JPH0147821B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for accurately inspecting the printing quality of continuously running printed matter in a paperback printing press or the like while the machine is still running.

Generally, very strict conditions are required regarding the print finish of printed matter, so a sufficiently reliable method is also required for inspection.

Therefore, instead of the conventional visual inspection method, a method has been proposed and put into practical use that uses image processing technology to automatically inspect printed matter by comparing image patterns.

Figure 1 shows the principle of an example of such an inspection method by comparing image patterns, in which 1 is a printed matter, 2 is a rotating drum, 3 is an image sensor camera, and 4 is an analog/digital (A/D). Converter, 5 is a changeover switch, 6 is a reference value memory, and 7 is a detected value memory.

The printed matter 1 is a long piece of paper, film, etc., on which a predetermined pattern is successively and repeatedly printed along the running direction of the paper by a paperback printing machine, and is sent out by a rotating drum 2.

An image sensor camera (hereinafter referred to as an IS camera) 3 images the surface of the printed material 1 on which the pattern is printed, and one-dimensionally captures a predetermined portion along the width direction X perpendicular to the traveling direction Y of the printed material 1. Scan and extract image signals. The one-dimensional image signal read from the printed matter 1 is digitized for each predetermined pixel by an A/D converter 4 and supplied to a switch 5.

The reference value memory and the detected value memory 7 have storage contents as shown in FIG. It is configured to be readable. Therefore, the switch 5 is now switched to the reference value memory 6 as shown in the figure, and a predetermined pattern part of the printed matter 1 is transferred to the IS camera 3.
When the image is captured in the printing width direction, the density information for each pixel in the width direction The image data of a predetermined range of the image printed on the printed material 1 is written into the reference value memory 6 as density information in the addresses divided in the running direction of the reference value memory 6. will be written. Moreover, if the switch 5 is switched to the lower side opposite to that shown in the figure, image data of a predetermined range of the pattern of the printed matter 1 will be written in the same way.

Therefore, at a predetermined time immediately after starting the printing operation, the switch 5 is switched to the reference value memory 6, and then the switch 5 is switched to the detected value memory 7, and from then on, the corresponding addresses of the reference value memory 6 and the detected value memory 7 are By reading out and comparing the density information and checking whether they match or not, it is possible to continuously judge the quality of the printing of the printed material 1, which is running at a considerable speed during the printing operation, and also by visual inspection. Inspections can be performed with a level of reliability that is incomparably higher than regular inspections.

By the way, the position of the pattern that is continuously and sequentially formed on printed matter by such a logic printing machine in the direction perpendicular to the running direction of the printed matter, that is, in the printing width direction, is not always at the same position during the printing operation. . That is, the feeding operation of printed matter to a multicolor rotary printing press generally involves considerable widthwise fluctuations. Therefore, in such cases, the operator moves the printing cylinder of the printing press in the width direction each time to adjust the printing target, or the operator automatically adjusts the printing position.
Therefore, even if there is no abnormality in the printing operation and the pattern is printed correctly, the position in the width direction of the printed material is not necessarily the same, but always fluctuates.

On the other hand, in the above-described inspection method by comparing image patterns, the quality of printing is determined by comparing the data read from both the reference value memory 6 and the detected value memory 7. If the position of the pattern on the printed matter 1 changes in the width direction between when data is written to the detection value memory 7 and when data is written to the detected value memory 7, the data read from both memories may be incorrect even if the pattern is correct. If these do not match, malfunction will occur.

This will be explained in detail with reference to FIGS. 3 and 4.

In Fig. 3, 8 is the imaging part by the image sensor included in the IS camera 3 (Fig. 1).
It has a structure in which a large number of photoelectric conversion elements, for example, 512 photoelectric conversion elements, are arranged in a linear manner in the width direction of the printed matter 1. On the other hand, a to d represent patterns repeatedly printed in sequence on the surface of the printed matter 1. ing.

These patterns a to d have different positions in the x direction, that is, in the width direction, of the printed matter 1 for the reasons described above.

Next, in FIG. 4, one of the photoelectric conversion elements of the photoelectric conversion section 8 is indicated by 8', and one of the pixels of patterns a and b are indicated by a' and b', respectively.

Therefore, data is now written to the reference value memory (Fig. 1) in the state of picture a in Fig. 3, and then,
Assume that data according to picture b in FIG. 3 is written into the detected value memory 7. As a result, the relationship between a certain pixel a' of pattern a and the photoelectric conversion element 8' becomes as shown in FIG. 4, and the relationship between a certain pixel b' of pattern b and the photoelectric conversion element 8' becomes as shown in FIG. Suppose it becomes as shown in Fig. 4 2.

Then, the density information written to the corresponding address in the reference value memory 6 becomes data corresponding to the area a'' in FIG. The data corresponds to the area b'' in FIG. 4.

Therefore, at this time, even if patterns a and b are the same, the data read from the reference value memory 6 and the data read from the detected value memory 7 will no longer match, even though the pattern is correct. It will be determined that the printing is defective.

For this reason, the above-described conventional inspection method has the drawback that it is prone to malfunction due to misalignment of the pattern in the width direction of the printed matter, and that it is not possible to obtain sufficient reliability in the inspection results.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to avoid malfunctions even if the position of the pattern in the width direction of continuously running printed matter changes, and to obtain sufficiently reliable inspection results. An object of the present invention is to provide a method for inspecting a running printed matter.

In order to achieve this object, the present invention detects a positional change in the width direction of a pattern formed on the surface of a running printed matter, and calculates the amount of positional change when data is written to a reference value memory and when data is written to a detected value memory. When data is written to and exceeds the specified value,
The feature is that the contents of the reference value memory are rewritten with the data read from the picture at that time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for inspecting running printed matter according to the present invention will be described below with reference to the drawings.

FIG. 5 shows an embodiment in which the inspection method according to the present invention is implemented by a computer, and the rotating drum 2, IS camera 3, A/D converter 4, reference value memory 6, detected value memory 7, etc. This is the same as the conventional example.
In FIG. 5, 9 is a rotary encoder for detecting the rotational phase of the rotating drum 2, 10 is a running position signal input circuit, 11 is a scanning direction signal input circuit,
12 is an address generation circuit, 13 is a computer interface, 14 is an arithmetic unit, 15 is a computer, 16 is a picture position detector, 17 is a picture position signal input circuit, and 18 is a reference value memory rewrite signal generation circuit.

The rotary encoder 9 generates a signal representing the rotational angular position of the rotary drum 2. Therefore, by checking the signal from the rotary encoder 9, the traveling position of the printed material can be determined, and image data from a predetermined portion of the pattern can be captured. The signal from this rotary encoder 9 is transmitted to the traveling position signal input circuit 1.
0 to the internal bus BUS.

The running direction signal input circuit 11 functions to send a signal representing the scanning direction by the IS3 to the internal bus BUS.

The address generation circuit 12 functions to send address signals necessary for the operation of the reference value memory 6 and the detected value memory 7 to the internal bus BUS.

The arithmetic unit 14 compares the detected value data read from the detected value memory 7 with the reference data from the reference value memory 6 to determine the quality.

The computer 15 is called a personal computer, for example, and consists of a central processing unit CPU, a memory MEM, a keyboard KB, a display CRT, etc., and is connected to the internal bus BUS via the computer interface 13, and follows a predetermined program. Then various processing is performed.

The picture position detector 16 includes an image sensor,
The position in the width direction of a pattern printed on the surface of a traveling printed matter 1 (FIG. 1) is detected by a rotating cylinder 2, and a pattern position signal is sent to an internal bus BUS via a pattern position signal input circuit 17.

The reference value memory rewrite signal generation circuit 18 takes in the picture position signal from the picture position detector 16, holds the picture position data at the time when the data is written to the reference value memory 6, and then writes it to the detected value memory 7. Each time data is written, it is compared with the captured picture position data, and when the difference between the two exceeds a predetermined value, a reference value memory rewrite signal is generated.

Next, an embodiment of a method for detecting a picture position using the picture position detector 16 is shown in FIG.

In FIG. 6, a indicates a pattern printed on the printed matter 2, and 16' indicates a portion detected by the pattern position detector 16.

The picture position detector 16 is detected by the rotating drum 2.
A predetermined portion in the width direction Generates a detection signal when Therefore, when the position of the pattern a on the printed matter 2 changes in the width direction, that is, in the x direction, the size of the portion included in the detection portion 16' of the pattern a changes, and the amount of light incident on the pattern position detector 16 changes. It's going to change.

Therefore, the position of the pattern a in the x direction can be detected by detecting the amount of light incident on the pattern position detector 16, so the light amount detection signal from this detector 16 is taken as the pattern position signal, and the pattern position signal is Internal bus via input circuit 17
All you have to do is send it to the BUS.

Next, FIG. 7 shows another embodiment of the picture position detection method, in which M is a wedge-shaped register mark.

In multi-color printing presses, wedge-shaped registration marks are placed in the margins of the printing surface for automatic registration in the width direction of printed matter. Therefore, in this embodiment, this register mark M is imaged by the picture position detector 16, and the detected portion 16' of the register mark M is detected by the position change Δx in the width direction of the picture as shown in FIG. 7 A and B. A change in the area contained within the area is detected as a change in light amount, and a picture position signal is thereby obtained.

Therefore, according to this embodiment, a mark suitable for position detection can be used regardless of the original pattern, so that the detection operation can be performed more reliably.

Furthermore, FIG. 8 shows another embodiment of the method for detecting the position of a picture, in which N is a mark for detecting positional deviation printed in the margin of the printed matter.

This mark N consists of a large number of line segments printed at regular intervals along the width direction x of the printed material in parallel to the running direction y, and the line included in the detection portion 16' is determined according to the position change Δx in the width direction. The pattern position signal is obtained by utilizing the change in the number of minutes.

Therefore, according to this embodiment, it becomes easy to obtain the picture position signal as the number of pulses.

Next, FIG. 9 shows an embodiment of the reference value memory rewrite signal generation circuit 18, which is connected to a microcomputer (referred to as a microcomputer) MC having input/output ports _P1 to _P4 .
and latches R ₁ and R ₂ , which function to receive predetermined signals S ₁ to _{S 5} via an internal bus BUS and generate a rewrite signal S ₆ at a predetermined time.

Further, the signal _S1 is a control command given from the computer 15, and one of four types of operation modes is selected according to this control command _S1 . These four operating modes are: (1) Inspection device stop mode (hereinafter simply referred to as "stop" mode) (2) Position tolerance setting mode (hereinafter simply referred to as "setting" mode) (3) Reference value (4) Print inspection mode (referred to as "inspection" mode).

The signal _S2 is a signal for inputting the position tolerance input from the computer 15 from the latch _R1 to the port _P2 of the microcomputer MC.

Signal S ₃ is connected to register R ₁ from computer 15
This is data representing the positional tolerance value written in.

The signal _S4 is a signal generated from the microcomputer MC in order to input the picture position information written in the latch _R2 to the port _P3 of the microcomputer MC.

The signal _S5 is sent from the picture position detector 16 to the input circuit 17.
This is the picture position information written to latch _R2 via .

The signal _S6 is a signal output from this reference value memory rewrite signal generation circuit 18 to the internal bus BUS, and is a reference value memory rewrite signal generated when the picture position changes beyond the allowable value. It is.

Next, the operation of the reference value memory rewrite signal generation circuit 18 shown in FIG. 9 will be explained with reference to the flowchart shown in FIG.

Now, assuming that signals S ₁ to S ₃ and S ₅ are given to this circuit 18 via the internal bus BUS, the microcomputer MC first checks what the content of the control command S ₁ is and determines whether it is When in the "stop" or "setting" mode, reading of the control command _S1 is repeated. However, in the "setting" mode, the signal S ₂ causes the latch R ₁ to be connected to the port of the microcontroller MC.
Input position tolerance data _S3 into _P2 .

Also, when the control command S ₁ is in the "reference" mode, the signal S ₄ is first generated and the latch is activated.
The picture position information is taken into the microcomputer MC from _R2 via port _P3 , and this is stored as the picture reference position information at the time of reference value data import, that is, the reference picture position data, and then the control command _S1
Return to reading.

Then, when the control command _S1 enters the "inspection" mode, the operation is as follows.

(i) Transfer the position tolerance data input to port _P2 in the "setting" mode to the register in the microcontroller MC.

(ii) Import the picture position information in the same way as in the "Standard" mode, use it as the position information at the time of importing the detection value data, that is, picture position data, compare it with the reference picture position data above, and calculate the difference. Calculate absolute value.

(iii) Next, the absolute value of this difference is compared with the position tolerance value, and when the absolute value of the difference exceeds the position tolerance value, a reference value memory rewrite signal _S6 is generated.

(iv) Return to reading control command _S1 .

Therefore, according to the embodiment shown in FIG. 5, the positional deviation in the width direction of the pattern of the printed matter 1 becomes large
Whenever it exceeds a preset tolerance value, a rewrite signal S6 is supplied from the reference value memory rewrite signal generation circuit 18 to the reference value memory 6, and at that time the rewrite signal _S6 is read by the IS camera 3. The current image data is written to the reference value memory as new reference value data, and thereafter, the detected value data is updated by this newly written reference value data until the rewrite signal _S6 is generated again. Since the discrimination is carried out, there is no malfunction even if the printed pattern is misaligned in the width direction perpendicular to the running direction of the printed matter, and only the quality of the pattern can be accurately determined at all times.

Note that in this embodiment, the detection data is written to the memory once and then read out and compared.
It goes without saying that the present invention can also be applied to a real-time processing method in which detected data is immediately compared with reference data without using memory.

As explained above, according to the present invention, even if the position of a printed pattern deviates in the width direction perpendicular to the running direction of printed matter in a multi-color paper transfer printing machine or the like, a malfunction occurs in determining the quality of printing. Since the risk can be eliminated, it is possible to provide an inspection method that can always maintain sufficient reliability in determining the quality of printing.

[Brief explanation of drawings]

Fig. 1 is a principle diagram showing an example of a method for determining the quality of printing by comparing image patterns, Fig. 2 is an explanatory diagram showing the stored contents of the memory, and Figs. 3 and 4 show conventional methods. FIG. 5 is an explanatory diagram showing problems in the inspection method; FIG. 5 is a block diagram showing an embodiment of the inspection method for running printed matter according to the present invention; FIG.
FIGS. 7A and 7B and FIGS. 8A and 8B are explanatory diagrams showing separate embodiments of the picture position detection means of the present invention, and FIG. 9 is an implementation of the reference value memory rewrite signal generation circuit. An explanatory diagram showing an example, FIG. 10 is a flowchart for explaining the operation. 16...Picture position detector, 17...Picture position signal input circuit, 18...Reference value memory rewrite signal generation circuit, a...Picture, M...Wedge-shaped register mark, N...For detecting positional deviation mark.

Claims (1)

[Claims] 1 The image data read from the pattern of the running printed matter at a predetermined time is written and held in the memory as reference value data, and thereafter the image data read sequentially from the pattern of the running printed matter is defined as detection value data and written into the memory. In a method for inspecting running printed matter in which the quality of printing is determined by comparing it with held reference value data, a picture position detection means for detecting a picture position in a direction perpendicular to the running direction of the running printed matter is provided, and the above-mentioned predetermined time point is The picture position data captured by the picture position detection means is held as reference picture position data, and the picture output from the picture position detection means is combined with the held reference picture position data each time the detected value data is read. Deviation data is obtained by sequentially comparing the position data and when this deviation data exceeds a predetermined value, the above-mentioned reference value data is rewritten with new image data read from the pattern of the traveling printed matter at this time, and this new image data is A method for inspecting running printed matter, characterized in that the quality of printing is determined sequentially based on reference value data.