DAC Reset Circuit for OLED Gray Scale Gradient Elimination
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Solution Overview
Problem
The performance of gray scales in current driving displays is degraded by parasitical capacitors and resistors, particularly evident when transitioning from high to low gray scales, leading to a gradient phenomenon that affects the display's ability to show the lowest gray scale accurately.
Innovation Solution
Incorporating a reset circuit at the output terminal of a digital-to-analog current converter to reset the voltage potential to the lowest gray scale potential, ensuring proper charging and discharging of parasitical capacitors and resistors, thereby enhancing the display's ability to show the lowest gray scale without gradient issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a digital-to-analog current converter is used to drive OLED pixels, then the display can achieve high resolution and large-scale panel requirements, but parasitical capacitors and resistors in the wiring degrade the gray scale performance
Solution Approach 1:
The patent extracts the harmful effect of parasitical capacitors by introducing a reset circuit that actively compensates for their charge storage effect. The reset circuit separates the parasitical capacitor's influence from the desired signal by providing a dedicated discharge path, thereby removing its harmful impact on gray scale performance.
Solution Approach 2:
The reset circuit acts as an intermediary mechanism between the DAC output and the pixel. It mediates the effect of parasitical capacitors by providing a controlled discharge path that prevents them from accumulating charge and degrading gray scale performance.
2Speed
If the display shows low gray scale immediately after high gray scale, then the transition is rapid, but the parasitical capacitors cause gradient phenomenon that degrades the lowest gray scale performance
Solution Approach 1:
The reset circuit performs preliminary action by continuously monitoring and readying the discharge path for parasitical capacitors. When transitioning from high to low gray scale, the reset circuit is already prepared to immediately discharge accumulated charge, preventing the gradient phenomenon before it can degrade the lowest gray scale display.
Solution Approach 2:
The reset circuit implements feedback by continuously monitoring the voltage potential at the DAC output and adjusting its discharge action accordingly. This feedback mechanism ensures that parasitical capacitors are discharged at the appropriate moment during transitions, maintaining accurate gray scale display regardless of transition speed.
3Device complexity
If the end of the DAC stores electric charge due to parasitical capacitors, then the circuit remains simple, but the stored charge prevents accurate display of low gray scale after high gray scale
Solution Approach 1:
The reset circuit applies local quality by providing a targeted discharge path specifically for parasitical capacitors at the DAC output, without affecting the overall simplicity of the circuit architecture. The solution is localized to the specific problem area (DAC output node) rather than requiring a complete circuit redesign.
Data Source
AI summary
A data driving circuit, used to drive display devices, comprises a digital-to-analog current converter (DAC), a reset circuit connected to the output terminal of the DAC for resetting the output potential of the DAC to a specific gray scale potential, and plural stages of data driver units connected to the output terminal of the DAC and the reset circuit to drive data lines of the display devices. Each of the data driver units comprises a sample-holding circuit and a control circuit.