Bistable DMD addressing method

• US 5,382,961 A
• Filed: 11/05/1993
• Issued: 01/17/1995
• 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, FRANK D
• Application Number:
  US08/148,127
• Time in Patent Office: 438 Days
• Field of Search: 345/84, 345/85, 345/108, 345/109, 345/904, 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, said method comprising the step of applying a bias voltage with an AC and a DC component to said array of pixels.

2. The method of claim 1 wherein each of said pixels assume one of two or more selected stable states according to a set of selective address voltages.

3. The method of claim 2 further comprising the step of electromechanically unlatching said pixels from their previously addressed state by removing said bias voltage from said array.

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

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

7. The method of claim 1 wherein said DC component has a negative polarity with respect to all phases of the AC component.

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

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

10. The method of claim 9 wherein said AC and said DC components are adjusted such that said beams are in periodic contact with an underlying DMD substrate.

11. The method of claim 9 wherein said AC component is selected to have the same frequency as the electromechanical resonant frequency of said beams.

12. A method of addressing an array of electromechanical pixels wherein each of said pixels comprises beams and 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 each of said pixels in one of said selected stable states by applying a bias voltage with an AC and a DC component to said array of pixels, wherein said AC and DC components are selected such that said beams are in periodic contact with an underlying substrate thus avoiding deleterious effects caused by sustained contact between the beam and the underlying substrate;

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

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

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 each of said pixels by reestablishing said bias voltage.

13. The method of claim 12 wherein said AC component is selected to have the same frequency as the electromechanical resonant frequency of said beams.

14. The method of claim 12 wherein said allowing step is approximately 10 to 20 μ

s in duration.

15. The method of claim 12 wherein said DC component has a magnitude of approximately 16 volts and said AC component has a magnitude of approximately 5 volts.

16. The method of claim 12 wherein said electromechanical latching step is approximately 10 to 20 μ

s in duration.

17. A digital micrormirror device (DMD), said DMD comprising:

a. 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;

b. a means for applying said set of selective address voltages to said array of electromechanical pixels;

c. a means for electromechanically latching each of said pixels in one of said selected stable states by applying a bias voltage; and

d. a means for forming said bias voltage to have an AC and a DC component.

18. The DMD of claim 17 wherein said AC and said DC components are adjusted such that said beams are in periodic contact with an underlying DMD substrate.

19. The DMD of claim 17 wherein said AC component is selected to have the same frequency as the electromechanical resonant frequency of said beams.