the flow of image processing performed in the inkjet recording system of the present embodiment. After the user sets the print purpose, recording quality, double-sided recording or single-sided recording, the type of recording medium, and the like, when a recording start command is input from the operation unit 111, the main apparatus main control unit 108 The processing for the designated image data is started.

  First, in step S201, the image data is subjected to color correction processing. Specifically, the red (R), green (G), and blue (B) multi-tone luminance data possessed by each pixel is within a color gamut that can be expressed by the recording apparatus by using a three-dimensional LUT or the like. To multi-gradation luminance data (R, G, B).

  In the subsequent step S202, the individual image data is converted into density signals for the four colors of ink that the printing apparatus has. Since the recording apparatus of the present embodiment includes black, cyan, magenta, and yellow inks, for example, RGB luminance data expressed in 256 gradations is converted into CMYK density data also expressed in 256 gradations. Converted. The density data of each pixel obtained at this time can be almost regarded as the amount of ink applied to the pixel.

  In the next step S203, multi-value error diffusion processing is performed on the density data separated into four colors. In the multi-level error diffusion of the present embodiment, the data Y, M, C, and K of 256 gradations for each color after the four-color separation processing is performed are converted into, for example, data of 5 gradations (5 levels). The converted five-level data is data indicating an arrangement pattern in the subsequent index expansion process.

  The image data is stored in the data buffer in the recording device via the main device I / F unit 109 and the recording device I / F unit 105 in the state of the data of five levels for each color. Subsequent index expansion processing in step S204 is performed by the recording apparatus main control unit 101 in the recording apparatus.

  FIG. 3 shows an example of how to use pigment black in single-sided printing.

  In this example, an example of using ink in a gray line is given. In this case, the color is composed of three colors of CMY in the bright part starting from white, and the pigment black is used in the dark part toward black, and the amount of CMY ink gradually decreases. At the end, printing is performed only with Bk ink, and CMY ink cannot be applied.

  In this way, by using abundant pigment black, the density of black increases and characters appear to be tightened.

  FIG. 5 is a flowchart showing the flow of processing in the present invention.

  First, in S401, an image to be printed is input from various applications.

  Next, in S402, it is specified whether the user designation for the current job is single-sided printing or double-sided printing for the current printing.

  If it is single-sided printing, a color conversion table for single-sided printing is set in the color conversion processing unit in S403. In this case, the amount of ink applied to the black portion is the color conversion table as described with reference to FIG. 4 so that printing with 100% Bk is performed as shown in FIG.

  If double-sided printing is performed, it is determined in step S404 whether the printing purpose is a document or a CAD drawing. If it is a document or CAD drawing, a color conversion table for single-sided printing is set in the processing unit at 405.

  Normally, in a character image, the amount of ink applied to pixels included in the character itself is high, but almost no ink is applied to the periphery thereof. It has been empirically confirmed that even if there is a region where the amount of applied ink is locally high, no adverse effect is caused during double-sided recording. On the other hand, reducing the amount of ink applied to the character portion results in a deterioration in character quality than expected. Therefore, in the present invention, even in double-sided recording, printing is performed without reducing the use amount of the pigment Bk and without degrading the quality when printing an image centered on characters and line drawings.

  For other purposes, a color conversion table for double-sided printing processing is set in the processing unit in S406.

  This color conversion table for double-sided printing is one in which the amount of pigment Bk used is suppressed as compared with the color conversion table for single-sided printing.

  FIG. 6 shows an example of a gray line in that case. In this conversion table, the ink shot in the black portion is different from the usual, and the amount of pigment Bk shot is reduced as shown in FIG. 6, and instead the amount of ink shot of CMY as the s dye is increased. By doing this, the density of black drops compared to when the pigment Bk is 100%, but the drying time is shortened. After printing one sheet, it prints on the next sheet, discharges it, and prints Time to overlap can be shortened.

  Thereafter, color conversion processing is performed using the table set in S407. This processing itself is as shown in FIG.

  In the above example, the use of pigment Bk ink is suppressed when printing a document or CAD drawing by double-sided printing. However, depending on the configuration, printing of pigment Bk may be suppressed only in the high-speed mode.

  In this example, the amount of the pigment Bk used is reduced. However, in double-sided printing, the pigment Bk may not be used at all for printing in the dark portion, and printing may be performed using only the dye CMY.

  In this way, it is possible to increase the throughput of printing by suppressing the use of pigment ink that causes drying when it is slow and rubs when printing for purposes other than documents and CAD drawings with double-sided printing, In addition, when the purpose is to print a document or a CAD drawing, it is possible to print with a black density secured.

[Industrial applicability]
The present invention is effective for an ink jet printer that uses at least one kind of pigment ink and a plurality of other dye inks for printing.

It is a perspective view for demonstrating schematic structure of a serial type inkjet recording device. 1 is a block diagram for explaining an ink jet recording system including an ink jet recording apparatus applied to an embodiment of the present invention and a main apparatus connected to the recording apparatus and responsible for main image processing. It is a flowchart for demonstrating the flow of the image processing performed with an inkjet recording system. It is a schematic diagram of the amount of ink applied in conventional black. It is a flowchart which shows the flow of a present Example. FIG. 6 is a schematic diagram of an ink ejection amount in black in which pigment Bk ejection is suppressed in the present example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conveyance roller 2 Pinch roller 4 Recording head 7 Carriage 12 Discharge roller 13 Spur 16 Reversing means 101 Recording apparatus main control part 102 Recording buffer 104 Feeding / discharging control part 105 Recording apparatus I / F part 106 Data buffer 107 System bus 108 Main apparatus Main control unit 109 Main device I / F unit 110 Display unit 111 Operation unit 112 System bus 113 Carriage motor control unit

Claims (4)

In an inkjet printer that has means for performing double-sided printing using multiple colors of ink, and at least one of the inks used for printing uses pigment ink,
There is a means for the user to specify the printing purpose, and printing is performed without using pigment ink when performing double-sided printing for a specific printing purpose among the specified printing purposes. Inkjet printer.   2. The ink jet printer according to claim 1, wherein a pigment ink is used only for black ink, and printing is performed without using the pigment ink for double-sided printing. In an inkjet printer that has means for performing double-sided printing using multiple colors of ink, and at least one of the inks used for printing uses pigment ink,
There is a means for the user to specify the printing purpose, and within the specified printing purpose, the amount of pigment ink used is reduced and the amount of other dye inks used for double-sided printing. An ink jet printer characterized by increasing printing. In an inkjet printer that has means for performing double-sided printing using multiple colors of ink, and at least one of the inks used for printing uses pigment ink,
There is a means for the user to specify the printing purpose. When the high-speed printing mode is specified by the user's operation during double-sided printing, the pigment ink can be used for a specific printing purpose. An ink-jet printer that reduces the amount used and increases the amount of other dye ink used for printing.

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