Charged-based compensation and parameter extraction in AMOLED displays
First Claim
1. A method of extracting a circuit parameter from a pixel circuit and providing in-pixel compensation for variation or aging of the pixel circuit, the pixel circuit including a light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal, the method comprising:
- causing an in-pixel compensation of the pixel circuit by applying a reference voltage from a first line or a second line to a storage device in the pixel circuit to charge the storage device based on the reference voltage to self-compensate for a variation or aging of the drive device or the light emitting device or both in the pixel circuit;
extracting, using a circuit external to the pixel circuit, the circuit parameter from the pixel circuit by closing a first switch in the pixel circuit to allow the circuit parameter to be read external to the pixel circuit from the first line or from the second line; and
subsequently driving the pixel circuit using programming information that has been compensated based on at least the extracted circuit parameter, where the driving is carried out while the pixel circuit is disconnected from both the first line and the second line and while a second switch and a third switch connected in line between the drive device and a power supply are closed to cause the light emitting device to emit light according to the compensated programming information.
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Accused Products
Abstract
A system reads a desired circuit parameter from a pixel circuit that includes a light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal. One embodiment of the extraction system turns off the drive device and supplies a predetermined voltage from an external source to the light emitting device, discharges the light emitting device until the light emitting device turns off, and then reads the voltage on the light emitting device while that device is turned off. The voltages on the light emitting devices in a plurality of pixel circuits may be read via the same external line, at different times. In-pixel, charge-based compensation schemes are also discussed, which can be used with the external parameter extraction implementations.
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Citations
15 Claims
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1. A method of extracting a circuit parameter from a pixel circuit and providing in-pixel compensation for variation or aging of the pixel circuit, the pixel circuit including a light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal, the method comprising:
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causing an in-pixel compensation of the pixel circuit by applying a reference voltage from a first line or a second line to a storage device in the pixel circuit to charge the storage device based on the reference voltage to self-compensate for a variation or aging of the drive device or the light emitting device or both in the pixel circuit; extracting, using a circuit external to the pixel circuit, the circuit parameter from the pixel circuit by closing a first switch in the pixel circuit to allow the circuit parameter to be read external to the pixel circuit from the first line or from the second line; and subsequently driving the pixel circuit using programming information that has been compensated based on at least the extracted circuit parameter, where the driving is carried out while the pixel circuit is disconnected from both the first line and the second line and while a second switch and a third switch connected in line between the drive device and a power supply are closed to cause the light emitting device to emit light according to the compensated programming information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A pixel circuit having a light emitting device, comprising:
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a drive transistor connected to the light emitting device; a storage device coupled to the drive transistor and storing programming information to cause the light emitting device to emit light according to the programming information via the drive transistor; a first switch connected between the drive transistor and a first line to connect the drive transistor to the first line according to a first signal; a second switch connected between the drive transistor and a second line to connect the second line to the drive transistor according to a second signal, where the first line or the second line supplies a reference voltage to the storage device when the first switch or the second switch is closed, and where the reference voltage is applied from the first line or the second line to charge the storage device according to the reference voltage to self-compensate for a variation or aging of the pixel circuit; and a third switch and a fourth switch connected in line between the drive transistor and a power supply, where the third switch and the fourth switch and their respective control signals have an inverse signal function of the first switch and the second switch and their respective control signals, where the pixel circuit is compensated externally to the pixel circuit for variations or aging of the pixel circuit by extracting a circuit parameter using the second line and storing the circuit parameter externally to the pixel circuit. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification