System and methods for extracting correlation curves for an organic light emitting device

A method for determining a characterization correlation curve for aging compensation for an organic light emitting device (OLED) based pixel in a display comprising:

• applying a first stress condition to a reference device;
• storing a baseline optical characteristic and a baseline electrical characteristic of the reference device;
• periodically measuring an output voltage based on a reference current to determine an electrical characteristic of the reference device;
• periodically measuring the luminance of the reference pixel to determine an optical characteristic of the reference device;
• determining a characterization correlation curve corresponding to the first stress condition based on the baseline optical and electrical characteristics and the determined electrical and optical characteristics of the reference device;
• storing the characterization correlation curve corresponding to the first stress condition
• applying a second stress condition to a second reference pixel having an OLED;
• storing a baseline optical characteristic and a baseline electrical characteristic of the second reference pixel;
• periodically measuring an output voltage based on a reference current to determine an electrical characteristic of the second reference pixel;
• periodically measuring the luminance of the reference pixel to determine an optical characteristic of the second reference pixel;
• determining a second characterization correlation curve corresponding to the second stress condition based on the baseline optical and electrical characteristics and the determined electrical and optical characteristic of the second reference pixel;
• storing the second characterization correlation curve corresponding to the second stress condition;
• determining a stress condition on an active pixel on a display, the stress condition falling between the first and second stress condition;
• determining a compensation factor as a function of the first and second characterization correlation curves corresponding to the first and second reference pixels;
• and
• modifying a programming voltage by the compensation factor to the active pixel to compensate for aging effects;
• wherein the compensation factor is determined based on a previous determined stress condition on the active pixel multiplied by an average compensation factor, the average compensation factor being a function of the difference between the first and second characterization correlation curves.

A display system for compensating of aging effects, the display system comprising:

• a plurality of active pixels displaying an image, the active pixels each including a drive transistor and an organic light emitting diode (OLED);
• a memory storing a first characterization correlation curve for a first predetermined stress condition and a second characterization correlation curve for a second predetermined stress condition;
• and
• a controller coupled to the plurality of active pixels, the controller determining a stress condition on one of the active pixels, the stress condition falling between the first and second predetermined stress conditions, and determining a compensation factor to apply to a programming voltage based on the characterization correlation curves of the first and second stress conditions.

A display system for compensating of aging effects, the display system comprising:

• a plurality of active pixels displaying an image, the active pixels each including a drive transistor and an organic light emitting diode (OLED);
• a memory storing a first characterization correlation curve for a first predetermined stress condition and a second characterization correlation curve for a second predetermined stress condition;
• a controller coupled to the plurality of active pixels, the controller determining a stress condition on one of the active pixels, the stress condition falling between the first and second predetermined stress conditions, and determining a compensation factor to apply to a programming voltage based on the characterization correlation curves of the first and second stress conditions;
• a first reference pixel including a drive transistor and an OLED;
• a second reference pixel including a drive transistor and an OLED;
• and
• wherein the first characterization correlation curve is determined based on electrical and optical characteristics determined from the first reference pixel under the first stress condition and the second characterization correlation curve determined based on electrical and optical characteristics determined from the second reference pixel under the second stress condition.

A method of determining a characterization correlation curve for an OLED device in a display, the method comprising:

• storing a first characterization correlation curve based on a first group of reference pixels at a predetermined high stress condition;
• storing a second characterization correlation curve based on a second group of reference pixels at a predetermined low stress condition;
• determining a stress level of an active pixel falling between the high and low stress conditions;
• determining a compensation factor based on the stress on the active pixel, the compensation factor based on the stress on the active pixel and the first and second characterization correlation curve;
• and
• adjusting a programming voltage to the active pixel based on the compensation factor.

A display system for compensating for aging effects, the display system comprising:

• a plurality of active pixels for displaying an image, the active pixels each including a drive transistor and an organic light emitting diode (OLED);
• a memory storing a first characterization correlation curve for a first predetermined stress condition and a second characterization correlation curve for a second predetermined stress condition;
• and
• a controller coupled to the plurality of active pixels, the controller
• determining a stress condition of a selected one of the active pixels, the stress condition falling between the first and second predetermined stress conditions, and
• determining a compensation factor to apply to a programming voltage for said selected active pixel, based on a weighted moving average of said first and second characterization correlation curves of said first and second predetermined stress conditions.

A display system for compensating for aging effects, the display system comprising:

• a plurality of active pixels displaying an image, the active pixels each including a drive transistor and an organic light emitting diode (OLED);
• a memory storing a first characterization correlation curve for a first predetermined stress condition and a second characterization correlation curve for a second predetermined stress condition;
• and
• a controller coupled to the plurality of active pixels, the controller
• determining a stress condition of a selected one of the active pixels, the stress condition falling between the first and second predetermined stress conditions, and
• determining a compensation factor to apply to a programming voltage for said selected active pixel, based on a weighted moving average of said first and second characterization correlation curves of said first and second predetermined stress conditions;
• wherein said stress condition for an active pixel at a time ti is St(ti)=(St(ti−1)*kavg+L(ti))/(kavg+1), where St(ti−1) is the stress condition at a previous time, kavg is a moving average constant, L(ti) is the measured luminance of the active pixel at time ti.

A display system for compensating for aging effects, the display system comprising:

• a plurality of active pixels displaying an image, the active pixels each including a drive transistor and an organic light emitting diode (OLED);
• a memory storing a first characterization correlation curve for a first predetermined stress condition and a second characterization correlation curve for a second predetermined stress condition;
• and
• a controller coupled to the plurality of active pixels, the controller
• determining a stress condition of a selected one of the active pixels, the stress condition falling between the first and second predetermined stress conditions,
• determining a compensation factor to apply to a programming voltage for said selected active pixel, based on a weighted moving average of said first and second characterization correlation curves of said first and second predetermined stress conditions, and
• determining the two predetermined stress conditions closest to said determined stress condition of said selected one of the active pixels and attendant characteristic data obtained from said reference pixels at said closest two predetermined stress conditions.