JPS63316674A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To transmit oscillation efficiently to a moving unit, by combining circular and linear reciprocating oscillations with each other, and by composing the oscillations so that the kinematic locus of a curve closed-circuit which is electrically variable in the shape and in the rotational direction may be generated at the tip of an oscillator. CONSTITUTION:On an oscillation unit 4 oscillated and driven by a piezoelectric unit 6, an oscillator tip section 5 is formed, and the piezoelectric unit 6 consists of a first piezoelectric element 6a generating the reciprocating oscillation of a circular locus on the unit 6 and a second piezoelectric element 6b generating the reciprocating oscillation, and the unit 6 is provided with an electrode 7 and a lead wire 8. Then, at the bottom section of the oscillation unit 4, said piezoelectric unit 6 as the laminated unit of the first and second piezoelectric elements 6a, 6b is bonded. As a result, with periodic voltage applied to the piezoelectric elements 6a, 6b, on the oscillator tip 5, a curve closed-circuit locus in an arbitrary shape can be generated in the arbitrary moving direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric vibrator, and in particular to a piezoelectric vibrator used in a piezoelectric motor that frictionally drives a moving body at its tip.

[Conventional technology]

FIG. 8 shows a piezoelectric motor that frictionally drives a moving body at the tip of a conventional piezoelectric vibrator disclosed in, for example, Japanese Unexamined Patent Publication No. 58-93478. The vibrating piece (2) vibrates on one side of the moving body (3) (3a)
It comes into contact with and separates from the

Next, the operation will be explained using FIGS. 8 and 9.

The central axis X of the vibrator (1) is aligned with one surface (3
It is tilted by an angle θ with respect to the normal n of a). When the vibrator (1) is excited in this state, the tip of the vibrating piece (2) causes a vibrational displacement in the X-axis direction, but when the tip of the vibrating piece (2) comes into contact with the surface (3a) of the moving body (3), , vibrating piece (2)
generates a bending vibration displacement in the y-axis direction. As a result, as shown in Fig. 9, the tip of the vibrating element (2) moves along the surface (3a) while it is in contact with the surface (3a), that is, while moving toward A-+B in the same figure. move in a straight line, surface (3a)
When moving away from , that is, from B to A in the figure, it moves in an elliptical shape. In this way, the moving body (3) is transformed into a vibrating piece (
2) is frictionally driven while in contact with the surface (3a) and is moved in the direction of arrow P shown in FIG.

[Problem that the invention seeks to solve]

As described above, conventional piezoelectric vibrators generate vibration changes only in the direction of the center axis of the vibrator, so it is necessary to place the vibrator at an angle with respect to the moving object. There are problems such as the vibration is limited to one direction, and the vibrating piece at the tip of the vibrator requires a certain length to bend and vibrate, making it difficult to realize a thin piezoelectric motor. there were.

This invention was made to solve the above-mentioned problems, and it is possible to draw a curved circuit locus in any direction using an electric signal at the tip of the vibrator, and also to draw a curved loop in the direction of the central axis of the vibrator. The purpose is to obtain a piezoelectric vibrator that can be made thinner.

[Means for solving problems]

A piezoelectric vibrator according to the present invention includes a first piezoelectric element that generates reciprocating vibration with an arcuate trajectory at the tip of the vibrating body, and a second piezoelectric element that generates reciprocating vibration with a linear trajectory. is connected to the vibrating body, and by applying an appropriate periodic voltage to each piezoelectric element, a curved closed motion locus suitable for driving the piezoelectric motor is generated at the tip of the vibrating body. It is something.

[Effect]

In this invention, by applying a periodic voltage to the piezoelectric element, it is possible to generate a curved closed path locus of any shape at the tip of the vibrator in any moving direction, and the piezoelectric actuator driven by the piezoelectric vibrator The moving direction of the moving body of the motor can be easily switched electrically.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and in the figure, a vibrator tip (5) is formed on a vibrator (4) which is vibrated and driven by a piezoelectric body. A piezoelectric body (6) that drives the vibrating body (4) includes a first piezoelectric element (6a) that generates reciprocating vibration with an arcuate trajectory at the vibrator tip (5), and a straight line between the vibrator tip (5) A second piezoelectric element (6b) that generates reciprocating vibration of a shaped locus, and electrodes (7a) to (7d),
It is equipped with lead wires (8a) to (8C). AC source(
9a) vibrates the first piezoelectric element (6a), and the AC power source (9b) vibrates the second piezoelectric element (6b).

In addition, in FIG. 1, the arrow shown on the piezoelectric body (6) is
It shows the polarization direction of the piezoelectric material.

Next, the operation will be explained. In the embodiment shown in FIG. 1, a first piezoelectric element (6a) that generates circular arc-shaped reciprocating vibration at the tip of the vibrator (5) is provided at the bottom of the vibrating body (4), and a first piezoelectric element (6a) that generates circular reciprocating vibration at the tip of the vibrator (5) ) to generate linear reciprocating vibration.
A piezoelectric body (6) in which piezoelectric elements (6b) are laminated and integrated is bonded.

The first piezoelectric element (6a) has a grounded reference electrode (7
C) and the piezoelectric element (6C) while facing this electrode (7C).
Electrodes (7a) to divide a) into two regions.

(7b) is provided. The piezoelectric element (6a) has a region formed by electrodes (7a) and (7c), and a region formed by electrodes (7a) and (7c).
The polarization directions of the regions formed in b) and (7c) are opposite to each other. Therefore, the electrode (7a), (
7b) with the lead wire (8a), and
When a periodic voltage such as a sine wave is applied from the AC power source (9a) through the lead wire (8b), the two regions of the piezoelectric element (6a) vibrate while being displaced in opposite directions. As a result, the tip (5) of the vibrating body (4) to which the piezoelectric element (6a) is bonded to the bottom performs an arcuate reciprocating vibration.

The mechanism for generating the above-mentioned circular arc-shaped reciprocating vibration of the vibrator tip (5) will be explained in further detail using the model diagram shown in FIG.

In FIG. 2, line segment n corresponds to the bottom of the vibrator (4) in FIG. 1, and point P corresponds to the vibrator tip (5). FIG. 2(a) shows a model of a state in which no strain displacement occurs in the two regions of the piezoelectric element (6a) described above. Next, a voltage is applied to the piezoelectric element (6a) to generate a contraction strain due to the longitudinal effect in one region and an elongation strain due to the longitudinal effect in the other region, which is modeled as shown in Figure 2 (
b) In FIG. 2(b), the A end side is the contraction strained portion, and the B end side is the expansion strained portion. Further, FIG. 2C shows a model in which the directions of strain displacement in the two regions of the piezoelectric element (6a) are reversed. As can be seen from FIGS. 2(a) to (C), the piezoelectric element (
6a) by applying a periodic voltage to both ends A of the bottom of the vibrating body (4).
, B, the tip P of the vibrating body performs an arcuate reciprocating vibration with the axis of rotation near the center of the bottom AB.

Next, as shown in FIG. 1, the second piezoelectric element (6b) has a reference electrode (7C) and an electrode (7d) opposite to this electrode (7C). The polarization in 6b) is uniformly applied in the direction in which the electrodes (7C) and (7d) face each other as shown by the arrows. For this reason, the lead wire (
When a periodic voltage such as a sine wave is applied from the AC power supply (9b) through the piezoelectric element (6b) and (8c), the piezoelectric element (6b)
produces a vibrational displacement of expansion and contraction due to the longitudinal effect in the direction of polarization.

As a result, the tip (
5) performs linear reciprocating vibration by the vibration of the piezoelectric element (6b). FIG. 3 is a model of a mechanism that generates linear reciprocating vibration of the vibrator tip (5). Figure 3(a) shows a model of the piezoelectric element (6b) with no distortion, and Figure 3(b) shows the piezoelectric element (6b)
) with elongation distortion due to longitudinal effect, same figure (C)
1 and 2 respectively show a state in which reduction strain occurs in the piezoelectric element (6b) due to the longitudinal effect. As can be easily seen in Figures 3(a) to (C), the tip P of the vibrating body (4) is located at the bottom AB.
Similarly, reciprocating vibration is performed linearly in the direction of the central axis of the vibrating body (4).

In the above, the vibration of the vibrator tip (5) caused by the piezoelectric elements (6a) and (6b) was considered individually.
) is a composite vibration of the above-mentioned circular arc-shaped reciprocating vibration and linear reciprocating vibration.

Next, consider the motion locus of the vibrator tip (5) when a reference periodic voltage is applied to the piezoelectric element (6b) and a periodic voltage synchronized with this reference periodic voltage is applied to the piezoelectric element (6a).

Figure 4 shows the first
In the model diagram of the piezoelectric vibrator shown in the figure, the origin of the coordinate axes is set at the tip P of the vibrator in a state where no distortion occurs in the vibrating body (4). Point Q Vibrator (4) Bottom A
B midpoint, AQ=BQ (=A'Q=B'Q) =
D, and the height of the piezoelectric vibrator is PQ(-P'Q)=H.

First, in FIG. 4(a), the first piezoelectric element (6a)
Consider the displacement of the tip P of the vibrator in the X-axis and y-axis directions.

Displacement ha ( due to longitudinal effect strain of the first piezoelectric element (6a)
Since t) is considered to be proportional to the output voltage Ea(t) of the AC power supply (9a), it can be written as ha(t) = Ka-Ea(t) as a proportionality coefficient Ka. Since the displacement ha(t) is minute, θ is also minute, so it is approximated. Therefore, the displacements xa(t), ya(t) of the tip P of the vibrator in the x and y axis directions due to the vibration of the piezoelectric element (6a)
Hato becomes.

Next, in FIG. 4(b), the second piezoelectric element (6b)
Consider the displacement of the tip P of the vibrator in the X-axis and y-axis directions.

Displacement hb ( due to longitudinal effect strain of the second piezoelectric element (6b)
Since t) is considered to be proportional to the output voltage Eb(t) of the AC power supply (9b), it can be written as hb(t)=Kb-Eb(t), setting the proportionality coefficient to 9. Therefore, the displacement xb(t) of the tip P of the vibrator in the x and y axis directions due to the vibration of the second piezoelectric element (6b).

yb(t) becomes, and due to the combined vibration of the piezoelectric elements (6a) and (6b), the displacement of the tip P of the vibrating body in the X-axis and y-axis directions is expressed by the formula % Formula % Now, the output of the piezoelectric element (6b) Eb(t)-BocO5(ωo1) is applied to the voltage Ebat) as a reference periodic voltage. At this time, when a periodic voltage Ea(t) = Aosin(ω.t), which is phase-shifted by −2 with respect to this reference periodic voltage gb(t), is applied to the first piezoelectric element (6a), Equation (3) is obtained. The locus of the vibrator tip P expressed by is an elliptical locus as shown in FIG. 5(a). Furthermore, when a periodic voltage Ea(t) = -A6sin (ω, 1), which is shifted by two phases from the reference periodic voltage Eb(t), is applied to the first piezoelectric element (6a), the tip of the vibrator P moves in the opposite direction along the trajectory shown in FIG. 5(a).

Also, reference voltage 1)4. (t) -B. cos(ω.t
) with respect to 乎π/2+θ. Periodic electric current Ea(t)−±AOsin (ωot+
θ. )7 When the voltage is applied to the first piezoelectric element (6a), the vibrator tip P becomes an elliptical locus with the axis tilted toward the rotation direction of the vibrator tip P, as shown in FIG. 5 fb).

Furthermore, the reference voltage Eb(t)=Bocos, (ωat)
ga(t)=±AOsin (ωo1)±
When C(Isln(2ω.1) (decoding in the same order) is applied to the piezoelectric element (6a), the vibrator tip P becomes as shown in FIG. 5(C).
As shown in , a trajectory with a large bulge is drawn near the apex of the trajectory.

Furthermore, a phase difference component θ is added to the applied voltage. (0〈θ0
The periodic voltage ga(t)−±Aosin(ωo1+θ0)±C(,5
When in(2ωo1+θ0) (same order of decoding) is applied to the first piezoelectric element (6a), the tip of the vibrator P
As shown in FIG. 5(d), the trajectory has a large bulge near the apex and is distorted in the direction of rotation of the tip of the vibrator.

FIG. 6 shows another embodiment, in which a piezoelectric element (6
Reference voltage (7C1) is applied to a) and (6b), respectively.
(7C2) is provided, (8bl), (8
b2) are lead wires connected to the respective reference voltages (7C1) and (7C2). Piezoelectric elements (6a) and (6b
) are electrically insulated by an insulating layer (10).

The operation of the piezoelectric vibrator having the above structure is similar to that of the embodiment shown in FIG. 1, except that both surfaces of the piezoelectric body (6) serve as reference electrodes and are grounded.

FIG. 7 shows yet another embodiment, in which a piezoelectric element (6a) that generates an arcuate trajectory at the tip of the piezoelectric vibrator and a piezoelectric element (6b) that generates a linear trajectory are laminated. .

With this configuration, the vibration displacement is increased by laminating the piezoelectric bodies, but the operation of the piezoelectric vibrator is similar to that of the embodiment shown in FIG.

〔Effect of the invention〕

As described above, according to the present invention, the circular arc-shaped reciprocating vibration and the linear reciprocating vibration are combined to form a curved closed path at the tip of the vibrator.
In addition, we have made it possible to generate arbitrary motion trajectories whose shape and direction of rotation are electrically variable, so if this is used in a piezoelectric motor, the direction of rotation or movement can be easily switched electrically, and the vibration It has the effect of efficiently transmitting the vibration to a moving object.O Also, unlike conventional piezoelectric vibrators, bending vibration of the vibrating element is not used, so the height of the piezoelectric vibrator can be lowered, making it possible to realize a thin piezoelectric motor. There is also.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of one embodiment of the present invention, FIGS. 2 to 5 are model diagrams for explaining the operation of the device shown in FIG. 1, and FIGS. 6 and 7 are views of other embodiments. FIG. 8 is an exploded perspective view of an example, FIG. 8 is a perspective view of essential parts of a piezoelectric motor using a conventional piezoelectric vibrator, and FIG. 9 is a diagram for explaining the operation of the one shown in FIG. (4)... Vibrator, (5)... Vibrator tip, (6)...
・Piezoelectric body, (6a), (6b)... 1st. Second piezoelectric element, (9a), (9b)...AC power supply. In each figure, the same reference numerals indicate the same or corresponding parts. Figures (a) (b) Figure 5 (C) (d) Figure 7 R Figure 8 Procedural Amendments dated January 2, 1986

Claims (7)

[Claims] (1) A first piezoelectric element that generates reciprocating vibration with an arcuate trajectory at the tip of the vibrating body and a second piezoelectric element that generates reciprocating vibration with a linear trajectory in the direction of the central axis of the vibrating body are integrated. A piezoelectric vibrator, comprising: a piezoelectric body having a shape of 100 mm, which synthesizes vibrations generated by the first and second piezoelectric elements to generate vibrations forming a curved closed path locus at the tip of the vibrating body. (2) at least one first piezoelectric element that generates reciprocating vibration in an arcuate trajectory at the tip of the vibrating body; and at least one piezoelectric element that generates linear reciprocating vibration in the direction of the central axis in the vibrating body;
2. The piezoelectric vibrator according to claim 1, wherein a piezoelectric body formed by laminating and integrating two second piezoelectric elements is coupled to the bottom surface of the vibrating body. (3) The longitudinal effect strain of the second piezoelectric element, which is made of at least one piezoelectric single plate polarized in either the positive direction or the negative direction of the central axis of the vibrating body, causes the vibrating body to have a linear shape in the central axis direction. A piezoelectric vibrator according to claim 1, which generates reciprocating vibrations. (4) A piezoelectric vibrator according to claim 1, comprising a first piezoelectric element in which an electrode on one side is divided into two to form two regions in which polarization directions are either the same or opposite to each other. (5) The piezoelectric vibrator according to claim 1, wherein a reference periodic voltage is applied to the second piezoelectric element, and another periodic voltage synchronized with the reference periodic voltage is applied to the first piezoelectric element. (6) A sine wave voltage is applied to the second piezoelectric element, and a sine wave voltage having the same period as the sine wave voltage and an arbitrary phase difference is applied to the first piezoelectric element. The piezoelectric vibrator according to item 5. (7) Apply a sine wave voltage to the second piezoelectric element, and generate a composite voltage of a sine wave voltage having the same period as the sine wave voltage and an arbitrary phase difference, and a harmonic voltage of this sine wave voltage. The piezoelectric vibrator according to claim 5, wherein a voltage is applied to the piezoelectric element.