Active tuning of a torsional resonant structure

• US 20040196518A1
• Filed: 01/30/2004
• Published: 10/07/2004
• Est. Priority Date: 08/05/1999
• Status: Active Grant

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Tegreene, Clarence T., Helsel, Mark P., Wine, David W.
• Granted Patent: US 7,002,716 B2
• Time in Patent Office: Days
• US Class Current: 359/204.4
• 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 26/085 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 26/10 Scanning systems
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G09G 2300/0469 Details of the physics of pixel operation
• CPC Class Codes: G09G 3/025 with scanning or deflecting the beams in two directions or dimensions
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: G09G 5/005 Adapting incoming signals to the display format of the display terminal
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

A MEM s scanning device has a variable resonant frequency. In one embodiment, the MEMs device includes a flexible arm that extends from a oscillatory body. An electrical field applies a force to the flexible arm, thereby bending the flexible arm to shift the moment of inertia of the oscillatory body and a secondary mass carried by the flexible arm. The shifted moment of inertia changes the resonant frequency of the MEMs device. In another embodiment, an absorptive material forms a portion of a torsional arm that supports the oscillatory body. The mechanical properties of the absorptive material can be varied by varying the concentration of a gas surrounding the absorptive material. The varied mechanical properties change the resonant frequency of the scanning device. A display apparatus includes the scanning device and the scanning device scans about two or more axes, typically in a raster pattern. Various approaches to controlling the frequency responses of the scanning device are described, including active control of MEMs scanners and passive frequency tuning.

Claims

1. -39. (Cancelled)

40. A beam scanner, comprising:

a plurality of light sources operable to emit a plurality of respective beams of light; and

at least one beam deflector aligned to receive the plurality of beams of light from the plurality of light sources and operable to scan the beams across respective overlapping regions of a field of view.

41. The beam scanner of claim 40, wherein the plurality of light sources includes a plurality of light emitting diodes.

42. The beam scanner of claim 41, wherein the plurality of light emitting diodes are operable to produce a plurality of colors of light.

44. The beam scanner of claim 40, wherein the plurality of light sources are operable to vary the intensity of the plurality of beams.

45. The beam scanner of claim 44, wherein the plurality of light sources are operable to vary the intensity of the plurality of beams to blend overlapping regions of the field of view.

46. The beam scanner of claim 45, wherein the light sources are operable to produce pixels, and data corresponding to pixel values is scaled to limit the intensity of overlapping pixels in the overlapping regions of the filed of view.

47. The beam scanner of claim 40, wherein the at least one beam deflector is a single beam deflector.

48. The beam scanner of claim 40, wherein the at least one beam deflector includes a microelectromechanical (MEMs) scanner.

49. The beam scanner of claim 48, wherein the microelectromechanical (MEMs) scanner is operable to scan the plurality of beams in at least two dimensions.

50. The beam scanner of claim 49, wherein the overlapping regions of the field of view are arranged such that each region extends horizontally across substantially the entire field of view and overlaps with at least one vertically adjacent regions.

51. The beam scanner of claim 40, wherein the overlapping regions are substantially distinct and overlap slightly.

76. The scanned beam display of claim 45, wherein the scaling of power is operative to blend the at least partially overlapping beams.

43. The beam scanner of claim 43, wherein the plurality of light emitting diodes are operable to produce a plurality of beams in each of the plurality of colors of light.

52. A method for blending illuminated regions in a field of view, comprising the steps of:

generating a plurality of beams of light;

directing the plurality of beams of light toward a scanner;

scanning the plurality of beams of light across a field of view, whereby each of the plurality of scanned beams illuminates a respective region of the field of view that overlaps with at least one other of the respective regions; and

modulating the intensity of each of the plurality of beams of light to compensate for the illumination energy produced by the other beams.

53. The method for blending illuminated regions in a field of view of claim 52, further comprising the step of:

modulating the intensity of the beams to produce an image on the field of view.

54. The method for blending illuminated regions in a field of view of claim 52, wherein the illuminated field of view includes an image plane in a display.

55. The method for blending illuminated regions in a field of view of claim 54, wherein the image plane includes the retina of a user.

56. The method for blending illuminated regions in a field of view of claim 54, wherein the image plane includes a projection screen.

57. The method for blending illuminated regions in a field of view of claim 56, wherein the projection screen is a rear projection screen.

58. The method for blending illuminated regions in a field of view of claim 56, wherein the projection screen is a front projection screen.

59. The method for blending illuminated regions in a field of view of claim 52, further comprising the steps of:

receiving a image for display; and

modulating the intensity of the plurality of beams of light to produce an illuminated pattern in the field of view corresponding to the image.

60. The method for blending illuminated regions in a field of view of claim 59, wherein the illuminated pattern is formed from pixels generated by the plurality of beams of light.

61. An image capture device, comprising:

a beam scanner operable to scan a plurality of beams across a field-of-view;

a detector aligned to receive beam energy scattered from the field-of-view and output an electrical signal corresponding to the received energy; and

a controller coupled to receive the electrical signal from the detector and output a representation of the received beam energy.

62. The image capture device of claim 61, further comprising:

a mechanical housing that encloses the beam scanner, detector and controller.

63. The image capture device of claim 62, wherein the mechanical housing includes a window for transmitting and receiving light energy.

64. The image capture device of claim 61, wherein the plurality of beams are encoded to make them distinct.

65. The image capture device of claim 64, wherein the plurality of beams are produced at two or more distinct wavelengths.

66. The image capture device of claim 64, wherein the plurality of beams are modulated at carrier frequencies.

67. The image capture device of claim 64, wherein the plurality of beams are emitted sequentially.

68. The image capture device of claim 61, wherein the plurality of beams are scanned across a respective plurality of regions of the field-of-view.

69. The image capture device of claim 68, wherein the plurality of respective regions at least partially overlap over at least a portion of a depth-of-field.

70. The image capture device of claim 69, wherein the controller is operable to stitch together data corresponding to the plurality of regions.

71. A scanned beam display, comprising:

a controller operable to receive an image signal and generate a control signal having plural instances of at least some pixels; and

a beam scanner coupled to receive the control signal from the controller and operable to scan a plurality of at least partially overlapping beams across a field-of-view.

72. The scanned beam display of claim 71, wherein the plural instances of pixels correspond to the regions of beam overlap.

73. The scanned beam display of claim 72, wherein each beam contributing to an overlapping region receives a scaled portion of the energy allocated to each pixel in the overlapping region.

74. The scanned beam display of claim 73, wherein the scaled portion of energy allocated to each pixel is selected to blend the overlapping region.

75. The scanned beam display of claim 72, wherein the controller is operable to cause scaling of power delivered to each of the plural instances of pixels.

77. The scanned beam display of claim 71, further comprising:

a screen aligned to receive the scanned beams.

78. The scanned beam display of claim 77, wherein the screen is a projection screen for viewing by an observer.

79. The scanned beam display of claim 78, further comprising:

a beam expander aligned to receive the scanned beams and operable to project beamlets to the eye of an observer.