Hexagonal Retroreflective Element with Segmented Faces

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Solution Overview

Problem

Existing retroreflective articles with hexagonal cube corner elements lack effective methods for achieving excellent observation angle characteristics, which are crucial for applications such as traffic signs and liquid crystal display devices.

Innovation Solution

The hexagonal cube corner retroreflective element is designed with three quadrilateral reflective lateral faces that share an apex, featuring vertical angle deviations and secondary reflective lateral faces, allowing for improved observation angle characteristics by providing multiple combinations of vertical angle deviations and tilting the optical axis to enhance retroreflective efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional hexagonal cube corner retroreflective elements are used, then retroreflective efficiency is maintained, but observation angle characteristics are insufficient

Engineering Contradiction:
Improveobservation angle characteristicsVSAvoidelement structure complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The retroreflective element is divided into multiple reflective lateral faces (first, second, third, fourth, fifth, and sixth faces) with different vertical angle deviations. Each face is segmented to provide specific reflection characteristics, allowing the overall element to achieve improved observation angle characteristics while maintaining retroreflective efficiency through the coordinated arrangement of these segmented faces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different vertical angle deviations are assigned to different reflective lateral faces (e.g., first face has a first vertical angle deviation, second face has a second vertical angle deviation, etc.). This local differentiation of geometric properties allows each face to contribute specifically to widening the observation angle in particular directions, achieving superior overall observation angle characteristics.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If the optical axis is tilted to improve entrance angle characteristics, then entrance angle characteristics are improved, but rotation angle characteristics deteriorate

Engineering Contradiction:
Improveentrance angle characteristicsVSAvoidrotation angle characteristics
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The optical axis is deliberately tilted relative to the normal of the common plane of the retroreflective element, creating an asymmetric configuration. This asymmetric tilt improves entrance angle characteristics by broadening the acceptance angle for incident light. The asymmetry is compensated by the specific arrangement of vertical angle deviations across the six reflective faces, which maintains rotation angle characteristics.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The vertical angle deviations of the reflective lateral faces are specifically adjusted (changed) to compensate for the optical axis tilt. By modifying these geometric parameters, the element maintains reliable rotation angle characteristics while benefiting from the improved entrance angle characteristics provided by the tilted optical axis.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If multiple combinations of vertical angle deviations are provided, then observation angle characteristics are improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveobservation angle characteristicsVSAvoidvertical angle deviation precision
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The provision of multiple combinations of vertical angle deviations across six segmented reflective faces achieves improved observation angle characteristics. The segmentation allows for distributed control of reflection angles, where small deviations in individual faces can be compensated by the collective arrangement, thereby reducing the stringent precision requirements compared to a monolithic design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The retroreflective element is designed to provide multiple functions simultaneously: maintaining retroreflective efficiency, improving observation angle characteristics, and accommodating manufacturing tolerances. The multi-face configuration with varying vertical angle deviations creates a universal design that achieves multiple performance goals without requiring extreme manufacturing precision in any single parameter.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 design achieves uniform observation angle characteristics and improved retroreflective efficiency, allowing for wider divergence of retroreflected light and enhanced performance in applications requiring broad observation angles.

Implementation Method 1

a first retroreflective element group including a plurality of hexagonal cube corner retroreflective elements, in which reflective lateral faces of the hexagonal cube corner retroreflective elements are oriented in a first direction, and a second retroreflective element group including a plurality of hexagonal cube corner retroreflective elements, in which reflective lateral faces of the hexagonal cube corner retroreflective elements are oriented in a second direction

Methodology Applied
Scientific EffectRetroreflection: Retroreflector

Implementation Method 2

three quadrilateral reflective lateral faces that share an apex, featuring vertical angle deviations and secondary reflective lateral faces

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

providing multiple combinations of vertical angle deviations and tilting the optical axis to enhance retroreflective efficiency... allowing for wider divergence of retroreflected light and enhanced performance in applications requiring broad observation angles

Methodology Applied
Scientific EffectLight divergence: Dispersion (of waves)

Data Source

PatentEP2431774B1Hexagonal corner cube retroreflective article
Publication Date: 2019.03.27 NIPPON CARBIDE KOGYO KK
  • EP2431774B1 patent drawingFigure 1~2
  • EP2431774B1 patent drawingFigure 3~4
  • EP2431774B1 patent drawingFigure 5A~5B

AI summary

There is provided a hexagonal cube corner retroreflective article with excellent observation angle characteristics. The hexagonal cube corner retroreflective article has a set of a large number of hexagonal cube corner retroreflective elements. In the hexagonal cube corner retroreflective element, at least one reflective lateral face (face a, face b, and/or, face c) is divided into a pair of an upper secondary reflective lateral face (face a1, face b1, and/or face c1) and a lower secondary reflective lateral face (face a2, face b2, and/or face c2) partitioned by a line segment (EF, FD, and/or DE) connected by apexes (E, F, and/or D) constituting that reflective lateral face, in which two secondary reflective lateral faces constituting the pair of the secondary reflective lateral faces are not on the same plane.