Circuits for controlling display apparatus

• US 20070086078A1
• Filed: 12/01/2006
• Published: 04/19/2007
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Barton, Roger, Payne, Richard, Lewis, Stephen, McAllister, Abraham, Steyn, Jasper, Hagood, Nesbitt
• Granted Patent: US 8,310,442 B2
• Time in Patent Office: Days
• US Class Current: 359/298
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0838 with level shifting
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38
• CPC Class Codes: G09G 3/3473 based on light coupled out of a light guide, e.g. due to scattering, by contracting the light guide with external means

Abstract

The invention relates to methods and apparatus for forming images on a display utilizing a control matrix to control the movement of MEMs-based light modulators.

Claims

1. A direct-view display apparatus comprising:

a transparent substrate,

an array of pixels including, for each pixel, a MEMS-based light modulator formed on the substrate and including a first actuator and a second actuator opposing the first actuator for controlling the state of the light modulator; and

a control matrix connected to the substrate including, for a pixel in the array of pixels, i) a write-enabling switch for enabling the pixel to respond to a data voltage, iii) a data switch for selectively controlling actuation of one of the first and second actuators, and iv) only one data voltage interconnect for setting a desired state of the light modulator to form an image, wherein a voltage applied to the data voltage interconnect controls the data switch.

2. The direct-view display apparatus of claim 1, wherein the data switch controls the actuation of both the first and the second actuators.

3. The direct-view display apparatus of claim 2, wherein the array comprises a plurality of columns of pixels, and wherein a plurality of the pixels in a column share a common data voltage interconnect.

4. The direct-view display apparatus of claim 2, wherein for each pixel, the control matrix comprises a voltage inverter circuit.

5. The direct-view display apparatus of claim 4, wherein the voltage inverter circuit comprises one of an nMOS voltage inverter circuit, a pMOS voltage inverter circuit, and a CMOS voltage inverter circuit.

6. The direct-view display apparatus of claim 4, wherein the voltage inverter circuit comprises a level shifting inverter.

7. The direct-view display apparatus of claim 4, wherein the voltage inverter circuit comprises a transition sharpening inverter.

8. The direct-view display apparatus of claim 4, wherein the voltage inverter circuit comprises a switching inverter.

9. The direct-view display apparatus of claim 2, wherein each pixel comprises a flip-flop.

10. The direct-view display apparatus of claim 9, wherein the flip-flop electrically couples the first and second actuators to one another.

11. The direct-view display apparatus of claim 8, wherein the flip-flop stores light modulator control instructions.

12. The direct-view display apparatus of claim 2, wherein each pixel comprises a cross-coupled inverter.

13. The direct-view display apparatus of claim 12, wherein the cross-coupled inverter electrically couples the first and second actuators to one another.

14. The direct-view display apparatus of claim 12, wherein the cross-coupled inverter stores modulator control instructions.

15. The direct-view display apparatus of claim 12, wherein the cross-coupled inverter comprises a level shifting inverter.

16. The direct-view display apparatus of claim 2, wherein the light modulators comprise shutter assemblies.

17. The direct-view display apparatus of claim 16, wherein in a pixel, the first and second actuators of the modulator force a shutter relative to an aperture.

18. The direct-view display apparatus of claim 17, wherein the aperture is formed in a layer of material on the substrate.

19. The direct-view display apparatus of claim 17, wherein the aperture is formed in a layer of material deposited on a substrate that is different from the substrate on which the array is formed.

20. The direct-view display apparatus of claim 2, comprising a voltage regulator for substantially limiting variation in a voltage applied across the first and second actuators during actuation that would otherwise be caused by movement of portions of the first and second actuators.

21. The direct-view display apparatus of claim 20, wherein the voltage regulator comprises a capacitor in a pixel in electrical communication with the one of the first and second opposing actuators.

22. The direct-view display apparatus of claim 20, wherein the voltage regulator comprises a display driver, including a DC voltage source, directly electrically connected to at least one of the first and second opposing actuators via an actuation voltage interconnect.

23. The direct-view display apparatus of claim 20, comprises a display driver, including a DC voltage source, electrically connected to at least one of the first and second opposing actuators via an actuation voltage interconnect, wherein the application of the voltage output from the direct-view display driver to the pixel is controlled by a switch at the pixel other than the data switch.

24. The direct-view display apparatus of claim 20, wherein the voltage variation is substantially limited if, during actuation, movement of portions of the opposing actuators results in a voltage reduction of less than twenty percent of a voltage level required to initiate actuation.

25. The direct-view display apparatus of claim 20, wherein the voltage variation is substantially limited if, during actuation, movement of portions of the opposing actuators results in a voltage reduction of less than ten percent of a voltage level required to initiate actuation.

26. The direct-view display apparatus of claim 20, wherein the voltage variation is substantially limited if, during actuation, movement of portions of the opposing actuators results in a voltage reduction of less than five percent of a voltage level required to initiate actuation.

27. The direct-view display apparatus of claim 2, wherein the light modulator comprises a light tap that selectively and locally frustrates total internal reflection of a light guide, thereby extracting light to form an image.

28. The direct-view display of claim 1, comprising a global actuation interconnect electrically connected to pixels in at least two rows and two columns of the control matrix for causing substantially simultaneous actuation of the pixels to which it is connected.

29. The direct-view display apparatus of claim 1, comprising a first voltage actuation interconnect, distinct from the data voltage interconnect, in electrical communication with the first actuator, for providing a voltage sufficient to actuate the first actuator.

30. The direct-view display apparatus of claim 29, comprising, for a pixel, a switch, other than the data switch, for regulating the application of the voltage provided via the first actuation voltage interconnect.

31. The direct-view display apparatus of claim 29, wherein the data switch comprises a discharge transistor for selectively discharging the voltage provided via the first voltage actuation interconnect.

32. The direct-view display apparatus of claim 29, comprising a common voltage interconnect coupled to the light modulators of a plurality of pixels for applying a common bias voltage to the light modulators.

33. The direct-view display apparatus of claim 29, comprising a second voltage actuation interconnect, distinct from the data voltage interconnect and the first voltage actuation interconnect, for providing a voltage sufficient to actuate the second actuator.

34. The direct-view display apparatus of claim 33, wherein the data switch controls the application of the voltage provided via the second actuation voltage interconnect.

35. The direct-view display apparatus of claim 33, wherein the second voltage actuation interconnect directly connects a display driver to the second actuator.

36. The direct-view display apparatus of claim 33, wherein the voltage provided by the second actuation voltage interconnect is insufficient to actuate the second actuator if a voltage greater than a maintenance voltage is applied to the first actuator.

37. The direct-view display apparatus of claim 1, comprising a global actuation interconnect coupled to discharge transistors included in a plurality of pixels for selectively enabling the voltage provided to the respective pixels via the data voltage interconnects corresponding to the pixels to control the discharge transistors.

38. The direct-view display apparatus of claim 1, comprising a voltage actuation interconnect electrically connected directly to one of the first and second actuators of pixels in multiple rows and multiple columns of the array of pixels.

39. A direct view display apparatus comprising:

a transparent substrate;

an array of pixels formed on the substrate including, for each pixel, a MEMS-based light modulator including a light modulator comprising a first electrostatic actuator for changing the state of the light modulator; and

a control matrix connected to the substrate including, for a pixel, a write-enabling interconnect for enabling the pixel to respond to a data voltage and a data voltage interconnect for applying the data voltage to a data switch, thereby controlling the state of the light modulator of the pixel;

and a voltage regulator for substantially limiting variation in a voltage applied across the actuator during actuation that would otherwise be caused by movement of portions of the actuator.

40. The direct-view display apparatus of claim 39, wherein the voltage regulator comprises a display driver including a DC voltage source.

41. The direct-view display apparatus of claim 40, comprising for a pixel, an actuation voltage interconnect, distinct from the data voltage interconnect, for connecting the first actuator to the direct-view display driver.

42. The direct-view display apparatus of claim 41, comprising, for a pixel, a switch, other than the data switch, for controlling the application of the voltage output by the direct-view display driver to the first actuator.

43. The direct-view display apparatus of claim 39, wherein each pixel includes a voltage regulator.

44. The direct-view display apparatus of claim 43, wherein the voltage regulator comprises a capacitor in electrical communication with the first electrostatic actuator.

45. The direct-view display apparatus of claim 39, wherein the voltage variation is substantially limited if, during actuation, movement of portions of the first actuator results in a voltage reduction of less than twenty percent of a voltage level required to initiate actuation.

46. The direct-view display apparatus of claim 39, wherein the voltage variation is substantially limited if, during actuation, movement of portions of the first actuator results in a voltage reduction of less than ten percent of a voltage level required to initiate actuation.

47. The direct-view display apparatus of claim 39, wherein the voltage variation is substantially limited if, during actuation, movement of portions of the first actuator results in a voltage reduction of less than five percent of a voltage level required to initiate actuation.

48. The direct-view display apparatus of claim 39, comprising a voltage inverter.

49. The direct-view display apparatus of claim 48, wherein the voltage inverter comprises a CMOS circuit.

50. The direct-view display apparatus of claim 39, wherein each light modulator comprises a second electrostatic actuator for applying a force opposing a force applied by the first actuator.

51. The direct-view display apparatus of claim 50, comprising, for a pixel, a flip-flop electrically coupling the first actuator and the second electrostatic actuator.

52. The direct-view display apparatus of claim 50, comprising, for a pixel, a cross-coupled inverter electrically coupling the first actuator and the second electrostatic actuator

53. The direct-view display apparatus of claim 39, wherein the MEMS-based light modulators comprise shutter-based light modulators.

54. The direct-view display apparatus of claim 39, comprising a second electrostatic actuator, opposing the first actuator, for controlling the state of the MEMS-based light modulators.

55. The direct-view display apparatus of claim 54, comprising, for a pixel, a first actuation voltage interconnect for providing a voltage to the first actuator sufficient to actuate the first actuator.

56. The direct-view display apparatus of claim 55, wherein the first actuation voltage interconnect provides a substantially constant voltage throughout the setting of an image and through the setting of subsequent images.

57. The direct-view display apparatus of claim 55, wherein, throughout operation of the direct-view display, the first actuation voltage interconnect provides a substantially constant voltage.

58. The direct-view display apparatus of claim 55, wherein first actuation voltage interconnect for a pixel is shared by a plurality of pixels.

59. The direct-view display apparatus of claim 55, comprising, for a pixel, a second voltage actuation interconnect, distinct from the data voltage interconnect and the first voltage actuation interconnect, for providing a voltage sufficient to actuate the second actuator.

60. The direct-view display apparatus of claim 59, wherein the voltage provided by the second actuation voltage interconnect is insufficient to actuate the second actuator if a voltage greater than a maintenance voltage is applied to the first actuator.

61. The direct-view display apparatus of claim 59, comprising, for a pixel, a switch, other than the data switch, for regulating the application of the voltage provided via the first actuation voltage interconnect.

62. The direct-view display apparatus of claim 59, wherein the data voltage interconnect for the pixel controls the actuation of both the first and second actuators.

63. The direct-view display apparatus of claim 59, comprising a common voltage interconnect coupled to the light modulators of a plurality of pixels for applying a common bias voltage to the light modulators.

64. The direct-view display apparatus of claim 59, wherein the data switch comprises a discharge transistor for selectively discharging the voltage provided via the first voltage actuation interconnect.

65. The direct-view display apparatus of claim 64, comprising a global actuation interconnect coupled to the discharge transistors of a plurality of pixels for selectively enabling the voltage provided to the respective pixels via the data voltage interconnects corresponding to the pixels to control the discharge transistor.

66. The direct-view display apparatus of claim 39, comprising a voltage actuation interconnect electrically connected directly to the first electrostatic actuators of pixels in multiple rows and multiple columns of the array of pixels.

69. The direct-view display apparatus of claim 65, wherein the CMOS circuit comprises a level shifting inverter8

67. A display apparatus comprising:

a transparent substrate;

an array of pixels including for each pixel, a MEMS-based light modulator formed on the glass substrate;

a control matrix formed on the glass substrate for addressing the MEMS-based light modulators of the array, wherein for each pixel, the control matrix includes a CMOS circuit.

68. The direct-view display apparatus of claim 67, wherein the CMOS circuit comprises a voltage inverter.

70. The direct-view display apparatus of claim 67, wherein the CMOS circuit comprises a flip-flop.

71. The direct-view display apparatus of claim 70, wherein the flip-flop controls the application of an actuation voltage to the light modulator.

72. The direct-view display apparatus of claim 70, wherein the flip-flop electrically couples opposing actuators of the light modulator.

73. The direct-view display apparatus of claim 67, wherein the MEMS-based light modulator comprises a shutter-based light modulator.

74. The direct-view display apparatus of claim 67, wherein the MEMS-based light modulator comprises a light tap-based light modulator.

75. The direct-view display apparatus of claim 67, wherein the MEMS-based light modulator comprises an electrowetting-based light modulator.

76. A direct-view display apparatus comprising:

a transparent substrate,

an array of pixels organized into rows and columns, wherein the rows are divided into at least two sets of rows, each respective row in a set of rows being associated with a corresponding row in the other sets of rows, collectively forming groups of rows, the array including for each pixel, light modulator formed on the substrate and including a first actuator for controlling the state of the light modulator; and

a control matrix connected to the substrate including;

for each group of associated rows, an electrical connection shared among the pixels of the associated rows, thereby enabling the group of associated rows to be actuated to an addressed state at substantially the same time.

77. The direct-view display apparatus of claim 76, wherein the control matrix comprises, for each column, a single write enable switch and single data store capacitor per set of rows.

78. The direct-view display of claim 76, wherein the electrical connections shared among the pixels of a particular group of associated rows enables the particular group of associated rows to be actuated at a different times than another group of associated rows.

79. The direct-view display apparatus of claim 76, comprising, for each group of associated rows, a second, distinct, electrical connection shared among the pixels of the associated rows for providing an actuation voltage to the light modulators in the pixels to reset the pixels to an initial state.

80. The direct-view display apparatus of claim 76, comprising a charge interconnect electrically connected to pixels in multiple columns and multiple sets of rows for providing an actuation voltage to the actuators in the pixels to drive the light modulators in the pixels into an addressed state.

81. The direct-view display apparatus of claim 76, wherein the light modulator comprises a MEMS-based light modulator.

82. The direct-view display apparatus of claim 81, wherein the MEMS-based light modulator comprises a shutter-based light modulator.

83. The direct-view display apparatus of claim 81, wherein the MEMS-based light modulator comprises a light tap-based light modulator.

84. The direct-view display apparatus of claim 81, wherein the MEMS-based light modulator comprises an electrowetting-based light modulator.