JPH04169235A - Method and device for detecting defect in multicolor printed matter - Google Patents

Abstract

PURPOSE:To improve reliability and efficiency of detection by a method wherein positions of defects in width direction are measured by means of image signals of a television camera to move a television camera for monitoring to a point through which the defect is expected to pass and a picture if at specified region including the defect is taken to display a stationary picture. CONSTITUTION:A television camera 2 for detecting defect takes a black and white picture of a long multicolor printed matter, i.e., printed surface S, over entire width and when a defect is detected during printing, a defect detector 5 measures the position in the width direction of the printed matter by counting the number of elements from the light receiving element of a linear array image sensor of the camera to a light receiving element at the position of the defect. A monitoring device 51 moves a monitoring color television camera 53 in the width direction of the matter based on position information to a point through which the defect is expected to pass to take a picture of a specified region including the defect when it reaches said point. On receipt of image signals, a color stationary picture display device 55 displays said signal on a television monitor 58 as color stationary picture. As a result, color and kind of defect can be found.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inspection method and apparatus for inspecting the quality of printing of multicolor printed matter obtained by, for example, gravure printing.

[Prior Art] Gravure printed matter is usually inspected at predetermined intervals by a skilled worker who directly visually inspects the printed matter to determine if there are defects such as missing or blurred patterns or characters, or scratches. We are determining whether By specifying the color in which the defect appears, the type of defect, etc., corresponding defect avoidance measures can be taken. For example, if a pattern or text is missing or blurred, the roll pressure of the gravure printing machine that printed the defective color will be adjusted, or the viscosity of the ink will be adjusted. Color doctoring is performed, thereby preventing future defects from occurring.

Furthermore, a technique is known in which the quality of printing is determined by pattern matching. This technique was implemented as follows.

First, a printed material determined to be good by visual inspection or the like is prepared, and a monochrome image of the printed material is captured using a television camera. Next, the camera's video signal is processed to extract the print outline pattern. Then, the enlarged outline pattern obtained by subjecting this outline pattern to vertical and horizontal enlarging processing is stored in a memory as a mask pattern. This enlargement process allows some errors based on printing variations and movement accuracy of printed matter to be tolerated. Thereafter, the printed matter to be inspected is imaged by the television camera. Then, a contour pattern extracted by a contour extraction means that processes the video signal of this camera,
The readout of the mask patterns stored in the memory is synchronized, and pattern matching is performed by comparing them by a pattern matching means.

In other words, by such a pattern matching method,
Information for determining the quality of printing can be obtained.

Furthermore, color still image display devices that display part of a printed surface as a color still image on a television monitor are also known. In this device, a color television camera is movably attached to a traverse rail that faces the printing surface of a traveling printed material and extends in the width direction of the printed material, and the camera is moved to an arbitrary position to cover a predetermined area of the printing surface. A color still image is captured and displayed on a television monitor connected to the camera. Therefore, when using this color still image display device, without stopping the running of the printed matter,
Any position on the printed surface can be sampled and monitored as a still image.

[Problems to be Solved by the Invention] In the defect detection using pattern matching described above, detection is performed by comparison with a mask pattern, so it is not possible to detect the type of the detected defect. Furthermore, since the color information of the printed surface is captured in monochrome as luminance information, it is also impossible to detect which color the detected defect is. Therefore, even if the defect detection technique described above is applied to an inspection apparatus for multicolor printed matter, there is a problem in that it is not possible to infer the cause of a defect from the inspection result and take sufficient measures to avoid the defect.

In addition, with the above color still image display device, only a part of the printed surface can be viewed as a color still image, but since printing defects occur randomly, there is no guarantee that the screen of the TV monitor will contain defects. do not have. Therefore, even if such a color still image display device is used, it cannot be expected to save much labor in defect inspection, and it is only used for checking printing register. Note that if this color still image display device is used to continuously obtain still images in the width direction of the printed surface, it is possible to monitor the entire width, but in that case, multiple There is a problem in that the traveling speed of colored printed matter cannot be increased and the inspection speed becomes slow.

An object of the present invention is to provide a method and apparatus for inspecting defects in multicolor printed matter that can improve the reliability and efficiency of defect inspection for multicolored printed matter.

[Means for Solving the Problems] In order to achieve the above object, in the defect inspection method for multicolor printed matter of the present invention, a defect detection television camera having a linear array image sensor as a light receiving part is used to continuously detect defects while traveling. image the entire width of a long multicolored printed matter,
The video signal from the television camera is processed to determine the quality of printing of the multicolor printed matter, and when it is determined that there is a defect during printing, the position of this defect in the width direction of the multicolored printed material is determined. a defect monitoring position movable in the width direction of the multicolored printed material at a defect monitoring position downstream in the running direction of the multicolored printed material from the printing defect detection position where the defect detection television camera is arranged. A color television camera is moved to a scheduled position where the defect passes based on the position information of the defect, and the camera images a predetermined area including the defect when the defect passes the scheduled position, The video signal from the surveillance color television camera is displayed on the television monitor as a color still image.

Further, to achieve the same purpose, a defect inspection device for multicolor printed matter is placed at a print defect detection position determined at an arbitrary position, and images a continuous long running multicolored printed matter over its entire width direction. A defect detection television camera with a linear array image sensor as a light receiving part, and a video signal from the television camera is supplied, and the video signal is processed to determine the quality of printing of the multicolor printed matter, and
a defect detection device that measures the position of the defect in the width direction of the multicolor printed matter when it is determined that there is a defect during the printing; a monitoring color television camera that is placed at a predetermined defect monitoring position, is always located at the center of the multicolor print in the width direction, and is movable in the width direction of the multicolor print using this position as an origin; and is supplied with positional information of the defect measured by the defect detection device, and based on this positional information, moves and arranges the monitoring color television camera to a scheduled position where the defect passes,
A monitoring device that uses the camera to image a predetermined area including the defect when the defect passes through the scheduled position, and a color still image that displays a video signal from the monitoring color television camera as a color still image on a television monitor. It is equipped with a display device.

[Function] At its installation position, that is, at the printing defect detection position, the defect detection television camera scans the printed surface of a continuous long multicolor printed matter that is running, printed in multiple colors by a gravure printing machine, over its entire width. Capture images in monochrome. By this imaging, color information on the printed surface is photo-electrically converted as brightness information.

A defect detection device to which the output (video signal) of the defect detection television camera is supplied processes the video signal and determines the quality of printing. When it is determined through this determination that there is a defect during printing, the defect detection device measures where the detected defect is located in the width direction of the multicolor printed material with respect to the origin set at an arbitrary position. This measurement is performed by counting and calculating the number of elements from the light receiving element at the position corresponding to the origin of the television camera linear array image sensor to the light receiving element at the position corresponding to the defect.

The monitoring device, which is supplied with the positional information of the defect obtained through this calculation process, moves the above-mentioned color monitoring television camera from its origin position in the width direction of the multicolor printed material based on the positional information, and moves it to the defect monitoring position. The above-mentioned defect is moved to a predetermined position where it passes. Note that the color television camera is focused on the printing surface in advance.

Then, when the defect detected by the defect detection device is moved to the predetermined position as the multicolor printed matter travels, the color television camera operates in synchronization with the movement of the multicolor printed matter to detect a predetermined position including the defect. Image the area.

A color still image display device to which a video signal from the monitoring color television camera is supplied displays the video signal as a color still image on a television monitor.

As described above, each time the defect detection device automatically detects a defect while the multicolor printed matter is running, the operator monitors a color still image of a predetermined area containing the detected defect via the TV monitor. can. Therefore, not only can defects be automatically detected, but also the detected defects can be reliably viewed as a color still image. Therefore, by monitoring the detected defects, it is possible to know the color and type of the defects.

In addition, in the defect inspection device, the monitoring color television camera of the monitoring device moves in the width direction of the multicolor printed material with the origin at the center position in the width direction of the multicolored printed material. It is possible to shorten the time required to reach the position where the edge of the printed matter is imaged.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Reference numeral 31 in FIG. 1 is a gravure printing apparatus, which is formed by, for example, eight gravure printing machines 32 to 39 arranged in parallel with each other. Reference numeral 40 in FIG. 1 is an unwinding roll on which a continuous long sheet of paper used for printing is wound, and the sheet unwound from this roll is supplied to the first-stage gravure printing machine 32.

Reference numeral 41 in FIG. 1 is a take-up roll for the multicolor printed matter S. This is a roll for winding up the multicolored printed matter S, which is paper that has passed through each of the gravure printing machines 32 to 39 one after another and has been printed in eight colors. It is. A defect inspection line is set between the gravure printing machine 39 in the final eighth stage and the take-up roll 41. Note that the arrows in FIGS. 1 and 2 indicate the running direction of the multicolor printed matter S.

Reference numeral 1 in FIGS. 1 and 2 is a camera unit equipped with, for example, four television cameras 2 for detecting defects. It is arranged to face the printed surface of the printed material S and to extend in the width direction of the printed material S. The field of view of the camera unit 1 is illuminated by an illumination device (not shown) provided as necessary.

Each defect detection television camera 2 is arranged along the width direction of the multicolor printed matter S, and each camera 2 has a CCD
A linear array image sensor is used as a light receiving part. Each of these television cameras 2 can scan the entire printed surface of the multicolor printed matter S in the width direction. The video signal output from each television camera 2 is processed by the defect detection bag f15 shown in FIG. 1, thereby determining whether the multicolor printing is good or not and measuring the position of the defect f.

The defect detection device 5 includes an AGC device 6, a contour extraction circuit 7, a first defect recognition section 8, a first defect determination circuit 9, a second defect recognition section 10, a second defect determination circuit 11, and a defect position measurement circuit 12. It is prepared and formed. Next, these will be explained.

The AGC device 6 is connected to the output end of the television camera 2, and is used to stabilize the transmission output against gain fluctuations of the defect detection device 5 as a whole.

A contour extraction circuit 7 serving as contour extraction means is connected to the output end of the AGC device 6. This circuit 7 consists of a differentiating circuit, takes in all the signals output from the television camera 2, emphasizes changes in this signal, and thereby extracts the outline pattern of the image.

The first defect recognition unit 8 includes a first pattern enlargement processing circuit 15 as a pattern enlargement processing means, a first mask pattern memory 16 as a first storage means, and a first pattern matching circuit 17 as a pattern matching means. It is formed from.

The first pattern enlargement processing circuit 15 is connected to the output end of the contour extraction circuit 17. This circuit 15 is a circuit for enlarging the signal related to the contour in the vertical direction and the horizontal direction in order to allow errors due to printing variations and feeding accuracy of the multicolor printed matter S, and the enlarged size Therefore, it is possible to tolerate some errors based on the expected variations and the feeding accuracy of the multicolor printed matter S. This enlarged dimension is specified when setting the cultivation season. Then, this circuit 15 performs a pattern enlargement process on the outline pattern to form a pattern to be inspected.

The first mask pattern memory 16 is connected to the output end of the contour extraction circuit 7. This memory 16 is capable of writing and reading, and stores mask contour patterns extracted by the contour extraction circuit 7 from multicolor printed matter that is determined to be good by visual inspection or other appropriate inspection. . Then, the memory 16 stores the mask contour pattern stored therein in the same type of multicolored printed matter S.
While the information is being inspected, it will be frozen and retained so that it will not be changed.

The first pattern matching circuit 17 connects the output terminal of the first pattern enlargement processing circuit 15 and the first mask pattern memory 16.
are connected to the output ends of the respective output terminals. This matching circuit 17 compares and matches the mask outline pattern read out from the first mask pattern memory 16 with the pattern to be inspected obtained by the first pattern enlargement processing circuit 15, and identifies the cholera pattern. This is a comparison to see if they match.

The first defect determination circuit 9 is connected to the output terminal of the first pattern matching circuit 17.

This is to determine whether or not. Note that the term "missing defect" here refers to a defect in which a part of printing is missing or blurred, and the size of the defect is specified in the determination circuit 9 at the time of initial setting. Of course.

The second defect recognition section 10 includes a second pattern enlargement processing circuit 21 as a pattern enlargement processing means, as shown in FIG.
, a second mask pattern memory 22 as a second storage means.
, and a second pattern matching circuit 23 as a second pattern matching means.

The second pattern enlargement processing circuit 21 is connected to the output end of the contour extraction circuit 7. This circuit 21 has the same configuration as the first pattern enlargement processing circuit 15, and performs pattern enlargement processing on the outline pattern to form a mask enlargement pattern.

The second mask pattern memory 22 is connected to the output end of the second pattern enlargement processing circuit 21. This memory 22 is also capable of writing and reading,
This stores the mask enlarged pattern processed by the processing circuit 21 for printing multicolor printed matter that is determined to be good by visual inspection or other appropriate inspection. The mask enlargement pattern stored in this memory 22 is also
While the same type of multicolored printed matter is being inspected, it is frozen and held so as not to be changed.

The second pattern matching circuit 23 is connected to the output end of the contour extraction circuit 7 and the output end of the second mask pattern memory 22, respectively. This matching circuit 23 is
The mask enlarged pattern read from the second mask pattern memory 22 is compared with the contour pattern obtained by the contour extraction circuit 7 for printing multicolor printed matter to determine whether these patterns match. It is for comparison.

The second defect determination circuit 11 uses the second pattern ma-so.The term "flyaway defect" here refers to a defect caused by scattered ink, dirt, foreign matter, etc. adhering to a location other than a predetermined printing location. Of course, the size of the defect is specified to the determination circuit 11 at the time of initial setting.

Further, the defect position measuring circuit 12 is connected to the output terminals of the defect determining circuits 9 and 11, respectively. This measuring circuit 12 is composed of a first central processing unit (CPU), and measures the position of the defect in the width direction of the multicolor printed matter S when it is determined that there is a defect. be.

The #J setting of the defect position (position information) is determined by the above TV camera 2.
This is performed by counting and calculating the number of elements in the linear array image sensor from the light receiving element at the position corresponding to the origin to the light receiving element at the position corresponding to the defect. Note that the above origin is arbitrarily determined, and in the illustrated example, the origin is the camera unit 1.
One end 1a of is set as the origin, and the distance G from there to the defect f is determined by calculation based on the number of elements described above. Further, an alarm device W45 such as a buzzer or a chime is connected to the output end of this measuring circuit 12, and this device 45
is operated simultaneously with the measurement of the defect location.

A monitoring device 51 is disposed at a defect monitoring position that is set on the downstream side in the traveling direction of the multicolor printed matter S at a distance L (see FIG. 2) from the printing defect detection position. This monitoring device 51 is provided with a traverse rail 52 extending in the width direction of the multicolor printed material S, and is movable in the width direction of the multicolored printed material S using the rail 52 as a guide, and monitors to image a partial area of the printed surface. It has a color television camera 53 and a traverse mechanism (not shown) for moving this camera 53.

The color television camera 53 is always placed at the origin position, with the center in the width direction of the multicolor printed matter S being the origin. Note that the color television camera 53 is focused in advance on the printed surface at the defect monitoring position by an automatic focusing mechanism, and this camera 53 has a zoom function, so that it can be adjusted as necessary by operating an operation panel (not shown). It is possible to zoom in on the part you want. Furthermore, a strobe light emitter (not shown) is attached to the side of the color television camera 53, and when the light emitter emits strobe light, the color television camera 53 can instantaneously take an image through a shutter. ing.

When the traverse mechanism connected to the other output end of the defect position measuring circuit 12 is supplied with the position information of the defect f, the traverse mechanism moves the color of the defect f to a scheduled position through which the defect f passes based on the position information. The television camera 53 is moved and placed on standby.

Further, a color still image display device 55 is connected to the other output terminal of the defect position measuring circuit 12.

This display device 55 includes a color still image control circuit 56 and an R
It includes a GB memory 57 and a television monitor 58.

The RGB memory 57 is connected to the output end of the color TV camera 53 and stores R (red), G (green), and B (
This is to accumulate color component signals of (blue). The color still image control circuit 56 connected to the other output end of the defect position measuring circuit 12 is comprised of a second central processing unit (CPU).

This control circuit 56 controls R based on the input of the position information.
When the GB memory 57 receives the video signal from the camera 53, the RGB memory 57 is operated to create a color still image, and one screen worth of video stored in the RBG memory 57 is displayed on the TV monitor 58. This controls the display of information as a color still image.

In addition, 61 in FIGS. 1 and 2 is a pulse generator, and this is provided in rolling contact with the edge of the multicolor printed matter S passing through the guide roller 62 on the starting end side of the inspection line. The output of this pulse generator 61 is supplied to each mask pattern memory 16, 22 and each defect determination circuit 9.11, and based on this output, the defect detection device 5 is activated in synchronization with the line speed of the multicolor printed matter S. It is now working.

Next, a case will be described in which a traveling multicolor printed matter S is inspected using the defect inspection apparatus having the above configuration.

First, after performing the necessary initial setting operations, the defect detection TV camera 2 images a print that has been determined to be non-defective through visual inspection or other appropriate inspection, and the outline extraction circuit 7 takes an image of this non-defective product (mask). After extracting the contour pattern, the extracted contour pattern is stored in the first defect recognition section 8 and the second defect recognition section 10, respectively.

After this, gravure printing is started, and the printed surfaces of the multicolor printed matter S are successively fed into the field of view of the defect detection television camera 2 and imaged. All video signals output from the television camera 2 are sent to the contour extraction circuit 7 via the AGC device 6.
Since the contour pattern to be inspected is extracted in this circuit 7, this pattern is supplied to a first defect recognition section 8 and a second defect recognition section 10, respectively.

In the first defect recognition section 8 , the contour pattern to be inspected outputted from the contour extraction circuit 7 is enlarged by a first pattern enlargement processing circuit 15 . The resulting pattern to be inspected is supplied to a first pattern matching circuit core.

The inputting of the pattern to this circuit 17 and the reading of the mask contour pattern related to the mask image from the first mask pattern memory 16 to the first pattern matching circuit 17 are performed at the same timing, so that both Compare and match patterns.

Then, if the pattern to be inspected has a particular defect, a part of the contour pattern related to the mask image protrudes from the enlarged pattern to be inspected. This protruding part is recognized as information about sexual flaws.

Next, this defect information is supplied to the first defect determination circuit 9, so that the contour pattern to be inspected for the video signal from the camera 2 is enlarged by this circuit 9. The signal is not supplied to the second pattern matching circuit 23 as it is. The input of the contour pattern to be inspected to this circuit 23 and the readout of the mask enlarged pattern related to the mask image from the second mask pattern memory 22 to the second pattern matching circuit 23 are performed at the same timing. is executed, thereby comparing and matching both patterns.

Therefore, if the pattern to be inspected has a defect in flyability, a part of the contour pattern to be inspected protrudes from the mask enlarged pattern.

This protruding part is recognized as information about a defect in flight performance. This defect information is then supplied to the second defect determination circuit 11, which determines whether or not the defect information is a defect.

The defect information detected as described above is supplied to the defect position measuring circuit 12. Then, this circuit 12 controls the multicolor printed matter S with respect to the origin 1a of the detected defect.
The position in the width direction, that is, the distance G in Fig. 2, is measured by counting and calculating the number of elements from the light receiving element at the position corresponding to the origin of the linear array image sensor of the camera 2 to the light receiving element at the position corresponding to the defect. do. Furthermore, based on the measurement of this defect position, the defect position measuring circuit 12 determines the position of the notifying device 4.
5 is operated to notify the operator of the detection of a defect by its sound or the like.

Then, the position information of the detected defect is supplied to the monitoring device 51. Therefore, the monitoring device 51 operates based on the supplied position information, and moves the monitoring color television camera 53 from its origin position until the defect f reaches the scheduled position where the defect f passes in the defect monitoring position. The camera 53 waits at the scheduled position.

Immediately after this, when the defect f detected by the defect detection device 5 is moved to the scheduled position in the defect monitoring position by moving the distance ML shown in FIG. The color television camera 53, which has been moved to a position where it can be seen and is on standby, is operated at the correct timing to instantaneously image a predetermined area including the defect f under strobe light emission.

A color video signal from this monitoring color television camera 53 is supplied to a color still image display device 55. Then, by the control operation of the color still image control circuit 56, which is operated in synchronization with the timing of receiving the defect position information from the defect position measuring circuit 12, the color video signal obtained by imaging is divided into three colors of R, G, and B. Disassemble RGB memory 5
At the same time, this accumulated color video information is displayed on a television monitor 58 as a color still image.

As described above, each time the defect detection device 5 automatically detects a defect f while the multicolor printed matter S is traveling, a color still image of a predetermined area including the defect f can be monitored via the television monitor 58. .

Therefore, not only can the defect f be automatically detected, but also the detected defect f can be reliably seen in a color still image. Therefore, by monitoring the detected defect f, it is possible to know the shape symptoms of the defect, such as what color the defect is and what type it is.
Accordingly, the operator can take appropriate measures to avoid defects. Of course, as described above, since the notifying device 45 operates in accordance with the detection of a defect, the operator does not need to continuously watch the television monitor 58, but only needs to watch each time the above-mentioned notification is issued, reducing the workload.

Moreover, since the monitoring color television camera 53 of the monitoring device 51 moves in the width direction of the multicolor print S with the center position in the width direction of the multicolor print S as its origin, this camera 53 moves at the edge of the multicolor print S. It is possible to shorten the time required to reach the position where the image of the part is to be imaged. Therefore, the distance ML from the defect detection position to the defect monitoring position, that is, the line length required for defect inspection, can be shortened.

[Effects of the Invention] According to the defect inspection method and apparatus of the present invention configured as described above, it is possible not only to automatically detect defects in multi-colored printed matter while it is running, but also to be able to reliably detect the defects each time it is detected. Since it is possible to monitor the shape and symptoms of detected defects using color still images, it is possible to improve the reliability and efficiency of defect inspection for multicolor printed matter. In addition, in a defect inspection apparatus in which the origin of the monitoring color television camera is located at the center in the width direction of the multicolor printed matter, the line length required for defect inspection can be shortened.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a diagram for explaining the configuration of a defect inspection device that implements the method of the present invention, and FIG.
The figure is a schematic plan view of a defect inspection line. 2... Television camera for defect detection, 5... Defect detection device, 51... Monitoring device, 55... Color still image display device, 58... Television monitor, S... Multicolor printed matter,
f... Defective applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] 1. A television camera for detecting defects with a linear array image sensor as a light receiving part, which images a running continuous long multicolored printed matter over its entire width, and receives the video signal from the television camera. When it is determined that there is a defect during printing, the position of this defect in the width direction of the multicolor print is measured, and the defect detection television is processed. A color television camera for monitoring, which is movable in the width direction of the multicolored printed material, is installed at a defect monitoring position downstream in the running direction of the multicolored printed material from the printing defect detection position where the camera is placed. The defect is moved to a scheduled position where the defect passes based on the position information, the camera captures an image of a predetermined area including the defect when the defect passes through the planned position, and the video signal from the monitoring color television camera is captured. A method for inspecting defects in multicolor printed matter, characterized by displaying it on a television monitor as a color still image. 2. A television camera for defect detection whose light receiving part is a linear array image sensor that is placed at a print defect detection position determined at an arbitrary position and captures an image of a running continuous long multicolored printed matter in its entire width direction; A video signal from a television camera is supplied, and this video signal is processed to determine the quality of printing of the multicolor printed matter, and when it is determined that there is a defect during the printing,
a defect detection device for measuring the position of this defect in the width direction of the multicolor printed matter; A monitoring color television camera is provided that is always located at the center of the printed matter in the width direction and is movable in the width direction of the multicolored printed matter with this position as the origin, and the defect detection device The position information of the defect is supplied, and based on this position information, the monitoring color television camera is moved and placed at a predetermined position where the defect passes, and the camera detects the defect when the defect passes through the predetermined position. and a color still image display device that displays a video signal from the monitoring color television camera on a television monitor as a color still image. Inspection equipment.