JP2021047047A - Imaging device, method for acquiring image, and inspection device - Google Patents

Abstract

To take an image of a dome-illuminated work-piece desirably.SOLUTION: An imaging unit includes a first camera for taking an image of an imaging target region through a first through-hole; and a second camera for taking an image of an imaging target region through the second through-hole. The second through-hole is provided in a first mirror reflection symmetrical area symmetrical to the first through-hole in terms of mirror reflection with respect to the imaging target region, in a first virtual flat surface including the first through-hole and the imaging target region, and in a position distant from a first cross line with the inner periphery surface. The first through-hole is provided in a second mirror reflection symmetrical area symmetrical to the second through-hole in terms of mirror reflection with respect to the imaging target region, in a second virtual flat surface including the second through-hole and the imaging target region, and in a position distant from a second cross line with the inner periphery surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image pickup device that images a work illuminated by a so-called dome illumination method, an image acquisition method that acquires an image of a work using the image pickup device, and an inspection device that inspects a work based on the image. ..

An inspection technique for inspecting a work such as an industrial part for defects such as scratches has been proposed (Patent Document 1). In the apparatus described in Patent Document 1, the light emitted from the light source is diffusely reflected on the inner surface of the dome-shaped reflector (corresponding to the "cover member" of the present invention) to irradiate the work, and the ceiling portion of the dome-shaped reflector is provided. The work is imaged by the imaging means through the photographing window (corresponding to the “through hole” of the present invention) provided in the above, and the image of the work is acquired. Then, the work is inspected based on the image. Further, as a device for imaging a work by dome illumination, for example, there is one described in Patent Document 2. In this device, a plurality of light emitting elements are dispersedly arranged on a dome having a dome-shaped inner peripheral surface facing the work (corresponding to the "cover member" of the present invention), and the work is illuminated from various directions. At the same time, the imaging means images the work through an observation window (corresponding to the “through hole” of the present invention) provided on the ceiling of the dome to acquire an image.

JP-A-2017-207380 JP-A-2019-86361

In the apparatus described in Patent Documents 1 and 2, a work is imaged by one imaging means. Therefore, a blind spot is generated depending on the shape of the work. Therefore, it is conceivable to further add an imaging means to the devices described in Patent Document 1 and Patent Document 2. In other words, a shooting window and an observation window are added to the dome-shaped reflector and the dome, and the work is imaged from an oblique direction or from the side through the shooting window to obtain a better image of the work. can do.

However, the following problems may occur depending on the position where the photographing window or the like is provided. That is, when the work is imaged by one of the imaging means due to the inclination of the work, a photographing window or the like for the other imaging means may be reflected. Diffuse reflection of the emitted light is not performed in the region of the dome-shaped reflector provided with the photographing window. Further, a light emitting element cannot be arranged in the observation window of the dome. Therefore, in the image acquired by one of the imaging means, the portion corresponding to the shooting window or the like is partially darkened, and the image quality is deteriorated. As a result, it becomes difficult to inspect the workpiece with high accuracy.

The present invention has been made in view of the above problems, and includes an imaging device capable of satisfactorily imaging a work lit by a dome, an image acquisition method capable of satisfactorily acquiring an image of a work under dome illumination, and a work. An object of the present invention is to provide an inspection device capable of inspecting with high accuracy.

A first aspect of the present invention is an imaging device, which has a work holding portion for holding a work, a dome-shaped inner peripheral surface facing the work held by the work holding portion, and a first through hole and a first through hole. 2 A cover member provided with through holes penetrating the inner peripheral surface and the outer peripheral surface, and an illuminating portion that illuminates the work by irradiating the work held by the work holding portion from each portion of the inner peripheral surface with illumination light. The image pickup unit includes an image pickup unit that images the imaged region of the work illuminated by the illumination unit, and the image pickup unit includes a first camera that images the imaged area through the first through hole and a second through hole for the imaged area. The second through hole has a second camera that takes an image through the image, and the second through hole captures the first through hole, the first through hole, and the imaged area that are mirror-symmetrical to the first through hole with respect to the imaged area. The first through hole is provided at a position away from the first intersection line between the including first virtual plane and the inner peripheral surface, and the first through hole is a second reflection symmetry that is mirror-symmetric with the second through hole with respect to the imaged region. It is characterized in that it is provided at a position away from the second intersection line between the second virtual plane including the region, the second through hole, and the imaged region and the inner peripheral surface.

A second aspect of the present invention is an image acquisition method for acquiring an image of a work using the image pickup device, in which the work is imaged by the image pickup unit while the work is rotated at least once by the rotation drive unit. It is characterized by acquiring an image of the work.

Further, a third aspect of the present invention is an inspection device, which is an inspection device that inspects a work based on an image captured by the image pickup unit while the work is rotated at least once by the image pickup device and the rotation drive unit. It is characterized by having.

In the invention configured as described above, the imaged region of the work is imaged by the first camera through the first through hole. Therefore, the first virtual plane including the first through-hole and the first mirror-symmetrical region, the first through-hole, and the image-to-image region, which are mirror-symmetrical to the image-to-image region, and the inner peripheral surface of the cover member. When the second through hole for the second camera is hooked on the line of intersection, the portion corresponding to the hooked portion of the image acquired by the first camera is partially darkened, and the image quality is deteriorated. However, in the present invention, the second through hole is arranged away from the first line of intersection. Therefore, deterioration of image quality is effectively prevented. This point is the same on the second camera side.

Further, in the above invention, the case where the imaging unit is composed of two cameras has been described, but the same is basically the case when the imaging unit is composed of three or more cameras.

As described above, according to the present invention, in an imaging device that performs dome illumination, a through hole for a camera provided in a cover member for imaging an imaged region, and the through hole with respect to the imaged region. Through holes for other cameras are arranged at positions away from the intersection line between the virtual plane including the reflection-symmetrical reflection-symmetrical region and the image-image region and the inner peripheral surface of the cover member. Therefore, it is possible to satisfactorily image the work illuminated by the dome without being affected by the through holes for other cameras. Further, by using the image pickup device, an image of the work can be obtained satisfactorily. Further, the workpiece can be inspected with high accuracy.

It is a figure which shows the whole structure of the inspection apparatus equipped with one Embodiment of the image pickup apparatus which concerns on this invention. It is the figure which looked at the cover member provided in the image pickup apparatus from above. It is a figure which shows typically the attached state of the 1st camera and a light emitting element with respect to a cover member. It is a figure which shows typically the attached state of the 2nd camera and a light emitting element with respect to a cover member. It is a figure which shows typically the attached state of the 3rd camera and a light emitting element with respect to a cover member. It is a flowchart which shows the inspection operation of the workpiece by the inspection apparatus shown in FIG.

FIG. 1 is a diagram showing an overall configuration of an inspection device equipped with an embodiment of an imaging device according to the present invention. Further, FIG. 2 is a view of the cover member provided in the image pickup apparatus as viewed from above. The inspection device 1 controls each part of the image pickup device 2 and the image pickup device 2 that images the work W having a shape that is rotationally symmetric about the axis of rotational symmetry (reference numeral AX in FIGS. 3 to 5), and the image pickup device 2 controls the image pickup device 2. It is provided with a control device 3 that inspects the work W based on the acquired image of the work W. In order to clarify the positional relationship of each part of the device, the XYZ right-angled coordinate axes are shown in FIG. That is, the X direction for moving the work W in the horizontal direction, the horizontal direction Y orthogonal to the X direction, and the vertical direction Z are shown.

The image pickup apparatus 2 includes an XY manual stage 21, a stage drive mechanism 22, a cover member 23, an image pickup section 24, and an illumination section (reference numerals 25 in FIGS. 3 to 5). The XY manual stage 21 is configured so that the work W can be held on the upper surface 21a. Further, the XY manual stage 21 can be moved in the X direction and the Y direction according to the manual operation of the operator. Therefore, by moving the XY manual stage 21 in the X and Y directions, the relative position of the rotation symmetry axis of the work W with respect to the rotation axis when the XY manual stage 21 is rotated by the stage drive mechanism 22 can be adjusted. it can. That is, it is possible to suppress the eccentricity by matching the rotation axis and the rotation symmetry axis.

The stage drive mechanism 22 includes a Z-axis drive unit 221 that moves the XY manual stage 21 up and down in the Z direction, an X-axis drive unit 222 that moves the XY manual stage 21 in the X direction, and a rotation shaft that faces the Z direction. It has an R-axis drive unit 223 that rotates in the R direction around (not shown). Therefore, the work W held by the XY manual stage 21 is positioned in the Z direction by operating the Z-axis drive unit 221 in response to an operation command from the drive control unit 31 of the control device 3. Further, when the X-axis drive unit 222 is operated in response to the above operation command, as shown in FIG. 1, a position where work imaging is performed below the cover member 23 (hereinafter referred to as “imaging position”) and X from the cover member 23. The XY manual stage 21 is moved to and from a work delivery position (not shown) separated in the direction. Further, by operating the R-axis drive unit 223 in response to the operation command, the XY manual stage 21 and the work W after the eccentric adjustment are integrally rotated at least once around the rotation axis.

The cover member 23 has a concave inner peripheral surface 23a. The cover member 23 is fixedly arranged vertically above the XY manual stage 21 positioned at the imaging position with the inner peripheral surface 23a facing downward. That is, the inner peripheral surface 23a of the cover member 23 faces the work W positioned at the imaging position, and is a dome that covers the work W from above. Further, the cover member 23 is provided with three through holes 231 to 233 penetrating the inner peripheral surface 23a and the outer peripheral surface 23b. The arrangement positions of the three through holes 231 to 233 are one of the characteristic portions of the present invention, and are important for acquiring a good image by the imaging unit 24. These will be described in detail after the configurations of the imaging unit 24 and the illumination unit 25 have been described.

The image pickup unit 24 is composed of three cameras 241 to 243. As the cameras 241 to 243, a CCD camera, a CMOS camera, or the like can be used. Further, the illumination unit includes a printed circuit board (not shown) arranged along the inner peripheral surface 23a of the cover member 23, and a plurality of light emitting elements arranged on the printed circuit board (reference numerals 251 in FIGS. 3 to 5). And have. As the light emitting element, an LED or the like can be used.

3 to 5 are diagrams schematically showing a mounting state of the camera and the light emitting element with respect to the cover member, respectively. In the lighting unit 25, for example, a plurality of triangular or trapezoidal printed circuit boards are spread over the inner peripheral surface 23a of the cover member 23. Of these plurality of printed circuit boards, those adjacent to the through holes 231 to 233 are provided with through holes of the same size (not shown) facing the through holes 231 to 233. Further, except for these through holes, each printed circuit board is provided with a plurality of through holes. Then, in each light emitting element 251, the lead of the light emitting element 251 is inserted into the through hole with the light emitting surface facing the work W positioned at the imaging position, and is mounted on the land of the printed circuit board. In this way, the plurality of light emitting elements 251 are dispersedly arranged with respect to the inner peripheral surface 23a of the cover member 23, and each light emitting element 251 emits light in response to a lighting command from the lighting control unit 32 of the control device 3. Illumination light is applied to the work W from various illumination directions. Then, the work W illuminated in this way is imaged from three different imaging directions.

As shown in FIG. 3, the camera 241 is arranged in the through hole 231 so that the imaged region Wa of the work W positioned at the imaging position from the imaging direction of 45 ° with respect to the XY plane can be imaged. In the following description, unless otherwise specified, as shown in FIGS. 1, 3 to 5, the imaged region Wa means an region in which the work W positioned at the imaging position should be imaged by the imaging unit 24.

As shown in FIG. 4, the camera 242 is arranged in the through hole 232 so that the imaged region Wa of the work W can be imaged from the imaging direction of 75 ° with respect to the XY plane. Further, as shown in FIG. 5, the camera 243 is arranged in the through hole 233 so that the imaged region Wa of the work W can be imaged from the imaging direction of 15 ° with respect to the XY plane. In this way, each of the cameras 241 to 243 captures the imaged region Wa of the work W through the through hole, acquires an image of the imaged region Wa, and transmits the image data to the image storage unit 33 of the control device 3.

Next, the relative positional relationship of the through holes 231 to 233 in the cover member 23 will be described in detail with reference to FIGS. 1 to 5. Here, in order to clarify the relationship of each part, the through holes 231 to 233 are referred to as "first through hole 231", "second through hole 232" and "third through hole 233", respectively. Further, the cameras 241 to 243 are referred to as "first camera 241", "second camera 242" and "third camera 243", respectively. Further, the reflection-symmetrical regions 261 to 263 of the through holes 231 to 233 with respect to the image-image region Wa are the "first reflection symmetry region 261", the "second reflection symmetry region 262" and the "third reflection symmetry region", respectively. It is called "263".

The first through hole 231 and the first mirrored symmetry region 261 have a mirroring relationship with respect to the imaged region Wa of the work W positioned at the imaging position. Here, the line of intersection between the first virtual plane (paper surface in FIG. 3) including the first through hole 231 and the first reflection symmetry region 261 and the imaged region Wa and the inner peripheral surface 23a of the cover member 23 (hereinafter, “the first”. As shown by the broken line in FIG. 1, 271 is a substantially semi-circular arc centered on the imaged region Wa. Therefore, when the second through hole 232 or the third through hole 233 is hooked on the first line of intersection 271, the light emitting element 251 does not exist at the hooked portion, and the light emitting element 251 is acquired by the first camera 241 due to the inclination of the imaged region Wa. In the image, the part corresponding to the hanging part becomes partially dark, and the image quality deteriorates. Therefore, in the present embodiment, as shown in FIG. 1, the second through hole 232 and the third through hole 233 are arranged at positions away from the first line of intersection 271. As a result, as shown in FIG. 3, the first camera 241 can satisfactorily image the imaged region Wa from an oblique 45 ° imaging direction without being affected by the second through hole 232 and the third through hole 233. it can.

The arrangement relationship of the second through hole 232 and the third through hole 233 with respect to the first camera 241 described above is the arrangement relationship of the first through hole 231 and the third through hole 233 with respect to the second camera 242 and the arrangement relationship with respect to the third camera 243. The same applies to the arrangement of the first through hole 231 and the second through hole 232. That is, as shown in FIG. 2, the second virtual plane (paper surface in FIG. 4) including the second through hole 232, the second reflection symmetry region 262, and the imaged region Wa, and the inner peripheral surface 23a of the cover member 23 The first through hole 231 and the third through hole 233 are provided apart from the intersection line (hereinafter referred to as "second intersection line") 272. As a result, as shown in FIG. 4, the second camera 242 can satisfactorily image the imaged region Wa from the image pickup direction of 75 ° above without being affected by the first through hole 231 and the third through hole 233. it can. Further, the line of intersection between the third virtual plane (paper surface in FIG. 5) including the third through hole 233, the third reflection symmetry region 263, and the imaged region Wa and the inner peripheral surface 23a of the cover member 23 (hereinafter, “third”). The first through hole 231 and the second through hole 232 are provided apart from the 273). As a result, as shown in FIG. 5, the third camera 243 can satisfactorily image the imaged region Wa from the imaging direction of 15 ° sideways without being affected by the first through hole 231 and the second through hole 232. Can be done. The image data of the imaged region Wa acquired by the image capturing unit 24 in this way is sent to the image storage unit 33 of the control device 3 and stored.

As shown in FIG. 1, the control device 3 has an image processing unit 34 and an inspection unit 35 in addition to the drive control unit 31, the lighting control unit 32, and the image storage unit 33. The image processing unit 34 reads the image data acquired by the image capturing unit 24 from the image storage unit 33 while the XY manual stage 21 holding the work W is rotated at least once around the rotation axis, and is an inspection target. An image of the imaged region Wa, that is, an inspection image is created. Then, the inspection unit 35 inspects the work W based on the inspection image.

FIG. 6 is a flowchart showing an inspection operation of the work by the inspection device shown in FIG. In the inspection device 1, the control device 3 controls each part of the inspection device 1 according to a pre-stored inspection program to execute the following operations.

An uninspected work W is placed on the upper surface 21a of the XY manual stage 21 waiting at a work delivery position away from the imaging position (FIG. 1) in the X direction by a transfer robot or an operator (not shown). When held, the drive control unit 31 of the control device 3 drives the stage drive mechanism 22 to position the work W at the imaging position (step S1). Here, when the rotation symmetry axis AX (FIGS. 3 to 5) of the work W with respect to the rotation axis is eccentric, the operator performs eccentric adjustment. That is, the operator moves the XY manual stage 21 in the X and Y directions to match the rotation axis and the rotation symmetry axis. This eccentricity adjustment process may be performed by temporarily suspending the stage movement during the positioning of the work W to the imaging position, or may be performed after the positioning is completed.

When it is confirmed that the work W is positioned at the imaging position in a state where the rotation axis and the rotation symmetry axis coincide with each other, in the next step S2, the illumination control unit 32 lights the light emitting element 251 to display the work W in various ways. Illuminate from the lighting direction of (work lighting). Further, the drive control unit 31 controls the R-axis drive unit 223 to integrally rotate the XY manual stage 21 and the work W after eccentric adjustment around the rotation axis (work rotation). The work illumination and the work rotation are continued until the work W rotates at least once, during which the work W is continuously or intermittently imaged by the image capturing unit 24, and the image data of the imaged region Wa is stored in the image storage unit 33. (Step S3).

When the work W makes at least one rotation (“YES” in step S4), the lighting control unit 32 turns off the light emitting element 251 to stop the work illumination, and the drive control unit 31 rotates the work by the R-axis drive unit 223. Stop (step S5). Subsequently, the drive control unit 31 drives the stage drive mechanism 22 to move the XY manual stage 21 from the imaging position to the work delivery position (step S6). The work W that has been imaged from the XY manual stage 21 positioned at the work delivery position is carried out from the inspection device 1 by a transfer robot, an operator, or the like.

Further, in parallel with the steps S5 and S6, the image processing unit 34 reads the image data from the image storage unit 33 to create an inspection image, and the inspection unit 35 inspects the work W based on the inspection image (step). S7).

As described above, in the present embodiment, in order to image the imaged region Wa of the work W from the three imaging directions while performing the dome illumination as shown in FIG. 1, the cover member 23 has three through holes 231 to 233. Are provided, but they are arranged so as to satisfy the following relationship. That is, in each of the through holes 231 to 233, the through hole, the virtual plane including the reflection symmetric region and the imaged region that are mirror-symmetrical to the imaged region Wa with respect to the imaged region Wa, and the inside of the cover member 23. Another through hole is arranged at a position away from the line of intersection with the peripheral surface 23a. Therefore, the imaged region Wa of the work W illuminated by the dome can be satisfactorily imaged without being affected by the through holes for other cameras. Further, by using the image pickup device 2, the image of the work W can be obtained satisfactorily. Further, the work W can be inspected with high accuracy based on the image.

As described above, in the present embodiment, the XY manual stage 21 corresponds to an example of the "work holding portion" of the present invention. Further, the R-axis drive unit 223 corresponds to an example of the "rotational drive unit" of the present invention.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, the imaged region Wa of the work W is imaged from three imaging directions, but the present invention can also be applied to an apparatus that images images from two imaging directions while illuminating the dome. The present invention can also be applied to an apparatus that captures images from four or more imaging directions.

Further, in the above embodiment, the work W is dome-lit by the same method as in Patent Document 2, but the present invention can be applied to a device that dome-illuminates by another method. For example, the same method as that described in Patent Document 1 can be used. That is, the inner peripheral surface 23a of the cover member 23 is finished as a reflective surface, and the illumination light is emitted from the light emitting element of the illumination unit arranged at the lower peripheral edge of the cover member 23 toward the inner peripheral surface 23a. May be reflected by the inner peripheral surface 23a to guide the work W to illuminate the work W.

The present invention can be applied to all imaging techniques for imaging a workpiece illuminated by the so-called dome illumination method, all image acquisition techniques for acquiring an image of a workpiece using the above imaging techniques, and all inspection techniques for inspecting a workpiece. ..

1 ... Inspection device 2 ... Imaging device 3 ... Control device 21 ... XY manual stage (work holding unit)
23 ... Cover member 23a ... Inner peripheral surface 23b ... Outer peripheral surface 24 ... Imaging unit 25 ... Lighting unit 35 ... Inspection unit 231 ... First through hole 232 ... Second through hole 233 ... Third through hole 241 ... First camera 242 ... 2nd camera 243 ... 3rd camera 251 ... light emitting element 261 ... 1st reflection symmetry area 262 ... 2nd reflection symmetry area 263 ... 3rd reflection symmetry area 271 ... 1st intersection line 272 ... 1st intersection line 273 ... First line of intersection W ... Work Wa ... Imaged area

Claims (7)

The work holding part that holds the work and
A cover member having a dome-shaped inner peripheral surface held by the work holding portion and facing the work, and having a first through hole and a second through hole penetrating the inner peripheral surface and the outer peripheral surface. ,
An illumination unit that illuminates the work by irradiating the work held by the work holding unit with illumination light from each portion of the inner peripheral surface.
It is provided with an image pickup unit that captures an imaged region of the work illuminated by the illumination unit.
The imaging unit includes a first camera that images the imaged area through the first through hole, and a second camera that images the imaged area through the second through hole.
The second through-hole includes a first mirror-symmetrical region that is mirror-symmetrical to the first through-hole with respect to the image-to-image region, a first virtual plane that includes the first through-hole and the image-to-image region, and the above. It is provided at a position away from the first line of intersection with the inner peripheral surface.
The first through hole includes a second mirror symmetry region that is mirror-symmetrical to the second through hole with respect to the imaged region, a second virtual plane including the second through hole and the imaged region, and the above. An imaging device characterized in that it is provided at a position away from the second line of intersection with the inner peripheral surface. The imaging device according to claim 1.
The cover member has a third through hole that penetrates the inner peripheral surface and the outer peripheral surface.
The imaging unit has a third camera that images the imaged region through the third through hole.
The first through hole and the second through hole include a third reflection symmetric region that is mirror-symmetrical to the third through hole with respect to the imaged region, the third through hole, and the imaged region. It is provided at a position away from the third line of intersection between the three virtual planes and the inner peripheral surface.
The third through hole is an imaging device provided at a position away from the first line of intersection and the second line of intersection. The imaging device according to claim 1 or 2.
An image pickup device having a plurality of light emitting elements in which the illumination unit is dispersedly arranged over the entire inner peripheral surface and emits the illumination light toward the work from different illumination directions. The imaging device according to claim 1 or 2.
The illumination unit has a light emitting element that emits the illumination light toward the inner peripheral surface.
The inner peripheral surface is an imaging device that is a reflecting surface that reflects the illumination light and guides the work to the work. The imaging device according to any one of claims 1 to 4.
An imaging device including a rotation drive unit that rotates the work holding unit around a rotation axis. An image acquisition method for acquiring an image of the work using the imaging device according to claim 5.
An image acquisition method, characterized in that an image of the work is acquired by the imaging unit while the work is rotated at least once by the rotation driving unit. The imaging device according to claim 5 and
An inspection device including an inspection unit that inspects the work based on an image captured by the imaging unit while the work is rotated at least once by the rotation drive unit.

Images