Display Module Light-Expanding Layer Viewing Angle Control

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Solution Overview

Problem

Conventional liquid crystal display (LCD) technologies experience changes in brightness, contrast, and color when viewed from different angles due to varying luminance of the backlight source, leading to reduced image quality at wider viewing angles and increased light leakage.

Innovation Solution

A display module comprising a backlight module, a liquid crystal layer, and a first light-expanding layer, where the backlight module provides a surface light source that forms an image through the liquid crystal layer, and the first light-expanding layer increases the viewing angle by adjusting the divergence angle of the surface light source, thereby reducing light leakage and maintaining image quality across a wider range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional LCD backlight source is used, then the display provides basic illumination, but the luminance varies significantly at different viewing angles causing reduced image quality and increased light leakage

Engineering Contradiction:

Improveluminance uniformityVSAvoidviewing angle range

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The optical control is segmented into two independent directions: the first light-expanding layer controls light distribution in the first direction while the second light-expanding layer controls light distribution in the second direction perpendicular to the first. This segmentation allows independent optimization of viewing angle characteristics in each direction, resolving the contradiction between luminance uniformity and viewing angle adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different light-expanding layers are applied with different optical properties tailored to specific viewing directions. The first light-expanding layer has optical characteristics optimized for the first direction, while the second light-expanding layer has characteristics optimized for the second direction, allowing local optimization of luminance uniformity for each viewing angle range.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the divergence angle of the surface light source is increased to widen viewing angle, then more viewing directions are covered, but light leakage increases and image quality deteriorates

Engineering Contradiction:

Improveviewing angle coverageVSAvoidlight leakage

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The light distribution control is segmented into two perpendicular directions using separate light-expanding layers. Each layer independently manages the divergence angle in its respective direction, allowing the display to achieve wide viewing angle coverage without excessive light leakage in any single direction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The optical parameters of the light-expanding layers are specifically designed to control the divergence angle. By adjusting the refractive indices, thicknesses, and structural parameters of the first and second light-expanding layers, the divergence angle is optimized to provide wide viewing coverage while maintaining sufficient light confinement to prevent leakage.

Inventive Principle:

Principle #35Parameter changes

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 provides a display module with improved image quality and reduced light leakage at wider viewing angles, ensuring clear images are maintained regardless of the viewer's position, while also minimizing luminance variations at different viewing directions.

Implementation Method 1

The first light-expanding layer is disposed on the liquid crystal layer and is configured to increase the viewing angle of the image light along a first direction

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

The first light-expanding layer substantially extends along a virtual plane... The divergence angle of the surface light source provided by the backlight source in the first direction is smaller

Methodology Applied

Scientific EffectLight diffusion: Scattering

Data Source

PatentUS10921645B2Display module

Publication Date: 2021.02.16 AU OPTRONICS CORP

AI summary

A display module includes a backlight module, a liquid crystal layer disposed on the backlight module, and a first light-expanding layer disposed on the liquid crystal layer. The backlight module provides a surface light source. The surface light source forms an image light through the liquid crystal layer, and the first light-expanding layer increases the viewing angle range of the image light along a first direction. The first light-expanding layer substantially extends along a virtual plane, the first direction is perpendicular to the normal of the virtual plane, and a second direction is perpendicular to the first direction and the normal of the virtual plane. The light intensity at the 60-degree viewing angle of the surface light source along the first direction is lower than the light intensity at the 60-degree viewing angle of the surface light source along the second direction.