Optical displacement gauge

Abstract

To suppress deterioration of light reception performance because of a change in a relative angle between a light reception window and an optical axis of a light receiving lens.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 from the 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 housing for storing the light projection / reception module and providing a light reception window for transmitting reflection light, a control section for controlling the motor and performing scanning of slit beams in a direction orthogonal to the X direction, and a signal processing section for generating a sectional profile at each rotational angle of the motor on the basis of a light reception quantity received by the imaging section. The light reception window is composed of a plane orthogonal to an optical axis of the light receiving lens substantially at a center position of a measurement range by scanning of slit beams.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

[0002] In a conventional optical displacement meter, the light projecting system and the light receiving system are housed in a housing that is provided with a light projecting window and a light receiving window to prevent dust from adhering to the light projecting system and the light receiving system.

[0003] In conventional optical displacement meters, the relative angle between the light receiving system, which includes the light receiving lens and imaging unit, and the light receiving window is fixed, so there is no change in light receiving performance depending on the angle between the light receiving window and the optical axis of the light receiving lens.

[0004] When acquiring two-dimensional profiles of the XZ cross section at different positions in the Y direction of the measurement target (workpiece) using a conventional optical displacement meter and generating three-dimensional shape data from these two-dimensional profiles, the conventional optical displacement meter must move in the Y direction relative to the workpiece. This requires 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. However, the introduction of the above-mentioned equipment can be hindered by installation space, costs, etc.

[0005] 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 two-dimensional profiles of the XZ cross section at different positions in the Y direction of the workpiece, and can generate three-dimensional shape data from these two-dimensional profiles (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0006] [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]

[0007] In an optical displacement meter that rotates a light-projecting system and a light-receiving system, the relative angle between the light-receiving system, which includes the light-receiving lens and imaging unit, and the light-receiving window changes depending on the rotation angle of the light-projecting system and the light-receiving system, so the change in light-receiving performance depending on the relative angle between the light-receiving window and the optical axis of the light-receiving lens cannot be ignored.

[0008] However, in Patent Documents 1 and 2, no measures are taken against the change in light receiving performance according to the relative angle between the light receiving window and the optical axis of the light receiving lens.

[0009] In view of the above problems, the present invention has an object to provide an optical displacement gauge that can suppress deterioration of light receiving performance caused by changes in the relative angle between the light receiving window and the optical axis of the light receiving lens. [Means for solving the problem]

[0010] The optical displacement meter according to the present invention is, for example, 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 distance measurement, and includes a light projecting module having a light projecting unit that projects a slit light extending in the X direction onto the workpiece, a light receiving lens that collects the reflected 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 together, a housing that stores the light projecting and receiving module and has a light receiving window that transmits the reflected light, a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction, and a signal processing unit that generates a profile of the cross section at each rotation angle of the motor based on the amount of light received by the imaging unit. The light receiving window is located at the approximate center position of the measurement range by scanning the slit light and is configured by a plane perpendicular to the optical axis of the light receiving lens.

[0011] 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

[0012] According to the present invention, it is possible to provide an optical displacement meter that can suppress deterioration of light receiving performance caused by changes in the relative angle between the light receiving window and the optical axis of the light receiving lens. [Brief description of the drawings]

[0013] [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] Diagram explaining the arrangement of light receiving windows DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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).

[0024] 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.

[0025] 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.

[0026] Light projecting unit 11, light receiving lens 12, and imaging unit 13 are rotatable about rotation axis AX3 along the X direction. 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.

[0027] Limiting the rotation range of motor 21 (see FIG. 5 described later) also limits the rotation ranges of light projecting unit 11, light receiving lens 12, and imaging unit 13. The limitation of the rotation range of motor 21 may be realized, for example, by controlling motor 21, or may be realized by a stopper that physically stops the movement of light projecting and receiving module 20 (see FIG. 5 described later).

[0028] At one end of the rotation range of the motor 21, the light-receiving window 17 and the end of the light-receiving unit 18, which has the light-receiving lens 12 and the imaging unit 13, on the workpiece W side are close to each other while being separated from each other, and the inner wall of the housing 10 and the light-projecting unit 11 are separated from each other. At the other end of the rotation range of the motor 21, the light-projecting window 16 and the end of the light-projecting unit 11 on the workpiece W side are close to each other while being separated from each other, and the inner wall of the housing 10 and the light-receiving unit 18 are separated from each other. This makes it possible to reduce the size of the housing 10 while avoiding contact between the light-receiving window 17 and the light-receiving unit 18 and between the light-projecting window 16 and the light-projecting unit 11.

[0029] The light projecting unit 11, the light receiving lens 12, and the image capturing unit 13 can rotate about a rotation axis AX3 along the X direction while satisfying the Scheimpflug relationship in which the light receiving surface of the image capturing unit 13 is inclined with respect to the optical axis of the light receiving lens 12. As a result, the focus is achieved at each cross section through which the light projecting axis AX1 passes in the region R1 shown by hatching 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. Therefore, the region R1 should be set as the measurement range of the slit light L1. In other words, the measurement range of the slit light L1 should be formed by a range in which the Scheimpflug relationship is achieved for each rotation angle of the motor 21 (see FIG. 5 described later).

[0030] The positional relationship between light projecting unit 11, light receiving lens 12, and imaging unit 13 may be reversed from that shown in FIG.

[0031] 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.

[0032] 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).

[0033] 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.

[0034] <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.

[0035] 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.

[0036] 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.

[0037] <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.

[0038] 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).

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] <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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] <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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] In the following step S7, the three-dimensional data generator 28 generates three-dimensional data.

[0058] 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.

[0059] The optical displacement meter 1 has a measurement period in which the light emitting / receiving module 20 is rotated at a substantially constant speed in a first rotation direction (counterclockwise direction CCW) or a second rotation direction (clockwise direction CW) to perform a measurement operation, and a non-measurement period in which the rotation direction of the light emitting / 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 / receiving module 20 at a substantially constant speed. The light receiving window 17 and the optical axis AX2 of the light receiving lens are perpendicular to each other at a substantially central position of the measurement range in the measurement period except for the non-measurement period. In the period in which the rotation direction is switched, deceleration and acceleration must be taken into consideration, and calculations such as the correlation between the peak position in the V direction and the rotation angle become complicated. Therefore, the non-measurement period is used as the period in which the rotation direction is switched, and the measurement operation is performed by facing the light emitting / receiving module 20 at a substantially central position of the measurement range in the measurement period in which stable measurement can be performed at a substantially constant speed, thereby suppressing the influence of deterioration of the transmission characteristics due to rotation on the measurement operation.

[0060] <Light receiving window placement> Fig. 11 is a diagram for explaining the arrangement of light-receiving window 17. Fig. 11 is a diagram showing the positional relationship between light-receiving window 17 and light-receiving lens 12 when slit light L1 is irradiated onto an approximate center position of the scanning range scanned by control unit 22 with slit light L1.

[0061] The light receiving window 17 has an entrance surface 171 on which the reflected light L2 is incident and an exit surface 172 from which the reflected light L2 is emitted. At least one of the entrance surface 171 and the exit surface 172 is formed of a plane perpendicular to the optical axis AX2 of the light receiving lens 12. More preferably, as shown in FIG. 11, both the entrance surface 171 and the exit surface 172 are formed of a plane perpendicular to the optical axis AX2 of the light receiving lens 12. In other words, when the slit light L1 is irradiated at a substantially central position of the scanning range, the light receiving window 17 and the light receiving lens 12 face each other directly, and the light receiving performance is the best. The light receiving performance can be evaluated, for example, by the modulation transfer function of the light receiving optical system having an optical path from the light receiving window 17 to the imaging unit 13.

[0062] On the other hand, as the irradiation position of the slit light L1 moves away from the approximate center position of the scanning range, the inclination of the light receiving lens 12 with respect to the light receiving window 17 increases, and the light receiving performance deteriorates.

[0063] However, by arranging the light receiving window 17 so that the light receiving performance is optimal when the slit light L1 is irradiated at approximately the center of the scanning range, it is possible to prevent the light receiving performance from deteriorating both when the slit light L1 is irradiated at one end of the scanning range and when the slit light L1 is irradiated at the other end of the scanning range, and as a result, it is possible to prevent the light receiving performance from deteriorating over the entire scanning range.

[0064] By positioning the light receiving window 17 so that the light receiving performance is optimal when the slit light L1 is irradiated approximately at the center position of the scanning range, the light receiving performance at one end of the scanning range (for example, the position of height Z2 of region R1 shown in Figure 2) and the light receiving performance at the other end of the scanning range (for example, the position of height Z0 of region R1 shown in Figure 2) become approximately identical.

[0065] During the non-measurement period, the light receiving range of the light receiving lens 12 intersects with the portion of the housing 10 excluding the light receiving window 17. During the non-measurement period, there is no problem even if the light receiving range of the light receiving lens 12 intersects with the portion (frame portion) excluding the light receiving window 17, so the area of ​​the light receiving window 17 can be made smaller, which reduces costs and increases the degree of freedom in arranging the light projection window 16, etc.

[0066] The approximate center position of the scanning range is, for example, either the approximate center angle of the rotation angle range of the light projecting and receiving module 20 in the measurement operation, or the approximate center position of the measurement range of the slit light L1 in the Y direction in the measurement operation. The approximate center position of the scanning range is any position where the difference in the rotation angle of the light projecting and receiving module 20 from the center position of the scanning range is within ±10°. More preferably, the approximate center position of the scanning range is any position where the difference in the rotation angle of the light projecting and receiving module 20 from the center position of the scanning range is within ±5°.

[0067] When a first difference and a second difference, which will be described later, are equal, the scanning range may be, for example, the rotation angle range of the light emitting and receiving module 20 during the measurement operation.

[0068] The first difference is the difference between the rotation angle of the light projecting and receiving module 20 when the measurement operation by scanning with the slit light L1 starts (the rotation angle of the motor 21 in the case of a direct drive method) and the rotation angle of the light projecting and receiving module 20 when the slit light L1 is parallel to the Z direction. The second difference is the difference between the rotation angle of the light projecting and receiving module 20 when the slit light L1 is parallel to the Z direction and the rotation angle of the light projecting and receiving module 20 when the measurement operation by scanning with the slit light L1 ends. The rotation angle range of the light projecting and receiving module 20 is the difference between the rotation angle of the light projecting and receiving module 20 when the scanning with the slit light L1 starts and the rotation angle of the light projecting and receiving module 20 when the scanning with the slit light L1 ends.

[0069] In addition, the rotation angle of the projector / receiver light module 20 at the start of scanning with the slit light L1 may include a plurality of angles, and the rotation angle of the projector / receive light module 20 at the end of scanning with the slit light L1 may include a plurality of angles. For example, the rotation angle of the projector / receive light module 20 at the start of scanning with the slit light L1 may include a first angle θ1 and a second angle θ2, and the rotation angle of the projector / receive light module 20 at the end of scanning with the slit light L1 may include the first angle θ1 and the second angle θ2. If the rotation angle of the projector / receive light module 20 changed from the first angle θ1 to the second angle θ2 in the previous scan, the control unit 22 may control the motor 21 so that the rotation angle of the projector / receive light module 20 changes from the second angle θ2 to the first angle θ1 in the current scan. Conversely, if the rotation angle of the light projecting and receiving module 20 changes from the second angle θ2 to the first angle θ1 in the previous scan, the control unit 22 controls the motor 21 so that the rotation angle of the light projecting and receiving module 20 changes from the first angle θ1 to the second angle θ2 in the current scan. Note that the first angle θ1 and the second angle θ2 may be defined as the rotation angles from the position (rotation angle) of the light projecting and receiving module 20 when the slit light L1 is parallel to the Z direction.

[0070] When the first difference and the second difference are not equal, the scanning range may be, for example, the measurement range of the slit light L1 in the Y direction.

[0071] The light receiving unit 18 is separated from the light receiving window 17 regardless of the rotational position within the scanning range, and the optical axis AX2 of the light receiving lens 12 passes through the light receiving window 17. This allows the light receiving lens 12 to collect the reflected light L2 over the entire scanning range, so that the scanning range can be the scanning range in the measurement operation.

[0072] The optical displacement meter 1 may have a plurality of scanning ranges (measurement ranges) in which the slit light L1 is scanned by the control unit 22. In this case, the arrangement of the light receiving window 17 described above may be established for at least one of the plurality of scanning ranges. For example, the approximate center position of the measurement range is the approximate center position of the maximum range in which the measurement operation can be performed. The optical displacement meter 1 accepts the selection of a part of the maximum range via the communication unit 25, sets the part of the range as a new measurement range by the signal processing unit 24, and performs the measurement operation for the new measurement range. At the approximate center position of the maximum range, the light receiving window 17 and the optical axis AX2 of the light receiving lens are perpendicular to each other, so that the transmission characteristics of the light receiving window 17 do not deteriorate extremely depending on the position of the measurement range. Therefore, the degree of freedom of the measurement can be increased while suppressing the effect of deterioration of the transmission characteristics due to rotation on the measurement operation. Furthermore, the optical displacement meter 1 may accept a change in the width of the measurement range via the communication unit 25, and even after the change, may set a new measurement range so that the light receiving window 17 and the optical axis AX2 of the light receiving lens 12 are perpendicular to each other at approximately the center, and perform a measurement operation in the new measurement range. Even if the width of the measurement range is changed according to the size of the workpiece, etc., the effect of deterioration of the transmission characteristics due to rotation on the measurement operation can be further suppressed by making the light receiving window 17 and the optical axis AX2 of the light receiving lens 12 perpendicular to each other at approximately the center of each measurement range.

[0073] <Light projection window placement> The positional relationship between the light projection window 16 and the light projection unit 11 when the slit light L1 is irradiated to the approximate center position of the scanning range scanned by the control unit 22 with the slit light L1 is preferably the same as the positional relationship between the light receiving window 17 and the light receiving lens 12. That is, the light projection window 16 has a slit light entrance surface into which the slit light L1 enters and a slit light exit surface from which the slit light L1 exits, and it is preferable that at least one of the slit light entrance surface and the slit light exit surface when the slit light L1 is irradiated to the approximate center position of the scanning range scanned by the slit light L1 by the control unit 22 is configured as a plane perpendicular to the light projection axis AX1 of the light projection unit 11. With this configuration, it is possible to suppress deterioration of the light projection performance due to a change in the relative angle between the light projection window 16 and the light projection axis AX1 of the light projection unit 11.

[0074] <Summary> The various embodiments described above will be generally described below.

[0075] 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 distance measurement, and includes a light-projecting and receiving module having a light-projecting unit that irradiates a slit light extending in the X direction onto the workpiece, a light-receiving lens that collects reflected 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 as a unit; a housing that stores the light-projecting and receiving module and has a light-receiving window that transmits the reflected light; a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction; and a signal processing unit that generates a profile of the cross section at each rotation angle of the motor based on the amount of light received by the imaging unit, and the light-receiving window is configured by a plane perpendicular to the optical axis of the light-receiving lens at approximately the center of the measurement range measured by scanning the slit light (first configuration).

[0076] In the optical displacement meter having the above-mentioned first configuration, the approximate center position of the measurement range may be configured (second configuration) to be either approximately the central angle of the rotation angle range of the light projecting and receiving module during measurement operation, or approximately the central position of the measurement range in the Y direction perpendicular to the XZ plane.

[0077] In an optical displacement meter having the above-mentioned first or second configuration, the optical displacement meter may have a measurement period in which the light emitting and receiving module is rotated at approximately constant speed in a first rotation direction or a second rotation direction opposite to the first rotation direction to perform a measurement operation, and a non-measurement period in which the rotation direction of the light emitting and receiving module is switched while the measurement operation is not performed, and may have a configuration (third configuration) in which the light receiving window and the optical axis of the light receiving lens are perpendicular to each other at approximately the center position of the measurement range in the measurement period excluding the non-measurement period.

[0078] In the optical displacement meter having any one of the first to third configurations, in the non-measurement period, the light receiving range of the light receiving lens may be configured to intersect with a portion of the housing excluding the light receiving window (fourth configuration).

[0079] In an optical displacement meter having any of the first to fourth configurations described above, the approximate center position of the measurement range may be the approximate center position of a maximum range in which a measurement operation can be performed, and the optical displacement meter may be configured to accept a selection of a portion of the maximum range and perform the measurement operation using the portion as a new measurement range (fifth configuration).

[0080] In an optical displacement meter having any of the first to fifth configurations described above, a configuration (sixth configuration) may be used in which a change in the width of the measurement range is accepted, and even after the change, a new measurement range is set in which the light receiving window and the optical axis of the light receiving lens are perpendicular to each other at approximately the center position, and the measurement operation is performed in the new measurement range.

[0081] In an optical displacement meter having any of the above first to sixth configurations, the light emitting and receiving module may be spaced apart from the light receiving window regardless of the rotational position within the measurement range, and the optical axis of the light receiving lens may pass through the light receiving window (seventh configuration).

[0082] In an optical displacement meter having any of the above configurations 1 to 7, the light receiving unit having the light receiving lens and the imaging unit may be configured (configuration 8) to be separated from the light receiving window within an angular range in which the light emitting and receiving module can be rotated by the motor, regardless of the rotational position outside the measurement range.

[0083] In an optical displacement meter having any of the above first to eighth configurations, the housing may be provided with a light projection window having light transmissivity that allows the slit light from the light projection unit to pass therethrough, and at one end of a rotation range of the light projection and reception module, the light reception window and an end of the light reception unit on the work side having the light receiving lens and the imaging unit are spaced apart but are in close proximity to each other, and the inner wall of the housing and the light projection unit are spaced apart, and at the other end of the rotation range, the light projection window and the end of the light projection unit on the work side are spaced apart but are in close proximity to each other, and the inner wall of the housing and the light reception unit are spaced apart (ninth configuration).

[0084] In an optical displacement meter having any of the above configurations 1 to 9, the light projecting and receiving module may further have a reflecting member that is provided on the optical path between the light receiving window and the imaging unit and folds back the reflected light, and the control unit may control the motor to rotate the light projecting and receiving module together with the reflecting member, and the reflecting member may be spaced apart from the light receiving window regardless of the rotational position within the measurement range (tenth configuration).

[0085] In the optical displacement meter having any of the above-mentioned first to tenth configurations, the transmission characteristics of the light receiving window at one end of the measurement range and the transmission characteristics of the light receiving window at the other end of the measurement range may be substantially identical (eleventh configuration).

[0086] In an optical displacement meter having any one of the above configurations 1 to 11, a light projection window that transmits the slit light from the light projection unit is provided in the housing as a separate body from the light receiving window, and the light projection window may be configured at approximately the center of the scanning range and by a plane perpendicular to the light projection axis of the light projection unit (configuration 12).

[0087] In an optical displacement meter having any of the first to twelfth configurations, the transmission characteristics of the light projection window at one end of the measurement range and the transmission characteristics of the light projection section at the other end of the measurement range may be substantially identical (thirteenth configuration).

[0088] <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]

[0089] 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 R1 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 light-receiving module including a light-projecting unit that projects slit light extending in the X direction onto the workpiece, a light-receiving lens that collects reflected light 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 housing that houses the light emitting and receiving module and has a light receiving window that transmits the reflected light; a control unit that controls the motor to cause the slit light to scan in a direction perpendicular to the X direction; a signal processing unit that generates the cross-sectional profile at each rotation angle of the motor based on an amount of light received by the imaging unit, The light receiving window is an optical displacement meter that is configured by a plane perpendicular to the optical axis of the light receiving lens at approximately the center position of the measurement range scanned by the slit light.

2. 2. The optical displacement meter according to claim 1, wherein the approximate center position of the measurement range is either an approximate center angle of a rotation angle range of the light emitting and receiving module during a measurement operation, or an approximate center position of the measurement range in a Y direction perpendicular to an X-Z plane.

3. The optical displacement meter includes: a measurement period in which the light emitting / receiving module is rotated at a substantially constant speed 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 in which the rotation direction of the light emitting and receiving module is switched while the measurement operation is not performed; 2. The optical displacement meter according to claim 1, wherein the light receiving window and the optical axis of the light receiving lens are perpendicular to each other at the approximate center position of the measurement range during the measurement period excluding the non-measurement period.

4. The optical displacement meter according to claim 1 , wherein in the non-measurement period, a light receiving range of the light receiving lens intersects with a portion of the housing excluding the light receiving window.

5. the approximate center position of the measurement range is an approximate center position of a maximum range in which a measurement operation can be performed; The optical displacement meter according to claim 1 , wherein the optical displacement meter accepts a selection of a part of the maximum range, and executes the measurement operation with the part of the range as a new measurement range.

6. 2. The optical displacement meter according to claim 1, wherein the optical displacement meter accepts a change in the width of the measurement range, and even after the change, sets a new measurement range in which the light receiving window and the optical axis of the light receiving lens are perpendicular to each other at an approximately central position, and performs a measurement operation in the new measurement range.

7. 2. The optical displacement meter according to claim 1, wherein the light emitting / receiving module is spaced apart from the light receiving window regardless of a rotational position within the measurement range, and an optical axis of the light receiving lens passes through the light receiving window.

8. 8. The optical displacement meter according to claim 7, wherein the light receiving unit having the light receiving lens and the imaging unit is separated from the light receiving window within an angular range in which the light emitting and receiving module can be rotated by the motor, regardless of a rotation position outside the measurement range.

9. the housing is provided with a light projection window having a light transmissibility through which the slit light from the light projection unit passes, At one end of a rotation range of the light emitting and receiving module, the light receiving window and an end of the light receiving unit having the light receiving lens and the imaging unit on the work side are spaced apart but come closest to each other, and the inner wall of the housing and the light emitting unit are spaced apart, 2. The optical displacement meter according to claim 1, wherein at the other end of the rotation range, the light projection window and the end of the light projection portion on the work side are spaced apart but closest to each other, and the inner wall of the housing and the light receiving portion are spaced apart.

10. the light emitting / receiving module further includes a reflecting member that is provided on an optical path between the light receiving window and the imaging unit and that reflects the reflected light; The control unit controls the motor to rotate the light emitting / receiving module together with the reflecting member, 2. The optical displacement meter according to claim 1, wherein the reflecting member is spaced apart from the light receiving window regardless of a rotational position within the measurement range.

11. 2. The optical displacement meter according to claim 1, wherein a transmission characteristic of the light receiving window at one end of the measurement range is substantially the same as a transmission characteristic of the light receiving window at the other end of the measurement range.

12. a light-projecting window that transmits the slit light from the light-projecting unit and is provided in the housing as a separate body from the light-receiving window; 2. The optical displacement meter according to claim 1, wherein the light projection window is formed by a plane perpendicular to a light projection axis of the light projection unit at a substantially central position of the measurement range.

13. 10. The optical displacement meter according to claim 9, wherein a transmission characteristic of the light projection window at one end of the measurement range is substantially the same as a transmission characteristic of the light projection window at the other end of the measurement range.

Images