Integrated Prism Sheet for LCD Backlight Modules

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Solution Overview

Problem

Conventional prism sheets in liquid crystal display (LCD) backlight modules are prone to scratches and unstable engagement due to their triangular design, increasing module thickness and complexity, and limiting view angles.

Innovation Solution

A prism sheet comprising two sub-prism sheets with different refractive indices, where one sheet has protrusions and the other has corresponding recesses, bonded together with ultraviolet curing adhesive, eliminating the need for a light guide plate and reducing engagement instability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If two prism sheets are provided to achieve light concentration in both horizontal and vertical directions, then the light concentration effect is improved, but the thickness of the backlight module and the number of parts are increased

Engineering Contradiction:

Improvelight concentration effectVSAvoidnumber of parts

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent merges two separate prism sheets into a single integrated prism sheet by bonding a first prism sheet and a second prism sheet together. The first prism sheet has prisms extending in the first direction, while the second prism sheet has prisms extending in the second direction (perpendicular to the first direction). This integration achieves light concentration in both horizontal and vertical directions while reducing the number of parts from two separate sheets to one unified structure.

Inventive Principle:

Principle #5Merging (Combining)

2Illumination intensity

Engineering Contradiction:

Improvelight concentration effectVSAvoidthickness of backlight module

Core Design Contradiction:

Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent implements a nested structure where the second prism sheet is bonded to the first prism sheet, with the protrusions of one sheet fitting into the recesses of the other sheet. This nesting arrangement allows the prisms of both sheets to be integrated in a compact configuration, achieving light concentration in multiple directions while minimizing the overall thickness increase compared to stacking two separate prism sheets.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Object-affected harmful factors

If a reverse prism sheet cooperates with a light guide plate having a prism structure, then the mutual scratch degree is mitigated, but the contact surfaces for engagement are very small causing unstable engagement

Engineering Contradiction:

Improvemutual scratch degreeVSAvoidengagement stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent segments the single prism sheet into two functional layers: a first prism sheet and a second prism sheet bonded together. The first prism sheet engages with the light guide plate to reduce scratching, while the second prism sheet provides additional engagement surfaces and structural support. This segmentation increases the total contact surface area for engagement, improving engagement stability while maintaining the scratch-mitigation benefit.

Inventive Principle:

Principle #1Segmentation

4Illumination intensity

If a triangular cross-section prism sheet is used, then light concentration is achieved, but a limited view angle is caused

Engineering Contradiction:

Improvelight concentrationVSAvoidview angle

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The patent employs asymmetric prism configurations by combining a first prism sheet with prisms extending in the first direction and a second prism sheet with prisms extending in the second direction (perpendicular to the first). This asymmetric, multi-directional prism arrangement broadens the view angle compared to a single triangular cross-section prism sheet, allowing light to be effectively concentrated and viewed from multiple angles simultaneously.

Inventive Principle:

Principle #4Asymmetry

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 prevents scratches and unstable engagement, enhances light concentration and view angles, simplifies assembly, and reduces module thickness by integrating the prism sheets, while maintaining optical performance.

Implementation Method 1

the first sub-prism sheet and the second sub-prism sheet are made of materials having different refractive indexes from each other

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

the first sub-prism sheet and the second sub-prism sheet are bonded by coating ultraviolet curing adhesive and curing the adhesive by UV rays

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Data Source

PatentUS8698975B2Prism sheet, backlight module and liquid crystal display device thereof

Publication Date: 2014.04.15 BOE TECHNOLOGY GROUP CO LTD

AI summary

The embodiments of present disclosure disclose a prism sheet, a backlight module and a liquid crystal display device thereof. The prism sheet comprises a first sub-prism sheet and a second sub-prism sheet with faces being closely bonded with each other, the first sub-prism sheet having a plurality of protrusions on the surface being bonded with the second sub-prism sheet, and the second sub-prism sheet having recesses on the surface being bonded with the first sub-prism sheet corresponding to the protrusions, wherein the first sub-prism sheet and the second sub-prism sheet are made of materials having different refractive indexes.