Optical displacement gauge

Abstract

To suppress an influence of regular reflection light from a workpiece surface occurring because of rotation of a light projection system component and a light reception system component.SOLUTION: An optical displacement gauge is a light section system optical displacement gauge for measuring a sectional profile of a workpiece having a height in the Z direction on the basis of a triangular survey principle, and 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 obtained by reflection of slit beams by 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, and a control section for controlling the motor and performing scanning of slit beams in a direction orthogonal to the X direction. When the light projection section applies slit beams to a workpiece having a regular reflection surface parallel with the X-Y plane extending the X direction and Y direction, a rotational angle of the light projection / reception module is restricted such that regular reflection light reflected from the regular reflection surface is not imaged by the imaging section.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

[0002] Conventional optical displacement meters obtain XZ cross-sectional profiles at different positions in the Y direction of the workpiece by moving parallel to the XY plane relative to the measurement target (workpiece), and generate three-dimensional shape data from these profiles. Therefore, with conventional optical displacement meters, the relative angle of the light-emitting and receiving systems with respect to the workpiece surface does not change significantly, and the probability that light specularly reflected from the workpiece surface will enter the light-receiving system is low unless the workpiece is set up for measurement using specular reflection.

[0003] Conventional optical displacement gauges require equipment such as a conveyor for transporting the workpiece, a linear motion mechanism for moving the conventional optical displacement gauge body relative to the workpiece, etc. However, the introduction of the above-mentioned equipment can be hindered by installation space, costs, etc.

[0004] 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]

[0005] [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]

[0006] In optical displacement meters that rotate the light-projecting system and the light-receiving system, the light-projecting system and the light-receiving system are rotated relative to a stationary workpiece to perform measurements, which increases the probability that specularly reflected light from the workpiece surface will enter the light-receiving system.

[0007] However, in Patent Documents 1 and 2, no measures are taken against specularly reflected light from the workpiece surface that occurs due to rotation of the light projecting system and the light receiving system.

[0008] In view of the above problems, the present invention aims to provide an optical displacement gauge that can suppress the effects of specularly reflected light from the workpiece surface caused by rotating the light-projecting system and the light-receiving system. [Means for solving the problem]

[0009] The optical displacement meter of the present invention is, for example, an optical displacement meter of a light-cutting type that measures the cross-sectional profile of a workpiece having a height in the Z direction based on the principle of triangulation, and is equipped with 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 light reflected by the slit light from the 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, and a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction, and when the light projecting unit irradiates the slit light onto the workpiece having a specular reflection surface parallel to an XY plane extending in the X and Y directions, the rotation angle of the light projecting and receiving module is limited so that the specular reflection light reflected from the specular reflection surface is not captured by the imaging unit.

[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 gauge that can suppress the effects of specularly reflected light from the workpiece surface caused by rotating the light-projecting system components and the light-receiving system components. [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 11] A diagram explaining the limitations on the rotation angle of the light emitting and receiving modules [Figure 12] A diagram explaining the limitations on the rotation angle of the light emitting and receiving modules 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 passes through the light projecting lens 15 and is converted into slit light L1. The housing 10 is provided with a light projecting window 16 having light transmissibility that allows the slit light L1 to pass therethrough. Similarly, the housing 10 is provided with a light receiving window 17 having light transmissibility that allows the reflected light L2 to pass therethrough. The light projecting window 16 and the light receiving window 17 are separate bodies (separate components). By having the light projecting window 16 and the light receiving window 17 as separate bodies, the light projecting window 16 and the light receiving window 17 are each a flat plate-shaped component, which makes it easy to manufacture the light projecting window 16 and the light receiving window 17. However, the light projecting window 16 and the light receiving window 17 may be integrated (one component).

[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 19. When the optical displacement meter 1 includes the reflecting member 19, the light receiving unit 18 includes the light receiving lens 12, the imaging unit 13, and the reflecting member 19. The reflecting member 19 is provided on the optical path between the light receiving window 17 and the imaging unit 13, and folds the reflected light L2 and the optical axis AX2 of the light receiving lens 12 back 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 19 to be compactly configured in the YZ plane extending in the Y and Z directions. Therefore, 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 19 can be reduced.

[0029] In FIG. 3, the reflecting member 19 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 19 is provided on the optical path between the light-receiving lens 12 and the imaging unit 13, the reflecting member 19 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 19. When the reflecting member 19 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 into a profile in 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 19, 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 19 (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 19 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 and receiving module 20 includes a base member 201. The base member 201 includes a cylinder portion extending along the X direction, a cover portion closing one end of the cylinder portion in the X direction, and a flange portion extending radially outward from the other end of the cylinder portion in the X direction. The light emitting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 19 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> 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.

[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 and receiving module 20 at a substantially constant speed in a first rotation direction (counterclockwise direction CCW) or a second rotation direction (clockwise direction CW), and a non-measurement period in which the rotation direction of the light emitting and receiving module 20 is switched but the measurement operation is not performed. In the measurement period in which the measurement operation is performed, the motor rotates the light emitting and receiving module 20 at a substantially constant speed. The period in which the rotation direction is switched needs to take deceleration and acceleration into consideration, and calculations such as the correlation between the peak position in the V direction and the rotation angle become complicated, so it is preferable to make it a non-measurement period.

[0057] <Limits on the rotation angle of the light emitting / receiving module> When the light projecting unit 11 irradiates the slit light L1 onto the workpiece W having a specular reflection surface parallel to an XY plane extending in the X and Y directions, the optical displacement meter 1 limits the rotation angle of the light projecting and receiving module 20 so that the specular reflection light reflected from the specular reflection surface of the workpiece W is not captured by the imaging unit 13. This enables the optical displacement meter 1 to suppress the influence of the specular reflection light from the specular reflection surface of the workpiece W that occurs due to the rotation of the light projecting and receiving module 20.

[0058] The optical displacement meter 1 rotates the light projecting and receiving module 20 so that the slit light L1 is irradiated onto the measurement region R2 shown in Fig. 11, while limiting the rotation angle of the light projecting and receiving module 20 so that the slit light L1 is not irradiated onto the region R3 shown in Fig. 11. When the optical displacement meter 1 executes a measurement operation, it advances image processing of the reflected light from the measurement region R2, which is set so that image processing proceeds at least until the three-dimensional data generation unit 28 generates three-dimensional data, at least until the three-dimensional data generation unit 28 generates three-dimensional data. The region R3 is a region where the specularly reflected light reflected from a specular reflection surface parallel to the XY plane of the workpiece W reaches the imaging unit 13.

[0059] The measurement range in the Y direction may be biased toward the light projector 11 side rather than the light receiver 18 side with respect to the light projector axis AX1 parallel to the Z direction. In addition, a first angle range θ1 formed by the light projector axis AX1 passing through the end of the measurement region R2 on the light projector 11 side and the light projector axis AX1 parallel to the Z direction may be larger than a second angle range θ2 formed by the light projector axis AX1 passing through the end of the measurement region R2 on the light receiver 18 side and the light projector axis AX1 parallel to the Z direction.

[0060] When viewed as if the light projecting unit 11 is located to the left of the light receiving lens 12 in the YZ plane extending in the Y and Z directions, the control unit 22 performs a measurement operation by rotating the light projecting and receiving module 20 in a first angle range θ1 to the left of the light projecting axis AX1 of the light projecting unit 11 parallel to the Z direction, and performs a measurement operation by rotating the light projecting and receiving module 20 in a second angle range θ2 that is smaller than the first angle range θ1 and does not include the predetermined angle at which the specular reflected light is focused on the light receiving lens to the right of the light projecting axis AX1 parallel to the Z direction. With this configuration, it is possible to ensure the measurement range while avoiding the adverse effects of specular reflection by measuring in a wide angle range on the left side where specular reflection does not occur and measuring in a narrow angle range where specular reflection does not occur on the right side where specular reflection is likely to occur such as in region R3.

[0061] During a non-measurement period in which the control unit 22 switches the rotation direction of the light emitting and receiving module 20 but does not perform a measurement operation, the control unit 22 may rotate the light emitting and receiving module 20 in a third angle range (region R3) including a rotation angle in which the light projecting axis AX1 and the optical axis AX2 of the light receiving lens 12 are symmetrical with respect to the perpendicular line (Z direction) of the XY plane. Since it is not necessary to consider the influence of specular reflection during the non-measurement period, the design freedom is increased by effectively utilizing the space on the right side for direction switching and maintenance operations.

[0062] The optical displacement meter 1 may also accept, via the communication unit 25, a selection of one of a first mode in which the measurement operation is limited to within a second angle range θ2 on the right side of the projection axis AX2 parallel to the Z direction, and a second mode in which the measurement operation is performed in an angle range that combines the second angle range θ2 and a third angle range θ3 including a predetermined angle at which specular reflection occurs on a surface parallel to the XY plane. For workpieces with a relatively high reflectance, the effect of specular reflection is suppressed by measuring in the limited first mode, while for workpieces with a relatively low reflectance that are unlikely to be affected by receiving specularly reflected light, the measurement efficiency can be increased by measuring in a wide range in the second mode with the restriction removed, thereby improving convenience.

[0063] The restriction of the rotation angle of the light emitting and receiving module 20 may be realized, for example, by the control unit 22 executing control to restrict the rotation angle of the motor 21, or by the optical displacement meter 1 being provided with a stopper that physically stops the movement of the light emitting and receiving module 20.

[0064] The optical displacement meter 1 limits the second angle range θ2 of the light projecting and receiving module 20 as an angle range θM in which the specularly reflected light from a specular reflection surface parallel to the XY plane is not received, based on the angle θTR (see FIG. 12) between the principal ray of the slit light and the principal ray of the reflected light captured by the light receiving lens, the converging angle θT (see FIG. 12) at which the slit light L1 emitted from the light source 14 is converged in the Y direction by the light projecting lens 15, and the light capture angle θR (see FIG. 12) of the light receiving lens 12. More specifically, the optical displacement meter 1 limits the rotation angle θM of the light projecting and receiving module 20 so as to satisfy (θTR-θT-θR) / 2>θM. The converging angle θT is the angle at which the light emitted from the light source 14 is converged in the Y direction by the light projecting lens 15. The above relational expression is a condition for preventing the light ray of the left end of the slit light from passing through the left end of the light receiving angle of the light receiving lens 12 by the specular reflection surface. In addition, since the imaging unit 13 is provided with an image sensor (image sensor) that outputs the distribution of the amount of light received from the work by a plurality of pixels arranged two-dimensionally, the light projecting and receiving module 20 has a predetermined measurement range in the direction of the light projection axis AX1, and the angle θTR becomes the minimum angle at the position farthest from the light projecting unit 11 in the predetermined measurement range. That is, FIG. 12 illustrates the state in which the light reflected from the slit light at the midpoint of the measurement range travels along the optical axis AX2 of the light receiving lens 12, and θTR at this time is defined as the angle X. The angle Y formed by the light reflected at the position farthest from the light projecting unit 11 in the measurement range (below the paper) and the light projecting axis AX1 passing through the principal point of the light receiving lens 12 is smaller than the angle X. Therefore, the control unit 22 controls the motor 21 so as to satisfy the above relational expression at the minimum angle (angle Y) of θTR.

[0065] The optical displacement meter 1 does not limit the rotation angle of the light projecting and receiving module 20 to one direction of rotation (clockwise direction CW shown in Figs. 11 and 12), but limits it to the other direction of rotation (counterclockwise direction CCW shown in Figs. 11 and 12). This is because there is no area where the specular reflected light reflected from the specular reflection surface of the workpiece W reaches the imaging unit 13 outside the measurement area R2 in one direction of rotation (clockwise direction CW shown in Figs. 11 and 12) in the rotation angle range of the light projecting and receiving module 20 where the specular reflected light reflected from the specular reflection surface of the workpiece W does not reach the imaging unit 13, while there is an area R3 where the specular reflected light reflected from the specular reflection surface parallel to the XY plane of the workpiece W reaches the imaging unit 13 outside the measurement area R2 in the other direction of rotation (counterclockwise direction CCW shown in Figs. 11 and 12).

[0066] It is preferable that the optical displacement meter 1 can remove the restriction on the rotation angle of the light emitting and receiving module 20.

[0067] For example, if the control unit 22 realizes a limitation on the rotation angle of the light emitting and receiving module 20 by executing control to limit the rotation angle of the motor 21 during a measurement operation to generate a cross-sectional profile, the control unit 22 can release the limitation on the rotation angle of the light emitting and receiving module 20 by stopping the execution of the control to limit the rotation angle of the motor 21 during an operation other than the measurement operation, such as a maintenance operation.

[0068] Also, for example, if the rotation angle of the light projecting and receiving module 20 is limited by a stopper that physically stops the movement of the light projecting and receiving module 20, the stopper can be made a movable member and moved to a location where it does not come into contact with the light projecting and receiving module 20, thereby lifting the restriction on the rotation angle of the light projecting and receiving module 20.

[0069] The timing at which the optical displacement meter 1 releases the restriction on the rotation angle of the light emitting / receiving module 20 is, for example, the timing at which the optical displacement meter 1 measures the workpiece W that does not have a specular reflection surface parallel to the XY plane, the timing at which the optical displacement meter 1 increases the rotation angle range of the motor 21 compared to that during measurement operation in order to suppress fretting wear on the bearings of the motor 21, etc. In other words, in maintenance operations where the effect on specular reflection is not an issue, it is effective to release the restriction on the rotation angle in order to suppress the above-mentioned fretting wear.

[0070] The rotation angle of the light emitting / receiving module 20 may be determined based on a state in which the top surface of the housing 10 is parallel to the XY plane, or a state in which the side surface of the housing 10 is parallel to the XZ plane extending in the X and Z directions. This simplifies the installation of the optical displacement meter 1 and improves the accuracy of setting the regions R2 and R3.

[0071] The optical displacement meter 1 may further include a polarizing filter for canceling the polarized component of the slit light specularly reflected by the workpiece W. For example, the polarizing filter may be provided in the light receiving window 17. This makes it possible to prevent the specularly reflected light specularly reflected by the surface of the workpiece W that is not parallel to the XY plane from being received by the imaging unit 13. Furthermore, a polarizing filter whose polarization axis is approximately perpendicular to the polarizing filter provided in the light receiving window 17 may be provided in the light projection window 16. This makes it possible to further prevent the specularly reflected light from being received by the imaging unit 13. As the polarizing filter, for example, a linear polarizing plate can be used.

[0072] <Summary> The various embodiments described above will be generally described below.

[0073] For example, the optical displacement meter disclosed in this specification is an optical displacement meter of a light-cutting type that measures a cross-sectional profile of a workpiece having a height in the Z direction based on the principle of triangulation, and includes a light projecting / receiving module having a light projecting unit that irradiates a slit light extending in the X direction, a light receiving lens that collects light reflected by the slit light from the workpiece, and an imaging unit that receives the light collected by the light receiving lens, a motor that rotates the light projecting / receiving module integrally, and a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction, and is configured (first configuration) such that when the light projecting unit irradiates the slit light onto the workpiece having a specular reflection surface parallel to an XY plane extending in the X and Y directions, the rotation angle of the light projecting / receiving module is limited so that the specular reflection light reflected from the specular reflection surface is not captured by the imaging unit.

[0074] In the optical displacement meter having the above-mentioned first configuration, the measurement range in the Y direction may be configured (second configuration) to be biased toward the light projecting unit side relative to the light projecting axis of the light projecting unit, which is parallel to the Z direction, rather than toward the light receiving unit side having the light receiving lens and the imaging unit.

[0075] In an optical displacement meter having the above first or second configuration, when viewed as if the light-projecting unit is located to the left of the light-receiving lens in a YZ plane extending in the Y direction and the Z direction, the control unit may be configured to rotate the light-projecting and receiving module in a first angle range to the left of the light-projecting axis of the light-projecting unit parallel to the Z direction to perform a measurement operation, and to rotate the light-projecting and receiving module in a second angle range that is smaller than the first angle range and does not include a predetermined angle at which the specularly reflected light is focused on the light-receiving lens to the right of the light-projecting axis parallel to the Z direction to perform a measurement operation (third configuration).

[0076] In the optical displacement meter having the third configuration described above, the control unit may be configured (fourth configuration) to rotate the light emitting and receiving module by the motor within a third angle range that includes a rotation angle at which the light emitting axis and the optical axis of the light receiving lens are symmetrical with respect to a perpendicular line to the XY plane during a non-measurement period in which the control unit switches the rotation direction of the light emitting and receiving module while not performing the measurement operation.

[0077] In the optical displacement meter of the third configuration described above, the optical displacement meter may be configured (fifth configuration) to accept selection of one mode from a first mode that limits the measurement operation to within the second angle range to the right of the light projection axis parallel to the Z direction, and a second mode that performs the measurement operation within an angle range that is the combination of the second angle range and a third angle range that includes the specified angle.

[0078] In the optical displacement meter of the third configuration described above, the control unit may be configured (sixth configuration) to control the motor so as to satisfy the relational expression (θTR-θT-θR) / 2>θM, with the second angle range being θM. θTR: Angle between the slit light and the reflected light captured by the light receiving lens θT: Converging angle (half angle) of the slit light θR: Light capture angle of the light receiving lens (half angle)

[0079] In an optical displacement meter having any of the above first to sixth configurations, the imaging unit may be equipped with an image sensor that outputs a light reception distribution of reflected light from the work by a plurality of pixels arranged in a two-dimensional array, so that the light projecting and receiving module has a predetermined measurement range in the light projection axis direction, and the θTR has a minimum angle at a position farthest from the light projecting unit in the predetermined measurement range, and the control unit may be configured to control the motor to satisfy the relational expression at the minimum angle of the θTR (seventh configuration).

[0080] <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]

[0081] 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 171 Incidence plane 172 Exit surface 18 Light receiving part 19 Reflective material 20 Light emitting / receiving module 201 Base material 21 Motor 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 C1 Y-direction center position of measurement area R1 area R2 measurement area R3 area Double work

Claims

1. An optical displacement meter using a light-cutting method that measures a cross-sectional profile of a workpiece having a height in the Z direction based on the principle of triangulation, 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 light reflected by a workpiece from the slit light, 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 control unit that controls the motor to cause the slit light to scan in a direction perpendicular to the X direction, When the light-projecting unit irradiates the slit light onto the workpiece having a specular reflection surface parallel to an XY plane extending in the X and Y directions, the rotation angle of the light-projecting and receiving module is limited so that the specular reflection light reflected from the specular reflection surface is not captured by the imaging unit.

2. 2. The optical displacement meter according to claim 1, wherein the measurement range in the Y direction is biased toward the light projecting unit side relative to a light projecting axis of the light projecting unit that is parallel to the Z direction, rather than toward a light receiving unit side having the light receiving lens and the imaging unit.

3. When viewed so that the light projecting unit is located to the left of the light receiving lens in a Y-Z plane extending in the Y direction and the Z direction, the control unit: a measuring operation is performed by rotating the light emitting / receiving module within a first angle range on the left side of a light projection axis of the light projecting unit parallel to the Z direction; 2. The optical displacement meter according to claim 1, wherein, on the right side of the light projection axis parallel to the Z direction, the measurement operation is performed by rotating the light projection / receiving module within a second angle range that is smaller than the first angle range and does not include a predetermined angle at which the specularly reflected light is focused on the light receiving lens.

4. The optical displacement meter described in claim 3, wherein the control unit rotates the light emitting and receiving module using the motor within a third angle range that includes a rotation angle at which the light emitting axis and the optical axis of the light receiving lens are symmetrical with respect to a perpendicular line to the X-Y plane during a non-measurement period in which the control unit switches the rotation direction of the light emitting and receiving module but does not perform the measurement operation.

5. The optical displacement meter includes: On the right side of the light projection axis parallel to the Z direction, a first mode limiting the measurement operation to within the second angular range; and a second mode in which the measurement operation is performed in a combined angle range of the second angle range and a third angle range including the predetermined angle.

6. 4. The optical displacement meter according to claim 3, wherein the control unit controls the motor so as to satisfy a relational expression (θTR-θT-θR) / 2>θM, where θM is the second angular range. θTR: Angle between the chief ray of the slit light and the chief ray of the reflected light captured by the light receiving lens θT: Converging angle (half angle) of the slit light θR: Light capture angle of the light receiving lens (half angle)

7. The imaging unit includes an image sensor that outputs a light receiving amount distribution of the reflected light from the workpiece by a plurality of pixels that are two-dimensionally arranged, so that the light projecting and receiving module has a predetermined measurement range in the light projection axis direction, The angle θTR is a minimum angle at a position farthest from the light projecting unit within the predetermined measurement range, The optical displacement meter according to claim 6 , wherein the control unit controls the motor so as to satisfy the relational expression at the minimum angle of the θTR.

Images