Light Emitting Device Wavelength Conversion and Heat Dissipation
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Solution Overview
Problem
Conventional white LED light emitting devices have inefficiencies due to poor heat dissipation and reabsorption of light, leading to decreased luminous efficacy and reliability.
Innovation Solution
A light emitting device configuration that includes a semiconductor light emitting element, a mounting member, a first wavelength conversion layer, a second wavelength conversion layer, and a transparent layer, where the wavelength conversion layers absorb and emit light with longer wavelengths, and the transparent layer prevents reabsorption and enhances heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorescer layer and die bonding adhesive are provided between the LED chip and leadframe, then the LED chip can be mounted on the leadframe, but heat dissipation becomes poor and luminous efficacy decreases
Solution Approach 1:
The patent removes the fluorescer layer and die bonding adhesive from between the LED chip and leadframe, extracting the heat dissipation problem source. The LED chip is directly mounted on the leadframe, eliminating thermal barriers and improving heat dissipation while maintaining mounting reliability through direct contact.
2Ease of manufacture
If conventional mounting configurations are used, then manufacturing is simplified, but luminous efficacy decreases due to heat generation and reabsorption
Solution Approach 1:
The patent converts the previously harmful direct mounting configuration into a beneficial one by eliminating intermediate layers that caused heat trapping and light reabsorption. The direct LED chip-to-leadframe contact transforms from a problematic simple structure into an optimized heat dissipation path, improving luminous efficacy while maintaining manufacturing simplicity.
3Illumination intensity
If fluorescer layers are placed between the LED chip and leadframe, then wavelength conversion can occur, but heat dissipation is poor and reliability decreases
Solution Approach 1:
The patent relocates the wavelength conversion function from the vertical dimension (between LED chip and leadframe) to the horizontal dimension (on the leadframe surface or in surrounding structures). This spatial reconfiguration allows heat to dissipate vertically through direct LED chip-to-leadframe contact while wavelength conversion occurs in a separate thermal zone, improving both heat dissipation and device reliability.
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 increases luminous efficacy by minimizing reabsorption and heat-related efficiency decreases, while improving the reliability of the light emitting device.
Implementation Method 1
The first wavelength conversion layer absorbs the first light emitted and emits a second light having a wavelength longer than a wavelength of the first light
Implementation Method 2
The second wavelength conversion layer absorbs the first light and emits a third light having a wavelength longer than the wavelength of the first light
Implementation Method 3
The first transparent layer is transparent to the first light, the second light, and the third light
Data Source
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AI summary
According to one embodiment, a light emitting device (210, 210a, 214, 215, 216, 218, 218a, 220, 220a, 220b) includes a semiconductor light emitting element (10) to emit a first light (L1), a mounting member (20), first and second wavelength conversion layers (30, 80) and a transparent layer (60). The first wavelength conversion layer (30) is provided between the element (10) and the mounting member (20) in contact with the mounting member (20). The first wavelength conversion layer (30) absorbs the first light (L1) and emits a second light (L2) having a wavelength longer than a wavelength of the first light (L1). The semiconductor light emitting element (10) is disposed between the second wavelength conversion layer (80) and the first wavelength conversion layer (30). The second wavelength conversion layer (80) absorbs the first light (L1) and emits a third light (L3) having a wavelength longer than the wavelength of the first light (L1). The transparent layer (60) is provided between the element (10) and the second wavelength conversion layer (80). The transparent layer (60) is transparent to the first, second, and third lights (L1, L2, L3).