AMOLED displays with multiple readout circuits

Patent metadata

Field	Value
Publication number	US-11074859-B2
Application number	US-201916574191-A
Country	US
Kind code	B2
Filing date	Sep 18, 2019
Priority date	Mar 15, 2013
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

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

What is claimed is:

1. A system for determining a value of an operational parameter of a light-emitting device 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 the 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 electrical signal provided to the pixel and measure a first output electrical signal of the pixel in response thereto, until reaching a final first input electrical signal provided to the pixel when the first output electrical signal equals a predetermined electrical signal, wherein one of the first output electrical signal and the predetermined electrical signal is a function of the operational parameter of the light-emitting device; and
extract the value of the operational parameter of the light-emitting device with use of the final first input electrical signal.

2. The system of claim 1 wherein the predetermined electrical signal is a predetermined known reference current and the first output electrical signal is a first output current which is a function of the operational parameter of the light-emitting device.

3. The system of claim 1 wherein the predetermined electrical signal is a previously measured second output electrical signal, the second output electrical signal previously output from said pixel in response to a second input electrical signal provided to the pixel.

4. The system of claim 3 wherein the controller is adapted to extract the operational parameter of the light-emitting device with use of the second input electrical signal provided to the pixel.

5. The system of claim 4 wherein the controller is adapted to extract the operational parameter of the light-emitting device from a difference between the final first input electrical signal provided to the pixel and the second input electrical signal.

6. The system of claim 3 wherein the controller is further adapted to, prior to said varying the first input electrical signal, setting the second input electrical signal provided to the pixel to generate said measured second output electrical signal, wherein only one of the first output electrical signal and the predetermined electrical signal is a function of the operational parameter of the light-emitting device.

7. The system of claim 1 wherein the first output electrical signal is a function of the operational parameter of the light-emitting device, and wherein the controller is further adapted to:
at an earlier time previous to said extracting of the operational parameter of the light-emitting device, vary a third input electrical signal provided to the pixel and measure a third output electrical signal of the pixel in response thereto, until reaching a final third input electrical signal provided to the pixel when the third output electrical signal equals the predetermined electrical signal, wherein one of the predetermined electrical signal and the third output electrical signal is a function of the operational parameter of the light-emitting device at the earlier time, and extract the value of the operational parameter of the light-emitting device at the earlier time with use of the final third input electrical signal; and
extract the value of the operational parameter of the light-emitting device with use of the final third input electrical signal provided to the pixel and the final first input electrical signal provided to the pixel and the value of the operational parameter of the light-emitting device at the earlier time.

8. The system of claim 7 wherein only one of the predetermined electrical signal and the third output electrical signal is a function of the operational parameter of the light-emitting device at the earlier time.

9. The system of claim 1 , wherein the operational parameter is the operational voltage V OLED of the light-emitting device.

10. A method of determining a value of an operational parameter of a light-emitting device 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 the light-emitting device of the pixel as a function of a programming of the storage capacitor, the method comprising:
varying a first input electrical signal provided to the pixel and measuring a first output electrical signal of the pixel in response thereto, until reaching a final first input electrical signal provided to the pixel when the first output electrical signal equals a predetermined electrical signal, wherein one of the first output electrical signal and the predetermined electrical signal is a function of the operational parameter of the light-emitting device; and
extracting the value of the operational parameter of the light-emitting device with use of the final first input electrical signal provided to the pixel.

11. The method of claim 10 wherein the predetermined electrical signal is a predetermined known reference current and the first output electrical signal is a first output current which is a function of the operational parameter of the light-emitting device.

12. The method of claim 10 wherein the predetermined electrical signal is a previously measured second output electrical signal, the second output electrical signal previously output from said pixel in response to a second input electrical signal provided to the pixel.

13. The method of claim 12 wherein said extracting comprises extracting the operational parameter of the light-emitting device with use of the second input electrical signal provided to the pixel.

14. The method of claim 13 wherein said extracting comprises extracting the operational parameter of the light-emitting device from a difference between the final first input electrical signal provided to the pixel and the second input electrical signal provided to the pixel.

15. The method of claim 12 further comprising:
prior to said varying the first input electrical signal provided to the pixel, setting the second input electrical signal provided to the pixel to generate said measured second output electrical signal, wherein only one of the first output electrical signal and the predetermined electrical signal is a function of the operational parameter of the light-emitting device.

16. The method of claim 10 wherein the first output electrical signal is a function of the operational parameter of the light-emitting device, the method further comprising:
at an earlier time previous to said extracting of the operational parameter of the light-emitting device, varying a third input electrical signal provided to the pixel and measuring a third output electrical signal of the pixel in response thereto, until reaching a final third input electrical signal provided to the pixel when the third output electrical signal equals the predetermined electrical signal, wherein one of the predetermined electrical signal and the third output electrical signal is a function of the operational parameter of the light-emitting device at the earlier time, and extracting the value of the operational parameter of the light-emitting device at the earlier time with use of the final third input electrical signal provided to the pixel; and
extracting the value of the operational parameter of the light-emitting device with use of the final third input electrical signal provided to the pixel and the final first input electrical signal provided to the pixel and the value of the operational parameter of the light-emitting device at the earlier time.

Assignees

• Ignis Innovation Inc

Inventors

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

Classifications

• 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

• G09G3/3233 Primary

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

• G09G2320/045

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

• G09G2320/0233

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

• G09G2320/043

  Preventing or counteracting the effects of ageing · CPC title