JP2005083906A - Defect detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defect detector for easily removing pseudo defect images generated by vibration, or the like and for preventing the erroneous detection of pseudo defects. <P>SOLUTION: An imaging line 7 of an object 1 to be inspected formed by a traverse slit reflection system imaging unit 19 is arranged slantingly to the relative travel direction between the object 1 to be inspected and the traverse slit reflection system imaging unit 19. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a plate-like or sheet-like specular or translucent acrylic plate, polycarbonate plate, liquid crystal glass plate or other surface irregularities or banks (excessive material supply of the subject to be examined). The present invention relates to an apparatus for detecting defects such as irregularities appearing in the rules), adhered foreign matter, and scratches.

  An object to be inspected, such as an acrylic plate manufactured by an extrusion molding machine, a polycarbonate plate, or a liquid crystal glass plate manufactured by a float method, is irradiated by illumination means, and reflected light reflected by the object to be inspected or the object to be inspected Defects such as surface irregularities, banks, attached foreign matter, and scratches are inspected by receiving the transmitted light that has passed through the object and performing image processing on the captured image captured by the imaging unit.

  For example, FIG. 1 of Japanese Patent Application Laid-Open No. 2002-1116015 (Patent Document 1) shows reflected light that is reflected from the surface of an object to be inspected by irradiating a stripe pattern having light and darkness from above the moving object to be inspected by an illumination device. Is detected by an imaging device and the captured image is analyzed to detect a defect of the object to be inspected.

  For example, as shown in FIG. 7A, a striped pattern having light and darkness is irradiated on the inspected object 1 by a long projector 5 arranged orthogonal to the conveyance direction a of the inspected object 1, When the transverse wave defect 2, the longitudinal wave defect 3, and the concave defect 4 on the inspection object 1 are imaged by the imaging means that does not perform, a captured image as shown in FIG. 7B is obtained. In FIG. 7B, 2a is a captured image of the transverse wave defect 2, 3a is a captured image of the longitudinal wave defect 3, and 4a is a captured image of the concave defect 4.

  When the Y-axis luminance value projection process is performed on the captured image shown in FIG. 7B, the defect peak waveform shown in FIG. 7C can be obtained. Here, the Y-axis luminance value projection processing is a graph of the peak value of the histogram obtained by adding the luminance values in the captured image shown in FIG. 7B on the Y-axis.

  Then, for example, by setting a predetermined threshold s for detecting the transverse wave defect 2 on the X axis in FIG. 7C, the transverse wave defect peak waveform 2c exceeding the threshold s is detected as the transverse wave defect 2. I can do it. Since the concave defect peak waveform 4c does not exceed the threshold s, it is not detected as a transverse wave defect. Separately, by setting a predetermined threshold (not shown) for detecting the concave defect 4, the concave defect peak waveform 4c exceeding the threshold is set. Can be detected as the concave defect 4.

JP 2002-1116015 A (FIG. 1)

  However, in the technique of the above-mentioned Patent Document 1, when the object to be inspected 1, the projector 5, the imaging device, etc. vibrate for some reason, for example, as shown in FIG. As shown in b), a pseudo defect image 6a in which light and dark according to the vibration frequency appear alternately is captured simultaneously.

  That is, if vibration occurs in the inspection object 1 at the vibration point A in FIG. 7A, the object 1 is irradiated by the projector 5 because it vibrates simultaneously on the imaging line 7 of the inspection object 1. As shown in FIG. 7B, the pseudo-defective image 6a in which the light and darkness along the imaging line 7 occurs in the captured image is captured. When such a pseudo defect image 6a is simultaneously subjected to Y-axis luminance value projection processing, as shown in FIG. 7C, a pseudo defect peak waveform 6c exceeding the threshold s for detecting the transverse wave defect 2 is used as a pseudo defect. There was a problem of false detection.

  The present invention solves the above-mentioned problems, and its object is to provide a defect detection device that can easily remove a false defect image caused by vibrations and prevent false detection of a false defect. It is what.

  In order to achieve the above object, a defect detection apparatus according to the present invention includes an illuminating unit that illuminates a plate-shaped or sheet-shaped object to be inspected, and reflected light that is illuminated by the illuminating unit and reflected by the object to be inspected. An imaging unit having an imaging unit that receives and captures transmitted light that has passed through the inspection object; and a defect detection unit that analyzes an image captured by the imaging unit and detects a defect of the inspection object. The imaging line of the inspected object formed by the imaging unit is arranged to be inclined with respect to the relative movement direction of the inspected object and the imaging unit.

  Since the present invention is configured as described above, the imaging line of the inspection object formed by the imaging unit is arranged to be inclined with respect to the relative movement direction of the inspection object and the imaging unit. , Transverse wave defects other than longitudinal wave defects parallel to the relative movement direction of the object to be inspected and the imaging unit, surface irregularities and banks having a two-dimensional area (material supply of the object to be inspected) When various defects such as irregular defects appearing irregularly due to excess, etc.), adhering foreign matter, scratches, etc. are imaged by the imaging means, the captured image is inclined with respect to the relative movement direction of the object to be inspected and the imaging unit An image is taken with an inclination angle corresponding to the angle.

  On the other hand, a pseudo defect image generated by vibration or the like is a pseudo defect image in which brightness and darkness occurs in a direction orthogonal to the relative movement direction of the object to be inspected and the imaging unit regardless of the inclination angle of the imaging line. Is imaged.

  As a result, the surface wave defects present on the object to be inspected, surface irregularities or banks having a two-dimensional area, irregularities appearing irregularly due to excessive material supply of the object to be inspected, actual foreign objects such as adhered foreign matter, scratches, etc. By changing the direction of the defect image and the pseudo defect image generated by vibration or the like, the image processing can be easily distinguished and the pseudo defect image can be easily and accurately removed.

  In the imaging unit, the illumination unit and the imaging unit may be configured integrally or may be configured separately. However, when the object to be inspected is fixed in a stationary state, a pair of illumination units constituting the imaging unit The imaging means can move integrally with the object to be inspected fixed in a stationary state.

  In addition, when the pair of illumination means and the imaging means constituting the imaging unit are fixed in a stationary state, an inspected object conveying means for conveying the plate-like or sheet-like inspected object is provided, and the inspected object conveying means The imaging line of the object to be inspected formed by the imaging unit can be inclined with respect to the conveyance direction of the object to be inspected conveyed by the above.

  In addition, the longitudinal direction or the arrangement direction of the illumination means is arranged to be inclined with respect to the relative movement direction between the object to be inspected and the imaging unit, thereby imaging the object to be inspected formed by the imaging unit. The line can be inclined.

  In addition, the imaging unit is a line sensor, and the longitudinal direction or the arrangement direction of the line sensor is arranged so as to be inclined with respect to the relative moving direction of the object to be inspected and the imaging unit, whereby the imaging unit The imaging line of the object to be inspected formed by the above can be inclined and arranged.

  Further, the illumination means can irradiate the object to be inspected with a stripe pattern having alternating brightness. If the object to be inspected has no defect and the surface is flat, the light / dark cycle of the stripe pattern imaged by the imaging means will not change, and if the object to be inspected has a defect and the surface is uneven, The light-dark cycle of the stripe pattern imaged by the imaging means changes in the uneven part. By measuring the shift amount of the light / dark cycle, it is possible to detect the defect of the inspection object.

  The illuminating means may irradiate the object to be inspected with a lattice pattern (checkered flag pattern pattern) alternately having light and dark instead of the stripe pattern, and if the object to be inspected has no defect and is flat. For example, if the light-dark cycle of the grid pattern imaged by the imaging means does not change and there is a defect on the object to be inspected and the surface is uneven, the grid imaged by the imaging means at the uneven portion The light / dark cycle of the pattern changes. By measuring the shift amount of the light / dark cycle, it is possible to detect the defect of the inspection object.

  In addition, the defect detection unit is configured to incline an imaging line of the inspection object formed by the imaging unit with respect to a moving direction of the inspection object and the imaging unit relative to a captured image captured by the imaging unit. It is characterized in that a pseudo defect image generated by vibration or the like is removed by performing coordinate conversion corresponding to an angle.

  In the picked-up image picked up by the image pickup means, a surface having a two-dimensional area or a transverse wave defect other than a longitudinal wave defect parallel to the relative movement direction of the object to be inspected and the image pickup unit. The captured images of various defects such as irregularities and banks (irregular defects appearing irregularly due to excessive material supply of the object to be inspected), adhering foreign matter, scratches, etc., are relative to the relative movement direction of the object to be inspected and the imaging unit. Images are taken with an inclination angle corresponding to the inclination angle of the imaging line.

  On the other hand, a pseudo defect image generated by vibration or the like is captured along a direction orthogonal to the relative movement direction of the object to be inspected and the imaging unit regardless of the inclination angle of the imaging line.

  Then, by performing coordinate conversion corresponding to the inclination angle of the imaging line of the object to be inspected formed by the imaging unit with respect to the relative moving direction of the object to be inspected and the imaging unit, A transverse wave defect other than a longitudinal wave defect parallel to the relative movement direction of the object to be inspected and the imaging unit existing on the object, a surface unevenness or bank having a two-dimensional area (due to excessive material supply of the object to be inspected, etc.) The captured images of various defects such as irregular irregularities appearing irregularly, attached foreign matter, and scratches are coordinate-transformed in a direction orthogonal to the relative movement direction of the object to be inspected and the imaging unit.

  On the other hand, the pseudo defect image generated by vibration or the like has an inclination angle corresponding to the inclination angle of the imaging line of the inspection object formed by the imaging unit with respect to the relative movement direction of the inspection object and the imaging unit. Coordinate conversion.

  Then, the histogram peak value obtained by adding the luminance in the coordinate-converted image to the direction orthogonal to the relative movement direction of the object to be inspected and the imaging unit is graphed. Transverse wave defects other than longitudinal wave defects parallel to the relative movement direction, surface irregularities and banks having a two-dimensional area (irregular defects appearing irregularly due to excessive material supply of the object to be inspected), adhered foreign matter, scratches By setting a predetermined threshold value for detecting various defects such as the above, a defect peak waveform exceeding the threshold value can be detected as a defect.

  On the other hand, since the pseudo defect image generated by vibration or the like is coordinate-transformed by being inclined with respect to a direction orthogonal to the relative movement direction of the object to be inspected and the imaging unit, the relative relationship between the object to be inspected and the imaging unit is relatively small. The peak value of the histogram added in the direction perpendicular to the moving direction becomes small and does not exceed the threshold value, so that it is not detected as a defect, and thereby the pseudo defect image can be easily and accurately removed.

  Since the present invention has the above-described configuration and operation, it is possible to easily remove a pseudo defect image generated by vibration or the like and prevent false detection of a pseudo defect.

  An embodiment of the defect detection apparatus according to the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of the defect detection apparatus according to the present invention, FIG. 2 is a block diagram showing the configuration of the control system of the defect detection apparatus according to the present invention, and FIG. FIG. 4 to FIG. 6 are diagrams illustrating a state in which a pseudo defect image is removed, and FIGS. 4 to 6 are diagrams illustrating a state in which various defects are detected.

  In FIG. 1, it is manufactured by a transparent or translucent transparent, translucent or opaque acrylic plate, polycarbonate plate, float method or the like that is continuously extruded and formed into a plate or sheet by an extruder 8. The object 1 to be inspected, such as a liquid crystal glass plate, is shown by a to-be-inspected object conveying means such as a pair of drive rollers 9 and 10 for nipping and conveying the object 1 to be inspected and a driven roller 11 for conveying while supporting the lower surface. 1 is conveyed in the direction of arrow a.

  On the downstream side (hereinafter simply referred to as “downstream side”) of the object 1 to be inspected 1 of the extrusion molding machine 8, vertical slits are provided, and stripes in the vertical direction (in the direction of conveyance of the object 1 to be inspected) alternately. A projector 12 composed of a long fluorescent lamp as illumination means for irradiating the pattern vertically upward from the lower surface side of the object 1 to be inspected, and an imaging means provided on the opposite side of the projector 12 through the object 1 to be inspected A vertical slit transmission system imaging unit 14 having a light receiver 13 having a CCD (charge coupled device) camera 13a is provided. The vertical slit transmission imaging unit 14 receives and images the transmitted light that passes through the surface of the inspection object 1 in the vertical direction by the light receiver 13 and detects a defect of the inspection object 1 described later in detail.

  In the vertical slit transmission system imaging unit 14, the projector 12 is arranged on the upper surface side of the object 1 to be inspected, irradiated obliquely downward from the upper surface side of the object 1 to be inspected, and reflected light reflected on the upper surface of the object 1 to be inspected. Can be received and imaged by the light receiver 13 to detect a defect of the object 1 to be inspected.

  On the downstream side of the longitudinal slit transmission system imaging unit 14, a projector 15 made of a long fluorescent lamp serving as an illumination means for irradiating obliquely upward from the lower surface side of the inspected object 1 without a slit, and the inspected object 1 A lower surface reflection system imaging unit 17 having a light receiver 16 having a CCD camera 16a serving as an imaging means provided on the lower surface side is provided. The lower surface reflection system imaging unit 17 receives the reflected light vertically reflected on the lower surface of the object 1 to be inspected by the light receiver 16 and images it, and detects a defect of the object 1 to be described later in detail.

  On the downstream side of the lower surface reflection system imaging unit 17, a horizontal slit is provided, and a stripe pattern in the horizontal direction (direction perpendicular to the conveyance direction of the object 1 to be inspected) is alternately inclined from the upper surface side of the object 1 to be inspected. Transverse slit reflection system having a projector 5 made of a long fluorescent lamp serving as an illuminating means for irradiating in a direction, and a light receiver 18 having a CCD camera 18a serving as an imaging means provided on the upper surface side of the inspected object 1. An imaging unit 19 is provided. The horizontal slit reflection imaging unit 19 receives the reflected light reflected on the upper surface of the inspection object 1 by the light receiver 18 and picks up an image, and detects a defect of the inspection object 1 described later in detail.

  The projector 5 of the horizontal slit reflection imaging unit 19 is arranged at a twisted position with respect to the object 1 to be inspected. That is, the imaging line 7 of the inspected object 1 formed on the inspected object 1 by the lateral slit reflection system imaging unit 19 comprising the projector 5 and the light receiver 18 is the inspected object 1 and the lateral slit reflection system imaging unit 19. Are inclined with respect to the conveyance direction a of the object 1 to be inspected, which is a relative movement direction.

  In the present embodiment, the object to be inspected 1 is transported such that the longitudinal direction of the projector 5 made of a long fluorescent lamp serving as an illuminating means is the relative movement direction of the object to be inspected 1 and the horizontal slit reflection imaging unit 19. It is arranged to be inclined with respect to the direction a. In the case where the projector 5 is composed of a plurality of point light sources, the arrangement direction of the point light sources is the relative movement direction between the object to be inspected 1 and the horizontal slit reflection imaging unit 19 and the transport direction a of the object to be inspected a Inclined with respect to.

  In FIG. 1, the imaging line 20 of the inspection object 1 formed on the inspection object 1 by the vertical slit transmission system imaging unit 14 including the projector 12 and the light receiver 13, the projector 15, and the light receiver 16. The imaging line 21 of the inspection object 1 formed on the inspection object 1 by the lower surface reflection system imaging unit 17 is arranged in a direction orthogonal to the conveyance direction a of the inspection object 1.

  In this embodiment, the inclination angle of the imaging line 7 of the inspected object 1 formed on the inspected object 1 by the horizontal slit reflection imaging unit 19 with respect to the direction orthogonal to the conveyance direction a of the inspected object 1 is set. The illumination optical axis of the light projector 5 and the light reception axis of the light receiver 18 are set at a predetermined angle with respect to the surface of the object 1 to be inspected, and the light axis of the light projector 15 of the bottom reflective imaging unit 17 is set. And the light receiving axis of the light receiver 16 is set to a predetermined angle.

  In the case where the imaging means is constituted by a line sensor, the longitudinal direction or the arrangement direction of the line sensor is the relative moving direction of the inspection object 1 and the lateral slit reflection system imaging unit 19 of the inspection object 1. The imaging line 7 of the inspected object 1 formed on the inspected object 1 by the horizontal slit reflection imaging unit 19 is arranged in the conveying direction a of the inspected object 1 by being inclined with respect to the conveying direction a. It can be arranged to be inclined.

  FIG. 2 is a block diagram showing the configuration of the control system of the defect detection apparatus according to the present invention. The captured image composed of analog values captured by the CCD cameras 13a, 16a, 18a of the respective light receivers 13, 16, 18 is It is converted into a digital value by an A / D (analog / digital) converter 22 and stored in an image memory 23 which is a storage means.

  The image calculation control unit 24 serving as the defect detection means images the object 1 to be inspected by the CCD cameras 13a, 16a, and 18a of the light receivers 13, 16, and 18 serving as image capturing means, and the analog image thus captured is A / D. A digital image is converted by the conversion unit 22, a predetermined image processing program is executed on the digital image stored in the image memory 23, and the digital image is analyzed to detect a defect in the inspection object 1.

  The defect information detected by the image calculation control unit 24 is displayed on the operation / display panel 27, and the defect information is output as a result signal by the result signal output unit 25. Further, the communication is output to the outside by the upper communication unit 26.

  Further, by operating the operation / display panel 27, the projectors 5, 12, 15 serving as illumination means constituting the respective imaging units by the external device control unit 28 via the image calculation control unit 24 and the light receiver serving as the imaging means. 13, 16, 18 can be controlled.

  The image calculation control unit 24 serving as the defect detection means captures an image with the light receiver 18 serving as the image capturing means of the horizontal slit reflection image capturing unit 19 in which the image capturing line 7 is inclined with respect to the transport direction a of the inspection object 1. A digital image obtained by digitally converting the analog captured image obtained by the A / D conversion unit 22 is subjected to coordinate conversion corresponding to the inclination angle of the imaging line 7, and a pseudo defect image 6a generated by vibration or the like (see FIG. 3B). Remove.

  For example, as shown in FIG. 3A, an illuminating unit arranged with an inclination angle Θ with respect to a direction (width direction of the inspection object 1) orthogonal to the conveyance direction a of the inspection object 1 An inspected object 1 is irradiated with a stripe pattern in a horizontal direction (direction perpendicular to the conveying direction of the object 1 to be inspected) alternately provided with a horizontal slit by a long projector 5 such as a fluorescent lamp. When the transverse wave defect 2, longitudinal wave defect 3 and concave defect 4 on the inspected object 1 are imaged by the light receiver 18 as means, a captured image as shown in FIG. 3B is obtained.

  In FIG. 3B, 2a is a captured image of the transverse wave defect 2, 3a is a captured image of the longitudinal wave defect 3, and 4a is a captured image of the concave defect 4. These captured images are shown in FIG. 3B according to the transport speed of the object to be inspected 1 conveyed by the pair of drive rollers 9 and 10 serving as the object to be inspected when the image capturing line 7 is arranged at an inclination. A time delay occurs in the X direction (the width direction of the object 1 to be inspected), and the image is captured as an image inclined according to the inclination angle Θ of the imaging line 7.

  Here, when the inspected object 1, the projector 5, the light receiver 18, etc. vibrate for some reason, for example, as shown in FIG. A pseudo defect image 6a in which brightness and darkness corresponding to the vibration frequency appear alternately is captured simultaneously.

  That is, if vibration occurs in the inspection object 1 at the vibration point A in FIG. 3A, the imaging line 7 of the inspection object 1 vibrates at the same time. In addition, the light and dark of the stripe pattern having the light and darkness irradiated to the object 1 to be inspected by the projector 5 alternately cross, and as shown in FIG. 7B, the captured image is displayed in the X direction (of the object 1 to be inspected) in FIG. A pseudo defect image 6a in which brightness and darkness along the width direction) is generated is captured.

  In this way, the imaging line 7 of the horizontal slit reflection system imaging unit 19 is moved with respect to the conveyance direction a of the inspection object 1 which is the relative movement direction of the inspection object 1 and the horizontal slit reflection system imaging unit 19. By being arranged at an inclination, the picked-up image 2a of the transverse wave defect 2 and the picked-up image 4a of the concave defect 4 are picked up as an image inclined according to the inclination angle Θ of the image pickup line 7, but a pseudo defect caused by vibration or the like Since the image 6a is picked up as an image along the X direction (the width direction of the inspection object 1) in FIG. 7B, the actual defect images 2a and 4a on the inspection object 1 are simulated and generated by vibrations or the like. The defect image 6a can be easily separated, and the pseudo defect image 6a caused by vibration or the like can be easily removed by performing a predetermined image analysis.

  For example, assuming that the inclination angle of the imaging line 7 of the horizontal slit reflection imaging unit 19 is Θ, the coordinates before conversion are X and Y, and the coordinates after coordinate conversion are X ′ and Y ′, The captured images 2a, 3a, 4a, and 6a shown in b) can be coordinate-converted into the post-coordinate-converted images 2b, 3b, 4b, and 6b shown in FIG.

  When the Y-axis luminance value projection process is performed on the image after coordinate conversion shown in FIG. 3C, the defect peak waveform shown in FIG. 3D can be obtained. Here, the Y-axis luminance value projection processing is a graph of the peak value of the histogram obtained by adding the luminance value in the image after coordinate conversion shown in FIG. 3C on the Y-axis.

  Then, for example, by setting a predetermined threshold value s for detecting the transverse wave defect 2 on the X axis in FIG. 3D, the transverse wave defect peak waveform 2 c exceeding the threshold value s is detected as the transverse wave defect 2. I can do it. Since the concave defect peak waveform 4c does not exceed the threshold s, it is not detected as a transverse wave defect. Separately, by setting a predetermined threshold (not shown) for detecting the concave defect 4, the concave defect peak waveform 4c exceeding the threshold is detected. Can be detected as the concave defect 4.

  When the coordinate-transformed image 6b of the pseudo defect in the image after coordinate transformation shown in FIG. 3C is simultaneously subjected to the Y-axis luminance value projection processing, the coordinate-transformed image 6b of the pseudo defect is coordinate-transformed as an oblique line. As shown in the pseudo defect peak waveform 6c in FIG. 3D, the peak value of the histogram obtained by adding the luminance value on the Y axis is also small.

  Therefore, since the pseudo defect peak waveform 6c does not exceed the threshold value s for detecting the transverse wave defect 2 as in the conventional example shown in FIG. 7 and described above, the false defect image 6a is not erroneously detected as a defect.

  As described above, after removing the pseudo defect image 6a caused by vibration or the like, a filtered image C in which brightness and darkness are uniformed by filtering the captured image B shown in FIG. 4 with a bandpass filter that passes only a specific frequency band. Get.

  Next, in order to detect the transverse wave defect 2, the Y direction differential image D obtained by performing the differentiation in the Y direction of FIG. 4 on the filter image C to remove the longitudinal wave defect image 3a is obtained. Then, Y-axis luminance value projection processing is performed from the Y-direction differential image D to obtain a Y-axis luminance value projection histogram E. The Y-axis luminance value projection histogram E is evaluated to detect the transverse wave defect 2.

  Similarly, in order to detect the longitudinal wave defect 3, the X-direction differential image F obtained by performing the differentiation in the X direction of FIG. 4 on the filter image C and removing the transverse wave defect image 2a is obtained. Then, an X-axis luminance value projection histogram G is obtained from the X-direction differential image F by performing an X-axis luminance value projection process. The X-axis luminance value projection histogram G is evaluated to detect the longitudinal wave defect 3.

  Next, in order to detect the concave defect 4, the X-direction differential image F is binarized to obtain a binarized image I. On the other hand, in the X-axis luminance value projection histogram G, a mask threshold value m for extracting only the longitudinal wave defect image 3a is set, and the mask threshold value m is determined from the X-axis luminance value projection histogram G of the X-axis luminance value projection. A mask image H in which the longitudinal wave defect mask 29 is generated according to the position of the histogram that exceeds is obtained. Then, the binarized image I is masked with the mask image H to obtain a concave defect extraction image J. The area of the extracted image is obtained from the recessed defect extracted image J, and is recognized as the recessed defect 4 when the area is equal to or larger than a predetermined area.

  FIG. 5 is a diagram showing a state in which a bank (irregular defect appearing irregularly due to excessive material supply of the object to be inspected) defect is detected by the vertical slit transmission system imaging unit 14. First, the captured image K including the bank defect image shown in FIG. 5 is filtered by a band-pass filter that passes only a specific frequency band to obtain a filter image L with uniform brightness.

  Next, in order to detect a bank defect, the filter image L is differentiated in the Y direction of FIG. Then, the Y-direction differential image M is binarized to obtain a binarized image N. An area is obtained from the binarized image N, and when the area is equal to or larger than a predetermined area, it is recognized as a bank defect.

  FIG. 6 is a diagram showing a state in which an attached foreign matter and a flaw defect are detected by the lower surface reflection system imaging unit 17. First, a filtered image P having a uniform brightness is obtained by filtering the captured image O including the adhered foreign matter and flaw defect image shown in FIG. 6 with a bandpass filter that passes only a specific frequency band.

  Next, in order to detect adhered foreign matter and scratch defects, the filter image P is differentiated in both the X and Y directions in FIG. Then, the binarized image R is obtained by binarizing the XY direction differential image Q. The binarized image R is temporarily subjected to image contraction processing to remove the noise image 30 in the binarized image R, and then subjected to image expansion processing to restore the attached foreign matter or scratch defect image to the original size. After that, an area is obtained, and when the area is equal to or larger than a predetermined area, it is recognized as an attached foreign matter or a flaw defect.

  In the above-described embodiment, the case where the object to be inspected 1 is transported by the object to be inspected such as the drive roller pair 9 and 10 and the horizontal slit reflection imaging unit 19 is fixed in a stationary state has been described. The inspection object 1 may be fixed in a stationary state, and the horizontal slit reflection imaging unit 19 may be moved and scanned with respect to the inspection object 1 fixed in a stationary state.

  Moreover, in the said embodiment, an example at the time of arrange | positioning the imaging line 7 of the horizontal slit reflection type imaging unit 19 inclining with respect to the relative moving direction of the to-be-inspected object 1 and the horizontal slit reflection type imaging unit 19 is arrange | positioned. As described above, the imaging lines 20 and 21 of the vertical slit transmission imaging unit 14 and the bottom reflection imaging unit 17 are inclined with respect to the relative movement direction of the object 1 to be inspected and the horizontal slit reflection imaging unit 19. It can also be arranged.

  As an application example of the present invention, it is produced by a transparent or translucent, opaque acrylic plate, polycarbonate plate or float method having a specular or translucent plate shape or sheet shape continuously produced by an extrusion molding machine. Applicable to devices that detect defects such as surface irregularities, banks (irregular defects appearing irregularly due to excessive material supply of the object to be inspected), adhered foreign matter, scratches, etc. present on the inspected object such as liquid crystal glass plates . Further, the present invention can also be applied to an apparatus that detects a defect existing in an object to be inspected by moving and scanning an imaging unit including an illumination unit and an imaging unit with respect to the object to be inspected fixed in a stationary state.

It is a schematic diagram which shows the whole structure of the defect detection apparatus which concerns on this invention. It is a block diagram which shows the structure of the control system of the defect detection apparatus which concerns on this invention. It is a figure which shows a mode that the pseudo defect image produced by the vibration etc. by the defect detection means is removed. It is a figure which shows a mode that various defects are detected. It is a figure which shows a mode that various defects are detected. It is a figure which shows a mode that various defects are detected. It is a figure explaining the subject of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Object to be inspected 2 ... Transverse wave defect 2a ... Transverse wave defect image 2b ... Transverse wave defect coordinate converted image 2c ... Transverse wave defect peak waveform 3 ... Longitudinal wave defect 3a ... Longitudinal wave defect image 3b ... Longitudinal wave defect coordinate transformed image DESCRIPTION OF SYMBOLS 4 ... Concave defect 4a ... Concave defect image 4b ... Image after coordinate conversion of concave defect 4c ... Concave defect peak waveform 5 ... Projector 6a ... Pseudo defect image 6b ... Image after pseudo defect coordinate conversion 6c ... Pseudo defect peak waveform 7 ... Imaging Line 8 ... Extruder 9,10 ... Drive roller pair
11 ... driven roller
12 ... Floodlight
13 ... Receiver
13a ... CCD camera
14… Vertical slit transmission system imaging unit
15 ... Floodlight
16 ... receiver
16a ... CCD camera
17… Lower reflection imaging unit
18 ... Receiver
18a ... CCD camera
19… Horizontal slit reflection imaging unit
20, 21 ... Imaging line
22 ... A / D converter
23 ... Image memory
24 ... Image calculation control unit
25. Result signal output section
26… High-level communication department
27 ... Operation / display panel
28… External device control unit
29 Longitudinal wave defect mask
30 ... Noise image B ... Captured image C ... Filter image D ... Y-direction differential image E ... Y-axis brightness value projection histogram F ... X-axis brightness value projection histogram G ... X-axis brightness value projection histogram H ... Mask image I ... Binary image J ... Concave defect extraction image K ... Captured image L ... Filter image M ... Y-direction differential image N ... Binary image O ... Captured image P ... Filter image Q ... XY-direction differential image R ... Binary image

Claims (5)

Illuminating means for illuminating a plate-like or sheet-like object to be inspected, and imaging means for receiving and imaging reflected light that is illuminated by the illuminating means and reflected by the inspected object or transmitted through the inspected object; An imaging unit having
A defect detection unit that analyzes an image captured by the imaging unit and detects a defect of the inspection object;
Have
A defect detection apparatus, wherein an imaging line of the inspection object formed by the imaging unit is arranged to be inclined with respect to a relative movement direction of the inspection object and the imaging unit. The defect detection apparatus according to claim 1, wherein a longitudinal direction or an arrangement direction of the illumination unit is arranged to be inclined with respect to a relative movement direction of the object to be inspected and the imaging unit. The image pickup means is a line sensor, and a longitudinal direction or an arrangement direction of the line sensor is arranged to be inclined with respect to a relative movement direction of the object to be inspected and the image pickup unit. Item 2. The defect detection apparatus according to Item 1. The defect detection apparatus according to claim 1, wherein the illuminating unit irradiates the object to be inspected with a stripe pattern or a lattice pattern having light and shade alternately. The defect detection means converts the picked-up image picked up by the pick-up means to an inclination angle of an image pickup line of the inspection object formed by the imaging unit with respect to a relative movement direction of the inspection object and the imaging unit. 5. The defect detection apparatus according to claim 1, wherein a pseudo defect image generated by vibration or the like is removed by performing corresponding coordinate transformation.

Images