MEMS device comprising oscillations measurements means

• US 8,626,468 B2
• Filed: 06/21/2009
• Issued: 01/07/2014
• Est. Priority Date: 07/02/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Inventors: Luft, Ido, Goren, Nir
• Primary Examiner(s): Doak, Jennifer L.
• Application Number:
  US13/002,378
• Publication Number:
  US 20110181931A1
• Time in Patent Office: 1,661 Days
• Field of Search: 3591981-1994, 3592006-2008, 359/202.1, 359/221.2, 3592231-2251, 359/226.2, 359/904, 359290-295, 359/838, 359/846, 359/871, 359/872, 250/204, 250/559.06, 250/559.29, 250/230, 250/234, 347255-260, 353/39, 353 98- 99, 385 15- 18, 385/22, 398/12, 398/19, 398/45
• US Class Current: 702/103
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 7/02 containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] B81B7/04 takes precedence

Abstract

A MEMS apparatus is provided for scanning an optical beam which comprises: a. at least one mirror operative to perform am oscillation motion to a pre-defined rotation angle around a mirror rotation axis; b. a sound sensing means; and c. a conversion means operative to convert sound vibrations detected by the sound sensing means into one or more electrical signals, and wherein the sound sensing means is located at the vicinity of the at least one mirror whereby the movement of the at least one mirror is sensed by the sound sensing means and converted by the conversion means into the one or more electrical signals characterizing the oscillating motion of the at least one mirror.

Claims

1. A MEMS apparatus comprising:

at least one mirror configured to perform an oscillation motion to a pre-defined rotation angle around a mirror rotation;

a sound sensor in direct physical contact with the at least one mirror and configured to sense sound vibrations indicative of movement of the at least one mirror; and

a conversion circuit configured to convert the sound vibrations detected by the sound sensor into one or more electrical signals.

2. An apparatus according to claim 1, wherein said one or more electrical signals are used in determining whether said mirror is oscillating.

3. An apparatus according to claim 2, further comprising a control circuit configured to control the oscillation motion of said at least one mirror, wherein if the value of said one or more electrical signals is less than a pre-defined value, said control circuit ceases operation of said MEMS apparatus.

4. An apparatus according to claim 1, wherein said one or more electrical signals are used in determining an absolute phase at which said mirror oscillates.

5. An apparatus according to claim 1, wherein said sound sensor is used in generating one or more electrical signals for characterizing oscillating motion of said at least one mirror.

6. An apparatus according to claim 1, wherein said sound sensor is operative in the audio and/or ultrasonic range.

7. An apparatus according to claim 6, wherein said sound sensor comprises at least one microphone.

8. An apparatus according to claim 6, wherein said sound sensor comprises at least one ultrasonic transducer.

9. An apparatus according to claim 1, wherein said sound sensor is operative in a range extending from about few tens of Hz to about few tens of kHz.

10. An apparatus, comprising:

a MEMS mirror;

a control circuit configured to drive an oscillating movement of said MEMS mirror;

a sensing circuit in direct physical contact with the MEMS mirror and configured to sense sound produced by oscillating movement of said MEMS mirror;

wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of sensed sound to detect at least one of an amplitude and a phase of said oscillating movement.

11. The apparatus of claim 10, wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of sensed sound to detect a position of said MEMS mirror.

12. The apparatus of claim 10, wherein the sensed sound comprises audio sound.

13. The apparatus of claim 10, wherein the sensed sound comprises ultrasonic sound.

14. The apparatus of claim 10, wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of sensed sound to detect failure of said oscillating movement.

15. The apparatus of claim 14, wherein said control circuit is further configured to turn off a light source whose output is directed at the MEMS mirror in response to detected failure of said oscillating movement.

16. The apparatus of claim 10, wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of sensed sound to synchronize operation of other devices with the oscillating movement of the MEMS mirror.

17. An apparatus, comprising:

a plurality of MEMS mirrors;

a control circuit configured to drive oscillating movement of said plurality of MEMS mirrors;

a sensing circuit configured to sense sound produced by said oscillating movement of said plurality of MEMS mirrors;

wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of said sensed sound to detect at least one of an amplitude and a phase of said oscillating movement.

18. The apparatus of claim 17, wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of sensed sound to detect a position of at least one of said MEMS mirrors.

19. The apparatus of claim 17, wherein the sensed sound comprises audio sound.

20. The apparatus of claim 17, wherein the sensed sound comprises ultrasonic sound.

21. The apparatus of claim 17, wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of said sensed sound to detect failure of said oscillating movement associated with at least one of said MEMS mirrors.

22. The apparatus of claim 21, wherein said control circuit is further configured to turn off a light source that has an output directed at said MEMS mirrors in response to the detected failure of said oscillating movement.

23. The apparatus of claim 17, wherein said control circuit is further configured to process signals output from said sensing circuit that are indicative of said sensed sound to synchronize operation of other devices with the oscillating movement of said MEMS mirrors.