JP5297245B2 - Object surface inspection equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an object surface inspection apparatus capable of clearly detecting a difference of glossiness at an inspected surface of an object surface. <P>SOLUTION: The object surface inspection apparatus includes an irradiation device 2 which irradiates an inspected surface 51 with line-like inspection light from a direction crossly intersecting with a normal line direction L1 of an inspected surface 51 of an inspected object 50; an imaging device 3 which is equipped with a light receiving element disposed in line-like, is arranged so that an angle &delta;2 between a light-receiving optical axis L3 of the light receiving element and the normal line direction of the inspected surface 51 is equal to an angle &delta;1 between a light projection optical axis L2 of the irradiation device 2 and the normal line direction L1 of the inspected surface 51, and images the inspected surface 51; in which the irradiation device 2 and the imaging device 3 are arranged so that the extending direction of the line-like inspection light and the extending direction L4 of a line-like visual field A intersect crossly to a conveying direction L5 of the inspected object 50 by a conveyer 4 at same angles &theta;1 and &theta;2 respectively. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an object surface inspection apparatus that inspects an inspection surface by irradiating an inspection surface of an inspection object with light and analyzing an image obtained by imaging the inspection surface.

  Generally, as an inspection device that measures the glossiness of the surface (inspection surface) of an inspection object, light is applied to the inspection surface from a light source whose angle between the normal direction of the inspection surface and the projection optical axis is about 45 degrees. The regular reflected light reflected by the inspection surface is imaged by the imaging means whose angle between the normal direction of the inspection surface and the light receiving optical axis is about 45 degrees, and the gloss of the inspection surface is obtained from the captured image of the imaging means. There was something to observe the degree.

  Further, as shown in Patent Document 1, a light source is arranged obliquely above one side of the inspection object, and illumination light is irradiated from the light source to the inspection surface at a shallow incident angle, and the other side of the inspection object is oblique. There has also been proposed an inspection method in which an imaging device is arranged above and an inspection surface is imaged at a shallow imaging angle so that foreign matters and protrusions on the inspection surface are captured as shadows.

JP-A-8-5573

  By the way, in the case of flooring manufactured by stacking the veneer on the plywood coated with adhesive and then pressing the veneer against the plywood with a smooth pressure plate, the adhesive is directly pressed against the pressure plate at the location where the veneer is damaged. As a result, a smooth surface is formed, and gloss is partially produced. In addition, a scratch or the like on the surface of the metal plate may cause a portion having a higher gloss than the surrounding portion. Using the above-described conventional inspection method, a portion having a higher gloss is treated as a gloss. There is a demand to discriminate from low rough surfaces.

  However, it is easy to scatter and reflect light in a specific direction and light in another direction, such as a plate material such as a flooring or a metal plate whose surface has been subjected to fine irregularities such as hairline processing. In the case of an inspection object having a surface property that is likely to be regularly reflected, it is necessary to observe the inspection object from the direction in which light is scattered and reflected in order to clearly detect the difference in glossiness of the surface. Here, in a manufacturing site of a large material such as a flooring material or a metal plate, it is composed of the flooring material or the metal plate after the step of bonding the protruding plate to the surface of the plywood or the step of performing the uneven processing on the surface of the metal plate. When the surface of the inspection object is irradiated with line light extending in a direction perpendicular to the conveyance direction and the surface of the object is imaged with a line camera to perform surface inspection, the floor material or the metal plate is conveyed and moved. Since the direction in which the scattering reflection is maximum does not necessarily match, if the imaging device is installed with the imaging direction aligned with the transport direction, the inspection object cannot be observed from the direction in which the scattering reflection is maximum. There was a case.

  The present invention has been made in view of the above problems, and an object thereof is to provide an object surface inspection apparatus capable of clearly detecting a difference in glossiness on an inspection surface of an object surface.

In order to achieve the above object, the invention of claim 1 is directed to an illumination means for irradiating the inspection surface with linear inspection light from a direction obliquely intersecting with the normal direction of the inspection surface of the inspection object, The light receiving element is arranged and the angle formed between the light receiving optical axis of the light receiving element and the normal direction of the inspection surface is the same as the angle formed between the light projecting optical axis of the illumination means and the normal direction of the inspection surface. An imaging unit arranged to image the inspection surface and an inspection processing unit that inspects the inspection surface by analyzing an image captured by the imaging unit, and the illumination unit and the imaging unit extend line-shaped inspection light. the extending direction of the direction and linear imaging region, the moving direction of the inspection object with respect to the illumination means and the imaging means moves relative, is arranged such that intersect obliquely at the same angle, the line Direction of the inspection light An angle measuring unit that measures an angle formed by the extending direction of the line-shaped imaging region and a moving direction, an image correcting unit that corrects deformation of an image captured by the imaging unit based on a measurement result of the angle measuring unit, and an inspection surface And a storage unit for storing a first threshold value for luminance and a second threshold value for the amount of change in luminance, which are used to detect a glossy change part that suddenly changes in the direction in which the glossiness increases. A bright portion extraction function for inspecting the inspection surface by analyzing the image after correction by the image processing means, wherein the inspection processing means extracts a region having a brightness higher than the first threshold as a bright portion from the captured image of the inspection surface; The average value of luminance is obtained for each of the bright part and the peripheral part of the bright part, and when the luminance difference between the average value of the luminance in the bright part and the average value of the luminance in the peripheral part is larger than the second threshold value, it is determined as the gloss changing part. Gloss change size Characterized in that it comprises a function.

According to a second aspect of the present invention, in the first aspect of the present invention, a third threshold value for luminance and a fourth threshold value for the amount of change in luminance used for detecting a glossy change portion that suddenly changes in the direction of decreasing glossiness on the inspection surface. the storage unit stores, inspection processing means, and the dark extracting function of extracting a region luminance is lower than the third threshold value from the captured image of the inspection surface as dark portions, the dark portion and the dark respectively between the peripheral area brightness average value And a gloss change determining function that determines that the brightness difference between the average brightness value in the dark area and the average brightness value in the peripheral area is larger than the fourth threshold value as the gloss change section.

The invention of claim 3 comprises illumination means for irradiating the inspection surface with line-shaped inspection light from a direction obliquely intersecting the normal direction of the inspection surface of the inspection object, and light receiving elements arranged in a line. The inspection surface is picked up so that the angle formed by the light receiving optical axis of the light receiving element and the normal direction of the inspection surface is the same as the angle formed by the projection optical axis of the illumination means and the normal direction of the inspection surface. An imaging unit; and an inspection processing unit that inspects an inspection surface by analyzing an image captured by the imaging unit. The illumination unit and the imaging unit are configured to extend the line-shaped inspection light and the line-shaped imaging region. The extending direction is arranged so as to cross obliquely at the same angle with respect to the moving direction in which the inspection object moves relative to the illumination unit and the imaging unit, and the extending direction and the line of the line-shaped inspection light Of the imaging area And angle measuring means for direction to measure the angle formed by the direction of movement that the image correcting means for imaging means to correct the deformation of an image captured based on the measurement result of the angle measuring means, the direction in which the glossiness is decreased in the inspection surface And a storage unit for storing a third threshold value for luminance and a fourth threshold value for the amount of change in luminance used to detect a glossy change part that suddenly changes , and the inspection processing unit analyzes the image corrected by the image correction unit. Inspecting the inspection surface, the inspection processing means respectively extracts a dark portion extraction function that extracts a region having a luminance lower than the third threshold from the captured image of the inspection surface as a dark portion, and a dark portion and a peripheral portion of the dark portion, respectively. A gloss change determining function for obtaining an average value of brightness, and determining that the brightness difference between the average value of brightness in the dark part and the average value of brightness in the peripheral part is greater than a fourth threshold value as a gloss change part. And butterflies.

A fourth aspect of the invention is characterized in that, in any one of the first to third aspects of the invention, the illuminating means includes a light source that irradiates a line-shaped parallel light onto the inspection surface.

According to the first and third aspects of the present invention, the illumination means irradiates the line-shaped inspection light from a direction obliquely intersecting the normal direction of the inspection surface. Inspection light is not inserted into the bottom side, and inspection light is irradiated only on the tip side of the convex portion, and the imaging means has an angle formed between the light receiving optical axis of the light receiving element and the normal direction of the inspection surface. Since it is arranged to be at the same angle as the angle between the light projection optical axis of the illumination means and the normal direction of the inspection surface, the imaging device receives the light component regularly reflected by the tip of the convex portion of the inspection surface Can do. Therefore, the amount of received light proportional to the regular reflectance of the inspection surface can be obtained without being affected by the pattern of the inspection surface and the surrounding stray light reflected by the inspection surface, so that the glossiness of the inspection surface can be detected correctly. . Furthermore, light is easily scattered and reflected in a specific direction, such as wood with a veneer with wood grain and a metal plate with hairline processing, and regular reflection of light in another direction. When inspecting inspection objects with surface properties that are easy to do, when the direction of maximum scattering reflection is parallel to the direction of movement, depending on the direction of movement when moving the product after the pasting process or hairline processing process Although the case where the direction in which the scattered reflection is maximum is orthogonal to the moving direction, the illumination unit and the imaging unit are configured such that the extending direction of the line-shaped inspection light and the extending direction of the line-shaped imaging region are respectively moving directions. Since they are arranged so as to cross obliquely at the same angle, they are affected by scattered light regardless of whether the direction in which scattered reflection is maximum is parallel to the moving direction or orthogonal to the moving direction. Kukushi, to obtain a received light amount proportional to the specular reflectance of the test surface, it is possible to correctly detect the gloss of the test surfaces, clearly detect differences in gloss.

  Here, if the light projecting optical axis of the illuminating unit and the light receiving optical axis of the imaging unit are greatly tilted with respect to the normal direction of the inspection surface, irregular reflection will occur due to minute irregularities on the inspection surface, which is Since the component in which the amount of reflected light has changed is less likely to enter the imaging means, the influence of the pattern on the inspection surface is reduced, and the portion where the glossiness has changed on the inspection surface can be reliably detected. When the inspection object is wood, if the angle of the light projecting optical axis of the illuminating unit and the light receiving optical axis of the imaging unit with respect to the normal direction of the inspection surface is 70 degrees or more as a result of the experiment, the inspection surface It was found that the influence of the pattern can be reduced. In addition, when imaging a long inspection object with a property that tends to diffusely reflect in a specific direction, such as a plate material such as a flooring material or a metal plate with fine unevenness on the surface, using a line camera, By arranging the light projecting / receiving optical axis at an angle of 60 ° or more with respect to the moving direction, even if the moving direction of the object is perpendicular or parallel to the direction in which the scattering / reflection of the surface is maximum, the direction in which scattering / reflection is likely to occur It is possible to observe the gloss change on the surface of the object.

According to the first aspect of the present invention, the image correction unit corrects the deformation of the image based on the measurement result of the angle measurement unit, so that it is possible to easily measure the size and area of the portion where the glossiness has changed. . According to the first aspect of the present invention, a part having a surface property that is smoother than that of the peripheral part is obtained by obtaining a part having a luminance higher than the first threshold and a luminance change amount with the peripheral part being larger than the second threshold. Can be detected.

According to the invention of claim 2, a part having a rough surface property compared to the peripheral part is detected by obtaining a part having a luminance lower than the third threshold and a luminance change amount with the peripheral part being larger than the fourth threshold. be able to.

According to the invention of claim 3 , the image correction means corrects the deformation of the image based on the measurement result of the angle measurement means, so that the size and area of the part where the glossiness has changed can be easily measured. . Further, according to the invention of claim 3, by obtaining a part having a luminance lower than the third threshold and a luminance change amount with the peripheral part being larger than the fourth threshold, a part having a rough surface property compared to the peripheral part is obtained. Can be detected.

According to the invention of claim 4 , by using a light source in which the direction of the line light irradiated onto the inspection surface is one direction, the inspection light is prevented from being inserted into the concave portion of the inspection surface, and the influence of the scattered light is prevented. Further reduction can be achieved.

The object surface inspection apparatus of this embodiment is shown, (a) (b) is explanatory drawing explaining the detection principle same as the above. (A) (b) is explanatory drawing explaining the detection principle same as the above. It is explanatory drawing of the captured image by the imaging device same as the above. It is explanatory drawing explaining the detection method of the glossy change part by the same as the above. It is explanatory drawing explaining the detection method of the glossy change part by the same as the above.

  Hereinafter, an embodiment in which the technical idea of the present invention is applied to an object surface inspection apparatus for detecting a surface defect of a plate material such as a flooring material will be described with reference to FIGS. As shown in FIG. 2 (a), the flooring is manufactured by stacking the protruding plate 51 on the plywood 57 coated with an adhesive and then pressing the protruding plate 51 against the plywood 57 with a smooth pressure plate. As shown in FIG. 2 (b), at the place where the protruding plate 51 is broken (where the crack or crack is generated), the adhesive 54 is directly pressed against the pressure plate, so that a fine concavo-convex structure (recess 52) is formed on the surface. Compared with the projecting plate portion 55 having a convex portion 53), a smooth surface portion 56 having higher glossiness is formed. In the object surface inspection apparatus of the present embodiment, such a smooth surface portion 56 is replaced with a defective portion. In addition, a part having a rough surface property compared to the peripheral part is also detected as a defective part. Note that the inspection object is not limited to a plate material, and may be one that detects a scratch formed on the surface of a metal material, and as a defective part, compared to a part having a smooth surface property compared to the peripheral part and a peripheral part. Alternatively, only one of the parts having rough surface properties may be detected.

Imaging for imaging the illumination device 2 (illumination means), an image of the inspection surface 51 of the plate 50 for irradiating the line-like inspection light at the object body inspection apparatus plate sliced veneer is bonded to the surface 50 (test object) The apparatus 3 (imaging means) and the image processing apparatus 1 that detects a defect in the inspection surface 51 of the plate member 50 by analyzing an image captured by the imaging apparatus 3 are provided as main components.

Illumination device 2 includes a light source 2a having an elongated light emitting unit such as example if a straight tube fluorescent lamp, and a mask 2b which linear slits are formed, when a parallel beam of the transmitted linear mask 2b inspection The surface 51 is irradiated. The illuminating device 2 is disposed at a position where the inspection surface 51 is irradiated with line light from a direction obliquely intersecting the normal direction of the inspection surface 51. Further, since the illumination device 2 performs parallel light illumination in which the direction of the light beam applied to the inspection surface 51 is one direction, even if the inspection surface 51 has minute irregularities as shown in FIG. Can be prevented from entering the concave portion 52, and the light reflected by the parallel surface near the top of the convex portion 53 can be incident on the imaging device 3.

  The image pickup apparatus 3 is composed of a line camera in which light receiving elements such as a CCD (Charge Coupled Device) and a CMOS image pickup element are arranged in a line shape, and a plate material 50 to be inspected by a transfer device 4 such as a conveyor. By being transported at a constant speed in the transport direction L5 (moving direction), the inspection surface of the plate member 50 is scanned, and an image of the entire surface of the inspection surface 51 is acquired. An image picked up by the image pickup device 3 is stored in an image memory 11 of the image processing device 1 described later, and a defect detection process is performed by the inspection processing unit 10. As the light receiving element of the image pickup device 3, it is preferable to use an element that can obtain an output proportional to the logarithm of incident light energy. Specifically, a light receiving element such as a logarithmic conversion type CMOS image pickup element may be used. . By using such a light receiving element, it is possible to prevent the luminance value indicating the glossiness of the inspection surface 51 acquired by the imaging device 3 from being saturated even when the change in the glossiness on the inspection surface 51 is large. The dynamic range can be expanded.

  Here, the line-shaped visual field A irradiated with the inspection light and the illumination device 2 are connected, and a straight line (hereinafter, this straight line is referred to as a light projection optical axis) L2 and the inspection surface orthogonal to the direction in which the visual field A extends. The angle δ1 (incident angle) formed by the normal line L1 of 51 and the line-shaped visual field A observed by the imaging device 3 on the inspection surface and the imaging device 3, and a straight line orthogonal to the direction in which the visual field A extends. (Hereinafter, this straight line is referred to as the light receiving optical axis) and the angle δ2 (reflection angle) formed by the normal line L1 are both equal and δ1 = δ2 ≧ 70 degrees. That is, since the illumination device 2 and the imaging device 3 are arranged so that the incident angle δ1 and the reflection angle δ2 coincide with each other across the field of view A, the imaging device 3 includes the inspection surface 51 of the plate 50 that is an inspection object. The light component specularly reflected at is mainly incident.

  FIG. 2A is an enlarged cross-sectional view schematically showing an inspection surface 51 of a plate material 50 that is an inspection object, and has a fine concavo-convex structure on the surface like a metal plate or wood subjected to hairline processing. In the case of an inspection target having a large incident angle δ1, the light emitted from the illuminating device 2 is positive at a portion having a nearly horizontal surface near the top of the convex portion 53 constituting the concave and convex portions of the light emitted from the illumination device 2. Only the reflected component is incident in the direction of the imaging device 3. The specularly reflected light component does not depend on the color of the inspection surface 51 and has a characteristic that the wavelength distribution of the light source light remains as it is, so that the light projection optical axis of the illumination device 2 and the normal line of the inspection surface 51 are used. By setting the angle δ1 and the angle δ2 formed between the light receiving optical axis of the imaging device 3 and the normal line of the inspection surface 51 as described above, the gloss of the inspection surface 51 is not affected by the color of the inspection surface 51. Only the difference in (glossiness), that is, the difference in regular reflectance can be imaged. Here, the above-mentioned angles δ1, δ2 may be set to appropriate values according to the surface roughness of the inspection object. For example, when inspecting a plate material having a surface roughness of about 10 to 20 μm used as a flooring material. The angles δ1 and δ2 are preferably 70 degrees or more.

Here, when there is a groove-like microstructure extending in a certain direction on the surface of the object to be inspected, such as a metal plate or wood whose surface has been subjected to fine processing such as hairline processing, the groove-like microstructure is When observed from a direction perpendicular to the surface, the inspection surface has a reflection characteristic close to that of the irregular reflection surface (rough surface), and when observed from the same direction as the groove-like microstructure, the inspection surface is close to the regular reflection surface (smooth surface). It will have reflection characteristics. For example, when detecting a difference in glossiness on the inspection surface in order to detect a smoother or rougher surface than the peripheral portion, the light projecting optical axis of the illumination device 2 and the light receiving optical axis of the imaging device 3 are detected. Is preferably arranged in a direction in which the inspection surface can be seen close to the irregular reflection surface. When the direction in which the scattered reflection is maximum coincides with the transport direction, the light projecting optical axis of the illumination device 2 and the light reception of the imaging device 3 It is desirable to arrange the illumination device 2 and the imaging device 3 so that the optical axis matches the transport direction. However, in the industrial field, for example, there are many cases where the conveyance direction is limited, for example, the inspection object is a roll product, and the inspection object can be conveyed only in the direction along the groove-like microstructure formed on the surface. There can be. That is, depending on the inspection object, the conveyance direction may be perpendicular to the groove-like microstructure, or the conveyance direction may be parallel to the groove-like microstructure. same angle .theta.1, are arranged so as to intersect obliquely at θ2 with respect to better direction, each conveying direction L5 of extension of the direction and linear imaging area extension of the inspection light (field a). Therefore, even when the groove-like fine structure of the inspection surface is orthogonal to the conveyance direction or parallel to the conveyance direction, the inspection surface 51 of the inspection object can be observed from the direction in which the inspection object can be seen close to the irregular reflection surface. The difference in glossiness can be clearly detected on the inspection surface 51. Here, when the inspection object is a plate 50 such as a flooring, the angles θ1 and θ2 formed by the light projecting optical axis of the illuminating device 2 and the light receiving optical axis of the imaging device 3 with the transport direction are 60 degrees or more and It is preferable to set the angle to less than 90 degrees. However, the inspection visual field width is a value obtained by dividing the width dimension of the plate material 50, which is an inspection object, by the cosine of the angle θ2 formed between the light receiving optical axis and the conveyance direction (inspection visual field width = inspection visual field width ÷ cos θ2). Since the visual field width becomes extremely large as it approaches 90 degrees, the angles θ1 and θ2 may be set as large as possible within a range in which the optical system can be practically configured.

  Further, when the extending direction L4 of the line-shaped imaging region (field of view A) obliquely intersects with the conveyance direction L5 at an angle θ2, the image of the plate member 50 acquired by the imaging device 3 is as shown in FIG. Therefore, in the process in which the imaging device 3 transfers the image data to the image memory 11, the image distortion is reduced by shifting the address of the image data in accordance with the image distortion. It is preferable to obtain the same image as the state in which the extending direction of the visual field A is orthogonal to the conveyance direction L5, and it is possible to easily measure the size and area of the portion of the inspection target where the glossiness has changed. Although the image pickup device 3 corrects image distortion in the process of transferring the image data to the image memory 11, the image data picked up by the image pickup device 3 is stored in the image memory 11 as it is, and the inspection processing unit 10 side In this case, a process for correcting image distortion may be performed. That is, an angle measurement unit 13 that measures an angle θ2 that the extending direction of the line-shaped imaging region makes with the conveyance direction L5 is provided in the image processing apparatus 1, and the inspection processing unit 10 reads out image data from the image memory 11 and outputs an image. In the course of processing, the image correction function unit 14 reads out the image data from the image memory 11, fetches the measurement result of the angle θ 2 from the angle measurement unit 13, and shifts the address of the image data based on the measurement result of the angle θ 2. Thus, after correcting the distortion of the image, by performing image processing using the corrected image data, it is possible to easily measure the size and area of the portion of the inspection object whose glossiness has changed.

  Next, the inspection processing unit 10 detects, from the image data stored in the image memory 11, a smooth surface portion having a higher glossiness than the peripheral portion on the inspection surface and a rough surface portion having a lower glossiness than the peripheral portion. The processing to be performed will be described below. Here, in the image captured by the imaging device 3, the luminance tends to be low if the surface is close to the irregular reflection surface (rough surface), and the luminance is high if the surface is close to the regular reflection surface (smooth surface). . Accordingly, the first threshold value Th1 used for detecting a portion (bright portion) having a relatively high gloss level on the inspection surface and a portion (dark portion) having a relatively low gloss level are used. The third threshold value Th3 of luminance is stored in the storage unit 12 in advance, and the bright portion extraction function unit 15 of the inspection processing unit 10 collects a collection of pixels whose luminance is brighter than the first threshold value Th1 in the image of the inspection object. While extracting as a smooth surface part (bright part), the dark part extraction function part 16 of the test | inspection process part 10 extracts the collection of the pixels whose brightness | luminance is darker than 3rd threshold value Th3 as a rough surface part (dark part) in the image of a test object. For example, if the area of the extracted bright part or dark part is equal to or greater than a predetermined reference value, it is determined that there is a defect. In this way, the process of extracting the bright part and the dark part by comparing the brightness of each pixel with the threshold value and extracting the bright part and the dark part from the object having a constant glossiness over the entire inspection surface has a specified glossiness. This method is suitable for detecting a portion that exceeds the range (that is, a portion whose glossiness is lower than a specified value or a portion that is higher than a specified value).

  On the other hand, when detecting scratches or damages on the surface of the inspection object, it is necessary to detect only the part where the glossiness of the inspection surface changes suddenly from the image captured by the imaging device 3. If only the simple threshold determination described above is performed, there is a possibility that a portion where the glossiness of the inspection surface is partially uneven may be erroneously detected. It is also preferable to evaluate the difference.

  Therefore, the second threshold Th2 of the luminance change amount is stored in the storage unit 12 in order to detect a glossy change portion that suddenly changes in the direction in which the glossiness increases on the inspection surface, and suddenly changes in a direction in which the glossiness decreases on the inspection surface. In order to detect the gloss change part to be detected, a fourth threshold Th4 of the luminance change amount (may be the same value as the second threshold Th2) is stored in the storage unit 12, for example, a part that changes suddenly in a direction in which the glossiness increases. In the case of detection, when the gloss changing unit 61, which is a collection of pixels having a luminance greater than the first threshold Th1, is extracted by the bright portion extraction function unit 15 as shown in FIG. The unit 17 obtains a circumscribed rectangular region 62 of the gloss changing unit 61 and sets an inspection region 63 obtained by extending the circumscribed rectangular region 62 vertically and horizontally by a predetermined expansion width m. When the average luminance D1 of the pixels in the changing portion 61 and the average luminance D2 of the region obtained by removing the gloss changing portion 61 from the inspection region 63 are obtained, and the luminance difference | D1-D2 | of both exceeds the above-described second threshold Th2. It is detected as a sudden change in glossiness in the bright direction.

  Similarly, when detecting a region that changes suddenly in the direction in which the glossiness decreases, when the darkness extraction function unit 16 extracts the gloss change unit 61 that is a collection of pixels having lower luminance than the third threshold Th3, the inspection is performed. The gloss change determination function unit 17 of the processing unit 10 obtains a circumscribed rectangular area 62 of the gloss changing section 61 and sets an inspection area 63 in which the circumscribed rectangular area 62 is expanded vertically and horizontally by a predetermined expansion width m. The average luminance D1 of the pixels in the gloss changing portion 61 and the average luminance D2 of the region excluding the gloss changing portion 61 from the inspection region 63 are obtained, and the luminance difference | D1-D2 | If it exceeds, it is detected as a sudden change in glossiness in the dark direction.

  As described above, the inspection processing unit 10 extracts a bright part, which is a group of pixels whose luminance is brighter than the first threshold, or a dark part, which is a group of pixels whose luminance is darker than the third threshold, in the image. Since only the portion where the difference in average luminance between the dark portion and its peripheral portion is larger than the second threshold Th2 and the fourth threshold Th4 is detected as the sudden change portion of the glossiness, the possibility of erroneously detecting uneven glossiness is reduced. can do.

  Note that the gloss change determination function unit 17 of the inspection processing unit 10 detects a sudden change site in glossiness by comparing the difference in average luminance between a bright part or dark part and its peripheral part with a predetermined threshold value. Instead of this, an abrupt change in glossiness may be detected by the detection method 2 described below. For example, when detecting a part that changes suddenly in the direction in which the glossiness increases, the bright portion extraction function unit 15 extracts the gloss changing unit 61 that is a collection of pixels having a luminance higher than the first threshold Th1, as shown in FIG. Then, the gloss change determination function unit 17 of the inspection processing unit 10 obtains the circumscribed rectangular region 62 of the gloss changing unit 61, and also inspects the circumscribed rectangular region 62 vertically and horizontally by a predetermined expansion width m. 63 is set, and a histogram of the luminance distribution of each pixel in the inspection area 63 is obtained. FIG. 5 is an example of the histogram obtained in this way. The peak 71 indicating the luminance distribution of the gloss changing portion 61 and the peripheral portion of the gloss changing portion 61 (the region obtained by removing the gloss changing portion 61 from the inspection region 63). The average luminance e1 and e2 and the standard luminance deviations d1 and d2 are obtained for the peak 72 indicating the luminance distribution of), and the clarity α defined by the following equation (1) is obtained.

  Here, the greater the separation between the luminance distribution 71 of the gloss changing unit 61 detected by the histogram shown in FIG. 5 and the luminance distribution 72 of the peripheral portion thereof, the higher the clarity α obtained by Equation (1). The value of the clarity α represents a relative distribution difference between the gloss changing portion 61 and its peripheral portion. Accordingly, the gloss change determination function unit 17 of the inspection processing unit 10 compares the clarity α obtained by the above-described processing with a predetermined threshold value stored in advance in the storage unit 12, and when the clarity exceeds the threshold value. The gloss changing portion 61 is detected as a sudden change portion of the glossiness.

  Further, when detecting a region that changes suddenly in the direction in which the glossiness decreases, the dark portion extraction function unit 16 extracts the gloss changing unit 61 that is a collection of pixels having a luminance lower than the second threshold Th1, as described above. Then, the gloss change determination function unit 17 of the inspection processing unit 10 obtains a circumscribed rectangular region 62 of the gloss changing unit 61, and an inspection region 63 in which the circumscribed rectangular region 62 is expanded vertically and horizontally by a predetermined expansion width m. And a histogram of the luminance distribution of each pixel in the inspection area 63 is obtained. Thereafter, the gloss change determination function unit 17 of the inspection processing unit 10 obtains the peak 71 indicating the luminance distribution of the gloss change unit 61 and the luminance distribution around the gloss change unit 61 from the luminance distribution histogram in the inspection region 63. For the peak 72 shown, average luminances e1 and e2 and luminance standard deviations d1 and d2 are obtained, respectively, and after obtaining the intelligibility α defined by the above formula (1), the intelligibility α is compared with a predetermined threshold value. When the articulation level exceeds the threshold value, the gloss changing unit 61 is detected as a sudden change unit of gloss level.

  As described above, the inspection processing unit 10 extracts a bright part, which is a collection of pixels whose luminance is brighter than the first threshold, or a dark part, which is a collection of pixels whose luminance is darker than the third threshold, in the image. After calculating the average brightness and the brightness standard deviation in the dark area and its surrounding area, the clarity shown in Equation (1) is found, and the part where this clarity exceeds a predetermined threshold is detected as a sudden change in gloss. doing. Therefore, since the unevenness of the glossiness on the inspection surface is large, even if the unevenness of the glossiness is erroneously detected even if the above-described detection method 1 is used, the clarity obtained from the average brightness and the brightness standard deviation is used. Further, by obtaining the sudden change portion of the glossiness, the sudden change portion of the glossiness can be obtained without erroneously detecting uneven glossiness.

  In the present embodiment, the case where the plate material 50 that is the inspection object is transported by the transport device 4 has been described as an example. However, the illumination device 2 and the imaging device 3 are moved by a transport device (not shown), thereby the illumination device. 2 and the imaging device 3 may move relative to the inspection object to scan the inspection object.

DESCRIPTION OF SYMBOLS 1 Image processing apparatus 2 Illumination apparatus 2a Light source 2b Mask 3 Imaging apparatus 4 Conveyance apparatus 10 Inspection processing part 11 Image memory 12 Storage part 13 Angle measurement part 14 Image correction function part 15 Bright part extraction function part 16 Dark part extraction function part 17 Gloss change Judgment function unit 50 Plate material 50 Inspection object 51 Inspection surface

Claims (4)

Illuminating means a linear inspection light from a direction that intersects the normal direction and the oblique inspection surface of the inspection object is irradiated on the inspection surface, the received light of the light receiving element comprises a light receiving element arranged in a line Imaging for imaging the inspection surface arranged so that an angle formed between the axis and the normal direction of the inspection surface is the same as an angle formed by the projection optical axis of the illumination unit and the normal direction of the inspection surface means and said a test processing means for performing an inspection of the inspection surface by the imaging means to analyze a captured image and the illumination means and the imaging means, extension of linear inspection light direction and linear The extending direction of the imaging region is arranged so as to cross obliquely at the same angle with respect to the moving direction in which the inspection object moves relative to the illumination unit and the imaging unit ,
An angle measuring unit that measures an angle between the extending direction of the line-shaped inspection light and the extending direction of the line-shaped imaging region and the moving direction, and the imaging unit picks up an image based on a measurement result of the angle measuring unit. An image correction unit that corrects image deformation, and a first threshold value of luminance and a second threshold value of the amount of change in luminance that are used to detect a glossy change portion that suddenly changes in the direction in which the glossiness increases on the inspection surface are stored. A storage unit
The inspection processing means inspects the inspection surface by analyzing the image corrected by the image correction means,
The inspection processing means extracts a bright portion extraction function as a bright portion from the captured image of the inspection surface as a bright portion, and the brightness portion and the peripheral portion of the bright portion respectively. A gloss change determining function that obtains an average value and determines a gloss change portion when the brightness difference between the brightness average value in the bright portion and the brightness average value in the peripheral portion is greater than the second threshold value. Characteristic object surface inspection device. The storage unit stores a third threshold value of luminance and a fourth threshold value of the luminance change amount used to detect a glossy change portion that suddenly changes in a direction in which the glossiness decreases on the inspection surface,
The inspection processing unit obtains an average value of luminance for each of a dark portion extraction function for extracting a region having a luminance lower than the third threshold value as a dark portion from a captured image of the inspection surface, and a dark portion and a peripheral portion of the dark portion. And a gloss change determining function for determining that the difference in brightness between the average value of brightness in the dark part and the average value of brightness in the peripheral part is greater than the fourth threshold value as a gloss change part. The object surface inspection apparatus according to 1. Illuminating means for irradiating the inspection surface with a line-shaped inspection light from a direction obliquely intersecting with the normal direction of the inspection surface of the inspection object, and a light receiving element arranged in a line, and receiving light of the light receiving element Imaging for imaging the inspection surface arranged so that an angle formed between the axis and the normal direction of the inspection surface is the same as an angle formed by the projection optical axis of the illumination unit and the normal direction of the inspection surface And an inspection processing means for inspecting the inspection surface by analyzing an image captured by the imaging means, wherein the illumination means and the imaging means are arranged in the direction in which the line-shaped inspection light extends and the line-shaped inspection light. The extending direction of the imaging region is arranged so as to cross obliquely at the same angle with respect to the moving direction in which the inspection object moves relative to the illumination unit and the imaging unit,
An angle measuring unit that measures an angle between the extending direction of the line-shaped inspection light and the extending direction of the line-shaped imaging region and the moving direction, and the imaging unit picks up an image based on a measurement result of the angle measuring unit. Image correction means for correcting the deformation of the image, and a third threshold value of luminance and a fourth threshold value of the luminance change amount used to detect a glossy change portion that suddenly changes in the direction of decreasing glossiness on the inspection surface are stored. a storage unit that,
The inspection processing means inspects the inspection surface by analyzing the image corrected by the image correction means,
The inspection processing unit determines and dark extracting function of extracting a region lower luminance than the third threshold value from the captured image of the inspection surface as dark portions, each average value of the brightness between the dark portion and the dark portion of the peripheral portion , those you anda gloss change determination function luminance difference between the average value of the brightness in the average value and the peripheral portion of the brightness in the dark portion is determined to change in gloss portion is larger than the fourth threshold value Body surface inspection device. 4. The object surface inspection apparatus according to claim 1 , wherein the illumination unit includes a light source that irradiates the inspection surface with a line-shaped parallel light . 5.

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