JPS6085961A - Color shift detection in offset printing - Google Patents

Abstract

PURPOSE:To enable easy checkup of a color shift in printed matter by separating each symbol as a position adjusting mark for color shift from the other and arranging and displaying the symbol at an optional interval. CONSTITUTION:A piece of paper 1 whose symbols (a)-(d) are dyed in their own corresponding basic colors and are arranged at an equal interval, is provided at least at one spot in a direction where pieces of paper cross directly in a blank space of a multi-colored copy 2. These pieces are photographed with a filter and, as a result, films 22-25 for plate making indicating each colored part A-D and each symbols (a)-(d) corresponding to the former are obtained. For color shift detection, first a distance between lines of each symbols (s)-(d) on a piece of paper 1 on copy 2 is scanned by a camera 27 and detected data is stored into a memory circuit provided on a detection bench 26. Next, distance between lines of each symbols (a)-(d) on a printed matter 21 using a printing plate 3, 4, 5, 6 instead of the copy 2 is detected. And this detected output and the stored detected output are subjected to arithmetic operation for comparison by a key 30, thus discriminating a color shift accurately.

Description

[Detailed description of the invention]

The present invention relates to a method for detecting color misregistration in offset printing, which accurately detects color misregistration on a printed matter in multicolor offset printing, thereby making it possible to accurately adjust the position of a plate for each color. Generally, when printing in multiple colors using offset printing, the original is separated into basic colors and multiple plates are prepared for each color, and the blank paper to be printed is passed through each plate in sequence.
7) By overlapping colors one after another, a multicolored printed product is obtained. However, in order to prevent the colors of the multi-color printed plates from overlapping or misaligning with each other, the setting position of each plate is adjusted during trial printing. In order to make the above work easier, at present, marks for adjusting the position of color misalignment are marked on the top, bottom, left and right margins of each plate. Visually detect color shifts in the vertical and horizontal directions based on the degree of overlap.
The setting position of the plate of that color was adjusted by the amount corresponding to the color shift, and the same procedure was repeated until the seals of each color overlapped in a perfect match. deer

[However, the + mark above consists of a thin line of, for example, 0.1 mm or less, and it is extremely difficult to accurately adjust the color shift condition represented by this thin line by visual inspection.
Currently, there is no device that can accurately detect this, so adjustments to the above-mentioned color shifts in the vertical and horizontal directions are made using only the human eye and intuition, which requires long experience and high-level 9JI training. There was an inconvenience. The present invention has been developed lff1 in view of the conventional problems, and makes it possible to easily check the state of color misregistration on printed matter, and also to easily adjust the accurate setting position of each plate. It is an object of the present invention to provide a method for detecting color misregistration in offset printing. The present invention will be specifically described below based on illustrated embodiments. Figure 1 shows color misregistration position adjustment marks used in the color misregistration detection method in offset printing according to the present invention, and the color misregistration adjustment marks are arranged so as to be separated from each other at equal intervals. The four symbols a, h,
c and d, and in this embodiment, each of the above symbols α, b, c, and d is an appropriate paper slot 11 formed to a certain size.
shown above. The meanings of each of the above symbols a, b, c, and d are as follows. In other words, in multicolor offset printing, 21
As shown in Figure 2, from the multi-colored manuscript 2, a plurality of plates 3, 4, 5, and 6 are prepared that print only the basic colors, for example, red, blue, yellow, and black. be done. These plurality of plates, that is, plate 3 for red printing, plate 4 for blue printing, plate 5 for yellow printing, and plate 6 for black printing, each have an L color misalignment position adjustment mark. Either symbol a, h, c, or d is displayed. In other words, in the conventional method, the color fade position adjustment mark is used as a mark, and the cross mark as a registration mark corresponding to the combination of the symbols σ, ll, C, and d is used for each version 3, ll.
, 5 and 6 are displayed at the common predetermined position 115Y, but in the case of the color fade position adjustment mark in the implementation of the present invention, for example, as shown in Figure 2, the red part A
Printing plate = 3 has symbol a, blue part B printing plate 4
The yellow part C is the symbol C, and the printing plate 5 is the symbol C.
The black printing plate 6 has the symbol d displayed at each position. As a result, as shown in FIG. 3, the plate cylinders 8, 9, 10, . IIK above versions 3, 4, 5.6
The comb cylinders 12, 13, 14, 15, which are used for transferring from each plate 3, 4, 5.6, and the adjacent impression cylinder 16, are installed. When the paper 2o is passed between
is obtained, and as shown in Fig. 2, the printed matter 2
1, each color portion A, B, C, D corresponding to each color portion A, B, C, Dr above appears, and each symbol a, b corresponding to each basic color f1. c and d will be displayed as symbols α, A, c, and d. Therefore, the above versions 3.4.5. f) Each plate cylinder 8゜9.
If the set position of either Jl or any plate is misaligned when installing it on the plates No. 10 and No. 11, the mutual spacing formed by the symbols α, h, c, and rl displayed on the printed matter No. 21 may be incorrect. This does not match the original mutual spacing formed by the symbols a, lr, c, and d, and it appears that there is a so-called color shift. In other words, since the color shift in offset printing is generally considered to be about 3u+ at most, each symbol a
, h, c, c1. are arranged and displayed at equal intervals of 4+am, each symbol α, displayed on the printed matter 21,
h, c, and d do not overlap each other even if there is a color shift, and it is possible to easily determine which color, that is, which plate is shifted. In addition, any symbol α, h in each version 3, 4, 5, or 6 above.
, C, and d in this embodiment, as shown in FIG. 72, the following method is used. First, a piece of paper 1 in which the above-mentioned symbols α, h, c, and d are colored in their corresponding basic colors and arranged and displayed with equal mutual spacing is shown in Fig. 2. As shown in FIG. Next, from the above state, plate-making films 22, 23, 24, which are used to photograph only each basic color by applying a so-called filter,
At the same time, the plate-making film 22, 23.24° 25 is printed on a metal plate to obtain each of the desired plates 3°, 4.5.6°. At this time, since the above-mentioned plate-making films 22, 23, 24, and 25 are photographed mechanically, the respective color portions A and B. The correlation positions between 0, D and each symbol α, h, c, cL are not changed, and a so-called filter is applied. ,
Each color part A and B, respectively. C, D and the corresponding symbols a, A, 11", d are displayed. Therefore, even during plate making, each plate 3, 4, 5, 6 has a predetermined color portion. A, B, C
, D and predetermined symbols a, h, c, and d are displayed. That is, for example, in this embodiment, the film 22
, an image of the red part A and the symbol a of the original 2 is photographed, an image of the blue part B and the symbol a is taken on the film 23, an image of the yellow part C and the symbol C is taken on the film 24, and the image of the yellow part C and the symbol C is taken on the film 23. Similarly, images of the black area and symbol d are photographed at 25. As another method, suppose that Figure 2 is used, but the manuscript 2 has a piece of paper 1 on which each of the above symbols α, h, c, and d is displayed.
Skip pasting t7, and from this state, manually prepare films for each basic color. Each of these films is then placed on a so-called mount (not shown), and from this state the plate-making film 22.23° 24.25 is manually manipulated. In this case, the paper strips 1 are provided on the mount at least one location in directions perpendicular to each other. As a result, each film for each of the above-mentioned plate making was 22°23.24
．． 25, each symbol a, h, c, d will be displayed at the fixed position, so the plate-making film 22,
At steps 23, 24, and 25, or at steps 3, 4, and 5°6 for each color printing plate, only necessary symbols are left on each plate. That is, on the plate 3 for printing the red portion A, only the symbol a is left and all the others are erased. In addition, the plate 4 for printing the blue part B has the symbol Rinori, and the plate 5 for printing the several color parts C only has the symbol C.
On the plate 6 for the black stamp 1ii+1, the symbols dσ) remain, and all others are erased. As a result, each plate 3, 4, 5.6 has predetermined color portions A, B, G, D and corresponding symbols Q, h,
C and d will be displayed. As described above, each symbol α as a mark for adjusting the color shift position on the paper piece 1 pasted on the original 2 or on the mount.
, l), (2, d are the corresponding versions 3, 4 with their array positions unchanged)
, 5.6, and each symbol α, h,
The distance between the lines c and d is for each version 3, 4. , 5, and 6. If the set position of any plate is set at A1, the misalignment will be caused by the gap between the lines mentioned above. This will appear as a narrowing of the distance. Therefore, in the offset printing color shift detection method according to the present invention, as shown in Fig. 4, first, the document 2 is positioned at the installation position of the detection table 26, and the paper piece on the document 2 is The line distances of the symbols a, h, c, and d above are scanned using the scanning camera 27, and the detected data is stored in the memory circuit provided on the detection stand 26, and the magnetic tape section 2
8 and display it on the CRT 29. Next, the printed matter 21, which is a product, is replaced with the original 2 on the detection table 26.
At the same time, the distance between the lines is detected in the same manner as described above, and this detection output and the stored detection output are compared and calculated by operating the operation key 30. This makes it possible to determine the numerical value of the error, and also to easily determine which plate is causing the color misregistration, making it possible to more advantageously adjust the setting position of the plate that is causing the color misregistration. . Figures 1 and 5 are block diagrams of signal system circuits, where d is a memory circuit that stores the line distances of each symbol a, h, c, and t on the original plate 2 as reference data, and 32 is a memory circuit that stores the line distances of each symbol a, h, c, and t on the original plate 2. Printed matter 2
The data in both memory circuits a+ and a2 are compared and computed in the arithmetic circuit 3+3 as data corresponding to the error in the distance between drawing lines, and the arithmetic output is sent to the other memory circuits. 314, the printing machines 3 and 5 are operated based on the calculated output, and the information is displayed on the display 36. Note that this signal system circuit can be configured to handle either digital signals or analog signals, and the means for detecting the distance between the lines of each symbol al"'l'1d may be a detection camera such as a television camera, or a detection camera such as a television camera. It can also be replaced with various optical means, such as a combination of a light emitting element and a light receiving element, or one that projects and reflects a laser beam.Therefore, the color misregistration position adjustment mark used in the present invention is suitable for use with multicolor originals. Symbols (1, b, C, d) corresponding to each of the basic colors of the berth color-coded from 2 (1, b, C, d) are sufficient as long as they are separated from each other at arbitrary intervals and displayed in an array; for example, the symbols a, h, It goes without saying that c and d may be broken lines, curved lines, etc. in place of the straight lines in the above-mentioned embodiments.Also, the symbols α, b, c, and d can be respectively assigned to one of the basic colors. It is not necessary to limit the color to a special color as long as it corresponds to the corresponding basic color, but for example, it may be colored in the same color as each corresponding basic color. When shooting film for each basic color, use film 22.2 for plate making for each basic color.
3, 24, and 25, only the symbols corresponding to the respective basic colors are directly displayed on the plate-making film. Furthermore, in this embodiment, each symbol a. It is assumed that h, c, and d are displayed in advance on the piece of paper 1, and the said piece of paper 1 is pasted on the manuscript 2, etc., but instead of this, it is assumed that they are displayed on the manuscript 2, etc. or on the plate-making It may also be displayed directly on the films 22, 23, 24, 25 using appropriate means. As described above, according to the present invention, the symbols, which are so-called register marks, as marks for adjusting the position of color misalignment, are separated from each other and arranged and displayed at arbitrary intervals, so that the symbols are displayed on printed matter, which is a product. Each symbol has the advantage that there is no risk of overlapping, making it easier to see which plate is causing the color misregistration, and each line of the color misregistration position adjustment mark initially displayed on the manuscript etc. Detect the distance while scanning with optical means, temporarily store this, and
Each line on the printed material printed by the plate is scanned by the optical means to detect the distance between the lines, and this detected data and the stored data are compared and calculated, and the error in the distance between the lines is determined by the calculation. By displaying numerical values on the display means, the state of color fading in the image of each plate can be detected quickly and accurately.If this is used as setting position adjustment data for each plate, it is possible to accurately determine the color fading of each plate. This has the advantage that positioning can be performed.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of a color shift position adjustment mark used in carrying out the method according to the present invention, Fig. 2 is a schematic system diagram from a manuscript to printed matter via platemaking, and Fig. 4. 3 is a schematic diagram of an offset printing press, Figures 4 and 4 are schematic perspective views of a color misregistration detection feed, and Figure 5 is a block circuit diagram of a signal system for detecting color misregistration. 1... piece of paper, 2... contested manuscript, 3, 4, 5.6... version, 21... printed matter, A, B, C, D... colored part, a
, h, c, cl... symbols. Representative Patent Attorney Izumi Ohno

Claims (3)

[Claims] (1) In addition to displaying color misregistration position adjustment marks at fixed positions on multiple plates, each of which is printed for each basic color by an appropriate means from a multicolor manuscript, printing using the above-mentioned board In the color blur detection method in offset printing that inspects the color misalignment A1 on the obtained printed matter and the misalignment state of the position adjustment mark, the color misalignment alignment mark is a color misalignment adjustment mark in which each symbol corresponding to each of the above basic colors is separated from each other at an arbitrary interval. The symbols are arranged and displayed, and are provided at least one location on the document in directions orthogonal to each other, and the distance between the lines of each symbol on the document is scanned by an optical means, and the detected data is is stored in a storage means, the distance between the lines of each symbol displayed on the printed material printed by the plurality of plates is detected by scanning with the optical means, and this detection output and the storage in the storage means are A method for detecting color misregistration in offset printing, characterized in that a calculation means compares and calculates the output, and a display means detects and displays the error output for each color of both signals. (2) Claims in which symbols are formed by straight lines]1
The method for detecting color misregistration in offset printing as described in Section 1. (3) A color misregistration detection method in offset printing according to claim 1j [circle 1]/paragraph 1, wherein the symbols are colored in their corresponding basic colors.