JP2931108B2 - Printed matter monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for various types of printing presses such as rotary offset printing presses, and more particularly to a printed matter monitoring device for detecting a defect such as a stain on a printed matter.

[0002]

2. Description of the Related Art Conventionally, as a printed matter monitoring device for detecting a defect such as a stain on a printed matter, for example, Japanese Patent Laid-Open No. 60-5853 is disclosed.
No. 5, JP-A-56-98638 is known. These monitor dirt and the like generated on the printing surface by the detection sensor. The detection sensor extends in a direction perpendicular to the direction of movement of the printing surface. Then, by sequentially scanning the detection sensor in accordance with the movement of the printing surface, the entire printing surface is monitored linearly.

That is, in the direction (longitudinal direction) perpendicular to the direction of movement of the printing surface, the total number of light receiving elements arranged in the direction of movement of the printing surface (flow direction) depends on the movement of the printing surface. The printing surface is divided and monitored for each of the divided zones (pixels).

Then, a predetermined number of printed materials are measured in a state in which a good product comes out after the printing adjustment, and an average value, a maximum value, a minimum value, and the like are obtained, thereby obtaining a reference value matrix of each pixel / reference value matrix Ao (i, j). ); I is the pixel number in the longitudinal direction, j is the pixel number in the flow direction and the allowable value {the allowable value matrix {(i, j)}
And make. Thereafter, the measured value {measured value matrix Ak (i, j); k is the k-th printed material} for each printed material is obtained.

When the difference between the reference value and the measured value is within the allowable value, it is determined that the product is good, and when the difference is out of the allowable value, it is determined that the product is defective. That is, | Ao (i, j) -Ak (i,
j) | is 良 (i, j) or less, | Ao (i, j)
If -Ak (i, j) | is larger than △ (i, j), it is determined to be defective.

[0006]

According to the above-mentioned prior art, it was possible to judge a defect when the fluctuation value of a pixel exceeded an allowable value.

However, defective printing surfaces include not only those that suddenly occur at unspecified positions, such as ink splashing, water dripping, oil dripping, etc., but also the ink adjusting device of the printing press during adjustment. There is a streak defect generated in the flow direction due to density unevenness or a blanket defect generated in the flow direction. Unlike transient defects such as ink splash, water dripping, oil dripping, etc., density unevenness and streak defects are continuous and require adjustment of the printing press.

As described above, there are two types of defects in the printed matter.
It would be desirable to have a printed matter monitoring device that can take actions such as automatically adjusting or stopping the machine.

However, in the prior art, such defective contents cannot be identified, and can be simply treated as a printed matter defective.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
Insufficient printing such as ink splash, water dripping, oil dripping, etc.
An object of the present invention is to provide a printed matter monitoring device capable of identifying and monitoring a streak defect.

[0011]

In order to achieve the above object, according to the present invention, a defect rate in a non-image portion in each unit area of a printing surface to be monitored is determined by a defect rate in an image portion in the same area. A central processing unit that calculates the defect rate of each pixel of the printing surface based on the reflection density information of each pixel, and the defect rate in the non-image part and the defect rate in the image part obtained by the central processing unit. And a failure content identification unit that determines the failure content of the printed surface by comparing the failure content with a preset failure rate classification value.

[0012]

The defect rate in the non-image part in each unit area of the printing surface to be monitored and the defect rate in the image part in the same area are determined based on the reflection density information for each pixel of the printing surface. Is calculated by the central processing unit.

Then, the defect rate in the non-image area and the defect rate in the image area obtained by the central processing unit are compared with a preset defect rate discrimination value in a defect content identification section. Thus, the content of the defect on the printing surface is determined.

Thus, not only the printing failure is detected, but also the content of the failure is identified.

[0015]

1 and 2 show a schematic configuration of a printed matter monitoring apparatus according to an embodiment of the present invention. A detection sensor 100 monitors a stain or the like generated on a printing surface 101 to be monitored. It should be noted that dirt on the printing surface 101 must be monitored at all times because it is generated by ink splashing or accidents such as water dripping or oil dripping. The detection sensor 100 extends in a direction (longitudinal direction χ of the printing surface) orthogonal to the moving direction of the printing surface 101 (flow direction y of the printing surface), and a plurality of sensors arranged at appropriate intervals in the longitudinal direction χ of the printing surface. (L) light receiving elements 1.

The light receiving element 1 detects light reflected from the printing surface 101.

The photocurrent generated by the light receiving element 1 in response to the light reflected from the printing surface 101 is converted from current to voltage by logarithmic conversion by a logarithmic conversion unit 2 so as to be converted into reflection density information and a required voltage level. Amplified.

The reflection density information for each pixel is sent to the sample hold amplifier 3. Sample hold amplifier 3
Is supplied with a sample signal from the encoder unit 4 that generates a signal corresponding to the pixel size in the web flow direction 合 わ せ in accordance with the movement of the printing surface 101. 101, t pixels in the longitudinal direction χ, and the flow direction y
Are divided into m pieces.

The reflection density information for each pixel sampled and held by the sample-and-hold amplifier 3 in accordance with the pixel is time-divided by the multiplexer 5 and sequentially A /
It is sent to the D converter 6. A plurality of multiplexers 5 and A / D converters 6 can be used in parallel to reduce the processing time.

The A / D converter 6 converts the reflection density information for each pixel from an analog value to a digital value.

Each reflection density information converted into a digital value is stored by the memory controller 7 in a predetermined memory position of the storage device 8 for each pixel position.

The storage device 8 is divided into the following parts according to the contents of the memory. That is, the memory 9 (blank surface matrix portion Dw (i)), the memory 10 (blank surface allowable value matrix portion Dwa (i)), the memory 11 (reference value matrix portion Ds (i, j)), and the memory 12 (allowable value). Matrix part Da (i, j)), memory 13 (image determination matrix part Z1 (i, j)), memory 14 (image determination matrix part Z2 (i, j)), memory 15 (measured value matrix part D
k (i, j)), memory 16 (judgment matrix part D
out (i, j)), memory 17 (product matrix section ZD1)
(i, j)), memory 18 (product matrix section ZD2
(i, j)), memory 19 (addition matrix section Z1 S
UM (i)), memory 20 (addition matrix section Z2 S
UM (i)), memory 21 (addition matrix section ZD1)
SUM (i)), memory 22 (addition matrix section ZD
2 SUM (i)), memory 23 (failure rate matrix section ERR1 (i)), memory 24 (failure rate matrix section E
RR2 (i)), memory 25 (memory 1 for the number of light receiving elements), memory 26 (memory m for the number of separations in the printing surface flow direction), memory 2
7 (predetermined number memory n), memory 28 (maximum value matrix portion MAX (i, j)), memory 29 (minimum value matrix portion MIN (i, j)), and memory 30 (coefficient memory α). ing.

The arithmetic unit 31 performs a specified operation (addition, subtraction, multiplication, division, comparison) on the memory contents retrieved via the memory controller 7.

The arithmetic unit 31 and the memory controller 7
A central processing unit 35 is constituted by the above-mentioned storage device 8.

The failure content identification section 32 stores the failure rate matrix section ERR1 of the memories 23 and 24 in the storage device 8 obtained as a result of the arithmetic processing by the arithmetic device 31 in the storage device 8.
(i), the failure content is identified by the value of ERR2 (i) and the failure rate classification value stored in the failure content identification unit 32, and an identification signal is generated.

The identification signal is sent to the print control device 33, and the print control device 33 performs display to the operator, stop of the printing press, instruction to the printing press adjusting device, and the like.

The fraction defective value 34 can be appropriately rewritten by the print controller 33.

Next, a series of procedures for determining the content of a defect on the printing surface 101 will be described with reference to FIGS. 4 (a) to 4 (c). << Preparation step before monitoring >><Step1> Blank paper (white background)
Is prepared in a predetermined number (determined appropriately according to the capability of the printed matter monitoring device and the printing press fluctuation state).

The reflection density information of each pixel from the first sheet of white paper is stored as a reflection density value at a predetermined position in the memory 15. At the same time, it is also stored in the memories 28 and 29. From the second blank page, the data is added to the memory 15 and stored in the memory 28. If the value is larger than the value previously stored in the memory 28, the value is stored again.
Is stored again when the value is smaller than the previously stored value. This is repeated for a predetermined number (n) stored in the memory 27 (predetermined number memory). After processing the predetermined number of sheets, the content of the memory 15 is divided by the value n of the memory 27, and the average value of each pixel is obtained and stored in the memory 15.
Then, the contents of the memory 15 are added for all pixels in the flow direction for each longitudinal pixel, divided by the value of the memory 26, and stored in the memory 9.

Thus, the blank page matrix D is stored in the memory 9.
w (i) is formed.

It is to be noted that the reason why this blank space matrix is collectively set as Dw (i) for each flow direction is that there is not much variation in the reflection density value in the flow direction, but the light source unevenness of the monitoring device in the longitudinal direction. This is because there is variation due to unevenness of the light receiving system, unevenness of the light receiving element, and the like.

Hereinafter, the case where the matrix is grouped for each pixel in the longitudinal direction is based on the same reason. The flow direction pixels e grouped for each of the longitudinal pixels form a unit area f.

Next, the contents of the memory 28 are added for all the pixels in the flow direction for each pixel in the longitudinal direction, are divided by the value of the memory 26, and are stored in the memory 10. Then, the contents of the memory 29 are added for all pixels in the flow direction for each pixel in the longitudinal direction,
This is divided by the value in the memory 26, subtracted from the value in the memory 10, and stored in the memory 10 again. Further, the value of the memory 10 for each pixel is multiplied by the value α of the memory 30 (coefficient memory) and stored in the memory 10 again.

In this manner, a blank page allowable value matrix Dwa (i) is formed in the memory 10.

<Step 2> Next, after the print operator has performed the print adjustment work, when it is recognized that non-defective products have been printed, reference data is created using these non-defective products as reference print surfaces. Each pixel reflection density value from the first sheet of the reference printing surface is stored at a predetermined position in the memory 11. At the same time, the data is stored at a predetermined position in the memories 28 and 29. From the second reference printing surface, the values are added and stored in the memory 11, compared with the value previously stored in the memory 28, and if larger, stored in the memory 28 again and stored in the memory 29. Is compared with the value previously stored in the memory 29 and is stored in the memory 29 again when it is smaller. This is repeated for a predetermined number (n) stored in the memory 27. After processing the predetermined number of sheets, the content of the memory 11 is divided by the value n of the memory 27, the average value of each pixel is obtained, and the average value is stored in the memory 11 again. Thus, the reference value matrix D is stored in the memory 11.
s (i, j) is formed.

Next, the content of the memory 29 is subtracted from the content of the memory 28 and stored in the memory 12. The content of the memory 12 is multiplied by the value α of the memory 30 (coefficient memory) and stored in the memory 12 again.

Thus, an allowable value matrix Da (i, j) is formed in the memory 12.

<Step 3> Reference value matrix Ds
For each pixel in the longitudinal direction of (i, j), a difference from the blank page matrix Dw (i) is obtained for all pixels in the flow direction, and if the absolute value of this difference is smaller than the blank page allowable matrix Dwa (i), The pixel is determined to be a white background portion (non-image portion). At this time, 0 is given to the corresponding position Z1 (i, j) of the memory 13 and 1 is given to the corresponding position Z2 (i, j) of the memory 14. The absolute value of the difference is the blank space allowable value matrix Dwa (i)
If larger, the pixel is determined to be an image part. At this time, 1 is given to the corresponding position Z1 (i, j) in the memory 13,
0 is given to the corresponding position Z2 (i, j) in the memory 14. Thus, an image determination matrix Z1 (i, j) having image information is formed in the memory 13, and an image determination matrix Z2 (i, j) having white background information is formed in the memory 14.

Next, an added value obtained by adding all the pixels in the flow direction for each pixel in the longitudinal direction of the image determination matrix Z 1 (i, j) is stored in the memory 19. Further, an added value obtained by adding all the pixels in the flow direction for each pixel in the longitudinal direction of the memory 14 is stored in the memory 20.
To memorize.

Thus, the addition matrix Z is stored in the memory 19.
1 SUM (i) is formed, and an addition matrix Z2 SUM (i) is formed in the memory 20.

At this point, the pre-monitoring preparation operation is completed.

In the above description, the value n of the predetermined number memory of the memory 27 and the value α of the coefficient memory of the memory 30 are always treated as the same, but different values are used for the blank page and the reference page. It is good. << Defective Product Monitoring Step >> Next, the following processing is performed on the print surface to be monitored to determine a defective product.

<Step 4> Each pixel reflection density value of the printing surface 101 is stored in a predetermined position of the memory 15. Thus, a measured value matrix Dk (i, j) is formed in the memory 15. (Note that k represents the k-th printing surface.) The measurement value matrix Dk (i, j) and the reference value matrix Ds (i,
j), and the difference is the tolerance matrix Da (i,
If it is larger than the value of j), it is determined to be defective and the memory 1
1 is given to the contents of 6, and 0 is given otherwise.

In this way, a judgment result matrix Dout (i, j) is formed in the memory 16. <Step 5> Next, the image determination matrix Z1 (i, j)
And the determination result matrix Dout (i, j) is multiplied for each pixel, and the calculation result is stored in the memory 17. Further, the image determination matrix Z2 (i, j) is multiplied for each pixel by the determination result matrix Dout (i, j), and the calculation result is stored in the memory 18.

Thus, the product matrix ZD1 (
i, j) are formed. Similarly, a product matrix ZD2 (i, j) indicating a defective pixel position generated in a white background portion as a non-image portion on the printing surface is formed in the memory 18.

<Step 6> Next, the product matrix ZD
An added value obtained by adding all the pixels in the flow direction for each (i, j) longitudinal pixel is stored in the memory 21. Further, an added value obtained by adding all the pixels in the flow direction for each pixel in the longitudinal direction of the product matrix ZD2 (i, j) is stored in the memory 22.

Thus, the addition matrix Z is stored in the memory 21.
D1 SUM (i) is formed, and an addition matrix ZD2 SUM (i) is formed in the memory 22.

Next, the addition matrix ZD1 SUM
(I) is divided by the corresponding value of the product matrix ZD1 (i, j) and stored in the memory 23 at the position corresponding to each pixel. Further, the content of the addition matrix ZD2 SUM (i) is divided by the corresponding value of the product matrix ZD2 (i, j) and stored in the memory 24 at a position corresponding to each pixel.

In this way, the defect rate matrix ERR1 (i) of the image portion on the printing surface is formed in the memory 23,
4 shows the defect rate matrix ERR2 (i) of the white portion of the printed surface.
Is formed.

<Step 7> Defect rate matrix ERR
When the values of 1 (i) and ERR2 (i) are larger than the defect rate discrimination value 34 by the defect rate discrimination value 34 for each longitudinal pixel in the defect content discriminating unit 32, the value is “large”, and when the value is smaller, the value is “small”. ", The failure rate matrix ERR1 (i), ERR2
Depending on the value of (i), the following four cases can occur.

When ERR1 (i) is “large” and ERR2 (i)
When ERR1 (i) is "Large" and ERR2 (i) is "Small" When ERR1 (i) is "Small" and ERR2 (i) is "Large" ERR1 (i) is "Large" In the case where ERR2 (i) is "small" and ERR2 (i) is "small", the density of the image area is lower than the density of the image area because many defects occur on the white background of the printing surface and the image area also has defects. It is considered that dark streak-like stains occurred on the printing surface.

In the case of (1), a lot of defects occur on a white background portion of the printing surface, and there is not much defect on the image portion. It is considered to have occurred on the surface.

In such cases, it is determined that streak-like stain has occurred on the printing surface. In the case of, there is little defect in the white portion of the print surface, and many defects have occurred in the image portion. It is considered that there was a defect in image formation. That is, a portion having a density different from that of the reference image exists in the formed image in a streak shape. From this, in the case of, it is determined that streak density unevenness has occurred in the image portion on the printing surface.

In the case of (1), since there is little defect in both the image portion and the white background portion on the printing surface, it is determined that dot-like stain has occurred on the printing surface.

<Step 8> If the defect content is the streak density unevenness, the following process is further performed by the defect content identification unit 32.

The control width of the ink fountain device of the printing press is set to, for example, 3
If 0 mm and the pixel width in the longitudinal direction of the monitoring device are, for example, 5 mm, one control width of the inking device is constituted by 30 ÷ 5 = 6 pixels. From this, if there is a failure content determination result and the result is the same for, for example, six consecutive pixels in the longitudinal direction, it is determined that this is stripe-like density unevenness due to the control width of the ink ejection device.

By performing the above steps (steps 1 to 8), it is possible to know not only the occurrence of a defect on the printing surface but also the content of the defect.

Then, the defective product monitoring step (steps 4 to 8) is repeated for each of the second and subsequent printing surfaces, and
By performing display to the operator or feedback to the printing press adjustment device such as automatic adjustment and automatic stop according to the determination result, it is possible to prevent a large amount of defects from occurring and to contribute to an improvement in the operation rate of the printing press.

The present embodiment has been described with reference to an example in which the printed image is a single-color or four-color print, and the image is not simply a color but a shade. However, it is obvious that more detailed printing error information can be obtained by performing a color separation process in the sensor unit and using the same method for each color.

[0060]

As described above, in the present invention,
By comparing the defective rate and the defective rate classification value, the content of the printing failure can be described as transient defects such as ink splash, water dripping, oil dripping, and the like such as streak density unevenness and streak stain. It can be divided into continuous failures. Thus, in the case of a continuous failure, the operator is instructed to adjust the printing press, performs automatic adjustment, and stops the printing press, thereby preventing the occurrence of a large number of defects and contributing to an improvement in the operation rate of the printing press.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a printed matter monitoring apparatus according to one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a main part of the apparatus.

FIG. 3 is a diagram showing a state where a printing surface monitored by the device is divided into pixels.

FIG. 4 (a) is a flowchart showing a series of procedures for determining the content of a defect on a printing surface in the apparatus.

FIG. 4 (b) is a flowchart showing the same procedure.

FIG. 4 (c) is a flowchart showing the same procedure.

[Explanation of symbols]

 32 defective content identification unit 35 central processing unit 101 printing surface e pixel f unit area

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41F 33/14 G01N 21/84 G01N 21/88 G01N 21/89

Claims (1)

(57) [Claims] 1. The defect rate of a non-image portion in each unit area of a printing surface to be monitored and the defect rate of an image portion in the same region are determined by using reflection density information for each pixel of the printing surface. The central processing unit calculates the defect rate in the non-image part and the defect rate in the image part obtained by the central processing unit, and compares the defect rate in the image part with a preset defect rate classification value. A printed matter monitoring device, comprising: a defective content identification unit for determining the defective content of the surface.