JPH10288502A - Touch signal probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch signal probe that is simple in structure and has no directional dependability. SOLUTION: A stylus 1 is provided with a detection element supporting part 1C for supporting and securing four deformation detecting elements (piezoelectric elements) 21 to 24, and this detection element supporting part 1C is a regular polyhedron whose section being orthogonalized with a shaft of the stylus 1 is formed into a regular polygon. Each of these deformation detecting elements 21 to 24 is attached to respective sides of this regular polyhedron, and the arithmetic processing of a sum, a difference and a square sum or the like is carried out on each signal to be outputted from these deformation detecting elements 21 to 24, and thus a contact detecting signal is generated on the basis of the result of the arithmetic processing. In succession, the sum of signals to be outputted from these elements 21 to 24, extracting a strain component acting on the stylus axial direction, and likewise any difference in signals to be outputted from these elements 21 to 24 is operated, extracting the bending strain component acting on the stylus shaft.

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 and the like of an object to be measured by a coordinate measuring machine or the like.

[0002]

2. Description of the Related Art A three-dimensional measuring machine or the like is known as a measuring machine for measuring the shape and dimensions of an object to be measured, but a stylus is used for measuring coordinates and position in such a case. A touch signal probe is provided that has a contact portion at the tip of the sensor and detects that the contact portion has come into contact with the object to be measured. Conventional examples of the touch signal probe are disclosed in Japanese Patent Publication No. Sho 60-48681 (conventional example 1), Japanese Patent Application Laid-Open No. 54-78164 (conventional example 2), and Japanese Patent Application Laid-Open No. 8-327308 (conventional example 3).

In Conventional Example 1, a measuring head or a measuring probe comprises a movable portion and a fixed portion, which are connected to each other via a seating mechanism. The movable part is composed of two divided members, and a measuring element (piezoelectric element) that responds to tension and compression with high sensitivity is provided between these members. In Conventional Example 2, a piezoelectric element is incorporated in a part of a stylus, a stylus is divided into two parts, a piezoelectric element is sandwiched between the divided styluses, and a piezoelectric element is attached to a contact portion provided at the tip of the stylus. It is a structure in which the element is worked up, and furthermore, the piezoelectric element is interposed between the contact portion and the stylus. In Conventional Example 3, a stylus is attached to the center of a disk-shaped substrate, and a plurality of piezoelectric elements are radially arranged around the stylus. In order to detect that the stylus has contacted the object to be measured, the sum of the absolute values of the signals output from the respective piezoelectric elements is detected.

[0004]

In the conventional examples 1 and 2,
When installing one piezoelectric element, when installing multiple piezoelectric elements, etc.
Various cases are disclosed. In general, a smaller number of piezoelectric elements has the advantage of lower cost because the stylus structure is simpler and easier to assemble, but it has insufficient detection accuracy in different directions and has direction dependency. become. On the other hand, when a plurality of piezoelectric elements (measuring elements) are incorporated, the direction dependency is reduced depending on the way of combining them, but there is a disadvantage that the structure becomes complicated.

[0005] Here, the direction dependency means the degree to which the response sensitivity of the measuring element differs depending on the contact point of the contact portion when the measuring ball at the tip of the stylus contacts the object to be measured. However, in the conventional example 1, although the measuring element is divided into one for X-axis measurement and one for Y-axis measurement, the direction dependency is not taken into consideration any more, and therefore, the improvement of the direction dependency is not necessarily sufficient. I can't say. Similarly, Conventional Example 2
Does not consider the relationship between the direction dependence and the arrangement of the piezoelectric elements. In Conventional Example 3, the sum of the absolute values of the signals output from the plurality of piezoelectric elements is calculated so that the detection sensitivity when the tip of the stylus comes into contact with the object to be measured does not have directivity. However, in the case where the device comes into contact with the object to be measured from a direction perpendicular to the stylus axis, the direction dependency of the detection sensitivity is not sufficiently improved. No mention is made of the case of contact from the stylus axis direction.

It is an object of the present invention to provide a touch signal probe which has a simple structure and has no direction dependency.

[0007]

Therefore, the present invention provides a contact detection signal based on a sum, a difference and a sum of squares of signals output from a deformation detection element attached to a side face of a detection element support of a regular polygon. It is intended to achieve the above purpose. Specifically, in the touch signal probe according to the present invention, a deformation detecting element that detects that the contact portion has contacted the object to be measured is disposed on a substantially columnar stylus having a contact portion at the tip thereof that contacts the object to be measured. In the touch signal probe described above, the stylus has a detection element support portion for supporting and fixing the deformation detection element, and the detection element support portion has a regular polygon whose cross section orthogonal to the axis of the stylus is a regular polygon. The deformation detection elements are attached to at least two of the side surfaces of the regular polygon, and arithmetic processing is performed on signals output from these deformation detection elements, and contact is made based on the result of the arithmetic processing. It is characterized by generating a detection signal.

For the measurement, when the contact portion of the stylus comes into contact with the object to be measured by moving the touch signal probe of the present invention, the impact force at the time of the contact is detected by the deformation detecting element. At this time, a detection signal is output from each deformation detection element, and an arithmetic process is performed on the signal output from each deformation detection element.
For example, first, a sum and a difference of these signals are generated. The reason for calculating the sum of the signals output from each deformation detection element is to remove the bending distortion component acting on the stylus axis and to extract the longitudinal distortion component acting in the stylus axis direction. The reason for calculating the difference between the output signals is to extract a bending distortion component acting on the stylus axis.

Thereafter, a sum of squares of the sum signal and the difference signal is generated. The reason for squaring each signal is to make the maximum value of the signal output from each deformation detection element completely constant irrespective of the angle between the mounting direction of the deformation detection element and the contact direction with the object to be measured. Further, by summing the squares of the signals, a large detection signal can be obtained, and the measurement accuracy can be improved. Generating a contact detection signal based on the signal generated from the sum of squares,
The coordinates at the point where the contact detection signal is generated are read as measured values. Therefore, in the present invention, high-precision measurement can be performed by eliminating the direction dependency by processing the signal output from each deformation detection element. Further, since the deformation detecting element is attached to the side surface of the polygon, the structure of the touch signal probe can be simplified.

Here, in the present invention, a structure may be employed in which a cross section of the detection element support section is square and a total of four deformation detection elements are attached to each side surface thereof. In this case, of these deformation detection elements, two differential signals output from two sets of deformation detection elements located in a front-to-back relationship with each other across the detection element support portion,
The configuration may be such that a contact detection signal is generated from a sum signal output from all four deformation detection elements or a sum signal output from two deformation detection elements located in a front-to-back relationship with each other. In this configuration, the contact detection signal is generated based on the signals output from the four deformation detection elements arranged at intervals of 90 degrees about the stylus axis, so that accurate measurement can be performed.

Further, a first contact signal is generated by squaring and summing two differential signals output from the two sets of deformation detecting elements located in the front-back relationship, and
Is compared with a reference value to generate a first detection signal, and a sum signal output from the four deformation detection elements or output from two deformation detection elements positioned in a front-to-back relationship. A second contact signal is generated from the sum signal, the second contact signal is compared with a reference value to generate a second detection signal, and after the second detection signal is delayed by a predetermined time, , A contact detection signal may be generated by a logical sum with the first detection signal. In this configuration, when generating the contact detection signal by the logical OR from the first contact signal and the second contact signal, the second contact that forms the local maximum value earlier in time is obtained.
Is delayed by a predetermined time, the same contact detection signal is generated regardless of the contact portion of the contact portion.

In addition, the sum signal output from each of the deformation detecting elements or the sum signal output from the two deformation detecting elements located in a front-to-back relationship is adjusted to be delayed by a predetermined time. After squaring a total of three signals, that is, a signal and two differential signals output from the deformation detection elements positioned in the front-back relationship, a contact detection signal may be generated using the summed signal. In this configuration, as described above, the same output is generated irrespective of the contact portion of the contact portion. Further, the deformation detecting element may be constituted by a piezoelectric element or a strain gauge. According to this configuration, the impact force when the contact portion of the stylus comes into contact with the object to be measured can be reliably detected by the deformation detection element.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the entire configuration of a touch signal probe according to a first embodiment of the present invention. FIG. 1A shows a state before a piezoelectric element as a deformation detecting element is attached, and FIG. This shows the state after the device has been attached.

Referring to FIG. 1A, a touch signal probe according to a first embodiment has a contact portion 1 at its tip which comes into contact with an object to be measured.
And four piezoelectric elements 21 on the substantially columnar stylus 1
The stylus 1 is formed integrally with the contact portion 1A, a stylus body 1B having a circular cross section with the contact portion 1A attached to one end, and the other end of the stylus body 1B. Detection element support 1C
And a screw portion 1D provided at an end of the detection element support portion 1C and attached to a probe body (not shown), and these members are arranged on a stylus shaft.

The detecting 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 side surfaces of the rectangular parallelepiped with an adhesive or the like on the entire surface. Among them, the piezoelectric elements 21 and 23 are in a front-to-back relationship with each other across the detection element supporting portion 1C, and the piezoelectric elements 22 and 24 are
Are adjacent to each other at the position adjacent to the. 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 portion 1A of the touch signal probe comes into contact with an object to be measured from a direction orthogonal to the stylus axis, and FIG. 2B is a front view.
6 is a graph illustrating a temporal change in the output of one piezoelectric element 21 in the case of FIG. 2B, the output of the piezoelectric element 21 reaches a local maximum value Vo at a point of time To determined by the natural frequency of the stylus 1 or the like after contact with the object to be measured.

The magnitude of the maximum value Vo is determined by the angle between 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 of the piezoelectric element 21 around the axis of the stylus 1 (FIG. 3). 4), and changes sinusoidally at a cycle of 360 degrees as shown in FIG. Output maximum
It can be seen that Vo reaches the maximum value Vmax when the object to be measured comes into contact with the stylus 1 at an angle (θ = 0) at which the piezoelectric element 21 is easily subjected to bending deformation.

FIG. 5 is a block diagram for generating a contact signal based on the output from the four piezoelectric elements 21 to 24.
FIG. 6 is a circuit diagram thereof. 5 and 6, the signals output from the piezoelectric elements 21 to 24
After being amplified is a V ₁ ~V ₄ at 1 to 34, the signal V outputted from the piezoelectric elements 21 and 23 on the front and back of each other
₁ and V ₃ , the difference V ₁₃ is calculated by the differential amplifier circuit 41,
Signals V _2, V ₄ outputted from the piezoelectric elements 22 and 24 on the front and back relationship to each other, the difference V ₂₄ is computed by the differential amplifier circuit 42.

Further, the sum V _{1234 of} the signals V _{1 to} V ₄ output from the piezoelectric elements 21 to 24 and amplified by the amplification circuits 31 to 34 is calculated by the addition circuit 5, and the sum V ₁₂₃₄ is calculated by the addition circuit 5. Two touch signals are generated. The second touch signal is compared with a reference value to generate a second detection signal including a digital signal. Here, the piezoelectric elements 21 and 23 (22,
The difference V ₁₃ (V ₂₄ ) between the output signals in ₂₄ ) is calculated because the phases of the output signals from the piezoelectric elements 21 and 23 (22, 24) having different mounting angles by 180 degrees around the stylus axis differ by 180 degrees. This is to extract the bending strain component acting on the stylus axis by this calculation.

The sum V of the four piezoelectric elements 21 to 24 is
_The reason why ₁₂₃₄ is calculated is to remove the bending strain component acting on the stylus axis and extract the longitudinal distortion component acting in the stylus axis direction. However, in the present embodiment, the extraction of the longitudinal distortion component is not limited to the method of calculating the sum of the output signals of all four piezoelectric elements 21 to 24,
The sum of the output signals may be calculated from the two piezoelectric elements 21 and 23 or the piezoelectric elements 22 and 24 that are in front and back relationship with each other.

A contact signal detection circuit 6 generates a detection signal from the signals generated by the differential amplifier circuits 41 and 42 and the second contact signal generated by the addition circuit 5. In the contact signal detection circuit 6, the difference between the output signals (V ₁₃ , V ₂₄ ) is calculated by the square circuit 7.
After being squared by 1 and 72, respectively, they are added by an adder circuit 8 to form a first contact signal. The first touch signal is compared with a reference value to generate a first detection signal including a digital signal. Here, the reason why the squares are added is that the maximum value of the output from the piezoelectric elements 21 and 23 (22, 24) having different mounting angles is made constant regardless of the angle θ. That is, the maximum value of the differential output of the piezoelectric elements 21 and 23 is

[0022]

(Equation 1)

The maximum value of the differential output of the piezoelectric elements 22 and 24 is

[0024]

(Equation 2)

## EQU2 ##

[0026]

(Equation 3)

[0027] a since, regardless of the angle .theta.o, the maximum value of the output at time T _o is the (Vmax) ^2. The above description is for the case where the object to be measured contacts the contact portion 1A from the direction in which the stylus 1 is perpendicular to the stylus axis. When the stylus 1 contacts the stylus axis at an angle β (see FIG. 7), the maximum value of the output is ｛. Vmax × COSβ｝ ² . In FIG. 7,
The angle β is defined as the direction orthogonal to the stylus axis and the contact portion 1
This is the angle between the direction in which A hits the object to be measured. Since the first contact signal V ₁₃ (V ₂₄ ) is a differential signal of the piezoelectric elements 21 and 23 (22, 24) affixed to the front and back sides of the stylus axis, Vmax × COSβ is the bending distortion of the detection element support 1C. It can be said that the signal represents the component.

In FIG. 6, the sum signal V ₁₂₃₄ calculated by the adding circuit 5 is obtained by the following equation, where K is an amplification factor.

[0029]

(Equation 4)

V ₁₂₃₄ is a signal representing the longitudinal distortion component excluding the bending distortion component, and β is 90 degrees, that is, the maximum value V when the contact portion 1A comes into contact with the DUT from the direction of the stylus axis.
_M , and the maximum value of the output when contacting the stylus axis at an angle of β is

[0031]

(Equation 5)

## EQU1 ## However, the time when the maximum value of {Vmax × COSβ} ² is formed and the time when V ₁₂₃₄ forms the maximum value are generally different. In other words, the vertical stiffness than the bending stiffness because generally higher, temporally earlier of V _1234. Therefore, after adjusting the gain so that V _M = Vmax, the V ₁₂₃₄ signal is given an appropriate time delay by the delay circuit 9, and then squared by the square circuit 73. (V ₁₂₃₄ ) ² signals squared by the squaring circuit 73 and ΔVmax × CO
When the Sβ｝ ² signal is added by the adder circuit 10,

[0033]

(Equation 6)

Thus, a constant signal is obtained irrespective of the contact angle β. In other words, by delaying the signal corresponding to the longitudinal strain which forms the local maximum value earlier in time by a predetermined time, the local maximum value is formed at the same timing as the signal corresponding to the bending strain so that the position of the measurement sphere 1A is The same output can be generated even when touched. Thereafter, the comparison circuit 11 compares the value with a predetermined reference value, and when the reference value is exceeded, a contact signal is generated. In the present embodiment, the method is not limited to a method in which an appropriate time delay is applied after squaring the (V ₁₂₃₄ ) signal, and may be changed according to the purpose of the present embodiment, such as squaring after delaying. . Further, after applying an appropriate time delay to the (V ₁₂₃₄ ) signal,

[0035]

(Equation 7)

The above operation may be performed. In this case, the same result as described above can be obtained.

Therefore, in the first embodiment, the piezoelectric elements 21 to 24 as deformation detecting elements for detecting that the contact portion 1A has come into contact with the object to be measured are arranged on the substantially columnar stylus 1 having the contact portion 1A at the tip. And the stylus 1 is the piezoelectric element 2
The stylus 1 has a detection element support 1C for supporting and fixing the stylus 1 to 24. The detection element support 1C is a regular polygon whose cross section orthogonal to the axis of the stylus 1 is a regular polygon. The piezoelectric element 21 is provided on at least two of the
To 24, respectively, and these piezoelectric elements 21 to 2
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. A highly accurate measurement can be performed without dependency.

That is, by calculating the sum of the signals output from the piezoelectric elements 21 to 24, the bending distortion component acting on the stylus axis is removed, and the distortion component acting on the stylus axis direction is extracted. By calculating the difference between the signals output from the piezoelectric elements 21 to 24, the bending distortion component acting on the stylus axis is extracted based on the signals having different phases output from the piezoelectric elements 21 to 24. By generating the sum of squares of the signal and the difference signal, the maximum value of the signal output from each of the piezoelectric elements 21 to 24 having a different mounting angle with respect to the stylus axis is determined by the mounting orientation of the deformation detecting element and the DUT. Irrespective of the angle θ formed by the contact azimuth with the object, the measurement accuracy can be improved irrespective of the angle at which the measuring ball 1A contacts the object to be measured. Moreover, since the piezoelectric elements 21 to 24 are attached to the side surfaces of the polygonal body, the structure of the touch signal probe can be simplified.

In the first embodiment, the detection element support 1C has a square cross section, and a total of four piezoelectric elements 21 to 24 are attached to each side surface. 24 of the detection element support portions 1
Two differential signals V ₁₃ and V ₂₄ output from two sets of deformation detecting elements 21 and 23 (22 and 24) located in a front-to-back relationship with each other across C, and four piezoelectric elements 21 and 2
4 and the sum signal output from the two deformation detecting elements located on the front and back sides, the contact detection signal is generated from the sum signal V _{1234 and the} sum signal output from the two deformation detection elements. Since the contact detection signal is generated based on the signals output from the four piezoelectric elements 21 to 24 arranged at an interval, accurate measurement can be performed.

Further, a first contact signal is generated from two differential signals V ₁₃ and V ₂₄ output from the two sets of deformation detecting elements 21 and 23 (22 and 24) located on the front and back, and the first contact signal is generated. The first detection signal is generated by comparing the contact signal with the reference signal, and the sum signal V ₁₂₃₄ output from the four deformation detection elements 21 to 24 or the two signals located on the front and back are output.
A second touch signal is generated from the sum signal output from the deformation detection elements 21 and 23 (22, 24), and a second detection signal is generated by comparing the second touch signal with a reference signal. Then, after delaying the second detection signal by a predetermined time, the contact detection signal is generated by the logical sum of the first detection signal and the first detection signal. In generating the contact detection signal by OR from the second, the second corresponding to the longitudinal distortion that forms the local maximum value earlier in time
By delaying the detection signal by a predetermined time, the same output is generated no matter where the contact portion comes into contact, so that measurement accuracy can be improved from this point as well. Also, the first
In the embodiment, since the piezoelectric elements 21 to 24 are used as the deformation detecting elements, it is possible to reliably detect the impact force when the contact portion 1A of the stylus 1 contacts the object to be measured. Therefore, highly accurate measurement can be performed.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in the configuration of the deformation detecting element, and the other configurations are the same as the first embodiment. Therefore, in the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description is omitted or simplified. FIG. 8A is a perspective view showing a state before a strain gauge as a displacement detecting element is attached, and FIG. 8B is a perspective view showing a state after the strain gauge is attached. In FIGS. 8A and 8B,
The displacement detection element according to the second embodiment includes the detection element support 1
C are the strain gauges 21 to 24 attached to the respective surfaces of the stylus main body 1B and the detection element support 1C when the contact portion 1A of the stylus 1 contacts the object to be measured. This is to detect deformation.

The signals output from the strain gauges 21 to 24 and the bridge circuit (not shown) are supplied to the means shown in FIGS. 5 and 6 in the same manner as the signals output from the piezoelectric elements 21 to 24 of the first embodiment. A touch signal is generated. That is, the signals output from the strain gauges 21 to 24 are
After being amplified is a V ₁ ~V ₄ at 1 to 34, the signal V ₁ output from the strain gauges 21 and 23 at the front and back relationship with each other, V _3, the difference V _{1 3} differential amplifier circuit The signals V ₂ , V ₄ calculated at 41 and output from the strain gauges 22, 24 having a front-to-back relationship with each other are represented by the difference V ₂₄ between the differential amplifier circuit 4
2 is calculated. These differential amplifier circuits 41 and 42 generate a first contact signal. Furthermore, the strain gauges 21 to
The sum V _{1234 of} the signals V _{1 to} V ₄ output from 24 and amplified by the amplification circuits 31 to 34 is calculated by the addition circuit 5, and the addition circuit 5 generates the second contact signal. Thereafter, the signals are processed in the same manner as in the first embodiment to generate a contact signal.

Therefore, according to the second embodiment, the first
Since it has the same configuration as the embodiment, the same operation and effect as the first embodiment can be obtained. Furthermore, in the second embodiment, since the strain gauges 21 to 24 are used as the displacement detection elements, the strain gauges 21 to 24 are provided at relatively low cost, so that the manufacturing cost of the touch signal probe can be reduced. .

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. 9, the signal {Vmax × COSβ} ² output from the addition circuit 8 is compared with a reference value by the comparison circuit 12, and when the reference value is exceeded, the OR circuit 13 is activated. A contact signal is generated via the adder 5. On the other hand, the sum signal _V1234 calculated by the adder circuit 5 is compared with a reference value by a comparator circuit 14. When this signal exceeds the reference value, a delay circuit 15 A configuration in which a contact signal is generated via the OR circuit 13 with a time delay may be employed. Further, in FIGS. 6 and 9, the contact signal generation circuit is configured by an analog circuit, but the contact signal generation circuit may be configured by a digital circuit.

In the present invention, the displacement detecting elements 21 to 2
10 (A) and 10 (B) to increase the output from FIG.
As shown in the figure, the central part of the detection element support part 1C is formed so as to be constricted, and both ends of the displacement detection elements 21 to 24 are supported and fixed to both side parts of the detection element support part 1C. A structure in which a gap is formed between the detecting element supporting portion 1C and the detecting element supporting portion 1C may be employed. At this time, the cross sections of both sides of the detection element supporting portion 1C that support the displacement detection elements 21 to 24 are square. In this structure, the rigidity of the detection element supporting portion 1C is lower than that of FIG.
, The amount of deformation of the displacement detection elements 21 to 24 increases. As a result, the outputs of the displacement detection elements 21 to 24 increase, and the measurement accuracy can be improved.

Further, in the above embodiment, the case where four displacement detecting elements 21 to 24 are installed has been described. However, in the present invention, as shown in FIGS. A structure in which two displacement detection elements 21 and 22 are fixed to two side surfaces adjacent to each other may be used. In this case, in the contact signal generation circuit of FIG.
Although it is not necessary to differentially amplify the signal output from the signal generator 2, the signal component includes not only the bending distortion component of the detection element supporting portion 1C but also a vertical distortion component, and thus can be said to be a simple circuit. Therefore, when the direction orthogonal to the stylus axis is in contact with the measured object, no direction dependency occurs in the direction of θ, but otherwise, the direction dependency remains in the direction of β. However, there is no inconvenience for simple measurement.

Further, in the present invention, as shown in FIG. 12, the cross-section of the detection element support 1C may be an equilateral triangle, and a total of three displacement detection elements 21 to 23 may be attached to each side surface. And the detection element support 1
The cross section of C may be formed into a regular pentagon, regular hexagon, or the like. When the cross section of the detection element support 1C is an equilateral triangle,
If the outputs of the three displacement detecting elements 21 to 23 are squared and added, a constant output that does not depend on the angle θ can be obtained when the object comes into contact with the object from a direction orthogonal to the stylus axis. Otherwise, direction dependency remains in the direction of β. However, there is no inconvenience for simple measurement.

Further, in the above description, the detection element support 1
Although the case where the cross section of the central part shape of C is a regular polygon has been described, in the present invention, as shown in FIG. 13, the central part of the detection element support part 1C may have a circular cross section. That is,
In the present invention, in the detection element support portion 1C, it is sufficient that the portion directly supporting the displacement detection elements 21 to 24 has a regular polygonal cross section, and the shape of a portion that does not contact the displacement detection elements 21 to 24 is not limited. Absent. In each of the above embodiments, the displacement detecting element is the piezoelectric element 21 to 24 or the strain gauge 21 to 24. However, in the present invention, if the displacement detecting element has a structure capable of detecting the displacement of the stylus 1, the displacement detecting element is a piezoelectric element. Structures other than 21 to 24 and strain gauges 21 to 24 may be used. Further, the displacement detecting elements are piezoelectric elements 21 to 2
4 and the strain gauges 21 to 24 may be mixed. Also, if the configuration is such that the arithmetic processing is performed on the signal output from the deformation detecting element and the contact detection signal is generated based on the result of the arithmetic processing, the sum and difference of the signals are not necessarily used as in the above embodiment. It is not limited to what you do.

[0049]

As described above, according to the present invention, the deformation detecting element for detecting that the contact portion has contacted the object to be measured is disposed on the substantially columnar stylus having the contact portion at the tip, and the stylus detects the deformation. It has a detection element support for supporting and fixing the element, the detection element support is a regular polygon whose cross section orthogonal to the axis of the stylus is a regular polygon, and among the side faces of the regular polygon, At least two deformation detection elements are attached to at least two surfaces, arithmetic processing is performed on signals output from these deformation detection elements, and a contact detection signal is generated based on the result of the arithmetic processing. Processing of signals output from the sensor eliminates directional dependence and enables high-precision measurement. In addition, the deformation detection element is attached to the side of the polygon to simplify the structure of the touch signal probe It can be the thing.

[Brief description of the drawings]

FIG. 1 shows a touch signal probe according to a first embodiment of the present invention, in which (A) is a perspective view showing a state before a piezoelectric element as a displacement detecting element is attached,
(B) is a perspective view showing a state after a piezoelectric element is attached.

FIG. 2A is a front view showing a case where a contact portion of a touch signal probe comes into contact with an object to be measured from a direction perpendicular to a stylus axis, and FIG. 6 is a graph showing a temporal change of an output of a piezoelectric element.

FIG. 3 is a perspective view of a touch signal probe for describing an angle θ between a mounting direction of a piezoelectric element and a direction in which a stylus comes into contact with an object to be measured.

FIG. 4 is a graph showing a relationship between an angle θ and a maximum output value Vo of a piezoelectric element.

FIG. 5 is a block diagram illustrating a configuration for generating a contact signal from a signal output from a displacement detection element (piezoelectric element).

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

FIG. 7 is a perspective view of the stylus for explaining an angle β formed between a direction perpendicular to the stylus axis and a direction in which a contact portion contacts an object to be measured.

FIG. 8A is a perspective view showing a touch signal probe according to a second embodiment of the present invention, and FIG. 8A is a perspective view showing a state before a strain gauge as a displacement detection element is attached;
(B) is a perspective view which shows the state after the strain gauge was attached.

FIG. 9 is a circuit diagram showing a modification of the present invention and showing a configuration for generating a contact signal from a signal output from a displacement detection element.

10A and 10B are perspective views showing a whole of a modified example (an example in which the shape of the detection element supporting portion is different) of the present invention, in which FIG. FIG. 5 is a perspective view showing a state after the displacement detecting element is attached.

FIGS. 11A and 11B are perspective views showing a modified example of the present invention (an example in which the number of displacement detection elements is different), wherein FIG. 11A is a perspective view showing a state before the displacement detection elements are attached, and FIG. FIG. 4 is a perspective view showing a state after a displacement detection element is attached.

FIG. 12 is a perspective view showing an entire modified example of the present invention (an example in which the cross-sectional shape of the detection element support is different).

FIG. 13 is an exploded perspective view showing the whole of a modification (an example in which the shape of the central portion of the detection element support is different) of the present invention.

[Explanation of symbols]

1 stylus 1A contact part 1C detecting element support part 21-24 Displacement detecting element (piezoelectric element, strain gauge)

Claims (6)

[Claims] 1. A touch signal probe in which a deformation detecting element for detecting that the contact portion has come into contact with an object to be measured is disposed on a substantially column-shaped stylus having a contact portion at its tip which comes into contact with the object to be measured. Has a detection element support for supporting and fixing the deformation detection element, and the detection element support is a regular polygon whose cross section orthogonal to the axis of the stylus is a regular polygon. At least two of the deformation detecting elements are attached to at least two of the side surfaces of the form, and arithmetic processing is performed on signals output from the deformation detecting elements, and a contact detection signal is generated based on a result of the arithmetic processing. Characteristic touch signal probe. 2. A touch signal probe according to claim 1, wherein a cross section of said detection element support is square, and a total of four said deformation detection elements are attached to each side surface thereof. Two differential signals output from two sets of deformation detection elements located in a front-to-back relationship with each other across the detection element support, and a sum signal output from all four deformation detection elements or A touch signal probe, wherein a touch detection signal is generated from a sum signal output from two deformation detection elements having a relationship positioned on the front and back. 3. The touch signal probe according to claim 2, wherein two differential signals output from the two sets of deformation detecting elements positioned in the front-back relationship are squared and summed to make the first contact. A signal is generated, and the first touch signal is compared with a reference value to generate a first detection signal, and the sum signal output from the four deformation detection elements or is located in a front-back relationship. A second touch signal is generated from the sum signal output from the two deformation detection elements, and the second touch signal is compared with a reference value to generate a second detection signal. A touch signal probe which generates a contact detection signal by ORing with a first detection signal after delaying the touch signal by a predetermined time. 4. The touch signal probe according to claim 2, wherein a magnitude of a sum signal output from each of said deformation detection elements or a sum signal output from two deformation detection elements located in a front-to-back relationship. 1 which was adjusted and delayed for a predetermined time
Generating a contact detection signal using a signal obtained by squaring a total of three signals, that is, two signals and two differential signals output from the deformation detection elements positioned in the front-back relationship, and then summing them. Touch signal probe. 5. The touch signal probe according to claim 1, wherein said deformation detecting element is a piezoelectric element. 6. The touch signal probe according to claim 1, wherein said deformation detecting element is a strain gauge.