JPH0584743B2 - - 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 calculated based on this detection power. 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.

In addition, do not perform register adjustment for each color at the same time.
When the output of the control circuit is switched and sequentially applied to the register adjustment motor to perform register adjustment for each color individually, the time required for correction further increases, and the above-mentioned problem becomes more pronounced.

[Means for solving problems]

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

That is, in the method of automatically performing registration adjustment described above, the amount of registration error between each color and each other color is determined for each color, and the total amount of registration error is determined for each color with the same color as the reference. , the reference color corresponding to the minimum value of each total registration error amount is used as the reference color, the corrected target value for each other color is determined according to this reference color, and the register is adjusted according to each corrected target value. It is assumed that this will be carried out.

[Effect]

Therefore, depending on the error occurrence distribution situation of each color,
The reference color with the lowest total correction amount for each color is automatically selected, and register adjustment is performed in the direction of focusing on this reference color, so that optimal correction is performed most quickly.

〔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 indicating a corrected target value.

The output signal of the OPC 29 is given to a digital-to-analog converter (hereinafter referred to as DAC) 32 via an interface (hereinafter referred to as I/F) 31, where it is converted into an analog signal and then sent to a drive circuit (hereinafter referred to as DRV) 33. The signal is converted into a motor drive signal by the selector (hereinafter referred to as SEL) 34 and selectively supplied to register adjustment motors M ₁ to M ₄ of each color plate cylinder, thereby register adjustment of each color is performed. .

On the other hand, the registered position of each color plate cylinder is detected individually by potentiometers (hereinafter referred to as PM) 41 ₁ to 41 ₄ provided for each color plate cylinder in correspondence with motors M ₁ to M ₄ ,
After sequentially and iteratively selecting each of these outputs in a multiplexer (hereinafter referred to as MPX) 42,
Analog-digital converter (hereinafter referred to as ADC) 4
3 as a digital signal, then I/F44
It is given to OPC29 via , and OPC29 is
The difference between the required correction amount and the current registered position detected by PM41 ₁ to 41 ₄ is determined as a correction target value, and the SEL 34 is controlled according to the color to be corrected, and the correction target value is sent. It's summery.

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 4th
The registration error distribution for color 4 is obtained as shown in FIG.

Note that OPC29 is a processor (hereinafter referred to as CPU).
The CPU executes instructions stored in the memory, and performs arithmetic processing while accessing the necessary data from the memory. Using color 1 as a reference, determine the absolute value of each of the misregister amounts E ₂ to _{E 4} with each of the other colors 2 to 4, and calculate the total amount of misregistration x ₁ as x ₁ = |E _{2 | ＋} | _{E 3} | ₊ | _{E 4 |}
…(2) x ₃ = |−E ₃ |+|E ₂ −E ₃ |+|E ₄ −E ₃ |
…(3) x ₄ = |−E ₄ |+|E ₂ −E ₄ |+|E ₃ −E ₄ |
...By each calculation in (4), calculate the absolute value of the amount of registration error between the first color, 1st to 4th colors, and each other color with 4 as the reference, and The total absolute value of the amount of registration error is determined, and a total amount of registration error x 1 with respect to the first color ₁ to a total amount of registration error x ₄ with reference to the fourth color 4 is determined for each individual.

Next, if we find the minimum of each total misregistration amount x ₁ to x ₄ , this will be the condition for minimizing the required correction amount overall, so we will find the minimum total misregistration amount and do the corresponding one. The reference color is set as the reference color.

Therefore, in the example shown in Figure 1, the third color 3 is the reference color, and if the correction target values for each color 1, 2, and 4 are calculated accordingly, the correction direction will be focused on the third color 3. As a result, the status of register adjustment corrections will be made quickly.

Figure 3 is a flowchart of the arithmetic processing status by the CPU in OPC29, and in the case of four-color printing,
For example, "error amount E ₁ ~ of each color based on the first color"
E ₄ is calculated and stored in memory'' 101, and based on these, ``calculate the total registration error amount of the first color standard'' 102 is performed using equation (1), and then (2) to (4) are performed.
By calculating the equations, steps 111 to 113 of ``determine the total amount of misregistration error of the second color reference'' to ``determine the total amount of misregistration error of the fourth color reference'' are performed.

Next, perform step 121 of "determine the minimum total registration error amount and use the reference color as the reference color", and use the error amount _E3 obtained in step 101 for this reference color Eir=Ei-Es...(5) (i = 1 to 4) "Find the correction error amount E ₁ r to E ₄ r" 1
22, and based on this, "correction target value calculation" 131 for each color is performed according to each output of PM41 ₁ to PM41 ₄ , and in "correction control" 132, the SEL 34 is controlled and the corrected target value is sent out. After performing this, steps 101 and subsequent steps are repeated via "RET".

Therefore, since the total amount of register adjustment corrections is minimized, the time required for correction is minimized, speeding up register adjustment is achieved, and the number of defective sheets generated during this period is significantly reduced.

However, instead of using the first color 1 as a reference, the amount of error with each color may be calculated using other colors as a reference.
The same effect can be obtained even if the amount of error based on each color is calculated for each individual color without using equations (2) to (4). Directional register adjustments can be made in a similar manner.

Also, in Figure 2, GAT23, CUT2
6 to LAT28 and MPX42 functions
It may be accommodated in the OPC 29 and realized by the CPU, or the OPC 29 may be configured by a combination of various logic circuits, and each motor M ₁
~If _M4 responds to digital signals, then
Various modifications are possible, such as omitting the DAC32 and selecting the DRV33 accordingly, as well as omitting the ADC43 when using a rotary encoder or the like that generates digital signals instead of _PM411 to _PM414 . It is.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, the amount of correction in register adjustment is minimized, register adjustment is not performed more than necessary, and the required time is shortened, so the amount of defective paper generated is significantly reduced. A remarkable effect can be obtained in register 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 4...1st color to 4th color, 21...LES (photoelectric sensor), 26...CUT (counter), 27...DEF (differential circuit), 28...LAT (latch circuit), 29...OPC
(arithmetic circuit), E ₁ to E ₄ ... Register error amount.

Claims (1)

[Claims] 1. In a method of detecting register marks for each of a plurality of colors and automatically adjusting registration between the colors based on the detection power, the amount of registration error between each color and each other color is determined individually. and find the sum of the absolute values of the above-mentioned misregistration amounts with respect to the same color as a reference for each individual, and use the reference color corresponding to the minimum value among the respective total misregistration errors as a reference color,
A corrected reference color setting method for automatic register adjustment, characterized in that a corrected target value for each other color is determined in accordance with the reference color, and the register adjustment is performed according to each corrected target value.