Systems, devices, and methods for driving an interferometric modulator

• US 8,847,862 B2
• Filed: 11/29/2011
• Issued: 09/30/2014
• Est. Priority Date: 11/29/2011
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Govil, Alok
• Primary Examiner(s): Nguyen, Kevin M
• Application Number:
  US13/306,133
• Publication Number:
  US 20130135326A1
• Time in Patent Office: 1,036 Days
• Field of Search: 345/85, 345/108, 359/245, 359/290
• US Class Current: 345/85
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• 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 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

This disclosure provides systems, methods, and apparatus for controlling the actuation of an analog interferometric modulator. In one aspect, a voltage may be determined from a sense electrode. A distance between one or more of the electrodes may be determined based on the voltage. The sense electrode may be capacitively coupled to another electrode, and may be implemented in a mirror of a movable layer of an interferometric modulator, or may be implemented in a floating fixed layer of an interferometric modulator.

Claims

1. A device for modulating light, comprising:

a first electrode coupled to a first voltage source;

a second electrode;

a movable electrode disposed between and spaced apart from the first electrode and the second electrode, the movable electrode including a third electrode and a fourth electrode, the third electrode and the fourth electrode being capacitively coupled, the third electrode and the fourth electrode being positioned in two different parallel planes separated by a gap;

a voltage sensor coupled to the third electrode; and

a second voltage source coupled to the fourth electrode, wherein the second electrode is coupled to a third voltage source.

2. The device of claim 1, wherein the voltage sensor provides feedback for the second voltage source.

3. The device of claim 1, wherein the movable electrode includes a mirror layer.

4. The device of claim 3, wherein the second electrode includes a partially reflective layer.

5. The device of claim 1, wherein the first voltage source includes a substantially fixed voltage source and the third voltage source is ground.

6. The device of claim 1, wherein the second voltage source includes a variable voltage source.

7. The device of claim 6, further including a drive circuit configured to adjust a position of the movable electrode by varying the voltage supplied by the second voltage source.

8. The device of claim 7, wherein the drive circuit is coupled to a first bus connected to one or more voltage sensors of other devices for modulating light.

9. A display system, comprising the device of claim 1, further comprising:

a display;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

10. The apparatus as recited in claim 9, further comprising:

a driver circuit configured to send at least one signal to the display; and

a controller configured to send at least a portion of the image data to the driver circuit.

11. The apparatus as recited in claim 9, further comprising:

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

12. The apparatus as recited in claim 11, wherein the image source module includes at least one of a receiver, transceiver, and transmitter.

13. The apparatus as recited in claim 9, further comprising:

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

14. A method of driving a device for modulating light, comprising:

applying a first voltage across a first electrode and a second electrode;

applying a second voltage to a third electrode in a first plane configured as a portion of a movable electrode, the movable electrode being disposed between and spaced apart from the first electrode and the second electrode and including a fourth electrode capacitively coupled to the third electrode that is positioned in a second different and parallel plane as the third electrode and separated from the third electrode by a gap; and

sensing a voltage of the fourth electrode.

15. The method of claim 14, wherein the movable electrode is displaced in response to the applying the second voltage.

16. The method of claim 15, wherein the sensed voltage is used to adjust the applied second voltage until the offset of the movable electrode is substantially equal to a desired offset.

17. A device for modulating light, comprising:

means for applying a first voltage across a first electrode and a second electrode;

means for applying a second voltage to a third electrode in a first plane configured as a portion of a movable electrode, the movable electrode being disposed between and spaced apart from the first electrode and the second electrode and including a fourth electrode capacitively coupled to the third electrode that is positioned in a second different and parallel plane as the third electrode and separated from the third electrode by a gap; and

means for sensing a voltage of the fourth electrode.

18. The device of claim 17, additionally including means for determining a position of the movable electrode based at least in part on the sensed voltage.