Voltage-programming scheme for current-driven AMOLED displays
First Claim
Patent Images
1. A system for driving a display which includes a pixel circuit having a plurality of thin film transistors and an organic light emitting diode, the system comprising:
- a voltage driver for generating a programming voltage to program the pixel circuit through a data line coupled to the pixel circuit;
a programmable current source for generating a current to apply to the pixel circuit during a calibration mode to extract a degradation of the pixel circuit through the data line; and
a switching network for selectively connecting the voltage driver or the programmable current source to the pixel circuit through the data line.
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Abstract
A system and method for driving an AMOLED display is provided. The AMOLED display includes a plurality of pixel circuits. A voltage-programming scheme, a current-programming scheme or a combination thereof is applied to drive the display. Threshold shift information, and/or voltage necessary to obtain hybrid driving circuit may be acquired. A data sampling may be implemented to acquire a current/voltage relationship. A feedback operation may be implemented to correct the brightness of the pixel.
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Citations
37 Claims
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1. A system for driving a display which includes a pixel circuit having a plurality of thin film transistors and an organic light emitting diode, the system comprising:
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a voltage driver for generating a programming voltage to program the pixel circuit through a data line coupled to the pixel circuit; a programmable current source for generating a current to apply to the pixel circuit during a calibration mode to extract a degradation of the pixel circuit through the data line; and a switching network for selectively connecting the voltage driver or the programmable current source to the pixel circuit through the data line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 26, 27, 28)
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11. A system for driving a pixel circuit having a plurality of thin film transistors and an organic light emitting diode, the system comprising:
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a pre-charge controller for pre-charging and discharging a data node of the pixel circuit to acquire threshold voltage information of a driving transistor from the data node using an external driving circuit outside the pixel circuit; an analog to digital converter for generating digital threshold voltage information indicative of the acquired threshold voltage information; a memory for digitally storing the digital threshold voltage information for use in a future driving cycle of the pixel circuit; a controller configured to retrieve the digital threshold voltage information from the memory and to adjust a programming voltage for a future driving cycle based on the retrieved digital threshold voltage information and based on video data information; and a hybrid driving circuit for programming the pixel circuit via the data node according to instructions from the controller. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A system for driving a pixel circuit having a plurality of thin film transistors and an organic light emitting diode, the system comprising:
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a sampler for sampling, from a data node of the pixel circuit, a voltage required to program the pixel circuit; a current source for providing current to the pixel circuit, the provided current causing the voltage sampled from the data node to be established on the data node; a memory for storing in a calibration table, as digital information, the voltage required to program the pixel circuit for use in a future programming cycle of the pixel circuit; and a programming circuit for programming the pixel circuit via the data node based on the digital information stored in the calibration table and based on video data information indicative of an amount of light to be emitted from the pixel circuit. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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29. A method of driving a pixel circuit having a plurality of thin film transistors including a drive thin film transistor and an organic light emitting diode, the method comprising:
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selecting a pixel circuit and pre-charging a data node of the pixel circuit using an external circuit connected through the data node; allowing the pre-charged data node to be discharged; extracting a threshold voltage of a drive thin film transistor via the data node; converting, via an analog to digital converter, the extracted threshold voltage to digital data; storing the digital data indicative of the extracted threshold voltage in a memory; compensating a programming signal based on the stored digital data indicative of the extracted threshold voltage; and programming the pixel circuit with the compensated programming signal via the data node. - View Dependent Claims (30, 31, 32)
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33. A method of driving a pixel circuit having a plurality of thin film transistors and an organic light emitting diode, the method comprising:
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applying a current from a current source to the pixel circuit via a data node of the pixel circuit, the applied current establishing a voltage required to program the pixel circuit with the applied current on the data node; sampling, from the data node, the voltage required to program the pixel circuit with the applied current; storing digital data indicative of the sampled voltage required to program the pixel circuit in a memory; and programming the pixel circuit, via the data node, based on the stored digital data and based on information indicative of an amount of light to be emitted from the pixel circuit. - View Dependent Claims (34, 35, 36)
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37. A method of driving a pixel circuit having a driving transistor for driving a light emitting device, the method comprising:
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pre-charging a data node of the pixel circuit via a data line coupled to the pixel circuit; discharging the data node to acquire threshold voltage information of the driving transistor, the pre-charging and discharging being carried out during an initial driving cycle of the pixel circuit; storing, as digital threshold voltage information, the acquired threshold voltage information in a memory located outside the pixel circuit; retrieving the digital threshold voltage information from the memory; adjusting digital programming data for a subsequent driving cycle following the initial driving cycle based on the retrieved digital threshold voltage information; programming the pixel circuit to emit light according to the adjusted programming data, the programming being carried out via the data line coupled to the data node.
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Specification