Current mode display driver circuit realization feature

• US 7,852,542 B2
• Filed: 03/02/2009
• Issued: 12/14/2010
• Est. Priority Date: 08/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Mignard, Marc
• Primary Examiner(s): Mack; Ricky L
• Assistant Examiner(s): JONES, JAMES
• Application Number:
  US12/396,395
• Publication Number:
  US 20090161192A1
• Time in Patent Office: 652 Days
• Field of Search: 359/245
• 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, for example 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 to provide a potential difference across the modulator, where the control circuitry is configured to incrementally increase the potential difference provided by a predetermined amount over a period of time, and where the optical element of the light modulator is moveable at least partially in response to the provided potential difference.

Claims

1. 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.

2. The method of claim 1, wherein the plurality of charge storing devices comprises one or more capacitors.

3. The method of claim 1, 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.

4. The method of claim 1, comprising five or more of said incremental steps.

5. The method of claim 1, comprising ten or more of said incremental steps.

6. The method of claim 1, wherein said drive circuit provides no current to said pixel when configured in said first state.

7. The method of claim 1, wherein said drive circuit provides current to said pixel when changed from said first state to said second state.

8. The method of claim 1, further comprising receiving information representative of image data.

19. The method of claim 1, wherein the plurality of charge storing devices are arranged in a parallel configuration in the first state.

20. The method of claim 1, wherein the plurality of charge storing devices are arranged in a series configuration in the second state.

9. 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 utilizing a plurality of charge storing devices,

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

10. The device of claim 9, wherein the control circuitry is configured to increase the potential difference across the light modulator in five or more increments.

11. The device of claim 9, wherein the control circuitry is configurable into at least two states, a first of said two states comprising the 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.

12. The device of claim 11, wherein the plurality of charge storing devices comprises a plurality of capacitors.

13. The device of claim 11, wherein the plurality of charge storing devices are arranged in a parallel configuration in the first of said two states.

14. The device of claim 11, wherein the plurality of charge storing devices are arranged in a series configuration in the second of said two states.

15. The device of claim 9, wherein the control circuitry is configured to increase the potential difference across the light modulator in tenor more increments.

16. The device of claim 9, wherein one or more of the plurality of charge storing devices comprises a capacitor.

17. The device of claim 9, further comprising an interface configured to receive information representative of image data.

18. The device of claim 17, wherein the interface comprises a network interface having a receiver.