Light Flux Control Member for COB LED Luminance Uniformity
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Solution Overview
Problem
Light-emitting devices using LEDs of the COB type experience luminance unevenness due to excessive light distribution towards the upper region, leading to non-uniform illumination and reduced light use efficiency, as conventional light flux controlling members fail to effectively manage light emitted in the lateral direction.
Innovation Solution
A light flux controlling member with an incidence surface, an emission surface, and a plurality of ridges, where the ridges are disposed substantially perpendicular to the central axis, controlling light distribution by refracting and reflecting light to minimize luminance unevenness and maximize light utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional light flux controlling members are used with COB LEDs, then light can be emitted from the device, but luminance unevenness occurs due to excessive light distribution towards the upper region
Solution Approach 1:
The rear surface of the light flux controlling member is segmented into multiple regions: a first region with a first inclined surface, a second region with a second inclined surface, and a third region with a third inclined surface. Each region has different inclination angles designed to redirect light from different emission angles of the COB LED, thereby distributing light more uniformly and reducing luminance unevenness in the upper region.
Solution Approach 2:
Different regions of the rear surface are assigned different local optical properties through varying inclination angles. The first inclined surface handles light from specific angles, the second inclined surface handles other angles, and the third inclined surface handles remaining angles. This local differentiation of optical characteristics enables precise control over light distribution to achieve uniform luminance.
2Use of energy by moving object
If conventional light flux controlling members are used, then light emission occurs, but light use efficiency is reduced due to light being absorbed by the substrate or reflected as uncontrollable light
Solution Approach 1:
The invention converts the harmful effect of light reaching the rear surface (which would otherwise be absorbed by the substrate or reflected uncontrollably) into a beneficial effect by using the rear surface as an additional light extraction path. The inclined surfaces on the rear surface redirect this light toward useful angles, transforming potential energy loss into useful light output and improving overall light use efficiency.
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 reduces luminance unevenness and enhances light distribution uniformity, ensuring efficient light emission and utilization in light-emitting devices, surface light source devices, and display devices, particularly when used with LEDs that emit significant light in the lateral direction.
Implementation Method 1
controlling light distribution by refracting and reflecting light
Implementation Method 2
controlling light distribution by refracting and reflecting light
Data Source
AI summary
This light flux control member comprises an incidence surface, an emission surface, and a plurality of protruding strips. The plurality of protruding strips are disposed approximately perpendicularly to a central axis. When the section perpendicular to the central axis of the incidence surface has the shape of an ellipse, at least some of the plurality of protruding strips are disposed outside a recessed part in the minor axis direction of the ellipse and along the minor axis direction. When the section of the emission surface has the shape of an ellipse, at least some of the plurality of protruding strips are disposed outside the recessed part in the major axis direction of the ellipse and along the major axis direction.