Non-contact shape measuring apparatus and position adjusting method

Abstract

Provided are: a sensor head (20); a light-receiving sensor (36) in which an incident position of reflected light (LA) on a light-receiving surface (36a) changes in accordance with the distance between the sensor head (20) and a measurement surface (Wa); a distance measurement unit (46) that measures the distance on the basis of the incident position of the reflected light (LA) on the light-receiving surface (36a); and a movement mechanism (C-axis movement mechanism (16)) that moves the sensor head (20) or the measurement surface (Wa) toward or away from the other along a movement axis (C-axis (14)). A measurement range (WR) is determined in advance at a position separated from the sensor head (20) in the emission direction of measurement light (L), and the light-receiving surface (36a) has a size at which the reflected light (LA) can be received even when the sensor head (20) or the measurement surface (Wa) is brought close to the other by the movement mechanism up to a position at which the measurement surface (Wa) is included within a proximity range (SR).

Description

Non-contact shape measuring device and position adjustment method

[0001] The present invention relates to a non-contact shape measuring instrument that measures the shape of a measurement surface in a non-contact manner, and a position adjustment method used in this non-contact shape measuring instrument.

[0002] There are known surface profile measuring machines that measure the shape, such as the contour shape and surface roughness, of a measurement surface of a workpiece (object to be measured). In such surface profile measuring machines, a contactor is brought into contact with the measurement surface and the workpiece is moved relative to each other in the horizontal direction, and the contactor traces the measurement surface while a sensor head detects displacement due to the oscillation of the contactor, and the surface profile of the measurement surface is measured based on a displacement detection signal output from the sensor head (see Patent Document 1).

[0003] In recent years, non-contact surface profile measuring instruments have become popular. Instead of contacting a contactor with the surface, these instruments measure the profile of a measurement surface by horizontally moving a sensor head, which can measure the distance to the measurement surface without contact, relative to the workpiece (see Patent Document 2). The non-contact sensor head measures the distance to the measurement surface using, for example, triangulation. Specifically, the sensor head emits measurement light toward the measurement surface, and the light reflected by the measurement surface is received by a light-receiving sensor in the sensor head. Since the incident position of the reflected light on the light-receiving surface of the light-receiving sensor changes depending on the distance between the sensor head and the measurement surface, the distance between the sensor head and the measurement surface can be measured based on the incident position of the reflected light on the light-receiving surface.

[0004] JP 2017-161548 A JP 2011-196763 A

[0005] 20 is an explanatory diagram for explaining the adjustment of the height position in the Z direction of the sensor head 100 before performing non-contact measurement of the measurement surface Wa of the workpiece W with the non-contact shape measuring machine. Of the mutually orthogonal X, Y, and Z directions in the figure, the X and Y directions are parallel to the horizontal direction, and the Z direction is an up-down direction perpendicular to the horizontal direction. The X direction is the movement direction (scanning direction) of the sensor head 100, and is the emission direction of the measurement light L emitted from the sensor head 100 from below in the Z direction.

[0006] 20 , the measurement range WR within which the shape of the measurement surface Wa can be measured when the sensor head 100 is moved in the X direction is spaced downward in the Z direction from the sensor head 100 when viewed from the Y direction. Therefore, as shown by the reference symbol XXA in Fig. 20 , when measuring the shape of the measurement surface Wa including the recess 102, if the position of the sensor head 100 in the Z direction is adjusted so that the measurement surface Wa is located at the center of the measurement range WR in the Z direction, the lowest point of the recess 102 will not be included in the measurement range WR.

[0007] Therefore, as shown by symbol XXB in Figure 20, the sensor head 100 is pressed toward the measurement surface Wa so that the lowest point of the recess 102 is included in the measurement range WR, and the Z-direction position of the sensor head 100 is adjusted to bring the sensor head 100 as close as possible to the measurement surface Wa.

[0008] When performing such Z-direction position adjustment of the sensor head 100, it is necessary to prevent damage to the sensor head 100 and the workpiece W by avoiding collision or contact of the sensor head 100 with the measurement surface Wa. For this reason, a method is known in which a piezoelectric sensor is provided on the underside of the sensor head 100, and the sensor head 100 is lowered downward in the Z direction until it comes into contact with the measurement surface Wa based on the signal output by the piezoelectric sensor. Also known is a method in which, instead of providing a piezoelectric sensor on the underside of the sensor head 100, a distance measuring sensor that measures the distance to the measurement surface Wa is separately provided in the sensor head 100, and the sensor head 100 is brought as close as possible to the measurement surface Wa based on the measurement results of the distance measuring sensor.

[0009] However, with the method of providing a piezoelectric sensor on the underside of the sensor head 100, the sensor head 100 cannot be brought close to the measurement surface Wa at a distance (working distance) shorter than the thickness of the piezoelectric sensor. Another problem is that it is tedious to manage the wiring extending from the piezoelectric sensor. Furthermore, since the piezoelectric sensor will eventually come into contact with the measurement surface Wa, damage to the sensor head 100 and the measurement surface Wa (workpiece W) cannot be reduced to zero. Furthermore, the piezoelectric sensor has a finite size, which effectively reduces the working distance. Furthermore, the wiring of the piezoelectric sensor is prone to picking up vibrations, which can cause measurement noise.

[0010] Furthermore, in the method of separately providing a distance measurement sensor in the sensor head 100, if a low-cost sensor (e.g., an ultrasonic sensor) is used as the distance measurement sensor, the measurement accuracy of the distance measurement sensor will be low, making it impossible to bring the sensor head 100 as close as possible to the measurement surface Wa. Conversely, if a high-precision sensor is used as the distance measurement sensor, manufacturing costs will increase. Furthermore, since the measurement axis of the sensor head 100 and the measurement axis of the distance measurement sensor are different, if the measurement surface Wa has an uneven shape, it is difficult to adjust the Z-direction position of the sensor head 100 so that the lowest point of the recess 102 is included in the measurement range WR. Furthermore, since the measurement axis of the distance measurement sensor is different from the measurement axis of the sensor head 100, it is not possible to handle cases such as small workpieces W.

[0011] The present invention has been made in view of the above circumstances, and aims to provide a non-contact shape measuring instrument that can bring one of the sensor head and the measurement surface close to the other at low cost and with high precision, and a position adjustment method used in this non-contact shape measuring instrument.

[0012] A non-contact shape measuring machine for achieving the object of the present invention comprises a sensor head that emits measurement light toward a measurement surface and onto which the reflected light of the measurement light reflected by the measurement surface enters; a light receiving sensor having a light receiving surface that receives the reflected light that enters the sensor head, and in which the incident position of the reflected light on the light receiving surface changes depending on the distance between the sensor head and the measurement surface; a distance measurement unit that measures the distance based on the incident position of the reflected light on the light receiving surface; and a moving mechanism that moves one of the sensor head and the measurement surface toward and away from the other along a predetermined moving axis, wherein a measurement range for measuring the distance in the emission direction is predetermined at a position away from the sensor head in the emission direction of the measurement light, and when the range between the sensor head and the measurement range is defined as the proximity range, the light receiving surface is large enough to receive the reflected light even when the other is moved toward one side by the moving mechanism to a position where the measurement surface is included in the proximity range.

[0013] According to this non-contact shape measuring instrument, by making a part of the light receiving sensor function as a proximity sensor, it is possible to detect the approach of one of the sensor head and the measurement surface to the other.

[0014] In a non-contact shape measuring instrument according to another aspect of the present invention, reflected light that is reflected in a direction different from the incident direction of the measurement light from the measurement surface is incident on the sensor head.

[0015] In a non-contact shape measuring instrument according to another aspect of the present invention, the measurement light emitted from the sensor head and the reflected light incident on the sensor head are coaxial.

[0016] A non-contact shape measuring instrument according to another aspect of the present invention includes a position adjustment unit that drives a movement mechanism to bring one sensor head closer to the other sensor, and a movement amount calculation unit that calculates the amount of movement of the other sensor needed to bring the other sensor head closest to the one sensor within the measurement range after the measurement surface reaches the measurement range while the other sensor head is approaching the one sensor, where the position adjustment unit drives the movement mechanism to bring the other sensor head closer to the one sensor by the movement amount after the measurement surface reaches the measurement range while the other sensor head is approaching the one sensor, based on the result of reception of reflected light by the light receiving sensor. This allows the sensor head to automatically bring the sensor head as close to the measurement surface as possible.

[0017] In a non-contact shape measuring instrument according to another aspect of the present invention, the position adjustment unit stops driving the movement mechanism when the light receiving sensor is no longer able to receive reflected light after the measurement surface has reached the measurement range, thereby preventing contact between the sensor head and the measurement surface.

[0018] In another aspect of the present invention, a non-contact shape measuring instrument includes a proximity determination unit that determines whether one of the sensor head and the measurement surface has approached to a position where the other is included in the proximity range based on the voltage value of the light-receiving signal, and the voltage value of the light-receiving signal output from the light-receiving sensor varies depending on the incident position of the reflected light on the light-receiving surface. This makes it possible to detect the approach of the other of the sensor head and the measurement surface based on the voltage value of the light-receiving signal.

[0019] In a non-contact shape measuring instrument according to another aspect of the present invention, the movement axis is parallel to the vertical direction.

[0020] A position adjustment method for achieving the object of the present invention is a position adjustment method for adjusting the position of the other side along the movement axis in the above-mentioned non-contact shape measuring machine, and includes: a first approaching step of bringing the other side closer to the one side using a movement mechanism; a first stopping step of stopping the first approaching step at a position where the measurement surface is included in the measurement range based on the result of receiving reflected light by the light receiving sensor during execution of the first approaching step; a second approaching step of bringing the other side further closer to the one side using the movement mechanism after the first stopping step; a signal outputting step of outputting a proximity signal indicating the approach of the other side to the one side when the other side approaches the one side to a position where the measurement surface is included in the proximity range based on the result of receiving reflected light by the light receiving sensor during execution of the second approaching step; a separating step of moving the other side away from the one side using the movement mechanism when the signal outputting step has been executed; and a second stopping step of stopping the separating step when the measurement surface reaches the measurement range based on the result of receiving reflected light by the light receiving sensor during execution of the separating step.

[0021] According to this position adjustment method, the sensor head can be brought as close as possible to the measurement surface.

[0022] In a position adjustment method according to another aspect of the present invention, in the first approaching step, the other is moved at a higher speed than in the second approaching step or the separating step, thereby shortening the time required for position adjustment.

[0023] The present invention enables one of the sensor head and the measurement surface to be brought closer to the other at low cost and with high precision.

[0024] 14 is a schematic diagram of a surface profile measuring machine according to a first embodiment; FIG. 15 is a schematic diagram of a sensor head according to the first embodiment; FIG. 16 is an explanatory diagram for explaining a measurement range of the sensor head; FIG. 17 is an explanatory diagram for explaining a head position range indicating the range of height positions of the sensor head in the Z direction allowed when measuring the profile of the measurement surface; FIG. 18 is a diagram showing a state in which the sensor head is brought closer to the measurement surface beyond the head position range shown in FIG. 4; FIG. 19 is an explanatory diagram for explaining a light-receiving sensor of the sensor head; FIG. 19 is a functional block diagram of a control device according to the first embodiment; FIG. 19 is a flowchart showing the flow of processing for measuring the profile of the measurement surface of a workpiece by the surface profile measuring machine according to the first embodiment; FIG. 19 is a flowchart showing the flow of processing for adjusting the height position of the sensor head in FIG. 8; FIG. 19 is an explanatory diagram for explaining processing for adjusting the height position of the sensor head; FIG. 19 is a functional block diagram of a control device of a surface profile measuring machine according to a second embodiment; FIG. 19 is an explanatory diagram for explaining the amount of movement calculated by a movement amount calculation unit; FIG. 19 is a flowchart showing the flow of processing for adjusting the height position of the sensor head in the surface profile measuring machine according to the second embodiment; FIG. 19 is an explanatory diagram for explaining processing for adjusting the height position of the sensor head in the surface profile measuring machine according to the second embodiment; FIG. 17 is an explanatory diagram for explaining a first light-receiving region and a second light-receiving region on a light-receiving surface of a light-receiving sensor that receives reflected light incident on a color confocal sensor head. FIG. 18 is an explanatory diagram for explaining in detail the second light-receiving region explained in FIG. 16. FIG. 19 is an explanatory diagram for explaining a method of approach determination by the approach determination unit of the fourth embodiment. FIG. 19 is an explanatory diagram for explaining modified examples of the surface shape measuring machine of each of the above embodiments. FIG. 20 is an explanatory diagram for explaining adjustment of the height position in the Z direction of the sensor head before performing non-contact measurement of the measurement surface of a workpiece with a non-contact shape measuring machine.

[0025] [First Embodiment] Figure 1 is a schematic diagram of a surface profile measuring machine 10 according to a first embodiment, which corresponds to a non-contact profile measuring machine of the present invention. As shown in Figure 1, the surface profile measuring machine 10 performs non-contact measurement of the profile of a measurement surface Wa of a workpiece W, specifically, the contour profile or surface roughness, etc. Note that, among the mutually orthogonal X, Y, and Z directions in the figure, the X and Y directions are planes parallel to the horizontal direction, and the Z direction is an up-down direction perpendicular to the horizontal direction. The Z direction is also a direction parallel (including approximately parallel, the same applies hereinafter) to the movement axis of the present invention.

[0026] The surface profile measuring instrument 10 includes a measuring table 12 , a C-axis 14 , a C-axis moving mechanism 16 , a holder 18 , a sensor head 20 , an operation unit 22 , a monitor 24 , and a control device 26 .

[0027] The measuring table 12 is substantially flat and has an upper surface parallel to the XY plane. A workpiece W is set on the upper surface of the measuring table 12, and a C-axis 14 is also provided on the upper surface of the measuring table 12.

[0028] The C-axis 14 corresponds to the movement axis of the present invention, and is a column extending in the Z direction (upward) from the upper surface of the measurement table 12. A holder 18 is attached to the C-axis 14 via a C-axis movement mechanism 16 so as to be freely movable in the Z direction.

[0029] The C-axis moving mechanism 16 adjusts the position of the sensor head 20 in the Z direction (adjusts the height position) by moving the holder 18 along the C-axis 14, i.e., in the Z direction. This makes it possible to adjust the distance between the sensor head 20 and the measurement surface Wa. In this case, the sensor head 20 corresponds to the "other" of the present invention, and the measurement surface Wa corresponds to the "one" of the present invention.

[0030] The C-axis moving mechanism 16 is a known actuator that moves the holder 18 along the C-axis 14 (Z direction). The C-axis moving mechanism 16 automatically moves the holder 18 in the Z direction under the control of a control device 26 (described later), or moves the holder 18 in the Z direction in response to an operator's operation (manual movement operation) of an elevation lever 22a (see FIG. 7). Note that the manual movement operation of the holder 18 may be performed using a known operating member other than the elevation lever 22a.

[0031] As shown in FIG. 7 , the holder 18 includes an X-axis moving mechanism 18a and an X-position detection sensor 18b. The X-axis moving mechanism 18a is a known actuator that holds the sensor head 20 movably in the X direction under the control of a control device 26 (described later). Driving the X-axis moving mechanism 18a moves the sensor head 20 in the X direction relative to the workpiece W (measurement surface Wa). The X-position detection sensor 18b, which is not shown in the figure, is composed of a linear scale and its reading head, etc., and detects the X-axis position of the sensor head 20 and outputs the detection result to the control device 26. The X-axis moving mechanism 18a and the X-position detection sensor 18b are not limited to the above-described configurations. For example, a stepping motor can be used as the drive source for the X-axis moving mechanism 18a. In this case, the X-position detection sensor 18b can detect the position based on the number of drive pulses of the stepping motor.

[0032] The sensor head 20 is a detector (distance measuring sensor) used to measure the distance to the measurement surface Wa by triangulation (non-contact distance measurement). The sensor head 20 emits measurement light L toward the measurement surface Wa located below it in the Z direction and receives reflected light LA ​​of the measurement light L reflected by the measurement surface Wa. Therefore, in this embodiment, the downward Z direction is the emission direction of the measurement light L from the sensor head 20. The configuration of this sensor head 20 will be described later (see FIG. 2). The measurement surface Wa can be scanned along the X direction with the measurement light L by moving the sensor head 20 in the X direction using an X-axis movement mechanism 18a (see FIG. 7).

[0033] The operation unit 22 uses, for example, a keyboard, a mouse, an operation panel, and operation buttons, and receives input of various operations by an operator. The operation unit 22 also includes a lift lever 22a that allows the operator to manually operate the C-axis movement mechanism 16 (see FIG. 7).

[0034] Various displays such as a known liquid crystal display may be used as the monitor 24. The monitor 24 displays the shape measurement results of the measurement surface Wa by the surface profile measuring instrument 10, various setting screens of the surface profile measuring instrument 10, various operation screens of the surface profile measuring instrument 10, etc.

[0035] The control device 26 is connected to the C-axis moving mechanism 16, the holder 18, the sensor head 20, the operation unit 22, and the monitor 24. The control device 26 comprehensively controls the operation of each part of the surface profile measuring instrument 10 in response to input operations to the operation unit 22.

[0036] Fig. 2 is a schematic diagram of the sensor head 20 according to the first embodiment. As shown in Fig. 2, the sensor head 20 includes a light source 30, a light incident / exit surface 32, a lens 34, and a light receiving sensor 36. The light source 30 emits measurement light L downward in the Z direction.

[0037] The light incident / exit surface 32 is a bottom surface facing the measurement surface Wa in the lower Z direction and has a light exit window 32a and a light entrance window 32b. The light exit window 32a is formed in the light incident / exit surface 32 at a position below the light source 30 in the Z direction, and allows the measurement light L emitted from the light source 30 to pass through and exit the measurement light L toward the measurement surface Wa. The light entrance window 32b is formed in a position shifted in the X direction from the light exit window 32a in the light incident / exit surface 32. Reflected light LA ​​reflected from the measurement surface Wa in a direction different from the incident direction of the measurement light L enters the light entrance window 32b.

[0038] The light entrance window 32b is formed to have a larger width in the X direction than the light exit window 32a in response to changes in the incident position and incident angle of the reflected light LA ​​with respect to the light entrance / exit surface 32 depending on the distance between the sensor head 20 and the measurement surface Wa (see FIG. 6). The light exit window 32a and the light entrance window 32b may also be openings.

[0039] The lens 34 transmits the reflected light LA ​​incident from the light entrance window 32 b and emits the reflected light LA ​​toward the light receiving surface 36 a of the light receiving sensor 36 .

[0040] The light-receiving sensor 36 is, for example, a one-dimensional or two-dimensional imaging element of the CCD (Charge Coupled Device) type or the CMOS (Complementary Metal-Oxide-Semiconductor) type, and has a light-receiving surface 36a that receives reflected light LA ​​incident from the measurement surface Wa through the light entrance window 32b and the lens 34. In the triangulation-type sensor head 20, the incident position of the reflected light LA ​​on the light-receiving surface 36a changes depending on the distance between the sensor head 20 and the measurement surface Wa in the emission direction of the measurement light L (here, the Z direction). This makes it possible to measure the distance between the sensor head 20 and the measurement surface Wa based on the incident position of the reflected light LA ​​on the light-receiving surface 36a.

[0041] 3 is an explanatory diagram illustrating the measurement range WR of the sensor head 20. As described above, in a triangulation-type sensor head 20, the incident position of the reflected light LA ​​on the light-receiving surface 36a changes depending on the distance between the sensor head 20 and the measurement surface Wa. Therefore, a measurement range WR in the Z direction (hereinafter simply referred to as the measurement range WR) within which the distance to the measurement surface Wa can be accurately measured is determined in advance for each type of sensor head 20 depending on the size of the light-receiving surface 36a. This measurement range WR is determined at a position spaced downward in the Z direction from the sensor head 20. Therefore, a proximity range SR is provided between the sensor head 20 (light incident / exit surface 32) and the measurement range WR, which is closer to the sensor head 20 than the measurement range WR.

[0042] In the sensor head 20, a lens (not shown) is generally inserted between the light source 30 and the light exit window 32a to narrow the spot diameter of the measurement light L, but if a lens with a short focal length is used to improve the lateral resolution of the sensor head 20, the spot diameter will be larger on the side closer to the sensor head 20. For this reason, a range that is not very suitable for measurements that require the lateral resolution of the sensor head 20 may be assigned to the proximity range SR.

[0043] Fig. 4 is an explanatory diagram for explaining the head position range MR, which indicates the range of height positions in the Z direction of the sensor head 20 that are permissible when measuring the shape of the measurement surface Wa. Fig. 5 is a diagram showing a state in which the sensor head 20 has approached the measurement surface Wa beyond the head position range MR shown in Fig. 4.

[0044] 4, when measuring the shape of the measurement surface Wa, the C-axis moving mechanism 16 adjusts the height position of the sensor head 20 in the Z direction so that the measurement surface Wa is included within the measurement range WR of the sensor head 20, i.e., between the lower limit (see reference numeral 4A in FIG. 4) and the upper limit (see reference numeral 4B in FIG. 4) in the Z direction. Specifically, the C-axis moving mechanism 16 adjusts the height position of the sensor head 20 (here, the light incident / exit surface 32) in the Z direction to within the head position range MR, which is a positional range such that the measurement surface Wa is included within the measurement range WR.

[0045] 20, the measurement surface Wa may have a recess 102. For this reason, when measuring the shape of the measurement surface Wa, it is preferable to move the sensor head 20 as close as possible to the measurement surface Wa, up to a height position (hereinafter referred to as the target height position H1) where the upper limit of the measurement range WR reaches the measurement surface Wa as viewed from the Y direction side, as shown by reference numeral 4B in FIG.

[0046] In this embodiment, in order to bring the sensor head 20 as close as possible to the measurement surface Wa, the sensor head 20 is first brought close to the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR as shown in Fig. 5. Next, the sensor head 20 is moved upward in the Z direction away from the measurement surface Wa, thereby adjusting the position of the sensor head 20 to the target height position H1 indicated by reference symbol 4B in Fig. 4.

[0047] When the sensor head 20 is brought close to the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR in this way, it is necessary to be able to detect the measurement surface Wa even within the proximity range SR in order to avoid contact of the sensor head 20 with the measurement surface Wa. In this case, providing the sensor head 20 with a piezoelectric sensor or a distance measuring sensor would cause problems in terms of accuracy and cost.

[0048] Therefore, in this embodiment, the size of the light receiving sensor 36 (light receiving surface 36a) of the sensor head 20 is adjusted (enlarged compared to conventional sizes) so that the measurement surface Wa can be detected even within the proximity range SR (see FIG. 6).

[0049] 6 is an explanatory diagram for explaining the light-receiving sensor 36 of the sensor head 20. Note that symbols A1 and A2 in the figure indicate the measurement surface Wa located within the measurement range WR, and symbol B in the figure indicates the measurement surface Wa located within the proximity range SR.

[0050] 6, the light-receiving surface 36a of the light-receiving sensor 36 is large enough to receive not only the reflected light LA ​​reflected by the measurement surface Wa (see symbols A1 and A2) within the measurement range WR, but also the reflected light LA ​​reflected by the measurement surface Wa (see symbol B) within the proximity range SR. Therefore, the light-receiving surface 36a includes a first light-receiving region E1 that receives the reflected light LA ​​from the measurement surface Wa within the measurement range WR, and a second light-receiving region E2 that receives the reflected light LA ​​from the measurement surface Wa within the proximity range SR. This second light-receiving region E2 functions as a proximity sensor that can detect the measurement surface Wa within the proximity range SR.

[0051] In this way, by allocating a portion of the light receiving sensor 36 (light receiving surface 36a) as a proximity sensor, the sensor head 20 can detect when the sensor head 20 has approached the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR without the need to install a piezoelectric sensor, a distance measuring sensor, etc.

[0052] FIG. 7 is a functional block diagram of the control device 26 according to the first embodiment. As shown in FIG. 7, the control device 26 includes an arithmetic circuit configured with various processors, memories, and the like. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). The various functions of the control device 26 may be implemented by a single processor or by multiple processors of the same or different types.

[0053] The control device 26 functions as a height position adjustment unit 40, an approach determination unit 42, an adjustment completion determination unit 43, a shape measurement control unit 44, a distance measurement unit 46, and a shape calculation unit 48 by executing a control program read from a memory unit not shown.

[0054] The height position adjustment unit 40 operates before the start of shape measurement of the measurement surface Wa and performs part of the height position adjustment process to adjust the height position of the sensor head 20 in the Z direction to the target height position H1 (see symbol 4B in Figure 4).

[0055] Here, the height position adjustment process of the sensor head 20 can be broadly divided into a first position adjustment process, a second position adjustment process, and a third position adjustment process. The first position adjustment process is a process of moving the sensor head 20 downward in the Z direction from an initial position above the measurement surface Wa in the Z direction to a position where the measurement surface Wa is included within the measurement range WR. The second position adjustment process is a process of further moving the sensor head 20 downward in the Z direction to a position where the measurement surface Wa is included within the proximity range SR. The third position adjustment process is a process of moving the sensor head 20 upward in the Z direction to the target height position H1. The height position adjustment unit 40 of the first embodiment drives the C-axis movement mechanism 16 to perform only the first position adjustment process. Note that the second and third position adjustment processes are performed by the operator operating the lift lever 22a to drive the C-axis movement mechanism 16, i.e., by manual movement operation.

[0056] The height position adjustment unit 40 is activated to perform a first position adjustment process when an operation to start adjusting the height position of the sensor head 20 is performed using the operation unit 22. The height position adjustment unit 40 drives the C-axis movement mechanism 16 to move the sensor head 20 downward in the Z direction along the C-axis 14. Then, based on the light reception result (light reception position) of the reflected light LA ​​at the first light reception area E1 of the light reception surface 36a of the light receiving sensor 36, the height position adjustment unit 40 stops the movement of the sensor head 20 by the C-axis movement mechanism 16 when the sensor head 20 reaches a position that includes the measurement surface Wa within the measurement range WR, for example, when the center position of the measurement range WR in the Z direction reaches the measurement surface Wa. This completes the first position adjustment process. Thereafter, the second position adjustment process and the third position adjustment process are performed by manual movement operations by the operator (see FIG. 9 ).

[0057] The movement of the sensor head 20 in the first position adjustment process is performed at a higher speed than the movement of the sensor head 20 in the second position adjustment process and the third position adjustment process, which are performed by manual movement operations.

[0058] The approach determination unit 42 is connected to the sensor head 20 (light receiving sensor 36) via, for example, a known communication line (Ethernet, RS232C, etc.). The approach determination unit 42 operates when the second position adjustment process is started by a manual movement operation by the operator, and determines whether the sensor head 20 has approached the measurement surface Wa to a position where the measurement surface Wa is included in the proximity range SR during the execution of this second position adjustment process.

[0059] Specifically, when the sensor head 20 approaches the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR, the reflected light LA ​​is incident on the second light-receiving region E2 of the light-receiving surface 36a, and a light-receiving signal of the reflected light LA ​​is output from this second light-receiving region E2. Therefore, the light-receiving signal of the reflected light LA ​​output from the second light-receiving region E2 is a near signal indicating that the sensor head 20 has approached the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR. Therefore, the proximity determination unit 42 is capable of performing a proximity determination (hereinafter abbreviated as "proximity determination") to determine whether the sensor head 20 has approached the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR, based on whether a proximity signal has been output from the light-receiving sensor 36.

[0060] Furthermore, when the approach determination unit 42 determines that the sensor head 20 is in an "approaching state" in the approach determination, it displays approach information indicating this on the monitor 24. This allows the operator to know that the sensor head 20 has approached the measurement surface Wa, i.e., that the second position adjustment process has been completed.

[0061] The adjustment completion determination unit 43 is activated when the third position adjustment process is initiated by a manual movement operation by the operator, and determines whether the sensor head 20 has reached the target height position H1 during the third position adjustment process. When the measurement surface Wa moves from the proximity range SR to the upper limit of the measurement range WR during the third position adjustment process, the reflected light LA ​​is incident on the first light-receiving area E1 of the light-receiving surface 36a. In this case, the output of the approach signal from the light-receiving sensor 36 stops, and a light-receiving signal of the reflected light LA ​​is output from the first light-receiving area E1. Therefore, the adjustment completion determination unit 43 can perform an adjustment completion determination (hereinafter abbreviated as adjustment completion determination) to determine whether the sensor head 20 has reached the target height position H1 based on whether the output of the approach signal from the light-receiving sensor 36 has stopped (whether a light-receiving signal of the reflected light LA ​​has been output from the first light-receiving area E1).

[0062] Furthermore, when the adjustment completion determination unit 43 determines that "the sensor head 20 has reached the target height position H1" in the adjustment completion determination, it displays adjustment completion information indicating this on the monitor 24. This allows the operator to know that the sensor head 20 has reached the target height position H1, i.e., that all height position adjustments of the sensor head 20 have been completed.

[0063] The shape measurement control unit 44 operates when, after the position of the sensor head 20 is adjusted to the target height position H1, an operation to start shape measurement of the measurement surface Wa is executed on the operation unit 22. The shape measurement control unit 44 drives the X-axis movement mechanism 18a of the holder 18 to move the sensor head 20 in the X direction, and also starts detection of the X-direction position of the sensor head 20 by the X-position detection sensor 18b. As a result, the measurement surface Wa is scanned along the X direction by the measurement light L emitted from the sensor head 20, thereby performing shape measurement of the measurement surface Wa.

[0064] When the shape measurement of the measurement surface Wa is started, the distance measurement unit 46 continuously measures the distance from the sensor head 20 to the measurement surface Wa (the irradiation position of the measurement light L) based on the light-receiving position of the reflected light LA ​​incident on the first light-receiving area E1 of the light-receiving surface 36a, and continuously outputs the measurement results of the distance measurement to the shape calculation unit 48. Note that the distance measurement by the distance measurement unit 46 is performed in synchronization with the detection of the X-direction position of the sensor head 20 by the X-position detection sensor 18b.

[0065] The shape calculation unit 48 calculates various shapes of the measurement surface Wa using a known method based on the distance measurement results by the distance measurement unit 46 and the X-direction position detection results of the sensor head 20 by the X-position detection sensor 18b, which are executed in synchronization with each other.

[0066] Once the shape measurement of the measurement surface Wa is completed, the operator operates the lift lever 22a to drive the C-axis movement mechanism 16, and moves (retracts) the sensor head 20 upward in the Z direction along the C-axis 14, thereby moving it away from the measurement surface Wa. This movement continues until the reflected light LA ​​is no longer received by the first light-receiving region E1 of the light-receiving surface 36a, that is, until the measurement surface Wa moves out of the measurement range WR. Note that the movement of the sensor head 20 in this case can be performed faster than the movement of the sensor head 20 in the second position adjustment process and the third position adjustment process.

[0067] [Operation of First Embodiment] Fig. 8 is a flowchart showing the flow of the shape measurement process of the measurement surface Wa of the workpiece W by the surface shape measuring machine 10 of the first embodiment configured as described above. Fig. 9 is a flowchart showing the flow of the height position adjustment process of the sensor head 20 in Fig. 8 according to the position adjustment method of the present invention. Fig. 10 is an explanatory diagram for explaining the height position adjustment process of the sensor head 20.

[0068] As shown in FIG. 8, after the operator sets the workpiece W on the upper surface of the measuring table 12, a height position adjustment process is first performed to adjust the height position of the sensor head 20 in the Z direction to the target height position H1 (step S10).

[0069] 9 and 10 , in response to an operator's operation to start height position adjustment using the operation unit 22, the height position adjustment unit 40 drives the C-axis movement mechanism 16 to move the sensor head 20 downward in the Z direction at high speed along the C-axis 14 (step S11, see symbol XA in FIG. 10 ). This causes the sensor head 20 to approach the measurement surface Wa at high speed. Note that step S11 corresponds to the first approaching step of the present invention.

[0070] Then, if the reflected light LA ​​is not received in the first light receiving area E1 of the light receiving surface 36a, that is, if the sensor head 20 has not approached the measurement surface Wa to a position where the measurement surface Wa is included within the measurement range WR, the height position adjustment unit 40 continues to move the sensor head 20 downward in the Z direction at high speed (NO in step S12).

[0071] When the sensor head 20 approaches the measurement surface Wa to a position where the measurement surface Wa is included within the measurement range WR, the reflected light LA ​​is received by the first light-receiving area E1 (YES in step S12). Then, when the reflected light LA ​​is received by the first light-receiving area E1, the height position adjustment unit 40 stops the movement of the sensor head 20 by the C-axis movement mechanism 16 based on the light-receiving result when an arbitrary position within the measurement range WR (e.g., the center position in the Z direction) reaches the measurement surface Wa (step S13; see symbol XB in FIG. 10). Note that step S13 corresponds to the first stopping step of the present invention. This completes the first position adjustment process for the sensor head 20.

[0072] When the first position adjustment process for the sensor head 20 is completed, the operator operates the lift lever 22a to drive the C-axis movement mechanism 16, thereby manually moving the sensor head 20 further downward in the Z direction along the C-axis 14 at low speed (step S14). Note that step S14 corresponds to the second approach step of the present invention. This starts the second position adjustment process for the sensor head 20, and the sensor head 20 approaches further toward the measurement surface Wa. At the same time, the approach determination unit 42 starts approach determination by monitoring whether or not an approach signal is output from the light-receiving sensor 36 (NO in step S15).

[0073] When the sensor head 20 approaches the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR, the reflected light LA ​​is incident on the second light-receiving area E2, causing the light-receiving sensor 36 to output a proximity signal (YES in step S15, which corresponds to the signal output step of the present invention). This causes the proximity determination unit 42 to determine that the proximity is in an "approaching state" and display approach information indicating this on the monitor 24 (step S16).

[0074] Upon receiving the approach information displayed on the monitor 24, the operator stops the drive of the C-axis movement mechanism 16 by the lift lever 22a, thereby stopping the movement of the sensor head 20. This stops the sensor head 20 at a height position where the measurement surface Wa is included in the proximity range SR (see symbol XC in FIG. 10 ). This completes the second position adjustment process for the sensor head 20.

[0075] When the second position adjustment process for the sensor head 20 is completed, the operator operates the lift lever 22a to drive the C-axis movement mechanism 16, thereby manually moving the sensor head 20 upward in the Z direction along the C-axis 14 (step S17). This starts the third position adjustment process for the sensor head 20, and the sensor head 20 moves away from the measurement surface Wa (corresponding to the separating step of the present invention). At the same time, the approach determination unit 42 starts an adjustment completion determination by monitoring whether or not an approach signal is output from the light-receiving sensor 36 (NO in step S18).

[0076] When the measurement surface Wa reaches the upper limit of the measurement range WR (within the measurement range WR), the reflected light LA ​​enters the first light-receiving area E1, and the output of the approach signal from the light-receiving sensor 36 stops (YES in step S18). This causes the adjustment completion determination unit 43 to determine that "the sensor head 20 has reached the target height position H1" and display adjustment completion information on the monitor 24. Upon receiving the adjustment completion information displayed on the monitor 24, the operator stops the movement of the sensor head 20 by stopping the drive of the C-axis movement mechanism 16 using the lift lever 22a (step S19, corresponding to the second stopping step of the present invention). This adjusts the position of the sensor head 20 to the target height position H1 (see symbol XD in FIG. 10 ). This completes the third position adjustment process for the sensor head 20, i.e., all height position adjustment processes for the sensor head 20 are completed.

[0077] 8 , after adjusting the position of the sensor head 20 to the target height position H1, the operator executes an operation to start the shape measurement of the measurement surface Wa on the operation unit 22 (step S20). In response to this start operation, the shape measurement control unit 44 drives the X-axis moving mechanism 18a to move the sensor head 20 in the X direction and starts detecting the X-direction position of the sensor head 20 by the X-position detection sensor 18b, thereby starting the shape measurement of the measurement surface Wa (step S30).

[0078] When the shape measurement of the measurement surface Wa is started, the distance measurement by the distance measurement unit 46 and the detection of the X-direction position of the sensor head 20 by the X-position detection sensor 18b are synchronously and continuously executed. Then, based on these results, the shape calculation unit 48 calculates various shapes of the measurement surface Wa using a known method.

[0079] When the operator has completed measuring the shape of the measurement surface Wa, he or she operates the lift lever 22a to drive the C-axis movement mechanism 16, thereby manually moving the sensor head 20 upward in the Z direction along the C-axis 14 at high speed. This causes the sensor head 20 to move away from the measurement surface Wa at high speed (NO in steps S40 and S50). The sensor head 20 continues to move away from the measurement surface Wa until the measurement surface Wa is outside the measurement range WR (YES in step S50).

[0080] As described above, in the surface profile measuring instrument 10 of the first embodiment, the size of the light-receiving surface 36a of the light-receiving sensor 36 is enlarged compared to conventional methods, and the light-receiving sensor 36 also functions as a proximity sensor, making it possible to detect the measurement surface Wa within the proximity range SR without providing a separate piezoelectric sensor and distance measuring sensor in the sensor head 20. As a result, the sensor head 20 can be brought close to the measurement surface Wa at low cost and with high accuracy. This allows the sensor head 20 to be positioned at the target height position H1 at low cost and with high accuracy.

[0081] 11 is a functional block diagram of the control device 26 of a surface profile measuring instrument 10 according to a second embodiment. In the surface profile measuring instrument 10 according to the first embodiment, part of the height position adjustment process of the sensor head 20 (second position adjustment process and third position adjustment process) is performed by manual movement operation by the operator, but the surface profile measuring instrument 10 according to the second embodiment automatically performs all of the height position adjustment process of the sensor head 20.

[0082] 11 , the surface profile measuring instrument 10 of the second embodiment has basically the same configuration as the surface profile measuring instrument 10 of the first embodiment, except that the function of the height position adjustment unit 40 of the control device 26 is different from that of the first embodiment, and the control device 26 functions as a movement amount calculation unit 41 instead of the adjustment completion determination unit 43. For this reason, parts that are the same in function or configuration as those of the first embodiment are given the same reference numerals, and their description will be omitted.

[0083] FIG. 12 is an explanatory diagram illustrating the movement amount Δh calculated by the movement amount calculation unit 41. As shown in FIG. 12, the movement amount calculation unit 41 calculates the movement amount Δh required to move the sensor head 20 closest to the measurement surface Wa within the range in which the measurement surface Wa is included within the measurement range WR after the measurement surface Wa reaches the lower limit of the measurement range WR while the sensor head 20 is approaching the measurement surface Wa from the initial position described above. Here, "moving the sensor head 20 closest to the measurement surface Wa within the range in which the measurement surface Wa is included within the measurement range WR" means moving the sensor head 20 to the target height position H1 (see FIG. 4). Because the Z-direction distance from the sensor head 20 to the end of the measurement range WR and the Z-direction width of the measurement range WR are known, the movement amount calculation unit 41 can calculate the movement amount Δh based on this known information.

[0084] Instead of causing the control device 26 to function as the movement amount calculation unit 41, a movement amount Δh calculated in advance may be stored in a storage unit (not shown).

[0085] Returning to Figure 11, when the operation to start adjusting the height position of the sensor head 20 is executed on the operation unit 22, the height position adjustment unit 40 (corresponding to the position adjustment unit of the present invention) of the second embodiment drives the C-axis moving mechanism 16 to automatically move the sensor head 20 to the target height position H1 based on the result of receiving the reflected light LA ​​by the light receiving sensor 36 and the movement amount Δh (see Figure 13 described below).

[0086] Fig. 13 is a flowchart showing the flow of the height position adjustment process of the sensor head 20 in the surface profile measuring instrument 10 of the second embodiment. Fig. 14 is an explanatory diagram for explaining the height position adjustment process of the sensor head 20 in the surface profile measuring instrument 10 of the second embodiment.

[0087] 13 and 14 , in response to an operator's operation to start height position adjustment on the operation unit 22, the height position adjustment unit 40 drives the C-axis movement mechanism 16 to move the sensor head 20 downward in the Z direction at high speed along the C-axis 14 (step S11, see reference symbol XIVA in FIG. 14 ). This causes the sensor head 20 to approach the measurement surface Wa at high speed. The height position adjustment unit 40 then continues to move the sensor head 20 downward in the Z direction at high speed until the first light-receiving region E1 receives the reflected light LA, i.e., until the measurement surface Wa reaches the lower limit of the measurement range WR (NO in step S12).

[0088] When the sensor head 20 approaches the measurement surface Wa to the reference position H0 where the measurement surface Wa reaches the lower limit of the measurement range WR (YES in step S12, see reference symbol XIVB in FIG. 14), the first light-receiving region E1 receives the reflected light LA. When the reflected light LA ​​is received by the first light-receiving region E1, i.e., when the sensor head 20 reaches the reference position H0, the height position adjustment unit 40 acquires the calculation result of the movement amount Δh from the movement amount calculation unit 41 (step S13A). Note that the timing at which the height position adjustment unit 40 acquires the movement amount Δh is not particularly limited, as long as it occurs before step S14A, which will be described later.

[0089] Then, the height position adjustment unit 40 drives the C-axis movement mechanism 16 to move the sensor head 20 further downward in the Z direction from the reference position H0 by a movement amount Δh at high speed (low speed movement is also possible), i.e., to bring it closer to the measurement surface Wa (step S14A).

[0090] At this time, the height position adjustment unit 40 monitors whether the reflected light LA ​​is received by the light-receiving surface 36a while the sensor head 20 is further moved downward in the Z direction by the movement amount Δh from the reference position H0. If the light-receiving sensor 36 is no longer able to receive the reflected light LA ​​during this movement of the sensor head 20, the height position adjustment unit 40 stops the movement of the sensor head 20 by the C-axis movement mechanism 16 (NO in step S15A, NO in step S16A, step S17A).

[0091] FIG. 15 is an explanatory diagram illustrating the reason for stopping the movement of the sensor head 20 in step S17A of FIG. 14 . As indicated by reference symbols XVA and XVB in FIG. 15 , it is difficult to precisely align the emission direction (measurement axis) of the measurement light L from the sensor head 20 with the C-axis 14 (Z direction), and this emission direction may be tilted relative to the Z direction. In this case, as the sensor head 20 moves downward in the Z direction, the incident position of the measurement light L incident on the measurement surface Wa from the sensor head 20 changes. Therefore, if the measurement surface Wa is tilted or has unevenness (such as a recess 102), the light-receiving sensor 36 may not be able to receive the reflected light LA ​​while the sensor head 20 is moving downward in the Z direction (approaching the measurement surface Wa), causing the light-receiving sensor 36 to lose sensitivity. As a result, if the sensor head 20 continues to move downward in the Z direction, there is a risk that the sensor head 20 will come into contact with the measurement surface Wa.

[0092] Therefore, in the second embodiment, if the light receiving sensor 36 loses sensitivity while the sensor head 20 is being moved further downward in the Z direction by a movement amount Δh from the reference position H0, the movement of the sensor head 20 is stopped, thereby preventing the sensor head 20 from coming into contact with the measurement surface Wa.

[0093] In addition, the height position adjustment unit 40 may stop the movement of the sensor head 20 when the approach determination unit 42 determines that the sensor head 20 is in an "approaching state" in the approach determination, that is, when the sensor head 20 approaches the measurement surface Wa to a position where the measurement surface Wa is included within the proximity range SR.

[0094] 13 and 14 , when the C-axis moving mechanism 16 has moved the sensor head 20 downward in the Z direction by the movement amount Δh from the reference position H0, the height position adjustment unit 40 stops the movement of the sensor head 20 by the C-axis moving mechanism 16 (YES in step S15A, YES in step S16A). This automatically adjusts the position of the sensor head 20 to the target height position H1 (see symbol XIVC in FIG. 14 ). Note that the processing thereafter is the same as in the first embodiment (see FIG. 8 ), so a detailed description will be omitted here.

[0095] As described above, in the surface shape measuring instrument 10 of the second embodiment, the height position adjustment of the sensor head 20 can be performed automatically, and therefore the position of the sensor head 20 can be adjusted to the target height position H1 more easily, more accurately, and in a shorter time than in the first embodiment.

[0096] [Third Embodiment] In the surface profile measuring instrument 10 of each of the above embodiments, a triangulation-type sensor head 20 is used to measure the distance between the sensor head 20 and the measurement surface Wa, but the present invention can also be applied to a surface profile measuring instrument 10 that measures the distance to the measurement surface Wa using a well-known color confocal-type sensor head 20 (not shown). Note that components that are the same in function or configuration as those of the above embodiments are given the same reference numerals and their description will be omitted.

[0097] In the color confocal sensor head 20, the wavelength of the reflected light LA ​​incident on the sensor head 20 [pinhole (optical fiber cable, etc., not shown)] changes depending on the distance between the sensor head 20 and the measurement surface Wa, and the incident position of the reflected light LA ​​incident on the light-receiving surface 36a (pixel position on the light-receiving surface 36a) changes depending on the wavelength of the reflected light LA. Therefore, as in the above embodiments, the color confocal sensor head 20 can also detect the measurement surface Wa within the proximity range SR by enlarging the size of the light-receiving surface 36a compared to conventional methods. Note that in the color confocal sensor head 20, the measurement light L and reflected light LA ​​are coaxial.

[0098] 16 is an explanatory diagram illustrating the first light-receiving region E1 and the second light-receiving region E2 on the light-receiving surface 36a of the light-receiving sensor 36 that receives the reflected light LA ​​incident on the color confocal sensor head 20. Note that the horizontal axis in Fig. 16 indicates the pixel position on the light-receiving surface 36a, and the vertical axis indicates the signal intensity of the light-receiving signal (symbol SG) of the reflected light LA ​​received by the light-receiving surface 36a.

[0099] 16, like the above embodiments, the light receiving surface 36a of the third embodiment is adjusted to a size that includes a first light receiving area E1 that receives reflected light LA ​​from the measurement surface Wa within the measurement range WR and a second light receiving area E2 that receives reflected light LA ​​from the measurement surface Wa within the proximity range SR. As a result, like the above embodiments, a portion of the light receiving sensor 36 (light receiving surface 36a) can be allocated as a proximity sensor, thereby achieving the same effects as the above embodiments.

[0100] Fig. 17 is an explanatory diagram for explaining in detail the second light-receiving region E2 described in Fig. 16. As shown in Fig. 17, when the sensitivity [signal strength (voltage value) of the light-receiving signal of the reflected light LA] changes depending on the incident position (pixel position on the light-receiving surface 36a) of the reflected light LA ​​incident on the light-receiving surface 36a, it is possible to measure the distance between the sensor head 20 and the measurement surface Wa depending on the magnitude of the sensitivity. In this case, the sensitivity gradually decreases as the incident position of the reflected light LA ​​on the light-receiving surface 36a moves away from the center of the pixel position.

[0101] Specifically, when the sensitivity falls below the lower threshold range R1A where sensitivity can be obtained, a non-sensitivity range R2A is entered, where the sensitivity is zero (including nearly zero). Furthermore, when the sensitivity exceeds the upper threshold range R1B where sensitivity can be obtained, a non-sensitivity range R2B is entered, where the sensitivity is zero. The lower threshold range R1A and the upper threshold range R1B may be unsuitable for distance measurement due to their low sensitivity (poor S / N ratio), particularly when a lens is selected to reduce the spot diameter of the measurement light L in the first light-receiving region E1. For this reason, the lower threshold range R1A and the upper threshold range R1B can also be included in the second light-receiving region E2.

[0102] Next, a surface profile measuring instrument 10 according to a fourth embodiment will be described. In the surface profile measuring instruments 10 according to the above-described embodiments, the approach determination unit 42 performs approach determination based on whether or not an approach signal is output from the light-receiving sensor 36. However, in the surface profile measuring instrument 10 according to the fourth embodiment, the approach determination unit 42 performs approach determination based on the voltage value (signal strength) of the light-receiving signal output from the light-receiving sensor 36.

[0103] The surface profile measuring instrument 10 of the fourth embodiment has basically the same configuration as the surface profile measuring instrument 10 of each of the above-described embodiments, except that it has a function of outputting the voltage value (signal value) of the light-receiving signal output from the light-receiving sensor 36 to the approach determination unit 42. Therefore, parts that are the same in function or configuration as those of the above-described embodiments are given the same reference numerals, and their description will be omitted.

[0104] 18 is an explanatory diagram for explaining the approach determination method of the approach determiner 42 of the fourth embodiment. Note that, here, the explanation will be given taking as an example a case where the voltage value of the light receiving signal output from the light receiving sensor 36 increases as the sensor head 20 approaches the measurement surface Wa and the distance between them becomes shorter.

[0105] 18, the approach determination unit 42 of the fourth embodiment performs approach determination based on whether the voltage value of the light-receiving signal output from the light-receiving sensor 36 reaches a predetermined maximum value Vmax (voltage value = Vmax) as shown by reference symbol XVIIIA, or whether the voltage value reaches a predetermined upper threshold value Th (voltage value = upper threshold value Th) as shown by reference symbol XVIIIB. In other words, the light-receiving signal of the maximum value Vmax or the upper threshold value Th is assigned to the approach signal.

[0106] In addition, if the voltage value of the light-receiving signal output from the light-receiving sensor 36 decreases as the distance between the sensor head 20 and the measurement surface Wa decreases, the approach determination unit 42, not shown, determines whether the voltage value of the light-receiving signal output from the light-receiving sensor 36 has reached a predetermined minimum value or lower threshold value. In other words, the light-receiving signal of the minimum value or lower threshold value is assigned to the approach signal.

[0107] [Modification] Figure 19 is an explanatory diagram for explaining a modification of the surface profile measuring instrument 10 of each of the above-described embodiments. In the surface profile measuring instrument 10 of each of the above-described embodiments, the sensor head 20 approaches the measurement surface Wa when the holder 18 is moved downward in the Z direction by the C-axis moving mechanism 16, and conversely, the sensor head 20 moves away from the measurement surface Wa when the holder 18 is moved upward in the Z direction by the C-axis moving mechanism 16. However, the present invention is not limited to this. For example, as shown in Figure 19, the surface profile measuring instrument 10 may be configured such that the sensor head 20 moves away from the measurement surface Wa when the holder 18 is moved downward in the Z direction by the C-axis moving mechanism 16, and conversely, the sensor head 20 approaches the measurement surface Wa when the holder 18 is moved upward in the Z direction by the C-axis moving mechanism 16.

[0108] [Others] In each of the above embodiments, the light source 30 and the light receiving sensor 36 are provided inside the sensor head 20, but the light source 30 and / or the light receiving sensor 36 may be provided outside the sensor head 20. In this case, a separate optical system may be provided to guide the measurement light L from the light source 30 to the sensor head 20, or a separate optical system may be provided to guide the reflected light LA ​​incident on the sensor head 20 to the light receiving sensor 36.

[0109] In each of the above embodiments, the C-axis 14, which corresponds to the movement axis of the present invention, is parallel to the Z direction (vertical direction), but it may be parallel to any direction other than the Z direction.

[0110] In each of the above embodiments, the sensor head 20 is moved in the Z direction along the C-axis 14 by the C-axis moving mechanism 16, but instead of moving the sensor head 20, the workpiece W may be moved along the moving axis by various known moving mechanisms.

[0111] In each of the above embodiments, the triangulation method and the color confocal method were used as examples of methods for measuring the distance from the sensor head 20 to the measurement surface Wa, but the present invention can be applied to various distance measurement methods that can measure the distance depending on the incident position of the reflected light LA ​​on the light receiving surface 36a.

[0112] Although the above embodiments have been described taking the surface shape measuring instrument 10 as an example, the present invention is applicable to various shape measuring instruments that perform non-contact measurement of various shapes of the measurement surface Wa.

[0113] 10... Surface shape measuring instrument, 12... Measurement table, 14... C-axis, 16... C-axis movement mechanism, 18... Holder, 18a... X-axis movement mechanism, 18b... X-position detection sensor, 20... Sensor head, 22... Operation unit, 22a... Lifting lever, 24... Monitor, 26... Control device, 30... Light source, 32... Light incident / exit surface, 32a... Light exit window, 32b... Light incident window, 34... Lens, 36... Light receiving sensor, 36a... Light receiving surface, 40... Height position adjustment unit, 41... Movement amount calculation unit, 42... Approach determination unit, 43... Adjustment completion determination unit , 44...Shape measurement control unit, 46...Distance measurement unit, 48...Shape calculation unit, 100...Sensor head, 102...Recess, E1...First light receiving area, E2...Second light receiving area, H0...Reference position, H1...Target height position, L...Measurement light, LA...Reflected light, MR...Head position range, R1A...Lower threshold range, R1B...Upper threshold range, R2A...Non-sensitivity range, R2B...Non-sensitivity range, SR...Proximity range, Th...Upper threshold, Vmax...Maximum value, W...Work, WR...Measurement range, Wa...Measurement surface, Δh...Movement amount

Claims

a distance measurement unit that measures the distance based on the incident position of the reflected light on the light receiving surface; and a moving mechanism that moves one of the sensor head and the measurement surface toward and away from the other along a predetermined moving axis, wherein a measurement range for measuring the distance in the emission direction is predetermined at a position away from the sensor head in the emission direction of the measurement light, and wherein, when the range between the sensor head and the measurement range is defined as a proximity range, the light receiving surface has a size that allows the reflected light to be received even when the other is moved toward the other by the moving mechanism to a position where the measurement surface is included in the proximity range.

2. A non-contact shape measuring instrument as claimed in claim 1, wherein the reflected light reflected in a direction different from the incident direction of the measurement light from the measurement surface is incident on the sensor head.

3. A non-contact shape measuring instrument according to claim 1, wherein the measurement light emitted from the sensor head and the reflected light incident on the sensor head are coaxial.

4. A non-contact shape measuring machine as described in any one of claims 1 to 3, comprising: a position adjustment unit that drives the moving mechanism to bring the other one closer to the one object; and a movement amount calculation unit that calculates the amount of movement of the other one required to bring the other one closest to the one object within a range in which the measurement surface is included in the measurement range after the measurement surface reaches the measurement range while the other one is approaching the one object, wherein the position adjustment unit drives the moving mechanism to bring the other one closer to the one object by the movement amount after the measurement surface reaches the measurement range while the other one is approaching the one object based on the result of receiving the reflected light by the light receiving sensor.

5. A non-contact shape measuring machine as described in claim 4, wherein the position adjustment unit stops driving the moving mechanism when the reflected light can no longer be received by the light receiving sensor after the measurement surface reaches within the measurement range.

6. A non-contact shape measuring machine as described in any one of claims 1 to 3, further comprising a proximity determination unit which determines whether the other one has approached the one to a position where the measurement surface is included within the proximity range based on the voltage value of the light receiving signal output from the light receiving sensor, the voltage value of the light receiving signal being output from the light receiving sensor varying depending on the incident position of the reflected light relative to the light receiving surface.

7. A non-contact shape measuring instrument according to any one of claims 1 to 3, wherein the movement axis is parallel to the vertical direction.

8. A position adjustment method for adjusting the position of the other object along the movement axis in a non-contact shape measuring machine as defined in any one of claims 1 to 3, comprising: a first approaching step of bringing the other object closer to the one object by the movement mechanism; a first stopping step of stopping the first approaching step at a position where the measurement surface is included in the measurement range based on the result of reception of the reflected light by the light receiving sensor during execution of the first approaching step; a second approaching step of bringing the other object further closer to the one object by the movement mechanism after the first stopping step; a signal outputting step of outputting an approaching signal indicating the approach of the other object to the one object when the other object has approached the one object to a position where the measurement surface is included in the approaching range based on the result of reception of the reflected light by the light receiving sensor during execution of the second approaching step; a separating step of separating the other object from the one object by the movement mechanism when the signal outputting step has been executed; and a second stopping step of stopping the separating step when the measurement surface reaches the measurement range based on the result of reception of the reflected light by the light receiving sensor during execution of the separating step.

9. The position adjustment method according to claim 8, wherein in the first approaching step, the other is moved at a higher speed than in the second approaching step and the separating step.

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