JP6500518B2 - Sheet inspection device - Google Patents

Description

  The present invention relates to a technology for detecting an abnormal part of a sheet-like object to be inspected.

  In a production line for manufacturing or processing a sheet-like article, an abnormal point on a sheet is generated using an image obtained by irradiating the sheet with visible light or infrared light and capturing the transmitted light or reflected light with a camera. An inspection apparatus for detecting (foreign substance contamination, dirt, scratches, etc.) is used.

  In this type of inspection apparatus, it is relatively easy to detect an abnormal place on a sheet, but it is very difficult to precisely and accurately determine what kind of abnormality is detected. . Therefore, conventionally, there is no alternative but to dispose of the sheet in which the abnormal portion is detected, discarding the sheet, or giving it to a detailed inspection by visual inspection. However, in actuality, there are various abnormalities that may occur in the sheet, and there are some which do not need to be defects (defects) depending on the type of product, application, material and the like.

  For example, although a microporous polyolefin film is generally used for a separator of a lithium ion secondary battery, since the separator itself is not noticeable to the human eye, even if there are some stains, etc., it is not possible unless there is a problem with the functionality. There is no need to make it a good product. On the other hand, metal contamination or adhesion or pinholes may be a short circuit, so it can be said that this is a type of abnormality that should not be overlooked. Conversely, in the case of paper, although small pinholes are acceptable, there are also cases where it is desirable to detect stains or wrinkles that affect appearance as defects.

  Therefore, conventionally, several inspection methods have been proposed in which the type of abnormality can be determined by combining a plurality of types of measurement systems. For example, in Patent Document 1, a transmitted light image obtained by capturing transmitted light from the back surface of a sheet and a reflected light image obtained by capturing light specularly reflected on the surface of the sheet are binarized to obtain the number of black pixels in the transmitted light image. If the number of black pixels in the reflected light image is significantly smaller than in the case of internal light, if the number of black pixels in the transmitted light image is significantly smaller than the number of black pixels in the reflected light image, then the surface foreign matter defect, In other cases, a method is disclosed for determining surface shape defects. In addition, according to Patent Document 2, an inspection is performed in which visible light and infrared light are irradiated to the same portion of a sheet, and a visible light image and an infrared light image obtained by imaging each reflected light are used to determine a metal defect. A method is disclosed.

  However, in the conventional method, although the abnormality on the surface of the sheet and the inside of the sheet can be detected with high accuracy, the problem is that the detection accuracy of the abnormality on the back surface of the sheet (the surface opposite to the reflected light measurement system) is low is there. For example, when foreign matter adheres to or mixes in with the back of the sheet, if the color of the foreign matter is dark (that is, if it is significantly different from the formation of the sheet), it can be detected even by the reflected light measurement system on the surface. Lighter colors make detection difficult. Therefore, in the conventional inspection method, there is a risk of missing a defect on the back side of the sheet. Of course, if the same inspection as the front surface of the sheet is also performed on the back surface of the sheet, it is possible to eliminate missed defects on the back surface. However, in that case, two sets of reflected light measurement systems are required, leading to an increase in the size and cost of the apparatus, which is not preferable. As mentioned above, there is also a type of abnormality that must not be overlooked, such as metal defects in separators, so a method capable of accurately detecting foreign matter attached to or mixed with the back of the sheet with a simple configuration is desired. .

JP, 2013-253906, A JP, 2014-20910, A

  The present invention has been made in view of the above-described circumstances, and the object of the present invention is a technique capable of accurately detecting both an abnormality on the front side and an abnormality on the back side of a sheet-like inspection object with a simple configuration. It is to provide.

The present invention is a sheet inspection apparatus for inspecting a sheet-like object to be inspected, and a first imaging sensor for imaging light emitted from a first light source and reflected by a first surface of the object to be inspected, and a second light source A second imaging sensor for imaging light emitted and transmitted through the inspection object; a first image of the inspection object obtained by the first imaging sensor; and the inspection object obtained by the second imaging sensor A processing unit configured to detect an abnormal part on the inspection object using the second image and to determine a type of abnormality occurring at the detected abnormal part; and an abnormality determined by the processing unit And an output unit that outputs information on an abnormal part including at least information indicating a type, and in the abnormal part, both the pixel value of the first image and the pixel value of the second image are the inspection object Ratio to the normal value when there is no abnormality above If you are lowering Te, wherein the processing unit, or abnormally occurring in previous SL anomaly is said a first surface foreign matter foreign matter into the first surface of the object to be inspected is attached or incorporated, the It is determined whether the foreign matter is adhered to or mixed in with the foreign matter on the second face side opposite to the first face, and the processing unit determines the degree of reduction of the pixel value of the first image with respect to the normal value. Is determined to be a first surface foreign object when the threshold value is larger than the threshold value, and is determined to be a second surface foreign object otherwise, the processing unit reduces the pixel value of the second image with respect to the normal value. The sheet inspection apparatus is characterized in that different threshold values are used according to the degree of .

  If there is any abnormality on the object to be inspected, characteristics such as the light absorptivity, reflectance and transmittance may change at the abnormal point as compared with other points (that is, places without abnormality). Moreover, the manner of change depends on the wavelength of light and the type of anomaly. Therefore, depending on what kind of abnormality has occurred on the inspection object, the characteristic is in the degree of change of the pixel value of each of the first image obtained by the first image sensor and the second image obtained by the second image sensor. appear. According to the present invention, it is possible to accurately determine which of the first surface and the second surface of the object under test has an abnormality based on the degree of decrease in pixel values of the first image and the second image. it can. Moreover, since a large-scale configuration such as providing the reflected light measurement system on both sides of the inspection object is unnecessary, the sheet inspection apparatus can be miniaturized. Here, the degree of decrease of the pixel value with respect to the normal value is, for example, the difference between the normal value and the pixel value (decrease amount), the difference between the normal value and the pixel value (decrease amount) divided by the normal value, or It is possible to use a value obtained by standardizing the reduction amount or the division value.

Prior Symbol processor, the degree of reduction with respect to the normal value of the first image pixel value is determined to the first surface foreign matter is larger than the threshold value, you determined that the second surface foreign matter otherwise . Further, the processing unit, in accordance with the degree of reduction with respect to the normal value of the pixel values of the second image, Ru using different said threshold. Thereby, the first surface foreign object and the second surface foreign object can be determined easily and accurately.

The imaging apparatus further includes a third imaging sensor for imaging the light emitted from the third light source and reflected by the inspection object, and the third imaging sensor is disposed on the first surface side of the inspection object, The light emitted from the first light source is visible light, the light emitted from the third light source is infrared light, and in the processing unit, the abnormality occurring at the abnormal portion is the first surface foreign matter In this case, it is preferable to determine whether the first surface foreign matter is a metal or a nonmetal using the third image of the inspection object obtained by the third imaging sensor. According to this configuration, not only the front / back determination but also the determination as to whether the foreign material is a metal or a nonmetal can be performed, so that the abnormality of the inspection object can be classified in more detail. In particular, in the case of an inspection object such as a secondary battery separator in which metallic foreign matter leads to a serious defect, the determination function of metal or nonmetal is extremely useful.

  For example, when the degree of decrease of the pixel value of the first image with respect to the normal value and the degree of decrease of the pixel value of the third image with respect to the normal value are substantially the same, the processing unit may It can be determined that the foreign matter is metal. Thereby, metals and nonmetals can be determined easily and accurately.

  The light source further includes a fourth light source that emits light from the opposite side of the first imaging sensor across the inspection object, and the light emitted from the first light source and the light emitted from the fourth light source are plural. The pixels of the first image have pixel values for each of a plurality of color components, and the pixels of the first image have pixel values of a plurality of color components, and at the abnormal portion, the pixels of any of the color components of the first image When the pixel value or the value obtained by integrating the pixel values of two or more color components is increased compared to the normal value, the processing unit determines the balance of the color components of the first image at the abnormal portion. It is preferable to determine whether the abnormality occurring at the abnormal point is a pinhole defect. According to this configuration, not only the front / back determination but also the pinhole defect determination can be performed, so that the abnormality of the inspection object can be classified in more detail. In particular, in the case of an object to be inspected in which a pinhole defect leads to a serious defect as in a separator of a secondary battery, the pinhole defect determination function is extremely useful. Here, a value obtained by integrating pixel values of two or more color components means a value corresponding to the brightness of the pixel calculated from pixel values of two or more color components.

  For example, when the balance of color components of the first image at the abnormal point is substantially the same as the balance of color components of light irradiated from the fourth light source, the processing unit generates the abnormal point It can be determined that a certain abnormality is a pinhole defect. Thereby, pinhole defects can be determined easily and accurately.

  The first imaging sensor configured to receive the light of the first light source, the second imaging sensor configured to receive the light of the second light source in one imaging device, and the second imaging sensor configured to receive the light of the second light source Preferably, the third imaging sensor configured to receive the light of the third light source is provided. Thus, the measurement system can be miniaturized.

  It is preferable that the imaging device has a spectral element that divides one optical path and guides light to each of the first imaging sensor, the second imaging sensor, and the third imaging sensor. As a result, since the first imaging sensor, the second imaging sensor, and the third imaging sensor can simultaneously capture the same position on the inspection object, it is not necessary to align the images obtained by each sensor, and the processing is simplified. Accuracy can be improved.

  The imaging device is disposed on the first surface side of the inspection object, and the first light source and the third light source are disposed to emit light to the first surface side of the inspection object, It is preferable that two light sources be disposed to face the imaging device with the inspection object interposed therebetween. As a result, the illumination system and the measurement system of the sheet inspection apparatus can be miniaturized.

  The first imaging sensor configured to receive the light of the first light source and the light of the fourth light source in one imaging device, and the light configured to receive the light of the third light source A third imaging sensor is provided, the imaging device is disposed on the first surface side of the inspection object, and the first light source and the third light source are light on the first surface side of the inspection object And the fourth light source is disposed to face the imaging device with the inspection object interposed therebetween, and the first light source doubles as the second light source, and the second imaging is performed. It is also preferable that the sensor be disposed so as to face the first light source with the inspection object interposed therebetween. Thereby, further downsizing of the illumination system and the measurement system of the sheet inspection apparatus can be achieved.

  The first imaging sensor configured to receive the light of the first light source and the light of the fourth light source in one imaging device, and the light configured to receive the light of the third light source A third imaging sensor is provided, the imaging device is disposed on the first surface side of the inspection object, and the first light source and the third light source are light on the first surface side of the inspection object And the fourth light source is disposed to face the imaging device with the inspection object interposed therebetween, and the third light source doubles as the second light source, and the second imaging is performed. It is also preferable that the sensor be disposed to face the third light source with the inspection object interposed therebetween. Thereby, further downsizing of the illumination system and the measurement system of the sheet inspection apparatus can be achieved.

  The first imaging sensor configured to receive the light from the first light source and the light from the fourth light source in one imaging device, and the light source configured to receive the light from the second light source A second imaging sensor and the third imaging sensor configured to receive the light of the third light source are provided, and the imaging device is disposed on the first surface side of the inspection object, The first light source and the third light source are disposed to emit light to the first surface side of the inspection object, and the common light source serving as the second light source and the fourth light source is the inspection object. It is also preferable to have a configuration in which it is disposed so as to face the image pickup apparatus with the image pickup apparatus interposed therebetween. Thereby, further downsizing of the illumination system and the measurement system of the sheet inspection apparatus can be achieved.

  The light emitted from the second light source may include light of a blue wavelength. Since the light of blue wavelength has a large energy, the transmittance of the object to be inspected is high, and the accuracy of abnormality detection can be improved.

  The light emitted from the first light source may include light of a red wavelength. Since the light having the red wavelength and the infrared light have substantially the same reflection characteristics with respect to metal, the determination accuracy of metal / nonmetal can be improved.

  The present invention can also be grasped as a sheet inspection apparatus having at least a part of the above configuration, and a control method of a sheet inspection apparatus having at least a part of the above processing, a sheet inspection method, or abnormal type discrimination of a sheet. It can be understood as a method. In addition, the present invention can also be regarded as a program for causing a computer to execute such a method, or a computer-readable storage medium which stores such a program non-temporarily. Each of the above configurations and processes can be combined with each other as long as there is no technical contradiction.

  According to the present invention, both the abnormality on the front side and the abnormality on the back side of the sheet-like object to be inspected can be accurately detected with a simple configuration.

FIG. 1 is a block diagram of a sheet inspection apparatus according to a first embodiment. FIG. 6 is a diagram showing an example of normalized pixel values obtained by each signal processing unit. An example of the result output screen which an output part outputs. Indicates the correspondence between the type of abnormality (upper part), the state of reflection and transmission of light at the abnormal part (middle part), and the degree of decrease in the normalized pixel value of the reflected light image and transmitted light image at the abnormal part (lower part) Figure. 6 is a flowchart of abnormality detection and type determination by the sheet inspection apparatus. 6 is a flowchart of type determination of abnormality according to the first embodiment. FIG. 7 is a block diagram of a sheet inspection apparatus according to a second embodiment. (A) is an example of the change of reflected visible light and reflected infrared light in the case of nonmetal, (b) is an example of the change of reflected visible light and reflected infrared light in the case of metal. 10 is a flowchart of type determination of abnormality according to the second embodiment. (A) is a figure which shows the structure of the sheet | seat inspection apparatus based on Example 3 and Example 4, (b) is a figure which shows the structure of the imaging device based on Example 3, (c) is an imaging device based on Example 4 FIG. FIG. 18 is a view showing the configuration of a sheet inspection apparatus according to a fifth embodiment. 16 is a flowchart of type determination of abnormality according to the fifth embodiment. FIG. 18 is a view showing the configuration of a sheet inspection apparatus according to a sixth embodiment. 12 is a modified example of type determination of abnormality according to the first embodiment.

  Hereinafter, with reference to the drawings, modes for carrying out the present invention will be exemplarily described in detail based on examples. However, the dimensions, materials, shapes, relative positions and the like of the components described in this embodiment are not intended to limit the scope of the present invention to them unless otherwise specified.

Example 1
FIG. 1 is a block diagram of a sheet inspection apparatus 1 according to the present embodiment. The sheet inspection apparatus 1 is a system used to automatically detect an abnormality or a defect of a sheet-like article in a production line for manufacturing or processing a sheet-like article.

  The sheet inspection apparatus 1 includes, as an illumination system, a first light source 31 that emits visible light to the front surface (first surface) of the sheet-like inspection object 2 and visible light on the back surface (second surface) of the inspection object 2 And a second light source 32 for emitting light. The sheet inspection apparatus 1 further includes a first imaging sensor 41 and a second imaging sensor 42 disposed on the surface side of the inspection object 2 as a measurement system. The first imaging sensor 41 is a reflected light measurement system configured to image the light emitted from the first light source 31 and diffused and reflected by the inspection object 2. The second imaging sensor 42 is irradiated from the second light source 32 and is This is a transmitted light measurement system configured to pick up the light that has passed through the inspection object 2 straight. Further, the sheet inspection apparatus 1 is a processing device 5 that performs detection of an abnormal part included in the inspection object 2 and type determination of abnormality based on an output signal of the first imaging sensor 41 and an output signal of the second imaging sensor 42. have.

  The inspection object 2 is a sheet-like article, and is conveyed in the arrow direction of FIG. 1 by the manufacturing apparatus or the processing apparatus. The inspection object 2 can be exemplified by paper, film, resin, cellulose and the like. The inspection object 2 may be a separator used for a secondary battery, an optical sheet used for liquid crystal, or the like. In the present embodiment, the illumination system and the measurement system are fixed, and the inspection object 2 is moved, but instead, the inspection object 2 is fixed and the illumination system and measurement system are moved. It is also good.

  The sheet inspection apparatus 1 uses the first image of the inspection object 2 obtained by the first imaging sensor 41 and the second image of the inspection object 2 obtained by the second imaging sensor 42 to detect an abnormality on the inspection object 2. While detecting a part, it has a function which discriminate | determines the kind of abnormality which has generate | occur | produced in the detected abnormal part, and outputs the result. In this embodiment, a resin film sheet having a transparent or translucent texture is used as the inspection object 2, and two types of abnormalities, that is, “front surface foreign matter” and “rear surface foreign matter” of the inspection object 2 are detected and determined. The surface foreign matter (first surface foreign matter) is an abnormality in which the foreign matter is attached or mixed into the surface (first surface) of the film, and the back surface foreign matter (second surface foreign matter) is a foreign matter to the back surface (second surface) of the film. It is an abnormality that has adhered or mixed.

  As the illumination system, it is possible to use one with a limited wavelength range, such as an LED, or one with a limited wavelength range using a wavelength filter. Light of the same wavelength may be used for the first light source 31 and the second light source 32, or light of different wavelengths may be used. In the present embodiment, the same type of white light source is used for the first light source 31 and the second light source 32.

  For example, a CCD image sensor in which 4096 light receiving elements are arranged in series can be used as the measurement system. A plurality of CCD image sensors may be arranged side by side in the width direction of the inspection object 2 in accordance with the width of the inspection object 2 so that the entire width of the inspection object 2 can be imaged. In each light receiving element, light is converted into charge according to the amount of light received. The charge output from each light receiving element is input to the processing device 5 as an output signal (imaging data). As the first imaging sensor 41 and the second imaging sensor 42, color cameras (three color sensors of R, G, and B) may be used, or a monochrome camera (one color sensor) may be used. In this embodiment, a monochrome camera is used. Further, in the present embodiment, the first imaging sensor 41 and the second imaging sensor 42 are disposed offset in the transport direction.

The processing device 5 processes the imaging data (imaging data of reflected light) output from the first imaging sensor 41, and the imaging data (imaging of transmission light) output from the second imaging sensor 42. And a second signal processing unit 52 for processing data). The first signal processing unit 51 performs white shading processing on the signal of one line output from the first imaging sensor 41 to correct the variation in the output level of each light receiving element. Similarly, the second signal processing unit 52 performs white shading processing on the signal of one line output from the second imaging sensor 42. Hereinafter, the values after white shading output from the first signal processing unit 51 and the second signal processing unit 52 are referred to as output pixel value I _reflection and I _{transmission, respectively,} and the image of the inspection object 2 consisting of the output pixel value I _{reflection Is referred} to as a transmitted light image (second image), which is an image of the object 2 to be inspected which is a reflected light image (first image) and an output pixel value I _transmission .

Furthermore, the first signal processing unit 51 and the second signal processing unit 52 calculate normalized pixel values of each of the reflected light and the transmitted light by normalizing the output pixel values I _reflection and I _transmission . In this embodiment, the normalized pixel value has a value range of 0 to 255, and the output pixel value (normal value) N _reflection in the state where there is no abnormality in the inspection object 2 and N _transmission is 128 which is the center value of the value range. Standardize to be The “output pixel value (normal value) in the absence of abnormality” may be an average value of output pixel values when imaging is performed a plurality of times. The normalized pixel value becomes smaller as the degree of decrease of the output pixel value (the amount of light received by the sensor) is larger, and becomes larger as the degree of increase of the output pixel value (the amount of light received by the sensor) is larger. There is a correlation with the degree. Then, the normalized pixel value becomes a value close to 128 in a portion where the inspection object 2 is not abnormal (also referred to as formation). In the following description, the output pixel value and the normalized pixel value are referred to as “pixel value” or simply “value” when it is not necessary to distinguish them in particular.

  FIG. 2 is a diagram showing an example of the normalized pixel value obtained by each of the signal processing units 51 and 52. As shown in FIG. The horizontal axis is a pixel (light receiving element), and the vertical axis is a normalized pixel value. The normalized pixel value is about 128 in the part where there is no abnormality (formation), but in the pixel corresponding to the abnormal part, the normalized pixel value increases or decreases. The direction (increase or decrease) of the change of the normalized pixel value and the change degree thereof may be different between the reflected light and the transmitted light. Even in the case of the formation portion, the normalized pixel values slightly vary from pixel to pixel due to the influence of unevenness or the like on the surface of the inspection object 2.

  The processing device 5 includes an alignment processing unit 55 that aligns an image obtained from the first imaging sensor 41 and an image obtained from the second imaging sensor 42. Here, since the first imaging sensor 41 and the second imaging sensor 42 are disposed offset in the transport direction of the inspection object 2, the portion imaged by the first imaging sensor 41 is the second imaging sensor 42. It takes a certain amount of time to reach the position where the image is taken. In order to compare the pixel values of the same place on the inspection object 2, the alignment processing unit 55 generates one line of image data obtained from the first imaging sensor 41 and one line obtained from the second imaging sensor 42. Perform alignment (time alignment) with the minute image data.

Here, since the transport speed of the inspection object 2 and the distance from the first imaging sensor 41 to the second imaging sensor 42 are known, they are imaged by the first imaging sensor 41 based on these values. The time delay until the location is imaged by the second imaging sensor 42 can be calculated. That is, alignment can be performed by shifting data by this time delay.

  Further, the processing device 5 includes an abnormality detection unit 56 that detects an abnormal part included in the inspection object 2 and a detection threshold storage unit 56A that stores a threshold used for the abnormality determination. In the present embodiment, as described later, when the degree of change of the output pixel value of the first imaging sensor 41 is large to a certain extent, it is determined that an abnormality occurs. Therefore, the threshold value of the degree of change of the pixel value to be determined as abnormal is stored in the detection threshold storage unit 56A. This threshold is determined by the type of the inspection object 2 and the inspection standard set by the user.

  The processing device 5 further includes a determination unit 57 that determines the type of abnormality when an abnormal part is detected, and a determination threshold storage unit 57A that stores a plurality of threshold values used in the process of determining the type of abnormality. There is. The determination unit 57 determines types of change (increase or decrease) in pixel value of each of the reflected light image obtained from the first imaging sensor 41 and the transmitted light image obtained from the second imaging sensor 42, and the type of abnormality to be distinguished. The correspondence relationship is defined in advance, and the type of abnormality is determined by determining to which type the method of changing the pixel value corresponds. Detailed processing will be described later.

  The output unit 58 is a function of outputting information on an abnormal part. Although the output destination of the information is typically a display device, it outputs information to the printing device, outputs a message or an alarm from a speaker, or transmits a message by e-mail or the like to the user's terminal Information may be sent to an external computer. FIG. 3 is an example of the result output screen output by the output unit 58 to the display device. In this screen, information 580 indicating the type of abnormality detected and determined (in the example of FIG. 3, "back surface foreign matter with a light density"), a reflected light image 581 of the abnormal portion imaged by the first imaging sensor 41, the second A change in output signals (output pixel value or normalized pixel value) of each of the first imaging sensor 41 and the second imaging sensor 42 in the transmitted light image 582 of the abnormal part captured by the imaging sensor 42 and the line 583 passing the abnormal part Graphs 584 and 585 are displayed. By outputting information on such an abnormal part, the user (inspector) can specifically grasp the contents of the generated abnormality, and it is judged whether or not the abnormality should be regarded as a defect (defect), or production equipment It can be useful for feedback on manufacturing conditions and operating conditions.

  In FIG. 4, the type of abnormality (upper stage), the state of reflection and transmission of light at the abnormal point (middle stage), and the degree of decrease of the normalized pixel value of the reflected light image and transmitted light image at the abnormal point (lower stage) Indicates the correspondence between In FIG. 4, “the degree of reduction” means the amount of reduction of the normalized pixel value with respect to the normal value (the value obtained by subtracting the normalized pixel value from the normal value (128)). Such correspondence can be obtained by performing an experiment for each type of abnormality. The method of change of standardized pixel values, classification of types, types of abnormalities that may occur, etc. vary depending on the material, physical properties, etc. of the inspection object 2, so the correspondence relationship as shown in FIG. It is good to prepare beforehand for every thing and to implement in the program of the processing apparatus 5 as a look-up table or determination logic.

  In FIG. 4, from the left, an abnormality (surface foreign substance (dark)) in which dense foreign substances 20 adhere or mix on the surface of the test object 2 and thin foreign substances 21 adhere or mix on the surface of the test object 2 Anomalous (surface foreign matter (light)), foreign matter 22 with high concentration attached to or mixed in with the back side of the inspection object 2 (backside foreign matter (dark)), foreign object 23 with low concentration adheres to the back side of the inspection object 2 Or the abnormality (back side foreign substance (light)) which was mixed is shown. In either case, both the value of the reflected light and the value of the transmitted light are lower than the normal value, but the degree of reduction of the reflected light and the transmitted light changes depending on the type of abnormality.

Specifically, the degree of decrease in the value of the reflected light is the largest in the case of surface foreign matter (dark), the smallest in the case of back surface foreign matter (light), and the case of surface foreign matter (light) and back surface foreign matter (dark) Is in the middle. On the other hand, the degree of reduction of the transmitted light value is determined by the concentration of the foreign matter, and does not depend on whether the foreign matter is on the front surface or the back surface. Therefore, in the case of front surface foreign matter (dark) and back surface foreign matter (dark), the degree of decrease in the value of transmitted light is relatively large, and in the case of front surface foreign matter (light) and back surface foreign matter (light), the value of transmitted light decreases The degree of is relatively small.

  TH1 to TH3 illustrated in the lower part of FIG. 4 are examples of determination thresholds for determining four types of abnormalities. The threshold TH1 is a threshold for determining the density / lightness of a foreign substance, and is set to be intermediate between the degree of reduction of transmitted light in the case of a thick foreign substance and the degree of reduction in transmitted light in the case of a light foreign substance. The threshold value TH2 is a threshold value for discriminating the front side / the back side in the case of a dark foreign substance, and is set between the reduction degree of the reflected light in the case of the front side foreign substance (dark) and the reduction degree of the reflected light in the case of the reverse side foreign substance (dark). Be done. The threshold TH3 is a threshold for discriminating the front side / the back side in the case of a light foreign substance, and is set to be intermediate between the degree of reduction of reflected light in the case of front side foreign substance (light) and the degree of reduction in reflected light in the case of back side foreign substance (light). Be done. These threshold values TH1 to TH3 are determined by experiments or the like, and are registered in advance in the determination threshold storage unit 57A.

  As described above, by clarifying in advance the correspondence between the type of change in value of each of the reflected light and the transmitted light and the type of abnormality, it is possible to easily and accurately determine the type of abnormality. In the present embodiment, the degree of change in the values of reflected light and transmitted light is evaluated using normalized pixel values obtained by normalizing output pixel values with normal values. As a result, it is possible to cancel the variation due to the variation of the light amount of the light source, the difference of the transmittance or reflectance or the absorptivity for each abnormal part, the difference of the transmittance or the reflectance or the absorptivity of the inspection object. Therefore, it is possible to make it hard to receive the influence of the disturbance, the influence of the abnormality or the variation of the inspection object, and it is possible to stabilize the accuracy of the detection of the abnormal part and the type determination of the abnormality.

  Next, the flow of processing of the sheet inspection apparatus 1 will be described with reference to FIG. FIG. 5 is a flowchart of processing executed by the processing device 5.

  In step S101, with the first light source 31 and the second light source 32 turned on, the first imaging sensor 41 and the second imaging sensor 42 capture an image of the inspection object 2, and the output signal thereof is the processing device 5 Incorporated into

In step S102, white shading processing is performed on the signal output from the first imaging sensor 41 and the signal output from the second imaging sensor 42 to generate output pixel values I _reflection and I _transmission . Each of the signal processing units 51 and 52 generates a normalized pixel value of reflected light and a normalized pixel value of transmitted light from the output pixel values I _reflection and I _transmission . The data of the output pixel value and the normalized pixel value is output to the alignment processing unit 55.

  In step S103, the alignment processing unit 55 aligns the reflected light data and the transmitted light data based on the transport speed of the inspection object 2 and the distance between the first imaging sensor 41 and the second imaging sensor 42. .

  In step S104, the abnormality detection unit 56 detects an abnormality. For example, the abnormality detection unit 56 detects an area (pixel group) including pixels smaller than 128 × 0.9 in an image of normalized pixel values of transmitted light, and the area of the area exceeds a predetermined value. The area is determined to be an "abnormal place". In the present embodiment, the detection threshold value for abnormality is set to -10% of the normal value (128), but this is only an example, and it is determined according to the characteristics of the inspection object or the imaging sensor, etc. The threshold may be set as appropriate. The detection threshold value is assumed to be registered in advance in the detection threshold storage unit 56A.

  In step S105, it is determined whether an abnormal part is detected in step S104. If an affirmative determination is made in step S105, the process proceeds to step S106. On the other hand, if a negative determination is made in step S105, this routine is ended assuming that there is no abnormality.

  In step S106, the determination unit 57 determines the type of abnormality.

  FIG. 6 shows a detailed flow of type determination of abnormality. First, in step S201, the determination unit 57 compares the degree of reduction of the transmitted light at the detected abnormal portion with the threshold value TH1 to determine the density / lightness of the foreign matter. Here, a value (reduction amount) obtained by subtracting the normalized pixel value from the normal value (128) is used as the “reduction degree”. If the degree of reduction of the transmitted light> TH1, the determination unit 57 determines that the object is a dark foreign object, and reads the threshold TH2 as the determination threshold for the front and back. On the other hand, if the degree of reduction of transmitted light ≦ TH1, the determination unit 57 determines that the object is a light foreign object and reads the threshold TH3 as the determination threshold for the front and back. That is, the determination unit 57 uses different determination thresholds for the determination of the front and back according to the degree of reduction of the transmitted light. Specifically, when the reduction degree of the transmitted light is larger than the threshold TH1, the determination threshold TH2 larger than the determination threshold TH3 in the case other than that is used.

  Then, determination unit 57 compares the reduction degree of the reflected light with the determination threshold (TH2 or TH3) (step S202 or S203), and the reduction degree of the reflected light is larger than the determination threshold (TH2 or TH3). It determines with a foreign material (step S204 or S206), and determines it as a back surface foreign material in the case other than that (step S205 or S207).

  When the type of abnormality is identified by the above determination logic, the process proceeds to the process of step S107 in FIG. In step S107, the output unit 58 outputs information on the abnormal part (see FIG. 3).

  According to the configuration of the present embodiment described above, it is possible to detect an abnormality in the sheet-like inspected object 2 and finely discriminate the type of the detected abnormality. In particular, detection of the back surface foreign matter, which was difficult to detect, can be performed only by the reflected light, and discrimination of the front surface foreign body and the back surface foreign body can be performed. This makes it possible to distinguish between an abnormality that may affect the quality of the product and an abnormality that does not need to be a defect (defect), thereby suppressing so-called oversight of inspection (overdetection) and increasing the product yield. It can be used for process improvement such as analysis of defect occurrence tendency.

In steps S201 to S203 in FIG. 6, the degree of decrease, which is the difference between the normal value and the normalized pixel value, is determined, and the degree of decrease is compared with the determination threshold. The specific method of determining whether the degree is larger than the threshold value is not limited to this. For example, in the present embodiment, the normal value is determined in advance (128).
TH1 '= 128-TH1
If the determination threshold TH1 ′ is defined as in the above, the determination process in step S201:
Degree of decrease of transmitted light (= 128-normalized pixel value of transmitted light)> TH1
And the following judgment process:
Normalized pixel value of transmitted light ≦ TH1 ′ (= 128−TH1)
And are equivalent. Therefore, TH1 ', TH2' (= 128-TH2), TH3 '(= 128-TH3) are prepared in advance as determination threshold values, and the determination process of steps S201 to S203 of FIG. It may be replaced by the determination process of S203 '. According to the determination process of FIG. 14, the process is simplified because the value of the decrease degree does not have to be calculated brightly.

Example 2
Next, a sheet inspection apparatus according to a second embodiment will be described. The second embodiment is characterized in that by adding a reflected light measurement system using infrared light to the configuration of the first embodiment, it is possible to determine whether the surface foreign matter is metal or nonmetal.

  FIG. 7 is a block diagram of the sheet inspection apparatus 1 according to the second embodiment. The sheet inspection apparatus 1 includes, in addition to the configuration of the first embodiment (see FIG. 1), a third light source 33 for irradiating the surface (first surface) of the inspection object 2 with infrared light, and the surface of the inspection object 2 And a third imaging sensor 43 disposed on the (first surface). The third imaging sensor 43 is an image sensor having sensitivity to the wavelength of infrared light, and is configured to image infrared light emitted from the third light source 33 and diffusely reflected by the inspection object 2.

  The sheet inspection apparatus 1 includes a first image of the inspection object 2 obtained by the first imaging sensor 41, a second image of the inspection object 2 obtained by the second imaging sensor 42, and an inspection object obtained by the third imaging sensor 43. An abnormal part on the inspection object 2 is detected using the third image of the object 2, and the type of abnormality occurring at the detected abnormal part is determined, and the result is output.

  In the present embodiment, a porous film made of an olefin resin used for a separator of a secondary battery or the like is used as the inspection object 2 and “surface foreign matter” and “rear foreign matter” are discriminated as in the first embodiment. In the case of "surface foreign matter", it is determined whether the foreign matter is "metal" or "nonmetal". In the manufacturing and processing steps of the sheet-like article, metal powder generated or exfoliated from the manufacturing apparatus or the conveying apparatus may be mixed or adhered to the sheet-like article. Such metal defects are serious defects that should not be overlooked in sheet-like articles such as secondary battery separators because they cause electrical shorts.

  Here, visible light is used as the first light source 31. As visible light, white light may be used, or light of a specific wavelength (color) may be used, but it is preferable to use long-wavelength light (for example, red light) in the visible light range. Further, near infrared light may be used as the third light source 33. In the sheet inspection apparatus 1 according to the present embodiment, is the degree of decrease in the reflected light of the light (visible light) of the first light source 31 substantially the same as the degree of decrease in the reflected light of the third light source 33 (infrared light)? This is because the type of metal that can be determined increases as the wavelengths of the visible light and the infrared light are closer because discrimination between metal and nonmetal is performed, and the determination accuracy is also improved. The types of metals that may be attached or mixed in the manufacturing and processing steps of the sheet-like article are limited to a certain extent (for example, iron, iron oxide, stainless steel, aluminum, copper, etc.), It is known that the reflection characteristics for red light and the reflection characteristics for near infrared light are approximately equal.

In addition to the configuration (see FIG. 1) of the first embodiment, the processing device 5 of the present embodiment is a third signal processing unit 53 that processes imaging data (imaging data of infrared light) output from the third imaging sensor 43. have. The third signal processing unit 53 performs white shading processing on imaging data of infrared light, and outputs an output pixel value I _IR . The image of the inspection object 2 composed of the output pixel value I _IR is called an infrared light image (third image). Further, the third signal processing unit 53 outputs the normalized pixel value by dividing the output pixel value I _IR by the normal value N _IR .

  8 (a) and 8 (b) show normalized pixel values of reflected visible light and reflected infrared light when the surface foreign matter is "non-metal" and "metal", respectively. The change in pixel value is schematically shown. As shown in FIG. 8A, when non-metallic foreign matter (dirt) adheres to the sheet, visible light is absorbed by the dirt, so the value of the reflected visible light becomes significantly smaller than the normal value. . On the other hand, since the absorption of infrared light is small, the degree of reduction of the value of reflected infrared light is considerably smaller than the degree of reduction of the value of reflected visible light. On the other hand, when metal adheres to the sheet, as shown in FIG. 8B, the reflectance of visible light and invisible light to the metal is almost the same, so the degree of decrease in the value of the reflected visible light and the reflection red The degree of decrease in the value of the ambient light is approximately equal. As described above, whether the foreign matter attached to or mixed in the sheet surface is metal or nonmetal and the degree of decrease in the value of the reflected visible light and the reflected infrared light is different, the determination of metal or nonmetal is made based on this. Is possible.

  FIG. 9 shows a flow of type determination of abnormality according to the present embodiment. The processes of steps S201 to S207 are the same as the processes of the first embodiment (see FIG. 6). In the present embodiment, after being determined as “surface foreign matter” in step S204 or S206, the determination unit 57 reads the threshold TH4 from the determination threshold storage unit 57A as the determination threshold of metal / nonmetal. The threshold TH4 is smaller than the minimum value (for example, can be determined statistically by experiments) of the difference between the degree of decrease in the reflected visible light and the reflected infrared light when nonmetal adheres or mixes, and is less than zero. It is set to a large value.

  In step S208, determination unit 57 calculates the absolute value of the difference between the reduction degree of the reflected infrared light and the reflected visible light, and when the value is smaller than threshold TH4, that is, the normal value of the reflected infrared light and the reflected visible light In the case where the degree of reduction with respect to is substantially the same) is determined as "metal" (step S209), and in the other cases, it is determined as "non-metal" (step S210).

  According to the configuration of the present embodiment described above, it is possible not only to discriminate between the surface foreign matter and the back surface foreign matter, but also in the case of the surface foreign matter, whether it is metal or nonmetal. This makes it possible to distinguish between metal defects that can be serious defects and other abnormalities, and can suppress so-called oversight of inspection (overdetection) and increase the product yield. In the case of the back surface foreign matter, it is not possible to determine whether it is metal or nonmetal in the method of the present embodiment, but it is judged that "possibly a metal defect" is judged to be the back surface foreign matter. Since it is possible, appropriate measures such as visual inspection can be made.

  Also in the present embodiment, the determination process of steps S201 to S203 of FIG. 9 may be replaced with the determination process of steps S201 'to S203' of FIG. In the determination process of step S208, instead of the "absolute value of the difference between the degree of reduction of the reflected infrared light and the reflected visible light", "the absolute value of the difference between the normalized pixel values of the reflected infrared light and the reflected visible light" You may use.

Example 3
FIG. 10A shows the configuration of the illumination system and measurement system of the sheet inspection apparatus 1 according to the third embodiment. In the third embodiment, a single imaging device 4 images the reflected visible light of the first light source 31, the transmitted visible light of the second light source 32, and the reflected infrared light of the third light source 33. As the imaging device 4, as shown in FIG. 10 (b), a 3-line camera in which three line sensors of a first imaging sensor 41, a second imaging sensor 42, and a third imaging sensor 43 are shifted in the transport direction Use

  In this configuration, when the imaging device 4 is disposed on the surface side (first surface side) of the inspection object 2, the first light source 31 and the third light source 33 are on the surface side like the imaging device 4 and the second light source 32 is It arrange | positions on the back surface side (2nd surface side), respectively so that it may oppose the imaging device 4 on both sides of the to-be-tested object 2. As shown in FIG. At this time, the wavelength range of each light source is set so that the light of the first light source 31, the light of the second light source 32, and the light of the third light source 33 include light of different wavelengths. The light reception wavelength range of each of the imaging sensors 41, 42, 43 is set so as to selectively receive only the wavelengths of the corresponding light sources 31, 32, 33. As a result, the reflected visible light, the transmitted visible light, and the reflected infrared light can be imaged by one imaging device 4, and the sheet inspection apparatus 1 can be miniaturized.

  As the light (transmitted light) of the second light source 32, light of a short wavelength, for example, blue light may be used. Since the energy of the light having a short wavelength is larger, the transmittance of the inspection object 2 is high, and the accuracy of the front / back determination can be improved. On the other hand, as the light (reflected light) of the first light source 31, it is preferable to use light containing at least a long wavelength light, for example, red light. As described above, by using long-wavelength light (light having a wavelength close to that of infrared light), metal / non-metal determination accuracy can be improved, and the types of metal that can be determined increase. is there.

Example 4
FIG. 10C shows the configuration of the imaging device 4 used in the sheet inspection apparatus 1 according to the fourth embodiment. The arrangement of the illumination system and the measurement system is the same as that of the third embodiment (see FIG. 10A), but the third embodiment uses a three-line camera while the third embodiment uses a three-line camera. It is different. That is, as shown in FIG. 10C, the imaging device 4 of the present embodiment uses incident light from the inspection object 2 by using the light separating element 40 that divides the light path as reflected visible light, transmitted visible light, and reflected red. The light is split into three of the external light, and each light is guided to the corresponding imaging sensor 41, 42, 43.

  Since the number of imaging devices 4 can be reduced to one by this method as well, the sheet inspection apparatus 1 can be miniaturized. Furthermore, since the imaging sensors 41, 42, 43 can image the light incident from the same position of the inspection object 2, alignment (time alignment) between data is not necessary. Therefore, the alignment process can be omitted to simplify the process, and since there is no influence of the alignment accuracy, there is an advantage that the abnormality detection accuracy can be improved. Although the three-plate camera is illustrated in FIG. 10C, in the case of an imaging apparatus including an element (image sensor) that receives at least three wavelengths (reflected visible light, transmitted visible light, and reflected infrared light), It is preferably applicable to this embodiment. For example, a four-plate camera or a five-plate camera may be used.

  Also in the case of this embodiment, light of a short wavelength, for example, blue light may be used as the light (transmitted light) of the second light source 32, and at least the light of the first light source 31 (reflected light) may be used. It is preferable to use light of a wavelength, for example, light including red light.

Example 5
FIG. 11 shows the configuration of the illumination system and the measurement system of the sheet inspection apparatus 1 according to the fifth embodiment. In the fifth embodiment, the second imaging sensor 42 is disposed on the back surface side (the second surface side) of the inspection object 2, and the first light source for reflected visible light and the second light source for transmitted visible light are one common light source. The fourth embodiment is characterized in that the fourth light source 34 is disposed on the back surface side of the inspection object 2 so as to make it possible to discriminate a pinhole defect.

  As shown in FIG. 11, in the present embodiment, the imaging device 4 is disposed on the surface side (first surface side) of the inspection object 2, and the common light source 35 and the third light source 33 are on the surface side of the inspection object 2. It is arranged to emit light. In addition, the fourth light source 34 is disposed to face the imaging device 4 with the inspection object 2 interposed therebetween. That is, the reflected visible light of the common light source 35, the reflected infrared light of the third light source 33, and the straight-ahead transmitted light of the fourth light source 34 enter the imaging device 4.

  As the common light source 35 and the fourth light source 34, light sources having the same wavelength range (the same spectral distribution) including a plurality of color components may be used. For example, a white light source can be used. Here, since the light of the fourth light source 34 is used to determine the pinhole defect of the inspection object 2, even if the light of the fourth light source 34 directly enters the imaging device 4 through the pinhole of the inspection object 2 The light amount is set to such a low level that the imaging data does not cause saturation. On the other hand, the light of the common light source 35 is set to have a sufficiently large light amount as compared to the fourth light source 34.

  As the imaging device 4, a three-plate type camera having three image sensors of two colors of R, G, and B + infrared light can be used. In this embodiment, an example using three image sensors of R, B and infrared light will be described. At this time, two image sensors of R and B correspond to the first imaging sensor 41, and an image sensor of infrared light corresponds to the third imaging sensor 43.

Furthermore, the second imaging sensor 42 is disposed on the back surface side (second surface side) so as to face the common light source 35 with the inspection object 2 interposed therebetween. In the present embodiment, the common light source 35 doubles as a second light source for transmitted light, and a combination of the common light source 35 and the second imaging sensor 42 constitutes a transmitted light measurement system. As the second imaging sensor 42, for example, a monochrome camera can be used. In the present embodiment, the first light source for reflected visible light is used as the common light source 35, but it is also possible to use the third light source 33 as the common light source. In that case, the second imaging sensor 42 having sensitivity to infrared light may be disposed at a position facing the third light source 33.

  FIG. 12 shows a flow of type determination of abnormality according to the present embodiment. The flow of FIG. 12 shows a process performed when an abnormal part (a part where the pixel value is significantly increased or decreased with respect to formation) is detected in the image of the inspection object 2. In addition, the same step number is attached | subjected about the process part same as the flow of the above-mentioned Example, and detailed description is abbreviate | omitted.

  First, in step S120, the determination unit 57 determines whether the pixel value of the detected abnormal portion is increasing (bright defect) or decreasing (dark defect). For determination as to whether a light defect or a dark defect, a pixel value of any color component of the first image obtained by the first imaging sensor 41 or a value obtained by combining pixel values of two or more color components is used. be able to. In the case of the present embodiment, for example, whether the pixel is a bright defect or a dark defect depending on whether the pixel value of R or B of the first image or the luminance value calculated from the values of R and B is larger than the threshold TH0. Determine. For example, the pixel value or the luminance value of the formation of the inspection object 2 is used as the threshold TH0.

  In the case of the dark defect, the routine of the front / back judgment and the metal / non-metal judgment is entered (step S120; YES). The flow of the front / back judgment and the metal / non-metal judgment is the same as that of the above-mentioned embodiment, so the description will be omitted.

  On the other hand, in the case of a bright defect, the routine for determining a pinhole defect / abnormality A / abnormality B is entered (step S120; No). First, the determination unit 57 determines whether the normalized pixel value of the reflected infrared light obtained by the third imaging sensor 43 is equal to or greater than the threshold TH5 (step S121). For example, TH5 may be set to about the same as the normal value (the value of formation) 128. If the normalized pixel value of the reflected infrared light is TH5 or more, it is determined as "abnormal B" (step SS122). When the normalized pixel value of the reflected infrared light is smaller than TH5, the determination unit 57 determines that the absolute value of the difference between the normalized pixel value of R and the normalized pixel value of B obtained by the first imaging sensor 41 is a threshold. Check to see if it is more than TH6. This indicates whether the balance of the color components (R, B) of the first image obtained by the first imaging sensor 41 is substantially the same as the balance of the color components (R, B) in the light irradiated from the fourth light source 34 It corresponds to the process to evaluate. If the color balance between the two is substantially the same (step S123: No), it is considered that the light emitted from the fourth light source 34 is directly incident on the first imaging sensor 41, and it is determined as "pinhole defect" (step S124). If the color balance is different (step S123; YES), it is determined as "abnormality A" (step S125). The color balance evaluation method may use a method other than the method described in the present embodiment. For example, the saturation of the pixel is calculated from the pixel values of R and B, and if the saturation is smaller than the threshold (that is, close to the achromatic color), the color balance is approximately the same as the balance in the normal state. You may judge.

  The "abnormality A" refers to the unevenness (portion where the porosity is rough) generated during the processing of the porous film or the state in which the oil adheres and permeates. In this case, the portion to which the unevenness or oil adheres and penetrates becomes a slightly colored and transparent spot. Then, the light from the common light source 35 and the light from the third light source 33 are transmitted almost to the back side through the spots. On the other hand, the light of the fourth light source 34 is transmitted to the surface side through the spot and is received by the first imaging sensor 41. However, unlike the pinhole defect, the light of a certain wavelength is absorbed and attenuated when transmitting through the spot, so that the color balance of the transmitted light is broken. Therefore, by evaluating the color balance, the pinhole defect and the abnormality A can be determined.

The “abnormality B” is unevenness (portion where the porous material is dense) generated at the time of processing of the porous film, and indicates a state in which the light reflectance is increased as compared to the film in the normal state. In this case, since the light from the common light source 35 and the light from the third light source 33 are both reflected at the spot where the unevenness has occurred, any value of R, B and infrared light is significantly increased compared to the normal value. Do. The light of the fourth light source 34 hardly transmits the inspection object 2 and is not received by the first imaging sensor 41.

  According to the configuration of the present embodiment described above, it is possible not only to discriminate between the surface foreign matter and the back surface foreign matter, but also in the case of the surface foreign matter, whether it is metal or nonmetal. Further, it is possible to determine the abnormality A, the abnormality B, and the pinhole defect. This makes it possible to distinguish between metal defects and pinhole defects that can become serious defects in secondary battery separators and other abnormalities, and suppress so-called oversight of inspection (overdetection) and increase product yield. be able to.

  Also in the present embodiment, the determination process of steps S201 to S203 of FIG. 12 may be replaced with the determination process of steps S201 'to S203' of FIG. In the determination process of step S208, instead of the "absolute value of the difference between the degree of reduction of the reflected infrared light and the reflected visible light", "the absolute value of the difference between the normalized pixel values of the reflected infrared light and the reflected visible light" You may use.

Example 6
FIG. 13 shows the configuration of the illumination system and measurement system of the sheet inspection apparatus 1 according to the sixth embodiment. In the sixth embodiment, the single imaging device 4 is configured by using a four-plate camera, and the second light source for transmitted visible light and the fourth light source for pinhole discrimination are constituted by one common light source 36. It is characterized by the point.

  As shown in FIG. 13, in the present embodiment, the imaging device 4 is disposed on the surface side (first surface side) of the inspection object 2, and the first light source 31 and the third light source 33 are on the surface side of the inspection object 2. Are arranged to emit light. Further, a common light source 36 serving as the second light source and the fourth light source is disposed to face the imaging device 4 with the inspection object 2 interposed therebetween. The common light source 36 is a light source capable of individually adjusting the light amount of each of blue light and white light, and irradiates the back surface of the inspection object 2 with light in which weak white light is superimposed on strong blue light. At this time, among the light emitted from the common light source 36, the blue light component corresponds to the light of the second light source, and the other wavelength components (red light and green light) correspond to the light of the fourth light source.

  As the imaging device 4, a four-plate camera having four image sensors of three colors of R, G, and B + infrared light can be used. At this time, two image sensors of R and G correspond to the first imaging sensor 41, an image sensor of B corresponds to the second imaging sensor 42, and an image sensor of infrared light corresponds to the third imaging sensor 43. .

  According to this configuration, since an image of reflected visible light, an image of reflected infrared light, and an image of transmitted visible light can be obtained, front / back judgment and metal / non-metal judgment can be performed as in the above-described embodiment. In addition, since an image having a plurality of colors of R and G can be obtained as an image of reflected visible light, in the case of a light defect, the pixel value of infrared light and the color balance of R and G are evaluated. Similarly to the above, determination of an abnormal A / abnormal B / pinhole defect can be performed. The configuration of the present embodiment is advantageous in that the same abnormality determination function as that of the fifth embodiment can be realized by a smaller device.

<Others>
The above examples merely illustrate the present invention, and the present invention is not limited to the above specific embodiments. The present invention can be modified in various ways within the scope of the technical idea. For example, the color components (wavelengths) listed in the above embodiments are merely examples, and light of other wavelengths may be used if it is possible to determine an abnormality. In the above embodiment, the process of detecting the abnormal part is first performed, and the process of discriminating the type of abnormality is applied only to the detected abnormal part, but the process of discriminating the type of abnormality is applied to the entire image. Good. For example, after the process of detecting the abnormal part and the process of determining the type of abnormality are executed in parallel, the same effect as that of the above embodiment can be obtained even if the results of both processes are combined.

1: sheet inspection device 2: inspection object 4: imaging device 5: processing device 31: first light source 32: second light source 33: third light source 34: fourth light source 35: common light source 36: common light source 41: first image sensor, 42: second image sensor, 43: third image sensor 51: first signal processor, 52: second signal processor, 53: third signal processor, 55: Alignment processing unit 56: abnormality detection unit 56A: detection threshold storage unit 57: determination unit 57A: determination threshold storage unit 58: output unit

Claims (13)

A sheet inspection apparatus for inspecting a sheet-like inspection object,
A first imaging sensor for imaging light emitted from the first light source and reflected by the first surface of the inspection object;
A second imaging sensor for imaging the light emitted from the second light source and transmitted through the inspection object;
An abnormal part on the inspection object is detected using the first image of the inspection object obtained by the first imaging sensor and the second image of the inspection object obtained by the second imaging sensor And a processing unit that determines the type of abnormality occurring at the detected abnormal point;
An output unit that outputs information related to an abnormal point, the output unit including at least information indicating an abnormality type determined by the processing unit;
When the pixel value of the first image and the pixel value of the second image are both lower than the normal value when there is no abnormality on the inspection object at the abnormal portion,
Wherein the processing unit, the abnormality occurring in previous SL anomaly is said or foreign matter into the first surface of the inspection object is a first surface contaminants adhered or contaminated, opposite to the first surface Determine whether the foreign matter is adhered to or mixed with the second face side or not .
The processing unit determines that the foreign substance is the first surface foreign substance when the degree of decrease of the pixel value of the first image with respect to the normal value is larger than the threshold value, and judges the foreign substance as the second surface foreign substance otherwise. Yes,
The sheet inspection apparatus , wherein the processing unit uses different threshold values in accordance with the degree of decrease of the pixel value of the second image with respect to the normal value . It further comprises a third imaging sensor for imaging the light emitted from the third light source and reflected by the inspection object,
The third imaging sensor is disposed on the first surface side of the inspection object,
The light emitted from the first light source is visible light,
The light emitted from the third light source is infrared light,
The processing unit uses the third image of the inspection object obtained by the third imaging sensor when the abnormality occurring at the abnormal part is the first surface foreign matter, and the first surface foreign matter The sheet inspection apparatus according to claim 1 , wherein it is determined whether the metal is a metal or a nonmetal. The processing unit is configured to generate the first surface foreign object when the degree of decrease of the pixel value of the first image with respect to the normal value and the degree of decrease of the pixel value of the third image with respect to the normal value are substantially the same. The sheet inspection apparatus according to claim 2 , wherein the sheet inspection apparatus is determined to be metal. It further has a fourth light source that emits light from the opposite side of the first imaging sensor across the inspection object,
The light emitted from the first light source and the light emitted from the fourth light source are lights having the same spectral distribution including a plurality of color components,
The pixels of the first image have pixel values for each of a plurality of color components,
When the pixel value of any color component of the first image or the value obtained by combining the pixel values of two or more color components at the abnormal point is increased compared to the normal value.
The processing section determines whether or not the abnormality occurring at the abnormal area is a pinhole defect, based on the balance of the color components of the first image at the abnormal area. The sheet inspection apparatus according to 2 or 3 . When the balance of color components of the first image at the abnormal portion is substantially the same as the balance of color components of the light emitted from the fourth light source, the processing unit generates the abnormality at the abnormal portion. The sheet inspection apparatus according to claim 4 , wherein the sheet inspection apparatus is determined to be a pinhole defect. The first imaging sensor configured to receive the light of the first light source, the second imaging sensor configured to receive the light of the second light source in one imaging device, and the second imaging sensor configured to receive the light of the second light source The sheet inspection apparatus according to claim 2 or 3 , further comprising: the third imaging sensor configured to receive light of a third light source. 7. The image pickup apparatus according to claim 6 , further comprising: a spectral element that divides one light path and guides light to each of the first image sensor, the second image sensor, and the third image sensor. Sheet inspection device. The imaging device is disposed on the first surface side of the inspection object;
The first light source and the third light source are disposed to emit light to the first surface side of the inspection object,
The second light source, the sheet inspection device according to claim 6 or 7, characterized in that it is arranged so as to face the image pickup device across the object to be inspected. The first imaging sensor configured to receive the light of the first light source and the light of the fourth light source in one imaging device, and the light configured to receive the light of the third light source A third imaging sensor is provided,
The imaging device is disposed on the first surface side of the inspection object;
The first light source and the third light source are disposed to emit light to the first surface side of the inspection object,
The fourth light source is disposed to face the imaging device with the inspection object interposed therebetween,
The first light source doubles as the second light source,
The second imaging sensor, the sheet inspection device according to claim 4 or 5, characterized in that it is arranged so as to face the first light source across the object to be inspected. The first imaging sensor configured to receive the light of the first light source and the light of the fourth light source in one imaging device, and the light configured to receive the light of the third light source A third imaging sensor is provided,
The imaging device is disposed on the first surface side of the inspection object;
The first light source and the third light source are disposed to emit light to the first surface side of the inspection object,
The fourth light source is disposed to face the imaging device with the inspection object interposed therebetween,
The third light source doubles as the second light source,
The sheet inspection apparatus according to claim 4 or 5 , wherein the second imaging sensor is disposed to face the third light source with the inspection object interposed therebetween. The first imaging sensor configured to receive the light from the first light source and the light from the fourth light source in one imaging device, and the light source configured to receive the light from the second light source A second imaging sensor and the third imaging sensor configured to receive light of the third light source;
The imaging device is disposed on the first surface side of the inspection object;
The first light source and the third light source are disposed to emit light to the first surface side of the inspection object,
The sheet inspection according to claim 4 or 5 , wherein a common light source serving as the second light source and the fourth light source is disposed to face the imaging device with the inspection object interposed therebetween. apparatus. The sheet inspection apparatus according to any one of claims 1 to 11 , wherein the light emitted from the second light source includes light of a blue wavelength. The sheet inspection apparatus according to any one of claims 1 to 12 , wherein the light emitted from the first light source includes light of a red wavelength.

Images