Optical Element for Uniform LED Surface Illumination
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Solution Overview
Problem
Existing light emitting devices using LEDs suffer from glare and dark spots on flat surfaces due to uneven light distribution, and have high light radiation loss due to improper light reflection and scattering.
Innovation Solution
An optical element with a light incoming section, a first light guiding section containing light scattering particles for multiply-scattering light, and a second light guiding section that launches light in a controlled direction, using a reflecting surface and a prism section to achieve uniform surface luminescence and reduce radiation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is introduced into a tight area at the side part of the LED to be launched from the side part, then the light can be launched from the side of the disk-shaped member, but the central section of the flat surface becomes excessively bright or too dark, resulting in non-uniform illumination
Solution Approach 1:
The disk-shaped member is divided into multiple light guiding sections (first light guiding section and second light guiding section) with different functions. The first light guiding section contains light scattering particles to diffuse light and reduce glare, while the second light guiding section guides light to the reflecting surface. This segmentation allows different regions to perform specialized functions, achieving uniform illumination across the flat surface.
Solution Approach 2:
Different regions of the light guiding member are given different optical properties. The first light guiding section contains light scattering particles to create a diffusing effect, while the second light guiding section has a different refractive index to guide light effectively. This local differentiation of optical properties enables the central section to be uniformly illuminated without excessive brightness or darkness.
2Adaptability or versatility
If the side part of the LED is rough with unevenness, then light launching direction diffuses in a relatively wide angular range, but it becomes hardly possible to control the launched light in a certain direction, resulting in high radiation loss
Solution Approach 1:
The refractive index parameter is changed in different regions of the light guiding member. The second light guiding section has a different refractive index than the first light guiding section, creating optical contrast that enables effective light guidance. This parameter change allows control of light direction despite the rough side part of the LED, reducing radiation loss by directing light toward the reflecting surface.
Solution Approach 2:
The light guiding member acts as an intermediary between the LED and the reflecting surface. It receives light from the rough side part of the LED and guides it through its internal structure to the reflecting surface, controlling the light path and reducing diffusion loss. This intermediary structure enables direction control without requiring a smooth LED surface.
3Illumination intensity
If a reflecting mirror is used to reflect light, then light can be launched from the second surface of the disk-shaped member, but a dark circle appears at the central section of the flat surface
Solution Approach 1:
The solution moves from a two-dimensional reflecting surface to a three-dimensional light guiding structure. Instead of using a flat reflecting mirror that creates a dark circle, the invention uses a volumetric light guiding member with light scattering particles and multiple light guiding sections. This three-dimensional approach distributes light more evenly across the flat surface, eliminating the dark circle defect while maintaining light output.
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 effectively suppresses glare and dark spots, enhances light efficiency, and allows for uniform surface illumination by controlling light distribution and reducing radiation loss.
Implementation Method 1
the first light guiding section contains light scattering particles for multiply-scattering light and generating light which passes through the reflecting surface and is emitted externally
Implementation Method 2
a reflecting surface, placed to be opposite to a light entry side of the first light guiding section, for totally-reflecting a linearly-traveling part of the incident light
Data Source
AI summary
Provided is an optical element which suppresses generation of glare and a dark section and is applicable to planar light emission having improved light efficiency. A light emitting device is also provided. A light emitting device is provided with: a light transmitting member having a light inputting section having light inputted thereto, a first light guide section which guides light inputted to the inputting section to a reflecting surface, the reflecting surface which is arranged on the first light guide section on the side opposite to the light inputting side and totally reflects light which forms one linear path among inputted light, and a second light guide section which guides reflected light; and a light emitting member which inputs light to the inputting section. The first light guide section contains light scattering particles, which multiply scatter light and generate light that passes through the reflecting surface and is outputted to the external, and the second light guide section partially or entirely outputs inputted light to the same surface to which light passed through the reflecting surface is outputted.