JP3130286B2 - Touch signal probe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch signal probe suitable for measuring a shape of a three-dimensional measuring machine or a machine tool, and more particularly to a vibrating touch signal probe having a low measuring force and a high sensitivity. Things.

[0002]

2. Description of the Related Art A height gauge (one-dimensional measuring machine), a three-dimensional measuring machine, a contour measuring machine and the like are known as measuring machines for measuring the shape and dimensions of an object to be measured. In order to perform coordinate detection and position detection in that case, a touch signal probe that detects contact with an object to be measured is used for the measuring device. As a principle of detection of this touch signal probe, a substantially cylindrical stylus having a contact portion at its tip which comes into contact with an object to be measured, vibration of the stylus and vibration caused by contact when the contact portion comes into contact with the object to be measured There is a structure that includes vibration / detection means for detecting a change in state, transmits a touch trigger signal when vibration detected by the vibration / detection means attenuates to a detection trigger level, and reads coordinate values at that time.

[0003] In order to widen the application range of the vibrating touch signal probe, it is desired to use a stylus, and for that purpose, a form in which the stylus is arranged in a cross shape is effective. FIG. 8 shows a first conventional example of a vibration type touch signal probe. In Conventional Example 1, a pair of stylus supports 3 having styluses 2 protruding at both ends are combined in the X and Y-axis directions, and a piezoelectric element 4 serving as a vibration / detection unit is provided above each stylus support 3. The stylus support 3 is arranged along the stylus 2 and each stylus support 3 is fixed to the tip of a probe main body 5 serving as a probe shaft.
Is brought into contact with the object to be measured to detect a change in the vibration state. Conventionally, a piezoelectric element serving as a vibration / detection unit is disposed on each of the mounting projections projecting from the four corners of the upper and lower surfaces of the block-shaped stylus support,
There is a touch signal probe in the form of a star stylus in which first and second styli that are symmetric with each other in the X-axis and Y-axis directions are arranged at the center position of each side surface (Japanese Patent Application No. 8-33).
No. 6986: Conventional example 2).

[0004]

The prior art 1 has a structure in which two sets of straight stylus supports 3 are combined.
Since the stylus is not arranged in the same plane, it is difficult to use, and it is difficult to reduce the size. In this respect, in Conventional Example 2, X is located at the center of each side surface of the stylus support.
Since the first and second styli that are symmetrical with each other in the axial and Y-axis directions are arranged, there is no inconvenience as in Conventional Example 1.

However, in the conventional example 2, since a single piezoelectric element generates reciprocating vibrations in both the X-axis and the Y-axis, a configuration in which four sets of vibration systems are coupled is provided. It is difficult for the Q value of the vibration in the resonance state to increase. FIG. 9 is a graph showing the relationship between the frequency and the amplitude, wherein (A) shows the case where the Q value is small, and (B) shows the case where the Q value is small.
The case where the value is large is shown. The difference D between the amplitude at the resonance point in the non-contact state and the amplitude at the resonance point after the contact (amplitude change due to the contact) is Q
Larger values are larger. Therefore, from FIG. 9, it can be seen that, in the vibrating touch signal probe based on the principle of detection of a change in the resonance state due to contact, the Q value of the vibration in the resonance state is an important factor directly affecting the sensitivity.

[0006] Therefore, the touch signal probe of the related art 2 having a stylus has a lower sensitivity than that of the related art 1 having the same stylus length, and has a large variation in detection response time. When the stylus contact speed is high (currently, 10 mm / sec or more), the touch signal probe is vibrated by the impact force at the time of contact,
Unpredictable disturbance occurs in the detected amplitude change. That is, when the stylus comes in contact with the object to be measured at a high speed, FIG.
As shown in FIG. 10A, the detected vibration displacement attenuates regularly from the start of the contact, while, on the other hand, FIG.
As shown in (2), a vibration waveform newly generated by the impact force is detected. The superimposition of these signals is the stylus detection signal.

FIG. 10 (C) shows a signal detected by the stylus as an amplitude converted into a DC level, and shows a graph of the relationship between the amplitude and time. FIG.
At 0 (C), when the vibration due to the impact force is applied as the same phase (shown by a solid line) and when the vibration due to the impact force is applied as an opposite phase (shown as a dotted line), it takes until the detection level of the touch trigger signal is reached. The time differs, and this difference in time becomes a variation error C in the detection response time, and a detection error occurs. Therefore, as the contact speed increases, the variation in the detection response time increases. This phenomenon is a problem that always occurs in all of the conventional vibrating touch signal probes. The frequency excited by the contact is the natural frequency of the vibrator composed of the stylus and the stylus support, and it is difficult to separate both signal components from the principle of vibration and detection at the resonance frequency.

An object of the present invention is to provide a touch signal probe which can perform high-precision measurement when formed in a cross shape and can be downsized.

[0009]

SUMMARY OF THE INVENTION Therefore, the present invention aims to achieve the above object by vibrating the vibrator with mode resonance having a high Q factor when the cross-shaped vibrator is vibrated at resonance. Is what you do. Specifically, the touch signal probe of the present invention includes a stylus support centered on the origin of the X axis, the Y axis, and the Z axis orthogonal to each other, and at least one of the X axis and the Y axis provided on the stylus support. A vibrator having a stylus fixed along the axis thereof, and a vibrator vibrating at a predetermined frequency arranged on a surface perpendicular to the Z-axis of the stylus support, and the stylus coming into contact with an object to be measured. Exciting / detecting means for detecting a state of vibration that changes to a touch signal probe that detects contact with the object to be measured because the state of vibration changes when the stylus contacts the object to be measured. Then, the vibrator is vibrated at a vibration frequency equal to one of the first natural frequency ω1 and the second natural frequency ω2 (ω2 ≠ ω1) of the vibrator, and the stylus is subjected to vibration. When it comes into contact with the measured object The change in the state of vibration when the stylus comes into contact with the object to be measured is enhanced by superposition of the other one of the first natural frequency ω1 and the second natural frequency ω2 of the generated vibration. And Note that the first natural frequency ω1 and the second natural frequency ω2 in the present invention are unique to the vibrator.

In the present invention having this configuration, the touch signal probe is moved to make contact with the object to be measured for measurement.
At this time, the vibrator is vibrated by the vibration / detection means in a vibration mode having a high Q value, for example, a vibration frequency equal to the second natural frequency ω2 to form a resonance state. In the vibration at the second natural frequency (second mode resonance), the Q value is high but the response amplitude is small. Therefore, the vibration component of the first natural frequency ω1 is superimposed on this vibration to change the vibration state. Enlarge. With the vibrator having this configuration, if the vibration is in the vibration direction, the amplitude width at the tip of the stylus of the vibrator is not smaller than the vibration at the primary natural frequency even in the vibration at the second natural frequency. Since the vibration of the stylus is surely restrained by the contact with the object to be measured, the change of the vibration state due to the contact surely occurs.
Therefore, the vibration of the stylus is reliably restrained, and the vibration state is accurately detected by the vibration / detection element. Moreover,
Since the stylus can be arranged on the same plane, the touch signal probe can be downsized even if the stylus is supported in a cross shape on the stylus support.

Here, in the present invention, the first natural frequency ω
A configuration may be provided including a beat signal component extracting means for detecting a beat signal generated by the superposition of 1 and the second natural frequency ω2. In this configuration, since the beat period of the beat signal is determined by the difference between the two frequencies, the frequency of the beat signal component takes a value completely different from the natural frequency. Therefore, it is easy to electrically extract the generated beat signal component with a filter, a resonator, or the like, and the superposed state of the first natural frequency ω1 and the second natural frequency ω2 is reliably detected. Vibration generated at the time of contact can be positively detected. This is effective in improving the S / N ratio.

Further, the stylus is fixed along the X-axis and arranged symmetrically with respect to the origin, and the second stylus is fixed along the Y-axis and arranged symmetrically with respect to the origin. A stylus pair may be provided.
With this configuration, it is possible to provide a cross-shaped stylus in which the stylus extends from the four side surfaces of the stylus support to the X axis and the Y axis, respectively.

On the other hand, the stylus is provided on the stylus support along one of the X-axis and the Y-axis, and is provided in a direction along the X-axis and the Y-axis of the stylus support, and A configuration in which a stylus is not provided may be provided with a balance member having a shape mechanically equivalent to the stylus. In this configuration, even if the stylus is an oscillator having an irregular structure provided on the stylus support along one of the X axis and the Y axis, the balance member balances the vibration with the stylus. Thereby, highly accurate measurement can be performed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Here, in each embodiment, the same components are denoted by the same reference numerals, and description thereof will be omitted or simplified. 1 to 6 show a first embodiment of the present invention. FIG. 1 is a perspective view of the touch signal probe according to the first embodiment. In FIG. 1, a touch signal probe includes a vibrator 16 configured by providing a stylus 13 on a stylus support 10, and a vibration that vibrates the vibrator 16 and changes when the stylus 13 comes into contact with an object to be measured. And a control circuit 17 for detecting a change in the vibration state of the vibrator 16 detected by the piezoelectric element 12 and transmitting a touch trigger signal. It is configured.

The stylus support 10 has its center at X,
A substantially rectangular parallelepiped block having a plane that is coincident with the origin of the Y and Z axes and that is perpendicular to the Z axis and has a square shape, and is installed at four corners of two upper and lower planes perpendicular to the Z axis. Projection 1
1, the piezoelectric elements 12 are bonded and arranged (in FIG.
(Only one piezoelectric element 12 is shown), and a pair of first and second styli extending in the center of each side surface in the X-axis and Y-axis directions and symmetrical with respect to the origin. 13 are arranged. Each of these styluses 13 has a contact portion 13 at its tip which comes into contact with the object to be measured.
a, the base end of which is a stylus support 1
0 is fixed by bonding, welding or the like. The stylus support 10 has a substantially cylindrical probe body 15 extending in the Z-axis.
Attached to. The probe support 15 is inserted through the center of the piezoelectric element 12 with a predetermined gap.

The piezoelectric element 12 is formed in a flat plate shape having a square planar shape, and is disposed in a plane orthogonal to the Z axis. The front surface electrode of the piezoelectric element 12 is divided into at least four parts, and the back surface is a common electrode. The surface electrode of the piezoelectric element 12 is configured such that a vibrating electrode for vibrating the stylus 13 in the axial direction (radial direction) and a detecting electrode are divided into a positive direction and a negative direction. In the first embodiment, a plurality of (for example, four) piezoelectric elements may be used, and these piezoelectric elements may be used exclusively for vibration or only for detection. In the first embodiment, the highest sensitivity is obtained when the stylus 13 contacts the object to be measured from a direction coinciding with the axial direction.

Next, the basic measurement principle of the first embodiment using the control circuit 17 will be described. 2A and 2B show a vibration mode of the vibrator 16, in which FIG. 2A shows a basic structure, FIG. 2B shows a primary mode of resonance, and FIG. 2C shows a secondary mode of resonance. In FIG. 2, the vibrator 16 applies radial vibration to each stylus 13, and the stylus 13 adjacent to each other has the same vibration form in each direction, but its phase is indicated by (B). The opposite is true in the primary mode, and the same is true in the secondary mode shown in FIG. This phase difference is a major feature when the stylus is vibrated in the radial direction.

The vibration mode of the straight vibrator shown in FIG. 8 is shown in FIG. 3A shows the basic structure of the vibrator, FIG. 3B shows the first-order mode resonance,
(C) shows second-order mode resonance. In FIG. 3, the vibrator 16 applies vibration to each stylus 2 along the axial direction. The direction of expansion and contraction of the piezoelectric element 3 and the direction of expansion and contraction of the stylus 2 correspond to the primary mode shown in FIG. In the resonance, the tip of the stylus 2 becomes in phase and the displacement of the tip of the stylus 2 increases, but in the secondary mode resonance shown in (C), the phase of the stylus 2 becomes the opposite phase and the displacement of the tip of the stylus 2 decreases (low sensitivity). However, in the first embodiment, the piezoelectric element 12
When the stylus 13 is vibrated in the radial direction, the amplitude of the tip of the stylus 13 does not become small compared to the amplitude of the piezoelectric element 12, and the vibration at the second natural frequency (second mode resonance) is applied. Sufficient sensitivity as a touch signal probe can be obtained in vibration.

FIG. 4 is a graph showing resonance characteristics of the vibrator. FIG. 4A shows a normal resonance characteristic of the vibrator 16 shown in FIG. 2, and the vibration at the second natural frequency ω2 is the first natural frequency ω1 (ω2 ≠ ω1). The amplitude is smaller than the vibration of. In this state, a change in the vibration of the stylus 13 cannot be reliably detected. Therefore, in the first embodiment, as shown in FIG. 4B, the second natural frequency ω2
Is substantially the same as the amplitude at the first natural frequency ω1. In order to increase the amplitude at the second natural frequency ω2, the length of the stylus 13 is set. Instead of the length, the thickness and material of the stylus 13 may be set. More specifically, the length of the stylus 13 at which the amplitude of the primary mode resonance is maximized is different from the length of the stylus 13 at which the amplitude of the secondary mode resonance is maximized. CAE such as FEM (Computer
Aided Engineering) technology.

Next, a specific configuration of the control circuit 17 will be described with reference to FIG. In FIG. 5, a control circuit 17 includes a vibration circuit 18 for driving and controlling a vibration electrode of the piezoelectric element 12.
And a detection circuit 19 that generates a touch trigger signal from a signal output from the detection electrode of the piezoelectric element 12, wherein the first natural frequency ω 1 of the vibration generated when the stylus 13 contacts the object to be measured is provided. This configuration is configured to enhance the change in the state of vibration when the stylus 13 contacts the object to be measured by superimposing the vibration component.

The vibrating circuit 18 detects a vibration signal output from the detecting electrode of the piezoelectric element 12 and simultaneously detects the vibration signal.
6, a natural frequency extracting means 20 for extracting only the second natural frequency ω 2, and receiving a signal from the natural frequency extracting means 20 to change the vibrating electrode of the piezoelectric element 12 to the second
And a drive signal generating means 21 for vibrating at the next natural frequency ω2. The detection circuit 19 calculates the first natural frequency ω
A beat signal component extracting means 22 for detecting a beat signal generated by superimposing 1 and the second natural frequency ω2;
Amplitude-DC level conversion means 2 for converting the signal output from the beat signal component extraction means 22 to amplitude-DC level
3 and a touch trigger signal generating means 24 for generating a touch trigger signal from the signal output from the amplitude-DC level converting means 23. The amplitude-DC level converting means 23 and the touch trigger signal generating means 24 have the same configuration as the conventional one, and the touch trigger signal generating means 24
The coordinate position of the touch signal probe at the time when the signal is issued is read as a measured value. In the first embodiment, a structure in which the beat signal component extracting means 22 is omitted may be used.

Next, the beat signal component extracting means 22 will be described. Generally, the vibration in the main vibration system of the two-degree-of-freedom vibration system is expressed by the following equation.

[0023]

(Equation 1)

Here, ω1 is the first natural frequency of the vibration system, ω2 is the second natural frequency, and φ1 and φ2 are arbitrary constants. When this vibration system is vibrated at, for example, the second natural frequency ω2 to form a resonance state, the secondary vibration is more dominant, and the apparent vibration is a steady state represented by the following equation. It will be.

[0025]

(Equation 2)

At this time, when the vibrator 16 starts contact with the object to be measured, the resonance state changes, so that the vibration state represented by [Equation 2] changes as shown by [Equation 1]. That is,
When the vibrator 16 comes into contact with the object to be measured, a vibration component having a frequency different from that of the excited resonance frequency is generated and starts to be superimposed. Specifically, the graph of FIG. 6 shows the amplitude-DC level converted detection signal when the stylus 13 starts contacting the object to be measured. In FIG. 6, the DC level-converted amplitude decreases while oscillating with the passage of time. This is equivalent to the difference between the primary and secondary frequencies as a result of superimposing the primary natural frequency (primary vibration mode) on the excited secondary natural frequency (secondary vibration mode). It appears as a variation K of the cycle. As a result, the vibrator 1 can be driven at the conventional primary natural frequency.
6 (shown by a dotted line in FIG. 6)
The signal greatly fluctuates due to the contact, and the apparent sensitivity and responsiveness of the cross-shaped touch signal probe can be improved by T1. FIG. 6 shows a signal waveform processed only by the amplitude-DC level converter 23 without using the beat signal component extractor 22.

Further, the vibration component excited by the impact force at the time of contact has a low Q value (it is susceptible to fluctuation due to external force).
Since the primary natural frequency ω1 is mainly used, the vibration component excited by the impact force does not overlap with the vibrating vibration component and does not become unstable. This is because the second natural frequency ω2 is used for excitation, and the frequency is completely different from the vibration component excited by the impact force. Rather, the excited first-order natural vibration component causes a signal to fluctuate greatly due to contact, and has the effect of increasing the apparent sensitivity and responsiveness of the touch signal probe. Therefore, even in a region where the contact speed is high, it is possible to reduce a variation error in the detection response time of the touch signal probe.

The beat signal shown in FIG. 6 is generated by the superposition of the first natural frequency ω1 and the second natural frequency ω2, and the beat period K is determined by the difference between the two frequencies. Therefore, since the frequency of the beat signal component takes a value completely different from the natural frequency, the beat signal component extracting means 22 electrically extracts the generated beat signal component using a filter, a resonator, or the like. Note that this beat signal is not generated unless it is touched, and is in principle no signal in a steady state. Therefore, it is effective in terms of the S / N ratio for detection.

Therefore, in the first embodiment, the stylus support 10 centered on the origin of the X axis, the Y axis, and the Z axis orthogonal to each other, and the X provided on the stylus support 10
A vibrator 16 includes a stylus 13 fixed along the axis and the Y-axis, and vibrates the vibrator 16 and detects a state of vibration that changes when the stylus 13 contacts an object to be measured. Vibration / detection means (piezoelectric element) 12
Are arranged on a plane perpendicular to the Z-axis of the stylus support 10 to constitute the touch signal probe. By arranging the stylus 13 in the same plane, the touch signal probe can be downsized.

Further, the touch signal probe according to the first embodiment vibrates the vibrator 16 at a vibrating frequency equal to the second natural frequency ω2 of the vibrator 16, and the stylus 13 comes into contact with the object to be measured. Since the stylus 13 is configured to enhance the change in the state of vibration when the stylus 13 contacts the object to be measured by superimposing the vibration component of the first natural frequency ω1 on the vibration generated at the time, the tip of the stylus 13 of the vibrator 16 Is not smaller than the vibration at the first natural frequency ω1, and the vibration of the stylus 13 is securely restrained by the contact with the object to be measured. appear. Therefore, the vibration of the stylus 13 is reliably restrained, and the vibration state is accurately detected by the vibration / detection element 12.

In the first embodiment, the control circuit 17
Is provided with a beat signal component extracting means 22 for detecting a beat signal generated by superimposing the first natural frequency ω1 and the second natural frequency ω2, the beat signal has a beat cycle of 2 Since the frequency of the beat signal component is determined by the difference between the two frequencies, the frequency of the beat signal component takes a value completely different from the natural frequency. Therefore, it is easy to electrically extract the generated beat signal component with a filter, a resonator, or the like, and the superposed state of the first natural frequency ω1 and the second natural frequency ω2 is reliably detected. Vibration generated at the time of contact can be positively detected,
This is effective for improving the S / N ratio.

Further, the stylus support 10 has X, Y
Since the plane is formed in a rectangular parallelepiped, the center position of the stylus support 10 can be easily matched with the origin of the X, Y, and Z axes, so that the touch signal probe can be easily assembled. . Also, stylus 13
Comprises a pair of first styli fixed along the X-axis and symmetrically arranged about the origin, and a pair of second styli fixed along the Y-axis and symmetrically arranged about the origin. With this configuration, a cross-shaped stylus in which the stylus 13 extends from the four side surfaces of the stylus support 10 in the X axis and the Y axis, respectively, can be provided.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the shape of the vibrator 26 is the first
The third embodiment is different from the first embodiment, and the other structure is the same as that of the first embodiment. In FIG. 7, the vibrator 26 of the second embodiment
The stylus support 10, a stylus 13 provided on one side surface of the stylus support 10 along the X axis, and a stylus 13 in a direction along the X axis and the Y axis of the stylus support 10. And a balance member 33 provided on a side surface not provided.

The balance member 33 provided on the X axis is
The block is a substantially rectangular parallelepiped and has a shape that is mechanically equivalent to the stylus 13. Here, whether or not they are mechanically equivalent is determined by the mass, rigidity, and the like of the balance member 33. The balance members 33 fixed to both side surfaces of the stylus support 10 along the Y axis have the same shape as the balance members 33 provided on the X axis, and are arranged at equal intervals around the origin. . The piezoelectric elements 12 are respectively arranged on upper and lower two planes orthogonal to the Z axis of the stylus support 10. With the vibration of the piezoelectric element 12, not only the stylus 13 but also the balance member 33 vibrates along the X axis or the Y axis.

The stylus support 10 comprises a probe body 25
Attached to. The probe support 25 extends in the Z-axis to support and fix the stylus support 10.
5A and a rod portion 25B integrally formed with the cylindrical portion 25A and extending in the X-axis direction. The cylindrical portion 25A is inserted through the center of the piezoelectric element 12 with a predetermined gap. In the second embodiment, the stylus 13 may be provided along the Y axis. In this case, the balance member 33 is provided along the X axis.

Therefore, in the second embodiment, in addition to the same effects as those of the first embodiment described above,
The stylus 13 is provided on the stylus support 10 along one of the X axis and the Y axis, and is in a direction along the X axis and the Y axis of the stylus
Since the balance member 33 having a shape that is mechanically equivalent to the stylus 13 is provided in a portion where the stylus 13 is not provided, the stylus 13 is moved along the one of the X axis and the Y axis. Even if the vibrator 26 has an irregular structure, the balance member 33 balances the vibration with the stylus 13 so that highly accurate measurement can be performed.

The present invention is not limited to the above embodiments, but includes the following modifications as long as the object of the present invention can be achieved. For example, in each of the above embodiments, the piezoelectric element 12
However, the present invention is not limited to this, and another actuator may be used. Further, the vibration / detection means may be provided on only one plane of the stylus support 10. Further, the stylus support 10 and the piezoelectric element 12
May have a planar circular shape.

Further, in the above-described embodiment, the vibrator 16 has a vibration frequency equal to the second natural frequency ω 2 of the vibrator 16.
And the vibration component of the first natural frequency ω1 in the vibration generated when the stylus 13 comes into contact with the object to be measured is superimposed. In the present invention, the reverse of the above-described embodiment, that is,
The vibrator 16 is vibrated at a vibration frequency equal to the first natural frequency ω1 of the vibrator 16, and the second natural frequency ω2 of the vibration generated when the stylus 13 contacts the object to be measured.
May be superimposed.

[0039]

Therefore, according to the present invention, when the touch signal probe is formed in a cross shape, it is possible to perform the measurement with high accuracy and to reduce the size.

[Brief description of the drawings]

FIG. 1 is a perspective view of a touch signal probe according to a first embodiment of the present invention.

FIG. 2 shows a vibration mode of the vibrator according to the first embodiment, in which (A) is a schematic plan view showing a basic structure of the vibrator,
(B) is a schematic plan view showing the first-order mode resonance, and (C) is a schematic plan view showing the first-order mode resonance.
FIG. 4 is a schematic plan view showing next mode resonance.

3A and 3B show a vibration mode of the conventional straight vibrator shown in FIG. 8, wherein FIG. 3A is a schematic plan view showing a basic structure of the vibrator, and FIG. Figure,
(C) is a schematic plan view showing a second-order mode resonance.

4A and 4B are graphs showing resonance characteristics of the vibrator according to the first embodiment, in which FIG. 4A shows a normal state, and FIG. 4B shows an amplitude at a second natural frequency; This shows a case where the amplitude is substantially the same as the amplitude at the time.

FIG. 5 is a block diagram illustrating a specific configuration of a control circuit according to the first embodiment.

FIG. 6 is a graph showing a relationship between time and a DC level-converted amplitude amount.

FIG. 7 is a perspective view of a touch signal probe according to a second embodiment of the present invention.

FIG. 8 is a perspective view showing a touch signal probe according to a conventional example.

FIG. 9 is a graph showing a relationship between frequency and amplitude,
(A) shows a case where the Q value is small, and (B) shows a case where the Q value is large.

FIG. 10A is a graph showing the relationship between vibration displacement and time due to contact of the stylus with the object to be measured, and FIG.
Is a graph showing the relationship between time and vibration displacement caused by the stylus colliding with the object to be measured, and FIG. 4C is a graph showing the relationship between the amount of amplitude converted into a DC level and time.

[Explanation of symbols]

 Reference Signs List 10 Stylus support 12 Vibration / detection means (piezoelectric element) 13 Stylus 16, 26 Vibrator 17 Control circuit 22 Beat signal component extraction means 33 Balance member

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01B 21/00-21/32 G01B 5/00-5/30

Claims (4)

(57) [Claims] 1. A stylus support centered on an origin of an X axis, a Y axis and a Z axis orthogonal to each other, and a stylus provided on the stylus support and fixed along at least one of the X axis and the Y axis. And a vibrator arranged at a plane perpendicular to the Z-axis of the stylus support, vibrating the vibrator at a predetermined frequency, and detecting a state of vibration that changes when the stylus comes into contact with the object to be measured. A touch signal probe for detecting contact with the object to be measured because the state of vibration changes when the stylus comes into contact with the object to be measured. The vibrator is vibrated at a vibration frequency equal to one of the primary natural frequency ω1 and the secondary natural frequency ω2 (ω2 ≠ ω1), and is generated when the stylus comes into contact with the object to be measured. First-order vibration Frequency ω1
A touch signal probe for enhancing a state change of vibration when the stylus comes into contact with an object to be measured by superimposing a vibration component of the other one of the second natural frequency ω2 and the second natural frequency ω2. 2. A touch signal probe according to claim 1, wherein a beat signal component for detecting a beat signal generated by superimposing said first natural frequency ω1 and said second natural frequency ω2 is extracted. A touch signal probe comprising means. 3. The touch signal probe according to claim 1, wherein the stylus is fixed along the X-axis and symmetrically arranged with respect to an origin.
The second fixed along the Y-axis and symmetrically arranged around the origin
And a stylus pair. 4. The touch signal probe according to claim 1, wherein the stylus is provided on the stylus support along one of an X-axis and a Y-axis. A touch signal probe, characterized in that a balance member having a shape that is mechanically equivalent to the stylus is provided in a portion along the Y axis where the stylus is not provided.