JPS61247283A - Electret motor - Google Patents

Abstract

PURPOSE:To linearly move movable elements with a simple construction by opposing electret plates formed in strip shape through the prescribed gap into movable elements, and displacing the end displacing ranges of two bimorphs to dispose in the gap. CONSTITUTION:A movable element 1 is composed of two electret plates 2, 3 and a coupling piece 4, and the plates 2 are alternately polarized longitudinally in the strip shape. The plates 2, 3 are opposed to each other in the same polarity through the prescribed gap G1, and mounted on a guide rail linearly movably in the longitudinal direction. The movement continuing first and second bimorphs 5, 6 are integrated by superposing two piezoelectric elements 7, 8, the ends are disposed in the gap G1, and the other ends are secured to a base 11. Thus, the prescribed voltage is applied from a drive circuit 12 to the second bimorph 6 to displace it upward to move the element 1 in the prescribed direction at 90 deg. of an electric angle. Further, it is further moved similarly by the first bimorph 5 at 90 deg. of the electric angle. This is repeated to move the element 1 to the desired ground point.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electret motor, which is particularly suitable for driving light loads, and has a moving element that moves linearly made of an electret, and generates torque by electrostatic force.

[Background Art] Electret motors in which the rotor is made of electret are disclosed in Japanese Patent Application Laid-Open No. 54-61604 and Japanese Patent Application Laid-open No. 56-53.
586 is known. This device consists of a rotor in which electrets having positive and negative charges are arranged alternately in the circumferential direction, and electrets arranged around the outer periphery of the rotor to apply an electrostatic force to the rotor.
Consists of twice as many electrodes. In this case, in order to reduce the step angle and make the rotor rotate smoothly, it is necessary to increase the number of electric lefts and electrodes.Therefore, in order to achieve smooth rotation, the number of electrodes that can be arranged is limited. In addition, as the number of electrodes increases, the number of parts and electrode connection lines also increase, resulting in the problem that the electrode drive circuit becomes complicated.

In addition, it is possible to change such a rotor to a linearly moving mover using the same principle, but in that case, a significantly larger number of electrodes would be required, which would ultimately reduce the feasibility. become scarce.

[Object of the Invention] The present invention has been made in view of the above-mentioned reasons, and its object is to provide an electret motor that has a simple structure and can linearly move a slider.

[Disclosure of the Invention] The electret motor according to the present invention has electret plates formed in a band shape and polarized with different polarities alternately in the longitudinal direction thereof, and facing each other with a predetermined gap so that each type of plate corresponds to the other. It consists of an integrated mover and two bimorphs whose electrode tips are displaced in a range slightly smaller than the predetermined gap by applying a predetermined voltage, and the bimorphs are moved by the electric current.

The displacement range of the tip of the rod is located within the predetermined gap, and the distance between the first bimorph and the second bimorph is 180 in electrical angle.
The object of the present invention is thereby achieved.

(Example) An example of the present invention will be described below based on FIGS. 1 to 6.

Reference numeral 1 denotes a mover, which is composed of two electret plates 2.3 and a connecting piece 4. Each electret plate 2.3 is P
Made of VDF (polyvinylidene fluoride), etc.
It is formed into a band shape, and its different polarities are alternately polarized in the longitudinal direction.

Each of the electric left plates 2.3 has a predetermined gap G1 and is integrated with an insulating coupling piece 4 so as to face each other so that the same polarities correspond to each other. The mover 1 is mounted on a guide rail (not shown) so as to be linearly movable in its longitudinal direction.

5.6 is a first bimorph for continuous movement, and a second bimorph for determining movement direction, which are made by stacking two piezoelectric elements 7°8 whose widths are equal to or smaller than the various widths of the moving element 1. It is formed into a long plate shape. Electrodes 7a, 8a are provided on both sides of each piezoelectric element 7.8, and the facing electrodes of these serve as a common electrode 9.10. and,
One end of the common electrode 9.10 is sufficiently protruded from the end surface of the piezoelectric element 7.8, and the other end of the bimorph 5.6 is
It is fixed to the base 11. In this case, both bimorphs 5.
6 is an electrical angle from 180° to 360° with respect to the pole of mover 1.
In the embodiment, the bimorphs 5 and 6 are arranged so as to be shifted by 270°. When a predetermined voltage is applied to each electrode from
0, more specifically, the protrusions from the end faces of the piezoelectric elements 7 and 8 are disposed such that a displacement range G2 is located within a predetermined gap Gl between both electric left plates 2.3. In this case, it is desirable that the electret plate 2.3 and the bimorph 5.6 are parallel to each other and the common electrode 9.10 is located at the center of the predetermined gap G1, with the bimorph 5.6 not being displaced.

The drive circuit 12 is connected in parallel and supplies a commercial frequency voltage as shown in FIG. 3(a) or a positive/negative pulse voltage as shown in FIG. 3(b) to each electrode according to a control signal. .10 are alternating offspring.

-A pole appears and undergoes a curved displacement.

An example of the signal supplied to the drive circuit 12 is as shown in FIG. 4, and for the first bimorph 5, it always starts with a non-polar half cycle as shown in (a), and thereafter, it changes + and - every half cycle. The polarity changes and ends with + and -, and continues to supply -. on the other hand,
Only one pulse, either + or -, is supplied to the second bimorph 6 slightly before the first rising edge of the first bimorph 5, and in the figure, for rightward movement, +(b) , -(c) is supplied for leftward movement.

(Operation) FIG. 1, that is, FIG. 5(a) shows the bimorph 5.6 in a state where no predetermined voltage is applied to the bimorph 5.6.
is not displaced, and the mover 1 is also stationary.

In this state, when a rightward movement control signal is input, the drive circuit 12 first supplies a predetermined voltage of 10 to the second bimorph 6, and the second bimorph 6 is displaced upward as shown in (b). However, attraction and repulsion are performed between the common electrode 10 and each of the electret plates 2, and the mover 1 moves by 90 electrical degrees in the direction of the arrow W1.

Next, ten predetermined voltages are supplied to the first bimorph 5, and the first bimorph 5 is displaced upward as shown in (C).
Attraction and repulsion are performed between the common electrode 9 and each of the electret plates 2, and the mover 1 further moves by 90 electrical degrees in the direction of the arrow W1.

Next, after passing through the state of (d), a predetermined voltage of - is supplied to the first bimorph 5, and as shown in (e), the first bimorph 5
is displaced downward, and attraction and repulsion occur between one pole of the common electrode 9 and various parts of the electret plate 3, and in the end, the mover 1 has moved 360 degrees in electrical angle from the state of (a). Become. Thereafter, this operation is repeated until the desired movement completion point is in the state (e).

Note that when moving from (c) to (d), the inertial force is acting on the mover 1, so the mover 1 goes a little too far, and this ensures reliable continuation of movement. Furthermore, by continuing to supply the first bimorph 5 with a predetermined negative voltage after the supply signal, the mover 1 is stopped quickly and the mover 1 is prevented from moving due to external force after stopping. do. That is, the electret motor does not have a reluctance torque that forcibly stops the rotor when the application of a predetermined voltage is stopped, unlike a permanent magnet motor, and therefore no braking force is applied to the electret motor.

6(a) to 6(e) show the case where a control signal for leftward movement is input, and the moving child operates in the same manner as in FIG. 5 and moves in the direction of arrow W2.

FIG. 7 shows another embodiment of the bimorph, in which the same parts as in the previous embodiment are given the same reference numerals.

This bimorph 15.16 has electrodes 7a, 8a provided only on the non-facing sides of two stacked piezoelectric elements 7.8, and does not have a common electrode as in the previous embodiment. Therefore, it is connected in series to the drive circuit 12, and as shown in FIG. 3(a),
A voltage as shown in (b) is supplied. As a result, progeny and -poles appear alternately on electrodes 7a and 8a, and bimorph 1
5.16 is entirely curved in its thickness direction. In this case, the displacement range G2 of the tips of the electrodes 7a and 8a also has a predetermined gap G1.
It shall be slightly smaller than

Also, the electrode 7 when approaching each electric left plate 2.3
Since offspring seeds (which may be negative polarities) always appear in a and 8a, the electret plates 2 and 3 are arranged so that different polarities correspond to each other as shown in FIG.

Figures 9(a) to (e) are explanatory diagrams of the operation of this device.
This embodiment is the same as the previous embodiment except that the polarity of each electret plate 2.3 and electrodes 7a+8a is different.

[Effects of the Invention] Since the electret motor of the present invention is constructed as described above, the electrodes that apply electrostatic force to the mover can perform the function with two bimorphs, and the structure is simple. , the mover can be moved linearly.

[Brief explanation of the drawing]

1 to 6 show one embodiment of the present invention, in which FIG. 1(a) is a side view, FIG. 2(b) is a plan view, and FIG. A perspective view of the second bimorph, FIG. 3 is a waveform diagram of a predetermined voltage from the drive circuit, (a) is a commercial frequency voltage, (b) is a pulse voltage, and FIG. 4 is a supply signal of the drive circuit, (a) is the first bimorph signal; (b) is the second bimorph signal when moving to the right; (C) is the second bimorph signal when moving to the left; 6(a) to 6(e) are explanatory diagrams of the operation when moving in the left direction. FIG. 7 is a perspective view of the bimorph of another embodiment, and FIG. 8 (
a) is its side view, (b) is its plan view, Fig. 9(a)
thru|or (e) are explanatory drawings at the time of rightward movement. 1-Mover, 2.3-Electroleft plate, 4-Joining piece, 5.15-First bimorph, 6.16-Second bimorph, 7.8-Piezoelectric element, 9.10-Common electrode, 1
1-- Base, 12-- Drive circuit. Patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshimaru Takemitsu (and 2 others) Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Goko = 1 King = = (a) Nyo ε = Koni 1 = Engineering E W 2222 King == Yo5 2== -W" =:= YoE =Work= W === ==Yo E 22211 Yogo] "'Yo mouth: Yoro: 0 mouth Yo: ! Eyoro= := Yo= “[

Claims (1)

[Claims] (1) A mover in which electret plates formed in a band shape and alternately polarized with different polarities in the longitudinal direction are integrated by facing each other with a predetermined gap so that each pole corresponds to the other;
It consists of two bimorphs whose electrode tips are displaced in a range slightly smaller than the predetermined gap by applying a predetermined voltage, and the bimorph is separated from the first bimorph so that the displacement range of the electrode tip is located within the predetermined gap. The second bimorph is an electret motor that is arranged so as to be shifted from 180° to 360° in electrical angle.