Double-Layered Electrode Structure for LCD Aperture Ratio
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Solution Overview
Problem
In-plane switching mode liquid crystal display devices face limitations in reducing the width of pixel and common electrodes due to resolution constraints of light exposure apparatuses, leading to decreased aperture ratio, brightness, and increased light reflectance, which affects viewing angles and power consumption.
Innovation Solution
The implementation of a double-layered structure for pixel and common electrodes, where the lower layer is made of a reflective conductive material and the upper layer of a transparent conductive material, with the use of H2O gas during the deposition of the transparent conductive layer to enhance etch bias and achieve narrower electrode widths, allowing for improved patterning precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layered structure is used for pixel and common electrodes, then the manufacturing process is simpler, but the light reflectance increases and aperture ratio decreases
Solution Approach 1:
The electrode structure is segmented into two distinct layers: a reflective conductive material layer (first layer) and a transparent conductive material layer (second layer). This segmentation allows each layer to perform its specific function - the first layer provides reflectivity control while the second layer provides transparency and conductivity, thereby reducing overall light reflectance while maintaining manufacturing feasibility
Solution Approach 2:
The electrode structure uses composite materials by combining reflective conductive material (such as aluminum or silver) with transparent conductive material (such as ITO or IZO). This composite structure leverages the complementary properties of both materials to achieve reduced light reflectance while maintaining electrical conductivity and transparency, directly addressing the harmful light reflectance issue
2Area of stationary object
If the electrode width is reduced to increase aperture ratio, then the brightness and aperture ratio improve, but the light exposure apparatus resolution requirements become more stringent
Solution Approach 1:
The solution moves from a single-layer electrode structure to a two-layer electrode structure, adding a vertical dimension to the electrode design. This dimensional change allows the electrodes to achieve narrower effective widths while maintaining manufacturability, as the dual-layer structure can be optimized independently in terms of width, thickness, and material composition to meet both aperture ratio and patterning precision requirements
3Area of stationary object
If the electrode width is reduced, then the aperture ratio increases, but the brightness may be affected due to reduced conductive material area
Solution Approach 1:
The composite material structure combines reflective conductive material with transparent conductive material in a dual-layer configuration. This allows the electrode to maintain high electrical conductivity and light transmission efficiency even at reduced widths, thereby preserving display brightness while increasing aperture ratio. The transparent conductive layer ensures optimal light transmission, while the reflective layer controls parasitic reflections that would otherwise reduce brightness
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 configuration increases the aperture ratio, reduces light reflectance, and enhances display quality by allowing for narrower electrode widths, thus improving brightness and reducing color differences across viewing angles.
Implementation Method 1
a transparent conductive material layer is formed on the reflective conductive material layer
Implementation Method 2
etching the transparent conductive material layer and the reflective conductive material layer using the photoresist pattern as an etching mask
Implementation Method 3
forming a photoresist pattern on the transparent conductive material layer
Data Source
AI summary
An array substrate for a liquid crystal display device comprises: gate and data lines crossing each other on a substrate to define a pixel region; a common line spaced apart from and parallel with the gate line; a thin film transistor in the pixel region and connected to the gate and data lines; a passivation layer on the thin film transistor; and pixel and common electrodes alternately arranged to produce an in-plane electric field, wherein each of the pixel and common electrodes has a double-layered structure of which the lower layer is formed of reflective conductive material and the upper layer is formed of transparent conductive material.