Current mode display driver circuit realization feature

• US 20060056000A1
• Filed: 07/15/2005
• Published: 03/16/2006
• 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 7,499,208 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 device for modulating light, comprising:

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

control circuitry connected to said light modulator for controlling said interferometric modulator, wherein the control circuitry provides a substantially constant current to said light modulator to control said movable optical element.

2. The device of claim 1, wherein said control circuitry is controllably switchable between a first configuration of the control circuitry that provides no current to said at least one light modulator and a second configuration that provides current to the at least one light modulator, and wherein said control circuitry is configured to provide a current to said movable optical element when switched between the first configuration and the second configuration.

3. The device according to claim 2, wherein

the first circuit configuration comprises a plurality of electrical devices connected electrically in a parallel configuration with each other, each of the electrical devices capable of storing an electric charge;

and

the second configuration comprises the plurality of electrical devices configured such that they are connected electrically in a series configuration with each other, and such that the series configuration is connected to said at least one light modulator.

4. The device of claim 3, wherein the plurality of electrical devices comprise capacitors.

5. The device according to claim 3, wherein said plurality of electrical devices comprises three or more capacitors.

6. The device according to claim 4, wherein said plurality of electrical devices comprises ten or more capacitors.

7. The device according to claim 3, wherein said control circuitry is configured to switch between the first configuration and the second configuration by connecting electrically each of the plurality of electrical devices in a series configuration with said light modulator over a predetermined time period.

8. The device of claim 7, wherein the plurality of electrical devices comprise capacitors.

9. The device according to claim 3, wherein said control circuitry is further configured to switch between the second configuration and the first configuration by connecting electrically each of the plurality of electrical devices to an electrically parallel configuration with each other over a predetermined time period.

10. The device of claim 9, wherein the plurality of electrical devices comprise capacitors.

11. 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.

12. The method of claim 11, further comprising receiving a signal in a driving circuit indicating to actuate an interferometric modulator pixel.

13. The method of claim 11, 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.

14. The method of claim 11, 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.

15. 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 it provides a voltage across the pixel.

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

17. 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 switching step 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.

18. The method of claim 17, 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 step 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.

19. The method of claim 17, wherein the plurality of charge storing devices comprises one or more capacitors.

20. A device for modulating light, comprising:

means for at least one light modulator comprising a movable optical element positionable in two or more positions, said modulator operating interferometrically to exhibit a different predetermined optical response in each of the two or more positions; and

means for control circuitry connected to said light modulator for controlling said interferometric modulator, wherein the control circuitry provides a substantially constant current to said light modulator to control said movable optical element.

21. A device for modulating light, comprising:

a display comprising at least one light modulator comprising a movable optical element positionable in two or more positions, said modulator operating interferometrically to exhibit a different predetermined optical response in each of the two or more positions;

control circuitry connected to said display for controlling said interferometric modulator, wherein the control circuitry provides a substantially constant current to said light modulator to control said movable optical element;

a processor that is in electrical communication with said display, said processor being configured to process image data; and

a memory device in electrical communication with said processor.

22. The device of claim 21, further comprising a controller configured to send at least a portion of said image data to said driver circuit.

23. The device of claim 22, further comprising:

an image source module configured to send said image data to said processor.

24. The apparatus of claim 23, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

25. The apparatus of claim 24, further comprising:

an input device configured to receive input data and to communicate said input data to said processor.