OLED voltage driver with current-voltage compensation

Patent metadata

Field	Value
Publication number	US-10636359-B2
Application number	US-201816132324-A
Country	US
Kind code	B2
Filing date	Sep 14, 2018
Priority date	Sep 21, 2017
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A mobile electronic device includes a display having an active array and a reference array. The active array includes a pixel and the reference array includes a reference pixel. The mobile electronic device also includes processing circuitry communicatively coupled to the display. The processing circuitry drives the pixel based at least in part on a degraded current-voltage relationship of the pixel, a reference current-voltage relationship of the reference pixel, and an aged current-voltage relationship.

First claim

What is claimed is:

1. A mobile electronic device comprising:
a display comprising an active array and a reference array, wherein the active array comprises a pixel and the reference array comprises a reference pixel; and
processing circuitry communicatively coupled to the display, wherein the processing circuitry is configured to drive the pixel based at least in part on a degraded current-voltage relationship of the pixel, a reference current-voltage relationship of the reference pixel, and an aged current-voltage relationship, wherein the aged current-voltage relationship is determined based on a stress applied to one or more pixels of an additional display, and wherein the aged current-voltage relationship is stored in a storage component accessible to the processing circuitry.

2. The mobile electronic device of claim 1 , wherein the aged current-voltage relationship is based at least in part on a periphery pixel of an additional active array of the additional display.

3. The mobile electronic device of claim 1 , wherein the processing circuitry comprises one or more look-up tables configured to store a set of degraded current-voltage values of the pixel associated with the degraded current-voltage relationship.

4. The mobile electronic device of claim 3 , wherein the processing circuitry comprises a voltage comparator circuit configured to generate the degraded current-voltage relationship based at least in part on the set of degraded current-voltage values.

5. The mobile electronic device of claim 3 , wherein the processing circuitry comprises a voltage comparator circuit configured to:
determine a set of degradation ratios based at least in part on the set of degraded current-voltage values, the reference current-voltage relationship, and the aged current-voltage relationship; and
generate the degraded current-voltage relationship based at least in part on the set of degradation ratios.

6. The mobile electronic device of claim 5 , wherein each degradation ratio of the set of degradation ratios is based at least in part on:
a first difference in current between a respective reference current-voltage value associated with the reference current-voltage relationship and a respective degraded current-voltage value of the set of degraded current-voltage values; and
a second difference in current between the respective reference current-voltage value and a respective degraded current-voltage value of the set of degraded current-voltage values and an aged current-voltage value associated with the aged current-voltage relationship.

7. A method comprising:
extrapolating, via processing circuitry, a set of extrapolated degradation ratios based at least in part on a set of received degradation ratios;
determining, via the processing circuitry, a first extrapolated current-voltage value based at least in part on a first extrapolated degradation ratio of the set of extrapolated degradation ratios comprising a first current less than a reference current;
determining, via the processing circuitry, a second extrapolated current-voltage value based at least in part on a second extrapolated degradation ratio of the set of extrapolated degradation ratios comprising a second current greater than the reference current;
generating, via the processing circuitry, an extrapolated current-voltage curve between the first extrapolated current-voltage value and the second extrapolated current-voltage value;
determining, via the processing circuitry, a compensation voltage based at least in part on the extrapolated current-voltage curve and the reference current; and
instructing, via the processing circuitry, a digital-to-analog converter to drive a pixel using the compensation voltage.

8. The method of claim 7 , comprising converting the set of extrapolated degradation ratios to a set of extrapolated current-voltage values, wherein the set of extrapolated current-voltage values comprises the first extrapolated current-voltage value and the second extrapolated current-voltage value.

9. The method of claim 8 , wherein the first current is the closest current among currents of the set of extrapolated current-voltage values less than the reference current.

10. The method of claim 8 , wherein the second current is the closest current among currents of the set of extrapolated current-voltage values greater than the reference current.

11. The method of claim 7 , wherein the reference current is configured to be produced at a reference pixel of a reference array when a reference voltage is supplied.

12. The method of claim 11 , wherein a diode of the reference pixel is configured to emit a target grey level when the reference voltage is supplied to the pixel.

13. The method of claim 12 , wherein instructing, via the processing circuitry, the digital-to-analog converter to drive the pixel using the compensation voltage approximately produces the target grey level at a second diode of the pixel.

14. The method of claim 11 , wherein driving, via the processing circuitry, the pixel using the compensation voltage is configured to approximately produce the reference current at the pixel.

15. The method of claim 7 , wherein the extrapolated current-voltage curve is linear.

16. A mobile electronic device comprising:
a display comprising an active array, a reference array, and a digital-to-analog converter, wherein the active array comprises a pixel; and;
processing circuitry communicatively coupled to the display, wherein the processing circuitry comprises:
a current-voltage compensation circuit configured to:
receive a plurality of degradation ratios, an input voltage, and an input reference current; and
output a compensation voltage based at least in part on the plurality of degradation ratios, the input voltage, and the input reference current,

wherein the digital-to-analog converter drives the pixel based at least in part on the compensation voltage.

17. The mobile electronic device of claim 16 , wherein the processing circuitry comprises a gamma-to-voltage converter configured to convert an input gray level to the input voltage.

18. The mobile electronic device of claim 17 , wherein the processing circuitry comprises a voltage-to-gamma converter configured to convert the compensation voltage to an output gray level.

19. The mobile electronic device of claim 18 , wherein a diode of the pixel is configured to approximately emit the input gray level when the digital-to-analog converter drives the pixel to output the output gray level.

20. The mobile electronic device of claim 16 , wherein the processing circuitry comprises a reference array look-up table configured to store the input voltage and the input reference current.

Assignees

• Apple Inc

Inventors

• Zhang Sheng
• Hou Yunhui
• Wang Chaohao

Classifications

• G09G2320/0233

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• G09G2310/027

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• G09G2320/041

  Temperature compensation · CPC title

• G09G2320/0673

  for control of gamma adjustment, e.g. selecting another gamma curve · CPC title

• G09G2320/045

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