Dual-TFT LCD Panel with Shared Data Line for Aperture Ratio
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Solution Overview
Problem
Conventional Multi-domain Vertical Alignment (MVA) liquid crystal displays (LCDs) face limitations in viewing angle and aperture ratio due to the use of opaque data lines, which also lead to color shift and reduced performance.
Innovation Solution
The implementation of an LCD panel design with two thin film transistors (TFTs) in each pixel unit, where the channel width/length ratio of the first TFT is 1.5-2.5 times larger than that of the second TFT, allowing for different tilt angles of liquid crystal molecules and reducing the need for opaque wirings, thereby enhancing the aperture ratio and minimizing color shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional MVA LCD uses separate first and second data lines for upper and lower pixel areas, then different tilt angles can be achieved, but the aperture ratio decreases due to opaque data lines
Solution Approach 1:
The patent merges the first and second data lines into a single shared data line that serves both the first TFT (controlling upper pixel area) and the second TFT (controlling lower pixel area). This consolidation eliminates the need for separate opaque data lines for each pixel area, thereby increasing the aperture ratio while still enabling independent control of different tilt angles through the dual-TFT architecture with different channel width/length ratios
Solution Approach 2:
The single shared data line performs multiple functions by serving both the first TFT and the second TFT in different pixel areas. This multi-functional data line structure allows the display to achieve different tilt angles in upper and lower regions without requiring separate dedicated data lines for each region, thus improving aperture ratio while maintaining viewing angle performance
2Adaptability or versatility
If conventional MVA LCD uses two TFTs with different channel width/length ratios, then different tilt angles are achieved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by giving the first TFT and second TFT different channel width/length ratios tailored to their specific functions. The first TFT has a larger channel width/length ratio optimized for controlling the upper pixel area, while the second TFT has a smaller ratio optimized for the lower pixel area. This localized optimization enables precise control of different liquid crystal tilt angles in different regions without requiring complex additional control circuits
Solution Approach 2:
The patent changes the physical parameters of the TFTs by adjusting the channel width/length ratios of the first and second TFTs. By modifying these geometric parameters during the manufacturing process, the display achieves different electrical characteristics and drive capabilities for controlling liquid crystal molecules in different pixel areas, thereby enabling multi-domain control with enhanced viewing angles
3Reliability
If conventional MVA LCD uses opaque data lines, then effective electrical connection is achieved, but color shift increases and aperture ratio decreases
Solution Approach 1:
By merging the first and second data lines into a single shared data line that connects to both TFTs, the patent reduces the total amount of opaque wiring material needed. This consolidation maintains reliable electrical connections to both pixel areas while minimizing the blocking of light by opaque lines, thereby reducing color shift and improving aperture ratio
Data Source
AI summary
An exemplary liquid crystal display (200) includes a plurality of gate lines (201), data lines (202), common lines (210), first pixel electrodes (204) and second pixel electrodes (214). Each of areas defined by one of the first pixel electrodes and an adjacent one of the second pixel electrodes is a pixel unit (208). Each pixel unit is driven by a first TFT (203) and a second TFT (213). The first thin film transistor and the second thin film transistor in each pixel unit are connected to a same one of the gate lines and a same one of the data lines, and to the first pixel electrode and the second pixel electrode respectively. A channel width/length ratio of the first thin film transistor is different from a channel width/length ratio of the second thin film transistor.