JPS63136979A - Electrostatic actuator - Google Patents

Abstract

PURPOSE:To reduce an applied voltage by forming the electrodes of a substrate and the like through patterning and by using a dielectric material as a rotor. CONSTITUTION:An electrostatic actuator is composed of a rotor 1 made of a dielectric material, and upper and lower plates 5, 6 of a stator. Conductive layers 1a are disposed radially at a predetermined interval from the axis of a rotational shaft 2 on the surface of the rotor 1 at the side of the plate 6, and the layers 1a are composed by forming the layer as a thin film on the surface at the side of the stator, and then shaping it by a photolithographic technique in a predetermined pattern. A substrate 4 is laminated on the opposed surfaces of the rotor 1 of the upper surface of the plate 6, and an electrode pattern 3 is further disposed. The electrode is formed by radially depositing it with respect to the axis of the shaft 2 of the rotor 1. Thus, voltages are sequentially applied to the electrodes, an electric field generated by the electrodes is moved to rotate the moving element by the electrostatic action with the element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic actuator that moves a mover using electrostatic force.

[Prior Art] Conventional actuators mainly utilize electromagnetic force, and due to their characteristics, they must be equipped with electromagnetic coils, permanent magnets, etc., resulting in complex structures and extremely large power consumption. Ta. Therefore, the amount of heat generated by the actuator was also large.

Therefore, in order to solve these problems, a synchronous motor using an electret (for example, Utility Model Application No. 57-98191, etc.) has been proposed as a motor that uses electrostatic force instead of electromagnetic force. It is known that the driving force of an actuator using such electrostatic force is proportional to the square of the applied voltage (V) and inversely proportional to the pressure 11i(d) between the stator and the movable element.

[Problems to be solved by the invention]However, electret type actuators require the use of special electrets, making it difficult to miniaturize the armature, and sufficient consideration must be given to the size and distance of the electrodes. It could not be said that the

Furthermore, production of electrets requires a special process, which inevitably increases costs.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and in order to provide an inexpensive actuator that is small in size and has a simple configuration, an embodiment of the present invention is as follows. It has the following configuration.

That is, it is composed of a stator in which a plurality of electrodes are arranged at predetermined intervals, and a movable element made of a dielectric material that is movable relative to the electrode arrangement surface of the stator at a fixed interval. The conductivity of at least the electrode-facing surface of the movable element is configured to change at predetermined intervals.

[Operation] In the above configuration, by sequentially applying voltage to the electrodes and moving the electric field generated by the electrodes, the movable element is rotated by electrostatic action with the charges accumulated in the movable element by the electrodes.

[Example] Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 is an exploded perspective view of an embodiment according to the present invention, and FIG. 2 is a sectional view thereof.

In the figure, 1 is a rotor made of a dielectric material, and 5 and 6 are upper and lower plates, which are stators. On the surface of the lower plate 6 of the rotor 1, a conductive layer 1a is provided at predetermined intervals radially from the axis of the rotating shaft 2.
is installed.

A front view of the rotor 1 provided with this conductive layer 1a is shown in FIG.
), and its cross-sectional view is shown in FIG. 3(B).

In this embodiment, the rotor 1 is made of glass, and the stator-side surface thereof is coated with Ti (0,3 μm) / Cr (0,0
It is constructed by forming a thin conductive layer (1 μm) and then shaping it into a predetermined pattern using photolithography technology. The rotor 1 is not limited to glass, and may be any dielectric material having a weak conductivity with a surface resistivity of about 1011 to 10'3 ohms, such as phenol resin.

In addition to Ti, the material of the conductive layer is Au and Ag.

It may also be a conductive material such as Cu, Al-A, Cr, Ta, or a laminate thereof.

Reference numeral 2 denotes a rotating shaft to which the rotor 1 is attached, and is rotatably supported by a bearing 7 provided on the upper plate 5 and a bearing 8 provided on the lower plate 6.

Note that the rotor 1 has a thickness of 0.4 mm and a diameter of 66 mm, and the rotating shaft 2 has a diameter of 1.5 mm.

A substrate 4 is laminated on the upper surface of the lower plate 6 facing the rotor 1, and an electrode pattern 3 is provided on the surface of the substrate 4 facing the rotor 1. The electrodes are formed by vapor deposition at predetermined intervals radially with respect to the axis of the rotating shaft 2 of the rotor 1.

Various methods such as etching can be used for patterning the electrode. Note that although Cr is used for the electrode 3, Ag, Au, A9. Buttering may be performed using various conductive metals such as , Cu, etc., and high melting point metals such as Ti and Ta (tantalum) may be used to prevent melting of the electrode due to discharge.

In this embodiment, the upper plate 5, lower plate 6, and substrate 4 are made of glass. However, these materials are not limited to glass, and may be made of plastics, ceramics, or the like as long as they have insulation properties.

The rotor 1, the substrate 4, and the upper plate 5 are held at a predetermined gap by spacers, screws 9a, 9b, 9c, and 9d, and a bearing 7.8, and are configured to be rotatable in the direction of arrow A or arrow B in the figure. ing.

In this embodiment, the electrodes 3 are formed to have an average pattern width [■ and a pattern pitch of 2 mm, and the distances between the electrodes 3 and the rotor 1, and between the rotor 1 and the upper plate 5 are both 0.25 mm.

Then, each electrode is supplied with φAl 1.0 from the drive circuit 10. φ
B12. A three-phase voltage of φC13 is applied to generate a rotating electric field on the substrate 4 to rotate the rotor 1.

By making the electrode pattern pitch and gap smaller, the torque generated on the rotor 1 becomes larger.

The timing of voltage application to the electrode 3 by this drive circuit 10 is shown in FIGS. 4(a) and 4(b). Here, Fig. 4(a) shows the case where a pulse voltage of (0/+V)V is applied to each phase (each electrode), and Fig. 4(b) shows the case where an AC voltage of (+V/-V)V is applied. This shows the case where φA11. φB12. φ
When a pulsed voltage as shown in FIG. 4(a) (the horizontal axis represents time t) is applied to each phase of C13, a moving electric field is generated in the direction of arrow A in FIG. Then, charges are generated in the rotor 1 by this moving electric field, and a driving force is exerted to follow the moving electric field in the same direction of arrow A with a certain slip. This state is shown in FIGS. 5(a) and 5(b).

Here, when a "-" potential is applied to the electrode 3a, for example,
On the surface of the rotor 1 facing the electrode 3a, a charge 21 (in this case, a "+" charge) having a polarity opposite to the voltage applied to the electrode 3a is locally charged due to the weak conductivity on the rotor 1. be done. In this state, the electric potential applied to the electrode 3a changes and the phase switches), and when electric lines of force like the arrow 22 in FIG. 5(b) are generated, the force F=qE (q; the surface charge of the rotor, E: strength of electric field in the direction of rotation of electric lines of force)
acts, and rotational force is generated.

This is the same even if the AC voltage shown in FIG. 4(b) is applied.

However, it is preferable that the phase order is A, B, B, λ, C9, A... (-0 means a phase shift of 180°).

To move the rotor 1 in the opposite direction (arrow B direction), the phase order of the applied voltages may be reversed, and in the case of the embodiment, two of the three phases may be replaced. Further, the number of phases may be any number as long as it can generate an 8-dynamic electric field.

At this time, the rotor 1 is provided with a conductive layer 1a,
As a result, the effective resistivity per unit area becomes lower than when the rotor 1 does not have the conductive layer 1a.

As a result, this embodiment has the advantage that the characteristics of the sliding speed and torque of the rotor 1 relative to the rotating electric field change, making starting easier, and increasing the ability to follow changes in the frequency of the rotating electric field and changes in load.

Further, among the charges induced on the surface of the rotor 1, those located on the pattern of the conductive layer can easily move within the range of the pattern, so the accumulation pattern of the charges induced on the rotor surface is The pattern of the side electrodes 3 is not limited, and can be slightly expanded. As a result, rotational stability against changing conditions increases. For example, in terms of stability against changes in humidity, it has been confirmed that the product according to this example is superior to the product according to the conventional example.

Note that the effects of this embodiment shown above can be controlled by the pattern shape of the conductive layer 1a provided on the rotor 1.

Therefore, the shape of the conductive layer 1a of the rotor 1 is as shown in FIG.
The shape is not limited to the shape shown in , and various patterns can be used.

Examples of other patterns of the conductive layer 1a of this rotor 1 are shown in FIGS. 6(A) to 6(C). In addition, Fig. 6 (B) is shown in Fig. 6 (
This is a version of A) with a finer pattern pitch. As shown in FIG. 6, the pattern of the electrodes 3 and the conductive layer 1 of the rotor 1
Since the pattern a is non-parallel, there is a constant conductive layer on the surface facing the electrodes 3, and extremely smooth rotation can be obtained regardless of the positional relationship between the electrodes 3 and the rotor 1.

[Second Embodiment] Furthermore, an example of a conductive layer pattern of another embodiment according to the present invention is shown in FIG.

Also in FIG. 7, a conductive material is formed in the form of a thin film on the surface of the rotor 1 made of glass, and then a conductive layer 1b is provided by shaping using the photolithography technique. This structure is the same as the first embodiment described above, but this embodiment is characterized in that the conductive layer 1b is formed into substantially the same shape as the electrode 3 of the substrate 4, and is connected to each other.

By using the rotor 1 having the pattern of this embodiment in the configuration shown in FIG. 1, the rotor 1 can be rotated by the mutual attractive force caused by the electrostatic force acting between the electrodes 3 of the substrate 4 and the conductive layer lb of the rotor 1. Sufficient rotational force can be obtained.

However, in order to rotate the rotor 1 continuously, it is necessary to set the pattern pitch of the conductive layer 1b of the rotor 1 to a value different from the pattern pitch of the electrodes 3 of the substrate 4. In this embodiment, the pattern width of the electrode 3 on the substrate 4 is 2.5 degrees.
The pattern pitch was an angular width of 6 degrees, and the angular width of the conductive layer 1b of the rotor 1 was 2.5 degrees and 5 degrees, respectively. Note that the voltage value and drive timing applied to the electrode 3 of the substrate 4 may be the same as in FIG. 4.

In this embodiment, the rotation of the rotor 1 can be synchronized with the drive timing of the applied voltage, and the rotation of the rotor 1 can be easily controlled. It also has the feature that the rotor 1 can be moved in steps by applying a pulsed voltage as shown in FIG. 4(a).

Further, the conductive layer of the rotor 1 may be in an electrically free state,
There is no need to apply a specific voltage from an external circuit or to ground, and the configuration can be simple.

Note that all of the above explanations have been made using a rotor that has electrode patterns only on one facing surface, but it is also possible to have electrode patterns on both sides and position and arrange the electrode patterns on the opposing board surface in exactly the same way as on the other board surface. Of course, it is also possible to have a configuration including the following. By providing electrode patterns on both sides, the driving force of the rotor can be doubled.

[Third Embodiment] Although the above description has been made regarding an electrostatic actuator having a motor structure that performs circular motion around the drive shaft 2, the present invention is not limited to this. It can also be used for a type of electrostatic actuator that moves. FIG. 8 shows an electrostatic actuator in which the movable element moves eight times in parallel.

In the figure, 51 is a stator, and electrodes 52 are formed on its surface. In this embodiment, the stator 51 is made of glass, and an electrode pattern is formed on its surface by vapor deposition. Various methods such as etching can be used for patterning this electrode. Further, the stator 51 and the electrodes 52 may be made of the same material as the substrate 4 and the electrodes 3 in FIG.

Further, 53 is a movable element made of a current-visiting body, and in this embodiment, glass is used as the movable element 53. This mover 5
The material 3 may have a low dielectric constant (e.g., desirably e=1 to 10) and a high resistance value, and may be formed of phenol resin or the like. A conductive layer 54 is provided on the surface of the movable element 53 facing the stator 51. A plan view of the mover 53 provided with the conductive layer 54 is shown in FIG. The pattern of the conductive layer 54 may be parallel to the electrode 52, or may be formed into various patterns such as the pattern shown in FIG. 6(C). If this pattern is made non-parallel to the pattern of the electrode 53 as shown in FIG. Movement becomes possible.

In this embodiment, the pattern width of the electrode 52 is 30 μm.
The pattern pitch is 80 μm, and the gap between the stator 51 and the movable element 53 is 10 μm. By miniaturizing this pattern pitch and gap, the mover 5
The torque generated on 3 is larger.

Further, 10 is a drive circuit for applying a predetermined voltage to the electric fi 52 of the stator 51, and since it has the same configuration as that in FIG. 1, its explanation will be omitted.

As shown in the figure, from the drive circuit 10, as in FIG.
11. φB12. There is a three-phase drive output of φC13, and each phase drive voltage is sequentially applied to each electrode 52 as shown in the timing chart of FIG.

As explained above, by forming the electrodes on the substrate 4 and the like by patterning and using a dielectric material as the rotor 1 or the movable body 53, the following effects can be obtained.

(1) By creating electrodes by patterning and miniaturizing the gap between the substrate, etc., and the rotor, etc., it becomes possible to create a small and thin actuator.

(2) With the miniaturization of the gap, the applied voltage can be reduced,
An actuator with lower power consumption can be created.

(3) A special material such as electret is not required for the rotor, and an inexpensive dielectric material such as PZT, glass, or phenol resin may be used.

(4) Since it is driven by electrostatic force, power consumption is extremely low and there is no risk of heat generation due to Joule heat.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an electrostatic actuator with low power consumption that is easy to start up, provides stable rotation, and is made of an inexpensive dielectric material rather than a special material.

[Brief explanation of the drawing]

1 is an exploded perspective view of an embodiment according to the present invention, FIG. 2 is a sectional view of the embodiment shown in FIG. 1, FIG. 3A is a plan view of the rotor of the embodiment, and FIG. Figure (B) is a sectional view of the rotor of this example, Figures 4 (a) and (b) are electrode drive timing charts of this example, and Figures 5 (a) and (b) are rotation of this example. 6A to 6C are plan views of a rotor according to another embodiment of the present invention. FIG. 7 is a front view of a rotor according to another embodiment of the present invention. , FIG. 8 is a perspective view of still another embodiment of the present invention, and FIG. 9 is a plan view of the movable element shown in FIG. 8. In the figure, 1... Rotor, la, lb, 54... Conductive layer, 2... Rotating shaft, 3.52... Electrode, 4... Substrate, 5... Top plate, 6... ... Lower plate, 7, 8 ... Bearing, 9
a to 9d... Spacer and screw, 10... Drive circuit, 21... Electric charge, 22... Lines of electric force, 51... Stator, 53 Mover. Patent applicant: Canon Corporation Figure 1 Figure 2 Figure 3 (A) Figure 3 (B) Figure 14 (0) Figure 4 (b) q Figure 5 (b) Figure 6 (A) Figure 6 Figure (B) Figure 7 -■ Mi Continued Ne City -tE "2" June 101, 1988] Director-General of the Patent Office 1, -+ Indication of Patent Application No. 1982-282159 2, Invention Name M?-+L Actuator 3, Person making the amendment/Relationship with the IS matter Patent applicant Canon Co., Ltd. 4, Agent 2-5-21 2-5-21 Torano, Minato-ku, Tokyo 105 5, Amendment order Date spontaneous 6, subject of correction 4. 7. Contents of the amendment (1) The following shall be inserted between lines 14 and 15 on page 6 of the specification. "However, the relative dielectric constant of the rotor material is lower (ε1=1~
10) is desirable. (2) The bottom line of page 16 of the specification is amended as follows. This mover 53 has a low dielectric constant (for example, ε, =
(3) Correct the figures 5(b) and 7 as shown in the attached sheet. Figure 5 (b) Figure 7

Claims (5)

[Claims] (1) Consisting of a stator in which a plurality of electrodes are arranged at predetermined intervals, and a movable element made of a dielectric material that is movable relative to the electrode arrangement surface of the stator at a fixed interval, The movable element is configured such that the conductivity of at least the surface facing the electrode changes at predetermined intervals, and the movable element is controlled by sequentially applying a voltage to the electrodes of the stator and moving the electric field generated by the electrodes. An electrostatic actuator characterized by being adapted to move. (2) The electrostatic actuator according to claim 1, wherein the electrodes are connected to each other in a plurality of phases, and the movable element is moved by changing the voltage applied to each phase. (3) The conductivity of the surface of the mover is changed by forming a conductive film on the stator side surface of the mover and then removing the conductive film at predetermined intervals to form a pattern. An electrostatic actuator according to claim 1 or 2. (4) The electrostatic actuator according to claim 3, wherein the patterns of the conductive film on the surface of the movable element are arranged as mutually independent patterns. (5) The movable element includes an output shaft, and a plurality of shaft supporting means for pivotally supporting the output shaft on the stator and a plurality of shafts arranged radially at predetermined intervals with respect to the axis of the output shaft on a surface facing the movable element. 5. The electrostatic actuator according to claim 1, further comprising an electrode.