Printing system

Abstract

This color patch has a plurality of white portions (102) arranged within a color patch region (101) constituted of a designated color to be reproduced on a printed work. A plurality of color portions (103) are arranged on the color patch region (101) having the plurality of white portions (102). The white portions (102) are arranged between adjacent color portions (103) among a plurality of arranged color portions (103).

Description

[Technical Field]

[0001] This invention ,mark Regarding printing systems. [Background technology]

[0002] In multi-color printing, such as offset printing, one method of color control involves measuring the solid color density to determine the difference from the target density and adjusting the color to approximate the target color. To measure solid color density, a color bar (control strip) is placed on a portion of the printed material, and solid color patches (color patches with 100% dot coverage) are printed within it.

[0003] Figure 7 shows a printed document produced by a printing press. A band-shaped color bar 2-2 is printed on the margins of the printed document 2, excluding the image area 2-1. In the case of four-color printing, for example, cyan (C), magenta (M), yellow (Y), and black (K), the color bar 2-2 consists of areas S1 to Sn, which include solid patches 2a1, 2a2, 2a3, and 2a4 prepared to measure the solid density of these four colors. Areas S1 to Sn correspond to the number of ink fountain keys in the printing unit for each color on the printing press. The width of each area S1, S2, to Sn corresponds to the width of the ink fountain keys. Therefore, the total width of the color bar is determined by the number and width of the ink fountain keys. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5022682 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, in offset printing (lithographic printing), for example, intermediate colors are reproduced by appropriately combining the halftone dots of the four CMYK colors. Therefore, in this type of color printing, when the size of the halftone dots changes on the printed material compared to the dots on the plate, the color that the human eye perceives also changes. Such changes in halftone dots on the printed material are not reflected in the color patch, and since the color does not change in the color patch, it is not possible to check the state of the halftone dots using color patch-based color management.

[0006] Therefore, conventionally, when color changes occurred due to changes in the size of halftone dots on printed materials, as described above, the printing operator would visually check the difference in color tone with the sample print and adjust the density. Visual color adjustment depends on the operator's skill, and the time, number of adjustments, and amount of wasted paper may increase unnecessarily.

[0007] This invention was made to solve the above-mentioned problems, and aims to enable color management using color patches even when the size of halftone dots on printed materials changes. [Means for solving the problem]

[0008] The color patch according to the present invention is a color adjustment color patch printed on the margin of a printed material printed by a printing press, and has a white area within the region of the color patch which is composed of a specified color to be reproduced on the printed material.

[0009] The printing system according to the present invention comprises a printing press capable of printing on a supplied sheet, a measuring instrument for measuring color matching data of color patches printed on the margins of a printed material printed by the printing press, and a controller that adjusts the amount of ink supplied to the printing press for printing the printed material based on the color matching data measured by the measuring instrument, wherein the color patches have white areas within the area of ​​the color patch composed of a specified color to be reproduced on the printed material. [Effects of the Invention]

[0010] As described above, according to the present invention, since a white-out portion is provided within the area of the color patch, color management can be performed using the color patch even if the size of the halftone dots on the printed matter changes.

Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a configuration diagram showing the configuration of a color patch according to an embodiment of the present invention. [Figure 2] FIG. 2 is a configuration diagram showing the configuration of another color patch according to an embodiment of the present invention. [Figure 3] FIG. 3 is a configuration diagram showing the configuration of another color patch according to an embodiment of the present invention. [Figure 4] FIG. 4 is a configuration diagram showing the configuration of another color patch according to an embodiment of the present invention. [Figure 5] FIG. 5 is a configuration diagram showing the configuration of another color patch according to an embodiment of the present invention. [Figure 6] FIG. 6 is a configuration diagram showing the configuration of a printing system according to an embodiment of the present invention. [Figure 7] FIG. 7 is a plan view showing an outline of a printed matter printed by a printing machine.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a color patch according to an embodiment of the present invention will be described with reference to FIG. 1. This color patch is provided on a plate for printing a printed matter, and is a color patch for color adjustment printed on the margin of the printed matter printed by a printing machine. The above-described printing machine is provided with a measuring device for measuring data for color adjustment of the color patch, and based on the measurement result of the measuring device, the data of the color patch is used for adjusting the color reproduced on the printed matter. This color patch is, for example, prepared on a lithographic plate in order to manage the color tone of a printing machine using four-color inks of cyan, magenta, yellow, and black, and constitutes a color bar printed by a lithographic printing machine.

[0013] This color patch has a white-out portion 102 within the area 101 of the color patch composed of the specified colors intended for color reproduction on a printed matter. In this example, within the area 101 of the color patch, there are a plurality of arranged white-out portions 102. In the area 101 of the color patch with the plurality of white-out portions 102, a plurality of color portions 103 are arranged. Among the plurality of arranged color portions 103, a white-out portion 102 is disposed between adjacent color portions 103. In this example, the plurality of white-out portions 102 are in a stripe pattern (stripe pattern) parallel to the conveyance direction of the printed matter and are arranged in a direction perpendicular to the conveyance direction.

[0014] The color patch can be provided for each of the four specified colors, for example, cyan, magenta, yellow, and black. For example, in the cyan color patch, the color portion 103 is cyan. For example, in the magenta color patch, the color portion 103 is magenta. For example, in the yellow color patch, the color portion 103 is yellow. For example, in the black color patch, the color portion 103 is black.

[0015] Also, in multicolor printing where specified colors of orange, green, and violet are added in addition to the four colors described above, color patches can be provided for each of orange, green, and violet in addition to cyan, magenta, yellow, and black. Note that it is not necessary to provide a white-out portion for all color patches.

[0016] Also, as shown in FIG. 2, the color patch can have the white-out portion 102a in a grid pattern within the area 101a. This example has a plurality of arranged white-out portions 102a, and in the area 101a of the color patch with the plurality of white-out portions 102a, a plurality of color portions 103a are arranged. Each of the plurality of color portions 103a is rectangular (square) and is arranged in a square pattern.

[0017] Furthermore, as shown in Figure 3, within region 101b, each of the white areas 102b in the color patch can be ring-shaped. This example includes multiple white areas 102b, and these multiple ring-shaped white areas 102b are arranged concentrically. The space between adjacent white areas 102b becomes the colored area 103b. In this example as well, region 101b includes multiple colored areas 103b.

[0018] Furthermore, as shown in Figure 4, within region 101c, the white portion 102c of the color patch can be spiral-shaped. In this example, one spiral-shaped white portion 102c can be formed continuously as a single unit. The region enclosed by the spiral-shaped white portion 102c, and the regions at the four outer corners of the spiral-shaped white portion 102c, become the color portion 103c. In this example, there is one color portion 103c formed integrally within region 101c.

[0019] Furthermore, as shown in Figure 5, within region 101d, the color patch can have a meandering meander shape for the white portion 102d. The meander-shaped white portion 102d can be formed as a continuous, integrated unit. The area other than the meander-shaped white portion 102d becomes the color portion 103d. In this example, region 101d has one integrally formed color portion 103d.

[0020] Next, a printing system according to an embodiment of the present invention will be described with reference to Figure 6. This printing system comprises a printing press 151 capable of printing on a supplied sheet (e.g., paper), and a measuring instrument 152 for measuring color matching data of color patches printed on the margins of the printed material printed by the printing press 151.

[0021] Furthermore, this printing system includes a controller 153 that adjusts the amount of ink supplied to the printing press 151 for printing based on the color matching data measured by the measuring instrument 152. As described above, the color patch has white areas within the area of ​​the color patch, which is composed of the specified color to be reproduced on the printed material. For example, the color patch may have multiple white areas arranged within the area of ​​the color patch. The controller 153 has, for example, the normal printing result of the color patch according to the above embodiment measured by the measuring instrument 152 as a reference. The controller 153 performs control by comparing the reference it has with the result measured by the measuring instrument 152 during the actual printing operation (see Patent Document 1).

[0022] As described above, since the color patch, which is composed of the specified color to be reproduced on the printed material, has a white area within it, changes in the size of the halftone dots on the printed material are reflected in the colored area, making it possible to perform color management using the color patch.

[0023] Below, we will compare the difference between using a solid patch and using a color patch of an embodiment that has multiple striped white areas 102, taking the case where the halftone dots are thickened as an example.

[0024] When using solid color patches, the density is adjusted to the standard value (the same as the sample print) by measuring the solid color patch. The ink density is the same as the sample, and theoretically, the printed material should have the same color. However, when examining the image in the printed material, the color tone may change due to other factors. For example, if the halftone dots appear thicker on the printed material, the area to be colored increases. Also, if the halftone dots appear thicker on the printed material, the colors of the image will appear darker to the human eye.

[0025] As described above, even if the halftone dots are thick on the printed matter, it is impossible to check (measure) the state of the halftone dots with a solid patch, so it is unclear how much the density should be reduced using the measurement results. Therefore, the operator has to perform color adjustment (such as reducing the density) while checking the color of the sample pattern.

[0026] On the other hand, when using a color patch (striped patch) having a plurality of white portions in a striped shape, if the halftone dots are thick on the printed matter, this state is reflected as a state where the color portions are thick even in the color patch, and the area of the plurality of white portions decreases. This state is also reflected in the result of measuring the color patch.

[0027] For example, in a proof print, measure the L * a * b * value of the striped patch of the printed matter with a measuring instrument. When the halftone dots are thick, the area of the white portions in the striped patch decreases, and relatively the area of the color portions increases, so the L * a * b * value in the measurement result changes. Using this measurement result, the color difference can be obtained, so the obtained value can be fed back and color adjustment (reducing the density) can be automatically performed. Note that the L * a * b * value is a commonly used color space system, where L * represents lightness, a * b * represents chromaticity. a * represents the red direction, -a * represents the green direction, b * represents the yellow direction, -b * represents the blue direction. Also, the color difference is the difference between colors, and is the value of the distance between the points of the reference color and the measured color on the L * a * b * color space.

[0028] Actual test printing revealed that the best results were obtained when automatic color adjustment was performed using striped patches with a color area ratio of 85%. In this test printing, the shape of the patch in plan view was 4.375 mm wide and 3.5 mm high. Under these conditions, it is believed that more accurate color management can be achieved by adjusting the color using striped patches with a color area ratio of 85%.

[0029] For example, in a rotary printing press, ink contained in an ink fountain is supplied to an ink fountain roller via multiple ink fountain keys, and the ink supplied to the ink fountain roller is then supplied to the printing plate via a group of ink rollers. As described above, the width of each region of the color bar shown in Figure 7 is determined by the width of the ink fountain key, so if a printing press equipped with a 35 mm wide ink fountain key is used, the width of one color bar region will be 35 mm. Therefore, the width of the above patch is the value obtained by dividing one color bar region (35 mm) into eight patches, totaling seven color patches and one colorless patch. Furthermore, the height of the above patch can be a value determined by the performance of the color tone control function consisting of the measuring instrument 152 and the controller 153, and can be a value between 3.0 and 5.0 mm, for example.

[0030] Furthermore, it has been found that using color patches with striped white areas parallel to the direction of transport of printed materials makes the system less susceptible to printing defects such as duplication and smudging that occur during printing.

[0031] As described above, according to the present invention, since the color patch includes a white area within its region, color management can be performed using the color patch even if the size of the halftone dots on the printed material changes.

[0032] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations are possible within the technical concept of the present invention by those with ordinary skill in the art. For example, although lithographic printing was described above as an example, the invention is not limited to this and can be similarly applied to other color printing methods. [Explanation of Symbols]

[0033] 101...area, 102...white area, 103...color area, 151...printing press, 152...measuring instrument, 153...controller, 2...printed material, 2-1...image area, 2-2...color bar, 2a1~2a4...solid patch, S1~Sn...color bar area.

Claims

[Claim 1] A printing press capable of printing on supplied sheets, A measuring instrument for measuring the L*a*b* values ​​as color matching data for color patches printed in the margins of printed materials printed by the aforementioned printing press, A controller that adjusts the amount of ink supplied to the printing press for printing the printed material based on the color matching data measured by the measuring instrument. Equipped with, The aforementioned color patch is composed of five or more specified colors to be reproduced on the printed material, and within the area of ​​the color patch, a white portion is provided. The color patch comprises a plurality of white areas arranged within the area of ​​the color patch, A printing system in which the multiple white areas arranged are in a striped or grid pattern parallel to the transport direction of the printed material.

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