Light Emitting Device with Sloped Reflection Layer
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Solution Overview
Problem
Existing light emitting devices face challenges in achieving high light extraction efficiency and small light emitting area due to limitations in cavity processing and increased absorption of transversely propagated light, leading to reduced total light flux.
Innovation Solution
A light emitting device design featuring a reflection material layer with a slope that reflects light emitted from the sides of the light emitting element, preventing it from being absorbed back into the element and enhancing extraction efficiency, while using a tabular member with a wavelength conversion function and a transparent resin layer to maintain optical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a cavity such as cup or recess is used to reflect light from the light emitting element, then the external efficiency of light for the upward direction is improved, but the light emitting surface area becomes larger than the upper surface of the light emitting element and light is decayed due to penetration through the fluorescent substance-containing resin layer or sealing material
Solution Approach 1:
The invention extracts the light reflection function from the cavity structure and relocates it to a reflection member positioned adjacent to the light emitting element. This separates the reflection function from the cavity's light extraction function, allowing the light emitting surface to be defined by the element's upper surface area rather than the cavity opening area.
Solution Approach 2:
The invention introduces a reflection member as an intermediary component between the light emitting element and the surrounding structure. This reflection member reflects light that would otherwise be emitted in lateral directions back toward the light emitting element, improving extraction efficiency without requiring a larger cavity opening.
2Area of stationary object
If a reflection member is disposed as a vertical wall to cover the sides of the light emitting element and wavelength conversion layer, then the light emitting surface area is reduced and front direction luminance is improved, but the light reflected at the side is returned to the inside of the light emitting element and absorbed, reducing the amount of total light flux
Solution Approach 1:
The invention employs an asymmetric reflection member configuration where the reflection surface is positioned and oriented to reflect light away from the light emitting element's active region. The reflection member has a specific geometric arrangement that directs reflected light toward safe zones where it can be extracted without being re-absorbed by the light emitting element.
Solution Approach 2:
The invention applies different functional zones: the reflection member is positioned to reflect light from specific lateral regions while avoiding the creation of harmful light paths back into the element. The geometric configuration creates localized reflection zones that improve extraction efficiency without causing energy loss through re-absorption.
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 design improves light extraction efficiency by preventing light absorption and maintaining optical quality, allowing for a smaller light emitting area and reduced degradation over time.
Implementation Method 1
a reflection material layer with a slope that reflects light emitted from the sides of the light emitting element
Implementation Method 2
a wavelength conversion layer, and a transparent resin layer to maintain optical characteristics
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)~3(e)
AI summary
There is provided a method for producing a light emitting device having a small light emitting area and showing high light extraction efficiency. An uncured resin 13' is dropped on either one or both of a light emitting element 11 and a tabular member 14 in such an amount that the resin is maintained on them by surface tension, the light emitting element 11 and the tabular member 14 are piled up with the uncured resin 13' maintained between them and on a side of the light emitting element by surface tension of the uncured resin 13' to form an uncured resin layer 13' having an inclined side 130, and then the resin layer 13 is cured. The tabular member is constituted with a material having an alkali metal oxide content of 0.2% by weight or lower.