JP2011207102A - Bidirectional color difference correcting method, recording device, bidirectional color difference correcting program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bidirectional color difference correcting method that can eliminate a bidirectional color difference, and to provide a recording device, a bidirectional color difference correcting program and a recording medium.SOLUTION: The bidirectional color difference correcting method for correcting a color difference generated in bidirectional recording of the recording device having a head unit for recording images and capable of recording in both directions of a forward path and a return path of main scanning operation, includes computing a contrast ratio estimated from the density of cyanogen, magenta and yellow in bidirectional recording, and amplifying the density of three colors reaching first.

Description

  The present invention relates to a bidirectional color difference correction method, a recording apparatus, a bidirectional color difference correction program, and a recording medium, and more particularly to a bidirectional color difference correction method, a recording apparatus, a bidirectional color difference correction program, and a recording medium that can eliminate bidirectional color differences. .

  In an ink jet printer, a method of printing by reciprocating a carriage unit that ejects ink is the mainstream. At this time, it is possible to realize high-speed printing by ejecting ink in both directions of the forward path and the backward path and forming an image. However, uneven color (both sides) due to different landing orders of ink droplets in the forward path and the backward path Color difference) occurs. As means for avoiding bidirectional color difference, a method of designing a forward discharge portion and a return discharge portion in a carriage section symmetrically is already known. Furthermore, a method for reducing the color difference by switching the gamma table between the forward path and the return path is already known.

  For the purpose of correcting bidirectional color differences, a method of switching γ correction parameters according to the angle of the origin in the color space is disclosed (see Patent Document 1).

  However, the conventional method of having a forward discharge portion and a return discharge portion has a problem that the carriage portion becomes large and the manufacturing cost increases. In addition, there is a problem that the color difference cannot be completely eliminated in switching the gamma table.

  Although the invention described in Patent Document 1 suppresses the bidirectional color difference by software correction while using an asymmetric carriage portion, the problem that the bidirectional color difference occurs cannot be solved.

  The present invention has been made in view of such circumstances, and an object of the present invention is to eliminate bidirectional color differences while using an asymmetric carriage portion.

  The bidirectional color difference correction method according to the present invention includes a head unit that performs image recording, and corrects a color difference that occurs during bidirectional recording of a recording apparatus capable of recording in both forward and backward directions of the main scanning operation. In this bidirectional color difference correction method, the concealment rate estimated from the densities of cyan, magenta, and yellow during bidirectional recording is calculated, and the density of the three landing colors is amplified.

  A recording apparatus according to the present invention is a recording apparatus having a head unit for recording an image and capable of recording in both forward and backward directions of the main scanning operation, and includes cyan, magenta, and yellow during bidirectional recording. The concealment rate estimated from the density is calculated, and the density of black is amplified.

  A bidirectional color difference correction program according to the present invention has a head unit that performs image recording, and corrects a color difference that occurs during bidirectional recording of a recording apparatus capable of recording in both forward and backward directions of the main scanning operation. This bi-directional color difference correction program is characterized in that a concealment rate estimated from cyan, magenta, and yellow densities during bi-directional recording is calculated, and the computer is executed to amplify the black density.

  The recording medium according to the present invention is a computer-readable recording medium for recording the processing of the bidirectional color difference correction program according to the present invention.

  According to the present invention, it is possible to eliminate bidirectional color difference while using an asymmetric carriage portion.

It is a figure for demonstrating the mechanism of the inkjet recording device which concerns on embodiment of this invention. It is the figure which showed the example of schematic structure of the head unit 10 mounted in the inkjet recording device shown in FIG. FIG. 6 is a diagram for explaining an example of the operation of the head unit during bidirectional recording on the recording paper. It is a figure explaining the image before and behind correction which concerns on embodiment of this invention. It is a figure explaining the color conversion process flow which concerns on this embodiment compared with the conventional color conversion process.

  Embodiments of the present invention will be described below in detail with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

  In the first place, the reason why the color difference occurs depending on the scanning direction (landing order) is thought to be because the ink that landed first is hidden by the ink that landed later. In the prior art, since “the amount of ink landed later” is not taken into consideration, the color difference cannot be sufficiently corrected. In the present embodiment, the amount of ink droplets that land first is amplified according to the area estimated to be concealed by ink droplets that land later. By performing this correction, it is possible to faithfully represent the density of the finally formed droplets, and it is possible to completely eliminate the bidirectional color difference by software correction while using an asymmetric carriage portion.

  In the present embodiment, when correcting the color difference between the forward path and the backward path in an apparatus that records an image in a bidirectional manner, the ink droplet that lands first depends on the area that is estimated to be hidden by the ink droplet that lands later. Is characterized by amplifying the amount of.

  FIG. 1 is a diagram for explaining the mechanism of the ink jet recording apparatus according to the present embodiment. In the figure, 1 is a frame, 2 and 3 are guide rails, 4 is a carriage, 5 is a guide plate, 6 is a drive gear, 7 is a sprocket gear, 8 is a platen, 8a is a feed knob, 9 is a pressure roller, and 10 is a head. A unit 15 is a recording sheet.

  In this ink jet recording apparatus, a carriage 4 is movably mounted on guide rails 2 and 3 horizontally mounted on a frame 1, a head unit 10 is mounted on the carriage 4, and a drive source such as a motor (not shown) is used. A feed knob that allows the carriage 4 to move in the direction A in the figure and that rotates the recording paper 15 set on the guide plate 5 via a drive gear 6 and a sprocket gear 7 by a drive source (not shown). It is taken in by the platen 8 provided with 8a, and can be conveyed in the direction B in the drawing by the pressure roller 9 that is in pressure contact with the periphery of the platen 8.

  In the ink jet recording apparatus, the recording paper 15 is transported in the sub-scanning direction (B direction) while moving the head unit 10 in the main scanning direction (A direction), and ink droplets are ejected from the head unit 10. The image is printed on the recording paper 15.

  FIG. 2 is a diagram showing a schematic configuration example of the head unit 10 mounted on the ink jet recording apparatus shown in FIG. In FIG. 2A, the head unit 10 is composed of ejection units 11, 12, 13, and 14 corresponding to the respective colors. Usually, recording is performed by ejecting ink droplets on the surface of the paper from the head unit 10 in which the ejection units 11, 12, 13, and 14 are integrated. These ejection units 11, 12, 13, and 14 have a plurality of ink ejection nozzles. Further, FIG. 2B shows a state in which the droplets ejected from the head unit 10 are recorded on the recording paper 15.

  FIG. 3 is a diagram for explaining an example of the operation of the head unit during bidirectional recording on the recording paper 15. The ejection units 11, 12, 13, and 14 are configured in the order of black, cyan, magenta, and yellow (hereinafter referred to as K, C, M, and Y) with respect to the main scanning forward recording direction. The arrangement order and the number of colors are not necessarily limited, and units with different arrangement orders and more colors may be added depending on the ink characteristics and the design concept.

  In the case of the head unit 10 shown in FIG. 3, ink is ejected in the order of K → C → M → Y at the same location during forward recording. Naturally, in the reverse recording, the recording is performed in the reverse order of Y → M → C → K. However, as ink colorant fixing characteristics, when ink droplets of different colors are driven into the same location, There is a characteristic that the color of the ink landed on the paper surface first becomes dominant.

  FIG. 4 is a diagram for explaining images before and after correction according to the present embodiment. In the pre-correction image, it can be seen that the ink that landed first is concealed by the ink that landed later, and the colors of the forward path and the backward path are different. In the corrected image, it can be seen that the color difference is reduced by amplifying the ink that landed first in consideration of the area concealed by the ink that landed later. In FIG. 4, the images of the forward path and the backward path appear to be completely different, but since the ink droplets are composed of fine dots, the colors match when the printed matter is perceived as vision.

  FIG. 5 is a diagram for explaining a color conversion processing flow according to the present embodiment as compared with the conventional color conversion processing. In general, colors input in RGB are converted through a black component generation process (BG / UCR) [step S10], a correction process by γ conversion [step S11], and a gradation conversion process [step S12]. Since the position of γ conversion may be performed before BG / UCR, the order of processing is not limited to this.

  In the color conversion processing according to the present embodiment, CMYK 8 bits are input and CMYK 8 bits are output [color difference correction / step S3]. The specific correction processing (calculation) contents of the color difference correction processing according to the present embodiment will be described below.

<Arithmetic processing when the arrangement of the ink ejection sections is KCMY>
In the case of outbound: ink lands in order of K → C → M → Y
K = K ÷ (1-Y × concealment factor) ÷ (1-M × concealment factor) ÷ (1-C × concealment factor)
C = C ÷ (1-Y × concealment factor) ÷ (1-M × concealment factor)
M = M ÷ (1-Y × concealment factor)
Y = Y

In the case of the return trip: ink lands in the order of Y → M → C → K
K = K
C = C ÷ (1-K × concealment factor)
M = M ÷ (1-K × concealment factor) ÷ (1-C × concealment factor)
Y = Y ÷ (1-K × concealment factor) ÷ (1-C × concealment factor) ÷ (1-M × concealment factor)

  Here, the concealment rate coefficient will be described. As shown in FIG. 4, the ink that has landed first is partially covered by the ink that landed later. The part covered by the ink that has landed later does not disappear completely, but becomes difficult to see. The concealment rate coefficient expresses the ratio of the ink landed first by the ink landed later, as a coefficient. This coefficient varies depending on the properties of the ink (transparency, drying speed, ease of mixing) and the properties of the paper (absorption rate, ease of bleeding). Therefore, it is preferable to determine the optimum value by actual measurement.

  KCMY If the printer is composed of four colors of ink and the ink ejection section is aligned, the ink of the three colors C, M, and Y will land after the K ink has landed. It is expected that the concentration of K will decrease.

  In order to correct this, the concealment rate estimated from the density of the three CMY colors is calculated, and the K density can be obtained as expected by amplifying the K density.

  Similarly, by correcting C and M, all inks can be printed at their original densities. That is, the bidirectional color difference can be eliminated by correcting the density of the three colors that land first.

  Furthermore, the color difference between the forward path and the backward path can be eliminated by correcting CMY for the backward path.

  The concealment rate can be calculated by using a correction table in addition to the above-described examples of multiplication and division.

  A program for the CPU to execute the processing shown in each embodiment constitutes a program according to the present invention. As a recording medium for recording the program, a semiconductor storage unit, an optical and / or magnetic storage unit, or the like can be used. By using such a program and a recording medium in a system having a configuration different from that of each of the above-described embodiments and causing the CPU to execute the program, substantially the same effect as the present invention can be obtained.

  Although the present invention has been specifically described above based on the preferred embodiments, it is needless to say that the present invention is not limited to the above-described ones and can be variously modified without departing from the gist thereof.

1 Frame 2, 3 Guide rail 4 Carriage 5 Guide plate 6 Drive gear 7 Sprocket gear 8 Platen 8a Feed knob 9 Pressure roller 10 Head unit 11, 12, 13, 14 Injection unit 15 Recording paper

Japanese Patent No. 4115213

Claims (7)

A bidirectional color difference correction method for correcting a color difference that occurs during bidirectional recording of a recording apparatus having a head unit that performs image recording and capable of recording in both forward and backward directions of a main scanning operation,
A bidirectional color difference correction method characterized by calculating a concealment rate estimated from cyan, magenta, and yellow densities during bidirectional recording, and amplifying the density of the three colors that land first.   2. The bidirectional color difference correction method according to claim 1, wherein correction is performed for cyan and magenta based on the concealment ratio, and all inks are printed at their original densities.   3. The bidirectional color difference correction method according to claim 1, wherein correction is performed for cyan, magenta, and yellow on the return path to eliminate a color difference between the forward path and the return path.   4. The bidirectional color difference correction method according to claim 1, wherein the concealment rate is calculated using a correction table in addition to multiplication and division. A recording apparatus having a head unit for recording an image and capable of recording in both forward and backward directions of the main scanning operation,
A recording apparatus that calculates a concealment rate estimated from cyan, magenta, and yellow densities during bidirectional recording, and amplifies the density of black. A bidirectional color difference correction program for correcting a color difference that occurs during bidirectional recording of a recording apparatus that has a head unit that performs image recording and is capable of recording in both directions of the forward and backward passes of the main scanning operation,
A bidirectional color difference correction program that calculates a concealment rate estimated from cyan, magenta, and yellow densities during bidirectional recording, and causes a computer to amplify the density of black.   A computer-readable recording medium for recording the processing of the bidirectional color difference correction program according to claim 6.

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