Concave Optical Element for Uniform LED Illumination
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Solution Overview
Problem
LED light sources with separate positions for shorter-wavelength and longer-wavelength light emission cause color variations depending on direction, leading to undesirable bluish or reddish light effects in illumination units.
Innovation Solution
An optical element with a concave light receiving surface around the optical axis, featuring local maximum and minimum values in angle measurements, ensures that light rays from each point on the source are refracted in various directions, reducing color differences due to direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional optical element with a planar light receiving surface is used, then the structure is simple and easy to manufacture, but color difference occurs in different directions due to separate positions of shorter-wavelength and longer-wavelength light emission
Solution Approach 1:
The light receiving surface is designed with a concave curved shape around the optical axis, featuring local maximum and minimum values in the angle between the normal and optical axis. This curvature causes light rays from different positions on the light source to be refracted in various directions, mixing shorter-wavelength and longer-wavelength lights to reduce color difference in different emission directions.
2Manufacturing precision
If the light receiving surface is made concave with local maximum and minimum angle values, then color difference due to direction is reduced, but the manufacturing complexity increases
Solution Approach 1:
The invention changes the geometric parameters of the light receiving surface by introducing specific concave curvature with controlled local maximum and minimum angle values. This parameter modification enables the surface to refract light in multiple directions while maintaining a relatively simple overall structure that can still be manufactured using conventional molding techniques.
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 optical element effectively diffuses light, minimizing color variations across different directions, resulting in uniform illumination by refracting rays from each point on the light source in multiple directions, thus maintaining consistent color across the illumination area.
Implementation Method 1
rays from each point on the light source are refracted in various directions depending on location on the light receiving surface which each ray reaches
Data Source
AI summary
An optical element has a light receiving surface covering a light source arranged on a plane and an exit surface covering the light receiving surface. When an axis passing through the center of the light source and is perpendicular to the plane is designated as an optical axis and the point of intersection of the optical axis and the light receiving surface is designated as O1, the light receiving surface is concaved around the optical axis with respect to the periphery. When an angle which a normal to the light receiving surface on a point P thereon forms with the optical axis is designated as φh and distance in the optical axis direction from O1 to P is designated as z, φh has at least one local maximum value and at least one local minimum value with respect to z while P is moved along the light receiving surface.