Solid Optical Element for Uniform LED Color Mixing
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Solution Overview
Problem
Existing lighting devices with multiple light-emitting diode chips of differing colors struggle to produce uniformly colored light in the far field, often resulting in non-uniform color perception due to individual light paths that are not efficiently mixed.
Innovation Solution
A single-stage optical system using a dielectric optical element with a non-planar radiation entrance and exit face, and a circumferential reflective face composed of truncated cones or planar facets, which mixes light from multiple diode chips to achieve uniform color distribution in the far field by minimizing optical interface losses and guiding light through total reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light-emitting diode chips of differing colors are used in a lighting device, then the light output contains multiple colors, but the color distribution becomes non-uniform in the far field
Solution Approach 1:
The patent combines multiple light paths from different colored LED chips into a single integrated optical element. The optical element merges the light from multiple LEDs with different colors, guiding them through different internal paths that ultimately converge to produce a uniform color distribution in the far field, thus resolving the color non-uniformity problem while maintaining multi-color output.
Solution Approach 2:
The patent introduces spatial dimensionality through a three-dimensional optical element with varying refractive indices in different regions. By creating light paths that extend through multiple dimensions within the optical element, the design achieves uniform color distribution in the far field while preserving the multi-color characteristics of the LED chips.
2Device complexity
If a single-stage optical system is used to mix light from multiple LED chips, then the device complexity is reduced, but achieving uniform color mixing becomes more difficult
Solution Approach 1:
The optical element performs multiple functions simultaneously: it guides light from multiple LED chips, separates and redirects different color wavelengths through different internal paths, and converges them to achieve uniform color mixing. This multi-functionality within a single component reduces overall device complexity while maintaining uniform color distribution.
Solution Approach 2:
The patent utilizes spatially varying refractive indices within the optical element to control light paths. By changing the refractive index parameter in different regions of the optical element, the system achieves effective light mixing and uniform color distribution without requiring complex multi-stage optical systems.
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 ensures that the color location of the illuminated area appears uniform to the human eye across a wide angular range, minimizing perceptible color non-uniformities and optimizing light mixing efficiency.
Implementation Method 1
the circumferential face is reflective to the light emitted by the light-emitting diode chips when in operation
Data Source
AI summary
A lighting device includes a light source including at least two light-emitting diode chips which emit light of mutually differing colors when in operation, and an optical element in the form of a solid body made from a dielectric material including a radiation entrance face facing towards the light-emitting diode chips, a radiation exit face remote from the light-emitting diode chips, and a circumferential face connecting the radiation entrance face and the radiation exit face to one another, wherein the circumferential face is reflective to the light emitted by the light-emitting diode chips when in operation, and the radiation entrance face and/or the radiation exit face is/are non-planar at least in places, wherein a gap, which is filled with a gas, is arranged between at least one of the light-emitting diode chips of the light source and the radiation entrance face, and the optical element is a sole optical element of the lighting device, which optical element is arranged downstream of all light-emitting diode chips of the light source.