Systems, devices, and methods for driving an analog interferometric modulator

• US 9,305,497 B2
• Filed: 08/28/2013
• Issued: 04/05/2016
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Seo, Jae Hyeong, Govil, Alok, Tung, Ming-Hau, Martin, Russel A.
• Primary Examiner(s): Zhou, Hong
• Application Number:
  US14/012,687
• Publication Number:
  US 20140210866A1
• Time in Patent Office: 951 Days
• Field of Search: 345 84- 85, 345/108, 345/690, 345/208, 345/210, 345/211, 345/212, 359/247, 359290-291, 359/295, 359/302
• US Class Current: 1/1
• CPC Class Codes: G02B 26/00 Optical devices or arrangements for the control of light using movable or deformable optical elements control of light by modification of the optical properties of the media of the elements involved therein G02F1/00
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Display elements of a display array include at least one fixed layer and a movable layer. The movable layer is positioned with respect to the at least one fixed layer by placing a charge on the movable layer and applying a voltage to the at least one fixed layer. The at least one fixed layer may be two layers positioned on either side of the movable layer. The movable layer may be positioned in a desired position when driving an array of display elements by executing a reset stage, a charging stage, and a bias stage.

Claims

1. A method of writing image data to an electromechanical display element to place the electromechanical display element into a defined display state, the display element including at least one stationary electrode and a movable electrode, the method comprising:

applying a first voltage to the at least one stationary electrode during a reset period;

applying a second voltage to the at least one stationary electrode during a charging period following the reset period;

applying a third voltage to the movable electrode during the charging period to charge the movable electrode with a charge Q defined at least in part by the third voltage;

applying a fourth voltage different from the second voltage to the at least one stationary electrode during a bias period following the charging period; and

electrically isolating the movable electrode during the bias period,

wherein the electromechanical display element includes first and second stationary electrodes,

wherein the movable electrode is positioned between the first and second stationary electrodes,

wherein the first voltage, second voltage, and fourth voltage are a first voltage differential, a second voltage differential, and a fourth voltage differential applied across the first stationary electrode and the second stationary electrode,

wherein the first voltage differential is substantially zero, and

wherein the movable electrode is electrically isolated during the reset period.

2. The method of claim 1, wherein the second voltage is substantially zero, and wherein the fourth voltage is non-zero.

3. The method of claim 1, further comprising applying a fifth voltage to the movable electrode during at least a portion of the reset period.

4. The method of claim 3, wherein the first voltage is substantially zero.

5. The method of claim 4, wherein the fifth voltage is substantially zero.

6. The method of claim 3, wherein the first, second, and fifth voltages are substantially zero, and wherein the third and fourth voltages are non-zero.

7. The method of claim 1, further comprising applying a fifth voltage to the movable electrode during at least a portion of the reset period.

8. The method of claim 7, wherein the fifth voltage is substantially zero.

9. The method of claim 8, wherein during the reset period, the movable electrode is placed in a reset state that is approximately centrally located between the first stationary electrode and the second stationary electrode.

10. The method of claim 1, wherein during the reset period, the movable electrode is placed in a reset state that is approximately centrally located between the first stationary electrode and the second stationary electrode.

11. The method of claim 8, wherein the first voltage differential is non-zero.

12. The method of claim 10, wherein during the reset period, the movable electrode is placed in a reset position that is nearer to the first stationary electrode than the second stationary electrode.

13. The method of claim 1, further comprising electrically isolating the movable electrode during a hold period following the charging period and prior to the bias period during which the second voltage differential is applied to the first and second stationary electrodes.

14. A display apparatus comprising:

an array of electromechanical display elements, each electromechanical display element including at least one stationary electrode and a movable electrode;

a driver circuit coupled to the array and configured to;

apply a first voltage to the at least one stationary electrode during a reset period;

apply a second voltage to the at least one stationary electrode during a charging period following the reset period;

apply a third voltage to the movable electrode during the charging period to charge the movable electrode with a charge Q defined at least in part by the third voltage;

apply a fourth voltage different from the second voltage to the at least one stationary electrode during a bias period following the charging period; and

electrically isolate the movable electrode during the bias period,

wherein the electromechanical display element includes first and second stationary electrodes,

wherein the movable electrode is positioned between the first and second stationary electrodes,

wherein the first voltage, second voltage, and fourth voltage are a first voltage differential, a second voltage differential, and a fourth voltage differential applied across the first stationary electrode and the second stationary electrode,

wherein the first voltage differential is substantially zero, and

wherein the movable electrode is electrically isolated during the reset period.

15. The display apparatus of claim 14, wherein the first and second stationary electrodes are formed as parallel strips of conductive material connected to the driver circuit.

16. The display apparatus of claim 15, wherein the movable electrode is supported between the parallel strips of conductive material on conductive support arms attached to a substrate.

17. The display apparatus of claim 16, wherein the support arms provide a conductive connection between one or more drive transistors and the movable electrode.

18. The display apparatus of claim 14, further comprising:

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

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

19. The display apparatus of claim 18, further comprising:

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

20. The display apparatus of claim 18, further comprising an image source module configured to send the image data to the processor, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

21. The display apparatus of claim 18, further comprising an input device configured to receive input data and to communicate the input data to the processor.

22. A display apparatus comprising:

an array of electromechanical display elements, each electromechanical display element including at least one stationary electrode and a movable electrode;

means for applying resetting voltages to the at least one stationary electrode for resetting display elements of the array;

means for applying charging voltages to the at least one stationary electrode and movable electrode for charging the movable electrodes of the display elements of the array;

means for applying biasing voltages to the at least one stationary electrode different from the charging voltages applied to the at least one stationary electrode for setting display elements of the array to a defined display state,

wherein the electromechanical display element includes first and second stationary electrodes,

wherein the movable electrode is positioned between the first and second stationary electrodes,

wherein the resetting voltages, the charging voltages, and the biasing voltages applied to the at least one stationary electrode are a resetting voltage differential, a charging voltage differential, and a biasing voltage differential applied across the first stationary electrode and the second stationary electrode,

wherein the resetting voltage differential applied to the at least one stationary electrode is substantially zero, and

wherein the movable electrode is electrically isolated when display elements of the array are reset.

23. The display apparatus of claim 22, wherein the means for applying resetting voltages, charging voltages, and biasing voltages includes a driver circuit.