Amoled displays with multiple readout circuits

Patent metadata

Field	Value
Publication number	US-2020013335-A1
Application number	US-201916574191-A
Country	US
Kind code	A1
Filing date	Sep 18, 2019
Priority date	Mar 15, 2013
Publication date	Jan 9, 2020
Grant date	—

Abstract

The OLED voltage of a selected pixel is extracted from the pixel produced when the pixel is programmed so that the pixel current is a function of the OLED voltage. One method for extracting the OLED voltage is to first program the pixel in a way that the current is not a function of OLED voltage, and then in a way that the current is a function of OLED voltage. During the latter stage, the programming voltage is changed so that the pixel current is the same as the pixel current when the pixel was programmed in a way that the current was not a function of OLED voltage. The difference in the two programming voltages is then used to extract the OLED voltage.

First claim

1 - 25 . (canceled)

26 . A system for determining a value of an operational parameter of a circuit element in a pixel in an array of pixels in a display, the pixel including a storage capacitor coupled to a drive transistor for supplying current to a light-emitting device of the pixel as a function of a programming of the storage capacitor, the system comprising:
a controller adapted to:
vary a first input signal provided to the pixel and measure a first output signal of the pixel in response thereto, until reaching a final first input signal provided to the pixel when the first output signal equals a predetermined signal, wherein one of the first output signal and the predetermined signal is a function of the operational parameter of the circuit element; and
extract the value of the operational parameter of the circuit element with use of the final first input signal.

27 . The system of claim 26 wherein the predetermined signal is a predetermined known reference current and the first output signal is a first output current which is a function of the operational parameter of the circuit element.

28 . The system of claim 26 wherein the predetermined signal is a previously measured second output signal, the second output signal previously output from said pixel in response to a second input signal provided to the pixel.

29 . The system of claim 28 wherein the controller is adapted to extract the operational parameter of the circuit element with use of the second input signal provided to the pixel.

30 . The system of claim 29 wherein the controller is adapted to extract the operational parameter of the circuit element from a difference between the final first input signal provided to the pixel and the second input signal.

31 . The system of claim 28 wherein the controller is further adapted to, prior to said varying the first input signal, setting the second input signal provided to the pixel to generate said measured second output signal, wherein only one of the first output signal and the predetermined signal is a function of the operational parameter of the circuit element.

32 . The system of claim 26 wherein the first output signal is a function of the operational parameter of the circuit element, and wherein the controller is further adapted to:
at an earlier time previous to said extracting of the operational parameter of the circuit element, vary a third input signal provided to the pixel and measure a third output signal of the pixel in response thereto, until reaching a final third input signal provided to the pixel when the third output signal equals the predetermined signal, wherein one of the predetermined signal and the third output signal is a function of the operational parameter of the circuit element at the earlier time, and extract the value of the operational parameter of the circuit element at the earlier time with use of the final third input signal; and
extract the value of the operational parameter of the circuit element with use of the final third input signal provided to the pixel and the final first input signal provided to the pixel and the value of the operational parameter of the circuit element at the earlier time.

33 . The system of claim 32 wherein only one of the predetermined signal and the third output signal is a function of the operational parameter of the circuit element at the earlier time.

34 . The system of claim 26 , wherein the circuit element is the light emitting device of the pixel, and the operational parameter is the operational voltage V OLED of the light emitting device.

35 . A method of determining a value of an operational parameter of a circuit element in a pixel in an array of pixels in a display, the pixel including a storage capacitor coupled to a drive transistor for supplying current to a light-emitting device of the pixel as a function of a programming of the storage capacitor, the method comprising:
varying a first input signal provided to the pixel and measuring a first output signal of the pixel in response thereto, until reaching a final first input signal provided to the pixel when the first output signal equals a predetermined signal, wherein one of the first output signal and the predetermined signal is a function of the operational parameter of the circuit element; and extracting the value of the operational parameter of the circuit element with use of the final first input signal provided to the pixel.

36 . The method of claim 35 wherein the predetermined signal is a predetermined known reference current and the first output signal is a first output current which is a function of the operational parameter of the circuit element.

37 . The method of claim 35 wherein the predetermined signal is a previously measured second output signal, the second output signal previously output from said pixel in response to a second input signal provided to the pixel.

38 . The method of claim 37 wherein said extracting comprises extracting the operational parameter of the circuit element with use of the second input signal provided to the pixel.

39 . The method of claim 38 wherein said extracting comprises extracting the operational parameter of the circuit element from a difference between the final first input signal provided to the pixel and the second input signal provided to the pixel.

40 . The method of claim 37 further comprising:
prior to said varying the first input signal provided to the pixel, setting the second input signal provided to the pixel to generate said measured second output signal, wherein only one of the first output signal and the predetermined signal is a function of the operational parameter of the circuit element.

41 . The method of claim 35 wherein the first output signal is a function of the operational parameter of the circuit element, the method further comprising:
at an earlier time previous to said extracting of the operational parameter of the circuit element, varying a third input signal provided to the pixel and measuring a third output signal of the pixel in response thereto, until reaching a final third input signal provided to the pixel when the third output signal equals the predetermined signal, wherein one of the predetermined signal and the third output signal is a function of the operational parameter of the circuit element at the earlier time, and extracting the value of the operational parameter of the circuit element at the earlier time with use of the final third input signal provided to the pixel; and
extracting the value of the operational parameter of the circuit element with use of the final third input signal provided to the pixel and the final first input signal provided to the pixel and the value of the operational parameter of the circuit element at the earlier time.

42 . The method of claim 41 wherein only one of the predetermined signal and the third output signal is a function of the operational parameter of the circuit element at the earlier time.

43 . The method of claim 35 , wherein the circuit element is the light emitting device of the pixel, and the operational parameter is the operational voltage V OLED of the light emitting device.

Assignees

• Ignis Innovation Inc

Inventors

• Soni Jaimal
• Ngan Ricky Yik Hei
• Chaji Gholamreza
• Zahirovic Nino
• Dionne Joseph Marcel

Classifications

• G09G3/3233 Primary

  with pixel circuitry controlling the current through the light-emitting element · CPC title

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title

• G09G2320/0295

  by monitoring each display pixel · CPC title

• G09G3/3291

  in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements · CPC title

• G09G2320/045

  Compensation of drifts in the characteristics of light emitting or modulating elements · CPC title