Interferometric modulators having charge persistence
AssigneeIdc, LLC
InventorClarence Chui
Life of this patent
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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.
Claims51
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 significantly change the actuation threshold.
A microelectromechanical (MEMS) device comprising:
- means for altering a state of the device, the state being based on an actuation threshold;
- and
- means for significantly altering the actuation threshold by actuating the device.
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:
- 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.
A method of manufacturing a microelectromechanical (MEMS) device, the method comprising:
- 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 transfer charge to the dielectric layer upon such contact.
A display device configured to display an image based on image data, the display device 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;
- 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.
A display device comprising:
- 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.
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:
- 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.
Dependencies are inferred from the claim text.