Bistable micromirror with contactless stops

• US 6,778,304 B1
• Filed: 11/10/2003
• Issued: 08/17/2004
• Est. Priority Date: 07/03/2001
• Status: Expired due to Fees

• Current Assignee: Altera Corporation (Intel Corporation)
• Original Assignee: PTS Corporation
• Inventors: Muller, Lilac
• Primary Examiner(s): Phan, James
• Application Number:
  US10/705,390
• Time in Patent Office: 281 Days
• Field of Search: 359/196-226, 359/871-872, 359/900, 359/290-291, 359/293, 359/297-298, 385/18, 385/40, 385/47
• US Class Current: 359/225.1
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/0016 Arrangements for avoiding sticking of the flexible or moving parts not provided for in groups B81B3/0005 - B81B3/0013
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10S 359/90 Methods
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A microstructure for steering light is provided that mitigates stiction. A substrate is provided on which a structural linkage is connected to support a structural film. The structural film includes a reflective coating. A hold electrode is connected with the substrate at a position laterally beyond an orthogonal projection of the structural film on the substrate. It is configured to hold the structural film electrostatically in a tilted position with respect to the substrate upon application of a potential difference between the structural film and the hold electrode. Because of its positioning with respect to the structural film, it is ensured that the structural film is not in contact with the substrate when the structural film is being held by the hold electrode.

Claims

1. A method for operating an optical switch, the method comprising:

tilting a first end of a micromirror assembly towards a substrate by applying a first electrostatic force; and

thereafter, holding the micromirror assembly in a first tilted position with respect to the substrate with a second electrostatic force originating from a point laterally beyond an orthogonal projection of the micromirror assembly on the substrate.

2. The method recited in claim 1 further comprising:

releasing the micromirror assembly from the first tilted position;

thereafter, tilting a second end of the micromirror assembly towards the substrate by applying a third electrostatic force; and

thereafter, holding the micromirror assembly in a second tilted position with respect to the substrate with a fourth electrostatic force originating from a point laterally beyond the orthogonal projection of the micromirror assembly on the substrate.

3. The method recited in claim 2 further comprising:

selecting the first tilted position from a plurality of possible first tilted positions by establishing a potential difference between the micromirror assembly and a first electrode used to establish the second electrostatic force; and

selecting the second tilted position from a plurality of possible second tilted positions by establishing a potential difference between the micromirror assembly and a second electrode used to establish the fourth electrostatic force.

4. The method recited in claim 3 wherein the plurality of possible first tilted positions are defined by first angles with respect to the substrate that deviate increasingly from horizontal with an increase in the potential difference between the micromirror assembly and the first electrode.

5. The method recited in claim 4 wherein the plurality of possible second tilted positions are defined by second angles with respect to the substrate that deviate increasingly from horizontal with an increase in the potential difference between the micromirror assembly and the second electrode.

6. The method recited in claim 2 wherein the third electrostatic force originates at a point laterally within the orthogonal projection of the micromirror assembly on the substrate.

7. The method recited in claim 1 further comprising selecting the first tilted position from a plurality of possible first tilted positions by establishing a potential difference between the micromirror assembly and a first electrode used to establish the second electrostatic force.

8. The method recited in claim 7 wherein the plurality of first tilted positions are defined by angles with respect to the substrate that deviate increasingly from horizontal with an increase in the potential difference between the micromirror assembly and the first electrode.

9. The method recited in claim 1 wherein the first electrostatic force originates at a point laterally within the orthogonal projection of the micromirror assembly on the substrate.