Light-Emitting Device Inclined Wavelength Conversion
Solution Overview
Problem
Current light-emitting devices face challenges in achieving high light extraction efficiency, particularly in reducing size and weight while increasing luminance, due to limitations in the extraction of light emitted from light-emitting elements.
Innovation Solution
A light-emitting device design incorporating a light-emitting element with a wavelength conversion member and a light-transmissive adhesive member, along with a first light-reflective member containing a light-reflective filler, where the wavelength conversion member has inclined surfaces and light-reflective particles are used to enhance light extraction by reflecting and scattering light in a direction that increases the light component extracted outside.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the size of the light-emitting device is reduced, then weight and thickness are reduced, but light extraction efficiency deteriorates
Solution Approach 1:
The patent introduces inclined surfaces on the lateral sides of the wavelength conversion member, transforming the traditional planar interface into a three-dimensional angular structure. This dimensional change enables light to be reflected and extracted in oblique directions, effectively increasing the light extraction efficiency without increasing the device footprint or thickness.
Solution Approach 2:
The wavelength conversion member is divided into multiple functional surfaces: a flat third main surface for light entry, inclined second lateral surfaces for light reflection, and a fourth main surface for light exit. This segmentation allows each surface to perform its specific function optimally, with the inclined surfaces specifically designed to redirect light that would otherwise be trapped, thereby improving extraction efficiency in a compact form.
2Length of stationary object
If the size of the light-emitting device is reduced, then thickness is reduced, but light extraction efficiency deteriorates
Solution Approach 1:
By introducing inclined surfaces that extend from the third main surface to the fourth main surface, the patent creates an angular light path that effectively increases the optical interaction length within the thin wavelength conversion member. This allows light to undergo multiple reflections and wavelength conversions within a reduced thickness, maintaining extraction efficiency despite the thinner profile.
Solution Approach 2:
The inclined surfaces create non-planar, angular interfaces that redirect light paths in a curved or angled manner rather than straight lines. This geometric transformation increases the effective optical path length within the thin device structure, enabling improved light extraction efficiency without increasing physical thickness.
3Loss of energy
If light extraction efficiency is improved by adding reflective structures, then luminance increases, but device complexity increases
Solution Approach 1:
The patent merges the wavelength conversion function and the light reflection function into a single integrated wavelength conversion member. The inclined surfaces are formed as an integral part of this member, eliminating the need for separate reflective elements or additional structural components. This integration improves light extraction efficiency while avoiding the complexity that would arise from adding multiple discrete parts.
Solution Approach 2:
The wavelength conversion member serves multiple functions simultaneously: it converts light wavelength, reflects light via its inclined surfaces, and provides structural support. This multi-functionality reduces the overall device complexity by eliminating the need for separate components dedicated to each function, while still achieving improved light extraction efficiency through the inclined reflective surfaces.
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 significantly enhances the light extraction efficiency of the light-emitting device by reflecting and scattering light emitted from the light-emitting element, leading to improved luminance and reduced size and weight.
Implementation Method 1
a wavelength conversion member (12) including a rectangular third main surface (12c) having an area larger than an area of the second main surface (11c) and bonded to the second main surface (11c), a fourth main surface (12d) opposite to the third main surface (12c), and second lateral surfaces (12e) connected with the third main surface (12c) and the fourth main surface (12d), the wavelength conversion member adapted to convert light emitted from the light-emitting element into light with a different wavelength
Implementation Method 2
a first light-reflective member (15) covering the first lateral surface (11e) provided with the light-transmissive adhesive member (19), the first light-reflective member including third lateral surfaces (15e) that are peripheral surfaces of the first light-reflective member (15). The first light-reflective member (15) contains a light-reflective first filler (41)
Implementation Method 3
Each of the second lateral surfaces (12e) of the wavelength conversion member (12) includes a first inclined surface (12f) in a region adjacent to the third main surface (12c). The wavelength conversion member (12) includes light-reflective particles (44) located on the first inclined surface (12f)
Data Source
AI summary
A light-emitting device includes a light-emitting element including first and second main surface, and a first lateral surface; a wavelength conversion member including a third main surface, a fourth main surface, and second lateral surfaces; a light-transmissive adhesive member; and a first light-reflective member containing a light-reflective first filler, covering the first lateral surface provided with the light-transmissive adhesive member, and including third lateral surfaces being peripheral surfaces of the first light-reflective member. In a cross-section in a direction perpendicular to the second main surface, a distance between the third lateral surfaces is smaller than a distance between the second lateral surfaces at a fourth main surface side. Each of the second lateral surfaces of the wavelength conversion member includes a first inclined surface in a region adjacent to the third main surface. The wavelength conversion member includes light-reflective particles located on the first inclined surface.