JPH0324899B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a printed matter inspection device for in-line comparing the condition of a printed matter being printed with a standard state in a printing press to detect abnormalities in the printed matter.

(Technical Background of the Invention and Problems thereof) Conventionally, printed matter has been mainly inspected off-line by relying on human vision. This stems from the fact that each piece of printed matter has a different pattern, and because inspection items for printed matter have been thought to involve subtle differences that require reliance on human vision. On the other hand, in response to the desire to evaluate printed matter while it is being printed, attempts have been made to use strobe lighting that is synchronized with the printing speed and to use mirrors that rotate synchronously at high speed to judge printed matter that is being printed as a still image. It was conducted. However, these methods were not systems that could be called inspection machines in that they relied on human vision for inspection. In addition, attempts have been made to print color patches at the same time as the patterns on the printed matter and inspect the color patches, thereby allowing the inspection of the printed matter to be performed on behalf of the user. However, with this method, if printing defects (oil drips, stains, etc.) occur in the pattern area, they will be overlooked, and the inspection machine cannot be said to perform its function satisfactorily.

On the other hand, a system has recently been proposed that inspects printed matter in-line using a line sensor, as seen in the "Printed Material Inspection Apparatus" disclosed in Japanese Patent Application No. 57-220515. By using this method, the pattern itself of the printed matter can be automatically inspected in-line, so it does not have the above-mentioned drawbacks and can be expected to have excellent effects as an inspection machine. However, this system is not without its problems; for example, after the inspection starts, the inspection machine detects small defects (hits,
Even if the operator determines that the defect is within an acceptable range due to stains, etc., the system of the above-mentioned invention will display the defect, alarm, mark, and reject, and unless the printing operator removes the defect, the system will continue to print. There is a problem in that the display etc. continues, and in this state, printing work is hindered.

In other words, whether small scratches or slight stains are acceptable or not is determined by the design of the print.For example, even a small defect can be a major defect at important points such as the appearance of a face or a product. However, there are cases in which small defects are considered to be within an acceptable range. As a result,
If you set strict tolerances to the inspection standards of the inspection machine so that small defects can be found at important points, even allowable errors in the printing process will be judged as defects, causing the printing process to stall. It turns out.

Here, it is conceivable to set various tolerance ranges in advance depending on the content of the image, but the setting method would be complicated, and in the end, it would be up to human judgment to decide whether or not the detected defect is acceptable. Other methods are also desired from the standpoint of necessity.

(Object of the Invention) The present invention was made to solve the above problems, and by using the present invention, it is possible to eliminate small defects found by an inspection machine that can be ignored in reality. It becomes possible to continue printing work and inspection.

(Detailed description of the invention) The present invention will be explained below.

FIG. 1 is a model diagram showing the configuration of one embodiment of the printed matter inspection apparatus of the present invention. In the embodiment shown in FIG. 1, the inspection device is attached to a rotary printing press, but there is no problem even if the inspection device is attached to a sheet-fed printing press.

In FIG. 1, a printing paper 3 supplied from a roll-shaped paper roll 2 is printed in four colors (yellow, red, black, and black) on the front and back sides in a printing section 1, and then,
The paper is transported to a dryer and a folding machine (not shown). The printed matter inspection device uses a rotary encoder 5 provided in the printing unit 1 to determine sampling timing for inspection, and detects pattern information of the pattern on the printing paper 3 by a detection unit 4 extending in a direction perpendicular to the printing paper conveyance direction. A line sensor such as a CCD scans the line one by one and inputs it into the processing circuit 6, where it is compared with a reference signal previously input for normal printing, etc.
If a preset allowable range is exceeded, an abnormality is displayed on the display 7. Furthermore, as countermeasures when an abnormality is detected, measures such as alarms, markings, and resets may be considered.

In the present invention, the operator visually determines the printed matter with the abnormality displayed on the display 7, etc., and if it is determined that it is out of the allowable range, the printing press is immediately stopped and the cause of the abnormality is stopped as in the conventional method. As soon as the dust is removed, the blanket washer and dust removal device are activated while the printing press is running to restore normal printing conditions and restart the inspection.

In addition, if the operator determines that the defect in the printed matter that is displayed as abnormal is within the allowable range, he or she can press a key on the control panel (not shown) that means ``Ignore the abnormality'' to start the printing machine. It becomes possible to continue the test as well as to continue the test.

In this state, defects that the above-mentioned operator has judged to be within the acceptable range are not displayed on the display, and no countermeasures such as alarms, markings, or resets are taken, and the printing continues as if it were normal printing. The print inspection device is activated. However, if a new defect that exceeds the allowable range occurs in the print, the print inspection device displays the defect on the display or takes other measures, leaving the final decision to the operator.

By repeating the above operations, the operator will be able to operate the printing press efficiently and will be able to discover all possible defects.

FIG. 2 shows a block diagram of one embodiment of the processing circuit of the print inspection apparatus according to the present invention.

The present invention is not limited to the processing circuit shown in FIG. 4, and any other circuit configuration may be used as long as the same effect is achieved.

As already mentioned, the detection unit 4 using a CCD line sensor or the like reads the information of the picture printed on the printing paper in a line perpendicular to the direction of travel of the printing paper. At this time, the sampling is a sampling pulse calculated by the sampling control circuit 13 based on the timing pulse TP generated by the rotary encoder 5 provided in the printing section.
This will be done in accordance with SP.

Since the input image signal IS is an analog signal, it is converted into a digital signal via the A/D converter 8. Here, when the printing operator presses an instruction button from the operation stand to set the current printed matter as a reference, the digitized image signal is stored in the reference memory 9, and from now on,
It is repeatedly used as a reference signal when testing is started. When the inspection starts, the image signal is A/D
The signal is directly transferred from the converter 8 to the differential circuit 10. At this time, the memory control circuit 12 specifies the address of the reference memory 9, reads out the reference signal, and simultaneously transfers the inspection signal and the reference signal of the pixel at the same position of the picture to the difference circuit 10. 10 outputs a difference signal DS meaning (test signal-reference signal).
This difference signal DS is compared with a predetermined tolerance value in a comparison circuit 11, and if the difference signal DS is larger than the tolerance value, an abnormality occurrence signal ES is transferred from the comparison circuit 11 to the CPU 14. According to the present invention, comparison methods other than the difference method can also be used; for example, the quadratic difference method detailed in "Inspection method for printed matter" in Japanese Patent Application No. 172,778/1982 can be applied. can also be done, but further explanation will be omitted here.

Next, the display on the display will be explained with reference to the flowchart shown in FIG. When the abnormality occurrence signal ES is transferred to the CPU 14, the CPU 14 sends data meaning "display not required" to the address corresponding to the position of the abnormality occurrence point in the abnormality occurrence ignore mask memory 15 for the mask corresponding to the address in the reference memory 9. Write. For example, if the error occurrence ignore mask memory 15 has a capacity of 1 bit per pixel, "Display = 0" and "Do not display =
In this case, the data at the address corresponding to the location of the abnormality location will be "1".

Next, the CPU 14 displays the occurrence of an abnormality on the display 7. The method of displaying this is
219059", ``Image Defect Portion Monitoring Device,'' and will not be described in detail here. In addition, in the event of an abnormality, measures other than displaying on the display,
For example, marking, alarm,
Reject etc. may also be implemented.

When an abnormality is displayed, the operator visually determines the printed material in which the abnormality has occurred, and if the worker determines that the printed material is unacceptable, the operator stops the printing press and removes the cause of the printing fault. do. again,
When the printing press starts operating and the "inspection start key" is pressed (not shown), all contents of the abnormality occurrence ignore mask memory 15 become "display=0". In other words, it is cleared once and the inspection is started again.

At this time, the error display on display 7 is also cleared once, so the defect occurs again and the error occurrence signal is
When the ES is transferred to the CPU 14, similar processing is performed and the display is displayed on the display 7.

On the other hand, if the operator visually determines that the abnormal printed matter is acceptable, he presses the abnormal occurrence ignore key 16 without stopping the printed matter, and the CPU
14 clears only the display 7 while leaving the contents of the abnormal occurrence ignoring mask memory 15 unchanged.

As a result, the inspection continues, but even if the abnormality occurrence signal ES enters the CPU 14 from now on, if the data at the corresponding address in the abnormality occurrence ignore mask memory 15 is "do not display = 1", the CPU 14
The occurrence of an abnormality is not displayed on the display 7.

Furthermore, if the data at the corresponding address in the abnormality occurrence ignore mask memory 15 is "display=0", the CPU 14 displays on the display 7 the occurrence of an abnormality.

As a result, the error that occurred before the operator pressed the error occurrence ignore key 16 will not be displayed on the display 7, and after that, only the error that occurred at the new position (address) will be displayed on the display 7. .

Note that the present invention is not limited to the steps in the flowchart shown in FIG. Instead, similar functions may be achieved using hardware.

One embodiment is shown in FIG.

rotary encoder 5, sampling control 13, and detection section 4 to comparison circuit 11
Since the circuit configuration up to this point is the same as that shown in FIG. 2, the explanation thereof will be omitted here.

According to this embodiment, the comparison circuit 11 is connected to one input terminal of the AND circuit 18 to send the abnormality occurrence signal ES, and the comparison circuit 11 is connected to the memory control circuit 12 to send the abnormality occurrence signal ES.
Sends the reference memory address of the pixel where the error occurred. In addition, the memory control circuit 12
It is connected to the CPU 14 and also to the abnormality occurrence ignore mask memory 15. Abnormal occurrence ignoring mask memory 15 is inverter circuit 1
7 to the other input terminal of the AND circuit 18, and the output of the AND circuit 18 is connected to the CPU 14.
connected so that it can be inserted into the In addition, the display 7 and the abnormal occurrence ignore key 16 are connected to the CPU 14.
It is connected to the.

To explain the operation of such a circuit, at the same time as the abnormality occurrence signal ES is generated, the memory control circuit transfers data at the address of the abnormality occurrence ignore mask memory 15 corresponding to the address of the reference memory 9 of the pixel where the abnormality occurrence signal ES has occurred. Set it to “1” in step 12, and from then on, always use AND during inspection.
Ignore abnormality in circuit 18 Data in mask memory 15 is inverted by inverter circuit 17 and sent to CPU 1
Transfer to 4.

As a result, even if the abnormality occurrence signal ES enters the AND circuit 18, if the data content of the corresponding address in the abnormality occurrence ignore mask memory 15 is "1", the abnormality display signal ES' is not transferred to the CPU 14 and the display 7 is not displayed. Moreover, if the data content is "0", the abnormality display signal ES' is sent to the CPU 14.
The abnormality is displayed on the display 7. In addition, when the abnormality occurrence ignore key 16 is pressed, the display 7 is cleared, and when the inspection start key (not shown) is pressed, the data in the abnormality occurrence ignore mask memory 15 and the display are cleared. The operations performed are similar and are controlled by the CPU 14.

(Effects of the Invention) The printed matter inspection apparatus of the present invention has been described in detail above, but by using the present invention, it is possible to continue inspection while ignoring printing failures that do not pose a problem. This makes it possible to efficiently perform inspections.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a model diagram showing an outline of the printed matter inspection apparatus of the present invention, FIG. 2 is a block diagram of the processing circuit of the present invention, and FIG. The figure is a block diagram of a process related to display display according to the present invention, and FIG. 4 is a block diagram of another embodiment of the present invention. 4...Detection unit, 7...Display, 9...Reference memory, 12...Memory control circuit, 14...CPU, 15...Ignore abnormality mask memory, 16...Ignore abnormality key, 17...
...Inverter circuit, 18...AND circuit.

Claims (1)

[Claims] 1. A pattern of a printed matter is captured pixel by pixel by a detection unit, and a detection signal based on the detected pattern information of each pixel is compared with a reference signal for each corresponding pixel inputted in advance to detect the pattern of the printed material. A print inspection device for detecting an abnormality has a mask memory having an address corresponding to an address of a reference signal, has means for writing data indicating whether or not to be displayed on a display into the mask memory, and further has means for writing data indicating whether or not to display the abnormality on a display. 1. A printed matter inspection apparatus characterized by comprising means for checking the contents of data in the mask memory at an address corresponding to the address of a pixel in which a pixel has occurred, and determining whether or not to display the data on a display.