Light Guide Plate Thickness Segmentation for Backlight Alignment

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Solution Overview

Problem

The challenge lies in creating a liquid crystal display device with a light guide plate that can efficiently introduce light from a light source, as existing methods like projection molding struggle to achieve dimensions thinner than 1 mm due to incomplete resin filling and difficulties in mold removal, leading to misalignment and reduced light usage efficiency.

Innovation Solution

A back light unit with a light guide plate featuring a light introducing portion and a lens on the light incident surface to refract and scatter light, combined with a light non-introducing portion, which allows for effective light guidance and distribution, ensuring sufficient light introduction from the light source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If projection molding method is used to manufacture light guide plate, then manufacturing process is simple, but thickness cannot be reduced below 1 mm due to insufficient resin filling and difficulty in mold removal

Engineering Contradiction:

Improvethickness of light guide plateVSAvoidmanufacturing process complexity

Core Design Contradiction:

Length of moving objectVSEase of manufacture

Solution Approach 1:

The light guide plate is divided into multiple sections with different thicknesses: a first light guide plate portion with thickness of 1 mm or less, and a second light guide plate portion with greater thickness. This segmentation allows the thin portion to achieve reduced thickness while the thicker portion provides structural support and facilitates manufacturing processes like mold removal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the light guide plate are given different thickness properties to serve different functions. The central region has reduced thickness for overall device thinning, while peripheral or specific structural regions maintain greater thickness for manufacturing feasibility and structural integrity.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If punching method is used to cut out light guide plate periphery, then manufacturing is simplified, but dimension accuracy is insufficient causing misalignment of light introducing structure

Engineering Contradiction:

Improvedimension accuracy of light introducing structureVSAvoidcutting process simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

A positioning protrusion is formed on the light introducing structure before the punching process. This protrusion engages with a corresponding positioning recess in the punch die, establishing precise positioning that ensures the light introducing structure is accurately formed even during the simplified punching operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The positioning protrusion and recess act as an intermediary mechanism between the light introducing structure and the punch die. This intermediary feature transfers and maintains precise dimensional relationships through the punching process, ensuring alignment accuracy without complicating the overall manufacturing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If light introducing structure is misaligned due to punching inaccuracies, then light introduction efficiency decreases, but this contradiction arises from the need to simplify manufacturing

Engineering Contradiction:

Improvelight introduction efficiencyVSAvoidmanufacturing simplicity

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The positioning protrusion is formed in advance on the light introducing structure to establish accurate positioning before light introduction occurs. This preliminary positioning feature ensures that even when using simplified punching methods, the light introducing structure remains properly aligned with the light source, maintaining high light introduction efficiency.

Inventive Principle:

Principle #10Preliminary action

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 configuration enables the production of a liquid crystal display device with improved light introduction efficiency, overcoming the limitations of traditional methods by ensuring precise alignment and enhanced light usage, even in thinner designs.

Implementation Method 1

a lens on the light incident surface to refract and scatter light

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a lens on the light incident surface to refract and scatter light

Methodology Applied

Scientific EffectScattering: Scattering

Data Source

PatentUS9557468B2Liquid crystal display device

Publication Date: 2017.01.31 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

A back light unit includes a light guide plate having at least one light introducing portion and a light exit portion, the front surface of the light exit portion being a light exit surface, and a light source facing the light guide plate and emitting light in a light emitting direction. The at least one light introducing portion includes a first portion and a second portion which is connected to the light exit portion, and in which the second portion spreads wider than the first portion in plan view.