Floating Gate TFT LCD Subpixel Shared Data Line
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Solution Overview
Problem
Conventional multi-domain vertical alignment LCDs require complex data line layouts and multiple data driving chips, increasing costs due to the need for separate gray scale voltage supply to each sub pixel unit.
Innovation Solution
The LCD design features a single data line driving both sub pixel units, with one TFT having an electrically floating gate electrode, simplifying the layout and reducing the number of data driving chips by using a shared data line for gray scale voltage supply, while maintaining contrast and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate data lines are used to supply gray scale voltages to each sub pixel unit, then display performance is enhanced, but data line layout complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the data line supply for both sub pixel units into a single shared data line. The first and second sub pixel units share the same data line for supplying gray scale voltages, eliminating the need for separate data lines and reducing layout complexity while maintaining display performance through the floating gate mechanism
Solution Approach 2:
The floating gate electrode acts as an intermediary element that enables a single data line to control two separate sub pixel units. By making the gate electrode of the second TFT electrically floating and connecting it to the drain of the first TFT, the system achieves independent control of both sub pixels through a shared data line, resolving the contradiction between simplified layout and display performance
2Reliability
If multiple data driving chips are used to supply gray scale voltages to each sub pixel unit, then display performance is enhanced, but manufacturing cost increases
Solution Approach 1:
The single data line is designed to perform multiple functions: it supplies gray scale voltages to both the first and second sub pixel units, and through the floating gate mechanism, enables independent control of both sub pixels. This multi-functionality eliminates the need for multiple dedicated data driving chips, reducing manufacturing cost while maintaining display performance
3Device complexity
If a single data line drives both sub pixel units, then data line layout complexity and manufacturing cost are reduced, but control precision over each sub pixel unit may be compromised
Solution Approach 1:
The floating gate electrode serves as a precision control intermediary. By making the gate electrode of the second TFT electrically floating and connecting it to the drain of the first TFT, the system achieves precise independent control of both sub pixel units through voltage division and capacitive coupling, maintaining manufacturing precision despite using a simplified single data line layout
Data Source
AI summary
An LCD includes data lines, gate lines intersecting with the data lines, and pixel units. Each pixel unit is defined by a minimal area formed by two adjacent data lines and two adjacent gate lines. Each pixel unit includes a first sub pixel unit and a second sub pixel unit. The first sub pixel unit includes a first thin film transistor (TFT) and a first pixel electrode. The second sub pixel unit includes a second TFT and a second pixel electrode. A gate electrode of the first TFT is connected to the gate line, a source electrode of the first TFT is connected to the data line. A source electrode of the second TFT is connected to a same data line, and a gate electrode of the second TFT is electrically floating.