JP4680415B2 - Damage prevention mechanism for fine stylus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mechanism for preventing damage to a fine stylus, and in particular, a three-dimensional fine shape of submillimeter order of mechanical parts such as measurement of the fine structure of a micromachine part and measurement of the internal shape of a fuel injection nozzle or an ink jet printer nozzle of an internal combustion engine. The present invention relates to a technique for preventing a fine stylus from being damaged in a microfabricated shape measuring apparatus used for measuring the stylus.
[0002]
[Prior art]
Conventionally, configurations represented by those described in Japanese Patent Application Laid-Open Nos. 5-264214 and 8-0745445 are known for measurement by a contact method of a minute shape.
[0003]
Both have a configuration in which a stylus or a probe can be inserted into a finely processed microstructure, which will be described in detail below.
[0004]
First, FIG. 7 shows a configuration diagram of a first conventional example represented by Japanese Patent Laid-Open No. 5-264214.
[0005]
In FIG. 7, 101 is a stylus, 102 is an actuator that vibrates the stylus 101 in the direction of the arrow in the figure, and 103 is a measurement object to which the stylus 101 comes close.
[0006]
Here, the measuring object 103 is placed on a Z stage 104 movable in the Z direction and an X stage 105 movable in the X axis direction. The Z stage 104 is a Z axis drive mechanism 106, and the X stage 105 is an X axis drive. Each is connected to the mechanism 107.
[0007]
Further, reference numeral 108 denotes a duty cycle measuring device, and the Z-axis driving mechanism 106, the X-axis driving mechanism 107, and the duty cycle measuring device 108 are controlled by a computer 109.
[0008]
In such a configuration, the actuator 102 vibrates the stylus 101 at a fixed position with a constant amplitude as indicated by an arrow in the figure.
[0009]
In this state, the electrical conduction between the stylus 101 and the measuring object 103 is detected by applying a DC voltage and looking at the short-circuit current, and the duty cycle measuring device 108 detects the ratio of the conduction time to the vibration period. become.
[0010]
For example, referring to FIG. 8, when the stylus 101 that vibrates as shown in FIG. 8A exceeds a certain displacement s, the measurement of the stylus 101 and the measurement object 103 is performed as shown in FIG. 8B. Electrical continuity is ensured between the target surfaces.
[0011]
The change in the relative distance between the stylus 101 and the measurement target surface of the measurement target 103 and the duty cycle have a relationship as shown in FIG.
[0012]
Therefore, the surface shape of the measuring object 103 can be detected by operating the Z-axis feed mechanism 105 while recording the duty cycle.
[0013]
As can be seen from FIG. 9, the relationship between the two is not completely proportional, but the degree of proportionality can be increased by changing the vibration of the stylus 101 from a sine wave to a triangular wave.
[0014]
Further, when the unevenness of the measurement target surface of the measurement target 103 exceeds the amplitude of the stylus 101, the surface shape of the measurement target 103 is measured by operating the X-axis drive mechanism 107 and repositioning the measurement target 103. It is also possible to do.
[0015]
Next, the second conventional example is an improvement of the first conventional example shown in FIG. 7 and improves the usability as a measuring device by combining the microscope 242 and the stylus 234.
[0016]
First, in FIG. 10, the photographing unit 242 and the stylus 234 are set in a coaxial positional relationship. That is, the stylus 234 is present at substantially the center of the image of the microscope 242. The image of the microscope 242 is guided to the image processing unit 244 and displayed on the display unit of the image processing unit 244. Then, while viewing the image displayed on the display unit, the XY stage 226A is moved in the X-axis direction or the Y-axis direction, and the fine hole 229 of the workpiece 228 is positioned at the center of the image. Thereafter, the work 228 is moved upward by the Z stage 226 </ b> B, whereby the stylus 234 is inserted into the fine hole 229. In this state, the coordinates of the minute hole surface 229A are obtained by making the contact between the stylus 234 and the minute hole surface 229A in the same manner as in the first conventional example while finely feeding the XY stage 226A again. Can do. By correcting the diameter of the stylus 234 from the coordinate values thus obtained, the inner diameter of the fine hole 229 can be known. Incidentally, the tip of the stylus 234 is machined into a diamond shape as shown in FIG. 11, and is devised so that the bore inner diameters in the X and Y directions can be accurately measured.
[0017]
[Problems to be solved by the invention]
Although the above two conventional examples have the possibility of being used for measurement of machining shapes such as nozzle holes and fine shapes, they have the following problems.
[0018]
In other words, the stylus commonly used in both is required to have shape stability, and thus is formed of a hard material. In general, the stage structure of a measuring device that relatively moves the measurement object and the stylus has a mass of several kilograms to several tens of kilograms. Overtravel will occur. Even if the tip of the stylus beam structure is displaced in a direction perpendicular to the beam, the displacement of the stylus can be relatively absorbed by the bending of the beam. However, when the tip is pushed in a direction parallel to the beam, there is no room for deformation of the beam, so that there is a problem that the beam is buckled or the life is remarkably shortened.
[0019]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and provide a damage prevention mechanism and a control method therefor that can prevent stylus damage and shortening of life regardless of the contact direction between the stylus and a measurement object.
[0020]
[Means for Solving the Problems]
In order to solve such a problem, the present invention attaches a holder of a fine stylus to a fine actuator, and prevents the fine stylus from buckling when the fine stylus contacts the measurement object in the axial direction thereof. This is a mechanism for preventing breakage of a fine stylus, which is characterized in that it is lifted up and released from contact, and when there is no risk of buckling, it is not released from contact.
[0021]
More specifically, first, the fine stylus and the object to be measured are moved relative to each other by the stage of the measuring device. However, since the stage has a large mass, the stage will coast after the contact of the fine stylus is detected. Deform. Fine stylus has high aspect ratio Needle Since it is a structure, it does not break even if it is deformed in the bending direction. However, if it is attempted to deform in the axial direction, it will be bent or buckled, leading to damage.
[0022]
Here, the holder of the fine stylus is attached to an actuator that displaces it in the axial direction, and at the same time, the stylus detects contact, and at the same time, the actuator is rapidly contracted to provide control compliance to the fine stylus. To prevent buckling and deformation.
[0023]
In addition, the velocity vector of the relative movement between the fine stylus and the measurement object has a component in a direction perpendicular to the axial direction of the fine stylus in some cases. When the velocity vector in the axial direction is small, the amount of overtravel in the axial direction after contact detection is also small, so there is no concern that the fine stylus will buckle. Therefore, only when the axial speed is greater than a certain value, control is performed to pull back the fine stylus, and otherwise, actuator control is performed to keep the fine stylus at a fixed position.
[0024]
As described above, even if the fine stylus comes into contact with the measurement target from any direction, the fine stylus can ensure proper escape and prevent damage such as buckling and deformation.
[0025]
In the first aspect of the present invention, a fine stylus having a cantilever structure and a measurement object having a fine shape are moved relative to each other in the direction of the fine stylus axis, and the fine shape is measured by detecting contact between the two. In the fine shape measuring apparatus, an actuator that protects the fine stylus by displacing the fine stylus in a direction away from the measurement object; A stage for relatively moving the fine stylus and the actuator toward the measurement object in the fine stylus axis direction; A contact detection unit that detects contact between the fine stylus and the measurement object and outputs a contact signal; a velocity vector calculator that calculates a relative movement speed vector of the fine stylus and the measurement object; and the fine stylus; When the contact between the fine stylus and the measurement target is detected in accordance with the relative movement speed vector of the measurement target and the contact signal, the actuator displaces the fine stylus in a direction away from the measurement target. A control unit that controls the actuator that is displaced in a direction in which the fine stylus approaches the measurement target when the non-contact between the fine stylus and the measurement target is detected. The controller is actuated so as to displace rapidly when the velocity in the direction of the fine stylus axis exceeds a certain level and when the contact signal is detected. Controlling the eta, and setting the approach speed and the detachment speed of the fine stylus and the measurement object to predetermined values, and when the fine stylus returns to the original position after the rapid detachment, Make sure that the measurement object is already at a distance Control the stage and the actuator This is a mechanism for preventing damage to a fine stylus. With such a configuration, the fine stylus can be protected from damage during contact.
[0026]
In this case, it is preferable that the actuator is made of a piezoelectric element because of its high-speed displacement characteristics.
[0027]
Further, as described in claim 3, it is preferable that the actuator comprises a piezoelectric element and a displacement magnifying mechanism because the stylus can escape a large amount of displacement and has a higher damage prevention effect.
[0028]
Furthermore, as described in claim 4, it is preferable that the actuator has a displacement sensor for monitoring displacement because displacement drift and displacement hysteresis peculiar to the actuator can be canceled.
[0029]
Also, The control unit controls the actuator so that the descending speed (speed component in the Z direction) is equal to or higher than a certain level and when the contact signal is detected, the actuator rapidly rises. This is desirable because the fine stylus can be released from contact at high speed, and at the same time, the fine stylus can automatically return to the original position.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.
[0031]
(Embodiment 1)
FIG. 1 shows a configuration of a fine shape measuring apparatus equipped with a fine stylus breakage preventing mechanism according to an embodiment of the present invention.
[0032]
In FIG. 1, 1 is a fine stylus, cantilever with a diameter of several tens of micrometers and a length of several millimeters Needle It has a structure. Reference numeral 2 denotes a stylus holder, which is attached to a fine movement actuator 10 that holds and fixes the fine stylus 1 in a replaceable state and displaces the fine stylus 1 in the axial direction. Reference numeral 3 denotes a measurement target, a part of which has a fine shape such as a fine hole, and is fixed to the Y stage 6 and the base 9 via the sample holder 4. The measurement object 3 and the fine stylus 1 can be moved relative to each other by the X stage 5, the Y stage 6, and the Z stage 7.
[0033]
First, the fine stylus 1 is cantilevered along the Z direction. Needle It has a structure, and its tip has a ball-shaped, abacus-ball, saddle-shaped projection, etc., and has the ability to detect that the tip is in contact with the measurement object. In this embodiment, this stylus is brought into contact with the change in the resonance state as shown in “Presentation of the 1999 Precision Engineering Spring Conference Academic Lecture” P.504 “Resonant Vibroscan Method Using Piezoelectric Sensor”. It is of the type to detect. Of course, a fine stylus that detects contact by electrical conduction, a stylus that detects a reaction force due to contact, or a stylus that detects a change in optical characteristics may be used. In general, the fine stylus 1 is made of a hard material such as cemented carbide, glass, ceramic, and has high shape stability with little friction and deformation. On the other hand, unreasonable deformation may lead to damage.
[0034]
The X stage 5, the Y stage 6, and the Z stage 7 move the fine stylus 1 relative to the measurement object 3, and when the fine stylus 1 detects contact, the X stage 5, the Y stage 6, and the Z stage 7 are simultaneously detected. The coordinates are read and stopped immediately, and the retraction operation is performed in the opposite direction. By repeating this series of operations, measurement of a fine shape is achieved. The X stage 5, Y stage 6, and Z stage 7 are generally guided by an air slide or a ball guide, and are driven by a rotary motor and a ball screw or a linear motor. Since the X stage 5, the Y stage 6, and the Z stage 7 and their driving parts have a constant mass (several kg to several tens kg) and inertia, the stage is not detected after the fine stylus 1 detects contact. Until the stop / retreat, overtravel of several μm to several tens of μm actually occurs, and as a result, the tip of the fine stylus 1 is pushed into the measurement object. Fine stylus 1 cantilevered Needle Because of this structure, the displacement in the horizontal (XY) direction can be absorbed by bending, and there is little damage. By the way, φ20μm, 1000μm long cemented carbide cantilever Needle If so, the tip displacement of 100 μm will not cause breakage.
[0035]
However, it cantilevered in the vertical (Z) direction. Needle Therefore, even if the fine stylus 1 is pushed in by several μm at most, it leads to the occurrence of buckling or bending.
[0036]
FIG. 2 is an enlarged view of the vicinity of the fine stylus 1 of FIG. As described above, the stylus holder 2 holds the fine stylus 1 in a removable form. A stylus substrate 11 is attached to the fine stylus 1 for stable mechanical coupling and electrical connection between the stylus holder 2 and the fine stylus 1. The stylus holder 2 is attached to the fine actuator 10, and the fine actuator 10 performs a retreat operation in the Z direction necessary for preventing the fine stylus 1 from being damaged to protect the fine stylus 1. The long focus microscope 8 provided on the left side of the fine stylus 1 has a role of guiding the fine stylus 1 to the measurement object 3. Since the focal position 12 is located below the fine stylus 1, after observing the measuring object 3 with the long focus microscope 8, the X stage 5, the Y stage 6, and the Z stage 7 are determined by a predetermined amount. By moving, the fine stylus 1 can be stably guided to the measurement object 3.
[0037]
Next, the overall configuration of the fine shape measuring apparatus and a control method for preventing damage will be described with reference to FIG. First, 19 is an NC control circuit (NC controller) for controlling the X stage 5, the Y stage 6, and the Z stage 7. When the contact signal 16 from the fine stylus 1 is received, the X stage 5, Y stage 6. , And a function to immediately stop and retract the Z stage 7. The NC control circuit 19 is provided with a speed vector calculator for obtaining a relative movement speed vector between the fine stylus 1 and the measuring object 3 so that the approach speed between the fine stylus 1 and the measuring object 3 can be known. The control computer 21 is a main CPU that controls the entire fine shape measuring apparatus, and has a function of instructing the NC control circuit 19 via the NC command 20 of XYZ movements necessary for measurement. When the breakage prevention control circuit 17 detects a signal from the stylus 1 via the contact signal detection circuit 13, it issues a displacement command 15 to the fine movement actuator control circuit 14, and the fine movement actuator 10 is driven accordingly, and the fine stylus 1. Evacuation operation is realized. Whether or not to perform the evacuation operation is determined by the ZDOWN signal 18 from the NC control circuit 19.
[0038]
FIG. 4 shows an example of the structure of a fine movement actuator 10 used in a damage prevention mechanism for pulling up the fine stylus 1 upward when the fine stylus 1 contacts the measuring object 3 from the Z direction. The fine actuator 10 is supported by the actuator body 36, the table portion 35 connected to the actuator body 36 via the parallel leaf spring 25, the stylus holder 2 fixed to the table portion 35, and the stylus holder 2. The fine stylus 1 is provided. Further, the fine movement actuator 10 includes a laminated piezoelectric element 22 that applies a fine movement operation to the table portion 35, and a displacement enlarging mechanism 23 that enlarges the displacement of the laminated piezoelectric element 22 and transmits the displacement to the table portion 35. The actuator main body 36 has a cup shape with a section that has a housing space 37 that opens downward and accommodates the table portion 35. The table portion 35 is housed in the housing space 37 and is connected and supported to the actuator body 36 by a parallel leaf spring 25 extending in the lateral direction between the actuator body 36 and the table portion 35. The stylus holder 2 is fixed to a table portion 35 that is precisely guided by a parallel spring 25.
[0039]
A pedestal 38 that protrudes from the side wall of the actuator body toward the inside of the accommodation space 37 is provided at a predetermined position of the lower end portion of the actuator body 36. The laminated piezoelectric element 22 is fixedly installed on the cradle 38, and one end of the displacement magnifying mechanism 23 is in contact with the upper surface of the laminated piezoelectric element 22. The other end of the displacement magnifying mechanism 23 is in contact with the upper surface of the table portion 35. A fulcrum member 39 is in contact with a predetermined position in an intermediate portion of the displacement magnifying mechanism 23. As a whole, the displacement magnifying mechanism 23 pushes down the table portion 35 when the laminated piezoelectric element 22 extends, and conversely, the laminated piezoelectric element. When the element 22 contracts (or shortens), the lever portion is configured to allow the table portion 35 to be returned to the original displacement position by the action of the parallel leaf spring. The displacement enlarging mechanism 23 is composed of an elastic hinge or the like, and can displace the displacement without play. The table portion 35 is driven in the Z direction by the laminated piezoelectric element 22 via the displacement magnifying mechanism 23. The laminated piezoelectric element 22 can generate a displacement of several μm at a voltage of about 100V, and the displacement magnifying mechanism 23 can displace the table part by several tens of μm. Since the displacement of the laminated piezoelectric element 22 generally drifts with time, the position of the table portion 35 is monitored by the displacement sensor 24 to ensure high positioning accuracy by feedback control.
[0040]
Such a structure in which the laminated piezoelectric element 22, the displacement magnifying mechanism 23, and the displacement sensor 24 are combined has been commercialized in many ways by PI Polytech Co., Ltd., and is as easy as controlling the laminated piezoelectric element 22 alone. The fine movement actuator 10 can be controlled.
[0041]
Further, when the amount of overtravel of the Z stage 7 is small, the displacement magnifying mechanism 23 is not always necessary, and the laminated piezoelectric element 22 alone can also serve to prevent breakage. Other actuators that can move at high speed can also be used as the fine movement actuator 10. For example, a voice coil motor, a linear motor, an electrostatic drive actuator, a magnetostrictive element, an electrostrictive element, or the like can be substituted.
[0042]
At this time, the breakage preventing operation is realized as follows. First, the fine movement actuator 10 is held in an extended state, and thereafter, the fine stylus 1 is brought close to and brought into contact with the measurement object 3 from above at a constant speed or higher. The fine stylus 1 is pulled up by contracting the fine actuator 10 at a high speed simultaneously with the contact, and the fine stylus 1 is not pushed in even if the Z stage 7 continues to descend without being stopped due to inertia. That is, damage to the fine stylus 1 due to buckling can be prevented.
[0043]
When the relative velocity vector is only the horizontal component (XY component), the fine stylus is not pushed in the Z direction at the time of contact and there is no fear of breakage. Further, if the Z component of the relative velocity vector is present even if it is small (for example, 1 μm / s), the overtravel of the Z stage after the contact is negligibly small. In these cases, it is not necessary to shrink the fine actuator 10 at the time of detection. FIG. 5 shows how the ZDOWN signal is generated by the speed vector calculator built in the NC control circuit 19. The relative movement speed vectors of the fine stylus 1 and the measurement object 3 generated by the movement of the X stage 5, the Y stage 6, and the Z stage 7 are an X direction speed component 26, a Y direction speed component 27, and a Z direction speed component 28. expressed. X- and Y-direction velocity components are not used for generating the ZDOWN signal.
[0044]
In the Z-direction velocity component 28, a threshold velocity 29 is set such that the fine stylus 1 approaches the measurement target 3, and the Z-direction velocity component 28 sets this value. Below (Above this threshold Speed When the fine stylus 1 approaches the measuring object 3), the ZDOWN signal 18 is turned on. When the ZDOWN signal is on, it means that the fine stylus 1 may buckle when it contacts the measuring object 3 and instructs the breakage prevention control circuit 17 to control the fine actuator 10. . Even if the ZDOWN signal is not generated by the NC control circuit 19, for example, the control computer 21 calculates the generation timing of the ZDOWN signal in advance in the measurement operation plan and directly instructs the damage prevention control circuit 17 to generate the ZDOWN signal. May be. Furthermore, the breakage prevention control circuit 17 may have a pulse interface of a linear encoder for measuring the position of the Z stage 7, and may determine the moving direction of the Z stage 7 and generate a ZDOWN signal. Furthermore, a method in which the damage prevention control circuit 17 directly takes in the NC command 20 and generates the ZDOWN signal by itself is also possible.
[0045]
FIG. 6 shows a circuit configuration for the breakage prevention control circuit 17 to output a displacement command 15 to the fine actuator 10. The contact signal from the fine stylus 1 is transmitted to the breakage prevention control circuit 17 via the TRIG signal 16. At this time, the rising speed 30 of the fine stylus 1 is set as a positive voltage, and the falling speed 31 is set as a negative voltage. The TRIG signal 16 controls the switch 32 and selects one of the voltages according to the contact state of the fine stylus 1. The switch 33 is controlled by the ZDOWN signal 18 from the NC control circuit 19 and selects either the voltage 30 or 31 indicating the ascending / descending speed or the voltage 31. The voltage selected by the switch 33 is input to the integrating circuit 34, and its output becomes the displacement command 15 and is output to the fine actuator control circuit, and the fine actuator 10 generates a displacement proportional to this voltage.
[0046]
With the above circuit configuration, the fine stylus 1 is controlled as follows. First, when both the TRIG signal 16 and the ZDOWN signal 18 are OFF, the integrating circuit 34 is saturated to the minus lower limit by the voltage 31, and the fine actuator 10 is waiting in advance at the lowest position. If the fine stylus 1 is approaching the measuring object 3 in the axial direction, the ZDOWN signal 18 is input, and a voltage other than zero is input to the integration circuit 34. Since the input voltage is selected by the TRIG signal 16, if no contact is detected with the fine stylus 1, a negative voltage continues to be input. Therefore, the integrating circuit 34 is saturated to the negative lower limit, and as a result, the fine actuator 10 It is in the lowest position. Next, when a contact signal is input to the fine stylus 1, a rising speed 30 is input, and the voltage output of the integrating circuit 34 increases rapidly. As a result, the fine actuator 10 rises faster than the speed of the Z stage, and the fine stylus 1 can be separated from the measurement object 3 even if the Z stage 7 cannot stop after contact detection and overtravels. When the contact state is canceled, the output value of the integration circuit starts to decrease again because the voltage 31 is switched. However, by setting the ascending speed 30 and the descending speed 31 to appropriate values, the fine stylus 1 By returning to the original lowest position, the Z stage 7 can eliminate the overtravel and provide a time allowance for the reversing / retracting operation (touch back operation). As a result, when the fine stylus 1 returns to the original lowest position, the measuring object 3 is already in a place away. By the above operation, it corresponds to the fine stylus 1 having compliance by the control force with respect to the pushing in the Z direction, which means that no buckling occurs even when pushing in the Z direction. In this embodiment, the control algorithm is realized by an analog circuit, but this method can be easily realized by a digital circuit, a microcomputer, or the like.
[0047]
The same effect can be obtained even if the switch 33 is integrated with the switch 32 and the logical product (AND) of the TRIG signal 16 and the ZDOWN signal 18 is given to the switch 32. Further, the same effect can be obtained by connecting the lower terminal of the switch 33 to the ground potential.
[0048]
With the above mechanism, the fine stylus 1 becomes compliant with pushing in all directions of XYZ, and can be prevented from being damaged. Furthermore, this embodiment can be expanded to allow the fine actuator 1 to be displaced in the XYZ triaxial directions, so that the fine stylus 1 can be given XYZ triaxial control compliance. The triaxial piezoelectric actuator is commercially available from PI Polytech, for example, and can be easily configured.
[0049]
As an advantage of the XYZ three-axis control compliance, the fine stylus 1 is detected within the displacement range of the actuator when contact is detected from the positional relationship between the fine stylus 1 and the measurement object 3 instructed by the control computer 21 in advance. You can escape freely. As a result, in addition to preventing damage when the micro stylus 1 is combined with a measuring device with extremely large overtravel in any direction, the movement plan trajectory of the fine stylus 1 and the surface position of the measuring object 3 are shifted in the case of scanning measurement. Can be absorbed.
[0050]
【The invention's effect】
As described above, according to the present invention, the cantilever is Needle When a fine stylus having a structure comes into contact with a measurement object, the pushing of the tip of the stylus caused by the fact that the stage of the measuring device cannot be stopped suddenly cancels the axial pushing that tends to damage the fine stylus with a fine actuator be able to.
[0051]
According to this configuration, when the tip of the fine stylus is pushed horizontally, Needle Damage is prevented by the bending of the structure, and when it is pushed in the axial direction, the damage can be prevented by controlling the actuator. As a result, an advantageous effect that stable contact detection can be realized.
[Brief description of the drawings]
FIG. 1 is a front view showing a schematic configuration of a fine shape measuring apparatus equipped with a fine stylus breakage preventing mechanism according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of an enlarged configuration near a fine stylus and a long focus microscope according to an embodiment of the present invention.
FIG. 3 is a control block diagram of a fine shape measuring apparatus according to an embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of a fine actuator used according to an embodiment of the present invention.
FIG. 5 is a diagram showing the principle of determination of a descent state according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating a control algorithm for preventing breakage according to an embodiment of the present invention.
FIG. 7 is a schematic configuration diagram of a conventional fine surface shape measuring apparatus.
FIG. 8 is a principle diagram showing a state of a contact signal and a duty ratio by a conventional device.
FIG. 9 is a diagram showing the relationship between the position of the surface to be measured by a conventional apparatus and the duty cycle.
FIG. 10 is a schematic configuration diagram of a conventional fine surface shape measuring apparatus.
FIG. 11 is a schematic diagram showing the shape of a stylus used in the same fine surface shape measuring apparatus.
[Explanation of symbols]
1 Fine stylus
2 Stylus holder
3 Measurement object
5 X stage
6 Y stage
7 Z stage
8 Long focus microscope
9 base
10 Fine actuator
17 Damage prevention control circuit
19 NC control circuit
22 Multilayer piezoelectric element
23 Enlarging mechanism
24 Displacement sensor
25 Parallel leaf spring
35 Table section
36 Actuator body
37 containment space
38 cradle
39 Supporting member

Claims (4)

In a fine shape measuring device that measures the fine shape by moving the measurement object with a fine stylus composed of a cantilever structure and the fine shape relative to each other in the fine stylus axis direction, and detecting the contact between them,
An actuator for protecting the fine stylus by displacing the fine stylus in a direction away from the measurement object;
A stage for relatively moving the fine stylus and the actuator toward the measurement object in the fine stylus axis direction;
A contact detection unit that detects contact between the fine stylus and the measurement object and outputs a contact signal;
A velocity vector calculator for obtaining a relative movement velocity vector of the fine stylus and the measurement object;
When the contact between the fine stylus and the measurement object is detected according to the relative movement speed vector of the fine stylus and the measurement object and the contact signal, the actuator removes the fine stylus from the measurement object. It is determined whether or not to displace in the direction of detachment, and when the non-contact between the fine stylus and the measurement object is detected, the actuator displaces the actuator in the direction in which the fine stylus approaches the measurement object. A control unit for controlling,
The controller controls the actuator so as to displace rapidly when the contact signal is detected when the velocity in the fine stylus axis direction is a certain level or more, and the fine touch When the approach speed and the separation speed of the needle and the measurement object are set to predetermined values, and when the fine stylus returns to the original position after the rapid separation, the measurement object seems to be already in a place away. And a mechanism for preventing breakage of a fine stylus which controls the stage and the actuator .   2. The fine stylus breakage prevention mechanism according to claim 1, wherein the actuator is a piezoelectric element.   2. The mechanism for preventing damage to a fine stylus according to claim 1, wherein the actuator uses a piezoelectric element and a displacement magnifying mechanism.   2. The mechanism according to claim 1, wherein the actuator has a displacement sensor for monitoring displacement.

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