JPS60145852A - Inspection apparatus of printed matter - Google Patents

Abstract

PURPOSE:To make highly precice, highly effective inspection of printed matter possible, by correcting detection density signal according to the speed of print. CONSTITUTION:Printing pattern is transferred onto a printing paper 4 with a plate cylinder 1, rubber blanket cylinder 2, and an impression cylinder 3 and the printing pattern is continuously reflected with a line state camera 5. Then, detection density signal is supplied to a signal treatment equipment 6, compared with the reference value of built-in memory and the quality of the printed pattern is inspected. This equipment 6 is supplied with the speed information of printing paper 4 via the rotary encoder 7 of rubber blanket cylinder 2, the density detection signal change to the change of exposure by speed being corrected and the inspection of printed matter can be highly precisely and highly effectively carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printed matter inspection device that automatically inspects printed matter for deprinting of marks and turns of patterns, characters, etc., and for various stains, scratches, etc. that occur on printed matter.

Normally, printed matter is inspected by a printing press operator who takes out the printed matter at appropriate intervals and visually inspects it. However, such an inspection is time-consuming, the detection is delayed, and by the time the defect is noticed, a countless number of defective prints have already been printed, resulting in a poor printing yield υ. Additionally, this requires an operator to constantly monitor the printing press, so in a factory where several printing presses are in operation, a number of operators equal to the number of printing presses is required.

Various automatic inspection devices for printed matter have been developed with the aim of solving this drawback and improving the yield of printed matter and saving labor.
Currently, there is no method that is necessarily satisfactory in terms of inspection accuracy.

These automatic inspection devices utilize optical techniques, and the principle thereof will be explained with reference to FIG.

1 is a plate cylinder, 2 is a blanket cylinder, and 3 is an impression cylinder. When the printing press 4 passes between the blanket cylinder and the impression cylinder, the printed pattern of the plate cylinder 1 is transferred onto printing paper. Reference numeral 5 denotes a line-shaped camera that scans the printed surface of the printed matter in a line (indicated by line A-11 in the figure) immediately after passing through the blanket cylinder, and continuously detects the optical density of the printed pattern on the line as an electrical signal. shows. 6 is
The video signal output from this line-shaped camera is received and compared with the normal print pattern stored in the memory mechanism included in the line camera, and the difference is used to detect printing defects such as dirt, scratches, white spots, etc. that occur on the printing paper. This is a signal processing device that has the function of detecting defects such as defects and outputting a signal to inform the operator of the defect, or, if the cause of the defect is known, outputting an operation signal to eliminate the cause of the defect. The key point of the printed matter quality defect inspection apparatus using the optical method described above is to correctly compare the detected shading signal with the shading signal of a normal printed pattern.

Conventionally, the detection limit size of the defect to be inspected has been relatively large, such as ink stains of a few centimeters or more, and the inspection speed has been relatively slow. However, as printing becomes more sophisticated and faster in recent years, the requirements for inspection tend to become more and more sophisticated.

That is, the situation has come to such a point that an inspection apparatus capable of supporting an inspection limit dimension of 1111I11 or less and an inspection speed of 5 m/s or more is desired. In such a situation, the normal grayscale signal (hereinafter referred to as the reference pattern) is compared with the detected grayscale signal,
When detecting printing defects that occur in printed matter based on the difference, the comparison signal density level between the two is highlighted as an important issue.

That is, in the conventional apparatus, as a means to obtain synchronization between the patterns of the reference printed matter and the detected printed matter, a rotation angle detector such as a rotary encoder is attached to the plate cylinder or the impression cylinder, and the leading edge of the printed pattern or the A pattern shading detection scanning signal is obtained for each inspection dimension. This is possible because the position of the plate cylinder or impression cylinder and the printed pattern correspond correctly. If the reference pattern signal and inspection pattern signal are detected in synchronization with the pattern of the printed matter using the method described above, synchronization between the two can basically be secured, but as mentioned above, if the impression cylinder or plate cylinder is Install an encoder, etc., and set its rotation angle (e.g. 360°/) 000 pitch 4
If the camera scans are synchronized using J5), synchronization can be ensured in principle without depending on the printing speed, but the time from one scan to the next varies due to fluctuations in the speed of the printing press, so the camera scan Departure times will vary. This has the disadvantage that the level of the detection signal obtained fluctuates and cannot be handled by simple comparison processing in printing defect determination.

The present invention was proposed in view of the above circumstances.
The purpose is to provide a printed matter inspection device that can operate with high accuracy and efficiency by correcting the detected density signal level in response to print speed fluctuations.

The printed matter inspection device according to the present invention optically combines the printed pattern of the printed matter onto a light receiving element, and detects the density of the printed matter by extracting the intensity of light incident on each light receiving element at that time as an electric quantity. In a printed matter inspection device that detects quality defects that occur in printed matter based on differences with a reference grayscale image, there is a device that detects and stores the printing speed when obtaining the reference grayscale image signal using a speed detector, and a device that detects and stores the printing speed at the time of inspection. is detected by the speed detector, and a divider that divides the detected value by the pre-stored printing speed, and a divider that multiplies the division result by the print density signal at the time of inspection or the reference density signal. and a multiplier to correct variations in the density signal of the printed matter caused by variations in printing speed during inspection, detecting variations in printing speed, and detecting the variations in response to the variations. By correcting the gray level signal level, it is possible to inspect printed matter with high precision and efficiency.

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of the signal processing device in FIG. 2.

In Figures 2 and 3, 1 is a plate cylinder, 2 is a blanket cylinder,
3 is an impression cylinder, 4 is a printing paper, 5 is a line camera, 6 is a signal processing device, 7 is a speed detection sensor, 61.65 is each ψ converter, 62 is a speed detector, 63, 64, 611 are each A memory, 66° and 67 are switches, 69 is a multiplier, 70 is a divider, 71 is a comparison circuit, and 72 is a determination circuit.

The operation of the above embodiment of the present invention will be explained.

In FIG. 2, the speed detection sensor 7 is, for example, a pulse generator attached to the blanket cylinder 2, and this pulse generator is proportional to the rotational speed of the blanket cylinder 2. This signal is sent to the signal processing device 6.
The print speed signal is obtained internally. Although the embodiment shown in FIG. 2 is an example in which the flux generator is attached to the blanket cylinder 2, it is of course possible to attach it to the plate cylinder 1 or the impression cylinder 3 as well. Further, it is not particularly necessary to use a pulse generator, and other speed detectors may be used. Figure 3 is the second
The figure shows the configuration of the signal processing device 6, in which a signal from a line camera 25 for detecting a pattern signal of a printed matter is input to an A7'D converter 61 and converted into a digital value.

This converted digital pattern signal is stored in the reference value memory 64 by the switch 66 if it is a reference pattern. If it is a detection signal, the switch 66
The data is stored in the failure detection memory 63 as a guarantee. It is called from this detection memory 63 at any time, and at the same time, the reference value memory 64
The reference value at the corresponding position in the picture is also called up, and both are input to the comparison circuit 71 in synchronization. The comparison circuit 7 basically calculates the difference between the two, and the output value is input to the judgment circuit 72, where the magnitude of the difference is evaluated. For example, if it exceeds a certain value, it is judged as a defective signal. and is output internally and externally. 62 is a speed detector for receiving signals from the pulse generator, etc., and obtaining a printing speed signal, and 65 is an lV for digitizing the speed range signal.
It is a D converter. Similarly to the above, when the measurement mode is to set the reference pattern, the speed signal digitized by the switch 67 is stored in the reference speed memory 68.When the measurement mode is inspection, the value is stored in the reference speed memory 68. 67, the value is directly input to the divider 7o.The divider 70 is also input with the value of the previously set reference speed memory 68, and division of the two is performed here. If the speed at the time of measurement is vo and the speed at the time of inspection is V, the value of v/■o is calculated.This value is stored in the detection memory 63.
and a comparison circuit 71. A multiplier 69 multiplies each detection value corresponding to a print pattern extracted from the detection memory by v/v0, and inputs the result to a comparison circuit 71. Comparison circuit 71 and determination circuit 7
The effect of No. 2 is the same as described above. Since camera detection signal fluctuations caused by fluctuations in printing speed are basically inversely proportional to the printing speed, the correction method described above, namely V/V,
By multiplying the values, detection signal fluctuations can be correctly removed.

According to the present invention, even if the printing speed when the reference pattern signal is acquired is different from the printing speed at the time of actual inspection, it is possible to correctly match the pattern using the printing speed correction device. This provides excellent effects such as making it possible to perform quality inspections with higher accuracy and efficiency.

Note that in the above embodiment, the detected value is V/V.

I made the correction, but of course the standard picture value in the standard memory was V. The effect is the same even with the correction method of multiplying the value of /V.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a conventional example, FIG. 2 is a schematic diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of the signal processing device in FIG. 2. 6... Signal processing device, 7... Speed detection sensor, 62
...speed detector, 63,64.68...memory, 6
9... Multiplier, 7Q... Divider, 7... Comparison circuit, 72... Judgment circuit. Applicant Sub-Agent Takehiko Suzue, Patent Attorney Figure 1 j I 3, page 1 continued [Phase] Inventor Shima 1) Jin Akira, Hiroshima Research Institute, 4-cho Kannon-Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Shigeru Itaya Hiroshima Hiroshima Research Institute, 4-chome, Kannon-Shinmachi, Nishi-ku, Tokyo 0 Inventors: 1) Toshiro 1, Taito, Taito-ku, Tokyo
Chome 6-2, Mitsubishi Heavy Industries, Ltd., 5-1, Toppan Printing Co., Ltd.

Claims (1)

[Claims] The printed pattern of the printed material is optically coupled onto the light receiving element, and the intensity of the light incident on each light receiving element at that time is extracted as an amount of electricity. In a printed matter inspection device that detects quality defects that occur in printed matter based on the difference between a divider that detects the paper and divides the detected value by the pre-stored printing speed, and a multiplier that multiplies the division result by a print density signal or a reference density signal at the time of inspection. 1. A printed matter inspection apparatus, comprising: a printed matter inspection apparatus, wherein the printed matter is corrected for variations in shading (I) of the printed matter due to printing speed fluctuations during inspection.