WO2005100960A1

WO2005100960A1 - Surface defect examining device

Info

Publication number: WO2005100960A1
Application number: PCT/JP2004/015467
Authority: WO
Inventors: Mamoru Sakaue; Chie Ishikawa; Makoto Iwata; Toshiyuki Kaya; Chimoto Takada; Akifumi Seo; Norio Endo
Original assignee: Daihatsu Motor Co., Ltd.; Chuo Electronic Measurement Co., Ltd.
Priority date: 2004-03-31
Filing date: 2004-10-20
Publication date: 2005-10-27
Also published as: JP2005291845A; JP4318579B2

Abstract

A surface defect examining device (100) comprising an irradiation system provided with a plurality of light-emitting elements (30) arranged in a predetermined layout pattern and an imaging camera (4) for imaging a surface to be examined irradiated with irradiation light from the light-emitting elements, wherein the layout pattern is such that the light-emitting elements are arranged continuously to leave dark surfaces (31) of predetermined shapes inside the layout pattern, the imaging camera is arranged on at least one dark surface to receive the light emitted from each light-emitting element and reflected off the surface being examined, and a copying unit (100a, 100b, 100c, Mb, Mc, Md) for moving the plurality of light-emitting elements and the imaging camera in one united body along the surface being examined are provided. The arrangement of the irradiation system and the imaging system is simple and rational, and highly reliable examination can be ensured.

Description

Surface defect inspection equipment

Technical field

[0001] The present invention provides a plurality of light emitting elements arranged in a predetermined layout pattern, an imaging camera for imaging a surface to be inspected illuminated by light emitted from the light emitting elements, and imaging information of the imaging camera. BACKGROUND OF THE INVENTION 1. Field of the Invention

[0002] As a typical example of this type of surface defect inspection apparatus, there is a technique used for inspecting a painted surface of an automobile body (specifically, a bumper). In such a surface defect inspection, irregularities, scratches, and the like existing on the painted surface as the surface to be inspected are to be inspected.

As an example of an inspection technique that uses inspection light with a specific pattern, a painted surface of a vehicle body is illuminated with irradiation light that creates a bright B-tone sound pattern, and the illuminated painted surface is imaged by an imaging camera. A technique of performing a surface inspection using an obtained captured image is known.

[0003] Fig. 10 illustrates a specific configuration of an inspection system using this technology. A technique using the same inspection principle as that of FIG. 10 is described in Patent Document 1 below.

That is, in the defect inspection system shown in FIG. 10, a plurality of bumpers to be inspected are stocked at the stock station 202, and the first inspector 204 removes the bumper 1 from the stock station 202 and attaches it to the arm of the robot 22. Attach. The robot 22 can change the posture of the bumper 1 by rotating the arm around the rotation axis 22d.

An illumination device 220 having a horizontal stripe light emission pattern is provided so as to surround the bumper 1 attached to the robot 22. The light emission pattern is a stripe-like light / dark pattern extending parallel to the rotation axis 22d of the bumper 1.

While the posture of the bumper 1 is changed by the robot 22, the light and dark patterns of the irradiation light reflected on the bumper 1 are imaged by the plurality of imaging cameras 4. The imaging result is sent to the analysis side. Then, the presence or absence of a defect is evaluated.

The second inspector 201 located on the lower side of the robot 22 removes the bumper 1 whose imaging has been completed from the robot 22, and performs a post-process such as a visual inspection.

The evaluation result of the bumper 1 by the defect evaluation unit and the information of the spot to be noticed in the visual inspection have already been sent to the second inspector in the subsequent process. Therefore, the second inspector can proceed quickly and reliably.

FIG. 11 shows the basic principle of the above-described surface defect inspection.

As shown in Fig. 11, if the painted surface is moved in the direction of arrow R, the image force of a defect such as a concave or convex surface on the painted surface becomes a coordinate in the direction orthogonal to the R direction (the direction of the front and back of the paper in Fig. 11). Images are taken while changing the direction coordinates (R coordinates) without changing. This can be used to detect defects. That is, in the captured image, the defective area is imaged darker than the surroundings in a bright stripe portion and brighter than the surroundings in a dark stripe portion. Therefore, using this phenomenon, defects can be avoided as halftone images of the bright and dark portions of the stripe.

[0006] Further, Patent Literature 2 below describes a technique for detecting a defect called "Yuzuhada", which is a periodic unevenness on the surface. Here, we are trying to find spots (mottle) in the paint thickness due to fluctuations in the captured image on the boundary between the light and dark areas of the light and dark stripes that are the irradiation light. In this inspection method, the paint surface where the disturbance that causes the displacement of the boundary image of the stripe occurs over a relatively wide range of the paint surface is detected.

However, in these conventional surface defect inspection methods, the illuminating part illuminates the painted surface with a stripe-like light-dark pattern, so that the irradiation light wraps around in a direction orthogonal (crossing) to the stripe-like light-dark pattern. No force is generated. As a result, if a defect exists in the same direction as the stripe extending direction, it is difficult to catch the defect.

[0007] Furthermore, these conventional surface defect inspection techniques have the disadvantage that only convex defects can be substantially extracted. In addition, since it is difficult to obtain the difference in brightness at the reflected portion, erroneous detection is likely to occur in the binary value processing. It is difficult to catch design lines and defects near them. As shown in FIGS. 10 and 11, the optical power of the irradiation light used for the inspection and the optical axis of the imaging camera intersect with each other, so that the amount of light taken into the imaging camera is not sufficient. Also, in such an inspection system, the processing on the defect evaluation side must be complicated due to the complexity of the optical system. At the same time, it is necessary to make the positional relationship between the irradiation system and the imaging system strict.

Patent Document 1: JP-A-8-145906 (FIGS. 5, 9 and 15)

Patent Document 2: JP-A-9-126744 (FIG. 13)

Disclosure of the invention

Problems to be solved by the invention

Therefore, an object of the present invention is to provide a plurality of light emitting elements arranged in a predetermined layout pattern.

(Irradiation system) and a surface defect inspection apparatus having an imaging power camera (imaging system) for imaging the surface to be inspected illuminated by the irradiation light of the light emitting element, the configuration of the irradiation system and the imaging system is simple and The objective is to obtain a surface defect inspection device that can perform reasonable and highly reliable inspections.

Means for solving the problem

[0011] In order to achieve the above object, a first characteristic configuration of the present invention is:

A plurality of light emitting elements arranged in a predetermined layout pattern, an imaging camera for imaging a surface to be inspected illuminated by irradiation light of the light emitting elements, and an output unit for outputting imaging information of the imaging camera, What is claimed is: 1. A surface defect inspection apparatus comprising: a defect evaluation unit that evaluates an output signal from an output unit and detects a defect on the inspection surface,

The layout pattern is such that the light emitting elements are continuously arranged so that a surface of a predetermined shape is left inside.

On at least one of the dark surfaces, the imaging camera is arranged to receive the irradiation light of each of the light-emitting elements reflected from the surface to be inspected,

A copying apparatus is provided which moves the plurality of light emitting elements and the at least one imaging camera integrally along the surface to be inspected.

[0012] Also in this defect inspection apparatus, as a principle of inspection, a force utilizing wraparound of irradiation light is used. Here, a ray in which light emitting elements are continuously arranged so as to leave a surface of a predetermined shape inside. Use out patterns.

In this case, for example, when the painted surface is flat, the layout pattern of the light emitting elements is hexagonal, and the optical axis of the irradiation light and the optical axis of the imaging camera are oriented in the normal direction of the painted surface, the painted surface If there is no defect in the image, only the hexagonal light / dark pattern is imaged. However, if there is a defect, an intermediate luminance area based on this defect is formed, and as shown in FIG. 7, it appears as, for example, an isolated point floating on a dark surface inside a hexagon. Therefore, the image resulting from this defect can be reliably captured by the imaging camera.

[0013] Moreover, by arranging the imaging camera on a dark surface, it is possible to make the optical axis direction of the irradiation light coincide with the optical axis direction of the imaging side, and so-called imaging inspection in an epi-illumination state becomes possible. .

By providing a defect evaluation unit that evaluates the output signal of the output unit and detects a defect on the surface to be inspected, it automatically evaluates the defect location using technology established as image processing technology. Can be determined.

Also, by providing the above-mentioned copying apparatus, the imaging unit including these optical devices (a plurality of light emitting elements and an imaging camera) can be copied so that the positional relationship with respect to the surface to be inspected is constant. As a result, a highly reliable defect inspection that operates automatically and can be performed. Note that the positional relationship is a relationship between the optical axis of the light emitting element and the optical axis of the imaging camera, and further, the distance from the irradiation surface to the inspection surface and the distance from the imaging surface force to the inspection surface.

[0014] A second characteristic configuration of the present invention is that the light-emitting surfaces of the plurality of light-emitting elements and the imaging surface of the at least one imaging camera are provided in the same plane, and the light-emitting surface in the same plane is provided. A surface and the imaging surface are maintained parallel to the surface to be inspected by the copying apparatus.

[0015] That is, in this type of inspection, the brightness of a captured image, the position of the image portion, and the like largely depend on the positional relationship between the light-emitting surface and the imaging surface. . In this regard, by arranging the light emitting surface and the imaging surface on the same plane, an imaging unit in which these are integrated can be easily constructed. As a result, it is possible to specify the configuration of the optical system in the inspection only by adjusting the distance to the surface to be inspected with the same plane force, and the reliability of the inspection is improved.

[0016] A third characteristic configuration of the present invention is that the layout pattern is repeated in a predetermined direction. It is a repeated layout pattern to be performed.

[0017] With this configuration, for example, image processing for imaging can be repeatedly performed on the same basis using the layout pattern portion of the light emitting element and the dark surface provided therein as one unit. . In addition, when the surface to be inspected moves during the inspection, the same inspected surface portion can be repeatedly inspected, so that a plurality of pieces of imaging information is obtained from the inspected surface portion to perform the inspection with high reliability. be able to.

[0018] A fourth characteristic configuration of the present invention includes a transport mechanism that transports the inspection surface relative to the plurality of light-emitting elements and the imaging camera, and the repeating direction of the layout pattern is the relative direction. It is in the direction of conveyance.

That is, in this type of surface defect inspection, the inspection may be performed with the surface to be inspected automatically moving. However, in the surface defect inspection apparatus according to the fourth characteristic configuration of the present invention, a specific inspection surface is sequentially and repeatedly imaged by repeating a predetermined layout pattern to obtain imaging information. Can be performed.

BEST MODE FOR CARRYING OUT THE INVENTION

[0020] The present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 shows an overall configuration of an inspection system 200 employing a surface defect inspection apparatus 100 of the present invention. This inspection system 200 is intended, for example, for surface defect inspection of a bumper 1 of an automobile.

In this inspection system 200, the surface defect inspection apparatus 100 is disposed on the lower side of the stock station 202 and on the upper side of the visual inspection station 203. The surface defect inspection apparatus 100 includes an imaging unit 300 having a configuration unique to the present application.

[0022] The imaging unit 300 performs a copying operation following the outer shape of the bumper 1, thereby making it possible to perform inspection with much higher accuracy, higher accuracy, and higher reliability than before.

Hereinafter, the configuration of the inspection system 200, the configuration of the copying apparatus of the imaging unit 300 in the surface defect inspection apparatus 100, and the processing of the captured image will be described in detail.

[Configuration of Inspection System]

In FIG. 1, a bumper 1 to be inspected is transferred by a transfer robot 2 from the upper right side to the lower left side in the figure. A stock station 202, a surface defect inspection apparatus 100, and a visual inspection station 203 are provided along the transport direction. As shown Inspection is performed using a pair of bumpers 1 as one unit.

[0024] The movement of the bumper 1 from the stock station 202 to the transfer robot 2 is performed by the first inspector 204, and a visual inspection is performed by the second inspector 201. This is the same as in the case of the above-described conventional technology.

Describing along the work flow, the first inspector 204 takes out the pair of bumpers 1 from the stock station 202 as needed and attaches them to the bumper support 2a of the transfer robot 2 (an example of a transfer mechanism).

[0025] The transfer robot 2 moves the transfer path to the lower side while holding the bumper 1. During this movement, the posture of the bumper 1 does not change, but only translates along the transport path. When the bumper 1 enters the surface defect inspection apparatus 100, the imaging unit 300 moves with a change in attitude so as to follow the surface shape of the bumper 1. As will be described later, while the imaging unit 300 is moving, the illumination unit 3 of the imaging unit 300 is maintained parallel to the inspection surface, the optical axis of the imaging camera 4 is maintained in the normal direction of the inspection surface, and The distance from the imaging unit 300 is kept constant.

Then, the light and dark pattern of the irradiation light reflected on the bumper 1 is imaged by a plurality of imaging cameras 4 provided in the imaging unit 300. The imaging result is sent to the defect evaluation unit 6 on the analysis side, and the presence or absence of a defect is evaluated.

[0026] The second inspector 201 located on the lower side of the conveyance visually inspects the sent bumper 1. As shown in FIG. 1, at this time, the second inspector 201 grasps the evaluation information from the defect evaluation unit 6 as information of “a place to be noticed in the inspection” displayed on the inspection result projector 15. The visual inspection can be advanced with particular emphasis on that location.

[Coping Configuration of Imaging Unit in Surface Defect Inspection Apparatus]

(a) Imaging unit 300

FIG. 4 shows an imaging unit 300 of the surface defect inspection apparatus 100. FIG. 4A is a plan view of the imaging unit 300 when the imaging unit 300 is in a posture facing the surface to be inspected facing upward, FIG. 4B is a front view of the imaging unit 300, and FIG. is there. As shown in these figures, the imaging unit 300 is composed of a unit frame 300a having a basically rectangular parallelepiped shape, and a vertically extending direction from both ends in the longitudinal direction (the direction of the arrow L1 in FIG. 4A) of the unit frame 300a. Extending swing support frame And a memory section 300b.

[0028] The upper end surface of the unit frame 300a is configured as a lighting unit 3. In the lighting section 3, a large number of light emitting elements 30 are arranged in a repeating layout in which a hexagonal shape is repeated as one unit. A large number of light emitting elements 30 constitute one light emitting surface 3a as a whole (see FIG. 5).

Further, at the center in the width direction of the illumination unit 3, the lens surfaces 4a (that is, imaging surfaces) of the plurality of imaging cameras 4 are juxtaposed at equal intervals along the longitudinal direction of the unit frame 300a. In the illustrated example, ten imaging cameras 4 are provided. As shown in FIG. 4 (b), a DC power supply 300c for the imaging camera 4 and the light emitting element 30 is provided inside the unit frame 300a.

(B) Configuration of Copying Device

The imaging unit 300 is provided at the tip of the swing support frame 300b and is supported by a pair of left and right support shafts 300d. These support shafts 300d are configured to be rotatable around the axis and to be movable in the vertical direction and the front-rear direction with respect to the device frame 100a of the surface defect inspection device 100.

FIG. 2 is a diagram also showing a frontal force orthogonal to the transport path of the apparatus frame 100a. In FIG. 2, the transport robot 2 also moves to the left with a rightward force.

FIG. 3 is a side view of the apparatus frame 100a as viewed from the entry side force of the transfer robot 2. FIG.

[0032] As shown in Figs. 2 and 3, the device frame 100a is configured as a gate-like structure in a side view and a rectangular structure in a front view.

The apparatus frame 100a is provided with a traveling frame 100b movable in the left-right direction (a direction along the transport direction) when viewed from the front, and an elevating frame 100c movable up and down.

The lifting frame 100c is configured to be vertically movable along a rail rc provided on the traveling frame 100b. This vertical movement is performed by a lifting / lowering motor Mc (see FIG. 3) provided at the center of the traveling frame 100b.

[0033] The movement of the traveling frame 100b along the transport direction is performed by the rail rb, the traveling motor Mb, and the traveling motor Mb arranged above the apparatus frame 100a. This is executed by the drive transmission mechanism that transmits the driving force to the Ob. This drive transmission mechanism also has a pair of gears and an endless chain belt.

As shown in FIG. 3, a mechanism for adjusting the swing posture of the imaging unit 300 is provided near the tip of the swing support frame 300b by reducing the rotation of the rotating motor Md and the rotating motor Md. This is realized by a gear transmission mechanism G that transmits the pair of left and right support shafts 300d. As shown in FIGS. 1 and 2, a laser sensor 400 is provided on the side of the device frame 100a. The laser sensor 400 detects the position of the surface portion of the bumper 1 currently being inspected by the imaging unit 300 and the inclination of the surface (the inclination shown in FIG. 2). Information from the laser sensor 400 is sent to the host computer 14 having a function as a copying and controlling device.

The host computer 14 generates a control command based on the shape information of the bumper 1 and the transfer position information of the transfer robot 2. Then, the control information is corrected based on the detection information from the laser sensor 400, and the control information is sent to the respective motors of the lifting motor Mc, the traveling motor Mb, and the rotating motor Md. Thereby, the image pickup unit 300 is automatically controlled so as to take an appropriate positional relationship with respect to the surface to be inspected.

As shown in FIG. 2, the appropriate positional relationship is such that the optical axis of the imaging camera 4 is the normal direction of the inspection surface, the light emitting surface 3a is parallel to the inspection surface, and the light emitting surface is Both the 3a and the imaging surface (that is, the lens surface 4a) have a surface force to be inspected at a predetermined distance. In FIG. 2, the position and orientation of the imaging unit 300 with respect to two different inspected surfaces are schematically indicated by one solid line and the other by a dashed line.

[Processing of Captured Image]

As shown in FIGS. 4 and 5, the main system of the imaging inspection in the surface defect inspection apparatus 100 is an illumination unit 3 that illuminates the painted surface of the bumper 1, which is the inspection surface, and the inspection unit illuminated by the illumination unit 3 It comprises an imaging camera 4 for imaging a surface and an image processing controller 5. The image processing controller 5 uses the output signal from the imaging camera 4 to evaluate the presence of a defect on the surface to be inspected and to output the evaluation defect. In the surface defect inspection apparatus 100, the imaging camera 4 is focused on the light emitting surface 3a projected on the inspection surface instead of the inspection surface, in other words, the imaging camera 4 is projected on the inspection surface. Light emitting element 3 described later By capturing 0 images, more accurate inspections can be realized!

[0038] The image processing controller 5 is positioned as a lower computer with respect to the host computer 14. The image processing controller 5 includes a monitor 12 and a printer 13 as output devices connected to an output unit 10 of the image processing controller 5 itself. Further, the image processing controller 5 has an image input unit 7 and a defect evaluation unit 6 in addition to the illumination / imaging control unit 9 for controlling the illumination unit 3. The image input unit 7 takes in an output signal from the imaging camera 4 and develops it in the memory 8 as digital image data (hereinafter simply referred to as an input image). The defect evaluation unit 6 performs a defect evaluation using the input image.

Further, the image processing controller 5 can transmit data to the host computer 14 via the communication unit 11.

The host computer 14 stores information on the bumper 1 to be inspected (which is downloaded to the image processing controller 5 as necessary) or operation information on the transfer robot 2 as a transfer device. Further, the defect information of the painted surface generated by the image processing controller 5 is also uploaded from the image processing controller 5 to the host computer 14 and stored therein.

The visual inspection station includes an inspection result projector 15 and a printer, which are controlled by a terminal connected to the host computer 14 via a network. Thereby, based on the defect information sent from the image processing controller 5 via the host computer 14, the defect position and the like can be instructed to the inspector via the inspection result projector 15.

As described above, the imaging unit 300 is controlled to follow so that the three conditions are simultaneously satisfied. That is, the light emitting surface 3a of the illumination unit 3 and the lens surface (corresponding to the image capturing surface) 4a of the imaging camera 4 face the surface to be inspected of the bumper 1 transported by the transport robot 2, and the light emitting surface 3a and the image capturing surface That is, the normal line of 4a and the normal line of the surface to be inspected match, and the separation distance from the light emitting surface 3a and the imaging surface 4a to the surface to be inspected is constant.

As shown in FIG. 4, the illumination unit 3 includes a large number of light emitting elements 30 (hereinafter, referred to as LED elements in this embodiment, which are LED elements). The hexagonal layout pattern has a layout pattern of It has a configuration in which the LED elements 30 are arranged consecutively (while holding between adjacent LED elements 30) so as to be repeated a plurality of times. The hexagonal layout pattern is a force that evenly covers the entire surface of the rectangular light emitting surface 3a. In FIG. 4 (a), only some of them are shown, and the rest are omitted. The remaining space not occupied by the LED elements 30 is referred to herein as the surface 31 and is a black or other dark, non-luminous plate surface.

Many dark surfaces 31 appear due to the LED elements 30 arranged in a mesh. The lens surfaces 4a of the imaging camera 4 are located on the ten dark surfaces 31 which are equally spaced apart on the axis along the longitudinal direction of the unit frame 300a among these surfaces 31. . Thereby, a configuration in which the plurality of imaging cameras 4 are incorporated in the illumination unit 3 is realized.

The image processing controller 5 has a CPU as a core member, and a functional unit for performing various operations of the surface defect inspection apparatus 100 is constructed by hardware and / or software.

As shown in FIG. 6, the defect evaluation unit 6 includes a preprocessing unit 60A that converts the input image developed in the memory 8 into a form suitable for defect detection, and a preprocessing unit 60A that uses the preprocessed input image on the inspection target surface. And a defect determination unit 60B that finds the defect of the defect.

[0045] The pre-processing unit 60A includes a luminance adjustment unit 61 that performs luminance adjustment on the input image, and a binarization processing unit 62 that performs binarization processing on the input image whose luminance has been adjusted. The brightness adjustment unit 61 of this embodiment performs not only gamma adjustment but also brightness adjustment for each pixel area. In the brightness adjustment for each pixel area, the brightness level of the luminescent image included in the input image reaches the brightness level of the luminescent image of the LED element obtained from the normal inspection surface, which serves as a reference for each paint color and paint surface. Is adjusted as follows.

[0046] The binarization processing unit 62 includes a binarization threshold determination unit 62a and an image feature extraction unit 62b. The binarization threshold determination unit 62a determines the binarization threshold from the grayscale histogram of the input image by a statistical method. The image feature extraction unit 62b applies a smoothing filter to the input image to eliminate noise, and applies an edge enhancement filter such as a Sobel filter to enhance the contour of the luminescent image or the defective image. Binarization processor 62, 2 Nei匕閾values using the determined portion 62a Niyotsu binarization threshold determined Te, the enhanced input image by the image feature extraction unit 62b into a ^binary image. An example of an input image binarized by the binarization processing unit 62 is conceptually shown in FIG. In the binary dark / dark image, the high-luminance area is displayed in white. Therefore, the emission image of the LED element group continuously arranged in the hexagonal layout pattern is displayed as a continuously connected white contour line of the hexagonal spread. On the other hand, the painted surface area facing the dark surface 31 is displayed as a dark area. If a paint defect exists in the paint surface area, it is displayed as an area (isolated point) that floats independently in white in the dark area as shown in Fig. 7 due to irregular reflection by the irradiation light of the peripheral force of the paint defect. .

[0048] From this, the defect detection is performed in a region where the luminance is prominent (a white region in this embodiment) in the binary image, and is not continuous in a predetermined pattern. It is only necessary to find an isolated point. A well-known image processing algorithm for searching for a continuous pixel while having a predetermined level of luminance value (density value) or for searching for an isolated area can be used.

As shown in the enlarged view of FIG. 8, the emission image of the LED element 30, which should originally appear as a continuous line, is interrupted, and the interrupted portion is erroneously detected as a coating defect. Could be done. The discontinuity of the emission image is caused by a change in the reflection characteristic with respect to the irradiation light based on the shape of the inspection surface (here, the painted surface). In order to appropriately avoid such erroneous detection, the defect determination unit 60B is substantially constituted by the following program.

[0050] The defect determination unit 60B includes a defect candidate extraction unit 63, a defect candidate selection unit 64, an image mask generation unit 65, a label setting unit 66, an area calculation unit 67, and a defect determination unit 68. ing. The defect candidate extraction unit 63 detects a non-consecutive independent pixel region having a predetermined number of pixels or less as an isolated point, and sets it as a defect candidate. The defect candidate selection unit 64 excludes, from the defect candidates, the defect candidates included in the region indicating the light emission image of the LED elements 30 arranged continuously. The image mask generation unit 65 integrates an unneeded image region such as an isolated point region and a background excluded from the defect candidates by the defect candidate selection unit 64 and performs a mask process as a non-defect determination target region. The label setting unit 66 performs a labeling process of assigning different labels (numbers) to different defect candidate areas in order to identify a plurality of defect candidate areas located outside the image mask. The area calculator 67 calculates the area of each labeled defect candidate area. defect The determination unit 68 determines the defect candidate as a true defect based on the area information from the area calculation unit 67, and writes it to the defect map.

[0051] The defect candidate selection unit 64 includes a defect candidate time-series determination unit 64a and a light emission image discontinuous portion search unit 64b. The defect candidate time series determination unit 64a determines whether or not the image candidates sequentially sent from the imaging camera 4 have been extracted as defect candidates a predetermined number of times in order to select the defect candidates extracted by the defect candidate extraction unit 63. By checking, it is possible to prevent suddenly occurring bright areas from being recognized as defect candidates. As can be understood from FIG. 8, the luminescence image discontinuous portion searching unit 64b checks whether the extracted defect candidate (isolated point) is located on an extension of the continuous luminescence image. As a result, it is possible to prevent the discontinuous portion of the light emission image from being recognized as a defect candidate.

The search for the non-continuous portion of the luminescent image is performed by using a shape feature extraction algorithm or the like that extracts a dark region located in an extended line region of the discontinuous portion while searching for consecutive luminescent image pixels. It is possible. The isolated points existing in the discontinuous region are excluded from the defect candidates.

The procedure of the defect evaluation of the painted surface by the defect evaluation unit 6 configured as described above will be described below with reference to the flowchart of FIG.

First, the frame images sequentially sent from the imaging camera 4 via the image input unit 7 are stored in a memory.

Take it into 8 (# 01). The brightness (density value) of the captured input image is adjusted by the brightness adjustment unit 61 (# 02). At this time, the feature amount of the input image is required. For the feature amount, it is preferable to divide the input image by a predetermined number of sections, and to use the maximum value of the average density value calculated for each section as the feature amount. Better ,.

This feature amount can also be used for determining the following binary threshold value and adjusting the lens aperture of the imaging camera 4. After the binary threshold value is determined by the binary threshold value determination unit 62a (# 03), the image feature extraction unit 62b performs smoothing and edge enhancement of the image (# 04). Is binarized to form a binarized image (# 05).

From the binarized input image, an isolated bright pixel area having a predetermined number of pixels (predetermined from image resolution or the like) is extracted as a defect candidate by the defect candidate extraction unit 63. (# 06). Among the extracted defect candidates, the defect candidate belonging to an isolated point that is instantaneously and locally generated due to disturbance light or the like is excluded from the defect candidate power by the defect candidate time-series determination unit 64a (# 07). Further, among the extracted defect candidates, a defect candidate belonging to an isolated point located in a discontinuous region of the luminescence image is excluded from the defect candidate power by the luminescence image discontinuous portion searching unit 64b (# 08).

[0056] The peripheral region including the discontinuous region of the luminescence image found by the luminescence image discontinuous portion search unit 64b is masked by the image mask generation unit 65 as an unnecessary pixel region (# 09). At this time, the mask processing is performed on the background area other than the painted surface as the surface to be inspected at the same time. The background area is determined based on the shape information of the bumper 1 as the inspection object to which the force of the host computer 14 is also transmitted and the transfer position information of the transfer robot 2.

In this embodiment, since the transfer position information obtained from the host computer 14 may be different from the actual position, the displacement of the bumper 1 in real time is checked using a laser sensor or the like. Thus, the position of the image mask is corrected (# 10). After the selection of the defect candidates and the removal of the background image in this manner, the remaining defect candidates (isolated points) are labeled (# 11), and the area of the isolated points to which each label is assigned is calculated. (# 12), the preset area !, satisfying the area condition (whether the force has an area equal to or larger than the threshold), and determining only the isolated point as a true defect (# 13), its coordinate position and size Is written in the defect map (# 14).

[Post-processing]

Thus, the procedure of the defect evaluation of the painted surface by the defect evaluation unit 6 is completed. After the inspection of the painted surface is completed in this procedure, the visual inspection station 203 performs a defect collation. The defect matching is performed by assigning an ID that matches the ID of the bumper carried into the visual inspection station 203 among the defect maps sent from the image processing controller 5 via the host computer 14. This is performed using

At that time, in order to facilitate the collation work by the inspector, it is convenient to operate the inspection result projector 15 so as to point out a defective portion based on the corresponding defect map. Of course, the defect information based on such a defect map is output on paper by a printer 13 connected to the output unit 10 of the surface defect inspection apparatus 100, and the output paper is attached to the bumper 1. It may be.

In the above-described embodiment, the illumination unit 3 is configured by the LED element group continuously arranged in a hexagonal mesh. However, the mesh form may be other than hexagonal, and the light emitting element 30 may be other than the LED element.

[Another Embodiment]

In the above embodiment, any inspected surface having a force surface defect, which is an example of inspecting a painted surface of an automobile body (particularly, a bumper), can be inspected. An example of this type is surface inspection of press-formed products.

In the above-described embodiment, the optical axis of the imaging camera 4, which is the most preferable for performing the copying, is the normal direction of the surface to be inspected (the copying condition 1), and the light emitting surface is This figure shows a copying apparatus that satisfies the relationship that is parallel to the surface to be inspected (scanning condition 2), the light emitting surface and the imaging surface are both at a predetermined distance from the surface to be inspected (scanning condition 3). However, as the copying conditions, copying that satisfies at least one of the above-described copying conditions 1 to 3 may be performed, and the other conditions may be processed by the image processing side.

In the embodiment described above, the input image is converted into a binary image for defect detection. However, it is also possible to perform defect detection by using a ternary image, which is not limited to the binary image of the input image, and by using a multi-value image.

In the above embodiment, an example has been shown in which the inspection system 200 is arranged in the order of the stock station 202, the surface defect inspection apparatus 100 according to the present invention, and the visual inspection station 203. However, if this system is to be manufactured and inspected with predetermined surface processing (painting, press molding, etc.), a stock station, a processing unit that performs painting, etc., a surface defect inspection device, and a visual inspection station are arranged in this order. Therefore, each process unit is to be arranged.

In the above embodiment, the light emitting surface of the light emitting element and the imaging surface of the imaging camera are located on the same plane, but the two surfaces are located at different positions due to the separation distance of the surface force to be inspected. It is a little in

Industrial applicability

[0065] As described above, the surface defect inspection apparatus that is active in the present invention is particularly suitable for use in automobile bodies such as bumpers. It is suitable for surface inspection of inspected surfaces with surface defects, including painted surfaces of die and press-formed products.

Brief Description of Drawings

FIG. 1 is an explanatory view showing a schematic configuration of an inspection system employing a surface defect inspection apparatus according to the present invention.

FIG. 2 is an explanatory view showing a schematic overall configuration of a surface defect inspection apparatus according to the present invention.

FIG. 3 is an explanatory view showing a schematic overall configuration of a surface defect inspection apparatus according to the present invention.

[4] Explanatory view showing an imaging unit of the surface defect inspection device according to the present invention

FIG. 5 is an explanatory diagram showing a control and information processing system of an imaging unit of the surface defect inspection apparatus according to the present invention.

FIG. 6 is a functional block diagram showing a configuration of a defect evaluation unit mounted on the surface defect inspection apparatus. FIG. 7 is an explanatory diagram for explaining a binarized input image

FIG. 8 is an explanatory view for explaining an isolated point present at a break in a light emission image

FIG. 9 is a flowchart showing a procedure of defect evaluation of a surface to be inspected by a defect evaluation unit.

FIG. 10 is an explanatory diagram showing the configuration of a conventional bumper inspection system

[FIG. 11] An explanatory view of an inspection principle showing a stripe-shaped irradiation light.

Explanation of symbols

[0067] 3 Lighting unit

4 Imaging camera

5 Image processing controller

6 Defect evaluation department

30 Light emitting element (LED element)

31 Dark side

60A Pre-processing section

60B Defect determination unit

61 Brightness adjuster

62 Binarization processing section

63 Defect candidate (isolated point) extraction unit Defect candidate selection unit Image mask generation unit Label setting unit Area calculation unit Defect judgment unit

Claims

The scope of the claims

[1] A plurality of light emitting elements arranged in a predetermined layout pattern, an imaging camera for imaging a surface to be inspected illuminated by irradiation light of the light emitting elements, and an output unit for outputting imaging information of the imaging camera. A surface defect inspection apparatus comprising: a defect evaluation unit that evaluates an output signal of the output unit force and detects a defect on the inspection surface.

A surface defect inspection apparatus provided with a copying apparatus for integrally moving the plurality of light emitting elements and the at least one imaging camera along the surface to be inspected.

[2] A light-emitting surface of the plurality of light-emitting elements and an image-capturing surface of the at least one image-capturing camera are provided in the same plane, and the light-emitting surface and the image-capturing surface in the same plane are copied. The surface defect inspection device according to claim 1, wherein the surface defect inspection device is maintained parallel to the inspection target surface by an apparatus.

3. The surface defect inspection apparatus according to claim 1, wherein the layout pattern force is a repetitive layout pattern that is repeated in a predetermined direction.

4. The method according to claim 1, further comprising a transport mechanism configured to relatively transport and move the surface to be inspected with respect to the plurality of light emitting elements and the at least one imaging camera, wherein a repeating direction of the layout pattern is the direction of the relative transport. The surface defect inspection apparatus according to the above.