Liquid Crystal Display Pixel Structure for Residual Image Reduction
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Solution Overview
Problem
Liquid crystal displays (LCDs) experience residual image phenomena due to residual charges in liquid crystal capacitors, which existing solutions, such as generating specific signals for full black or full white images, increase system complexity without fully addressing the issue.
Innovation Solution
The implementation of a liquid crystal display design that includes a source driver, a gate driver, and pixel units with a liquid crystal capacitor and storage capacitors, where the voltage level of the second common voltage is greater than the first common voltage, effectively reducing the residual image phenomenon by ensuring a faster discharge of pixel electrode voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a timing controller generates a specific signal for enabling a source driver to generate a pattern of data signal (full black or full white image) upon powering off, then the residual image phenomenon can be reduced, but the system complexity increases
Solution Approach 1:
The patent extracts the residual charge removal function from the timing controller and signal generation system, and implements it directly at the pixel level through dedicated discharge paths. By removing the need for complex controller signals and source driver pattern generation, the solution eliminates residual images through a simplified architecture where each pixel unit independently discharges its own charges through the second storage capacitor connected to the second common voltage line.
Solution Approach 2:
The patent introduces a second common voltage line and second storage capacitor as intermediary elements between the pixel electrode and ground. This intermediary discharge path allows residual charges to be rapidly removed without requiring complex control signals, effectively mediating the charge removal process in a simple and efficient manner.
2Speed
If the voltage level of the second common voltage is increased to a range between maximum pixel data voltage and twice the maximum pixel data voltage, then the discharge speed of pixel electrode voltage increases, but the voltage management complexity increases
Solution Approach 1:
The patent changes the voltage parameter of the second common voltage line to a specific range (between maximum pixel data voltage and twice the maximum pixel data voltage) to optimize the discharge speed. This parameter adjustment creates an optimal voltage differential that accelerates charge removal while maintaining manageable voltage levels through straightforward voltage generation circuitry.
3Productivity
If a second storage capacitor is added between the pixel electrode and the second electrode, then the residual charge removal efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The patent implements multi-functionality by having the second storage capacitor serve dual purposes: it acts as a regular storage capacitor during normal display operation to maintain pixel voltage, and simultaneously serves as a discharge path during shutdown to rapidly remove residual charges. This universal component eliminates the need for separate discharge capacitors, reducing overall structural complexity while improving charge removal efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design shortens the time period of residual image phenomenon from 10 seconds to 1 second by ensuring the pixel electrode voltage drops to zero faster, thereby improving the LCD's shutdown process.
Implementation Method 1
a liquid crystal capacitor electrically coupled between the first electrode and the pixel electrode for driving liquid crystal layer in response to the pixel data voltage and the first common voltage
Implementation Method 2
a storage capacitor electrically coupled between the pixel electrode and the second electrode
Data Source
AI summary
A liquid crystal display includes a source driver, for generating a pixel data voltage, a gate driver, for generating a scanning signal voltage, and a plurality of pixel units. Each pixel unit includes a switch unit for delivering the pixel data voltage upon receiving the scanning signal voltage, a pixel electrode electrically coupled to the switch unit, a first electrode for supplying a first common voltage, a second electrode for supplying a second common voltage, a liquid crystal capacitor electrically coupled between the first electrode and the pixel electrode for driving liquid crystal layer in response to the pixel data voltage and the first common voltage, and a storage capacitor electrically coupled between the pixel electrode and the second electrode.