Electroluminescent Display Pixel Sensing With VRR Luminance Compensation
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Solution Overview
Problem
Electroluminescent display apparatuses experience luminance deviations between sensing and non-sensing pixels due to variable refresh rate (VRR) driving, where frame frequency varies based on input images, causing temporary light emission stops during sensing periods.
Innovation Solution
The display apparatus includes a display panel with a target pixel for sensing, a data driver supplying specific voltage levels in defined periods, and a sensing circuit to sense electrical characteristics, using a luminance compensation data voltage higher than the display data voltage and a luminance recovery data voltage within a defined range, with controlled periods for image writing, sensing, and recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external compensation technology is used to sense electrical characteristics during image display, then image quality is improved through compensation, but luminance deviation occurs between sensing and non-sensing pixels
Solution Approach 1:
The patent applies preliminary action by performing sensing in a dedicated sensing period before the pixel emits light for display. The sensing operation is prepared and executed in advance during a specific time window, allowing the pixel to be in a known initial state (non-emission state) when sensing occurs, thus eliminating luminance deviation while maintaining sensing accuracy.
2Measurement precision
If sensing is performed in non-emission state to avoid light interference, then sensing accuracy is improved, but luminance deviation occurs between sensing and non-sensing pixels
Solution Approach 1:
The patent implements periodic action by dividing the display cycle into distinct periods: emission periods for normal display and dedicated sensing periods for electrical characteristic measurement. This periodic alternation allows the system to maintain both high sensing accuracy (during sensing periods) and luminance uniformity (by compensating during subsequent compensation periods based on sensed values).
Solution Approach 2:
The patent applies feedback by using the sensed electrical characteristic values to generate compensation values that are applied to subsequent display operations. The sensing circuit measures pixel characteristics, and this information feeds back into the display driver to adjust and compensate for variations, thereby maintaining luminance uniformity across all pixels including those that underwent sensing.
3Adaptability or versatility
If variable refresh rate driving is implemented to adapt to different input images, then adaptability is improved, but luminance deviation worsens due to varying frame frequencies
Solution Approach 1:
The patent applies dynamics by making the sensing and compensation operations adaptive to variable refresh rates. The sensing period is dynamically adjusted based on the actual frame frequency, allowing the system to maintain proper sensing timing regardless of whether the display is running at high or low refresh rates. This dynamic adjustment ensures that sensing accuracy and luminance uniformity are maintained across different operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces luminance deviations between sensing and non-sensing pixels by compensating for luminance loss during temporary light emission stops, ensuring consistent image quality across varying frame frequencies.
Implementation Method 1
Each of pixels of electroluminescent display apparatuses includes a light emitting device self-emitting light
Implementation Method 2
a sensing circuit configured to sense an electrical characteristic of the target pixel based on the sensing data voltage
Data Source
AI summary
An electroluminescent display apparatus includes a display panel including a target pixel for sensing, a data driver configured to supply a display data voltage to the target pixel in an image writing period of one frame, supply a sensing data voltage to the target pixel in a sensing period, supply a luminance compensation data voltage to the target pixel in a sensing line compensation period, and supply a luminance recovery data voltage to the target pixel in a recovery period, and a sensing circuit configured to sense an electrical characteristic of the target pixel based on the sensing data voltage in the sensing period. The image writing period, the sensing period, the sensing line compensation period, and the recovery period may be sequentially arranged. The luminance compensation data voltage may have a voltage level higher than the display data voltage.