SYSTEM AND METHODS FOR EXTRACTING CORRELATION CURVES FOR AN ORGANIC LIGHT EMITTING DEVICE

• US 20160307498A1
• Filed: 06/30/2016
• Published: 10/20/2016
• Est. Priority Date: 02/04/2010
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chaji, Gholamreza
• Granted Patent: US 10,163,401 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2300/0413 Details of dummy pixels or dummy lines in flat panels
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A method of compensating for efficiency degradation of an OLED in an array-based semiconductor device having arrays of pixels that include OLEDs, including determining for a plurality of operating conditions interdependency curves relating changes in an electrical operating parameter of said OLEDs and the efficiency degradation of said OLEDs, the plurality of operating conditions can include temperature or initial device characteristics as well as stress conditions to more completely determine interdependency curves for a wide variety of OLEDs. In some cases interdependency curves are updated remotely after fabrication of the array-based device. Some embodiments utilize degradation-time curves and methods which do not require storage of stress history.

Claims

1. A method of compensating for efficiency degradation of an organic light emitting device (OLED) in an array-based semiconductor device having arrays of pixels that include OLEDs, said method comprising:

determining for a plurality of operating conditions interdependency curves relating changes in an electrical operating parameter of said OLEDs and the efficiency degradation of said OLEDs in said array-based semiconductor device, the plurality of operating conditions comprising at least two operating condition types;

determining at least one operating condition for the OLED in respect of the at least two operating condition types;

measuring the electrical operating parameter of said OLED;

determining an efficiency degradation of said OLED using said interdependency curves, said at least one operation condition for the OLED, and said measured electrical operating parameter;

determining a correction factor for the OLED with use of said efficiency degradation;

and

compensating for said efficiency degradation with use of said correction factor.

2. The method of claim 1 wherein the at least two operating condition types comprise a temperature condition and a stress condition, and the at least one operation condition for the OLED comprises a temperature history and a stress history.

3. The method of claim 2 wherein each interdependency curve has an associated temperature condition and a stress condition, and wherein determining an efficiency degradation comprises:

determining at least one temperature associated interdependency curve with use of said temperature history; and

determining from said at least one temperature associated interdependency curve and said stress history and said measured electrical operating parameter, the efficiency degradation of the OLED.

4. The method of claim 2 wherein each interdependency curve has an associated effective stress history as a function of at least the temperature condition and a stress condition, and wherein determining an efficiency degradation comprises:

determining an effective stress history for the OLED with use of the temperature history and the stress history; and

determining from said interdependency curves and said effective stress history and said measured electrical operating parameter the efficiency degradation of the OLED.

5. The method of claim 3 wherein after the correction factor for the OLED has been determined, a start point associated with the interdependency curves is reset, after which the temperature history and the stress history only comprise temporary histories.

6. The method of claim 4 wherein after the correction factor for the OLED has been determined, a start point associated with the interdependency curves is reset, after which the temperature history and the stress history only comprise temporary histories.

7. The method of claim 1 wherein the at least two operating condition types comprise a temperature condition and an initial device characteristic condition, and the at least one operation condition for the OLED comprises a temperature history and initial device characteristics.

8. The method of claim 7 wherein each interdependency curve has an associated initial device characteristic condition and a stress condition, and wherein determining an efficiency degradation comprises:

determining at least one initial device characteristic associated interdependency curve with use of said initial device characteristics; and

determining from said at least one initial device characteristic associated interdependency curve and said stress history and said measured electrical operating parameter, the efficiency degradation of the OLED.

9. The method of claim 8, wherein determining for a plurality of operating conditions interdependency curves comprises:

extracting initial characteristics for each of a plurality of test OLEDs;

repeatedly subjecting the test OLEDs to different stress conditions until all test OLEDs are measured; and

extracting interdependency curves for said test OLEDs and storing said interdependency curves such that each interdependency curve is associated with at least one stress condition and an initial device characteristic condition.

10. The method according to claim 9 further comprising:

updating remotely a set of interdependency curves stored with the array-based semiconductor device with a set of prepared interdependency curves from a remote interdependency curve library at least twice after fabrication of the array-based semiconductor device.

11. The method according to claim 10, wherein the updating remotely occurs at least twice including at the time of at least two of shipping the array-based semiconductor device to the manufacturer, integrating the array-based semiconductor device into a product, and operation of the array-based semiconductor device at a consumer site.

12. The method of claim 1, wherein determining the efficiency degradation comprises:

initializing a total effective stress time value;

sampling brightness data for said OLED;

calculating an effective stress time corresponding to said sampling for at least one given reference stress level;

updating the total effective stress time for said OLED based on the at least one given stress level;

determining whether to sample more brightness data; and

in a case no more brightness data are to be sampled, updating the efficiency degradation with use of the total effective stress, and the interdependency curves.

13. The method of claim 12, wherein determining whether to sample more brightness data comprises comparing the total effective stress time with a predetermined threshold.

14. The method of claim 1, wherein determining the efficiency degradation comprises:

initializing a total change in degradation factor;

sampling brightness data for said OLED;

calculating a change in degradation corresponding to the sampled brightness;

updating the total change in degradation factor for said OLED;

determining whether to sample more brightness data; and

in a case no more brightness data are to be sampled, updating the efficiency degradation with use of the total change in degradation factor, and the interdependency curves.

15. The method of claim 14, wherein determining whether to sample more brightness data comprises comparing the total change in degradation factor with a predetermined change in degradation threshold.

16. A method of compensating for efficiency degradation of an organic light emitting device (OLED) in an array-based semiconductor device having arrays of pixels that include OLEDs, said method comprising:

determining for a plurality of operating conditions at least one degradation-time curve relating changes in a stress time parameter associated with said OLEDs and the efficiency degradation of said OLEDs in said array-based semiconductor device, the plurality of operating stress conditions comprising at least two operating stress condition types;

measuring at least one operating stress condition for the OLED in respect of the at least two operating stress condition types;

determining an efficiency degradation of said OLED using said at least one degradation-time curve, and said at least one operating stress condition for the OLED;

determining a correction factor for the OLED with use of said efficiency degradation;

and

compensating for said efficiency degradation with use of said correction factor.

17. The method of claim 16 wherein after the correction factor for the OLED has been determined, a start point associated with the at least one degradation-time curve is reset.

18. The method of claim 16, wherein determining the efficiency degradation comprises:

initializing a total effective stress time value;

sampling brightness data for said OLED;

calculating an effective stress time corresponding to said sampling for at least one given reference stress level;

updating the total effective stress time for said OLED based on the at least one given stress level;

determining whether to sample more brightness data; and

in a case no more brightness data are to be sampled, updating the efficiency degradation with use of the total effective stress, and the at least one degradation-time curve.

19. The method of claim 16, wherein determining the efficiency degradation comprises:

initializing a total change in degradation factor;

sampling brightness data for said OLED;

calculating a change in degradation corresponding to the sampled brightness;

updating the total change in degradation factor for said OLED;

determining whether to sample more brightness data; and

in a case no more brightness data are to be sampled, updating the efficiency degradation with use of the total change in degradation factor, and the at least one degradation-time curve.