Color-Specific Threshold Correction in OLED Pixel Circuits
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Solution Overview
Problem
Conventional organic EL displays face challenges in achieving high image quality and low power consumption due to the trade-off between image quality and power consumption in threshold correction, particularly for colors like blue and green, where human visual sensitivity varies, leading to noticeable color variations and inefficient power usage.
Innovation Solution
A current-driven display device with pixel circuits differentiated by color, employing initial potential differences and reference voltages tailored to each color to optimize threshold correction, reducing power consumption while maintaining high image quality by adjusting the current flowing through compensation switching elements based on human visual sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large initial potential difference is applied to all pixel circuits for threshold correction, then image quality improves for sensitive colors like blue, but power consumption increases unnecessarily for less sensitive colors like green
Solution Approach 1:
The patent applies different initial potential differences to pixel circuits depending on their display color. Specifically, blue pixel circuits receive a larger initial potential difference (e.g., 5V) to ensure accurate threshold correction for this visually sensitive color, while green pixel circuits receive a smaller initial potential difference (e.g., 3V) since green is less sensitive to chromaticity variations. This local differentiation resolves the contradiction by tailoring the correction strength to the specific visual sensitivity requirements of each color channel.
Solution Approach 2:
The patent changes the parameter of initial potential difference based on the display color of the pixel circuit. By adjusting this parameter according to human visual sensitivity characteristics for different colors, the system achieves optimal threshold correction accuracy for each color while minimizing unnecessary power consumption. This parameter adaptation allows the system to balance image quality and power efficiency.
2Use of energy by moving object
If a small initial potential difference is applied to pixel circuits, then power consumption is reduced, but threshold correction accuracy deteriorates for sensitive colors like blue
Solution Approach 1:
The patent implements local quality by providing enhanced initial potential difference specifically to blue pixel circuits that require higher correction accuracy, while using reduced potential difference for green pixel circuits where high accuracy is less critical. This ensures that power consumption is minimized overall while sensitive color channels receive the necessary correction strength.
Solution Approach 2:
The system dynamically adjusts the initial potential difference parameter based on the display color of each pixel circuit. This parameter change strategy ensures that blue pixel circuits receive sufficient potential difference for accurate threshold correction, while green pixel circuits operate with lower power consumption, thereby resolving the contradiction between power efficiency and correction accuracy.
3Device complexity
If uniform threshold correction is applied to all colors, then circuit design is simplified, but image quality suffers due to noticeable color variations in sensitive regions
Solution Approach 1:
The patent applies local quality by differentiating the threshold correction approach based on display color. Blue pixel circuits undergo more intensive correction with larger initial potential differences to address human visual sensitivity to blue chromaticity variations, while green pixel circuits receive milder correction. This color-specific approach maintains high image quality without significantly complicating the overall circuit design.
Solution Approach 2:
The system changes the correction parameters according to display color to maintain color uniformity. By adjusting the initial potential difference parameter for different colors, the patent achieves uniform image quality across all pixel circuits while accounting for human visual sensitivity characteristics, without requiring fundamentally different circuit architectures.
Data Source
AI summary
A pixel circuit includes an organic EL element, a driving, and a switching provided between the gate and drain of the driving. Upon writing into the pixel circuit, an initial voltage is applied to the gate terminal of the driving, and the switching is temporarily controlled to a conducting state while the driving is in a conducting state, and a data voltage corrected using a gate terminal potential of the driving obtained at that time is applied to the gate terminal of the driving. In at least one embodiment, the human is sensitive to blue chromaticity differences but is insensitive to green chromaticity differences. An initial voltage that increases the accuracy of threshold correction is used for blue pixel circuits, and an initial voltage that reduces power consumption is used for green pixel circuits. By this, a current-driven type color display device with high image quality and low power consumption is provided.