LCD Terminal Layer Structure Against Reflective Electrode Etchant Damage
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Solution Overview
Problem
Conductive layers in the terminal portion of reflective and transflective liquid crystal display devices are prone to damage during the formation of a reflective electrode due to the use of etchants.
Innovation Solution
The terminal portion is designed with a specific layered structure where the lower conductive layer is formed in the same layer as the gate electrode, covered by an intermediate transparent conductive layer, and an upper conductive layer is formed in the same layer as the transparent electrode, without including a conductive layer in the same layer as the source or drain electrodes, and the structure includes an organic insulating layer with an uneven surface to match the reflective electrode's uneven surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive layer is formed in the same layer as the source electrode and drain electrode in the terminal portion, then electrical connectivity is improved, but the terminal portion is damaged by etchant during reflective electrode formation
Solution Approach 1:
The patent extracts the problematic conductive layer configuration from the terminal portion. Specifically, it removes the conductive layer that would be formed in the same layer as the source and drain electrodes from the terminal portion structure, thereby eliminating the vulnerability to etchant damage while preserving electrical connectivity through alternative conductive layer arrangements
Solution Approach 2:
The patent applies local quality by differentiating the terminal portion structure from the pixel electrode structure. The terminal portion uses a specific layered configuration (first conductive layer, second conductive layer, third conductive layer) that differs from the source/drain electrode layer, providing localized protection against etchant while maintaining overall device functionality
2Adaptability or versatility
If a reflective electrode is formed using etchant, then the reflective region is created for reflection mode display, but the terminal portion conductive layers are damaged
Solution Approach 1:
The patent segments the device into distinct functional regions with different layered structures. The display region contains the reflective electrode formed by etching the reflective region of the transparent electrode, while the terminal portion uses a protected layered structure that prevents etchant damage, allowing both reflection mode display and terminal integrity
Solution Approach 2:
The patent introduces an intermediate protective structure in the terminal portion consisting of multiple conductive layers (first, second, and third conductive layers) that act as intermediaries to protect against etchant penetration while still allowing the etching process to proceed in the display region for reflective electrode formation
Data Source
AI summary
A first substrate of a liquid crystal display device includes a TFT provided in each pixel, a transparent electrode electrically connected to the TFT, a reflective electrode provided on a portion of the transparent electrode which is located in a reflective region, and a terminal portion disposed in a non-display region. The terminal portion includes a lower conductive layer formed in the same layer as a gate electrode of the TFT, an intermediate conductive layer formed of a transparent conductive material and covering the lower conductive layer, and an upper conductive layer formed in the same layer as the transparent electrode, and does not include a conductive layer formed in the same layer as a source electrode and a drain electrode of the TFT.