Optical displacement gauge

Abstract

To suppress an influence of fretting wear.SOLUTION: An optical displacement gauge includes: a light projection / reception module having a light projection section for applying slit beams extending in the X direction, a light receiving lens for condensing reflection light from a workpiece, and an imaging section for receiving light condensed by the light receiving lens; a motor for integrally rotating the light projection / reception module; a bearing for supporting a rotation axis of the light projection / reception module; and a control section for controlling the motor, rotating the light projection / reception module within a first angle range of a measurement object, and performing scanning of slit beams in a direction orthogonal to the X direction. The bearing is rotated up to a second angle range being outside of a measurement object and being outside the first angle range along with the light projection / reception module by rotation of the motor.SELECTED DRAWING: Figure 11A

Description

[Technical field]

[0001] The present invention relates to an optical displacement meter. [Background technology]

[0002] When acquiring XZ cross-sectional profiles at different positions in the Y direction of a measurement target (workpiece) using a conventional optical displacement meter and generating three-dimensional shape data from those profiles, equipment such as a conveyor for transporting the workpiece and a linear motion mechanism for moving the conventional optical displacement meter body relative to the workpiece is required. However, the introduction of the above-mentioned equipment can be hindered by installation space, costs, etc.

[0003] On the other hand, an optical displacement meter that rotates a light projection system and a light receiving system is known as an optical displacement meter that does not require the above-mentioned equipment, can acquire XZ cross-sectional profiles at different positions in the Y direction of the workpiece, and can generate three-dimensional shape data from those profiles (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

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

[0005] In an optical displacement meter that rotates a light-projecting system and a light-receiving system, it is assumed that a bearing is provided to rotatably support the rotor of the motor in order to realize smooth and stable rotation when the light-projecting system and the light-receiving system are rotated by a motor. When the rotor of the motor is caused to reciprocate (oscillate) within a certain rotation angle range, fretting wear occurs depending on the rotation angle range.

[0006] However, in Patent Document 1 and Patent Document 2, no measures are taken against fretting wear.

[0007] In view of the above problems, an object of the present invention is to provide an optical displacement meter capable of suppressing the influence of fretting wear. [Means for solving the problem]

[0008] An optical displacement meter according to one aspect of the present invention includes, for example, a light projecting and receiving module having a light projecting unit that irradiates a slit light extending in an X direction, a light receiving lens that collects reflected light from a workpiece, and an imaging unit that receives the light collected by the light receiving lens; a motor that rotates the light projecting and receiving module as a unit; a bearing that supports a rotation shaft of the light projecting and receiving module; and a control unit that controls the motor to rotate the light projecting and receiving module within a first angle range of the object to be measured and scan the slit light in a direction perpendicular to the X direction, and the bearing rotates together with the light projecting and receiving module by the motor to a second angle range outside the first angle range that is not the object to be measured.

[0009] An optical displacement meter according to another aspect of the present invention includes a light projecting and receiving module having a light projecting unit that irradiates a slit light extending in an X direction, a light receiving lens that collects reflected light from a workpiece, and an imaging unit that receives the light collected by the light receiving lens, a motor that rotates the light projecting and receiving module integrally, a bearing that supports a rotation shaft of the light projecting and receiving module, and a control unit that controls the motor to rotate the light projecting and receiving module within a first angle range of a measurement target, thereby projecting the slit light in a direction perpendicular to the X direction. and a control unit for scanning the bearing in the direction perpendicular to the axis of rotation of the light emitting / receiving module. The bearing has an inner ring, an outer ring, a plurality of rolling elements arranged movably between the inner ring and the outer ring, and a lubricant covering the plurality of rolling elements. As the light emitting / receiving module rotates, the plurality of rolling elements move between the inner ring and the outer ring, and when the light emitting / receiving module rotates from one end to the other end of the first angle range, the movement of the plurality of rolling elements causes the lubricant to penetrate between the inner ring and the rolling elements and between the outer ring and the rolling elements.

[0010] However, other features, elements, steps, advantages, and characteristics will become more apparent from the detailed description that follows and the accompanying drawings related thereto. Effect of the Invention

[0011] According to the present invention, it is possible to provide an optical displacement meter capable of suppressing the influence of fretting wear. [Brief description of the drawings]

[0012] [Figure 1] Diagram explaining the optical displacement measurement system [Diagram 2] Diagram explaining the principle of triangulation [Diagram 3] FIG. 1 is a diagram illustrating an optical displacement meter having a reflecting member. [Figure 4] A diagram explaining a method for detecting peak positions [Diagram 5] Functional block diagram of optical displacement sensor [Figure 6] FIG. 1 is a diagram illustrating a first example of a motor arrangement. [Figure 7] FIG. 1 is a diagram illustrating a first example of a motor arrangement. [Figure 8] FIG. 2 is a diagram illustrating a second example of motor arrangement. [Figure 9] FIG. 2 is a diagram illustrating a second example of motor arrangement. [Figure 10] FIG. 1 is a diagram showing a process flow of the measurement operation of the optical displacement measurement system. [Figure 11A] A diagram explaining the angle range of the light emitting and receiving module [Figure 11B] A diagram explaining the angle range of the light emitting and receiving module [Figure 12A] A diagram explaining the angle range of the light emitting and receiving module [Figure 12B] A diagram explaining the angle range of the light emitting and receiving module [Figure 13A] A diagram explaining the angle range of the light emitting and receiving module [Figure 13B] A diagram explaining the angle range of the light emitting and receiving module [Figure 14] FIG. 1 is a diagram showing an example of a schematic configuration of a bearing; [Figure 15] FIG. 1 is a diagram showing a process flow of a maintenance operation for an optical displacement measurement system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Optical displacement measurement system> 1 is a diagram showing a schematic configuration example of an optical displacement measurement system 100 of this configuration example, which includes an optical displacement meter 1, a control device 2, a display device 3, and an input device 4.

[0014] In this configuration example, the X direction corresponds to the width direction of the slit light L1 output from the optical displacement meter 1, the Z direction corresponds to the height direction of the workpiece W, and the Y direction corresponds to the direction in which the slit light L1 moves due to the rotation of the light projector (not shown in FIG. 1). The XZ plane described below is a plane extending in the X and Z directions. Since the optical displacement meter 1 scans the slit light L1 by rotating the light projector / receiver module 20, the scanning direction of the slit light L1 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 that reciprocates around a rotation axis.

[0015] The optical displacement measurement system 100 is a system that measures the profile and three-dimensional shape of the workpiece W. The profile of the workpiece W is data indicating the outer edge of the cut surface of the workpiece W by the slit light L1. When the slit light is irradiated parallel to the XZ plane, the profile of the workpiece W becomes data indicating the outer edge of the cut surface parallel to the XZ plane, and is therefore also called a two-dimensional profile of the XZ cross section of the workpiece W.

[0016] For example, a profile is a collection of (xi,zi) (i is the index). xi indicates the position in the X direction. zi indicates the height in the Z direction. A three-dimensional shape is a collection of (xi,yi,zi). yi indicates the position in the Y direction.

[0017] The optical displacement meter 1 operates according to instructions from the control device 2. The optical displacement meter 1 outputs a slit light L1 extending in the X direction and receives reflected light L2 from the workpiece W. The optical displacement meter 1 then calculates a profile of the workpiece W based on the light reception result. The optical displacement meter 1 performs imaging at regular intervals to generate profiles of the workpiece W with different yi. In addition, the optical displacement meter 1 generates three-dimensional shape data of the workpiece W from the profiles of the workpiece W with different yi.

[0018] The control device 2 outputs instructions based on user input received by the input device 4 to the optical displacement meter 1, and receives measurement results of the workpiece W from the optical displacement meter 1. The control device 2 also outputs a display signal to the display device 3. The control device 2 is, for example, a personal computer, a programmable logic controller, or the like.

[0019] Based on a display signal from the control device 2, the display device 3 displays, for example, the measurement results of the workpiece W, a UI (user interface) for setting the optical displacement meter 1, and the like.

[0020] The input device 4 accepts a user input to the optical displacement measurement system 100. In Fig. 1, a keyboard and a mouse are illustrated as the input device 4. However, the input device 4 is not limited to a keyboard and a mouse. For example, the input device 4 may be a touch panel arranged on the display screen of the display device 3.

[0021] 2 is a diagram explaining the principle of the light cutting method (triangulation distance measurement). A light projecting unit 11, a light receiving lens 12, and an imaging unit 13 are stored inside a housing 10 of the optical displacement meter 1. The light projecting unit 11 has a light source 14 and a light projecting lens 15. For example, the light source 14 may be a laser light emitter, and the light projecting lens 15 may be composed of a plurality of lenses including a cylindrical lens.

[0022] The light output from the light source 14 is converted into slit light L1 by passing through a light projecting lens 15. The housing 10 is provided with a light projecting window 16 having a light transmitting property that allows the slit light L1 to pass therethrough. Similarly, the housing 10 is provided with a light receiving window 17 having a light transmitting property that allows the reflected light L2 to pass therethrough.

[0023] The light receiving lens 12 is a lens for collecting the reflected light L2 and forming an image on the light receiving surface of the imaging unit 13. The light receiving lens 12 may be configured to include only one lens, or may be configured to include multiple lenses. The light receiving lens 12 may also be configured to include optical components other than lenses (e.g., optical filters, etc.). The imaging unit 13 is an image sensor having multiple photoelectric conversion elements arranged two-dimensionally. The imaging unit 13 receives the light collected by the light receiving lens.

[0024] As shown in FIG. 2, the optical axis AX2 of the light receiving lens 12 is inclined with respect to the projection axis AX1 of the light projecting unit 11. The projection axis AX1 of the light projecting unit 11 coincides with the optical axis of the light source 14. As a result, the reflected light L2 from the height Z1 forms an image at a position V1 in the V direction on the light receiving surface of the imaging unit 13, and the reflected light L2 from the height Z2 forms an image at a position V2 in the V direction on the light receiving surface of the imaging unit 13. That is, the V direction of the light receiving surface of the imaging unit 13 corresponds to the Z direction of the workpiece W. Although the U direction of the light receiving surface of the imaging unit 13 is not shown, the U direction corresponds to the X direction of the workpiece W. That is, the vertical direction of the image, which is the light receiving result output by the imaging unit 13, is the V direction, and the horizontal direction is the U direction.

[0025] Light projecting unit 11, light receiving lens 12, and imaging unit 13 are rotatable about rotation axis AX3 along the X direction while satisfying the Scheimpflug relationship in which the light receiving surface of imaging unit 13 is inclined with respect to the optical axis of light receiving lens 12. The relative positions of light projecting unit 11, light receiving lens 12, and imaging unit 13 are fixed. In Fig. 2, the states of light projecting unit 11, light receiving lens 12, and imaging unit 13 before rotation in the counterclockwise direction CCW are illustrated by solid lines, and the states after rotation in the counterclockwise direction CCW are illustrated by dashed lines.

[0026] The light projecting unit 11, the light receiving lens 12, and the imaging unit 13 can rotate about a rotation axis AX3 along the X direction while satisfying the Scheimpflug relationship. This allows the image to be in focus at each cross section through which the light projecting axis AX1 passes in the shaded area R1 in Fig. 2. In other words, the optical displacement meter 1 can generate a focused profile of the workpiece W even if the height of the workpiece W changes.

[0027] The positional relationship between light projecting unit 11, light receiving lens 12, and imaging unit 13 may be reversed from that shown in FIG.

[0028] 3, the optical displacement meter 1 may further include a reflecting member 18. The reflecting member 18 is provided on the optical path between the light receiving window 17 and the imaging unit 13, and folds back the reflected light L2 and the optical axis AX2 of the light receiving lens 12 toward the light projecting unit 11. This allows the light projecting and receiving module that integrally holds the light projecting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 to be configured compactly in the YZ plane extending in the Y and Z directions. This allows the moment of inertia around the rotation axis AX3 of the light projecting and receiving module that integrally holds the light projecting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 to be reduced.

[0029] In FIG. 3, the reflecting member 18 is provided on the optical path between the light receiving lens 12 and the imaging section 13, but it may also be provided on the optical path between the light receiving window 17 and the light receiving lens 12 (see, for example, FIG. 8 and FIG. 9 described later).

[0030] When the reflecting member 18 is provided on the optical path between the light-receiving lens 12 and the imaging unit 13, the reflecting member 18 reflects the light after being collected by the light-receiving lens 12, and therefore it is possible to reduce the area of ​​the reflecting surface of the reflecting member 18. When the reflecting member 18 is provided on the optical path between the light-receiving window 17 and the light-receiving lens 12, the heavy light-receiving lens 12 can be disposed closer to the rotation axis AX3, which increases the effect of reducing the moment of inertia.

[0031] <Position (height calculation)> 4 is a diagram for explaining a method for calculating the heights constituting the profile from image I1, which is the light reception result output by image capture unit 13. Slit light L1 has a certain width in the Y direction. Therefore, the width of the light spot brought about by reflected light L2 on the light receiving surface of image capture unit 13 also becomes a width that spans multiple photoelectric conversion elements.

[0032] Therefore, the optical displacement meter 1 obtains an approximation curve P1 indicating the change in luminance value from the luminance value of each pixel, and calculates the position in the V direction that brings about the peak value on the approximation curve P1. In FIG. 4, the leftmost column is the column of interest, and the distribution of luminance values ​​of the column of interest (approximation curve P1) is illustrated. The approximation curve P1 is obtained by curve fitting a plurality of sample values, etc. Sample values ​​below the detection threshold are not taken into consideration. The position in the V direction that brings about this peak value indicates the height of the workpiece W. The optical displacement meter 1 obtains an approximation curve P1 at each position (each pixel column) in the U direction, and calculates the position (height) in the V direction that brings about the peak value from the approximation curve P1. By performing this calculation process at each position in the U direction, one profile is obtained. Such calculation process may be called sub-pixel processing.

[0033] Note that, for example, by calibration before shipment, coordinate conversion conditions (e.g., a coordinate conversion table) indicating the correspondence between the UV coordinates and rotation angle θ, as expressed by (U, V, θ)=(X, Y, Z), and the local coordinates (X, Y, Z) are generated and stored in a memory unit (not shown) of the optical displacement meter 1. Therefore, the optical displacement meter 1 can convert the profile in the UV coordinate system to the XYZ coordinate system based on the rotation angle θ through simple calculations.

[0034] <Function block> 5 is a functional block diagram of the optical displacement meter 1. The optical displacement meter 1 includes a light emitting and receiving module 20, a motor 21, and a control unit 22.

[0035] The light projecting and receiving module 20 integrally holds the light projecting unit 11, the light receiving lens 12, and the imaging unit 13. In addition, in the case where the optical displacement meter 1 includes a reflecting member 18, the light projecting and receiving module 20 integrally holds the light projecting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 (not shown in FIG. 5).

[0036] The motor 21 rotates the light projecting unit 11, the light receiving lens 12, and the imaging unit 13. More specifically, the motor 21 rotates the light projecting and receiving module 20. The motor 21 may rotate the light projecting and receiving module 20 by a direct drive method in which no intermediate mechanism such as a reducer is disposed between the motor 21 and the light projecting and receiving module 20, or may rotate the light projecting and receiving module 20 via an intermediate mechanism such as a reducer.

[0037] The control unit 22 includes a motor control unit 23, a signal processing unit 24, and a communication unit 25. The control unit 22 controls the motor 21 to rotate the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 in a state where the Scheimpflug relationship is satisfied, and scans the slit light L1 in a direction perpendicular to the X direction. More specifically, the motor control unit 23 controls the motor 21 to rotate the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 in a state where the Scheimpflug relationship is satisfied, and the signal processing unit 24 controls the light projecting unit 11 to irradiate the slit light L1 from the light projecting unit 11.

[0038] The signal processing unit 24 includes a peak detection unit 26, a profile generation unit 27, and a three-dimensional data generation unit 28. The peak detection unit 26 detects a position (peak position) in the V direction that brings about a peak in the luminance value based on the light reception result output from the imaging unit 13. The profile generation unit 27 generates one profile data by collecting the heights (zi) of the workpiece W at each position (xi) in the X direction obtained by the peak detection unit 26. The three-dimensional data generation unit 28 generates three-dimensional shape data of the workpiece W from the profiles of the workpiece W having different yi generated by the profile generation unit 27. At least a part of the peak detection unit 26, the profile generation unit 27, and the three-dimensional data generation unit 28 may be provided inside the control device 2 (see FIG. 1) instead of inside the optical displacement meter 1.

[0039] The communication unit 25 performs wired or wireless communication with the control device 2. For example, the communication unit 25 receives instructions from the control device 2 and transmits them to the control unit 22. In addition, the communication unit 25 transmits, for example, profile data and three-dimensional shape data of the workpiece W generated by the signal processing unit 24 to the control device 2.

[0040] <Motor placement> Figures 6 and 7 are diagrams for explaining a first example of the arrangement of the motor 21. Figure 6 is a cross-sectional view perpendicular to the X direction of the optical displacement meter 1 taken along line BB' in Figure 7. Figure 7 is a cross-sectional view along the XZ plane of the optical displacement meter 1 taken along line AA' in Figure 6.

[0041] In the first example, the light emitting and receiving module 20 includes a plate-shaped base member 201 extending along a plane perpendicular to the X direction. The light emitting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 are mounted on the base member 201.

[0042] In the first example, the light projecting and receiving module 20 does not overlap with the motor 21 and the accessories of the motor 21 in the X direction. The accessories of the motor 21 are, for example, an encoder that detects the amount of rotation of the rotor of the motor 21. According to the first example of the arrangement of the motor 21, it is easy to arrange the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 close to each other. By arranging the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 close to each other, the light projecting and receiving module 20 can be configured to be compact. Therefore, the moment of inertia around the rotation axis AX3 of the light projecting and receiving module 20 can be reduced.

[0043] In the first example, the control unit 22 does not overlap with the light emitting and receiving module 20 in the X direction, but overlaps with the motor 21 in the X direction.

[0044] Figures 8 and 9 are diagrams for explaining a second example of the arrangement of the motor 21. Figure 8 is a cross-sectional view perpendicular to the X direction of the optical displacement gauge 1 taken along line BB' in Figure 9. Figure 9 is a cross-sectional view perpendicular to the Z direction of the optical displacement gauge 1 taken along line AA' in Figure 8.

[0045] In the second example, the light emitting / receiving module 20 includes a base member 201. The base member 201 includes a tube portion extending along the X direction, a cover portion closing one end of the tube portion in the X direction, and a flange portion extending radially outward from the other end of the tube portion in the X direction. The light emitting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 are mounted on the flange portion of the base member 201.

[0046] In the second example, the light-emitting / receiving module 20 overlaps with at least one of the motor 21 and an accessory of the motor 21 in the X direction. As in the first example, the accessory of the motor 21 is, for example, an encoder that detects the amount of rotation of the rotor of the motor 21. According to the second example of the arrangement of the motor 21, it becomes easy to arrange the light-emitting unit 11 away from the light-receiving lens 12 and the imaging unit 13. By separating the light-emitting unit 11 from the light-receiving lens 12 and the imaging unit 13, the scanning range of the slit light L1 can be expanded.

[0047] Furthermore, in the second example, the control unit 22 overlaps with the light emitting and receiving module 20 and the motor 21 in the X direction. Note that the control unit 22 may be disposed in a position that does not overlap with the motor 21 in the X direction but overlaps with the motor 21 as viewed from the X direction. When the control unit 22 is disposed in a position that does not overlap with the motor 21 in the X direction but overlaps with the motor 21 as viewed from the X direction, the control unit 22 may or may not overlap with the light emitting and receiving module 20 and the motor 21 in the X direction.

[0048] <Processing flow (measurement operation)> Fig. 10 is a diagram showing a process flow of the measurement operation of the optical displacement measurement system 100. When the input device 4 receives a user input instructing the start of measurement, the process flow of Fig. 10 starts. When the optical displacement measurement system 100 executes a measurement operation, the optical displacement meter 1 executes the measurement operation.

[0049] First, in step S1, the light projector 11 starts emitting the slit light L1. In the following step S2, the motor control unit 23 starts rotating the motor 21. Note that the processing of step S1 and the processing of step S2 may be executed simultaneously. Before executing step S1, the motor control unit 23 may rotate the motor to move the light projector / receive module 20 to a predetermined scanning start position. The processing of steps S1 and S2 starts scanning with the slit light L1.

[0050] In the next step S3, the motor control unit 23 determines whether the amount of rotation (rotation angle) of the motor 21 from the start of rotation is smaller than a threshold value. If the amount of rotation of the motor 21 from the start of rotation is smaller than the threshold value, the determination process of step S3 continues, and the scanning of the slit light L1 continues.

[0051] When the amount of rotation of the motor 21 from the start of rotation reaches the threshold, the flow proceeds to step S4. The threshold is the amount of rotation calculated based on the measurement range. The measurement range is set as a default, and when the measurement range is changed by the user, the control unit 22 (e.g., the signal processing unit 24) calculates the threshold of the amount of rotation based on the measurement range after the change.

[0052] In step S4, motor control unit 23 stops the rotation of motor 21. In the following step S5, light projector 11 stops emitting slit light L1. Note that steps S4 and S5 may be performed simultaneously. The scanning of slit light L1 is completed by the processes of steps S4 and S5.

[0053] In the next step S6, the profile generator 27 generates a profile. The profile generator 27 may start generating a profile during scanning with the slit light L1.

[0054] In the following step S7, the three-dimensional data generator 28 generates three-dimensional data.

[0055] In the following step S8, the display device 3 displays the measurement results. The measurement results are, for example, a cross-sectional view of the workpiece W based on the profile, a three-dimensional image of the workpiece W based on the three-dimensional data, etc. When the process of step S8 ends, the process flow of FIG. 10 ends.

[0056] The optical displacement meter 1 has a measurement period in which the measurement operation is performed by rotating the light emitting / receiving module 20 at a substantially constant speed in a first rotation direction (counterclockwise CCW direction) or a second rotation direction (clockwise CW direction), and a non-measurement period in which the measurement operation is not performed. In the measurement period in which the measurement operation is performed, the motor rotates the light emitting / receiving module 20 at a substantially constant speed. The non-measurement period includes at least a start-up period from start-up to moving to the first measurement operation, a maintenance operation period described later, a deceleration period for decelerating from a constant speed and stopping with the end of a measurement operation in one direction of rotation, an acceleration period for reaching a constant speed from a stopped state to start a measurement operation in the other direction of rotation, and a termination period from the end of the last measurement operation to the power being turned off. The deceleration period or acceleration period is also called a rotation direction switching period. If deceleration and acceleration occur in these periods, it is preferable to make them non-measurement periods because calculations such as the association between the peak position in the V direction and the rotation angle become complicated.

[0057] <Angle range of light emitting / receiving module> FIG. 11A is a diagram for explaining the angle range of the light emitting / receiving module 20 when the optical displacement meter 1 performs a maintenance operation. FIG. 11B is a diagram for explaining the angle range when the optical displacement meter 1 performs a switching operation of the rotation direction of the light emitting / receiving module 20 without performing a maintenance operation. The angle range of the light emitting / receiving module 20 has a first angle range θ1 of the measurement object, a second angle range θ2 for a maintenance operation of the object not to be measured, and a third angle range θ3 for a switching operation of the rotation direction of the object not to be measured. The first angle range θ1 is determined based on the measurement range set by default or by the user. The second angle range θ2 is determined based on the first angle range θ1 and the specifications of the bearing 210. The third angle range θ3 is determined based on the angular velocity of the motor 21, the moment of inertia, the specifications of the bearing 210, and the like. The control unit 22 controls the motor 21 to rotate the light emitting / receiving module 20 in the first angle range θ1 of the measurement object, and scans the slit light L1 in a direction perpendicular to the X direction. When the maintenance operation is to be performed, the control unit 22 controls the motor 21 to rotate the light emitting / receiving module 20 in the second angle range θ2 following the first angle range θ1, thereby performing the maintenance operation, and stops the motor 21 in the third angle range θ3 for the rotation direction switching operation. In other words, the light emitting / receiving module 20 is configured to be rotatable up to an angle range (also called a non-measurement angle range) that is a combination of the second angle range θ2 and the third angle range θ3, by the rotation of the motor 21. The rotation direction switching period is set as a non-measurement period because deceleration and acceleration must be taken into account, which complicates the calculation, and the rotation range can be effectively utilized by performing the maintenance operation during that period. When the maintenance operation is not to be performed, the control unit 22 controls the motor 21 to rotate the light emitting / receiving module 20 in the third angle range θ3 following the first angle range θ1. When the maintenance operation is not to be performed for each measurement operation, there is no need to rotate the light emitting / receiving module 20 in the second angle range θ2 and the third angle range θ3, so that the tact time can be shortened by switching the rotation direction in the minimum range (the third angle range θ3).

[0058] With this configuration, even if the first angle range θ1 is small, the occurrence of fretting wear in the motor 21 can be suppressed by rotating the light emitting / receiving module 20 at least to the second angle range θ2 for maintenance operation. As a result, the optical displacement meter 1 can suppress the influence of fretting wear (reduced life due to fretting wear). It can also be said that the optical displacement meter 1 performs maintenance operation by rotating the light emitting / receiving module 20 in a non-measurement angle range that is the combination of the second angle range θ2 and the third angle range θ3.

[0059] Here, the first angle range θ1 of the measurement target means an angle range in which image processing is set to proceed at least until three-dimensional data is generated by the three-dimensional data generating unit 28. On the other hand, the second angle range θ2 and the third angle range θ3 of the measurement target mean angle ranges in which image processing is set not to proceed until three-dimensional data is generated by the three-dimensional data generating unit 28. Therefore, in the second angle range θ2 and the third angle range θ3 of the measurement target, image processing may proceed until a profile is generated by the profile generating unit 27, or image processing may not proceed until a profile is generated by the profile generating unit 27.

[0060] When the optical displacement meter 1 performs a measurement operation, the motor control unit 23 starts the rotation of the motor 21, and the rotation of the motor 21 accelerates and then becomes constant, after which the rotation of the motor 21 decelerates and stops. The angular range of the light emitting and receiving module 20 during the period when the motor 21 rotates at a constant speed is the first angular range θ1 to be measured. The angular range of the light emitting and receiving module 20 during the non-measurement period is at least one of the second angular range θ2 and the third angular range θ3 that are not to be measured. By performing a maintenance operation during the period when a measurement operation is not performed, the occurrence of a breakdown can be suppressed without reducing the takt time.

[0061] In Fig. 11A and Fig. 11B, the second angle range θ2 and the third angle range θ3 are formed on the outside of the first angle range θ1 in the counterclockwise direction CCW. As shown in Fig. 12A and Fig. 12B, the second angle range θ2 and the third angle range θ3 may be formed on the outside of the first angle range θ1 in the clockwise direction CW. As shown in Fig. 13A and Fig. 13B, the second angle range θ2 and the third angle range θ3 may be divided into two ranges and formed both on the outside of the first angle range θ1 in the counterclockwise direction CCW and on the outside of the first angle range θ1 in the clockwise direction CW. In Fig. 13A and Fig. 13B, the two ranges constituting the second angle range θ2 and the third angle range θ3 are the same size, but may be different sizes.

[0062] The motor 21 has a bearing 210. The bearing 210 rotatably supports the rotor of the motor 21. In this embodiment, since the motor 21 is a direct drive type that directly rotates the light emitting and receiving module 20, the bearing 210 can also be considered to be provided on the rotation shaft of the light emitting and receiving module. When an intermediate mechanism such as a reducer is used, bearings are provided on both the rotation shaft of the motor and the rotation shaft of the light emitting and receiving module. FIG. 14 is a diagram showing a schematic configuration example of the bearing 210. The bearing 210 has an inner ring 211, an outer ring 212, a plurality of rolling elements 213 arranged movably between the inner ring 211 and the outer ring 212, and a lubricant that covers the plurality of rolling elements 213. The plurality of rolling elements 213 move between the inner ring 211 and the outer ring 212 due to the rotation of the light emitting and receiving module 20. The number and shape of the rolling elements 213 are not limited to the example shown in FIG. 14. Therefore, the bearing 210 may be, for example, a cross roller bearing, a ball bearing, a needle bearing, or the like.

[0063] When the light emitting / receiving module 20 rotates in either the counterclockwise direction CCW or the clockwise direction CW from one end to the other end of the combined range of the first angle range θ1 and the second angle range θ2, the movement of the multiple rolling elements 213 causes the lubricant to penetrate between the inner ring 211 and the rolling elements 213 and between the outer ring 212 and the rolling elements 213. This suppresses contact between the inner ring 211 and the rolling elements 213 and between the outer ring 212 and the rolling elements 213, suppressing fretting wear. As a result, the optical displacement meter 1 can suppress the effects of fretting wear (reduced life due to fretting wear).

[0064] When the light projector / receiver module 20 rotates in either the counterclockwise direction CCW or the clockwise direction CW from one end to the other end of the range defined by the combination of the first angle range θ1 and the second angle range θ2, it is preferable that the rolling element 213 rotates half a turn or more. As a result, if there is lubricant around the rolling element 213, the lubricant will be distributed around the entire circumference of the rolling element 213 by the light projector / receiver module 20 rotating in either the counterclockwise direction CCW or the clockwise direction CW from one end to the other end of the range defined by the combination of the first angle range θ1 and the second angle range θ2. This can enhance the effect of suppressing fretting wear.

[0065] It is more preferable that the rolling element 213 rotates one or more revolutions if the light projecting and receiving module 20 rotates in either the counterclockwise direction CCW or the clockwise direction CW from one end to the other end of the range defined by the combination of the first angle range θ1 and the second angle range θ2. As a result, if there is lubricant around the rolling element 213, the lubricant will be distributed around the entire circumference of the rolling element 213 by the light projecting and receiving module 20 rotating in either the counterclockwise direction CCW or the clockwise direction CW from one end to the other end of the range defined by the combination of the first angle range θ1 and the second angle range θ2. This further enhances the effect of suppressing fretting wear.

[0066] In addition, it is preferable that the first angle range θ1 is smaller than the angle θB between two adjacent rolling bodies 213, while the combined range of the first angle range θ1 and the second angle range θ2 is set to be equal to or larger than the angle between two adjacent rolling bodies 213. As a result, if the light emitting / receiving module 20 rotates in either the counterclockwise direction CCW or the clockwise direction CW from one end to the other end of the combined range of the first angle range θ1 and the second angle range θ2, the rolling body 213 moves to at least the position of the adjacent rolling body 213. As a result, a film of lubricant is formed on the raceway surface on which the rolling body 213 of the inner ring 211 rolls and the raceway surface on which the rolling body 213 of the outer ring 212 rolls, and a film of lubricant is formed on the entire outer circumference of the inner ring 211 and the entire inner circumference of the outer ring 212. Therefore, the effect of suppressing fretting wear can be enhanced.

[0067] It is preferable that a lubricant pool is formed between two adjacent rolling elements 213, and when the light emitting / receiving module 20 rotates from one end to the other end of the combined range of the first angle range θ1 and the second angle range θ2 in either the counterclockwise direction CCW or the clockwise direction CW, the rolling elements 213 pass through the adjacent pools while rotating. This ensures that a film of lubricant is formed on the raceway surface on which the rolling elements 213 of the inner ring 211 roll and on the raceway surface on which the rolling elements 213 of the outer ring 212 roll. This further enhances the effect of suppressing fretting wear.

[0068] <Processing flow (maintenance operation)> 15 is a diagram showing a process flow of the maintenance operation of the optical displacement measurement system 100. When the optical displacement measurement system 100 executes the maintenance operation, the optical displacement meter 1 executes the maintenance operation.

[0069] For example, the process flow of FIG. 15 may be started each time the process flow of FIG. 10 ends. In this case, the optical displacement meter 1 executes a maintenance operation each time a measurement operation is executed. For example, the motor control unit 23 executes a measurement operation by rotating the light emitting / receiving module 20 in the clockwise direction CW in the first angle range θ1, and then executes a maintenance operation by further rotating the light emitting / receiving module 20 in the clockwise direction CW in the second angle range θ2, and then decelerates and stops the light emitting / receiving module 20 in the third angle range θ3. The motor control unit 23 rotates the light emitting / receiving module 20 in the counterclockwise direction CCW using the third angle range θ3 and a part of the second angle range θ2, and stops the light emitting / receiving module 20 at a predetermined position to accelerate to a rotation speed required for the measurement operation in the first angle range θ1 in the counterclockwise direction CCW. Thereafter, when the motor control unit 23 receives a trigger (instruction) to start the next measurement operation, it rotates the light emitting and receiving module 20 in the counterclockwise direction CCW while accelerating, then performs the next measurement operation at a constant rotation speed, then rotates it further in the counterclockwise direction CCW in a second angle range θ2 to perform a maintenance operation, and then decelerates and stops it in a third angle range θ3. By repeating the above operations, the maintenance operation can be performed during the replacement of the workpiece W between measurement operations, so that the maintenance operation can be performed efficiently in terms of time.

[0070] 15 may be started when the optical displacement meter 1 is started (more specifically, immediately after the start). That is, during the above-mentioned start-up period, the control unit 22 performs a maintenance operation by rotating the light emitting / receiving module 20 at least through the second angle range θ2, and then rotates it to the start position of the first measurement operation. In this case, the optical displacement meter 1 performs a maintenance operation when the optical displacement meter 1 is started.

[0071] 15 may be started when the optical displacement meter 1 is terminated (more specifically, immediately before the termination). That is, during the above-mentioned termination period, the control unit 22 performs a maintenance operation by rotating the light emitting / receiving module 20 at least through the second angle range θ2, and then turns off the power. In this case, the optical displacement meter 1 performs a maintenance operation when the optical displacement meter 1 is terminated. By performing a maintenance operation at the start-up or termination time when it is less likely to affect the takt, it is possible to efficiently prevent the occurrence of failures.

[0072] 15 may be started every time the measurement operation is performed a specified number of times. In this case, the optical displacement meter 1 performs the maintenance operation every time the measurement operation is performed a specified number of times. The value of the specified number of times is stored, for example, in a memory built into the optical displacement meter 1 or the control device 2. It is preferable that the value of the specified number of times can be changed by a user input received by the input device 4.

[0073] 15 may be started every time a specified time elapses. In this case, the optical displacement meter 1 executes a maintenance operation every time a specified time elapses. The value of the specified time is stored in, for example, a memory built into the optical displacement meter 1 or the control device 2. It is preferable that the value of the specified time can be changed by a user input received by the input device 4.

[0074] Also, for example, the process flow of FIG. 15 may be started by a user input instructing the execution of a maintenance operation. In this case, the optical displacement meter 1 executes the maintenance operation in response to a user input instructing the execution of the maintenance operation. The optical displacement meter 1 may provide the control device 2 with information based on the elapsed time since the most recent execution of the maintenance operation, and the control device 2 may cause the display device 3 to display based on the information. This makes it possible to present information that is helpful to a user who is considering whether or not to instruct the execution of the maintenance operation. The information may be, for example, the elapsed time itself since the most recent execution of the maintenance operation, or a flag or message for prompting the maintenance operation that is generated when the elapsed time since the most recent execution of the maintenance operation is equal to or longer than a certain time. Also, the optical displacement meter 1 may receive an instruction to execute a maintenance operation from a user, count the number of times the rotation direction of the light emitting / receiving module 20 is switched by the measurement operation after the maintenance operation, and when the number of times of switching reaches a predetermined number, stop the execution of the measurement operation until receiving an instruction to execute a new maintenance operation. This stops the measurement operation until the maintenance operation is executed, thereby suppressing the occurrence of fretting wear. For example, the motor control unit 23 counts the number of switching operations, and the communication unit 25 accepts an instruction to perform a maintenance operation from a user.

[0075] First, in step S11, the motor control unit 23 starts the rotation of the motor 21.

[0076] In the next step S12, the motor control unit 23 determines whether the light emitting and receiving module 20 has rotated from one end to the other end of the range of the first angle range θ1 and the second angle range θ2 combined. If the light emitting and receiving module 20 has not rotated from one end to the other end of the range of the first angle range θ1 and the second angle range θ2 combined, the determination process of step S12 continues, and the motor 21 continues to rotate.

[0077] When the light emitting and receiving module 20 has rotated from one end to the other end of the combined range of the first angle range θ1 and the second angle range θ2, the flow proceeds to step S13.

[0078] In step S13, the motor control unit 23 causes the motor 21 to stop rotating.

[0079] When the process of step S13 ends, the process flow of FIG. 15 ends.

[0080] In the maintenance operation, since it is not necessary to measure the shape of the workpiece W, it is not necessary to determine the rotation speed in consideration of the exposure time of the imaging unit 13. Therefore, the rotation speed of the light emitting and receiving module 20 in the maintenance operation may be faster than the rotation speed of the light emitting and receiving module in the measurement operation. This makes it possible to shorten the time required for the maintenance operation.

[0081] In addition, when the rotation of the light emitting and receiving module 20 in the maintenance operation is not uniform, the maximum rotation speed of the light emitting and receiving module 20 in the maintenance operation may be regarded as the rotation speed of the light emitting and receiving module 20 in the maintenance operation to be compared with the rotation speed of the light emitting and receiving module 20 in the measurement operation. For example, when moving to the maintenance operation after the measurement operation, the control unit 22 may accelerate from the constant rotation speed during the measurement operation to start the maintenance operation. Similarly, when the rotation of the light emitting and receiving module 20 in the measurement operation is not uniform, the maximum rotation speed of the light emitting and receiving module 20 in the measurement operation may be regarded as the rotation speed of the light emitting and receiving module 20 in the measurement operation to be compared with the rotation speed of the light emitting and receiving module 20 in the maintenance operation. In addition, in the maintenance operation, the measurement operation (at least the operation in which image processing proceeds to the generation of three-dimensional data by the three-dimensional data generating unit 28) may be performed while the light emitting and receiving module 20 is rotating in the first angle range θ1.

[0082] In the above description, the first angle range θ1 for the measurement operation, the second angle range θ2 for the maintenance operation, and the third angle range θ3 for the switching of the rotation direction are distinguished from each other, but the present invention is not limited to including the second angle range θ2 for the maintenance operation. For example, if the light emitting / receiving module 20 rotates from one end to the other end of the angle range that combines the first angle range θ1 for the measurement operation and the third angle range θ3 for the switching of the rotation direction, the lubricant will infiltrate between the inner ring and the rolling elements and between the outer ring and the rolling elements due to the movement of the multiple rolling elements of the bearing 210, and therefore the maintenance operation is essentially performed at the same time, so that fretting wear can be suppressed. Note that, when the measurement operation is performed even during the switching operation of the rotation direction (deceleration period and acceleration period), there is substantially no distinction between the first angle range θ1 and the third angle range θ3, and the third angle range θ3 is included in the first angle range θ1. Therefore, when the light emitting / receiving module 20 rotates from one end to the other end of the first angle range θ1 for measurement operation, even if the movement of the multiple rolling bodies of the bearing 210 causes lubricant to penetrate between the inner ring and the rolling bodies and between the outer ring and the rolling bodies, a maintenance operation is essentially performed at the same time, thereby suppressing fretting wear.

[0083] <Summary> The various embodiments described above will be generally described below.

[0084] For example, a first optical displacement meter disclosed in this specification includes a light projecting and receiving module having a light projecting unit that irradiates a slit light extending in the X direction, a light receiving lens that collects reflected light from a workpiece, and an imaging unit that receives the light collected by the light receiving lens, a motor that rotates the light projecting and receiving module as a unit, a bearing that supports the rotation shaft of the light projecting and receiving module, and a control unit that controls the motor to rotate the light projecting and receiving module within a first angle range of the measurement object and scan the slit light in a direction perpendicular to the X direction, and the bearing is configured to rotate by the motor together with the light projecting and receiving module to a second angle range outside the first angle range that is not the measurement object (first configuration).

[0085] In the optical displacement meter of the above-mentioned first configuration, the bearing may have an inner ring, an outer ring, multiple rolling elements arranged to be movably disposed between the inner ring and the outer ring, and a lubricant covering the multiple rolling elements, and the multiple rolling elements move between the inner ring and the outer ring as the light projector and receiver module rotates, and when the light projector and receiver module rotates from one end to the other end of a range that is the combined range of the first angle range and the second angle range, the movement of the multiple rolling elements causes the lubricant to penetrate between the inner ring and the rolling elements and between the outer ring and the rolling elements (second configuration).

[0086] In the optical displacement meter having the second configuration described above, the optical transmitter / receiver module may be configured so that the rolling body rotates more than half a turn when the light transmitter / receiver module rotates from one end to the other end of the combined range of the first angle range and the second angle range (third configuration).

[0087] In the optical displacement meter having the second or third configuration described above, the first angle range may be smaller than the angle between two adjacent rolling bodies, while the combined range of the first angle range and the second angle range is set to be greater than or equal to the angle between the two adjacent rolling bodies (fourth configuration).

[0088] In an optical displacement meter having any of the second to fourth configurations described above, a lubricant accumulation area may be formed between two adjacent rolling elements, and when the light projector / receiver module rotates from one end to the other end of a range that combines the first angle range and the second angle range, the multiple rolling elements may pass through the adjacent accumulation areas while rotating (fifth configuration).

[0089] In an optical displacement meter having any of the above first to fifth configurations, the optical displacement meter may be configured to be capable of performing a measurement operation and a maintenance operation, and the control unit may be configured (sixth configuration) to control the motor to rotate the light emitting and receiving module within the first angle range during the measurement operation, and to control the motor to rotate the light emitting and receiving module at least within the second angle range during the maintenance operation.

[0090] In the optical displacement meter of the sixth configuration described above, the optical displacement meter has a measurement period in which a measurement operation is performed by rotating the light emitting and receiving module in a first rotation direction or a second rotation direction opposite to the first rotation direction, and a non-measurement period in which the measurement operation is not performed, and the control unit may be configured to perform the maintenance operation by rotating the light emitting and receiving module at least within the second angle range during the non-measurement period (seventh configuration).

[0091] In the optical displacement meter of the seventh configuration described above, the non-measurement period may include a startup period from when the optical displacement meter is powered on to when the first measurement operation starts, or an end period from when the last measurement operation ends to when the optical displacement meter is powered off, and the control unit may be configured to perform the maintenance operation by rotating the light emitting and receiving module at least through the second angle range during the startup period, and then rotate it to the start position of the first measurement operation, or to perform the maintenance operation by rotating the light emitting and receiving module at least through the second angle range during the end period, and then turn off the power (eighth configuration).

[0092] In an optical displacement meter having the seventh or eighth configuration described above, the control unit may be configured to rotate the light projector and receiver module at approximately the same speed in the first rotation direction or the second rotation direction during the measurement period to perform the measurement operation, and to rotate the light projector and receiver module within the second angle range during the non-measurement period to perform the maintenance operation, and to stop the light projector and receiver module in a third angle range for switching the rotation direction of the light projector and receiver module (ninth configuration).

[0093] In the optical displacement meter having any of the seventh to ninth configurations above, the control unit may be configured (tenth configuration) to perform the maintenance operation by rotating the light emitting and receiving module through the second angle range at a faster speed than during the measurement operation.

[0094] In the optical displacement meter of the 9th configuration above, the control unit may be configured to selectively execute a first mode in which, during the non-measurement period, the maintenance operation and switching of the rotation direction of the light projector and receiver module are performed by rotating the light projector and receiver module within the second angle range and the third angle range, and a second mode in which the rotation direction is switched without performing the maintenance operation by rotating the light projector and receiver module within the third angle range (11th configuration).

[0095] In the optical displacement gauges of the seventh to eleventh configurations described above, the optical displacement gauge may be configured (twelfth configuration) to receive an instruction from a user to perform the maintenance operation, count the number of times the rotational direction of the light emitting and receiving module is switched by the measurement operation after the maintenance operation, and when the number of times of switching reaches a predetermined number, stop execution of the measurement operation until a new instruction to perform the maintenance operation is received.

[0096] For example, a second optical displacement meter disclosed in this specification includes a light projecting and receiving module having a light projecting unit that irradiates a slit light extending in the X direction, a light receiving lens that collects reflected light from a workpiece, and an imaging unit that receives the light collected by the light receiving lens, a motor that rotates the light projecting and receiving module integrally, a bearing that supports a rotation shaft of the light projecting and receiving module, and a motor that controls the light projecting and receiving module to rotate within a first angle range of a measurement target, and scan the slit light in a direction perpendicular to the X direction. and a control unit for controlling the rotation of the light emitting and receiving module so as to rotate the light emitting and receiving module, the bearing has an inner ring, an outer ring, a plurality of rolling elements arranged to be movable between the inner ring and the outer ring, and a lubricant covering the plurality of rolling elements, and as the light emitting and receiving module rotates from one end to the other end of the first angle range, the movement of the plurality of rolling elements causes the lubricant to penetrate between the inner ring and the rolling elements and between the outer ring and the rolling elements (thirteenth configuration).

[0097] In the optical displacement meter of the thirteenth configuration, the rolling element may rotate half a turn or more when the light projecting and receiving module rotates from one end to the other end of the first angle range (fourteenth configuration).

[0098] In the optical displacement meter having the thirteenth or fourteenth configuration, the first angle range may be set to be equal to or larger than the angle between two adjacent rolling elements (fifteenth configuration).

[0099] In an optical displacement meter having any of the above-mentioned configurations 13 to 15, a lubricant accumulation area may be formed between two adjacent rolling bodies, and when the light projector / receiver module rotates from one end to the other end of the first angle range, each of the multiple rolling bodies may pass through the adjacent accumulation areas while rotating (configuration 16).

[0100] <Other Modifications> In addition to the above-mentioned embodiment, various technical features disclosed in this specification can be modified in various ways without departing from the spirit of the technical creation. In other words, the above-mentioned embodiment should be considered to be illustrative and not restrictive in all respects, and the technical scope of the present invention is defined by the claims, and should be understood to include all modifications that fall within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0101] 1. Optical displacement gauge 2. Control device 3 Display device 4 Input Devices 10. Housing 11 Light projector 12 Receiving lens 13 Imaging unit 14 Light source 15 Projection lens 16 Floodlight 17 Light receiving window 18 Reflective material 20 Light emitting / receiving module 201 Base material 21 Motor 210 Bearing 211 Inner Circle 212 Outer ring 213 Rolling elements 22 Control section 23 Motor control unit 24 Signal Processing Section 25 Communications Department 26 Peak detector 27 Profile Generation Unit 28 3D Data Generation Division 100 Optical Displacement Measurement System AX1 light emitting axis AX2 optical axis I1 Image AX3 Rotation Axis R1 area Double work

Claims

1. a light projecting and receiving module including a light projecting unit that projects a slit light extending in the X direction, a light receiving lens that collects the light reflected from the workpiece, and an imaging unit that receives the light collected by the light receiving lens; a motor for rotating the light emitting and receiving modules together; a bearing for supporting a rotation shaft of the light emitting / receiving module; a control unit that controls the motor to rotate the light emitting / receiving module within a first angle range of a measurement target, and scans the slit light in a direction perpendicular to the X direction; Equipped with The bearing is rotated by the motor together with the light emitting and receiving module to a second angle range outside the first angle range that is not subject to measurement.

2. the bearing includes an inner ring, an outer ring, a plurality of rolling elements movably disposed between the inner ring and the outer ring, and a lubricant covering the plurality of rolling elements; the plurality of rolling elements move between the inner ring and the outer ring due to rotation of the light emitting / receiving module; 2. The optical displacement meter of claim 1, wherein when the light emitting / receiving module rotates from one end to the other end of a range that is the combined range of the first angle range and the second angle range, the movement of the multiple rolling bodies causes the lubricant to penetrate between the inner ring and the rolling bodies and between the outer ring and the rolling bodies.

3. 3. The optical displacement meter according to claim 2, wherein when the light emitting / receiving module rotates from one end to the other end of a range that is a combination of the first angle range and the second angle range, the rolling element rotates by half a turn or more.

4. 3. The optical displacement meter according to claim 2, wherein the first angle range is smaller than the angle between two adjacent rolling elements, while the combined range of the first angle range and the second angle range is set to be equal to or greater than the angle between two adjacent rolling elements.

5. 3. The optical displacement meter of claim 2, wherein a lubricant accumulation area is formed between two adjacent rolling bodies, and when the light emitting / receiving module rotates from one end to the other end of a range that is the combined range of the first angle range and the second angle range, the plurality of rolling bodies pass through the adjacent accumulation areas while rotating.

6. The optical displacement meter is configured to be capable of performing a measurement operation and a maintenance operation, The control unit is In the measurement operation, the motor is controlled to rotate the light emitting and receiving module within the first angle range; 2. The optical displacement meter according to claim 1, wherein the motor is controlled so as to rotate the light emitting and receiving module at least within the second angle range in the maintenance operation.

7. The optical displacement meter includes: a measurement period in which the light emitting / receiving module is rotated in a first rotation direction or a second rotation direction opposite to the first rotation direction to perform a measurement operation; a non-measurement period during which the measurement operation is not performed; The optical displacement meter according to claim 6 , wherein the control unit executes the maintenance operation by rotating the light emitting and receiving module at least within the second angle range during the non-measurement period.

8. the non-measurement period includes a start-up period from when the optical displacement meter is powered on until the first measurement operation starts, or a termination period from when the last measurement operation ends until the optical displacement meter is powered off, The control unit is During the startup period, the maintenance operation is performed by rotating the light emitting / receiving module at least through the second angle range, and then the light emitting / receiving module is rotated to a start position of the first measurement operation; or 8. The optical displacement meter according to claim 7, wherein, in the termination period, the maintenance operation is performed by rotating the light emitting and receiving module at least through the second angle range, and then the power is turned off.

9. The control unit is During the measurement period, the measurement operation is performed by rotating the light emitting / receiving module at a substantially constant speed in the first rotation direction or the second rotation direction; 8. The optical displacement meter according to claim 7, wherein during the non-measurement period, the maintenance operation is performed by rotating the light emitting / receiving module within the second angle range, and the light emitting / receiving module is stopped within a third angle range for switching the rotation direction of the light emitting / receiving module.

10. The optical displacement meter according to claim 9 , wherein the control unit executes the maintenance operation by rotating the light emitting and receiving module through the second angle range at a higher speed than during the measurement operation.

11. The control unit, during the non-measurement period, a first mode in which the maintenance operation and the switching of the rotation direction of the light emitting and receiving module are performed by rotating the light emitting and receiving module within the second angle range and the third angle range; 10. The optical displacement meter according to claim 9, wherein a first mode is selectively executed by rotating the light emitting and receiving module within the third angle range to switch the rotation direction without executing the maintenance operation.

12. The optical displacement meter includes: receiving an instruction to perform the maintenance operation from a user, and counting the number of times the rotation direction of the light emitting / receiving module is switched by the measurement operation after the maintenance operation; The optical displacement meter according to claim 7 , wherein when the number of switchings reaches a predetermined number, execution of the measurement operation is stopped until a new instruction to execute the maintenance operation is received.

13. a light projecting and receiving module including a light projecting unit that projects a slit light extending in the X direction, a light receiving lens that collects the light reflected from the workpiece, and an imaging unit that receives the light collected by the light receiving lens; a motor for rotating the light emitting and receiving modules together; a bearing for supporting a rotation shaft of the light emitting / receiving module; a control unit that controls the motor to rotate the light emitting / receiving module within a first angle range of a measurement target, and scans the slit light in a direction perpendicular to the X direction; the bearing includes an inner ring, an outer ring, a plurality of rolling elements movably disposed between the inner ring and the outer ring, and a lubricant covering the plurality of rolling elements; the plurality of rolling elements move between the inner ring and the outer ring due to rotation of the light emitting / receiving module; An optical displacement meter in which, when the light emitter / receiver module rotates from one end to the other end of the first angle range, the movement of the multiple rolling bodies causes the lubricant to penetrate between the inner ring and the rolling bodies and between the outer ring and the rolling bodies.

14. 14. The optical displacement meter according to claim 13, wherein the rolling element rotates more than half a turn when the light emitting / receiving module rotates from one end to the other end of the first angle range.

15. The optical displacement meter according to claim 13 , wherein the first angular range is set to be equal to or larger than an angle between two adjacent rolling elements.

16. 14. The optical displacement meter according to claim 13, wherein a lubricant pool is formed between two adjacent rolling bodies, and when the light projector / receiver module rotates from one end to the other end of the first angle range, each of the rolling bodies passes through the adjacent pool while rotating.

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