LCD Pixel Circuit Connecting Switch for Feed-Through Voltage
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Solution Overview
Problem
Conventional LCD technologies face issues with feed-through voltage, which causes brightness differences between frames of positive and negative polarity, leading to flicker and increased image sticking risks, due to limitations in the storage capacitor's capacity.
Innovation Solution
Incorporating a connecting switch, specifically a second thin-film transistor, between pixel units in the same column but different rows to increase overall capacitance, thereby reducing feed-through voltage by equally sharing its influence across connected capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the storage capacitor capacity is increased to reduce feed-through voltage, then the feed-through voltage is reduced, but the aperture ratio is reduced
Solution Approach 1:
The patent merges the storage capacitor functions of adjacent pixel units by electrically connecting pixel electrodes through a connecting switch. This allows the capacitance of multiple pixel electrodes to be combined, effectively increasing the total capacitance available for reducing feed-through voltage without requiring a larger dedicated storage capacitor within each pixel unit, thereby preserving aperture ratio.
Solution Approach 2:
The pixel electrode serves multiple functions: it acts as both the display electrode and part of the storage capacitor. By connecting adjacent pixel electrodes, the system achieves multi-functionality where the same structural element (pixel electrode) contributes to both display function and charge storage, eliminating the need for separate large storage capacitors that would reduce aperture ratio.
2Object-affected harmful factors
If the storage capacitor capacity is increased to reduce feed-through voltage, then the feed-through voltage is reduced, but the device complexity is increased
Solution Approach 1:
Instead of adding more separate capacitor components to each pixel unit, the patent combines the capacitance of existing pixel electrodes through electrical connection. This merging approach increases effective capacitance without adding structural complexity or additional capacitor components.
Solution Approach 2:
The pixel electrode and connecting switch structure serves dual purposes: maintaining display functionality while providing enhanced charge storage capacity. This multi-functionality reduces device complexity by eliminating the need for separate dedicated storage capacitors.
3Object-affected harmful factors
If the connecting switch is added to increase overall capacitance, then the feed-through voltage is reduced, but the device complexity is increased
Solution Approach 1:
The connecting switch is integrated into the existing pixel circuit structure, allowing the same transistor to function as both the pixel switching element and the connecting switch. This multi-functionality reduces device complexity by avoiding the addition of separate dedicated connecting transistors.
Solution Approach 2:
The patent merges the functions of pixel control and inter-pixel connection into a unified circuit architecture. By sharing transistors and conductive structures between pixel operation and connection functions, the overall device complexity is minimized while achieving the desired capacitance increase.
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 solution effectively reduces feed-through voltage and minimizes the risk of image sticking by increasing the overall capacitance, ensuring consistent charging and improved display quality.
Implementation Method 1
Ctotal=Cgs(parasitic capacitor of a TFT)+Cst (storage capacitor)+Clc (liquid crystal capacitor)... the value of AV can be lower by reducing Cgs or increasing Ctotal... increasing Cst is the conventional approach... However, Cst is usually limited by conditions such as an aperture ratio
Data Source
AI summary
An LCD array substrate, an LCD panel and an LCD pixel circuit are disclosed. The LCD array substrate includes: a substrate and a plurality of gate lines and data lines, wherein the gate lines and the data lines are crossed with each other to form a plurality of pixel units; each of the pixel units is provided with a pixel electrode, a first thin-film transistor, and a connecting switch controlled by the corresponding gate line; the switch is controlled to be turned on.