Electrostatic actuator

• US 20050219017A1
• Filed: 03/30/2005
• Published: 10/06/2005
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shirakawa, Kazuhiko
• Granted Patent: US 7,859,370 B2
• Time in Patent Office: Days
• US Class Current: 335/78
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833
• CPC Class Codes: G02B 6/3552 1x1 switch, e.g. on/off switch
• CPC Class Codes: G02B 6/3564 Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: H01H 2059/0054 Rocking contacts or actuating members
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A switch with an actuator has two supporting columns on a substrate, and a rocking plate on the supporting columns. The rocking plate is pivoted by (pivotally mounted on) the two supporting columns. The rocking plate is made of conductive material, so that it can be subjected to electrostatic force of an adsorption electrode. In the switch, it is not necessary to provide a narrow beam to support the rocking plate, because the rocking plate is pivoted by the supporting columns. Therefore, the switch is a long-life microswitch.

Claims

1. An electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator comprising:

a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate.

2. The electrostatic actuator as set forth in claim 1, wherein:

the number of the supporting columns is two.

3. The electrostatic actuator as set forth in claim 1, wherein:

each of the supporting columns has a leg portion and a column capital portion, the leg portion being a portion fixed on the substrate and the column capital portion being a portion provided on the leg portion and thicker than the leg portion;

the rocking plate has hollow domed portions; and

the column capital portion of each of the supporting columns is engaged with a corresponding domed portion.

4. The electrostatic actuator as set forth in claim 3, wherein:

each of the domed portions has an inner wall having a spherical surface shape, and the column capital portion of each of the supporting columns has a spherical surface shape at a portion that contacts the corresponding domed portion.

5. The electrostatic actuator as set forth in claim 3, wherein:

each of the domed portions has an inner wall having a triangular pyramid shape, and the column capital portion of each of the supporting columns has a triangular pyramid shape at a portion that contacts the corresponding domed portion.

6. The electrostatic actuator as set forth in claim 3, wherein:

the column capital portion and the leg portion of each of the supporting columns are made of polycrystalline silicon.

7. The electrostatic actuator as set forth in claim 1, further comprising:

an adsorption electrode control circuit, which is provided on the substrate, for controlling the adsorption electrode.

8. The electrostatic actuator as set forth in claim 1, wherein:

the supporting columns are connected to electrodes for fixing potentials of the supporting columns.

9. The electrostatic actuator as set forth in claim 1, wherein:

the substrate is an anti-insulating substrate, a ceramic substrate, an InP substrate, a GaN substrate, or an SiC substrate.

10. A microswitch, comprising:

an electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator including a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate; and

a pair of signal line electrodes, which are provided on the substrate, for being electrically connected to each other through the rocking plate when the rocking plate is attracted toward the substrate.

11. The microswitch as set forth in claim 10, further comprising:

a contact electrode, which is provided on the rocking plate at such a portion as to contact the pair of signal line electrodes, for electrically connecting the pair of signal line electrodes.

12. The microswitch as set forth in claim 10, further comprising:

a dielectric material provided on at least one of (i) the pair of signal line electrodes at such a portion as to contact the rocking plate and (ii) the rocking plate at such a portion as to contact the pair of signal line electrodes.

13. The microswitch as set forth in claim 10, further comprising:

a stopper, which is provided on the substrate, for limiting a driven range of the rocking plate, so as to create a gap between the rocking plate and the pair of signal line electrodes when the rocking plate is attracted toward the substrate.

14. The microswitch as set forth in claim 13, wherein:

the gap is several tens of nanometers.

15. The microswitch as set forth in claim 10, further comprising:

a signal circuit provided on the substrate and connected to the pair of signal line electrodes.

16. An RF circuit, comprising:

a microswitch including

an electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator including a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate; and

a pair of signal line electrodes, which are provided on the substrate, for being electrically connected to each other through the rocking plate when the rocking plate is attracted toward the substrate.

17. The RF circuit as set forth in claim 16, further comprising:

at least one of a capacitor, an inductor, a resistor, and a filter, a connection state of which is controlled by the microswitch.

18. A micro optical switch, comprising:

an electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator including a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate; and

a light-reflecting film provided on the rocking plate of the electrostatic actuator.

19. A micro optical switch system, comprising:

a micro optical switch including

an electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator including a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate; and

a light-reflecting film provided on the rocking plate of the electrostatic actuator;

a light source for emitting light onto the light-reflecting film of the micro optical switch; and

a light receiver for receiving reflected light from the light-reflecting film.

20. The micro optical switch system as set forth in claim 19, wherein:

the light source is an input-use optical waveguide for outputting an optical signal received from outside toward the light-reflecting film; and

the light receiver is an output-use optical waveguide for receiving the optical signal reflected on the light-reflecting film and outputting the optical signal toward outside.

21. The micro optical switch system as set forth in claim 19, wherein:

the light source is a light-emitting element for emitting light in accordance with an electric signal received from outside onto the light-reflecting film; and

the light receiver is a light-receiving element for receiving the light reflected on the light-reflecting film, converting the light into an electric signal, and outputting the electric signal.

22. The micro optical switch system as set forth in claim 19, further comprising:

a light-condensing lens provided on a surface of at least one of the light source and the light receiver.

23. The micro optical switch system as set forth in claim 19, further comprising:

a case for covering the light source and the light receiver, the case having an inner wall that does not reflect light.

24. The micro optical switch system as set forth in claim 23, further comprising:

a wire connected to the adsorption electrode and provided so as to run through the substrate.

25. A communication device, comprising:

a microswitch including

an electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator including a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate; and

a pair of signal line electrodes, which are provided on the substrate, for being electrically connected to each other through the rocking plate when the rocking plate is attracted toward the substrate.

26. A communication device, comprising:

a micro optical switch system including

an electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator including a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate; and

a light-reflecting film provided on the rocking plate of the electrostatic actuator;

a light source for emitting light onto the light-reflecting film of the micro optical switch; and

a light receiver for receiving reflected light from the light-reflecting film.

27. A method of manufacturing an electrostatic actuator in which a rocking plate is electrostatically attracted by an adsorption electrode provided on a substrate, the electrostatic actuator including a plurality of supporting columns, which are fixed on the substrate and arranged in a line, for pivotally supporting the rocking plate, the method comprising:

a first step, in which the supporting columns and the adsorption electrode are formed on the substrate;

a second step, in which a sacrificial film is formed on an entire surface of the substrate, including the supporting columns;

a third step, in which a conductive film is formed on the sacrificial film;

a fourth step, in which the rocking plate is formed by patterning the conductive film; and

a fifth step, in which the sacrificial film, which is under the rocking plate, is removed.

28. The method as set forth in claim 27, wherein:

in the fourth step, a through hole is formed in the rocking plate.