Liquid Crystal Panel Oblique Viewing Compensation

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Solution Overview

Problem

Conventional liquid crystal display apparatuses fail to provide sufficient contrast ratio and color uniformity when viewed from different angles, particularly in large stationary television settings, due to inadequate reduction of light leak and color shift in oblique directions.

Innovation Solution

Incorporating an isotropic optical element between the liquid crystal cell and the second polarizer, and using a negative C plate in combination with a negative A plate between the liquid crystal cell and the first polarizer, to reduce light leak and enhance display properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a negative A plate is used to improve contrast ratio in oblique direction, then contrast ratio is improved, but color shift in oblique direction cannot be sufficiently reduced

Engineering Contradiction:

Improvecontrast ratioVSAvoidcolor shift

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent combines multiple optical compensation films (negative C plate and negative A plate) with different optical characteristics to create a composite structure. The negative C plate (with nx=ny>nz) and negative A plate (with nx=nz>ny) work together to simultaneously control both contrast ratio and color shift, achieving performance that neither film could provide alone.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The optical compensation function is divided into separate components: the negative C plate handles one aspect of optical compensation while the negative A plate handles another. This segmentation allows each component to be optimized for its specific function while working together to solve the overall problem of oblique viewing performance.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If multiple persons view a large display at the same time from different angles, then viewing coverage is improved, but display uniformity and contrast ratio deteriorate

Engineering Contradiction:

Improveviewing coverageVSAvoiddisplay uniformity

Core Design Contradiction:

Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent modifies the optical parameters of the liquid crystal display system by introducing compensation films with specific retardation values and optical axes. The negative C plate and negative A plate have carefully controlled refractive index relationships (nx=ny>nz and nx=nz>nymodified the viewing angle characteristics and improved display uniformity across different viewing angles, enabling multiple viewers to simultaneously enjoy consistent image quality.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If conventional retardation films are used to improve display properties, then some contrast ratio improvement is achieved, but light leak in oblique direction cannot be sufficiently reduced

Engineering Contradiction:

Improvecontrat ratioVSAvoidlight leak

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The negative C plate and negative A plate act as intermediary optical elements between the liquid crystal cell and the viewer. These compensation films mediate the optical interaction by controlling the polarization state and phase delay of light passing through the display, thereby reducing light leak in oblique directions while maintaining contrast ratio improvement.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 significantly improves the contrast ratio and reduces color shift in oblique directions, providing better display uniformity and comfort for multiple viewers without color unevenness across the screen.

Implementation Method 1

a negative C plate and a negative A plate which satisfy nx=ny>nz and nx=nz>nymodified by the presence of the negative C plate and negative A plate, light leak in an oblique direction in black display can be drastically reduced

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 2

arranging an isotropic optical element between the liquid crystal cell and a second polarizer

Methodology Applied

Scientific EffectOptical retardation: Birefringence

Data Source

PatentUS7619706B2Liquid crystal panel, liquid crystal television, and liquid crystal display apparatus

Publication Date: 2009.11.17 NITTO DENKO CORP

AI summary

A liquid crystal panel including a liquid crystal cell having an improved contrast ratio in an oblique direction and an improved color shift in an oblique direction is provided.A liquid crystal panel according to the present invention includes: a liquid crystal cell; a first polarizer arranged on one side of the liquid crystal cell; a second polarizer arranged on another side of the liquid crystal cell; a negative C plate and a negative A plate arranged between the liquid crystal cell and the first polarizer; and an isotropic optical element arranged between the liquid crystal cell and the second polarizer. The negative C plate is arranged between the first polarizer and the negative A plate.