Optical Element Illumination Uniformity LED
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Solution Overview
Problem
Illumination devices using planar light sources, such as LEDs, face challenges in providing uniform illumination when the lengthwise and breadthwise directions are different, leading to unevenness in illuminance across the illuminated area.
Innovation Solution
The design incorporates a planar light source with a light receiving surface shaped like a cap, where the light receiving surface is symmetric with respect to the x-axis and y-axis, and a light exiting surface with a diffusion member, which reduces unevenness of illuminance by diffusing light along the optical axis, ensuring a consistent illuminance distribution across the area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of LED light sources is increased to illuminate a large area uniformly, then the illumination uniformity is improved, but the manufacturing cost and power consumption increase
Solution Approach 1:
The patent applies local quality by designing optical elements with asymmetric light distribution characteristics tailored to specific regions. The optical elements are configured to redirect light from LED chips arranged in one direction (e.g., x-axis) to achieve uniform illumination in both x and y directions, with each optical element having optimized properties for its local position to compensate for the directional emission pattern of LEDs
Solution Approach 2:
The patent transforms a one-dimensional LED chip arrangement into two-dimensional uniform illumination by using optical elements that redirect light in multiple directions. The optical elements convert the linear light distribution from LED chips into radial or omnidirectional light patterns, effectively adding dimensional coverage without increasing the number of light sources
2Illumination intensity
If the illuminated area is located away from the LED light sources to achieve uniform illumination, then the illumination uniformity is improved, but the device cannot be made compact in size
Solution Approach 1:
The patent employs curved or spheroidal optical elements (such as dome-shaped lenses or reflectors) positioned close to the LED chips. These curved surfaces redirect light rays through refraction or reflection to achieve uniform illumination distribution over a compact area, eliminating the need for large separation distances between light sources and illuminated surface
3Ease of manufacture
If LED chips are arranged in a line for electrical wiring convenience, then the ease of manufacture is improved, but the illumination uniformity in both lengthwise and breadthwise directions deteriorates
Solution Approach 1:
The patent introduces optical elements as intermediaries between the linearly arranged LED chips and the illumination plane. These optical elements act as mediators that take the directional light output from the linear LED arrangement and transform it into uniform two-dimensional illumination, allowing the LEDs to maintain their simple linear configuration for ease of wiring while achieving uniform illumination through the optical mediation
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 configuration effectively reduces unevenness of illuminance in both directions, achieving a more uniform illumination even when the lengthwise and breadthwise dimensions of the light source are disparate, thereby enhancing the illumination device's performance and compactness.
Implementation Method 1
a light exiting surface with a diffusion member, which reduces unevenness of illuminance by diffusing light along the optical axis
Data Source
AI summary
An illumination device for planar light sources gives uniform illumination on an illuminated plane. A of lengthwise direction and length of breadthwise direction are different from each other. The illumination device includes a planar light source and an optical element including a light receiving surface for receiving light form the planar light source and a light exiting surface. A shape of the planar light source is symmetric with respect to x-axis and y-axis and a length of the shape in x-axis direction is shorter than length of the shape in y-axis direction; the center of the planar light source is set as the origin and two axes orthogonal to each other are selected as x-axis and y-axis. Assuming that the maximum value of x-coordinate of the planar light source is a and the maximum value of y-coordinate of the planar light source is b, the following relationships hold:hab=(ha+a)-(hb+b)(ha+a)hab≤0.02.