Light Emitting Device Fluorescent Body Distribution
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Solution Overview
Problem
Existing light emitting devices face challenges in achieving high light extraction efficiency and uniform light distribution due to uneven light emission characteristics and absorption of light by the fluorescent body, particularly in side emission type LEDs where light is emitted both upward and sideways.
Innovation Solution
A light emitting device design featuring a base with a recessed portion, a light emitting element mounted within, a translucent member coating the element, and a sealing resin containing a fluorescent body distributed more on the side than the top, allowing efficient extraction of primary light and wavelength conversion, while minimizing light loss through the side wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the fluorescent body is disposed directly above the light emitting element to maximize wavelength conversion, then the light extraction efficiency is improved, but the light distribution becomes uneven and light loss increases due to absorption
Solution Approach 1:
The patent applies local quality by creating different fluorescent body distribution characteristics in different regions: the first region (directly above the light emitting element) has a higher concentration of fluorescent body for maximum wavelength conversion, while the second region (surrounding the first region) has a lower concentration to reduce light absorption and improve light distribution uniformity. This spatial variation in fluorescent body density resolves the contradiction between extraction efficiency and distribution uniformity.
2Device complexity
If a single layer coating is used to simplify the structure, then the device complexity is reduced, but the light distribution uniformity and extraction efficiency are compromised
Solution Approach 1:
The patent implements local quality within a single layer coating by spatially varying the fluorescent body concentration: the first region contains a higher concentration for effective wavelength conversion, while the second region contains a lower concentration to minimize light absorption and improve uniformity. This approach maintains structural simplicity while achieving improved light distribution through localized compositional variation.
3Loss of energy
If the fluorescent body concentration is increased to enhance wavelength conversion, then the light extraction efficiency is improved, but the light distribution becomes more uneven due to increased absorption
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatially differentiated fluorescent body concentration: the first region directly above the light emitting element has high concentration for efficient wavelength conversion, while the second region surrounding it has low concentration to reduce light absorption and maintain distribution uniformity. This localized optimization allows high conversion efficiency without sacrificing uniformity.
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 extraction efficiency and reduces unevenness in light emission, achieving higher brightness and chromaticity uniformity by optimizing the placement of the fluorescent body and translucent member to direct light effectively.
Implementation Method 1
a coating member that contains a fluorescent body that is excited by light from the light emitting element
Data Source
AI summary
A light emitting device includes a base that has an element mounting surface, a light emitting element that is mounted on the element mounting surface and that has maximum light intensity in a directly upward direction, and a coating member that contains a fluorescent body that is excited by light from the light emitting element, and that is constituted by a single layer that coats an upper part of the light emitting element. The fluorescent body exists at a position other than directly above the light emitting element.