JP2024172889A - Appearance inspection device and appearance inspection method - Google Patents

Abstract

[Problem] To provide an appearance inspection device capable of appropriately inspecting the appearance of a cylindrical or columnar object to be inspected. [Solution] The appearance inspection device is an appearance inspection device for inspecting the appearance of a cylindrical or columnar object to be inspected, and includes a rotation mechanism for rotating the object to be inspected in the circumferential direction of the object to be inspected, a sensor for irradiating a laser beam onto the surface of the object to be inspected while rotating in the circumferential direction and receiving the reflected light of the laser beam reflected by the surface of the object to be inspected, an image processing unit for generating a height image of the surface based on the reception state of the reflected light, and a judgment unit for judging the properties of the surface based on the height image. [Selected Figure] Figure 2

Description

The present invention relates to an appearance inspection device and an appearance inspection method.

Conventionally, there has been known a method for inspecting a silicon single crystal produced by the Czochralski method (see, for example, Patent Documents 1 and 2).
Patent Document 1 discloses a method of scanning the shape of a V-notch formed in the longitudinal direction of a silicon single crystal ingot using an optical measurement means, generating evaluation data by performing coordinate conversion of the V-notch shape data obtained by the scan, and judging the quality of the V-notch shape based on the generated evaluation data.
Patent Document 2 discloses a method for identifying regions in a silicon single crystal having an excess of vacancies by performing a heat treatment on a p-type silicon single crystal in a nitrogen atmosphere and then measuring the distribution of crystal defects caused by vacancies in the silicon single crystal.

In addition, Patent Document 3, which relates to a cleaning device for silicon single crystal blocks cut from silicon single crystals, discloses that the appearance of silicon single crystal blocks cleaned by the cleaning device is automatically inspected.

JP 2020-043205 A JP 2018-186195 A JP 2011-143321 A

However, Patent Documents 1 and 2 do not disclose a method for inspecting the appearance of silicon single crystals. Furthermore, Patent Document 3 discloses an automatic inspection of the appearance of silicon single crystal blocks, but does not disclose a specific method.

The present invention aims to provide an appearance inspection device and an appearance inspection method that can properly inspect the appearance of a cylindrical or columnar object to be inspected.

The appearance inspection device of the present invention is an appearance inspection device that inspects the appearance of a cylindrical or columnar inspection object, and includes a rotation mechanism that rotates the inspection object in the circumferential direction of the inspection object, a sensor that irradiates a laser beam onto the surface of the inspection object rotating in the circumferential direction and receives the reflected light of the laser beam reflected by the surface of the inspection object, an image processing unit that generates a height image of the surface based on the reception state of the reflected light, and a judgment unit that judges the properties of the surface based on the height image.

In the visual inspection device of the present invention, it is preferable that the device further includes a sensor movement mechanism that moves the sensor along the surface, the rotation mechanism rotates the object under inspection one revolution at a time in the circumferential direction, the sensor irradiates the laser light onto the surface while the object under inspection is rotating once, and receives the reflected light reflected by the surface of the object under inspection, and the sensor movement mechanism moves the sensor a predetermined distance along the surface each time the object under inspection rotates once.

In the visual inspection device of the present invention, it is preferable that the rotation mechanism changes the rotation direction to the opposite direction every time the inspected object is rotated once in the same direction a predetermined number of times.

In the visual inspection device of the present invention, it is preferable that the sensor movement mechanism moves the single sensor along the outer peripheral surface as the surface in a direction parallel to the central axis of the inspected object, and moves the sensor in the radial direction of the inspected object along the end face as the surface.

In the visual inspection device of the present invention, it is preferable that the sensor movement mechanism includes a first movement mechanism that moves the first sensor in a direction parallel to the central axis of the object to be inspected along the outer peripheral surface as the surface, and a second movement mechanism that moves the second sensor in the radial direction of the object to be inspected along the end face as the surface.

In the visual inspection device of the present invention, it is preferable that the laser light is blue laser light.

In the visual inspection device of the present invention, it is preferable that the image processing unit generates a two-dimensional image of the surface based on the receiving state of the reflected light, and the judgment unit identifies an abnormality on the surface based on the two-dimensional image, and judges the presence or absence of a defect on the surface based on the height image of the identified abnormality.

The appearance inspection method of the present invention is an appearance inspection method for inspecting the appearance of a cylindrical or columnar object to be inspected, and includes a surface inspection step of rotating the object to be inspected once in the circumferential direction of the object to be inspected, irradiating a laser beam from a sensor onto the surface of the object to be inspected while rotating in the circumferential direction, and receiving the reflected light of the laser beam reflected by the surface of the object to be inspected by the sensor, an image processing step of generating a height image of the surface based on the reception state of the reflected light, and a determination step of determining the properties of the surface based on the height image.

In the appearance inspection method of the present invention, the surface inspection step preferably includes rotating the object under inspection once in the circumferential direction and then stopping the object under inspection. Here, it is preferable to repeat the process of irradiating the surface with the laser light from the sensor while the object under inspection is rotating once, receiving the light reflected by the surface with the sensor, and moving the sensor a predetermined distance along the surface when the object under inspection stops.

In the appearance inspection method of the present invention, the surface inspection step includes an outer peripheral surface inspection step and an end face inspection step performed before or after the outer peripheral surface inspection step, and the outer peripheral surface inspection step is preferably performed by rotating the object to be inspected once in the circumferential direction and then stopping the object to be inspected. Here, it is preferable that, while the object to be inspected rotates once, the laser light is irradiated from the single sensor onto the outer peripheral surface as the surface, the reflected light reflected from the outer peripheral surface is received by the single sensor, and when the object to be inspected stops, the process of moving the single sensor along the outer peripheral surface by a predetermined distance in a direction parallel to the central axis of the object to be inspected is repeated. It is preferable that the end face inspection step is performed by rotating the object to be inspected once in the circumferential direction and then stopping the object to be inspected. Here, it is preferable that, while the object to be inspected rotates once, the laser light is irradiated from the single sensor onto the end face as the surface, the reflected light is received by the single sensor, and when the object to be inspected stops, the process of moving the single sensor along the end face by a predetermined distance in the radial direction of the object to be inspected is repeated.

In the appearance inspection method of the present invention, the surface inspection step preferably includes rotating the test object once in the circumferential direction and then stopping the test object. Here, while the test object rotates once, the first sensor irradiates the laser light onto the outer peripheral surface as the surface, and the first sensor receives the reflected light reflected by the outer peripheral surface, while the second sensor irradiates the laser light onto the end surface as the surface, and the second sensor receives the reflected light reflected by the end surface, and when the test object stops, the first sensor is moved along the outer peripheral surface by a first distance in a direction parallel to the central axis of the test object, and the second sensor is moved along the end surface by a second distance in the radial direction of the test object.

In the visual inspection method of the present invention, it is preferable that in the surface inspection process, when rotating the object to be inspected once in the circumferential direction, the direction of rotation is changed to the opposite direction every time the object to be inspected is rotated once in the same direction a predetermined number of times.

In the visual inspection method of the present invention, it is preferable that the object to be inspected is a cylindrical silicon single crystal block obtained by cutting a silicon single crystal.

In the visual inspection method of the present invention, the surface inspection step preferably includes detecting a notch in the silicon single crystal block when rotating the object to be inspected once in the circumferential direction, and rotating the silicon single crystal block once based on the notch.

In the appearance inspection method of the present invention, it is preferable that the laser light is blue laser light.

In the appearance inspection method of the present invention, it is preferable that the image processing step generates a two-dimensional image of the surface based on the reception state of the reflected light, and the judgment step identifies an abnormality on the surface based on the two-dimensional image, and judges the presence or absence of a defect on the surface based on the height image of the identified abnormality.

1 is a perspective view showing a schematic configuration of a visual inspection apparatus according to a first embodiment. 2 is a block diagram showing a schematic configuration of a control system of the visual inspection apparatus according to the first embodiment. FIG. 5A and 5B are schematic diagrams showing a movement state of a sensor during inspection according to the first embodiment. 5A and 5B are schematic diagrams showing the irradiation range of the blue laser light used in the inspection according to the first embodiment, in which (A) shows the irradiation range of the outer circumferential surface, and (B) shows the irradiation range of the end surface. 1A is a schematic diagram of images used in an inspection according to the first embodiment, in which (A) shows a two-dimensional image, (B) shows a height image, and (C) shows a cross-sectional shape image. 4 is a flowchart of a visual inspection process according to the first embodiment. 4 is a flowchart of a visual inspection process according to the first and second embodiments. 5 is a flowchart of an inspection process for an outer circumferential surface according to the first embodiment. 4 is a flowchart of an end face inspection process according to the first embodiment. FIG. 11 is a perspective view showing a schematic configuration of a visual inspection apparatus according to a second embodiment. FIG. 11 is a block diagram showing a schematic configuration of a control system of a visual inspection apparatus according to a second embodiment. 11A and 11B are schematic diagrams showing the movement state of the sensor during inspection according to the second embodiment, in which (A) shows the movement state during inspection of the outer circumferential surface, and (B) shows the movement state during inspection of the end surface. 10 is a flowchart of a visual inspection process according to a second embodiment. 10 is a flowchart of an inspection process for an outer circumferential surface and an end surface according to a second embodiment. 10 is a flowchart of an inspection process for an outer circumferential surface and an end surface according to a second embodiment.

[First embodiment]
[Configuration of visual inspection device]
First, the configuration of a visual inspection apparatus according to a first embodiment of the present invention will be described.
Fig. 1 is a perspective view showing a schematic configuration of a visual inspection device of a first embodiment. Fig. 2 is a block diagram showing a schematic configuration of a control system of the visual inspection device. Fig. 3 is a schematic diagram showing a movement state of a sensor during inspection. Fig. 4 is a schematic diagram showing an irradiation range of blue laser light used for inspection, (A) showing the irradiation range of an outer peripheral surface, and (B) showing the irradiation range of an end surface. Fig. 5 is a schematic diagram of an image used for inspection, (A) showing a two-dimensional image, (B) showing a height image, and (C) showing a cross-sectional shape image.
In the following description, each component may be described based on the XYZ coordinate system shown in FIG. 1, where the X-axis direction represents the front-rear direction, the Y-axis direction represents the left-right direction, and the Z-axis direction represents the up-down direction.

The appearance inspection device 1 shown in FIG. 1 inspects the appearance of a silicon single crystal block B as a cylindrical object to be inspected.
The silicon single crystal block B is obtained by cutting out a cylindrical shape from a silicon single crystal produced by the Czochralski method, and then performing at least a well-known cylindrical grinding process on the outer peripheral surface and a chamfering process on the corners at both ends in the crystal axis direction (the longitudinal direction of the silicon single crystal block B).
The silicon single crystal block B has an outer peripheral surface BA, which is a surface of the silicon single crystal block B, on which a notch BV is formed along the longitudinal direction of the silicon single crystal block B.
The size of the silicon single crystal block B can be exemplified as a diameter R of 100 mm or more and 450 mm or less, and a length L of 50 mm or more and 500 mm or less.

As shown in Figures 1 and 2, the visual inspection device 1 includes a rotation mechanism 2, an inspection unit 3, and a control device 4.

The rotating mechanism 2 rotates the silicon single crystal block B in the circumferential direction of the silicon single crystal block B. The rotating mechanism 2 includes a pair of rotating rollers 21 and a roller driving unit 22 that drives the pair of rotating rollers 21.
The pair of rotating rollers 21 are arranged horizontally at a predetermined distance from each other and rotatably about a rotation axis extending in the front-rear direction. The pair of rotating rollers 21 support the outer peripheral surface BA of the silicon single crystal block B from below.
The roller driving unit 22 rotates the pair of rotating rollers 21 in the same direction under the control of the control device 4, thereby rotating the silicon single crystal block B in the circumferential direction of the silicon single crystal block B.

The inspection unit 3 includes a single sensor 31 and a sensor movement mechanism 32.

The sensor 31 is configured by a laser displacement sensor, and includes a sensor body 311 , an emitting section 312 , and a light receiving section 313 .
The sensor body 311 includes a light incident/exit surface 311A.
The irradiation unit 312 is disposed in the sensor body 311. The irradiation unit 312 continuously irradiates the blue laser light based on the control of the control device 4. The irradiation unit 312 may irradiate the blue laser light intermittently at a predetermined interval. As shown in FIG. 3, when the distance from the light entrance/exit surface 311A to the outer peripheral surface BA is the inspection distance K, the blue laser light irradiated from the light entrance/exit surface 311A is irradiated so that the length of the linear irradiation range H is shorter than the length of the outer peripheral surface BA in the front-rear direction, as shown in FIG. 3. When the distance from the light entrance/exit surface 311A to the end surface BB is the inspection distance K, the blue laser light is irradiated so that the length of the irradiation range H is shorter than the radius of the end surface BB.
Light receiving unit 313 is disposed within sensor body 311. Light receiving unit 313 receives reflected light of blue laser light that is irradiated from light incident/emitting surface 311A and reflected by outer circumferential surface BA or end surface BB, and outputs a signal corresponding to the light receiving state to control device 4. Hereinafter, "reflected light of blue laser light" may be simply referred to as "reflected light".

The sensor movement mechanism 32 includes a six-axis robot 321. The six-axis robot 321 is configured to hold the sensor 31 and to be able to freely change the position and orientation of the light incident/exit surface 311A relative to the silicon single crystal block B. The six-axis robot 321 moves the sensor 31 in the front-to-rear direction above the silicon single crystal block B under the control of the control device 4. In other words, the six-axis robot 321 moves the sensor 31 along the outer peripheral surface BA in a direction parallel to the central axis BC of the silicon single crystal block B. The six-axis robot 321 moves the sensor 31 in the up-down direction at a position facing the end face BB on the rear side (-X direction side) of the silicon single crystal block B under the control of the control device 4.

As shown in FIG. 2, the control device 4 includes an input unit 41, a display unit 42, a memory unit 43, and a control unit 44. The roller drive unit 22, the irradiation unit 312, the light receiving unit 313, the six-axis robot 321, the input unit 41, the display unit 42, and the memory unit 43 are electrically connected to the control unit 44.

The input unit 41 is configured, for example, by a touch panel or physical buttons. The input unit 41 is used to input various information, and outputs a signal corresponding to the input to the control unit 44.

The display unit 42 displays various information based on the control of the control unit 44.

The memory unit 43 is configured with a well-known storage device such as a hard disk drive (HDD). The memory unit 43 stores various information necessary for inspecting the silicon single crystal block B.

The control unit 44 includes a CPU (Central Processing Unit). The control unit 44 functions as a block information acquisition unit 441, an inspection control unit 442, an image processing unit 443, a determination unit 444, a block shape calculation unit 445, and a display control unit 446 by the CPU executing the inspection control program stored in the storage unit 43.

The block information acquisition unit 441 acquires block information for identifying the silicon single crystal block B to be inspected. The block information acquisition unit 441 may acquire block information input by an operator operating the input unit 41, or may acquire block information read by a code reader from a two-dimensional code displayed on, for example, an end face BB of the silicon single crystal block B.

The inspection control unit 442 controls the roller driving unit 22 and the six-axis robot 321 to inspect the outer peripheral surface BA and end surface BB of the silicon single crystal block B.
When inspecting the outer peripheral surface BA, the inspection control unit 442 controls the six-axis robot 321 to position the sensor 31 at the inspection position of the first outer peripheral surface with the light incident/exit surface 311A facing the outer peripheral surface BA on the upper side of the silicon single crystal block B. The inspection position of the first outer peripheral surface is a position where the rear end of the irradiation range H is located rearward of the rear end face BB, the front end is located on the outer peripheral surface BA, and the distance from the light incident/exit surface 311A to the outer peripheral surface BA is the inspection distance K, as shown by the solid lines in Fig. 3 and Fig. 4(A). Note that in Fig. 4(A), the irradiation range H is illustrated as a rectangle whose left-right direction is parallel to the short side direction in order to make the first embodiment easy to understand, but the actual irradiation range H is a line extending in the front-rear direction. The inspection control unit 442 controls the roller driving unit 22 to rotate the silicon single crystal block B once about the central axis BC, and causes the irradiation unit 312 to irradiate the blue laser light onto the outer circumferential surface BA.
When the inspection control unit 442 acquires a signal corresponding to the light receiving state from the light receiving unit 313 which receives the light reflected by the outer peripheral surface BA, it associates information on the light receiving state at each rotation angle, position information on the inspection position of the first outer peripheral surface, and block information of the silicon single crystal block B to be inspected, and stores them in the memory unit 43 as inspection information for the first outer peripheral surface.

Thereafter, the inspection control unit 442 controls the six-axis robot 321 to sequentially move the sensor 31 along the central axis BC to an inspection position of the Nth (N is an integer of 2 or more) outer peripheral surface while maintaining the state in which the light incident/exit surface 311A faces the outer peripheral surface BA and maintaining the distance from the light incident/exit surface 311A to the outer peripheral surface BA at the inspection distance K. When the sensor 31 is at the inspection position of the Nth outer peripheral surface, the irradiation range H is located at the position indicated by the two-dot chain line. The inspection position of the Nth outer peripheral surface is located forward of the inspection position of the (N-1)th outer peripheral surface, and is a position where the overlap width between the irradiation range H of the blue laser light irradiated from the inspection position of the Nth outer peripheral surface and the irradiation range H of the blue laser light irradiated from the inspection position of the (N-1)th outer peripheral surface is width D1. The width D1 is a value exceeding 0 mm. The inspection control unit 442 rotates the silicon single crystal block B once each time the sensor 31 is positioned at the inspection position for the Nth outer circumferential surface, and causes the irradiation unit 312 to irradiate the outer circumferential surface BA with blue laser light.
Each time the inspection control unit 442 emits blue laser light at the inspection position of the Nth outer peripheral surface, it associates information on the light receiving state at each rotation angle, position information of the inspection position of the Nth outer peripheral surface, and block information, and stores the information in the memory unit 43 as inspection information for the Nth outer peripheral surface.

The inspection control unit 442 repeats the above-mentioned process until the inspection is completed with the front end of the irradiation range H positioned forward of the front end face BB and the rear end positioned on the outer peripheral surface BA, as shown in FIG. 4(A). In the example shown in FIG. 4(A), the above-mentioned process is repeated until the inspection is completed with the sensor 31 positioned at the inspection position of the 13th outer peripheral surface.

When inspecting the end face BB, the inspection control unit 442 controls the six-axis robot 321 to position the sensor 31 at the inspection position of the first end face with the light incident/exit surface 311A facing the end face BB. The inspection position of the first end face is a position where the upper end of the irradiation range H is located above the outer circumferential surface BA, the lower end is located on the end face BB, and the distance from the light incident/exit surface 311A to the end face BB is the inspection distance K, as shown by the dashed line in FIG. 3 and FIG. 4B. Note that in FIG. 4B, the irradiation range H is illustrated as a rectangle whose left-right direction is parallel to the short side direction for easy understanding of the first embodiment, but the actual irradiation range H is a line extending in the up-down direction. The inspection control unit 442 rotates the silicon single crystal block B once and causes the irradiation unit 312 to irradiate the end face BB with blue laser light.
When the inspection control unit 442 acquires a signal corresponding to the light receiving state from the light receiving unit 313 that receives the reflected light from the end face BB, it associates information on the light receiving state at each rotation angle with position information of the inspection position of the first end face and block information, and stores the information in the memory unit 43 as inspection information for the first end face.

Thereafter, the inspection control unit 442 controls the six-axis robot 321 to move the sensor 31 vertically to the inspection position of the Mth end face (M is an integer of 2 or more) while maintaining the state in which the light incident/exit surface 311A faces the end face BB and maintaining the distance from the light incident/exit surface 311A to the end face BB at the inspection distance K. When the sensor 31 is present at the inspection position of the Mth end face, the irradiation range H is located at the position indicated by the two-dot chain line. The inspection position of the Mth end face is located below the inspection position of the (M-1)th end face, and is a position where the overlap width between the irradiation range H of the blue laser light irradiated from the inspection position of the Mth end face and the irradiation range H of the blue laser light irradiated from the inspection position of the (M-1)th end face is width D2. The width D2 is a value exceeding 0 mm and may be the same as or different from the width D1. The inspection control unit 442 rotates the silicon single crystal block B once each time the sensor 31 is positioned at the inspection position for the Mth end face, and causes the irradiation unit 312 to irradiate the end face BB with blue laser light.
Each time the inspection control unit 442 emits blue laser light at the inspection position of the Mth end face, it associates information on the light receiving state at each rotation angle, position information of the inspection position of the Nth end face, and block information, and stores them in the memory unit 43 as inspection information for the Mth end face.
The inspection control unit 442 repeats the above-mentioned process until the inspection is completed in a state where the lower end of the irradiation range H is located below the central axis BC and the upper end is located above the central axis BC, as shown in Fig. 4(B) . In the example shown in Fig. 4(B) , the above-mentioned process is repeated until the inspection is completed in a state where the sensor 31 is located at the inspection position for the fifth end face.

The image processing unit 443 generates a two-dimensional image PA shown in Fig. 5(A) and a height image PB shown in Fig. 5(B) based on the state of reception of reflected light at the light receiving unit 313 for each rotation angle represented by the inspection information of each outer peripheral surface or the inspection information of each end surface. The up-down direction in the two-dimensional image PA in Fig. 5(A) and the height image PB in Fig. 5(B) is the circumferential direction of the silicon single crystal block B, and the left-right direction is the direction of the central axis BC.
The image processing unit 443 generates a cross-sectional shape image PC shown in FIG. 5C based on the height image PB.

The two-dimensional image PA represents the characteristics of the outer peripheral surface BA or the end surface BB irradiated with the blue laser light in black and white shading. For example, the two-dimensional image PA represents the characteristics of the outer peripheral surface BA or the end surface BB in black and white shading corresponding to the distance from the reference surface to the sensor 31, with the outer peripheral surface BA or the end surface BB being used as a reference surface.
For example, in the two-dimensional image PA shown in Fig. 5A, which is generated based on the inspection information of the first outer peripheral surface, the outer peripheral surface BA is represented by a white region. The chamfered portion BD of the silicon single crystal block B is represented by a first gray region extending linearly in the circumferential direction at one end of the white region in the direction of the central axis BC. The inspection object non-existence region C, where the silicon single crystal block B is not present, is represented by a black region located on the other end side of the white region in the direction of the central axis BC with respect to the first gray region.

An abnormal portion BE may exist on the outer peripheral surface BA, the chamfered portion BD, or the boundary between the outer peripheral surface BA and the chamfered portion BD. The abnormal portion BE is a protruding portion where dirt or other foreign matter is attached, or a recessed portion where defects such as scratches, cracks, chips, or residual skin are present. Residual skin is a portion that was not ground during cylindrical grinding.
In the two-dimensional image PA, the abnormal area BE is represented by a second gray area, the shade of which depends on the height or depth of the abnormal area BE and may be a shade different from or the same as that of the first gray area.
In the two-dimensional image PA, the abnormal area BE is represented in shades of gray according to its height or depth, so if the two-dimensional image PA is used in a determination process to determine whether the abnormal area BE is a foreign object or a defect, the determination may become difficult.

The height image PB represents the characteristics of the outer peripheral surface BA or the end surface BB in color. For example, the height image PB represents the characteristics of the outer peripheral surface BA or the end surface BB in hue, brightness, and saturation corresponding to the distance from the reference surface to the sensor 31, with the outer peripheral surface BA or the end surface BB being used as a reference surface.
For example, in the height image PB shown in Fig. 5(B) generated based on the inspection information of the first outer peripheral surface, the abnormal portion BE is represented by a color having at least one of different hue, brightness, and saturation depending on the depth of the abnormal portion BE relative to the outer peripheral surface BA when the abnormal portion BE is a defect occurrence region, and depending on the height of the abnormal portion BE relative to the outer peripheral surface BA when the abnormal portion BE is a foreign matter adhesion region. When the abnormal portion BE shown in Fig. 5(B) is a defect occurrence region, for example, a shallow portion BE1, an intermediate portion BE2 deeper than the shallow portion BE1, and a deep portion BE3 deeper than the intermediate portion BE2 are represented by colors having at least one of different hue, brightness, and saturation.
In addition, in the height image PB, the outer peripheral surface BA, the chamfered portion BD, the non-existent inspection object area C, and the abnormal area BE where foreign matter is attached are represented in colors having hue, brightness, and saturation according to their height or depth relative to the outer peripheral surface BA.
In the height image PB, the abnormal area BE is represented by a different color having at least one of a hue, a brightness, and a saturation according to its height or depth. Therefore, when the height image PB is used for the process of determining the abnormal area BE, the determination becomes easier than when the two-dimensional image PA is used.

The cross-sectional shape image PC represents the cross-sectional shape of the defect occurring in the abnormal portion BE. The cross-sectional shape image PC in Fig. 5(C) represents the cross-sectional shape of the abnormal portion BE along the line VC-VC parallel to the circumferential direction in Fig. 5(B). In the cross-sectional shape image PC, the defects in the abnormal portion BE are represented by lines corresponding to the shapes of the shallow portion BE1, the intermediate portion BE2, and the deep portion BE3. In the cross-sectional shape image PC in Fig. 5(C), the up-down direction is the radial direction of the silicon single crystal block B, and the left-right direction is the circumferential direction.
The cross-sectional shape image PC may represent the cross-sectional shape of the abnormal area BE along a line inclined or perpendicular to the circumferential direction.

In addition, although not shown, the image processing unit 443 generates a two-dimensional image PA, a height image PB, and a cross-sectional shape image PC that represent the state of the end face BB, the chamfered portion BD, the non-existent inspection object area C, and the abnormal area BE based on the inspection information of each end face.

When the irradiation range H corresponding to the inspection position of the outer peripheral surface in the inspection information of the outer peripheral surface includes an area outside the end face BB, the chamfered portion BD and the inspection target non-existence area C are present in the two-dimensional image PA and height image PB, but when the area outside the end face BB is not included, the chamfered portion BD and the inspection target non-existence area C are not present in the two-dimensional image PA and height image PB. When the irradiation range H corresponding to the inspection position of the end face in the inspection information of the end face includes an area outside the outer peripheral surface BA, the chamfered portion BD and the inspection target non-existence area C are present in the two-dimensional image PA and height image PB, but when the area outside the outer peripheral surface BA is not included, the chamfered portion BD and the inspection target non-existence area C are not present in the two-dimensional image PA and height image PB.

The determination unit 444 identifies an abnormality BE on the outer peripheral surface BA or the end surface BB based on the two-dimensional image PA. When the determination unit 444 detects that a second gray area representing the abnormality BE exists within a white area representing the outer peripheral surface BA or the end surface BB in the two-dimensional image PA, the determination unit 444 determines that an abnormality BE exists on the outer peripheral surface BA or the end surface BB.
When the determination unit 444 determines that an abnormal portion BE exists based on the two-dimensional image PA, the determination unit 444 determines whether or not a foreign matter or defect exists at the abnormal portion BE as a property of the outer peripheral surface BA or the end surface BB based on the height image PB including the abnormal portion BE. If the color of the area representing the abnormal portion BE in the height image PB indicates that it is higher than the outer peripheral surface BA or the end surface BB, the determination unit 444 determines that a foreign matter exists at the abnormal portion BE, and if the color of the area representing the abnormal portion BE in the height image PB indicates that it is lower than the outer peripheral surface BA or the end surface BB, the determination unit 444 determines that a defect exists at the abnormal portion BE.

When the determination unit 444 determines that a defect exists in the abnormal area BE, it determines whether the defect is a scratch, a crack, a chip, or a remaining skin, that is, it determines the type of the defect. When determining the type of defect, the determination unit 444 makes the determination based on at least one parameter of the length, area, depth, and inclination angle of the defect. The determination unit 444 calculates at least one of the length, area, and depth of the defect based on the height image PB. The determination unit 444 calculates at least the inclination angle of the depth and inclination angle of the defect based on the cross-sectional shape image PC.
The judgment unit 444 may determine that the defect is an unacceptable defective defect if the at least one parameter is equal to or greater than a threshold value preset in the judgment unit 444, and may determine that the defect is an acceptable defect if the parameter is less than the threshold value.

The block shape calculation unit 445 calculates the length and diameter of the silicon single crystal block B in the direction of the central axis BC based on the two-dimensional image PA, the height image PB, or the movement distance of the sensor 31 during inspection.

The display control unit 446 controls the display unit 42 to display the presence or absence of foreign matter or defects on the outer peripheral surface BA and the end surface BB, the type of defect, and the length and diameter of the silicon single crystal block B as the inspection results on the display unit 42.

[Operation of visual inspection device]
Next, a description will be given of the appearance inspection process of the silicon single crystal block B as an operation of the appearance inspection apparatus 1. Figures 6 and 7 are flowcharts of the appearance inspection process. Figure 8 is a flowchart of the inspection process of the outer circumferential surface. Figure 9 is a flowchart of the inspection process of the end surface.
The processes of steps S2 to S7 shown in Fig. 6, steps S21 to S25 shown in Fig. 8, and steps S31 to S35 shown in Fig. 9 constitute a surface inspection process. Of the processes constituting the surface inspection process described above, the processes of steps S5 and S21 to S25 constitute an outer circumferential surface inspection process, and the processes of steps S7 and S31 to S35 constitute an end face inspection process. The processes of steps S8 to S12 shown in Fig. 7 constitute a judgment process.

An operator or a conveying device (not shown) sets a silicon single crystal block B to be inspected on a pair of rotating rollers 21 as shown in FIG.
Before or after the silicon single crystal block B is set on the pair of rotating rollers 21, the block information acquisition unit 441 of the control unit 44 constituting the visual inspection apparatus 1 acquires block information as shown in FIG. 6 (step S1).

When the inspection control unit 442 of the control unit 44 receives an instruction to start the inspection based on the operator's operation of the input unit 41, it controls the six-axis robot 321 to move the sensor 31 to the inspection position of the first outer peripheral surface on the outer peripheral surface BA of the silicon single crystal block B (step S2).

The inspection control unit 442 rotates the silicon single crystal block B so that the notch BV is located at the reference position (step S3).
For example, the inspection control unit 442 controls the roller driving unit 22 to rotate the silicon single crystal block B once in a first direction (clockwise direction when viewed from the front), and controls the irradiation unit 312 to irradiate the outer circumferential surface BA with blue laser light. For example, during the rotation of the silicon single crystal block B, the image processing unit 443 generates a two-dimensional image PA in which the outer circumferential surface BA and the notch BV are represented in different shades, or a height image PB in which the outer circumferential surface BA and the notch BV are represented in different colors, based on the light receiving state of the reflected light at the light receiving unit 313. The inspection control unit 442 controls the roller driving unit 22 to stop the rotation of the silicon single crystal block B based on the two-dimensional image PA or the height image PB so that the notch BV is located at a reference position.
An example of the reference position is a position where the angle between a first imaginary line extending vertically upward from the central axis BC when viewing the end face BB from the front and a second imaginary line connecting the central axis BC and the center of the notch BV is 0°, but it may be a position other than 0°.

The inspection control unit 442 detects the position of the rear end face BB when viewed from above, that is, the edge of the silicon single crystal block B (step S4).
For example, the inspection control unit 442 detects the edge of the silicon single crystal block B based on the two-dimensional image PA or the height image PB used when positioning the notch BV at the reference position.

The inspection control unit 442 performs an inspection process for the outer circumferential surface BA (step S5).
In the inspection process of the outer circumferential surface BA in step S5, the inspection control unit 442 sets the set rotation direction of the silicon single crystal block B to a first direction as shown in FIG. 8 (step S21).

The inspection control unit 442 inspects the outer circumferential surface BA of the silicon single crystal block B while rotating it once in the set rotation direction (step S22).
In step S22, the inspection control unit 442 controls the roller driving unit 22 to rotate the silicon single crystal block B once in the set rotation direction, and controls the irradiation unit 312 to irradiate the outer circumferential surface BA with blue laser light. When the inspection control unit 442 acquires a signal corresponding to the light receiving state from the light receiving unit 313, it generates inspection information of the outer circumferential surface corresponding to the inspection position of the sensor 31 on the outer circumferential surface and stores it in the storage unit 43. When the inspection control unit 442 determines that the notch BV has returned to the reference position based on the signal from the light receiving unit 313, it stops the rotation of the silicon single crystal block B.

The inspection control unit 442 judges whether the inspection of the entire outer peripheral surface BA has been completed (step S23). For example, when the image processing unit 443 generates a two-dimensional image PA or a height image PB based on the inspection information of the outer peripheral surface generated in step S22, and the two-dimensional image PA or the height image PB includes an inspection object non-existent region C forward of the end face BB, the inspection control unit 442 judges that the inspection of the entire outer peripheral surface BA has been completed (step S23: YES), and ends the inspection process of the outer peripheral surface BA.
On the other hand, when the two-dimensional image PA or the height image PB does not include the inspection target non-existing region C on the front side of the end face BB, the inspection control unit 442 determines that the inspection of the entire outer peripheral surface BA has not been completed (step S23: NO), and sets the set rotation direction of the silicon single crystal block B to the opposite direction to that in the previous inspection (step S24). That is, in step S24, the inspection control unit 442 sets the set rotation direction to the second direction if the set rotation direction in the previous inspection was the first direction, and sets the set rotation direction to the first direction if the set rotation direction in the previous inspection was the second direction.
In addition, in step S23, if the set number of inspections input by the operator based on operation of the input unit 41 has been completed, it may be determined that inspection of the entire outer peripheral surface BA has been completed, and if the set number of inspections has not been completed, it may be determined that inspection of the entire outer peripheral surface BA has not been completed.

The inspection control unit 442 controls the six-axis robot 321 to move the sensor 31 to the inspection position for the next outer circumferential surface (step S25).
In step S25, if the inspection position of the outer circumferential surface in the previous inspection was the inspection position of the Eth outer circumferential surface (E is an integer greater than or equal to 1), the inspection control unit 442 moves the sensor 31 to the inspection position of the (E+1)th outer circumferential surface.

After the process of step S25, the inspection control unit 442 inspects the outer circumferential surface BA while rotating the silicon single crystal block B once in the set rotation direction (step S22).
The inspection control unit 442 repeats the above-mentioned process until it is determined in step S23 that inspection of the entire outer circumferential surface BA has been completed.

When the inspection process of the outer peripheral surface BA in step S5 is completed, the inspection control unit 442 controls the six-axis robot 321 to move the sensor 31 to the inspection position of the first end face opposite the rear end face BB of the silicon single crystal block B, as shown in FIG. 6 (step S6).

The inspection control unit 442 performs an inspection process for the end surface BB (step S7).
In the inspection process of the end face BB in step S7, the inspection control unit 442 sets the set rotation direction of the silicon single crystal block B to the first direction (step S31), as shown in FIG. 9, in the same manner as in the process of step S21.

The inspection control unit 442 inspects the end face BB while rotating the silicon single crystal block B once in the set rotation direction (step S32).
In step S32, the inspection control unit 442 rotates the silicon single crystal block B once in the set rotation direction, and irradiates the end face BB with blue laser light from the irradiation unit 312. The inspection control unit 442 generates end face inspection information corresponding to the end face inspection position of the sensor 31 based on a signal corresponding to the light receiving state from the light receiving unit 313, and stores the information in the storage unit 43.

The inspection control unit 442 judges whether the inspection of the entire end face BB has been completed (step S33). For example, the inspection control unit 442 calculates a set number of times until the inspection is completed in a state where the lower end of the irradiation range H is located below the central axis BC and the upper end is located above the central axis BC, based on the radius of the silicon single crystal block B and the width of the irradiation range H. Then, the inspection control unit 442 judges that the inspection of the entire end face BB has been completed when the set number of inspections has been completed, and judges that the inspection of the entire end face BB has not been completed when the set number of inspections has not been completed. The set number of times may be a number inputted based on the operation of the input unit 41 by the operator.
If the inspection control unit 442 determines that the inspection of the entire end face BB has been completed (step S33: YES), the inspection control unit 442 ends the inspection process of the end face BB.
On the other hand, if the inspection control unit 442 determines that inspection of the entire end face BB has not been completed (step S33: NO), it sets the set rotation direction of the silicon single crystal block B to the opposite direction to that during the previous inspection (step S34), similar to the processing of step S24.

The inspection control unit 442 controls the six-axis robot 321 to move the sensor 31 to the inspection position for the next end face (step S35).
In step S35, if the inspection position of the end face in the previous inspection was the inspection position of the Eth end face (F is an integer greater than or equal to 1), the inspection control unit 442 moves the sensor 31 to the inspection position of the (F+1)th end face.

After the process of step S35, the inspection control unit 442 inspects the end face BB while rotating the silicon single crystal block B once in the set rotation direction (step S32).
The inspection control unit 442 repeats the above-described process until it determines in step S33 that inspection of the entire end face BB has been completed.

When the inspection process of the end face BB in step S7 is completed, the determination unit 444 identifies an abnormality BE on the outer circumferential surface BA and the end face BB, as shown in FIG. 8 (step S8).
Before the process of step S8, the image processing unit 443 generates a two-dimensional image PA corresponding to the inspection position of each outer peripheral surface based on the inspection information of each outer peripheral surface. The image processing unit 443 generates a two-dimensional image PA corresponding to the inspection position of each end surface based on the inspection information of each end surface. The process in which the image processing unit 443 generates the two-dimensional image PA corresponding to the inspection position of the outer peripheral surface and the inspection position of the end surface constitutes an image processing step.
In step S8, the determination unit 444 identifies an abnormal portion BE in the area irradiated with the blue laser light from the inspection position of each outer peripheral surface on the outer peripheral surface BA based on the two-dimensional image PA corresponding to the inspection position of each outer peripheral surface. The determination unit 444 identifies an abnormal portion BE in the area irradiated with the blue laser light from the inspection position of each end surface on the end surface BB based on the two-dimensional image PA corresponding to the inspection position of each outer peripheral surface.

The determination unit 444 determines whether or not an abnormal point BE exists on the outer circumferential surface BA or the end surface BB based on the identification result in step S8 (step S9).
When the determination unit 444 determines that an abnormality location BE exists on the outer circumferential surface BA or the end surface BB (step S9: YES), the determination unit 444 determines the type of abnormality (step S10).
Before the process of step S10, if an abnormality BE exists on the outer peripheral surface BA, the image processing unit 443 generates a height image PB corresponding to the location of the abnormality BE based on the inspection information of the outer peripheral surface used in generating the two-dimensional image PA including the abnormality BE. If an abnormality BE exists on the end surface BB, the image processing unit 443 generates a height image PB corresponding to the location of the abnormality BE based on the inspection information of the end surface used in generating the two-dimensional image PA including the abnormality BE. The process in which the image processing unit 443 generates the height image PB corresponding to the location of the abnormality BE on the outer peripheral surface BA and the end surface BB constitutes an image processing step.
In step S10, the determination unit 444 determines that the type of abnormality in the abnormal area BE is a defect or a foreign substance, based on the height image PB generated by the image processing unit 443.

The process of step S10 may be performed as follows.
The image processing unit 443 generates a two-dimensional image PA and a height image PB corresponding to the inspection position of each outer peripheral surface and the inspection position of each end surface before the processing of step S8. The determination unit 444 may select a height image PB corresponding to the position where the abnormality portion BE exists from the height images PB generated by the image processing unit 443 in the processing of step S1, and determine the type of abnormality based on the selected height image PB.

The determination unit 444 determines whether the type of abnormality is a defect or not based on the determination result in step S10 (step S11).
When the determining unit 444 determines that the type of abnormality is a defect (step S11: YES), the determining unit 444 determines the type of the defect (step S12).
When the determination unit 444 uses the cross-sectional shape image PC in step S12, before the processing of step S12, the image processing unit 443 generates a cross-sectional shape image PC representing the cross-sectional shape of the defect based on the height image PB including the defect.
The determination unit 444 determines the type of defect based on a parameter obtained based on at least one of the height image PB and the cross-sectional shape image PC corresponding to the position where the defect exists, and a threshold value of the parameter.

After processing in step S12, if the determination unit 444 determines that no abnormality BE exists on the outer peripheral surface BA or the end surface BB (step S9: NO), or if the determination unit 444 determines that the type of abnormality is a foreign body rather than a defect (step S11: NO), the block shape calculation unit 445 calculates the length and diameter of the silicon single crystal block B (step S13).

The display control unit 446 causes the display unit 42 to display the test results (step S14).
In step S13, the display control unit 446 may cause the display unit 42 to display the presence or absence of foreign matter or defects and the type of defects as the inspection results, in the following manner.
The display control unit 446 causes the display unit 42 to display a figure obtained by developing the outer peripheral surface BA onto a plane and figures of both end surfaces BB. The display control unit 446 may cause the display unit 42 to display the location of the abnormal point BE or a predetermined range including the abnormal point BE in these figures in a first color corresponding to a foreign matter or a second color corresponding to a defect, and may also cause the display unit 42 to display the other areas in a third color.
The display control unit 446 may also cause the display unit 42 to display text indicating the position of the foreign substance or defect.
In step S14, the display control unit 446 causes the display unit 42 to display in text the length and diameter of the silicon single crystal block B as the inspection results.

[Effects of the First Embodiment]
The rotation mechanism 2 of the visual inspection device 1 rotates the cylindrical silicon single crystal block B once in the circumferential direction of the silicon single crystal block B under the control of the control device 4. The sensor 31 irradiates a laser beam onto the surface of the silicon single crystal block B rotating in the circumferential direction, and receives the laser beam reflected from the silicon single crystal block B. An image processing unit 443 of the control unit 44 constituting the control device 4 generates a height image PB of the surface based on the state of reception of the reflected light by the sensor 31. A determination unit 444 of the control unit 44 determines the properties of the surface based on the height image PB.
According to such an appearance inspection device 1, a height image PB in the circumferential direction of the silicon single crystal block B can be generated simply by rotating the silicon single crystal block B in its circumferential direction without moving the sensor 31 in the circumferential direction of the silicon single crystal block B. The appearance inspection device 1 can appropriately determine the properties of the surface of the silicon single crystal block B based on the height image PB generated using laser light. Therefore, it is possible to provide an appearance inspection device 1 that can appropriately inspect the appearance of the silicon single crystal block B.

The visual inspection device 1 includes a sensor moving mechanism 32 that moves the sensor 31 a predetermined distance along the surface of the silicon single crystal block B. The visual inspection device 1 rotates the silicon single crystal block B once and then stops it. While the silicon single crystal block B is rotating once, the sensor 31 irradiates the surface of the silicon single crystal block B with blue laser light, and the sensor 31 receives the light reflected by the surface of the silicon single crystal block B. When the silicon single crystal block B stops, the sensor moving mechanism 32 moves the sensor 31 a predetermined distance along the surface of the silicon single crystal block B, and the process is repeated.
Therefore, when the surface to be inspected is the outer peripheral surface BA, even if the irradiation range H of the blue laser light on the sensor 31 is shorter than the length of the outer peripheral surface BA in the direction of the central axis BC, the entire outer peripheral surface BA can be inspected by moving the sensor 31 along the outer peripheral surface BA in a direction parallel to the central axis BC by the sensor moving mechanism 32 every time the silicon single crystal block B irradiated with the blue laser light rotates once. When the surface to be inspected is the outer peripheral surface BA, even if the irradiation range H of the blue laser light on the sensor 31 is shorter than the length of the outer peripheral surface BA in the direction of the central axis BC, the entire outer peripheral surface BA can be inspected by moving the sensor 31 along the outer peripheral surface BA in a direction parallel to the central axis BC by the sensor moving mechanism 32 every time the silicon single crystal block B irradiated with the blue laser light rotates once.
Therefore, the appearance inspection device 1 can appropriately inspect the appearance of the silicon single crystal block B without using a sensor 31 with a wide irradiation range H of the blue laser light.

The sensor moving mechanism 32 includes a six-axis robot 321 that moves the single sensor 31 in the direction of the central axis BC along the outer circumferential surface BA of the silicon single crystal block B and in the radial direction of the silicon single crystal block B along the end face BB. The appearance inspection device 1 inspects the entire outer circumferential surface BA by moving the sensor 31 in the direction of the central axis BC along the outer circumferential surface BA of the silicon single crystal block B, and then inspects the entire end face BB by moving the sensor 31 in the radial direction of the silicon single crystal block B along the end face BB.
Therefore, the appearance of the entire silicon single crystal block B can be appropriately inspected by using only a single sensor 31 .

The rotating mechanism 2 rotates the silicon single crystal block B once alternately in different directions when inspecting the outer circumferential surface BA or the end surface BB.
Here, due to the influence of the shape of the outer peripheral surface BA of the silicon single crystal block B or the outer peripheral surface of the rotating roller 21, or the parallelism of the pair of rotating rollers 21, the silicon single crystal block B may be displaced in the direction of the central axis BC when the silicon single crystal block B is rotated once. In this case, if the silicon single crystal block B is rotated once in the same direction during inspection of the outer peripheral surface BA or the end surface BB, the silicon single crystal block B will be significantly displaced from the inspection start position. If such a positional displacement occurs, the deviation between the inspection position of the outer peripheral surface of the sensor 31 and the position in the direction of the central axis BC on the outer peripheral surface BA, which is set in advance for the inspection position of the outer peripheral surface, increases every time the silicon single crystal block B is rotated once in the same direction during inspection of the outer peripheral surface BA, and there is a risk that the outer peripheral surface BA cannot be properly inspected. The deviation of the distance from the sensor 31 to the end surface BB from the inspection distance K increases every time the silicon single crystal block B is rotated once in the same direction during inspection of the end surface BB, and there is a risk that the end surface BB cannot be properly inspected.
As in the first embodiment, by alternately rotating the silicon single crystal block B once in different directions when inspecting the outer peripheral surface BA, even if the silicon single crystal block B is displaced in the direction of the central axis BC when the silicon single crystal block B is rotated once, the silicon single crystal block B will be displaced in the opposite direction and return to its original position when it is next rotated in the opposite direction, so that it is possible to minimize the deviation between the inspection position of the outer peripheral surface of the sensor 31 and the position of the outer peripheral surface BA in the direction of the central axis BC that is preset for the inspection position of the outer peripheral surface. By alternately rotating the silicon single crystal block B once in different directions when inspecting the end face BB, it is possible to minimize the deviation of the distance from the sensor 31 to the end face BB from the inspection distance K for the same reason as when inspecting the outer peripheral surface BA.
Therefore, the appearance inspection device 1 can properly inspect the appearance of the outer peripheral surface BA and the end surface BB of the silicon single crystal block B.

The sensor 31 irradiates the silicon single crystal block B, which has a high reflectivity, with blue laser light.
In this way, by using blue laser light, which has a shorter wavelength than red laser light, the width of the irradiation range H can be reduced, and the appearance inspection device 1 can generate clear two-dimensional images PA and height images PB that are less affected by scattering.
Therefore, the visual inspection device 1 can more appropriately inspect the visual appearance of the outer peripheral surface BA and end surface BB of the silicon single crystal block B based on the clear two-dimensional image PA and height image PB.

The visual inspection device 1 rotates the silicon single crystal block B once with the notch BV as a reference.
In this manner, the visual inspection device 1 can control the rotation of the silicon single crystal block B by a simple method of simply using the conventional notch BV on the silicon single crystal block B as a reference.

The visual inspection device 1 generates a two-dimensional image PA of the surface of a silicon single crystal block B based on the reception state of the reflected light of the blue laser light, identifies abnormal points BE on the surface based on the two-dimensional image PA, and determines the presence or absence of defects on the surface based on a height image PB of the identified abnormal points BE.
Therefore, when no abnormal area BE is present, the appearance inspection device 1 does not need to generate a height image PB, and can perform inspection efficiently.

[Second embodiment]
[Configuration of visual inspection device]
Next, the configuration of a visual inspection apparatus according to a second embodiment of the present invention will be described.
Fig. 10 is a perspective view showing a schematic configuration of a visual inspection apparatus according to a second embodiment. Fig. 11 is a block diagram showing a schematic configuration of a control system of the visual inspection apparatus. Fig. 12 is a schematic diagram showing the movement state of a sensor during inspection, where (A) shows the movement state during inspection of an outer peripheral surface, and (B) shows the movement state during inspection of an end surface.
The same configurations as those in the first embodiment are given the same names and symbols, and descriptions thereof will be simplified or omitted.

The appearance inspection device 5 shown in FIG. 10 inspects the appearance of a silicon single crystal block B in the same manner as the appearance inspection device 1 of the first embodiment.
As shown in FIGS. 10 and 11 , the appearance inspection device 5 includes a rotation mechanism 2, an inspection unit 6, and a control device 7.

The inspection unit 6 includes a first sensor 61, a second sensor 62, and a sensor moving mechanism 63.

The first and second sensors 61, 62 each have the same configuration as the sensor 31 of the first embodiment. The first and second sensors 61, 62 each include a first and second sensor body 611, 621 having a first and second light incident/exit surface 611A, 621A, a first and second irradiating portion 612, 622 that irradiates blue laser light, and a first and second light receiving portion 613, 623, respectively.
The first irradiating unit 612 of the first sensor 61 irradiates the outer peripheral surface BA with blue laser light. As shown in Fig. 12A, when the distance from the first light incident/exiting surface 611A to the outer peripheral surface BA is an inspection distance K, the blue laser light irradiated from the first light incident/exiting surface 611A is irradiated so that the length of the irradiation range H is shorter than the length of the outer peripheral surface BA in the front-rear direction.
The second irradiating unit 622 of the second sensor 62 irradiates the end face BB with blue laser light. The blue laser light irradiated from the second light incident/exiting surface 621A is irradiated so that the length of the irradiation range H is shorter than the radius of the end face BB when the distance from the first light incident/exiting surface 611A to the end face BB is an inspection distance K, as shown in FIG.
The first light receiving unit 613 receives the light reflected by the outer circumferential surface BA, and outputs a signal corresponding to the light receiving state to the control device 7. The second light receiving unit 623 receives the light reflected from the end surface BB, and outputs a signal corresponding to the light receiving state to the control device 7.

The sensor moving mechanism 63 includes a single-axis actuator 631 as a first moving mechanism, and a six-axis robot 321 as a second moving mechanism.
The single-axis actuator 631 holds the first sensor 61 and moves the first sensor 61 back and forth on the right side of the outer circumferential surface BA of the silicon single crystal block B based on the control of the control device 7 .
The six-axis robot 321 holds the second sensor 62 and moves the second sensor 62 up and down to a position facing the rear end face BB of the silicon single crystal block B based on the control of the control device 7 .

11 , the control device 7 includes an input unit 41, a display unit 42, a storage unit 43, and a control unit 74. The roller driving unit 22, the first irradiation unit 612, the first light receiving unit 613, the second irradiation unit 622, the second light receiving unit 623, the single-axis actuator 631, the six-axis robot 321, the input unit 41, the display unit 42, and the storage unit 43 are electrically connected to the control unit 74.
The control unit 74 has the same configuration as the control unit 44 of the first embodiment, except that an inspection control unit 742 is different from the inspection control unit 442 of the first embodiment.

The inspection control unit 742 controls the roller drive unit 22 and the single-axis actuator 631 to inspect the outer peripheral surface BA of the silicon single crystal block B. The inspection control unit 742 controls the roller drive unit 22 and the six-axis robot 321 to inspect the end surface BB of the silicon single crystal block B.

When inspecting the outer peripheral surface BA, the inspection control unit 742 controls the single-axis actuator 631 to position the first sensor 61 at the inspection position of the first outer peripheral surface with the first light incident/exit surface 611A facing the outer peripheral surface BA on the right side of the outer peripheral surface BA of the silicon single crystal block B, as shown by the solid line in Fig. 12 (A). The inspection position of the first outer peripheral surface in the second embodiment is different from the inspection position of the first outer peripheral surface in the first embodiment, which is located above the outer peripheral surface BA, in that it is located on the right side of the outer peripheral surface BA, but the position in the front-rear direction is the same as the inspection position of the first outer peripheral surface in the first embodiment. The inspection control unit 742 controls the roller driving unit 22 to rotate the silicon single crystal block B once and to irradiate the outer peripheral surface BA with blue laser light from the first irradiation unit 612.
When the inspection control unit 742 acquires a signal corresponding to the light receiving state from the first light receiving unit 613 which receives the light reflected by the outer circumferential surface BA, it generates inspection information for the first outer circumferential surface and stores it in the memory unit 43.

After that, the inspection control unit 742 controls the single-axis actuator 631 to sequentially move the first sensor 61 along the central axis BC to the inspection position of the Nth outer peripheral surface, as shown by the two-dot chain line in FIG. 12A (FIG. 12A shows only the first sensor 61 at the inspection position of the second outer peripheral surface). The inspection position of the Nth outer peripheral surface in the second embodiment is different from the inspection position of the Nth outer peripheral surface in the first embodiment, which is located above the outer peripheral surface BA, in that it is located to the right of the outer peripheral surface BA, but the position in the front-rear direction is the same as the inspection position of the Nth outer peripheral surface in the first embodiment. In other words, the inspection position of the Nth outer peripheral surface is a position where the overlap width between the irradiation range H of the blue laser light irradiated from the inspection position of the Nth outer peripheral surface and the irradiation range H of the blue laser light irradiated from the inspection position of the (N-1)th outer peripheral surface is width D1. The width D1 is a value exceeding 0 mm. The inspection control unit 742 rotates the silicon single crystal block B once each time the first sensor 61 is positioned at the inspection position of the Nth outer peripheral surface, and irradiates blue laser light from the first irradiation unit 612 to the outer peripheral surface BA, generates inspection information for the Nth outer peripheral surface, and stores it in the memory unit 43.
The inspection control unit 742, like the inspection control unit 442 of the first embodiment, repeats the above-mentioned processing until the inspection is completed in a state where the front end of the irradiation range H is located forward of the front end face BB and the rear end is located on the outer circumferential surface BA.

When inspecting the end face BB, the inspection control unit 742 controls the six-axis robot 321 to position the second sensor 62 at the inspection position for the first end face with the second light incident/exit surface 621A facing the end face BB, as shown by the solid line in Fig. 12(B). The inspection position for the first end face in the second embodiment is the same as the inspection position for the first end face in the first embodiment. The inspection control unit 742 rotates the silicon single crystal block B once and causes the second irradiation unit 622 to irradiate the end face BB with blue laser light.
When the inspection control unit 742 acquires a signal corresponding to the light receiving state from the second light receiving unit 623 that receives the reflected light from the end face BB, it generates inspection information for the first end face and stores it in the memory unit 43.

Thereafter, the inspection control unit 742 controls the six-axis robot 321 to sequentially move the second sensor 62 along the vertical direction to the inspection position of the Mth end face, as shown by the two-dot chain line in FIG. 12(B) (only the second sensor 62 at the inspection position of the second end face is shown in FIG. 12(B)). The inspection position of the Mth end face is a position where the overlap width between the irradiation range H of the blue laser light irradiated from the inspection position of the Mth end face and the irradiation range H of the blue laser light irradiated from the inspection position of the (M-1)th end face is width D2. The width D2 is a value exceeding 0 mm, and may be the same as or different from the width D1. In other words, the first distance over which the first sensor 61 moves and the second distance over which the second sensor 62 moves may be the same as or different from each other. The inspection control unit 742 rotates the silicon single crystal block B once each time the second sensor 62 reaches the inspection position for the Mth end face, and irradiates blue laser light from the second irradiation unit 622 onto the end face BB, generates inspection information for the Mth end face, and stores it in the memory unit 43.
The inspection control unit 742, like the inspection control unit 442 of the first embodiment, repeats the above-mentioned processing until the inspection is completed in a state where the lower end of the irradiation range H is located below the central axis BC and the upper end is located above the central axis BC.

[Operation of visual inspection device]
Next, as an operation of the visual inspection device 5, a visual inspection process for the silicon single crystal block B will be described.
Fig. 13 is a flowchart of the appearance inspection process, and Figs. 14 and 15 are flowcharts of the inspection process for the outer circumferential surface and end surface.
The same processes as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted.
The processes of steps S41 to S43, S3, and S4 shown in FIG. 13, the processes of steps S21, S24, S51 to S54, S57, and S58 shown in FIG. 14, and the processes of steps S55, S56, S59, and S60 shown in FIG. 15 constitute a surface inspection process.

Before or after the silicon single crystal block B is set on the pair of rotating rollers 21, the block information acquisition unit 441 of the control unit 74 constituting the visual inspection device 5 acquires block information as shown in FIG. 13 (step S1).

When the inspection control unit 742 of the control unit 74 receives an instruction to start inspection, it controls the single-axis actuator 631 to move the first sensor 61 to an inspection position on the first outer peripheral surface on the right side of the outer peripheral surface BA of the silicon single crystal block B (step S41).
The inspection control unit 742 controls the six-axis robot 321 to move the second sensor 62 to an inspection position for the first end face opposing the rear end face BB of the silicon single crystal block B (step S42).
The inspection control unit 742 may perform the process of step S42 before the process of step S41, or may perform the process of step S41 at the same time.

The inspection control unit 742 rotates the silicon single crystal block B so that the notch BV is located at the reference position (step S3).
The inspection control unit 742 detects the edge of the silicon single crystal block B (step S4).

The inspection control unit 742 performs an inspection process for the outer circumferential surface BA and the end surface BB (step S43).
In the inspection process of the outer circumferential surface BA and the end surface BB in step S43, the inspection control unit 742 sets the set rotation direction of the silicon single crystal block B to the first direction as shown in FIG. 14 (step S21).

The inspection control unit 742 sets the surfaces to be inspected to the outer peripheral surface BA and the end surface BB (step S51).

The inspection control unit 742 inspects the inspection target surface while rotating the silicon single crystal block B once in the set rotation direction (step S52).
In step S52, the inspection control unit 742 controls the roller driving unit 22 to rotate the silicon single crystal block B once in the set rotation direction.
When the surface to be inspected includes the outer peripheral surface BA, the inspection control unit 742 controls the first irradiation unit 612 to irradiate the outer peripheral surface BA with blue laser light while the silicon single crystal block B is rotating, and when a signal corresponding to the light receiving state is obtained from the first light receiving unit 613, generates inspection information of the outer peripheral surface corresponding to the inspection position of the outer peripheral surface of the first sensor 61 and stores it in the memory unit 43.
When the inspection control unit 742 includes the end face BB in the surface to be inspected, it controls the second irradiation unit 622 to irradiate the end face BB with blue laser light while the silicon single crystal block B is rotating, and when it acquires a signal corresponding to the light receiving state from the second light receiving unit 623, it generates end face inspection information corresponding to the inspection position of the end face of the second sensor 62 and stores it in the memory unit 43.

The inspection control unit 742 determines whether or not the inspection of both the entire outer peripheral surface BA and the entire end surface BB has been completed (step S53). The determination criteria in step S53 may be, for example, the same as those in steps S23 and S33 in the first embodiment.
If the inspection control unit 742 determines that inspection of both the entire outer circumferential surface BA and the entire end surface BB has been completed (step S53: YES), it ends the inspection process of the outer circumferential surface BA and the end surface BB.
On the other hand, if the inspection control unit 742 determines that inspection of at least one of the entire outer peripheral surface BA and the entire end surface BB has not been completed (step S53: NO), it sets the set rotation direction of the silicon single crystal block B to the opposite direction to that during the previous inspection (step S24).

The inspection control unit 742 determines whether or not inspection of only the entire end face BB has been completed (step S54).
If the inspection control unit 742 determines that inspection of only the entire end surface BB has not been completed (step S54: NO), it determines whether inspection of only the entire outer peripheral surface BA has been completed (step S55), as shown in Figure 15.
If the inspection control unit 742 determines that inspection of only the entire outer peripheral surface BA has not been completed (step S55: NO), that is, if it determines that inspection of both the entire outer peripheral surface BA and the entire end face BB has not been completed, it controls the single-axis actuator 631 to move the first sensor 61 to the inspection position for the next outer peripheral surface, and controls the six-axis robot 321 to move the second sensor 62 to the inspection position for the next end face (step S56).
As shown in FIG. 14, the inspection control unit 742 sets the inspection target surfaces to the outer peripheral surface BA and the end surface BB (step S51), and inspects the inspection target surfaces while rotating the silicon single crystal block B once in the set rotation direction (step S52).

If the inspection control unit 742 determines that inspection of only the entire end face BB has been completed (step S54: YES), it controls the single-axis actuator 631 to move the first sensor 61 to the inspection position for the next outer peripheral surface (step S57).
The inspection control unit 742 sets the inspection target surface to the outer circumferential surface BA (step S58), and inspects the inspection target surface while rotating the silicon single crystal block B once in the set rotation direction (step S52).

As shown in FIG. 15, when the inspection control unit 742 determines that inspection of only the entire outer peripheral surface BA has been completed (step S55: YES), it controls the six-axis robot 321 to move the second sensor 62 to the inspection position for the next end face (step S59).
The inspection control unit 742 sets the inspection target surface to the end surface BB (step S60), and inspects the inspection target surface while rotating the silicon single crystal block B once in the set rotation direction, as shown in FIG. 14 (step S52).
The inspection control unit 742 repeats the above-described process until it determines in step S53 that inspection of both the entire outer circumferential surface BA and the entire end surface BB has been completed.

When the inspection process of the outer peripheral surface BA and the end surface BB in step S43 is completed, the control unit 74 performs the processes of steps S8 to S14 shown in FIG. 7.

[Effects of the second embodiment]
The visual inspection device 5 can achieve the following effects in addition to the effects achieved by the visual inspection device 1 of the first embodiment.
The visual inspection device 5 includes a sensor moving mechanism 63 having a single-axis actuator 631 for moving the first sensor 61 along the outer circumferential surface BA in the direction of the central axis BC of the silicon single crystal block B, and a six-axis robot 321 for moving the second sensor 62 along the end face BB in the radial direction of the silicon single crystal block B. The visual inspection device 5 rotates the silicon single crystal block B once and stops it, and while the silicon single crystal block B is rotating once, irradiates the outer circumferential surface BA with blue laser light from the first sensor 61 and receives the reflected light with the first sensor 61, and irradiates the end face BB with blue laser light from the second sensor 62 and receives the reflected light with the second sensor 62. When the silicon single crystal block B stops, the visual inspection device 1 repeats the process of moving the first sensor 61 a first distance along the outer peripheral surface BA in the direction of the central axis BC of the silicon single crystal block B, and moving the second sensor 62 a second distance in the radial direction of the silicon single crystal block B along the end face BB.
In this manner, by simultaneously inspecting the outer peripheral surface BA and the end surface BB while the silicon single crystal block B is rotating, the inspection efficiency can be improved.

[Modification]
Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and various improvements and design changes that do not deviate from the gist of the present invention are also included in the present invention.

For example, in the first embodiment, the visual inspection device 1 may be configured to inspect only the outer peripheral surface BA or the end face BB of the silicon single crystal block B. When the visual inspection device 1 is configured to inspect only the outer peripheral surface BA, the width of the irradiation range H of the blue laser light from the sensor 31 may be made longer than the length of the outer peripheral surface BA in the direction of the central axis BC, and the visual inspection device 1 may not need to be provided with the sensor moving mechanism 32. When the visual inspection device 1 is configured to inspect only the end face BB, the width of the irradiation range H of the blue laser light from the sensor 31 may be made longer than the radial length of the end face BB, and the visual inspection device 1 may not need to be provided with the sensor moving mechanism 32.
In the second embodiment, the width of the irradiation range H of the blue laser light from the first sensor 61 is made longer than the length of the outer peripheral surface BA in the direction of the central axis BC, so that it is not necessary to provide a single-axis actuator 631 in the appearance inspection device 5, and the width of the irradiation range H of the blue laser light from the first sensor 61 is made longer than the radial length of the end face BB, so that it is not necessary to provide a six-axis robot 321 in the appearance inspection device 5.
In the first embodiment, instead of the six-axis robot 321, a three-axis robot that moves the sensor 31 in the forward/backward or upward/downward direction and rotates it around one axis may be used.
In the second embodiment, a six-axis robot 321 may be applied as a configuration for moving the first sensor 61, a single-axis actuator 631 may be applied as a configuration for moving the second sensor 62, or a linear movement mechanism or a three-axis robot other than the single-axis actuator 631 may be applied as a configuration for moving the first and second sensors 61, 62.

In the first and second embodiments, the rotation direction of the silicon single crystal block B is changed every time the silicon single crystal block B is rotated once, but if the amount of deviation of the silicon single crystal block B when the silicon single crystal block B is rotated once is extremely small, the rotation direction of the silicon single crystal block B may be changed every time the silicon single crystal block B is rotated once in the same direction a plurality of times, or the silicon single crystal block B may be rotated continuously in the same direction. If there is no deviation of the silicon single crystal block B when the silicon single crystal block B is rotated once, the silicon single crystal block B may be rotated continuously in the same direction.
In the first and second embodiments, an orientation flat may be formed in the silicon single crystal block B instead of the notch BV, and the silicon single crystal block B may be rotated once with the orientation flat as a reference.

In the first and second embodiments, a red laser light may be used instead of the blue laser light.
In the second embodiment, the width of the illumination range H of the first sensor 61 and the width of the illumination range H of the second sensor 62 may be different.

In the first and second embodiments, at least one of the two-dimensional image PA and the cross-sectional shape image PC does not have to be generated.
In the first and second embodiments, the object to be inspected is not limited to the silicon single crystal block B, and the material thereof is not limited as long as it has a columnar or cylindrical shape.

1, 5...visual inspection device, 2...rotation mechanism, 31...sensor, 32, 63...sensor movement mechanism, 61...first sensor, 62...second sensor, 321...six-axis robot (second movement mechanism), 443...image processing unit, 444...determination unit, 631...single-axis actuator (first movement mechanism), B...single crystal silicon block, BA...outer periphery, BB...end face, BC...center axis, BD...chamfered portion, BE...abnormal area, BV...notch, PA...two-dimensional image, PB...height image, PC...cross-sectional shape image.

Claims (16)

A visual inspection apparatus for inspecting the visual appearance of a cylindrical or columnar object to be inspected, comprising:
a rotation mechanism that rotates the object under test in a circumferential direction of the object under test;
a sensor that irradiates a laser beam onto a surface of the object being inspected while rotating in the circumferential direction and receives a reflected light of the laser beam reflected by the surface of the object being inspected;
an image processing unit that generates a height image of the surface based on a receiving state of the reflected light;
A determination unit that determines a property of the surface based on the height image. 2. The visual inspection apparatus according to claim 1,
a sensor moving mechanism for moving the sensor along the surface;
The rotation mechanism rotates the object under test once in the circumferential direction,
The sensor irradiates the surface of the object under test with the laser light while the object under test is rotating once, and receives the reflected light reflected by the surface of the object under test;
The sensor moving mechanism moves the sensor a predetermined distance along the surface each time the object under inspection rotates once. 3. The visual inspection apparatus according to claim 2,
The rotation mechanism rotates the object under inspection once in the same direction a predetermined number of times, and changes the rotation direction to the opposite direction every time. 4. The visual inspection apparatus according to claim 2,
An appearance inspection device in which the sensor moving mechanism moves a single sensor along the outer peripheral surface as the surface in a direction parallel to the central axis of the object to be inspected, and moves the sensor in the radial direction of the object to be inspected along the end face as the surface. 4. The visual inspection apparatus according to claim 2,
The sensor moving mechanism includes:
a first moving mechanism that moves the first sensor along an outer circumferential surface as the surface in a direction parallel to a central axis of the test object;
a second moving mechanism that moves the second sensor in a radial direction of the object to be inspected along the end face as the surface. 2. The visual inspection apparatus according to claim 1,
The appearance inspection apparatus, wherein the laser light is a blue laser light. 2. The visual inspection apparatus according to claim 1,
The image processing unit generates a two-dimensional image of the surface based on a receiving state of the reflected light,
The judgment unit identifies an abnormal portion on the surface based on the two-dimensional image, and judges the presence or absence of a defect on the surface based on the height image of the identified abnormal portion. 1. A visual inspection method for inspecting the visual appearance of a cylindrical or columnar object to be inspected, comprising the steps of:
a surface inspection process of rotating the object under inspection once in a circumferential direction of the object under inspection, irradiating a laser beam from a sensor onto a surface of the object under inspection rotating in the circumferential direction, and receiving the reflected light of the laser beam reflected on the surface of the object under inspection by the sensor;
an image processing step of generating a height image of the surface based on a reception state of the reflected light;
and a determination step of determining a property of the surface based on the height image. 9. The appearance inspection method according to claim 8,
The surface inspection step includes:
A visual inspection method comprising: rotating the object under inspection once in the circumferential direction and then stopping the rotation; irradiating the laser light from the sensor onto the surface while the object under inspection is rotating once; receiving the light reflected from the surface by the sensor; and repeating the process of moving the sensor a predetermined distance along the surface once the object under inspection has stopped. 9. The appearance inspection method according to claim 8,
The surface inspection step includes:
An outer peripheral surface inspection process;
An end face inspection step is performed before or after the outer circumferential surface inspection step,
The outer circumferential surface inspection step includes:
the object to be inspected is rotated once in the circumferential direction and then stopped; while the object to be inspected is rotating once, the laser light is irradiated from the single sensor onto the outer peripheral surface as the surface, the light reflected from the outer peripheral surface is received by the single sensor; when the object to be inspected is stopped, the single sensor is moved a predetermined distance along the outer peripheral surface in a direction parallel to the central axis of the object to be inspected;
The end face inspection step includes:
A visual inspection method comprising: rotating the object under inspection once in the circumferential direction and then stopping the rotation; irradiating the laser light from the single sensor onto an end face serving as the surface while the object under inspection is rotating once, and receiving the reflected light by the single sensor; and, once the object under inspection has stopped, repeating the process of moving the single sensor a predetermined distance in the radial direction of the object under inspection along the end face. 9. The appearance inspection method according to claim 8,
The surface inspection step includes:
an appearance inspection method comprising: rotating the object under inspection once in the circumferential direction and then stopping the same; and, while the object under inspection is rotating once, irradiating the laser light from a first sensor onto an outer peripheral surface as the surface, and receiving the reflected light reflected from the outer peripheral surface by the first sensor; irradiating the laser light from a second sensor onto an end surface as the surface, and receiving the reflected light reflected from the end surface by the second sensor; and, when the object under inspection is stopped, moving the first sensor along the outer peripheral surface a first distance in a direction parallel to a central axis of the object under inspection, and moving the second sensor along the end surface a second distance in the radial direction of the object under inspection, repeating the process. The appearance inspection method according to any one of claims 9 to 11,
The surface inspection step is a visual inspection method in which, when rotating the object to be inspected once in the circumferential direction, the rotation direction is changed to the opposite direction every time the object to be inspected is rotated once in the same direction a predetermined number of times. The appearance inspection method according to claim 12,
A visual inspection method, wherein the object to be inspected is a cylindrical silicon single crystal block obtained by cutting a silicon single crystal. The appearance inspection method according to claim 13,
The surface inspection step is a visual inspection method in which a notch in the silicon single crystal block is detected when the object to be inspected is rotated once in the circumferential direction, and the silicon single crystal block is rotated once based on the notch. The appearance inspection method according to claim 13,
The appearance inspection method, wherein the laser light is a blue laser light. 9. The appearance inspection method according to claim 8,
The image processing step generates a two-dimensional image of the surface based on a receiving state of the reflected light,
The determination step is a visual inspection method for identifying an abnormality on the surface based on the two-dimensional image, and determining the presence or absence of a defect on the surface based on the height image of the identified abnormality.

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