JP2001004311A - Positioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow positioning with a simple and small structure at high resolution and precision by measuring the drive distance of a linear actuator using a capacitance meter, and setting the capacitance value as a reference with a sensing point of a tuning-fork contact sensor. SOLUTION: A piezoelectric actuator 1 is applied with a voltage so that a contact piece 2 of a tuning-fork contact sensor A contacts a contact sensing mirror surface 3, and the position at that time, or a start point, is allowed to correspond to the capacitance between electrodes 4 and 4' of a capacitance meter B. With the relationship between electrode gap and capacitance acquired as a measurement curve in advance, if the capacitance measured value between electrodes at the start point is different from the value at the start point of the measurement curve, that amount is corrected for reference setting. A probe 5 is positioned by controlling the application voltage of the piezoelectric actuator 1 and the output of the capacitance meter B. This method is effective even to linear actuators such as a voice coil motor and linear motor. Further, a 3-way combination of them may provide a 3-dimension alignment device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device, wherein a capacitance meter for measuring a position is set as a reference at a sensing point of a tuning fork type contact sensor.

[0002]

2. Description of the Related Art There are many positioning devices using a reference setting using an optical microswitch or a touch probe, and a positioning device using a linear scale or a laser measuring device, and there are problems such as dimensions, resolution and accuracy.

[0003]

SUMMARY OF THE INVENTION Improvement of resolution and accuracy in reference setting and positioning.

[0004] High speed and stable positioning.

The present invention has a simple structure, small size, high resolution,
A main object is to provide a high-precision positioning device.

[0006]

According to the first aspect of the present invention,
The distance moved by the linear actuator is measured by a capacitance meter, and the value of the capacitance is set as a reference at the sensing point of the tuning fork type contact sensor.

According to the present invention, a position serving as a reference for positioning is sensed with high speed and high accuracy using a tuning fork type contact sensor, and furthermore, a measurement value of the capacitance meter at this position, that is, a starting point is set as a reference. Therefore, the position is accurately measured by the capacitance meter, and a compact, high-resolution, high-precision positioning device is provided.

[0008] The invention according to claim 2 is characterized in that the position is controlled so as to fall within a predetermined range around the set value.

According to the present invention, the position is not controlled so as to become the set value of the positioning, but is controlled so as to vibrate within a predetermined range around the set value. Thus, a positioning device that is resistant to noise characteristics such as vibration is provided.

According to a third aspect of the present invention, starting from the sensing point of the first aspect, the positioning is performed at a sensing point of a separately provided tuning fork type contact sensor.

In the present invention, the position is determined by the sensing point of the separately provided tuning fork-type contact sensor. However, the position and size of the contact can be selected in accordance with the shape and size of the object to be measured, so that high resolution is achieved.・ High-precision dimensional measurement becomes possible.

A fourth aspect of the present invention is the invention according to the third aspect, wherein a portion other than a node of another contact is arranged near the node of the vibrating contact.

According to the present invention, for example, when the size of the contact of the tuning fork type contact sensor is increased, a portion of the vibration node where the sensitivity of the contact sensing is reduced appears on the contact. Since the contact is supplemented, a positioning device capable of sensing contact over a wide range is provided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a part of a schematic diagram 1 showing an embodiment of a positioning apparatus according to the present invention, in which a change in form and a change in electrical characteristics are observed while applying pressure to a sample under an electron microscope. is there. By applying a voltage to the piezoelectric actuator 1,
The contact 2 of the tuning fork type contact sensor A is brought into contact with the contact sensing mirror surface 3, and the instantaneous position, that is, the starting point is made to correspond to the capacitance between the electrodes 4, 4 'of the capacitance meter B.

Here, the contact 2 is made of the inventor's prior application "Japanese Patent Application No. 8-217307".

Since a true spherical steel ball is fixed at the position P1 described in (1), the accuracy of contact sensing, that is, the positioning accuracy of the starting point is high.

Since the relationship between the electrode spacing and the capacitance is previously obtained as a calibration curve, when the measured value of the capacitance between the electrodes at the starting point is different from the value at the starting point of the calibration curve, , That is, the correction, that is, the reference setting. The positioning of the probe 5 is performed by controlling the relationship between the voltage applied to the piezoelectric actuator 1 and the output of the capacitance meter, that is, the distance between the electrodes 4 and 4 '. In this embodiment, the positioning of the starting point is performed. Is a standard deviation of 5 nm and 1 from the starting point.
Positioning at a position moved by 0 μm had a standard deviation of 10 nm. Here, the sample 6, the sample stage 7, the fixed stage 8, and the electric measuring device E are shown.

FIG. 2 shows an embodiment of a conventional positioning device.
Although the optical microswitch 9 is used for starting point detection, the standard deviation usually exceeds 3 μ due to the influence of temperature drift and the like. In addition, the starting point and the distance moved by the piezoelectric actuator 1 are measured by a linear scale C or a displacement meter using a laser length measuring device D to perform positioning. In general, it is difficult to set the standard deviation to 50 nm. . In the case of a laser length measuring device, the measuring system becomes large and is easily affected by external vibration.

FIG. 3 shows an embodiment of the positioning device according to the present invention, in which a contact 2A of a tuning fork type contact sensor is provided separately from the contact 2 of the tuning fork type contact sensor for detecting the starting point. The tip 2a of the contact has a true spherical shape, and the hollow cylinder 10 illuminated on the object to be measured is moved in the diametric direction so that the diameter of the hollow cylinder can be accurately determined from the two positioning points where contact is sensed on the inner wall. Is to be measured. In this way, by providing a contact sensor in addition to the contact sensor for positioning the starting point, the point to be positioned is clearly set, and high-resolution and high-precision dimension measurement can be performed. Since the dimension measurement here does not simply determine the point at which the touch is detected, it determines the position of the touch sensing point from the positioning control of the touch sensing point, that is, the statistical processing of a plurality of data. it can.

FIG. 4 shows an embodiment of the positioning device according to the present invention, and illustrates a contact portion of a tuning fork type contact sensor applied to a wide range of dimension inspection. When the contact 11 descends in the direction of the arrow 12 and comes into contact with the place 13 where the size of the object to be measured is higher than the standard, the tuning fork type contact sensor detects this, and the height dimension is determined from the distance between the contact point and the starting point. Measure 14. When the node 15 of the vibration of the contact 11 comes in contact with the place 16 higher than the reference, the contact cannot be sensed. To compensate for this insensitive portion, another contact 17 having no node in this portion is arranged side by side with the contact 11. Is installed to measure the size by positioning control.

[0020]

As described above, according to the present invention, the distance moved by the linear actuator is measured by the capacitance meter, and the value of the capacitance is used as a reference point at the sensing point of the tuning fork type contact sensor. Since they are set, a small, high-resolution, high-precision positioning device is provided. In the description of the present invention, the example of the piezoelectric actuator has been described. However, the effect can be improved when a linear actuator such as a voice coil motor or a linear motor is used. It is also possible to provide a three-dimensional positioning device by combining the devices in three directions. Furthermore, in place of the tuning fork type contact sensor, a contact sensor using a change in piezo resistance, a change in the vibration frequency and phase of the crystal oscillator, a change in the mechanical filter characteristics of the sound resonator, and the like are used. High-speed, high-sensitivity, high-precision positioning device.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a positioning device according to the present invention.

FIG. 2 is an explanatory view showing one embodiment of a conventional positioning device.

FIG. 3 is an explanatory view showing one embodiment in which a tuning fork type contact sensor is provided at two places in the embodiment of the present invention.

FIG. 4 is an explanatory view showing one embodiment applied to a wide range of dimension inspection in the embodiment of the present invention.

[Explanation of symbols]

1 Piezoelectric actuator A
Tuning fork type contact sensor B Capacitance meter 2,2A
Contact 3 Contact sensing mirror surface 4, 4 '
Electrode 5 Probe E
Electrical measuring device 6 Sample 7
Sample table 8 Fixed table 9
Optical micro switch C Linear scale D
Laser measuring device 10 Hollow cylinder 12
Arrows 11, 17 Contacts 13, 16
Higher than standard 14 Height 15
Node of vibration

Claims (4)

[Claims] 1. A positioning device, wherein a distance moved by a linear actuator is measured by a capacitance meter, and a value of the capacitance is set as a reference at a sensing point of a tuning fork type contact sensor. 2. The positioning device according to claim 1, wherein the position is controlled so as to fall within a predetermined range around a set value of the positioning. 3. The positioning device according to claim 1, wherein the positioning is performed at a sensing point of a separately provided tuning fork type contact sensor starting from the sensing point. 4. The positioning device according to claim 3, wherein a portion that is not a node of another contact is arranged near the node of the vibrating contact.