Device and method for display memory using manipulation of mechanical response

• US 7,626,581 B2
• Filed: 04/22/2005
• Issued: 12/01/2009
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Chui, Clarence, Kothari, Manish
• Primary Examiner(s): Shalwala; Bipin
• Assistant Examiner(s): Chowdhury; Afroza Y
• Application Number:
  US11/112,487
• Publication Number:
  US 20060077505A1
• Time in Patent Office: 1,684 Days
• Field of Search: 345 84- 86, 345108-111
• US Class Current: 345/204
• 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 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Embodiments of an exemplary MEMS interferometric modulator comprise a movable layer and a fixed layer separated by an air gap. A driving scheme employs row/column actuation protocols which maintain voltages to the MEMS interferometric modulator that are above or below the voltage range necessary to place the MEMS interferometric modulator within a “hysteresis window” or “stability window.” Stable operation of the MEMS interferometric modulator is achieved by selecting mechanical design features that optimize the actuation and release times of the interferometric modulator. Some of the features affecting the release and actuation times include altering post spacing, altering internal stress or tension of the movable layer, altering the thickness or composition of the movable layer, altering the bulkiness of the tethers, perforating the movable layer and providing vias in the fixed layer.

Claims

1. A method of actuating an array of interferometric modulators multiple times to display a single row of data, the method comprising:

receiving a data signal for actuating one or more interferometric modulators during a time period corresponding to a single row;

actuating the one or more interferometric modulators with a potential difference such that the one or more interferometric modulators moves to an actuation state;

releasing the one or more interferometric modulators such that the one or more interferometric modulators drifts away from the actuation state and towards a released state; and

re-actuating the one or more interferometric modulators such that before reaching the released state, the one or more interferometric modulators moves back to the actuation state.

2. The method of claim 1 further comprising applying a bias voltage to the one or more interferometric modulators while the one or more interferometric modulator drift away from the actuation state.

3. The method of claim 2, wherein the potential difference is substantially equal to twice the bias voltage.

4. The method of claim 2, wherein an absolute value of the bias voltage is less than an absolute value of a voltage corresponding to a hysteresis window for the one or more interferometric modulators.

5. A method of driving an interferometric modulator to display a row of data, the method comprising:

receiving a data signal for display by the interferometric modulator during a period of time corresponding to a single row display period; and

actuating the interferometric modulator during the single row display period such that the interferometric modulator moves to an actuation state;

releasing the interferometric modulators such that one or more of the interferometric modulators drifts away from the actuation state and towards a released state; and

re-actuating the interferometric modulators such that before reaching the released state, the one or more of the interferometric modulators moves back to the actuation state.

6. The method of claim 5 further comprising applying a bias voltage to the interferometric modulator while the interferometric modulator moves away from the actuation state.

7. The method of claim 6, wherein the potential difference is substantially equal to twice the bias voltage.

8. The method of claim 6, wherein an absolute value of the bias voltage is less than an absolute value of a voltage corresponding to a hysteresis window for the interferometric modulator.

9. A method of writing display data to a row of interferometric modulators in an array of display elements, the method comprising:

writing a first set of display data to the row of interferometric modulators with a potential difference so as to actuate at least some of the interferometric modulators such that the at least some of the interferometric modulators move to an actuated state;

releasing the at least some of the interferometric modulators in the row of interferometric modulators such that the at least some of the interferometric modulators drift away from the actuated state and towards a released state; and

re-actuating the at least some of the interferometric modulators such that before the at least some of the interferometric modulators reach the released state, the at least some of the interferometric modulators move back to the actuated state.

10. The method of claim 9 further comprising applying a bias voltage to the at least some of the interferometric modulators in the row of interferometric modulators while the at least some of the interferometric modulators move away from the actuated state.

11. The method of claim 10, wherein the potential difference is substantially equal to twice the bias voltage.

12. The method of claim 10, wherein an absolute value of the bias voltage is less than an absolute value of a voltage corresponding to a hysteresis window for the at least some of the interferometric modulators.

13. A method of actuating an array of interferometric modulators multiple times to display a single row of data, the method comprising:

receiving a data signal for actuating one or more interferometric modulators during a time period corresponding to a single row;

actuating the one or more interferometric modulators with a potential difference such that the one or more interferometric modulators moves to a released state;

releasing the one or more interferometric modulators such that the one or more interferometric modulators drifts away from the released state and towards an actuated state; and

re-actuating the one or more interferometric modulators such that before reaching the actuated state, the interferometric modulators moves back to the released state.

14. The method of claim 13 further comprising applying a bias voltage to the one or more interferometric modulators while the one or more interferometric modulators drift away from the released state.

15. The method of claim 14, wherein the potential difference is substantially equal to twice the bias voltage.

16. The method of claim 14, wherein an absolute value of the bias voltage is greater than an absolute value of a voltage corresponding to a hysteresis window for the one or more interferometric modulators.

17. A method of driving an interferometric modulator to display a row of data, the method comprising:

receiving a data signal for display by the interferometric modulator during a period of time corresponding to a single row display period; and

actuating the interferometric modulator during the single row display period such that the interferometric modulator moves to a released state;

releasing the interferometric modulators such that one or more interferometric modulators drifts away from the released state and towards an actuated state; and

re-actuating the interferometric modulators such that before reaching the actuated state, the one of more of the interferometric modulators moves back to the released state.

18. The method of claim 17 further comprising applying a bias voltage to the interferometric modulator while the interferometric modulator moves away from the released state.

19. The method of claim 18, wherein the potential difference is substantially equal to twice the bias voltage.

20. The method of claim 18, wherein an absolute value of the bias voltage is greater than an absolute value of a voltage corresponding to a hysteresis window for the interferometric modulator.

21. A method of writing display data to a row of interferometric modulators in an array of display elements, the method comprising:

writing a first set of display data to the row of interferometric modulators with a potential difference so as to actuate at least some of the interferometric modulators such that the least some of the interferometric modulators move to a released state;

releasing the at least some of the interferometric modulators in the row of interferometric modulators such that the at least some of the interferometric modulators drift away from the released state and towards an actuated state; and

re-actuating the at least some of the interferometric modulators such that before the at least some of the interferometric modulators reach the actuated state, the at least some of the interferometric modulators move back to the released state.

22. The method of claim 21 further comprising applying a bias voltage to the at least some of the interferometric modulators in the row of interferometric modulators while the at least some of the interferometric modulators move away from the released state.

23. The method of claim 22, wherein the potential difference is substantially equal to twice the bias voltage.

24. The method of claim 22, wherein an absolute value of the bias voltage is greater than an absolute value of a voltage corresponding to a hysteresis window for the at least some of the interferometric modulators.