Prismatic Light Guide for Incandescent Retrofit

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Solution Overview

Problem

Conventional LED light sources have limited optical efficiency and require additional reflective materials and larger dimensions to achieve a light intensity distribution similar to incandescent sources, increasing costs and manufacturing complexity.

Innovation Solution

An optical element with a prismatic surface inside a light guide that reflects light back into the guide, minimizing multireflection and allowing for smaller dimensions, eliminating the need for additional reflective foils, and using a reflector with a concave surface to achieve a full-sphere light distribution similar to incandescent sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If reflective foils or coatings are used to achieve high optical efficiency, then optical efficiency is improved, but device cost and manufacturing complexity increase

Engineering Contradiction:
Improveoptical efficiencyVSAvoidmanufacturing complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The light guide structure itself provides the reflective function through its geometric design. The internal surfaces and angles of the light guide act as natural reflectors, eliminating the need for separate reflective foils or coatings. This self-service approach maintains high optical efficiency while simplifying manufacturing.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the geometric parameters of the light guide, specifically using a 45-degree angle configuration for internal surfaces. This parameter optimization enables efficient light reflection and redirection without requiring additional reflective materials, thereby reducing both cost and manufacturing complexity.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If reflective foils or coatings are used to achieve high optical efficiency, then optical efficiency is improved, but device dimensions increase

Engineering Contradiction:
Improveoptical efficiencyVSAvoidlight guide dimensions
Core Design Contradiction:
Loss of energyVSVolume of moving object

Solution Approach 1:

By optimizing the geometric parameters of the light guide, particularly using 45-degree angles for internal surfaces, the invention achieves high optical efficiency within a compact form factor. The precise angular configuration maximizes light reflection efficiency without requiring additional space for separate reflective components.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The reflective function is merged into the light guide structure itself. The light guide serves dual purposes: guiding light transmission and providing reflection through its geometric design. This integration eliminates the need for separate reflective foils or coatings, reducing overall device dimensions.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If conventional LED configuration is used, then manufacturing is simpler, but light distribution is limited to hemisphere

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidlight distribution range
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The invention employs curved or angled internal surfaces within the light guide at 45-degree configurations. This geometric curvature enables light to be redirected in multiple directions, transforming the conventional hemispherical light distribution into a full-sphere distribution pattern, while maintaining manufacturing simplicity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The light guide structure adds spatial dimensionality to light distribution by using angled surfaces that redirect light in three-dimensional space. This geometric configuration enables full-sphere light emission (4π steradians) from a conventional LED that would normally only emit into a hemisphere (2π steradians).

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 maintains or improves optical efficiency while reducing costs and manufacturing complexity, allowing for smaller dimensions and a light distribution similar to incandescent sources, overcoming the limitations of conventional LED light sources.

Implementation Method 1

The angle of the prisms to the axial direction are chosen such that it is large enough for total internal reflection of light incident on the prisms

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a reflector arranged at the other end of the light guide capable of reflecting light incident on the reflector

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2386043B1Optical element with led, and light source comprising the same
Publication Date: 2016.04.13 SIGNIFY HOLDING BV
  • EP2386043B1 patent drawingFigure 1~2b
  • EP2386043B1 patent drawingFigure 3a~3b
  • EP2386043B1 patent drawingFigure 4~5

AI summary

The present invention relates to an optical element including a light guide, into which light from one or more light-emitting diodes in a light unit arranged at one end of the light guide is injected, and a reflector arranged at the other end of the light guide capable of reflecting light incident on the reflector. The light guide further includes a prismatic surface comprising a plurality of prisms, each prism being arranged at an angle to an axial direction of the light guide, for guiding the light emitted from the light unit towards the output end of the light guide. The present invention also relates to a light source including an optical element according to the present invention, the light source being arranged for retrofitting into a luminaire employing an incandescent light source.