Shape measuring probe, three-dimensional shape measuring method using the same, and non-contact optical measuring device

Abstract

To provide a shape measuring probe that can perform measurement without a failure of a shape measuring probe even when the probe collides a subject to be measured, and a three-dimensional shape measuring device equipped with the probe.SOLUTION: A shape measuring probe comprises: a probe base part which is equipped with a probe shaft which emits measurement light while rotating and a rotation mechanism which rotates the probe shaft, and supports the probe shaft; a probe holder for mechanically connecting the probe base part and the rotation mechanism; and a pressing mechanism which mechanically connects the probe base part and the probe holder by pressing the probe base part and the probe holder at a predetermined force, where the probe is configured so that a tip position of the probe shaft shifts from a predetermined position as mechanical connection by the pressing mechanism comes off when a predetermined force or more is added to the probe shaft.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shape measuring probe, a three-dimensional shape measuring method using the same, and a non-contact optical measuring device. [Background technology]

[0002] Patent document 1 discloses a technology that enables the probe to be replaced depending on the purpose of the measurement in an apparatus that emits measurement light and irradiates the measurement light onto the object to be measured (workpiece) via a probe attached to a rotating motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-549181 Summary of the Invention [Problem to be solved by the invention]

[0004] When the probe is brought close to the workpiece to measure the shape of the workpiece, the probe may come into contact with the workpiece. If the rotating probe comes into contact with the workpiece, the workpiece and the probe may be damaged. The technology described in Patent Document 1 provides a function for easily attaching and detaching the probe by attaching the probe to a rotating motor using a magnet, but the purpose is to replace the probe depending on the purpose of the measurement, and there is a concern that when the probe collides with the workpiece, the probe may fall off, or when the collision occurs in the axial direction of the probe, a large force is applied to the probe and motor, causing them to break down.

[0005] The present invention has been made in consideration of the above-mentioned points, and has an object to provide a shape measurement probe that can prevent equipment failure even when the probe collides with a workpiece, a three-dimensional shape measurement method using the same, and a non-contact optical measurement device. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention is configured as follows. A shape measurement probe that emits measurement light emitted from a light source towards a measurement object and receives reflected light of the measurement light reflected by the measurement object, the shape measurement probe comprising: a probe shaft that rotates to emit measurement light; and a rotation mechanism that rotates the probe shaft. The shape measurement probe comprises: a probe base that supports the probe shaft; a probe holder for mechanically connecting the probe base and the rotation mechanism; and a pressing mechanism that mechanically connects the probe base and the probe holder by pressing the probe base and the probe holder with a predetermined force, wherein when a force greater than a predetermined force is applied to the probe shaft, the mechanical connection by the pressing mechanism is released, thereby shifting the position of the tip of the probe shaft from a predetermined position. A three-dimensional shape measurement method and a non-contact optical measuring device using the shape measurement probe. Effect of the Invention

[0007] According to the present invention, it is possible to provide a non-contact optical measuring device that is robust against contact and collision with a workpiece.

[0008] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a non-contact optical measuring device. [Diagram 2] FIG. 2 is an enlarged view of the tiltable portion of FIG. [Diagram 3] 13A and 13B are diagrams illustrating another example of a configuration in which a pressure applying mechanism is realized by a spring. [Figure 4] 13A and 13B are diagrams showing the state of a tiltable part when a probe comes into contact with a workpiece to be measured. [Diagram 5] 13A and 13B are diagrams illustrating another example configuration of a kinematic mount. [Figure 6] FIG. 13 is a diagram showing yet another example configuration of a kinematic mount. [Figure 7] 13A-13D show examples of mechanisms for replicating the position of a metrology probe shaft other than a kinematic mounting mechanism; [Figure 8] FIG. 13 is a diagram showing an example of a method for estimating not only the presence or absence of contact but also the method of contact from the outputs of four displacement detectors. [Figure 9] FIG. 13 is a schematic diagram showing an example of a non-contact optical measuring device in the case where a robot is used. [Figure 10] 13 is a schematic diagram showing a position where a pressure applying mechanism for a probe holding mechanism is realized by using a magnet. [Figure 11] 13 is a schematic diagram showing a method for increasing the range of motion of a probe holding mechanism by elastically holding a target ring for a displacement sensor relative to a deformable portion of the probe holding mechanism. FIG. [Figure 12] FIG. 13 is a diagram showing an example of a configuration in which a reflecting mirror / light path switching element is rotated by a small rotating mechanism at the tip of a probe shaft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0011] 1 is a schematic diagram showing an example of a non-contact optical measurement device in the first embodiment. A non-contact optical measurement device 290 in this embodiment has a probe control mechanism 200, connection cables 150, 151, 152, a measurement head 160, and a measurement probe 180.

[0012] Hereinafter, an example of a three-dimensional shape measuring device configured as a non-contact optical measuring device will be described. The probe control mechanism 200 controls a distance measurement light source built into the measuring head 160 to output measuring light to the measuring probe 180. The connection cable 150 has an optical fiber and guides the measuring light to the measuring probe 180. The measuring probe 180 is a device that irradiates a measuring workpiece 301 with the measuring light 300, detects the reflected light from the measuring workpiece 301 with a detector 173, and guides the detected signal to the probe control mechanism 200 via the cable 151.

[0013] Here, a wavelength-swept laser is used as the measurement light, which is split into measurement light and reference light by coupler 171, and the measurement light is guided to circulator 170, passed through it, and a laser is emitted from lens 161 to irradiate measurement workpiece 301. The light reflected by measurement workpiece 301 is again focused by lens 161 and returned to the optical fiber, its direction is changed by circulator 170, and it is combined with the initially split reference light by coupler 172 to cause interference, and is detected by detector 173, resulting in an interference beat with a frequency proportional to the difference between the distance to the measurement workpiece and the length of the reference optical path. This can be analyzed by probe control mechanism 200 to measure the distance.

[0014] Alternatively, if broadband light is used as the measurement light, the same optical path as above is used, and a spectrometer is used as the detector 173, an interference spectrum can be obtained at the detector. Since the period of this interference spectrum is proportional to the difference between the distance to the measurement workpiece 301 and the length of the reference optical path, it is possible to measure the distance by processing this with the probe control mechanism 200.

[0015] The measurement head 160 and the measurement probe 180 include a lens 161, a rotation mechanism 162, an optical path switching element 163, a measurement probe shaft 164, a polarization state control unit 165, a fixed quarter-wave plate 166, and a rotating quarter-wave plate 167. The lens 161 narrows the measurement light output from the probe control mechanism 200 and guided to the connection cable 150, and guides it to the measurement probe shaft 164. The rotation mechanism 162 rotates the optical path switching element 163 around a rotation axis parallel to the measurement light output from the lens 161 using a driving device such as a motor under the control of a distance calculation unit described later.

[0016] The measurement light emitted from the lens 161 is converted into circularly polarized light by a fixed quarter-wave plate 166. The rotation direction of the circularly polarized light is selected by the linear direction controlled by a polarization state control unit 165. This circularly polarized light is converted back into linearly polarized light by a quarter-wave plate 167 that rotates together with the measurement probe shaft 164, but the direction of the axis of 167 relative to the optical path switching element 163 is adjusted in advance so that the direction of this linearly polarized light can be selected to be perpendicular or parallel to the reflecting surface of the optical path switching element 163 depending on the rotation direction of the circularly polarized light.

[0017] The optical path switching element 163 selectively emits light using the measurement light whose polarization direction is controlled by the polarization state control unit 165 and the quarter-wave plates 166 and 167. The optical path switching element 163 has an optical path switching function, and emits light in at least one of a first direction 300a which is the same traveling direction as the traveling direction of the measurement light output from the lens 161, and a second direction 300b which is approximately perpendicular to the first direction 300a. The optical path switching element 163 is, for example, a polarizing beam splitter which selectively emits light according to a change in the polarization direction.

[0018] The measurement probe shaft 164 engages the light path switching element 163 and passes the light emitted from the lens 161. The measurement probe shaft 164 is, for example, cylindrical with an opening downward (first direction 300a) as shown in Fig. 1, and engages the light path switching element 163 at its tip. The measurement probe shaft 164 rotates around a rotation axis parallel to the measurement light output from the lens 161, and the light path switching element 163 rotates as the tip of the measurement probe 164 rotates.

[0019] As another embodiment, when it is not necessary to switch the measurement direction and only measurement in the side direction indicated by 300b is required, a simple reflecting mirror may be used instead of the optical path switching element as 163. In this case, if the variation in the reflection characteristics of the reflecting mirror due to the polarization direction does not pose a problem, the polarization state control unit 165 and the quarter-wave plates 166 and 167 may be omitted.

[0020] The polarization state control unit 165 controls the polarization of the measurement light output from a distance measurement control mechanism (not shown) under the control of the probe control mechanism 200. The polarization state control unit 165 changes, for example, the polarization direction of the measurement light.

[0021] As shown in Figure 1, when the measurement target portion of the measurement workpiece 301 has a cylindrical hole shape, the bottom depth of the hole shape can be measured by using measurement light emitted in a first direction 300a by controlling the polarization by the polarization state control unit 165.

[0022] Furthermore, the light emitted in the second direction 300b from the light path switching element 163 by the polarization control by the polarization state control unit 165 rotates according to the rotation of the light path switching element 163, passes through an opening or a wall surface on the side of the tip of the measurement probe shaft 164, and is irradiated onto the measurement work 301. The light reflected or scattered by the measurement work 301 travels back along the emission path in the same manner as the light emitted in the first direction 300a, and reaches the probe control mechanism 200, and the distance to the measurement work 301 is calculated. By rotating the measurement probe 180 using the measurement light emitted in the second direction 300b, it is possible to measure the shape of a cylindrical side surface, for example.

[0023] Next, we will explain the three-dimensional shape measuring device equipped with the measuring head 160. The measurement workpiece 301 is mounted on a moving mechanism 500 (XYZ stage in this figure), and this allows the measurement workpiece 301 to approach the measurement probe shaft 164 of the measurement head 160 from various positions and directions, and the measurement light 300 is emitted from the measurement probe shaft 164 to measure the shape of the measurement workpiece 301.

[0024] FIG. 1 shows an example of a state in which the shape of a hole 311 formed on a measurement workpiece 301 is measured. In this state, the depth of the bottom of the hole can be measured by controlling the measurement light to be emitted in the direction 300a, and the inner diameter shape of the hole can be measured by controlling the measurement light to be emitted in the direction 300b and rotating the rotation mechanism 162. To achieve this, the overall control device 225 issues a command to the movement mechanism control device 215, which is composed of any one of an XYZ stage controller, a CMM (Coordinate Measurement Machine), a robot controller, etc., to drive the movement mechanism 500 and control the positional relationship between the measurement probe shaft 164 and the measurement workpiece 301 to be in a desired state. Next, the overall control device 225 issues a command to the probe control mechanism 200, and the probe control mechanism 200 measures the shape using the measurement head 160 in the manner already described.

[0025] In this explanation, the measurement work 301 is described as being mounted on the moving mechanism 500 (XYZ stage), but various other configurations are possible as long as it is possible to change the relative positional relationship between the measurement probe shaft 164 and the measurement work 301. For example, the moving mechanism 500 may be an XY stage instead of an XYZ stage, and the vertical relative movement between the measurement probe shaft 164 and the measurement work 301 may be realized by mounting the measurement head 160 on a Z stage (not shown) and driving this.

[0026] It is also possible to use a stage mechanism of a five-axis machining center as the moving mechanism 500, or to hold the measuring head 160 instead of the machining tool of the five-axis machining center and measure the shape of the work before and after machining on the machining device. In this case, the measuring head 160 is mounted on an XYZ stage (not shown), and the measurement work 301 is mounted on the XYZ stage. The stage in this case is a two-axis rotating stage. This makes it possible to approach the measurement probe shaft 164 in any position on the measurement work 301 in any attitude.

[0027] When the relative positions of the measurement probe shaft 164 and the measurement work 301 are moved, contact between the measurement probe shaft 164 and the measurement work 301 or the movement mechanism 500 may occur due to incorrect installation of the measurement work 301, an incorrect shape of the measurement work 301, an incorrect program for the movement mechanism 500, or other errors. Conventionally, when such contact occurred, serious damage was caused to the measurement probe shaft 164 and the measurement head 160, particularly the rotation mechanism 162, making it necessary to replace or repair the entire measurement head 160, which could result in high costs and the inability to perform measurements for a long period of time.

[0028] In view of such problems, the present invention provides a function in which, when contact occurs, a part of the measurement probe 180 reversibly deforms to deflect the force caused by contact between the measurement probe shaft 164 and the measurement workpiece 301, and at the same time detects the contact and stops the moving mechanism 500, thereby keeping the deformation within the range of reversible deformation of the measurement probe 180 and preventing damage to the measurement probe 180, the main body of the measurement head 160, the measurement workpiece 301, etc. Also, if the deformation is large and damage remains in the components of the measurement probe 180, a function is provided in which the measurement probe 180 can be easily repaired at low cost with a short downtime by replacing it with a spare one.

[0029] The measurement probe 180 of the present invention is formed by the following configuration shown in FIG. 1 in addition to the measurement probe shaft 164, the rotating ¼ wavelength plate 167, and the reflecting mirror / optical path switching element 163 already described.

[0030] To explain this part, we will also use Figure 2, which is an enlarged view of the target area in Figure 1.

[0031] First, a description will be given of a portion consisting of a probe attachment portion 187 attached to a rotating mechanism flange portion 189 of the rotating mechanism 162 in the measuring head 160, a column 185 supporting a disk-shaped part of the probe base portion 181 against the probe attachment portion 187, and a mounting screw 186 fixing the measuring head 160 to the rotating mechanism flange portion 189. These parts are integrated with the rotating mechanism 162 by the mounting screw 186 to rotate, and are portions that do not deform when the measurement workpiece 301 and the measuring probe shaft 164 come into contact with each other. The probe shaft portion reversibly displaces in this portion to realize a function of deflecting the force due to contact. Although the column 185 is composed of three columns in the example of FIG. 1, the number of columns may be one or more as long as sufficient strength is maintained.

[0032] Next, the probe shaft portion will be described. The probe base 181 is pressed against the probe holder 184 by a pressure mechanism 183 such as a spring. The center of the probe base 181 is hollow, and the measurement probe shaft 164 is firmly fixed thereto. With this configuration, the measurement probe shaft 164 normally rotates together with the rotation mechanism 162, but when a force due to contact with the measurement probe shaft 164 and the measurement workpiece 301 is applied to the measurement probe shaft 164, the force applied to the pressure mechanism 183 exceeds the pressure, and the probe base 181 floats up from the probe holder 184, and absorbs the force due to contact between the measurement probe shaft 164 and the measurement workpiece 301. When the force due to the contact is eliminated, the probe base 181 is pressed against the probe holder 184 again, and the unity of the rotation mechanism 162 and the measurement probe shaft 164 is restored. In FIG. 1, the pressure applying mechanism is provided at three locations indicated by circles, but the number of locations is not limited to three. For example, as shown in FIG. 3, a spring 183′ is arranged so that the coil surrounds the center of rotation through which the optical path of the measurement light 300 passes, and the probe base 181 is pressed against the probe holder 184. This makes it possible to apply pressure stably without blocking the optical path of the measurement light 300.

[0033] Here, since it is necessary to reproduce the positional relationship between the probe base 181 and the probe holder 184 when the latter is pressed against the latter, the embodiment in FIG. 1 employs a kinematic mount mechanism. A kinematic mount is a mechanism that uniquely determines the six degrees of freedom of the position and orientation of an object by pressing against it, and there are various variations. In FIG. 1, a pair of two approximately parallel rods 182b attached to the probe holder 184 and one ball 182a attached to the probe base 181 (the pair forms one component of the kinematic mount 182) is configured at three locations. By pressing the ball against the parallel rods, the center position of the ball is constrained on a straight line, and two degrees of freedom are determined. By using three sets of such pairs, all six degrees of freedom are determined, and the position and orientation can be reproduced stably with sub-micrometer accuracy.

[0034] The operation of the probe when it comes into contact will be further explained using Fig. 4. Fig. 4(a) is a reprint of the same view as the enlarged view of the tiltable part of the measurement probe 180 in Fig. 3. In contrast, Fig. 4(b) shows a state in which the tip of the measurement probe 180 comes into contact with the measurement workpiece 301 from the side and a force is applied to the right in the figure. In this way, one of the three balls 182a that make up the kinematic mount (the ball on the right in the figure) floats with respect to the rod 182b, and the measurement probe shaft 164 and the probe base 181 rotate counterclockwise, deflecting the force applied to the tip of the measurement probe shaft 164 (not shown) from the left.

[0035] 4(c) is a diagram showing a state in which the measurement workpiece 301 comes into contact with the tip of the measurement probe 180 from below in the figure, and an upward force is applied to the measurement probe shaft 164. In this way, the three balls 182a constituting the kinematic mount float relative to the rod 182b, and the measurement probe shaft 164 and the probe base 181 move upward, deflecting the force applied from below to the tip of the measurement probe shaft 164 (not shown).

[0036] In either case of Figures 4(a) and (b), when the external force acting on the measurement probe shaft 164 is released, the force of the pressure mechanism 183 (a spring is used in this figure) presses the probe base 181 against the probe holder 184, thereby restoring the constraint provided by the kinematic mount and returning the probe to its original position in Figure 4(a).

[0037] There are other possible configurations for the kinematic mount as described with reference to FIG. 3. First, a rod pair may be used on the probe base 181 side and a sphere may be used on the probe holder 184 side. Furthermore, the same purpose can be achieved by forming one pair from two adjacent spheres 182a' and one rod 182b' as shown in FIG. 5. Also, a V-shaped groove may be used instead of two rods. Furthermore, it goes without saying that the same purpose can be achieved by forming each pair from any combination of two rods and a sphere, two spheres and one rod, or one sphere and a V-shaped groove.

[0038] Furthermore, rather than assigning the same type of constraint to each of the three pairs, for example, as shown in FIG. 6, a configuration can be used in which the first pair is configured with a sphere and a bowl-shaped conical shape 182a-1 to constrain the position of three degrees of freedom, the second pair is configured with a sphere 182b and a V-groove shape 182a-2 to constrain two degrees of freedom on a straight line, and the third pair is configured with a sphere and a plane 182a-3 to constrain one degree of freedom on a plane.

[0039] As a configuration other than the kinematic mount mechanism, there is a combination of a fitting cylinder and a flat part, or a combination of a cone shape and a mortar shape, which are described in Fig. 7(a) and (b), respectively. In Fig. 7(a), a low-height protrusion 193 with an obliquely dropped end is formed at the center of the probe base 181. The outer diameter of this protrusion 193 is specified with a fitting tolerance with respect to the inner diameter of the center hole of the probe holder 184, so that the center of rotation is aligned with an accuracy of about 10 micrometers. The height in the vertical direction of the paper is determined by the contact plane of the probe holder 184 and the probe base 181, so that five degrees of freedom other than the probe rotation direction by the rotation mechanism 162 are accurately reproduced. Since the accuracy of the probe rotation direction is not required so much, it may be left as it is, or a key groove and a key-like part may be formed between the probe holder 184 and the probe base 181 to accurately restrict the degree of freedom in the rotation direction.

[0040] 7(b), the contact surface between the probe holder 184 and the probe base 181 is made conical and pressed by the pressure mechanism 183, thereby making it possible to constrain five degrees of freedom other than the direction of probe rotation by the rotation mechanism 162. Since precision in the direction of probe rotation is not required to a great extent, this may be left as is, or a key groove and a key-like part may be formed between the probe holder 184 and the probe base 181 to accurately constrain the degree of freedom in the direction of rotation.

[0041] Finally, the contact detection mechanism of the present invention will be described. The probe base 181 is disk-shaped, and the displacement of the disk-shaped portion of the probe base 181 caused by the contact of the measurement probe shaft 164 with the measurement workpiece 301 is detected by the displacement sensor 190 to detect contact. Displacement detection can be performed in a non-contact manner by any of the following: (1) detection by a change in eddy current generated in the target disk by electromagnetic induction, (2) detection by a change in electrostatic capacitance between the target disk and the displacement sensor 190, (3) magnetizing the target and detecting a change in the magnetic field by the displacement sensor 190, (4) irradiating the target disk with light and detecting the intensity of the reflected / scattered light, (5) triangulation in which light is irradiated onto the target disk and a sensor detects a change in the reflected position due to the target displacement, and (6) measuring the distance to the target by laser interference. A plurality of displacement sensors 190 are arranged so that the distance can be measured at one, two, or preferably three or more points.

[0042] As will be described in detail later with reference to Fig. 8, when the distance between any of the multiple sensors and the probe base 181 becomes closer and falls below a threshold, the contact detection mechanism 199 issues an alarm as contact has occurred, and the moving mechanism control device 215 stops. If three or more displacement sensors 190 are arranged here, the direction of contact can be detected as described below. Even if only one displacement sensor 190 is arranged, if it is arranged so that it can detect the distance close to the center of the probe base 181, no matter in which direction the measurement probe shaft 164 is tilted or displaced in the Z direction, the probe base 181 will always displace in a direction approaching the sensor, making it possible to detect contact of the measurement probe shaft 164.

[0043] Alternatively, as another configuration example, if a sensor that can detect tilt at the same time as displacement is used as the displacement sensor 190, it is possible to detect contact in various directions with high accuracy using one displacement sensor. For example, the sensor may be a sensor that has three built-in laser interferometers and detects tilt and displacement from the difference between these, or a sensor that detects tilt by irradiating a laser and detecting the direction of the laser reflected by a target.

[0044] As described above, the operation when the contact detection mechanism 199 issues a contact detection alarm and the movement mechanism control device 215 stops will be described. To eliminate the contact, the operator issues an instruction to the movement mechanism control device 215 via the overall control device 225 to change the relative position of the measurement workpiece 301 and the measurement probe 180. Depending on the device configuration, an interlock function may be activated and the movement mechanism control device 215 may not respond while the contact detection mechanism 199 is issuing an alarm. In such a device configuration, a switch (not shown) that disables the interlock function is provided in the movement mechanism control device 215, or an interlock release button is provided on the GUI (graphical user interface) of the overall control device 225, providing a function to disable the interlock during the contact elimination operation.

[0045] Since the probe shaft 164 may have been damaged at the time of contact, in a desirable configuration, after the contact is released, the overall control device 225 automatically performs operation check and recalibration, or prompts the operator to perform operation check and recalibration. Using a calibration work (not shown) placed by the operator on the moving mechanism 500, or a calibration work (not shown) that is always fixed to a part of the moving mechanism 500, the relative positions of the measurement probe 180 and the calibration work are changed, and the calibration work is measured with the measurement probe 180. If the contact speed between the probe and the work is excessive, and a large force is applied to the probe shaft 164 before the moving mechanism control device 215 stops, causing irreversible deformation due to plastic deformation or the like, if the deformation is large, the optical path of the measurement light 300 may be blocked, making it difficult to obtain a correct signal. This is judged by the probe control mechanism 200, and the operator is prompted to replace the probe unit 180 via the overall control device 225.

[0046] If the irreversible deformation is minor, for example on the order of a few micrometers, there is no problem with the measurement function, but the measured radius value changes by the amount that the position of the reflecting mirror / optical path switching element 163 at the tip of the probe shaft 164 has changed, resulting in errors in the shape and diameter value of the measurement target portion 311 of the workpiece 301 being measured. By measuring a calibration workpiece, the shape of which is known in advance, it is possible to determine the calibration offset to be added to the radius value to be measured, and to always measure the shape of the measurement workpiece 301 accurately.

[0047] As yet another configuration example, a contact sensor may be used instead of the displacement sensor as the displacement sensor 190 to detect contact between the probe base 181 and the contact sensor due to contact of the measurement probe shaft 164. For example, a contact sensor may be used that detects the internal strain of the displacement sensor due to contact using a strain gauge or a piezoelectric element, or that excites vibration on the surface of the displacement sensor and detects and captures the decrease in the vibration amplitude due to contact as a change in current. Alternatively, a microswitch whose conduction state changes due to contact may be used as the contact sensor. Alternatively, an electrode may be exposed on the surface of the contact sensor, and contact may be detected by a change in electrical resistance due to contact with the probe base 181.

[0048] Furthermore, the rotating mechanism flange portion 189 and the probe mounting portion 187 are formed so that a cylindrical protrusion of the probe mounting portion 187 fits into a cylindrical recess of the rotating mechanism flange portion 189. If the diameters of this cylindrical protrusion and recess are formed with a fitting tolerance, it is possible to assemble the measurement probe 180 to the rotating mechanism 162 with a variation of about 10 micrometers. In this state, the rotating mechanism flange portion 189 and the probe mounting portion 187 of the measurement probe 180 are firmly fixed by tightening the mounting screw 186. With this configuration, even if the measurement probe 180 is damaged, it can be easily replaced with a spare measurement probe 180 prepared in advance.

[0049] Alternatively, instead of a fitting structure, a kinematic mount structure may be formed on the contact surface between the rotating mechanism flange portion 189 and the probe attachment portion 187, and a magnet may be incorporated into either the rotating mechanism flange portion 189 or the probe attachment portion 187, with the other being made of a ferromagnetic material, or magnets may be incorporated into both the rotating mechanism flange portion 189 and the probe attachment portion 187, with the opposing magnetic poles being paired. In this way, attachment screws 186 are not required when replacing the measurement probe, and it becomes possible to attach and detach it with a single touch by using magnetic attraction.

[0050] The embodiment described above makes it possible to provide a function in an apparatus for measuring the three-dimensional shape of a measurement workpiece, which can prevent damage to the measurement head by stopping the moving mechanism while variably deflecting contact between the measurement probe shaft 164 and the measurement workpiece 301. EXAMPLES

[0051] As another embodiment, an apparatus can be configured that does not measure the three-dimensional shape but inspects the appearance condition (for example, scratches on the surface) of the surface of a three-dimensional measurement workpiece. A laser or a high-intensity broadband light source is used as the measurement light, and the measurement light is irradiated onto the measurement workpiece 301 by the lens 161 in FIG. 1, and the light reflected and scattered by the workpiece is again collected by the lens 161, and this is detected by the detector 173 by the circulator 170. In this case, since it is not interference detection, the couplers 171 and 172 used for branching and combining the reference light are not required. By detecting the intensity of the reflection and scattering of the workpiece by the detector 173, it is possible to obtain and analyze an appearance image of the measurement workpiece by the probe control mechanism 200, thereby detecting defects in the measurement workpiece. Alternatively, if a spectrometer is used as the detector 173, the spectrum of the reflected light can be obtained by the probe control mechanism 200, and the distribution of the material on the surface of the measurement workpiece can be analyzed by analyzing this data by the overall control device 225. EXAMPLES

[0052] An embodiment in which a robot is used as the moving mechanism 500 of the measuring head will be described with reference to FIG. 9. In the example of this figure, the robot 500' is a 6-axis articulated robot having six rotary joints A1 to A6. The measuring head 160 is attached to the tip of this robot via a measuring head attachment 501. Then, the overall control device 225 in FIG. 1 controls the robot 500' via the moving mechanism control device 215 to change the relative position and posture of the measuring probe shaft 164 extending from the measuring head 160 and the measuring workpiece 301, making it possible to measure any part of the measuring workpiece 301. The example of FIG. 9 shows a state in which an oblique hole 311 formed in the measuring workpiece 301 is being measured.

[0053] In this way, by utilizing the flexible position and orientation control ability of the robot, it becomes possible to move the measurement head to various locations on the workpiece to perform flexible measurements. Although a six-axis articulated robot is shown in the diagram of this embodiment, it goes without saying that other types of robots, such as SCARA robots and gantry robots, may also be used. EXAMPLES

[0054] An embodiment in which a magnet is used instead of a spring as a pressure mechanism for the probe base will be described using Figure 10. Figure 10 shows the measurement head 160 and measurement probe 180 extracted from Figure 1. Only the parts that differ from Figure 1 will be explained here.

[0055] The probe base 181 is attracted to the probe holder 184 by a magnetic pressure applying mechanism 183a. In this embodiment, the probe holder 184 is made of a ferromagnetic material. The center of the probe base 181 is hollow, and the measurement probe shaft 164 is firmly fixed thereto. With this configuration, the measurement probe shaft 164 normally rotates together with the rotation mechanism 162, but when a force is applied to the measurement probe shaft 164 due to contact with a measurement workpiece 301 or the like, the force applied to the magnet part of the pressure applying mechanism 183a exceeds the magnetic attraction force, and the probe base 181 floats up from the probe holder 184, and absorbs the force due to contact between the measurement probe shaft 164 and the measurement workpiece 301 or the like.

[0056] When the contact force is released, the probe base 181 is attracted to the probe holder 184 again by the magnetic attraction, thereby restoring the unity of the rotation mechanism 162 and the measurement probe shaft 164. If the probe base 181 is far away from the probe holder 184, the attractive force of the magnet 183a on the probe holder 184 becomes weak, and the probe base 181 may not be attracted again stably. In such a case, it is recommended to provide a weak auxiliary spring 183b to push the probe base 181 back toward the probe holder 184.

[0057] In FIG. 10, three pressure mechanisms are provided, but the number of mechanisms is not limited to three. For example, the probe base 181 may be attached to the probe holder 184 with a single annular magnet that surrounds the measurement light 300, i.e., the center of rotation of the rotation mechanism 162, so that stable pressure can be applied without blocking the optical path of the measurement light 300.

[0058] With this configuration, in an apparatus for measuring the three-dimensional shape of a measurement workpiece, it is possible to provide a function that can prevent damage to the measurement head by stopping the moving mechanism while variably deflecting contact between the measurement probe shaft 164 and the measurement workpiece 301. Since the attraction force of the magnet 183a increases rapidly when the distance to the probe holder 184, which is the object to be attracted, is close, it is possible to apply a stable pressure only when the measurement probe shaft 164 is normally not in contact with the measurement workpiece or the like, and to reduce the pressure when contact occurs. EXAMPLES

[0059] Fig. 11 shows an embodiment that makes it possible to extend the tiltable range of the measurement probe shaft 164 by compensating for the operating range of the displacement sensor 190. In Fig. 1, when the measurement probe shaft 164 comes into contact with a measurement workpiece or the like, the contact detection mechanism 199 detects the contact and stops the moving mechanism 500 via the moving mechanism control device 215, but if the moving speed of the moving mechanism 500 is high, it cannot be stopped in time and the tiltable range of the measurement probe shaft 164 is exceeded. In that case, the measurement probe shaft undergoes elastic deformation, but if the elastic deformation range is also exceeded, the measurement probe shaft 164 will undergo irreversible deformation or damage.

[0060] If a small sensor using, for example, eddy current is used as the displacement sensor 190, the detectable range of the displacement of the probe base 181 is, for example, about 1.5 mm. Therefore, if the amount of displacement of the probe base 181 from when the displacement sensor 190 detects contact to when the moving mechanism stops exceeds 1.5 mm, the range in which the measurement probe shaft 164 can be tilted will be exceeded.

[0061] Furthermore, when a contact sensor is used as the displacement sensor 190, the measurement probe shaft 164 has already begun to elastically deform when contact is detected, and it is necessary to stop the moving mechanism 500 before this deformation enters the region of plastic deformation or breakage.

[0062] An embodiment that addresses this issue is shown in Figure 11. The measurement head 160 and measurement probe 180 of Figure 1 are extracted, so only the parts that differ from Figure 1 will be explained.

[0063] In the embodiment of FIG. 11, the displacement of the probe base 181 is not measured by the displacement sensor / contact sensor 190, but instead the displacement of a circular target ring 191 is measured. The target ring 191 is held relative to the probe base 181 via a target ring elastic holding mechanism 192. Normally, the target ring 191 moves integrally with the probe base 181. When the target ring 191 is displaced and comes into contact with the displacement sensor 190 or the surrounding members of the measurement head 160, the target ring elastic holding mechanism 192 elastically deforms and absorbs the large displacement applied to the measurement probe shaft 164. This makes it possible to compensate for the operating range of the proximity sensor 190 and extend the collapsible range of the measurement probe shaft 164. The target ring elastic holding mechanism 192 is preferably provided in three or more places in order to hold the target ring 191 integrally with the probe base 181 under normal conditions.

[0064] For example, a rubber member or a spring may be used as the target ring elastic holding mechanism 192. In particular, when a spring is used, if the measurement head 160 is moved at high speed, the spring may vibrate, causing the target ring 191 to move unnecessarily, which may cause the displacement sensor 190 to malfunction.

[0065] As a preferable embodiment that can solve this problem, it is effective to configure the target ring elastic holding mechanism 192 with three types of members: a hole 194, a pillar 195, and a spring 196. The pillar 195 with a flared end is passed through a hole 194 drilled in the target ring 191, and then through the spring 196, and then fixed to the probe base 181 in a compressed state. Then, the target ring 191 is pressed against the flared part at the end of the pillar 195 by the pressure of the spring 196, and the target ring 191 will not separate from the flared part at the end of the pillar 195 unless the inertial force acting on the target ring 191 due to the movement of the measurement head 160 exceeds this pressure. Furthermore, unless the inertial force acting on target ring 191 due to the left-right movement of measurement head 160 exceeds the static friction force obtained by multiplying the static friction coefficient between the expanded portion at the end of pillar 195 and target ring 191 and the pressure applied by spring 196, target ring 191 will not shift sideways.

[0066] In the figure of this embodiment, pillar 195 is fixed to probe base 181 and hole 194 is opened in target ring 191 through which pillar 195 passes. However, it should be noted that the same effect can be obtained by the opposite method, that is, fixing pillar 195 to target ring 191 and opening hole 194 through which pillar 195 passes in probe base 181.

[0067] In addition, in such a configuration using target ring 191 in addition to probe base 181, since there is no need to make probe base 181 disk-shaped in order to use it as a target for proximity sensor / contact sensor 190 as in Fig. 1, probe base 181 may be shaped with arms extending in three directions, and target ring elastic holding mechanism 192 may be attached to the tip of each arm, as shown in the AA cross section of Fig. 11. In that case, the shape of pillar 185 is not cylindrical, but may be made, for example, fan-shaped with a larger cross-sectional area, as shown in the AA cross section, to increase strength.

[0068] With the configuration of the embodiment described above, it is possible to compensate for the operating range of the proximity sensor 190 and expand the tiltable range of the measurement probe shaft 164. EXAMPLES

[0069] An embodiment in which the rotation mechanism 162 is provided on the measurement probe 180 side, rather than on the measurement head 160 side, will be described with reference to Fig. 12. Only the parts that differ from Fig. 11 will be described.

[0070] As shown in Fig. 12, a small rotating mechanism 162 is disposed at the tip of a measurement probe shaft 164. A reflecting mirror / optical path switching element 163 and, if necessary, a quarter-wave plate 167 are mounted on the hollow rotating shaft of the rotating mechanism 162, and are rotated by the rotating mechanism 162. A probe mounting portion 187 of the measurement probe 180 configured in this manner is attached by a mounting screw 186 to a non-rotating fixed flange portion 189' provided on the measurement head 160 side. The measurement light emitted from the lens 161 passes through the quarter-wave plate 166 and the rotating quarter-wave plate 167 if necessary, and then reaches the rotating reflecting mirror / optical path switching element 163, thereby changing the measurement direction.

[0071] Even with this configuration, in an apparatus for measuring the three-dimensional shape of a measurement workpiece, it is possible to provide a function that can stop the moving mechanism while variably deflecting contact between the measurement probe shaft 164 and the measurement workpiece 301, thereby preventing damage to the measurement head. EXAMPLES

[0072] An embodiment in which not only the presence or absence of contact but also the direction of contact is detected and reflected in the control of the device will be shown using Fig. 8. When using proximity sensors / contact sensors 190 that simply measure distance or contact without detecting the inclination of the target ring 191 or the probe base 181, it has already been explained that it is preferable to use three or more sensors, but Fig. 8 shows an example in which four sensors are used. In this way, four proximity sensors / contact sensors are arranged at 90 degree intervals around the measurement probe shaft 164 relative to the target ring 191 or the disk-shaped probe base 181.

[0073] These sensors are named x+, x-, y+, and y- according to the coordinate system shown in the figure. These outputs are received by a contact detection mechanism 199. In a basic configuration, when any of the x+, x-, y+, and y- sensors detects proximity or contact, the contact detection mechanism 199 determines that the measurement probe shaft 164 has come into contact with a workpiece or the like. In addition, the contact detection mechanism 199 can further determine which sensor is making the detection by analyzing the sensor. The table in Fig. 8 is an example of a judgment table when the number of sensors is four.

[0074] In the table, 1 indicates that each sensor has detected proximity / contact, and 0 indicates that it has not detected it. By referring to this table and reading the corresponding collision direction column, the contact direction of the measurement probe shaft 164 with the measurement workpiece or the like can be determined. In this way, when four sensors are used, in addition to contact in the Z direction, the lateral contact direction can also be determined with a resolution of 45°. For example, doubling the number of sensors improves the angular resolution by a factor of two.

[0075] Furthermore, if the proximity sensor is capable of measuring the distance to the target 181 / 191, rather than simply whether the target is farther than a reference distance, by using three or more proximity sensors 190, the amount of tilt, direction of tilt, and displacement in the Z direction of the target 181 / 191 can be quantitatively determined by calculation within the contact detection mechanism 199.

[0076] As described above, since the contact direction of the measurement probe shaft 164 can be known by the contact detection mechanism 199, it becomes possible for the moving mechanism control device 215 to automatically drive the moving mechanism 500 in the direction to eliminate this contact. Alternatively, by showing this information to the operator by the overall control device 225, it becomes possible to utilize this information for manual operation by the operator to eliminate the contact. <Additional Notes> A force is applied to the probe base by a spring or magnet in the direction in which the probe moves away from the probe rotation motor, and the probe base is pressed against a holding surface such as a kinematic mount. The holding surface rotates together with the rotation motor. As a result, when a force is applied to the probe tip due to a collision with a workpiece, the force is released by separating the holding surface and the probe base, and when the force is removed, the probe base is pressed against the holding surface again, so that the probe returns to its original state reversibly with good reproducibility. Furthermore, a collision can be detected by detecting the displacement of the probe with a sensor, and the operation of the movement mechanism for the relative position of the probe and the workpiece can be stopped to prevent equipment failure. This makes it possible to provide a non-contact optical measuring device that is robust against contact and collision with the workpiece. [Explanation of symbols]

[0077] 150: optical fiber connection cable, 151: detector connection cable, 152: proximity sensor connection cable, 160: measurement head, 161: lens, 162: rotation mechanism, 163: reflecting mirror / light path switching element, 164: measurement probe shaft, 165: polarization state control section, 166: fixed 1 / 4 wave plate, 167: rotating 1 / 4 wave plate, 170: circulator, 171: coupler, 172: coupler, 173: detector, 180: measurement probe, 181: probe base, 182: kinematic mount, 183: pressure mechanism (spring), 183a: pressure mechanism (magnet), 183b: pressure mechanism (auxiliary spring), 184: probe holder , 185: pillar, 186: mounting screw, 187: probe mounting portion, 189: rotation mechanism flange portion, 190: displacement sensor / contact sensor, 191: target ring, 192: target ring elastic holding mechanism, 193: fitting protrusion portion of probe base, 194: hole, 195: pillar, 196: spring, 199: contact detection mechanism, 200: probe control mechanism, 215: moving mechanism control device, 225: overall control device, 300: measurement light, 300a: measurement light facing in a first direction, 300b: measurement light facing in a second direction, 301: measurement workpiece, 311: narrow portion / hole portion, 500: moving mechanism, 500': robot, 501: measurement head attachment.

Claims

1. A shape measuring probe that emits measurement light emitted from a light source toward a measurement object and receives reflected light of the measurement light reflected by the measurement object, a probe shaft that rotates to emit the measurement light; A rotation mechanism that rotates the probe shaft; Equipped with a probe base supporting the probe shaft; a probe holder for mechanically connecting the probe base and the rotation mechanism; a pressing mechanism that mechanically connects the probe base and the probe holder by pressing the probe base and the probe holder with a predetermined force, A shape measurement probe characterized in that, when a force greater than the predetermined force is applied to the probe shaft, the mechanical connection by the pressing mechanism is released, causing the tip position of the probe shaft to shift from a predetermined position.

2. 2. The shape measuring probe according to claim 1, 11. A shape measuring probe, comprising: a pressing mechanism that applies pressure by using at least one of an elastic force of an elastic body and an attractive force of a magnet.

3. 2. The shape measuring probe according to claim 1, A shape measurement probe characterized in that the rotation mechanism and the probe holder are mechanically connected by at least one of a kinematic mounting mechanism, a combination of a mating cylinder and a flat portion, or a combination of a conical shape and a mortar shape.

4. 2. The shape measuring probe according to claim 1, The shape measuring probe, wherein the probe holder is attached to the rotation mechanism by a fitting structure or a kinematic mounting mechanism, by being screwed or pressed by elastic force or magnetic force.

5. 2. The shape measuring probe according to claim 1, A shape measuring probe comprising a detection mechanism for detecting when a force equal to or greater than the predetermined value is applied to the probe shaft.

6. 6. The shape measuring probe according to claim 5, A shape measuring probe, characterized in that the detection mechanism is a displacement detection sensor that detects a displacement of the relative position of the probe shaft and the rotation mechanism.

7. 7. The shape measuring probe according to claim 6, 13. A shape measuring probe, comprising: a probe shaft having a rotating portion and a displacement detection sensor for detecting a displacement of the rotating probe shaft by a non-rotating displacement detection sensor.

8. 7. The shape measuring probe according to claim 6, The displacement detection sensor is either (a) a sensor that detects distance or inclination non-contact by any of the following means: electromagnetic induction, capacitance, magnetic field, light intensity, laser triangulation, or laser interference; or (b) a contact sensor that detects contact due to displacement as a change in current, detects strain due to contact with a strain gauge, a piezoelectric element, or captures it as a decrease in vibration amplitude.

9. The shape measuring probe according to any one of claims 1 to 8, A shape measuring probe characterized in that the measurement light is a wavelength swept laser, and the distance between the tip of the probe shaft and the object to be measured is measured based on an interference beat between the measurement light and the reflected light, and the three-dimensional shape of the object to be measured is measured.

10. The shape measuring probe according to any one of claims 1 to 8, A shape measuring probe characterized in that the measurement light is broadband light, and the distance between the tip of the probe shaft and the object to be measured is measured based on the interference spectrum of the measurement light and the reflected light, and the three-dimensional shape of the object to be measured is measured.

11. The shape measuring probe according to any one of claims 1 to 8, The measurement light is a laser or a high-intensity broadband light source, A shape measuring probe comprising: a defect detection mechanism that acquires an appearance image of the measurement object based on the intensity of reflection / scattering of the reflected light, and detects defects in the measurement object.

12. A non-contact optical measuring device equipped with the shape measuring probe according to any one of claims 6 to 8, a display mechanism for detecting a contact direction between the object to be measured and the probe shaft by comparing detection values ​​of the plurality of displacement detection sensors and displaying a moving direction of the probe shaft to prevent the probe shaft from contacting the object to be measured.

13. A non-contact optical measuring device equipped with the shape measuring probe according to any one of claims 6 to 8, a contact direction between the object to be measured and the probe shaft by comparing detection values ​​of the plurality of displacement detection sensors; and a moving mechanism for moving the probe shaft so that the probe shaft does not come into contact with the object to be measured.

14. 14. The non-contact optical measurement device according to claim 13, The non-contact optical measuring device may be a CMM (Coordinate Measurement Machine), a multi-axis robot, or a multi-axis stage.

15. A method for measuring a three-dimensional shape of a measurement object, comprising using the shape measuring probe according to any one of claims 1 to 8.

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