Semiconductor Light-Emitting Device With Wavelength Converting Layer
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Solution Overview
Problem
Conventional semiconductor light-emitting devices face chromatic variability issues when projecting white light, especially when used in vehicle headlamps, due to differences in light emission from the central and peripheral areas of the light-emitting surface, leading to non-uniform color tone and reduced light distribution quality.
Innovation Solution
A semiconductor light-emitting device design featuring a mounting board with a semiconductor light-emitting chip and a wavelength converting layer covering both the top and side surfaces, a sealing member with a cutout section to protect electrodes, and a transparent layer that reduces the light-emitting surface area, enhancing light uniformity and reliability by using a combination of phosphors and reflective materials to manage light path lengths and intensities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a small light-emitting surface is used to efficiently control light with small optical structures, then light control efficiency is improved, but chromatic variability increases due to differences in light emission from central and peripheral areas
Solution Approach 1:
The patent applies local quality by creating different optical path lengths in different regions of the light-emitting device. Specifically, a light-absorbing layer is positioned at the periphery to absorb stray light, while the central region maintains direct light emission. This regional differentiation ensures uniform chromaticity across the entire light-emitting surface, resolving the contradiction between using a small light-emitting surface for efficient light control and maintaining chromatic uniformity.
2Ease of manufacture
If a wavelength converting layer covers only the top surface of the semiconductor light-emitting chip, then manufacturing simplicity is maintained, but light uniformity deteriorates due to chromatic variability in the emitted mixture light
Solution Approach 1:
The patent extends the wavelength converting layer from merely covering the top surface to also covering the side surface of the semiconductor light-emitting chip. This dimensional extension ensures that light emitted from all surfaces of the chip undergoes wavelength conversion, eliminating chromatic variability between central and peripheral areas while maintaining manufacturing feasibility through a straightforward layer extension approach.
3Illumination intensity
If the light-emitting surface area is reduced to achieve high light-emitting intensity from a small surface, then light intensity is improved, but chromatic variability increases due to optical characteristics and physical characteristics
Solution Approach 1:
The patent converts the harmful effect of stray light and optical reflections that cause chromatic variability into a beneficial solution by introducing a light-absorbing layer. This layer absorbs excess light paths that would otherwise cause color variation, enabling the device to maintain high light-emitting intensity from a small surface area while achieving uniform chromaticity across the light-emitting surface.
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 achieves high uniformity and intensity of white light emission from a small surface area, reducing chromatic variability and improving reliability, making it suitable for harsh conditions in vehicle headlamps and other lighting applications.
Implementation Method 1
a wavelength converting material 63 having a convex side surface 63S disposed between the top surface of the semiconductor light-emitting chip 61 and the bottom surface of the transparent layer 64
Data Source
AI summary
A reliable semiconductor light-emitting device can include a mounting board, at least one semiconductor light-emitting chip mounted on the mounting board, a wavelength converting layer having a side surface covering the light-emitting chip, and a seal member having an opening contacting the side surface of the wavelength converting layer and covering chip electrodes. The light-emitting device can also include a transparent layer disposed into the opening of the sealing member so as to be located over the light-emitting chip and within a top surface of the light-emitting chip, and can be configured to emit various mixture lights having a high uniformity by using lights emitted from the light-emitting chip and the wavelength converting layer. Thus, the disclosed subject matter can provide the reliable light-emitting device, which can emit the mixture lights including a substantially white color light from a small light-emitting surface as a light source for a headlight, etc.