Electrostatic actuator

• US 7,859,370 B2
• Filed: 03/30/2005
• Issued: 12/28/2010
• Est. Priority Date: 03/31/2004
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Mai; Anh T
• Assistant Examiner(s): Rojas; Bernard
• Application Number:
  US11/095,359
• Publication Number:
  US 20050219017A1
• Time in Patent Office: 2,099 Days
• Field of Search: 335/78, 200/181
• 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, 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;

the rocking plate has hollow domed portions;

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

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

the corresponding domed portion surrounds the column capital portion so as not to be separated from the column capital portion.

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, further comprising:

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

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

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

5. 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.

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

the rocking plate is supported so as to pivot about an axis parallel to the line in which the plurality of supporting columns are fixed.

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

the rocking plate is slidable relative to the supporting columns.

8. 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, 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.

9. The electrostatic actuator as set forth in claim 8, 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.

10. The electrostatic actuator as set forth in claim 8, 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.

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

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

12. 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, 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; 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.

13. The microswitch as set forth in claim 12, 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.

14. The microswitch as set forth in claim 12, 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.

15. The microswitch as set forth in claim 12, 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.

16. The microswitch as set forth in claim 15, wherein:

the gap is several tens of nanometers.

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

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

18. 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, 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; 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.