Pixel Circuit Bias Adjustment for Mixed Refresh Rate Displays
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Solution Overview
Problem
Existing display panels face challenges in designing pixel circuits to accommodate different display functions or effects, such as those required for game images versus movie images or text and time information, due to issues with threshold voltage drift in drive transistors caused by varying data refresh rates and bias states.
Innovation Solution
The implementation of a bias adjustment module in pixel circuits that adjusts the bias state of drive transistors through control signals, optimizing the bias adjustment duration based on the data refresh rate and mode of operation to counteract threshold voltage drift, thereby facilitating differential design for varying display functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixel circuits are designed with different functions for different display scenarios, then the adaptability of the display panel is improved, but the device complexity increases due to differential pixel circuit designs
Solution Approach 1:
The pixel circuit is designed with a universal structure that can perform multiple display functions (game images, movie images, text, time information) by dynamically adjusting the bias state of the drive transistor through a bias adjustment module, rather than designing separate circuits for each function
Solution Approach 2:
The bias adjustment module dynamically changes the bias state of the drive transistor based on different display scenarios and refresh rates, allowing a single pixel circuit design to adapt to different functions through real-time parameter adjustment
2Manufacturing precision
If the data refresh rate is increased for high-quality display, then the display quality is improved, but the threshold voltage drift in drive transistors worsens due to extended bias adjustment duration
Solution Approach 1:
The bias adjustment is performed periodically at specific timing points within each refresh cycle, allowing the drive transistor to be adjusted at controlled intervals rather than continuously, which prevents excessive bias adjustment duration even at high refresh rates
Solution Approach 2:
The bias adjustment module changes the bias state parameter of the drive transistor based on the refresh rate and display mode, optimizing the balance between display quality and threshold voltage stability by adjusting parameters dynamically
3Ease of operation
If a fixed bias adjustment duration is used for all pixel circuits, then the ease of operation is improved, but the manufacturing precision deteriorates due to threshold voltage drift in low refresh rate circuits
Solution Approach 1:
The bias adjustment duration is customized for different pixel circuits based on their specific refresh rates and display functions, with low refresh rate circuits receiving longer adjustment durations and high refresh rate circuits receiving shorter durations, optimizing each circuit's threshold voltage control
Data Source
AI summary
Provided are a display panel. When a bias adjustment control signal is an effective pulse signal, a bias adjustment module is on and provides a bias adjustment signal for a drive transistor. The data refresh rate of a first pixel circuit is a first frequency F1. The data refresh rate of a second pixel circuit is a second frequency F2. F1≠F2. A data refresh period of the first pixel circuit includes R1 image refresh frames. A data refresh period of the second pixel circuit includes R2 image refresh frames. The sum of time durations of effective pulses of the bias adjustment control signal is Ws1 in the data refresh period of the first pixel circuit. The sum of time durations of effective pulses of the bias adjustment control signal is Ws2 in the data refresh period of the second pixel circuit. Ws1/R1≠Ws2/R2.