Optical displacement gauge

Abstract

To provide a new method for suppressing noise by multiple reflection when measuring the shape of a work-piece by applying slit light extending in an X direction to the work-piece that moves relatively in a direction crossing the X direction.SOLUTION: A control section of an optical displacement meter controls an image sensor so as to successively acquire a plurality of light reception images following relative movement of a work-piece, detects a peak position candidate in a V direction (a direction orthogonal to a U direction) for each position in the U direction (the direction corresponding to the X direction) on the basis of the distribution of the quantity of received light of a light reception image for each light reception image, generates one or more clusters composed of a plurality of peak position candidates selected such that the distance between a peak position candidate of an optical light reception image and a peak position candidate of another light reception image becomes a certain level or less for each position in the U direction, executes determination regarding whether noise is included in the cluster on the basis of an inclination relative to the direction of the relative movement of the cluster, and generates profile data of the work-piece on the basis of the determination result.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an optical displacement meter that detects the displacement of a measurement object by a triangulation method. [Background technology]

[0002] In a light-cutting type optical displacement meter, a strip of light with a linear cross section is projected from the light projector onto the object to be measured (hereinafter referred to as the workpiece), and the reflected light is received by a two-dimensional light receiving element. The workpiece profile is measured based on the position of the peak in the light-receiving amount distribution obtained by the light receiving element. Here, the light projected onto the workpiece may be multiple-reflected on the workpiece's surface. In this case, the multiple-reflected light enters the light receiving element, causing multiple peaks to appear in the light-receiving amount distribution, making it impossible to measure the workpiece profile accurately. Similar problems occur when light from other sources than the light projector (ambient light) enters the light receiving element, or when light reflected by parts of the workpiece other than the part being measured enters the light receiving element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-270536 Summary of the Invention [Problem to be solved by the invention]

[0004] Noise due to multiple reflections occurs and is observed in each received image. The optical displacement meter disclosed in Patent Document 1 distinguishes between true peak positions and noise due to multiple reflections in a single received image itself, based on the positional relationship between peak candidates in the U direction corresponding to the X direction (the direction in which the slit light extends).

[0005] The inventors conducted various studies on noise caused by multiple reflections and found that when a three-dimensional image is obtained by acquiring multiple received light images and multiple profiles in the scanning direction through relative movement between the optical displacement meter and the workpiece, it is possible to distinguish between the true peak position and noise caused by multiple reflections based on the positional relationship between peak candidates in the scanning direction.

[0006] The present invention aims to provide a new method for suppressing noise caused by multiple reflections when measuring the shape of a workpiece by irradiating a slit light extending in the X direction onto the workpiece that moves relatively in a direction intersecting the X direction. [Means for solving the problem]

[0007] An optical displacement meter according to one aspect of the present invention includes a light-projecting unit that irradiates a slit light extending in an X direction onto a workpiece that moves relatively in a direction intersecting the X direction; an image sensor that has a plurality of pixels two-dimensionally arranged in a U direction corresponding to the X direction and a V direction perpendicular to the U direction, that receives light reflected by the workpiece by the plurality of pixels, and outputs a received light image that shows a distribution of the amount of received light; and a control unit that generates profile data of the workpiece based on the received light image, and measures the shape of the workpiece based on the profile data. The control unit controls the image sensor to sequentially acquire a plurality of the received light images in accordance with the relative movement, detects peak position candidates in the V direction for each position in the U direction based on the distribution of the amount of received light of the received light image, generates one or more clusters consisting of a plurality of peak position candidates selected so that, for each position in the U direction, the distance between the peak position candidate of any of the received light images and the peak position candidate of another of the received light images is equal to or less than a certain value, determines whether the cluster contains noise based on the inclination of the cluster with respect to the direction of the relative movement, and generates the profile data based on the result of the determination.

[0008] An optical displacement meter according to another aspect of the present invention includes a light-projecting unit that irradiates a slit light extending in an X direction onto a workpiece that moves relatively in a direction intersecting the X direction, an image sensor that has a plurality of pixels two-dimensionally arranged in a U direction corresponding to the X direction and a V direction orthogonal to the U direction, receives light reflected by the workpiece by the plurality of pixels, and outputs a received light image that shows a distribution of the amount of received light, and a control unit that generates profile data of the workpiece based on the received light image, and measures the shape of the workpiece based on the profile data. the control unit controls the image sensor to sequentially acquire a plurality of light-receiving images in accordance with the relative movement, detects peak position candidates in the V direction for each position in the U direction based on the distribution of the amount of light received in the light-receiving image, converts UV coordinate information including each of the U direction positions and the V direction peak position candidates at each of the U direction positions, and information about the relative movement, into XYZ coordinate information including peak position candidates in the Z direction corresponding to each XY coordinate, based on predetermined coordinate conversion conditions, generates one or more clusters consisting of a plurality of peak position candidates selected for each X-axis position in the XYZ coordinate information such that a distance between a peak position candidate at an arbitrary Y-axis position and a peak position candidate at another Y-axis position is equal to or smaller than a certain value, determines whether or not the cluster contains noise based on an inclination of the cluster with respect to the Y-axis direction, and generates the profile data based on the result of the determination.

[0009] Still other features, elements, steps, advantages, and characteristics will become more apparent from the detailed description that follows and the accompanying drawings related thereto. [Effects of the Invention]

[0010] The optical displacement meter according to the present invention can provide a new method for suppressing noise caused by multiple reflections when measuring the shape of a workpiece by irradiating a slit light extending in the X direction onto the workpiece that is moving relatively in a direction intersecting the X direction. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an optical displacement measurement system according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a measurement range of a rotary optical displacement meter. [Figure 3] FIG. 10 is a diagram illustrating an optical displacement meter equipped with a reflecting member. [Figure 4] FIG. 10 is a diagram illustrating a method for detecting a peak position. [Figure 5] FIG. 2 is a functional block diagram of an optical displacement meter. [Figure 6A] FIG. 1 is a schematic diagram showing the true height of a workpiece and a height that may be mistakenly recognized. [Figure 6B] FIG. 1 is a schematic diagram showing the true height of a workpiece and a height that may be mistakenly recognized. [Figure 6C] FIG. 1 is a schematic diagram showing the true height of a workpiece and a height that may be mistakenly recognized. [Figure 7] This is profile data that summarizes the height of the workpiece at each position in the Y direction. [Figure 8] FIG. 10 is a diagram showing a processing flow of the measurement operation of the optical displacement measurement system. [Figure 9A] FIG. 10 is a diagram showing two-dimensional data of a group of peak candidates. [Figure 9B] FIG. 10 is a diagram showing two-dimensional data of clustered peak candidates. [Figure 9C] FIG. 10 is a diagram showing two-dimensional data of a group of clustered peak candidates after correction. [Figure 9D] FIG. 10 is a diagram showing two-dimensional data of a group of clustered peak candidates after correction. [Figure 9E] FIG. 10 is a diagram showing two clusters with different slopes. [Figure 9F] FIG. 10 is a diagram showing two clusters with different slopes. [Figure 9G] FIG. 10 is a diagram showing two clusters with different slopes. [Figure 10] FIG. 10 is a diagram showing another processing flow of the measurement operation of the optical displacement measurement system. [Figure 11]FIG. 10 is a diagram illustrating an optical displacement measurement system according to a second embodiment. [Figure 12] FIG. 1 is a diagram illustrating the principle of triangulation. [Figure 13] FIG. 10 is a diagram illustrating a method for detecting a peak position. [Figure 14] FIG. 2 is a functional block diagram of an optical displacement meter. [Figure 15] FIG. 1 is a schematic diagram showing the true height of a workpiece and a height that may be mistakenly recognized. [Figure 16] This is profile data that summarizes the height of the workpiece at each position in the Y direction. [Figure 17] FIG. 10 is a diagram showing a modified example of the optical displacement meter. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0013] <<First Embodiment>> <Optical displacement measurement system> Fig. 1 is a diagram showing a schematic configuration example of an optical displacement measurement system according to the first embodiment. The optical displacement measurement system 100 shown in Fig. 1 includes an optical displacement meter 1, a control device 2, a display device 3, and an input device 4.

[0014] In this embodiment, 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 projecting unit (not shown in FIG. 1). The XZ plane, which will be described later, is a plane extending in the X and Z directions. Note that the optical displacement meter 1 scans the slit light L1 by rotating the light projecting and receiving module 20, so the scanning direction of the slit light L1 is a direction perpendicular to the X direction in the YZ plane, including the Y direction. Note that 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 that indicates 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 that indicates the outer edge of the cut surface that is parallel to the XZ plane, and therefore is also referred to as 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. Note that 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 results. The optical displacement meter 1 performs imaging at regular intervals to generate profiles of the workpiece W with different yi. The optical displacement meter 1 also 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 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 disposed on the display screen of the display device 3.

[0021] 2 is a diagram illustrating the measurement range of the rotary optical displacement meter 1. A light projecting unit 11, a light receiving lens 12, and an imaging unit 13 are housed inside a housing 10 of the optical displacement meter 1. The light projecting unit 11 has a light source 14 and a projection lens 15. For example, the light source 14 may be a laser beam emitter, and the projection lens 15 may be composed of multiple lenses including a cylindrical lens.

[0022] Light output from the light source 14 passes through a light projecting lens 15 and is converted into slit light L1. The housing 10 is provided with a light projecting window 16 that has light transmissibility that allows the slit light L1 to pass through. Similarly, the housing 10 is provided with a light receiving window 17 that has light transmissibility that allows the reflected light L2 to pass through. The light projecting window 16 and the light receiving window 17 are separate bodies (separate components). Because the light projecting window 16 and the light receiving window 17 are separate bodies, the light projecting window 16 and the light receiving window 17 are each flat-shaped components, 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 that collects the reflected light L2 and forms an image on the light-receiving surface of the imaging unit 13. The light-receiving lens 12 may include only one lens, or may include multiple lenses. The light-receiving lens 12 may also include optical components other than lenses (for example, optical filters). The imaging unit 13 is an image sensor that has multiple photoelectric conversion elements that are two-dimensionally arranged. 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 light projection axis AX1 of the light-projecting unit 11. The light 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 height Z1 forms an image at position V1 in the V direction on the light-receiving surface of the imaging unit 13, and the reflected light L2 from height Z2 forms an image at position V2 in the V direction on the light-receiving surface of the imaging unit 13. In other words, 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. In other words, the vertical direction of the light-receiving image showing the distribution of the amount of received light 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 around 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. For example, light projecting unit 11, light receiving lens 12, and imaging unit 13 are arranged and fixed on a support member (not shown) with their relative positions fixed. In FIG. 2, the state of light projecting unit 11, light receiving lens 12, and imaging unit 13 before rotation in the counterclockwise direction CCW is shown by solid lines, and the state after rotation in the counterclockwise direction CCW is shown by dashed lines.

[0026] Limiting the rotation range of motor 21 (see FIG. 5 described later) also limits the rotation range of light projecting unit 11, light receiving lens 12, and imaging unit 13. The rotation range of motor 21 may be limited, for example, by controlling motor 21, or by a stopper that physically stops the movement of light projecting and receiving module 20 (see FIG. 5 described later).

[0027] 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.

[0028] 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 relative to the optical axis of the light receiving lens 12. This allows the image to be in focus at each cross section through which the light projecting axis AX1 passes in the shaded region 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. 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 within a range in which the Scheimpflug relationship holds for each rotation angle of the motor 21 (see FIG. 5, described later).

[0029] The positional relationship between light projecting unit 11, light receiving lens 12, and imaging unit 13 may be reversed from that shown in FIG.

[0030] 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 bends 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, which integrally holds the light-projecting unit 11, the light-receiving lens 12, the imaging unit 13, and the reflecting member 19, to be compact in the YZ plane extending in the Y and Z directions. This allows the moment of inertia around the rotation axis AX3 of the light-projecting and receiving module, which integrally holds the light-projecting unit 11, the light-receiving lens 12, the imaging unit 13, and the reflecting member 19, to be reduced.

[0031] In FIG. 3, the reflecting member 19 is provided on the optical path between the light receiving lens 12 and the imaging unit 13, but it may also be provided on the optical path between the light receiving window 17 and the light receiving lens 12.

[0032] 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 it has been collected by the light-receiving lens 12, thereby making it possible to reduce the area of ​​the reflective 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 positioned closer to the rotation axis AX3, thereby significantly reducing the moment of inertia.

[0033] <Position (height calculation)> 4 is a diagram illustrating 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 that reflected light L2 brings to the light receiving surface of image capture unit 13 also becomes wide enough to span multiple photoelectric conversion elements.

[0034] Therefore, the optical displacement meter 1 obtains an approximate curve P1 indicating the change in brightness value from the brightness value of each pixel, and calculates the position in the V direction where the approximate curve P1 produces a peak value. In Figure 4, the leftmost column is the column of interest, and an example of the distribution of brightness values ​​(approximate curve P1) for the column of interest is shown. The approximate curve P1 is obtained by curve fitting multiple sample values, for example. Sample values ​​below the detection threshold are not taken into account. The position in the V direction where this peak value produces indicates the height of the workpiece W. The optical displacement meter 1 obtains an approximate curve P1 at each position (each pixel column) in the U direction, and calculates the position (height) in the V direction where the peak value produces from the approximate curve P1. By performing this calculation process at each position in the U direction, a single profile can be obtained. This type of calculation process may be referred to as subpixel processing.

[0035] Note that, for example, a coordinate conversion condition (e.g., a coordinate conversion table) indicating the correspondence between UV coordinates and the rotation angle θ, such as (U, V, θ) = (X, Y, Z), and the local coordinates (X, Y, Z), is generated by pre-shipment calibration 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. Note that, in the coordinate conversion, equal-interval correction may be performed in the X and Y directions so that positions in the X and Y directions are plotted at equal intervals, and Z corresponding to the corrected (X, Y) may be calculated by linear interpolation or the like and output as the measurement result. Image processing performed on the measurement results often assumes data sampled at equal intervals in the X and Y directions, so equal-interval correction facilitates subsequent image processing.

[0036] <Function block> 5 is a functional block diagram of the optical displacement meter 1. The optical displacement meter 1 includes a light emitting / receiving module 20, a motor 21, and a control unit 22.

[0037] The light-emitting and light-receiving module 20 integrally holds the light-emitting unit 11, the light-receiving lens 12, and the imaging unit 13. Furthermore, if the optical displacement meter 1 includes a reflecting member 19, the light-emitting and light-receiving module 20 integrally holds the light-emitting unit 11, the light-receiving lens 12, the imaging unit 13, and the reflecting member 19 (not shown in FIG. 5).

[0038] 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.

[0039] Control unit 22 includes motor control unit 23, signal processing unit 24, and communication unit 25. Control unit 22 controls motor 21 to rotate light projector 11, light-receiving lens 12, and image capture unit 13 in a state where the Scheimpflug relationship is satisfied, thereby scanning slit light L1 in a direction intersecting the X direction. More specifically, motor control unit 23 controls motor 21 to rotate light projector 11, light-receiving lens 12, and image capture unit 13 in a state where the Scheimpflug relationship is satisfied, and signal processing unit 24 controls light projector 11 to irradiate slit light L1 from light projector 11.

[0040] The signal processing unit 24 includes a peak detection unit 241 , a profile generation unit 242 , a three-dimensional data generation unit 243 , an inspection unit 244 , and a setting unit 245 .

[0041] The peak detection unit 241 detects the position in the V direction (peak position) that brings about the peak of the brightness value based on the light reception result output from the imaging unit 13. The profile generation unit 242 generates one profile data by summarizing the height (zi) of the workpiece W at each position (xi) in the X direction determined by the peak detection unit 241. The three-dimensional data generation unit 243 generates three-dimensional shape data of the workpiece W from the profiles of the workpiece W with different yi generated by the profile generation unit 242.

[0042] The inspection unit 244 inspects the workpiece W based on the three-dimensional shape data of the workpiece W generated by the three-dimensional data generation unit 243. The inspection unit 244 performs predetermined measurements on the three-dimensional shape data of the workpiece W, and inspects the workpiece W based on the measurement results. For example, the inspection unit 244 measures the length, angle, etc. of a predetermined portion of the workpiece W. Then, the inspection unit 244 determines whether the workpiece W is a non-defective product based on these measurement results and preset thresholds, etc.

[0043] 1 is operated by a user, the setting unit 245 detects the operation and accepts various settings related to the control unit 22. For example, the setting unit 245 sets inspection parameters to be used in the inspection unit 244. Also, for example, the setting unit 245 sets imaging parameters that are imaging conditions in the imaging unit 13.

[0044] At least some of the peak detection unit 241, profile generation unit 242, three-dimensional data generation unit 243, inspection unit 244, and setting unit 245 may be provided in a location (for example, inside the control device 2 shown in FIG. 1) separate from the main body of the optical displacement meter 1. In this case, the optical displacement meter 1 has a separate structure consisting of the main body of the optical displacement meter 1 and a separate part of the optical displacement meter 1.

[0045] The communication unit 25 communicates with the control device 2 via wired or wireless communication. 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, and inspection results of the workpiece W determined by the inspection unit 244, to the control device 2.

[0046] <Measures against stray light> 6A to 6C are schematic diagrams showing the true height of the workpiece W and the height that may be mistakenly recognized. FIG. 6A shows the state in which a horizontal plane extending in the Y direction of the workpiece W is being measured. The measurement light reflected from the horizontal plane not only directly enters the imaging unit 13 but also further reflects from a vertical plane extending in the Z direction of the workpiece W before entering the imaging unit 13. In FIG. 6A, the light-projecting unit 11, the light-receiving lens 12, and the imaging unit 13 at the first measurement timing of the horizontal plane extending in the Y direction of the workpiece W are shown by solid lines, and the light-projecting unit 11, the light-receiving lens 12, and the imaging unit 13 at the second measurement timing are shown by dashed lines. FIGS. 6B and 6C show the state in which a vertical plane extending in the Z direction of the workpiece W is being measured. The measurement light reflected from the vertical plane not only directly enters the imaging unit 13 but also further reflects from a horizontal plane extending in the Y direction of the workpiece W before entering the imaging unit 13. 6B illustrates a first measurement timing of a vertical surface of the workpiece W extending in the Z direction, and FIG. 6C illustrates a second measurement timing of the vertical surface of the workpiece W extending in the Z direction.

[0047] The true height H1 of the workpiece W hardly changes between the first and second measurement timings, whereas the height H2 of the workpiece W that may be mistakenly recognized due to light (stray light) that is multiple-reflected on the surface of the workpiece W entering the imaging unit 13 changes significantly between the first and second measurement timings.

[0048] Therefore, when the peak detection unit 241 is set not to implement stray light countermeasures and the workpiece W having the shape shown in Fig. 6 is measured, the profile data summarizing the height (zi) of the workpiece W at each position (yi) in the Y direction at a certain position in the X direction will be as shown in Fig. 7. As can be seen from Fig. 7, the inclination of the height H2 of the workpiece W relative to the Y direction, which may be mistakenly recognized as a result of light (stray light) multiplexed reflected on the surface of the workpiece W entering the imaging unit 13, is greater than the inclination of the true height H1 of the workpiece W relative to the Y direction. In this embodiment, this knowledge is utilized to implement stray light countermeasures.

[0049] <Processing flow> Fig. 8 is a diagram showing a processing 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 processing flow of Fig. 8 starts.

[0050] First, in step S1, the light projecting unit 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 projecting and receiving module 20 to a predetermined scanning start position. The processing of steps S1 and S2 starts scanning with the slit light L1. When the processing of steps S1 and S2 is completed, the flow proceeds to step S3.

[0051] The imaging unit 13 captures images at an imaging period, for example, at equal time intervals or equal rotation intervals of the motor 21 (step S3), and generates a received light image in which the vertical direction is the V direction and the horizontal direction is the U direction (step S4). When capturing images at equal rotation intervals, position information of the rotation of the motor 21 can be detected by, for example, an encoder.

[0052] In the following step S5, the peak detection unit 241 detects up to N (N is a predetermined integer equal to or greater than 2) V-direction candidate peak positions that are equal to or greater than a predetermined amount of received light at each position in the U-direction of the received-light image. If there are more than N V-direction candidate peak positions, the N positions are detected in descending order of the amount of received light. Note that it is possible that the number of detected V-direction candidate peak positions is zero.

[0053] The above-described processing of steps S3 to S5 is executed for each photographing cycle in which one received-light image is photographed.

[0054] When the irradiation position of the slit light beam L1 reaches the scanning end position, the flow proceeds to step S6.

[0055] In step S6, motor control unit 23 stops the rotation of motor 21. In the following step S7, light projector 11 stops emitting slit light L1. Note that the processes of steps S6 and S7 may be executed simultaneously. The processes of steps S6 and S7 complete the scanning of slit light L1. When the scanning of slit light L1 is completed, the flow proceeds to step S8.

[0056] The processing of steps S8 to S10 is executed for each position in the U direction.

[0057] In step S8, the peak detection unit 241 plots peak candidate positions at a position (Ui) in the U direction, with the horizontal axis representing the θ direction and the vertical axis representing the V direction, to generate two-dimensional data of a group of peak candidates, for example, as shown in Fig. 9A. In the example shown in Fig. 9A, the maximum number of detected peak candidate positions is set to four.

[0058] In the following step S9, the peak detection unit 241 executes noise suppression processing. Details of the noise suppression processing will be described below.

[0059] First, the peak detection unit 241 forms a cluster from a plurality of peak position candidates selected in the two-dimensional data of the peak candidate group so that the distance between the peak position candidate of an arbitrary light receiving image and the peak position candidate of another light receiving image (a light receiving image having a different value in the θ direction from the arbitrary light receiving image) is equal to or less than a certain distance. When the peak position candidate of an arbitrary light receiving image is away from all the peak position candidates of all the other light receiving images in the two-dimensional data of the peak candidate group by more than a certain distance, the peak detection unit 241 forms a cluster from only one peak position candidate of the arbitrary light receiving image.

[0060] Next, the peak detection unit 241 calculates the gradient of each cluster in the θ direction using the least squares method or the like. Although the θ direction is not strictly a straight line because it is a rotation, the gradient of each cluster can be calculated by locally regarding it as a straight line. When there are a first cluster candidate (e.g., cluster candidate A1 shown in FIG. 9A) and a second cluster candidate (e.g., cluster candidate A2 shown in FIG. 9A) with different gradients within an arbitrary range in the θ direction, the peak detection unit 241 regards the first cluster candidate and the second cluster candidate as different clusters rather than a single cluster, even if the shortest distance between the first cluster candidate and the second cluster candidate is equal to or less than a certain value. In this case, one of the cluster candidates is likely to contain noise, and therefore, by regarding them as different clusters even if they are adjacent, measurement accuracy is improved. Furthermore, even if a third cluster candidate (e.g., cluster candidate A3 shown in FIG. 9A) is located at a distance equal to or less than a certain distance from a position where the shortest distance between a first cluster candidate (e.g., cluster candidate A1 shown in FIG. 9A) and a second cluster candidate (e.g., cluster candidate A2 shown in FIG. 9A) is equal to or less than a certain distance, the peak detection unit 241 regards the third cluster candidate as a cluster different from both the first cluster candidate and the second cluster candidate.

[0061] When the peak detection unit 241 divides the multiple peak candidate positions in the example shown in FIG. 9A into clusters in the above procedure, the multiple peak candidate positions in the example shown in FIG. 9A are divided into clusters CL1 to CL15 as shown in FIG. 9B.

[0062] Here, even if the distance between a peak position candidate of any of the received light images and a peak position candidate of another of the received light images is equal to or less than a certain value, if a change in slope (slope in the θ direction in the case of the flow processing shown in FIG. 8, or slope in the Y-axis direction in the case of the flow processing shown in FIG. 10 described later) of a certain value or more occurs within the cluster candidate, the peak detection unit 241 may consider the change in slope to be a boundary between different clusters.

[0063] For example, because the right end of the candidate peak position included in CL1 and the left end of the candidate peak position included in CL3 are within a certain distance, CL1 and CL3 can be considered as a single cluster. However, because a change in slope occurs between CL1 and CL3 beyond a certain level, the point where the change in slope occurs is considered as a boundary and separate clusters. Noise is likely to occur in areas with steps in the scanning direction, i.e., the Y direction, such as the edge of the workpiece W. Therefore, if large changes in slope are grouped into the same cluster, a single cluster will contain candidate peak positions due to the true height of the workpiece W and candidate peak positions due to noise, leading to a decrease in measurement accuracy. By separating the points where the change in slope occurs as described above into separate clusters, it is possible to prevent candidate peak positions due to the true height of the workpiece W and candidate peak positions due to noise from being mixed together in a single cluster.

[0064] Next, the peak detection unit 241 calculates the number of peak candidate positions that make up each cluster (hereinafter referred to as the number of members), and deletes clusters whose number of members is equal to or less than a threshold. Clusters caused by unstable noise tend to have a small number of members, so noise can be suppressed by deleting clusters with a small number of members. For example, if the threshold is set to 2, clusters CL6 to CL13 are deleted, and the two-dimensional data of the group of clustered peak candidates shown in FIG. 9B is corrected to the two-dimensional data of the group of clustered peak candidates shown in FIG. 9C.

[0065] Next, the peak detection unit 241 determines that all clusters whose absolute value of the gradient in the θ direction is equal to or greater than a predetermined value are noise and removes them. As a result, clusters CL2, CL5, and CL14 are removed from the two-dimensional data of the clustered peak candidates shown in Figure 9C, and the two-dimensional data of the clustered peak candidates is corrected to the two-dimensional data of the clustered peak candidates shown in Figure 9D.

[0066] Furthermore, when multiple clusters exist within a given range in the θ direction, the peak detection unit 241 generates profile data by preferentially using clusters with small absolute values ​​of inclination relative to the θ direction among the multiple clusters. Specifically, when multiple clusters exist within a given range in the θ direction, the peak detection unit 241 determines that clusters with large absolute values ​​of inclination relative to the θ direction among the multiple clusters are noise and removes them, and generates profile data based on clusters with small absolute values ​​of inclination. Because clusters with large absolute values ​​of inclination relative to the θ direction are more likely to be clusters caused by stray light, determining that clusters with large absolute values ​​of inclination relative to the θ direction are noise and removing them increases the possibility of suppressing noise.

[0067] Furthermore, when multiple clusters partially overlap within any range in the θ direction, the peak detection unit 241 generates profile data at the overlapping positions based on the cluster among the multiple clusters that has a small absolute value of the slope with respect to the θ direction, while generating profile data at positions other than the overlapping positions based on each of the multiple clusters. Since a single cluster may contain a mixture of peak candidate positions due to the true height of the workpiece W and peak candidate positions due to noise, the risk of excessive deletion of peak candidate positions can be reduced by limiting removal to only positions where multiple clusters overlap in the θ direction.

[0068] For example, in the case where there exists a cluster CLN-1 and a cluster CLN whose absolute value of the tilt in the θ direction is greater than that of the cluster CLN-1 and is less than a predetermined value, if the clusters CLN-1 and CLN do not overlap in the θ direction, as shown in Fig. 9E, neither the cluster CLN-1 nor the cluster CLN is removed. On the other hand, if the clusters CLN-1 and CLN overlap in the θ direction, as shown in Fig. 9F or 9G, the cluster CLN is removed only at the position where they overlap in the θ direction.

[0069] Two clusters with similar slopes (two clusters whose slope difference is less than the allowable value) are considered to be two clusters with the same slope, and the peak detection unit 241 does not determine that the cluster with a large absolute value of the slope in the θ direction is noise and does not perform the process of removing it for the two clusters considered to have the same slope.

[0070] Finally, if multiple peak candidate positions remain at each position in the θ direction, the peak detection unit 241 narrows down the peak candidate positions to one at each position in the θ direction using the information on the light amount.

[0071] In step S10, the peak detection unit 241 determines the peak candidate positions at each position in the θ direction remaining after the noise suppression processing in step S9 as peak positions at each position in the θ direction. When the processing in step S10 ends, the flow proceeds to step S11.

[0072] The profile generating unit 27 converts the profile in the UV coordinate system into the XYZ coordinate system (step S11), and generates a two-dimensional profile of the XZ cross section of the workpiece W (step S12).

[0073] In the following step S13, the three-dimensional data generator 28 generates three-dimensional data.

[0074] In the following step S14, the display device 3 displays the measurement results. The measurement results may be, 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 processing of step S14 ends, the processing flow of FIG. 8 ends.

[0075] In the processing flow of FIG. 8, the noise suppression processing is performed in step S8, and then the coordinate transformation is performed in step S11. However, as in the processing flow of FIG. 10, the coordinate transformation may be performed first, and then the noise suppression processing may be performed.

[0076] Step S8' in Figure 10 corresponds to step S11 in Figure 8, step S9' in Figure 10 corresponds to step S8 in Figure 8, step S10' in Figure 10 corresponds to step S9 in Figure 8, and step S11' in Figure 10 corresponds to step S10 in Figure 8.

[0077] The U direction in steps S8 to S10 in FIG. 8 becomes the X direction in steps S9' to S11' in FIG. 10, and the V direction in steps S8 to S10 in FIG. 8 becomes the Z direction in steps S9' to S11' in FIG. 10.

[0078] <<Second embodiment>> <Optical displacement measurement system> Fig. 11 is a diagram showing a schematic configuration example of an optical displacement measurement system according to the second embodiment. The optical displacement measurement system 100 shown in Fig. 11 includes an optical displacement meter 1, a control device 2, a display device 3, an input device 4, and a belt conveyor 5.

[0079] In this embodiment, 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 is a direction perpendicular to the X and Z directions. An XZ plane, which will be described later, is a plane extending in the X and Z directions.

[0080] The optical displacement measurement system 100 is a system that measures the profile and three-dimensional shape of a workpiece W that is transported in the Y direction by a belt conveyor 5. The profile of the workpiece W is data that indicates the outer edge of the cut surface of the workpiece W by a slit light L1. When the slit light is irradiated parallel to the XZ plane, the profile of the workpiece W becomes data that indicates the outer edge of the cut surface that is parallel to the XZ plane, and is therefore also referred to as a two-dimensional profile of the XZ cross section of the workpiece W.

[0081] 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. Note that a three-dimensional shape is a collection of (xi, yi, zi). yi indicates the position in the Y direction.

[0082] 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 results. The optical displacement meter 1 performs imaging at regular intervals to generate profiles of the workpiece W with different yi. The optical displacement meter 1 also generates three-dimensional shape data of the workpiece W from the profiles of the workpiece W with different yi.

[0083] 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.

[0084] 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.

[0085] The input device 4 accepts 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 disposed on the display screen of the display device 3.

[0086] FIG. 12 is a diagram illustrating the principle of the light-section method (triangulation). A light-projecting unit 11, a light-receiving lens 12, and an imaging unit 13 are built into 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 multiple lenses including a cylindrical lens. 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 through which the slit light L1 passes. Similarly, the housing 10 is provided with a light-receiving window 17 through which reflected light L2 is guided into the housing 10.

[0087] The light-receiving lens 12 is a lens for focusing the reflected light L2 on the imaging unit 13. The imaging unit 13 is a sensor having a plurality of pixels (which may also be called light-receiving elements or photoelectric conversion elements) arranged two-dimensionally. As shown in FIG. 12, the light-receiving axis AX2 of the imaging unit 13 is tilted at an angle θ1 with respect to the light projection axis AX1 of the light source 6. In other words, the reflected light L2 from height Z0 is focused at a position V0 in the V direction of the imaging unit 13. The reflected light L2 from height Z1 is focused at a position V1 in the V direction of the imaging unit 13. The reflected light L2 from height Z2 is focused at a position V2 in the V direction of the imaging unit 13. In this way, the V direction of the imaging unit 13 corresponds to the Z direction of the workpiece W. Although the U direction of the imaging unit 13 is not shown, the U direction corresponds to the X direction of the workpiece W. In other words, the vertical direction of the image, which is the light reception result output by the imaging unit 13, is the V direction, and the horizontal direction is the U direction.

[0088] In Figure 12, the light source 14 is positioned so that the slit light L1 is output in the Z-axis direction, but the positional relationship between the pair of light source 14 and projector lens 15 and the pair of imaging unit 13 and receiver lens 12 may be reversed.

[0089] <Position (height calculation)> 13 is a diagram illustrating 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 that reflected light L2 brings to the light receiving surface of image capture unit 13 also becomes wide enough to span multiple photoelectric conversion elements.

[0090] Therefore, the optical displacement meter 1 obtains an approximate curve P1 indicating the change in brightness value from the brightness value of each pixel, and calculates the position in the V direction where the approximate curve P1 produces a peak value. In Figure 13, the leftmost column is the target column, and an example of the distribution of brightness values ​​(approximate curve P1) for the target column is shown. The approximate curve P1 is obtained by curve fitting multiple sample values, for example. Sample values ​​below the detection threshold are not taken into account. The position in the V direction where this peak value produces indicates the height of the workpiece W. The optical displacement meter 1 obtains an approximate curve P1 at each position (each pixel column) in the U direction, and calculates the position (height) in the V direction where the peak value produces from the approximate curve P1. By performing this calculation process at each position in the U direction, a single profile can be obtained. This type of calculation process may be referred to as subpixel processing.

[0091] Note that, for example, a coordinate conversion condition (e.g., a coordinate conversion table) indicating the correspondence between the UV coordinates and the relative position y in the Y direction between the optical displacement meter 1 and the workpiece W, as expressed by (U, V, y) = (X, Y, Z), and the local coordinates (X, Y, Z), is generated by pre-shipment calibration 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 relative position y in the Y direction between the optical displacement meter 1 and the workpiece W through simple calculations. Note that, in the coordinate conversion, equal-interval correction is performed in the X and Y directions so that positions in the X and Y directions are plotted at equal intervals, and Z corresponding to the corrected (X, Y) may be obtained by linear interpolation or the like and output as the measurement result. Image processing performed on the measurement results often assumes data sampled at equal intervals in the X and Y directions, so equal-interval correction facilitates subsequent image processing.

[0092] <Function block> 14 is a functional block diagram of the optical displacement meter 1. The optical displacement meter 1 includes a light emitting / receiving module 20 and a control unit 22.

[0093] The light emitting / receiving module 20 integrally holds the light emitting unit 11, the light receiving lens 12, and the imaging unit 13.

[0094] The control unit 22 includes a signal processing unit 24 and a communication unit 25. The signal processing unit 24 controls the light projecting unit 11 to cause the light projecting unit 11 to irradiate the slit light L1.

[0095] The signal processing unit 24 includes a peak detection unit 241 , a profile generation unit 242 , a three-dimensional data generation unit 243 , an inspection unit 244 , and a setting unit 245 .

[0096] The peak detection unit 241 detects the position in the V direction (peak position) that brings about the peak of the brightness value based on the light reception result output from the imaging unit 13. The profile generation unit 242 generates one profile data by summarizing the height (zi) of the workpiece W at each position (xi) in the X direction determined by the peak detection unit 241. The three-dimensional data generation unit 243 generates three-dimensional shape data of the workpiece W from the profiles of the workpiece W with different yi generated by the profile generation unit 242.

[0097] The inspection unit 244 inspects the workpiece W based on the three-dimensional shape data of the workpiece W generated by the three-dimensional data generation unit 243. The inspection unit 244 performs predetermined measurements on the three-dimensional shape data of the workpiece W, and inspects the workpiece W based on the measurement results. For example, the inspection unit 244 measures the length, angle, etc. of a predetermined portion of the workpiece W. Then, the inspection unit 244 determines whether the workpiece W is a non-defective product based on these measurement results and preset thresholds, etc.

[0098] 11 is operated by a user, the setting unit 245 detects the operation and accepts various settings related to the control unit 22. For example, the setting unit 245 sets inspection parameters to be used in the inspection unit 244. Also, for example, the setting unit 245 sets imaging parameters that are imaging conditions in the imaging unit 13.

[0099] At least some of the peak detection unit 241, profile generation unit 242, three-dimensional data generation unit 243, inspection unit 244, and setting unit 245 may be provided in a location (for example, inside the control device 2 shown in FIG. 11) separate from the main body of the optical displacement meter 1. In this case, the optical displacement meter 1 has a separate structure consisting of the main body of the optical displacement meter 1 and a separate part of the optical displacement meter 1.

[0100] The communication unit 25 communicates with the control device 2 via wired or wireless communication. 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, and inspection results of the workpiece W determined by the inspection unit 244, to the control device 2.

[0101] <Measures against stray light> Fig. 15 is a schematic diagram showing the true height and the height that may be mistakenly recognized as the height of the workpiece W. In Fig. 15, the light projecting unit 11, the light receiving lens 12, and the image capturing unit 13 at the first measurement timing are shown by solid lines, and the light projecting unit 11, the light receiving lens 12, and the image capturing unit 13 at the second measurement timing are shown by dashed lines.

[0102] The true height H1 of the workpiece W hardly changes between the first and second measurement timings, whereas the height H2 of the workpiece W that may be mistakenly recognized due to light (stray light) that is multiple-reflected on the surface of the workpiece W entering the imaging unit 13 changes significantly between the first and second measurement timings.

[0103] Therefore, when the peak detection unit 241 is set not to implement stray light countermeasures and the workpiece W having the shape shown in FIG. 15 is measured, the profile data summarizing the heights (zi) of the workpiece W at each position (yi) in the Y direction at a certain position in the X direction will be as shown in FIG. 16. As can be seen from FIG. 16, the inclination of the height H2 of the workpiece W relative to the Y direction, which may be mistakenly recognized as a result of light (stray light) multiplexed reflected on the surface of the workpiece W entering the imaging unit 13, is greater than the inclination of the true height H1 of the workpiece W relative to the Y direction. In this embodiment, the peak detection unit 241 implements stray light countermeasures by utilizing the knowledge discovered by the present inventor.

[0104] <Processing flow> In this embodiment, the motor 21 in the first embodiment is replaced with a drive motor for the belt conveyor 5, and while the scanning direction was the rotation direction of the light emitting and receiving module 20 in the first embodiment, in this embodiment it is the transport direction (Y direction) of the workpiece W by the belt conveyor 5. Therefore, by changing the motor and the contents of the coordinate conversion, the processing flow shown in Fig. 8 and the processing flow shown in Fig. 10 can also be applied to this embodiment.

[0105] <Modification of relative movement> 11, the workpiece W is moved in the Y direction by a belt conveyor 5 relative to the light emitting and receiving module 20 of the optical displacement meter 1, thereby measuring the profile and three-dimensional shape of the workpiece W. In this embodiment, the workpiece W moves, but the relative movement between the workpiece W and the light emitting and receiving module 20 of the optical displacement meter 1 is not limited to this. Therefore, the workpiece W may remain stationary and the light emitting and receiving module 20 of the optical displacement meter 1 may move, or both the workpiece W and the light emitting and receiving module 20 of the optical displacement meter 1 may move.

[0106] 17, when the light emitting and receiving module 20 of the optical displacement meter 1 is moved, the optical displacement meter 1 includes a linear motion mechanism 26, and the control unit 22 includes a linear motion mechanism control unit 27. The linear motion mechanism control unit 27 controls the linear motion mechanism 26 to move the light emitting and receiving module in the Y direction within the housing 10.

[0107] <<Others>> In addition to the above-described embodiments, the 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-described embodiments should be considered to be illustrative and not restrictive in all respects. Furthermore, 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 of the claims. [Explanation of symbols]

[0108] 1 Optical displacement gauge 2. Control device 3 Display device 4 Input Devices 5 Belt conveyor 10. Housing 11 Light projector 12 Receiving lens 13 Imaging unit (image sensor) 14 Light source 15 Projection lens 16 Floodlight 17 Light receiving window 18 Light receiving part 19 Reflective material 20 Light emitting and receiving module 21 Motor 22 Control Unit 23 Motor control unit 24 Signal Processing Section 25 Communications Department 26 Linear motion mechanism 27 Linear motion mechanism control unit 100 Optical displacement measurement system 241 Peak detector 242 Profile Generation Unit 243 3D Data Generation Unit 244 Inspection Department 245 Settings AX1 light emitting axis AX2 optical axis AX3 Rotation Axis I1 Image L1 slit light L2 reflected light R1 area double work

Claims

1. a light projecting unit that projects slit light extending in an X direction onto a workpiece that moves relatively in a direction intersecting the X direction; an image sensor having a plurality of pixels two-dimensionally arranged in a U direction corresponding to the X direction and a V direction perpendicular to the U direction, receiving light reflected by the workpiece with the plurality of pixels and outputting a light receiving image showing a distribution of the amount of received light; a control unit that generates profile data of the workpiece based on the received light image and measures the shape of the workpiece based on the profile data; Equipped with The control unit controlling the image sensor to sequentially acquire a plurality of the received light images in accordance with the relative movement; detecting a peak position candidate in the V direction for each position in the U direction based on a distribution of the amount of received light of each of the received light images; For each position in the U direction, generating one or more clusters each including a plurality of peak position candidates selected so that the distance between any one of the peak position candidates of the received light image and the peak position candidates of the other of the received light images is equal to or less than a certain value; determining whether the cluster contains noise based on the inclination of the cluster with respect to the direction of the relative movement; generating the profile data based on the result of the determination; Optical displacement gauge.

2. a light projecting unit that projects slit light extending in an X direction onto a workpiece that moves relatively in a direction intersecting the X direction; an image sensor having a plurality of pixels two-dimensionally arranged in a U direction corresponding to the X direction and a V direction perpendicular to the U direction, receiving light reflected by the workpiece with the plurality of pixels and outputting a light receiving image showing a distribution of the amount of received light; a control unit that generates profile data of the workpiece based on the received light image and measures the shape of the workpiece based on the profile data; Equipped with The control unit controlling the image sensor to sequentially acquire a plurality of received light images in accordance with the relative movement; detecting a peak position candidate in the V direction for each position in the U direction based on a distribution of the amount of received light of each of the received light images; converting UV coordinate information including each of the U-direction positions and peak position candidates in the V-direction at each of the U-direction positions, and information regarding the relative movement, into XYZ coordinate information including peak position candidates in the Z-direction corresponding to each of the XY coordinates based on predetermined coordinate conversion conditions; For each position in the X-axis direction of the XYZ coordinate information, generating one or more clusters each including a plurality of peak position candidates selected such that the distance between a peak position candidate at any Y-axis position and a peak position candidate at another Y-axis position is equal to or less than a certain value; determining whether the cluster contains noise based on the inclination of the cluster with respect to the Y-axis direction; generating the profile data based on the result of the determination; Optical displacement gauge.

3. The control unit 3. The optical displacement meter according to claim 1, wherein, when there are first cluster candidates and second cluster candidates having different inclinations in any range of the relative movement direction, even if the shortest distance between the first cluster candidate and the second cluster candidate is equal to or less than the certain value, the first cluster candidate and the second cluster candidate are regarded as different clusters rather than as a single cluster.

4. The control unit 4. The optical displacement meter according to claim 3, wherein even if a third cluster candidate exists at a distance equal to or less than the certain distance from a position where the shortest distance between the first cluster candidate and the second cluster candidate is equal to or less than the certain distance, the third cluster candidate is regarded as a cluster different from both the first cluster candidate and the second cluster candidate.

5. The control unit 3. The optical displacement meter according to claim 1, wherein even if the distance between any one of the peak position candidates of the received light image and another of the peak position candidates of the received light image is equal to or less than the certain level, if a change in slope of a certain level or more occurs within a cluster candidate, the clusters are considered to be different from each other at the boundary where the change in slope occurs.

6. The control unit 3. The optical displacement meter according to claim 1, wherein an entire cluster in which the absolute value of the gradient is equal to or greater than a predetermined value is determined to be noise and is removed.

7. The control unit 3. The optical displacement meter according to claim 1, wherein when a plurality of clusters exist in any range of the relative movement direction, the profile data is generated by preferentially using a cluster having a small absolute value of the slope among the plurality of clusters.

8. The control unit 3. The optical displacement meter according to claim 1, wherein, when a plurality of clusters exist within an arbitrary range of the relative movement direction, a cluster having a large absolute value of the slope among the plurality of clusters is determined to be noise and removed, and the profile data is generated based on a cluster having a small absolute value of the slope.

9. The control unit 3. The optical displacement meter according to claim 1, wherein, when a plurality of the clusters partially overlap in any range in the direction of the relative movement, the profile data is generated at the overlapping position based on a cluster of the plurality of clusters having a small absolute value of the slope, while the profile data is generated at positions other than the overlapping position based on each of the plurality of clusters.

Images