Semiconductor Light Emitting Device Curved Wavelength Conversion
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Solution Overview
Problem
Semiconductor light emitting devices using wavelength converting materials on LED chips face issues with color unevenness due to insufficient coverage of the wavelength converting part at the corners, leading to reduced light output and brightness when light-shielding parts are used to address this problem.
Innovation Solution
A semiconductor light emitting device design featuring a support substrate with edges extending beyond the semiconductor film, a light-shielding part covering the side surfaces, and a wavelength converting part with a curved surface shape that extends to the edges of the support substrate, ensuring sufficient thickness at corners and preventing light emission from side surfaces, thereby eliminating color unevenness and enhancing light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light-shielding part is provided in each corner of the semiconductor film surface to prevent blue light emission, then color unevenness is eliminated, but the area of the light-emitting part is reduced, resulting in reduction in light flux and brightness
Solution Approach 1:
A resin layer is introduced as an intermediary material between the semiconductor film and the external environment. This resin layer extends to and covers the corner regions, acting as a mediator that prevents blue light emission from corners without requiring direct light-shielding structures on the semiconductor film surface, thereby maintaining light flux while achieving color uniformity
Solution Approach 2:
The solution moves from a two-dimensional surface approach (providing light-shielding parts on the film surface) to a three-dimensional approach by extending the resin layer into the corner regions. This dimensional extension allows the wavelength converting part to cover corners effectively without reducing the active light-emitting area of the semiconductor film
2Ease of manufacture
If the wavelength converting part is coated over the upper surface of the semiconductor film, then the wavelength converting part forms a curved surface shape like a dome, but the wavelength converting part does not spread sufficiently into the corners, resulting in color unevenness
Solution Approach 1:
The resin layer is designed with varying thickness and extension characteristics in different regions. In corner regions, the resin layer extends further and has different coverage properties compared to the central region, ensuring sufficient wavelength converting material presence in corners while maintaining the overall dome-shaped curved surface structure for optimal light extraction
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 solution effectively eliminates color unevenness and improves light output by ensuring adequate thickness of the wavelength converting material at corners and redirecting unnecessary fluorescent particles, resulting in uniform emission and increased luminous flux and efficiency.
Implementation Method 1
The fluorescent substance absorbs blue light to emit yellow light of a longer wavelength. Part of blue light emitted from the blue LED is converted by the fluorescent substance into yellow light
Implementation Method 2
a light-reflecting layer and having a support surface supporting the semiconductor film
Data Source
AI summary
A semiconductor light emitting device which has a wavelength converting part on a semiconductor film and can eliminate unevenness in emission color without a reduction in light output. The semiconductor film includes a light emitting layer. The support substrate is bonded to the semiconductor film via a light-reflecting layer and has a support surface supporting the semiconductor film and edges located further out than the side surfaces of the semiconductor film. The light-shielding part covers the side surfaces of the semiconductor film and part of the support surface around the semiconductor film in plan view. The wavelength converting part contains a fluorescent substance and is provided over the support substrate to bury the semiconductor film and the light-shielding part therein. The wavelength converting part has a curved surface shape in which its thickness increases when going from the edges toward the center of the semiconductor film.