JPH07304162A - Register control device for offset rotary printing machine - Google Patents

Abstract

PURPOSE:To prevent the lowering of accuracy for register control even when the printing of a register mark bleeds. CONSTITUTION:A device comprises an encorder 6 for sensing the revolution of a plate cylinder 2, an image pickup device 7 for crossing perpendicularly a register mark, which is a right-angle equilateral triangle printed on a web 1 by plate cylinders 2-5 in the advancing direction of the web 1, scanning and sensing, and conforms the opposite side of right angle to the advancing direction of the web 1, a computation control section 8 for finding a center of gravity of the register mark from the output of the image pickup device 7 and the output of the encorder 6 and forming the deviation from a preset gravity center position and an adjusting section 9 for adjusting the deviation of plate cylinders based on the computed deviation. The center of gravity of the register mark is computed from the crossing length of first and last scanning lines crossing the register mark by the computation control section 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the registration of an offset rotary printing press by means of a register mark printed on a web, and more particularly to a register of an offset rotary printing press for accurately controlling the printing of a register mark. Regarding the control device.

[0002]

2. Description of the Related Art When printing a plurality of colors, register control is performed to prevent color misregistration. An offset rotary printing machine will be described as an example of the multicolor printing machine. FIG. 6 shows the basic configuration of an offset rotary printing press. The web 1 unwound from the supply roller is a black plate cylinder 2, a blue plate cylinder 3,
By sequentially passing through the printing unit including the red plate cylinder 4 and the yellow plate cylinder 5, black, blue, red, and yellow are printed, and a series of printing is completed. The perimeters of the plate cylinders 2, 3, 4, 5 in the printing unit are of the same size, and one printing is performed for each rotation of the plate cylinder, and the web 1 passing through the printing unit has the plate cylinder perimeter. The pattern of 1 unit is repeatedly printed.

When register control for preventing color misregistration by adjusting the rotation of these four plate cylinders, register marks as shown in FIG. The body prints. That is, the black register mark is performed by the black plate cylinder 2 that prints a black pattern, the blue register mark is the blue plate cylinder 3, and so on. To print.

In FIG. 7, (a) shows a case where the registration error is zero in a state where there is no print deviation of each color. The arrow indicates the traveling direction of the web 1. (B) shows the case where the blue register mark is shifted to the red side by dmm, and at this time, the blue pattern is also shifted to the red side by dmm. That is, the deviation of the pattern of each color can be measured by monitoring the relative position between the register marks.

Japanese Unexamined Patent Publication No. 63-22651 discloses a technique for scanning a fine register mark array having a right-angled diamond shape as a register mark to find a registration error between respective colors and to correct it. Further, Japanese Patent Laid-Open Publication No. 62-502601 discloses a technique for register control using the center of gravity of a mark, but does not describe the shape of the mark or how to obtain the center of gravity of the mark.

[0006]

There are many types of paper printed by the plate cylinder, but in the case of newsprint, ink easily bleeds. In the case of a triangle, the size of the register mark is about 2 mm even on the long side, so that the size changes when the ink bleeds. In the case of the right-angled isosceles triangle register mark shown in FIG. 8, the length a in the web traveling direction is obtained from the length a intersecting the scan line S. When the blur becomes a1, the shift between the register marks is based on this a1. Since it is calculated, there is a problem that the correct shift cannot be obtained and accurate register control cannot be performed.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a register control device for an offset rotary printing press, in which the accuracy is small even if the register mark is deformed. Another object of the present invention is to provide a register mark having a shape and an arrangement that facilitates calculation of the center of gravity.

[0008]

In order to achieve the above object, in register control of an offset rotary printing press that performs rough printing with a plurality of plate cylinders, an encoder that detects the rotation of the plate cylinders and each of the plate cylinders are used. A linear sensor that is a right-angled isosceles triangle printed on a web, and a register mark in which opposite sides of the right angle are aligned with the traveling direction of the web is scanned and detected orthogonal to the traveling direction of the web. An arithmetic control unit that calculates the center of gravity of the register mark from the output of the encoder and calculates the displacement between the center of gravity position set in advance and the center of gravity obtained from the detected value, and the displacement of the plurality of plate cylinders by the output of this arithmetic control unit The arithmetic control unit calculates the center of gravity of the register mark from the intersection length of the first and last scan lines that intersect the register mark. Those were Unishi.

[0009]

Operation: The register mark is an isosceles right triangle, and the opposite side of the right angle coincides with the traveling direction of the web, and the intersection length of the first and last scan lines intersecting the register mark and the length between the first and last scan lines are defined. The positions of both ends of the right-angled opposite sides of the right-angled isosceles triangle can be found from, and the center-of-gravity position can be calculated from the fact that the center-of-gravity exists at the center position of the both ends and the property of the right-sided isosceles triangle. The length between the scan lines is obtained by obtaining the peripheral speed of the plate cylinder from the rotation angle of the encoder per unit time and the radius of the plate cylinder, and multiplying this peripheral speed by the scan cycle. In addition,
The first and last intersecting scan lines intersect each other with the right-angled opposite sides of the right-angled isosceles triangle with the center of gravity in between, and the first intersection length gives the position of one end of the right-angled opposite sides. The other end position is obtained from the intersection length. Even if the register mark is bleed and the register mark becomes thick, the center of gravity position hardly changes. Therefore, correct the deviation between the predetermined position of the register mark center of gravity (the position where no deviation occurs) and the center of gravity obtained from the detected position. The calculation can be performed, and the adjustment for reducing the deviation can be correctly performed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. Printing on the web 1 is performed by the plate cylinders 2 to 5 that print black, blue, red and yellow. An encoder 6 that rotates in a one-to-one relationship with the reference printing plate cylinder 2 is provided.
The number of revolutions and the rotational position of are output in pulses. Encoder 6
Has, for example, an A phase that generates 1000 pulses per revolution of the plate cylinder, a B phase, and a Z phase that generates 1 pulse per revolution. Phase B is 90 degrees shifted from Phase A,
Used to detect the direction of rotation of the encoder. The image pickup device 7 scans the web 1 in the direction perpendicular to the direction of travel of the web to take an image of the register mark. The image pickup device 7 uses a one-dimensional CCD sensor as a linear sensor. The register mark is formed on the CCD sensor by the objective lens of the image pickup device 7, converted into an electric signal, and output as image data. The operation control unit 8 analyzes the image data of the input register mark and calculates the center of gravity thereof, and for each register mark, the theoretical position of the other register mark center of gravity with respect to the reference mark center of gravity of the black plate cylinder serving as the reference (reference The position of the center of gravity of the register mark that does not cause displacement with respect to the center of gravity of the register mark of the plate cylinder is obtained in advance, and the displacement of the position from this theoretical position is calculated. The adjusting unit 9 controls the blue, red, and yellow plate cylinders 3 to 5 so that the calculated deviation is reduced.

FIG. 2 is a diagram showing the output of each cell of the one-dimensional CCD sensor when the image pickup device 7 scans the register mark 10. The arrow indicates the traveling direction of the web 1, and L indicates the scanning range (field of view). There are N cells (bits) in the one-dimensional CCD sensor, and the register mark 10 is set at the m-th bit.
Is detected, the output rises, and the register mark 10 is removed at the n-th bit, so the output falls. Since the length per bit is represented by L / N, the length a of the scan line S intersecting the register mark 10 is (n−m) · L /
Represented by N.

FIG. 3 shows a register mark 1 used in this embodiment.
It is a figure which shows the shape and arrangement | positioning of 0. (A) shows the shape of the register mark 10. The sides of the right-angled isosceles triangle that face the right angles are arranged in the direction of web travel. (B) is black, blue,
The arrangement of the register mark 10 printed on the web 1 by each of the red and yellow plate cylinders 2 to 5 is shown.

FIG. 4 is a diagram for explaining a method of obtaining the center of gravity of the register mark 10. The scanning cycle is calculated with respect to the speed of the web 1 and the length of the opposite side of the register mark 10 at right angles so that one register mark 10 is scanned at least twice when the register mark 10 passes through the imaging range of the imaging device 7. It is adjusted by the control unit 8. In this embodiment, the scan cycle is constant and 30 microseconds / 1 scan. However, if the speed of the web 1 is low as it is, the length of the web 1 passing during one scan is short and the number of scans on the register mark becomes too large. Therefore, the number of scans on the register mark is made almost constant. , The sample period is changed according to the speed of the web 1. In other words, when the web 1 is at high speed, all scan data is sampled, and as the speed becomes slower, the sampling period is increased from once every 2 scans to once every 3 scans, and at most 2
Sampling is performed once every 55 scans. Web 1
The number of pulses per unit time of the encoder 6 is counted, and the number of pulses per one revolution of the plate cylinder (1 in this embodiment).
(000 pulses), the rotation angle of the plate cylinder 2 is calculated, the peripheral speed is calculated from this rotation angle and the radius of the plate cylinder 2, and the same peripheral speed can be calculated.

All image data of scan lines sampled according to the speed of the web 1 are taken in. As described in FIG. 2, the image data rises at the position m where the intersection with the register mark 10 starts and falls at the position n where the intersection ends. Since the image pickup device 7 is fixed, and the movement of the web 1 in the lateral direction (direction perpendicular to the traveling direction) can be ignored for a short time, the number of m which starts the intersection with the register mark 10 from the scan start position for each scan. The length up to the position is almost constant, and the position of n at which the intersection ends is moved to the right stepwise when sequentially scanned from top to bottom,
On the contrary, it gradually moves to the left. This change occurs in the scan lines sampled continuously, so that the register mark 1
It is possible to identify the shape of 0. Of the scan lines used for this identification, the first and last two are selected and used for calculating the center of gravity.

FIG. 4 shows a case where two scan lines S1 and S2 which intersect first and last intersect with the register mark 10. When two or more lines intersect, they shall intersect between S1 and S2. The number of scan lines that intersect is 2
Even in the case of a book, since the scan lines are evenly spaced, they intersect each other with the center of gravity G of the register mark 10 in between. The vertices of the register mark 10 are represented by A, B, and C as shown in the figure, and the side A
Let the length of B be x. The length between the scan lines S1 and S2 is s. s is the interval between the sampled scan lines, and is calculated from the sampling period and the speed of the web 1. When there is a scan line between S1 and S2, the value of s is k, which is the number of scan line intervals.
Is multiplied by the scan line interval s to be ks. a and b can be obtained by the method described in FIG. 2, and the length x of the side AB can be obtained by using the value of s described above. Since the register mark 10 is an isosceles right triangle, the line segment CD connecting the midpoints D and C of AB is x / 2, and the center of gravity G is the position where CG and GD are 2: 1 on the line segment CD. Exists in. Therefore, the coordinates of point A are (X1, Y
1), assuming that the coordinates of point B are (X2, Y2), the coordinates of the center of gravity G are expressed as follows.

X-coordinate of the center of gravity G: (X1 + X2) / 2 Y-coordinate of the center of gravity G: (Y1 + Y2) / 2 + 1/3 · (X1
-X2) / 2 Note that the coordinate axis is X in the traveling direction of the web as shown in the figure.
Take the Y axis in the direction perpendicular to the axis. The X coordinate of the point A is represented by the position of the scan line S1 and the value of a. If the traveling speed of the web 1 is V and the X coordinate of S1 when the scan line S1 intersects the register mark 10 is 0, the X coordinate of the point A after t time is represented by Vt + a. Also A
Since the Y coordinate of the point does not change with time, the position of cell 1 shown in FIG. 2 may be used as the origin of the coordinate. The X coordinate of the point B can be represented by Vt- (s + b). In this way, the center of gravity G can be displayed in X and Y coordinates.

FIG. 5 shows black, blue, red and yellow register marks 1
It is the figure which represented the gravity center G1-G4 of 0 by the X, Y coordinate. Theoretical blue, red, and yellow register marks 1 with no deviation from the center of gravity G1 of the black register mark 10
The center of gravity G20, G30, G40 of 0 is obtained, and the difference G20-G from the center of gravity G3, G3, G4 calculated from the image data is obtained.
2, G30-G3, G40-G4
The deviations of the register mark blue, red, and yellow with respect to the register mark black and the direction in which the web advances and the direction perpendicular thereto can be obtained.

[0018]

As is apparent from the above description, according to the present invention, a register mark of an isosceles right triangle is printed with the opposite side of the right angle being the web advancing direction, and the center of gravity of the register mark is intersected with at least two scan lines. The register center is calculated and the shift of the center of gravity of other register marks is calculated for register control, so even if the shape of the register mark changes due to bleeding, the center of gravity does not change much. Stable register control can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is an explanatory diagram for obtaining an intersection length of a register mark that intersects a scan line.

FIG. 3 is a diagram showing the shape and arrangement of register marks according to the embodiment.

FIG. 4 is a diagram illustrating a method of calculating the center of gravity of a register mark.

FIG. 5 is an explanatory diagram for calculating a shift of the center of gravity of another register mark with respect to a reference register mark.

FIG. 6 is a diagram illustrating a configuration of a fold impression plate cylinder unit.

FIG. 7 is an explanatory diagram for detecting a shift of the plate cylinder due to a register mark.

FIG. 8 is an explanatory diagram of a register mark deformed by bleeding.

[Explanation of symbols]

 1 Web 2-5 Plate cylinder 6 Encoder 7 Imaging device 8 Arithmetic control unit 9 Adjustment unit 10 Register mark

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Iwama 2951 Ishikawa-cho, Hachioji-shi, Tokyo 4 Nireko Co., Ltd. (72) Inventor Takeo Yamada 2951 Ishikawa-cho, Hachioji-shi, Tokyo 4 Nireko Co., Ltd.

Claims (1)

[Claims] 1. In register control of an offset rotary printing press for performing a rough impression by a plurality of plate cylinders, an encoder for detecting the rotation of the plate cylinders, and an isosceles right triangle printed on a web by each of the plate cylinders, A register mark in which opposite sides of a right angle are aligned with the traveling direction of the web, a linear sensor for scanning and detecting orthogonal to the traveling direction of the web, and the center of gravity of the register mark is obtained from the output of the linear sensor and the output of the encoder, An arithmetic control unit for calculating a deviation between a center of gravity position set in advance and a position of the center of gravity obtained from a detected value, and an adjusting unit for adjusting the deviation of the plurality of plate cylinders by the output of the arithmetic control unit are provided. The offset printing press is characterized by calculating the center of gravity of the register mark from the intersection length of the first and last scan lines that intersect the register mark. This control device.