Two-dimensional gimbaled scanning actuator with vertical electrostatic comb-drive for actuation and/or sensing

• US 6,819,822 B2
• Filed: 12/28/2000
• Issued: 11/16/2004
• Est. Priority Date: 03/24/2000
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Kiang, Meng-Hsiung, Behin, Behrang, Daneman, Michael J., Pannu, Satinderpall, Lau, Kam-Yin
• Primary Examiner(s): Sanghavi, Hemang
• Assistant Examiner(s): ROJAS, OMAR R
• Application Number:
  US09/751,660
• Publication Number:
  US 20010048784A1
• Time in Patent Office: 1,419 Days
• Field of Search: 385/16, 385/18, 359/196-199, 359/223, 359/224, 359/226
• US Class Current: 385/18
• CPC Class Codes: B81B 2201/033 Comb drives
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0181 See-saws
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 3/0021 Transducers for transforming electrical into mechanical energy or vice versa dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00
• CPC Class Codes: B81C 1/00214 Processes for the simultaneaous manufacturing of a network or an array of similar microstructural devices
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 26/0866 the reflecting means being moved or deformed by thermal means
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• 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 6/3542 Non-blocking switch, e.g. with multiple potential paths between multiple inputs and outputs, the establishment of one switching path not preventing the establishment of further switching paths
• CPC Class Codes: G02B 6/3546 NxM switch, i.e. a regular array of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• 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: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type

Abstract

A two-dimensional scanner consists of a rotatable gimbal structure with vertical electrostatic comb-drive actuators and sensors. The scanner'"'"'s two axes of rotation may be controlled independently by activating two sets of vertical comb-drive actuators. The first set of vertical comb-drive actuator is positioned in between a outer frame of the gimbal structure and the base, and the second set of vertical comb-drive actuator is positioned in between the inner part of the gimbal structure and the outer frame of the gimbal structure. The inner part of the gimbal structure may include a reflective surface, and the device may be used as a mirror. Furthermore, the capacitance of the vertical comb-drives may be measured to monitor the angular position of the mirror, and the capacitive position-monitoring signal may be used to implement closed-loop feedback control of the mirror angle. The two-dimensional scanner may be fabricated in a semiconductor process. Two-dimensional scanners may be used to produce fiber-optic switches.

Claims

1. A two-dimensional scanner comprising:

a) a base;

b) an outer frame rotatably attached to the base for rotation about a first axis substantially parallel to a plane containing the outer frame and/or the base;

c) an inner part rotatably attached to the outer frame for rotation about a second axis substantially parallel to a plane containing the inner part and/or the outer frame;

d) a first set of comb fingers attached to the outer frame; and

e) a second set of comb fingers attached to the base, wherein the first and second sets of comb fingers interdigitate in a substantially co-planar fashion at some rotation of the outer frame relative to the base about the first axis.

2. The scanner of claim 1, further comprising means for applying a voltage between the first and second set of comb fingers, whereby the comb fingers may act as a comb-drive actuator.

3. The scanner of claim 2, further comprising means for applying a constant biasing force between the outer frame and the base.

4. The scanner of claim 2, further comprising means for sensing an angular position of the outer frame relative to the base.

5. The scanner of claim 4, wherein the means for sensing angular position are chosen from the group consisting of gap-closing electrodes and piezoresistive sensors.

6. The scanner of claim 4, wherein the means for sensing angular position comprises a capacitance sensor electrically coupled between the first and second sets of comb fingers, whereby the comb fingers may act as both a comb-drive actuator and a sensor.

7. The scanner of claim 1, further comprising means for sensing an angular position of the outer frame relative to the base.

8. The scanner of claim 7, wherein the means for sensing angular position includes a capacitance sensor electrically coupled between the first and second sets of comb fingers.

9. The scanner of claim 7, further comprising drive means for rotating the outer frame relative to the base.

10. The scanner of claim 9, wherein the drive means is chosen from the group consisting of gap-closing electrodes, magnetic drives, and piezo drives.

11. The scanner of claim 1, further comprising:

e) a third set of comb fingers attached to the inner part; and

f) a fourth set of comb fingers attached to the outer frame, wherein the third and fourth sets of comb fingers interdigitate at some rotation of the inner part relative to the outer frame about the second axis.

12. The scanner of claim 11, further comprising:

g) means for applying a voltage between the first and second sets of comb fingers, whereby the first and second sets of comb fingers may act as a comb-drive actuator; and

h) means for applying a voltage between the third and fourth sets of comb fingers, whereby the third and fourth sets of comb fingers may act as a comb-drive actuator.

13. The scanner of claim 12, further comprising:

g′

) means for measuring a capacitance between the first and second sets of comb fingers, whereby the first and second sets of comb fingers may act as both a comb-drive actuator and a position sensor; and

h′

) means for measuring a capacitance between the third and fourth sets of comb fingers, whereby the third and fourth sets of comb fingers may act as both a comb-drive actuator and a position sensor.

14. The scanner of claim 12, further comprising:

g″

) means for measuring a capacitance between the first and second sets of comb fingers, whereby the first and second sets of comb fingers may act as a position sensor; and

h″

) means for measuring a capacitance between the third and fourth sets of comb fingers, whereby the third and fourth sets of comb fingers may act as a position sensor.

15. The scanner of claim 14, further comprising drive means for rotating the inner part relative to the outer frame.

16. The scanner of claim 15, wherein the drive means is chosen from the group consisting of gap-closing electrodes, magnetic drives, and piezo drives.

17. The scanner of claim 14, further comprising drive means for rotating the outer frame relative to the base.

18. The scanner of claim 17, wherein the drive means is chosen from the group consisting of gap-closing electrodes, magnetic drives, and piezo drives.

19. The scanner of claim 1, wherein the outer frame is rotatably attached to the base by means selected from the group consisting of torsional flexures, cantilever-like flexures, serpentine flexures, and pin-and-staple type hinges.

20. The scanner of claim 19, wherein the torsional flexures have cross-sections selected from the group consisting of rectangular cross-section, I-shaped cross-section, and T-shaped cross-section.

21. The scanner of claim 1, wherein the inner part is rotatably attached to the outer frame by means selected from the group consisting of torsional flexures, cantilever-like flexures, serpentine flexures, and pin-and-staple type hinges.

22. The scanner of claim 21, wherein the torsional flexures have cross-section selected from the group consisting of rectangular cross-section, I-shaped cross-section, and T-shaped cross-section.

23. A two-dimensional scanner comprising:

a) a base;

b) an outer frame rotatably attached to the base for rotation about a first axis substantially parallel to a plane containing the outer frame and/or the base;

c) an inner part rotatably attached to the outer frame for rotation about a second axis substantially parallel to a plane containing the outer frame and/or the base;

d) a first set of comb fingers attached to the inner part; and

e) a second set of comb fingers attached to the outer frame, wherein the first and second sets of comb fingers interdigitate in a substantially co-planar fashion at some rotation of the inner part relative to the outer frame about the second axis.

24. The scanner of claim 23, further comprising means for applying a voltage between the first and second set of comb fingers, whereby the comb fingers may act as a comb-drive actuator.

25. The scanner of claim 24, further comprising means for applying a constant biasing force between the inner part and the outer frame.

26. The scanner of claim 24, further comprising means for sensing an angular position of the inner part relative to the outer frame.

27. The scanner of claim 26, wherein the means for sensing angular position are chosen from the group consisting of gap-closing electrodes and piezoresistive sensors.

28. The scanner of claim 26, wherein the means for measuring angular position comprises a capacitance sensor electrically coupled between the first and second sets of comb fingers, whereby the comb fingers may act as both a comb-drive actuator and a sensor.

29. The scanner of claim 23, further comprising means for sensing an angular position of the inner part relative to the outer frame.

30. The scanner of claim 29, wherein the means for sensing angular position includes a capacitance sensor electrically coupled between the first and second sets of comb fingers.

31. The scanner of claim 29, further comprising drive means for rotating the outer frame relative to the base.

32. The scanner of claim 31, wherein the drive means is chosen from the group consisting of gap-closing electrodes, magnetic drives, and piezo drives.

33. The scanner of claim 23, wherein the outer frame is rotatably attached to the base by means selected from the group consisting of torsional flexures, cantilever-like flexures, serpentine flexures, and pin-and-staple type hinges.

34. The scanner of claim 33, wherein the torsional flexures have cross-sections selected from the group consisting of rectangular cross-section, I-shaped cross-section, and T-shaped cross-section.

35. The scanner of claim 23, wherein the inner part is rotatably attached to the outer frame by means selected from the group consisting of torsional flexures, cantilever-like flexures, serpentine flexures, and pin-and-staple type hinges.

36. The scanner of claim 35, wherein the torsional flexures have cross-section selected from the group consisting of rectangular cross-section, I-shaped cross-section, and T-shaped cross-section.

37. A fiber-optic switch comprising:

a) an array of input optical fibers;

b) one or more arrays of mirrors for deflecting light from one or more input optical fibers, wherein one or more mirrors in the one or more arrays includes a two-dimensional scanner; and

c) an array of output optical fibers for coupling light emerging from the one or more arrays of mirrors;

wherein the two-dimensional scanner comprises;

i) a base;

ii) an outer frame rotatably attached to the base for rotation about a first axis substantially parallel to a plane containing the outer frame and/or the base;

iii) an inner part rotatably attached to the outer frame for rotation about a second axis substantially parallel to a plane containing the outer frame and/or the base;

iv) a first set of comb fingers attached to the outer frame; and

v) a second set of comb fingers attached to the base, wherein the first and second sets of comb fingers interdigitate in a substantially co-planar fashion at some rotation of the outer frame relative to the base about the first axis.

38. The switch of claim 37, wherein the one or more arrays of mirrors individually steer light from the input optical fibers to the output optical fibers.

39. The switch of claim 37, wherein the input optical fibers and output optical fibers are terminated with microlenses.

40. The switch of claim 37, wherein the inner part includes a mirror.

41. The switch of claim 37, further comprising means for applying a voltage between the first and second set of comb fingers, whereby the first and second sets of comb fingers may act as a comb-drive actuator.

42. The switch of claim 37, further comprising means for sensing a capacitance between the first and second comb fingers, whereby the first and second sets of comb fingers may act as a position sensor for sensing an angular position of the outer frame relative to the base.

43. The switch of claim 42, further comprising means for applying a voltage between the first and second set of comb fingers, whereby the first and second sets of comb fingers may act as both a comb-drive actuator and an angular position sensor.

44. The optical switch of claim 37, further comprising:

e) a third set of comb fingers attached to the inner part; and

f) a fourth set of comb fingers attached to the outer frame, wherein the third and fourth sets of comb fingers interdigitate at some rotation of the inner part relative to the outer frame about the second axis.

45. An optical switch, comprising:

a) an array of input optical fibers;

b) one or more arrays of mirrors for deflecting light from one or more input optical fibers, wherein one or more mirrors in the one or more arrays includes a two-dimensional scanner; and

c) an array of output optical fibers for coupling light emerging from the one or more arrays of mirrors;

wherein the two-dimensional scanner comprises;

i) a base;

ii) an outer frame rotatably attached to the base for rotation about a first axis substantially parallel to a plane containing the outer frame and/or the base;

iii) an inner part rotatably attached to the outer frame for rotation about a second axis substantially parallel to a plane containing the outer frame and/or the base;

iv) a first set of comb fingers attached to the inner part; and

v) a second set of comb fingers attached to outer frame, wherein the first and second sets of comb fingers interdigitate in a substantially co-planar fashion at some rotation of the inner part relative to the outer frame about the second axis.

46. The switch of claim 45, wherein the one or more arrays of mirrors individually steer light from the input optical fibers to the output optical fibers.

47. The switch of claim 45, wherein the input optical fibers and output optical fibers are terminated with microlenses.

48. The switch of claim 45, wherein the inner part includes a mirror.

49. The switch of claim 45, further comprising means for applying a voltage between the first and second set of comb fingers, whereby the first and second sets of comb fingers may act as a comb-drive actuator.

50. The switch of claim 45, further comprising means for sensing a capacitance between the first and second comb fingers, whereby the first and second sets of comb fingers may act as a position sensor for sensing an angular position of the outer frame relative to the base.

51. The switch of claim 50, further comprising means for applying a voltage between the first and second set of comb fingers, whereby the first and second sets of comb fingers may act as both a comb drive actuator and an angular position sensor.