JPH06169580A - Alignment method for electrostatic motor - Google Patents

Abstract

PURPOSE:To draw up a thermocouple so as to facilitate alignment work by applying high frequency exciting voltage to the piezoelectric element provided below a needle so as to float the needle, and generating the moment of electrostatic thrust in a mobile electrode. CONSTITUTION:When voltage is applied between electrodes in the condition that a needle 6 is floated by the high frequency excitation of a piezoelectric element 4, the shifting stops in the specified position that specified electrostatic thrust occurs since the shifting of the needle 6 is stopped by a thrust detector 7, and moment occurs by the electrostatic thrust in other position. Next, voltage is applied between the electrodes in the condition that the needle 6 stops the excitation of the piezoelectric element 4 and that it contacts by point with a ball 41, whereupon it generates electrostatic thrust, which is detected with a thrust detector 7. The condition that a stator electrode and a needle electrode are drawn up in parallel can be detected by applying voltage between the electrodes until the electrostatic thrust detected at this time accords with the electrostatic thrust detected at floating and working thrust thereby repeating the minute rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment method for relative positioning of a stator and a mover of an electrostatic motor.

[0002]

2. Description of the Related Art Conventionally, a pair of electrodes provided on the surfaces of a stator and a mover of an electrostatic motor are assembled in parallel with each other. However, in an ultra-small precision electrostatic motor with a gap between electrodes, pitch between electrodes, electrode width, etc. of several micrometers, the dimensions are small and the accuracy is strict, so the pair of electrodes of the stator and the mover are manually assembled in parallel with each other. It's not easy. Therefore, the mover is fixed to an XY table which is rotatable around an axis perpendicular to the electrode surface on which the electrode pair is disposed and which is movable in a direction orthogonal to the electrode surface, and the electrode pair of the mover is fixed. The pair of electrodes of the stator are opposed to each other via the inter-electrode gap. For the stator and mover,
An optical positioning device that irradiates a light beam to the diffraction grating to generate moire fringes is attached to generate moire fringes, and the amount of deviation between the electrode pair of the stator and the electrode pair of the mover is determined by the shape of the moire fringes. The mover is moved and positioned so that the amount of displacement is eliminated by the Y table (for example, Japanese Patent Laid-Open No. 1-107102).

[0003]

However, in the ultra-small precision electrostatic motor, positioning of the electrode pair and the diffraction grating is difficult, and the optical positioning device is complicated. Therefore, it takes a lot of time to align the stator and the mover. There was a drawback that it cost. An object of the present invention is to facilitate alignment work of a stator and a mover of a microminiature precision electrostatic motor.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a stator having a plurality of stator electrodes arranged at a predetermined pitch in the moving direction on the surface and a stator electrode facing each other with a minute gap therebetween. An electrostatic motor alignment method for arranging an electrode pair composed of a stator electrode and a mover electrode of an electrostatic motor comprising a mover having a plurality of mover electrodes arranged on a surface at a predetermined pitch. A plurality of piezoelectric elements are provided on the lower surface of the mover, and an arbitrary high-frequency excitation voltage is applied to the piezoelectric element to push up the mover to levitate, and in this state, a voltage is applied between the electrode pair to move the mover. The mover is rotated by the moment of the electrostatic thrust generated on the moveable electrode inclined with respect to, and the mover electrode is aligned so as to be parallel to the stator electrode.

[0005]

[Function] In the training, the piezoelectric element provided below the mover levitates the mover by applying an excitation voltage, and is fixed by the moment of electrostatic thrust generated on the movable electrode inclined with respect to the moving direction of the mover. The child electrode and the mover electrode are rotated by a slight angle in a direction parallel to each other, and the electrode pairs are aligned. The determination of the aligned state is performed by collating with the thrust characteristic that can be calculated, and the electrodes are moved so that the electrostatic thrust becomes maximum. The electrostatic thrust force at that time is detected by disposing a thrust force measuring device on the side surface in the moving direction of the mover and using the thrust force measuring device.
The above method makes it easy to align the electrode pairs,
It also has the effect of increasing the thrust of the electrostatic motor.

[0006]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side sectional view showing an embodiment of the present invention, in which a stator 2 having a stator electrode 3 on a lower surface thereof is supported on a flat base 1 with legs 21 spaced apart from the surface. is there. Piezoelectric elements 4 on which spheres 41 are mounted are provided at four positions on the upper surface of the base 1 facing the lower surface of the stator 2, and the movable element electrode 5 is provided on the upper surface.
The mover 6 provided with is supported on the ball 41. As shown in FIG. 2, support electrodes 22 and 61 are provided at the four corners of the surfaces of the stator 2 and the mover 6 that face each other.
By applying a voltage to 61, the mover 6 is moved to the stator 2
It is designed to ascend to the surface. When a voltage is applied to the stator electrode 3 and the mover electrode 5, an electrostatic thrust F is generated in the horizontal direction to move the mover 6. A thrust detector 7 for detecting the electrostatic thrust F is used. It is provided on the base 1. Before the mover 6 is brought into a driving state, a high frequency excitation voltage E is applied to the piezoelectric element 4 to push up the mover 6 with a lifting force P, and the floating amount Z is levitated. Pushing force P at that time
Can be obtained by the following equation (1), and the flying height Z can be obtained by the equation (2). P = (W ² / T) · (d / S) · E (1) Z = d · E · T (2) where W: length of one side of the cross section of the supporting electrodes 22 and 61 d : Elastic coefficient of the sphere S: Piezoelectric coefficient of the piezoelectric element T: Thickness of the piezoelectric element E: Applied voltage The applied voltage E changes by changing the frequency of the applied voltage, and the floating period can be arbitrarily determined. FIG. 3 shows a state in which the stator electrode 3 and the mover electrode 5 are exactly parallel to each other. The electrostatic thrust F at this time is obtained as a sine function. Analysis parameters are as follows: drive voltage is 150 V, gap between drive electrodes is 5 μm, and pitch between electrodes is 21 μ.
Numerical analysis under the conditions of m, electrode width 8 μm, electrode length 20 mm, and electrode number 660 is as shown in FIG. Due to the change in the movement amount x, the electrostatic thrust F is point-symmetrical at the midpoint of the pitch between the electrodes. The electrostatic thrusts corresponding to the movement amounts x ₀ , x ₁ , x ₂ in FIG. 4 are F ₀ , F ₁ ,
Given by F ₂ . The alignment method will be described below. In the initial state, as shown in FIG. 5, the mover electrode 5 is tilted with respect to the stator electrode 3 by a tilt angle φ. Arbitrary electrode length y ₀ , y from one end of the mover electrode 5
The electrostatic thrusts at the positions of ₁ and y ₂ correspond to the movement amounts x ₀ , x ₁ and x ₂ shown in FIG. 4, respectively, and the electrostatic thrust F ′ when the mover 6 is tilted is shown in FIG. As indicated by the bold line, x ₀
Becomes the average value of the electrostatic thrust between x ₂ and x ₂ , which is smaller than the electrostatic thrust F ₀ shown in FIG. Therefore, when a voltage is applied between the electrodes in a state where the mover 6 is levitated by exciting the piezoelectric element 4 at a high frequency, the mover 6 is stopped from moving by the thrust detector 7, so that the electrostatic thrust F _{0 is applied.} The movement stops at the position of x ₀ where is generated, and a moment is generated by the electrostatic thrust at other positions. Due to this moment, the stator electrode 3 and the mover electrode 5 are rotated by a small angle in a direction in which they are parallel to each other. Next, the mover 6 stops the excitation of the piezoelectric element 4,
When a voltage is applied between the electrodes in a state of being in point contact with the ball 41, an electrostatic thrust is generated, and the thrust at that time is detected by the thrust detector 7. The electrostatic thrust F ′ detected by the thrust detector 7 is
The stator electrode 3 and the mover electrode 5 are exactly parallel, and x
_The voltage is applied between the electrodes until the electrostatic force F ₀ that can be detected at the position of ₀ coincides with the force, and the thrust is applied. It is possible to detect a state in which the stator electrode and the mover electrode are aligned in parallel by making a minute rotation by the moment of the electrostatic thrust and repeating the detection of the electrostatic thrust.

[0007]

As described above, according to the present invention, by maximizing the electrostatic thrust between the mover electrode and the stator electrode, the electrode pair of the mover electrode and the stator electrode is formed. Since they can be aligned, the alignment work of the stator and the mover of the microminiature precision electrostatic motor can be facilitated, and the thrust of the electrostatic motor can be increased.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing the surfaces of a stator and a mover.

FIG. 3 is an explanatory diagram showing positions of a stator and a mover.

FIG. 4 is an explanatory diagram showing a relationship between positions of a stator and a mover and electrostatic thrust.

FIG. 5 is an explanatory diagram showing a positional relationship between a stator and a mover when the mover is tilted.

FIG. 2 is an explanatory diagram showing the relationship between the positions of the stator and the mover and the electrostatic thrust when the mover is tilted.

[Explanation of symbols]

 1 Base 2 Stator 3 Stator Electrode 4 Piezoelectric Element 5 Mover Electrode 6 Mover 7 Thrust Detector

[Procedure amendment]

[Submission date] November 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing the surfaces of a stator and a mover.

FIG. 3 is an explanatory diagram showing positions of a stator and a mover.

FIG. 4 is an explanatory diagram showing a relationship between positions of a stator and a mover and electrostatic thrust.

FIG. 5 is an explanatory diagram showing a positional relationship between a stator and a mover when the mover is tilted.

FIG. 6 is an explanatory diagram showing the relationship between the positions of the stator and the mover and the electrostatic thrust when the mover is tilted.

[Explanation of reference numerals] 1 base 2 stator 3 stator electrode 4 piezoelectric element 5 mover electrode 6 mover 7 thrust detector

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Miwa Miwa 5-9-10 Tokodai, Tsukuba, Ibaraki Prefecture Yasukawa Electric Tsukuba Research Institute

Claims (1)

[Claims] 1. A stator having a plurality of stator electrodes arranged at a predetermined pitch in the moving direction on the surface, and a plurality of mover electrodes on the surface so as to face the stator electrodes with a minute gap therebetween. An electrostatic motor alignment method for aligning an electrode pair composed of a stator electrode and a mover electrode of an electrostatic motor having a mover arranged at a predetermined pitch thereon, wherein a plurality of piezoelectric elements are provided on a lower surface of the mover. Provided individually, by applying an arbitrary high-frequency excitation voltage to the piezoelectric element to push up and float the mover, in this state a voltage is applied between the electrode pair,
The movable element is rotated by the moment of the electrostatic thrust generated in the movable electrode inclined with respect to the moving direction of the movable element to align the movable element electrode so as to be parallel to the stator electrode. And electrostatic motor alignment method.