Systems and methods of actuating MEMS display elements

• US 20060057754A1
• Filed: 02/25/2005
• Published: 03/16/2006
• Est. Priority Date: 08/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Cummings, William J.
• Granted Patent: US 7,560,299 B2
• Time in Patent Office: Days
• US Class Current: 438/48
• 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 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Methods of writing display data to MEMS display elements are configured to minimize charge buildup and differential aging. The methods may include writing data with opposite polarities, and periodically releasing and/or actuating MEMS elements during the display updating process. Actuating MEMS elements with potential differences higher than those used during normal display data writing may also be utilized.

Claims

1. A method of actuating a MEMS display element, said MEMS display element comprising a portion of an array of MEMS display elements, said method comprising:

actuating said MEMS display element with a potential difference of a first polarity during a first portion of a display write process;

releasing saind MEMS display element; and

actuating said MEMS display element with a potential difference having a polarity opposite said first polarity during a second portion of said display write process.

2. The method of claim 1, wherein said first portion of said display write process comprises writing a first frame of display data to said array of MEMS display elements and wherein said second portion of said display write process comprises writing a second frame of display data to said array of MEMS display elements.

3. The method of claim 2, wherein one or more other frames of display data are written to said array between said first frame and said second frame.

4. The method of claim 1, comprising actuating said MEMS display element with a potential difference of said first polarity during a third portion of said display write process.

5. The method of claim 1, comprising alternately applying potential differences of opposite polarity to display elements of said array during alternating portions of said display write process.

10. The method of claim 1, comprising:

writing a first frame of display data to said array with a potential difference of said first polarity so as to actuate said MEMS display element;

placing substantially all MEMS elements in said array in a released state; and

writing a second frame of display data to said array with a potential difference of said opposite polarity so as to actuate said MEMS display element.

6. The method of claim 6, wherein said alternating portions of said display write process comprise writing alternating frames of display data to said array of MEMS display elements.

7. The method of claim 6, wherein said alternating portions of said display write process comprise writing alternating rows of display data to said array of MEMS display elements.

8. A method of writing display data to a row of MEMS display elements in an array of MEMS display elements, said method comprising:

placing substantially all MEMS elements in said row of said array into a released state;

writing a first set of display data to said row of said array with a potential difference of said first polarity so as to actuate said MEMS display element;

placing substantially all MEMS elements in said row of said array in a released state; and

writing a second set of display data to said row of said array with a potential difference of said opposite polarity so as to actuate said MEMS display element.

9. The method of claim 8, wherein said first set of display data and said second set of display data comprise identical data.

11. The method of claim 11, wherein said first frame of display data and said second frame of display data are the same.

12. A method of operating a MEMS element in an array of MEMS elements forming a display, said method comprising:

periodically applying a first potential difference to said MEMS element, said first potential difference having a magnitude sufficient to actuate said MEMS element, and having a polarity;

periodically applying a second potential difference to said MEMS element, said second potential difference being of approximately equal magnitude and opposite polarity as said first potential difference;

wherein said first potential difference and said second potential difference are respectively applied to said MEMS element at defined times and for defined time durations that depend on a rate at which image data is written to MEMS elements of said array, and wherein said first and second potential differences are each applied to said MEMS element an approximately equal amount of time over a given period of display use;

wherein said method comprises writing the same frame of data using both a potential differences of said first polarity and potential differences of said opposite polarity.

13. A method of writing display data to an array of MEMS display elements comprising:

actuating all MEMS elements in a portion of said array; and

writing display data to said portion of said array.

14. The method of claim 13, wherein said portion of said array comprises a row of MEMS elements of said array.

15. The method of claim 13, wherein said portion of said array comprises said entire array.

16. The method of claim 13, comprising releasing all MEMS elements in said portion of said array prior to writing display data to said portion of said array.

17. A method of writing display data to an array of MEMS display elements comprising periodically actuating at least some elements of said MEMS elements with a potential difference greater than a potential difference used when actuating said MEMS elements during the process of writing display data to said MEMS elements.

18. A system for writing data to an array of MEMS display elements, said system comprising:

a column driver;

a row driver;

wherein said row driver and column driver are configured to periodically actuate at least some elements of said array with a potential difference greater than a potential difference used when actuating elements during a display writing process.