System and methods for extraction of threshold and mobility parameters in AMOLED displays
First Claim
1. A data extraction system for an organic light emitting device (OLED) based display, the system comprising:
- a pixel circuit including an organic light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input to provide a programming signal, and a storage device to store the programming signal;
a charge-pump amplifier having a current input and a voltage output, the charge-pump amplifier including an operational amplifier in negative feedback configuration, wherein the feedback is provided by a capacitor connected between the output and the inverting input of the operational amplifier, a common-mode voltage source to drive the non-inverting input of the operational amplifier, and an electronic switch coupled across the capacitor to reset the capacitor;
a switch module including the input coupled to the output of the pixel circuit and an output coupled to the input of the charge-pump amplifier, the switch module including a plurality of electronic switches to steer current in and out of the pixel circuit, provide a discharge path between the pixel circuit and the charge-pump amplifier, and isolate the charge-pump amplifier from the pixel circuit; and
a controller coupled to the pixel circuit, charge-pump amplifier and the switch module, the controller controlling input signals to the pixel circuit, charge-pump amplifier and switch module in a predetermined sequence to produce an output voltage value which is a function of a parameter of the pixel circuit, the sequence including providing a program voltage to the programming input to either;
pre-charge an internal capacitance of the pixel circuit to a charge level and transfer the charge to the charge-pump amplifier via the switch module to generate the output voltage value;
orprovide a current from the pixel circuit to the charge-pump amplifier via the switch module to produce the output voltage value by integration over a certain period of time.
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Accused Products
Abstract
Disclosed is a system and method to improve the extraction of transistor and OLED parameters in an AMOLED display for compensation of programming voltages to improve image quality. A pixel circuit includes an organic light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input to provide the programming signal, and a storage device to store the programming signal. A charge-pump amplifier has a current input and a voltage output. The charge-pump amplifier includes an operational amplifier in negative feedback configuration. The feedback is provided by a capacitor connected between the output and the inverting input of the operational amplifier. A common-mode voltage source drives the non-inverting input of the operational amplifier. An electronic switch is coupled across the capacitor to reset the capacitor.
74 Citations
14 Claims
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1. A data extraction system for an organic light emitting device (OLED) based display, the system comprising:
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a pixel circuit including an organic light emitting device, a drive device to provide a programmable drive current to the light emitting device, a programming input to provide a programming signal, and a storage device to store the programming signal; a charge-pump amplifier having a current input and a voltage output, the charge-pump amplifier including an operational amplifier in negative feedback configuration, wherein the feedback is provided by a capacitor connected between the output and the inverting input of the operational amplifier, a common-mode voltage source to drive the non-inverting input of the operational amplifier, and an electronic switch coupled across the capacitor to reset the capacitor; a switch module including the input coupled to the output of the pixel circuit and an output coupled to the input of the charge-pump amplifier, the switch module including a plurality of electronic switches to steer current in and out of the pixel circuit, provide a discharge path between the pixel circuit and the charge-pump amplifier, and isolate the charge-pump amplifier from the pixel circuit; and a controller coupled to the pixel circuit, charge-pump amplifier and the switch module, the controller controlling input signals to the pixel circuit, charge-pump amplifier and switch module in a predetermined sequence to produce an output voltage value which is a function of a parameter of the pixel circuit, the sequence including providing a program voltage to the programming input to either; pre-charge an internal capacitance of the pixel circuit to a charge level and transfer the charge to the charge-pump amplifier via the switch module to generate the output voltage value;
orprovide a current from the pixel circuit to the charge-pump amplifier via the switch module to produce the output voltage value by integration over a certain period of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A data extraction system for an organic light emitting device (OLED) based display, the system comprising:
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a pixel circuit including a drive transistor, an organic light emitting device, and a programming input coupled to the gate of the drive transistor, the drive transistor having a source or a drain coupled to the OLED; a charge-pump amplifier having an input and an integrated voltage output; a switch module including an input coupled to the output of the pixel circuit and an output coupled to the input of the charge-pump amplifier, the switch module including switches to steer current in and out of the pixel circuit, provide a discharge path between the pixel circuit and the charge-pump amplifier and isolate the charge-pump amplifier from the pixel circuit; and a controller coupled to the pixel circuit, charge-pump amplifier and the switch module, the controller controlling voltage inputs to the pixel circuit, charge-pump amplifier and switch module in a predetermined sequence to produce an output voltage value which is a function of a parameter of the pixel circuit, the sequence including providing a program voltage to the programming input to either pre-charge a capacitance of the pixel circuit to a charge level, transferring the charge to the charge-pump amplifier via the switch module to generate the output voltage value or providing a current from the pixel circuit to the charge-pump amplifier via the switch module to produce the output voltage value by integration. - View Dependent Claims (12, 13, 14)
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Specification