OLED voltage driver with current-voltage compensation

1. An 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;

sensing circuitry coupled to the pixel and configured to sense a set of current-voltage values of the pixel;

reference sensing circuitry coupled to the reference pixel and configured to sense a reference set of current-voltage values of the reference pixel; and

processing circuitry communicatively coupled to the display, wherein the processing circuitry is configured to perform operations comprising:

generating a current-voltage curve from the set of current-voltage values;

generating a reference current-voltage curve from the reference set of current-voltage values;

determining a set of degradation ratios based at least in part on the set of current-voltage values and the reference set of current-voltage values;

reconstructing the reference current-voltage curve based at least in part on the set of degradation ratios to produce a reconstructed reference current-voltage curve;

determining a set of gamma tap points for respective brightness settings of a plurality of brightness settings of the display based at least in part on the reconstructed reference current-voltage curve; and

performing gray tracking on the set of gamma tap points to compensate for the set of degradation ratios.

2. The electronic device of claim 1 , wherein the current-voltage curve is interpolated from a first set of current values and a first set of voltage values, each associated with one of the brightness settings of the plurality of brightness settings.

3. The electronic device of claim 2 , wherein performing gray tracking comprises:

determining a first voltage level corresponding to a respective gray level associated with each gamma tap point of the set of gamma tap points based on the reconstructed reference current-voltage curve; and

for respective gamma tap points of the set of gamma tap points, upon determining that a first interpolated voltage level associated with a first gray level of a first gamma tap point of the set of gamma tap points is closer to the first voltage level than a second interpolated voltage level associated with the respective gray level, mapping the first interpolated voltage level to the respective gray level to generate a set of voltage values.

4. The electronic device of claim 3 , wherein the gray tracking comprises:

for each respective gamma tap point of the set of gamma tap points, upon determining that the second interpolated voltage level is closer to the first voltage level than the first interpolated voltage level, mapping the second interpolated voltage level to the respective gray level to generate the set of voltage values.

5. The electronic device of claim 4 , wherein the operations comprise:

causing the pixel to be driven based at least in part on the set of voltage values.

6. The electronic device of claim 4 , comprising:

reference array control circuitry coupled to the reference array and configured to convert each voltage value of the set of voltage values to a gray level, wherein the operations comprise:

compensating for voltage degradation in the set of voltage values; and

causing the pixel to be driven based at least in part on the respective gray level.

7. The electronic device of claim 6 , wherein compensating for voltage degradation comprises:

determining a set of voltage differences based on the current-voltage curve and the reference current-voltage curve;

applying one or more voltage compensation values to the pixel based on the set of voltage differences;

determining one or more current compensation values based on the one or more voltage compensation values;

limiting the one or more current compensation values below a visibility threshold; and

driving the pixel based at least in part on the one or more limited current compensation values.

8. The electronic device of claim 7 , comprising:

current step limiter circuitry configured to limit the one or more current compensation values below the visibility threshold.

9. The electronic device of claim 1 , wherein the sensing circuitry is configured to sense one or more current values of the pixel and wherein the reference sensing circuitry is configured to sense one or more reference current values of the reference pixel.

10. An electronic device comprising:

an electronic display comprising:

an active array comprising a first pixel;

a first digital-to-analog converter configured to drive the first pixel;

first sensing circuitry configured to sense a first set of current-voltage characteristics of the first pixel;

a reference array comprising a second pixel;

a second digital-to-analog converter configured to drive the second pixel; and

second sensing circuitry configured to sense a second set of current-voltage characteristics of the second pixel; and

processing circuitry communicatively coupled to the electronic display, wherein the processing circuitry is configured to perform operations comprising:

generating a current-voltage curve from the first set of current-voltage characteristics;

generating a reference current-voltage curve from the second set of current-voltage characteristics;

determining a set of degradation ratios based at least in part on the first set of current-voltage characteristics and the second set of current-voltage characteristics;

reconstructing the reference current-voltage curve based at least in part on the set of degradation ratios to produce a reconstructed reference current-voltage curve;

determining a set of gamma tap points for each brightness setting of a plurality of brightness settings of the electronic display based at least in part on the reconstructed reference current-voltage curve; and

programming the set of gamma tap points into the first digital-to-analog converter for driving the first pixel.

11. The electronic display of claim 10 , wherein the current-voltage curve is interpolated from a first set of current values and a first set of voltage values, each associated with one of the brightness settings of the plurality of brightness settings.

12. The electronic display of claim 10 , comprising:

performing gray tracking on the set of gamma tap points, comprising:

determining a first voltage level corresponding to a respective gray level associated with each gamma tap point of the set of gamma tap points based at least in part on the reconstructed reference current-voltage curve; and

for each respective gamma tap point of the set of gamma tap points, upon determining that a first interpolated voltage level associated with a first gray level of a first gamma tap point of the set of gamma tap points is closer to the first voltage level than a second interpolated voltage level associated with the respective gray level, mapping the first interpolated voltage level to the respective gray level to generate a set of voltage values.

13. The electronic display of claim 12 , wherein the gray tracking comprises:

for each respective gamma tap point of the set of gamma tap points, upon determining that the second interpolated voltage level is closer to the first voltage level than the first interpolated voltage level, mapping the second interpolated voltage level to the respective gray level to generate the set of voltage values.

14. The electronic display of claim 13 , wherein the set of gamma tap points programmed into the first digital-to-analog converter are based at least in part on the set of voltage values.

15. The electronic display of claim 13 , the operations comprising:

compensating for voltage degradation in the set of voltage values;

converting each voltage value of the set of voltage values to a gray level; and

driving the first pixel based at least in part on the gray levels.

16. The electronic display of claim 15 , wherein compensating for voltage degradation comprises:

determining a set of voltage differences based at least in part on the current-voltage curve and the reference current-voltage curve;

applying one or more voltage compensation values to the first pixel based at least in part on the set of voltage differences;

determining one or more current compensation values based at least in part on the one or more voltage compensation values;

limiting the one or more current compensation values below a visibility threshold; and

driving the first pixel based at least in part on the one or more limited current compensation values.

17. The electronic display of claim 16 , further comprising:

current step limiter circuitry configured to limit the one or more current compensation values below the visibility threshold.

18. A method comprising:

sensing, via active array sensing circuitry, a set of current-voltage values of a pixel of an active array of a display;

sensing, via reference array sensing circuitry, a reference set of current-voltage values of a reference pixel of a reference array;

determining, via processing circuitry, a set of degradation ratios based at least in part on the set of current-voltage values and the reference set of current-voltage values;

reconstructing, via the processing circuitry, a reference current-voltage curve based at least in part on the degradation ratios to produce a reconstructed reference current-voltage curve;

determining, via the processing circuitry, a set of gamma tap points for each brightness setting of the display based at least in part on the reconstructed reference current-voltage curve; and

performing, via the processing circuitry, gray tracking on the set of gamma tap points to compensate for the set of degradation ratios.

19. The method of claim 18 , further comprising:

determining, via the processing circuitry, a first voltage level corresponding to a respective gray level associated with each gamma tap point of the set of gamma tap points based at least in part on the reconstructed reference current-voltage curve; and

for each respective gamma tap point of the set of gamma tap points, upon determining that a first interpolated voltage level associated with a first gray level of a first gamma tap point of the set of gamma tap points is closer to the first voltage level than a second interpolated voltage level associated with the respective gray level, mapping, via the processing circuitry, the first interpolated voltage level to the respective gray level to generate a set of voltage values.

20. The method of claim 19 , further comprising:

for each respective gamma tap point of the set of gamma tap points, upon determining that the second interpolated voltage level is closer to the first voltage level than the first interpolated voltage level, mapping, via the processing circuitry, the second interpolated voltage level to the respective gray level to generate the set of voltage values.