Thin Light Guide Plate with Projections for LCD Backlight

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Solution Overview

Problem

Liquid crystal display devices face challenges in miniaturization due to the difficulty in manufacturing thin light guide plates and light leakage from the light source, which affects brightness uniformity.

Innovation Solution

A liquid crystal display device design featuring a thin light guide plate with a reflection face and projections, combined with a light shielding member, such as a black two-sided adhesive tape, to prevent light leakage and enhance brightness uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If injection molding is used to manufacture light guide plates, then manufacturing efficiency is improved, but the light guide plate thickness cannot be reduced below 1 mm

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidlight guide plate thickness

Core Design Contradiction:

ProductivityVSLength of moving object

Solution Approach 1:

The patent replaces the injection molding process with a lamination process. Instead of injecting molten resin into a mold, the light guide plate is formed by laminating a light guide plate material layer onto a substrate. This substitution of manufacturing methodology enables production of ultra-thin light guide plates (0.1-1.0 mm thickness) that cannot be achieved through conventional injection molding, while maintaining manufacturing efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Length of stationary object

If a light source is provided on the side face of the light guide plate to reduce backlight thickness, then overall thickness is reduced, but light leaks into the screen causing brightness non-uniformity

Engineering Contradiction:

Improvebacklight thicknessVSAvoidlight leakage causing brightness non-uniformity

Core Design Contradiction:

Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the harmful stray light that leaks from the light source before it can reach the screen. A light shielding member is positioned between the light source and the liquid crystal panel to intercept and block the leaked light. This extraction of the harmful element (stray light) prevents brightness non-uniformity while maintaining the thin backlight structure.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a light shielding member as an intermediary element between the light source and the liquid crystal panel. This intermediary component specifically blocks the harmful stray light from reaching the screen, mediating between the light source and display panel to prevent brightness non-uniformity while allowing the thin backlight design to function properly.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Length of moving object

If the light guide plate is made thinner to reduce device thickness, then miniaturization is achieved, but manufacturing difficulty increases due to insufficient resin filling and mold removal issues

Engineering Contradiction:

Improvelight guide plate thicknessVSAvoidmanufacturing difficulty

Core Design Contradiction:

Length of moving objectVSEase of manufacture

Solution Approach 1:

The patent replaces the injection molding process with a lamination process. Instead of injecting molten resin into a mold (which fails for thicknesses below 1 mm due to insufficient filling and removal difficulties), the light guide plate is formed by laminating a light guide plate material layer onto a substrate. This substitution eliminates the manufacturing challenges associated with ultra-thin injection molded parts while enabling production of light guide plates with thicknesses of 0.1-1.0 mm.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables the production of liquid crystal display devices with light guide plates thinner than 1 mm, effectively preventing light leakage and improving brightness uniformity by using a light shielding member to block stray light.

Implementation Method 1

a light shielding member is formed between the liquid crystal panel and the light guide plate... effectively preventing light leakage

Methodology Applied

Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 2

the light guide plate including a reflection face on a back face thereof

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS8228464B2Liquid crystal display device

Publication Date: 2012.07.24 MAGNOLIA PURPLE CORP

AI summary

A liquid crystal display device including a thin light guide plate and capable of preventing light leakage from light sources is provided. The light guide plate is formed of a sheet. On a back face of the light guide plate, a first projection and a second projection that protrude outwardly and a reflection face provided between the first projection and the second projection are provided. The light sources are disposed on a side face of the light guide plate. A light entering portion is disposed on the side face where the light source is provided. A thin film portion is included between the light sources adjacent to each other in the light entering portion.