Grooved Reflective Light Guide for Uniform Street Lighting

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Solution Overview

Problem

Achieving uniform luminance distribution along the longitudinal direction of a road becomes increasingly challenging as the distance between streetlamps increases, while there is an economic incentive to reduce street lighting costs by spacing them further apart.

Innovation Solution

A light guide element with a reflective surface featuring mutually parallel grooves that spread the light distribution pattern of second light beams in the direction between spatial planes, ensuring total reflection and uniform luminance distribution, particularly in street lighting applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the distance between adjacent streetlamps is increased to reduce costs, then the economic cost of street lighting is reduced, but the uniformity of luminance distribution along the road deteriorates

Engineering Contradiction:
Improvecost of street lightingVSAvoiduniformity of luminance distribution
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The reflective surface is segmented into multiple grooves that divide and redirect light beams in specific directions. This segmentation allows light to be distributed more uniformly along the road, compensating for increased spacing between streetlamps and maintaining luminance uniformity while reducing the number of streetlamps needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The grooves on the reflective surface create localized light redirection zones with specific angular distributions. By designing grooves with particular geometries and orientations, the light distribution is optimized for specific road sections, ensuring uniform illuminance even when streetlamps are spaced farther apart.

Inventive Principle:
Principle #3Local quality

2Productivity

If the distance between adjacent streetlamps is increased, then the number of streetlamps is reduced, but the luminance distribution uniformity in the longitudinal direction becomes insufficient

Engineering Contradiction:
Improvelighting coverage efficiencyVSAvoidluminance distribution uniformity
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The grooves on the reflective surface redirect light not only in the vertical direction but also in the longitudinal direction along the road. This dimensional redirection of light beams ensures that even with fewer streetlamps, the light distribution along the longitudinal axis remains uniform, improving lighting coverage efficiency.

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

3Stability of the object's composition

If a reflective surface with grooves is used to spread light distribution, then the luminance uniformity is improved, but the device complexity increases

Engineering Contradiction:
Improveluminance distribution uniformityVSAvoidcomplexity of light guide element
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The reflective surface incorporates grooves that create a porous-like structure for light redirection. This groove structure, while adding some complexity, provides an effective and relatively simple method to achieve uniform light distribution compared to more complex optical systems, as the grooves can be integrated into the existing light guide element structure.

Inventive Principle:
Principle #31Porous materials

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 light guide element with grooves on the reflective surface facilitates a sufficiently uniform luminance distribution along the road, even at increased streetlamp spacings, optimizing lighting efficiency and reducing costs.

Implementation Method 1

transparent material on a route of the first light beams for modifying a light distribution pattern of the first light beams, where a refractive index of the transparent material is greater than unity

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

The geometrical forms of the cavity 109 and the refractive index of the transparent material 107 are selected so that the total reflection takes place on the reflective surface 108

Methodology Applied
Scientific EffectTotal reflection: Total Internal Reflection

Data Source

PatentEP2776883B1Light guide element for modifying the light distribution pattern of a light source
Publication Date: 2017.07.26 LEDIL
  • EP2776883B1 patent drawingFigure 1a~1d
  • EP2776883B1 patent drawingFigure 1e~1f
  • EP2776883B1 patent drawingFigure 2a~2b

AI summary

A light guide element (201) for modifying a light distribution pattern of a light source (202) is presented. The light source radiates first light beams to a first quarter-space (203) and second light beams to a second quarter-space (204), where the first and second quarter-spaces are defined by mutually perpendicular spatial planes (xy, xz) and one (xy) of the spatial planes constitutes a planar boundary between the first and second quarter-spaces. The light guide element comprises transparent material (207) on a route of the first light beams for modifying the light distribution pattern of the first light beams and a reflective surface (208) for reflecting at least a part of the second light beams to the first quarter-space. A surface of solid material on a route of the second light beams comprises grooves (213) for spreading the light distribution pattern of the second light beams in the direction ( ±y) of the section line between the spatial planes.