JP2011085520A - Defect discrimination device, defect discrimination method, and sheet-like material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defect discrimination device and a defect discrimination method capable of effectively discriminating a kind of an irregularity defect which has generated on a surface of a sheet-like material with light permeability, and a sheet-like material which has been discriminated for defect. <P>SOLUTION: The defect discrimination device includes, on a travel route of the sheet-like material with light permeability, a first irradiation means 2 irradiating the sheet-like material with parallel light, a first screen 4 projecting light through the sheet-like material from the first irradiation means, a first image means 6 imaging light projected on the first screen, a second irradiation means 3 irradiating the sheet-like material with parallel light from a position nearer to the sheet-like material than the first irradiation means, a second screen 5 disposed maintaining the same distance as that between the first irradiation means and the first screen, and a second image means 7 imaging light projected on the second screen. The kind of an irregularity defect which has generated on a surface of the sheet-like material is discriminated by comparing and checking the defect information obtained from the first image means and the defect information obtained from the second image means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a defect determination apparatus, a defect determination method, and a defect determination method, which are provided along a production line or a processing line for a light-transmitting sheet-like material, and determine the type of the unevenness of the sheet-like material in-line. It relates to the discriminated sheet.

  In recent years, quality requirements for polymer films are becoming stricter, and requirements standards for defects occurring in films are increasing year by year. Therefore, in the manufacturing process of a sheet-like material represented by a polymer film, a defect inspection of the sheet-like material is generally performed. Conventionally, defects that have been inspected include a wide variety of defects such as dust and film pieces, and other foreign materials, mixed foreign materials, and irregularities such as fish eyes, holes, and scratches. Along with this, an uneven defect having a small optical distortion with respect to a normal part is being demanded as an inspection object.

  Conventionally, as a method for detecting irregularities in a defect inspection of a light-transmitting sheet-like object, the sheet-like object is irradiated by illumination means, and the transmitted or reflected light is received by a light-receiving means such as a line sensor. Generally, a method for detecting and judging a defect based on a change in the number of defects is used.

  For example, there has been proposed a method for determining whether a defect of a sheet-like material is a concave defect or a convex defect based on a change in the amount of received light (see, for example, Patent Document 1). According to this method, it is possible to discriminate between a concave defect and a convex defect using the light refraction action by the concave and convex defect, but the concave and convex defect that does not have an abrupt shape change has a small amount of change in the amount of received light. There was room for improvement in detecting uneven defects with gradual changes.

  On the other hand, a method has been proposed in which fine irregularities on the surface shape of a sheet-like object are extracted from inspection results obtained by a plurality of illumination means and light receiving means, and colorless irregularities such as fish eyes are detected and determined (for example, patents). Reference 2). According to this method, it is possible to detect the concave / convex defect by emphasizing the lens effect of the concave / convex shape, but when there are a plurality of types of concave / convex defects in the sheet-like material, the type of each defect is distinguished. There was a need for further improvements.

  Causes of irregularities are various, such as the above-mentioned fish eye, dents caused by biting of foreign matter, streaks due to traveling rods, etc., fine curvature due to uneven shape of the molded guide body such as cast film and cast roll, The countermeasures for eliminating each uneven defect are different. However, since the above prior art cannot accurately determine the type of the concavo-convex defect, there are cases where the cause of the concavo-convex defect cannot be specified or eliminated.

  Accordingly, development and improvement of means capable of discriminating the type of irregularities on the surface of the sheet-like material are required.

JP 2009-156651 A JP 2005-351825 A

  In view of the above circumstances, the present invention provides a defect discriminating apparatus, a defect discriminating method, and a sheet-like object in which a defect is discriminated, which can effectively discriminate the type of uneven defects generated on the surface of a light-transmitting sheet-like object. For the purpose.

  As a result of intensive studies to solve the above problems, the present inventor paid attention to the fact that the lens effect of the defective portion differs depending on the shape of the defect in determining the irregularity defect generated on the surface of the light-transmitting sheet. Then, the sheet-like object is irradiated with parallel light, the light projected on a plurality of screens having different distances from the sheet-like object is received by the image pickup means, and the defect type is determined by comparing and collating the obtained defect information. By finding the method, the present invention has been completed.

  That is, the first of the present invention is the first irradiation means for irradiating the sheet-like material with parallel light on the traveling path of the light-transmitting sheet-like material, and the first irradiation means with respect to the sheet-like material surface. A first screen that is installed on the opposite side of the irradiation unit and projects light from the first irradiation unit that has passed through the sheet-like material; a first imaging unit that images the light projected on the first screen; and A light source having the same specifications as the first irradiation means, a second irradiation means for irradiating the sheet-like object with parallel light from a position closer to the sheet-like object than the first irradiation means, and the sheet-like object surface On the opposite side of the second irradiation means, the light from the second irradiation means that is installed at the same distance as the distance between the first irradiation means and the first screen and is transmitted through the sheet is projected. Second screen and the second screen A defect discriminating apparatus having a second imaging means for imaging the projected light, wherein the defect information obtained from the first imaging means and the defect information obtained from the second imaging means are compared and collated. The present invention relates to a defect discriminating apparatus characterized by discriminating the type of uneven defects generated on the surface of a sheet-like object.

  According to a preferred embodiment, in the defect determination apparatus, a shadow pattern of the concavo-convex defect projected on the first screen by the lens effect of the concavo-convex defect is photographed by the first imaging means, and the second screen is captured by the lens effect of the concavo-convex defect. The shadow pattern of the projected concavo-convex defect is photographed by the second imaging means, and the position coordinates on the surface of the sheet-like object are compared and collated among the defect information obtained by the first imaging means and the second imaging means. Thus, the present invention relates to the defect discriminating apparatus characterized by discriminating the type of the concavo-convex defect.

  A preferred embodiment relates to any one of the above-described defect discrimination apparatuses, wherein the first irradiation means and the second irradiation means are point light sources.

  In a preferred embodiment, the first irradiation unit and the second irradiation unit each include one or a plurality of lenses to make the irradiation light parallel light.

  In a preferred embodiment, the lamp used in the first irradiation unit and the second irradiation unit is an arc discharge type.

  In a preferred embodiment, the first imaging means and the second imaging means are line sensor CCD cameras.

  According to a second aspect of the present invention, using the defect determination device according to any one of the above, the type of uneven defect generated on the surface of the sheet material is determined on the travel route of the sheet material. The present invention relates to a defect determination method.

  The third aspect of the present invention relates to a sheet-like material in which the type of unevenness defect is determined using the defect determination apparatus described above.

  In the present invention, the uneven defect having a different cause of occurrence uses the fact that a difference occurs in the lens effect due to the unevenness of the defect because the defect shape is different. That is, by irradiating the light-transmitting sheet-like material including the concavo-convex defect with parallel light, only the concavo-convex defect having a large thickness change is projected on the screen having a small distance from the sheet-like material. An uneven defect having a large thickness change and an uneven defect having a small thickness change are projected onto a screen having a large distance. By imaging the projected images of both screens with the imaging means and comparing and comparing the respective defect detection information, it is possible to effectively determine the defect shape, that is, the uneven defect having a different cause of occurrence, and the light-transmitting sheet-like material. It becomes possible to determine the irregular defect stably over a long period of time.

It is a figure which shows an example of the defect inspection apparatus which concerns on the conventional embodiment. It is a figure which shows an example of the defect inspection apparatus which concerns on the conventional embodiment. It is a figure which shows an example of the defect determination method and its apparatus which concern on embodiment of this invention. It is a figure which shows an example of the defect determination method and its apparatus which concern on embodiment of this invention.

  The present invention provides a first irradiation means for irradiating the sheet-like material with parallel light on a traveling path of the light-transmitting sheet-like material, and a side opposite to the first irradiation means with respect to the sheet-like material surface. A first screen that projects light from the first irradiation means that is transmitted through the sheet-like material, a first imaging means that images light projected on the first screen, and the first irradiation means. A light source of the same specification, and a second irradiation means for irradiating the sheet-like object with parallel light from a position closer to the sheet-like object than the first irradiation means; and the second irradiation with respect to the sheet-like object surface. A second screen that is installed on the opposite side of the means and maintaining the same distance as the distance between the first irradiation means and the first screen, and projects light from the second irradiation means that has passed through the sheet-like material; , The light projected on the second screen A defect discriminating apparatus having a second imaging means for imaging, wherein the defect information obtained from the first imaging means and the defect information obtained from the second imaging means are compared and collated on the surface of the sheet-like object. The present invention relates to a defect discriminating apparatus, a defect discriminating method, and a sheet-like object in which a defect is discriminated by the defect discriminating apparatus.

  The “sheet-like material” in the present invention is a so-called sheet-like material having light transmittance and a very small scale in the thickness direction with respect to the surface direction, and the thickness and width are not particularly limited. Absent. Examples of the sheet-like material include a film, a sheet, and a thin film.

  In the present invention, “on the travel route” of the sheet-like material includes, for example, a state in which the sheet-like material is continuously conveyed in a production process such as manufacturing and processing, and is not particularly limited. .

  In the present invention, the term “concave defect” means that the ratio of the protrusion thickness and the dent depth to the sheet-like material thickness is + 25% to −25%, and the size is 50 μm to 1 cm when the defect is not continuous like a streak. Refers to a colorless defect. Further, the uneven defect having a gradual change in shape refers to those in which the ratio of the protrusion thickness and the recess depth dimension based on the sheet thickness is less than 0.2% with respect to the diameter dimension of the defect portion, An uneven defect having a sharp shape change refers to a defect having a ratio of the protrusion thickness and the dent depth dimension based on the sheet thickness to 1% or more with respect to the diameter dimension of the defect portion. Here, the colorless defect refers to a defect having the same color as the sheet-like material and having the same transparency, for example, due to a general fish eye, a dent caused by the biting of a foreign object, a traveling flaw, etc. Patterns resulting from surface shape unevenness of the molding guide body such as streaks, cast films and cast rolls are exemplified, and there are no particular limitations as long as they occur on the surface of the sheet-like material.

  In the present invention, the “lens effect” is a phenomenon in which the uneven portion of the light-transmitting sheet exhibits the same effect as the concave lens and the convex lens, and the traveling direction of the emitted light changes with respect to the incident light. Say that.

  In the present invention, “parallel light” refers to light composed of components of light beams that are not parallel to each other of light beams emitted from the light source and are more nearly parallel to the optical axis in the illumination direction, For example, the light by the parallel light generator described in Unexamined-Japanese-Patent No. 2004-28785 is mentioned.

  Hereinafter, a defect determination apparatus and a defect determination method according to the present invention will be described with reference to FIGS. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

  FIG. 1 is a schematic diagram showing a schematic configuration of a conventional defect detection apparatus.

  In FIG. 1, reference numeral 1 denotes a sheet-like object that runs in the direction of arrow X. Reference numerals 2 and 3 denote light sources having the same specifications, and reference numerals 6 and 7 denote light receiving means for receiving light emitted from the light sources 2 and 3 and transmitted through the sheet-like object 1, respectively. Reference numeral 8 denotes a determination unit that compares the amounts of light received by the light receiving units 6 and 7 to determine the type of defect.

  In FIG. 1, the light receiving means 6 is dark-field imaging, and receives light scattered from a defect out of light emitted from the light source 2. On the other hand, the light receiving means 7 performs bright field photography. By comparing and collating the amounts of light received by the light receiving means 6 and the light receiving means 7, it is possible to discriminate between a concave defect and a convex defect, or a substantial defect and a concave and convex defect such as a foreign object. However, since the amount of received light is small when the thickness change is transmitted through a fine unevenness defect, the scattered light is hardly received by the light receiving means 6, so this method is applied only to the unevenness defect whose thickness change is abrupt. Limited applicability.

  As a means for detecting a concave-convex defect having a minute thickness change, a method of irradiating light from an oblique direction with one or more light sources as shown in FIG. 2 is generally performed. In FIG. 2, reference numeral 1 denotes a sheet-like object that travels in the direction of the arrow X. Reference numerals 2 and 3 denote light sources having the same specifications, which irradiate light from an oblique direction on the surface of the sheet-like object. Reference numerals 6 and 7 denote light receiving means for receiving light emitted from the light sources 2 and 3 and transmitted through the sheet-like object 1. Reference numeral 8 denotes a determination unit that compares the amounts of light received by the light receiving units 6 and 7 to determine the type of defect.

  According to this method, by irradiating light from an oblique direction, the lens effect due to the uneven shape of the defect is emphasized, so the change in the amount of light received by the light receiving means becomes significant, and a fine uneven defect with a thickness change is detected. Is possible. However, since only defects having a thickness change within a certain range can be detected, it is difficult to distinguish between the types of each defect when there are a plurality of types of uneven defects in the sheet-like material.

  On the other hand, FIG. 3 is a schematic diagram showing a schematic configuration of the defect determination method and apparatus according to the present invention.

  In FIG. 3, reference numeral 1 denotes a sheet-like material that travels in the direction of arrow X via a guide roll 9. Reference numerals 2 and 3 denote irradiation means for irradiating parallel light, and reference numerals 4 and 5 denote screens for projecting light emitted from the light sources 2 and 3 and transmitted through the sheet 1. Here, the parallel light emitted from the light sources 2 and 3 is set so that the component of the light beam is very nearly parallel to the optical axis in the irradiation direction, but the light is not completely parallel, so the light is slightly diverged. To do. Therefore, the amount of light attenuates according to the distance from the light source. Therefore, in order to keep the amount of light projected on the screens 4 and 5 equal, the linear distance L1 + L2 from the first irradiation means to the first screen and the linear distance L3 + L4 from the second irradiation means to the second screen are the same distance. Is set. On the other hand, the distance L2 from the sheet-like material to the first screen and the distance L4 from the sheet-like material to the second screen are different in order to express the difference in lens effect due to the irregular defect. Reference numerals 6 and 7 denote imaging means, which acquire defect information from the amount of light projected on the screens 4 and 5. Denoted by 8 is a defect discriminating unit, which compares the defect information acquired by the imaging units 6 and 7 to determine the type of the concavo-convex defect.

  According to the above configuration, since both the first irradiation unit and the second irradiation unit irradiate parallel light, the light having the same parallelism even though the distances L1 and L3 from the irradiation unit to the sheet-like object are different. Is incident on the sheet. On the other hand, since L2 and L4, which are distances to reach the screen after passing through the sheet-like material, are different, the types of uneven defects projected on the first screen and the second screen are different. That is, in the distance relationship of L2 <L4 shown in FIG. 3, when the irregular shape of the defect is abrupt, the focal length due to the lens effect of the defective portion is small, and the shadow of the defect is projected on both the first screen and the second screen. Is done. On the other hand, when the uneven shape change of the defect is gradual, the focal length due to the lens effect of the defect portion is large, and it is necessary to increase the distance between the sheet-like object and the screen in order to form a shadow. Although a shadow of a defect can be projected onto the first screen, a shadow of the defect cannot be projected onto the first screen. Therefore, it is possible to discriminate uneven defects having different shapes by comparing and comparing the defect information detected on the first screen with the defect information on the second screen at the timing when the same defect passes on the second screen. It becomes.

  When there are a plurality of uneven defects generated in the sheet-like material 1, it is preferable to appropriately adjust the number of sets of the irradiation unit, the screen, and the imaging unit according to the number of layers that need to be determined.

  The first irradiating unit and the second irradiating unit are not particularly limited as long as the light source can irradiate parallel light and can uniformly irradiate the sheet-like object with a light amount recognizable by the imaging unit. As a means for realizing the parallel light, it is preferable to adopt a point light source as a light source type because it is possible to create light with reduced light interference, and further, the light from the point light source is made up of a plurality of lenses. It is more preferable that the light passes through the light beam because it is close to parallel light. Also, in lamps used for point light sources, lamps that emit light by arc discharge, such as xenon lamps and mercury lamps, are closer to points than lamps such as LEDs and halogen lamps that have chips or filaments in the light source. It is preferable in that it can be. As a light source that can be used in the present invention, for example, a xenon short arc lamp light source device SX-UI501XQ manufactured by USHIO INC. Can be used.

  The sizes of the first screen and the second screen can be appropriately determined according to the width dimension of the sheet-like material, the irradiation angle of the irradiation means, and the distance from the irradiation means. That is, the first screen and the second screen are dimensioned so that all the light irradiated from the irradiation means and transmitted through the sheet can be projected in the width direction of the sheet. What has the flatness which does not have is preferable. The surface material of the first screen and the second screen may be any material that diffuses the light emitted from the first irradiation means and the second irradiation means, and is preferably a light color system that hardly absorbs light. It is more preferable that

  The distance L2 between the sheet-like material and the first screen and the distance L4 between the sheet-like material and the second screen can be appropriately determined according to the size of the defect to be identified. The larger the distance between the sheet-like material and the screen, the smaller the irregularity inclination angle, that is, the irregularity defect with a slight change in thickness such as protrusions and depressions, or the irregularity defect with a large size in the sheet-like surface direction. Can be projected onto the screen. In addition, as shown in FIG. 4, the lens effect of the concavo-convex defect portion is emphasized by tilting the sheet-like object with respect to the optical axis of the light emitted from the first irradiation means and the second irradiation means. It is also possible to set the distance from the means to the screen small.

  A line sensor camera or an area sensor camera can be appropriately applied to the first imaging means and the second imaging means, but a line sensor camera is preferable in that the resolution in the width direction of the sheet-like object can be set finely. When a line sensor camera is applied to the imaging means, it is possible to install a separate encoder, integrate the traveling speed of the sheet-like material from the output pulse, and calculate the position information of the detected defect. As the line sensor camera that can be used in the present invention, for example, TI5150TSS manufactured by Excel Corporation can be used.

  The defect discriminating means 8 includes a circuit for extracting presence / absence of concave / convex defects at each photographing position and position information based on a signal representing received light amount information sent from the first imaging means and the second imaging means, and a first imaging Any circuit may be provided as long as it has a circuit for comparing the defect information of the means and the second image pickup means and discriminating the type of the concavo-convex defect, and is not particularly limited as long as this object can be achieved. As a flow of defect detection in the present invention, for example, with respect to the amount of light received by the first imaging unit and the second imaging unit, a bright side threshold for detecting a convex defect and a dark side for detecting a concave defect A threshold value is set, and when a received light amount signal that is equal to or greater than the bright side threshold value or less than the dark side threshold value is input, it is recognized as a defect and position information is stored, and a two-dimensional image is created. In addition, as a flow of defect determination in the present invention, for example, the defect information detected by comparing and comparing defect position information recorded by the first imaging unit and the second imaging unit and a two-dimensional image subjected to image processing Are classified into the concavo-convex defects detected by both of the imaging means, or the concavo-convex defects detected by either one of them, thereby determining the type of the concavo-convex defect. Here, in addition to the concave and convex defects, there are cases where defects having a substance and a function of shielding light occur in the sheet-like material, but the light is shielded by the falling level of the luminance signal of the shadow of the concave defect and the foreign matter. Since the falling level of the luminance signal in this case is different, it is possible to discriminate foreign objects and uneven defects by additionally setting a threshold value. In addition, in the present invention, it is also possible to discriminate only uneven defects by installing a foreign matter removing means and a means for detecting substantial foreign matter on the upstream side in the traveling direction of the sheet-like material with respect to the defect discriminating apparatus. Is possible.

  As described above, the first irradiating means for irradiating the sheet-like material with parallel light on the traveling path of the light-transmissive sheet-like material, and the first irradiating means for the sheet-like material surface. A first screen that projects light from the first irradiating means that is transmitted through the sheet-like material, a first imaging means that images the light projected on the first screen, and the first A light source having the same specification as the irradiating means, a second irradiating means for irradiating the sheet-like object with parallel light from a position closer to the sheet-like object than the first irradiating means, and the surface of the sheet-like object On the opposite side of the second irradiating means, the first irradiating means is installed at the same distance as the distance between the first irradiating means and the first screen, and projects light from the second irradiating means that has passed through the sheet. 2 screens and projection onto the second screen A defect discriminating apparatus having a second image pickup means for picking up the emitted light, wherein the defect information obtained from the first image pickup means and the defect information obtained from the second image pickup means are compared and collated. By using a defect discriminating device, it is possible to determine the types of uneven defects generated on a sheet-like material, and to identify the cause of the generated uneven defects. It becomes possible to carry out early countermeasures, and it becomes possible to obtain a sheet-like object free from irregular defects.

1. Sheet
2. First irradiation means Second irradiation means 4. First screen 5. Second screen 6. First imaging means 7. Second imaging means 8. Defect determining means 9. Guide roll

Claims (8)

On the travel path of the light-transmitting sheet-like object, the first irradiation means for irradiating the sheet-like object with parallel light, and installed on the opposite side of the sheet-like object surface to the first irradiation means, A first screen that projects light from the first irradiation means that has passed through the sheet, a first imaging means that images light projected on the first screen, and a light source having the same specifications as the first irradiation means A second irradiating means for irradiating the sheet-like object with parallel light from a position closer to the sheet-like object than the first irradiating means; and a side opposite to the second irradiating means with respect to the sheet-like object surface. A second screen that projects the light from the second irradiating means that is installed at the same distance as the distance between the first irradiating means and the first screen and transmits the sheet-like material; First to image the light projected on the screen A defect discriminating apparatus having an image pickup means, wherein the defect information obtained from the first image pickup means and the defect information obtained from the second image pickup means are compared and collated, and the uneven defect generated on the surface of the sheet-like object A defect discriminating apparatus characterized by discriminating the type of the defect. In the defect discriminating apparatus, a shadow pattern of the concavo-convex defect projected on the first screen by the lens effect of the concavo-convex defect is photographed by the first imaging means, and the concavo-convex defect projected on the second screen by the lens effect of the concavo-convex defect is detected. A shadow pattern is photographed by the second imaging means, and the position coordinates on the surface of the sheet-like object are compared and collated among the defect information obtained by the first imaging means and the second imaging means. The defect determination apparatus according to claim 1, wherein the type is determined. The defect determination apparatus according to claim 1 or 2, wherein the first irradiation unit and the second irradiation unit are point light sources. The defect determination apparatus according to any one of claims 1 to 3, wherein the first irradiation unit and the second irradiation unit include one or a plurality of lenses to make the irradiation light parallel light. The defect determination apparatus according to any one of claims 1 to 4, wherein a lamp used in the first irradiation unit and the second irradiation unit is an arc discharge type. 6. The defect determination apparatus according to claim 1, wherein the first imaging unit and the second imaging unit are line sensor CCD cameras. A defect characterized in that, using the defect discriminating device according to any one of claims 1 to 6, a type of a concavo-convex defect generated on the surface of the sheet-like material is discriminated on a travel route of the sheet-like material. How to determine. A sheet-like material in which the type of the concave-convex defect is determined using the defect determination device according to claim 1.

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