Selective update of micro-electromechanical device

• US 20040218334A1
• Filed: 04/30/2003
• Published: 11/04/2004
• Est. Priority Date: 04/30/2003
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Van Brocklin, Andrew L., Ghozeil, Adam L., Martin, Eric T.
• Granted Patent: US 7,358,966 B2
• Time in Patent Office: Days
• US Class Current: 361/139
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• 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

Abstract

The present invention provides a data controller for controlling an electrostatically-controlled micro-electromechanical system (MEMS) device having a variable operating characteristic based on control data. The data controller comprises a data comparator and an update circuit. The data comparator is configured to receive control data of a present update cycle, to compare the control data of the present update cycle to control data of a previous update cycle on which the variable operating characteristic of the MEMS device is presently based, and to provide an update signal having a first state when the control data of the present update cycle is substantially equal to the control data of the previous update cycle. The update circuit is configured to receive the control data of the present update cycle, to receive the update signal, and to provide the control data of the present update cycle to the MEMS device, wherein the update circuit does not provide the control data of the present update cycle to the MEMS device when the update signal is in the first state.

Claims

1. A data controller for controlling an electrostatically-controlled micro-electromechanical system (MEMS) device having a variable operating characteristic based on control data, the data controller comprising:

a data comparator configured to receive control data of a present update cycle, to compare the control data of the present update cycle to control data of a previous update cycle on which the variable operating characteristic of the MEMS device is presently based, and to provide an update signal having a first state when the control data of the present update cycle is substantially equal to the control data of the previous update cycle; and

an update circuit configured to receive the control data of the present update cycle, to receive the update signal, and to provide the control data of the present update cycle to the MEMS device, wherein the update circuit does not provide the control data of the present update cycle to the MEMS device when the update signal is in the first state.

2. The data controller of claim 1, wherein the data comparator further comprises:

a memory for storing the control data of the previous update cycle on which the presently stored charge of the MEMS device is based.

3. The data controller of claim 2, wherein the control data of the previous update cycle stored in the memory is replaced with the control data of the present update cycle when the control data of the present update cycle is not substantially equal to the control data of the previous update cycle.

4. The data controller of claim 1, wherein the data comparator is configured to provide an update signal having the first state when the control data of the present update cycle is within a range of the control data of the previous update cycle.

5. The data controller of claim 1, wherein the update circuit is further configured to receive a an enable signal having a first state indicative of when the control data of the present update cycle is to be provided to the MEMS device and a second state indicative of when the control data of the present update cycle is not to be provided to the MEMS device, wherein the update circuit does not provide the control data of the present cycle to the MEMS device when the enable signal has the second state.

6. The data controller of claim 5, wherein the update circuit comprises:

a first switch configured to receive the control data and the enable signal, and to provide the control data, wherein the first switch does not provide the control data when the enable signal has the second state; and

a second switch configured to receive the control data from the first switch and the update signal, and to provide the control data to the MEMS device, wherein the second switch does not provide the control data to the MEMS device when the update signal has the first state.

7. The data controller of claim 6, wherein the first switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the enable signal, a drain configured to receive the control data, and a source configured to provide the control data.

8. The data controller of claim 6, wherein the second switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the update signal, a drain configured to receive the control data from the first switch, and a source configured to provide the control data to the MEMS device.

9. A micro-electromechanical system comprising:

an electrostatically-controlled micro-electromechanical system (M EMS) device having a variable operating characteristic based on control data; and

a data controller comprising;

a data comparator configured to receive control data of a present update cycle, to compare the control data of the present update cycle to control data of a previous update cycle on which the variable operating characteristic of the MEMS device is presently based, and to provide an update signal having a first state when the control data of the present update cycle is substantially equal to the control data of the previous update cycle; and

an update circuit configured to receive the control data of the present update cycle, to receive the update signal, and to provide the control data of the present update cycle to the MEMS device, wherein the update circuit does not provide the control data of the present update cycle to the MEMS device when the update signal is in the first state.

10. The micro-electromechanical system of claim 9, wherein the data comparator further comprises:

a memory for storing the control data of the previous update cycle on which the variable operating characteristic of the MEMS device is presently based.

11. The micro-electromechanical system of claim 10, wherein the control data of the previous update cycle stored in the memory is replaced with the control data of the present update cycle when the control data of the present update cycle is not substantially equal to the control data of the previous update cycle.

12. The micro-electromechanical system of claim 9, wherein the data comparator is configured to provide an update signal having the first state when the control data of the present update cycle is within a range of the control data of the previous update cycle.

13. The micro-electromechanical system of claim 9, wherein the update circuit is further configured to receive a an enable signal having a first state indicative of when the control data of the present update cycle is to be provided to the MEMS device and a second state indicative of when the control data of the present update cycle is not to be provided to the MEMS device, wherein the update circuit does not provide the control data of the present cycle to the MEMS device when the enable signal has the second state.

14. The micro-electromechanical system of claim 13, wherein the update circuit comprises:

a first switch configured to receive the control data and the enable signal, and to provide the control data, wherein the first switch does not provide the control data when the enable signal has the second state; and

a second switch configured to receive the control data from the first switch and the update signal, wherein the second switch does not provide the control data to the MEMS device when the update signal has the first state.

15. The micro-electromechanical system of claim 14, wherein the first switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the enable signal, a drain configured to receive the control data, and a source configured to provide the control data.

16. The micro-electromechanical system of claim 14, wherein the second switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the update signal, a drain configured to receive the control data from the first switch, and a source configured to provide the control data to the MEMS device.

17. The micro-electromechanical system of claim 9, wherein the update circuit and the MEMS device together form a micro-electromechanical cell.

18. The micro-electromechanical system of claim 9, wherein the MEMS device comprises:

a charge-controlled MEMS device configured to modulate light to display, at least partially, a pixel of a displayable image.

19. The micro-electromechanical system of claim 18, wherein the variable operating characteristic comprises:

a stored charge on a variable capacitor.

20. The micro-electromechanical system of claim 18, wherein the control data comprises:

frame data representative of the displayable image.

21. The micro-electromechanical system of claim 18, wherein the MEMS device and update circuit together form a light modulating cell.

22. A light modulating system comprising:

a charge-controlled micro-electromechanical system (MEMS) device configured to modulate light based on a stored charge on a variable capacitor to display, at least partially, a pixel of a displayable image, wherein the stored charge is based on frame data representative of the displayable image; and

a data controller comprising;

a data comparator configured to receive frame data of a present frame, to compare the frame data of the present frame to frame data of a previous frame on which a presently stored charge of the MEMS device is based, and to provide an update signal having a first state when the frame data of the present frame is substantially equal to the frame data of the previous frame; and

an update circuit configured to receive the frame data of the present frame, to receive the update signal, and to provide the frame data of the present frame to the MEMS device, wherein the update circuit does not provide the frame data of the present frame to the MEMS device when the update signal is in the first state.

23. The light modulating system of claim 22, wherein the data comparator further comprises:

a memory for storing the frame data of the previous update cycle on which the presently stored charge of the MEMS device is based.

24. The light modulating system of claim 23, wherein the frame data of the previous update cycle stored in the memory is replaced with the frame data of the present frame when the control data of the present frame is not substantially equal to the frame data of the previous frame.

25. The light modulating system of claim 22, wherein the data comparator is configured to provide an update signal having the first state when the frame data of the present frame is within a range of the frame data of the previous frame.

26. The light modulating system of claim 22, wherein the update circuit is further configured to receive a an enable signal having a first state indicative of when the frame data of the present frame is to be provided to the MEMS device and a second state indicative of when the frame data of the present frame is not to be provided to the MEMS device, wherein the update circuit does not provide the frame data of the present frame to the MEMS device when the enable signal has the second state.

27. The light modulating system of claim 26, wherein the update circuit comprises:

a first switch configured to receive the frame data of the present frame and the enable signal, and to provide the frame data of the present frame, wherein the first switch does not provide the frame data of the present frame when the enable signal has the second state; and

a second switch configured to receive the frame data of the present frame from the first switch, to receive the update signal, and to provide the frame data of the present frame to the MEMS device, wherein the second switch does not provide the frame data of the present frame to the MEMS device when the update signal has the first state.

28. The light modulating system of claim 27, wherein the first switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the enable signal, a drain configured to receive the frame data of the present frame, and a source configured to provide the frame data of the present frame.

29. The light modulating system of claim 27, wherein the second switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the update signal, a drain configured to receive the frame data of the present frame from the first switch, and a source configured to provide the frame data of the present frame to the MEMS device.

30. The light modulating system of claim 22, wherein in the update circuit and the MEMS device together form a light modulating cell.

31. A micro-electromechanical system comprising:

an M-row by N-column array of micro-electromechanical cells configured to perform a task, each cell comprising;

an electrostatically-controlled micro-electromechanical system (MEMS) device having a variable operating characteristic based on control data; and

an update circuit configured to receive control data of a present update cycle, to receive an update signal, and to provide the control data of the present update cycle to the MEMS device, wherein the update circuit does not provide the control data of the present update cycle to the MEMS device when the update signal has a first state; and

a data comparator configured to compare for each cell of the array the control data of the present update cycle to frame data of a previous update cycle on which the variable operating characteristic of the cell is presently based, and to provide to each cell of the array the update signal having a first state when the control data of the present update cycle is substantially equal to the control data of the previous update cycle on which the variable operating characteristic is presently based.

32. The micro-electromechanical system of claim 31, wherein the data comparator further comprises:

a memory for storing for each micro-electromechanical cell of the array the control data of the previous update cycle on which the variable operating characteristic of the MEMS device is presently based.

33. The micro-electromechanical system of claim 32, wherein for each micro-electromechanical cell the control data of the previous update cycle stored in the memory is replaced with the control data of the present update cycle when the control data of the present update cycle is not substantially equal to the control data of the previous update cycle.

34. The micro-electromechanical system of claim 31, wherein the data comparator is configured to provide an update signal having the first state when the control data of the present update cycle is within a range of the control data of the previous update cycle on which the variable operating characteristic of the MEMS device is presently based.

35. The micro-electromechanical system of claim 31, wherein the update circuit is further configured to receive a an enable signal having a first state indicative of when the control data of the present update cycle is to be provided to the MEMS device and a second state indicative of when the control data of the present update cycle is not to be provided to the MEMS device, wherein the update circuit does not provide the control data of the present update cycle to the MEMS device when the enable signal has the second state.

36. The micro-electromechanical system of claim 35, wherein the update circuit comprises:

a first switch configured to receive the control data of the present update cycle and the enable signal, and to provide the control data, wherein the first switch does not provide the control data when the enable signal has the second state; and

a second switch configured to receive the control data from the first switch and the update signal, and to provide the control data to the MEMS device, wherein the second switch does not provide the control data to the MEMS device when the update signal has the first state.

37. The micro-electromechanical system of claim 36, wherein the first switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the enable signal, a drain configured to receive the control data, and a source configured to provide the control data.

38. The micro-electromechanical system of claim 36, wherein the second switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the update signal, a drain configured to receive the control data from the first switch, and a source configured to provide the control data to the MEMS device.

39. A light modulating system for displaying an image, the system comprising:

an M-row by N-column array of light modulating cells, each cell comprising;

a charge-controlled micro-electromechanical system (MEMS) device configured to modulate light based on a stored charge to display, at least partially, a pixel of the image, wherein the stored charge is based on frame data representative of the image; and

an update circuit configured to receive frame data of a present frame, to receive an update signal, and to provide the frame data of the present frame to the MEMS device, wherein the update circuit does not provide the frame data of the present frame to the MEMS device when the update signal has a first state; and

a data comparator configured to compare for each cell of the array the frame data of the present frame data to frame data of a previous frame on which a presently stored charge of the cell is based, and to provide to each cell of the array the update signal having a first state when the frame data of the present frame is substantially equal to the frame data of the previous frame on which the presently stored charge is based.

40. The light modulating system of claim 39, wherein the data comparator further comprises:

a memory for storing for each light modulating cell of the array the frame data of the previous frame on which the presently stored charge of the MEMS device is based.

41. The light modulating system of claim 40, wherein for each light modulating cell the frame data of the previous frame stored in the memory is replaced with the frame data of the present frame when the frame data of the present frame is not substantially equal to the frame data of the previous update cycle.

42. The light modulating system of claim 39, wherein the data comparator is configured to provide an update signal having the first state when the frame data of the present frame is within a range of the frame data of the previous frame on which the presently stored charge of the MEMS device is based.

43. The light modulating system of claim 39, wherein the update circuit is further configured to receive a an enable signal having a first state indicative of when the frame data of the present frame is to be provided to the MEMS device and a second state indicative of when the frame data of the present frame is not to be provided to the MEMS device, wherein the update circuit does not provide the frame data of the present frame to the MEMS device when the enable signal has the second state.

44. The light modulating system of claim 43, wherein the update circuit comprises:

a first switch configured to receive the frame data of the present frame and the enable signal, and to provide the frame data, wherein the first switch does not provide the frame data when the enable signal has the second state; and

a second switch configured to receive the frame data from the first switch and the update signal, and to provide the frame data to the MEMS device, wherein the second switch does not provide the frame data to the MEMS device when the update signal has the first state.

45. The light modulating system of claim 44, wherein the first switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the enable signal, a drain configured to receive the frame data, and a source configured to provide the frame data.

46. The light modulating system of claim 44, wherein the second switch comprises:

a p-channel metal-oxide semiconductor (PMOS) device having a gate configured to receive the update signal, a drain configured to receive the frame data from the first switch, and a source configured to provide the frame data to the MEMS device.

47. A method of updating control data for an electrostatically-controlled micro-electromechanical system (MEMS) device having a variable operating characteristic based on the control data, the method comprising:

receiving control data of a present update cycle;

comparing the control data of a present update cycle to control data of a previous update cycle on which the variable operating characteristic of the MEMS device is presently based; and

updating the MEMS device with the control data of the present update cycle only when the control data of the present update cycle is not substantially equal to the control data of the previous update cycle on which the variable operating characteristic of the MEMS device is presently based such that the variable operating characteristic of the MEMS device is modified to reflect the control data of the present update cycle.

48. The method of claim 47, further comprising:

storing in a memory the control data of the previous update cycle on which the variable operating characteristic of the MEMS device is presently based.

49. The method of claim 48, further comprising:

replacing the control data of the previous update cycle stored in the memory with the control data of the present update cycle when the control data of the present update cycle is not substantially equal to the control data of the previous update cycle stored in the memory.

50. The method of claim 47, further comprising:

receiving an enable signal indicative of when the control data of the present update cycle is to be provided to the MEMS device; and

updating the MEMS device with the control data of the present update cycle only when the enable signal indicates that the MEMS device is to be updated with the control data of the present update cycle and when the control data of the present update cycle is not substantially equal to the control data of the previous update cycle on which the variable operating characteristic of the MEMS device is presently based.

51. A data controller for controlling an electrostatically-controlled micro-electromechanical system (MEMS) device having a variable operating characteristic based on control data, the data controller comprising:

means for receiving and comparing control data of a present update cycle to control data of a previous update cycle on which the variable operating characteristic is presently based and for providing an update signal having a first state when the control data of the present update cycle is substantially equal to the control data of the previous cycle on which the variable operating characteristic is presently based; and

means for receiving the update signal and for providing the control data of the present update cycle to the MEMS device, wherein the control data of the present update cycle is not provided to the MEMS device with the update signal has the first state.

52. The data controller of claim 51, further comprising:

means for storing the control data of the previous update cycle on which the variable operating characteristic of the MEMS device is presently based.

53. The data controller of claim 52, further comprising:

means for replacing the stored control data of the previous update cycle with the control data of the present update cycle when the control data of the present update cycle is not substantially equal to the control data of the previous update cycle stored in the memory.