Transflective LCD Single Cell Gap Gray-Scale Matching
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Solution Overview
Problem
Transflective liquid crystal displays (LCDs) with a single cell gap suffer from gray-scale differences between reflective and transmissive areas due to phase retardation differences, leading to deteriorated display quality, while dual cell gap structures face manufacturing defects and patterning issues.
Innovation Solution
A transflective LCD with a single cell gap structure, where each pixel includes a transmissive and reflective area with specific electrode configurations and a voltage controller to match phase retardation values, and a method of manufacturing involving thin film transistors, pixel electrodes, and a common electrode to control voltages and align liquid crystal molecules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single cell gap structure is used in transflective LCD, then manufacturing process is simplified, but gray-scale difference occurs between reflective and transmissive areas due to phase retardation difference
Solution Approach 1:
The patent applies local quality by configuring different electrode structures in different areas of the same cell gap. Specifically, the reflective area uses a reflective common electrode while the transmissive area uses a transparent common electrode, allowing each area to have optimized optical properties while maintaining a single cell gap structure for simplified manufacturing.
Solution Approach 2:
The patent changes the optical parameters of the common electrode by using different materials with different transparency characteristics in different areas. The reflective common electrode has high reflectivity while the transparent common electrode has high light transmission, thereby adjusting the phase retardation characteristics locally to match gray-scale between areas.
2Manufacturing precision
If a dual cell gap structure is used in transflective LCD, then gray-scale difference between reflective and transmissive areas is reduced, but step difference occurs and patterning defects occur in manufacturing process
Solution Approach 1:
The patent merges the functions of two different cell gaps into a single cell gap structure by using area-specific electrode configurations. Instead of creating physically separate regions with different gap distances, it combines the reflective and transmissive functions in one uniform cell gap through material property differentiation in the electrode layers.
Solution Approach 2:
The patent shifts from a spatial dimension solution (different cell gap distances) to a material property dimension solution (different electrode transparency and reflectivity). By changing the optical characteristics of electrodes rather than the physical gap distance, it achieves gray-scale matching without creating step differences or patterning complexity.
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
The solution effectively reduces gray-scale differences and improves display quality by matching phase retardation values, simplifying the manufacturing process and reducing defects, resulting in enhanced electro-optical characteristics and manufacturing efficiency.
Implementation Method 1
a transmissive pixel electrode, disposed in the transmissive area, electrically connected to the first thin film transistor to charge a first pixel voltage based on the data signal; and a reflective pixel electrode disposed in the reflective area and electrically connected to the second thin film transistor to charge a second pixel voltage based on the data signal
Implementation Method 2
a liquid crystal layer disposed between the first substrate and the second substrate... drives the liquid crystal layer to control a transmittance of light for each pixel
Data Source
AI summary
A liquid crystal display includes a first substrate including pixels, each having a transmissive area and a reflective area, a second substrate, and a liquid crystal layer disposed between the first and second substrates. Each of the pixels includes first and second thin film transistors which output a data signal in response to a first gate signal, a transmissive pixel electrode disposed in the transmissive area and electrically connected to the first thin film transistor to charge a first pixel voltage based on the data signal, a reflective pixel electrode disposed in the reflective area and electrically connected to the second thin film transistor to charge a second pixel voltage based on the data signal, and a voltage controller which controls the first pixel voltage and the second pixel voltage in response to a second gate signal, which is generated after the first gate signal.