Optical displacement meter

Abstract

This invention provides an optical displacement meter. It can suppress the 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. It is an optical displacement meter based on the triangulation principle for measuring the cross-sectional profile of a workpiece, comprising: a light-projecting and light-receiving module having a light-projecting part that illuminates slit light extending along the X-direction, a light-receiving lens that converges reflected light from the workpiece, and an imaging part that receives the light converged by the light-receiving lens; a motor that integrally rotates the light-projecting and light-receiving module; a housing that houses the light-projecting and light-receiving module and has a light-receiving window through which reflected light passes; a control unit that controls the motor to scan the slit light in a direction orthogonal to the X-direction; and a signal processing unit that generates the cross-sectional profile at each rotation angle of the motor based on the amount of light received. The light-receiving window is formed by a plane orthogonal to the optical axis of the light-receiving lens at approximately the center of the measurement range of the slit light scan.

Description

Technical Field

[0001] This utility model relates to an optical displacement meter. Background Technology

[0002] Traditional optical displacement gauges have the following structure: the light-emitting system and the light-receiving system are housed in a housing, and the housing is provided with a light-emitting window and a light-receiving window to prevent dust from adhering to the light-emitting system and the light-receiving system.

[0003] In conventional optical displacement meters, the relative angle between the light-receiving system, including the light-receiving lens and the camera unit, and the light-receiving window is fixed. Therefore, there is no change in the light-receiving performance corresponding to the angle between the optical axis of the light-receiving window and the light-receiving lens.

[0004] In situations where conventional optical displacement gauges are used to acquire two-dimensional profiles of the XZ cross-sections of a workpiece at different positions in the Y direction, and to generate three-dimensional shape data based on these profiles, the conventional optical displacement gauge must be moved relative to the workpiece in the Y direction. Therefore, equipment such as conveyor belts for transporting the workpiece and linear motion mechanisms for moving the conventional optical displacement gauge body relative to the workpiece is required. However, the introduction of such equipment may be hindered by factors such as installation space and cost.

[0005] On the other hand, as an optical displacement meter that can acquire two-dimensional profiles of the XZ cross sections at different positions in the Y direction of a workpiece without the aforementioned equipment and generate three-dimensional shape data based on these two-dimensional profiles, it is known that an optical displacement meter rotates the light-emitting system and the light-receiving system (see Patent Document 1 and Patent Document 2).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: European Patent Application Publication No. 3232152

[0009] Patent Document 2: Chinese Utility Model No. 210664364 Specification Utility Model Content

[0010] Problems to be solved by utility models

[0011] In an optical displacement meter that rotates the light-emitting system and the light-receiving system, the relative angle between the light-receiving system and the light-receiving window, including the light-receiving lens and the camera unit, changes according to the rotation angle of the light-emitting system and the light-receiving system. Therefore, the change in light-receiving performance corresponding to the relative angle between the optical axis of the light-receiving window and the light-receiving lens cannot be ignored.

[0012] However, neither Patent Document 1 nor Patent Document 2 addresses the changes in light-receiving performance corresponding to the relative angle between the optical axes of the light-receiving window and the light-receiving lens.

[0013] In view of the above problems, the purpose of this utility model is to provide an optical displacement meter that can suppress the deterioration of light-receiving performance caused by the change of the relative angle between the light-receiving window and the light-receiving lens.

[0014] Solution for solving the problem

[0015] The optical displacement meter involved in this utility model is, for example, an optical sectioning type optical displacement meter that measures the cross-sectional profile of a workpiece with height in the Z direction based on the principle of triangulation. The optical displacement meter includes: a light-emitting and light-receiving module, which has a light-emitting part that illuminates the workpiece with slit light extending in the X direction, a light-receiving lens that converges the reflected light from the workpiece, and an imaging part that receives the light converged by the light-receiving lens; a motor that rotates the light-emitting and light-receiving module integrally; a housing that houses the light-emitting and light-receiving module and is provided with a light-receiving window through which the reflected light passes; and a control unit that controls the motor to... The slit light scans in a direction orthogonal to the X direction; and a signal processing unit generates three-dimensional shape data of the workpiece based on the amount of light received by the imaging unit, wherein the positional relationship between the light-receiving window and the light-receiving lens is set such that when the slit light is irradiated at approximately the center of the measurement range of the slit light scanning, at least one of the incident surface and the exit surface of the light-receiving window is formed by a plane orthogonal to the optical axis of the light-receiving lens, and the measurement range is formed by the range in which the light-projecting unit, the light-receiving lens, and the imaging unit all satisfy Schahm's law when the light-projecting and light-receiving module is rotated to each angle.

[0016] Preferably, the approximate center position of the measurement range is the approximate center angle of the rotation angle range of the light-emitting and light-receiving module during the measurement action.

[0017] Preferably, the optical displacement meter has a measurement period and a non-measurement period, wherein during the measurement period, the light-emitting and light-receiving module is rotated at approximately the same speed in a first rotation direction or a second rotation direction opposite to the first rotation direction to perform the measurement action; during the non-measurement period, the rotation direction of the light-emitting and light-receiving module is switched, and the measurement action is not performed; and during the measurement period, the light-receiving window is orthogonal to the optical axis of the light-receiving lens at the approximately center position of the measurement range.

[0018] Preferably, during the non-measurement period, the light-receiving range of the light-receiving lens intersects with the portion of the housing other than the light-receiving window.

[0019] Preferably, the approximate center position of the measurement range is the approximate center position of the maximum range in which the measurement action can be performed, and the optical displacement gauge accepts the selection of a portion of the maximum range and uses that portion of the range as the new measurement range to perform the measurement action.

[0020] Preferably, the optical displacement meter accepts changes in the width of the measurement range, sets a new measurement range after the change where the light-receiving window and the optical axis of the light-receiving lens are orthogonal at approximately the center position, and performs the measurement action within this new measurement range.

[0021] Preferably, the light-projecting and light-receiving module is separated from the light-receiving window regardless of its rotational position within the measurement range, and the optical axis of the light-receiving lens passes through the light-receiving window.

[0022] Preferably, the light-receiving part having the light-receiving lens and the camera part is separated from the light-receiving window regardless of its rotational position, which is within the angular range that allows the light-emitting and light-receiving module to rotate via the motor and outside the measurement range.

[0023] Preferably, the housing is provided with a light-transmitting window that allows light from the slit of the light-projecting part to pass through. At one end of the rotation range of the light-projecting and light-receiving module, the light-receiving window is separated from and closest to the end of the light-receiving part having the light-receiving lens and the camera part on the workpiece side, and the inner wall of the housing is separated from the light-projecting part. At the other end of the rotation range, the light-projecting window is separated from and closest to the end of the light-projecting part on the workpiece side, and the inner wall of the housing is separated from the light-receiving part.

[0024] Preferably, the light-projecting and light-receiving module further includes a reflective member disposed in the optical path between the light-receiving window and the camera unit. The reflective member is used to refract the reflected light back. The control unit controls the motor to rotate the light-projecting and light-receiving module, including the reflective member, as a whole. Regardless of the rotational position of the reflective member within the measurement range, it remains separate from the light-receiving window.

[0025] Preferably, the light transmission characteristics of the light-receiving window at one end of the measurement range are approximately the same as those at the other end of the measurement range.

[0026] Preferably, in the housing, a projection window is provided separately from the light-receiving window to allow the slit light from the projection section to pass through. The positional relationship between the projection window and the projection section is set such that when the slit light is irradiated at approximately the center of the measurement range of the slit light scanning, at least one of the slit light incident surface and the slit light exit surface of the projection window is formed by a plane orthogonal to the projection axis of the projection section.

[0027] Preferably, the light transmission characteristics of the projection window at one end of the measurement range are approximately the same as those at the other end of the measurement range.

[0028] Furthermore, other features, elements, steps, advantages, and characteristics will become more apparent from the following description of the implementation of the utility model and the accompanying drawings.

[0029] Effects of the utility model

[0030] According to this invention, an optical displacement meter can be provided that can suppress the deterioration of light-receiving performance caused by changes in the relative angle between the light-receiving window and the light-receiving lens. Attached Figure Description

[0031] Figure 1 This is a diagram illustrating an optical displacement measurement system.

[0032] Figure 2 This is a diagram illustrating the principle of triangulation.

[0033] Figure 3 This is a diagram illustrating an optical displacement meter with a reflective element.

[0034] Figure 4 This is a diagram illustrating the method for detecting peak positions.

[0035] Figure 5 This is a functional block diagram of an optical displacement meter.

[0036] Figure 6 This is the first example diagram illustrating the configuration of a motor.

[0037] Figure 7 This is the first example diagram illustrating the configuration of a motor.

[0038] Figure 8 This is the second example diagram illustrating the motor configuration.

[0039] Figure 9 This is the second example diagram illustrating the motor configuration.

[0040] Figure 10 This is a diagram illustrating the processing flow of the measurement action of an optical displacement measurement system.

[0041] Figure 11 This is a diagram illustrating the configuration of the light-receiving window. Detailed Implementation

[0042] <Optical Displacement Measurement System>

[0043] Figure 1 This is a diagram showing a schematic structural example of an optical displacement measurement system. The optical displacement measurement system 100 of this structural example includes an optical displacement gauge 1, a control device 2, a display device 3, and an input device 4.

[0044] In this structural 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 of the slit light L1 passing through the projection section (in... Figure 1 (Not shown in the figure) corresponds to the direction of rotational movement. The XZ plane, described later, is a plane extending along the X and Z directions. Furthermore, the optical displacement meter 1 scans the slit light L1 by rotating the light-emitting and light-receiving module 20; therefore, the scanning direction of the slit light L1 is a direction orthogonal to the X direction on the YZ plane, including the Y direction. In addition, in this specification, "rotation" means a reciprocating oscillating motion around a rotation axis.

[0045] The optical displacement measurement system 100 is a system for measuring the contour and three-dimensional shape of a workpiece W. The contour of the workpiece W refers to the data representing the outer edge of the cross-section of the workpiece W produced by the slit light L1. When the slit light is illuminated parallel to the XZ plane, the contour of the workpiece W becomes the data representing the outer edge of the cross-section parallel to the XZ plane, and is therefore also called the two-dimensional contour of the XZ section of the workpiece W.

[0046] For example, a contour is a collection of (xi, zi) where i is the index. xi represents the position in the X direction, and zi represents the height in the Z direction. Similarly, a 3D shape is a collection of (xi, yi, zi), where yi represents the position in the Y direction.

[0047] 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 along the X direction and receives reflected light L2 from the workpiece W. Furthermore, the optical displacement meter 1 calculates the contour of the workpiece W based on the received light. The optical displacement meter 1 performs imaging at regular intervals to generate different contours of the workpiece W. Additionally, the optical displacement meter 1 generates three-dimensional shape data of the workpiece W based on these different contours.

[0048] The control device 2 outputs an instruction based on the user input received by the input device 4 to the optical displacement meter 1, and receives the measurement result of the workpiece W from the optical displacement meter 1. Additionally, the control device 2 outputs a display signal to the display device 3. The control device 2 is, for example, a personal computer, a programmable logic controller, etc.

[0049] The display device 3 displays, for example, the measurement results of the workpiece W, and the UI (user interface) for setting the optical displacement meter 1, based on the display signal from the control device 2.

[0050] Input device 4 accepts user input for the optical displacement measurement system 100. Figure 1 In the illustration, a keyboard and a mouse are shown as input devices 4. However, input device 4 is not limited to a keyboard and a mouse. For example, input device 4 could also be a touch panel disposed on the display screen of display device 3.

[0051] Figure 2 This diagram illustrates the principle of optical tangential (triangulation) distance measurement. Inside the housing 10 of the optical displacement meter 1 are housed a light-projecting unit 11, a light-receiving lens 12, and an image-capturing unit 13. The light-projecting unit 11 includes a light source 14 and a projection lens 15. For example, the light source 14 is a laser beam emitter, and the projection lens 15 can also be composed of multiple lenses, including cylindrical lenses.

[0052] The light emitted from the light source 14 is converted into slit light L1 by the projection lens 15. A light-transmitting window 16 is provided in the housing 10 to allow the slit light L1 to pass through. Similarly, a light-receiving window 17 is provided in the housing 10 to allow reflected light L2 to pass through. The projection window 16 and the light-receiving window 17 are separate (different components). By separating the projection window 16 and the light-receiving window 17, each is a flat plate, thus simplifying their manufacture. However, the projection window 16 and the light-receiving window 17 can also be integrated (a single component).

[0053] The light-receiving lens 12 is a lens used to converge the reflected light L2 and image it onto the light-receiving surface of the imaging unit 13. The light-receiving lens 12 can be a structure comprising only one lens or multiple lenses. Alternatively, the light-receiving lens 12 can also include optical components other than lenses (e.g., optical filters). The imaging unit 13 is an image sensor having multiple photoelectric conversion elements arranged in a two-dimensional pattern. The imaging unit 13 receives the light converged by the light-receiving lens.

[0054] like Figure 2As shown, the optical axis AX2 of the light-receiving lens 12 is tilted relative to the projection axis AX1 of the light-projecting section 11. The projection axis AX1 of the light-projecting section 11 is aligned with the optical axis of the light source 14. Therefore, the reflected light L2 from height Z1 is imaged at position V1 in the V direction of the light-receiving surface of the imaging section 13, and the reflected light L2 from height Z2 is imaged at position V2 in the V direction of the light-receiving surface of the imaging section 13. In other words, the V direction of the light-receiving surface of the imaging section 13 corresponds to the Z direction of the workpiece W. Although the U direction of the light-receiving surface of the imaging section 13 is not shown, it corresponds to the X direction of the workpiece W. That is, the longitudinal direction of the image output by the imaging section 13 is the V direction, and the transverse direction is the U direction.

[0055] The light-projecting unit 11, the light-receiving lens 12, and the imaging unit 13 are rotatable about a rotation axis AX3 along the X direction. The relative positions of the light-projecting unit 11, the light-receiving lens 12, and the imaging unit 13 are fixed. Figure 2 In the diagram, the states of the projection unit 11, the light-receiving lens 12, and the imaging unit 13 before rotating counterclockwise (CCW) are shown in solid lines, and the states of the projection unit 11, the light-receiving lens 12, and the imaging unit 13 after rotating counterclockwise (CCW) are shown in dashed lines.

[0056] By limiting motor 21 (see below) Figure 5 The rotation range of the light-projecting unit 11, the light-receiving lens 12, and the camera unit 13 is also limited. The limitation of the rotation range of the motor 21 can be achieved, for example, by controlling the motor 21, or by physically stopping the light-projecting and light-receiving module 20 (see below). Figure 5 This is achieved through the movement of stop components.

[0057] At one end of the rotation range of the motor 21, the light-receiving window 17 is separated from and closest to the end of the light-receiving part 18, which has a light-receiving lens 12 and an imaging part 13, on the workpiece W side, and the inner wall of the housing 10 is separated from the light-projecting part 11. At the other end of the rotation range of the motor 21, the light-projecting window 16 is separated from and closest to the end of the light-projecting part 11 on the workpiece W side, and the inner wall of the housing 10 is separated from the light-receiving part 18. Thus, the housing 10 can be miniaturized while avoiding contact between the light-receiving window 17 and the light-receiving part 18, and between the light-projecting window 16 and the light-projecting part 11.

[0058] The light-projecting unit 11, the light-receiving lens 12, and the imaging unit 13 can rotate around the rotation axis AX3 in the X direction, with the light-receiving surface of the imaging unit 13 tilted relative to the optical axis of the light-receiving lens 12, satisfying the relationship of Scherm's law. Therefore, in Figure 2In region R1, illustrated by a grid, focus is applied to each section through which the optical axis AX1 passes. That is, even if the height of the workpiece W changes, the optical displacement gauge 1 can generate a focused outline of the workpiece W. Therefore, region R1 can be set as the measurement range of the slit light L1. In other words, the measurement range of the slit light L1 is determined by the motor 21 (see below). Figure 5 The range in which the relationship of Scherm's Law holds true at each rotation angle can be determined.

[0059] Furthermore, the positional relationship between the light-projecting part 11, the light-receiving lens 12, and the imaging part 13 can also be related to... Figure 2 The positional relationships shown are reversed.

[0060] In addition, such as Figure 3 As shown, the optical displacement meter 1 may also include a reflective member 19. When the optical displacement meter 1 includes the reflective member 19, the light-receiving part 18 has a structure including a light-receiving lens 12, an imaging part 13, and the reflective member 19. The reflective member 19 is provided in the optical path between the light-receiving window 17 and the imaging part 13, and is used to fold the reflected light L2 and the optical axis AX2 of the light-receiving lens 12 back toward the light-projecting part 11. As a result, a light-projecting and light-receiving module that integrates the light-projecting part 11, the light-receiving lens 12, the imaging part 13, and the reflective member 19 can be compactly constructed on the YZ plane extending along the Y and Z directions. Therefore, the moment of inertia of the light-projecting and light-receiving module that integrates the light-projecting part 11, the light-receiving lens 12, the imaging part 13, and the reflective member 19 about the rotation axis AX3 can be reduced.

[0061] exist Figure 3 In this configuration, the reflective member 19 is disposed in the optical path between the light-receiving lens 12 and the imaging unit 13. However, the reflective member 19 may also be disposed in the optical path between the light-receiving window 17 and the light-receiving lens 12 (for example, see the description below). Figure 8 and Figure 9 ).

[0062] When the reflecting member 19 is disposed in the optical path between the light-receiving lens 12 and the imaging unit 13, the reflecting member 19 reflects the light focused by the light-receiving lens 12, thus making the area of ​​the reflecting surface of the reflecting member 19 small. When the reflecting member 19 is disposed in the optical path between the light-receiving window 17 and the light-receiving lens 12, the heavy light-receiving lens 12 can be arranged close to the rotation axis AX3, thus increasing the effect of reducing the moment of inertia.

[0063] <Position (height calculation)>

[0064] Figure 4This diagram illustrates a method for calculating the height of a contour based on the image I1, which is the result of light reception output by the imaging unit 13. The slit light L1 has a certain width in the Y direction. Therefore, the width of the light spot generated by the reflected light L2 on the light-receiving surface of the imaging unit 13 is also a width that spans multiple photoelectric conversion elements.

[0065] Therefore, the optical displacement meter 1 calculates an approximate curve P1 representing the change in brightness value based on the brightness value of each pixel, and calculates the position of the peak value in the approximate curve P1 in the V direction. Figure 4 In the diagram, the leftmost column is the column of interest, illustrating the distribution of brightness values ​​(approximate curve P1). The approximate curve P1 is obtained by curve fitting to multiple sampled values. Sampled values ​​below the detection threshold are not considered. The location where the peak value occurs in the V direction represents the height of the workpiece W. The optical displacement meter 1 calculates the approximate curve P1 at each position (each pixel column) in the U direction, and calculates the location (height) of the peak value in the V direction based on the approximate curve P1. By performing this calculation at each position in the U direction, a contour can be obtained. This type of calculation can also be called sub-pixel processing.

[0066] Furthermore, for example, by pre-shipment calibration, coordinate transformation conditions (e.g., coordinate transformation table) representing the correspondence between UV coordinates and rotation angle θ and local coordinates (X,Y,Z) are generated, such as by (U,V,θ)=(X,Y,Z), and the coordinate transformation conditions are stored in the storage unit (not shown) of the optical displacement meter 1. Therefore, the optical displacement meter 1 can transform the profile in the UV coordinate system to the profile in the XYZ coordinate system based on the rotation angle θ through simple calculation.

[0067] <Function Block>

[0068] Figure 5 This is a functional block diagram of the optical displacement meter 1. The optical displacement meter 1 includes a light-emitting and light-receiving module 20, a motor 21, and a control unit 22.

[0069] The light-emitting and light-receiving module 20 integrates the light-emitting part 11, the light-receiving lens 12, and the imaging part 13. Furthermore, when the optical displacement meter 1 includes a reflective member 19, the light-emitting and light-receiving module 20 integrates the light-emitting part 11, the light-receiving lens 12, the imaging part 13, and the reflective member 19 (in... Figure 5 (Not shown in the image) Maintained as a whole.

[0070] Motor 21 rotates the light-projecting unit 11, the light-receiving lens 12, and the camera unit 13. More specifically, motor 21 rotates the light-projecting and light-receiving module 20. Motor 21 can rotate the light-projecting and light-receiving module 20 either by direct drive without an intermediate mechanism such as a speed reducer between motor 21 and the light-projecting and light-receiving module 20, or by rotating the light-projecting and light-receiving module 20 via an intermediate mechanism such as a speed reducer.

[0071] 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, which are in a state satisfying Scheres' law, thereby scanning the slit light L1 in a direction orthogonal 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, which are in a state satisfying Scheres' law, and the signal processing unit 24 controls the light-projecting unit 11 to illuminate the slit light L1 from the light-projecting unit 11.

[0072] The signal processing unit 24 includes a peak detection unit 26, a contour generation unit 27, and a three-dimensional data generation unit 28. The peak detection unit 26 detects the position (peak position) of the peak that generates brightness values ​​in the V direction based on the light reception results output from the camera unit 13. The contour generation unit 27 generates contour data by summing the heights (zi) at each position (xi) in the X direction of the workpiece W obtained by the peak detection unit 26. The three-dimensional data generation unit 28 generates three-dimensional shape data of the workpiece W based on the different contours of the workpiece W generated by the contour generation unit 27. Furthermore, at least some of the peak detection unit 26, contour generation unit 27, and three-dimensional data generation unit 28 may not be housed inside the optical displacement meter 1, but rather in the control device 2 (see reference 1). Figure 1 (the interior of)

[0073] The communication unit 25 communicates with the control device 2 via wired or wireless means. For example, the communication unit 25 receives instructions from the control device 2 and transmits these instructions to the control unit 22. Additionally, the communication unit 25 sends, for example, contour data and three-dimensional shape data of the workpiece W generated by the signal processing unit 24 to the control device 2.

[0074] <Motor Configuration>

[0075] Figure 6 and Figure 7 This is a diagram illustrating the first example of the configuration of motor 21. Figure 6 yes Figure 7 A cross-sectional view of the optical displacement meter 1 at the BB′ line, perpendicular to the X direction. Figure 7 yes Figure 6 A cross-sectional view of the optical displacement meter 1 along the XZ plane at line AA′.

[0076] In the first example, the light-projecting and light-receiving module 20 has a plate-shaped base member 201 extending along a plane perpendicular to the X direction. The light-projecting part 11, the light-receiving lens 12, the imaging part 13, and the reflective member 19 are mounted on the base member 201.

[0077] In the first example, the light-emitting and light-receiving module 20 does not overlap with the motor 21 and its auxiliary components in the X direction. The auxiliary components of the motor 21 are, for example, an encoder that detects the rotational amount of the motor 21's rotor. According to this first example of the motor 21's configuration, the light-emitting section 11 can be easily arranged close to the light-receiving lens 12 and the camera section 13. By bringing the light-emitting section 11 close to the light-receiving lens 12 and the camera section 13, the light-emitting and light-receiving module 20 can be compactly configured. Therefore, the moment of inertia of the light-emitting and light-receiving module 20 about the rotation axis AX3 can be reduced.

[0078] In addition, in the first example, the control unit 22 does not overlap with the light-emitting and light-receiving module 20 in the X direction, but overlaps with the motor 21 in the X direction.

[0079] Figure 8 and Figure 9 This is a second example of the configuration of motor 21. Figure 8 yes Figure 9 A cross-sectional view of the optical displacement meter 1 at the BB′ line, perpendicular to the X direction. Figure 9 yes Figure 8 A cross-sectional view of the optical displacement meter 1 at line AA′ perpendicular to the Z direction.

[0080] In the second example, the light-projecting and light-receiving module 20 includes a base member 201. The base member 201 includes a cylindrical portion extending in the X direction, a cover portion for blocking one end of the cylindrical portion in the X direction, and a flange portion extending radially outward from the other end of the cylindrical portion in the X direction. The light-projecting portion 11, the light-receiving lens 12, the imaging portion 13, and the reflective member 19 are mounted on the flange portion of the base member 201.

[0081] In the second example, the light-emitting and light-receiving module 20 overlaps with at least one of the motor 21 and its auxiliary components in the X direction. Similar to the first example, the auxiliary component of the motor 21 is, for example, an encoder that detects the amount of rotation of the motor 21's rotor. According to the second example of the motor 21's configuration, it is easy to arrange the light-emitting section 11 away from the light-receiving lens 12 and the imaging section 13. By distancing the light-emitting section 11 from the light-receiving lens 12 and the imaging section 13, the scanning range of the slit light L1 can be expanded.

[0082] In the second example, the control unit 22 overlaps with the light-emitting and light-receiving module 20 and the motor 21 in the X direction. Alternatively, the control unit 22 may be positioned so that it does not overlap with the motor 21 in the X direction but overlaps with the motor 21 when viewed along the X direction. When the control unit 22 is positioned so that it does not overlap with the motor 21 in the X direction but overlaps with the motor 21 when viewed along the X direction, the control unit 22 may or may not overlap with the light-emitting and light-receiving module 20 and the motor 21 in the X direction.

[0083] <Processing Flow>

[0084] Figure 10 This is a diagram illustrating the processing flow of the measurement operation of the optical displacement measurement system 100. When the input device 4 receives user input indicating the start of measurement, the measurement begins... Figure 10 The processing flow.

[0085] First, in step S1, the light-projecting unit 11 begins to illuminate the slit light L1. In the following step S2, the motor control unit 23 starts rotating the motor 21. Furthermore, the processes in steps S1 and S2 can be performed simultaneously. Alternatively, the motor control unit 23 can rotate the motor before performing step S1 to move the light-projecting and light-receiving module 20 to a predetermined scanning start position. Through the processes of steps S1 and S2, scanning of the slit light L1 begins.

[0086] In the next step S3, the motor control unit 23 determines whether the rotation amount (rotation angle) of the motor 21 since the start of rotation is smaller than a threshold. If the rotation amount of the motor 21 since the start of rotation is smaller than the threshold, the determination process in step S3 continues, and the scanning of the slit light L1 continues.

[0087] When the rotation amount of motor 21 from the start of rotation reaches a threshold, the process proceeds to step S4. Furthermore, the threshold is the rotation amount calculated based on the measurement range. The measurement range is set by default; if the user changes the measurement range, the control unit 22 (e.g., the signal processing unit 24) calculates the threshold for the rotation amount based on the changed measurement range.

[0088] In step S4, the motor control unit 23 stops the rotation of the motor 21. In the next step S5, the projection unit 11 stops the illumination of the slit light L1. Furthermore, the processes in step S4 and step S5 can be performed simultaneously. Through the processes in steps S4 and S5, the scanning of the slit light L1 is completed.

[0089] In the next step S6, the contour generation unit 27 generates a contour. Furthermore, the contour generation unit 27 can also begin generating the contour while the slit light L1 is scanning.

[0090] In the next step S7, the three-dimensional data generation unit 28 generates three-dimensional data.

[0091] In the next step S8, 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 its contour, a three-dimensional image of the workpiece W based on three-dimensional data, etc. When the processing in step S8 ends, Figure 10 The processing flow has ended.

[0092] The optical displacement meter 1 has a measurement period and a non-measurement period. During the measurement period, the light-emitting and receiving module 20 is rotated at approximately the same speed in either a first rotation direction (counterclockwise CCW) or a second rotation direction (clockwise CW) to perform the measurement action. During the non-measurement period, the rotation direction of the light-emitting and receiving module 20 is switched, but no measurement action is performed. During the measurement period, the motor rotates the light-emitting and receiving module 20 at approximately the same speed. The light-receiving window 17 is orthogonal to the optical axis AX2 of the light-receiving lens at approximately the center position of the measurement range during the measurement period. Regarding the rotation direction switching period, since it is necessary to consider deceleration and acceleration, and the calculation of the correlation between the peak position in the V direction and the rotation angle becomes complicated, it is set as the non-measurement period. By aligning the light-receiving window 17 and the light-receiving lens 12 at approximately the center position of the measurement range during the measurement period, which allows for approximately the same speed and stable measurement, the influence of the deterioration of light transmission characteristics caused by rotation on the measurement action can be suppressed.

[0093] <Configuration of the light-receiving window>

[0094] Figure 11 This is a diagram illustrating the configuration of the light-receiving window 17. Figure 11 This is a diagram showing the positional relationship between the light-receiving window 17 and the light-receiving lens 12 when the slit light L1 is irradiated at the approximate center position of the scanning range scanned by the slit light L1 through the control unit 22.

[0095] The light-receiving window 17 has an incident surface 171 for the reflected light L2 to enter and an exit surface 172 for the reflected light L2 to exit. At least one of the incident surface 171 and the exit surface 172 is formed by a plane orthogonal to the optical axis AX2 of the light-receiving lens 12. More preferably, as shown in the figure... Figure 11 As shown, both the incident surface 171 and the exit surface 172 are composed of planes orthogonal to the optical axis AX2 of the light-receiving lens 12. That is, when the slit light L1 is irradiated at approximately the center position of the scanning range, the light-receiving window 17 is directly opposite the light-receiving lens 12, thereby optimizing the light-receiving performance. 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.

[0096] On the other hand, the farther the slit light L1 is from the approximate center of the scanning range, the greater the tilt of the light-receiving lens 12 relative to the light-receiving window 17, and the worse the light-receiving performance.

[0097] However, by configuring the light-receiving window 17 in a manner that optimizes light-receiving performance when the slit light L1 is irradiated at approximately the center of the scanning range, it is possible to suppress the deterioration of light-receiving performance 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. As a result, it is possible to suppress the deterioration of light-receiving performance throughout the entire scanning range.

[0098] By configuring the light-receiving window 17 in a manner that optimizes light reception performance when the slit light L1 is irradiated at approximately the center of the scanning range, for one end of the scanning range (e.g., Figure 2 The light-receiving properties of the region R1 (position of height Z2) shown are related to the other end of the scanning range (e.g., Figure 2 The light-receiving properties of the area R1 at the height Z0 shown are roughly the same.

[0099] During the non-measurement period, the light-receiving range of the light-receiving lens 12 intersects with the portion of the housing 10 other than 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) other than the light-receiving window 17, so the area of ​​the light-receiving window 17 can be reduced, thereby achieving cost reduction and increased freedom in the configuration of the projection window 16, etc.

[0100] The approximate center position of the scanning range can be either the approximate center angle of the rotation angle range of the light-emitting and light-receiving module 20 during the measurement operation, or the approximate center position of the measurement range of the slit light L1 in the Y direction during the measurement operation. Furthermore, the approximate center position of the scanning range can be any position where the different rotation angles of the light-emitting and light-receiving module 20 converge within ±10° relative to the center position of the scanning range. More preferably, the approximate center position of the scanning range can be any position where the different rotation angles of the light-emitting and light-receiving module 20 converge within ±5° relative to the center position of the scanning range.

[0101] If the first difference and the second difference are equal as described later, the scanning range can be, for example, the rotation angle range of the light-emitting and light-receiving module 20 during the measurement operation.

[0102] The first difference is the difference between the rotation angle of the light-emitting and receiving module 20 at the start of the measurement action performed by scanning the slit light L1 (or the rotation angle of the motor 21 in the case of direct drive) and the rotation angle of the light-emitting 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-emitting and receiving module 20 when the slit light L1 is parallel to the Z direction and the rotation angle of the light-emitting and receiving module 20 at the end of the measurement action performed by scanning the slit light L1. The range of the rotation angle of the light-emitting and receiving module 20 is the difference between the rotation angle of the light-emitting and receiving module 20 at the start of scanning the slit light L1 and the rotation angle of the light-emitting and receiving module 20 at the end of scanning the slit light L1.

[0103] Alternatively, the rotation angle of the light-emitting and light-receiving module 20 at the start of the scanning of the slit light L1 may include multiple angles, and the rotation angle of the light-emitting and light-receiving module 20 at the end of the scanning of the slit light L1 may also include multiple angles. For example, the rotation angle of the light-emitting and light-receiving module 20 at the start of the scanning of the slit light L1 may include a first angle θ1 and a second angle θ2, and the rotation angle of the light-emitting and light-receiving module 20 at the end of the scanning of the slit light L1 may also include a first angle θ1 and a second angle θ2. If the rotation angle of the light-emitting and light-receiving module 20 changes from the first angle θ1 to the second angle θ2 in the previous scan, the control unit 22 controls the motor 21 to change the rotation angle of the light-emitting and light-receiving module 20 from the second angle θ2 to the first angle θ1 in the current scan. Conversely, if the rotation angle of the light-emitting and light-receiving module 20 changed from the second angle θ2 to the first angle θ1 in the previous scan, the control unit 22 controls the motor 21 to change the rotation angle of the light-emitting and light-receiving module 20 from the first angle θ1 to the second angle θ2 in the current scan. Furthermore, the first angle θ1 and the second angle θ2 are defined as rotation angles relative to the position (rotation angle) of the light-emitting and light-receiving module 20 when the slit light L1 is parallel to the Z direction.

[0104] If the first difference and the second difference are not equal, the scanning range can be, for example, the measurement range of the slit light L1 in the Y direction.

[0105] Regardless of its rotational position within the scanning range, the light-receiving part 18 is separated from the light-receiving window 17, and the optical axis AX2 of the light-receiving lens 12 passes through the light-receiving window 17. As a result, the light-receiving lens 12 can converge the reflected light L2 throughout the entire scanning range, thus enabling the scanning range to be set as the scanning range during the measurement operation.

[0106] Furthermore, the optical displacement meter 1 may also have multiple scanning ranges (measurement ranges) scanned by the slit light L1 via the control unit 22. In this case, it is sufficient that the configuration of the light-receiving window 17 described above is established for at least one of the multiple 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 portion of the maximum range via the communication unit 25, sets that portion of the range as a new measurement range via the signal processing unit 24, and performs the measurement operation for that new measurement range. At the approximate center position of the maximum range, the light-receiving window 17 is orthogonal to the optical axis AX2 of the light-receiving lens, so that the light transmission characteristics of the light-receiving window 17 do not deteriorate drastically depending on the position of the measurement range. Therefore, it is possible to increase the degree of freedom of measurement while suppressing the influence of the deterioration of the light transmission characteristics caused by rotation on the measurement operation. Alternatively, the optical displacement meter 1 can receive changes in the measurement range via the communication unit 25, set a new measurement range after the change where the light-receiving window 17 is orthogonal to the optical axis AX2 of the light-receiving lens 12 at approximately the center position, and perform the measurement operation within this new measurement range. Even when the measurement range is changed according to the size of the workpiece, etc., by making the light-receiving window 17 orthogonal to the optical axis AX2 of the light-receiving lens 12 at approximately the center position of each measurement range, the influence of the deterioration of light transmission characteristics caused by rotation on the measurement operation can be further suppressed.

[0107] <Spectrum Window Configuration>

[0108] Preferably, the positional relationship between the projection window 16 and the projection section 11 when the slit light L1 is irradiated at approximately the center position of the scanning range scanned by the slit light L1 through the control unit 22 is the same as the positional relationship between the receiving window 17 and the receiving lens 12. That is, preferably, the projection window 16 has a slit light incident surface for the slit light L1 to enter and a slit light exiting surface for the slit light L1 to exit, and at least one of the slit light incident surface and the slit light exiting surface when the slit light L1 is irradiated at approximately the center position of the scanning range scanned by the slit light L1 through the control unit 22 is formed by a plane orthogonal to the projection axis AX1 of the projection section 11. With this structure, it is possible to suppress the deterioration of projection performance caused by changes in the relative angle between the projection window 16 and the projection axis AX1 of the projection section 11.

[0109] Summary

[0110] The various implementation methods described above will now be summarized in general.

[0111] For example, the optical displacement meter disclosed in this specification is an optical sectioning type optical displacement meter that measures the cross-sectional profile of a workpiece with height in the Z direction based on the principle of triangulation. The optical displacement meter includes: a light-emitting and light-receiving module having a light-emitting part that irradiates the workpiece with slit light extending in the X direction, a light-receiving lens that converges the reflected light from the workpiece, and an imaging part that receives the light converged by the light-receiving lens; a motor that integrally rotates the light-emitting and light-receiving module; a housing that houses the light-emitting and light-receiving module and is provided with a light-receiving window through which the reflected light passes; a control unit that controls the motor to scan the slit light in a direction orthogonal to the X direction; and a signal processing unit that generates the cross-sectional profile at each rotation angle of the motor based on the amount of light received by the imaging part, wherein the light-receiving window is formed by a plane orthogonal to the optical axis of the light-receiving lens at approximately the center position of the measurement range of the slit light scan (first structure).

[0112] In the optical displacement meter of the first structure described above, it may also be the following structure: the approximate center position of the measurement range is either the approximate center angle of the rotation angle range of the light-emitting and light-receiving module during the measurement action or the approximate center position of the measurement range in the Y direction orthogonal to the XZ plane (second structure).

[0113] In the optical displacement meter of the first or second structure described above, the following structure may also be used: the optical displacement meter has a measurement period and a non-measurement period, wherein, during the measurement period, the light-emitting and light-receiving module is rotated at approximately the same speed in a first rotation direction or a second rotation direction opposite to the first rotation direction to perform the measurement action, and during the non-measurement period, the rotation direction of the light-emitting and light-receiving module is switched without performing the measurement action, and the light-receiving window is orthogonal to the optical axis of the light-receiving lens at the approximately center position of the measurement range during the measurement period (third structure).

[0114] In any of the optical displacement gauges described in structures 1 to 3 above, the following structure may also be used: during the non-measurement period, the light-receiving range of the light-receiving lens intersects with the portion of the housing other than the light-receiving window (structure 4).

[0115] In any of the optical displacement gauges in the first to fourth structures described above, the following structure may also be used: the approximate center position of the measurement range is the approximate center position of the maximum range in which the measurement action can be performed, and the optical displacement gauge accepts the selection of a portion of the maximum range and uses that portion of the range as the new measurement range to perform the measurement action (fifth structure).

[0116] In any of the optical displacement meters in the above-mentioned structures 1 to 5, the optical displacement meter may also have the following structure: the optical displacement meter accepts changes in the width of the measurement range, sets a new measurement range after the change in which the light-receiving window and the optical axis of the light-receiving lens are orthogonal at approximately the center position, and performs the measurement action within the new measurement range (structure 6).

[0117] In any of the optical displacement gauges in the first to sixth structures described above, the following structure may also be used: the light-emitting and light-receiving module is separated from the light-receiving window regardless of its rotational position within the measurement range, and the optical axis of the light-receiving lens passes through the light-receiving window (seventh structure).

[0118] In any of the optical displacement meters in the first to seventh structures described above, the following structure may also be used: the light-receiving part having the light-receiving lens and the camera part is separated from the light-receiving window regardless of the rotational position within the angle range that the light-emitting and light-receiving module can be rotated by the motor and outside the measurement range (the eighth structure).

[0119] In any of the optical displacement gauges in structures 1 to 8 described above, the following structure may also be used: a light-transmitting window with light transmission is provided in the housing to allow light from the slit of the light-emitting part to pass through; at one end of the rotation range of the light-emitting and light-receiving module, the light-receiving window is separated from and closest to the end of the light-receiving part having the light-receiving lens and the camera part on the workpiece side, and the inner wall of the housing is separated from the light-emitting part; at the other end of the rotation range, the light-emitting window is separated from and closest to the end of the light-emitting part on the workpiece side, and the inner wall of the housing is separated from the light-receiving part (structure 9).

[0120] In any of the optical displacement meters in the above-mentioned structures 1 to 9, the following structure may also be used: the light-emitting and light-receiving module further includes a reflective member, which is disposed in the optical path between the light-receiving window and the camera unit. The reflective member is used to refract the reflected light back. The control unit controls the motor to rotate the light-emitting and light-receiving module, including the reflective member, as a whole. The reflective member is separated from the light-receiving window regardless of its rotational position within the measurement range (structure 10).

[0121] In any of the optical displacement gauges in the first to tenth structures described above, the following structure may also be used: the light transmission characteristics of the light-receiving window at one end of the measurement range are approximately the same as the light transmission characteristics of the light-receiving window at the other end of the measurement range (structure 11).

[0122] In any of the optical displacement gauges in the first to eleventh structures described above, the following structure may also be used: In the housing, a projection window is provided separately from the light-receiving window to allow light from the projection section to pass through, and the projection window is formed by a plane orthogonal to the projection axis of the projection section at approximately the center of the measurement range (the 12th structure).

[0123] In any of the optical displacement gauges in structures 1 through 12, the following structure may also be used: the light transmission characteristics of the projection window at one end of the measurement range are approximately the same as the light transmission characteristics of the projection window at the other end of the measurement range (structure 13).

[0124] <Other variations>

[0125] Furthermore, various modifications can be made to the technical features disclosed in this specification, in addition to the embodiments described above, without departing from the spirit of its technical design. That is, the embodiments described above should be considered illustrative rather than restrictive in all respects, and the scope of protection of this utility model should be understood to be defined by the claims, including all modifications within the meaning and scope equivalent to the claims.

[0126] Explanation of reference numerals in the attached figures

[0127] 1: Optical displacement gauge; 2: Control device; 3: Display device; 4: Input device; 10: Housing; 11: Projection section; 12: Receiving lens; 13: Camera section; 14: Light source; 15: Projection lens; 16: Projection window; 17: Receiving window; 171: Incident surface; 172: Exit surface; 18: Receiving section; 19: Reflecting component; 20: Projection and receiving module; 201: Base component; 21: Motor; 22: Control section; 23: Motor control section; 24: Signal processing section; 25: Communication section; 26: Peak detection section; 27: Contour generation section; 28: 3D data generation section; 100: Optical displacement measurement system; AX1: Projection axis; AX2: Optical axis; I1: Image; AX3: Rotation axis; R1: Area; W: Workpiece.

Claims

1. An optical displacement meter, which is an optical sectioning type optical displacement meter that measures the cross-sectional profile of a workpiece with height in the Z direction based on the principle of trigonometric ranging, characterized in that it comprises: The light-projecting and light-receiving module includes a light-projecting part that projects slit light extending in the X direction onto the workpiece, a light-receiving lens that converges reflected light from the workpiece, and a camera part that receives the light converged by the light-receiving lens. A motor that causes the light-emitting and light-receiving modules to rotate as a whole; The housing contains the light-emitting and light-receiving module and is provided with a light-receiving window that allows the reflected light to pass through; The control unit controls the motor to scan the slit light in a direction orthogonal to the X direction; as well as The signal processing unit generates three-dimensional shape data of the workpiece based on the amount of light received by the camera unit. The positional relationship between the light-receiving window and the light-receiving lens is configured such that when the slit light is irradiated at approximately the center of the measurement range of the slit light scan, at least one of the incident surface and the exit surface of the light-receiving window is formed by a plane orthogonal to the optical axis of the light-receiving lens. The measurement range is formed by the range in which the light-projecting part, the light-receiving lens, and the imaging part all satisfy Schahm's law when the light-projecting and light-receiving module is rotated to each angle.

2. The optical displacement meter according to claim 1, characterized in that, The approximate center position of the measurement range is the approximate center angle of the rotation angle range of the light-projecting and light-receiving module during the measurement action.

3. The optical displacement meter according to claim 1, characterized in that, Regardless of its rotational position within the measurement range, the light-projecting and light-receiving module is separated from the light-receiving window, and the optical axis of the light-receiving lens passes through the light-receiving window.

4. The optical displacement meter according to claim 3, characterized in that, Regardless of the rotational position of the light-receiving part, which has the light-receiving lens and the camera part, within the angular range that allows the light-projecting and light-receiving module to rotate via the motor and outside the measurement range, it is separated from the light-receiving window.

5. The optical displacement meter according to claim 1, characterized in that, The housing is provided with a light-transmitting window that allows light from the slit of the light-projecting part to pass through. At one end of the rotation range of the light-projecting and light-receiving module, the light-receiving window is separated from and closest to the workpiece-side end of the light-receiving part, which has the light-receiving lens and the camera part, and the inner wall of the housing is separated from the light-projecting part. At the other end of the rotation range, the projection window is separated from and closest to the end of the projection part on the workpiece side, and the inner wall of the housing is separated from the light-receiving part.

6. The optical displacement meter according to claim 1, characterized in that, The light-projecting and light-receiving module also includes a reflective component, which is disposed in the optical path between the light-receiving window and the camera unit. The reflective component is used to refract the reflected light back. The control unit controls the motor to rotate the light-emitting and light-receiving module, including the reflective component, as a whole. Regardless of its rotational position within the measurement range, the reflective component remains separated from the light-receiving window.

7. The optical displacement meter according to claim 1, characterized in that, The light transmission characteristics of the light-receiving window at one end of the measurement range are approximately the same as those at the other end of the measurement range.

8. The optical displacement meter according to claim 1, characterized in that, The housing includes a projection window, separate from the light-receiving window, that allows light from the slit in the projection section to pass through. The positional relationship between the projection window and the projection section is set such that when the slit light is irradiated at approximately the center of the measurement range of the slit light scanning, at least one of the slit light incident surface and the slit light exit surface of the projection window is formed by a plane orthogonal to the projection axis of the projection section.

9. The optical displacement meter according to claim 5, characterized in that, The light transmission characteristics of the projection window at one end of the measurement range are approximately the same as those at the other end of the measurement range.

Images