LED Optical System Reducing Hard Shadow Edges

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Solution Overview

Problem

Existing LED light systems with lenses and pot-like reflectors often produce undesirable hard shadow edges and glare due to inefficient light reflection, which affects the pleasantness and effectiveness of the light appearance on surfaces.

Innovation Solution

An optical system comprising a lens and a pot-like reflector with inwardly facing, reflective surface areas, where the reflector's shape defines a main axis and forms a light exit opening, with the lens positioned opposite to the reflector, allowing most light to pass through without reflection, and using diffusely reflective or scattering surfaces to minimize shadow edges and glare.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a pot-like reflector is used to reflect light from the LED light source, then light distribution can be influenced, but hard shadow edges and glare are produced

Engineering Contradiction:
Improvelight distributionVSAvoidhard shadow edges and glare
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The reflector is designed with a specific bell shape in axial section and a flat front surface that creates a shadow-free zone. This local geometric quality change allows the reflector to redirect light in a controlled manner, influencing light distribution while avoiding the formation of hard shadow edges and glare that would occur with conventional reflector shapes.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The reflector features a curved bell shape in axial section with a flat front surface. This specific curvature design enables the reflector to redirect light rays at appropriate angles to achieve desired light distribution patterns while the flat front surface prevents direct reflection of light that would cause glare and hard shadows.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Illumination intensity

If the reflector strongly influences light emission, then light distribution can be controlled, but the lens cannot primarily determine the light appearance

Engineering Contradiction:
Improvelight distribution controlVSAvoidlens determination of light appearance
Core Design Contradiction:
Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The reflector is designed to provide only partial action in light redistribution. By creating a shadow-free zone and using a flat front surface, the reflector performs just enough light redirection to prevent unwanted effects, while allowing the lens to perform its primary function of shaping the light appearance without excessive interference from the reflector.

Inventive Principle:
Principle #16Partial or excessive action

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 system primarily determines light emission by the lens, reducing hard shadow edges and ensuring a minimum shielding angle, while allowing for fine-tuning of light distribution, resulting in a more pleasant and efficient light appearance.

Implementation Method 1

a lens (2) for influencing the light

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

The reflective surface areas of the reflector are preferably diffusely reflective or scattering

Methodology Applied
Scientific EffectDiffuse reflection: Reflection

Implementation Method 3

The reflective surface areas of the reflector are preferably diffusely reflective or scattering

Methodology Applied
Scientific EffectScattering: Scattering

Data Source

PatentEP3058411B1Optical system for an LED light source and luminaire comprising such an optical system
Publication Date: 2021.12.01 ZUMTOBEL LIGHTING GMBH
  • EP3058411B1 patent drawingFigure 1
  • EP3058411B1 patent drawingFigure 2
  • EP3058411B1 patent drawingFigure 3

AI summary

The invention relates to an optical system for influencing light emitted by an LED light source (1). The optical system comprises a lens (2) for influencing the light, and a pot-like reflector (3), the shape of which defines a principal axis (A). The reflector (3) has inwardly facing, reflective surface regions (31) and forms a light exit opening (4) with respect to the principal axis (A) on a first side. In this case, the lens (2) is arranged on a second side - opposite the first side- of the reflector (3), specifically in such a way that the light after emerging from the lens (2) covers a path to the light exit opening (4) and subsequently leaves the reflector (3) through said light exit opening. The optical system is designed in this case such that a predominant portion of the light on the path between the lens (2) and the light exit opening (4) is not reflected at the reflective surface regions (31) of the reflector (3) and only a further, smaller portion of said light is reflected at the reflective surface regions (31) of the reflector (3). What can be achieved by virtue of this design is, in particular, that the light appearance that can be generated by a luminaire comprising such an optical system exhibits no or at most only reduced undesirable hard shadow edges. In this case, a minimum shielding angle for the light emission can nevertheless be ensured. Moreover, the light distribution can be influenced by the reflector (3).