Circuits for controlling MEMS display apparatus on a transparent substrate

• US 8,482,496 B2
• Filed: 06/12/2007
• Issued: 07/09/2013
• Est. Priority Date: 01/06/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Lewis, Stephen R.
• Primary Examiner(s): CERULLO, LILIANA P
• Application Number:
  US11/811,842
• Publication Number:
  US 20080174532A1
• Time in Patent Office: 2,219 Days
• Field of Search: 345 84- 98, 345108-110, 345204-206, 345208-210, 345214-215, 359237-324
• US Class Current: 345/84
• CPC Class Codes: G09G 2300/0473 Use of light emitting or modulating elements having two or more stable states when no power is applied
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0857 Static memory circuit, e.g. flip-flop
• CPC Class Codes: G09G 2310/02 Addressing, scanning or driving the display screen or processing steps related thereto
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• 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 3/3466 based on interferometric effect

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 display apparatus comprising:

a transparent substrate,

an array of pixels including a plurality of MEMS light modulators wherein each pixel includes at least one MEMS light modulator, and

a control matrix including,

a plurality of scan line interconnects running in a first direction, each enabling a plurality of pixels along the first direction to respond to data voltages; and

a plurality of data interconnects running in a second direction perpendicular to the first direction, each providing data voltages to a plurality of pixels along the second direction; and

for each pixel in the array;

a set of switches comprising a first switch and a second switch directly connected in series, wherein the first switch and second switch are formed on the transparent substrate, and wherein the first switch and second switch together connect an energy source to at least one MEMS light modulator of the respective pixel,

a data switch coupled to a corresponding one of the scan line interconnects and a corresponding one of the data interconnects for controlling the state of the at least one MEMS light modulator of the respective pixel.

2. The display apparatus of claim 1, wherein the first switch comprises a first transistor and the second switch comprises a second transistor.

3. The display apparatus of claim 2, wherein the first and second transistors share a common gate voltage.

4. The display apparatus of claim 2, wherein a gate of the first transistor is substantially at a first voltage, a gate of the second transistor is substantially at a second voltage, and the first and second voltages are different for at least one moment in time.

5. The display apparatus of claim 4, wherein the second voltage is substantially equal to half of the first voltage while the first and second transistors are each in an off state.

6. The display apparatus of claim 4, comprising an interconnect for supplying the second voltage to the gate of the second transistor.

7. The display apparatus of claim 4, wherein the energy source is connected to an actuation voltage interconnect for supplying an actuation voltage to the at least one MEMS light modulator of the respective pixel.

8. The display apparatus of claim 7, wherein the second voltage is substantially equal to half of the actuation voltage while the first and second transistors are each in an off state.

9. The display apparatus of claim 7, wherein the actuation voltage interconnect is a global common interconnect for supplying the actuation voltage to multiple pixels in the array.

10. The display apparatus of claim 1, wherein the respective pixel comprises a first actuator for driving the at least one MEMS light modulator of the respective pixel into a first state.

11. The display apparatus of claim 10, comprising a second actuator, different from the first actuator, for driving the at least one MEMS light modulator of the respective pixel into a second state.

12. The display apparatus of claim 11, comprising an actuation voltage interconnect for supplying an actuation voltage to the second actuator.

13. The display apparatus of claim 11, wherein the second actuator is connected to the energy source via at least one switch.

41. The display apparatus of claim 1, wherein the energy source provides a voltage of at least 40 Volts.

42. The display apparatus of claim 41, wherein the voltage across each of the first and second switches is less than 40 Volts.

14. A display apparatus comprising:

a transparent substrate,

an array of pixels including a plurality of MEMS light modulators wherein each pixel includes at least one MEMS light modulator, and

a control matrix including,

a plurality of scan line interconnects running in a first direction, each enabling a plurality of pixels along the first direction to respond to data voltages; and

a plurality of data interconnects running in a second direction perpendicular to the first direction, each providing data voltages to a plurality of pixels along the second direction; and

for each pixel in the array;

a first switch and a second switch directly connected in series and through which current flows from at least one MEMS light modulator of the respective pixel to a current drain interconnect, wherein the first switch and second switch are formed on the transparent substrate,

a data switch coupled to a corresponding one of the scan line interconnects and a corresponding one of the data interconnects for controlling the state of the at least one MEMS light modulator of the respective pixel.

15. The display apparatus of claim 14, wherein the first switch comprises a first transistor and the second switch comprises a second transistor.

16. The display apparatus of claim 15, wherein the first and second transistors share a common gate voltage.

17. The display apparatus of claim 15, wherein a gate of the first transistor is substantially at a first voltage, a gate of the second transistor is substantially at a second voltage, and the first and second voltages are different for at least one moment in time.

18. The display apparatus of claim 17, wherein the first voltage is substantially equal to half of an actuation voltage supplied to the at least one MEMS light modulator of the respective pixel while the first and second transistors are each in an off state.

19. The display apparatus of claim 17, wherein the data interconnect supplies a data voltage to the gate of the second transistor.

20. The display apparatus of claim 17, comprising a cascode interconnect for supplying the first voltage to the gate of the first transistor.

21. The display apparatus of claim 14, wherein the respective pixel comprises a first actuator for driving the at least one MEMS light modulator of the respective pixel into a first state and the control matrix comprises a first actuation voltage interconnect for supplying a first actuation voltage to the first actuator.

22. The display apparatus of claim 21, wherein the first actuation voltage interconnect is a global common interconnect for supplying the actuation voltage to multiple pixels in the array.

23. The display apparatus of claim 21, comprising a second actuator for driving the at least one MEMS light modulator of the respective pixel into a second state.

24. The display apparatus of claim 23, comprising a second actuation voltage interconnect for supplying a second actuation voltage to the second actuator.

25. The display apparatus of claim 23, wherein the second actuator is connected to the first actuation voltage interconnect via at least one switch.

26. A display apparatus, comprising:

a transparent substrate,

an array of pixels including a plurality of light modulators wherein each pixel includes at least one light modulator, and

a control matrix including,

a plurality of scan line interconnects running in a first direction, each enabling a plurality of pixels along the first direction to respond to data voltages; and

a plurality of data interconnects running in a second direction perpendicular to the first direction, each providing data voltages to a plurality of pixels along the second direction; and

for each pixel in the array,

a charging cascode connecting an energy source to at least one light modulator of the respective pixel, wherein the charging cascode comprises a first switch and a second switch directly connected in series,

a discharging cascode through which current flows from the at least one light modulator of the respective pixel to a current drain interconnect, wherein the charging and discharging cascodes are connected to a common interconnect, and wherein the charging and discharging cascode are formed on the transparent substrate, and

a data switch coupled to a corresponding one of the scan line interconnects and a corresponding one of the data interconnects for controlling the state of the at least one light modulator of the respective pixel.

27. The display apparatus of claim 26, wherein the discharging cascode comprises a third switch and a fourth switch directly connected in series.

28. The display apparatus of claim 27, wherein

the first switch comprises a first transistor connecting the energy source and the second switch,

the second switch comprises a second transistor connecting the first switch and the at least one light modulator of the respective pixel,

the third switch comprises a third transistor connecting the at least one light modulator of the respective pixel and the fourth switch, and

the fourth switch comprises a fourth transistor connecting the third switch and the current drain interconnect.

29. The display apparatus of claim 28, wherein a gate of the second transistor and a gate of the third transistor are connected to the common interconnect.

30. The display apparatus of claim 28, wherein the first and second transistors are of a transistor type different from that of the third and fourth transistors.

31. The display apparatus of claim 30, wherein each of the first, second, third, and fourth transistors are all the same one of NMOS type or PMOS type.

32. The display apparatus of claim 26, wherein the control matrix comprises a CMOS control matrix.

33. The display apparatus of claim 26, wherein the energy source is connected to an actuation voltage interconnect for supplying an actuation voltage to the at least one light modulator of the respective pixel.

34. The display apparatus of claim 33, wherein the common interconnect is at a voltage that is substantially half of the actuation voltage.

35. The display apparatus of claim 33, wherein the actuation voltage interconnect is a global common interconnect for supplying the actuation voltage to multiple pixels in the array.

36. The display apparatus of claim 26, wherein the plurality of light modulators comprises a plurality of MEMS light modulators wherein each pixels includes at least one MEMS light modulator.

37. The display apparatus of claim 36, wherein the respective pixel comprises a first actuator for driving at least one MEMS light modulator of the respective pixel into a first state.

38. The display apparatus of claim 37, comprising a second actuator for driving the at least one MEMS light modulator of the respective pixel into a second state.

39. The display apparatus of claim 38, comprising a second actuation voltage interconnect for supplying a second actuation voltage to the second actuator.

40. The display apparatus of claim 38, wherein the second actuator is connected to the first actuation voltage interconnect via at least one switch.

43. The display apparatus of claim 28, wherein the energy source provides a voltage of at least 40 Volts.

44. The display apparatus of claim 43, wherein the voltage across each of the first, second, third, and fourth transistors is less than 40 Volts.