OLED Display Hysteresis Compensation Using Test Pixels
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Solution Overview
Problem
Organic light emitting display devices face luminance non-uniformity due to hysteresis characteristics in driving transistors, which can lead to afterimages and require separate compensation for panel deviations, and existing solutions accelerate transistor degradation.
Innovation Solution
Incorporating a display panel with active pixels and test pixels in a non-display region, where test pixels measure sensing currents to obtain hysteresis characteristic values, allowing for compensation of input image data based on these values to reduce afterimages and panel deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If driving transistors are initialized to an on-bias state before each frame, then luminance non-uniformity caused by hysteresis characteristics is reduced, but transistor degradation is accelerated
Solution Approach 1:
The patent applies preliminary action by initializing driving transistors to an on-bias state before the display period to compensate for hysteresis effects. This preliminary initialization ensures that all transistors start from a known state, reducing luminance non-uniformity without requiring continuous on-state maintenance during non-display periods, thus extending transistor lifespan.
2Manufacturing precision
If driving transistors are turned on every frame for initialization, then hysteresis compensation is achieved, but separate compensation operations for panel deviation are required
Solution Approach 1:
The patent merges hysteresis compensation and panel deviation compensation into a single integrated initialization operation. By measuring sensing currents during the on-bias state initialization and using these measurements for both hysteresis characterization and panel deviation compensation, the patent eliminates the need for separate compensation operations, reducing device complexity while maintaining comprehensive compensation.
3Manufacturing precision
If test pixels are added in the non-display region for measuring hysteresis characteristics, then afterimage reduction is achieved, but device structure becomes more complex
Solution Approach 1:
The patent extracts the hysteresis measurement function from the display region by placing test pixels in the non-display region. This extraction allows dedicated hysteresis characterization without interfering with the display function of active pixels. The test pixels are selectively activated only during measurement periods, adding minimal structural complexity while enabling accurate afterimage reduction through hysteresis compensation.
Data Source
AI summary
An organic light emitting display device includes a display panel including a plurality of active pixels in a display region, and a plurality of test pixels in a non-display region, a panel driver configured to provide the test pixels with data signals corresponding to a plurality of gray levels, and to drive the display panel, a readout circuit configured to measure sensing currents flowing through the test pixels, and a controller configured to obtain hysteresis characteristic values of the test pixels based on the sensing currents, to generate output image data by compensating input image data for the active pixels based on the hysteresis characteristic values of the test pixels to which the active pixels are mapped, and to control the panel driver to display an image based on the output image data.