Light Guide Panel Structure for Reducing Edge Dark Portions

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Solution Overview

Problem

Conventional edge-light type backlight units in liquid crystal displays suffer from the generation of dark portions due to uneven light distribution, leading to irregular brightness and reduced display quality, which limits the miniaturization of the backlight unit and effective screen area.

Innovation Solution

A light guide panel with dark portion reducing units, such as oblique grooves or semi-conical shapes, on its incidence surface to reflect light and reduce dark areas, combined with diffusion units for uniform light distribution, ensures that light is redirected to minimize dark portions and enhance brightness uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If edge light sources are installed at lateral sides of light guide panel, then device size is reduced, but dark portions are created causing non-uniform brightness

Engineering Contradiction:
Improvebacklight unit sizeVSAvoidbrightness uniformity
Core Design Contradiction:
Volume of moving objectVSIllumination intensity

Solution Approach 1:

The patent applies local quality by creating dark portion reducing units with specific geometric features (oblique grooves, semi-conical shapes, or pyramidal structures) at specific locations on the light guide panel - namely between adjacent light sources and at panel edges. These localized structural modifications redirect light precisely where dark portions occur, improving brightness uniformity without requiring changes to the overall edge-lit configuration or increasing device size.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The dark portion reducing units act as intermediary optical elements between the light sources and the display area. These units with their specific geometric configurations (oblique surfaces, grooves, or conical shapes) serve as mediators that redirect light from the edge sources into the dark portion areas, enabling uniform illumination without directly modifying the light sources themselves or the panel boundaries.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If distance d from LED is excluded to avoid dark portions, then brightness uniformity is improved, but effective screen area is reduced

Engineering Contradiction:
Improvebrightness uniformityVSAvoideffective screen area
Core Design Contradiction:
Illumination intensityVSArea of stationary object

Solution Approach 1:

The patent applies preliminary action by pre-configuring dark portion reducing units with specific geometric structures (oblique grooves, semi-conical shapes) at predetermined locations on the light guide panel before light emission occurs. These units proactively redirect light into areas that would otherwise be dark, eliminating the need to exclude any distance d from the light sources and thereby maximizing the effective screen area while ensuring brightness uniformity.

Inventive Principle:
Principle #10Preliminary action

3Area of stationary object

If light sources are arranged closer together, then screen area is increased, but dark portions between sources increase

Engineering Contradiction:
Improvescreen areaVSAvoiddark portion reduction
Core Design Contradiction:
Area of stationary objectVSIllumination intensity

Solution Approach 1:

The patent addresses this contradiction by implementing dark portion reducing units with specific geometric features (oblique surfaces, grooves, or conical structures) at localized positions between adjacent light sources. These units provide targeted light redirection precisely where dark portions form due to close spacing, enabling high-density light source arrangement that maximizes screen area while maintaining brightness uniformity through local optical correction.

Inventive Principle:
Principle #3Local quality

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 effectively reduces dark portions, achieving uniform brightness and increasing the usable screen area by redirecting light from the edges, thereby improving display quality and enabling miniaturization of the backlight unit.

Implementation Method 1

at least one dark portion reducing unit that is formed on the incidence surface between the locations for adjacent pairs of the light sources and at the edges at both ends of the incidence surface, and reflects the light incident from the light sources

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

an upper surface transmitting a portion of incident light and reflecting the rest of the incident light

Methodology Applied
Scientific EffectTransmission:

Implementation Method 3

an upper surface transmitting a portion of incident light and reflecting the rest of the incident light

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 4

a lower surface facing the upper surface and reflecting the light incident from the incidence surfaces and dark portion reducing units

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP1808716B1Light guide panel and display device employing the same
Publication Date: 2012.04.18 SAMSUNG LED CO LTD
  • EP1808716B1 patent drawingFigure 1~2
  • EP1808716B1 patent drawingFigure 3~4
  • EP1808716B1 patent drawingFigure 5~6

AI summary

Provided are a light guide panel (110) and a display device employing the same. The light guide panel includes: an incidence surface (102) facing a plurality of light sources (100) separated apart a predetermined distance; at least one dark portion reducing unit (105) that is formed on the incidence surface between adjacent pairs of the slight sources and at both edges of the incidence surface, and reflects the light incident from the light sources to reduce the creation of dark portion units; an upper surface transmitting a portion of incident light and reflecting the rest of the incident light; and a lower surface facing the upper surface and reflecting the light incident from the incidence surfaces and dark portion reducing units. The light guide panel includes the dark portion reducing units to reduce the distance between the light source and the light source and thus reduce the size of a useless portion of a screen caused by dark portions.