JP2019060903A - Inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of signal lines used in a lighting device for a photometric stereo. A lighting device 3 has a plurality of LEDs arranged in a substantially annular shape and a lighting control unit for lighting the plurality of LEDs. In particular, the lighting device 3 has a storage unit that stores a lighting pattern. The lighting device 3 lights any one of the plurality of LEDs according to a lighting pattern specified by a control signal received from the image processing device 5 via the signal line 8. [Selection diagram] Fig. 1

Description

  The present invention relates to an inspection apparatus.

  In order to measure an accurate three-dimensional shape of a work (product to be inspected) using the principle of photometric stereo, it is necessary to use an illumination light source such that the illumination light is incident on each surface of the work with a uniform amount of light. Become. Also, the incident angle of the illumination light needs to be known. Furthermore, since the incident angle of light must not change according to the part of the work, an illumination light source of a size corresponding to the size of the work to be inspected is required. In addition, scale information (actual size per pixel) of the image projected on the camera is also required. Appearance inspection devices are often installed by the user, and it is difficult to request these strict installation conditions from the user. Then, according to patent document 1, the installation burden of the user is reduced by proposing the exclusive device which integrated illumination and a camera.

JP 2007-206797 A

  Although patent document 1 irradiates parallel light to work piece 2 respectively by four spot illumination light sources, since it is spot illumination, it is easy to produce a shadow. As a result, depending on the type and placement of the workpiece, many areas of the surface of the workpiece can not be measured. Depending on the type and placement of the work, if the lighting device can be moved away from the work to use specular light, or if the lighting device can be brought close to the work to use diffuse reflected light, such problems may be alleviated. . By the way, in the photometric stereo method, since it is necessary to illuminate the work from a large number of illumination directions, a large number of signal lines for individually controlling a large number of light sources are required. However, when the number of signal lines increases, not only the cost increases, but also the cable containing a large number of signal lines becomes thick, which hinders the cable management.

  Therefore, the present invention aims to reduce the number of signal lines used in a lighting device for photometric stereo.

According to the invention, for example
Imaging means for imaging an inspection object;
A plurality of light sources arranged in a substantially annular shape, a storage unit storing the lighting patterns of the plurality of light sources, and a lighting pattern stored in the storage unit, specified by a control signal received via a signal line A lighting control unit for lighting the plurality of light sources according to a lighting pattern, and illumination means for adjusting a distance to the inspection object by moving independently of the imaging means;
An inspection image generation unit that combines a plurality of luminance images acquired by the imaging unit according to a photometric stereo method, and generates an inspection image having a plurality of pixel values according to the inclination or reflectance of the surface of the inspection object When,
There is provided an inspection apparatus comprising: determination means for determining the quality of the inspection object using the inspection image.

  According to the present invention, a signal line capable of transmitting a control signal for specifying the lighting pattern stored in the storage unit is disposed, and the lighting pattern is specified according to the control signal to light a plurality of light sources. The number of signal lines can be significantly reduced as compared to the case where signal lines are arranged for each.

Diagram showing the outline of the inspection device Diagram for explaining the principle of photometric stereo Diagram for explaining the stacked operation Diagram showing how to determine weights based on feature size A diagram showing an example of inspection images having different feature sizes Diagram to explain the images involved in the generation of surface shape images Diagram explaining how to generate texture image Functional block diagram of inspection device Flow chart showing setting mode Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Flow chart showing inspection mode Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram showing an example of a user interface Diagram for explaining the structure of the lighting device Diagram for explaining the structure of the lighting device Block diagram for lighting control Diagram showing the timing sequence for lighting control Diagram showing an example of lighting pattern Diagram showing an example of a user interface Diagram showing an example of a user interface

  One embodiment of the present invention is shown below. The particular embodiments described below will help to understand various concepts such as the superordinate, intermediate and subordinate concepts of the present invention. Further, the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments.

  FIG. 1 is a diagram showing an example of an appearance inspection system. The line 1 is a conveyor belt or the like for conveying the workpiece 2 which is an inspection object. The illumination device 3 is an example of an illumination unit that illuminates the inspection object according to the photometric stereo method. The camera 4 is an example of an imaging unit that receives the reflected light from the illuminated inspection object in accordance with the photometric stereo method and generates a luminance image. The image processing device 5 calculates a normal vector of the surface of the work 2 from the plurality of luminance images acquired by the camera 4 and is an inclination image constituted by pixel values based on the normal vectors calculated from the plurality of luminance images For the reduced image of the inclined image, the pixel value of the pixel of interest is accumulated and calculated using the normal vector of the adjacent pixel adjacent to the pixel of interest to generate an inspection image having the pixel value, and using the inspection image This is an appearance inspection apparatus that determines the quality of an inspection object. The tilt image may be referred to as a normal vector image. The image processing device 5 may create a reflectance image (albedo image) from the luminance image. The display unit 7 displays a user interface for setting control parameters related to an examination, an inclination image, a reflectance image, an examination image, and the like. The input unit 6 is a console, a pointing device, a keyboard or the like, and is used to set control parameters. The image processing device 5 and the lighting device 3 are connected by a signal line 8. The image processing device 5 and the camera 4 are connected by a signal line 9.

  In particular, according to FIG. 1, the camera 4 and the lighting device 3 are supported by different frames so as to be able to move independently. As described above, since the lighting device 3 is movable independently of the camera 4, the distance from the work 2 to the lighting device 3 can be freely adjusted. That is, by disposing the illumination device 3 away from the work 2 depending on the type and placement of the work 2, the camera 4 can strongly receive the specular reflection light. Further, by disposing the illumination device 3 close to the work 2, the camera 4 can strongly receive the diffuse reflection light. Note that the camera 4 and the illumination device 3 may be instructed by the same frame. In this case, the lighting device 3 may be fixed to the frame by a clamp mechanism or the like for adjusting the mounting position of the lighting device 3.

<Principle of Photometrics Stereo>
In a general photometric stereo method, as shown in FIG. 2, illumination light L1 to L4 is irradiated to the work 2 from four directions while being switched to generate four luminance images. The direction of the illumination light used when capturing each luminance image is only one direction. The luminance image is composed of a plurality of pixels, and in the four luminance images, four pixels having the same coordinates correspond to the same work surface. Equation 1 shown in FIG. 2 holds between the pixel values (brightness values) I1, I2, I3, I4 of four pixels and the normal vector n. Here, ρ is the reflectance. L is the amount of illumination light from each direction, which is known. Here, the amount of light is the same in all four directions. S is the illumination direction matrix and is known. By solving this equation, the reflectance ρ and the normal vector n for each coordinate (work surface) can be obtained. As a result, a reflectance image and a tilt image are obtained.

  In the present embodiment, the height component is further extracted from the tilt image, and a shape image indicating the shape of the workpiece is created as an inspection image. The inspection image is obtained by the accumulation calculation equation which is the equation 2 shown in FIG. Here, z n is the n-th accumulation result and indicates the shape of the work surface. x and y indicate the coordinates of the pixel. n indicates how many times the calculation is repeated. p indicates a horizontal inclination component, and q indicates a vertical inclination component. p and q are obtained from the normal vector n. w is a weight. Further, in the first accumulation operation, an inclination image of 1/1 is used, the reduced inclination image of 1/2 is used for the second accumulation, and a reduced inclination image of 1/4 is used for the third accumulation. When creating a reduced image, reduction processing may be performed after performing Gaussian processing.

  In the present embodiment, a parameter called feature size is adopted in the stacking operation. The feature size is a parameter that gives weight to the components of the reduced image used in the stacking operation. The feature size is a parameter indicating the size of the surface shape of the workpiece 2. For example, if the feature size is 1, the weights for the four pixels adjacent to the target pixel in the xy direction are maximized and the accumulation operation is performed. If the feature size is 2, the weights for the eight pixels adjacent to the target pixel in the xy direction are set the largest, and the stacking operation is performed. However, since calculation using eight pixels causes an increase in the amount of calculation, the above-described reduced image is created and used for the calculation. That is, instead of using eight adjacent pixels, the inclination image is reduced to 1⁄2 and the operation is performed. This makes it possible to take account of four pixels in the reduced image for a certain target pixel in the calculation. The same reduction effect of calculation load is achieved by creating a reduced image according to the feature size even when the feature size increases to 4, 8, 16, 32, and setting the weight to the maximum for the reduced image corresponding to the feature size. Is obtained.

  FIG. 3 shows an example of the stacking operation. In this example, two inclination images (an image of the inclination component p in the horizontal direction and an image of the inclination component q in the vertical direction) obtained from the normal vector n are input. First, the entire shape is stacked up with the tilt image with a large degree of reduction, and the detail shape is stacked with an image with a smaller degree of reduction than that. This makes it possible to restore the entire shape in a short time. According to FIG. 3, for example, z which is a parameter indicating the shape of the workpiece surface for the pixel of interest is calculated by Equation 2 for the 1/32 reduced image. The weight w is determined according to the feature size. Each pixel constituting the reduced image is set as a target pixel and the calculation is repeated (iterated). The initial value of z is zero. Next, z is calculated for the 1/16 reduced image according to Equation 2. Here, the inclination component of the 1/16 reduced image is accumulated with respect to the calculation result of 1/32. In the same manner, the calculation is performed by stacking 1/8 reduced images to 1/1 images.

  FIG. 4 shows an example of weights for each feature size. The horizontal axis indicates the resolution level (reduction degree), and the vertical axis indicates the weight. As can be seen from FIG. 4, at feature size 1, the weight of level 0 (1/1 image) having the smallest degree of reduction is maximum. This makes it possible to build up fine shapes. In feature size 2, the weight of level 1 (1/2 image) is maximum. This makes it possible to stack larger sized shapes. Thus, each weight is determined such that a peak occurs at a level corresponding to the feature size.

  As a method of restoring the shape image, a known Fourier transform integral method can also be adopted in addition to the above-described accumulation operation (A Method for Enforcing Integrity in Shape from Shading Algorithms, IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 10, No. 4 July 1988). Also in this method, it is possible to generate a reduced image in the calculation process and adjust the weighting component to change the extracted feature size.

  FIG. 5 shows an example of an inspection image according to the difference in feature size. It can be seen that the feature size 4 extracts the shape of the detail, the feature size 64 extracts the entire shape, and the feature size 16 extracts the shape of these intermediate sizes. Such a small feature size is useful for inspecting fine flaws, a large feature size is suitable for determining the presence or absence of an object, and an intermediate feature size is suitable for OCR or the like of concavo-convex characters. That is, it is possible to improve the inspection accuracy by selecting an appropriate feature size according to the inspection tool.

  FIG. 6 is a diagram showing a process of creating an inspection image by the photometric stereo method. The luminance images 601 to 604 are luminance images obtained by illuminating the work 2 with illumination lights different in illumination direction. The luminance image 600 is a luminance image obtained by illuminating simultaneously from four directions. The normal vector of the work surface is determined from the plurality of luminance images acquired by illuminating the work 2 with illumination light different in illumination direction. The tilt image 611 is a tilt image in which the tilt component in the X direction of the normal vector obtained from the brightness images 601 to 604 is a pixel value. The inclination image 612 is an inclination image in which an inclination component in the Y direction of the normal vector obtained from the luminance images 601 to 604 is a pixel value. The reflectance image 610 is a reflectance image in which the variation of the brightness value due to the inclination of the work surface is removed from the normal vectors determined from the brightness images 601 to 604, and the reflectance of the work surface is an image. The inspection images 621 to 623 are images having different feature sizes obtained from the tilt images 611 and 612, respectively. Since the inspection images 621 to 623 are also composed of pixels based on the inclination component, they are a kind of inclination image. An inspection image of the workpiece 2 is generated in such a procedure. A luminance image 600 or a reflectance image 610 which is an omnidirectional illumination image may be adopted as an inspection image depending on the inspection tool. The omnidirectional illumination image is a luminance image acquired by turning on all the plurality of light sources provided in the illumination device 3.

<Texture information>
The texture information is information based on the reflectance ρ of the surface of the work 2. The reflectance ρ is determined by Equation 1, that is, one reflectance image is obtained from four luminance images. The reflectance image is an image having pixel values proportional to the reflectance ρ of the work surface. As shown in FIG. 7, normal vectors are calculated from the four luminance images 701 to 704, and the reflectance of each pixel is calculated based on the calculated normal vectors and the luminance values of the corresponding pixels of the plurality of luminance images. The texture images 711 and 712 which are reflectance images are obtained by calculating pixel values in proportion to. As the generation method, there are a method of obtaining a texture image by pixel averaging of four luminance images, and a method of obtaining a texture image by pixel averaging after removing halation from the four luminance images. The texture image 711 is obtained by image averaging, and the texture image 712 is an example obtained by halation removal. There are four pixels whose coordinates match in the four luminance images. Remove the halation by excluding the pixel having the largest pixel value among the four pixels, or excluding the first to N-th pixels (N is a natural number of 3 or less) in descending order of the pixel values. Is possible. This is because halation appears in the image as high luminance. The texture images 711 and 712 are both types of reflectance images because they are composed of pixels based on reflectance.
<Function block>
FIG. 8 is a block diagram of the inspection apparatus. In this example, the lighting device 3, the camera 4 and the image processing device 5 are respectively housed in separate housings, but this is merely an example, and may be integrated as appropriate. The illumination device 3 is an example of an illumination unit that illuminates an inspection object according to the photometric stereo method, and includes a light source group 801 and an illumination controller 802 that controls the light source group. A plurality of light emitting elements may constitute one segment, and a plurality of segments may further constitute a light source group 801. The number of segments is generally four, but may be three or more. This is because if the work 2 can be illuminated from illumination directions in three or more directions, an inspection image can be generated by the photometric stereo method. As shown in FIG. 1, the outer shape of the lighting device 3 may be ring-shaped. Moreover, the illuminating device 3 may be comprised by the several illumination unit isolate | separated each. For example, although there are lighting units in the market that are used to capture work 2, these have not been developed for photometric stereo. However, the lighting device 3 may be configured by preparing a plurality of such lighting units and connecting a lighting controller that controls them. The lighting controller 802 controls the lighting timing and lighting pattern (lighting pattern) of the light source group 801 according to the control command from the image processing device 5. Although the lighting controller 802 is described as being built in the lighting device 3, it may be built in the camera 4 or may be built in the image processing device 5, or in a housing independent of them. It may be accommodated.

  The camera 4 is an example of an imaging unit that receives the reflected light from the inspection object illuminated according to the photometric stereo method to generate a luminance image, and executes an imaging process according to a control command from the image processing device 5 Do. The camera 4 may create a luminance image of the work 2 and transfer it to the image processing device 5, or transfer the luminance signal obtained from the imaging device to the image processing device 5, and the image processing device 5 generates a luminance image May be Since the luminance signal is a signal that is the source of the luminance image, in a broad sense the luminance signal is also a luminance image.

  The image processing apparatus 5 is a type of computer, and communicates with a processor 810 such as a CPU or ASIC, a storage device 820 such as a RAM, ROM, or portable storage medium, an image processing unit 830 such as an ASIC, or a network interface. And a part 850. A processor 810 is in charge of setting an inspection tool, adjusting control parameters, and generating / regenerating / updating an inspection image. The photometric processing unit 811 calculates a normal vector n of the surface of the work 2 from the plurality of luminance images acquired by the camera 4 and an inclination having a pixel value based on the normal vector n calculated from the plurality of luminance images Arithmetic means for generating an inspection image having the pixel value by calculating the pixel value of the target pixel by using normal vectors n of adjacent pixels adjacent to the target pixel for the image and the reduced image of the inclination image It functions as inspection image generation means). Specifically, the inspection image is generated using the above-described equation or the like. The illumination control unit 812 transmits a control command to the illumination controller 802 to control a lighting pattern, illumination switching timing, and the like. The imaging control unit 813 controls the camera 4. The UI management unit 814 displays a user interface (UI) for setting an inspection tool, a UI for setting parameters necessary for generating an inspection image, and the like on the display unit 7, and inputs from the input unit 6. Set the inspection information and thus the inspection tools and parameters. In particular, the feature size setting unit 815 functions as a setting unit that sets a feature size, which is a parameter that gives a weight w to the component of the reduced image used in the stacking operation. The image selection unit 816 selects an image to be displayed among a plurality of luminance images, a plurality of inspection images, a plurality of tilt images, and a plurality of reflectance images. The image selection unit 816 may select an image to be stored or output among the plurality of luminance images and inspection images acquired by the camera 4. The inspection tool setting unit 817 sets an inspection tool for the inspection image selected by the image selection unit 816. The inspection tool setting unit 817 sets, for example, a flaw inspection area or a character recognition area on the reference image. The reference image setting unit 818 sets a reference image which is an inspection image acquired from a non-defective item. The display control unit 851 switches the luminance image and the inspection image to display them on the display unit 7 or displays the luminance image and the inspection image simultaneously. Further, when the control parameter is adjusted, the display control unit 851 updates the image displayed on the display unit 7 to an image on which the control parameter is reflected. The inspection tool setting unit 817 may include a display control unit 851, a feature size setting unit 815, an image selection unit 816, a reference image setting unit 818, and a condition setting unit 819. The image processing unit 830 performs pattern search on the inspection image using the reference image, and functions as an inspection area setting unit that sets an inspection area (eg, a flaw inspection area, a character recognition area, etc.) in the inspection image. The inspection area is, for example, a character recognition area. The condition setting unit 819 sets conditions for outputting an image to an external device connected to the display unit 7 or the communication unit 850, and conditions for saving the image in a portable storage medium or the like. The determination unit 840 functions as a determination unit that determines the quality of the work 2 using the inspection image. For example, the determination unit 840 receives the result of the inspection performed using the inspection image in the image processing unit 830, and determines whether the inspection result satisfies the non-defective condition (such as tolerance).

  The storage device 820 stores luminance image data 821 which is data of a luminance image acquired by the camera 4, tilt image data 822 and reflectance image data 823 generated by the photometric processing unit 811. The storage device 820 also stores various setting data, program codes for generating a user interface, and the like. The storage device 820 may store and hold inspection images having different feature sizes. In addition to the inspection image, the storage device 820 may store tilt image data and reflectance image data that are the origin of the inspection image. These will be useful for identifying which of the inspection image, the inclination image or the reflectance image had a problem and correcting its control parameters when an erroneous judgment of the work 2 is found.

  The image processing unit 830 performs an appearance inspection using the inspection image (tilt image data 822 and reflectance image data 823) generated by the photometric processing unit 811. The flaw inspection unit 831 executes flaw inspection in flaw inspection areas of a plurality of inspection images generated using different feature sizes. The OCR unit 832 functions as a character recognition processing unit that executes character recognition processing on a plurality of inspection images generated using different feature sizes. The flaw inspection unit 831 and the OCR unit 832 read the inspection image (tilt image data 822 and reflectance image data 823) stored in the storage device 820, perform inspection in the character recognition area, and store the inspection result in the storage device 820. It may be written or passed to the determination unit 840. The determination unit 840 determines the quality of the work 2 based on the inspection result.

<Setting mode>
The inspection system has a setting mode for setting an inspection tool, and an inspection mode (operation mode) for executing an appearance inspection of the workpiece 2 in accordance with the set inspection tool. Here, an example of the setting mode will be described.

  FIG. 9 is a flowchart relating to the setting mode. When the start of the setting mode is instructed through the input unit 6, the UI management unit 814 of the processor 810 displays a UI for setting an inspection tool on the display unit 7.

  FIG. 10 shows an example of the UI. The UI 1000 displayed on the display unit 7 by the UI management unit 814 is provided with a pull-down menu 1001 for specifying the storage destination of the inspection result and a text box 1002 for inputting the name of the inspection tool. When detecting that the execution button is pressed, the UI management unit 814 displays the next UI.

  In the UI 1100 shown in FIG. 11, a guidance 1101 for setting an inspection tool, a measurement execution button 1102 for instructing the camera 4 to take an image, a display area 1103 for displaying an image taken by the camera 4 and camera settings A camera setting button 1104 for instructing start is provided. The image selection unit 1105 is a button for selecting an image to be displayed in the display area 1103 or an image to be used for an examination. In this example, the image selection unit 1105 alternatively selects any one image of shape 1, shape 2, texture and normal. When the measurement execution button 1102 is operated, the imaging control unit instructs the camera 4 to perform imaging. The UI management unit 814 renders the luminance image acquired by the camera 4 in the display area 1103. When another image is selected by the image selection unit 1105, the UI management unit 814 renders the image selected by the image selection unit 1105 in the display area 1103. In this manner, the user can switch the image displayed in the display area 1103 by operating the image selection unit 1105 or instructing switching of the image through the input unit 6. When the camera setting button 1104 is operated, the UI management unit 814 switches to the next UI.

  In step S901, the UI management unit 814 displays a UI on the display unit 7 in order to set the camera 4, and executes the camera setting. FIG. 12 shows an example of the camera setting UI 1200. The camera setting tab 1201 includes a pull-down menu 1202 for setting a camera model, a pull-down menu 1203 for setting an image size, a pull-down menu 1204 for setting a shutter speed, and a slider 1205 for setting a camera sensitivity. When the measurement execution button 1102 is operated, the UI management unit 814 displays a luminance image acquired by the camera 4 in the display area 1103 according to the imaging parameter set at that time. This allows the user to determine whether the set parameters are appropriate.

  In step S902, the UI management unit 814 displays a UI on the display unit 7 to set the photometric process, and executes the setting. For example, when it is detected that the photometric stereo setting tab 1210 provided in the camera setting UI 1200 is operated, the UI management unit 814 effectively switches the photometric stereo setting tab 1210 as shown in FIG. To switch effectively means to switch the display state of the photometric stereo setting tab 1210 to a state in which the user can operate. The photometric stereo setting tab 1210 includes a pull-down menu 1301 for selecting an image and a feature size setting unit 1302. In this example, it is assumed that any one of three inspection images (shape 1, shape 2 and shape 3) having different feature sizes can be selected. A feature size is set by the feature size setting unit 1302 for each image selected by the pull-down menu 1301.

  A selection unit for selecting a lighting pattern may be disposed on the photometric stereo setting tab 1210. Further, a designation unit may be provided to designate the light emission amount per one illumination.

  In step S903, the UI management unit 814 displays a UI for setting an inspection tool on the display unit 7 and executes the setting. FIG. 14 shows an example of the UI 1400 for setting an inspection tool. The image selection button 1401 is a button for selecting an examination image to be used for examination among a plurality of examination images. The examination category selection button 1402 is a button for selecting a category of tools to be added as an examination tool among a plurality of examination categories. A recognition target setting button 1403 is a button for selecting one of a plurality of recognition targets. In this example, “shape 1” is selected as the inspection image, “recognition” is selected as the category, and “character recognition” is selected as the recognition process. When the add button 1404 is operated, the UI management unit 814 switches to the next UI. FIG. 15 shows a reference image registration UI 1500. In addition to the measurement execution button 1102 and the display area 1103 described above, a registration button 1501 is disposed in the reference image registration UI 1500. When the registration button 1501 is operated, the UI management unit 814 registers the image acquired by the measurement execution button 1102 and displayed in the display area 1103 as a reference image. When the registration is completed, the UI management unit 814 switches to the next UI.

  FIG. 16 shows a measurement area setting UI 1600. In the display area 1103 of the measurement area setting UI 1600, a reference image 1601 and a frame 1602 indicating the measurement area are arranged. The UI management unit 814 changes the position and size of the frame 1602 in accordance with an instruction from the input unit 6. The user adjusts the position and size of the frame 1602 in accordance with the position and size of the portion of the reference image 1601 to be measured. Furthermore, the UI management unit 814 may execute setting of clipping of characters, dictionary setting for registering a specific example of a character to be recognized (character image), and a character corresponding to the character image.

  Next, the flaw inspection tool will be described. As shown in FIG. 17, when a flaw inspection is selected by the inspection category selection button 1402, the UI management unit 814 displays an inspection content selection button 1701. In this example, a tool for measuring the total area of the wound is selected by the inspection content selection button 1701. When the add button 1404 is operated, the UI management unit 814 switches the UI.

  FIG. 18 shows a measurement area setting UI 1800. In the measurement area setting UI 1800, a frame 1802 indicating a measurement area (a flaw inspection area) is disposed. The shape of the frame 1802 can be changed, and for example, one of a plurality of shapes is selected by a pull-down menu 1801 for selecting the shape. The UI management unit 814 renders a frame 1802 of the shape selected by the pull-down menu 1801 in the display area 1103. The UI management unit 814 changes the position and size of the frame 1802 in accordance with an instruction from the input unit 6.

  FIG. 19 shows a setting UI 1900 for setting a flaw detection condition. In the setting UI 1900, a pull-down menu 1901 for selecting a flaw detection direction, a box 1902 for designating a flaw segment size, and a slider 1903 for designating a flaw level are disposed. When the flaw inspection unit 831 detects a flaw in the flaw inspection area (in the frame 1802) based on the flaw detection condition set by the setting UI 1900, the UI management unit 814 displays a flaw detection mark 1910 at the position of the flaw. May be This would allow the user to determine whether the flaw detection conditions are appropriate.

<Inspection mode>
FIG. 20 is a flowchart showing an inspection mode. When the start of the inspection mode is instructed through the input unit 6, the processor 810 shifts the operation mode to the inspection mode.

  In step S2001, the processor 810 captures and acquires an image of the work 2 while switching the illumination direction according to the set lighting pattern. Specifically, the lighting control unit 812 specifies the lighting pattern with reference to the setting data held in the storage device 820, and sends a command for specifying the lighting pattern to the lighting controller 802. The imaging control unit 813 refers to the setting data held in the storage device 820 to specify control parameters (shutter speed, sensitivity, etc.) regarding the camera 4, and transmits a command for specifying this to the camera 4. The photometric processing unit 811 transmits a trigger signal for instructing the start of illumination to the illumination controller 802, and in conjunction with this, transmits a trigger signal for instructing the start of imaging to the camera 4. The lighting controller 802 switches the lighting direction in synchronization with the trigger signal. For example, the lighting controller 802 turns on the light emitting elements corresponding to the four lighting directions one by one in accordance with the lighting pattern specified by the command. The lighting controller 802 may hold the correspondence between the command and the lighting pattern in a memory or the like. The trigger signal may be issued only at the start of lighting or may be issued at the switching timing. The camera 4 captures the work 2 in accordance with the control parameters, and transfers the luminance image to the image processing device 5. In this way, for example, one luminance image is generated per illumination direction.

  In step S2002, the processor 810 obtains the normal vector n and the reflectance ρ from the plurality of luminance images. As described above, the photometric processing unit 811 applies Equation 1 to pixel values of a plurality of luminance images to obtain a normal vector n and a reflectance ρ.

  In step S2003, the processor 810 generates an inspection image according to the set feature size. As described above, the photometric processing unit 811 determines the weight W corresponding to the feature size from the weight table or the like, and executes the accumulation operation using Equation 2 to generate an inspection image (tilt image). Thus, the photometric processing unit 811 may generate an inclination image having pixel values based on the normal vector n of the surface of the workpiece 2 from the plurality of luminance images. When a plurality of feature sizes having different values are set, the photometric processing unit 811 may generate an inspection image for each of the set feature sizes. Further, the photometric processing unit 811 may generate a reflectance image or a texture image by the method described above. For example, the photometric processing unit 811 calculates the reflectance ρ of the surface of the work 2 along with the normal vector n of the surface of the work 2 from a plurality of luminance images, and generates a reflectance image having pixel values based on the reflectance 当 該. You may Here, an image to be inspected may be generated, and generation of an image not to be inspected may be omitted.

  The processor 810 displays the inspection image on the display unit 7 in S2004. The UI management unit 814 may simultaneously or selectively display the luminance image, the tilt image, and the reflectance image on the display unit 7 together with the inspection image. When selectively displaying, the UI management unit 814 may switch and display four luminance images in order, for example, in accordance with a switching instruction from the input unit 6. For example, a specific key provided on the console of the input unit 6 may be assigned as an image switching button.

  In step S2005, the processor 810 instructs the image processing unit 830 to execute an examination. When instructed to perform an examination, the image processing unit 830 activates a preset examination tool to execute an examination on the examination image. For example, the flaw inspection unit 831 determines the level of the flaw according to the set measurement area and detection condition, and transfers the examination result (the level of the flaw) to the determination unit 840. The flaw inspection unit 831 may execute a pattern search using the above-described reference image to set an inspection area, and may perform inspection in the inspection area. Further, the OCR unit 832 executes character recognition processing on the inspection image according to the character recognition setting set in advance, and transfers the character recognition result to the determination unit 840. The OCR unit 832 may also execute a pattern search using the above-described reference image to set an inspection area (character recognition area) and execute an inspection in the inspection area.

  In step S2006, the determination unit 840 of the processor 810 compares the inspection result with the determination threshold to determine whether the workpiece 2 is good. For example, in the case where both the flaw inspection and the OCR are set, the determination unit 840 determines that the workpiece is a workpiece when both the inspection result of the flaw inspection unit 831 and the character recognition result of the OCR unit 832 are at pass level. 2 is determined to be good.

<Image save setting>
FIG. 21 shows an example of the UI 2100 for setting an inspection flow. The UI management unit 814 causes the display unit 7 to display the UI 2100, and sets a plurality of processes to be executed between the start and the end of the inspection flow in accordance with an instruction input from the input unit 6. In this example, an imaging process, a pattern search process, a position correction process and a flaw inspection process are added to the inspection flow. For example, when the end of the inspection flow is designated through the input unit 6, the UI management unit 814 may be set to accumulate the inspection history at the end. The inspection history is, for example, an inspection result or an image used for the inspection.

  When adding each process, the UI management unit 814 may receive selection of an image used in each process through the input unit 6. For example, the user designates four luminance images, tilt images, reflectance images and the like different from the illumination direction for the imaging process through the input unit 6 as acquisition targets, and one of the luminance images for the pattern search process ( An omnidirectional illumination image or the like may be specified as a search target, and an inspection image or the like generated from a tilt image may be specified as an inspection target for the flaw inspection process. In this embodiment, since a plurality of shape images and reflectance images generated from a plurality of luminance images captured in the imaging step can be output to the inspection step in the subsequent stage, the user is generated from the common imaging step. The plurality of inspection images can be applied to various inspections according to the characteristics of each image.

  FIG. 22 illustrates an example of the UI 2200 for setting conditions for accumulating a history. A setting unit 2201 for setting identification information for identifying storage conditions is configured by a pull-down menu for selecting identification information to be set from among a plurality of pieces of identification information. In this example, the storage condition of the identification information “0:” is selected in the setting unit 2201. As the accumulation condition, there are, for example, a condition that an image is accumulated only when an inspection result is not a good product, a condition that an image is always accumulated for each work regardless of the inspection result, and the like. Here, the processor 810 activates the condition setting unit 819 when detecting that the detail setting button or the like is pressed. Condition setting unit 819 sets, for example, one of a mode for always storing or outputting an image and a mode for storing or outputting an image when determination unit 840 determines that the inspection object is not a non-defective item. May be The image selection unit 2202 selects an image to be stored when the storage condition is satisfied. Here, “all” and “designated” can be selected by the image selection unit 2202. The storage destination selection unit 2203 is configured by a pull-down menu for selecting a storage destination of an image (for example, a built-in memory, a portable medium such as a memory card, or a network storage such as an FTP server).

  FIG. 23 illustrates an example of the UI 2300 displayed on the display unit 7 by the UI management unit 814 when “specified” is selected by the image selection unit 2202. In this example, a check box 2301 is provided to select an image to be actually stored among all types of images handled in the inspection flow. Shapes 1 and 2 are inspection images (tilt images) having different feature sizes. The texture is a reflectance image. The normal is an image acquired by omnidirectional illumination. The four arrows are icons indicating the illumination direction. That is, four luminance images having different illumination directions are distinguished by the arrow mark. The image checked in the check box is set as the save target.

  The processor 810 may include determination means for determining whether the condition for storing or outputting the image is satisfied after the determination unit 840 completes the determination. That is, in the end portion of the inspection flow, the processor 810 may determine whether the accumulation condition or the output condition set by the condition setting unit 819 is satisfied.

  FIG. 24 shows an example in which the image output process 2401 is added to the inspection flow. In the embodiment described above, the image is set to be output at the end of the inspection flow, but in this example, the UI management unit 814 outputs the image at an arbitrary position in the inspection flow according to the user instruction input from the input unit 6. Set As described above, the processor 810 may determine whether the condition for storing or outputting an image is satisfied in the image output process 2401 positioned before the determination unit 840 ends the determination. The storage settings and the like associated with the image output process 2401 may be the same as or different from those described with reference to FIGS.

  FIG. 25 shows another example of the UI regarding the storage setting (output setting). In the state where the image output process 2401 is selected by the input unit 6, when an instruction to start setting is further input by the input unit 6, the UI management unit 814 displays the UI 2501. The image variable 2502 functions as an image selection unit for selecting an image to be output. In this example, the image variable to be output is designated by the image variable given to each process in the inspection flow. That is, an image to be output can be selected for each process. The number of output images and the image format may also be set in the UI 2501. An output destination selection unit 2503 is a pull-down menu for selecting an image output destination (for example, a built-in memory, a portable storage medium such as a memory card, or a network storage such as an FTP server).

  FIG. 26 shows an example of the UI 2600 for selecting an image. When the detail setting button is pressed in the UI 2501, the UI management unit 814 displays the UI 2600. In the UI 2600, a radio button for selecting whether to save all the images or individual specification, a check box for individually selecting the images, and the like are arranged. In this example, since the individual designation is selected by the radio button, the check box is validated, and some images are selected through the check box. As described above, an image to be stored or output may be selected from a plurality of luminance images, an inspection image, an omnidirectional illumination image, and a composite luminance image obtained by combining a plurality of luminance images. Further, the UI 2600 may be configured to be able to select an image to be stored or output from a plurality of inspection images each having a different feature size. The UI 2600 may be configured to select an image to be stored or output from a plurality of luminance images, an inspection image, and a reflectance image in which the reflectance of the surface of the inspection object is a pixel value.

<Configuration of lighting device>
FIG. 27A is a perspective view of the lighting device 3. FIG. 27B is a top view of the lighting device 3. FIG. 27C is a bottom view of the lighting device 3. FIG. 27D is a side view of the lighting device 3. The housing of the lighting device 3 has an upper case 2701 and a lower case 2702. At the lower part of the lower case 2, a light diffusion member 2703 for diffusing the light output from each of a plurality of light sources (light emitting elements such as LEDs) is disposed. As shown in FIG. 27A and FIG. 27C, the light diffusion member 2703 has an annular shape as well as the upper case 2701 and the lower case 2702. As shown in FIG. 27B and FIG. 27D, a connector 2704 is provided on the upper surface of the upper case 2701. The connector 2704 is connected with a cable for communication between the lighting controller 802 stored in the lighting device 3 and the image processing device 5.

  FIG. 28A is a side view showing the control substrate 2801 and the LED substrate 2802 stored in the lighting device 3. The control substrate 2801 is an example of a second substrate on which the lighting control unit is mounted. The LED substrate 2802 is an example of a first substrate on which a plurality of light sources are mounted. FIG. 28B is a top view of the LED substrate 2802. FIG. FIG. 28C is a cross-sectional view in which the vicinity of the LED 2803 in the lighting device 3 is enlarged. FIG. 28D is a bottom view of the LED substrate 2802. FIG. FIG. 28E is a side view in which the vicinity of the LED 2803 in the LED substrate 2802 is enlarged.

  A lighting controller 802 and a connector 2704 are disposed on the control board 2801. Light emitting elements such as LEDs constituting the light source group 801 are mounted on the LED substrate 2802. As shown in FIG. 28B, in this embodiment, four LED substrates 2802 are provided. It is assumed that four LEDs 2803 are disposed on each of the four LED substrates 2802. Thus, the light source group 801 is composed of 16 light emitting elements. As shown in FIG. 28C, FIG. 28D and FIG. 28E, the light shielding member 2805 is disposed between two adjacent LEDs 2803 among the plurality of LEDs 2803. When a large number of LEDs 2803 are closely arranged, illumination light emitted from two adjacent LEDs 2803 may pass through the same area of the light diffusion member 2703. In this case, according to the lighting pattern, one of the LEDs 2803 is not lit, the other is lit, the other LED 2803 is not lit, and one of the LEDs 2803 is lit. The illumination light is irradiated with the same light quantity from the same illumination direction on the surface. This makes it difficult to generate an inspection image with high accuracy. Therefore, by arranging a light shielding member 2805 between two adjacent LEDs 2803, the uniformity of the light amount and the independence of the light sources are balanced for the two adjacent LEDs 2803. As shown in FIG. 28C, the light emission direction 2821 of the LED 2803 and the main illumination direction 2822 do not match. Therefore, the light emitted from the LED 2803 is deflected in the direction of the light diffusing member 2703 by arranging the reflecting mirror 2804. Thus, the light emitted by the LED 2803 can be efficiently irradiated to the work 2. In this example, the emission direction 2821 and the reflection direction of the reflecting mirror 2804 are substantially orthogonal, but the cross-sectional shape of the light diffusion member 2703 forms a circular arc (FIG. 28C), and the angle with respect to the circular arc The central angle) is about 90 degrees. By thus enlarging the central angle, it becomes easy to irradiate a substantially uniform parallel light to the surface of the workpiece 2 even if the lighting device 3 is moved away from or brought close to the workpiece 2.

<Circuit configuration of lighting device>
FIG. 29 shows an example of the circuit configuration of the lighting device 3. In this example, one of four LED groups constituting the light source group 801 is shown. The four LEDs 2803 a to 2803 d are connected in series. The variable power supply 2900 having a variable voltage generates and outputs a voltage of a voltage value (for example, 2 V to 20 V) specified by the lighting controller 802. The variable constant current source 2901 adjusts the current flowing in the LED group so as to have the current value (eg, 0 A to 1 A) specified by the lighting controller 802. Adopting such a current control method makes it easy to realize dimming with high linearity. The variable constant current source 2901 detects the value of the voltage applied to the variable constant current source 2901 and feeds it back to the lighting controller 802 to protect the variable constant current source 2901 from overvoltage. Switches 2903a to 2803d are connected in parallel to the LEDs 2803a to 2803d, respectively. The lighting control unit 2911 of the lighting controller 802 can individually switch each of the LEDs 2803a to 2803d between lighting and non-lighting by individually opening and closing the switches 2903a to 2803d. As described above, by connecting the switches 2903a to 2803d in parallel to the LEDs 2803a to 2803d, it is possible to individually light up any one of the LEDs 2803a to 2803d or to light all of the LEDs 2803a to 2803d. This helps to realize various lighting patterns. The lighting control unit 2911 switches on / off of the main switch 2903e inserted between the variable constant current source 2901 and the ground to execute lighting control in units of one LED group. The communication unit 2910 receives a control signal instructing a lighting pattern and a trigger signal instructing start of lighting from the illumination control unit 812 of the image processing apparatus 5, and passes it to the lighting control unit 2911. The lighting control unit 2911 reads lighting pattern data 2920 corresponding to the control signal from the storage unit 803, and controls the switches 2903a to 2803d according to the lighting pattern data 2920. The lighting pattern data 2920 may include identification information of light sources that are simultaneously lighted at one lighting timing among a plurality of light sources, information indicating a lighting order of the plurality of light sources, and the like. For example, 16 LEDs can be distinguished by 4-bit identification information. The lighting pattern data 2920 may include information indicating the number of illumination directions (the number of divisions). The number of illumination directions is basically four, but may be eight. The lighting pattern data 2920 may include information indicating a lighting width (the number of light sources simultaneously lit at one lighting timing). For example, four LEDs light up in the basic lighting width. On the other hand, two LEDs light in one half of the lighting width, and one LED lights in one quarter of the lighting width. The lighting pattern data 2920 may include information specifying the timing at which all the LEDs are lit. For example, all lighting may be instructed before performing lighting according to the photometric stereo method, or all lighting may be instructed after performing lighting according to the photometric stereo method. The lighting pattern data 2920 may include information indicating a lighting start position. For example, identification information indicating the LED to be lit first among the 16 LEDs may be included. In this case, the LED to be lit is changed in accordance with the clockwise illumination direction from the LED to be lit first. The lighting pattern data 2920 may be configured by information indicating the number of times of lighting (1 to 16 times) in one lighting cycle or identification information (0x000 to 0xFFFF) of the LED to be lit. The lighting pattern data 2920 may include an illumination light amount per one LED, a lighting time (exposure time), an interval time indicating a lighting interval, and the like. As described above, the lighting control unit 2911 turns on the plurality of LEDs 2803 according to the lighting pattern data 2920 which is the lighting pattern data 2920 stored in the storage unit 803 and specified by the control signal received through the signal line 8. Therefore, the number of signal lines can be significantly reduced as compared with the case where the signal lines 8 are arranged for each LED.

  FIG. 30 is a diagram showing a timing sequence of lighting control. When the control signal is received at time t1, the lighting control unit 2911 determines a voltage value according to the lighting pattern and sets it in the variable power supply 2900. Since it takes time for the voltage output from variable power supply 2900 to stabilize at the target voltage, voltage setting is performed first. This improves the response of lighting.

  At time t2, the lighting control unit 2911 individually sets on / off of the switches 2903a to 2803d in accordance with the lighting pattern. That is, the switch connected in parallel to the LED instructed to light by the lighting pattern is switched on, and the switch connected in parallel to the LED instructed not to light by the lighting pattern The switch is switched off.

  When the trigger signal is received at time t3, the lighting control unit 2911 turns on the main switch 2903e. As a result, the LED lights up according to the lighting pattern. The lighting control unit 2911 adjusts the voltage applied to the LED group in accordance with the number of LEDs to be lit (in accordance with the overvoltage feedback). This voltage adjustment ends at time t4.

  At time t5, the lighting control unit 2911 turns off the main switch 2903e and turns off the lighted LED. The lighting control unit 2911 sets the voltage of the variable power supply 2900 high enough for the next lighting cycle. By setting the voltage of the variable power supply 2900 sufficiently high, responsiveness of lighting to the lighting command is improved. In particular, in the photometric stereo method, since it is necessary to acquire a large number of luminance images, it is required to reduce the time required for one shooting. In particular, when the workpiece 2 is moving, the position of the workpiece 2 in each luminance image is shifted, so the longer the imaging time, the lower the accuracy of the inspection image. Therefore, the improvement of the responsiveness of the lighting device 3 alleviates these problems.

<Lighting pattern>
FIG. 31 is a diagram showing an example of the lighting pattern. The lighting pattern P1 is a pattern for realizing illumination from four illumination directions using 16 LEDs. The lighting pattern P2 is a pattern for realizing illumination from eight illumination directions using 16 LEDs. With luminance images from eight illumination directions compared to luminance images from four illumination directions, the calculation accuracy of the normal vector n and the reflectance is improved, so that there is an advantage that the accuracy of the inspection image is improved. Further, by increasing the illumination direction, the detection accuracy of the edge present in the oblique direction and the outer shape detection accuracy of the circular workpiece are improved. The lighting pattern P3 is a pattern for realizing illumination from four illumination directions using 16 LEDs. Compared to the lighting pattern P1, in the lighting pattern P3, the number of LEDs lit by one lighting is half. Since the light source area is reduced, the reflection of the light source onto the work 2 can be reduced. The lighting pattern P4 is a pattern for realizing illumination from eight illumination directions using 16 LEDs. As compared with the lighting pattern P2, in the lighting pattern P4, the number of LEDs lit by one lighting is doubled. This is advantageous in the case where the light intensity as well as the accuracy of the inspection image is required. The lighting pattern P5 is a pattern in which all lighting is added before and after the lighting pattern P1 which is a basic pattern. The two luminance images obtained by illuminating from all directions are useful in estimating the amount of movement of the workpiece 2. As a result, it is possible to create an inspection image while correcting the position of the workpiece 2 within the luminance image with high accuracy even when performing shooting while moving the workpiece 2. The lighting pattern P6 is a lighting pattern in which the lighting start position is shifted by one clockwise in the lighting pattern P1. In the present embodiment, since the illumination device 3 can be moved independently from the camera 4, the installation direction of the camera 4 and the installation direction of the illumination device 3 may be shifted. Moreover, it is not easy to correct the position of the lighting device 3 once fixed. Therefore, the lighting start position of the lighting device 3 is corrected by the deviation between the mounting direction of the camera 4 and the mounting direction of the lighting device 3 to match the lighting direction assumed in the luminance image with the actual lighting direction. It can be done.

<Adjustment of lighting pattern lighting position>
FIG. 32 shows an example of the UI 3200 for adjusting the lighting start position. The inspection tool setting unit 817 includes an adjustment unit for adjusting the lighting start position described above, and sets the UI 3200 in the display unit 7. The UI 3200 has a display area 1103 for displaying a luminance image and an adjustment button 3201 for adjusting the lighting start position. The inspection tool setting unit 817 superimposes and displays an arrow 3202 which is an icon for indicating the illumination direction assumed for the luminance image on the luminance image. This makes it easy to check whether the illumination direction assumed for the luminance image matches the actual illumination direction. The user operates the adjustment button 3201 through the input unit 6. The inspection tool setting unit 817 detects this adjustment operation, and notifies the illumination control unit 812 of the adjustment amount. The lighting control unit 812 transmits the adjustment amount of the lighting start position to the lighting controller 802. When the lighting control unit 2911 of the lighting controller 802 receives the adjustment amount through the communication unit 2910, the lighting control unit 2911 stores the adjustment amount in the storage unit 803. Thus, the lighting control unit 2911 corrects the lighting start position in the lighting pattern specified by the lighting pattern data 2920 according to the adjustment amount. In addition, in order to determine whether the adjustment is correct, the inspection tool setting unit 817 may cause the camera 4 to perform imaging through the imaging control unit 813 to acquire a luminance image and display it in the display area 1103. As described above, the inspection tool setting unit 817 may update and display the luminance image when the LED to be lighted is changed. Note that as shown in FIG. 32, the display control unit 851 may switch the luminance image displayed in the display area 1103 and display it on the display unit 7. This will allow the illumination direction to be set correctly in all luminance images with different illumination directions. FIG. 33 shows an example of the UI 3300 for adjusting the lighting start position. As shown in FIG. 33, the inspection tool setting unit 817 may display four luminance images side by side in the display area 1103. This will save the user the trouble of switching the four luminance images.

<Summary>
According to the present embodiment, the photometric processing unit 811 calculates the normal vector of the surface of the work 2 from the plurality of luminance images acquired by the camera 4 according to the photometric stereo method, and calculates from the plurality of luminance images. The pixel value of the pixel of interest is accumulated and calculated using the normal vector of the adjacent pixel adjacent to the pixel of interest for the inclination image formed by the pixel values based on the normal vector and the reduced image of the inclination image. An inspection image having the pixel value is generated. In particular, according to the present embodiment, the feature size setting unit 815 is provided which sets a feature size which is a parameter for giving a weight to the component of the reduced image used in the stacking operation. By introducing the concept of the feature size in this manner, it is possible to easily set parameters for generating an inspection image from an image acquired using the principle of photometric stereo.

  The feature size setting unit 815 may set a plurality of feature sizes having different values. In this case, the photometric processing unit 811 may generate an inspection image for each of the plurality of feature sizes set by the feature size setting unit 815. It is conceivable that the appropriate feature size may differ depending on the type of inspection tool. Therefore, generating inspection images according to a plurality of feature sizes each having a different value may be advantageous in selecting a more appropriate inspection image corresponding to the inspection.

  The flaw inspection unit 831 executes flaw inspection on a plurality of inspection images generated using different feature sizes, and the determination unit 840 determines the quality of the work 2 using the inspection result of the flaw inspection unit 831. It is also good. By performing flaw inspection on a plurality of inspection images, it is not necessary to select one inspection image in advance, which may be convenient for the user. The OCR unit 832 executes character recognition processing on a plurality of inspection images generated using different feature sizes, and the determination unit 840 determines the quality of the work 2 using the character recognition result of the OCR unit 832. Good. By performing character recognition processing on a plurality of inspection images, it is not necessary to select one inspection image in advance, which may be convenient for the user.

  Originally, it is possible to generate a height image indicating the height of the work 2 by the photometric stereo method. However, in order to measure the height of the surface of the work 2, it is necessary to set the positional relationship between the camera 4 and the lighting device 3 quite strictly. On the other hand, it is also possible to use shape information and texture (pattern) information without using height information among images obtained by the photometric stereo method. For example, if height images are used for flaw inspection or OCR, strict setting of the camera 4 and the illumination device 3 is not necessary. Thus, if it is an unnecessary inspection tool of accurate height data, arrangement conditions of camera 4 and lighting installation 3 can be eased. The illumination directions may be three or more.

  The photometric processing unit 811 calculates the reflectance of the surface of the workpiece 2 along with the normal vector of the surface of the workpiece 2 from the plurality of luminance images acquired by the camera 4, and the reflectance configured by pixel values based on the reflectance An image may be generated, and the determination unit 840 may determine the quality of the work 2 using the reflectance image. This is because there are inspection tools for which reflectance images are suitable for inspection. The photometric processing unit 811 generates an inclination image composed of pixel values based on the normal vector of the surface of the workpiece 2 from the plurality of luminance images acquired by the camera 4, and the determination unit 840 uses the inclination image to generate the workpiece 2. It may be judged whether or not This is because there are inspection tools for which the tilt image is suitable for inspection. The determination unit 840 may determine the quality of the work 2 using the luminance image. This is because there are inspection tools that are suitable for inspection of luminance images before being processed into tilt images and reflectance images. The determination unit 840 may determine the quality of the work 2 using at least one luminance image among a plurality of luminance images each having a different illumination direction. Since there are scratches that become clear due to the difference in the illumination direction, a luminance image obtained by illuminating the workpiece 2 from a certain direction would be preferable for detecting such scratches.

  The determination unit 840 may simultaneously turn on all the light sources of the lighting device 3 and determine the quality of the work 2 using the luminance image acquired by the camera 4. The quality of the work 2 may be determined by using a so-called omnidirectional illumination image. For example, an omnidirectional illumination image may be suitable for area calculation of a certain portion of the workpiece 2 and measurement of the length of a terminal.

  The determination unit 840 may determine the quality of the work 2 using a composite luminance image generated by combining a plurality of luminance images having different illumination directions. The synthetic luminance image is an image similar to the omnidirectional illumination image. Thus, using synthetic luminance images instead of omnidirectional illumination images would allow inspection to be performed without acquiring omnidirectional illumination images. When an omnidirectional illumination image is required, it is necessary to acquire four luminance images having different illumination directions and one omnidirectional illumination image obtained by illuminating from four directions simultaneously. That is, five illuminations and five imagings are required. On the other hand, if a synthetic luminance image is used, four illuminations and four imagings may be performed. By adopting the synthetic luminance image in this manner, the processing load on the processor 810 can be reduced when it is necessary to process a plurality of inspection images in a short time. In addition, although it is necessary to reduce the conveyance speed of line 1 as the number of acquired images increases, in the present embodiment, since the number of acquired images can be reduced, the conveyance speed of line 1 can also be increased. .

  The storage device 820 may store and hold the inspection image. The determination unit 840 or the image processing unit 830 may read the inspection image from the storage device 820 and execute the inspection, and may determine the quality of the work 2 based on the inspection result. The storage device 820 may be any of a built-in memory, a portable storage medium, and a network storage. For example, if the inspection image is stored in a portable storage medium, network storage, it will be possible to execute the inspection process in a device different from the device that generated the inspection image.

  The storage device 820 may store a plurality of inspection images generated by applying different feature sizes. The storage device 820 may store at least one of the tilt image and the reflectance image in addition to the inspection image. The image selection unit 816 may select one inspection image from a plurality of inspection images. The inspection tool setting unit 817 may set an inspection tool for the inspection image selected by the image selection unit 816. Among the plurality of inspection images generated by applying feature sizes different in value, there may be unnecessary ones for the inspection. Thus, the user may set the inspection image according to the inspection tool.

  As described with reference to FIG. 15 and the like, the image processing unit 830 may set the inspection area by executing the pattern search using the reference image acquired from the non-defective item. The determination unit 840 may determine the quality of the work 2 using the result of the inspection performed in the inspection area. The inspection area is, for example, a character recognition area.

  As described with reference to FIGS. 11 and 21 to 26, the image selection unit 816 may select an image to be stored or output among the plurality of luminance images and inspection images acquired by the camera 4. . In addition, the image selection unit 816 stores a plurality of luminance images, an inspection image, a luminance image acquired by lighting all of a plurality of light sources included in the lighting device 3 and a synthetic luminance image obtained by synthesizing a plurality of luminance images. An image to be a target or an output target may be selected. Furthermore, the image selection unit 816 may select an image to be stored or output from a plurality of examination images each having a different feature size. Furthermore, the image selection unit 816 may select an image to be stored or output from a plurality of luminance images, an inspection image, and a reflectance image in which the reflectance of the surface of the workpiece 2 is a pixel value. By appropriately selecting the image associated with the examination in this manner, it will be easy to store or output the desired image.

  A condition setting unit 819 may be further provided to set conditions for storing or outputting an image. For example, as described with reference to FIGS. 22 and 26, the condition setting unit 819 always stores or outputs an image when the determination unit 840 determines that the work 2 is not good. You may set any one of the following modes. As described with reference to FIGS. 21 to 26, the processor 810 may determine whether the condition for storing or outputting the image is satisfied after or before the determination unit 840 completes the determination. For example, it may be determined in the inspection flow whether or not to save the image when the inspection is completed, or it may be determined whether to save the image in any step of the inspection flow. In particular, in the latter case it will be possible to save also intermediate images that occur during the inspection flow. Such intermediate images may be useful in tracking down the cause of inspection failure and adjusting control parameters.

  According to the present embodiment, the lighting device 3 includes the plurality of LEDs 2803 arranged in a substantially annular shape, the light diffusion member 2703 for diffusing the light output from each of the plurality of LEDs 2803, and a predetermined start when instructed to start lighting. And a lighting control unit 2911 for lighting a plurality of light sources according to the lighting pattern. In particular, the lighting device 3 adjusts the distance to the work 2 by moving independently of the camera 4. As a result, depending on the type and placement of the work, the illumination device 3 can be moved away from the work to use regular reflection light, or the illumination device 3 can be brought close to the work to use diffuse reflection light. The lighting controller 802 such as the lighting control unit 2911 may be disposed outside the lighting device 3.

  As described with reference to FIGS. 28C to 28E, the light shielding member 2805 may be provided between two adjacent LEDs 2803 among the plurality of LEDs 2803. As a result, the balance between the uniformity of the light amount and the independence of the light source is maintained for the two adjacent LEDs 2803.

  The lighting apparatus 3 may include an LED substrate 2802 which is a first substrate on which a plurality of LEDs 2803 are mounted, and a control substrate 2801 which is a second substrate on which the lighting control unit 2911 is mounted. By separating the substrates, the effects of heat generation of the plurality of LEDs 2803 can be mitigated.

  An example in which the plurality of LEDs 2803 are arranged in an annular shape has been described with reference to FIGS. 27 and 28. A toroidal arrangement is advantageous for achieving collimated light from each illumination direction. In addition, annular | circular shape is only an example and arrangement | positioning etc. of a regular polygon may be arrange | positioned. For example, sixteen LEDs 2803 may be arranged at each vertex of a dodecagon.

  The lighting device 3 may have a storage unit 803 storing the lighting patterns of the plurality of LEDs 2803. The lighting control unit 2911 may turn on the plurality of LEDs 2803 according to the lighting pattern stored in the storage unit 803 when instructed to start lighting by the control signal or the trigger signal. Thus, even if the lighting control unit 2911 is the lighting pattern data 2920 stored in the storage unit 803 and lights the plurality of LEDs 2803 according to the lighting pattern data 2920 specified by the control signal received through the signal line 8 Good. Therefore, the number of signal lines can be significantly reduced as compared with the case where the signal lines 8 are arranged for each LED. For example, in order to control 16 LEDs 2803 from the image processing apparatus 5, at least 17 signal lines are required. However, in the present embodiment, since the signal line 8 capable of transmitting the control signal instructing the lighting pattern can be adopted, the number of signal lines can be reduced, and the cost of the cable connecting the image processing device 5 and the lighting device 3 Can be reduced.

  The storage unit 803 may store a plurality of lighting patterns (such as P1 and P3) in which the number of light sources to be simultaneously lighted is different. This makes it possible to easily change the amount of light by half or twice. The storage unit 803 may store a plurality of lighting patterns (such as P1 and P2) each having a different number of illumination directions. This makes it possible to easily obtain luminance images with different illumination directions. The storage unit 803 has a plurality of lighting patterns (P1, P3, P5, and P6) for illuminating the inspection object in order from four directions, and a lighting pattern (P2 and P4) for illuminating the inspection object in order from eight directions. You may memorize. This makes it possible to easily change the amount of light by half or twice. The storage unit 803 may store a lighting pattern (such as P5) for lighting all of the plurality of light sources simultaneously. This makes it possible to easily obtain an omnidirectional illumination image. The estimation unit 833 of the image processing unit 830 estimates the position of the workpiece 2 from the omnidirectional illumination image. As indicated by the lighting pattern P5, the illumination control unit 812 and the imaging control unit 813 simultaneously turn on all of the plurality of LEDs 2803 at the first timing to cause the camera 4 to acquire the first luminance image. Further, as indicated by the lighting pattern P5, the illumination control unit 812 and the imaging control unit 813 simultaneously turn on all the plurality of LEDs 2803 at the Nth timing (the sixth timing in the lighting pattern P5), To obtain a luminance image of The estimation unit 833 estimates the movement amount of the workpiece 2 from the first luminance image and the second luminance image. That is, the estimation unit 833 estimates the position of the work 2 in the luminance image of the second to fifth timings from the luminance image of the first timing and the luminance image of the sixth timing in the lighting pattern P5. The photometric processing unit 811 acquires the movement amount of the work 2 at each timing from the estimation unit 833, and corrects each luminance image so that the positions of the work 2 in the luminance images at the second to fifth timings coincide. And create an inspection image from the corrected luminance image. In order to estimate the position of the work 2, since the omnidirectional illumination image is advantageous, a lighting pattern including lighting all the plurality of LEDs 2803 at the same time as the lighting pattern P5 is required.

  As described with reference to FIG. 29, the plurality of LEDs 2803 form a light source group for each of a predetermined number (for example, four) of LEDs 2803 and even if the plurality of LEDs 2803 are connected in series in each light source group Good. Switches 2903 a to 2903 d that can be switched on / off by the lighting control unit 2911 are connected in parallel to the respective LEDs 2803 a to 2803 d. Thereby, it becomes possible to freely switch between the lighting and non-lighting of the plurality of LEDs 2803 a to 2803 d according to the lighting pattern. That is, various lighting patterns can be adopted.

  As described with reference to FIG. 29, the lighting control unit 2911 includes a variable power supply 2900 that supplies voltages to the plurality of LEDs 2803, a variable constant current source 2901 that adjusts current flowing to the plurality of LEDs 2803, and a variable constant current source 2901. The main switch 2903 e may be controlled to switch on / off the switch. That is, as described with reference to FIG. 30, the lighting control unit 2911 is a switch connected in parallel to each of the plurality of LEDs 2803 according to the lighting pattern after the voltage supplied by the variable power supply is sufficiently high. , And the main switch 2903e may be switched on to light any one of the plurality of LEDs 2803 according to the lighting pattern. This will achieve high response of lighting and improved power efficiency. The lighting control unit 2911 may control the voltage of the variable power supply 2900 according to the voltage value fed back from the variable constant current source 2901 so that an overvoltage is not applied to the variable constant current source 2901. This will allow the variable constant current source 2901 to be protected from over voltage.

  As described with reference to FIG. 2 and the like, the lighting device 3 includes at least two pairs of light sources each having the same light amount. In FIG. 2, the illumination light L1 and the illumination light L2 have equal light amounts, and the illumination directions are also different by 180 degrees to form a pair. Similarly, the illumination light L3 and the illumination light L4 have equal amounts of light, and the illumination directions are also different by 180 degrees to form a pair. By preparing at least two light source pairs in this manner, it is possible to accurately calculate the normal vector and the reflectance of each surface of the workpiece. Such a light source pair is formed also for the lighting pattern described using FIG. For example, two light source pairs are provided in the lighting patterns P1, P3, P5, and P6, and four light source pairs are provided in the lighting patterns P2 and P4.

  DESCRIPTION OF SYMBOLS 1 ... Line, 2 ... Work, 3 ... Lighting apparatus, 4 ... Camera, 5 ... Image processing apparatus, 6 ... Input part, 7 ... Display part

According to the invention, for example
Imaging means for imaging an inspection object;
Illumination means having a plurality of light sources individually housed in a substantially annular casing provided separately from the imaging means and individually illuminating the inspection object from three or more different illumination directions;
Control means for switching the illumination direction by lighting the light sources corresponding to the plurality of illumination directions in turn after lighting the light sources to be lit first based on the information indicating the lighting start position of the plurality of light sources ;
Inspection image generation means for synthesizing a plurality of luminance images acquired by the imaging means by photometric stereo method to generate an inspection image having a plurality of pixel values according to the shape or reflectance of the surface of the inspection object ,
A determination unit that determines the quality of the inspection object using the inspection image;
Setting means for receiving the adjustment of the lighting start position in order to match the actual illumination direction of the plurality of luminance images with the illumination direction assumed in advance;
An inspection apparatus is provided, characterized in that

Claims (17)

Imaging means for imaging an inspection object;
A plurality of light sources arranged in a substantially annular shape, a storage unit storing the lighting patterns of the plurality of light sources, and a lighting pattern stored in the storage unit, specified by a control signal received via a signal line A lighting control unit for lighting the plurality of light sources according to a lighting pattern, and illumination means for adjusting a distance to the inspection object by moving independently of the imaging means;
An inspection image generation unit that combines a plurality of luminance images acquired by the imaging unit according to a photometric stereo method, and generates an inspection image having a plurality of pixel values according to the inclination or reflectance of the surface of the inspection object When,
And a determination unit that determines the quality of the inspection object using the inspection image.   The inspection apparatus according to claim 1, wherein the lighting pattern is a lighting pattern according to a photometric stereo method. The lighting means further comprises a communication unit,
The inspection apparatus according to claim 1, wherein the control unit of the illumination unit reads out a lighting pattern corresponding to the information received by the communication unit from the storage unit and uses the lighting pattern.   The inspection apparatus according to any one of claims 1 to 3, wherein the lighting pattern includes identification information of a light source which is simultaneously lighted at one lighting timing among the plurality of light sources. .   The inspection apparatus according to any one of claims 1 to 3, wherein the lighting pattern includes information indicating a lighting order of the plurality of light sources.   The inspection apparatus according to any one of claims 1 to 5, wherein the storage unit stores a plurality of lighting patterns different in the number of light sources to be lighted simultaneously.   The inspection apparatus according to any one of claims 1 to 6, wherein the storage unit stores a plurality of lighting patterns each having a different number of illumination directions.   The inspection apparatus according to any one of claims 1 to 7, wherein the storage unit stores a plurality of lighting patterns for illuminating the inspection object in order from four directions.   The inspection apparatus according to any one of claims 1 to 8, wherein the storage unit stores a lighting pattern for illuminating the inspection object in order from eight directions.   The inspection apparatus according to any one of claims 1 to 9, wherein the storage unit stores a lighting pattern for lighting all of the plurality of light sources simultaneously. At the first timing, all of the plurality of light sources are turned on simultaneously to cause the imaging unit to acquire the first luminance image, and at the Nth timing, all of the plurality of light sources are simultaneously turned on to cause the imaging unit to The image processing apparatus further comprises estimation means for acquiring a luminance image and estimating a movement amount of the inspection object from the first luminance image and the second luminance image.
The inspection apparatus according to claim 10, wherein any one of the plurality of light sources is turned on according to a photometric stereo method at each timing existing between the first timing and the Nth timing. The plurality of light sources form a light source group for each predetermined number of light sources, and a predetermined number of light sources are connected in series in each light source group,
The control unit controls a constant current source according to the lighting pattern to supply current to each light source group, and a variable power supply which supplies voltage to the light source group according to a voltage applied to the constant current source The inspection apparatus according to any one of claims 1 to 11, wherein the output voltage of the sensor is adjusted.   A switch is connected in parallel to each of the predetermined number of light sources, and the control unit controls switching of the switches to switch on and off each of the predetermined number of light sources. An inspection device according to Item 12. Display means for displaying a luminance image of the inspection object;
The inspection apparatus according to any one of claims 1 to 12, further comprising: an adjusting unit configured to adjust an illumination direction by changing a light source to be lit in the lighting pattern.   The inspection apparatus according to claim 14, wherein the display unit simultaneously displays a luminance image of the inspection object and an icon indicating an illumination direction applied when the luminance image is acquired.   16. The inspection apparatus according to claim 14, wherein when the light source to be lit is changed by the adjustment unit, the display unit updates and displays the luminance image.   The inspection apparatus according to any one of claims 1 to 16, wherein the plurality of light sources include at least two pairs of light sources each having the same light amount.