Inspection device

Abstract

The present invention provides an inspection device which is positioned with respect to a conveyance device that is installed separately from the inspection device, and can perform inspection with good accuracy even when an object to be inspected is carried in and out by using the conveyance device.　An inspection device 10 that is positioned with respect to a conveyance device 50 and inspects an object 12 to be inspected that is carried in by using the conveyance device 50 includes: an imaging unit 20 that moves relative to the object 12 to be inspected and images the object; and a control unit 30 that controls operation of the imaging unit 20 to acquire image data. The control unit 30 is configured to splice a plurality of pieces of image data on the basis of the three-dimensional shape of the object 12 to be inspected calculated by a height measurement portion 32b to generate entire image data of the object 12 to be inspected, and inspect the object 12 to be inspected on the basis of the entire image data. The control unit 30 performs calibration by using a reference jig 60 that is positioned at a location different from a substrate placement surface of the conveyance device 50.

Description

Inspection Equipment

[0001] The present invention relates to an inspection device.

[0002] An inspection device for inspecting an object to be inspected, such as an electronic circuit board (hereinafter simply referred to as a "board"), is installed in a manufacturing plant, and the object to be inspected that has been transported from a previous process is carried in by a transport section (e.g., a conveyor) within the inspection device, fixed in the inspection device, and inspected, and after inspection, the object to be inspected is carried out from the inspection device and passed to the next process. When installing such an inspection device in, for example, an existing plant, a transport device (e.g., a conveyor) already in use in the plant may be reused (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2018-112523

[0004] Compared to a configuration in which a dedicated transport unit is installed within the inspection device, a configuration in which an inspection device equipped with an imaging unit, etc. is installed on a transport device installed separately from the inspection device is independent of the inspection device, and therefore, for example, the height of the transport device and the flatness of the substrate mounting surface vary from plant to plant. In conventional inspection devices, calibration is performed by placing an adjustment (calibration) jig on the transport unit of the inspection device, but because the transport device differs from plant to plant, there was a problem that adjustments cannot be made in this way. If accurate adjustments cannot be made, for example, when the entire object to be inspected is divided and imaged, it becomes impossible to accurately inspect the joints between these images.

[0005] The present invention has been made in consideration of such problems, and aims to provide an inspection device that can perform inspections with high accuracy even when it is placed on a conveying device installed separately from the inspection device and configured to use this conveying device to carry in and out the object to be inspected.

[0006] In order to solve the above problem, the inspection apparatus of the present invention is an inspection apparatus that is arranged relative to a conveying device and inspects an object to be inspected that has been carried in by the conveying device, and includes: an imaging unit that moves relative to the object to be inspected to image the object to be inspected; and a control unit that controls the operation of the imaging unit and acquires image data imaged by the imaging unit, and the control unit includes an imaging processing unit that performs image processing on multiple image data obtained by dividing the object to be inspected by the imaging unit, and a height measurement unit that calculates the three-dimensional shape of the object to be inspected based on the image data, and is configured to generate overall image data of the object to be inspected by combining the multiple image data based on the three-dimensional shape calculated by the height measurement unit, and inspect the object to be inspected based on the overall image data, and the control unit performs calibration using a jig that is arranged at a position different from the substrate mounting surface of the conveying device.

[0007] Furthermore, in the inspection device according to the present invention, it is desirable that the jig be positioned at a predetermined calibration height, and that the control unit perform inspection by imaging the object to be inspected within an imaging range including the calibration height using the imaging unit.

[0008] Furthermore, it is preferable that the inspection device according to the present invention has a main frame that supports the imaging unit, and that the jig be detachable from the main frame.

[0009] Furthermore, in the inspection device of the present invention, it is desirable that the control unit corrects the inspection surface of the object to be inspected so that it is horizontal with the imaging surface of the imaging unit, taking into account distortion of the substrate mounting surface of the conveying device, and restores the three-dimensional shape of the entire object to be inspected.

[0010] Furthermore, the inspection device according to the present invention has a predetermined safety area provided on the conveying device side of the imaging unit, and has a camera-under-sensor that detects that at least a portion of the object to be inspected transported by the conveying device is within the safety area, and the camera-under-sensor has a light-projecting unit that projects light and a light-receiving unit that receives the light, arranged on either side of the conveying device, and it is desirable that the light-projecting unit and the light-receiving unit are arranged so that the light forms a predetermined angle with respect to a direction perpendicular to the direction in which the object to be inspected is transported by the conveying device.

[0011] According to the present invention, an inspection device can be provided that is arranged relative to a conveying device installed separately from the inspection device and that can perform inspections with high accuracy even when configured to use this conveying device to transport the object to be inspected in and out.

[0012] 1 is a perspective view showing the appearance of an inspection device. FIG. 1 is an explanatory diagram showing the appearance of the inspection device with the cover removed, where (a) is a perspective view and (b) is a front view. FIG. 2 is an explanatory diagram for explaining the configuration of the inspection device. FIG. 3 is an explanatory diagram for explaining the relationship between the movable range of the imaging unit and the safety area. FIG. 4 is an explanatory diagram for explaining the arrangement of the light beam of the sensor below the camera. FIG. 5 is a flowchart for explaining the inspection process. FIG. 6 is an explanatory diagram for explaining a conventional method for combining divided area images. FIG. 7 is an explanatory diagram for explaining a step that occurs in a conventional method for combining divided area images. FIG. 8 is an image of an electronic circuit board showing an example of the arrangement of DOPs set in the method for combining divided area images used in the inspection device according to the present embodiment. FIG. 9 is an explanatory diagram for explaining that a step does not occur in the method for combining divided area images used in the inspection device according to the present embodiment. FIG. 10 is an image of an electronic circuit board showing another example of the arrangement of DOPs set in the method for combining divided area images used in the inspection device according to the present embodiment. FIG. 11 is an explanatory diagram for explaining a reference jig attached to a support frame, where (a) is a perspective view, (b) is a top view, and (c) is an A-A cross-sectional view of (b). 10A and 10B are explanatory diagrams for explaining a method of fixing a reference jig to a support frame, in which (a) shows a top view, (b) shows an enlarged view of the vicinity of a cap screw, and (c) shows an enlarged view of the vicinity of a pin and a recess.

[0013] A preferred embodiment of the present invention will now be described with reference to the drawings. First, the configuration of an inspection device 10 according to this embodiment will be described with reference to FIGS. 1 to 5. As shown in FIG. 1, the inspection device 10 is arranged relative to a transport device 50 installed separately from the inspection device 10. The transport device 50 is passed through a through-hole 41 provided in the inspection device 10, and the inspection device 10 is used to transport an object under test 12 into and out of the interior of the inspection device 10 covered by a cover 40 (the inspection space within the through-hole 41). The inspection device 10 is configured to inspect the object under test 12 using image data (two-dimensional image data or pattern image data) of the object under test 12 obtained by capturing an image of the transported object under test 12. The object under test 12 is, for example, an electronic circuit board (substrate) on which components are mounted and solder is applied.

[0014] 2 and 3, the inspection apparatus 10 is arranged relative to a transport device 50 that loads, holds, and loads the object under test 12 into and out of the inspection apparatus 10, and is configured to include an imaging unit 20 that is an imaging section that illuminates and images the object under test 12, an XY stage 16 that moves the imaging unit 20 relatively to the object under test 12, and a control unit 30 that is a control section that controls the operation of the imaging unit 20 and the XY stage 16 and inspects the object under test 12. For convenience of explanation, as shown in Fig. 3, the substrate mounting surface of the transport device 50 (here, a plane parallel to the ground surface of the inspection apparatus 10) is defined as the XY plane (the X and Y directions are orthogonal to each other, and the direction in which the object under test 12 is transported by the transport device 50 is defined as the X direction), and the direction perpendicular to the substrate mounting surface (i.e., the imaging direction of the camera unit 21 that configures the imaging unit 20 (the optical axis direction of the optical system of the camera unit 21)) is defined as the Z direction.

[0015] The imaging unit 20 is attached to the moving table of the XY stage 16 and can be moved in both the X and Y directions by the XY stage 16. The XY stage 16 is, for example, a so-called H-shaped XY stage. The XY stage 16 includes a Y-axis unit 16b consisting of a Y-direction guide extending in the Y direction and a Y-drive unit that moves the moving table in the Y direction along the Y-direction guide, and an X-axis unit 16a consisting of two X-direction guides supporting the Y-direction guide at both ends and an X-drive unit that moves the moving table and the Y-direction guides in the X direction along the X-direction guides. The XY stage 16 also includes a Z-axis unit 16c consisting of a Z-direction guide attached to the Y-direction guide and extending in the Z direction, and a Z-drive unit that moves the imaging unit 20 attached to the moving table in the Z direction via the Z-direction guide. The imaging unit 20 may further include a rotation mechanism that rotates the imaging unit 20 around the optical axis of the optical system of the camera unit 21. The X-drive unit, Y-drive unit, and Z-drive unit may be linear motors or ball screws.

[0016] As shown in FIG. 2( a), the inspection device 10 includes a main frame 42 that supports the entire inspection device 10, and a support frame 43 that is attached to the upper surface of the main frame 42 and supports the imaging unit 20 and other components. As shown in FIG. 2( b), the main frame 42 is composed of a first frame 42a and a second frame 42b that can be separated in the Y direction (a direction perpendicular to the direction in which the inspection object 12 is transported by the transport device 50). The through-hole 41 described above is formed in the first frame 42a so that its cross section is U-shaped when viewed from the X direction. A plurality of casters (wheels) 44a are attached to the underside of the first frame 42a. A plurality of fixing legs 44b are attached to the underside of the second frame 42b. Therefore, the inspection device 10 can be easily positioned relative to the conveying device 50 by moving the first frame 42a using the casters 44a so that the conveying device 50 is inserted into the through-hole 41 from the opening (the opening of the U-shaped cross-section through-hole 41) on the side of the first frame 42a where the second frame 42b is attached, and then attaching the second frame 42b to the first frame 42a so as to close the opening of the first frame 42a. The first frame 42a is fixed using the fixing legs 44b provided on the first frame 42a. Because the casters 44a and the fixing legs 44b are attached to the first frame 42a and the second frame 42b in this way, even if the first frame 42a and the second frame 42b are separated at the installation location of the inspection device 10, each can stand on its own, making it easy to position the inspection device 10 relative to the conveying device 50.

[0017] 2(b), when the main frame 42 is divided into a first frame 42a and a second frame 42b, a support frame 43 is attached to the upper surface of the first frame 42a, an X-direction guide of the X-axis unit 16a described above is attached to the upper surface of this support frame 43, and the imaging unit 20 is supported by the XY stage 16 including this X-direction guide. With this configuration, the inspection object 12 inside the through-hole 41, i.e., inside the inspection space of the inspection device 10, can be imaged from the Z direction to perform inspection. Furthermore, when the second frame 42b is attached to the first frame 42a, the support frame 43 is fixed to the second frame 42b, thereby fixing the first frame 42a and the second frame 42b.

[0018] In addition, if the range that can be imaged and inspected by the camera unit 21 (the range (Z-direction range) in which a focused image of the inspected object 12 can be captured by moving the camera unit 21 in the Z direction) is displayed on the X-direction side surface of the main frame 42 (first frame 42a and second frame 42b), the work of positioning the inspection device 10 of this embodiment relative to the conveying device 50 will be easier.

[0019] Furthermore, the inspection device 10 according to this embodiment is configured so that the cover 40 can be detachably attached to cover the main frame 42. This prevents an operator from coming into contact with the imaging unit 20 or the XY stage 16 that are operating during inspection, thereby improving safety. The cover 40 has an opening for the through-hole 41, and by changing the position and size of the opening depending on the height of the transport device 50, it is possible to prevent anything other than the inspected object 12 from entering the interior of the inspection device 10. Furthermore, by attaching a cover corresponding to the height of the transport device 50 to the lower portion of the opening formed in the cover 40 that is located below the transport device 50, safety can be further improved.

[0020] 3, the imaging unit 20 includes a camera unit 21 that captures an image from a direction perpendicular (Z direction) to the inspection surface (substrate surface) of the inspected object 12, an illumination unit 22, and a projection unit 23. In the inspection device 10 according to this embodiment, the camera unit 21, the illumination unit 22, and the projection unit 23 are configured as an integrated imaging unit 20. In this integrated imaging unit 20, the relative positions of the camera unit 21, the illumination unit 22, and the projection unit 23 may be fixed, or each unit may be configured to be relatively movable. Alternatively, the camera unit 21, the illumination unit 22, and the projection unit 23 may be separate units that are configured to be independently movable.

[0021] The camera unit 21 includes an imaging element that generates a two-dimensional image of the subject and an optical system (e.g., a lens) for focusing the image on the imaging element. The camera unit 21 is, for example, a CCD camera. The maximum field of view of the camera unit 21 may be smaller than the area where the object to be inspected is placed on the conveying device 50. In this case, the camera unit 21 divides the object to be inspected 12 into multiple regions, captures image data of each divided region (divided region image data), and stitches (combines) these image data to capture the entire object to be inspected 12. The control unit 30 controls the XY stage 16 so that the camera unit 21 moves to the next imaging position each time the camera unit 21 captures divided region image data. The control unit 30 combines the divided region image data obtained by the imaging unit 20 to generate overall image data of the object to be inspected 12.

[0022] Note that the camera unit 21 may include an imaging element that generates a one-dimensional image (a line-shaped image) instead of a two-dimensional imaging element. In this case, the entire image of the object under inspection 12 can be acquired by scanning the object under inspection 12 with the camera unit 21. Furthermore, the imaging unit 20 may include, in addition to the camera unit 21, a plurality of camera units that image the object under inspection 12 at angles different from that of the camera unit 21. By imaging the object under inspection 12 at angles different from that of the camera unit 21, areas that are shaded by components attached to the object under inspection 12 and cannot be imaged by the camera unit 21 can be inspected using image data captured at angles different from that of the camera unit 21.

[0023] The illumination unit 22 is configured to project illumination light onto the surface of the inspection object 12 for imaging by the camera unit 21. The illumination unit 22 includes one or more light sources that emit light of a wavelength or wavelength range selected from the wavelength range detectable by the imaging element of the camera unit 21. The illumination light is not limited to visible light, and ultraviolet light, X-rays, etc. may also be used. When multiple light sources are provided, each light source is configured to project light of a different wavelength (e.g., red, blue, and green) onto the surface of the inspection object 12 at a different projection angle.

[0024] The object under inspection 12 illuminated by the lighting unit 22 is imaged by the camera unit 21. The inspection device 10 determines the presence or absence of defects on the board of the object under inspection 12 (for example, whether components are present and properly arranged, whether there are any excess items, and whether the solder application state is good or bad) based on image data of the object under inspection 12 (this image data is referred to as "two-dimensional image data") obtained by illuminating and imaging the object under inspection 12 with the lighting unit 22 and a height map, which will be described later.

[0025] In the inspection device 10 according to this embodiment, the illumination unit 22 is a side illumination source that projects illumination light obliquely onto the inspection surface of the object under inspection 12, and in this embodiment, includes an upper light source 22a, a middle light source 22b, and a lower light source 22c. In the inspection device 10 according to this embodiment, the side illumination sources 22a, 22b, and 22c are each a ring illumination source that surrounds the optical axis of the camera unit 21 and is configured to project illumination light obliquely onto the inspection surface of the object under inspection 12. Each of these side illumination sources 22a, 22b, and 22c may be configured with multiple light sources arranged in a circular ring shape. Furthermore, the upper light source 22a, the middle light source 22b, and the lower light source 22c, which are side illumination sources, are each configured to project illumination light at different angles onto the inspection surface.

[0026] The projection unit 23 projects a pattern (e.g., illumination light with varying light intensity) onto the inspection surface of the object under test 12. The object under test 12 onto which the pattern is projected is imaged by the camera unit 21. The inspection device 10 creates a height map of the inspection surface of the object under test based on image data of the object under test 12 obtained by imaging (this image data is referred to as "pattern image data"). Here, the height map is data that contains height information of the object under test 12 (the three-dimensional shape of the object under test 12) for each pixel of the pattern image data. The control unit 30 detects local mismatches between the projected pattern and the pattern image data, and acquires height information for that portion based on the local mismatches. In other words, changes in the imaged pattern relative to the projected pattern correspond to changes in height on the inspection surface.

[0027] The projection pattern is preferably a one-dimensional stripe pattern in which different continuous intensities are periodically repeated. The projection unit 23 is arranged to project the stripe pattern obliquely onto the inspection surface of the inspection object 12. Discontinuities in height on the inspection surface of the inspection object 12 appear as pattern shifts in the stripe pattern image. Therefore, the height difference can be determined from the amount of pattern shift. For example, the control unit 30 creates a height map using the PMP (Phase Measurement Profilometry) method, which uses a stripe pattern whose brightness changes according to a sine curve. In the PMP method, the amount of shift in the stripe pattern corresponds to the phase difference of the sine curve.

[0028] The projection unit 23 includes a pattern forming device, a light source device for illuminating the pattern forming device, and an optical system for projecting a pattern (light transmitted through the pattern forming device) onto the inspection surface of the object under test 12. The pattern forming device may be, for example, a variable patterning device capable of dynamically generating a desired pattern, such as a liquid crystal display, or a fixed patterning device in which a pattern is fixedly formed on a substrate, such as a glass plate. When the pattern forming device is a fixed patterning device, it is preferable to provide a movement mechanism for moving the fixed patterning device or an adjustment mechanism in the optical system for pattern projection, thereby making the projection position of the pattern variable. Furthermore, the projection unit 23 may be configured to be able to switch between multiple fixed patterning devices having different patterns.

[0029] A plurality of projection units 23 may be provided around the camera unit 21. The plurality of projection units 23 are arranged so as to project patterns onto the inspection object 12 from different projection directions, respectively. In this way, it is possible to reduce the area on the inspection surface that is shaded due to height differences and onto which the pattern is not projected.

[0030] Furthermore, a plurality of sensors are disposed on each of the first frame 42a and the second frame 42b constituting the main frame 42 to detect the object under test 12 being carried into and out of the through-hole 41, which is the inspection space, by the transport device 50. Each of these sensors is configured to transmit a detection signal to the control unit 30.

[0031] First, a carry-in / carry-out sensor 17 is provided on each of the first frame 42a and the second frame 42b on the entrance and exit sides of the through-hole 41. Each carry-in / carry-out sensor 17 is composed of a light-emitting unit and a light-receiving unit that extend in the Z direction (up and down direction), with one unit attached to the first frame 42a and the other unit attached to the second frame 42b so that the transport device 50 is sandwiched between them when viewed from the X direction. This carry-in / carry-out sensor 17 is configured so that the light-emitting unit receives light that is emitted in the Y direction from the light-emitting unit. The light-emitting unit of the carry-in / carry-out sensor 17 is composed of a plurality of light sources arranged in the Z direction, and the light-receiving unit is composed of a plurality of light-receiving elements arranged in the Z direction. When the object under test 12 passes through the entrance or exit of the through-hole 41, the object under test 12 blocks at least a portion of the light emitted from the light-emitting unit of the carry-in / carry-out sensor 17, preventing the light from being received by the light-receiving unit, thereby detecting that the object under test 12 has passed through the entrance or exit of the through-hole 41. The inspection control unit 31 of the control unit 30 is configured not to perform inspection (not to move the imaging unit 20 by the XY stage 16) when the carry-in / carry-out sensor 17 detects the object under test 12 (or an object other than the object under test 12). It is desirable that the mounting position of the carry-in / carry-out sensor 17 relative to the first frame 42a and the second frame 42b be changeable according to the height of the conveyance device 50.

[0032] Additionally, within the through-hole 41, a camera-under sensor 18 is provided in each of the first frame 42a and the second frame 42b below the imaging unit 20. The camera-under sensor 18 is composed of a light-projecting unit and a light-receiving unit extending in the X direction (conveying direction). One is attached to the first frame 42a, and the other is attached to the second frame 42b, so that the conveying device 50 is sandwiched between them when viewed from the Z direction. The camera-under sensor 18 is configured so that the light-receiving unit receives light projected from the light-projecting unit in the Y direction. The light-projecting unit of the camera-under sensor 18 is composed of multiple light sources arranged in the X direction, and the light-receiving unit is composed of multiple light-receiving elements arranged in the X direction. These units detect whether the inspected object 12 is located at a predetermined height below the camera unit 21. As shown in FIG. 4, the camera unit 21 is movable in the Z direction along the Z-direction guide of the Z-axis unit 16c (movable range in FIG. 4). Therefore, even when the camera unit 21 is positioned at the bottom of the Z-direction guide, a safety area is provided that the object under inspection 12 does not enter so as to avoid contact with the object under inspection 12 located within the through-hole 41 (inspection space). Therefore, the camera-below sensor 18 is configured to detect the object under inspection 12 located within a safety area equal to or greater than a predetermined height. That is, when the top of the object under inspection 12 is located within the through-hole 41 at a position equal to or greater than the predetermined height (within the safety area), the object under inspection 12 blocks at least a portion of the light emitted from the light-emitting unit of the camera-below sensor 18, preventing the light from being received by the light-receiving unit. This makes it possible to detect that the object under inspection 12 is located at a position equal to or greater than the predetermined height. The inspection control unit 31 of the control unit 30 is configured not to perform inspection (not to move the imaging unit 20 by the XY stage 16) when the camera-below sensor 18 detects the object under inspection 12 (or an object other than the object under inspection 12).

[0033] FIG. 5 shows the light beam LB projected from the light-projecting unit of the camera-below sensor 18 and received by the light-receiving unit. In the inspection device 10 according to this embodiment, the direction in which the light beam LB extends (the projection direction) is not perpendicular to the direction in which the object under test 12 is transported (the X direction), but is projected at an angle (at a predetermined angle with respect to the Y direction) relative to the perpendicular direction (the Y direction). In other words, the projection direction of the light beam LB is not perpendicular to the X direction in which the object under test 12 is transported by the transport device 50. This configuration makes the width W' of the light beam LB projected by the camera-below sensor 18 in the direction in which the object under test 12 passes (the width in which the object under test 12 can be detected) wider than the width W of the light beam LB projected by the camera-below sensor 18, making it easier for the camera-below sensor 18 to detect the object under test 12. This improves the detection accuracy for the object under test 12 located higher than the predetermined position, preventing the XY stage 16 from operating the imaging unit 20 and coming into contact with the object under test 12. In particular, since the inspection device 10 according to this embodiment is arranged relative to a conveying device 50 that is independent of the inspection device 10, safety can be improved by making it easier to detect that a portion of the inspected object 12 is within the safety area.

[0034] The control unit 30 shown in Figure 3 controls the entire device, and is realized as hardware by the CPU, memory, and other LSIs of any computer, and as software by programs loaded into memory, but here it is depicted as a functional block realized by the cooperation of these. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various ways by hardware alone, software alone, or a combination of both.

[0035] FIG. 3 shows an example of the configuration of the control unit 30. The control unit 30 includes an inspection control unit 31 and a memory 35, which is a storage unit. The inspection control unit 31 includes an image processing unit 32, an inspection information processing unit 33, and an inspection unit 34. The image processing unit 32 includes an image capturing processing unit 32a and a height measurement unit 32b. The inspection device 10 also includes an input unit 36 ​​for receiving input from a user or another device, and an output unit 37 for outputting information related to the inspection. The input unit 36 ​​and the output unit 37 are each connected to the control unit 30. The input unit 36 ​​includes, for example, input means such as a mouse or keyboard for receiving input from a user, and communication means for communicating with other devices. The output unit 37 includes known output means such as a display or printer.

[0036] As a preprocessing step for creating a height map, the inspection control unit 31 controls the relative movement of the imaging unit 20 and the inspection table 14 while projecting a pattern onto the object under inspection 12 from the projection unit 23 using the imaging processing unit 32a of the image processing unit 32, thereby dividing and sequentially capturing pattern images of the object under inspection 12. The projected pattern is preferably a stripe pattern whose brightness changes according to a sine curve based on the PMP method. The inspection control unit 31 combines the captured divided area images to generate pattern image data for the entire inspection surface of the object under inspection 12. The inspection control unit 31 stores the pattern image data in the memory 35. Note that pattern image data may be generated for only a portion of the inspection surface of the object under inspection 12, rather than for the entire inspection surface.

[0037] The height measurement unit 32b creates a height map of the entire inspection surface of the object under test 12 based on the image of the pattern in the pattern image data. The height measurement unit 32b first calculates the local phase difference between the pattern image data and the reference pattern image data for the entire image data, thereby calculating a phase difference map of the inspection surface of the object under test 12. Here, the "reference pattern image data" refers to image data in which a pattern is projected onto a reference plane by the projection unit 23 (i.e., image data acquired by the camera unit 21 in a state in which a pattern generated by a pattern forming device built into the projection unit 23 is projected onto the reference plane). The height measurement unit 32b creates a height map of the object under test 12 based on a reference plane serving as a reference for height measurement and the phase difference map. The reference plane is, for example, the surface of the electronic circuit board to be inspected. The reference plane does not necessarily have to be flat, but may be a curved surface that reflects deformation such as warpage of the board.

[0038] Specifically, the height measurement unit 32b determines the phase difference of the stripe pattern between each pixel of the pattern image data and the corresponding pixel of the reference pattern image data. The height measurement unit 32b converts the phase difference into height information. This is because the distance from the projection unit 23 varies depending on the position on the inspection surface, so even if the stripe width of the reference pattern is constant, the stripe width changes from one end of the pattern projection area on the inspection surface to the other. The height measurement unit 32b obtains height information from the reference plane based on the converted height information and the reference plane, and creates a height map of the inspection object 12.

[0039] The image processing unit 32 of the inspection control unit 31 may create an image of the object under test 12 having a height distribution by associating height information contained in the height map of the object under test 12 with each pixel of the two-dimensional image data of the object under test 12. The image processing unit 32 may also perform a three-dimensional modeling display of the object under test 12 based on the object under test image data with height distribution. The image processing unit 32 may also superimpose the height distribution on the two-dimensional image data of the object under test 12 and display it on the output unit 37. For example, the two-dimensional image data may be displayed in different colors depending on the height distribution.

[0040] The inspection control unit 31 is configured to execute various control processes for inspection based on input from the input unit 36 ​​and inspection-related information stored in the memory 35. The inspection-related information includes inspection information such as two-dimensional image data of the object 12 to be inspected, a height map of the object 12 to be inspected (calculated from the pattern image data as described above), and substrate inspection information. The inspection unit 34 executes inspection based on the created substrate inspection information and the two-dimensional image data and height map of the object 12 to be inspected.

[0041] Board inspection information is created for each type of board and is used in rule-based inspections. Board inspection information is a collection of inspection information for components arranged on the board, their positions, and each solder applied to the board. The inspection information for each component or solder includes the inspection items required for that component or solder, the inspection window, which is the inspection area on the image for each inspection item, and the inspection criteria that serve as the basis for determining the placement and pass / fail for each inspection item. One or more inspection windows are set for each inspection item. For example, in an inspection item that determines the pass / fail of solder application, typically, the same number of inspection windows as the number of solder application areas on the component are set in a layout that corresponds to the layout of the solder application areas. Furthermore, for inspection items that use image data that has undergone predetermined image processing on two-dimensional image data of the inspected object 12, the details of that image processing are also included in the inspection information.

[0042] When multiple inspection rules are applied to one inspection object (for example, each pin of a semiconductor chip), one inspection window is set for that inspection object for each inspection rule. For example, when four inspection rules, "position shift inspection," "floating inspection," "polarity inspection," and "solder inspection," are applied to the tips of each pin of a semiconductor chip having multiple pins, four inspection windows corresponding to these inspection rules are set.

[0043] The inspection information processing unit 33 sets each item of inspection information to suit the board in the board inspection information creation process. For example, the inspection information processing unit 33 automatically sets the position and size of each inspection window for each inspection item so that it matches the solder layout of the board. The inspection information processing unit 33 may be configured to accept user input for some items of the inspection information. For example, the inspection information processing unit 33 may be configured to accept tuning of the inspection criteria by the user. The inspection criteria may be set using height information.

[0044] Furthermore, prior to the inspection, the inspection information processing unit 33 creates substrate inspection information using the two-dimensional image data of the object to be inspected 12, which is the above-mentioned substrate entire surface image data, and a height map (created from the pattern image data).

[0045] As described above, the inspection unit 34 inspects the object 12 under inspection based on the created substrate inspection information (inspection information) and the two-dimensional image data and height map of the object 12 under inspection to be inspected.

[0046] Here, in the inspection device 10 according to this embodiment, the transport of the object to be inspected 12 into the inspection device 10, and the fixing and transporting thereof during inspection (when taking an image) are performed using a transport device 50 installed separately from the inspection device 10. Therefore, the inspection control section 31 of the control unit 30 is configured to control the transport device 50 by the plant control device 52, which controls the operation of the transport device 50, by transmitting and receiving control signals to and from the plant control device 52, for the transport of the object to be inspected 12 into the inspection device 10, and the fixing and transporting thereof during inspection (when taking an image).

[0047] Next, the inspection process of the object under inspection 12 by the inspection apparatus 10 according to this embodiment will be described with reference to FIG. 6 . When the inspection starts, the inspection control unit 31 of the control unit 30 controls the operation of the transport device 50 via the plant control device 52, and transports the substrate, which is the object under inspection 12 to be inspected, to the inspection position of the inspection apparatus 10 (step 100). As described above, the inspection control unit 31 detects that the object under inspection 12 has been transported to the inspection position by detecting that the object under inspection 12 has passed through the transport-in / transport-out sensor 17 located upstream of the through-hole 41. Note that if the transport-in / transport-out sensor 17 does not detect the transport of the object under inspection 12, the inspection control unit 31 does not perform the subsequent inspection process (does not move the imaging unit 20). Furthermore, as described above, if the under-camera sensor 18 detects that a portion of the object under inspection 12 is within the safety zone, the inspection control unit 31 also does not perform the subsequent inspection process (does not move the imaging unit 20). Then, the inspection control unit 31 causes the imaging processing unit 32a of the image processing unit 32 to image the substrate, which is the object 12, carried into the inspection position, and acquires two-dimensional image data and pattern image data of the object 12 (step 102). The acquired two-dimensional image data and pattern image data are stored in the memory 35. The inspection control unit 31 also causes the height measurement unit 32b of the image processing unit 32 to calculate height information using the acquired pattern image data and create a height map (step S104). This height map is also stored in the memory 35.

[0048] Next, the inspection control unit 31 uses the two-dimensional image data and height map acquired by the above processing to inspect the object under inspection 12 using the inspection unit 34. Specifically, one of the inspection windows set for the object under inspection 12 is selected (step S106), and inspection processing is performed for the selected inspection window (step S108).

[0049] In the inspection process S108, the inspection unit 34 reads the inspection information set in the currently selected inspection window, i.e., the board inspection information, from the memory 35. Then, based on this board inspection information, the inspection unit 34 performs an inspection using a rule-based inspection method on the two-dimensional image data and height map in the currently selected inspection window, determines whether the inspection is good or bad based on the inspection results, stores the result (good or bad) in the memory 35 as the inspection result for the currently selected inspection window, and ends the inspection process S108.

[0050] When the inspection process S108 is completed, the inspection unit 34 determines whether all inspection windows have been selected (step S110). If it determines that an unselected inspection window remains (step S110: N), the inspection unit 34 returns to step S106, selects the next inspection window, and repeats the subsequent processes. On the other hand, if it determines that all inspection windows have been selected (step S110: Y), the inspection unit 34 determines whether the inspection results of all inspection windows have been judged to be good (step S112). If it determines that the inspection results of all inspection windows are good (step S112: Y), the inspection unit 34 judges the currently inspected object 12 to be good and stores this in the memory 35 (step S114). On the other hand, if it determines that at least one inspection window has been judged to be bad (step S112: N), the inspection unit 34 judges the currently inspected object 12 to be bad and stores this in the memory 35 together with information on the inspection window judged to be bad (step S116).

[0051] Finally, the inspection control unit 31 controls the operation of the transport device 50 via the plant control device 52 to remove the object 12 from the inspection position (step S118), thereby completing the inspection of one object 12. The inspection control unit 31 detects that the object 12 has been removed by detecting that the object 12 has passed through the carry-in / carry-out sensor 17 located downstream of the through-hole 41. Furthermore, when there is a next object 12 to be inspected, the inspection control unit 31 executes the inspection from step S100, repeating the process of carrying in, capturing an image, inspecting, and carrying out. Here, after the image of the object 12 to be inspected in step S102 is completed, the inspection control unit 31 executes the process from step S104 onward, removes the object 12 from the inspection position, and carries the next object 12 to the inspection position and captures an image. This allows the inspection of the previous object 12 and the capturing of the next object 12 to be inspected to be performed in parallel, thereby shortening the takt time required for the inspection.

[0052] As described above, the inspection device 10 according to this embodiment uses image data (two-dimensional image data or pattern image data) obtained by capturing an image of the object under inspection 12 with the camera unit 21 of the imaging unit 20 to inspect whether components are present or not on the surface of the object under inspection 12, whether their placement is appropriate, whether there are any excess items, and whether the solder condition is good. Therefore, a certain level of resolution is required for the image data, and therefore the imaging magnification of the camera unit 21 is high. As a result, the area that can be captured in one imaging (observation area FOV) is small. Therefore, the inspection device 10 is configured to capture the entire object under inspection 12 by dividing it into multiple partial images (divided area images or divided area image data), and then paste (combine) these divided area images together to form a single image capturing the entire object under inspection 12 for inspection.

[0053] Generally, an object under test 12 such as an electronic circuit board has distortion in the board, and the surface (board surface or inspection target surface) of the object under test 12 is not flat. Furthermore, in the inspection device 10 according to this embodiment, the transport device 50 that transports the object under test 12 is installed separately from the inspection device 10, and it is not guaranteed that the board mounting surface of the transport device 50 is flat or that the ground surface of the transport device 50 is parallel to the board mounting surface. Therefore, when a process of joining (combining) divided area images (divided area image data) is performed, there is a problem that the rate of erroneous determinations near the boundaries of the divided area images increases.

[0054] FIG. 7 is a conceptual diagram illustrating the process from acquiring divided-area images to correcting and combining them for height and tilt to acquiring an image of the entire object under test 12. Here, the object under test 12 is described as an electronic circuit board 90 with components 92 mounted on the upper surface of the board 91. As shown in FIG. 7( a), the board 91 of the electronic circuit board 90 is distorted due to various factors, such as the board's own warping and the component placement. The electronic circuit board 90 is divided into multiple areas (nine in FIG. 7) according to the field of view (FOV) of the camera unit 21 and photographed. The image processing unit 32 calculates a plane (conveniently referred to as an "FOV plane") representing the board surface for each divided area. At this time, the FOV planes of each divided area each have different heights and tilts, and FIG. 7( b) shows the result of joining these FOV planes together. However, because the height of the board surface differs for each divided area, accurate height measurement cannot be performed for the entire electronic circuit board, assuming the height of the board surface to be zero. Therefore, the height data within each divided area is corrected so that the FOV plane of each divided area becomes a horizontal plane with zero height, and the data of the divided areas is combined to produce the image shown in Figure 7(c). This generates an image of the circuit board in which the influence of distortion of the board 91 is suppressed.

[0055] However, in the case of thin substrates with low rigidity, substrates with slits, or substrates subjected to large localized loads, the substrate may bend into a complex shape. Furthermore, an uneven substrate mounting surface of the transport device 50 may also cause distortion of the substrate. In such cases, the FOV plane may not be smoothly connected, resulting in steps between adjacent divided regions. Correcting this condition may result in elevated portions near the boundaries of the divided regions. Figure 8 illustrates this situation. Figures 8(a) and 8(b) are schematic diagrams showing the cross section of an electronic circuit board 90, with the board 91 of the electronic circuit board 90 indicated by a solid line, the boundaries of the divided regions indicated by dotted lines, and a horizontal plane of zero height (a plane parallel to the imaging surface of the camera unit 21) indicated by a two-dot chain line. Figure 8(c) is a diagram equivalent to Figure 7(b).

[0056] As shown in FIG. 8A , when the substrate 91 of the electronic circuit board 90 is bent in a curved, uneven shape, the FOV plane of each divided region is obtained as shown by the dashed-dotted line. In this case, among the obtained FOV planes FVa, FVb, and FVc of the divided regions, there is almost no step at the boundary between the FOV plane FVb of the second divided region from the left and the FOV plane FVc of the third divided region from the left. However, there is a large step G at the boundary between the FOV plane FVa of the first divided region from the left and the FOV plane FVb of the second divided region from the left. Therefore, if the FOV planes with the step G between the divided regions are joined as they are, the result will be as shown in FIG. 8C .

[0057] Figure 8(b) shows a situation where the heights of each part in each divided region are corrected and combined so that the FOV planes FVa, FVb, and FVc shown in Figure 8(a), which have different heights and inclinations, become a horizontal plane FV of zero height. In this case, a step G appears between the first board portion 91a from the left and the second board portion 91b from the left, where there was a step between the FOV planes, resulting in discontinuity in height on both sides of this step. Therefore, the left end of board portion 91b, which was significantly raised by this correction during combination, has a height relative to the zero-height board plane FV, which could be erroneously detected as an excess item. Furthermore, with conventional methods for combining divided region images, if one excess item exists across divided regions, it could be erroneously detected as multiple excess items.

[0058] A method for combining divided area images to solve the problems that occur when combining divided area images will now be described. In this method for combining divided area images, a plurality of distortion observation points (DOPs) are set in advance within each divided area (field of view (FOV)) of the electronic circuit board 90. The distortion observation points (hereinafter referred to as "DOPs") are observation points that define the height of the board surface when combining images of the divided areas. Figure 9 shows an example of the arrangement of DOPs across the entire electronic circuit board when four DOPs are automatically allocated and evenly positioned within each divided area of ​​the electronic circuit board 90.

[0059] The height of each DOP can be determined from the divided area image captured for each divided area. For example, as described above, the FOV plane can be determined for each divided area, and the height of the FOV plane at the DOP position can be used as the height of that DOP. Alternatively, when the DOP position is determined to be the substrate surface from the height map of the divided area image captured for each divided area, that height can be used as the height of the DOP.

[0060] For the DOPs whose heights have been calculated in this way, adjacent DOPs are connected by straight lines to form triangular planes. At this time, two triangular planes are formed in the center of the divided region, and many (14 in the illustrated configuration example) triangular planes connecting to adjacent divided regions are formed around them. That is, these triangular planes (referred to as "DOP planes" for convenience) are formed continuously throughout the interior and exterior of each divided region. The height and inclination of each DOP plane can be calculated in the same way as for the FOV plane, and the height of each part within the region is corrected based on the calculated height and inclination of the DOP plane. By combining these, an image of the entire electronic circuit board is generated.

[0061] 10A and 10B are explanatory diagrams for explaining the above situation, and are conceptual diagrams that schematically show a cross section of the electronic circuit board 90 corresponding to the above-mentioned FIGS. 8A and 8B. The board 91 of the electronic circuit board 90 is shown by a solid line, the boundaries of the divided regions (joints of the FOV) are shown by dotted lines, and the setting position of the DOP and the horizontal plane of zero height are shown by two-dot chain lines.

[0062] 10A, when the substrate 91 of the electronic circuit board 90 is bent in a curved, uneven shape, the DOP planes of each divided region are determined as shown by the dashed-dotted lines. As described above, the DOP planes (DP1 to DP7) are formed continuously throughout the interior and exterior of each divided region, and the boundary between the first divided region from the left and the second divided region from the left, where the step G occurred on the FOV plane, is connected by a DOP plane DP3 formed by connecting the DOPs provided within each divided region. The boundary between the second divided region from the left and the third divided region from the left is similar, and is connected by a DOP plane DP5.

[0063] 10B, when the height information of each divided area is corrected so that the DOP surfaces DP1 to DP7 become horizontal planes with a height of zero, the height of each part of the electronic circuit board 90 after correction does not have any steps, including at the boundaries between the divided areas. Therefore, by generating an entire image of the electronic circuit board 90 using the above-mentioned method for combining divided area images, acquiring the generated entire image of the electronic circuit board 90, and performing a board inspection, it is possible to inspect with high precision whether components are present and properly positioned, whether there are any excess items, and whether the solder condition is good, even if the divided area images are combined to generate an entire image, since the electronic circuit board is relatively large.

[0064] In the above description, an example was given in which DOPs were automatically allocated and evenly spaced based on the divided areas of the electronic circuit board 90. However, DOPs can also be set by other methods. For example, as an example of another method for setting DOPs, a method in which the operator sets the DOPs himself will be exemplified. In this case, the operator retrieves an image of the electronic circuit board stored as board data in the memory 35, displays it on the display, and, while appropriately using the image enlargement function, selects an area where the board surface is exposed, sets the DOP, and stores it. An image of the electronic circuit board 90 with DOPs set in this manner is shown in FIG. 11. Once the DOPs have been set, triangles connecting adjacent DOPs are automatically created. The intersections of each triangle in the figure represent the DOPs arbitrarily set by the operator.

[0065] With this setting method, the DOP position is a portion where the board surface is exposed, so the height of the image captured by the camera unit 21 can be used as the height of the DOP position as is. In other words, there is no need to perform processing such as finding the FOV plane from the image captured by the camera unit 21 and calculating the height of the DOP position. Furthermore, since the DOP can be set at an appropriate position depending on the mounting status of components on the electronic circuit board (for example, by setting DOPs at a high density in an area where bending is expected), it is possible to meticulously correct distortion of the board and synthesize images of the divided areas, thereby obtaining a high-precision image of the entire electronic circuit board.

[0066] In order to accurately join the divided area images using the method described above, it is necessary to adjust the XY stage 16 that moves the imaging unit 20 of the inspection device 10 to eliminate assembly errors, etc. For example, in the XY stage 16 that moves the imaging unit 20, which images the electronic circuit board (the object under test 12) and acquires image data, relative to the object under test 12, if there is an assembly error in the X-axis unit 16a, Y-axis unit 16b, and Z-axis unit 16c that make up the XY stage 16, highly accurate measurement results cannot be obtained. Therefore, in the inspection device 10 according to this embodiment, assembly errors in the XY stage 16 and the like are adjusted (calibrated) using a reference jig.

[0067] 12, the reference jig 60 is configured to include a reference plate 61 on which a flat surface (reference surface) 61a with guaranteed accuracy is formed, a base 62 attached to the underside of the reference plate 61, and two handles 63 attached to the base 62. The reference surface 61a of the reference plate 61 is provided with a first reference portion 61b having grid lines whose positions and lengths are drawn with high precision, and a second reference portion 61c having a plurality of cylinders of different heights whose positions and heights are highly accurate.

[0068] The first reference portion 61b is used to measure distortion of the X-axis unit 16a, Y-axis unit 16b, and Z-axis unit 16c of the XY stage 16 from the positions of the acquired image data (the positions of the grid lines or their intersections) and the position of the camera unit 21 by moving the imaging unit 20 using the control unit 30 and capturing an image of the first reference portion 61b with the camera unit 21. This allows for adjustment of distortion in the machine coordinate system consisting of the X-axis unit 16a, Y-axis unit 16b, and Z-axis unit 16c. Furthermore, the relationship between the position of the camera unit 21 in the Z direction and the imaging magnification can be adjusted from the image data captured of the first reference portion 61b. Furthermore, the second reference portion 61c is captured by the camera unit 21 with a pattern projected by the projection unit 23, and adjustments are made so that accurate height information can be calculated from the captured image data based on information about a cylinder provided on the second reference portion 61c, whose height is known.

[0069] Even if the reference jig 60 is placed on the substrate mounting surface of the transport device 50, the height and flatness of the transport device 50 are not guaranteed, and accurate adjustment (calibration) is not possible. Therefore, in the inspection device 10 according to this embodiment, the reference jig 60 is configured to be detachably attached to the support frame 43 that holds the imaging unit 20 via the XY stage 16. The support frame 43 has a rectangular shape when viewed from the Z direction and is composed of frame members that define the four sides of this rectangle. Specifically, as shown in FIGS. 12( a) and 12(b), the support frame 43 is composed of frame members 43a and 43b that extend in the Y direction when attached to the main frame 42, and frame members 43c and 43d that extend in the X direction. The lower surfaces of the frame members 43c and 43d are attached to the upper surface of the main frame 42, and the X-direction guide of the X-axis unit 16a that constitutes the XY frame 16 is attached to the upper surfaces of the frame members 43c and 43d. As described above, the main frame 42 is composed of a first frame 42a and a second frame 42b, and the frame member 43a of the support frame 43 is attached to the upper surface of the outer edge (the edge extending in the X direction) of the second frame 42b.

[0070] The support frame 43 also has a support member 43e extending in the Y direction so as to connect the lower surfaces of the two frame members 43c and 43d extending in the X direction. The imaging unit 20 is configured to image the inspection object 12 placed on the conveying device 50 through an opening 43g surrounded by the frame members 43a, 43c, and 43d and the support member 43e. A plate-shaped support portion 43f is formed on the lower surface of the frame member 43a, protruding inward (toward the support member 43e) so as to face the support member 43e. The upper surfaces of the support member 43e and the support portion 43f are located on the same plane.

[0071] As shown in FIG. 12C , the X-direction length of the base 62 of the reference jig 60 is approximately the same as the X-direction length of the inner side between the support portions 43f and the support members 43e. The X-direction length of the reference plate 61 is longer than the X-direction length of the base 62, and the reference plate 61 is configured to protrude from the base 62 at both ends in the X direction. Therefore, when the handle 63 of the reference jig 60 is held and the base 62 is inserted into the opening 43g from above the support frame 43, the lower surfaces of both ends in the X direction of the reference plate 61 come into contact with the upper surfaces of the support members 43e and the support portions 43f, and the reference jig 60 is supported by the support frame 43. In FIG. 4 , the position of the reference surface of the reference jig 60 is shown as the calibration height plane (the plane at the calibration height where the reference surface of the reference jig 60 is located). As such, the reference plane is within the imaging range of the imaging unit 20 (camera unit 21).

[0072] As shown in FIG. 13 , two pins 43h aligned in the Y direction are formed on the top surface of the support member 43e, and recesses 61d aligned with the pins 43h are formed on the end of the reference plate 61 of the reference jig 60 facing the support member 43e. When the reference jig 60 is attached to the support frame 43, the pins 43h are inserted into the recesses 61d, which facilitates positioning of the reference jig 60 relative to the support frame 43. Two cap screws 43h aligned in the Y direction are provided on the end of the reference jig 60 facing the support portion 43f. Turning the cap screws 43h causes the member attached to the cap screws 43h to abut against the side surface of the support portion 43f of the support frame 43. Further turning of the cap screws 43h pushes the reference jig 60 (base 62) in the X direction (toward the support member 43e). Therefore, the side surface of the base 62 on the support member 43 e side abuts against the side surface of the support member 43 e , so that the reference jig 60 can be fixed to the support frame 43 .

[0073] 2, the reference jig 60 can be attached to and detached from the support frame 43 from the outside in the Y direction of the main frame 42 (second frame 42b) of the inspection apparatus 10. Furthermore, the reference jig 60 can be fixed to and released from the support frame 43 by operating cap screws 43h located near the outside in the Y direction of the main frame 42. Therefore, an operator can attach and detach the reference jig 60 from the outside of the inspection apparatus 10 without entering the interior of the inspection apparatus 10, and this operation can be performed safely.

[0074] Furthermore, since the imaging unit 20 is fixed to the support frame 43, by attaching the reference jig 60 to the support frame 43, the positions of the imaging unit 20 and the reference jig 60 become known, and accurate adjustment (calibration) can be performed regardless of the conveying device 50 on which this inspection device 10 is placed.

[0075] It goes without saying that the above embodiments do not limit the invention described in the claims, and that not all of the combinations of the characteristic features described in the embodiments are necessarily essential features of the solution.

[0076] REFERENCE SIGNS LIST 10 Inspection device 12 Inspected object 18 Sensor under camera 20 Imaging unit (imaging section) 30 Control unit (control section) 50 Conveying device 60 Reference jig (jig)

Claims

1. An inspection device that is arranged with respect to a conveying device and inspects a test object carried in by the conveying device, the inspection device comprising: an imaging unit that moves relative to the test object and images the test object; and a control unit that controls the operation of the imaging unit and acquires image data imaged by the imaging unit, wherein the control unit includes: an imaging processing unit that performs image processing on a plurality of image data obtained by dividing and imaging the test object with the imaging unit; and a height measurement unit that calculates a three-dimensional shape of the test object based on the image data, and is configured to generate overall image data of the test object by stitching together the plurality of image data based on the three-dimensional shape calculated by the height measurement unit, and to inspect the test object based on the overall image data, and the control unit is an inspection device that performs calibration using a jig arranged at a position different from the substrate placement surface of the conveying device.

2. The inspection device according to claim 1, wherein the jig is arranged at a predetermined calibration height, and the control unit inspects the test object by imaging the test object within an imaging range including the calibration height with the imaging unit.

3. The inspection device according to claim 2, further comprising a main frame that supports the imaging unit, wherein the jig is detachable from the main frame.

4. The inspection device according to any one of claims 1 to 3, wherein the control unit corrects the inspection target surface of the test object to be horizontal with the imaging surface of the imaging unit including the distortion of the substrate placement surface of the conveying device, and restores the three-dimensional shape of the entire test object.

5. The inspection device according to claim 1, wherein a predetermined safety region is provided on the conveying device side of the imaging unit, and the inspection device has a camera lower sensor that detects that at least a part of the test object carried in by the conveying device is within the safety region, the camera lower sensor including a light projecting unit that projects light and a light receiving unit that receives the light, the light projecting unit and the light receiving unit being arranged such that the light has a predetermined angle with respect to a direction orthogonal to the direction in which the test object is conveyed by the conveying device.

Images