Low power circuits for active matrix emissive displays and methods of operating the same
First Claim
1. A display having a plurality of pixels, each pixel comprising:
- a light-emitting device configured to emit light in response to a current flowing through the light-emitting device, a luminance of the light-emitting device being dependent upon the current;
a transistor coupled to the light-emitting device and configured to provide the current through the light-emitting device, the current increasing with a ramp voltage applied to a control terminal of the transistor; and
a first switching device configured to switch off in response to the luminance of the light-emitting device having reached a specified level, thereby disconnecting the ramp voltage from the transistor; and
wherein the first switching device is further configured to stay off thereby allowing the luminance of the light-emitting device to be kept at the specified level until the pixel is rewritten.
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Accused Products
Abstract
The embodiments of the present invention provide a flat panel display having a plurality of pixels, each comprising a light-emitting device configured to emit light in accordance with a current flowing through the light-emitting device, a transistor coupled to the light-emitting device and configured to provide the current through the light-emitting device, the current increasing with a ramp voltage applied to a control terminal of the transistor, and a switching device configured to switch off in response to the luminance of the light-emitting device having reached a specified level, thereby disconnecting the ramp voltage from the transistor and locking the brightness at the specified level. The switching device is further configured to stay off thereby allowing the luminance of the light-emitting device to be kept at the specified level until the pixel is rewritten in a different frame.
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Citations
20 Claims
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1. A display having a plurality of pixels, each pixel comprising:
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a light-emitting device configured to emit light in response to a current flowing through the light-emitting device, a luminance of the light-emitting device being dependent upon the current; a transistor coupled to the light-emitting device and configured to provide the current through the light-emitting device, the current increasing with a ramp voltage applied to a control terminal of the transistor; and a first switching device configured to switch off in response to the luminance of the light-emitting device having reached a specified level, thereby disconnecting the ramp voltage from the transistor; and wherein the first switching device is further configured to stay off thereby allowing the luminance of the light-emitting device to be kept at the specified level until the pixel is rewritten. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling the brightness of a pixel in a display, the method comprising:
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switching on a switching device by applying a first control voltage to a first control terminal and a second control voltage to a second control terminal of the switching device; applying a ramp voltage through the switching device to a gate of a transistor serially coupled with the light-emitting device thereby causing a luminance of the light-emitting device to increase with the ramp voltage; and illuminating an optical sensor with the light from the light-emitting device thereby causing an electrical parameter associated with the optical sensor to change according to the luminance of the light-emitting device; and wherein the second control voltage is dependent on the electrical parameter and changes to a different value in response to the luminance of the light-emitting device having reached a specified level for the pixel, thereby switching off the switching device. - View Dependent Claims (11, 12, 13, 14)
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15. A display having a plurality of pixels, each pixel comprising:
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a light-emitting device configured to emit light in response to a current flowing through the light-emitting device, a luminance of the light-emitting device being dependent upon the current; a transistor configured to provide the current through the light-emitting device, the current increasing with a ramp voltage applied to a control terminal of the current source; and a first switching device configured to disconnect the ramp voltage from the transistor in response to the luminance of the light-emitting device having reached a specified level; and wherein the transistor and the light-emitting device are serially coupled with each other between a variable voltage source and ground. - View Dependent Claims (16, 17, 18, 19)
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20. A display having a plurality of pixels, each pixel comprising:
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a light-emitting device; means for allowing a ramp voltage to control a current through the light-emitting device so that the luminance of the light-emitting device increases with the ramp voltage; means for disconnecting the ramp voltage from the light-emitting device in response to the luminance having reached a specified level; and means for keeping the luminance at the specified level after the ramp voltage is disconnected; and wherein the means for keeping comprises means for isolating the pixel from other pixels in the display.
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Specification