JPH04303659A - Automatic color matching device - Google Patents

Abstract

PURPOSE:To provide an automatic color matching device capable of rapid color matching for printed matter and the minimized loss of sheets at the beginning of a printing process. CONSTITUTION:The image of a proofed sheet or a finally proofed sheet is read by ink color component and this data is calculated by an area corresponding to the key zone of a printing device, to obtain the density value of each key zone. Thus, the opening degree of an ink key is adjusted based on the density. Further, a printed book is picked up for density detection and the density is compared to a density corresponding to a preset key opening degree. Finally the key opening degree is adjusted in accordance with the comparison difference.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic color matching device that adjusts in advance the opening degree of each ink key of a printing press and appropriately sets the amount of ink supplied.

0002

[Prior Art] In recent years, in offset printing, the ink supply amount is adjusted according to the pattern before printing, reducing paper waste at the beginning of printing, shortening the time from test printing to regular printing operation, etc. "Ink preset system"
is being widely introduced. This refers to the image area (
It optically distinguishes between low-reflectance areas) and non-image areas (high reflectance areas), and adjusts the image area ratio (area of image areas/total area of the plate) to correspond to the ink key of the ink fountain of the printing press. Measurements are made in advance for each key zone, and the key opening degree of each ink key is determined before printing based on the measured pattern area ratio, and the amount of ink is adjusted in accordance with the pattern before printing. This system has already been put into practical use for some time and is becoming established as a general printing technology.

[0003] As described above, in the conventional system, the key opening degree was adjusted based on the measurement result of the picture area ratio of the printing plate. Here, before creating a printing plate, first, a proof is made using a proof plate, and the client looks at the proof and checks the color tone of the printed matter. Then, a printed version is created based on a proof sheet that has been proofread by the client and does not require any correction, or a proof sheet that requires correction but does not need to be proofread again. However, due to unpredictable factors during the printing plate creation process, such as during printing and development, the printing plate may not reflect the client's desired color tones. Therefore, even if the key opening degree is adjusted based on the pattern area ratio of the printing plate, it may not be possible to obtain a printed matter with a color matching that of the proof paper or proof paper. Therefore, it still takes time to match the colors, and it is not possible to prevent the occurrence of paper waste at the beginning of printing.

0004

[Problems to be Solved by the Invention] The present invention has been made to address the above-mentioned circumstances, and its purpose is to provide automatic color matching that can quickly perform color matching and reduce paper waste at the beginning of printing. The purpose is to provide equipment.

[0005]

[Means for Solving the Problems] The automatic color matching device according to the present invention includes a sensor means for optically reading image information of a printed matter, and an output of the sensor means for each ink key zone, and for each color in each ink key zone. The apparatus includes means for determining the density of each ink, and means for supplying the determined density to each ink key for each color as opening degree information.

[0006]

[Function] According to the automatic color matching device according to the present invention, the density of each color in each key zone of an actual printed matter such as proofing paper or proofing paper is determined instead of a printing plate, and the ink key is adjusted accordingly. By adjusting the opening degree, printed matter with the color desired by the client can be obtained in a short time, and the amount of paper waste at the beginning of printing can be reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an automatic color matching apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is an external view showing the outline of this embodiment, and FIG. 2 is a plan view. A sample table 12 on which printed matter 10 is placed is provided on the upper surface of the apparatus main body. Examples of printed matter include proof sheets such as proof sheets and approval sheets, and actual printed materials (hereinafter referred to as printed books). Here, eight pages of printed matter constitute one sheet. A reading head 14 consisting of a line sensor is arranged above the sample table 12. The reading head 14 is arranged along the left-right direction of the sample table 12, and is moved in the front-back direction of the sample table 12 by scanning mechanisms 16 provided on both sides of the apparatus main body. Thereby, the image information of the printed matter 10 is optically read. Although not shown, the image reading surface of the reading head 14 is colored red (R).
, green (G), and blue (B) filters are attached, and image information for each color is output from the reading head 14.

The output of the read head 14 is provided to a control circuit as shown in FIG. The control circuit may be provided within the device main body or may be provided separately from the device main body. Image signals of R, G, and B color components outputted from the reading head 14 are supplied to an RGB/YMCK converter 30, and the image signals are converted into signals for each ink color used for printing, that is, yellow (Y), yellow (Y),
It is converted into image signals for red (M), indigo (C), and black (K). The Y, M, C, and K image signals are supplied to an arithmetic circuit 32, where they are totaled (integrated) for each key zone of the printing press, and the color density of the printed matter for each key zone is determined. The key zone is the area corresponding to the ink key in the ink fountain of the printing press.
In FIG. 2, the leftmost key zone 40 is shown by a dashed line. It is assumed that a large number of ink fountains of a printing press are arranged in a row corresponding to the horizontal direction of the printed matter 10 in FIG. For this reason, the printed matter 10 must be placed on the sample table 12 in such an orientation that the key zone is perpendicular to the reading head 14. This density signal for each color and each key zone is supplied to a printing machine (not shown),
The key opening degree is controlled based on this.

On the other hand, in front of the sample table 12 of the main body of the apparatus, as shown in FIG. 2, a display section 18 is provided which displays the key opening degree (density) for each key zone as a bar graph. The display section 18 consists of two lines of display sections 18a and 18b, and the display section 18a is a proof sheet (proof sheet or proof sheet).
Indicates the key opening degree obtained when reading the image information of
The other display section 18b shows the key opening degree obtained when reading the image information of the printed book. Further in front of the display section 18, a switch 20 for manual adjustment of the key opening degree is provided. The switch 20 also consists of a plurality of key opening/closing switches provided for each key zone.

As shown in FIG. 3, the signal from the switch 20 is supplied to the arithmetic circuit 32, and the display section 18 is connected to the arithmetic circuit 32.
Connected to the output of 2.

Referring to the flowchart shown in FIG.
The color matching operation according to this embodiment will be explained. First, make a proof and show the proof to the client. After the client's proofreading is completed, the proof sheet or proof sheet is returned to the printing shop. Based on this, the operator performs color matching and creates a printing plate. As shown in step #10, place the proofing paper or proofing paper on the sample table 12, and while moving the reading head 14, check the R and B of the proofing paper or proofing paper.
, G. Read image information for each color component. read head 14
The image signal output from the RGB/YMCK converter 30
image information for each ink color, and further, step #1
As shown in FIG. 2, the density values for each key zone are totaled by the arithmetic circuit 32, and an integral value is determined. In the case of proof paper, since the density of the image on the proof paper is equal to the image density of the target printed book, the integral value for each key zone becomes the key opening degree. However, in the case of liability paper, the hue may be partially different from the color desired by the client, so the totalized integral value cannot be directly used as the key opening degree. That is, since various corrections are indicated in red on the release sheet, it is necessary to correct the key opening determined according to the image density read by the reading head 14 in accordance with the instructions on the release sheet. This is shown in step #14. Step #
14 is not necessary in case of proofreading paper. Specifically, the operator operates the switch 20 according to the key opening graph on the display section 18a and the instructions on the responsibility sheet to correct the key opening. The key opening degree graph also changes due to the modification, but the value before modification is also displayed so that the degree of modification can be recognized. Thereafter, in step #16, the key opening degree signal is transferred to the printing press and supplied to the ink key of the ink fountain as a control signal, and the key opening degree is determined (preset).

[0012] As a result, the key opening degree can be preset according to the hue of the actual printed matter rather than the pattern area ratio of the printing plate, so the time required for color matching can be shortened, and losses at the beginning of printing can be reduced. Paper can be reduced.

In this embodiment, a sampling inspection is performed for further adjustment of the key opening degree after presetting. That is,
After the printing plate is created, printing of the printed book starts as shown in step #18, and after a predetermined number of sheets have been printed or after a predetermined period of time has elapsed, one sheet of the printed book is pulled out as shown in step #20. . As shown in step #22, the printed book is placed on the sample table 12, and the image information of the printed book is read in the same way as in the case of proof printing. Step #24
Then, the arithmetic circuit 32 aggregates the density values for each key zone of the printed book, calculates an integral value, and displays the integrated value as a key opening degree graph on the display section 18b. Here, if the ink supply amount is appropriate, the density of the printed book and the density of the proof paper (preset key opening degree) match, but if it is not appropriate, it is necessary to adjust the key opening degree. Therefore, in step #26, it is determined whether the two match, and if they do not match, the arithmetic circuit 32 changes the key opening signal according to the difference between the two, as shown in step #28, Control so that both match. At this time as well, the display section 18b displays the key opening degree determined from the density value of the printed book and the adjusted value so as to be distinguishable. Instead of or in addition to the automatic control of the arithmetic circuit 32, the operator uses the switch 20 to control the key position by referring to the key opening degree graph displayed on the display section 18, as in the case of the liability paper. The opening signal may be changed. After this, the process returns to step #20 and a sampling inspection is performed again. When it is detected in step #26 that the preset value and the measured value match, the color matching is ended. Note that after adjusting the key opening degree in step #28, the process may be terminated without performing another sampling inspection.

As explained above, according to this embodiment, the image information of the proof sheet is optically read, the key opening degree is preset based on the density of each color, and furthermore, the first sheet of printing is extracted, The image information is also read, the density of each color is detected, and if the density does not match the preset density, the key opening degree can be further adjusted to match the colors in a short time and reduce paper waste. can be reduced. Furthermore, since it also has a function to correct the density value read at the time of presetting, color matching can be performed not only based on proof paper but also on proof paper.

The present invention is not limited to the embodiments described above, but can be implemented with various modifications. For example, the key opening degree for the black plate is preset based on the picture area ratio of the printing plate, as in the conventional system, and there is no need for subsequent adjustment. Also,
The reading head for reading the image information of the printed book does not have to be shared with the head for proofing. In this case, since the head can be attached to the printing machine, there is no need to take out the printed book, and there is an advantage that it can be inspected online.

[0016]

[Effects of the Invention] As explained above, according to the present invention, the density of each color in each key zone of an actual printed matter, such as proofing paper or proofing paper, rather than a printing plate, is determined, and the density of each color is determined accordingly. To provide an automatic color matching device that can quickly perform color matching and reduce paper waste at the beginning of printing by adjusting the opening degree of an ink key.

[Brief explanation of drawings]

FIG. 1 is an external view schematically showing an embodiment of an automatic color matching device according to the present invention.

FIG. 2 is a plan view of the device of FIG. 1;

FIG. 3 is a block diagram of a control circuit of one embodiment.

FIG. 4 is a flowchart showing a color matching operation according to one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10...Printed material, 12...Sample table, 14...Reading head, 16...Scanning mechanism, 18...Display part, 20...Switch, 30...RGB/YMCK converter, 32... Arithmetic circuit.

Claims (1)

[Claims] 1. An automatic color matching device for adjusting the opening degree of an ink key of a printing press, comprising: a sensor means for optically reading image information of a printed matter; and an output of the sensor means for each ink key zone. 1. An automatic color matching device comprising means for determining the density of each ink of each color, and means for supplying the determined density to each ink key of each color as opening degree information.