High performance MEMS scanner

• US 20050179976A1
• Filed: 11/12/2004
• Published: 08/18/2005
• Est. Priority Date: 02/09/2004
• Status: Active Grant

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Brown, Dean R., Montague, Thomas W., Sprague, Randall B., Davis, Wyatt O.
• Granted Patent: US 7,482,730 B2
• Time in Patent Office: Days
• US Class Current: 359/224.100
• 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 26/0841 the reflecting element being moved or deformed by electrostatic 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 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence

Abstract

A high performance MEMS scanner is disclosed. In some embodiments, scanner mirror has a wide and short aspect ratio that is similar to rotating polygon facets. Long torsion arms allow large rotation angles including 20° zero-to-peak mechanical and greater. Suspensions couple the scan mirror to torsion arms, reducing dynamic mirror deformation by spreading the torque load. “leverage members” at the distal ends of the torsion arms help reduce stress concentrations. Elimination of a mounting frame increases device yield. Heater leads allow for precise trimming of the scanner resonant frequency. A compressive mount holds mounting pads against mounting structures.

Claims

1. A MEMS scanner;

comprising;

a scan plate having longitudinal and lateral dimensions;

a first torsion arm coupled to the scan plate and extending longitudinally from a proximal to a distal location therefrom, the first torsion arm defining an axis of rotation of the scan plate;

a first leverage member coupled to the distal location of the first torsion arm and extending laterally therefrom in opposing directions from an axial location coincident with the first torsion arm to two lateral locations, the lateral locations forming junctions with one or more mounting structures.

2. The MEMS scanner of claim 1;

wherein the first leverage member is substantially straight.

3. The MEMS scanner of claim 1;

wherein the first leverage member is of a serpentine shape.

4. The MEMS scanner of claim 1;

wherein the first leverage member is axially symmetric with respect to the first torsion arm.

5. The MEMS scanner of claim 1;

wherein the first leverage member is axially asymmetric with respect to the first torsion arm.

6. The MEMS scanner of claim 1;

wherein the one or more mounting structures includes two mounting pads, each pad being coupled to a respective lateral location of the first leverage member.

7. The MEMS scanner of claim 1;

wherein the one or more mounting structures includes a mounting frame, the mounting frame being coupled to the lateral locations of the first leverage member.

8. The MEMS scanner of claim 1;

wherein the first torsion arm is the only torsion arm.

9. The MEMS scanner of claim 1;

wherein at least one of the support structures includes a piezo-electric stack actuator.

10. The MEMS scanner of claim 1;

further comprising a mirror formed on a surface of the scan plate.

11. The MEMS scanner of claim 1;

further comprising;

a suspension; and

wherein the scan plate is coupled to the respective first torsion arm through the suspension, the suspension being operative to spread a dynamic torque load across the scan plate.

12. The MEMS scanner of claim 1;

further comprising;

a second torsion arm, coaxial to the first torsion arm, coupled to the scan plate and extending longitudinally from a proximal to a distal location therefrom, the second torsion arm cooperating with the first torsion arm to form the axis of rotation of the scan plate;

a second leverage member coupled to the distal location of the second torsion arm and extending laterally therefrom in opposing directions from an axial location coincident with the second torsion arm to two lateral locations, the lateral locations forming junctions with one or more mounting structures.

13. The MEMS scanner of claim 12;

wherein the one or more mounting structures include first, second, third, and fourth mounting pads, each mounting pad coupled to a lateral location of a respective leverage member.

14. The MEMS scanner of claim 12;

wherein the one or more mounting structures includes a mounting frame, the mounting frame being coupled to the lateral locations of the first and second leverage members.

15. The MEMS scanner of claim 13;

further comprising first, second, third, and fourth clamps, each clamp coupled to compressively hold a respective mounting pad against a respective support structure.

16. The MEMS scanner of claim 15;

wherein at least one of the support structures includes a piezo-electric stack actuator.

17. The MEMS scanner of claim 16;

wherein two of the support structures include respective piezo-electric stack actuators and two of the support structures include a substantially immoveable housing.

18. The MEMS scanner of claim 12;

further comprising a mirror formed on a surface of the scan plate.

19. The MEMS scanner of claim 12;

wherein the scan plate, the two torsion arms, and the two leverage members are formed from silicon.

20. The MEMS scanner of claim 12;

further comprising;

first and second opposed suspensions; and

wherein the scan plate is coupled to the respective first and second torsion arms through the first and second opposed suspensions, the first and second opposed suspensions being operative to spread a dynamic torque load across the scan plate.

21. The MEMS scanner of claim 12;

wherein;

the one or more mounting structures include at least two mounting pads, each of the at least two mounting pads being coupled to a respective leverage member.

22. The MEMS scanner of claim 21;

further comprising;

at least two conductive leads, each conductive lead being electrically coupled to a respective one of the two or more mounting pads.

23. The MEMS scanner of claim 22;

wherein the at least two conductive leads are operable to apply an electrical potential across the first and second leverage members, the first and second torsion arms, and the scan plate.

24. The MEMS scanner of claim 22;

wherein the at least two conductive leads are operable to apply an electrical potential across the MEMS scanner, the electrical potential being operative to modify a resonant frequency of the MEMS scanner.

25. The MEMS scanner of claim 12;

wherein the length of each torsion arm is greater than about two times the longitudinal dimension of the scan plate.

26. The MEMS scanner of claim 25;

wherein the length of each torsion arm is greater than about four times the longitudinal dimension of the scan plate.

27. A MEMS scanner;

comprising;

a scan plate having a lateral dimension and a longitudinal dimension;

first and second opposed torsion arms, each torsion arm coupled to the scan plate and extending longitudinally from a proximal to a distal location therefrom, the first and second torsion arms defining an axis of rotation of the scan plate; and

first and second opposed mounting structures, each mounting structure coupled to a distal location of a respective torsion arm; and

wherein, each of the first and second torsion arms has a length greater than about four times the longitudinal dimension of the scan plate.

28. The MEMS scanner of claim 27, wherein the first and second opposed mounting structures further include:

first and second opposed leverage members, each leverage member coupled to a distal location of a respective torsion arm and extending laterally therefrom in opposing directions from an axial location coincident with a respective torsion arm to two equidistant lateral locations, the equidistant lateral locations forming a junction with one or more mounting structures.

29. The MEMS scanner of claim 28;

wherein the first and second mounting structures include first, second, third, and fourth mounting pads, each mounting pad coupled to an equidistant lateral location of a respective leverage member.

30. The MEMS scanner of claim 29;

further comprising first, second, third, and fourth clamps, each clamp coupled to compressively hold a respective mounting pad against a respective support structure.

31. The MEMS scanner of claim 30;

wherein at least one of the support structures includes a piezo-electric stack actuator.

32. The MEMS scanner of claim 31;

wherein two of the support structures include respective piezo-electric stack actuators and two of the support structures include a substantially immoveable housing.

33. The MEMS scanner of claim 27;

further comprising a mirror formed on a surface of the scan plate.

34. The MEMS scanner of claim 27;

wherein the scan plate, the two torsion arms, and the two leverage members are formed from silicon.

35. The MEMS scanner of claim 27;

further comprising;

first and second opposed suspensions; and

wherein the scan plate is coupled to the respective first and second torsion arms through the first and second opposed suspensions, the first and second opposed suspensions being operative to spread a dynamic torque load across the scan plate.

36. The MEMS scanner of claim 27;

wherein;

the first and second mounting structures each include a leverage member coupled to a respective torsion arm and at two or more mounting pads, each of the two or more mounting pads being coupled to an end of the respective leverage member.

37. The MEMS scanner of claim 36;

further comprising;

at least two conductive leads, each conductive lead being electrically coupled to a respective one of the two or more mounting pads.

38. The MEMS scanner of claim 37;

wherein the at least two conductive leads are operable to apply an electrical potential across the first and second leverage members, the first and second torsion arms, and the scan plate.

39. The MEMS scanner of claim 37;

wherein the at least two conductive leads are operable to apply an electrical potential across the MEMS scanner, the electrical potential being operative to modify a resonant frequency of the MEMS scanner.

40. The MEMS scanner of claim 27;

wherein the lateral dimension of the scan plate is greater than about four times the longitudinal dimension of the scan plate.

41. The MEMS scanner of claim 40;

wherein the lateral dimension of the scan plate is greater than about eight times the longitudinal dimension of the scan plate.

42. A MEMS scanner;

comprising;

a scan plate having a lateral dimension and a longitudinal dimension;

first and second opposed torsion arms, each torsion arm coupled to the scan plate and extending longitudinally from a proximal to a distal location therefrom, the first and second torsion arms defining an axis of rotation of the scan plate; and

first and second opposed mounting structures, each mounting structure coupled to a distal location of a respective torsion arm; and

first and second heater leads coupled to respective first and second opposed mounting structures, the heater leads being operable to pass current through the MEMS scanner to produce joule heating in the MEMS scanner.

43. The MEMS scanner of claim 42;

wherein the first and second mounting structures each include;

a leverage member, coupled to the distal location of the respective torsion arm and extending laterally therefrom in opposing directions from an axial location coincident with the respective torsion arm to two equidistant lateral points.

44. The MEMS scanner of claim 43;

wherein the first and second mounting structures each includes first and second mounting pads, each mounting pad coupled to the equidistant lateral point of a respective leverage member.

45. The MEMS scanner of claim 44;

further comprising first, second, third, and fourth clamps, each clamp coupled to compressively hold a respective mounting pad against a respective support structure.

46. The MEMS scanner of claim 44;

wherein the first and second heater leads are each electrically coupled to one of the first and second mounting pads coupled to each of the two leverage members.

47. The MEMS scanner of claim 46;

wherein the first and second heater leads are operable to apply an electrical potential across the first and second leverage members, the first and second torsion arms, and the scan plate.

48. The MEMS scanner of claim 46;

wherein the first and second heater leads are operable to apply an electrical potential across the MEMS scanner, the electrical potential being operative to modify a resonant frequency of the MEMS scanner.

49. The MEMS scanner of claim 45;

wherein at least one of the support structures includes a piezo-electric stack actuator.

50. The MEMS scanner of claim 49;

wherein two of the support structures include respective piezo-electric stack actuators and two of the support structures include a substantially immoveable housing.

51. The MEMS scanner of claim 43;

wherein the scan plate, the two torsion arms, and the two leverage members are formed from silicon.

52. The MEMS scanner of claim 42;

further comprising a mirror formed on a surface of the scan plate.

53. The MEMS scanner of claim 42;

further comprising;

first and second opposed suspensions; and

wherein the scan plate is coupled to the respective first and second torsion arms through the first and second opposed suspensions, the first and second opposed suspensions being operative to spread a dynamic torque load across the scan plate.

54. The MEMS scanner of claim 42;

wherein the lateral dimension of the scan plate is greater than about four times the longitudinal dimension of the scan plate.

55. The MEMS scanner of claim 54;

wherein the lateral dimension of the scan plate is greater than about eight times the longitudinal dimension of the scan plate.

56. The MEMS scanner of claim 42;

wherein the length of each torsion arm is greater than about four times the longitudinal dimension of the scan plate.

57. The MEMS scanner of claim 56;

wherein the length of each torsion arm is greater than about 8 times the longitudinal dimension of the scan plate.

58. A MEMS scanner;

comprising;

a scan plate having a lateral dimension and a longitudinal dimension;

first and second opposed torsion arms, each torsion arm coupled to the scan plate and extending longitudinally from a proximal to a distal location therefrom, the first and second torsion arms defining an axis of rotation of the scan plate; and

first and second opposed mounting structures, each mounting structure coupled to a distal location of a respective torsion arm; and

at least two clamps, each clamp coupled to compressively hold a respective mounting structure against a respective support structure.

59. The MEMS scanner of claim 58;

wherein the first and second mounting structures each include;

a leverage member, coupled to the distal location of the respective torsion arm and extending laterally therefrom in opposing directions from an axial location coincident with the respective torsion arm to two equidistant lateral points.

60. The MEMS scanner of claim 59;

wherein the first and second mounting structures each includes first and second mounting pads, each mounting pad coupled to the equidistant lateral point of a respective leverage member.

61. The MEMS scanner of claim 60;

wherein the at least two clamps includes first, second, third, and fourth clamps, each clamp coupled to compressively hold the respective mounting pad against the respective support structure.

62. The MEMS scanner of claim 61;

wherein at least one of the support structures includes a piezo-electric stack actuator.

63. The MEMS scanner of claim 62;

wherein two of the support structures include respective piezo-electric stack actuators and two of the support structures include a substantially immoveable housing.

64. The MEMS scanner of claim 58;

further comprising;

first and second opposed suspensions; and

wherein the scan plate is coupled to the respective first and second torsion arms through the first and second opposed suspensions, the first and second opposed suspensions being operative to spread a dynamic torque load across the scan plate.

65. The MEMS scanner of claim 58;

wherein the scan plate, torsion arms, and mounting structures are composed of a semiconductor.

66. The MEMS scanner of claim 65;

wherein the semiconductor is silicon.

67. A MEMS scanner;

comprising;

a first mounting structure;

a first torsion arm coupled to the first mounting structure;

a scan mirror coupled to the first torsion arm, the scan mirror being operable to rotate to and fro around a scan axis defined by the first torsion arm;

a second torsion arm substantially coaxial with the first torsion arm coupled to the scan mirror; and

a second mounting structure, separate from the first mounting structure, coupled to the second torsion arm.

68. The MEMS scanner of claim 67;

wherein the first mounting structure, first torsion arm, scan mirror, second torsion arm, and second mounting structure are formed from a single piece of silicon.

69. The MEMS scanner of claim 68;

further comprising a layer of metal on a surface of the scan mirror.

70. The MEMS scanner of claim 67;

wherein the first mounting structure further includes;

a first mounting pad;

a first connecting arm operably connected at a first end to the first mounting pad and at a second end to the first torsion arm;

a second connecting arm operably connected at a first end to the first torsion arm; and

a second mounting pad operably connected to a second end of the second connecting arm.