Liquid Crystal Display Pixel Reset Circuit for Charge Retention
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Solution Overview
Problem
Liquid crystal display devices with memory in each pixel face the challenge of preventing charge retention in the liquid crystal when the power is turned off, leading to issues like burn-in and image retention, which existing technologies fail to adequately address.
Innovation Solution
Incorporating a reset circuit that sets the potential difference between voltages applied to both ends of the liquid crystal to 0V when the power is turned off, using a combination of inverter circuits and switching elements to ensure equalization of video voltages, and employing a power source circuit to generate an internal voltage based on an external power source, which is used as a reset signal to discharge the liquid crystal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a memory is arranged in each display pixel to maintain image display without external input signals, then power consumption is reduced and image display capability is improved, but charge retention in liquid crystal occurs causing burn-in and image retention
Solution Approach 1:
The reset circuit is activated in advance when power is turned off to equalize the video voltages applied to the liquid crystal before the display operation stops, preventing charge retention from occurring in the first place
Solution Approach 2:
The invention utilizes the power-off event itself as a trigger signal to activate the reset circuit, converting the harmful effect of power interruption into a beneficial opportunity to discharge the liquid crystal and prevent burn-in
2Use of energy by moving object
If power source is turned off to optimize power consumption, then energy efficiency is improved, but charge remains in liquid crystal causing display defects
Solution Approach 1:
The reset operation is performed preliminarily during the power-off transition period, equalizing voltages before the display function completely shuts down, ensuring no charge remains when power consumption is minimized
Solution Approach 2:
The system uses its own power-off event to automatically trigger the reset circuit, making the discharge operation self-activating without requiring external control signals or additional power consumption
3Reliability
If video voltages are equalized to prevent charge retention, then display reliability is improved, but additional reset circuit components increase device complexity
Solution Approach 1:
The reset circuit serves multiple functions: it equalizes video voltages to prevent charge retention, uses the power-off event as its trigger signal, and can be integrated with existing display pixel structures, making it a multi-functional component that adds minimal complexity
Solution Approach 2:
The reset circuit is merged with the existing video signal lines and power control logic, combining the discharge function with the existing voltage application infrastructure rather than adding completely separate control mechanisms
Data Source
AI summary
A display device which arranges a memory part for every display pixel is configured to prevent a charge from remaining in liquid crystal when a power source is turned off. Each display pixel includes a memory part for storing video data, a pixel electrode, and a switch part for selectively applying a first video voltage or a second video voltage different from the first video voltage to the pixel electrode corresponding to the video data stored in the memory part. The display device further includes a reset circuit for allowing the first video voltage and the second video voltage to have the same voltage when a power source of the display device is turned off.