JP3404259B2 - 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 used for measuring the shape of an object to be measured by a coordinate measuring machine or the like.

[0002]

BACKGROUND ART A coordinate measuring machine or the like is known as a measuring machine for measuring the shape and size of an object to be measured. In order to detect coordinates and position in that case, a stylus is used as a measuring machine. A touch signal probe is used which is provided with a contact ball at the tip portion of and which detects that the contact ball contacts the object to be measured. As this touch signal probe, a stylus is provided with a detection element such as a piezoelectric element, and the impact when the contact ball at the tip of the stylus contacts the object to be measured is detected by the detection element, and there is a conventional example in which contact detection is performed. This conventional example has an advantage that the structure is relatively simple, but has a disadvantage that the sensitivity is different depending on from which direction the contact ball comes into contact, that is, it has direction dependency.

Therefore, the applicant of the present invention has filed a patent application as a touch signal probe having a simple structure and no direction dependence.
I proposed a touch signal probe shown in 9-32149.
This touch signal probe has a structure in which four piezoelectric elements are attached at 90-degree intervals to a substantially columnar stylus having a contact sphere that comes into contact with the object to be measured at the tip, and the contact signal is output from the signal output from the piezoelectric element. circuitry for generating is shown in Figure 1 1.

[0004] In FIG. 1 1, the signal output from the piezoelectric elements 21 to 24, after being amplified by the amplifier circuit 31 to 34 is the V ₁ ~V _4, the piezoelectric element 21 in the front and back of each other, The signals V ₁ and V ₃ output from 23 are the difference (V
₁ -V ₃₎ is calculated by the differential amplifier circuit 41, the signal V ₂ output from the piezoelectric elements 22 and 24 on the front and back of each other,
V ₄ is the difference (V ₂ -V ₄₎ is calculated by the differential amplifier circuit 42. The signals generated by the differential amplifier circuits 41 and 42 are squared by the squaring circuits 71 and 72, respectively, and then added by the adding circuit 8 to form one signal V _v . This signal V _v is a signal corresponding to the vibration component in the direction perpendicular to the stylus axis.

Further, the signals V _{1 to} V ₄ output from the piezoelectric elements 21 to 24 and amplified by the amplifier circuits 31 to 34 are:
The sum of these is calculated in the adder circuit 5, and the adder circuit 5 generates the signal V _H. This signal V _H is a signal corresponding to the vibration component in the stylus axis direction. The signal V _H calculated by the adder circuit 5 is compared with the reference value by the comparison circuit 14, and the first contact signal S _H output when this signal exceeds the reference value is transmitted via the OR circuit 13. , On the other hand, the adder circuit 8
The comparison circuit 12 compares the signal Vv output from the reference signal with a reference value, and when the reference value is exceeded, the second contact signal Sv output is transmitted via the OR circuit 13.

When the angle in the plane including the stylus axis is α and the angle in the plane perpendicular to the stylus axis is β, the signal Vv corresponding to the vibration component in the direction perpendicular to the stylus axis is extracted. , V ₁₃ and V ₂₄ are calculated, it is possible to fix α and reduce the direction dependency when the contact is made from the direction in which only β changes. However, the signal V _H corresponding to the vertical vibration component in the stylus axis direction reaches the threshold value of the comparison circuit 14, and the comparison circuit 1
And time in which the first contact signal S _H reaches a certain level outputted from the 4, the signal corresponding to the lateral vibration component of the stylus axis direction perpendicular Vv reaches the threshold of the comparator circuit 12, is output from the comparator circuit 12 There is a time difference Δt with the time when the second contact signal Sv reaches a certain level.

Due to this time difference Δt, when a contact is made from a direction in which α changes, direction dependency occurs. Δt is because there is a difference between the vibration component generated by the contact and perpendicular to the stylus axis, that is, the speed at which the transverse wave is transmitted to the piezoelectric element, and the vibration component generated by the contact in the stylus axis direction, that is, the speed at which the longitudinal wave is transmitted to the piezoelectric element. It is the time difference that occurs. Therefore, the time difference Δ is set in advance by the delay circuit 75.
By delaying the first contact signal S _H by t, it is possible to reduce the direction dependency when the contact is made from the direction in which α changes.

[0008]

When performing coordinate detection or position detection using a touch signal probe, it is common to replace the stylus.
The touch signal probe shown in No. 9-32149 assumes a constant stylus, not a replacement. Depending on the size and shape of the stylus,
The time difference Δt is different, and when the stylus is changed, when the stylus is contacted from a direction in which α changes, the time difference Δt causes direction dependency.

It is an object of the present invention to provide a touch signal probe which does not depend on the direction of any stylus.

[0010]

Therefore, according to the present invention, the time difference between the first contact signal corresponding to the longitudinal vibration component and the second contact signal corresponding to the lateral vibration component is obtained for each stylus to be mounted, and The purpose is to correct the time difference and achieve the above-mentioned object. Specifically, the touch signal probe according to the present invention, a substantially columnar stylus having a contact ball that contacts the object to be measured at the tip, a detection piezoelectric element for detecting that the contact ball has contacted the object to be measured. By arranging a plurality of signals and calculating the sum, difference and sum of squares of the signals output from these detection piezoelectric elements, the signal corresponding to the longitudinal vibration component along the axial direction of the stylus and the axial direction of the stylus are orthogonal. And a signal corresponding to the lateral vibration component along the direction, the first contact signal is generated from the signal corresponding to the longitudinal vibration component, and the second contact signal is generated from the signal corresponding to the lateral vibration component. A touch signal probe for generating a touch signal by a logical sum of the first touch signal and the second touch signal, wherein the second touch is generated after the first touch signal is generated. The signal is A time difference measuring circuit for measuring a time difference until the generation, and a delay circuit for delaying the first contact signal by a set delay time when obtaining a logical sum of the first contact signal and the second contact signal The time difference measuring circuit is configured to perform a delay time setting operation for setting the time difference in the delay circuit as the delay time each time the stylus is replaced.

For measurement, when the touch signal probe of the present invention is moved and the contact ball of the stylus contacts the object to be measured, the impact force at the time of contact is detected by the detecting piezoelectric element. At this time, a detection signal is output from each detection piezoelectric element,
First, the sum and difference of the signals output from each of the detection piezoelectric elements are generated. The sum of the signals output from each detection piezoelectric element is calculated in order to remove the bending strain component acting on the stylus axis and extract the longitudinal vibration component acting in the stylus axis direction. The reason why the difference between the signals output from the elements is calculated is to extract the lateral vibration component acting on the stylus axis from the signals output from the respective piezoelectric detection elements and having different phases.

After that, a sum of squares is generated for these difference signals. The sum of squares of each signal is generated so that the maximum value of the signal output from each detection piezoelectric element is made completely constant regardless of the angle between the mounting direction of the detection piezoelectric element and the contact direction with the DUT. This is because Furthermore, a large detection signal can be obtained, and the measurement accuracy can be improved. A first contact signal corresponding to a longitudinal vibration component along the axial direction of the stylus based on signals generated from the sum, difference and sum of squares , and lateral vibration along a direction orthogonal to the axial direction of the stylus. A second touch signal is generated corresponding to each component, and a touch detection signal is generated by a logical sum from the first touch signal and the second touch signal. In generating the contact detection signal, the first contact signal that forms the maximum value earlier in time is delayed by the delay circuit by the predetermined time difference Δt, so that the same contact detection signal is generated regardless of the contact portion of the contact ball. To do.

In the present invention, prior to the measurement, the contact ball of the stylus attached is brought into contact with the object to be measured at a predetermined angle, for example, 45 degrees, and the first contact signal at this time is generated before the first contact signal is generated. The time difference Δt until the second touch signal is generated is obtained by the time difference measuring circuit. Therefore, in the present invention,
Even if the shape of the stylus to be mounted changes, the time difference Δt between the first contact signal and the second contact signal is corrected for each stylus, so that direction dependency is eliminated and highly accurate measurement can be performed.

Here, in the present invention, the time difference measuring circuit outputs a signal from the first touch signal to the second touch signal, and a flip-flop circuit that outputs the output signal. It may be configured to include a clock circuit that clocks the time when the output signal is output by the circuit and calculates the time difference. In this configuration, the time difference Δt between the first contact signal and the second contact signal of the stylus attached is
Is calculated by the flip-flop circuit and the clock circuit, and after the time difference Δt is calculated, normal measurement is performed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. Here, the same components as those shown in FIG. 1 are designated by the same reference numerals to simplify the description. FIG. 1 shows an overall configuration of a touch signal probe according to an embodiment of the present invention, (A) shows a state before a piezoelectric element is attached, and (B) shows a state after the piezoelectric element is attached. Indicates the state of.

In FIG. 1 (A), the touch signal probe of this embodiment has a contact ball 1A at the tip which contacts the object to be measured.
The four columnar stylus 1 having four piezoelectric elements 21 to
The stylus 1 has a structure in which 24 is attached. The stylus 1 is integrally formed with the contact ball 1A, a stylus body 1B having a circular cross section with the contact ball 1A attached to one end, and the other end of the stylus body 1B. A piezoelectric element supporting portion 1C,
The piezoelectric element support portion 1C has a screw portion 1D provided at an end portion thereof and attached to a probe body (not shown), and these members are arranged on the stylus shaft.

The piezoelectric element supporting portion 1C is a rectangular parallelepiped having a square cross section orthogonal to the stylus axis, and the piezoelectric elements 21 to 24 are fixed to the respective side surfaces of the rectangular parallelepiped over the entire surface thereof with an adhesive or the like. Of these, the piezoelectric elements 21 and 23 are in a front-back relationship with each other with the piezoelectric element supporting portion 1C interposed therebetween, and the piezoelectric elements 22 and 24 are the piezoelectric elements 21 and 23.
At the position adjacent to, there is a front-back relationship with each other. As shown in FIG. 1B, each of the piezoelectric elements 21 to 24 has a planar rectangular shape whose longitudinal direction is parallel to the stylus axis.

FIG. 2A is a front view showing a case where the contact ball 1A of the touch signal probe is brought into contact with the object to be measured from a direction orthogonal to the stylus axis, and FIG.
It is a graph which shows the time change of the output of one piezoelectric element 21 in the case of (A). In FIG. 2B, after the contact with the object to be measured, the output of the piezoelectric element 21 has a maximum value V _O at a time point To determined by the natural frequency of the stylus 1 and the like.

The magnitude of the maximum value V _O is the angle formed by the mounting direction of the piezoelectric element 21 and the direction in which the stylus 1 contacts the object to be measured, that is, the angle Θ about the axis of the stylus 1 of the piezoelectric element 21 (Fig. 3), and as shown in FIG. 4, it changes in a sinusoidal shape with a cycle of 360 degrees. It can be seen that the output maximum value V _O becomes the maximum value V _max when the stylus 1 contacts the object to be measured at an angle (Θ = 0) at which the piezoelectric element 21 is susceptible to bending deformation.

FIG. 5 is a block diagram for generating a contact signal by the outputs from the four piezoelectric elements 21-24.
FIG. 6 is a circuit diagram thereof. In FIG. 5 and FIG. 6, the signals output from the respective piezoelectric elements 21 to 24 are the amplification circuit 3
The signals V ₁ and V ₃ output from the piezoelectric elements 21 and 23 which are in a front-back relationship with each other after being amplified by Vs ₁ to 34 into V _{1 to} V ₄ have a difference (V ₁ −V ₃ ). Differential amplifier circuit 4
1, the piezoelectric elements 22, which are in a front-back relationship with each other,
The signals V ₂ and V ₄ output from 24 are the difference (V ₂ −
V ₄ ) is calculated by the differential amplifier circuit 42.

Here, the piezoelectric elements 21, 23 (22, 2
The difference (V ₁ −V ₃ ) (V ₂ −V ₄ ) between the output signals in ₄ ) is calculated from the piezoelectric elements 21, 23 (22, 24) having different mounting angles of 180 degrees about the stylus axis. This is because the phases of the output signals are different by 180 degrees, and the lateral vibration component along the direction orthogonal to the axial direction of the stylus axis is extracted by this calculation. The sum of the signals V _{1 to} V ₄ output from the piezoelectric elements 21 to 24 and amplified by the amplifier circuits 31 to 34 is calculated by the adder circuit 5. Four piezoelectric elements 21
The reason for calculating the sum of ˜24 is to remove the lateral vibration component acting on the stylus axis and extract the longitudinal vibration component acting on the stylus axis direction. However, in this embodiment,
When extracting the longitudinal vibration component, all four piezoelectric elements 2
The present invention is not limited to the one that calculates the sum of the output signals of 1 to 24, and two piezoelectric elements 21,
Alternatively, the sum of output signals from 23 or the piezoelectric elements 22 and 24 may be calculated. The contact detection circuit 6 generates a detection signal from the signals generated by the differential amplifier circuits 41 and 42 and the signal generated by the addition circuit 5. The sum signal V _H calculated by the adder circuit 5 is obtained by the following equation, where K ₁ is the amplification factor.

[0022]

[Equation 1]

The signals generated by the differential amplifier circuits 41 and 42 are squared by the squaring circuits 71 and 72, respectively,
The signal is added by the adder circuit 8 to obtain the signal Vv. This signal Vv
Is a signal corresponding to the lateral vibration component along the direction perpendicular to the stylus axis. Here, the squared addition is performed so that the output signals from the piezoelectric elements 21, 23 (22, 24) having different 90-degree mounting angles are constant regardless of Θ. The signal Vv calculated by the adder circuit 8 is obtained by the following equation, where K ₂ is an amplification factor.

[0024]

[Equation 2]

The time for forming the maximum value of the signal Vv and the signal V
_The times at which _H forms a local maximum are generally different. In other words, since the rigidity in the longitudinal direction is generally higher than the bending rigidity,
The signal V _H is earlier in time. Therefore, by delaying the signal V _H corresponding to the vertical vibration component that forms the maximum value earlier in time by a predetermined time, the maximum value is formed at the same timing as the signal corresponding to the horizontal vibration component. The same output can be generated no matter where it touches 1A. Specifically, the signal V _H calculated by the adder circuit 5
Is compared with a reference value (H level) by a comparison circuit 14, and is output when this signal exceeds the reference value (H level).
After delaying the contact signal S _H of
It is generated via the circuit 13. Further, the signal Vv calculated by the adder circuit 8 is compared with the reference value (H level) by the comparison circuit 12, and the second contact signal Sv output when this signal exceeds the reference value (H level) is obtained. It is generated via the OR circuit 13.

[0026] In this embodiment, the angle alpha (see FIG. 7) at a predetermined angle in the plane including the stylus axis, for example, in contact with the workpiece the stylus 1 as 45 degrees, the first contact signal S _H when the The time difference Δt from when the second contact signal Sv is generated to when the second contact signal Sv is generated is measured by the time difference measuring circuit 16. Here, the contact angle α of the stylus 1 to the object to be measured is not limited to 45 degrees. The angle should be such that two components, a vertical vibration component in the stylus axial direction and a lateral vibration component in the direction orthogonal to the axial direction, are generated, and theoretically 0
It may be anything other than 90 degrees. However, in practice, since it is necessary to detect the time when each vibration component is generated, the amplitude of each vibration component must be large enough to some extent. Therefore, 45 degrees is preferable.
The time difference measuring circuit 16 performs a delay time setting operation of setting the time difference Δt as a delay time in the delay circuit 15 every time the stylus 1 is replaced, and its configuration is shown in FIG.
As shown in, a flip-flop circuit 18 that outputs an output signal from the generation of the first contact signal S _H to the generation of the second contact signal Sv, and the output signal is output by the flip-flop circuit 18. And a time counting circuit 19 for measuring the time and calculating the time difference Δt.

The flip-flop circuit 18 has a reset /
First set flip-flop (RS-FF)
Of the output of the comparator circuit 1 4 contact signal S _H is sent to connected to the cell Tsu City of terminals, connects the output of the comparator circuit 1 2 in which the second contact signal S _v is sent to the reset terminal, The output signal S ₁ is at the H level from the time when the first contact signal S _H goes to the H level until the second contact signal S _v goes to the H level (see FIG. 9). The clock circuit 19 outputs a clock generator 51, an AND circuit 52 that receives and outputs the signal of the clock generator 51, the output signal S ₁ of the flip-flop circuit 18 and the delay time setting operation signal, and a signal from the AND circuit 52. It is composed of an up counter 53 which calculates a time difference Δt from the time when the output signal S ₁ is at H level. This up counter 5
3 is provided with a reset terminal 53A, and this reset terminal 53A is connected to a control unit (not shown) of the coordinate measuring machine. When the delay operation setting signal is output during the delay operation, the up counter 53 is reset and Δ
Time t.

The delay circuit 15 receives the signal from the clock generator 51, the first contact signal S _H and the inverted signal of the delay time setting operation signal and outputs the AND circuit 56, and the AND circuit 56. Signal and first
The down counter 57 is loaded with the time difference Δt from the up counter 53 in response to the contact signal S _H of the down counter 57 and the clock signal is input to start down counting.
It consists of and.

The down counter 57 outputs a BORROW signal when its value becomes 0, which is a signal S _{HD obtained} by delaying the first contact signal S _H by the time difference Δt.
Used as. In the present embodiment, the configurations of the delay circuit 15 and the time difference measuring circuit 16 are not limited to the configurations described above. For example, the clock generator 51 is not shared by the delay circuit 15 and the time difference measuring circuit 16,
It may be provided separately.

Therefore, in this embodiment, the contact ball 1 is attached to the tip.
Piezoelectric elements 21 to 24 for detecting that the contact ball 1A has come into contact with an object to be measured are arranged on a substantially columnar stylus 1 having A, and the stylus 1 is a piezoelectric element supporting portion for supporting and fixing the piezoelectric elements 21 to 24. 1C, the piezoelectric element supporting portion 1C is a regular polygonal body whose cross section orthogonal to the axis of the stylus 1 is a regular polygonal shape, and the piezoelectric elements 21 to 21 are provided on at least two sides of each side surface of the regular polygonal body. 24 is attached to each of the piezoelectric elements 21 to 24, the sum, the difference and the sum of squares of the signals output from the piezoelectric elements 21 to 24 are generated, and the contact detection signal is generated based on the generated signals. By processing the signals output from ˜24, directional dependence can be eliminated and highly accurate measurement can be performed.

That is, by calculating the sum of the signals output from the piezoelectric elements 21 to 24, the bending strain component acting on the stylus axis is removed to extract the longitudinal vibration component acting in the stylus axis direction, and the piezoelectric element is extracted. By calculating the difference between the signals output from 21-24, the piezoelectric elements 21-2
The lateral vibration components acting on the stylus axis are extracted on the basis of the signals with different phases output from 4, and the sum of squares of the sum signal and the difference signal of these components is respectively generated, so that the stylus axis is generated. The maximum value of the signal output from each of the piezoelectric elements 21 to 24 having different mounting angles is defined by the angle Θ between the mounting direction of the detecting piezoelectric element and the contact direction with the object to be measured.
Since it is constant regardless of the measurement accuracy, it is possible to improve the accuracy of the measurement regardless of the contact angle of the measurement sphere 1A with the object to be measured. Moreover, the piezoelectric elements 21 to 24 are attached to the side surfaces of the polygonal body.
Since the structure is attached, the structure of the touch signal probe can be simplified.

Further, in this embodiment, the piezoelectric element supporting portion 1
The cross section of C is square, and total 4 on each side.
Since the piezoelectric elements 21 to 24 are attached to each other, the piezoelectric element supporting portion 1C of the piezoelectric elements 21 to 24 is included.
Two differential signals (V ₁ -V ₃ ), (V ₂ -V ₄ ) output from two sets of detection piezoelectric elements 21, 23 (22, 24) located in front and back relation with each other across And 4
Since the first and second contact detection signals S _H and Sv are generated from the sum signal output from all the piezoelectric elements 21 to 24, they are separated from each other about the stylus axis by 9
Since the contact detection signal is generated based on the signals output from the four piezoelectric elements 21 to 24 arranged at 0 degree intervals, accurate measurement can be performed.

Further, the first touch signal S_HAnd second contact
To generate a touch signal from the logical sum of the signal Sv
The first touch signal S_HIs delayed by a time difference Δt
Since the structure is used, the object to be measured is located on the measuring ball 1A.
The same output is generated even if the
It is possible to improve the accuracy of measurement. In addition, this embodiment
Then, the first contact signal S_HSecond contact after the occurrence of
Time difference measurement time to measure the time difference until signal Sv occurs
Path 16 and the first touch signal S _HAnd the second contact signal Sv
When determining the logical sum of the_HIs set
A delay circuit 15 for delaying the delay time Δt
The contact detection circuit 6 and the time difference measurement circuit 16 is
Every time the Iras 1 is replaced, the time difference Δt is used as the delay time.
The configuration is such that a delay time setting operation set in the delay circuit 15 is performed.
Therefore, the contact ball of the stylus 1 attached before the measurement
1A is contacted with the DUT at a predetermined angle, for example 45 degrees.
The first contact signal S at this time_HSecond from the occurrence of
Measure the time difference Δt until the contact signal Sv is generated.
Stylus 1 to be attached by asking by the circuit
Even if the shape of the stylus changes, the first touch signal for each stylus 1
S _HAnd the time difference Δt between the second contact signal Sv is corrected.
Therefore, from this point as well, the direction dependency is eliminated and the accuracy is high.
Can measure.

Further, since the delay time setting operation and the normal measurement operation are distinguished by the delay time setting operation signal, the wrong time difference Δt is not used. Therefore, high accuracy of measurement is ensured.

The present invention is not limited to the above-described embodiment, but includes the following modifications as long as the object of the present invention can be achieved. For example, in the present invention, as shown in FIG. 10, the load signal generating circuit 61 may be included. The load signal generating circuit 61 generates a load signal to the down counter 57 after a predetermined time has elapsed from the output of the signal S _HD or after the delay time setting operation is completed .

Further, in order to increase the output from the piezoelectric elements 21 to 24, the central portion of the piezoelectric element supporting portion 1C is formed so as to be constricted, and both ends of the piezoelectric elements 21 to 24 are piezoelectric element supporting portions. The structure may be such that it is supported and fixed to both side portions of 1C, and a central portion thereof forms a gap with the piezoelectric element supporting portion 1C. In this structure, since the rigidity of the piezoelectric element support portion 1C is lower than that of the piezoelectric element support portion 1C of FIG. 1, the amount of deformation of the piezoelectric elements 21 to 24 increases. Therefore, the outputs of the piezoelectric elements 21 to 24 become large, so that the measurement accuracy can be improved.

Further, in the present invention, the piezoelectric element supporting portion 1C may have a regular triangular cross section, and a total of three piezoelectric elements 21 to 23 may be attached to each side surface thereof. The cross section of 1C may be formed into a regular pentagon, a regular hexagon, or the like. When the cross section of the piezoelectric element support portion 1C is an equilateral triangle, the outputs of the three piezoelectric elements 21 to 23 are squared and added, and when contacting the object to be measured from the direction orthogonal to the stylus axis, the angle Θ is obtained. A constant output that does not depend, that is, a bending strain component can be obtained, and a vertical strain component can be obtained by adding the outputs of the three piezoelectric elements 21 to 23. The present invention can be applied to these signals.

Further, in the above embodiment, the piezoelectric element 21 is used.
Although the case where four to 24 are installed has been described, in the present invention, two piezoelectric elements are provided on two side surfaces adjacent to each other of the piezoelectric element support portion 1C.
A structure in which the individual piezoelectric elements 21 and 22 are fixed to each other may be used .

Further, in the above, the piezoelectric element supporting portion 1
The case where the cross section of the central portion of C is a regular polygon has been described, but in the present invention, the central portion of the piezoelectric element supporting portion 1C may have a circular cross section. That is, in the present invention, in the piezoelectric element supporting portion 1C, it is sufficient if the portion that directly supports the piezoelectric elements 21 to 24 has a regular polygonal cross section, and the piezoelectric elements 21 to 24.
The shape of the portion that does not come into contact with is not limited.

[0040]

As described above, according to the present invention, a detection piezoelectric for detecting the contact of the contact ball with the object to be measured is provided on a substantially columnar stylus having a contact ball at the tip for contacting the object to be measured. A plurality of elements are arranged, and a signal corresponding to a longitudinal vibration component along the axial direction of the stylus and an axial direction of the stylus are calculated by calculating the sum, difference and sum of squares of signals output from these detection piezoelectric elements. And a signal corresponding to a lateral vibration component along a direction orthogonal to
A first contact signal is generated from the signal corresponding to the longitudinal vibration component, a second contact signal is generated from the signal corresponding to the lateral vibration component, and the first contact signal and the second contact signal are generated. A touch signal probe for generating a contact signal by OR of the time difference measuring circuit for measuring a time difference between the generation of the first contact signal and the generation of the second contact signal; A delay circuit that delays the first contact signal by a set delay time when the logical sum of the contact signal and the second contact signal is calculated, and the time difference measurement circuit replaces the stylus each time. Since the delay time setting operation for setting the time difference as the delay time in the delay circuit is performed, it takes time to generate the touch detection signal by the logical sum from the first touch signal and the second touch signal. The first contact signal for forming a fast maximum value is by delayed by a predetermined time difference Δt by the delay circuit, the same contact detection signal regardless of the contact portion of the contact sphere is generated. Moreover, even if the shape of the stylus to be mounted changes, the time difference Δt between the first contact signal and the second contact signal is corrected for each stylus, so that the direction dependency is eliminated and highly accurate measurement can be performed.

[Brief description of drawings]

1A and 1B show a touch signal probe according to an embodiment of the present invention, FIG. 1A is a perspective view showing a state before a piezoelectric element is attached, and FIG. 1B is a perspective view after the piezoelectric element is attached. It is a perspective view showing the state.

FIG. 2A is a front view showing a case in which the contact ball of the touch signal probe contacts the object to be measured from a direction orthogonal to the stylus axis, and FIG. 2B shows one of the cases in FIG. It is a graph which shows the time change of the output of a piezoelectric element.

FIG. 3 is a perspective view of a touch signal probe for explaining an angle Θ between the mounting direction of the piezoelectric element and the direction in which the stylus contacts the object to be measured.

FIG. 4 is a graph showing the relationship between the angle Θ and the output maximum value V _o of the piezoelectric element.

FIG. 5 is a block diagram showing a configuration for generating a contact signal from a signal output from a piezoelectric element.

FIG. 6 is a circuit diagram showing a configuration for generating a contact signal from a signal output from a piezoelectric element.

FIG. 7 is a side view of a stylus for explaining an angle α formed by a direction orthogonal to the stylus axis and a direction in which a contact ball hits an object to be measured.

FIG. 8 is a circuit diagram showing configurations of a delay circuit and a time difference measuring circuit.

FIG. 9 is a graph showing the relationship between the first contact signal S _H , the second contact signal S _v, and the output signal S ₁ of the flip-flop circuit.

FIG. 10 shows a modified example of the present invention and is a diagram corresponding to FIG. 8.

FIG. 11 is a circuit diagram illustrating a touch signal probe described as background art and showing a configuration for generating a contact signal from a signal output from a piezoelectric element.

[Explanation of symbols]

1 stylus 1A contact ball 1C Piezoelectric element support 15 Delay circuit 16 time difference measurement circuit 18 Flip-flop circuit 19 Clock circuit 20 Reset circuit 21-24 Piezoelectric element

Claims (2)

(57) [Claims] 1. A detection device for detecting a plurality of piezoelectric elements for detecting the contact of the contact ball with an object to be measured, which is arranged on a substantially columnar stylus having a contact ball at the tip thereof for contacting the object to be measured. A signal corresponding to a longitudinal vibration component along the axial direction of the stylus and a lateral vibration component along a direction orthogonal to the axial direction of the stylus by calculating the sum, difference and sum of squares of the signals output from the piezoelectric element. And a signal corresponding to the vertical vibration component, a first contact signal is generated from the signal corresponding to the vertical vibration component, and a second contact signal is generated from the signal corresponding to the lateral vibration component. A touch signal probe for generating a touch signal by a logical sum of a touch signal and the second touch signal, the time difference from the generation of the first touch signal to the generation of the second touch signal. Time to measure Difference measuring circuit,
A delay circuit that delays the first contact signal by a set delay time when obtaining a logical sum of the first contact signal and the second contact signal, and the time difference measuring circuit replaces the stylus. The touch signal probe is configured to perform a delay time setting operation in which the time difference is set as the delay time each time the delay circuit is set in the delay circuit. 2. The touch signal probe according to claim 1, wherein the time difference measuring circuit outputs an output signal from the generation of the first contact signal to the generation of the second contact signal. A touch signal probe comprising: a flip-flop circuit; and a clock circuit that clocks a time when an output signal is output by the flip-flop circuit to calculate the time difference.