Drive method for MEMS devices
First Claim
1. A method of driving an interferometric modulator, comprising:
- establishing a first charge differential across a first and a second conductive plate of said interferometric modulator wherein said first and second conductive plates are separated by a variable gap distance;
isolating said first and second plates for a first duration; and
decreasing said charge differential to a final charge differential being less than said first charge differential and wherein said second charge differential corresponds to a second value of said variable gap distance.
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Abstract
Embodiments of exemplary MEMS interferometric modulators are arranged at intersections of rows and columns of electrodes. In certain embodiments, the column electrode has a lower electrical resistance than the row electrode. A driving circuit applies a potential difference of a first polarity across electrodes during a first phase and then quickly transition to applying a bias voltage having a polarity opposite to the first polarity during a second phase. In certain embodiments, an absolute value of the difference between the voltages applied to the row electrode is less than an absolute value of the difference between the voltages applied to the column electrode during the first and second phases.
108 Citations
22 Claims
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1. A method of driving an interferometric modulator, comprising:
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establishing a first charge differential across a first and a second conductive plate of said interferometric modulator wherein said first and second conductive plates are separated by a variable gap distance;
isolating said first and second plates for a first duration; and
decreasing said charge differential to a final charge differential being less than said first charge differential and wherein said second charge differential corresponds to a second value of said variable gap distance. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of driving an interferometric modulator, comprising:
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establishing a preliminary known charge state with respect to a first and a second conductive plate of a variable capacitor wherein said first and second conductive plates are separated by a variable gap distance;
establishing a first charge differential across said first and second conductive plates to force said first and second conductive plates toward each other;
isolating said first and second conductive plates for a first duration; and
decreasing said charge differential to a second charge differential being less than said first charge differential and wherein said second charge differential corresponds to a second value of said variable gap distance. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A charge control circuit, comprising:
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a power supply; and
a switch circuit configured to convey a pulse charge from said voltage source onto an interferometric modulator to isolate said interferometric modulator for a determined duration.
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- 17. The circuit of claim 17, wherein the switch circuit comprises a tri-state circuit.
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21. A micro-electromechanical system, comprising:
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an M-row by N-column array of a micro-electromechanical cells, wherein each of said cells includes a micro-electromechanical device (MEM device) having a variable capacitor formed by a first conductive plate and a second conductive plate separated by a variable gap distance; and
a switch circuit configured to apply a selected voltage level across first and second plates of a variable capacitor of said MEM device to cause a charge to accumulate on said variable capacitor, and wherein the charge is removed over time from said first conductive plate.
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22. A charge control system, comprising:
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means for establishing a first charge differential between first and second conductive plates of an interferometric modulator; and
means for isolating said first and second conductive plates for a first duration.
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Specification