Charge-Sharing Control for LCD Power Reduction
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Solution Overview
Problem
Liquid crystal displays (LCDs) experience increased power consumption when displaying primary colors due to frequent switching between high and low voltage levels, which is inefficient and leads to higher energy usage.
Innovation Solution
A charge-sharing controlling method that determines if the display panel is showing a primary color screen and adjusts the activated time of the charge-sharing circuit between sub-pixels with opposite polarities, prolonging the active time when displaying primary colors to reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the data voltage is switched between high and low voltage levels frequently to maintain primary color display, then the color accuracy is improved, but the power consumption is increased
Solution Approach 1:
The charge-sharing circuit is activated in advance during the horizontal blanking period to pre-charge or discharge the liquid crystal capacitors to intermediate voltage levels before the next frame's primary color display. This preliminary action reduces the voltage switching amplitude during active display, thereby maintaining color accuracy while lowering power consumption.
Solution Approach 2:
The charge-sharing circuit acts as an intermediary between the data driver and the liquid crystal capacitors. It provides an intermediate voltage level through charge sharing between adjacent pixel capacitors, reducing the need for frequent high-amplitude voltage switching and thereby decreasing power consumption while maintaining display quality.
2Reliability
If the voltage is varied continuously to prevent liquid crystal deterioration, then the display quality is improved, but the power consumption is increased
Solution Approach 1:
The charge-sharing circuit performs voltage adjustment in advance during the horizontal blanking period, so that when the next frame begins, the liquid crystal capacitors are already at the appropriate intermediate voltage level. This eliminates the need for continuous high-amplitude voltage variation, maintaining display quality while reducing power consumption.
Solution Approach 2:
The charge-sharing circuit operates periodically during horizontal blanking periods rather than continuously. This periodic operation maintains the liquid crystal voltage within safe ranges to prevent deterioration while consuming less power compared to continuous voltage variation.
3Loss of energy
If the activated time of charge-sharing circuit is prolonged to reduce power consumption, then the power-saving effect is improved, but the charging time of pixel capacitors is reduced
Solution Approach 1:
The charging process is segmented into two phases: charge-sharing during horizontal blanking (when power saving is prioritized) and additional charging during the vertical blanking period or early display period (when complete charging is ensured). This segmentation allows prolonged charge-sharing activation for power saving while still guaranteeing complete capacitor charging.
Solution Approach 2:
The charge-sharing circuit performs preliminary charging during horizontal blanking to reduce the remaining charge requirement. This preliminary action allows the circuit to be activated for longer periods without compromising the final charging completeness, as the remaining charging can be completed during subsequent periods.
Data Source
AI summary
A charge-sharing controlling method and a display panel are disclosed. The charge-sharing controlling method is suitable for the display panel including plural sub-pixels. The charge-sharing controlling method includes following steps: determining whether the display panel is displaying a primary color screen; if the display panel is displaying a primary color screen, prolonging an activated time of a charge-sharing circuit, which is coupled between any two of the sub-pixels displaying the same color, adjacent to each other and having opposite polarities.