JP3140476U - Excitation contact detection sensor - Google Patents

Abstract

The present invention provides an excitation type contact detection sensor that can maintain vibration characteristics and can reduce the influence of a difference in rigidity caused by the direction of receiving a load upon contact on measurement accuracy.
A stylus having a substantially shaft-like stylus body and a contact portion, a vibrating means, a detecting means, and a stylus holder that supports the stylus are provided. The stylus holder 1 has a fixed portion 11 and three arm portions 12 provided on the outer periphery of the virtual cylinder S centering on the axis of the stylus main body 21. The stylus 2 is disposed in the inner space of the virtual cylinder S and is supported by the arm portion 12 via the six elastic pieces 4. Three or more elastic pieces 4 are provided radially between the stylus body 21 and the arm portion 12 from the two axial positions of the stylus body 21 around the axis at equal intervals, and along the axial direction. It is provided in an elastically deformable state.
[Selection] Figure 2

Description

  The present invention relates to an excitation-type contact detection sensor, and is used, for example, when measuring the shape of an object to be measured with a three-dimensional measuring machine or the like.

  Conventionally, height gauges (one-dimensional measuring machines), three-dimensional measuring machines, surface texture measuring machines, small hole measuring machines, and the like are known as measuring machines for measuring the shape and dimensions of an object to be measured. In these measuring instruments, various probes are used to detect the positional relationship between the measuring instrument main body and the object to be measured. These probes are classified into non-contact probes and contact probes, or continuous measurement probes and touch trigger probes.

  As a contact-type touch trigger probe of a measuring machine as described above, an excitation type contact detection sensor 100 as shown in FIG. 6 is known (see Patent Document 1). The vibration-type contact detection sensor 100 includes a stylus holder 101, a stylus 102, and two piezoelectric elements 103. The stylus holder 101 includes a fixed portion 111 for attaching to a moving shaft of a measuring machine (not shown) and a pair of arm portions 112. The stylus 102 is supported by an elastic piece 104 disposed between the arm portion 112 and the stylus 102. Further, a contact portion 121 that comes into contact with the object to be measured is provided at the tip of the stylus 102.

The pair of arms 112, the elastic piece 104, and the stylus 102 have the same thickness dimension (dimension indicated by T1 in the drawing). The thickness dimension T1 is smaller than the thickness dimension T2 of the fixed portion 111.
The piezoelectric element 103 is mounted so as to straddle the stylus 102, vibrates the stylus 102 in the resonance state in the axial direction, and detects a change in the resonance state of the stylus 102 that occurs when the contact portion 121 contacts the object to be measured. Is to do.

  In such a configuration, when the stylus 102 is vibrated by the piezoelectric element 103, the stylus 102 vibrates in a resonance state along the axial direction. In this state, when the contact part 121 comes into contact with the object to be measured, a change occurs in the resonance state of the stylus 102. By detecting this change with the piezoelectric element 103, the contact between the contact part 121 and the object to be measured is detected. become able to.

JP 2005-345483 A

In the vibration-type contact detection sensor 100 described in Patent Document 1, the arm portion 112 and the stylus 102 are formed with the same thickness dimension T1, as shown in FIG. 6B, and the thickness dimension T1 is The thickness dimension T2 of the fixed portion 111 is smaller. That is, since the stylus holder 101 has a shape in which the arm portion 112 is thinned with respect to the fixed portion 111, the longitudinal direction (X direction) of the elastic piece 104 when an external load acts on the contact portion 121, and the arm A difference in rigidity of the entire sensor occurs in the thickness direction (Y direction) of the portion 112.
For example, when measuring a measurement object with a sensor attached to a three-dimensional shape measuring machine, touch measurement (intermittent measurement) or measurement of a steeply inclined surface is performed using the sensor in order to approach the measurement object from various directions. If it is performed, a measurement result having a different shape may be obtained in spite of measuring a symmetrical shape in the X direction and the Y direction.

Due to the difference in rigidity depending on the shape of the support portion of the stylus 102, the deflection amount in the X direction and the deflection amount in the Y direction of the entire sensor when the contact portion 121 contacts the object to be measured are different. There is a problem that the measurement accuracy is affected by the difference (direction dependency).
In particular, when measurement accuracy on the nanometer order is required, the influence on the measurement accuracy due to the difference in the amount of deflection in each direction is large.
On the other hand, it is conceivable to increase the thickness dimension in the Y direction of the entire sensor to ensure the rigidity in the Y direction. However, regarding the portions of the stylus 102 and the elastic piece 104 that are vibrated by the piezoelectric element 103, If the thickness is changed, the detection sensitivity of the measuring force, the vibration frequency, and the Q value (an index indicating the sharpness of the resonance state) may change greatly, and the sensor function may not be performed. For this reason, there has been a great demand for securing rigidity without changing the basic structure of the sensor.

  An object of the present invention is to provide an excitation-type contact detection sensor that can maintain vibration characteristics and can reduce the influence of the difference in rigidity caused by the direction of receiving a load upon contact on measurement accuracy.

  An excitation-type contact detection sensor of the present invention includes a stylus body formed in a substantially shaft shape, a stylus having a contact portion provided at a distal end portion of the stylus body and in contact with an object to be measured, and the stylus in a resonance state. A vibrating means comprising: a vibrating means for vibrating at a position; a detecting means for detecting the contact from a change in a resonance state of the stylus that occurs when the contact portion and the object to be measured are brought into contact; and a holder that supports the stylus. In the mold contact detection sensor, the holder extends along the axis on a fixed portion provided coaxially with the shaft of the stylus body, and on an outer periphery of a virtual cylinder centering on the shaft from the fixed portion. The stylus is disposed in a space formed inside the virtual cylinder, and is supported by the support through a plurality of elastic pieces. Between the stylus body and the support portion, three or more radial portions are provided at equal intervals around the axis from two positions in the axial direction of the stylus body, and elastically deformable along the axial direction. It is provided in a state.

Here, the axial direction of the stylus body is defined as a Z direction, and two directions orthogonal to the Z direction and perpendicular to each other are defined as X and Y directions.
For example, as the support portion extending along the axis (Z direction) on the outer periphery of the virtual cylinder, a cylindrical support portion centering on the axis of the stylus body can be employed. Or the support part in which the several arm part extended along an axis | shaft from a fixing | fixed part was provided on the outer periphery of the virtual cylinder may be sufficient.

According to this configuration, since the stylus body is supported by the support portion via the plurality of elastic pieces that are elastically deformed in the axial direction of the stylus body, when the vibration unit vibrates the stylus, the stylus is moved in the axial direction. Vibrates in a resonant state along When the contact portion comes into contact with the object to be measured in this state, the detecting means detects a change in the resonance state, and the positional relationship between the object to be measured and the vibration-type contact detection sensor is measured.
In such an excitation-type contact detection sensor, elastic pieces supporting the stylus are provided radially at equal intervals around the stylus axis, and elastic pieces are provided radially at two locations in the axial direction of the stylus body. Therefore, the difference in rigidity in the X and Y directions orthogonal to the stylus axis (Z direction) can be suppressed. Therefore, it is possible to reduce the direction dependency of the rigidity that the rigidity in the Y direction is smaller than the rigidity in the X direction as in the conventional sensor, and the influence of the difference in rigidity caused by the direction of receiving the load at the time of contact on the measurement accuracy. Can be reduced.

Further, regarding the stylus, although the arrangement of the elastic pieces that support the stylus body is different from that of the conventional sensor, the stylus itself can adopt a substantially similar structure. Therefore, the vibration characteristics of the conventional sensor can be easily maintained without greatly changing the detection sensitivity, vibration frequency, and Q value of the measuring force.
In addition, since the support part is provided on the outer periphery of the virtual cylinder around the axis of the stylus along the axis, and the stylus is arranged in the inner space of the virtual cylinder, a plurality of elastic pieces are arranged radially. can do. Therefore, the stylus is securely held, the stylus support structure is stabilized, and high measurement accuracy can be obtained.
The rigidity in each direction was calculated by the finite element method using the shape of the vibration contact detection sensor of the present invention. As shown in FIG. 5, in the conventional sensor, the rigidity in the Y direction is changed to the rigidity in the X direction. On the other hand, only 30% was obtained, but according to the sensor of the present invention, the rigidity in the Y direction can be made the same as the rigidity in the X direction.

In the vibration-type contact detection sensor of the present invention, the support portion is constituted by three or more arm portions that extend in parallel with each other and are arranged at equal intervals in the outer circumferential direction of the virtual cylinder, and The pieces are preferably arranged between the arm portions and the stylus body.
Here, since three or more arms are arranged at equal intervals in the outer circumferential direction of the virtual cylinder, a structure for supporting the stylus is formed by arranging each arm at a position corresponding to the radial elastic piece. Is done.

  According to this configuration, the support portion is configured by three members (arm portions) extending in parallel with each other, and the respective support portions (arm portions) are arranged at equal intervals in the outer circumferential direction of the virtual cylinder. A predetermined gap can be secured between the arms. Therefore, when the support structure of the stylus including the stylus and the elastic piece is formed inside the arm portion, the forming operation can be performed from the gap between the arm portions. For example, the support portion is formed in a cylindrical shape. Compared with the case where it is, the support structure of a stylus can be formed easily.

In the vibration-type contact detection sensor of the present invention, the holder is preferably formed of a low thermal expansion material.
According to this configuration, since the holder is made of a low thermal expansion material, the holder hardly undergoes thermal expansion, and the influence on measurement accuracy due to temperature change can be reduced.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of the vibration-type contact detection sensor 10 of the present embodiment. 2 to 4 are a perspective view, a front view, and a bottom view of the vibration-type contact detection sensor 10 in a state before the piezoelectric element 3 is mounted.
As shown in FIG. 1, the vibration-type contact detection sensor 10 includes a stylus holder (holder) 1, a stylus 2, and six piezoelectric elements 3.

  The stylus holder 1 includes a fixing portion 11 for attaching to a moving shaft of a measuring machine (not shown) and a support portion 13 including three arm portions 12 extending in parallel from the fixing portion 11. Here, the fixing portion 11 is provided coaxially with the stylus 2. Further, as shown in FIG. 2, the three arm portions 12 constituting the support portion 13 are arranged on the outer periphery of the virtual cylinder S around the axis of the stylus 2 at equal intervals in the outer peripheral direction. 2 along the axis.

The stylus 2 includes a stylus main body 21 formed in a substantially shaft shape, and a contact portion 22 provided at the tip of the stylus main body 21 and in contact with an object to be measured.
The stylus body 21 is disposed between the three arms 12 of the stylus holder 1. That is, the stylus body 21 is arranged in a space formed inside the virtual cylinder S and is supported by the arm portion 12 via the six elastic pieces 4.

As shown in FIGS. 2 to 4, the elastic piece 4 is arranged such that its longitudinal direction is substantially perpendicular to the axial direction of the stylus 2, one end is connected to the inner peripheral surface of the arm portion 12, and the other end is the stylus body. It is connected to the outer peripheral surface of 21.
Further, three elastic pieces 4 are arranged at regular intervals along the axial direction from a substantially central position of the stylus main body 21, and each of the three elastic pieces 4 is arranged around the axis. Are provided radially at intervals of 120 degrees. With such a configuration, each elastic piece 4 can be elastically deformed in the axial direction of the stylus 2.
In the present embodiment, a description is given of a configuration in which three elastic pieces 4 are connected around the axis of the stylus main body 21 at intervals of 120 degrees, but the elastic pieces 4 connected around the axis of the stylus main body 21 are described. The number is not necessarily limited to three. That is, as long as the number of the elastic pieces 4 is three or more as long as it is connected at equal intervals around the axis of the stylus main body 21, any number may be used. For example, four elastic pieces 4 may be connected around the axis of the stylus body 21 at intervals of 90 degrees, or may be connected at intervals of 60 degrees.

  The stylus holder 1, the stylus 2, and the elastic piece 4 are all formed from a low thermal expansion material. Of these, the stylus 2 and the six elastic pieces 4 have the same thickness dimension (dimension indicated by T1 in FIG. 4). On the other hand, the fixed portion 11 and the three arm portions 12 constituting the stylus holder 1 have a thickness dimension T2 larger than the thickness dimension T1. Here, the thickness dimensions T1 and T2 are dimensions along an orthogonal direction of a plane formed by the axial direction of the stylus 2 and the longitudinal direction of each elastic piece 4, that is, directions in which the elastic pieces 4 can be elastically deformed. , And a dimension along a direction perpendicular to the longitudinal direction of each elastic piece 4.

  As shown in FIG. 1, the piezoelectric element 3 is mounted in a state of being spanned between a pair of parallel elastic pieces 4. The piezoelectric elements 3 are arranged such that the two piezoelectric elements 3 sandwich the pair of elastic pieces 4. The piezoelectric element 3 as the vibration means 31 is bonded to one side of the pair of elastic pieces 4, and the piezoelectric element 3 as the detection means 32 is bonded to the other side. Here, the vibration means 31 is for vibrating the stylus 2 in the axial direction in a resonance state, and the detection means 32 is a resonance state of the stylus 2 that is generated when the contact portion 22 contacts the object to be measured. It is for detecting a change.

  In such a configuration, when the stylus 2 is vibrated by the vibration means 31, the stylus 2 vibrates in a resonance state along the axial direction. In this state, when the contact portion 22 comes into contact with the object to be measured, a change occurs in the resonance state of the stylus 2, and the detection means 32 detects this change, thereby detecting the contact between the contact portion 22 and the object to be measured. be able to. In this way, the positional relationship between the object to be measured and the vibration-type contact detection sensor 10 is measured.

[Effects of this embodiment]
According to this embodiment, the following effects can be achieved.
(1) The elastic pieces 4 that support the stylus 2 are provided radially at equal intervals around the axis of the stylus 2, and the elastic pieces 4 are provided radially at two locations in the axial direction of the stylus body 21. Therefore, as shown in FIGS. 3 and 4, the difference in rigidity in the X and Y directions orthogonal to the axis (Z direction) of the stylus 2 can be suppressed. Therefore, it is possible to reduce the direction dependency of the rigidity that the rigidity in the Y direction is smaller than the rigidity in the X direction as in the conventional sensor, and the influence of the difference in rigidity caused by the direction of receiving the load at the time of contact on the measurement accuracy. Can be reduced.

(2) Regarding the stylus 2, the arrangement of the elastic pieces 4 that support the stylus body 21 is different from that of the conventional sensor, but the stylus 2 itself can adopt a substantially similar structure. Therefore, the vibration characteristics of the conventional sensor can be easily maintained without greatly changing the detection sensitivity, vibration frequency, and Q value of the measuring force.

(3) Since the arm portion 12 is constituted by three members extending in parallel with each other and the respective arm portions 12 are arranged at equal intervals in the outer circumferential direction of the virtual cylinder S, the stylus 2 It arrange | positions in the inner space of the arm part 12, is supported radially by the elastic piece 4, and is hold | maintained reliably by this. Therefore, the support structure of the stylus 2 is stabilized and high measurement accuracy can be obtained.

(4) Since the arms 12 are constituted by three members extending in parallel with each other and the arms 12 are arranged at equal intervals in the outer circumferential direction of the virtual cylinder S, Can secure a predetermined gap. Therefore, when forming the support structure of the stylus 2 including the elastic piece 4 on the inner side of the arm portion 12, the forming operation can be performed from the gap between the arm portions 12, so that, for example, the arm portion 12 is cylindrical. Compared to the case where the stylus 2 is formed, the support structure of the stylus 2 can be easily formed.

(5) Since the material of the stylus holder 1 is a low thermal expansion material, the thermal expansion of the arm portion 12 hardly occurs, so that the influence on the measurement accuracy due to the temperature change can be reduced.

[Variations of the present invention]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the case where the stylus holder 1 has the support portion 13 including the three arm portions 12 has been described. However, as the support portion of the present invention, a cylindrical shape formed on the outer periphery of the virtual cylinder S is used. It may be.
Further, the vibration means 31 and the detection means 32 are not limited to the piezoelectric element 3 of the above-described embodiment. For example, a piezoelectric element formed on the surface of each elastic piece 4 using MEMS (Micro Electro Mechanical System). You may comprise with a film | membrane.
In the above-described embodiment, the fixed portion 11 and the three arm portions 12 constituting the stylus holder 1 have been described as having the thickness dimension T2 larger than the thickness dimension T1 of the elastic piece 4. However, the present invention is not limited to this. The thickness of the fixed portion 11 of the stylus holder 1 may be the dimension T2, and the thickness of the arm portion 12 may be the same as the thickness T1 of the elastic piece 4.

  Hereinafter, embodiments of the present invention will be described. In this example, the following evaluation is performed using a vibration-type contact detection sensor having a configuration substantially similar to the configuration described in the above embodiment.

[1. Evaluation item〕
Rigid FEM analysis using the design model was performed. Here, a load is applied to the contact portion of the stylus tip along each direction so as to be in substantially the same state as actual measurement conditions, and the rigidity in each direction is calculated.
[2. Measurement condition〕
A force of 10 μN is applied to the contact portion of the stylus in each direction (X and Y directions shown in FIGS. 3 and 4), the amount of deflection is analyzed, and the rigidity in each direction is calculated.

[3. Results and discussion)
In FIG. 5, the result of the rigidity FEM analysis of an excitation type | mold contact detection sensor is shown. Using the results of the conventional sensor design model, the stiffness in the X and Y directions of the conventional and the present invention is shown with the stiffness in the X direction as 100.
According to this stiffness FEM analysis, the stiffness in the X direction of the vibration-type contact detection sensor of the present invention is the same as the stiffness in the X direction of the conventional sensor.
In the conventional sensor, the rigidity in the Y direction is about 30% of the rigidity in the X direction. On the other hand, in the vibration-type contact detection sensor of the present invention, the rigidity in the Y direction is about 100% of the rigidity in the X direction. Thus, in the sensor of the present invention, it has been found that the respective stiffnesses in the X direction and the Y direction match.

  The present invention can be used as a stylus of a scanning microscope such as an atomic force microscope as well as an excitation type contact sensor of a surface texture measuring device.

The perspective view which shows the vibration type contact detection sensor which concerns on one Embodiment of this invention. The figure which shows the state before mounting | wearing the said vibration type contact detection sensor with a piezoelectric element. The front view which shows the said excitation type | mold contact detection sensor. The bottom view which shows the said vibration type contact detection sensor. The figure which shows the analysis result which concerns on the Example of this invention. (A), (B) is the front view and side view which show the conventional sensor.

Explanation of symbols

1 ... Stylus holder (holder)
DESCRIPTION OF SYMBOLS 2 ... Stylus 3 ... Piezoelectric element 4 ... Elastic piece 10 ... Excitation type contact detection sensor 11 ... Fixed part 12 ... Arm part 13 ... Supporting part 21 ... Stylus main body 22 ... Contact part 31 ... Excitation means 32 ... Detection means S ... Virtual cylinder.

Claims (3)

A stylus having a stylus body formed in a substantially shaft shape, and a contact portion provided at a tip portion of the stylus body and in contact with an object to be measured;
Vibration means for vibrating the stylus in a resonance state;
Detection means for detecting the contact from a change in the resonance state of the stylus that occurs upon contact between the contact portion and the object to be measured;
An excitation-type contact detection sensor comprising a holder for supporting the stylus,
The holder includes a fixed portion provided coaxially with the shaft of the stylus main body, and a support portion extended from the fixed portion on an outer periphery of a virtual cylinder centering on the shaft along the shaft. ,
The stylus is disposed in a space formed inside the virtual cylinder, and supported by the support portion via a plurality of elastic pieces,
The elastic piece is provided between the stylus main body and the support portion at three or more radial positions at equal intervals around the axis from two axial positions of the stylus main body, and in the axial direction. An excitation-type contact detection sensor provided in a state in which it can be elastically deformed along. The vibration-type contact detection sensor according to claim 1,
The support portion is constituted by three or more arm portions that extend in parallel to each other and are arranged at equal intervals in the outer circumferential direction of the virtual cylinder,
The vibration-type contact detection sensor, wherein the elastic piece is disposed between each arm and the stylus body. The vibration-type contact detection sensor according to claim 2,
The vibration contact detection sensor according to claim 1, wherein the holder is made of a low thermal expansion material.

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