WO2016121878A1 - Optical appearance inspection device and optical appearance inspection system using same - Google Patents

Abstract

Provided are an optical appearance inspection device capable of achieving a reduction in the number of cameras to be used, downsizing of the device itself, and performing various kinds of inspections in a short time without requiring operating time, for example, for moving the cameras, and an optical appearance inspection system using the same. The optical appearance inspection device comprises an image capturing means for capturing an image of an object to be inspected, and a processing means for analyzing/determining the presence or absence of a defect in the appearance of the object to be inspected, using the captured image captured by the image capturing means. The processing means acquires the captured image from the image capturing means, and analyzes changes in color and/or brightness between respective pieces of image data relating to a plurality of lines respectively selected from regions in which mutually different intensities of light are applied to the object to be inspected, to thereby determine the presence or absence of defects in the appearance of the object to be inspected.

Description

Optical appearance inspection apparatus and optical appearance inspection system using the same

The present invention relates to an optical appearance inspection apparatus for inspecting the appearance of various articles such as food and industrial products, and an imaging means which can be suitably used for the optical appearance inspection apparatus. In particular, it is suitable for an optical appearance inspection apparatus for analyzing the image data obtained by photographing an article and checking the presence or absence of an uneven defect such as flaws and burrs or distortion on the article surface or the presence of foreign matter visible through the surface; Imaging means that can be used for

In order to inspect defects on the surface of various articles (hereinafter, also referred to as “objects to be inspected”) such as food products such as agricultural products and processed foods, or industrial products such as resin molded products and metal products, It is practiced to photograph an article to be conveyed and analyze the photographed image data.

The applicant of the present invention also proposes an apparatus for inspecting foreign matter and the like using such image data in Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-8339). In this document, in order to inspect foreign matter in the powder filled in the transparent container easily and reliably, the transparent container is imparted with a vibration combining the reciprocating vibration in the longitudinal direction and the reciprocating vibration in the horizontal direction, thereby the transparent container While circulating the powder inside the powder, the powder that circulates and flows is imaged, and the foreign substance inspection method in the powder in the transparent container is proposed to inspect the presence or absence of foreign substances using the obtained image.

In addition, in order to inspect defects in the appearance of the article in the past, inspection content (ie whether to inspect the adhesion of dust, whether to inspect the presence or absence of scratches and burrs on the surface, or the presence or absence of distortion on the surface Depending on the difference, etc.), it was necessary to change the shooting direction or the way of lighting. For example, in the inspection of dust and the like attached to the inspection object, the inspection (photographing) must be performed from directly above, and in the inspection of irregularities such as scratches, the inspection object is inspected from an oblique direction by changing the angle of the camera or the camera I had to shoot. Therefore, in the case of performing various surface inspections on the inspection object, it is necessary to reciprocate the inspection object a plurality of times or to provide a plurality of inspection stations for inspection.

Therefore, in order to shorten the inspection time, Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-333449) proposes an inspection apparatus of a back light panel which can perform performance inspection only by one reciprocation. That is, in this document, an inspection mechanism disposed in an inspection area for inspecting a plate-like object to be inspected, a mounting table on which the object to be inspected is detachably mounted, and the mounting table horizontally. Mounting table moving means for moving in the direction, an operation unit for operating the moving means, a camera for capturing an image from the top surface of the table, and two cameras for capturing the table from the left and right of the upper surface And a detection unit that detects defects based on an image from the camera, and a display unit that displays the detection result of the detection unit, and the test object is moved by only one reciprocation of the test object by the camera. The examination is to be finished.

Also, in the past, there has been proposed a technology for automating changing the angle to be inspected (photographed) according to the type of defect to be inspected. For example, in Patent Document 3 (Japanese Patent Application Laid-Open No. 2006-300913), the imaging angle of the camera in the forward pass and return pass is automatically moved, and the angle of the positional relationship between the camera and the work is changed. Technologies have been proposed. That is, this document proposes a light guide plate inspection apparatus having a rotary actuator and a brake that holds a plurality of line sensor cameras for light guide plate inspection from above the light guide plate loading stage and changes the imaging angle of the camera together with its structure. ing.

Furthermore, in the past, there has been proposed an imaging apparatus provided with a line sensor camera devised so as to be able to clearly image an imaging object having surface irregularities. For example, in Patent Document 4 (Japanese Patent Laid-Open No. 2011-223233), an objective lens and a plurality of line scan sensors disposed within the imaging depth of the objective lens and including a plurality of imaging elements are arranged in series in the scanning direction. An imaging unit; a plurality of sets of the line scan sensors are line sensor cameras arranged so that their imaging positions are different from each other; and imaging results of the plurality of sets of the line scan sensors are the imaging element unit The in-focus image extracting means for extracting an in-focus image from among the plurality of unit-captured images read out in order in the above, and the in-focus imaging for combining the extracted in-focus image to generate an in-focus image There has been proposed an imaging device provided with an image generation unit.

JP, 2010-8339, A JP 2007-333449 A Unexamined-Japanese-Patent No. 2006-300913 JP, 2011-223233, A

As described above, when inspecting a defect appearing on the surface of an article (object to be inspected), it is inspected whether dust or the like has adhered to the surface or unevenness such as flaws, burrs or distortion of the surface Depending on whether or not to inspect, it was necessary to change the direction in which the object to be inspected is photographed or the way of applying light. For example, when the inspection target is a light guide plate and the appearance inspection in the manufacturing process is to be automated, the transmitted illumination is used to inspect the presence or absence of carbonized foreign matter in the resin which is the manufacturing raw material and discolored defects such as undissolved. In order to inspect gentle uneven defects caused by melting temperature and injection pressure at the time of resin molding, scattering illumination must be irradiated and photographed, and molding In order to inspect a steep uneven defect such as a flaw or burr due to a mold or a take-out machine to be used for, it was necessary to shoot by irradiating low angle illumination. Therefore, it has been necessary to prepare illumination conditions in accordance with the features of the defect to be inspected and cameras for imaging under the respective illumination conditions.

Therefore, in order to solve this problem, conventionally, a plurality of cameras may be installed as disclosed in Patent Document 1 or the direction of the camera may be automatically corrected as disclosed in Patent Document 2. It has been proposed.

However, when using a plurality of cameras, not only the number of cameras installed naturally increases the cost, but also the installation space for the cameras must be secured, so the inspection apparatus itself is There was a problem that it enlarged. Also, in the case of automatically correcting the direction of the camera, an operation time for moving the camera to a predetermined position is required, and it is considered that the inspection time increases.

Therefore, the present invention provides an optical appearance inspection apparatus in which the size of the apparatus itself is reduced by reducing the number of cameras used and the number of cameras installed, and an optical appearance inspection system using the same. Optical type that can perform various types of inspections in a short time without requiring operation time such as moving the camera while reducing the number of cameras used as the first problem. A second object is to provide an appearance inspection apparatus and an optical appearance inspection system using the same.

Further, the inspection object is conveyed by a conveying means such as a belt conveyor, but the size, height or thickness of the inspection object is various. That is, the object to be inspected may also be a three-dimensional article such as a box-like or tubular-like one having a height at one time, or a plate-like or sheet-like article having a low height at one time. Therefore, in order to photograph an article having different height, thickness, etc. at an accurate angle, it is necessary to adjust the installation position and angle of the camera or the installation position and angle of the inspection object at each inspection. It was time and effort.

Therefore, the present invention does not require changing the height or angle of the camera, the illumination, or the inspection object even when inspecting the inspection object having different sizes, heights, or thicknesses. A third object is to provide an optical appearance inspection apparatus capable of inspecting the appearance of an inspection object and an optical appearance inspection system using the same.

Furthermore, in the prior art, the presence or absence of carbonized foreign matter in resin which is a raw material for production, discolored defects such as undissolved, melting temperature at the time of resin molding, gentle uneven defects caused by injection pressure, molds used for molding When inspecting a defect that appears in the appearance of the object to be inspected, such as a sharp uneven defect such as a flaw or burr caused by the take-out machine, by using a photographed image, an image to be inspected must be photographed for each defect. I had to.

Therefore, according to the present invention, an optical appearance inspection apparatus capable of inspecting various kinds of defects appearing in the appearance of the inspection object as described above by one photographing, and an optical using the same It is a fourth object to provide a visual inspection system.

Moreover, when performing surface inspection based on a captured image, it is possible that the transmission position and reflection position of the irradiated light will be fluctuate | varied by the thickness and height position of test object changing. Therefore, it is desirable to eliminate such fluctuation, and it is also desirable to acquire "changes in the irradiated light" caused by surface defects as data without leakage.

In this respect, Patent Document 4 discloses that the entire surface of an imaging object having irregularities on the surface is clearly imaged by extracting and combining imaging data in focus. However, the invention according to this document has an object of clearly imaging an imaging object having surface irregularities, and a plurality of sets of line scan sensors are arranged so that their imaging positions are different from each other. It is done. Therefore, with this technology, although it is possible to acquire a photographed image of an optimum focal distance, it is not possible to acquire a photographed image for surface inspection that involves the positional relationship with the light source. Further, the technology of this patent document 4 is described in the claim 4 that "each of the line scan sensors is composed of a plurality of sensor arrays read out by TDI method", and the sensor array has 256 lines. In view of the generality, in this technology, the height resolution is limited by the tilt angles and the number of lines of the plurality of imaging elements, and it is considered that the degree of freedom in following the unevenness in practical use is low.

Therefore, in the present invention, the surface inspection of the object to be inspected can be carried out at high speed and / or high accuracy by using a photographing means designed to secure a wide field of view and acquire an optimum image for surface inspection. The fifth object of the present invention is to provide an optical appearance inspection apparatus which can be used and an optical appearance inspection system using the same.

In order to solve at least one of the above problems, according to the present invention, the image data in a plurality of lines selected from inside and outside of the area illuminated by the illumination means is analyzed and judged line by line. The present invention provides an optical appearance inspection apparatus adapted to inspect various defects appearing in the appearance, and an optical appearance inspection system using a defect.

That is, the optical appearance inspection system according to the present invention analyzes and determines the presence or absence of the appearance defect in the inspection object using the photographing means for photographing the inspection object and the photographed image photographed by the photographing means. Processing means for obtaining a photographed image from the photographing means, and processing the color and / or the image data of the plurality of lines respectively selected from the regions different in the intensity of the light irradiated to the inspection object The change in brightness is analyzed to determine the presence or absence of each appearance defect in the inspection object.

«About the shooting means»
In the above-described optical appearance inspection apparatus of the present invention, the photographing means is for photographing the inspection object to obtain a photographed image, and is configured with various imaging elements. In particular, it is desirable that the photographing means be capable of acquiring the photographed image data as electronic data. This is to smoothly perform the image analysis process in the processing means. The imaging device may be a CMOS image sensor or a CCD image sensor. In particular, it is desirable that a camera capable of photographing every arbitrary line like the CMOS image sensor camera. Such a camera capable of capturing an image for each arbitrary line can be configured to include a photodiode row in which a plurality of photodiodes are arranged in a row, and by providing a plurality of photodiode rows, the processing means can obtain The image data in can be acquired. On the other hand, if it is a camera such as a CCD image sensor that acquires a planar photographed image, images are extracted in multiple lines from a planar photographed image obtained by photographing an inspection object, and image data to be analyzed is acquired. You can do it.

In particular, it is desirable to use, as the photographing means, a camera provided with a planar imaging element in which a plurality of photodiodes are arranged in the vertical and horizontal directions and capable of extracting an arbitrary plurality of lines in the imaging field of view. Similar to the case of using a plurality of imaging means and illumination means by passing through the imaging region without stopping the inspection object by imaging with an arbitrarily selected line even though it is a planar imaging element It is because the image of can be obtained. Also, like a camera using an image sensor for capturing a planar image, processing for extracting necessary lines (areas) after acquiring a planar captured image is unnecessary, and processing speed can be increased. It is That is, by using the photographing means using the CMOS image sensor, the inspection process can be simplified, the amount of data can be reduced, and the inspection time can be shortened.

Even if the transmitting position and the reflecting position of the irradiated light are changed due to the difference or change of the material of the object to be inspected, or the change of the thickness or the height position of the object to be inspected, It is desirable to configure it so that it can be acquired. For this purpose, for example, an object to be inspected is photographed in an area having a certain width in the scanning direction, and an area where the change in color and / or brightness is optimum is extracted and combined from the photographed image, and this is subjected to surface inspection It is also desirable to use image data for

That is, the imaging unit has an imaging unit for imaging a plurality of lines arranged in parallel to the scanning direction of the inspection object and an orientation orthogonal to the scanning direction for each of the plurality of lines imaged by the imaging unit (that is, imaging After comparing the color and / or brightness for each area in the longitudinal direction of the selected line, the area of a specific line is extracted based on this comparison, and this is combined to combine image data of one or more lines. It can be composed of an image processing unit to be combined.

In the optical appearance inspection apparatus using the imaging unit, the imaging unit is parallel to the scanning direction of the inspection object in each of a plurality of lines respectively selected from regions with different intensities of light irradiated to the inspection object. An optical appearance inspection apparatus using a plurality of image data of one line or a plurality of lines respectively synthesized by the image processing unit as image data of a plurality of lines which are photographed by a plurality of lines arranged in a row and analyzed by the processing means Can. In the optical appearance inspection apparatus configured in this manner, image data used for surface inspection (that is, image data acquired from respective regions having different intensities of irradiated light) are arranged in the scanning direction of the inspection object Since the color and / or brightness of a specific area in a plurality of lines are compared, and one or more lines of image data combined and extracted and combined with an area image optimum for each surface inspection are used, The surface inspection can be performed reliably and accurately. In addition, when the shooting area of the inspection object to be photographed at one time is a plurality of lines aligned in the scanning direction of the inspection object, an area unit of the plurality of lines aligned in the scanning direction of the inspection object The inspection object can be transported at the same time, and the inspection speed can also be improved.

«About processing means»
<About the configuration of processing means>
The processing means acquires a photographed image photographed by the photographing means, and changes in color and / or brightness of image data in a plurality of lines respectively selected from regions having different intensities of light irradiated to the inspection object. It is an apparatus which analyzes and determines the presence or absence of each appearance defect in a test subject. The image data analyzed by the processing means may be an image obtained by processing the photographed image, as well as directly using the photographed image by the photographing means. That is, this processing means acquires a photographed image from the photographing means, and uses the acquired photographed image as image data to be analyzed, or performs color processing on image data generated by performing image processing on the acquired photographed image. The change in brightness may be analyzed to inspect the appearance defect in the inspection object. Therefore, this processing means is accompanied by a CPU (Central Processing Unit), a memory, etc. for performing image processing as necessary, in order to perform numerical calculation, information processing, device control, etc. necessary for the analysis and judgment. Configured The image processing on the photographed image includes extraction processing of an arbitrary area from the photographed image, coupling processing of the photographed image, and correction processing such as lightness, saturation, and contrast.

The processing means analyzes image data of a plurality of lines. The image data of the plurality of lines is, as described above, image data of a plurality of lines acquired by photographing with a camera using an image sensor capable of photographing in an arbitrary plurality of lines like a CMOS image sensor Like the image sensor, image data of a plurality of lines acquired by extracting and extracting from a planar image captured by a camera using an image sensor for acquiring a planar image may be used. In particular, when the processing means acquires an image photographed in a planar shape, the extraction processing from the planar image can be executed by the processing means.

<About the image data of the line acquired by the processing means>
The image data of a plurality of lines analyzed by the processing means is image data of a plurality of lines respectively selected from regions having different intensities of light irradiated to the inspection object. The “light irradiated to the inspection object” is light reflected by the inspection object or light transmitted through the inspection object, and the image data of the plurality of lines is the reflected light or the transmitted light. Are selected from different regions. The intensity of the “light irradiated to the object to be inspected” can also be measured by light directed to the object to be inspected (light to be irradiated to the object to be inspected), which is the luminance on the light irradiation side of the object to be inspected Can be specified by measuring the brightness of the reflected light or transmitted light of the test object of a single color.

The light irradiated to the inspection object may be natural light as well as light irradiated by the illumination unit provided with the light source. Even if it is natural light, if the irradiation direction to the inspection object is specified, it is considered that the kind of appearance defect appearing in the image is different depending on which position the line-like image data is acquired. is there. However, it is desirable that the optical appearance inspection apparatus according to the present invention further include illumination means for irradiating the inspection object with light in order to keep the irradiation conditions such as the light irradiation position and the luminance constant. At that time, it is desirable that the image data of the plurality of lines analyzed by the processing means be respectively selected from regions having different intensities of light emitted by the illumination means.

The illumination means can use various illuminations to illuminate the inspection object. The light emitted by the illumination means may be visible light or invisible light such as infrared light, ultraviolet light, and X-rays. In particular, in the case of illumination means for emitting visible light, in addition to white light, light having a peak in a specific wavelength range such as blue, green, red, yellow, etc. may be emitted. Therefore, the photographing means is not necessarily limited to one for photographing light in the visible light region, but includes one capable of photographing light in the invisible light region. Further, in consideration of analyzing the image data of a plurality of lines, it is preferable that the illumination means be line illumination for irradiating light in a long range. When line illumination is used as the illumination means, it is preferable that the extension direction of the illumination and the extension directions of the image data of the plurality of lines used for the analysis be provided parallel to each other. It is preferable that the two extending directions be orthogonal to the scanning direction of the inspection object.

Further, the light to be photographed by the photographing means may be light (transmitted light) obtained by transmitting the irradiated light through the inspection object or light (reflected light) reflected by the inspection object. Therefore, the inspection object to which light is irradiated may be transparent or opaque, and may be a partially transparent or partially opaque article. When photographing an inspection object, generally, when the inspection object is transparent, it is desirable to photograph transmitted light of light irradiated to the inspection object to inspect a defect in appearance. However, in the case where the transparent inspection object causes reflected light, the reflected light can be photographed to inspect an appearance defect. On the other hand, when the inspection object is opaque, the appearance defect is inspected only by photographing the reflected light of the light irradiated to the inspection object.

As described above, when the optical appearance inspection apparatus according to the present invention includes the illumination unit, the image data of a plurality of lines analyzed by the processing unit is an area where the intensity of light emitted by the illumination unit differs. It is desirable to be selected from That is, at least the light intensity is selected from the respective regions of different light intensity, such as within the region where the illumination means is emitting light and outside the region where the illumination means is emitting light. Is desirable. This is because the types of defects that can be observed (or easily observed) differ depending on whether the illumination means is inside or outside the area where the light is illuminated. Therefore, by acquiring image data for analysis from areas inside and outside the area irradiated by the illumination means, it is possible to acquire image data that can be easily observed according to various types of defects. .

Further, “image data in a plurality of lines” analyzed by the processing means includes the area within the area irradiated with light by the irradiation means, the area outside the area irradiated with light by the irradiation means, and the boundary area of both. It is desirable to select from any two or more areas among three places.

That is, the optical appearance inspection apparatus according to the present invention further includes illumination means for irradiating the inspection object with light, and the image data in plural lines analyzed by the processing means is irradiated with light by the illumination means. At least at least a non-irradiated area in the vicinity of the contour area and not irradiated with light by the illumination means. It is desirable to be configured to be selected in any two or more regions. It is particularly desirable that the image data of the plurality of lines be selected from each of the irradiation center area, the outline area, and the non-irradiation area.

As described above, by setting the area for acquiring image data to be analyzed as the irradiation center area, the outline area, and the non-irradiation area, the image data of the analysis target is acquired in relation to the irradiation area of the illumination means. The area can be identified. Therefore, if the irradiation area in the illumination means can be specified, the position of the image data of the line to be analyzed by the processing means can be specified. The specification of the irradiation area in the illumination means can be measured or set every inspection object, but in the case of inspecting a plurality of inspection objects having the same shape and size, the irradiation area in the illumination means first After that, by using the image data of a predetermined position (line), the appearance inspection of a plurality of inspection objects can be continuously performed. Therefore, in this case, first of all, in the object to be actually inspected, it is confirmed on which line it is preferable to acquire the image data to be analyzed, and then the acquisition position of the image data to be analyzed (line It is desirable to identify). In particular, when setting which line of image data is to be analyzed in the contour area and the non-irradiated area, defects (concave defects such as scratches, burrs or distortion, adhesion of foreign matter, and foreign matter on the inspection object to be actually inspected) It is desirable to actually measure and specify a position where a defect such as a color non-uniformity or the like is likely to appear. When the photographing means is a camera using an image sensor capable of photographing in any plural lines like a CMOS image sensor, it is desirable to acquire image data in the set plural lines.

The optical appearance inspection apparatus according to the present invention further includes illumination means for irradiating the inspection object with light, and the image data in a plurality of lines analyzed by the processing means is applied to the inspection object. At least one of a high brightness area where the brightness of the light is the highest, a brightness change area where the brightness is rapidly changing, and a low brightness stable area where the change is stable at a brightness lower than the brightness change position. It is also desirable to configure to select within one or more regions. It is particularly desirable that the image data of the plurality of lines be selected from each of the high brightness area, the brightness change area, and the low brightness stable area.

As described above, by setting the area for acquiring the image data to be analyzed as the high brightness area, the brightness change area, and the low brightness stable area, the brightness of the light actually irradiated is measured, and the measured data is used. It is possible to specify an area for acquiring image data to be analyzed. The measurement of the brightness of the irradiation light can be measured or set for each inspection object, but when a plurality of inspection objects of the same shape and size are inspected, the irradiation brightness is first measured. Once the line position of the image data to be analyzed is specified, thereafter, by using the image data of a predetermined position (line), it is possible to continuously inspect the appearance of a plurality of inspection objects. Also in this case, in the target to be actually inspected, after confirming which line it is better to acquire the image data to be analyzed, the acquisition position (line) of the image data to be analyzed is specified. Is desirable. In particular, when setting which line of image data is to be analyzed in the luminance change region and the low luminance stable region, defects (concave defects such as flaws, burrs or distortion, foreign matter) on the inspection object to be actually inspected It is desirable to actually measure and identify a position where it is easy to see defects such as adhesion and color defects such as uneven color. When the photographing means is a camera using an image sensor capable of photographing in any plural lines like a CMOS image sensor, it is desirable to acquire image data in the set plural lines.

<About processing and inspection of image data by processing means>
The processing means is, as described above, in the “regions with different light intensities”, “irradiated central region, outline region, and non-irradiated region” or “high luminance region, luminance change region, and low luminance stable region” Obtain image data in multiple lines respectively, perform image processing as necessary, analyze and judge, foreign objects attached to the inspection object, discoloration etc. appearing in the appearance of the inspection object It is possible to inspect various types of defects such as defects, gentle uneven defects on the outer surface of the inspection object, and steep uneven defects such as flaws and burrs. At this time, the image data in a plurality of lines selected from each region can have different widths in each line, and any or all of the image data in a plurality of lines can be adjusted arbitrarily. it can.

That is, the processing means acquires image data in a plurality of lines to be analyzed from the photographed image photographed by the photographing means. As this image data, when the photographing unit is a camera using an image sensor capable of photographing in any plural lines like a CMOS image sensor, scanning of the photographing unit is performed every plural lines (the illumination unit A plurality of line-shaped images (line-shaped images extending in the direction intersecting the scanning direction) are acquired in different lines in relation to the area irradiated with light, and the scanning direction is obtained for each line. , And can be used as an expanded planar image of the entire inspection object. The process of developing such a line-shaped image into a plane image may be performed by a photographing unit or a processing unit.

On the other hand, when the photographing means is a camera using an image sensor for photographing a planar image like a CCD image sensor, the photographed image obtained from the photographing means is a planar image. Then, the processing means selects and extracts each of the predetermined areas as a line-shaped image from each of the plurality of photographed images acquired by scanning the photographing means, and this is extracted in each scanning line in the scanning direction. By connecting them, they can be developed into planar images that cover the entire inspection object, and can be used as image data to be analyzed. However, in this case, processing of extracting a plurality of regions arbitrarily specified in relation to the region irradiated with light by the illumination unit from the planar image acquired in one shooting in a line It will be necessary.

Then, the processing means can analyze changes in color and / or brightness in the image data acquired by the above-mentioned processing, and can judge the presence or absence of each appearance defect in the inspection object. The analysis of the change of the color and / or the brightness with respect to the image data can be made by judging the color and the brightness for each pixel and obtaining the amount of change with the surrounding pixels.

Here, the types of defects that can be inspected include all defects that can be observed from the appearance. That is, in addition to foreign matter, discoloration, and unevenness defects on the surface of the inspection object, foreign matter and discoloration defects existing inside the inspection object can also be inspected as long as they can be transmitted and observed from the appearance. Therefore, carbonized foreign matter of resin which is a manufacturing raw material, discolored defects such as undissolved, melting temperature at the time of resin molding, gentle uneven defects caused by injection pressure, and flaws caused by a mold or an ejector used for molding It is possible to inspect a defect appearing on the appearance of the inspection object such as a steep uneven defect such as a burr.

<< Preferred Embodiment >>
As described above, a linear image obtained for each of a plurality of lines is developed into a planar image for each line and used as image data. Based on this image data, defects in the appearance of the inspection object are detected. In the case of inspection, it is desirable that the scanning for imaging in the imaging means be completed at one time in order to shorten the inspection time. In the present invention, the image data of different positions (lines) can be obtained in relation to the area where the illumination means is emitting light only by scanning the imaging means once. It is possible to inspect kinds of appearance defects.

Furthermore, in the optical appearance inspection apparatus according to the present invention, in order to simplify and miniaturize the configuration of the apparatus itself, it is desirable that there is only one imaging means as a component. That is, it is desirable to acquire image data in a plurality of lines from a photographed image by one photographing means. However, it can also be configured using two or more photographing means. In the case of using two or more photographing means, it is possible to make the area photographed by each photographing means different. Specifically, when the length in the direction orthogonal to the scanning direction of the imaging means (the length in the width direction of the imaging area) is long, a plurality of imaging means can be arranged in the length direction. In this case, the areas photographed by the respective photographing means are different in the longitudinal direction of the inspection object. Also, any of the imaging means may capture some of the image data in a plurality of lines necessary for the examination, and another imaging means may capture the image data in the other line.

Further, in the present embodiment, it is desirable that the photographing means be configured to synthesize optimum image data for each region where the intensity of light irradiated to the inspection object is different. Such an imaging means is an imaging means provided with an optical element in which a plurality of photodiode rows made up of a plurality of photodiodes are arranged in parallel, and imaging with a plurality of photodiode rows is made at any two or more places. In other words, imaging means capable of setting ROI (Reagion Of Interest) in two or more places, preferably three places in the imaging region can be realized.

Therefore, such an imaging means is an imaging means used for an optical appearance inspection apparatus that determines the presence or absence of an appearance defect from an image obtained by imaging an inspection object while scanning, and is arranged in the scanning direction of the inspection object The color and / or brightness of each of the shooting units shooting with a plurality of lines and the plurality of lines shot by the shooting unit are compared based on each region in the direction orthogonal to the scanning direction, and the identification is performed based on this comparison It is possible to obtain a photographing means for an optical appearance inspection apparatus comprising an image processing unit which extracts the line area of and combines these to combine image data of one line.

The imaging unit in the imaging unit can be configured using an imaging element such as a CMOS image sensor or a CCD image sensor, and further includes an optical component such as a lens for condensing and imaging incident light from the inspection object. Can be configured. With regard to such an imaging element, in the case of a CMOS image sensor, since an image for each photodiode row is acquired, color and / or brightness comparison processing for each region aligned in the direction orthogonal to the scanning direction is performed at high speed I can do things. On the other hand, when a CMOS image sensor is used, it is necessary to execute processing such as cutting out image data for each area aligned in a direction orthogonal to the scanning direction from photographed image data.

In addition, the image processing unit in the photographing unit can be configured using a processing device that performs image processing. The processing device may be provided in the same case as the imaging unit, or may be provided in a case or device other than the imaging object to process an image acquired from the imaging unit. . That is, such an imaging unit can be embodied as a module in which an imaging unit and an image processing unit are integrated, or both may be separately provided to realize mutual cooperation processing. Therefore, a digital camera may be used as an imaging unit, and a computer may be used as an image processing unit.

In the above imaging means, a plurality of photodiode rows arranged in a direction crossing the scanning direction are provided adjacent to each other in the scanning direction, and are arranged in the scanning direction in a plurality of photodiode rows acquired in one shooting. The brightness and / or color tone of the photodiodes can be compared, and an image of any photodiode can be extracted or calculated under preset conditions. Then, by connecting the extracted or calculated images together, it is possible to combine image data of one line for the imaging location. By thus generating one line of image data to be used for inspection, the accuracy of inspection can be improved, and by reducing the amount of data, the inspection speed can be increased.

Further, as a condition for extracting or calculating the image of the photodiode (pixel-based image) arranged in the scanning direction, the “processing non-operation mode”, the “maximum luminance mode”, and the “minimum luminance mode” will be described in detail below. It can be configured to select from "average brightness mode", "intermediate brightness mode" and the like.

The "processing non-processing mode" is a mode in which pixels aligned in the scanning direction are acquired as they are, and can be acquired as a monochrome image.
“Maximum luminance mode” is image data in which pixels having the largest luminance among pixels arranged in the scanning direction are extracted from pixel columns arranged in the direction crossing the scanning direction and synthesized into one line. Is the mode to get In this mode, it is possible to generate one line of image data to be used for inspection at the maximum luminance value for bright defects.
The “minimum luminance mode” is a mode in which pixels having the minimum luminance are extracted between the pixels arranged in the scanning direction, and image data obtained by combining the pixels into one line is acquired. In this mode, it is possible to generate one line of image data to be used for inspection with the lowest luminance value for dark defects.
In the "average luminance mode", an average value of the luminances of pixels lined up in the scanning direction is calculated in pixel columns aligned in the direction crossing the scanning direction, and image data obtained by combining the calculated values into one line is acquired It is a mode. In this mode, since the average of the luminance at each pixel is calculated, it is possible to acquire a processed image roughly through a soft filter as image data for inspection.

[Intermediate luminance mode] In this mode, pixels in which the luminance is intermediate between pixels arranged in the scanning direction are extracted, and image data obtained by synthesizing the pixels into one line is acquired. In this mode, since pixels with average brightness are acquired, it is possible to acquire image data from which spike noise has been removed. Particularly in the "average luminance mode", clear image data can be acquired even when the image is blurred.

Further, it is desirable that the photographing means be formed so that the above-mentioned mode can be set for each area where the intensity of light irradiated to the inspection object is different (that is, "partial scan area"). This is to obtain image data required for inspection more clearly in each partial scan area. In addition, it is desirable that the imaging unit be provided with an image adjusting unit that makes the offset value and / or the gain value different for each partial scan area. The areas where the intensity of light irradiated to the inspection object is different are different from each other because the brightness etc. required for imaging differ according to the type of defect appearing on the surface of the inspection object. Alternatively, by providing image adjustment means for making the gain values different, it is possible to obtain optimal image data required for each area. By adjusting the digital gain and the offset, it is possible to obtain an optimal image according to the color and the degree of transmission of the inspection object or the intensity (luminance) of the light to be irradiated.

«About the optical appearance inspection system»
In addition, the optical appearance inspection apparatus according to the present invention can be configured as an optical appearance inspection system by further including a configuration for transporting an inspection object. That is, in the optical appearance inspection system configured using the optical appearance inspection apparatus according to the present invention, the inspection object moving means which further mounts the inspection object and conveys it, and the inspection The movement detection means for detecting the movement speed or movement distance of the inspection object by the object movement means, and the photographed image acquired by the processing means is calculated based on the movement speed or movement amount acquired from the movement detection means The optical appearance inspection system can be configured to acquire in association with the photographed position.

A conveyor, a manipulator, etc. can be mentioned as this inspection object transport means. Moreover, a rotary encoder, a linear encoder, etc. can be mentioned as a transfer detection means. Then, the imaging unit constituting the optical appearance inspection apparatus captures an image at the timing at which the signal derived from the moving speed or the moving distance acquired from the transfer detecting unit is acquired, and the image of each line in the photographed image (line Image can be associated with the imaging position. As a result, it is possible to suppress the variation in imaging resolution due to the fluctuation of the moving speed of the inspection object in the inspection object moving means, and to correct the position when developing a plane image from a plurality of acquired line images Become.

In the above-described optical appearance inspection system, the inspection object moving means may include holding means for suctioning the inspection object to be transported in a placed state or pressing the inspection object. This is in order to keep the distance to the imaging means constant when the inspection object is plate-like or sheet-like. The holding means blows downflow air against the inspection object to press the inspection object against the inspection object moving means, or the surface on which the inspection object is placed in the inspection object moving means Can be embodied as a configuration in which a minute opening is provided and the mounting surface of the inspection object is sucked from the opening. Such holding means is sufficient if the inspection object is in close contact with the inspection object moving means at least at the time of photographing by the photographing means.

Further, in the optical appearance inspection system according to the present invention, the thickness of the object to be inspected can also be inspected. That is, thickness measuring means for measuring the thickness of the inspection object can be further provided on the movement path of the inspection object in the inspection object moving means. Preferably, the processing apparatus is configured to detect a defect in thickness based on the measurement value of the thickness measuring means.

As this thickness measurement means, a reflection type laser displacement meter can be used, and defects in the thickness of the inspection object can be inspected from the measurement results of the thickness measurement means. In addition, the thickness of the inspection object can be obtained from the measurement result of the thickness measurement means, and the position of the line of the image data analyzed by the processing means (acquisition position in the photographing means) can be adjusted based on this.

The processing means can also control the operation of each device constituting the optical appearance inspection apparatus of the present invention, and, for example, the position of the photographing means, the position and brightness of the illumination means, and the plurality analyzed by the inspection means. The acquisition position of the image data in the line can also be controlled. Further, this processing means can determine the presence or absence of a defect in the appearance based on the acquired or processed image. In this determination, it is possible to identify an area having a difference in color tone, lightness, brightness and the like in the image, and further to determine the size of the area from the number of pixels and the like. As a result, it is possible to automatically specify an inspection object having an appearance defect based on the judgment result of the processing means.

And the inspection object which can inspect the appearance with the optical appearance inspection apparatus according to the present invention and the optical appearance inspection system using the same is not particularly limited, and agricultural products, aquatic products, or the like thereof It may be food products such as processed products, and various industrial products such as resin plates, glass plates, metal plates, electronic parts / products, optical parts / products and the like. However, it is desirable that the object to be inspected has a shape with less unevenness in appearance. For example, in a plate-like body or a cylinder, defects in the appearance can be inspected more accurately. Also, the inspection object may be transparent or opaque.

According to the above-described optical appearance inspection apparatus according to the present invention, image data in a plurality of lines can be acquired simultaneously by one imaging means, so the number of imaging means to be used can be reduced, and It is possible to reduce the number of installed devices, and thus to provide an optical appearance inspection apparatus in which the apparatus itself is miniaturized and an optical appearance inspection system using the same.

In addition, when acquiring a plurality of image data necessary for the appearance inspection, it is not necessary to move the photographing means and the illumination means, and therefore, it is not necessary to operate the optical devices. Thus, an optical appearance inspection apparatus capable of performing various types of inspections in a short time and an optical appearance inspection system using the same are realized. In particular, when a camera using an image sensor capable of photographing at an arbitrary line, such as a CMOS image sensor, is used as a photographing means, the inspection time can be further shortened because the image processing speed is increased.

In addition, where the size, height or thickness of the inspection object is various, in the optical appearance inspection apparatus according to the present invention, it is necessary to select the line for acquiring the image data to be analyzed. It is not necessary to adjust the installation position and angle of the illumination means. Therefore, even when inspecting inspection objects having different sizes, heights, or thicknesses, it is not necessary to change the height or angle of the camera, the illumination, or the inspection object, which has conventionally been troublesome. An optical appearance inspection apparatus capable of inspecting the appearance of an inspection object and an optical appearance inspection system using the same are realized.

In the optical appearance inspection apparatus according to the present invention, since a plurality of images necessary for the appearance inspection can be obtained by one scanning by the photographing means, various types of defects appearing in the appearance of the inspection object can be obtained. An optical appearance inspection apparatus capable of performing inspection in one shot and an optical appearance inspection system using the same are realized.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows the optical appearance inspection system comprised using the optical appearance inspection apparatus concerning this Embodiment. (A) a perspective view showing an appearance inspection station, (B) an enlarged plan view of an essential part showing an irradiation condition of a light to an inspection object and a reading position to explain processing contents in the optical appearance inspection apparatus, (C) processing It is a top view which shows the image data for analyzing in an apparatus. Explaining that various defects can be inspected, (A) An enlarged view of an essential part showing a state where a defect sample is provided on an inspection object, (B) showing how defects are seen in a region irradiated with transmitted light A schematic front view, (C) A schematic front view showing the appearance of defects in the outline of the area irradiated with transmitted light, (D) An area not irradiated with transmitted light, the appearance of defects in the area near the outline area It is a front schematic diagram which shows the direction. The optical appearance inspection apparatus in other embodiment is shown, (A) The principal part expansion perspective view of the said optical appearance inspection apparatus, (B) The process which extracts the line-form image in several lines from the image which image | photographed It is a conceptual diagram which shows the content, (C) It is a top view which shows the image data used as analysis object synthesize | combined from the image of a line form. Explains how defects appear when the inspection object is opaque. (A) An enlarged view of a main part showing the inspection object provided with a defect sample, (B) a defect in a region irradiated with light A schematic front view showing the appearance of (C) a schematic front view showing the appearance of defects in the outline of the area irradiated with light, (D) an area not irradiated with light, in the area near the outline area It is a front schematic diagram which shows the appearance of a defect. It is a perspective view which shows the inspection method in, when a test object is cylindrical shape. It is a perspective view which shows the inspection method in case a test object is long in the width direction. It is a schematic diagram which shows the principle of the imaging | photography means used with an optical appearance inspection apparatus. It is a schematic diagram which shows the formation principle of the image data by an imaging | photography means.

Hereinafter, several embodiments of the optical appearance inspection apparatus according to the present invention will be described with reference to the drawings. In particular, in the following embodiment, although it shows concretely as optical appearance inspection device 50 for inspecting the appearance of industrial products (including parts), inspection object object W is not restricted to these, but various things are It can be targeted.

FIG. 1 is an overall configuration diagram showing an optical appearance inspection system 60 configured using the optical appearance inspection apparatus 50 according to the present embodiment. In the present embodiment, in particular, the inspection object W is configured to inspect a plate-like transparent object, and as an example, a configuration suitable for inspecting the light guide plate And

As shown in FIG. 1, in the optical appearance inspection system 60 shown in this embodiment, a receiving station 10 for receiving a light guide plate which is an inspection object W, and the optical appearance inspection apparatus 50 are installed to be inspected. It comprises an appearance inspection station 20 which inspects the appearance of W, a thickness inspection station 30 which inspects the thickness of the inspection object W, and an unloading station 40 which sends out the inspection object W whose inspection is completed.

At the receiving station 10, a work to be an inspection object W in the optical appearance inspection system 60 is received. In the present embodiment, since the inspection object W is a thin plate-like light guide plate, warpage, lifting, and the like easily occur, and therefore, warpage, lifting, and the like occur in the appearance inspection station 20 and the thickness inspection station 30 which follow. It is desirable that the inspection object W be in close contact with the inspection object moving means 11 by a holding means (not shown) so as not to adversely affect the inspection. Such holding means may be realized as a structure for suctioning the inspection object W toward the inspection object moving means or a configuration for blowing air from above onto the inspection object W and pressing the inspection object movement means 11. it can. Then, while being held by the holding means, the inspection object W delivered at the receiving station 10 horizontally moves the visual inspection station 20 and the thickness inspection station 30 which follow thereafter, and reaches the unloading station 40. The holding means may be configured to hold the inspection object W only when the inspection is actually performed, such as the appearance inspection station 20 and the thickness inspection station 30, etc.

In addition, various conveyors and the like can be used as the inspection object moving means 11 for transferring the inspection object W to each station. In particular, since the inspection object W in the present embodiment is transparent and the illumination means 52 used is transmission illumination, the inspection object moving means 11 for conveying the inspection object W is an appearance inspection to be described later. It is provided to pass between the imaging means 51 provided in the station 20 and the illumination means 52.

Further, as described above, the inspection object W is transparent, and the photographing means 51 is configured to photograph the transmitted light transmitted through the inspection object W, so the inspection object moving means 11 and the inspection It is desirable that the holding means of the object W be configured so as not to block between the photographing means 51 and the illumination means 52. This is to enable imaging of the entire inspection object W formed transparent. Specifically, the inspection object moving means 11 is formed of a transparent material so as not to affect imaging, or is held at a position that does not affect imaging such as the side surface of the inspection object W. It may be configured to be transported, and the holding mechanism of the inspection object W may be formed of a transparent material so as not to affect imaging, or may be held by the flow of air. It can be configured.

The appearance inspection station 20 inspects the appearance of the inspection object W. The optical appearance inspection apparatus 50 installed in the appearance inspection station 20 transmits light as illumination means 52 for emitting light so as to transmit the inspection object W, and the inspection object for which light is emitted by the illumination means 52 A camera using a CMOS image sensor as the photographing unit 51 for photographing W and a photographed image photographed by the photographing unit 51 are obtained, and the inspection object W is obtained based on image data of a plurality of lines having different light intensities. A control device as processing means 53 for judging the presence or absence of an appearance defect is configured as a main component.

In particular, since the inspection object W in the present embodiment is a transparent product and the illumination means 52 used is transmission illumination, the photographing means 51 is provided to face the illumination means 52, Desirably, the photographing means 51 is provided so that the photographing direction faces the irradiation direction of the illumination means 52.

The transmitted illumination used as the illumination means 52 can emphasize the defect by irradiating the inspection object W with light. The illumination means 52 preferably uses an LED as a light source in order to ensure stable irradiation performance even in long-term and long-term operation, and a defect in appearance is judged based on image data of a plurality of lines. Therefore, it is desirable to use line lighting. In addition, the illumination means 52 may adjust the wavelength of the irradiated light arbitrarily in accordance with the material, color and the like of the inspection object W. When the inspection object W is red, light in the red wavelength region can be irradiated, and when the inspection object W is green, light in the green wavelength region can be irradiated. When the inspection object W is formed of a material having a high reflectance such as metal or is formed of a transparent material, it is desirable to irradiate light in the blue wavelength range. This is because light in the blue wavelength range has a short wavelength and reflected light and transmitted light are easily scattered.

In order to clearly illuminate the inspection object W conveyed by the inspection object moving means 11, it is desirable that the illumination means 52 be installed in the vicinity of the conveyance means. However, in order to adjust the width of the contour of the area illuminated by the illumination means 52 or to adjust the luminance of the illuminated area, the illumination means 52 comprises the inspection object moving means 11. You may install so that a space | interval can be adjusted arbitrarily.

The camera used as the imaging unit 51 includes a CMOS image sensor as an imaging device, and includes a planar imaging device in which a plurality of photodiodes are arranged in the vertical and horizontal directions. For example, an imaging element having 2048 pixels in the horizontal direction (the width direction with respect to the scanning direction) and 2048 pixels in the vertical direction (the scanning direction) can be used. In the photographing means 51 provided with such an image sensor, when the visual field in the horizontal direction is 200 mm, the visual field in the vertical direction is also 200 mm. Therefore, the photodiode used for photographing in this visual field in the vertical direction When a plurality of columns are specified, image data in a plurality of lines can be acquired by scanning the imaging unit 51. In addition, by changing the position (line) of the photodiode row used for photographing in this vertical visual field, it can be operated as if using a plurality of line sensors, and the angle of view is open It is possible to perform an operation that changes the angle depending on the angle.

Then, the control device used as the processing means 53 acquires the photographed image photographed by the photographing means 51, analyzes the image data of a plurality of lines, and judges the presence or absence of the defect in the appearance. The image data used for this analysis may be obtained by using the photographed image photographed by the photographing means 51 as it is or connecting the photographed image for every plural lines and developing it into a planar image. Therefore, the processing means 53 is configured with a CPU (Central Processing Unit), a memory and the like for analyzing image data and performing numerical calculation and information processing necessary for performing image processing as necessary. . A computer can be used as such a processing device, but it may be a device designed to perform numerical calculation and information processing necessary for analyzing and judging defects in image processing and appearance. The processing means 53 can also control which line of the photodiode row arranged in the scanning direction of the photographing means 51 in the image pickup device.

In addition, in order to correlate the photographed image acquired from the photographing unit 51 with the photographing position of the inspection object W, a transfer detection unit that detects the horizontal movement distance and moving speed of the inspection object W by the inspection object moving unit 11 It is desirable to provide 54. As the transfer detection means 54, a rotary encoder, a linear encoder or the like can be used. The transfer detection means 54 can be installed at any place in the transport path of the inspection object W, and desirably the appearance inspection in order to accurately measure the horizontal movement distance and speed of the inspection object W It is installed at the station 20, and more preferably installed near the imaging area in the imaging means 51. The detection signal from the transfer detection means 54 is sent to the processing means 53 to suppress the variation of the imaging resolution due to the change of the moving speed of the inspection object W by the inspection object moving means 11. When developing an image acquired in a shape into image data (planar image) used for analysis, the position correction can be made possible.

And in thickness inspection station 30, it is inspected whether thickness in inspection object W is in a predetermined range. That is, in the thickness inspection station 30, the thickness of the inspection object W transported by the inspection object moving means 11 is measured by the thickness detection means 31 formed of a reflection type laser displacement meter. The measurement result is sent to the processing means 53, and the processing means 53 can detect a defect in the thickness of the inspection object W.

The optical appearance inspection system 60 shown in FIG. 1 is configured such that the inspection object W is particularly transparent, and a captured image is acquired by transmissive illumination. That is, the illumination means 52 is provided on the opposite side across the inspection object W. In this respect, if the inspection object W is not transparent, it is not possible to acquire image data by transmitted illumination. Therefore, when the inspection object W is opaque, as shown in FIG. 4 described later, the reflection illumination is used, and the photographing unit 51 photographs the reflected light of the light irradiated to the inspection object portion, as described above. Image data can be acquired. At that time, it is desirable that the illumination means 52 irradiate light to the inspection object W from the photographing direction by the photographing means 51, and in particular, it is preferable to irradiate light vertically above the inspection object W.

Next, the processing contents of the optical appearance inspection apparatus 50 in the appearance inspection station 20 will be described with reference to FIG. 2 (A) is a perspective view showing the appearance inspection station 20, and FIG. 2 (B) is an enlarged plan view of the main part showing the irradiation condition of the light to the inspection object W and the reading position. These are top views which show the image data for analyzing in a processing apparatus.

First, in the appearance inspection station 20, the inspection object W is transported by the inspection object moving means 11 such as a conveyor, and the illumination means 52 is provided below the inspection object moving means 11. The illumination means 52 is a line illumination, and illuminates light throughout the width direction (the direction intersecting the transfer direction) of the inspection object W. The light of the illumination means 52 is transmitted through the inspection object W, whereby the photographing means 51 provided above the inspection object W can photograph the transmitted light of the inspection object W. Then, the inspection object W passes between the illumination means 52 and the photographing means 51.

As shown in FIG. 2B, in the imaging unit 51, in the area illuminated by the transmitted light, the bright area A1, its outline area A2, and the area not irradiated with the transmitted light, and the outline area In the area A3 of the near area, the image data captured by the line extending in the width direction (the direction intersecting the scanning direction) of the inspection object W is acquired. The imaging in each line is performed while transporting the inspection object W, and is imaged each time it moves by the number of pixels acquired in at least one imaging. The transfer distance of the inspection object W is detected by the transfer detection means 54 such as the rotary encoder. Therefore, at the time when the signal indicating movement by a fixed distance is obtained from the transfer detection means 54, the photographing means 51 can take an image on a predetermined line.

Then, after the imaging in each line shown in FIG. 2 (B) is performed for the entire inspection object W, the line-shaped images taken each time the inspection object moves are joined together, as shown in FIG. The image data D1 to D3 expanded into the surface image as shown in 2.) are formed. That is, in the area illuminated by the transmitted light, the image data D1 formed of the image obtained by photographing the bright area A1 and the image obtained by imaging the area A2 not illuminated by the transmitted light but in the vicinity of the outline area The image data D2 formed as described above and the image data D3 formed of an image obtained by photographing an area A3 which is an area not irradiated with transmitted light and which is in the vicinity of the outline area are formed. In the formation of such image data, the processing device acquires a line-shaped image every time the image pickup means 51 takes an image, and expands the image into a planar image. It may be recorded and sent to the processing means 53 after being synthesized to the plane image. Each plane image (image data) in each line formed in this manner is obtained by photographing a state in which the irradiation direction of light to the inspection object W is made different. Therefore, although the light can be acquired by one scan by the imaging unit 51, the same image data as in the case where the imaging unit 51 is scanned a plurality of times can be acquired by changing the irradiation angle of light.

Next, referring to FIG. 3, an example of inspecting various defects by using image data in a plurality of lines having different light irradiation conditions will be described. FIG. 3A is an enlarged view of an essential part showing a state in which a defect sample is provided on the inspection object W, and FIG. 3B is a front view showing how a defect appears in a region irradiated with transmitted light. FIG. 3C is a schematic front view showing how defects appear in the outline of the area irradiated with transmitted light, and FIG. 3D is an area not irradiated with transmitted light 6 is a schematic front view showing how a defect appears in a region near the contour region.

In this example, the inspection object W is transparent, and FIGS. 3B to 3D show how the transmitted light looks when it is irradiated with light. In the inspection object W, as a sample, as shown in FIG. 3A, from the top in order from the top, flaw defects F1 such as flaws present on the surface, color defects F2 in which black foreign matter is present on the surface or inner surface, surface An uneven defect F3 is formed which is composed of gentle unevenness in the above.

In the sample inspection object W in which such a defect is formed, as shown in FIG. 3 (B), the color defect F2 appears clearly in the area A1 where the light is irradiated to the back surface, The defect F1 and the uneven defect F3 do not appear clearly. Further, as shown in FIG. 3C, in the contour area A2, the uneven defect F3 appears clearly, while the color defect F2 and the flaw defect F1 do not appear clearly. Then, as shown in FIG. 3D, in the area A3 where light is not irradiated, the flaw defect F1 appears clearly, while the color defect F2 and the concavo-convex defect F3 do not appear clearly.

As described above, since the types of defects that appear clearly in the relationship with the area irradiated with light are different, the image data in the plurality of lines are respectively analyzed to obtain a plurality of images acquired in one scan. Image data can be used to inspect various cosmetic defects.

In the above embodiment, since the inspection object W is a transparent product, transmissive illumination is used as the illumination means 52, but when the inspection object W is opaque, the following As shown in FIG. 4, the illumination unit may be provided on the photographing unit 51 side, and the photographing unit 52 may be configured to photograph the reflected light of the light irradiated to the inspection object W. In the above embodiment, a camera using a CMOS image sensor is used as the photographing means 51. However, a camera using a CCD image sensor for photographing a predetermined area as a plane image may be used. In the case, image processing such as extraction of a line-shaped image as shown in FIG. 4 below is performed.

FIG. 4 shows an optical appearance inspection apparatus 150 according to another embodiment, and the optical appearance inspection apparatus 150 is also installed in the appearance inspection station 20 of the optical appearance inspection system 60 shown in FIG. Can. The optical appearance inspection apparatus 150 shown in this embodiment particularly uses a camera using a CCD image sensor as the photographing means 151, and the illumination means 152 is configured to photograph reflected light, not transmitted light. . FIG. 4 (A) is an enlarged perspective view of an essential part showing an optical appearance inspection apparatus 150 according to another embodiment, and FIG. 4 (B) is a process for extracting line-shaped images in a plurality of lines from photographed images. It is a conceptual diagram which shows the content, FIG.4 (C) is a top view which shows the image data used as analysis object synthesize | combined from the line-form image.

Also in this embodiment, the inspection object W is transported by the inspection object moving means 11 such as a conveyor. Light is emitted from the illumination means 152 provided above the inspection object W transported. Then, in the photographing means 151 provided above the inspection object W in the same manner as the illumination means 152, an area which is at least irradiated with light and which is in the vicinity of the irradiated area and which is not irradiated with light The image is taken so that the entire width direction of the inspection object W is captured. The captured image is associated with the transfer distance or the like measured by the transfer detection unit such as a rotary encoder, as in the above-described embodiment.

Then, as shown in FIG. 4B, a line-shaped image is extracted from an area set arbitrarily from an image obtained by photographing a certain area. That is, a line-shaped image is drawn from the respective lines of the area A1 illuminated by the light emitted from the illumination means 152, its outline area A2, and the area not irradiated with light but in the vicinity area A3 of the outline area. Extract (L1 to L3). That is, the linear image L1 is extracted from the area A1 illuminated by light, and the linear image L2 is extracted from the outline area A2 of the area A1 illuminated by light, and the area is not irradiated with light. A linear image L3 is extracted from the vicinity area A3 of the outline area.

Then, the extracted line-shaped images are connected to each other to combine image data composed of planar images as shown in FIG. 4C. That is, the image data D11 in which the linear images L1 extracted from the lighted area A1 are joined and the linear image L2 extracted from the outline area A2 of the light A1 are connected. The image data D12 and the image data D13 in which the linear image L3 extracted from the vicinity area A3 of the area which is not irradiated with light and is extracted are respectively synthesized. Then, it is possible to determine the presence or absence of each appearance defect in the inspection object W by analyzing the change in color and / or brightness of each of the synthesized plane images (image data).

Next, with reference to FIG. 5, the appearance of a defect when the inspection object W is opaque will be described. FIG. 5 shows how the reflected light looks when the inspection object W is irradiated with light, and FIG. 5 (A) is a main part enlarged view showing the inspection object W provided with a defect sample. FIG. 5 (B) is a schematic front view showing the appearance of defects in the area irradiated with light, and FIG. 5 (C) shows the appearance of defects in the outline of the area irradiated with light. FIG. 5 (D) is a schematic front view showing an appearance of a defect in a region not irradiated with light and in the vicinity of the contour region.

In this example, the inspection object W is opaque, and FIGS. 5B to 5D show how the reflected light appears when the inspection object W is irradiated with light. In the inspection object W, as shown in FIG. 5A as a sample, in order from the top, a foreign matter defect F11 such as a black foreign matter existing on the surface, a hole defect F12 such as a penetrating hole, and the like A flaw defect F13 such as a flaw is formed.

In the sample inspection object W in which such a defect is formed, as shown in FIG. 5B, the hole defect F12 clearly appears in the area A1 where the light is irradiated to the surface, while the foreign matter The defect F11 and the flaw defect F13 do not appear clearly. Further, as shown in FIG. 5C, in the contour area A2, the foreign matter defect F11 clearly appears, while the hole defect F12 and the flaw defect F13 do not clearly appear. Then, as shown in FIG. 5D, in the area A3 where the light is not irradiated, the flaw defect F13 clearly appears, while the foreign matter defect F11 and the pore defect F12 do not clearly appear.

As described above, even if the inspection target is opaque, by photographing the reflected light, the types of defects that clearly appear differ in relation to the area irradiated with the light. Therefore, by analyzing the image data in each of the plurality of lines, it is possible to inspect various appearance defects using a plurality of image data acquired in one scan.

In the present embodiment, the case where the inspection object W is opaque has been described, but in the case of transparency, as shown in FIG. 2, the illumination means 52 for emitting the transmission illumination can be used. . Further, as described in the present embodiment, even when the inspection object W is opaque, as described above, the photographing means 51 formed of a camera using a CMOS image sensor can be used, and in this case, Can develop an image taken at each line into a plane image to inspect a defect.

FIG. 6 is a perspective view showing an inspection method when the inspection object W is cylindrical. As shown in this figure, when the inspection object is cylindrical and the appearance on the circumferential surface is inspected, the appearance inspection can be performed by rotating the inspection object W around the axis. In particular, when the inspection object W has a curved surface, by using a camera using a CMOS image sensor as the photographing means 51, the problem of distortion of the image on the curved surface can be eliminated, and the appearance inspection is performed more accurately. I can do things. However, even in this embodiment, a camera using a CCD image sensor may be used as the photographing means.

FIG. 7 is a perspective view showing an inspection method in the case where the inspection object W is long in the width direction, that is, in the direction orthogonal to the transfer direction. As shown in this figure, when the inspection object is wide, a plurality of imaging means 51 can be used side by side in the width direction. In this case, a plurality of photographing means 51 will be used. However, image data in a plurality of lines is acquired by any one imaging unit 51 in the range in any width direction. In FIG. 7, the imaging means 51 is arranged in a line, but may be arranged in a zigzag. However, it is necessary to be able to specify the imaging range so that the imaging region can be connected later without any gap in the imaging region in the width direction. However, even in this embodiment, a camera using a CCD image sensor may be used as the photographing means.

According to the optical appearance inspection apparatus configured as described above, it becomes possible to simultaneously inspect all defects generated in the manufacturing process of the inspection object W in one imaging condition under one imaging condition, Further, even when the inspection object W is a product having a different thickness, image data necessary for inspection is acquired to analyze / determine defects without physically adjusting the optical system such as the photographing unit and the illumination unit. I can do things.

Next, referring to FIGS. 8 and 9, imaging means which can be suitably used in the optical appearance inspection apparatus according to the present embodiment will be described. As shown in FIG. 8, such an imaging means is configured by arranging a plurality of photodiode rows, in which a plurality of photodiodes are arranged in a direction intersecting the scanning direction, in parallel, in the scanning direction. FIG. 8 shows four photodiode rows made up of A to D rows, each row consisting of nine photodiodes arranged in the arrangement direction. By photographing with the photographing means configured in this way, it is possible to photograph an image of 36 columns in total of 4 columns × 9.

In particular, the photographing means according to this embodiment is further configured to include an image processing unit, and the image processing unit executes processing to reduce the image size of 36 pixels. Specifically, for all pixels lined in the arrangement direction, processing for calculating or extracting pixels of the brightness set in advance such as maximum brightness, minimum brightness, average brightness and the like from pixels lined in the scanning direction Run. Then, according to this condition, one row of image data is generated by connecting the calculated or extracted pixels, and this one row of image data is used for surface inspection. FIG. 8 shows an arrangement of photodiodes, and when this is viewed as a pixel photographed by each photodiode, pixels having the lowest luminance are extracted. In FIG. 8, when the photodiode array is viewed as an array of pixels, the B1 pixel having the lowest luminance is extracted in the pixels A1 to D1 and the luminance is the lowest also in the pixels A2 to D2 arranged next to each other. Extract C2 pixels. Then, such calculation or extraction processing is executed up to the pixels A9 to D9 to generate one line of image data composed of the pixels B1, C2, A3, B4, C5, D6, B7, C8 and A9. As a result, an image of 36 pixels can be synthesized into image data of 9 pixels, thereby reducing the amount of data and increasing the processing speed. Note that such pixel extraction can also be performed by the processing means.

FIG. 9 is a schematic view showing a process of computing or extracting one row of image data from an image obtained by actually capturing an inspection object. As shown in FIG. 9A, the inspection object W is photographed, and an image consisting of ten rows of pixels arranged in the scanning direction is photographed. Each row can be composed of pixels according to the optical element. Then, as shown in FIG. 9B, the pixels in the respective columns aligned in the scanning direction are compared from the photographed pixels, and as shown in FIG. 9C, the pixel having the highest luminance is extracted. By performing this process up to the arrangement direction of the pixels in each column and combining the extracted pixels into one column, image data of one column can be generated. And since this generated image data of one row is used for inspection, the image data used for inspection can be greatly reduced and processing speed can be improved.

In the inspection apparatus using such a photographing means, the inspection speed can be increased by setting the transfer distance of the inspection object to the number of pixel rows photographed in approximately one photographing. That is, in FIG. 9, a large number of inspection objects can be inspected by transferring the inspection object by 9 pixels or 10 pixels and imaging them.

On the other hand, in the case where the transfer distance of the inspection object is shorter than the pixel row captured in one shooting, an image of a wide range including the periphery may be obtained for any of the regions. it can. For example, as shown in FIG. 9, when ten photodiode rows are arranged in the scanning direction, imaging can be performed by transferring one to five rows. Then, by extracting a pixel (a pixel set in advance as a condition) suitable for the purpose from among the photographed pixels, it is possible to acquire more accurate image data without omission of photographing. Therefore, in this case, surface inspection can be performed with high accuracy.

The optical appearance inspection apparatus according to the present invention is used to inspect defects in appearance of various articles such as raw materials, agricultural products, marine products, or processed products thereof as well as industrial products. Can. The inspection object W can be inspected for appearance regardless of whether it is transparent or opaque.

10 Receiving Station
11 inspection object moving means
20 Appearance inspection station
30 inspection station
31 Detection means
40 unloading station
50, 150 Optical appearance inspection device
51, 151 shooting means
52, 152 Lighting means
53 Processing means
54 Transfer detection means
60 Optical appearance inspection system
W inspection object

Claims (12)

A photographing means for photographing an inspection object;
And processing means for analyzing and judging the presence or absence of an appearance defect in the inspection object using the photographed image photographed by the photographing means;
The processing means acquires a photographed image from the photographing means, and analyzes changes in color and / or brightness of image data in a plurality of lines respectively selected from regions different in the intensity of light irradiated to the inspection object. An optical appearance inspection apparatus characterized by judging the presence or absence of each appearance defect in an inspection object.
Furthermore, illumination means for irradiating light to the inspection object is provided,
2. The optical system according to claim 1, wherein the image data in the plurality of lines analyzed by the processing means is selected from each of an area within the area illuminated by the illumination means and an area outside the area illuminated by the illumination means. Type appearance inspection device.
Furthermore, illumination means for irradiating light to the inspection object is provided,
The image data in a plurality of lines analyzed by the processing means includes an irradiation central area which is a central portion of an area irradiated with light by the illumination means, an outline area of an area irradiated with light by the illumination means, and the outline The optical appearance inspection apparatus according to claim 1, wherein the optical appearance inspection apparatus is selected in at least any two or more areas of the non-irradiated area near the area and not irradiated with the light by the illumination means.
Furthermore, illumination means for irradiating light to the inspection object is provided,
The image data in a plurality of lines analyzed by the processing means is a high brightness area where the brightness of light irradiating the inspection object is the highest, a brightness change area where the brightness changes rapidly, and the brightness change position The optical appearance inspection apparatus according to claim 1, wherein the optical appearance inspection apparatus is selected in at least any two or more areas of a low luminance stable area where the change is stable at lower luminance.
The image data to be analyzed by the processing means is obtained by scanning a photographing means to obtain a plurality of line-like images respectively taken on a plurality of lines, and combining and developing this for each line. It is an image,
The optical appearance inspection apparatus according to any one of claims 1 to 4, wherein acquisition of image data in a plurality of lines in the processing means is acquired by one scan in an imaging means.
The photographing means is an image sensor camera which scans the inspection object in a predetermined direction,
The image data in a plurality of lines analyzed by the processing means is a plane image obtained by combining images taken in a line shape extending in a direction crossing the scanning direction at a plurality of different positions in the scanning direction of the photographing means The optical appearance inspection apparatus according to any one of claims 1 to 5, which is
The photographing means is
An imaging unit for imaging a plurality of lines aligned in the scanning direction of the inspection object;
The color and / or brightness of each of the plurality of lines photographed by the photographing unit are compared for each area in the direction orthogonal to the scanning direction, and then the area of the specific line is extracted based on the comparison. And an image processing unit that combines the image data of one line,
The imaging unit performs imaging with a plurality of lines arranged in the scanning direction of the inspection object, in each of a plurality of lines respectively selected from regions with different intensities of light irradiated to the inspection object.
The optical appearance inspection apparatus according to any one of claims 1 to 6, wherein a plurality of image data of one line synthesized by the image processing unit are used as the image data of the plurality of lines analyzed by the processing means.
The image pickup means according to any one of claims 1 to 7, wherein the photographing means comprises an image adjustment means for making the offset value and / or the gain value different for each area where the intensity of the light irradiated to the inspection object is different. Optical appearance inspection device.
An optical appearance inspection system configured using the optical appearance inspection apparatus according to any one of claims 1 to 8, comprising:
The apparatus further comprises inspection object moving means for carrying the inspection object by placing the inspection object thereon, and transfer detection means for detecting the moving speed or movement distance of the inspection object by the inspection object moving means.
The optical appearance inspection system according to claim 1, wherein the photographed image acquired by the processing means is associated with the photographing position calculated based on the movement speed or movement amount acquired from the transfer detection means.
The inspection object moving means is provided with a holding means for suctioning or pressing the inspection object to be placed and transported.
Thickness measuring means for measuring the thickness of the inspection object is provided on the movement path of the inspection object in the inspection object moving means,
The optical appearance inspection system according to claim 9, wherein the processing means detects a defect in thickness based on a measurement value of the thickness measurement means.
An imaging unit for use in an optical appearance inspection apparatus that determines the presence or absence of an appearance defect from an image obtained by capturing an inspection object while scanning.
It comprises an optical element in which a plurality of photodiode rows composed of a plurality of photodiodes are arranged in parallel, and imaging with a plurality of photodiode rows can be realized in any two or more places in the optical element An imaging means for an optical appearance inspection apparatus, characterized in that
An imaging unit for use in an optical appearance inspection apparatus that determines the presence or absence of an appearance defect from an image obtained by capturing an inspection object while scanning.
An imaging unit for imaging a plurality of lines aligned in the scanning direction of the inspection object;
The color and / or brightness of each of the plurality of lines photographed by the photographing unit are compared for each area in the direction orthogonal to the scanning direction, and then the area of the specific line is extracted based on the comparison. An imaging unit for an optical appearance inspection apparatus, comprising: an image processing unit that combines the image data of one line and combines the image data.

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