JP4901533B2 - Force sensor, load detection device, and shape measurement device - Google Patents

Description

  The present invention mainly relates to the fields of electrical measurement in the field of semiconductor manufacturing, probe contact detection in failure analysis, etc., shape measurement during ultra-precision machining, and manipulation in biotechnology.

  As an example of the prior art, the configuration of a coordinate measuring machine is shown in FIG. In the three-dimensional measuring machine 80, a probe 81 is attached to an XYZ stage 83 provided with a three-dimensional displacement meter 82 in the XYZ directions. The XYZ stage 83 can move the probe 81 in the XYZ directions by the control / drive unit 84, the PC 85, and the operation unit 86. The XYZ stage 83 is operated manually or with a motor to measure the displacement in the XYZ directions when the probe 81 is pressed against the measurement object 88 by the three-dimensional displacement meter 82 and display it on the display 87. Measure the shape. As the three-dimensional displacement meter 82, a glass scale is usually used.

  However, while the processing accuracy of ultra-precision processing has reached a level of several tens of nanometers, the measurement accuracy of the workpiece shape measuring apparatus shown in FIG. The demand for is increasing. Moreover, when a glass scale is used, a measuring apparatus also becomes large. Therefore, the measurement time is prolonged due to the increase in the measurement range due to the enlargement of the workpiece and the increase in the number of measurement points due to the complicated shape, and the demand for shortening the measurement time is also increasing.

  In addition, since the conventional shape measuring apparatus is a system in which the probe is pressed against the measurement object manually or with a motor, it is difficult to make the load constant when the probe contacts the measurement object. For this reason, there are problems that the amount of deformation due to the rigidity of the probe and the measuring instrument body varies depending on the measurer and the measurement, or that the measurement error increases because the load fluctuates when the inclination angle of the measurement shape is large. . In order to solve this problem, there has been a demand for a force sensor that can measure the contact force during shape measurement with high accuracy and high resolution. In addition, since the structure of the probe, the force sensor, and the means for moving the probe is complicated, there is a problem that the price of the apparatus becomes expensive. Further, for shortening the measurement time, it is necessary to move the probe at a high speed. However, when the probe is large and heavy, it is difficult to move at high speed.

  The present invention has been made in view of these problems, and it is a first object of the present invention to provide a force sensor that can be downsized, has high resolution, and is inexpensive.

  Further, when electrical measurement or failure analysis of a single device such as a semiconductor is performed, there is a problem that the probe is deformed when the probe is pressed against the device electrode with a large load. Further, when the probe is brought into contact with the electrode by position control, there is a problem that the probe is separated from the electrode by disturbance such as vibration. The present invention has been made in view of these problems, and a second object of the present invention is to provide a load detection device that can measure in a more stable contact state between the probe and the electrode by using the load detection device according to the present invention. Yes.

  It is a third object of the present invention to provide a shape measuring device that can measure with high accuracy using a load detection device using a force sensor according to the present invention.

  In order to achieve the first object, a force sensor according to the present invention includes a flexible substrate made of insulating ceramics, a fixing member having support portions for supporting both ends of the flexible substrate, and the movable sensor. A probe provided between the support portions of the flexible substrate, and is formed in a thin film at a portion where distortion occurs on the flexible substrate when a load is applied to the probe. At least one strain gauge whose electrical resistance value changes due to strain, and measures a force applied to the probe by the strain gauge, and a part of the probe is restricted so as to limit a range in which the probe moves. It is characterized by being covered with a fixing member.

  Alternatively, a flexible substrate made of insulating ceramics, at least one strain gauge formed on the flexible substrate in a thin film shape, and having an electric resistance value changed by strain of the flexible substrate, and the flexible substrate A probe holder attached to one end of the flexible substrate, a probe supported by the probe holder, and the other end of the flexible substrate to the vicinity of the at least one strain gauge, and a load A fixing member having high rigidity with respect to a direction other than the direction of detecting the protection member, a protection member supported by the fixing member, and having a predetermined gap between the probe holder and the probe holder in order to limit the movement range of the probe holder, It is characterized by having.

  The probe holder and the fixing member are hollow cylinders, and the flexible substrate is fitted in a notch groove provided on a side surface of the cylinder, or four strain gauges are provided. Each of the two may have a positive or negative distortion, and the other two may be arranged so that the distortion has the opposite sign or 0 from the two.

  Also, as another configuration, a cruciform flexible substrate made of insulating ceramics, and a thin film is formed on a portion where distortion occurs on each arm of the flexible substrate. Four strain gauges with varying electrical resistance values, a fixing member for holding the tip of each arm of the cross-shaped flexible substrate, a probe holder provided at the center of the cross-shaped flexible substrate, A probe supported by the probe holder, and measuring the load applied to the probe in three directions perpendicular to each other by measuring a sum signal and / or a difference signal of the four strain gauges. It is characterized by breaking down into its component power.

  The probe and the probe holder are conductors, and a conductor that is electrically connected to the holding portion is formed on the flexible substrate, and includes a terminal for outputting an electrical signal from the probe. Also good. The flexible substrate may be made of zirconia ceramic, and the strain gauge formed in a thin film shape on the flexible substrate may be a Cr-N thin film. Further, an amplifier for amplifying the bridge output by the strain gauge may be provided.

  In order to achieve the second object, in the load detection device according to the present invention, any one of the force sensors described above is mounted on a moving unit including a driving unit and a control unit, and the moving unit is attached to the force sensor. The probe is moved so as to face the measurement object, and the moving means stops when the load between the probe and the measurement object reaches a desired value.

  Alternatively, the force sensor according to any one of the above is mounted on a moving unit including a driving unit and a control unit, and the probe mounted on the force sensor is moved by the moving unit so as to face the measurement object. The moving means controls the load so that the load received by contacting the probe with the object to be measured maintains a desired value.

  Alternatively, the force sensor according to any one of the above is mounted on a moving unit including a driving unit and a control unit, and the probe mounted on the force sensor is moved by the moving unit so as to face the measurement object. The moving means includes position detecting means, and when the detected position reaches a desired value, the control means controls the driving means so as to hold the position.

  The moving means may be a fine movement stage including a laminated piezoelectric actuator and a parallel hinge spring.

  Alternatively, a flexible substrate, a probe holder provided at one end of the flexible substrate, a probe attached to the probe holder, and a fixing provided at the other end of the flexible substrate A member, a piezoelectric element bonded to the flexible substrate, at least one strain gauge provided on the flexible substrate for detecting bending displacement of the flexible substrate due to the load of the probe, and the piezoelectric element And at least one strain gauge for detecting a bending displacement of the flexible substrate caused by applying a voltage.

  In order to achieve the third object, a shape measuring apparatus of the present invention includes any one of the force sensors and the moving means described above, so that the load received by the probe from the measurement object maintains a desired value. In addition, the shape of the measuring object is measured by scanning the moving means and measuring the position of the probe at that time.

  The moving means may be a fine movement stage including a laminated piezoelectric actuator and a parallel hinge spring.

  Alternatively, a flexible substrate, a probe holder provided at one end of the flexible substrate, a probe attached to the probe holder, and a fixing provided at the other end of the flexible substrate A member, a piezoelectric element bonded to the flexible substrate, at least one strain gauge provided on the flexible substrate for detecting bending displacement of the flexible substrate due to the load of the probe, and the piezoelectric element And at least one strain gauge for detecting a bending displacement of the flexible substrate caused by applying a voltage.

  The shape of the measurement object is measured by correcting the deformation amount of the force sensor and the probe based on the rigidity of the force sensor, the rigidity of the probe, and the contact load that the force sensor receives from the measurement object.

  Since the force sensor according to the present invention uses a flexible substrate made of insulating ceramics and a strain gauge formed in a thin film shape, the force sensor can be reduced in size and manufactured at low cost. . In addition, since the strain gauge is a Cr-N thin film formed on a flexible substrate by sputtering or the like, a minute force generated by a displacement on the order of nm can be detected, and a force sensor having high resolution can be obtained. Obtainable. Since the movement range of the probe is limited, it is possible to effectively prevent the flexible substrate from being damaged when the probe is replaced.

  Since the load detection device of the present invention can be made small and lightweight, the probe can be moved at high speed. In addition, when the force with which the probe presses the measurement object reaches a predetermined value, the position can be secured or a constant pressing force can be maintained. However, it is possible to maintain a constant pressing force following the vibration, and to perform an accurate measurement without being affected by the vibration. In addition, since the load detection device according to the present invention can perform measurement with a constant load, there is little measurement variation depending on the measurer and each measurement.

  Further, by using the force sensor and the load detection device, stable shape measurement can be performed with high resolution.

  FIG. 1 is a perspective view of a force sensor 10 according to a first embodiment of the present invention. The force sensor 10 is provided with a flexible substrate 11, which is made of insulating ceramics such as zirconia and has appropriate flexibility. Both ends of the flexible substrate 11 are supported by support portions 12a and 12b of the fixing member 12, and strain gauges 13a to 13d made of a Cr—N thin film are directly formed on the upper surface by sputtering or the like. Since the strain gauges 13a to 13d are formed by meandering thin lines and are thin films formed by sputtering or the like, the strength is almost zero, and the strain gauge itself does not reinforce the flexible substrate 11. Further, since the thin film is formed by sputtering, the adhesive does not intervene, and absorption, variation, and creep of sensitivity due to the adhesive layer can be suppressed, and a strain gauge with good stability can be obtained. In addition, since the cross-sectional area is small, a resistance wire having high resistance is obtained, and a strain gauge with high sensitivity can be obtained by increasing the bridge voltage. The support portions 12a and 12b are arm-shaped, and the rigidity in the X direction is small so that there is a degree of freedom in the X direction. In addition, the fixing member 12 is provided with a reinforcing portion 12 c so that the fixing member 12 does not deform with the deformation of the flexible substrate 11. A probe holder 16 is joined to substantially the center of the flexible substrate 11, and a probe 17 is attached to the tip thereof. When a load is applied to the probe 17, the flexible substrate 11 bends to cause distortion on the flexible substrate 11. When a load in the + Z direction is applied to the probe 17, negative distortion (shrinkage) occurs in the flexible substrate 11 near the support portions 12 a and 12 b, and positive distortion (extension) occurs near the probe holder 16. The magnitude of the distortion is larger as it is closer to the support portion 12a12b in the case of negative distortion, and is larger as it is closer to the probe holder 16 in the case of positive distortion. Therefore, since the strain gauges 13a to 13d need to be as sensitive as possible, the strain gauge 13a is close to the support portion 12a, the strain gauge 13d is close to the support portion 12b, and the strain gauges 13b and 13c are probes. It is desirable to form the holders 16 at portions close to both sides.

  FIG. 2 is a diagram in which the strain gauges 13a to 13d are bridge-connected. In the strain gauges 13a to 13d, when the flexible substrate 11 is bent, the meandering line expands and contracts and the electric resistance value changes. Therefore, as shown in FIG. 2, a bridge connection is made and the output voltage is increased by taking a differential resistance change caused by positive and negative strains of the strain gauges 13a to 13d. The relationship between the input voltage Vin and the output voltage Vout is expressed by the following equation (1) where the strain generated on the flexible substrate 11 on which the strain gauges 13a to 13d are formed is represented by ε1 to ε4, the gauge factor k, and the gain G of the gauge amplifier. ). However, ε1 represents the strain of the strain gauge 13b, ε2 represents the strain of the strain gauge 13a, ε3 represents the strain of the strain gauge 13d, and ε4 represents the strain of the strain gauge 13c. Ε1 and ε4 are positive strains, and ε2 and ε3 are negative strains.

Vout = Vin {k (ε1-ε2-ε3 + ε4)} G / 4 Formula (1)
As can be seen from equation (1), since the sign of the negative distortion is negative, Vout is proportional to the value obtained by adding the absolute values of ε1 to ε4. That is, the sensitivity of the force sensor can be improved by providing two strain gauges where the positive and negative strains are generated.

  The force sensor 10 having such a configuration can be easily miniaturized, and can detect a very light force with a high resolution of 10 μN as a contact load due to a displacement on the order of nm. Further, since the contact force is very small, the surface of the measurement object is not damaged.

  3A is a perspective view of the entire force sensor shown in FIG. 1 as viewed obliquely from below, and FIG. 3B is an enlarged bottom view of the force sensor. FIG. 4 is an enlarged cross-sectional view showing the main part of the AA cross section of FIG. The fixing member 12 and the support portions 12a and 12b of the force sensor 10 are entirely covered with a cover 18. The cover 18 is in close contact with the upper surface of the fixing member 12 and is separated from the support portions 12 a and 12 b, but is integral with the fixing member 12. The cover 18 has a hole 18a at the bottom, and the probe holder 16 passes through the hole 18a. Between the probe holder 16 and the hole 18a, there is a gap on one side d1 in the x direction, and there is a gap on one side d2 in the y direction. The probe holder 16 is provided with plate-like convex portions 16a extending in the x direction below the flexible substrate 11 with two pieces spaced apart on one side, and the hole 18a of the cover 18 is interposed between them. The edge is designed to enter. Therefore, a gap on one side d3 is secured in the z direction between the edge of the hole 18a and the upper and lower convex portions 16a. With such a configuration, the probe holder 16 can move in the holes 18a in the x, y, and z directions within the gaps d1, d2, and d3. By appropriately determining d1 to d3, even when a large load is applied to the probe holder 16 such as when the probe 17 is replaced, the range in which the probe holder 16 moves in the XYZ directions is limited, and the flexible substrate 11 It is possible to prevent the force sensor 10 from being damaged. Instead of limiting the moving range of the probe holder 16, the moving range of the probe 17 itself may be limited by the hole 18a or the like.

  As a specific example of this embodiment, the flexible substrate 11 is a zirconia substrate having a shape of 4 × 30 × 0.05 mm, and a meandering line formed of a Cr—N thin film is formed by means such as sputtering. Gauges 13a to 13d are formed. By setting the gauge factor to 6, the bridge voltage 10V, and the gain of the gauge amplifier to 1600 times. An output of 10 V is obtained for a load of 1 g weight.

  FIG. 5 is a perspective view showing the force sensor 20 of the second embodiment of the present invention. A hollow cylindrical fixing member 22 is attached to the preamplifier (or gauge amplifier) 21. Two hollow grooves 22a are formed in the hollow portion of the fixing member 22 so as to face each other, and an insulating and flexible flexible substrate 23 made of ceramics such as zirconia is fitted therein. ing. The flexible substrate 23 protrudes outward from the tip of the fixing member 22, and a probe holder 24 having the same shape as that of the fixing member 22 is provided at the protruding tip, and in a notch groove 24 a formed so as to face the same. A flexible substrate 23 is fitted into the base plate. A cylindrical protective member 25 is attached to the tip of the fixing member 22, and the protective member 25 covers a part of the probe holder 24, but the probe protrudes from the protective member 25 of the probe holder 24. 17 is attached. The outer diameter of the probe holder 24 is smaller than the inner diameter of the protective member 25, and a gap on one side d is provided.

  The flexible substrate 23 has a portion that is not covered by either of the fixing member 22 and the probe holder 24, and strain gauges 13a to 13d are provided on the surface of this portion as shown in FIG. Is provided. These strain gauges 13a to 13d are the same as those of the first embodiment, and are formed by sputtering a line made of a Cr-N thin film. The strain gauges 13a to 13d are covered with a protective member 25. As shown in FIG. 6 (b), a conductor 26 is formed almost entirely on the back surface of the flexible substrate 23. Since the conductor 26 is a thin film formed by sputtering or the like, it is flexible. The conductive substrate 23 is not reinforced.

  The strain gauges 13a and 13b are formed so that the strain sensitivity is in the X direction, and the strain gauges 13c and 13d are in the Y direction, and are connected to each other as shown in FIG. 21 is connected. The resistance change due to the strain gauges 13a to 13d is extremely small, and the strain gauge sensor signal cable is easily routed to be influenced by surrounding electrical noise. Therefore, the influence of noise can be reduced by installing the preamplifier 21 in the vicinity of the strain gauges 13a to 13d and routing the amplified signal. If the strain gauges 13c and 13d are provided on the back surface of the flexible substrate 23, the strain gauges 13a and 13b and the strain gauges 13c and 13d are subjected to strain in the positive and negative directions, so that the sensitivity can be increased.

  When the probe 17 moves so as to face the measurement object 19 and comes into contact with it, a load is applied and the probe 17 is displaced in the Z direction, this displacement is transmitted to the flexible substrate 23. Since the fixing member 22 and the probe holder 24 have sufficiently large rigidity as compared with the flexible substrate 23, the strain gauges 13a and 13b of the flexible substrate 23 are formed when a load is applied to the probe 17. The bent portion is bent the most, and the sensitivity of the strain gauge can be increased. The displacement of the probe 17 in the Z direction is a bending of the flexible substrate 23 and is displaced in the X direction. Therefore, the displacement is detected by the strain gauges 13a and 13b, and the strain gauges 13c and 13d are in an insensitive state where no displacement is detected. The strain gauges 13a to 13d are bridge-connected as shown in FIG. 7, and the load applied to the probe 17 can be measured by detecting the displacement amount of the strain gauges 13a and 13b.

  In the embodiment of FIG. 5, the strain gauges 13a to 13d are all formed on one surface of the flexible substrate 23. However, the strain gauges 13a and 13b are formed on the front side, and the strain gauges 13c and 13d are formed on the back side. When the sensitivity of all strain gauges is aligned in the X direction, one is expanded and the other is contracted, and sensitivity and resolution can be further increased.

  If a large load is applied to the probe 17 when the probe is exchanged, the displacement of the flexible substrate 23 becomes large and the flexible substrate 23 may be damaged. On the other hand, in the present invention, the protection member 25 is provided and the range in which the probe holder 24 can move is limited to the range of the gap on one side d, so that the flexible substrate 23 can be prevented from being damaged. Further, since the force sensor 20 has a cylindrical shape, the structure is simple, high in mass productivity, and can be configured to be small and light.

  The probe holder 24 and the probe 17 are made of metal, and the electrical characteristics of the measurement object 19 in electrical contact with the probe 17 can be measured from the terminal 29 by a terminal 29 connected on the conductor 26.

  FIGS. 8A and 8B are views of the force sensor 30 according to the third embodiment of the present invention, in which FIG. 8A is a perspective view and FIG. 8B is a reduced plan view of the flexible substrate 31. The force sensor 30 can measure the force in the XYZ directions applied to the probe 17 by dividing it.

  The force sensor 30 has a flexible substrate 31 having a cross shape, and strain gauges 13a to 13d are formed on the arms of the cross. The flexible substrate 31 and the strain gauges 13a to 13d are formed by the same material and method as the flexible substrate 11 shown in FIG. The force sensor 30 has a cross-shaped fixing member 32, and the tips of the four arms of the cross-shaped flexible substrate 31 are supported by support portions 32 a to 32 d suspended from the tips of the four arms of the fixing member 32. The parts are joined. Each support part 32a-32d is formed thinly, and it is trying for the rigidity of a bending direction to become small so that it may not become resistance when the flexible substrate 31 bends. On the fixing member 32, a reinforcing portion 32e for increasing the rigidity of the fixing member 32 is fixed. A probe holder 16 is provided at the center of the cross-shaped flexible substrate 31, and a probe 17 is attached to the probe holder 16.

  When a load in the X direction is applied to the probe 17, the strain gauges 13b and 13d have zero strain, the strain gauge 13a has positive strain, and the strain gauge 13c has negative strain. When a load in the Y direction is applied to the probe 17, the strain gauge 13d becomes negative, the strain gauge 13b becomes positive, and the strain gauges 13a and 13c have zero strain. Further, when a load in the Z direction is applied to the probe 17, positive strain is generated in the strain gauges 13a to 13d. Therefore, by outputting the sum signal and difference signal of the strain gauges 13a to 13d, the force in the XYZ directions applied to the probe 17 can be divided and measured, and a triaxial force sensor can be realized. it can.

  FIG. 9 is a perspective view showing a force sensor 40 having a fine movement stage 41 as a moving means in the fourth embodiment of the present invention. This force sensor 40 with a fine movement stage is obtained by mounting the force sensor 10 on a fine movement stage 41 shown in FIG. As shown in FIG. 10, the fine movement stage 41 is formed with slits 41a penetrating the front and back of a rectangular parallelepiped metal block such as aluminum as shown in the figure, and a parallel hinge spring in which a plurality of slits 41a are close to each other at four corners. 42 is formed. The fixed portion 43 formed on the outside of the slit 41a of the fine movement stage 41 and the moving portion 44 formed on the inside of the slit 41a are connected to each other by these four parallel hinge springs 42, and a guide mechanism without backlash. Is working. A laminated piezoelectric actuator 45 is incorporated between the fixed portion 43 and the moving portion 44. In the multilayer piezoelectric actuator 45, piezoelectric ceramics and internal electrodes are alternately stacked, and the internal electrodes are alternately applied to the external electrodes so that electric fields opposite to each other are applied to the adjacent piezoelectric ceramics by the internal electrodes. It has a connected structure.

  By applying a voltage to the multilayer piezoelectric actuator 45, the multilayer piezoelectric actuator 45 expands and contracts, and the moving part 44 can be displaced with respect to the fixed part 43 with a resolution of nm level against the elastic force of the parallel hinge spring 42. it can. In addition, since the amount of expansion and contraction is determined by the voltage applied to the laminated piezoelectric actuator 45, the moving unit 44 can be moved by a desired amount.

  The force sensor 10 fixes the cover 18 to the fixing member 12 to the moving part 44 of the fine movement stage 41. Therefore, the fine movement stage 41 is a moving means for moving the force sensor 10. The laminated piezoelectric actuator 45 and the parallel hinge spring 42 constitute a driving means for the moving means.

  The multilayer piezoelectric actuator 45 is connected to a PC 48 via a driver 46 and a D / A converter 47 as shown in FIG. The bridge output of the force sensor 10 is connected to the PC 48 via a preamplifier (gauge amplifier) 21 and an A / D converter 49. The probe 17 can be brought into contact with the measurement object 19 by applying a voltage to the laminated piezoelectric actuator 45 of the fine movement stage 41 in accordance with a command from the PC 48 and lowering the probe 17. Then, the load at the time of contact is detected by the force sensor 10, and the detected load is taken into the PC 48 via the A / D converter 49. When the load detected by the force sensor 10 reaches the set value, the PC 48 stops the fine movement stage 41 at that position. By holding the voltage applied to the laminated piezoelectric actuator 45, the fine movement stage 41 can hold its position. Or, conversely, by applying a servo voltage to the multilayer piezoelectric actuator 45 so as to maintain the set load as the detection load, the probe 17 and the measurement object 19 are controlled so as to always maintain a desired contact pressure. It becomes possible to do. With the above configuration, the gauge amplifier 21, the A / D converter 49, the driver 46, the D / A converter 47, and the PC 48 constitute a moving means control means.

  That is, the force sensor 40 with a fine movement stage can be used not only as a force sensor but also as a load detection device that holds a constant contact pressure (load).

  The force sensor 10 to be mounted may be the force sensor 20 described in the second embodiment or the force sensor 30 described in the third embodiment.

  By using the force sensor 40 with a fine movement stage according to the present invention, for example, when the electrical characteristics are measured by pressing the probe 17 onto the measurement object 19, contact can be made with a constant load, so that a reliable contact state is maintained. Stable measurement is possible. Further, by using the force sensor 40 with a fine movement stage according to the present invention, for example, even when a very soft measurement object is clamped, the measurement object can be clamped with an optimum load. It is possible to clamp without breaking.

  FIG. 12A is a perspective view showing a force sensor 50 with a fine movement stage according to a fifth embodiment of the present invention, and FIG. 12B is a perspective view showing a state in which the force sensor 10 is removed. A fine movement stage 51 as a moving means is obtained by incorporating a displacement sensor probe 52 into the fine movement stage 41 shown in FIGS. Components common to fine movement stage 41 are assigned the same reference numerals as fine movement stage 41, and description thereof is omitted. The force sensor 10 is fixed to the moving unit 44 of the fine movement stage 51. One end of the displacement sensor probe 52 is fixed to the fixed portion 43, and the other end is in contact with the moving portion 44. The displacement sensor probe 52 has the same structure as that of the force sensor 10 shown in FIG. 1 in principle, and includes a member that is elastically deformed (not shown) and four strain gauges provided on the member. The gauge is bridged. When the moving unit 44 moves relative to the fixed unit 43, the displacement sensor probe 52 detects the position of the moving unit 44, so that the displacement sensor probe 52 serves as a position detecting unit for the moving unit 44.

  FIG. 13 is a block diagram of the fifth embodiment. The same components as those in the block diagram of the fourth embodiment shown in FIG. The displacement sensor probe 52 is connected to the displacement sensor amplifier 53 and can measure the displacement amount of the moving unit 44 of the fine movement stage 51 by taking the measured displacement into the PC 48 via the A / D converter 54. Others are the same as described in FIG. Further, by applying a voltage to the multilayer piezoelectric actuator 45 in accordance with a command from the PC 48 and lowering the probe 17, the load when the probe 17 contacts the measurement object 19 is detected by the force sensor 10 and detected. Secondly, the force sensor 50 with the fine movement stage can be stopped at a position where the detected load becomes an arbitrary value by taking the load into the PC 48 via the gauge amplifier 21 and the A / D converter 49. This is the same as described in the embodiment. By measuring the position where the force sensor 50 with the fine movement stage is stopped by the displacement sensor probe 52 and the displacement sensor amplifier 53 shown in FIG. 13 and applying a servo voltage to the driver 46 so that the displacement of the fine movement stage 51 becomes constant, The probe 17 can hold the measurement object 19 in a state where it is pushed in a certain distance. Further, the fine movement stage 41 as the moving means is scanned with respect to the measurement object 19, and the position of the probe 17 at that time is measured by the displacement sensor probe 52, so that it can be used as a shape measuring device.

  As is apparent from the above configuration, the gauge amplifier 21, the A / D converter 49, the driver 46, the D / A converter 47, the PC 48, the displacement sensor amplifier 53, and the A / D converter 54 constitute a moving means control means. ing.

  Of course, the force sensor mounted may be the force sensor 20 described in the second embodiment or the force sensor 30 described in the third embodiment.

  FIG. 14 is a perspective view of a force sensor 60 with a fine movement stage according to a sixth embodiment of the present invention. Here, the three fine movement stages 41 are combined in the XYZ axial directions, and the force sensor 10 is attached thereto. The fine movement stage for X axis is 41X, the fine movement stage for Y axis is 41Y, and the fine movement stage for Z axis is 41Z.

  The force sensor 10 is fixed to the moving part 44 of the Z-axis fine movement stage 41Z, and the fixed part 43 of the Z-axis fine movement stage 41Z is fixed to the moving part 44 of the X-axis fine movement stage 41X, and the X-axis fine movement stage 41X. The fixed portion 43 is fixed to the moving portion 44 of the Y-axis fine movement stage 41. With such a configuration, the force sensor 10 can be moved by a minute amount in the X, Y, and Z axis directions with a resolution of nm. Others are the same as described in the fifth embodiment.

  Further, a servo voltage is applied to the stacked piezoelectric actuator 45 of the Z-axis fine movement stage 41Z so that the load applied between the probe 17 and the measurement object 19 becomes a set desired value, and the measurement with the probe 17 is performed. The load applied to the object 19 is kept constant, and the measurement object 19 is scanned by the X-axis fine movement stage 41X and the Y-axis fine movement stage 41Y, whereby the probe 17 is moved to the surface of the measurement object 19 with a desired contact load. Can be traced. By measuring the displacement of the Z-axis fine movement stage 41Z at this time with the displacement sensor probe 52, the surface shape of the measuring object 19 can be measured. When the contact load is large, the error in measuring the surface shape becomes large. However, the force sensor according to the present invention can set the contact load to a very small value of 10 μN. It is possible to measure without damaging the surface of the object 19. Further, in order to measure the surface shape with higher accuracy, deformation due to the rigidity of the flexible substrate 11 itself of the force sensor 10 cannot be ignored, but the force sensor 10 according to the present invention is composed only of an elastic body. By performing the constant load control according to the present invention, the load and the deformation amount of the force sensor 10 have a linear relationship and become substantially constant, and therefore can be easily corrected.

  In FIG. 14, by using the force sensor 30 described in the third embodiment instead of the mounted force sensor 10, it is possible to trace with a desired load in the XYZ directions. , 41Y, 41Z can be measured by measuring the displacement in the XYZ direction.

  FIG. 15 is a diagram showing a seventh embodiment of the present invention. The force sensor 70 with a fine movement stage according to the seventh embodiment has an insulating flexible substrate 71 similar to the flexible substrate 11 shown in FIG. 1, has a proximal end fixed to a fixing member 72, and a probe at the distal end. A holder 16 and a probe 17 are attached. A piezoelectric element 73 is formed on the front surface of the flexible substrate 71, and strain gauges 74a, 74b, 74c, and 74d for displacement detection are formed on the back surface side of the piezoelectric element 73. Further, near the probe holder 16 of the flexible substrate 71, strain gauges 13a and 13b are formed on the front side, and strain gauges 13c and 13d are formed on the back side, respectively, and these are bridge-connected.

  When the probe 17 is pressed against the measuring object 19 and receives a force and is displaced in the Z direction, the flexible substrate 71 is displaced in the Z direction, but the strain gauges 13a and 13b and the strain gauges 13c and 13d Is on the front and back of the flexible substrate 71, so that when one detects the strain of expansion, the other detects the strain of shrinkage, and these are bridge-connected as shown in FIG. The force applied to 17 can be detected with high accuracy.

  In addition, a piezoelectric element 73 is provided on the upper surface of the flexible substrate 71. When a voltage is applied to the piezoelectric element 73, the flexible substrate 71 expands and contracts in the longitudinal direction. The probe 17 is moved in the Z direction. The strain gauges 74a and 74b detect expansion and contraction in the length direction (left and right direction in FIG. 15) of the flexible substrate 71, and detect expansion and contraction in the width direction of the strain gauges 74c and 74d and flexible substrate 71. Stretching in the length direction is insensitive. Therefore, the amount of movement when the probe 17 moves in the Z direction can be detected by bridge-connecting these four strain gauges as shown in FIG. Further, when a voltage is applied to the piezoelectric element 73, the probe 17 is displaced in the Z direction. This displacement amount can be measured by the displacement detection strain gauges 74a, 74b, 74c, and 74d. Therefore, the probe 17 can be moved to a desired position by adjusting the voltage applied to the piezoelectric element 73.

  The configuration shown in FIG. 15 is a simpler configuration than the embodiment shown in FIG. 9, and it is possible to realize a force sensor integrally having moving means that can move in the Z direction. Light weight and low cost can be realized.

It is a perspective view which shows the principal part of the force sensor by the 1st Example of this invention. It is a figure which shows the state which bridge-connected four strain gauges of FIG. (A) is the perspective view which looked at the whole force sensor shown in FIG. 1 from diagonally downward, (b) is the figure seen from B of (a), and is the expanded bottom view of a force sensor. It is an expanded sectional view which shows the principal part of the AA cross section of FIG. It is a perspective view which shows the force sensor of the 2nd Example of this invention. (A) is a figure of the strain gauge formed in the flexible substrate of 2nd Example, (b) is a figure which shows the conductor formed in the back surface of a flexible substrate. It is a figure which shows the bridge connection of the four strain gauges of FIG. (A) It is a perspective view which shows the structure of the force sensor of the 3rd Example by this invention, (b) is a figure which shows arrangement | positioning of a flexible substrate and a strain gauge. It is a perspective view which shows the force sensor provided with the fine movement stage as a moving means in 4th Example of this invention. It is a perspective view which shows the structure of a fine movement stage. It is a block diagram of a 4th example. (A) is a perspective view which shows the force sensor with a fine movement stage of 5th Example of this invention, (b) is a perspective view which shows the state which removed the force sensor. It is a block diagram of the 5th example of the present invention. It is a perspective view which shows the force sensor with a fine movement stage of the 6th Example by this invention. It is a figure which shows the 7th Example by this invention. It is a figure which shows the conventional coordinate measuring machine.

Explanation of symbols

d, d1 to d3 Gap 10, 20, 30 Force sensor 11, 23 Flexible substrate 12 Fixing member 12a, 12b Support part 12c Reinforcement part 13a-13d Strain gauge 16a Protruding part 16, 24 Probe holder 17 Probe 18 Cover (fixed) Element)
18a Hole 19 Measurement object 21 Preamplifier (or gauge amplifier)
22 fixing member 23 flexible substrate 22a, 24a notch groove 25 protective member 26 conductor 29 terminal 31 cross-shaped flexible substrate 32 fixing member 32a-32d support portion 32e reinforcing portion 40, 50, 60, 70 force with fine movement stage Sensors 41, 41X, 41Y, 41Z Fine movement stage 41a Slit 42 Parallel hinge spring 43 Fixed part 44 Moving part 45 Multilayer piezoelectric actuator 46 Driver 47 D / A converter 48 PC
49, 54 A / D converter 51 Fine movement stage 52 Displacement sensor probe 53 Displacement sensor amplifier 71 Flexible substrate 72 Fixing member 73 Piezoelectric elements 74a to 74d Displacement detection strain gauges

Claims (12)

A flexible substrate made of insulative ceramics, at least one strain gauge formed on the flexible substrate in a thin film shape and having an electric resistance value changed by strain of the flexible substrate, and the flexible substrate A load is detected by supporting a probe holder attached to one end of the probe, a probe supported by the probe holder, and the other end of the flexible substrate from the vicinity of the at least one strain gauge. A fixing member having a high rigidity in a direction other than the direction in which the probe holder is supported, and a protection member supported by the fixing member and having a predetermined gap between the probe holder and the probe holder in order to limit the movement range of the probe holder. A force sensor , wherein the probe holder and the fixing member are hollow cylinders, and the flexible substrate is fitted in a notch groove provided on a side surface of the cylinder . The four strain gauges are provided, two of which are arranged so that the strain is positive or negative, and the other two are arranged so that the strain has an opposite sign or 0 with respect to the two. The force sensor according to 1 . The probe and the probe holder are conductors, a conductor electrically connected to the probe holder is formed on the flexible substrate, and a terminal for outputting an electrical signal from the probe is provided. The force sensor according to claim 1 or 2 , characterized by the above. Wherein the flexible substrate is made of zirconia ceramics, according to any one of claims 1 to 3, characterized in that the strain gauges are formed as a thin film on the flexible substrate is a thin film of Cr-N Force sensor. The force sensor according to any of claims 1 4, characterized in that the amplifier for amplifying the bridge output by the strain gauge is provided. The force sensor according to any one of claims 1 to 5 is mounted on a moving unit including a driving unit and a control unit, and a probe mounted on the force sensor by the moving unit is opposed to a measurement object. When the load between the probe and the measurement object reaches a desired value, the moving means stops. The force sensor according to any one of claims 1 to 5 is mounted on a moving unit including a driving unit and a control unit, and a probe mounted on the force sensor by the moving unit is opposed to a measurement object. The load detecting device is controlled so that the load received by the probe contacting the measurement object by the moving means is maintained at a desired value. The force sensor according to any one of claims 1 to 5 is mounted on a moving unit including a driving unit and a control unit, and a probe mounted on the force sensor by the moving unit is opposed to a measurement object. The load detecting device is characterized in that when the detection position reaches a desired value, the control means controls the driving means so as to hold the position. . 9. The load detection device according to claim 6, wherein the moving means is a fine movement stage including a laminated piezoelectric actuator and a parallel hinge spring. A force sensor according to any one of claims 1 to 5 and a moving means, wherein the probe scans the moving means so that a load that the probe receives from a measurement object maintains a desired value. A shape measuring apparatus that measures the shape of the measurement object by measuring the position of the object. The shape measuring apparatus according to claim 10 , wherein the moving means is a fine movement stage including a laminated piezoelectric actuator and a parallel hinge spring. The shape of the measurement object is measured by correcting the deformation amount of the force sensor and the probe based on the rigidity of the force sensor, the rigidity of the probe, and the contact load that the force sensor receives from the measurement object. The shape measuring apparatus according to claim 10 or 11 , characterized in that:

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