Crossed Prism Optical Sheet for Backlight Uniformity

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Solution Overview

Problem

Conventional prism sheets for backlight units exhibit poor condensing efficiency in one direction due to directivity, leading to differences in viewing angles between horizontal and vertical directions, and increasing manufacturing costs when attempting to address this with crossed prism sheets.

Innovation Solution

An optical sheet with crossed prism patterns having first and second condensing axes that intersect diagonally relative to the light source arrangement direction, providing balanced condensing effects in both vertical and horizontal directions, fabricated using ultraviolet curable resin and a transparent base film with a negative prism pattern.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a conventional prism sheet with unidirectional prism peaks is used, then light condensing is achieved in a specific direction, but viewing angle characteristics differ between horizontal and vertical directions and condensing efficiency deteriorates in the longitudinal direction

Engineering Contradiction:

Improvelight condensing efficiencyVSAvoidviewing angle uniformity

Core Design Contradiction:

Illumination intensityVSEase of operation

Solution Approach 1:

The optical sheet is segmented into multiple prism patterns with different orientations. Specifically, first prism patterns have peaks extending in a first direction while second prism patterns have peaks extending in a second direction different from the first direction. This segmentation allows each prism pattern to contribute to condensing light in different directions, achieving uniform viewing angle characteristics while maintaining high condensing efficiency.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If multiple optical sheets are arranged to cross each other to improve viewing angles, then viewing angle characteristics are enhanced, but manufacturing costs and device complexity increase

Engineering Contradiction:

Improveviewing angle characteristicsVSAvoidnumber of optical sheets

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

Multiple prism patterns that would traditionally require separate optical sheets are merged into a single optical sheet. The sheet contains both first prism patterns with peaks in a first direction and second prism patterns with peaks in a second direction, all within one substrate. This merging maintains the viewing angle enhancement benefits while reducing device complexity and manufacturing costs by eliminating the need for multiple stacked sheets.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If multiple optical sheets are arranged to cross each other to achieve balanced condensing, then viewing angle uniformity improves, but manufacturing costs increase

Engineering Contradiction:

Improveviewing angle uniformityVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The invention combines multiple prism patterns into a single optical sheet structure, reducing the total number of components that need to be manufactured and assembled. By integrating first prism patterns and second prism patterns in one sheet, manufacturing steps are reduced and assembly complexity is lowered, thereby decreasing overall manufacturing cost while maintaining viewing angle uniformity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The optical sheet is segmented to include different prism patterns with various peak directions within a single substrate. This segmentation allows the sheet to provide balanced condensing effects in multiple directions without requiring multiple separate sheets, thus maintaining viewing angle uniformity while simplifying manufacturing and reducing costs.

Inventive Principle:

Principle #1Segmentation

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 enhances the contrast ratio and viewing angle uniformity, reduces manufacturing costs, and minimizes light leakage, while maintaining balanced luminance distribution across directions.

Implementation Method 1

fabricated using ultraviolet curable resin and a transparent base film with a negative prism pattern

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS8366287B2Optical sheet and backlight unit using the same

Publication Date: 2013.02.05 SAMSUNG DISPLAY CO LTD

AI summary

Disclosed are an optical sheet, which includes a prism pattern having condensing axes crossing each other in diagonal directions with respect to an arrangement direction of light sources, thereby achieving an enhanced contrast ratio without a reduction in viewing angle and an increase in costs, and a backlight unit using the same. The optical sheet includes a plurality of crossed prism patterns each having a first condensing axis and a second condensing axis crossing each other in diagonal directions with respect to an arrangement direction of a light source.