Interferometric modulators having charge persistence
First Claim
Patent Images
1. A microelectromechanical (MEMS) device comprising:
- an electrode;
a dielectric layer coupled to the electrode, the dielectric layer comprising at least a substantially trappy surface; and
a movable layer extending over the surface of the dielectric layer so as to form a cavity therebetween, the movable layer being configured to contact the dielectric if an electrical potential between the electrode and at least a portion of the movable layer is greater than an actuation threshold,wherein when the movable layer contacts the dielectric layer charge is transferred between the movable layer and the dielectric layer to shift the actuation threshold to one of a plurality of functional differentiatable actuation thresholds.
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Abstract
An iterferometric modulator is formed having a dielectric with charge persistence. The interferometric modulator is addressed by a method making advantageous use of the charge persistence property, wherein the interferometric modulator is pre-charged in such a way that the pre-charging is not observable to a viewer, and the actuation voltage threshold of the imod is significantly lowered. Subsequently the interferometric modulator may be actuated with a significantly lower actuation voltage, thereby saving power.
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Citations
55 Claims
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1. A microelectromechanical (MEMS) device comprising:
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an electrode; a dielectric layer coupled to the electrode, the dielectric layer comprising at least a substantially trappy surface; and a movable layer extending over the surface of the dielectric layer so as to form a cavity therebetween, the movable layer being configured to contact the dielectric if an electrical potential between the electrode and at least a portion of the movable layer is greater than an actuation threshold, wherein when the movable layer contacts the dielectric layer charge is transferred between the movable layer and the dielectric layer to shift the actuation threshold to one of a plurality of functional differentiatable actuation thresholds. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A microelectromechanical (MEMS) device comprising;
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an electrode; a dielectric layer coupled to the electrode, the dielectric layer comprising at least a substantially trappy surface; and a movable layer extending over the dielectric layer so as to form a cavity therebetween, the movable layer being configured to contact the dielectric if an electrical potential between the electrode and at least a portion of the movable layer is greater than the actuation threshold; means for altering a state of the device, the state being based on an actuation threshold; and means for shifting the actuation threshold to one of a plurality of functional differentiatable actuation thresholds by actuating the device. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of addressing a microelectromechanical (MEMS) element that includes a movable layer and a dielectric layer comprising at least a substantially trappy surface, the method comprising:
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transferring a charge to the dielectric of the MEMS element during a pre-charge period without substantially altering a perceived appearance; and applying a first electrical potential difference to the MEMS element during a period sufficient to actuate the selected MEMS element and alter the perceived appearance. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A method of manufacturing a microelectromechanical (MEMS) device, the method comprising:
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forming an electrode; forming a dielectric layer comprising at least a substantially trappy surface, the dielectric layer being coupled to the electrode; and forming a movable layer over the dielectric layer so as to establish a cavity therebetween, the movable layer being configured to contact the dielectric if an electrical potential between the electrode and at least a portion of the movable layer is greater than an actuation threshold, and to shift the actuation threshold to one of a plurality of functional differentiatable actuation thresholds as a result of such contact. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A display device configured to display an image based on image data, the display device comprising:
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an array of microelectromechanical (MEMS) display elements, each MEMS display element comprising a movable layer and a dielectric layer comprising at least a substantially trappy surface; and a driving circuit configured to; receive the image data; select individual MEMS display elements based on the image data; apply a first electrical potential difference to the selected individual MEMS display elements to drive the movable layer to contact the dielectric and transfer charge thereto, wherein the image is not displayed; and apply a second electrical potential difference substantially simultaneously to selected and non-selected individual MEMS display elements of the array to actuate the selected individual MEMS display elements and display the image. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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38. A display device comprising:
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means for receiving image data; means for selecting one or more of an array of microelectromechanical (MEMS) display elements based at least in part on the image data, wherein each MEMS display element comprises a movable layer and a dielectric layer comprising at least a substantially trappy surface; means for applying a first electrical potential difference to each selected MEMS display element such that the movable layer contacts the dielectric and transfers charge thereto, wherein the image is not displayed; and means for applying a second electrical potential difference substantially simultaneously to all display elements of the array to actuate the selected MEMS display elements and display the image. - View Dependent Claims (39, 40, 41, 42, 43, 44)
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45. A method of displaying an image on a display comprising an array of microelectromechanical (MEMS) display elements, each MEMS display element comprising a movable layer and a dielectric layer comprising at least a substantially trappy surface, the method comprising:
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receiving image data; selecting individual MEMS display elements based on the received image data; transferring a charge to the dielectric of each selected MEMS display element during a pre-charge period without substantially altering the perceived appearance; and applying a first electrical potential difference substantially simultaneously to all MEMS display elements of the array during a display period sufficient to actuate the selected MEMS display elements and to display the image. - View Dependent Claims (46, 47, 48, 49, 50)
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51. A microelectromechanical (MEMS) device comprising:
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forming an electrode; forming a dielectric layer comprising at least a substantially trappy surface, the dielectric layer being coupled to the electrode; forming a movable layer over the dielectric layer so as to establish a cavity therebetween, the movable layer being configured to contact the dielectric if an electrical potential between the electrode and at least a portion of the movable layer is greater than an actuation threshold, and to transfer charge to the dielectric layer upon such contact; and configuring the electrode and the movable layer to be connected to additional MEMS devices of an array; configuring the dielectric layer to maintain the transferred charge for a period of time exceeding 100 ms after contact between the movable layer and the dielectric layer is broken. - View Dependent Claims (52)
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53. A method of manufacturing a microelectromechanical (MEMS) device, the method comprising:
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forming an electrode; forming a dielectric layer comprising at least a substantially trappy surface, the dielectric layer being coupled to the electrode; forming a movable layer over the dielectric layer so as to establish a cavity therebetween, the movable layer being configured to contact the dielectric if an electrical potential between the electrode and at least a portion of the movable layer is greater than an actuation threshold, and to transfer charge to the dielectric layer upon such contact; and configuring the electrode and the movable layer to be connected to additional MEMS devices of an array; configuring the dielectric layer to maintain the transferred charge for a period of time exceeding 100 ms after contact between the movable layer and the dielectric layer is broken. - View Dependent Claims (54, 55)
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Specification