Optical displacement gauge

Abstract

To suppress an error in height data in a displacement gauge for measuring displacement by rotating a light projection / reception module relative to a still work.SOLUTION: An optical displacement gauge includes: a light projection section for applying slit light to a work; an image sensor for outputting a light reception quantity distribution of reflection light from the work; a motor for integrally rotating the light projection section and the image sensor; a control section for controlling the motor, and permits scanning by slit light and rotating the image sensor and exposing it to light; and a rotational angle acquisition section for acquiring a reference angle corresponding to a light exposure period of the image sensor. The control section acquires a peak position in a V direction of a light reception quantity distribution obtained while rotating the image sensor during a light exposure period, estimates a representative angle in which a peak position is acquired on the basis of a reference angle corresponding to a light exposure period and a control condition of the image sensor or the motor, and calculates the height of a work at the representative angle from the peak position.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present disclosure relates to an optical displacement meter that uses light to measure the displacement of a workpiece. [Background technology]

[0002] As an optical displacement meter, for example, there is a known one that is configured to acquire an XZ cross-sectional profile by irradiating a slit light extending in the X direction onto a workpiece and receiving the light reflected by the surface of the workpiece with an image sensor. It is possible to generate data on the three-dimensional shape of a workpiece by acquiring multiple XZ cross-sectional profiles at different positions in the Y direction of the workpiece, but in this case, equipment such as a conveyor for transporting the workpiece in the Y direction and a linear motion mechanism for moving the displacement meter body in the Y direction relative to the workpiece is required, which can make its introduction difficult.

[0003] In response to this, for example, as disclosed in Patent Documents 1 and 2, a light-projecting system that projects a slit light and a light-receiving system that receives the reflected light (collectively referred to as the light-projecting and receiving system) are configured to be rotatable, and the light-projecting and receiving system is rotated so that the slit light is scanned in the Y direction relative to the workpiece. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Publication No. 3232152 [Patent Document 2] China Utility Model Registration No. 210664364 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, for example, when the displacement gauge body is moved by a linear motion mechanism, the displacement gauge body continues to move relative to the workpiece during the exposure period for generating one profile. At this time, the positional relationship between the optical system of the displacement gauge body and the reference surface on which the workpiece is placed does not substantially change, so no error due to relative movement occurs in the obtained height data.

[0006] However, when measuring a stationary workpiece by rotating the light projecting and receiving system as in Patent Documents 1 and 2, the measurement area becomes arc-shaped as the light projecting and receiving system rotates, so the positional relationship between the optical system and the reference surface on which the workpiece is placed changes depending on the rotation angle of the light projecting and receiving system. Therefore, the height data obtained during the exposure period is not the height at the start of the exposure period, which causes an error in the height data.

[0007] The present disclosure has been made in consideration of such points, and its purpose is to suppress errors in height data in a displacement meter that measures the height of a stationary workpiece by rotating a light emitting and receiving module. [Means for solving the problem]

[0008] In order to achieve the above object, the present embodiment can be based on an optical displacement meter that uses light to measure the displacement of a workpiece. The optical displacement meter includes a light projection unit that irradiates a workpiece with slit light extending in the X direction, an image sensor that has a plurality of pixels two-dimensionally arranged in a U direction corresponding to the X direction and a V direction perpendicular to the U direction and outputs a distribution of the amount of light reflected from the workpiece by the plurality of pixels, a motor that rotates the light projection unit and the image sensor together, a control unit that controls the motor to scan the slit light in a direction perpendicular to the X direction and expose the image sensor while rotating in that direction, and a rotation angle acquisition unit that acquires a reference angle corresponding to an exposure period of the image sensor, and the control unit acquires a peak position in the V direction of the distribution of the amount of light received obtained by accumulating electric charges in the plurality of pixels while rotating the image sensor during the exposure period, estimates a representative angle at which the peak position is acquired based on the reference angle corresponding to the exposure period and a control condition of the image sensor or the motor, and calculates the height of the workpiece in the Z direction at the representative angle from the peak position.

[0009] According to this configuration, when the light projector and the image sensor are rotated integrally by a motor, the slit light extending in the X direction scans the workpiece in a direction perpendicular to the X direction. This makes it possible to measure the height of the workpiece at different positions and generate cross-sectional profiles at different positions in the scanning direction without requiring equipment such as a conveyor for transporting the workpiece in the Y direction and a linear motion mechanism for moving the displacement gauge body in the Y direction relative to the workpiece.

[0010] Although the reference angle corresponding to the exposure period is acquired by the rotation angle acquisition unit at a predetermined timing, since the rotational motion continues during the exposure period, if the peak position in the V direction of the light receiving amount distribution acquired by the control unit corresponds to a rotation angle at a timing different from the above-mentioned predetermined timing of the exposure period, an error occurs when calculating the height from the reference angle and the peak position in the V direction. Therefore, by estimating the representative angle at which the peak position in the V direction is acquired based on the control conditions of the image sensor or motor, it becomes possible to obtain accurate height data in the Z direction at the representative angle. Effect of the Invention

[0011] As described above, the representative angle is estimated based on the control conditions of the image sensor or motor and the reference angle, so that errors in the height data can be suppressed when measuring the height of a stationary workpiece by rotating the light projecting and receiving module. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram illustrating an operation of the optical displacement meter according to the first embodiment of the present invention. [Diagram 2] 1 is a perspective view of an optical displacement meter according to a first embodiment of the present invention, as viewed from above. [Diagram 3] FIG. 1 is a perspective view of an optical displacement meter according to a first embodiment of the present invention, as viewed from below. [Figure 4] 1 is a plan view showing the inside of an upper space of an optical displacement meter according to a first embodiment of the present invention. [Diagram 5] 1 is a plan view of a light projecting and receiving module of an optical displacement meter according to a first embodiment of the present invention. [Figure 6] FIG. 1 is a block diagram showing a configuration of an optical displacement meter according to a first embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 3 is a cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 1 is a diagram illustrating a displacement measurement technique. [Figure 10]FIG. 4 is a diagram illustrating the shape of a measurement region. [Figure 11] 10 is a timing chart showing exposure timing when the light emitting and receiving module is rotated in both directions. [Figure 12] 4 is a timing chart showing a correction amount of an encoder correction value. [Figure 13] FIG. 1 is a diagram illustrating an example of HDR. [Figure 14] 10 is a timing chart illustrating a method of synchronizing exposure timing when the light emitting and receiving modules are rotated in both directions. [Figure 15] FIG. 13 is a diagram illustrating an example of a correction table. [Figure 16] 1 is a graph showing measurement errors according to the present invention and a comparative example. [Figure 17] FIG. 7 is a view corresponding to FIG. 5 according to a first modified example of the first embodiment. [Figure 18] FIG. 5 is a view corresponding to FIG. 4 and relating to Modification 2 of Embodiment 1. [Figure 19] 13 is a bottom view of the internal structure of an optical displacement meter according to a second modified example of the first embodiment. FIG. [Figure 20] FIG. 4 is a view corresponding to FIG. 2 according to the second embodiment. [Figure 21] FIG. 11 is a diagram showing the internal structure of the optical displacement meter according to the second embodiment as viewed from above. [Figure 22] FIG. 8 is a view corresponding to FIG. 7 according to the second embodiment. [Figure 23] FIG. 21 according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its applications, or its uses.

[0014] (Embodiment 1) 1 is a diagram for explaining an optical displacement meter 1 according to a first embodiment of the present invention during operation. The optical displacement meter 1 is an example of a light-cutting type optical displacement meter that uses a slit light S1 to measure a cross-sectional profile of a workpiece W (measurement object) having a height in the Z direction based on the principle of triangulation. In this embodiment, an example will be described in which an inspection system S is configured by the optical displacement meter 1, a controller 2, and a personal computer PC, but the present invention is not limited to this configuration example, and for example, the inspection system S may include a PLC (programmable logic controller) or the like.

[0015] When setting up the inspection system S before it is put into operation, various inspection settings can be made, for example, by the controller 2 and personal computer PC. When it is put into operation after setting up, the optical displacement meter 1 measures the displacement of the workpiece W at a predefined timing. Data indicating the measurement results is sent from the optical displacement meter 1 to the controller 2 and personal computer PC, and an inspection based on the inspection settings is performed. Data indicating the measurement results of the optical displacement meter 1, the inspection results, etc. can be saved in the controller 2 and personal computer PC.

[0016] During operation, it is possible to operate the system using only the optical displacement meter 1 without using the controller 2 and the personal computer PC, and the operation form is not limited to that shown in Fig. 1. In the following explanation, the inspection system S is explained as including the optical displacement meter 1, but the present invention is also applicable to the case where the system is operated using only the optical displacement meter 1, or the case where the system is operated using a combination of the optical displacement meter 1 and a PLC.

[0017] The inspection system S is a system that performs an in-line visual inspection of the workpiece W. In an in-line visual inspection, for example, in a site where a plurality of workpieces W are transported in sequence, visual inspection of the workpieces W is performed in sequence. The X-direction, Y-direction, and Z-direction of the workpiece W are defined as shown in FIG. 1. In a plan view of the workpiece W, the X-direction and the Y-direction are directions perpendicular to each other. The Z-direction is the height direction of the workpiece W, and is a direction perpendicular to the X-direction and perpendicular to the Y-direction. The X-direction of the workpiece W can also be called the depth direction of the workpiece W, and the Y-direction of the workpiece W can also be called the width direction of the workpiece W, but this definition is merely an example, and the definitions of the X-direction, Y-direction, and Z-direction of the workpiece W are arbitrary.

[0018] Since the height data of the workpiece W can be acquired by the optical displacement meter 1, the appearance inspection includes dimensional inspection, shape inspection, defect inspection, etc. based on the height data. The workpiece W is not particularly limited, and examples include various parts, members, devices, instruments, parts of them, etc. The workpiece W can also be called a measurement object. After the workpiece W is transported to a measurable area of ​​the optical displacement meter 1 by a transport device not shown, the optical displacement meter 1 measures the displacement.

[0019] The optical displacement meter 1 is used in a state where it is fixed to a mounting member 5, for example. The mounting member 5 is a part of equipment installed in a factory or the like, and is fixed so as not to move relative to the workpiece W. Therefore, the optical displacement meter 1 does not move relative to the workpiece W. Although details will be described later, even if the optical displacement meter 1 is fixed to the mounting member 5, by making the internal light projecting and receiving module 10 (shown in FIG. 4) rotatable around an axis parallel to the X direction, it becomes possible to scan the slit light S1 extending in the X direction of the workpiece W from the light projecting and receiving module 10 in a direction perpendicular to the X direction of the workpiece W, and receive the reflected light S2 reflected at multiple points in the Y direction on the surface W1 of the workpiece W by the light projecting and receiving module 10. In this way, even when the light projecting and receiving module 10 is rotated around an axis parallel to the X direction, the slit light S1 can be scanned on the surface W1 of the workpiece W as in the case where the workpiece W or the optical displacement meter 1 is moved linearly. In addition, since the optical displacement meter 1 scans the slit light S1 by rotating the light emitting / receiving module 10, the scanning direction of the slit light S1 is a direction perpendicular to the X direction in the YZ plane, including the Y direction. In this specification, "rotation" refers to a swinging motion reciprocating around a rotation axis.

[0020] By performing signal processing based on the amount of received reflected light S2, multiple cross-sectional profiles of the workpiece W at different rotation angles can be obtained. Based on the obtained cross-sectional profiles, it is possible to generate data (height data) of the three-dimensional shape of the workpiece W. Note that since the slit light S1 rotates, the cross-sectional profiles are not necessarily parallel to the XZ plane.

[0021] As described above, by making the light emitting / receiving module 10 provided inside the optical displacement gauge 1 rotatable, it is possible to obtain multiple cross-sectional profiles of the workpiece W at different rotation angles without transporting the workpiece W in the Y direction and without moving the optical displacement gauge 1 in the Y direction relative to the workpiece W. Therefore, equipment such as a conveyor for transporting the workpiece W and a linear motion mechanism for moving the optical displacement gauge 1 in the Y direction relative to the workpiece W is not required, making it easy to introduce an inspection process using the optical displacement gauge 1.

[0022] The workpiece W may be movable relative to the optical displacement meter 1, but multiple cross-sectional profiles can be obtained with the workpiece W stopped during measurement. The optical displacement meter 1 may be movable relative to the workpiece W, but multiple cross-sectional profiles can be obtained with the optical displacement meter 1 stopped during measurement. The present invention is not limited to the case where the optical displacement meter 1 is completely fixed, but may be movably supported by the mounting member 5, or may be attached to a robot arm or the like and movable to any measurement location.

[0023] FIG. 2 is a perspective view of the optical displacement meter 1 according to the first embodiment of the present invention as viewed from above, and FIG. 3 is a perspective view of the optical displacement meter 1 according to the first embodiment of the present invention as viewed from below. As shown in each figure, the left-right direction, depth direction, and up-down direction of the optical displacement meter 1 are defined, but this is for the convenience of explanation and does not limit the posture of the optical displacement meter 1 during operation. In the operation form shown in FIG. 1, the optical displacement meter 1 is installed above the workpiece W, so that the slit light S1 is irradiated downward and the reflected light S2 travels upward. In this operation form, the left-right direction of the optical displacement meter 1 corresponds to the Y direction of the workpiece W, the up-down direction of the optical displacement meter 1 corresponds to the X direction of the workpiece W, and the depth direction of the optical displacement meter 1 corresponds to the Z direction of the workpiece W. Furthermore, the optical displacement gauge 1 may be installed so that the slit light S1 is irradiated horizontally onto the workpiece W, or the optical displacement gauge 1 may be installed so that the slit light S1 is irradiated downward onto the workpiece W, and the orientation of the optical displacement gauge 1 when installed is not particularly limited.

[0024] FIG. 4 is a diagram showing the internal structure of the optical displacement meter 1. The optical displacement meter 1 includes a light emitting / receiving module 10 (also shown in FIG. 5), a motor 20 (shown in FIG. 7) for rotating the light emitting / receiving module 10, a motor control unit 30 (shown in FIG. 8), and a housing 40. The light emitting / receiving module 10, the motor 20, and the motor control unit 30 are stored in the housing 40. As shown in FIG. 6, in the first embodiment, the control unit 3 is configured by the motor control unit 30, a power supply unit 34 (described later), and a signal processing unit 32 (described later). Note that, for convenience of explanation, the motor control unit 30 and the signal processing unit 32 are shown separately in FIG. 6, but the motor control unit 30 and the signal processing unit 32 may be integrated.

[0025] The light-projecting and receiving module 10 includes a light-projecting unit 11 that emits a slit light S1 extending in the X direction, a light-collecting unit 12 having a light-receiving lens that collects reflected light S2 reflected by the workpiece W, an imaging unit 13 that receives the light collected by the light-collecting unit 12, and a support member 14 that holds the light-projecting unit 11, the light-collecting unit 12, and the imaging unit 13 together.

[0026] As shown in FIG. 6, the light projection unit 11 has a laser light emitter (light source) 11a, an optical system 11b, a light source housing that houses the laser light emitter 11a and the optical system 11b, and a light projection control unit 11c that controls the laser light emitter 11a. The laser light emitter 11a is controlled by the light projection control unit 11c to emit a predetermined amount of laser light at a predetermined timing for a predetermined period of time. The light emitted from the laser light emitter 11a is incident on the optical system 11b. The optical system 11b is composed of a plurality of lenses including, for example, cylindrical lenses (not shown), and spreads the incident laser light in a strip shape to form slit light S1, which is then irradiated onto the workpiece W. The light projection unit 11 has a long shape in the irradiation direction of the slit light S1.

[0027] The light collecting unit 12 is configured as a lens unit including multiple large-diameter light receiving lenses in order to improve the amount of light received, and has the light receiving lenses and a lens housing that houses the light receiving lenses. Since the light collecting unit 12 includes multiple large-diameter lenses and is relatively large in size, the weight of the light collecting unit 12 is heavier than the weight of the light projecting unit 11.

[0028] The imaging unit 13 includes an image sensor 13a, such as a CMOS (complementary metal oxide semiconductor) sensor, and an imaging control unit 13b. The image sensor 13a is controlled by the imaging control unit 13b to capture an image at a predetermined timing. The exposure time of the image sensor 13a during imaging can be controlled by the imaging control unit 13b.

[0029] 7 and 8, the support member 14 is made of a flat, highly rigid member, such as a metal plate. As shown in Fig. 7, the support member 14 is fixed to a rotating shaft 50 that constitutes a part of the optical displacement meter 1, and is supported by a housing 40 so as to be rotatable around a rotation center line A that is the axis of the rotating shaft 50. The extension direction of the support member 14 is perpendicular to the rotation center line A.

[0030] The light projecting unit 11, the light collecting unit 12, and the imaging unit 13 are fixed to the upper surface of the support member 14. Specifically, in a plan view of the light projecting and receiving module 10 shown in Fig. 5, the light projecting unit 11 is fixed to a portion of the support member 14 on the left side of the rotation center line A, and the light collecting unit 12 and the imaging unit 13 are fixed to the opposite side. This means that the light projecting unit 11 and the light collecting unit 12 are provided at an interval from each other in the radial direction (Y direction, Z direction) of the rotation axis 50.

[0031] The light projecting unit 11 is disposed so that the irradiation direction of the slit light S1 faces the Z direction. The light collecting unit 12 is disposed so that the optical axis is along the direction in which the reflected light S2 is incident on the front side (workpiece W side) of the support member 14. Therefore, the light projecting unit 11 and the light collecting unit 12 both face the Z direction, but the optical axis of the optical system 11b of the light projecting unit 11 and the optical axis of the light collecting unit 12 (the optical axis of the light receiving lens) cross each other at a point away from the light projecting and receiving module 10 in the Z direction. The horizontal distance between the light projecting unit 11 and the light collecting unit 12, and the relationship between the optical axis of the optical system 11b of the light projecting unit 11 and the optical axis of the light collecting unit 12 can be changed depending on the installation distance of the optical displacement meter 1 relative to the workpiece W, the measurement accuracy, etc., so the illustrated example is merely an example.

[0032] The longer the distance between the light collecting unit 12 and the rotation axis, the larger the moment of inertia of the light collecting unit 12 due to rotation. When switching the rotation direction of the light emitting / receiving module 20, the light emitting / receiving module 20 needs to be stopped once. At this time, the larger the moment of inertia, the larger the energy required to decelerate the rotational motion of the light emitting / receiving module 20, which leads to an increase in the distance and time until the rotational motion stops. Therefore, the light emitting / receiving module 10 further includes a light receiving side reflecting member 15 fixed to the support member 14. This not only makes it possible to make the size of the light emitting / receiving module 10 compact, but also reduces the moment of inertia due to rotation, which leads to a reduction in the measurement interval. The light receiving side reflecting member 15 is composed of, for example, a mirror, and by folding back the reflected light S2 emitted from the light collecting unit 12 to the light emitting unit 11 side, the distance between the imaging unit 13 or the light collecting unit 12 and the rotation axis 50 of the light emitting / receiving module 10 in the YZ plane is shortened. The folding direction may be, for example, a direction toward the center position in the Y direction of the housing 40. The YZ plane is a plane that includes both a straight line extending in the Y direction and a straight line extending in the Z direction, and is perpendicular to the X direction.

[0033] Specifically, the light-receiving side reflecting member 15 is positioned at the right end of the support member 14 in a portion deeper than the light-collecting unit 12, and is disposed on the optical path between the imaging unit 13 and the light-collecting unit 12 in the YZ plane, and reflects the light collected by the light-collecting unit 12 toward the imaging unit 13. In addition, the rotation axis 50 of the light-emitting and receiving module 10 is disposed between the light-receiving side reflecting member 15 and the light-emitting unit 11 in the YZ plane.

[0034] By disposing the light-receiving-side reflective member 15 on the optical path between the imaging section 13 and the light-collecting section 12, it is possible to reduce the area of ​​the light-receiving-side reflective member 15, since it is only necessary to reflect the light after it has been collected by the light-collecting section 12. The position of the light-receiving-side reflective member 15 does not have to be on the optical path between the imaging section 13 and the light-collecting section 12, and the light-collecting section 12 may be disposed on the optical path between the light-receiving-side reflective member 15 and the imaging section 13, as in Modification 1 (shown in FIG. 17) described later.

[0035] The light-receiving side reflecting member 15 protrudes upward from the upper surface of the support member 14. The extending direction of the light-receiving side reflecting member 15 is the depth direction. The emission direction of the reflected light S2 incident on the light-receiving side reflecting member 15 can be set by the installation angle of the light-receiving side reflecting member 15, and the emission direction of the reflected light S2 is directed toward the light-receiving surface of the image sensor 13a.

[0036] The positional relationship between the image sensor 13a of the imaging unit 13 and the optical axis of the light collecting unit 12 is set to have a Scheimpflug relationship in which the light receiving surface of the image sensor 13a is inclined with respect to the optical axis of the light collecting unit 12. An optical system that satisfies the Scheimpflug relationship can be called a Scheimpflug optical system, and in this embodiment, the light projecting and receiving module 10 is configured by integrally holding the light projecting unit 11, the light collecting unit 12, and the imaging unit 13 on the support member 14 so as to have the Scheimpflug relationship. Since the light projecting unit 11 is focused along its projection axis due to the Scheimpflug relationship, a profile image in which the slit light is focused on the reflected light reflected by the workpiece W can be obtained. Therefore, the measurement accuracy of the three-dimensional shape data of the workpiece W is improved, and thus a highly accurate profile can be obtained.

[0037] Even when the light-emitting and receiving module 10 is rotated around the rotation center line A, the relative positional relationship between the light-emitting unit 11, the light-collecting unit 12, the imaging unit 13, and the light-receiving side reflecting member 15 does not change. Therefore, the Scheimpflug relationship is maintained regardless of the rotation angle of the light-emitting and receiving module 10.

[0038] The imaging unit 13 has a cover glass 13c. The cover glass 13c is formed so as to cover the light receiving surface of the image sensor 13a and is fixed to the image sensor 13a. The cover glass 13c is made of a light-transmitting member that transmits the reflected light S2 emitted from the light-receiving side reflecting member 15. The reflected light S2 that has transmitted through the cover glass 13c forms an image on the light receiving surface of the image sensor 13a.

[0039] The rotation axis 50 of the light projecting and receiving module 10 is disposed so as to substantially coincide with the center of gravity of the light projecting and receiving module 10 in the YZ plane. That is, the light projecting and receiving module 10 includes the light projecting section 11, the light collecting section 12, the image capturing section 13, and the light receiving side reflecting member 15 in addition to the support member 14, and when the center of gravity of the light projecting and receiving module 10 is measured or calculated in a state in which the light projecting section 11, the light collecting section 12, the image capturing section 13, and the light receiving side reflecting member 15 are fixed to the support member 14, it substantially coincides with the rotation center line A. In other words, the positions of the rotation axis 50 in the Y direction and the Z direction relative to the support member 14 are set so that the center of gravity of the light projecting and receiving module 10 becomes the center of rotation. The support member 14 is fixed to the rotation axis 50 by a plurality of fastening members (not shown) or the like, so that the support member 14 and the rotation axis 50 do not rotate relatively to each other.

[0040] By substantially matching the center of gravity of the light-emitting / receiving module 10 with the rotation center line A, the moment of inertia caused by the rotation of the light-emitting / receiving module 10 is reduced, and the load on the motor 20 caused by, for example, vibration is suppressed, and further, the decrease in the rotation speed of the light-emitting / receiving module 10 is suppressed. The center of gravity of the light-emitting / receiving module 10 and the rotation center line A do not need to be exactly the same, and there is no problem if the amount of deviation is within the allowable manufacturing tolerance, for example. Even if the center of gravity of the light-emitting / receiving module 10 and the rotation center line A are slightly misaligned, they can be considered to be substantially substantially aligned. For example, it is sufficient to sufficiently reduce the moment of inertia of the light-emitting / receiving module 10, sufficiently suppress the load on the motor 20 caused by vibration, and further suppress the decrease in the rotation speed of the light-emitting / receiving module 10. Therefore, if such effects can be achieved, a slight deviation between the center of gravity of the light-emitting / receiving module 10 and the rotation center line A is permitted, and it can be said that the two are substantially aligned.

[0041] As described above, the weight of the light-collecting unit 12 is increased by increasing the diameter of the light-collecting unit 12. Therefore, in some cases, it is considered that the center of gravity of the light-emitting / receiving module 10 is too close to the light-collecting unit 12, making design difficult. In such a case, as shown by the imaginary line only in FIG. 5, the weight 16 can be provided on the light-emitting / receiving module 10 on the light-emitting unit 11 side. This allows the center of gravity of the light-emitting / receiving module 10 to be positioned in the middle between the light-emitting unit 11 and the light-collecting unit 12. The weight 16 is disposed on the opposite side of the rotation center line A from the light-collecting unit 12. The weight 16 may be fixed to the support member 14 or to the light-emitting unit 11. The number of weights 16 is not limited to one, and may be multiple.

[0042] The closer the rotation axis of the light-emitting and receiving module 10 is to the center of gravity, the more stable the rotation will be and the less the load on the rotation axis 50 will be; however, it is assumed that the weights of the light-emitting unit 11 and the light-collecting unit 12 are different. With this configuration, a weight is provided in the light-emitting and receiving module 10 at a position closer to the light-emitting unit 11 than to the light-collecting unit 12 in order to reduce the misalignment between the center of gravity of the light-emitting and receiving module 10 and the rotation axis 50 that would result from the difference in weight, thereby stabilizing the rotation and reducing the load on the rotation axis 50.

[0043] The material of the light source housing of the light projector 11 may be a material having a higher density than the material of the lens housing of the light collector 12 without providing the weight 16. For example, the support member 14 and the lens housing, which have a large volume, may be made of a relatively low-density material such as aluminum, and the light source housing may be made of a relatively high-density material such as zinc or stainless steel (SUS). This allows the light projector 11 to be made heavier, so that the center of gravity of the light projecting and receiving module 10 can be positioned at the middle between the light projector 11 and the light collector 12. The material of the housing of the light projector 11 may be a material having a higher density than the material of the housing of the light collector 12, and the weight 16 may be provided on the light projector 11 side of the light projecting and receiving module 10.

[0044] 7, the housing 40 is a member for storing the light emitting and receiving module 10, the motor 20, and the motor control unit 30, and has a two-tiered structure. That is, the housing 40 has an upper housing component 41 that constitutes the upper part, and a lower housing component 42 that constitutes the lower part. The two-tiered structure can also be called a two-layered structure, in which case the upper housing component 41 is the first layer and the lower housing component 42 is the second layer.

[0045] The upper housing component 41 and the lower housing component 42 may be an integral part, or may be formed of separate members. In this embodiment, a case will be described in which the upper housing component 41 and the lower housing component 42 are formed of separate members. In this case, the housing 40 can be formed by joining the upper housing component 41 and the lower housing component 42 using, for example, a fastening member (not shown) or the like.

[0046] As shown in Fig. 7, the upper housing component 41 has an upper peripheral wall portion 43 and an upper wall portion 44. The upper wall portion 44 extends along the YZ plane. The upper peripheral wall portion 43 extends from the peripheral edge of the upper wall portion 44 toward the lower housing component 42. A space formed inside the upper housing component 41 is defined as an upper space R1. The upper space R1 is closed by the lower housing component 42, and the upper space R1 is sealed.

[0047] 2 and 4, a light projecting window 43a and a light receiving window 43b are provided in the front portion of the upper peripheral wall portion 43. The light projecting window 43a and the light receiving window 43b are made of a light-transmitting member. As shown in FIG. 4, the light projecting window 43a is disposed so as to face the surface of the light projecting unit 11 onto which the slit light S1 is projected. The size and position of the light projecting window 43a are set so that even if the light projecting and receiving module 10 rotates, the slit light S1 can be projected from the light projecting window 43a as long as the rotation angle of the light projecting and receiving module 10 is within a predetermined angle range described later.

[0048] Further, the light receiving window 43b is disposed so as to face the light incident surface of the light collecting unit 12. The size and position of the light receiving window 43b are set so that even if the light emitting and receiving module 10 rotates, the reflected light S2 can enter the light collecting unit 12 through the light receiving window 43b as long as the rotation angle of the light emitting and receiving module 10 is within a predetermined angle range described later.

[0049] As shown in FIG. 7, the lower housing component 42 has a substrate 45, a lower peripheral wall 46 extending downward from the substrate 45, and a lid member 47. The substrate 45 extends along the YZ plane and is a portion that closes the lower open portion of the upper housing component 41. The lid member 47 is attached to the lower end of the lower peripheral wall 46. A space formed inside the lower housing component 42 is a lower space R2. The lower space R2 is sealed by the lid member 47. In short, the housing 40 has a structure that seals the inside. The sealed structure is a structure that prevents external dust and dirt from entering the inside of the housing 40, and can be called, for example, a dustproof structure. The housing 40 does not need to be completely sealed, and for example, there may be a gap through which air can slightly enter and exit.

[0050] 3, recesses 46a are formed on both the left and right sides of the lower peripheral wall portion 46 of the lower housing component 42. The recesses 46a can be used, for example, as a portion into which an operator inserts his or her fingers to grip the optical displacement meter 1 when installing the optical displacement meter 1. The recesses 46a may be provided as necessary.

[0051] As shown in FIG. 7, the lower space R2 houses the motor 20 for integrally rotating the light emitting and receiving module 10. The central axis of the motor 20 housed in the lower space R2 coincides with the axis of the rotation shaft 50 and is oriented to extend in the vertical direction. On the other hand, the light emitting and receiving module 10 is housed in the upper space R1. The upper space R1 and the lower space R2 are aligned in the central axis direction of the motor 20, so that the light emitting and receiving module 10 housed in the upper space R1 is arranged to be aligned in the central axis direction of the motor 20 relative to the motor 20 housed in the lower space R2. In other words, the optical displacement meter 1 has a multi-stage structure in which the light emitting and receiving module 10 is arranged in the upper stage and the motor 20 is arranged in the lower stage.

[0052] Since the light-emitting and receiving module 10 is arranged to be aligned with the motor 20 in the direction of its central axis, the motor 20 is less likely to affect the positional relationship between the light-emitting unit 11 and the light-collecting unit 12 of the light-emitting and receiving module 10. Therefore, it is possible to design the light-emitting and receiving module 10 in such a way that the distance between the light-emitting unit 11 and the light-collecting unit 12 cannot be made large, for example, when the installation distance is relatively short.

[0053] The optical displacement meter 1 further includes a bearing 51 for rotatably supporting the rotation shaft 50 of the light emitting and receiving module 10. Since the light emitting and receiving module 10 is heavy as described above, when the optical displacement meter 1 is used in the posture shown in FIG. 1, for example, a moment load is generated on the rotation shaft 50 due to the weight of the light emitting and receiving module 10. Specifically, due to the difference between the part of the rotation shaft 50 supported by the bearing 51 and the center of gravity of the light emitting and receiving module 10, a moment load acts on the rotation shaft 50 in a direction that tilts the shaft core with respect to the horizontal plane. In particular, in the case of the above-mentioned two-stage structure, the upper housing component 41 and the lower housing component 42 are arranged in the direction of the central axis of the motor (the rotation shaft of the light emitting and receiving module), so that the difference between the part of the rotation shaft 50 supported by the bearing 51 and the center of gravity of the light emitting and receiving module 10 tends to be relatively large. In response to this, the bearing 51 of the present embodiment is configured to be able to support a moment load that occurs due to a difference between the portion of the rotating shaft 50 that is supported by the bearing 51 and the position of the center of gravity of the light emitting and receiving module 10 .

[0054] As the bearing 51 capable of supporting the moment load, for example, a cross roller bearing can be used in which a plurality of rollers 51c are arranged between an annular outer ring member 51a and an inner ring member 51b, and the axes of the rollers 51c adjacent in the circumferential direction are perpendicular to each other. That is, a step portion 45a into which the outer ring member 51a is fitted is formed in an annular shape in the base plate portion 45 of the lower housing component 42. The outer ring member 51a is fixed to the base plate portion 45 in a state in which it is fitted in the step portion 45a. Meanwhile, a fitting portion 50a into which the inner ring member 51b is fitted is formed in the upper portion of the rotating shaft 50. The inner ring member 51b is fixed in a state in which it is fitted in the fitting portion 50a. The inner ring member 51b may be fixed to the support member 14 of the light emitting / receiving module 10.

[0055] By using a cross roller bearing as the bearing 51, the rollers 51c come into line contact with the outer ring member 51a and the inner ring member 51b, and thus rigidity is significantly improved compared to ball-type bearings. Therefore, while having a thin and compact bearing structure in the axial direction, it is possible to receive not only the radial load (radial load) of the rotating shaft 50 but also the axial load (thrust load), and rigidity against the moment load can be improved. Therefore, smooth rotation can be achieved regardless of the orientation of the optical displacement meter 1 during operation.

[0056] Bearing 51 may be built into motor 20. Also, bearing 51 may be something other than a cross roller bearing. When using something other than a cross roller bearing, for example, two or more ball bearings are arranged at intervals from each other in the axial direction of rotating shaft 50. This results in a bearing structure capable of supporting the moment load. When using two or more ball bearings, one ball bearing can be held in base plate portion 45 of lower housing component 42, and the other ball bearings can be built into motor 20.

[0057] The optical displacement meter 1 further includes an encoder (rotation angle acquisition unit) 52 for acquiring the rotation angle of the rotating shaft 50, i.e., the rotation angle of the light emitting / receiving module 10. The encoder 52 is an optical encoder. Optical encoders are well known in the art and, although not shown, have, for example, a rotating plate fixed to the lower end of the rotating shaft 50 and rotating together with the rotating shaft 50, and a fixed plate fixed to the housing 40, and are configured such that light irradiated from the light emitter is received by the light receiver through slits formed at equal intervals in the rotating plate and the fixed plate, and the amount of received light is converted into an electrical signal to generate and output a pulse.

[0058] By using an optical encoder as the encoder 52, the detection accuracy of the rotation angle is improved compared to a magnetic encoder, but the encoder 52 is vulnerable to dust and the like. In response to this, the encoder 52 is stored inside the housing 40, specifically in the lower space R2 which is sealed as described above, to prevent dust and the like from adhering to the encoder 52. For example, even if dirt or dust enters the housing 40 when adjusting the position and orientation of the imaging unit 13 in the upper space R1 in which the light emitting and receiving module 10 is stored, the space in which the encoder 52 is stored is sealed to prevent dirt or dust from entering the lower space R2 in which the encoder 52 is stored from the upper space R1 in which the light emitting and receiving module 10 is stored and rotated. This makes it easier to use an optical encoder which is highly accurate but susceptible to dirt and dust, and enables highly accurate measurement.

[0059] The motor 20 is a direct drive motor that directly drives the light emitting and receiving module 10. Direct drive refers to a drive mode in which no reduction mechanism is interposed between the motor 20 and the driven object. As will be described later, the present invention is not limited to a direct drive motor.

[0060] The motor 20 includes a stator 21 formed of a coil and a rotor 22 formed of a permanent magnet. The rotor 22 is fixed to the outer periphery of a rotating shaft 50 between a bearing 51 and an encoder 52. The stator 21 is fixed to the lower housing component 42 and disposed so as to surround the rotor 22.

[0061] The motor control unit 30 is composed of, for example, a microcomputer, a ROM, a RAM, etc., and operates according to a predetermined program. Specifically, the motor control unit 30 can set the rotation speed of the motor 20 to a desired speed and the rotation angle of the motor 20 to a desired angle by controlling the current flowing through the stator 21. An encoder 52 is connected to the motor control unit 30. The motor control unit 30 can calculate the current rotation angle of the light emitting and receiving module 10 based on the pulse signal output from the encoder 52.

[0062] When the scanning start position, scanning end position, scanning range, etc. of the slit light S1 with respect to the workpiece W are set by the inspection settings, it is possible to calculate the rotation start position, rotation end position, rotation angle, etc. of the light projecting and receiving module 10 corresponding to the set scanning start position, scanning end position, and scanning range. Based on the results of this calculation, the motor control unit 30 controls the motor 20 to rotate the light projecting and receiving module 10 while maintaining the Scheimpflug relationship inside the housing 40, and scan the slit light S1 in a direction perpendicular to the X direction.

[0063] Since the light emitting / receiving module 10 is stored in the upper space R1 of the housing 40, depending on the rotation angle of the light emitting / receiving module 10, a part of the light emitting / receiving module 10 may come into contact with the inner wall of the housing 40. In response to this, in this embodiment, the rotation angle range of the light emitting / receiving module 10 that rotates during operation of the optical displacement meter 1, i.e., during measurement, is set to a predetermined angle range that prevents the light emitting / receiving module 10 from coming into contact with the inner wall of the housing 40. In other words, assuming that the light emitting / receiving module 10 has rotated to the first rotation angle, the light emitting / receiving module 10 has a dimension that makes contact with the inner wall of the housing 40 in the YZ plane perpendicular to the X direction, but the rotation angle range of the light emitting / receiving module 10 that rotates during measurement is set to a predetermined angle range smaller than the first rotation angle in order to prevent the light emitting / receiving module 10 from coming into contact with the inner wall of the housing 40. With this configuration, the housing 40 can be easily miniaturized because it is only necessary to design the housing 40 based on the angle range in which the light emitting / receiving module 10 needs to rotate.

[0064] Methods for setting the rotation angle range of the light emitting / receiving module 10 to a predetermined angle range include, for example, a mechanical realization method and a software realization method. In this embodiment, as a mechanical realization method, a first stopper 61 and a second stopper 62, which are an example of mechanical parts, are provided inside the housing 40 as shown in FIG. 4. In this example, the first stopper 61 and the second stopper 62 are provided so as to protrude upward from the substrate portion 45. When the light emitting / receiving module 10 rotates around the rotation center line A in the direction of arrow B, the light emitting / receiving module 10 abuts against the first stopper 61 before a part of the light emitting / receiving module 10 contacts the inner wall of the housing 40, and the light emitting / receiving module 10 is prevented from rotating further in the direction of arrow B. Furthermore, when the light projecting and receiving module 10 rotates in the direction of arrow C around the rotation center line A, the light projecting and receiving module 10 abuts against the second stopper 62 before a part of the light projecting and receiving module 10 comes into contact with the inner wall of the housing 40, preventing the light projecting and receiving module 10 from rotating further in the direction of arrow C. In other words, the first stopper 61 and the second stopper 62 are provided inside the housing 40 to prevent the light projecting and receiving module 10 from rotating outside a predetermined angle range during measurement.

[0065] The first stopper 61 and the second stopper 62 can be made of an elastic material such as rubber or a thermoplastic elastomer. Alternatively, the first stopper 61 and the second stopper 62 can be made of metal, and an elastic material can be provided on the portion of the support member 14 where the first stopper 61 and the second stopper 62 come into contact. This makes it possible to reduce the sound generated when the light emitting and receiving module 10 comes into contact with the first stopper 61 and the second stopper 62.

[0066] Also, it is preferable to abut the support member 14 against the first stopper 61 and the second stopper 62. This is because if the light projecting unit 11, the light collecting unit 12, etc. are abutted against the first stopper 61 or the second stopper 62, the optical axis may be shifted due to the impact at the time of abutment. Also, the first stopper 61 and the second stopper 62 may be provided on the upper peripheral wall portion 43. Furthermore, only one of the first stopper 61 and the second stopper 62 may be provided.

[0067] Next, a method using software will be described. That is, the motor control unit 30 can execute contact avoidance control to prevent the light emitting and receiving module 10 from contacting the inner wall of the housing 40. The motor control unit 30 controls the motor 20 to rotate the light emitting and receiving module 10 within a predetermined angle range during measurement, based on a rotation angle acquired by calculating a pulse signal output from the encoder 52. This control is the contact avoidance control. By executing this contact avoidance control, it is possible to prevent the light emitting and receiving module 10 from contacting the inner wall of the housing 40 without providing stoppers 61 and 62. Note that the stoppers 61 and 62 may be provided even when the contact avoidance control is executed.

[0068] Only during measurement is it necessary to prevent the light emitting and receiving module 10 from contacting the inner wall of the housing 40. For example, during non-measurement times such as during maintenance or various settings, it is acceptable for the light emitting and receiving module 10 to contact the inner wall of the housing 40, so the motor control unit 30 can be configured to execute contact avoidance control only during measurement.

[0069] As shown in FIG. 8, the lower housing component 42 is provided with a board storage space R3. In the plan view shown in FIG. 4, the board storage space R3 is offset from the center of the housing 40 toward the rear, and is therefore positioned further rearward than the motor 20 (shown in FIG. 7). The board storage space R3 is located below the upper space R1 in which the light emitting and receiving module 10 is stored, and is therefore a different space from the upper space R1. The board storage space R3 is disposed at a different position from the upper space R1 with respect to the direction of the rotation axis of the light emitting and receiving module 10, while being disposed at the same position as the lower space R2 that stores the motor 20. When viewed along the rotation axis of the light emitting and receiving module 10, the upper space R1 and the lower space R2 are disposed at positions overlapping with the rotation axis, while the board storage space R3 is disposed at a position not overlapping with the rotation axis. For example, if the size of the light emitting and receiving module 10 is larger than the size of the motor 20, the housing 40 can be made more compact in external shape by using a two-tier structure in which the upper space R1 that stores the light emitting and receiving module 10 is the first tier, and the lower space R2 that stores the motor 20 and the board storage space R3 that stores the control unit 30 are the second tier.

[0070] As shown in FIG. 8, the board storage space R3 stores a motor control board 31 on which the motor control unit 30 is mounted, a signal processing board 33 on which the signal processing unit 32 is mounted, and a power supply board 35 on which the power supply unit 34 is mounted. The motor control board 31 and the signal processing board 33 are equipped with processors such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor) and an FPGA (Field Programmable Gate Array) that function as the motor control unit 30 and the signal processing unit 32, as well as storage elements (not shown) such as a RAM (Random Access Memory) and a ROM (Read Only Memory) for storing programs executed by the processor. Each board 31, 33, and 35 is fixed to the lower housing component 42. Since the motor control unit 30 and the signal processing unit 32 are stored in the board storage space R3 different from the upper space R1, the light projecting unit 11, which is particularly prone to heat generation, can be thermally isolated from the motor control unit 30 and the signal processing unit 32, and the operation of the motor control unit 30 and the signal processing unit 32 can be stabilized. The arrangement of the control unit 3 is not limited to the above example, and may be, for example, a configuration in which the signal processing unit 32 is stored within the housing 40 while the motor control unit 30 is arranged outside the housing 40.

[0071] Since the reflected light S2 is incident from the front side of the housing 40, the motor control unit 30, the signal processing unit 32, and the power supply unit 34 stored in the back side of the housing 40 are arranged on the opposite side of the light emitting and receiving module 10 from the side on which the reflected light S2 is incident. This makes it possible to prevent the motor control unit 30, the signal processing unit 32, and the power supply unit 34 from interfering with the displacement measurement. Furthermore, when the Z direction is taken as the reference, the motor control unit 30, the signal processing unit 32, and the power supply unit 34 are arranged adjacent to the light emitting and receiving module 10 in the Z direction. Furthermore, since the board storage space R3 is sealed by the cover member 47, dust and the like are prevented from entering the boards 31, 33, and 35.

[0072] The signal processing board 33 is located at the top, the motor control board 31 is located below the signal processing board 33, and the power supply board 35 is located below the motor control board 31. The signal processing board 33 located at the top is closest to the light emitting and receiving module 10, but this signal processing board 33 is located below the support member 14 of the light emitting and receiving module 10. This prevents the light emitting and receiving module 10 from coming into contact with the signal processing board 33 when it rotates within a predetermined angle range. In other words, the motor control unit 30, the signal processing unit 32, and the power supply unit 34 are all positioned so as to avoid contact with the light emitting and receiving module 10 that rotates during measurement.

[0073] The power supply unit 34 is a part that supplies power to the light projecting unit 11, the imaging unit 13, the motor control unit 30, the signal processing unit 32, etc. In this embodiment, the power supply unit 34, the motor control unit 30, and the signal processing unit 32 are mounted on different boards, but this is not limiting, and any two or more of them may be integrated and mounted on a single board.

[0074] The signal processing unit 32 is composed of, for example, a microcomputer, a ROM, a RAM, etc., and operates according to a predetermined program to generate cross-sectional profile data of the workpiece W based on the amount of light received by the imaging unit 13. The boards 31, 33, 35 are connected to the light projecting unit 11 and the imaging unit 13 by wiring indicated by reference symbol 70 in Fig. 4. This wiring 70 is flexible and configured so as not to affect the rotational operation of the light projecting and receiving module 10.

[0075] 10, the image sensor 13a of the imaging unit 13 has a plurality of pixels two-dimensionally arranged in a U direction corresponding to the X direction and a V direction perpendicular to the U direction. The signal processing unit 32 acquires the luminance value (amount of received light) of each pixel of the image sensor 13a and obtains an approximation curve of the luminance value change. The signal processing unit 32 calculates the peak position in the V direction of each pixel row in the obtained approximation curve and obtains the calculated peak position as the displacement of the workpiece W.

[0076] The signal processing unit 32 executes the above-mentioned calculation of the peak position multiple times during the rotational operation of the light emitting and receiving module 10. The signal processing unit 32 associates the obtained peak position with the rotation angle of the light emitting and receiving module 10 when the peak position was obtained, and stores this as measurement data. Since the rotation angle and UV coordinates of the light emitting and receiving module 10 correspond to the XYZ coordinates of the workpiece, cross-sectional profile data of the workpiece W at a desired rotation angle can be generated based on the measurement data. In addition, by acquiring multiple cross-sectional profiles of the workpiece W at different rotation angles, the signal processing unit 32 can generate data of the three-dimensional shape of the workpiece W.

[0077] That is, the control unit 3 including the motor control unit 30 and the signal processing unit 32 controls the motor 20 to rotate the light projecting and receiving module 10 to scan the slit light S1 in a direction perpendicular to the X direction, and controls the light projecting unit 11 and the imaging unit 13 to generate a cross-sectional profile at each of different rotation angles of the light projecting and receiving module 10. When controlling the light projecting unit 11 and the imaging unit 13, the control unit 3 transmits an exposure trigger to the light projecting unit 11 and the imaging unit 13 to drive the light projecting unit 11 and the imaging unit 13. The light projecting unit 11 and the imaging unit 13 that have received the exposure trigger are configured to perform imaging. The transmission timing of the exposure trigger can be set based on the rotation angle θ acquired by the encoder 52, and the control unit 3 transmits the exposure trigger when a specific rotation angle is reached. As another method, when the transmission timing of the exposure trigger is set in advance, the encoder 52 acquires the rotation angle θ at the timing when the exposure trigger is transmitted.

[0078] (Correction processing by the control unit) 10 is a schematic diagram showing the shape of the measurement area F1 of the optical displacement meter 1. When the light emitting and receiving module 10 is rotated as in the first embodiment, the measurement area F1 becomes a long arc-shaped area centered on the rotation center line A of the light emitting and receiving module 10. For this reason, if there is a change in the angle information used to calculate the height and the exposure timing, an error may occur in the height data.

[0079] Fig. 11 is a timing chart showing the exposure timing when the light-emitting and receiving module 10 is rotated in the direction B in Fig. 4 and when the light-emitting and receiving module 10 is rotated in the direction C in Fig. 4. When the light-emitting and receiving module 10 is rotating in the direction B, if the control unit 3 transmits an exposure trigger A to the light-projecting unit 11 and the imaging unit 13, the light-projecting unit 11 and the imaging unit 13 perform the first imaging, if the control unit 3 transmits an exposure trigger B to the light-projecting unit 11 and the imaging unit 13, the light-projecting unit 11 and the imaging unit 13 perform the second imaging, and if the control unit 3 transmits an exposure trigger C to the light-projecting unit 11 and the imaging unit 13, the light-projecting unit 11 and the imaging unit 13 perform the third imaging. Thereafter, when the rotation direction of the light-emitting / receiving module 10 switches to direction C, the control unit 3 sends an exposure trigger C to the light-projecting unit 11 and the imaging unit 13, which then perform the fourth imaging, and when the control unit 3 sends an exposure trigger B to the light-projecting unit 11 and the imaging unit 13, which then perform the fifth imaging.

[0080] Focusing on the second and fifth imaging, height measurements are performed during exposure periods t1 and t2, respectively. Specifically, the reference angle θ1 at the timing when the exposure trigger B is transmitted is acquired by the encoder 52, but since the rotational motion continues during the exposure period t1, the peak position in the V direction of the light reception amount distribution acquired by the control unit 3 corresponds to the height of the rotational angle (representative angle) θ2 at the timing during the exposure period. In other words, if coordinate conversion is performed using the reference angle θ1 and the measured peak position in the V direction, an error occurs in the height data. In addition, even if the slit light is irradiated at the same height, the exposed position in the V direction on the image sensor 13a changes due to the rotational motion during the exposure period t1. Note that the reference angle θ1 is not limited to the timing when the exposure trigger B is transmitted.

[0081] For example, in the case of a workpiece W having a diffusive surface (dark workpiece), the instantaneous rotation angle θ2 of the lines L1 and L2 in the B and C directions, respectively, becomes the representative angle corresponding to the peak position in the V direction obtained during the exposure periods t1 and t2 on average, and in the case of a workpiece W having a mirror surface (bright workpiece), the instantaneous rotation angle θ2 of the lines L3 and L4 in the B and C directions, respectively, becomes the representative angle corresponding to the peak position in the V direction obtained during the exposure periods t1 and t2 on average. For a dark workpiece W, the control unit 3 can determine the rotation angle at approximately the center of the exposure period as the representative angle θ2.

[0082] Changes in the angle information used to calculate the height and the exposure timing can cause errors in the height data. In this embodiment, in order to suppress the occurrence of these errors, the control unit 3 is configured to estimate the representative angle θ2 at which the peak position in the V direction is obtained based on the control conditions of the image sensor 13a or the motor 20 and the reference angle θ1 obtained by the encoder 52, and to calculate the Z-direction height of the workpiece W at the representative angle θ2 from the peak position.

[0083] The control conditions of the image sensor 13a include at least one of the trigger interval for starting the exposure period and the length of the exposure period. The control conditions of the motor 20 include at least one of the angular velocity of the motor 20, the rotation direction of the motor 20, and the number of reciprocating movements. The rotation direction of the motor 20 includes directions B and C in FIG. 4. Direction B may be called forward rotation, and direction C may be called reverse rotation. Since the forward path of the oscillating motion corresponds to the odd-numbered measurements and the return path corresponds to the even-numbered measurements, the direction of rotation of the motor 20 can also be specified depending on whether the number of reciprocating movements is even or odd.

[0084] In the optical displacement meter 1, for example, a coordinate conversion condition (for example, a coordinate conversion table) indicating the correspondence between the UV coordinates and the rotation angle θ, as expressed by (U, V, θ)=(X, Y, Z), and the local coordinates (X, Y, Z) is generated by calibration before shipment, and is stored in the storage unit. The control unit 3 calculates the correction value Δθ based on the control conditions of the image sensor 13a or the motor 20, and estimates the representative angle θ2 based on the reference angle θ1 obtained by the encoder 52 and the correction value Δθ. Then, the control unit 3 can calculate the local coordinates (X, Y, Z) based on the values ​​of U and V obtained by measurement and the estimated representative angle θ2, and measure the height of the workpiece W. As will be described later, the control unit 3 can change the correction value Δθ depending on, for example, the rotation direction.

[0085] Furthermore, the storage unit may store a plurality of conversion conditions, and the control unit 3 can measure the height of the workpiece W using a conversion condition selected from the plurality of conversion conditions according to the control conditions, without calculating the correction value Δθ. For example, by using a conversion table of (U, V, θ) ⇒ (X, Y, Z) according to the control conditions of the image sensor 13a or the motor 20, it is possible to accurately convert (X, Y, Z) according to the angular velocity, exposure period, and exposure interval, even with the same (U, V, θ).

[0086] Also, a conversion condition can be prepared for each rotation direction of the motor 20. If the angular velocity of the motor 20 can be changed, a conversion condition corresponding to each angular velocity can also be prepared. If multiple settings are possible for the exposure period and exposure trigger interval of the image sensor 13a, a conversion condition corresponding to each setting can also be prepared. Note that, when there are multiple mutually different control conditions, each control condition may correspond to a different conversion condition, or multiple control conditions may correspond to a common conversion condition.

[0087] A specific example of calculation of the correction value will be described with reference to Fig. 12. The time interval between exposure trigger B and exposure trigger C is defined as the trigger period, and the time for the second imaging to be performed after exposure trigger B is received is defined as the exposure period. The start time of the second imaging can be obtained from the encoder 52, and is the encoder raw value. The encoder correction value A and the encoder correction value B can be calculated as follows.

[0088] ΔθB=θpitch×exposure time / trigger period ΔθA=θpitch×exposure time / trigger period×0.5 θpitch: Rotation angle pitch between exposure triggers (trigger period) That is, since an error occurs if the raw encoder value is used as is, the above formula ΔθA is calculated and added to the raw encoder value to correct it to angle information at line L1. When the raw encoder value is corrected, the control unit 3 measures the height based on the peak position in the V direction (shown in FIG. 9) acquired under the control conditions and the corrected rotation angle. Note that θpitch / trigger period corresponds to the angular velocity.

[0089] When the rotation of the light projecting and receiving module 10 is a reciprocating motion, the location being measured will shift in both the Y and Z directions on the way there (e.g., in the direction B shown in FIG. 4) and on the way back (e.g., in the direction C shown in FIG. 4), but accurate values ​​can be calculated in both the Y and Z directions by performing coordinate conversion using the representative angle θ2. In this way, the control unit 3 determines the timing of the exposure trigger for driving the light projecting unit 11 and the imaging unit 13 based on the control conditions, and drives the light projecting unit 11 and the imaging unit 13 by the exposure trigger. The control unit 3 can measure the height based on the data obtained by the light projecting unit 11 and the imaging unit 13 driven by the exposure trigger.

[0090] The optical displacement meter 1 according to the first embodiment has a multiple exposure or HDR (High Dynamic Range) function within one exposure time to accommodate changes in the amount of light of the workpiece W. When the encoder raw value is corrected by the method shown in Fig. 12, it is also possible to correct Δθ according to, for example, multiple exposure or other HDR methods.

[0091] For example, as shown in FIG. 13, the image sensor 13a monitors the amount of light received by each pixel during the exposure time, and the optical displacement meter 1 can be applied with an HDR function in which the image sensor 13a monitors the amount of light received by each pixel during the exposure time, and performs exposure reset at a specific timing T for bright pixels whose amount of light received during the exposure time exceeds a threshold. In the case of the HDR shown in this figure, the non-bright area can be corrected to the viewing location (line L1 in FIG. 12) at a time of (t3+t2) / 2. On the other hand, the bright area can be corrected to the viewing location (line L2 in FIG. 12) at a time of t3+t2 / 2. That is, the control unit 3 estimates the rotation angle at a time approximately in the middle of the exposure time as the representative angle θ2 for dark pixels, while adjusting the amount of light received that is equal to or greater than the threshold at a predetermined time point (t3) during the exposure time for bright pixels, and estimating the rotation angle after the predetermined time point as the representative angle. In this way, the control unit 3 can calculate the correction value by different calculation methods for bright pixels whose amount of light received is equal to or greater than a threshold and dark pixels whose amount of light received is less than the threshold during the exposure time of the imaging unit 13. The control unit 3 can set the correction value for bright pixels to be larger than the correction value for dark pixels. The storage unit may also include coordinate conversion conditions to be used for bright pixels whose received light amount is equal to or greater than a threshold, and coordinate conversion conditions to be used for dark pixels whose received light amount is less than the threshold.

[0092] Furthermore, the control unit 3 can recognize the rotation direction of the motor 20 and adjust the correction value according to the recognized rotation direction. When the rotation angle acquired by the encoder 52 is the same, the control unit 3 changes the correction value of the rotation angle according to the rotation direction of the light emitting / receiving module 10. Specifically, as shown in FIG. 14, the control unit 3 can adjust the exposure trigger timing so that exposure is performed in the same angle range while grasping control conditions such as exposure time and trigger interval. In this case, the exposure triggers D, E, and F are adjusted so that the first, second, and third images captured when the light emitting / receiving module 10 is rotated in the B direction (first rotation direction) are exposed in the same angle range as the sixth, fifth, and fourth images captured when the light emitting / receiving module 10 is rotated in the C direction (second rotation direction). In this way, the control unit 3 is configured to determine the exposure trigger timing so as to scan in the first angle range from the first rotation direction and to scan in the first angle range from the second rotation direction opposite to the first rotation direction, and to associate the height data obtained by scanning in the first angle range from the first rotation direction and the height data obtained by scanning in the first angle range from the second rotation direction with the same rotation angle. That is, the motor 20 rotates the image sensor 13a in the first rotation direction and then rotates it in the second rotation direction opposite to the first rotation direction, and the control unit 3 controls the start timing of the first exposure period and the start timing of the second exposure period so that both the center of the angle range corresponding to the first exposure period while the image sensor 13a is rotating in the first rotation direction and the center of the angle range corresponding to the second exposure period while the image sensor 13a is rotating in the second rotation direction substantially coincide with the representative angle θ2.

[0093] The control unit 3 can obtain the representative angle θ2 using correction conditions for correcting the reference angle θ1 obtained by the encoder 52 based on the control conditions of the image sensor 13a or the motor 20. An example of the correction conditions is a correction table as shown in Fig. 15. The correction table includes the encoder raw value, the correction value in the B direction, and the correction value in the C direction.

[0094] 16 is a graph showing the measurement error according to the present invention and a comparative example. This graph shows "the present invention" which shows the case where the correction process is performed, and "comparative example" which shows the case where the correction process is not performed. In the comparative example, the peaks of the graph are high and the valleys are deep, which indicates that there is a large error that occurs in the outbound and inbound measurements when the light emitting / receiving module 10 is moved back and forth. On the other hand, in the case of the present invention, the peaks of the graph are significantly lower and the valleys are significantly shallower than in the comparative example, which indicates that the error that occurs in the outbound and inbound measurements is suppressed.

[0095] (Modification 1 of the first embodiment) FIG. 17 shows the light-emitting / receiving module 10 according to the first modified example of the first embodiment. The light-emitting / receiving module 10 of the first modified example has different positions of the light-emitting unit 11, the light-collecting unit 12, the image capturing unit 13, and the light-receiving side reflecting member 15 from those of the above-mentioned embodiment. Specifically, the rotation axis 50 of the light-emitting / receiving module 10 is disposed at a position overlapping the light-collecting unit 12 in the YZ plane. That is, as described above, it is desired to reduce the moment of inertia caused by the rotation of the light-emitting / receiving module 10 as much as possible, but providing a weight 16 as shown by an imaginary line in FIG. 5 may increase the weight of the light-emitting / receiving module 10, which may be undesirable. Therefore, as a method for reducing the moment of inertia caused by the rotation of the light-emitting / receiving module 10 without providing the weight 16, a method of overlapping the light-collecting unit 12, which is heavy, with the rotation axis 50 of the light-emitting / receiving module 10 in the YZ plane can be adopted. As a result, at least a part of the light-collecting unit 12 is disposed on an extension line of the rotation axis 50 of the light-emitting / receiving module 10. Incidentally, the rotation axis 50 does not have to completely overlap with the light collecting unit 12, and it is sufficient that at least a part of the rotation axis 50 and at least a part of the light collecting unit 12 overlap with each other when viewed from the direction of the rotation center line A. This makes it possible to eliminate the need for the weight 16, or to make the weight 16 lighter.

[0096] In addition, in the first modification, the imaging section 13 and the light-receiving side reflecting member 15 are disposed to sandwich the light-collecting section 12. As a result, the light-collecting section 12 in the first modification is disposed on the optical path between the light-receiving side reflecting member 15 and the imaging section 13 in the YZ plane, and collects the light reflected by the light-receiving side reflecting member 15 and makes it incident on the imaging section 13.

[0097] Furthermore, the light-projecting and light-receiving module 10 of the first modification includes a light-projecting side reflecting member 17. That is, the light-projecting unit 11 of the first modification is disposed so that the slit light S1 irradiated from the optical system 11b is directed toward the left rear side. This allows the light-projecting unit 11 to be brought closer to the rotation center line A, and the moment of inertia caused by the rotation of the light-projecting and light-receiving module 10 can be further reduced, but the workpiece W is located on the opposite side to the slit light S1 irradiated from the optical system 11b. In response to this, the light-projecting side reflecting member 17 is disposed so as to reflect the slit light S1 emitted from the optical system 11b of the light-projecting unit 11 toward the workpiece W side. This light-projecting side reflecting member 17 is fixed to the support member 14 or the light-projecting unit 11, and the relative positional relationship with respect to the light-projecting unit 11 does not change even if the light-projecting and light-receiving module 10 rotates.

[0098] (Modification 2 of the first embodiment) Figures 18 and 19 show an optical displacement meter 1 according to a second modification of the first embodiment. Figure 18 is a diagram showing the internal structure of the optical displacement meter 1 as viewed from above, and Figure 19 is a diagram showing the internal structure of the optical displacement meter 1 as viewed from below.

[0099] In the optical displacement meter 1 of the second modification, the motor 20 is not a direct drive motor, but is configured to rotate the light emitting and receiving module 10 via a speed reducing mechanism 25. As shown in Fig. 18, the motor 20 is stored in the upper space R1 together with the light emitting and receiving module 10. As shown in Fig. 19, the output shaft 20a of the motor 20 passes downward through the substrate 45 and reaches the lower space R2. In addition, the driven shaft 10a fixed to the light emitting and receiving module 10 also passes downward through the substrate 45 and reaches the lower space R2.

[0100] The reduction mechanism 25 is housed in the lower space R2 and includes a driving pulley 25a fixed to the output shaft 20a of the motor 20, a driven pulley 25b fixed to the driven shaft 10a, and a transmission belt 25c wound around the driving pulley 25a and the driven pulley 25b. The driving pulley 25a has a smaller diameter than the driven pulley 25b. The transmission belt 25c is a timing belt.

[0101] In the second modification, when the output shaft 20a of the motor 20 housed in the upper space R1 rotates, the driving pulley 25a rotates, and the rotational force of the driving pulley 25a is transmitted to the driven pulley 25b via the transmission belt 25c. The driving force transmitted to the driven pulley 25b is transmitted to the driven shaft 10a, so that the motor 20 can rotate the light emitting and receiving module 10. In the second modification, the driven shaft 10a serves as the rotational shaft of the light emitting and receiving module 10.

[0102] The speed reduction mechanism 25 is not limited to the combination of the pulleys 25a, 25c and the transmission belt 25c, but may be, for example, a combination of a driving sprocket, a driven sprocket and a timing chain, or a combination of multiple gears. The type of the motor 20 that can be used is, for example, a DC motor, a stepping motor, a servo motor, or the like.

[0103] (Embodiment 2) 20 to 22 show an optical displacement meter 1 according to a second embodiment of the present invention. In this second embodiment, the structure of the housing 400 and the positional relationship between the motor 20 and the light emitting and receiving module 100 are different from those in the first embodiment. In the following, the same parts as those in the first embodiment are given the same reference numerals and their explanations are omitted, and the different parts will be explained in detail.

[0104] 20 and 22, the housing 400 has a single-tier structure, and the boards 31, 33, and 35 are also stored inside the housing 400. By partitioning the inside of the housing 400, the space in which the boards 31, 33, and 35 are stored and the space in which the light emitting and receiving module 100 is stored can be made different spaces.

[0105] The housing 400 includes a bottom wall portion 401, a peripheral wall portion 402 extending upward from the peripheral portion of the bottom wall portion 401, and a lower cover member 403 for closing an upper open portion. A light projection window 402a through which the slit light S1 irradiated from the light projector 11 passes, and a light receiving window 402b through which the reflected light S2 reflected from the workpiece W passes are provided in the front portion of the peripheral wall portion 402.

[0106] 22, an annular wall portion 404 is formed in the center of the lower wall portion 401, protruding into the housing 400 and extending around the rotation center line A. An end wall portion 405 is formed at the tip of the annular wall portion 404, extending in the radial direction of the rotation center line A. An opening 405a is formed in the center of the end wall portion 405, into which the rotating shaft 50 is inserted.

[0107] A motor storage space R4 is formed inside the annular wall portion 404. The stator 21 and rotor 22 of the motor 20 are stored in the motor storage space R4. The stator 21 of the motor 20 is fixed to the inner surface of the annular wall portion 404. That is, in this embodiment, a stator holding portion is configured by the annular wall portion 404 and the end wall portion 405. On the other hand, the rotor 22 of the motor 20 is fixed to the rotating shaft 50.

[0108] The outer ring member 51a of the bearing 51 is fixed to the end wall portion 405 in a state where it is fitted into a step portion 405b formed in the end wall portion 405. As a result, the bearing 51 is held by a stator holding portion formed by the annular wall portion 404 and the end wall portion 405. On the other hand, the inner ring member 51b is fitted into a fitting portion 50a formed on the rotating shaft 50.

[0109] The motor storage space R4 also stores the encoder 52. A lower cover member 406 is provided at the lower end of the housing 400. The motor storage space R4 is sealed by the lower cover member 406, preventing dust and the like from adhering to the encoder 52.

[0110] The light-emitting and receiving module 100, like the first embodiment, comprises a light-projecting section 11, a light-collecting section 12, an imaging section 13, a weight 16, etc., but the support member 110 that holds the light-projecting section 11, the light-collecting section 12, and the imaging section 13 together is significantly different from the support member 14 of the first embodiment.

[0111] That is, in the first embodiment, the light projecting and receiving module 10 and the motor 20 (bearing 51 and encoder 52) are aligned in the direction of the rotation axis 50 (height direction), whereas in the second embodiment, at least one of the motor 20, the bearing 51 supporting the rotation axis 50, or the encoder 52 connected to the motor 20 is included within a portion of the height range in the direction of the rotation axis 50 of the light projecting and receiving module 100. This makes it possible to design the light projecting unit 11 and the light collecting unit 12 of the light projecting and receiving module 100 so as to set a large gap between them, for example when the installation distance is relatively long.

[0112] Specifically, the support member 110 includes a fixed portion 111 fixed to the rotating shaft 50, one-side vertical plate portion 112, the other-side vertical plate portion 113, a light condensing portion holding portion 114, and a light projecting portion holding portion 115. The fixed portion 111, the one-side vertical plate portion 112, the other-side vertical plate portion 113, the light condensing portion holding portion 114, and the light projecting portion holding portion 115 may be integrally molded, or may be formed by combining separate members.

[0113] The fixed portion 111 is in the form of a plate extending in the radial direction of the rotating shaft 50, and in this embodiment, it is in the form of a circle as shown in FIG. 21, and is disposed so as to cover the end wall portion 405 from above as shown in FIG. 22. The one-side vertical plate portion 112 extends downward along the direction of the rotating shaft 50 from the right side of FIG. 22, that is, from one radial side of the rotating shaft 50 at the fixed portion 111. The other-side vertical plate portion 113 extends downward along the direction of the rotating shaft 50 from the left side of FIG. 22, that is, from the other radial side of the rotating shaft 50 at the fixed portion 111. The one-side vertical plate portion 112 and the other-side vertical plate portion 113 are disposed so as to face the annular wall portion 404. In addition, the one-side vertical plate portion 112 and the other-side vertical plate portion 113 are curved in an arc shape like the annular wall portion 404, and rotate while maintaining a certain gap between them and the annular wall portion 404 when the light emitting and receiving module 100 rotates.

[0114] The one-side vertical plate portion 112 and the other-side vertical plate portion 113 may be integrally formed. For example, a ring-shaped peripheral wall portion (not shown) extending downward from the peripheral edge portion of the fixing portion 111 may be formed, and the one-side vertical plate portion 112 and the other-side vertical plate portion 113 may be formed at parts of the peripheral direction of this peripheral wall portion.

[0115] The light collecting unit holding part 114 has a plate shape extending in the radial direction of the rotation axis 50 from the lower end of the one-side vertical plate part 112. The light collecting unit 12, the imaging unit 13, the cover glass 13c, etc. are held on the upper surface of the light collecting unit holding part 114. Therefore, the rotation axis 50 of the light emitting and receiving module 100 is disposed at a position that does not overlap with the light collecting unit 12 and the imaging unit 13 in the YZ plane.

[0116] The light-projecting unit holding portion 115 has a plate shape extending in the radial direction of the rotation shaft 50 from the lower end portion of the other-side vertical plate portion 113. The light-projecting unit 11, weight 16, etc. are held on the upper surface of the light-projecting unit holding portion 115. Therefore, the rotation shaft 50 of the light-projecting and receiving module 100 is disposed at a position that does not overlap with the light-projecting unit 11 in the YZ plane.

[0117] In this way, the light collecting unit holding part 114 and the light projecting unit holding part 115 are disposed to sandwich the rotation shaft 50, and protrude in opposite directions from each other in the radial direction of the rotation shaft 50. The weight 16 can be fixed to the light projecting unit holding part 115. Furthermore, the weight 16 may be fixed to the side of the fixing part 111 opposite to the side on which the one-side vertical plate part 112 is formed.

[0118] Support member 110, which has fixing portion 111, one-side vertical plate portion 112, other-side vertical plate portion 113, light collecting portion holding portion 114, and light emitting portion holding portion 115, has a plurality of bent portions 110A in a cross section in the X direction. Since support member 110 has a structure having a plurality of bent portions 110A in this way, the rigidity can be increased compared to when support member 110 is a flat plate.

[0119] The motor 20 and the bearing 51 are disposed between the one-side vertical plate portion 112 and the other-side vertical plate portion 113 of the support member 110. The bearing 51 is disposed between the one-side vertical plate portion 112 and the other-side vertical plate portion 113 at a location closer to the fixed portion 111 than the motor 20. As a result, the motor 20 and the bearing 51 are included within a portion of the height range of the light emitting and receiving module 100. Although not shown, only the motor 20 may be included within the height range of the light emitting and receiving module 100, or only the bearing 51 may be included within the height range of the light emitting and receiving module 100.

[0120] A rotation drive unit is configured by at least the motor 20, the bearing 51, and the encoder 52. The motor 20 is fixed to a wall surface (lower wall portion 401 and annular wall portion 404) adjacent to a light projecting and receiving surface provided with a light projecting window 402a for passing slit light and a light receiving window 402b for passing reflected light (collectively referred to as a light projecting and receiving window).

[0121] The light projecting and receiving window in this embodiment is composed of a light projecting window 402a and a separate light receiving window 402b, but the light projecting and receiving windows may be integrally formed. The light projecting and receiving surface is a surface that is one of the surfaces that constitute the outer shape of the housing 400 on which the light projecting and receiving windows are provided, and is a surface consisting of multiple flat surfaces formed by the windows as shown in Figures 4 and 14. When the light projecting and receiving windows are integrally formed, the light projecting and receiving surface may be a surface consisting of a single flat surface formed by the light projecting and receiving windows.

[0122] The support member 110 supports the light emitting and receiving module 100 so that the light emitting and receiving module 100 is positioned in a plane perpendicular to the X direction and in which the rotation drive unit is present. The support member 110 has a first portion (e.g., a fixed portion 111) and a second portion (e.g., a light collecting unit holding portion 114 and a light emitting unit holding portion 115) that are formed by a plurality of bent portions 110A and have different heights in the direction of the rotation axis, and the rotation drive unit and the light emitting and receiving module 100 are present between the plane formed by the first portion and the plane formed by the second portion in at least a cross section including the rotation axis. This configuration makes it possible to increase the rigidity of the support member 110 and reduce the thickness of the housing 400 in the X direction.

[0123] Although not shown, the encoder 52 may be included within the height range of the light projecting and receiving module 100. For example, by disposing the encoder 52 at the middle or upper end of the rotation shaft 50, the encoder 52 will be included within the height range of the light projecting and receiving module 100. Only the encoder 52 may be included within the height range of the light projecting and receiving module 100, only the motor 20 and the encoder 52 may be included within the height range of the light projecting and receiving module 100, or only the bearing 51 and the encoder 52 may be included within the height range of the light projecting and receiving module 100.

[0124] The light-receiving side reflecting member 15 is disposed on the optical path between the light-collecting unit 12 and the light-receiving window 402b of the housing 400 in the YZ plane, and reflects the reflected light S2 that has passed through the light-receiving window 402b toward the light-collecting unit 12. That is, the light-collecting unit 12 is disposed on the optical path between the light-receiving side reflecting member 15 and the imaging unit 13 in the YZ plane, and collects the reflected light S2 reflected by the light-receiving side reflecting member 15 and makes it incident on the imaging unit 13. This allows the reflected light S2 to be folded back toward the light-projecting unit 11 so that the distance between the imaging unit 13 or the light-collecting unit 12 and the rotation axis 50 of the light-projecting and receiving module 100 in the YZ plane is shortened.

[0125] (Modification of the second embodiment) 23 shows an optical displacement meter 1 according to a modified example of the embodiment 2. In this modified example, the light-receiving side reflecting member 15 is omitted. By arranging the light-collecting unit 12 so that the optical axis of the light-collecting unit 12 faces the light-receiving window 402b of the housing 400, the reflecting member 15 becomes unnecessary.

[0126] This modified example is also an example of a layout in which a wide interval is secured between light projecting unit 11 and light collecting unit 12. For example, this modified example can be applied when the installation distance is relatively long.

[0127] The above-described embodiment is merely illustrative in every respect and should not be interpreted as being restrictive. Furthermore, all modifications and changes within the scope of equivalence of the claims are within the scope of the present invention. For example, in the second embodiment, a light-projecting side reflecting member may be provided. Also, in the second embodiment, a speed reduction mechanism may be provided. Also, in the first and second embodiments, the motor 20 may be provided outside the housing 40, 400. Also, the correction processes shown in FIG. 12 and FIG. 14 are applicable to the second embodiment. [Industrial Applicability]

[0128] As described above, the optical displacement meter according to the present disclosure can be used, for example, to obtain data on the three-dimensional shape of a workpiece. [Explanation of symbols]

[0129] 1. Optical displacement gauge 10, 100 Light emitting / receiving module 11 Light projector 12 Receiving lens 13 Imaging unit 20 Motor 30 Motor control unit 32 Signal Processing Section 52 Encoder W work

Claims

1. a light projection unit that irradiates a slit light extending in the X direction onto the workpiece; An image sensor having a plurality of pixels two-dimensionally arranged in a U direction corresponding to the X direction and a V direction perpendicular to the U direction, and outputting a light receiving amount distribution of reflected light from the work by the plurality of pixels; a motor that rotates the light projecting unit and the image sensor together; a control unit that controls the motor to cause the slit light to scan in a direction perpendicular to the X direction and expose the image sensor while rotating in that direction; a rotation angle acquisition unit that acquires a reference angle corresponding to an exposure period of the image sensor, The control unit is While rotating the image sensor during the exposure period, a peak position in the V direction of a distribution of received light amount obtained by accumulating electric charges in the plurality of pixels is acquired; A representative angle at which the peak position is acquired is estimated based on the reference angle corresponding to the exposure period and a control condition of the image sensor or the motor, and the height of the work in the Z direction at the representative angle is calculated from the peak position. Optical displacement gauge.

2. 2. The optical displacement meter according to claim 1, The rotation angle acquisition unit acquires the reference angle at a start point of the exposure period.

3. 2. The optical displacement meter according to claim 1, The control conditions of the image sensor include at least one of the length of the exposure period or the trigger interval at which the exposure period starts, and the control conditions of the motor include at least one of the angular velocity, the rotation direction, and the number of reciprocating motions of the motor. Optical displacement gauge.

4. 2. The optical displacement meter according to claim 1, the motor rotates the image sensor in a first rotation direction and then rotates the image sensor in a second rotation direction opposite to the first rotation direction; The control unit estimates different representative angles in the first rotation direction and the second rotation direction even when the reference angle acquired by the rotation angle acquisition unit is the same in the first rotation direction and the second rotation direction.

5. 2. The optical displacement meter according to claim 1, The control unit estimates a rotation angle at approximately the center of the exposure period as the representative angle.

6. 2. The optical displacement meter according to claim 1, When the plurality of pixels includes both bright pixels whose amount of light received during the exposure period is equal to or greater than a threshold value and dark pixels whose amount of light received is less than the threshold value, the control unit uses different methods of estimating the representative angle for the bright pixels and the dark pixels.

7. 7. The optical displacement meter according to claim 6, The control unit estimates the rotation angle at approximately the center of the exposure period as the representative angle for the dark pixels, while adjusting the amount of received light that is equal to or greater than the threshold at a predetermined point in the exposure period for the bright pixels, and estimating the rotation angle after the predetermined point in time as the representative angle.

8. 2. The optical displacement meter according to claim 1, a storage unit that stores a plurality of conversion conditions for converting a UV coordinate and a rotation angle into an XYZ coordinate according to a control condition of the image sensor or the motor; The control unit converts the UV coordinates and the reference angle into XYZ coordinates corresponding to the representative angle based on a conversion condition selected from the plurality of conversion conditions in accordance with a control condition of the image sensor or the motor.

9. 9. The optical displacement meter according to claim 8, the plurality of conversion conditions include a conversion condition used for a bright pixel whose amount of received light during the exposure period exceeds a threshold, and a conversion condition used for a dark pixel whose amount of received light does not exceed the threshold, When the plurality of pixels includes both the bright pixels and the dark pixels during the exposure period, the control unit selects, for each pixel, either the conversion condition to be used for the bright pixels or the conversion condition to be used for the dark pixels based on the threshold value.

10. 2. The optical displacement meter according to claim 1, the motor rotates the image sensor in a first rotation direction and then rotates the image sensor in a second rotation direction opposite to the first rotation direction; The control unit controls the start timing of the first exposure period and the start timing of the second exposure period so that both the center of an angle range corresponding to a first exposure period while the image sensor is rotating in the first rotation direction and the center of an angle range corresponding to a second exposure period while the image sensor is rotating in the second rotation direction approximately coincide with the representative angle.

Images