Method and system for driving an active matrix display circuit
First Claim
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1. A display system, the system comprising:
- a pixel circuit for being programmed according to programming information during a programming cycle, and driven to emit light according to the programming information during an emission cycle, the pixel circuit comprising;
a light emitting device for emitting light during the emission cycle, a drive transistor for conveying a drive current through the light emitting device during the emission cycle, said drive transistor having gate, source and drain terminals,a storage capacitor for being charged with a voltage based at least in part on the programming information during the programming cycle, said storage capacitor having first and second terminals, said first terminal being coupled to the gate of said drive transistor,a first switch transistor, operated according to a first select line, for conveying the voltage to the storage capacitor during the programming cycle, anda regulating transistor for conveying a leakage current to a gate terminal of the drive transistor, thereby adjusting a gate voltage of the drive transistor,said regulating transistor having gate, source and drain terminals, said gate terminal of the regulating transistor being coupled to one of said terminals of said storage capacitor, one of the source and drain terminals of said regulating transistor being coupled to said gate terminal of said drive transistor, and the other of said source and drain terminals of said regulating transistor being direct connected to a node between said light emitting device and said drive transistor, wherein the pixel circuit provides constant averaged current over a frame time.
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Abstract
A method and system for driving an active matrix display is provided. The system includes a drive circuit for a pixel having a light emitting device. The drive circuit includes a drive transistor for driving the light emitting device. The system includes a mechanism for adjusting the gate voltage of the drive transistor.
337 Citations
13 Claims
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1. A display system, the system comprising:
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a pixel circuit for being programmed according to programming information during a programming cycle, and driven to emit light according to the programming information during an emission cycle, the pixel circuit comprising; a light emitting device for emitting light during the emission cycle, a drive transistor for conveying a drive current through the light emitting device during the emission cycle, said drive transistor having gate, source and drain terminals, a storage capacitor for being charged with a voltage based at least in part on the programming information during the programming cycle, said storage capacitor having first and second terminals, said first terminal being coupled to the gate of said drive transistor, a first switch transistor, operated according to a first select line, for conveying the voltage to the storage capacitor during the programming cycle, and a regulating transistor for conveying a leakage current to a gate terminal of the drive transistor, thereby adjusting a gate voltage of the drive transistor, said regulating transistor having gate, source and drain terminals, said gate terminal of the regulating transistor being coupled to one of said terminals of said storage capacitor, one of the source and drain terminals of said regulating transistor being coupled to said gate terminal of said drive transistor, and the other of said source and drain terminals of said regulating transistor being direct connected to a node between said light emitting device and said drive transistor, wherein the pixel circuit provides constant averaged current over a frame time. - View Dependent Claims (2, 3, 4, 5)
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6. A method of operating a display having a pixel circuit for driving a light emitting device, the method comprising:
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charging the pixel circuit, during a programming cycle, by turning on a first switch transistor such that a voltage is charged on a storage capacitor having first and second terminals with the first terminal coupled to a gate terminal of a drive transistor that also has source and drain terminals; and conveying a leakage current by a regulating transistor having gate, source and drain terminals, said gate terminal of said regulating transistor being coupled to the second terminal of said storage capacitor, one of the source and drain terminals of said regulating transistor being coupled to the gate terminal of the drive transistor, and the other of said source and drain terminals of said regulating transistor being direct connected to a node between said light emitting device and said drive transistor, thereby adjusting the voltage at said node. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification