LCD VCOM Voltage Adjustment for Flicker Reduction
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Solution Overview
Problem
Liquid crystal display (LCD) panels experience flickering and image sticking issues when operating at lower refresh rates due to mismatched common electrode voltage (VCOM) frequencies, hindering the adoption of lower refresh rates for power savings.
Innovation Solution
An information handling system with a timing controller and power management integrated circuit (PMIC) that adjusts and applies a common voltage at the target refresh rate to the LCD, balancing positive and negative voltages to minimize flicker and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the LCD operates at lower refresh rates to save power, then energy consumption is reduced, but flickering and image sticking issues occur due to mismatched VCOM frequencies
Solution Approach 1:
The system dynamically adjusts the VCOM frequency to match the LCD refresh rate. The power management circuit receives the target refresh rate from the timing controller and dynamically selects or generates the corresponding VCOM frequency, allowing the display to operate stably at various refresh rates including lower power-saving modes.
Solution Approach 2:
The invention changes the VCOM frequency parameter based on the refresh rate. By adjusting this electrical parameter to match different operating conditions, the system eliminates flickering while enabling lower refresh rates for power savings. The storage component holds multiple VCOM frequency values corresponding to different refresh rates.
2Device complexity
If a fixed VCOM frequency is used, then the circuit design is simplified, but the LCD cannot operate correctly at variable refresh rates
Solution Approach 1:
The power management circuit is designed with multi-functionality to handle both fixed and variable refresh rate scenarios. It can operate in different modes: using a fixed VCOM frequency for simplicity or dynamically adjusting to match variable refresh rates, making the display system adaptable to different operating conditions without requiring complete circuit redesign.
Solution Approach 2:
The timing controller acts as an intermediary between the refresh rate requirements and the VCOM generation. It communicates the target refresh rate to the power management circuit, which then uses this information to select or generate the appropriate VCOM frequency, bridging the gap between variable display requirements and stable voltage supply.
3Device complexity
If the VCOM frequency does not match the refresh rate, then the common voltage generation is simpler, but flickering and image sticking occur
Solution Approach 1:
The system implements feedback by having the timing controller communicate the target refresh rate to the power management circuit. This feedback loop ensures that the VCOM frequency is continuously adjusted to match the actual operating refresh rate, preventing flickering and image sticking while maintaining relatively simple voltage generation circuitry.
Data Source
AI summary
An information handling system includes a timing controller configured to transmit a command for a common voltage of a particular frame rate to a power management circuit. A storage component may store digital information, wherein each digital information is associated with the common voltage of a particular frame rate. The power management circuit supports a variety of common voltage requirements of the liquid crystal display including an ability to select digital information of the digital information that is associated with the common voltage at the particular frame rate stored in the storage component and apply the common voltage at the particular frame rate to the liquid crystal display.