LCD Wire Grid Polarizer Pad Electrode Adhesion
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Solution Overview
Problem
Liquid crystal displays (LCDs) face issues with light efficiency due to absorptive polarizing plates, and the integration of wire grid polarizers (WGP) can lead to wiring defects in pad portions due to adhesion problems with metal wiring lines on the WGP insulating layer.
Innovation Solution
The LCD design includes a WGP on one substrate, a WGP insulating layer covering it, and a pad electrode extending along the sidewall of the insulating layer, with a non-overlap area on the substrate to prevent defects, and a flexible printed circuit board connected via an anisotropic conductive film for improved adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a WGP insulating layer is formed to prevent metal material effects on TFT, then TFT characteristics are protected, but adhesion problems occur in pad portions due to metal wiring lines on the insulating layer
Solution Approach 1:
The pad electrode is divided into two distinct parts: a first pad electrode formed on the substrate before the WGP insulating layer, and a second pad electrode formed on the WGP insulating layer. This segmentation allows each part to serve its function without adhesion problems - the first pad electrode provides a stable base layer, while the second pad electrode makes contact with the metal wiring line without requiring adhesion to the WGP insulating layer.
Solution Approach 2:
The first pad electrode acts as an intermediary layer between the substrate and the second pad electrode. It provides a stable adhesion surface for the second pad electrode, eliminating the need for the second pad electrode to adhere to the WGP insulating layer, thus preventing wiring defects while maintaining TFT protection.
2Ease of manufacture
If an absorptive polarizing plate is used to adjust polarization of incident light, then polarization control is achieved, but light efficiency of the light source is reduced
Solution Approach 1:
The absorptive polarizing plate is replaced with a wire grid polarizer (WGP) that uses reflection rather than absorption to achieve polarization. The WGP reflects S-polarized light and transmits P-polarized light, eliminating the energy loss associated with absorption while maintaining effective polarization control for the LCD.
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 enhances light efficiency by using a WGP and prevents wiring defects in the pad portion, ensuring reliable electrical connections and improved display performance.
Implementation Method 1
The WGP is an optical device that extracts linearly polarized light having a specific oscillation direction from unpolarized light such as natural light. When a period of the arrangement of metal wires is shorter than a half wavelength of an incident electromagnetic wave, a polarization component (S wave) parallel to the metal wires is reflected, and a polarization component (P wave) perpendicular to the metal wires is transmitted.
Implementation Method 2
a flexible printed circuit board connected to a pad portion, wherein the FPCB is thermo-compression bonded to the pad portion by an anisotropic conductive film disposed on the first substrate
Data Source
AI summary
Provided are a liquid crystal display (LCD) comprising: a first substrate; a second substrate which faces the first substrate; a liquid crystal layer which is disposed between the first substrate and the second substrate; a wire grid polarizer (WGP) which is disposed on the first substrate; a WGP insulating layer which is disposed on the WGP and covers the WGP; and a pad electrode which is disposed on the first substrate, wherein the first substrate comprises a non-overlap area protruding from the second substrate, a sidewall of the WGP insulating layer is located in the non-overlap area, and the pad electrode extends from the non-overlap area of the first substrate along the sidewall of the WGP insulating layer.