Display Panel Current Sensing for Pixel Deterioration
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Solution Overview
Problem
Display devices face issues with pixels emitting light at undesired luminance due to deterioration of light emitting elements and changes in threshold voltage of driving transistors over time, leading to inconsistent performance.
Innovation Solution
A display device with a sensing controller that measures current through power lines to determine the need for sensing the voltage-current characteristics of light emitting elements and threshold voltages of driving transistors, allowing for independent and reduced frequency sensing based on pixel age and deterioration, thereby adjusting sensing cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing is performed frequently to detect pixel deterioration, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The sensing controller changes the sensing frequency based on the measured current values. When current values indicate normal operation, sensing is performed less frequently. When current values indicate deterioration (deviation from reference values), sensing frequency is increased. This dynamic parameter adjustment resolves the contradiction by adapting sensing intensity to actual pixel condition.
Solution Approach 2:
The system uses the existing drive current through power lines to perform sensing, eliminating the need for separate sensing operations. The current measurer continuously monitors current that is already flowing for light emission, and the sensing controller uses this data to determine when sensing is needed. This self-service approach reduces additional sensing time while maintaining detection accuracy.
2Measurement precision
If sensing is performed for all pixels, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The sensing controller applies different sensing strategies to different pixels based on their individual current measurements. Pixels showing normal current values undergo less frequent or no sensing, while pixels with abnormal current values (indicating deterioration) are sensed more frequently. This localized quality approach ensures accurate detection where needed while maintaining overall display productivity.
Solution Approach 2:
Instead of performing full sensing on all pixels every frame, the system performs partial sensing only on pixels that require it based on current measurement thresholds. The sensing controller determines the minimum necessary sensing action for each pixel, performing excessive sensing only when deterioration is detected, thus balancing measurement precision with productivity.
Data Source
AI summary
A display device includes a display panel, a power supply a current measurer, a controller, and a sensor. The display panel includes pixels connected between first and second power lines. The power supply applies power voltages to the first and second power lines. The current measurer measures a current applied to the display panel from the power supply through the first and second power lines. The controller outputs a first sensing control signal indicating whether to sense a voltage-current characteristic of the light emitting element of at least one of the pixels based on a measured current. The sensor senses the voltage-current characteristic of the light emitting element in response to the first sensing control signal.