JP2011126264A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce stripe-like noises in an inkjet recording device comprising line head structure. <P>SOLUTION: The inkjet recording device includes: a recording unit that has an inkjet head unit composed of a plurality of the connected line heads and records an image to a recording medium; an acquisition unit that acquires pixel information shown by pixel of an original; a storage unit that stores seam position information of the head unit and head characteristics information; a prediction unit that obtains output characteristics of each printing direction of printed matter from the pixel information, position information and head characteristics information; and a turning unit that changes the printing direction where influences of the seam head unit on the original are minimized based on the output characteristics of the prediction unit to form an image and output it to the recording unit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus.

  In recent years, in order to increase the speed of printing and recording, there have been appeared ones in which a plurality of inkjet head units are connected to form a line head configuration, and an image is recorded on a sheet in one pass or a smaller number of scan passes. In such an ink jet recording apparatus, since there has been an error in the recording accuracy of the ejection characteristics of each nozzle, the recording unevenness of each ink nozzle has been corrected by performing a complicated multi-scan. In addition, when a plurality of inkjet heads are connected, in this joint part, due to the attachment position accuracy between the heads, the characteristic variation between the heads, the difference in the ejection characteristics of the head end part itself, etc., White streaks, black streaks, density steps, and the like were generated, giving visual discomfort as streak noise (hereinafter, streak noise). Conventionally, even for such a line head, a method of reducing streak noise by performing the complicated multi-scan or the like has been proposed. Further, Patent Document 1 proposes a method of reducing streak noise by gradually shifting the position where the multi-head is divided depending on the position in the sub-scanning direction.

JP 2008-62515 A

  However, the above-described method for performing multi-scan has a problem that the printing speed is reduced as the multi-scan is executed. Further, the method of shifting the head division position is not easy to finely adjust the division position.

  Accordingly, the present invention provides an ink jet recording apparatus that can reduce the appearance of noise without performing multi-scanning or fine adjustment of the head in order to prevent streak noise generated at the joint of the multi-head. The purpose is to do.

  In order to achieve the above object, an ink jet recording apparatus of the present invention has an ink jet head unit composed of a plurality of connected line heads, and a recording unit for recording an image on a recording medium and a pixel of an original are shown. From the acquisition unit that acquires pixel information, the storage unit that stores the position information and head characteristic information of the joints of the head unit, and the output characteristics according to each printing direction of the printed matter from the pixel information, position information, and head characteristic information. A prediction unit to be obtained, and a direction changing unit that generates an image by changing the print direction to minimize the influence of the joint of the head unit on the original based on the output characteristics of the prediction unit, and outputs the image to the recording unit With.

1 is a block diagram showing a configuration of an ink jet recording apparatus according to an embodiment of the present invention. Conceptual diagram showing an example of the noise state of the recording apparatus 1 is a flowchart showing the operation of the recording apparatus shown in FIG. Diagram showing the relationship between print direction and layout Diagram showing the relationship between print direction and layout Diagram showing the relationship between print direction and layout Diagram showing the relationship between print direction and layout Diagram showing the relationship between print direction and chromaticity distribution Diagram showing the relationship between print direction and chromaticity distribution Diagram showing the relationship between print direction and chromaticity distribution Diagram showing the relationship between print direction and chromaticity distribution Schematic diagram for explaining calculation of average chromaticity of block Diagram showing visual color discrimination ellipse

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is an overall view of an embodiment of an apparatus in which the present invention is applied to a multifunction peripheral (hereinafter referred to as MFP). The MFP 1 has an acquisition unit 2 that acquires pixel values, a storage unit 3 that stores head unit joint position information and head characteristic information, and a prediction that determines output characteristics of a printed matter from the pixel values, position information, and head characteristic information. Unit 4, a direction changing unit 5 for converting an image into an optimum direction based on the result obtained by the prediction unit, and an inkjet head unit for spraying ink on a recording medium, for example, paper based on document or image data A recording unit 6 is provided, and is connected to a terminal such as a personal computer (hereinafter referred to as PC) 8 via a network 7. The PC 8 incorporates an application program 9 typified by document creation and paint software and a printer driver 10 that gives a print command to the MFP 1.

  Here, when the user instructs printing of a document or image created / edited on the PC 8 via the printer driver 10, print data is sent to the MFP 1, the direction of the image is changed as necessary, and the recording unit 6. A hard copy is created by the inkjet head unit.

  FIG. 2 is a schematic diagram showing the configuration of the inkjet head unit. Since it is difficult to make a long inkjet head, a plurality of heads are arranged in a staggered manner as shown in this figure. There is no problem if the characteristics of the head are always uniform, but there are limits to maintaining uniformity in terms of yield and cost. Therefore, it is often the case that heads with some variation are connected and arranged.

  In order to prevent noise from being generated at the central joint that is most easily noticeable, the heads 20 are joined together with a small difference between the heads. However, it is difficult to match up to the joint part off the center, and a part with a large difference occurs. For example, as shown in this figure, the center seam 21 hardly causes unevenness, but a slightly larger streak noise appears at a position 22 slightly away from the center and a position 23. . Similarly, although the central seam of the color unevenness is suppressed, there is a high possibility that a portion with large unevenness appears at the seam away from the center.

  The streak noise is conspicuous in the portion where the seam unevenness is large, and it is considerably disturbing particularly when the streak noise is applied to a uniform region where the pixel values such as photographic images are intermediate. On the other hand, if the image is a character image or graphic image in which there is no intermediate and uniform pixel value, even if streak noise is applied, it will not be noticed. Therefore, in this embodiment, the direction of the image is changed so that the streak noise is arranged in a place where it is not noticeable on the screen as much as possible. In addition, regarding color unevenness, if it is difficult to place white or solid portions, or only white or solid at locations where color unevenness is large, it is desirable to dispose a color in which color unevenness is not noticeable.

  In the embodiment of the present invention, in order to realize this, in the following procedure, when a print execution command is given from the PC 8 as shown in FIG. 1, the processing procedure will be described with reference to the flowchart of FIG. To do. When a print command is instructed on the PC 8 (100), the acquisition unit 2 acquires pixel information including, for example, a document layout from the PC 8 (101), and the prediction unit 4 acquires the pixel information from the acquisition unit 2. The head unit seam position information and head characteristic information stored in the storage unit 3 are acquired (102). The pixel information may include chromaticity distribution information.

  Next, the prediction unit 4 analyzes the layout from the pixel information acquired by the above-described operation (103). The distribution information of the chromaticity is analyzed (104), and the output characteristics of the printed matter are obtained based on the position information of the joints of the head unit and the information of the head characteristics. A direction in which the streak noise is most inconspicuous for printing is predicted from the output characteristics based on the layout and chromaticity distribution information and the head characteristic information (105). After the direction of the image is changed to the optimum direction (106), printing is executed by the recording unit 6 (107). The output characteristic of the printed matter is a pixel value at the time of output at the joint of the head unit.

  Next, how to determine the printing direction will be described. First, the direction in which the streak noise is not noticeable is determined as follows. 4 to 7 are schematic diagrams in which the image to be printed is turned 90 degrees. In this figure, a portion 30 indicated by a thick line is a position through which a joint where the streak noise is conspicuous passes. Comparing these, in all of FIGS. 4 to 6, the path of the joint where the streak noise is conspicuous just crosses the region of the photograph, so that the streak noise is likely to be an obstacle. On the other hand, FIG. 7 is the most preferable direction because the path of the seam is a region of characters and graphics where noise is not a concern.

  The printing direction is also referred to the chromaticity distribution of the image to be printed. 8 to 11 are schematic views in which the image to be printed is turned 90 degrees in the same manner as in FIGS. 4 to 7. It is assumed that the target image is an image including, for example, three types of color regions as shown in this figure. Each color area may be, for example, a color bar or a gradation pattern, and the classification of areas such as characters and photographs is the same. Further, the color unevenness of the line head to be used is assumed to be the largest at 30 joints.

  Here, the portion corresponding to the path of the joint where large color unevenness occurs crosses all the color regions in the direction of FIGS. 8 and 10, whereas in the direction of FIGS. 9 and 11, the joint is Only one color area passes. Therefore, the direction corresponding to FIGS. 9 and 11 may be selected so that the target color area corresponds to a color area with low color discrimination ability.

  The color discrimination ability for a certain area is obtained by the following procedure. As shown in FIG. 12, the image is divided into a plurality of blocks, vertically and horizontally, and the average chromaticity in the block is obtained. Further, as shown in this figure, a set of blocks traversed by the joint portion with large color unevenness, and the average chromaticity of each of the hatched area 50 and area 51 in this figure are obtained and stored in the storage unit 3. A color discrimination ability that refers to chromaticity described later as an address, that is, a value corresponding to the size of the discrimination circle is obtained from the table, and that value is used as a guideline for the color discrimination ability of the area. FIG. 13 shows a human visual color discrimination ellipse. The size of the ellipse is stored in the storage unit 3 for each chromaticity. The discriminant circle having the average chromaticity of the area obtained by the above-described operation when viewed on the chromaticity diagram is selected as the discriminant circle of the area. Here, it is preferable to select the direction crossing this low color discrimination area, that is, the high discrimination circle area, as the printing direction.

  If the selected direction is the same due to streak noise and color unevenness, that direction. If they do not match, the direction in which the streak noise is not conspicuous is prioritized and the printing direction is finally determined.

  When there are two or more directions in which the streak noise and color unevenness are minimized, the direction in which the sub-scanning direction is shortened is selected with priority.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 MFP
2 Acquisition unit 3 Storage unit 4 Prediction unit 5 Direction change unit 6 Recording unit

Claims (4)

A recording unit having an inkjet head unit composed of a plurality of connected line heads, and recording an image on a recording medium;
An acquisition unit that acquires pixel information indicated by pixels of the document;
A storage unit for storing position information and head characteristic information of a joint of the head unit;
A prediction unit for obtaining output characteristics according to each printing direction of the printed matter from the pixel information, position information, and head characteristic information;
An ink jet recording comprising: a direction changing unit configured to generate an image by changing to a printing direction that minimizes an influence of a joint of the head unit on the document based on an output characteristic of the prediction unit, and to output the image to the recording unit; apparatus.   The inkjet recording apparatus according to claim 1, wherein the pixel information includes document layout information.   The storage unit further stores chromaticity and color discrimination ability around the chromaticity, and the pixel information acquired by the acquisition unit includes chromaticity distribution information. 3. The ink jet recording apparatus according to 1 or 2.   The ink jet recording apparatus according to claim 1, wherein the output characteristic obtained by the prediction unit is a pixel value at the time of output at a joint of the head unit.

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