JP2002162363A - Meandering tracking system for error detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a meandering tracking system for an error detector which exactly can detect side edges of an inspected object to accurately track along meandering of the inspected object without being affected by any background condition of an image data reading position. SOLUTION: The meandering tracking system for an error detector 1 is characteristically provided with an image data generation means 4 scanning an inspected object 2 to be carried orthogonally with a traveling direction A to obtain an image data, a side edge detecting means 10 making side edge detection of the inspected object from the beginning position located on the inspected object through widthwise outward direction, based on the image data, an inspection area setting means 12 setting widthwise inner direction of the detected side edge as the inspection area and widthwise outward direction as the non-inspection area, and a threshold setting means 14 setting different threshold for each of the inspection area and non-inspection area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a meandering tracking device for a defect detection device, and more particularly, to a device for detecting a defect of a conveyed inspection object, detecting the meandering of the inspection object and following the meandering. The present invention relates to a meandering follow-up device for a defect detection device capable of executing the detected defect detection.

[0002]

2. Description of the Related Art Conveyed sheets, films, nonwoven fabrics,
2. Description of the Related Art A defect detection device that detects a defect of a long object such as a metal foil is known. Because long objects may meander during transportation, defect detection devices for detecting defects on long objects include:
It is required to follow the meandering.
A meandering tracking device as described in JP 132966 has been proposed. This apparatus detects a boundary between an inspection target and a background, that is, a position of a side edge of the inspection target by a line image sensor that scans a long detection target in a width direction, and determines this position. The meandering state of the test object is detected by comparing with the position of the side edge detected in a state where the test object is not meandering, and the inspection area is changed to match the meandering state. .

[0003]

In this meandering tracking device, a side image is detected by detecting a change in the image data from one end of the image data by the line image sensor toward the inside in the width direction of the inspection object. Is performed. That is, a change in image data is detected from the background position outside the width direction of the long inspection object toward the center in the width direction of the inspection object, and the position where the value of the image data greatly changes is detected. It is determined to be a side edge.

Here, since the image reading position at which the line image sensor or the like obtains the image data must be a position where the long object to be inspected is stably conveyed, the roller for conveying the inspected object is required. Set above. Since this roller is formed of a material such as metal or rubber, the surface may be scratched or stained due to use.

For this reason, the image data generated by the line image sensor may include a portion where the value of the image data fluctuates due to scratches and dirt on the background portion outside the width direction of the inspection object. . Therefore, when the detection of the side edge from the background portion on the outer side in the width direction of the long inspection object toward the center in the width direction of the inspection object, image data due to scratches, dirt, etc. on the roller surface is obtained. Is erroneously recognized as a change caused by the side edge of the inspection object, and the position of the side edge cannot be detected accurately. As a result, a problem arises in that the meandering of the inspection object cannot be accurately followed. Such a problem can occur not only due to a flaw on the roller surface, but also due to a flaw in the background portion at the position where the image data is read.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and accurately detects a side edge of an inspection object without being affected by a background state of a position where image data is read, and meanders the inspection object. It is an object of the present invention to provide a meandering follow-up device for a defect detection device, which can follow the object accurately.

[0007]

According to the present invention, there is provided an image data generating means for scanning an object to be conveyed in a direction perpendicular to a conveying direction to obtain image data, and the inspection based on the image data. A side edge detecting means for detecting a side edge of the inspection object from the start position located on the object outward in the width direction, and an inner side in the width direction of the detected side edge is detected in the inspection area. Inspection area setting means for setting the outer side in the width direction of the set side edge as a non-inspection area, and threshold value setting means for setting different threshold values for each of the inspection area and the non-inspection area. Meandering device for a defect detection device.

According to the meandering follow-up device for a defect detection device having such a configuration, the detection of the side edge is performed outward from the center of the inspection object, so that the background state of the inspection object is affected. Without this, accurate side edge detection is performed.

According to a preferred aspect of the present invention, the side edge detecting means detects a side edge toward both sides in the width direction of the inspection object.

According to such a configuration, since the positions of both side edges of the inspection object can be accurately detected, not only the meandering state but also the width of the inspection object at the inspection position can be accurately grasped. It is also possible to detect abnormalities such as kinking of objects.

According to another preferred aspect of the present invention, the side edge detecting means detects a side edge based on image data obtained by averaging a plurality of the image data.

According to such a configuration, fluctuations in image data due to scratches, dirt, and the like on the inspection object disappear or decrease due to averaging. Is not determined to have a side edge.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a drawing showing a schematic configuration of a meandering tracking device 1 for a defect detection device according to a preferred embodiment of the present invention. The meandering tracking device 1 is a sheet-like web 2 that is a long test object that is continuously conveyed.
, That is, a shift in a direction orthogonal to the transport direction indicated by the arrow A, and sets an inspection range corresponding to the meandering. The web 2 is a long sheet-like material such as a sheet, a film, a nonwoven fabric, and a metal foil. In addition, the inspection object of the present invention is not limited to such a sheet-like long object, and may be a cut sample such as a glass plate or a resin plate. It is particularly suitable for inspecting a long sheet-like object to be conveyed.

As shown in FIG. 1, the meandering tracking device 1 includes a line CCD camera 4 which is image data generating means for obtaining image data by scanning in a direction orthogonal to the transport direction. The line CCD camera 4 is arranged at a position above the roller 6 that conveys the web 2, and is configured to generate image data on a scanning line 8 indicated by a dotted line along the longitudinal axis of the roller 6. The length of the scanning line 8 is set to be sufficiently longer than the width of the web 2 so as to be able to cope with a deviation (meandering) of the web in any of the left and right directions. Therefore, the image data generated by the line CCD camera 4 has image data from the web 2 at the center and image data from the surface of the roller 6 at both ends.

The meandering tracking device 1 further includes a line CCD
A side edge detecting unit 10 for detecting a side edge of the web 2 based on image data generated by the camera 4 is provided. The side edge detecting means 10 records the image data generated by the line CCD camera 4 in a memory, and records the image data of the web 2 from a portion corresponding to the center in the width direction of the web 2 to a portion corresponding to the outside in the width direction. Detect side edges. Specifically, the value of each pixel of the image data recorded in the memory is sequentially compared with a predetermined value, and the position where the value of the recorded image data exceeds or falls below the predetermined value is determined by the side edge ( Edge). This decision method includes background,
If the output of the detection target is stable, there is an advantage that the side edge (edge) can be accurately detected even if there is some blur.

Further, the side edge determination is not limited to this method, and any method may be used as long as the side edge is detected outward from the start position located on the web in the width direction. But it is good. For example, the determination may be based on a difference value between images separated by a predetermined distance. In this method, if the size of the image data at the side edge changes to some extent, the output level from the web fluctuates. Also, there is an advantage that the side edge can be accurately detected.

The image data used by the side edge detecting means 10 is preferably obtained by averaging a plurality of image data generated by the line CCD camera 4 with a time lag. The use of the data averaged in this way eliminates the influence of changes in image data due to scratches, stains, etc. on the web 2, formation defects, granular defects, and the like. Further, by performing a smoothing process such as a moving average in the element direction, it is possible to prevent the influence when the image data includes a linear defect.

The meandering tracking device 1 further includes an inspection area setting means 12 for setting an inner side in the width direction of the detected side edge as an inspection area and an outer side in the width direction of the detected side edge as a non-inspection area.
And threshold setting means 14 for setting different thresholds for each of the inspection area and the non-inspection area.
Since different thresholds are set with the detected side edge as a boundary, the inspection area where defect detection is performed is arranged corresponding to the meandering of the web. In this way, the inspection of the web 2 is performed by a known method in the inspection area arranged corresponding to the meandering of the web.

Next, another preferred embodiment of the present invention will be described in detail with reference to FIGS. FIG. 2 is a diagram showing a schematic configuration of a defect detection device 20 including a meandering tracking device according to a preferred embodiment of the present invention, and FIG.
6 is a flowchart showing a meandering tracking processing operation performed in the defect detection device 20 of FIG.

As shown in FIG. 2, the defect detection device 20 includes a line CCD camera 22 used as a line image sensor, an image processing device 24, and a host computer 26. The image processing device 24
/ D converter 28, comparator 30, run length circuit 32, reference value memory 34, and first memory used alternately for writing and reading of a bright defect detection threshold and a dark defect detection threshold. A threshold memory 36A and a second threshold memory 36B, a first run-length buffer 38A and a second run-length buffer 38B,
I / O interface 4 for transmitting and receiving data between AM 40, CPU 42, and host computer 26
4 is provided.

In the above embodiment and the present embodiment, only one set of the line CCD cameras 4 and 22 and the corresponding image processing device and the like are provided. However, usually, the line CCD cameras 4 and 22 correspond to the width of the inspection object and the resolution of the camera. In addition, a plurality of line CCD cameras and corresponding image processing devices are provided. As the line CCD cameras 4 and 22, for example, the number of pixels is 1
024-7450 line CCD cameras are used.
If the width of the inspection object is 2400 mm, the line CCD camera is 5000 pixels, the resolution is 0.1 mm / pixel, and the overlapping range of the adjacent cameras is about 20 mm, 5 lines C
A CD camera is required.

The threshold memories 36A and 36B store 8 bits / bit for binarizing the output of the line CCD camera 22.
In the pixel memory, when writing to one threshold memory is performed, the other threshold value is read from the other and the operation of performing the binarization process is performed alternately. By doing so, continuous inspection is possible. Also, when detecting both bright and dark defects simultaneously,
Each series has a capacity of two rows.

Data is written in the threshold memories 36A and 36B following the meandering of the web to be inspected. The threshold value of the actual inspection area where the inspection is performed is a predetermined value A
Then, the threshold value of the non-inspection area where the inspection is not performed is set to a predetermined value B. Here, the predetermined value A is a threshold value for detecting a defect to be detected on the inspection target, and is a predetermined fixed value or a value of a predetermined ratio to the output of the background. The value of A is appropriately changed depending on the content of the defect to be detected.

The predetermined value B is a threshold value for preventing any value of the image data from being detected as a defect. The threshold value memory 36A of 8 bits / pixel,
When 36B is used, the value is set to 255 when a bright defect is detected, and set to 0 when a dark defect is detected.

The means for detecting the side edge of the web to be inspected based on the output signal from the line CCD camera 22, ie, the image data, includes a reference value memory 34 and a CPU 42.
The image data from the line CCD camera 22 is recorded in the reference value memory 34, and the side edge of the web is moved from the portion corresponding to the central portion in the width direction of the web to the portion corresponding to the outer side in the width direction. Detect. Specifically, the value of each pixel of the image data recorded in the reference value memory 34 is sequentially compared with a predetermined value, and the position where the value of the recorded image data exceeds or falls below the predetermined value is determined. It is determined to be a side edge. This decision method includes background,
If the output of the detection target is stable, there is an advantage that the side edge (edge) can be accurately detected even if there is some blur.

The side edge determination is not limited to this method, and any method may be used as long as the side edge is detected outward from the start position on the web in the width direction. . For example, the determination may be based on a difference value between images separated by a predetermined distance. In this method, if the size of the image data at the side edge changes to some extent, the output level from the web fluctuates. Also, there is an advantage that the side edge can be accurately detected. It is preferable to determine which method is adopted depending on the state of the side edge of the web.

The position (ie, edge coordinates) of the side edge thus detected is transferred to the host computer 26 through the I / O interface 44, and the position and width of the side edge to be inspected are determined. And CPU4
2 is the first based on the position and width of the side edge to be inspected.
And the second threshold memories 36A and 36B are updated. Therefore, in this embodiment, the inspection area setting means and the threshold setting means are constituted by the CPU 42, the first and second threshold memories 36A and 36B, and the like.

In this embodiment, in the case of detecting a bright defect, the threshold value is set so that the output of the comparator 30 for an area having an output level larger than the threshold value set in the threshold value memory becomes "1". In the case of dark defect detection, the comparator 3 for an area having an output level smaller than the threshold value set in the threshold value memory
The threshold is set so that the output of 0 becomes “1”.

Therefore, the area corresponding to the defective part is "1" and the area corresponding to the normal part is "1" by the comparator 30.
This binary data by the comparator 30 is run-length encoded by a run-length encoding circuit 32 that obtains a transition point address from "0" to "1" or from "1" to "0". Run-length buffer 3
8A and 38B.

The run-length code obtained by the run-length encoding circuit 32 is temporarily stored in two systems of run-length buffers 38A and 38B. The run-length codes temporarily stored in the run-length buffers 38A and 38B are alternately used by the CPU 40 to execute the connectivity processing. The connectivity processing refers to processing while comparing data in a plurality of continuous scan lines between the lines. By performing this connectivity processing, defects can be recognized and morphological characteristics can be measured.

Next, the procedure of the side edge detection processing performed by the defect detection device 20 will be described with reference to the flowchart of FIG. First, in step S1, image data from the line CCD camera 22 is input to the image processing device 24, and then, in step S2, preprocessing of the image data is performed.
In the pre-processing, the image data of a plurality of lines from the line CCD camera 22 are averaged to prevent variations due to the influence of formation defects and granular defects. Further, by performing a smoothing process such as a moving average in the element direction, it is possible to prevent the effect when the image data includes a linear defect.

Next, in step S3, a start position of side edge detection is set. This start position is a position corresponding to the center of the web to be inspected. Step S4
Then, a side edge is detected from the start position set in step S3 toward one side edge of the web to be inspected. Next, in step S5, a side edge is detected from the start position set in step S3 toward the other side edge of the web to be inspected. Next, in step S6,
The inspection width is set based on the detected positions of both side edges,
Further, in step S7, the threshold memories 36A and 36B
Is updated.

FIGS. 4 to 6 are diagrams showing examples of detecting the side edges of the web by the meandering tracking device of the above embodiment. The roller on the scanning line 8 has a flaw F, and the meandering web has a dirt (defect) X (FIG. 4). At this time, flaws F and dirt X appear in the output value from the line CCD camera 22 (FIG. 5). However, the image data in the reference value memory 34 (FIG. 6), which is a value obtained by averaging the image data of a plurality of lines from the line CCD camera, has a drop in the output corresponding to the dirt X on the transported web. Not appearing. Therefore, based on the output value of the reference value memory 34, the side edge of the web is detected from the start point on the web toward the outside (side edge) in the width direction, so that the roller on the outer side in the width direction of the web is detected. It can be seen that the side edge can be detected without being affected by the flaw.

In the present invention, the generation of image data by the line CCD cameras 4 and 22 may use either reflected light or transmitted light from the inspection object according to the inspection object.

The present invention is not limited to the above-described embodiment, and various changes and modifications can be made within the scope of the claims.

[0036]

As described above, according to the present invention, the image data can be read without being affected by the background state at the reading position.
Provided is a meandering tracking device that can accurately detect a side edge of a long inspection object and accurately follow the meandering of the inspection object.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a meandering tracking device for a defect detection device according to a preferred embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of a defect detection device including a meandering tracking device according to another preferred embodiment of the present invention.

FIG. 3 is a flowchart showing a meandering tracking processing operation performed in the defect detection device of FIG. 2;

FIG. 4 is a diagram illustrating scan lines and defects on the web for explaining an example of detecting a side edge of the web by the meandering tracking apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating an output value from a line CCD camera for explaining an example of detecting a side edge of a web by the meandering tracking device according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating values of image data in a reference value memory for explaining an example of detecting a side edge of a web by the meandering tracking device according to the embodiment of the present invention.

[Explanation of symbols]

 1: meandering follower 2: web 4: line CCD camera (image data generating means) 6: roller 8: scanning line 10: side edge detecting means 12: inspection area setting means 14: threshold setting means

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2F065 AA13 AA49 BB01 CC02 DD13 FF04 JJ25 PP15 QQ04 QQ24 QQ25 QQ42 UU05 2G051 AA32 AA37 AB07 AC21 CA03 CB01 CD04 DA06 EA11 EA14 EB01 EB02 EC03 EB01 CB01 A02CB02

Claims (3)

[Claims] An image data generating unit that obtains image data by scanning a conveyed inspection object in a direction orthogonal to a conveyance direction; and a start position that is located on the inspection object based on the image data. A side edge detecting means for detecting a side edge of the object to be inspected outward in the width direction; an inner side of the detected side edge in the width direction as an inspection area; and an outer side of the detected side edge in the width direction. A defect detection apparatus comprising: an inspection area setting means for setting a side as a non-inspection area; and a threshold value setting means for setting different thresholds for each of the inspection area and the non-inspection area. Meandering follower. 2. The meandering follow-up device for a defect detection device according to claim 1, wherein said side edge detection means detects a side edge toward both sides in the width direction of the inspection object. 3. The meandering follow-up device for a defect detection device according to claim 1, wherein the side edge detection means performs the side edge detection based on image data obtained by averaging a plurality of the image data.