White LED Package Dual-Surface Light Extraction
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Solution Overview
Problem
Conventional white LED packages can only extract light from a single front surface, resulting in low light extraction efficiency from the rear surface due to the limited light reflection design, which restricts the utilization of light emitted from both lateral and rear directions of blue LED chips.
Innovation Solution
A white LED package with plural blue LED chips is designed to include a transparent plate with a front fluorescent glue layer and a rear transparent glue layer, where the edge of the rear glue layer has an inclined or curved lateral surface, allowing light to be extracted from both the front and rear surfaces, and the rear glue layer is aligned with the front glue layer, enhancing light extraction efficiency and reducing color temperature differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single front surface light extraction design is used, then the structure is simple, but the light extraction efficiency from the rear surface is low
Solution Approach 1:
The patent transitions from single-direction (front surface) light extraction to dual-direction (front and rear surfaces) light extraction by adding a rear transparent glue layer with inclined lateral surface. This dimensional change in light extraction pathways increases overall light utilization without significantly complicating the package structure.
Solution Approach 2:
The light extraction function is segmented into two independent pathways: front surface extraction through the front fluorescent glue layer and rear surface extraction through the rear transparent glue layer. This segmentation allows each surface to contribute independently to total light output, resolving the contradiction between structural simplicity and extraction efficiency.
2Ease of manufacture
If only front surface light extraction is implemented, then the manufacturing process is simple, but the light utilization is incomplete
Solution Approach 1:
The patent converts the previously wasted rear-emitted light (which would otherwise be lost) into a useful light extraction pathway by adding the rear transparent glue layer with inclined lateral surface. This transforms the harmful light loss into a beneficial secondary light extraction channel, maintaining manufacturing simplicity while improving light utilization.
3Illumination intensity
If a light reflecting surface is disposed under the LED chip, then the brightness of extracted light is increased, but the light extraction from rear surface is still limited
Solution Approach 1:
The patent makes the light extraction system multi-functional by enabling both front and rear surfaces to extract light effectively. The rear transparent glue layer with inclined lateral surface provides universal light extraction capability across both surfaces, allowing the package to adapt to different lighting requirements and applications.
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 design effectively increases the light extraction efficiency from the rear surface and reduces color temperature differences between the front and rear extracted light, enabling more comprehensive light utilization and improved color consistency.
Implementation Method 1
the edge of the rear transparent glue layer has an inclined lateral surface or a curved inclined lateral surface... the light extraction efficiency of the rear surface of the transparent plate is increased by the rear transparent glue layer
Implementation Method 2
a front fluorescent glue layer covering the plural blue LED chips... a rear transparent glue layer covering a rear surface of the transparent plate... the front fluorescent glue layer and the rear transparent glue layer being separated by the transparent plate
Data Source
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AI summary
A white light-emitting diode (LED) package containing plural blue LED chips is disclosed. The white LED package includes a transparent plate, plural blue LED chips bonded on a front surface of the transparent plate, a front fluorescent glue layer covering the plural blue LED chips, and a rear transparent glue layer covering a rear surface of the transparent plate and located at a position aligned with the front fluorescent glue layer. The edge of the rear transparent glue layer has an inclined lateral surface or a curved inclined lateral surface. Therefore, the light can be extracted from both front and rear surfaces, and the light extraction efficiency of the rear surface of the transparent plate is increased. The rear transparent glue layer can be replaced by a rear fluorescent glue layer to reduce the color temperature difference between the lights extracted from the front surface and the rear surface.