JP2002365225A - Method and apparatus for inspecting sheet material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method and apparatus of a sheet material for easily detecting wrinkles without any need for patrolling work by a human when detecting the wrinkles being generated when winding up the sheet material in a roll. SOLUTION: As the method for detecting wrinkles S being generated when winding up the sheet material 2 in a roll, light is applied to a roll 3 of the sheet material 2 from either of light sources 4A and 4B, and at the same time the image of the roll 3 is picked up by using a camera 5 where visual field width has been set to a range of 50-500 mm, and the wrinkles S are detected based on the reflection light from the roll 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting wrinkles generated when a sheet material is wound into a roll, and more particularly to a method and apparatus for detecting wrinkles without manual patrol. The present invention relates to a method and an apparatus for inspecting a sheet material.

[0002]

2. Description of the Related Art In general, when a sheet material made of synthetic resin is manufactured, the sheet material is stretched from a raw material obtained by extruding a raw material resin, and the sheet material is divided by a slitter and continuously rolled. It is wound up in a shape. However, wrinkles may be formed on the rolls during winding of the sheet material, and the rolls having such wrinkles need to be detected as defective products.

However, the traces of the wrinkles gradually disappear with continuous winding of the sheet material, and it is extremely difficult to inspect the appearance of the roll at the end of the winding. It is necessary to constantly monitor the winding state of the roll while turning. For this reason, at present, the worker checks the winding state of the roll by patrol every few minutes, for example.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to detect wrinkles generated when a sheet material is rolled up in a roll shape, and it is possible to easily detect wrinkles without manual patrol work. It is an object of the present invention to provide a method and an apparatus for inspecting a sheet material.

[0005]

In order to achieve the above object, a sheet material inspection method according to the present invention is a method for detecting wrinkles generated when a sheet material is wound up in a roll shape. Irradiating the roll with light, capturing an image of the roll using a camera having a field of view set in a range of 50 to 500 mm, and detecting wrinkles based on reflected light from the roll. It is.

[0006] By setting the field of view of the camera narrow and thus increasing the resolution of the image, it becomes possible to detect wrinkles using the reflected light from the rolls. This makes it possible to easily detect wrinkles without involving the traveling work. In order to perform the inspection over the entire width of the roll using a camera having a narrow field of view as described above, it is possible to use a plurality of cameras. However, from the viewpoint of equipment cost, if one camera is used for each roll, good. Therefore, it is preferable to swing the camera around an axis perpendicular to the plane including the rotation axis of the roll and the line of sight of the camera, and to switch the line of sight of the camera along the axial direction of the roll. Also, the line of sight of the camera can be changed by moving the camera and the illumination parallel to the rotation axis of the roll.

It is preferable that the camera has an autofocus function. In other words, when the sheet material is wound in a roll shape, the outer diameter of the roll gradually increases, and the roll becomes thicker. Therefore, in order to reliably detect wrinkles, the focal length automatically changes in accordance with the thicker roll. Is required.

When utilizing reflected light for detecting wrinkles, it is preferable to always irradiate the roll with light from behind the camera. That is, when light is irradiated from the rear of the camera, the reflected light of the portion having no wrinkles on the roll hardly enters the camera, and the reflected light of the wrinkled portion mainly enters the camera. Therefore, it is possible to more clearly capture the abnormal reflection caused by wrinkles.

As means for distinguishing abnormal reflection and noise caused by wrinkles in a camera image and for reliably determining the occurrence of wrinkles, wrinkles are determined based on at least one of the aspect ratio and the inclination angle of a streak-like abnormal reflection area. Should be determined. Usually, the wrinkles generated on the roll extend in the roll circumferential direction, so that the presence of the wrinkles can be specified based on the aspect ratio and the inclination angle of the streaky abnormal reflection area. In addition, a fine noise can be removed by determining the area of the streak portion and determining only an area having a certain area or more as a wrinkle.

When the roll to be inspected is a synthetic resin sheet, an air layer is formed in the gap between the wound sheet and the sheet, and this air layer may cause interference fringes on the roll surface. When the roll is imaged with a monochrome camera and the detection sensitivity is increased to detect fine wrinkles and wrinkle determination is performed,
A grayscale image due to interference fringes may be erroneously determined as a wrinkle.

In order to prevent such erroneous determination, it is preferable to use a color camera as a camera and detect wrinkles using a color image of a roll. The roll is imaged with a color camera, and the obtained color image is separated into three primary colors. The three primary colors are usually R (red), G (green), and B (blue), but may be separated into magenta, cyan, yellow, and the like. If wrinkles are determined using only one of the three primary color images thus decomposed, the image due to the interference fringes is faint, and it is easy to accurately determine wrinkles. In particular, by performing wrinkle determination from a green image, it is possible to determine wrinkles without being affected by interference fringes, which is preferable.

[0012] Interference is a phenomenon in which light reflected from the upper surface and the lower surface of the air layer is strengthened or weakened at a specific wavelength in accordance with the thickness of the air layer. Interference fringes occur due to subtle changes depending on the position. Normally, the thickness of the air layer between the film layers is 0.2 to 0.3 μm. If the thickness of the air layer changes within this range, the intensity of the blue component and the red component greatly changes due to interference, while the intensity of the green component changes. Change is 1/2 of that
Less than the following.

Since the change of the green component contained in the interference fringe generated in the air layer of 0.2 to 0.3 μm is smaller than the change of the other blue and red components, wrinkles are detected from the green image. This makes it possible to determine wrinkles that are not easily affected by interference fringes.

On the other hand, a sheet material inspection apparatus according to the present invention is an apparatus for detecting wrinkles generated when a sheet material is wound into a roll, comprising: a light source for irradiating light to the roll of the sheet material; A camera for imaging the roll is provided, and a field of view of the camera is set in a range of 50 to 500 mm.

In the above inspection apparatus, a rotation mechanism for swinging the camera is provided around an axis perpendicular to a plane including the rotation axis of the roll and the line of sight of the camera, and the line of sight of the camera is set along the axial direction of the roll. It is preferable to switch between them. Further, it is preferable to provide a determination unit that detects at least one of the aspect ratio and the inclination angle of the streaky abnormal reflection area from the image of the camera, and determines the occurrence of wrinkles based on the detected value.

According to the present invention, in the method for manufacturing a sheet material in which the sheet material is stretched and the sheet material is continuously wound into a roll, the above-described method for inspecting the sheet material is carried out. It is possible to minimize the amount of non-defective products.

Examples of the sheet material in the present invention include a film, a sheet, a web, and the like. In particular, a synthetic resin film from which clear reflected light can be obtained is preferable.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 and 2 show a sheet inspection apparatus according to an embodiment of the present invention. As shown in FIGS. 1 and 2, a roll 3 formed by winding a sheet material 2 is formed on the outer peripheral surface of a core material 1 that can be driven to rotate. At a position facing the outer peripheral surface of the roll 3, a pair of left and right light sources 4A and 4B for irradiating the roll 3 with light and a camera 5 for imaging a light-irradiated portion of the roll 3 are arranged. The camera 5 is a CCD camera having an autofocus function, and has a visual field width of 50 to 500 mm on the outer peripheral surface of the roll.
, More preferably in the range of 50 to 200 mm. If the visual field width is too narrow, the efficiency of wrinkle detection with respect to the entire width of the roll is deteriorated. Conversely, if the visual field width is too wide, the resolution of the image is reduced and wrinkle detection becomes difficult.

The camera 5 swings around an axis perpendicular to a plane including the rotation axis 3a of the roll 3 and the line of sight 5a of the camera 5 based on driving of a rotation mechanism 6 having a pulse motor or the like. It has become. Therefore, the line of sight 5 a of the camera 5 can be switched along the axial direction of the roll 3. Note that the camera 5 is a color camera, and can capture either a color image or a monochrome image. The image of the camera 5 is displayed on a monitor 7 and input to a computer 8.

The computer 8 binarizes the image data of the camera 5 according to the light intensity to generate processed image data. The processed image is displayed on the display device 9,
It is stored in a storage device in the computer 8 as needed. The computer 8 controls an operation state and a swing operation of the camera 5. The computer 8 also controls the light sources 4A, 4A according to the swing direction of the camera 5.
B so that either one of them is turned on.
Is controlled. That is, one of the light sources 4A and 4B located behind the camera 5 is selectively turned on.

When an inspection is performed using the above-described inspection apparatus, when the sheet material 2 is wound into a roll, the light sources 4A,
4B, the roll 3 is irradiated with light, and the roll 3 is imaged using the camera 5 having a narrow field of view. At this time, the reflected light of the portion where the roll 3 has no wrinkle hardly enters the camera 5, and only the reflected light of the portion of the wrinkle S enters the camera 5. Therefore, it is possible to easily detect the wrinkles S only by confirming the abnormal reflection caused by the wrinkles S without involving the patrol work by hand.

After the inspection at an arbitrary position in the axial direction of the roll 3 is completed, the line of sight 5 a of the camera 5 is switched along the axial direction of the roll 3 by driving the rotating mechanism 6. By sequentially moving the imaging position along the axial direction of the roll 3, an inspection can be performed over the entire width of the roll. Since the trace of the wrinkles S gradually disappears with the continuous winding of the sheet material 2, the camera 5
Is preferably set to 1 to 5 minutes.

Since the camera 5 has an autofocus function, the wrinkles S can be reliably detected even if the roll 3 becomes thicker as the sheet material 2 is wound. When the autofocus function does not function sufficiently, the focal length may be adjusted at the edge of the roll 3 in the axial direction, and the focal length between the edges may be calculated.

FIGS. 3 to 5 show processed images obtained by binarizing the raw image of the camera, where X indicates the roll axis direction and Y indicates the roll circumferential direction. As shown in FIG. 3, when the raw image of the camera is binarized, a streak-like abnormal reflection area caused by a wrinkle S extending in the roll circumferential direction Y and a band-like abnormal reflection area caused by a disturbance spreading in the roll axis direction X are obtained. A clear processed image D is obtained.

FIG. 4 shows a result obtained by binarizing a monochrome image obtained from a roll on which interference fringes appear and determining wrinkles.
In addition to the wrinkles S, the interference fringes are erroneously determined as wrinkles. On the other hand, FIG.
Indicates that a color image of the same roll is separated into three primary colors, and only the green image is binarized to determine wrinkles. Only the wrinkles S are detected without detecting the interference fringes.

The occurrence of the wrinkles S can be visually confirmed on the monitor 7 or the display device 9, but can be automatically determined by software installed in the computer 8.

That is, the computer 8 discriminates abnormal reflection and noise caused by wrinkles S in the raw image of the camera 5 and determines whether or not the wrinkles S are generated. A determination unit that detects at least one of the ratio and the inclination angle and determines the occurrence of wrinkles S based on the detected value is mounted.

In the determination means, as shown in FIG. 4, an ellipse C containing a streak-like abnormal reflection area is created, and an aspect ratio (H / W) obtained from its width W and height H is obtained. What is necessary is just to compare this aspect ratio with a preset threshold value. For example, H /
W ≧ 5 may be used as a criterion for determining wrinkles S. Further, as shown in FIG. 5, an ellipse C containing a streak-like abnormal reflection area is created, and its major axis L is inclined at an angle θ with respect to the roll axis direction X.
May be obtained, and this inclination angle θ may be compared with a preset threshold value. For example, 60 ° ≦ θ ≦ 120 ° may be used as a criterion for determining wrinkles S. These aspect ratios and inclination angles can be used alone or in combination as criteria.

Although it is sufficiently possible to distinguish abnormal reflection and noise caused by the wrinkles S as described above, in order to further improve the detection accuracy of the wrinkles, the area around the roll may be covered with a light shielding curtain or the like. It is desirable to minimize the effects of disturbance.

FIGS. 6 and 7 show a sheet inspection apparatus according to another embodiment of the present invention. In the present embodiment, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description of those portions is omitted.

As shown in FIGS. 6 and 7, a roll 3 formed by winding a sheet material 2 is formed on the outer peripheral surface of a rotatable core material 1. At a position facing the outer peripheral surface of the roll 3, a light source 4 for irradiating the roll 3 with light and a camera 5 for imaging the light-irradiated portion of the roll 3 are arranged. The camera 5 swings around an axis perpendicular to a plane including the rotation axis 3a of the roll 3 and the line of sight 5a of the camera 5 based on driving of a rotation mechanism 6 including a pulse motor or the like. ing. The image of the camera 5 is displayed on the monitor 7
And is recorded on the VCR 11.

When the inspection is performed using the above-described inspection apparatus, when the sheet material 2 is wound into a roll, the light source 4 irradiates the roll 3 with light and the camera 5 having a narrow field of view is used. The roll 3 is used to image the roll 3. At this time, the reflected light of the portion where the roll 3 has no wrinkle hardly enters the camera 5, and only the reflected light of the portion of the wrinkle S enters the camera 5. Therefore, by checking the abnormal reflection caused by the wrinkles S on the monitor 7, it is possible to easily detect the wrinkles S without involving the patrol work by hand.

FIG. 8 exemplifies a sheet material manufacturing apparatus which preferably uses the above-described inspection apparatus. This sheet material manufacturing apparatus includes an extruder 21, a gear pump 22, a filter 23, a base 24, a cooling roll 25, a vertical stretching machine 27, a horizontal stretching machine 28, a thickness gauge 29, and a winder 30.
And a thickness gauge 2 for measuring the thickness of the stretched sheet material.
9 is input to the thickness controller 32, and the thickness controller 3
2, the base 24 is controlled. The roll manufactured in the above process is slit into a small width according to the specifications of the user.

When a sheet material is continuously manufactured using the above-described manufacturing apparatus, the method of inspecting a sheet material according to the present invention can minimize the amount of defective products. Will be possible.

[0036]

As described above, according to the present invention, in a method for detecting wrinkles generated when a sheet material is wound into a roll, light is applied to the roll of the sheet material and the field width is reduced. Since the roll is imaged using a camera set in the range of 50 to 500 mm and wrinkles are detected based on the reflected light from the roll, it is possible to easily detect wrinkles without manual patrol work. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a sheet material inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a side view showing a sheet material inspection apparatus according to an embodiment of the present invention.

FIG. 3 is a view showing a processed image of a raw image of a camera.

FIG. 4 is a processed image obtained from a monochrome image in which interference fringes are erroneously determined as wrinkles.

FIG. 5 is a processed image obtained from a green image obtained by decomposing a color image and eliminating the influence of interference fringes.

FIG. 6 is a diagram for explaining a parameter (aspect ratio of a streaky abnormal reflection area) for determining wrinkles.

FIG. 7 is a diagram for explaining a parameter for determining wrinkles (the inclination angle of a streak-like abnormal reflection area).

FIG. 8 is a configuration diagram illustrating a sheet material inspection apparatus according to another embodiment of the present invention.

FIG. 9 is a side view showing a sheet material inspection apparatus according to another embodiment of the present invention.

FIG. 10 is a configuration diagram illustrating a sheet material manufacturing apparatus to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core material 2 Sheet material 3 Roll 3a Roll rotation axis 4, 4A, 4B Light source sheet 5 Camera 5a Camera line of sight 6 Rotation mechanism 7 Monitor 8 Computer 9 Display device 10 Lighting switching device 11 Video deck

Continued on the front page F-term (reference) 2F065 AA23 AA31 AA49 BB13 CC02 DD06 FF04 FF41 GG13 HH12 HH14 JJ03 JJ26 MM25 MM28 PP05 QQ04 QQ24 QQ25 QQ28 SS02 2G051 AA32 BA01 BB01 CA04 CA06 CB01 DA07 A07 DA06 A07 DA06 CA01 CA12 CE16 DB02 DB06

Claims (14)

[Claims] 1. A method for detecting wrinkles that occurs when a sheet material is wound into a roll, wherein the light is applied to the roll of the sheet material and a field width is set to 50 to 500 mm.
Image the roll using a camera set in the range of
A method for inspecting a sheet material, comprising detecting wrinkles based on reflected light from the roll. 2. The sheet inspection method according to claim 1, wherein a line of sight of the camera is switched along an axial direction of the roll. 3. The sheet material inspection method according to claim 2, wherein the camera is swung about an axis perpendicular to a plane including the rotation axis of the roll and the line of sight of the camera. 4. The sheet inspection method according to claim 1, wherein the camera has an autofocus function. 5. The sheet material inspection method according to claim 1, wherein the roll is always irradiated with light from behind a camera. 6. The sheet material according to claim 1, wherein the occurrence of wrinkles is determined based on at least one of an aspect ratio and an inclination angle of a streak-like abnormal reflection area in the image of the camera. Inspection method. 7. The sheet material inspection method according to claim 1, wherein the camera is a color camera, and wrinkles are determined based on a color image of the roll. 8. The sheet material inspection method according to claim 7, wherein the color image is separated into three primary colors, and wrinkles are determined from one of the three primary color images. 9. An apparatus for detecting wrinkles generated when winding a sheet material into a roll, comprising: a light source for irradiating light to the roll of the sheet material; and a camera for imaging the roll. An inspection apparatus for a sheet material, wherein a field of view of the camera is set in a range of 50 to 500 mm. 10. The sheet material inspection apparatus according to claim 9, wherein a line of sight of the camera is switched along an axial direction of the roll. 11. The sheet material inspection apparatus according to claim 10, further comprising a rotation mechanism that swings the camera around an axis perpendicular to a plane including the rotation axis of the roll and the line of sight of the camera. 12. A method according to claim 9, further comprising detecting at least one of an aspect ratio and an inclination angle of a streak-like abnormal reflection area from an image of the camera, and determining occurrence of wrinkles based on the detected value. The sheet material inspection apparatus according to any one of claims 11 to 13. 13. The sheet material inspection apparatus according to claim 9, wherein the camera is a color camera. 14. A sheet material subjected to the sheet material inspection method according to any one of claims 1 to 8 when the sheet material is stretched and the sheet material is continuously wound into a roll. Manufacturing method.