Bistable DMD addressing method

• US 5,285,196 A
• Filed: 10/15/1992
• Issued: 02/08/1994
• Est. Priority Date: 10/15/1992
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Gale, Richard O. Jr.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): Lopez, F. Daniel
• Application Number:
  US07/961,997
• Time in Patent Office: 481 Days
• Field of Search: 340/764, 340/783, 340/805, 358/62, 358/223, 359/230, 359/290, 359/291, 359/292, 359/295
• US Class Current: 345/108
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G06K 15/1238 simultaneously exposing more than one point
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: Y10S 345/904 Display with fail/safe testing feature

Abstract

A preferred embodiment of the present invention provides a method of addressing a digital micromirror device (DMD) having an array of electromechanical pixels (20) comprising deflectable beams (30) wherein each of the pixels (20) assume one of two or more selected stable states according to a set of selective address voltages. A first step of the preferred method is electromechanically latching, by applying a bias voltage with an AC and a DC component to the array of pixels (20), each of the pixels (20) in one of the selected stable states. A second step is applying a new set of selective address voltages to all the pixels (20) in the array. A third step is electromechanically unlatching, by removing the bias voltage from the array, the pixels (20) from their previously addressed state. A fourth step is allowing the array of pixels (20) to assume a new state in accordance with the new set of selective address voltages. A fifth step is electromechanically latching, by reestablishing the bias voltage with the AC component and the DC component, each of the pixels (20 ). Other devices, systems and methods are also disclosed.

Claims

1. A method of addressing an array of electromechanical pixels wherein each of said pixels assume one of two or more selected stable states according to a set of selective address voltages, said method comprising the steps of:

a) electromechanically latching, by applying a bias voltage with an AC and a DC component to said array of pixels, each of said pixels in one of said selected stable states;

b) applying a new set of selective address voltages to all said pixels in said array;

c) electromechanically unlatching, by removing said bias voltage from said array, said pixels from their previously addressed state;

d) allowing said array of pixels to assume a new state in accordance with the new set of selective address voltages; and

e) electromechanically latching, by reestablishing said bias voltage, each of said pixels.

2. The method of claim 1 wherein said applying step occurs before said electromechanically unlatching step.

3. The method of claim 1 wherein said pixel comprises deflectable beams and said AC component is selected to have the same frequency as the electromechanical resonant frequency of said beams.

4. The method of claim 3 wherein said AC and DC components are adjusted such that said beams are in periodic contact with an underlying substrate.

5. The method of claim 1 wherein said allowing step is approximately 10 to 20 μ

s in duration.

6. The method of claim 1 wherein said DC component is approximately 16 volts.

7. The method of claim 6 wherein said DC component has a negative polarity.

8. The method of claim 1 wherein said AC component is approximately 5 volts.

9. The method of claim 1 wherein said electromechanical latching step is approximately 10 to 20 μ

s in duration.

10. A method of addressing a digital micromirror device (DMD) having an array of electromechanical pixels comprising deflectable beams wherein each of said pixels assume one of two or more selected stable states according to a set of selective address voltages, said method comprising the steps of:

a) electromechanically latching, by applying a bias voltage with an AC and a DC component to said array of pixels, each of said pixels in one of said selected stable states;

b) applying a new set of selective address voltages to all said pixels in said array;

c) electromechanically unlatching, by removing said DC component of said bias voltage, said pixels from their previously addressed state;

d) allowing said array of pixels to assume a new state in accordance with the new set of selective address voltages; and

e) electromechanically latching, by reestablishing said DC component of said bias voltage, each of said pixels.

11. The method of claim 10 wherein said applying step occurs before said electromechanically unlatching step.

12. The method of claim 10 wherein said AC and DC components are adjusted such that said beams are in periodic contact with an underlying DMD substrate.

13. The method of claim 10 wherein said AC component is selected to have the same frequency as the electromechanical resonant frequency of said beams.

14. The method of claim 10 wherein said allowing step is approximately 10 to 20 μ

s in duration.

15. The method of claim 10 wherein said DC component is approximately 16 volts.

16. The method of claim 15 wherein said DC component has a negative polarity.

17. The method of claim 10 wherein said AC component is approximately 5 volts.

18. The method of claim 10 wherein said electromechanical latching step is approximately 10 to 20 μ

s in duration.