JPH0584744B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for setting a corrected reference color when automatically adjusting registration errors between colors in a multicolor printing press.

[Conventional technology]

In multicolor printing machines such as rotary presses, the register between each color changes depending on the printing materials such as printing paper, blanket, and ink, as well as changes in printing conditions such as tension applied to the paper and ink tack.
For the purpose of automatically detecting this and correcting the registration error between each color, Japanese Patent Laid-Open No. 58
The method disclosed in No. 14751 is becoming increasingly popular.

[Problem that the invention seeks to solve]

However, conventionally, register marks printed for each color are detected, and the registration error between each color is determined based on this detection power, but when determining the registration error, the reference color is Alternatively, a staff member selects a specific color from among each color, and the printing status of the register mark with this fixed color is used as the standard, and the amount of registration error between each color is generally reduced. When viewed, this fixedly set color is not the center of the error occurrence distribution situation, and there are cases where more corrections are made than necessary, and control using motor drive is used for register adjustment. Therefore, it takes a long time to make corrections, and each time more corrections are made than necessary, a large amount of defective paper such as duplicate printing is generated, resulting in an uneconomical problem.

[Means for solving problems]

In order to solve the above-mentioned problem, the present invention is constructed by the following means.

In other words, in the above-mentioned method of automatically performing registration adjustment, the amount of registration error between each color with respect to each other color is determined based on a specific color among each color, and the maximum error amount in the positive direction is calculated from among these amounts of error. Find the maximum error amount in the positive direction and the maximum error amount in the negative direction, set the midpoint between this maximum error amount in the positive direction and the maximum error amount in the negative direction as a virtual reference point, find the color closest to this and use it as the reference color, and use the other colors according to this reference color. A corrected target value is determined for each color, and the register is adjusted according to each corrected target value.

[Effect]

Therefore, depending on the error occurrence distribution situation of each color,
The color closest to the center of the error distribution range is set as the reference color, and the corrected target value for each color is determined based on this, and register adjustment is performed according to each corrected target value. No corrections will be made, and prompt corrections will be made.

〔Example〕

Hereinafter, details of the present invention will be explained with reference to figures showing examples.

Figure 2 is a block diagram of an electric circuit for determining the corrected target value, and shows a photoelectric sensor (hereinafter referred to as
LES) 21 output to a waveform shaping circuit (hereinafter referred to as WFC)
22 generates a square wave and supplies it to a gate circuit (hereinafter referred to as GAT) 23, while a gate pulse from a gate pulse generation circuit (hereinafter referred to as GPG) 24 generated based on the operation of the printing press generates a square wave.
23, and also resets a counter (hereinafter referred to as CUT) 26 that counts clock pulses from a clock pulse generator (hereinafter referred to as CLG) 25, and the GPG 24 determines the detection reference point for each color and the corresponding detection start time. In order to generate gate pulses from and continue to generate gate pulses until register mark detection is completed for each color,
The detection force of each register mark by the LES 21 passes through the GAT 23 for each color, and the differential circuit (hereinafter referred to as
DEF) given to 27.

Then, the DEF 27 sends out a differential pulse corresponding to the leading edge or trailing edge of the register mark for each color.
In order to supply the latch circuit (hereinafter referred to as LAT) 28 and thereby hold the count value of CUT 26,
The count value of the CUT 26, which is reset at the same time as the gate pulse generation of the GPG 24 starts and restarts counting the clock pulses given from the CLG 25, is held by the LAT 28, and this value indicates the distance between the detection reference point and the register mark for each color.

Note that the GPG24 sends out a clear pulse for each color just before the start of detection of each register mark to clear the LAT28.
8, the distance between the detection reference point and the register mark for the first color is maintained, then the same distance for the second color is maintained, and thereafter similar distances for the third and subsequent colors are maintained sequentially. is the arithmetic circuit (hereinafter,
OPC) 29 will be given sequentially, and OPC
29 performs calculations to be described later and sends out an output signal S _D indicating the corrected target value.

Figure 1 is a diagram of the situation in which corrected reference colors are set as a prerequisite for obtaining corrected target values.The distance between the detection reference point for each color and the register mark is the specified distance if the registration error is zero. , the deviation of the measured distance from this specified distance determines the first color. 1st to 7th
The registration error distribution for color 7 is obtained as shown in Figure 1.

Note that OPC29 is a processor (hereinafter referred to as CPU).
The CPU executes the instructions stored in the memory, and performs arithmetic processing while accessing the necessary data from the memory. In Figure 1, the specific color is Using the first color 1, the amount of registration error between each other color 2 to 7 using the first color 1 as a reference E ₂ to _{E 7}
is determined for each individual, and from these, the maximum error amount in the positive direction is
E _nax1 and the maximum negative error amount E _nax2 as E ₅ and E _{6
After calculating E _ _ _}
The color closest to this color is set as the reference color.

Therefore, in the example of FIG. 1, the seventh color 7 is the reference color, and if the correction target values for each color 1 to 6 are determined accordingly, the correction direction will be focused on the seventh color 7, The status of register adjustment corrections will be made promptly.

Figure 3 is a flowchart of the calculation processing status by the CPU in OPC29, and in the case of double-sided printing,
For example, "error amount of each color based on the first color on the top surface"
Find E ₁ ~ En and perform memory storage 101,
``Determine the maximum error amount E <sub>nax1</sub> in the positive direction'' from E <sub>1</sub> to En, and similarly ``Determine the maximum error amount E nax1 in the negative direction'' 102
After performing ``Calculate E <sub>nax2</sub> '' 103, perform ``Calculate E _F '' 111 by calculating equation (1), and then ``Find the error between E _F and each color'' 112 of the virtual reference point obtained thereby. Then, calculate E _ic = E _i −E _F ...(2) (i=1 to n), and "set the color with the minimum error as the reference color" from among these error amounts E _1c to E _oc . Do 113.

Next, the amount of error obtained using equation (2) for the reference color
``Find the corrected error amount E _1r ~ E _or' ' by calculating E _ir = Eic - Esc ... (3) (i = 1 ~ n) using E _sc 1
21 is performed, and based on this, "corrected target value calculation" 122 is performed for each color, and after "corrected target value sending" 123 is performed, steps 101 and subsequent steps are repeated via "RET".

Note that the corrected target value is determined according to the current plate cylinder register position for each color, and this corrected target value is sent out as an output signal S _D for each color and given to the register adjustment motor of each color plate cylinder. 7th color/7 in Figure 1
The registration of each color is adjusted in the direction of convergence.

Therefore, the amount of correction for register adjustment is maximum for the fifth color, 5, and the sixth color, 6, but the seventh color is fixed, and the amount of correction decreases overall, so for the first color,
The maximum correction amount is reduced compared to when using 1 as the standard,
Registration adjustment is made faster, and the number of defective sheets generated during this process is greatly reduced.

However, instead of using the first color 1 as a specific color, the amount of error with each color may be calculated using other colors as a reference.If the detection area by LES21 is selected according to the shape of the register mark, the error in the vertical direction can be determined. In addition to this, register adjustment in the left and right directions can also be performed in the same way.

Also, in Figure 2, GAT23, CUT2
6 to LAT28 functions are accommodated in OPC29,
It may be realized by a CPU, or OPC2
Various modifications are possible, such as configuring 9 by a combination of various logic circuits.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, the amount of correction for register adjustment is generally reduced, register adjustment is not performed more than necessary, and the time required is shortened, so the amount of defective paper generated is significantly reduced. This has a significant effect on registration adjustment used in various multicolor printing machines.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention; FIG. 1 is a diagram of a situation in which a modified reference color is set, FIG. 2 is a block diagram of an electric circuit, and FIG. 3 is a flowchart of arithmetic processing. 1 to 7...1st color to 7th color, 21...LES (photoelectric sensor), 26...CUT (counter), 27...DEF (differential circuit), 28...LAT (latch circuit), 29...OPC
(Arithmetic circuit), E ₁ to _{E 7} ... Register error amount, E _F ... Virtual reference point.

Claims (1)

[Claims] 1. In a method of detecting register marks for each of a plurality of colors and automatically adjusting the register between the colors based on the detection power, Determine the amount of error for each individual, and determine the maximum positive error amount and the maximum negative error amount from each error amount, and set the midpoint between the maximum positive error amount and the maximum negative error amount as a virtual reference point, The automatic method is characterized in that the color closest to the virtual reference point is determined and used as the reference color, the corrected target value for each of the other colors is determined according to the reference color, and the register adjustment is performed according to each of the corrected target values. How to set the correction reference color for register adjustment.