CURRENT MODE DISPLAY DRIVER CIRCUIT REALIZATION FEATURE

• US 20090161192A1
• Filed: 03/02/2009
• Published: 06/25/2009
• Est. Priority Date: 08/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Mignard, Marc
• Granted Patent: US 7,852,542 B2
• Time in Patent Office: Days
• US Class Current: 359/245
• CPC Class Codes: G09G 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2310/066 Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
• CPC Class Codes: G09G 2330/025 Reduction of instantaneous peaks of current
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

The invention comprises devices and methods for driving a MEMs pixel, and in particular, an interferometric modulator pixel. In one embodiment a device for modulating light includes a light modulator including a movable optical element positionable in two or more positions, the modulator operating interferometrically to exhibit a different predetermined optical response in each of the two or more positions, and control circuitry connected to the light modulator for controlling said interferometric modulator, where the control circuitry is controllably switchable between two circuit configurations, and where the control circuitry provides current to said light modulator when switching between the two circuit configurations to cause the movable optical element of the light modulator to move between two positions of its two or more positions. In another embodiment a method of driving an interferometric modulator pixel with a driving circuit includes providing a potential difference across the interferometric pixel, wherein the provided potential difference increases over a period of time, and changing the position of a movable reflective layer of the interferometric pixel based on the provided potential difference.

Claims

1. A method of driving an interferometric modulator pixel with a driving circuit, the method comprising:

providing a potential difference across the interferometric pixel, wherein the provided potential difference increases over a period of time; and

changing the position of a movable reflective layer of the interferometric pixel based on the provided potential difference;

wherein providing a potential difference across the interferometric pixel comprises incrementally increasing the potential difference across the interferometric pixel by a predetermined amount, wherein the potential difference is increased in two or more increments.

2. The method of claim 1, further comprising receiving a signal in a driving circuit indicating to actuate an interferometric modulator pixel.

3. The method of claim 1, wherein providing a potential difference across the interferometric pixel comprises incrementally increasing the potential difference across the interferometric pixel by a predetermined amount, wherein the potential difference is increased in five or more increments.

4. The method of claim 1, wherein providing a potential difference across the interferometric pixel comprises incrementally increasing the potential difference across the interferometric pixel by a predetermined amount, wherein the potential difference is increased in ten or more increments.

5. The method of claim 1, comprising providing a substantially constant current to said interferometric pixel during said providing a potential difference.

6. The method of claim 1, further comprising decreasing the potential difference across the interferometric pixel by a predetermined amount, wherein the potential difference is decreased in two or more increments.

7. A method of driving an interferometric modulator pixel with a substantially constant current source to produce different optical responses, the method comprising:

configuring a drive circuit in a first state so that a plurality of charge storing devices are charged by a voltage source and the plurality of charge storing devices do not provide a voltage across the interferometric modulator pixel; and

changing the configuration of the driving circuit to a second state in a series of incremental steps over a predetermined time, wherein each of the incremental steps comprises connecting one of the plurality of charge storing devices to the pixel such that the one charge storing device provides a voltage across the pixel.

8. The method of claim 7, wherein the plurality of charge storing devices comprises one or more capacitors.

9. The method of claim 7, further comprising changing the configuration of the driving circuit from the second state to the first state in a series of incremental steps over a predetermined time, wherein each of the incremental steps comprises removing one of the plurality of charge storing devices from connection to the pixel such that the removed charge storing device does not provide a voltage across the pixel.

10. The method of claim 7, comprising five or more of said incremental steps.

11. The method of claim 7, comprising ten or more of said incremental steps.

12. The method of claim 7, wherein said drive circuit provides no current to said pixel when configured in said first state.

13. The method of claim 7, wherein said drive circuit provides current to said pixel when changed from said first state to said second state.

14. The method of claim 7, further comprising receiving information representative of image data.

15. A method of driving an interferometric modulator pixel with a substantially constant current source to produce different optical responses, the method comprising:

providing a substantially constant current source to drive the interferometric modulator pixel, said providing comprising

connecting one of a plurality of charge storing devices in the driving circuit to provide a potential difference across the interferometric modulator pixel; and

repeating said connecting until all of the plurality of charge storing devices are connected in an electrical series connection with each other, and such that the plurality of charge storing devices provide a potential difference across the interferometric modulator pixel.

16. The method of claim 15, wherein providing a substantially constant current source to drive the interferometric modulator pixel further comprises:

configuring one of the plurality of charge storing devices in the driving circuit so that it does not provide a potential difference across the interferometric modulator pixel; and

repeating said configuring until all of the plurality of charge storing devices are configured so that they do not provide a potential difference across the interferometric modulator pixel.

17. The method of claim 15, wherein said connecting and said repeating are performed over a predetermined time period.

18. The method of claim 15, wherein the plurality of charge storing devices comprises one or more capacitors.

19. The method of claim 15, wherein connecting a charge storing device is performed five or more times.

20. The method of claim 15, wherein connecting a charge storing device is performed ten or more times.

21. A device for modulating light, comprising:

at least one light modulator comprising a movable optical element and operating interferometrically to exhibit a different optical response in each of two or more positions; and

control circuitry configured to provide a potential difference across the light modulator, the control circuitry being configured to incrementally increase the potential difference provided by a predetermined amount over a period of time,

wherein the optical element is configured to be movable at least partially in response to the provided potential difference.

22. The device of claim 21, wherein the control circuitry is configured to increase the potential difference across the light modulator in five or more increments.

23. The device of claim 21, wherein the control circuitry is configurable into at least two states, a first of said two states comprising a plurality of charge storing devices being configured to be charged by a voltage source and to not provide a voltage across the light modulator, a second of said two states comprising one or more of the plurality of charge storing devices being connected to the light modulator such that a voltage is provided across the light modulator.

24. The device of claim 23, wherein the plurality of charge storing devices comprises a plurality of capacitors.

25. A device for modulating light, comprising:

means for providing a potential difference across a light modulator;

means for incrementally increasing the potential difference provided across the light modulator by a predetermined amount over a period of time; and

means for changing the position of a movable reflective layer of the light modulator based on the provided potential difference.