Trapezoidal LED Optical Element for Asymmetrical Wallwash

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Solution Overview

Problem

Existing wallwashers with LED light sources face challenges in achieving reproducible and compact asymmetrical light distribution due to large optical systems and complex manufacturing tolerances, which result in inconsistent illumination.

Innovation Solution

An elongate optical element with a trapezoidal cross-section featuring a curved light entry area, a lens-like free-form optics-covered light emission surface, and convexly curved side surfaces described by third-order or higher-order polynomials, combined with matrix-like free-form optics on the exit surface, allows precise control of light distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If mechanically formed trough reflectors are used to achieve asymmetrical light distribution, then the desired two-dimensional light distribution on the wall is achieved, but the optical system becomes relatively large and manufacturing tolerances negatively affect reproducibility

Engineering Contradiction:
Improvelight distribution uniformityVSAvoidoptical system size
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent combines the light-guiding function and the light-shaping function into a single integrated optical element. The optical element has a light entry area that receives light from the LED circuit board and a light emission surface that emits the shaped light, merging what were previously separate components (reflector and light guide) into one compact unit. This reduces the overall optical system size while maintaining the asymmetrical light distribution capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The optical element employs curved surfaces including a curved bottom surface in the light entry area and a curved light emission surface with free-form optics. These curved geometries are specifically designed to control light propagation paths and achieve the desired asymmetrical light distribution pattern on the wall, replacing the mechanically formed trough reflector approach.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Illumination intensity

If mechanically formed trough reflectors are used to achieve asymmetrical light distribution, then the desired two-dimensional light distribution on the wall is achieved, but manufacturing tolerances have a negative effect on reproducibility

Engineering Contradiction:
Improvelight distribution uniformityVSAvoidreproducibility of light distribution
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The optical element employs curved surfaces including a curved bottom surface in the light entry area and a curved light emission surface with free-form optics. These curved geometries are specifically designed to control light propagation paths and achieve the desired asymmetrical light distribution pattern on the wall, replacing the mechanically formed trough reflector approach.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent specifies that the curved surfaces follow curves describable by third-order or higher-order polynomials. This mathematical characterization of the surface geometry allows for precise control of light distribution characteristics while providing a clear manufacturing specification that reduces tolerance variability and improves reproducibility across production batches.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If linear LED circuit boards with trough reflectors are used, then area lighting for wall illumination is achieved, but the optical system requires relatively large dimensions

Engineering Contradiction:
Improvewall illumination capabilityVSAvoidoptical system length
Core Design Contradiction:
Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent combines the light-guiding function and the light-shaping function into a single integrated optical element. The optical element has a light entry area that receives light from the LED circuit board and a light emission surface that emits the shaped light, merging what were previously separate components (reflector and light guide) into one compact unit. This reduces the overall optical system size while maintaining the asymmetrical light distribution capability.

Inventive Principle:
Principle #5Merging (Combining)

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 enables efficient and reproducible asymmetrical light distribution with a compact optical system, ensuring uniform illumination of vertical surfaces while minimizing production tolerances and overall size, resulting in high-quality surface lighting.

Implementation Method 1

the bottom surface, the basic shape of the light-emitting surface and the two side surfaces are each convexly curved, with the bottom surface, the basic shape of the light-emitting surface and the two side surfaces each following curves that can be described by third-order or higher-order polynomials

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

a light emission surface opposite the light entry area, which has a curved basic shape overlaid with lens-like free-form optics

Methodology Applied
Scientific EffectLens focusing: Lens

Data Source

PatentEP3112747B1Optical element for influencing the light emitted by an extended illumination source
Publication Date: 2018.05.23 ZUMTOBEL LIGHTING GMBH
  • EP3112747B1 patent drawingFigure 1~2
  • EP3112747B1 patent drawingFigure 3
  • EP3112747B1 patent drawingFigure 4

AI summary

An optical element (10) for influencing the light emission of an elongated light source, in particular one or more elongated LED boards (50), extends in a longitudinal direction and has an approximately trapezoidal cross-section with a light entry area (11) facing the light source, which has a recess (12) with a curved bottom surface (13), a light emission surface (15) opposite the light entry area (11), which has a curved basic shape (16) to which lens-like freeform optics (17) are superimposed, and two curved side surfaces (21, 22) extending from the light entry area (11) to the light emission surface (15).