Multi-domain Polarizing Sheet for LCD Light Leakage Compensation

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Solution Overview

Problem

Existing liquid crystal display (LCD) devices face challenges in achieving uniform light transmissivity and high aperture ratio, leading to light leakage and contrast issues, particularly in diagonal viewing angles due to differences in liquid crystal alignment directions across domains within a pixel region.

Innovation Solution

The implementation of a polarizing sheet or compensation film with multiple polarizing domains, each corresponding to the alignment domains of the liquid crystal, to compensate for light-transmitting characteristics and improve alignment matching, thereby enhancing light efficiency and image contrast.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single polarizing sheet with uniform light-transmitting axis is used, then the structure is simple and manufacturing is easy, but light transmissivity becomes non-uniform across different alignment domains causing light leakage and contrast issues

Engineering Contradiction:

Improvepolarizing sheet manufacturing simplicityVSAvoidlight transmissivity uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The polarizing sheet is divided into multiple polarizing domains, each with a light-transmitting axis oriented in a specific direction corresponding to the liquid crystal alignment direction of its corresponding domain. This segmentation allows each domain to control light transmission independently, achieving uniform overall light transmissivity while maintaining manufacturing feasibility through standardized domain-specific processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the polarizing sheet are assigned different light-transmitting axis orientations matched to the local liquid crystal alignment characteristics. Each polarizing domain exhibits specialized optical properties tailored to its corresponding alignment domain, transforming the uniform sheet into a functionally differentiated structure that addresses local optical requirements

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If liquid crystal molecules are aligned in multiple directions within a pixel region to improve viewing angle, then viewing angle performance improves, but light leakage increases and contrast deteriorates

Engineering Contradiction:

Improveviewing angle performanceVSAvoidlight leakage

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The invention converts the potentially harmful effect of multiple alignment directions (which cause light leakage) into a beneficial configuration by introducing corresponding polarizing domains with matched light-transmitting axes. Each alignment domain's inherent optical characteristics are harnessed through its matching polarizing domain to achieve uniform light transmission, transforming the source of contrast problems into the solution for improved viewing angle performance

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If the light-transmitting axis of the polarizing sheet is oriented at a fixed angle, then the polarizing sheet structure is simple, but light transmission becomes non-uniform across domains with different alignment angles

Engineering Contradiction:

Improvepolarizing sheet structure complexityVSAvoidlight transmission uniformity

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The polarizing sheet structure is segmented into multiple domains, each with independently controlled light-transmitting axis orientations. This segmentation increases functional complexity while maintaining overall structural manageability, allowing each segment to optimize light transmission for its specific alignment domain while the complete sheet maintains coherent optical performance

Inventive Principle:

Principle #1Segmentation

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 approach improves light efficiency and image contrast by ensuring uniform light transmissivity across all domains, reducing light leakage and enhancing viewing angles without compromising contrast.

Implementation Method 1

a polarizing sheet having a plurality of polarizing domains corresponding to the plurality of alignment domains of the liquid crystal

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 2

The LCD device is driven according to the optical anisotropy and polarizing characteristics of the liquid crystal material

Methodology Applied

Scientific EffectOptical anisotropy: Anisotropy

Data Source

PatentUS7630030B2LCD device comprising a polarizing domain of a polarizing sheet having a transmission angle that is the same as the liquid crystal alignment angle of the corresponding alignment domain of a pixel

Publication Date: 2009.12.08 LG DISPLAY CO LTD

AI summary

Disclosed is an LCD device and a method for fabricating the same is disclosed, which maximizes light efficiency by compensating for light transmissivity resulting from the alignment of the liquid crystal in a plurality of alignment domains within a pixel region. Compensation is accomplished by a polarizing sheet having a plurality of polarizing regions corresponding to the alignment domains, wherein each polarizing region has a transmission angle that corresponds to the alignment angle of the corresponding domain so that light leakage in a black state can be minimized.