LCD Panel Photo Spacer Relocation for Contrast Ratio
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Solution Overview
Problem
Conventional liquid crystal display panels with horizontal electric field modes, such as IPS and FFS, face challenges in achieving a black display state due to light leakage near photo spacers, which reduces contrast ratio and visibility in bright environments, especially when circular polarizing plates are used.
Innovation Solution
A configuration where a first λ/4 plate and a polarizing plate are sequentially disposed on the observation surface side, with a second λ/4 plate on the back surface side, and photo spacers are strategically placed on both substrates to maintain consistent retardation and prevent light leakage, using a black matrix to hide the spacers and enhance visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a circular polarizing plate is disposed on the observation surface side to increase visibility at bright places, then external light reflection is reduced, but light leakage occurs in the vicinity of the photo spacer causing contrast ratio reduction
Solution Approach 1:
The patent extracts the photo spacer from the pixel region and relocates it to the non-pixel region (adjacent to the pixel region but not overlapping). This separation removes the source of light leakage from the pixel area, allowing the circular polarizing plate to function effectively without causing contrast ratio reduction.
Solution Approach 2:
The patent applies different configurations to different regions: the photo spacer is positioned in the non-pixel region where it does not interfere with the pixel's optical characteristics. This local differentiation allows the pixel region to maintain its imaging function while the non-pixel region houses the photo spacer for cell gap formation.
2Manufacturing precision
If photo spacers are disposed on the substrate to maintain cell gap, then liquid crystal layer thickness is controlled, but light leakage occurs in the vicinity of the photo spacer reducing contrast ratio
Solution Approach 1:
The photo spacer is extracted from the pixel region and repositioned in the non-pixel region. This relocation maintains the photo spacer's function in controlling cell gap thickness while removing it from the light path of the pixel region, thereby preventing light leakage that would reduce contrast ratio.
3Illumination intensity
If a retarder is disposed on the liquid crystal layer side to improve visibility, then external light reflection is reduced, but light leakage occurs near the photo spacer causing contrast ratio reduction
Solution Approach 1:
The photo spacer is extracted from the pixel region and relocated to the non-pixel region. This separation ensures that the retarder can improve visibility without the photo spacer causing light leakage in the pixel area, thus maintaining high contrast ratio.
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 improves visibility in bright environments by reducing light leakage and maintaining a high contrast ratio, allowing for effective black display states in liquid crystal display panels.
Implementation Method 1
The in-cell retarder is formed by, for example, applying a liquid crystalline photopolymerizable material (liquid crystalline photopolymerizable monomer) to the liquid crystal layer side surface of the substrate on the observation surface side
Implementation Method 2
One of the first substrate and the second substrate includes a pair of electrodes configured to generate a horizontal electric field at the liquid crystal layer upon voltage application. Liquid crystal molecules in the liquid crystal layer homogeneously align with no voltage application between the electrodes.
Implementation Method 3
a first polarizing plate; a first λ/4 plate; a first substrate; a second λ/4 plate... The in-plane slow axis of the first λ/4 plate forms an angle of 45° with the transmission axis of the first polarizing plate
Data Source
AI summary
The liquid crystal display panel includes: a first polarizing plate; a first λ/4 plate; a first substrate; a second λ/4 plate; a liquid crystal layer; a second substrate; and a second polarizing plate, wherein the first substrate includes a black matrix but no photo spacer, the second substrate includes a photo spacer overlapping with the black matrix, liquid crystal molecules in the liquid crystal layer homogeneously align with no voltage application, the second λ/4 plate covers no side surface of the photo spacer, and the in-plane slow axis of the first λ/4 plate forms an angle of 45° with the transmission axis of the first polarizing plate and is orthogonal to the in-plane slow axis of the second λ/4 plate.