System and methods for extraction of threshold and mobility parameters in AMOLED displays
First Claim
1. A method of extracting a circuit parameter from a 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:
- turning on the drive device so that the voltage of the light emitting device rises to a level higher than its turn-on voltage,turning off the drive device so that the voltage on the light emitting device is discharged through the light emitting device until the light emitting device turns off, andreading the voltage on the light emitting device while that device is turned off.
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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.
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Citations
7 Claims
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1. A method of extracting a circuit parameter from a 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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turning on the drive device so that the voltage of the light emitting device rises to a level higher than its turn-on voltage, turning off the drive device so that the voltage on the light emitting device is discharged through the light emitting device until the light emitting device turns off, and reading the voltage on the light emitting device while that device is turned off.
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2. A method of extracting a circuit parameter from a pixel circuit including a light emitting device, a drive transistor having gate, source and drain terminals 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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turning on the drive device and measuring the current and voltage of the drive transistor while changing the voltage between the gate and the source or drain of the drive transistor to operate the drive transistor in the linear regime during one time interval and in the saturated regime during a second time interval, and extracting a parameter of the light emitting device from the relationship of the currents and voltages measured with the drive transistor operating in the two regimes.
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3. A system for extracting a circuit parameter from a 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 system comprising
a controller coupled to the pixel circuit and supplying controlling input signals to the pixel circuit in a predetermined sequence to produce an output voltage value which is a function of a parameter of the pixel circuit, the sequence including turning off the drive device and supplying a predetermined voltage from an external source to said light emitting device, discharging said light emitting device until the light emitting device turns off, and reading the voltage on the light emitting device while that device is turned off.
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6. A system for extracting a circuit parameter from a 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 system comprising:
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a controller coupled to the pixel circuit and supplying controlling input signals to the pixel circuit in a predetermined sequence to produce an output voltage value which is a function of a parameter of the pixel circuit, the sequence including turning on the drive device so that the voltage of the light emitting device rises to a level higher than its turn-on voltage, turning off the drive device so that the voltage on the light emitting device is discharged through the light emitting device until the light emitting device turns off, and reading the voltage on the light emitting device while that device is turned off.
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7. A system for extracting a circuit parameter from a pixel circuit including a light emitting device, a drive transistor having gate, source and drain terminals to provide a programmable drive current to the light emitting device, a programming input, and a storage device to store a programming signal, the system comprising:
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a controller coupled to the pixel circuit and supplying controlling input signals to the pixel circuit in a predetermined sequence to produce an output voltage value which is a function of a parameter of the pixel circuit, the sequence including turning on the drive device and measuring the current and voltage of the drive transistor while changing the voltage between the gate and the source or drain of the drive transistor to operate the drive transistor in the linear regime during one time interval and in the saturated regime during a second time interval, and extracting a parameter of the light emitting device from the relationship of the currents and voltages measured with the drive transistor operating in the two regimes.
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Specification