Diffusion Lens Back-Side Sloped Surfaces for Uniform Luminance
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Solution Overview
Problem
In light emitting modules, reducing lens diameter leads to luminance non-uniformity (mura) at the flange part due to the emission of light from upwardly-sloping or flat surfaces on the lens back-side, causing non-uniform illumination.
Innovation Solution
A diffusion lens design with a back-side part featuring a 1st sloped surface sloping upward from the light incidence part and a 2nd sloped surface sloping downward, breaking the curvature at the flange part, and inflection points to offset light emitted from the flange part, ensuring uniform luminance by controlling light diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the lens diameter is reduced to achieve miniaturization, then the device size is reduced, but luminance non-uniformity occurs at the flange part
Solution Approach 1:
The back-side surface of the lens is segmented into multiple regions with different slope angles: a first region with an upward slope from the light incidence part, a second region with a downward slope from the first sloped surface, and a third region with a flat surface. This segmentation allows each region to control light diffusion differently, preventing luminance non-uniformity while maintaining miniaturization.
Solution Approach 2:
Different regions of the lens back-side surface are assigned different local optical properties through varying slope angles. The first region (upward slope) controls light diffusion in one direction, the second region (downward slope) controls diffusion in another direction, and the third region (flat) provides a transition zone. This local quality variation ensures uniform luminance distribution across the flange part even with reduced lens diameter.
2Volume of moving object
If flange parts are formed to reduce lens diameter, then miniaturization is achieved, but luminance non-uniformity (mura) occurs at the flange part
Solution Approach 1:
Instead of controlling luminance uniformity only in the radial direction, the invention introduces angular control by creating sloped surfaces at different angles on the back-side of the lens. The upward slope, downward slope, and flat surface create multi-dimensional light diffusion paths, ensuring uniform luminance distribution across the flange part while maintaining compact lens dimensions.
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 prevents luminance non-uniformity at the flange part by uniformly distributing light, maintaining even illumination even when the lens diameter is reduced, as demonstrated by experimental photographs and graphs showing reduced mura values within specific slope angle ranges.
Implementation Method 1
a light incidence part that forms an inner surface where light emitted from a light emitting device is incident
Implementation Method 2
a 2nd sloped surface that is formed sloping downward from the end of the 1st sloped surface; because the light diffused by the 2nd sloped surface of the back-side part offsets light emitted from the flange part
Data Source
AI summary
A light emitting module is provided that has a diffusion lens that both reduces lens radius and renders uniform light luminance by preventing luminance non-uniformities caused by lens radius reduction. The light emitting module includes a circuit board, a light emitting device mounted on the circuit board, and a diffusion lens that controls the light emitted from the light emitting device and is installed on the circuit board so as to be located above the light emitting device.