ACTIVE MATRIX DISPLAY DEVICE WITH OPTICAL FEEDBACK AND DRIVING METHOD THEREOF
First Claim
1. An active matrix display device comprising an array of display pixels, each pixel comprising:
- a current-driven light-emitting display element (2);
a drive transistor (22) for driving a current through the display element (2);
a storage capacitor (30) for storing a voltage to be used for addressing the drive transistor;
a discharge transistor (36) for discharging the storage capacitor (30) thereby to switch off the drive transistor (22);
a discharge capacitor (40) between the gate of the discharge transistor and its source, anda light-dependent device (38) for controlling the timing of the operation of the discharge transistor (36) by charging or discharging the discharge capacitor in dependence on the light output of the display element (2),wherein the device further comprises;
reading circuitry (70) for monitoring the charge on the discharge capacitor (40); and
data correction means (90) for correcting pixel data to be applied to the pixel in response to the reading circuitry measurements.
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Accused Products
Abstract
An active matrix display device comprises an array of display pixels, each pixel comprising a current-driven light emitting display element (2), a drive transistor (22) for driving a current through the display element (2) and a storage capacitor (30) for storing a voltage to be used for addressing the drive transistor (22). A discharge transistor (36) is used for discharging the storage capacitor (30) thereby to switch off the drive transistor in dependence on the light output of the display element (2). Reading circuitry (70) is used for monitoring the charge on a discharge capacitor (40), the pixel data is corrected in response to the reading circuitry measurements. This can extend the lifetime of the display.
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Citations
22 Claims
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1. An active matrix display device comprising an array of display pixels, each pixel comprising:
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a current-driven light-emitting display element (2); a drive transistor (22) for driving a current through the display element (2); a storage capacitor (30) for storing a voltage to be used for addressing the drive transistor; a discharge transistor (36) for discharging the storage capacitor (30) thereby to switch off the drive transistor (22); a discharge capacitor (40) between the gate of the discharge transistor and its source, and a light-dependent device (38) for controlling the timing of the operation of the discharge transistor (36) by charging or discharging the discharge capacitor in dependence on the light output of the display element (2), wherein the device further comprises; reading circuitry (70) for monitoring the charge on the discharge capacitor (40); and data correction means (90) for correcting pixel data to be applied to the pixel in response to the reading circuitry measurements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of driving an active matrix display device comprising an array of display pixels each comprising a drive transistor (22) and a current-driven light emitting display element (2), the method comprising, for each addressing of the pixel:
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applying a pixel drive voltage to an input of the pixel; storing a voltage derived from the pixel drive voltage on a discharge capacitor (40); charging a storage capacitor (30) to a drive voltage, and driving a current through the display element by applying the storage capacitor voltage to the drive transistor (22) thereby illuminating the display element (2); switching on a discharge transistor (36) using charge flow through a light dependent device (38) illuminated by the light output of the display element (2), the charge flow charging or discharging the discharge capacitor (40); and discharging the storage capacitor (30) using the discharge transistor (36) thereby to turn off the drive transistor, wherein the method further comprises monitoring the charge on the discharge capacitor (40) and correcting pixel data to be applied to the pixel in response to the charge monitoring. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification