Luminous Flux Control Member for Uniform Surface Lighting
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Solution Overview
Problem
Conventional light flux controlling members in surface light source devices suffer from luminance unevenness and light loss due to light being reflected or absorbed into the substrate, particularly when beams with large emission angles are involved.
Innovation Solution
A light flux controlling member with an incidence surface, an emission surface, and a plurality of linear protrusions (total reflection prisms) that are rotationally symmetric about the central axis, where the linear protrusions include first and second reflection surfaces and a ridge line, effectively redirecting light reflected by the emission surface to minimize absorption and reflection into the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light flux controlling member uses conventional emission surface design, then light can be output toward outside, but light is reflected by emission surface and travels in direction directly above light flux controlling member causing luminance unevenness
Solution Approach 1:
The emission surface is segmented into multiple inclined surfaces (first inclined surface, second inclined surface, third inclined surface) with different orientations. Each inclined surface redirects light in specific directions to prevent concentration in the direction directly above the light flux controlling member, thereby improving luminance uniformity and reducing light loss.
Solution Approach 2:
Different regions of the emission surface are given different local properties through the inclined surfaces. The first inclined surface redirects light laterally, the second inclined surface redirects light at intermediate angles, and the third inclined surface redirects light at steeper angles. This local differentiation ensures uniform light distribution and prevents energy loss.
2Loss of energy
If light flux controlling member uses simple emission surface, then device complexity is low, but light reflected by emission surface is absorbed into substrate causing excessive light loss
Solution Approach 1:
The emission surface uses inclined surfaces with curved or faceted geometry rather than simple flat surfaces. These curved inclined surfaces are designed to redirect reflected light away from the substrate, preventing absorption and reducing light loss, while maintaining manufacturability through moldable structures.
3Illumination intensity
If light flux controlling member redirects reflected light laterally, then luminance unevenness is reduced, but device structure becomes more complex
Solution Approach 1:
The light flux controlling member integrates the light redirecting function directly into the emission surface structure itself, rather than adding separate components. The inclined surfaces are formed as part of the single light flux controlling member body, combining the emission and light redirection functions into one integrated structure, thereby improving luminance uniformity without significantly increasing device complexity.
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 enhances light use efficiency and uniformity, reducing luminance unevenness and light loss by redirecting light reflected by the emission surface in a lateral direction, thereby improving the overall performance of light emitting devices and display apparatuses.
Implementation Method 1
a plurality of linear protrusions each having a cross-section that is substantially triangle-shaped, the linear protrusions being formed to surround the central axis... each of the plurality of linear protrusions includes a first reflection surface, a second reflection surface, and a ridge line that is an intersection line of the first reflection surface and the second reflection surface
Implementation Method 2
The light entered light flux controlling member 20 reaches emission surface 24, and is output toward the outside from emission surface 24 (solid arrow). At this time, the light is refracted according to the shape of emission surface 24, so that the traveling direction of the light can be controlled.
Implementation Method 3
part of the light reached emission surface 24 is reflected by emission surface 24 (Fresnel reflection) and reaches rear surface 26 facing the substrate on which light emitting element 10 is mounted (dashed arrow)
Data Source
AI summary
This luminous flux control member has: an incidence surface through which light emitted from a light-emitting element enters; an emission surface through which the light entering from the incidence surface is emitted to the outside; and multiple ridges that are formed on the back side so as to surround the central axis (CA) and that have a substantially triangular cross-sectional shape. Each of the multiple ridges has a first reflecting surface, a second reflecting surface, and a ridge line which is the line of intersection of the first reflecting surface and the second reflecting surface. An imaginary line containing the ridge lines intersects the central axis (CA) at a position closer to the front side than the ridge lines.