Structured LED Converter Layer for Uniform Color
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Solution Overview
Problem
Conventional light-emitting diode (LED) chips exhibit significant color space variations due to non-uniform phosphor distribution and production tolerances, leading to inconsistent color spectrum when viewed from different angles.
Innovation Solution
A structured converter layer is applied to the LED chip, with subregions having varying thickness or being free of the converter layer, specifically designed to reduce the dependence of the color space on viewing angle by controlling light emission from different regions of the chip's main face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thin uniform converter layer is applied to the entire main face of the semiconductor layer, then the manufacturing process is simple, but the color space shows significant dependence on viewing angle
Solution Approach 1:
The converter layer is segmented into multiple regions with different thicknesses or material compositions. The main face is divided into a first region with a first converter layer and a second region with a second converter layer, allowing different parts of the emission surface to contribute differently to the overall color space at various viewing angles.
Solution Approach 2:
Different regions of the converter layer are given different local properties (thickness, material composition, or both) to optimize color space uniformity. The first region has different converter layer characteristics than the second region, creating localized quality variations that compensate for viewing angle dependence.
2Reliability
If phosphor-containing potting compound is used for encapsulation, then the LED chip is protected and packaged, but color space variations arise due to non-uniform phosphor distribution
Solution Approach 1:
The phosphor conversion function is extracted from the bulk potting compound and concentrated into a thin structured converter layer applied directly to the semiconductor layer. This eliminates the phosphor distribution problems inherent in potting compound encapsulation while maintaining the protective packaging function.
Solution Approach 2:
A thin converter layer serves as an intermediary between the semiconductor layer and the potting compound. This converter layer performs the phosphor conversion function with uniform distribution, while the potting compound provides protection without contributing to color space variations.
3Productivity
If production tolerances are relaxed for LED chip height and positionability, then manufacturing cost decreases, but variations in potting compound amount lead to color space distribution variations
Solution Approach 1:
The converter layer is applied to the semiconductor layer before encapsulation in a controlled manner with specific thickness variations built in. This preliminary structuring compensates for subsequent variations in potting compound amount and LED chip positioning, maintaining color space uniformity despite relaxed production tolerances.
Solution Approach 2:
The converter layer thickness or material composition is varied across different regions to compensate for expected variations in potting compound amount. By pre-adjusting parameters in the converter layer, the system becomes less sensitive to production tolerances in encapsulation and positioning.
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 structured converter layer achieves a more uniform color space spectrum across various viewing angles, enhancing the LED chip's color consistency and radiation intensity, particularly at larger viewing angles, compared to unstructured converter layers.
Implementation Method 1
a luminescence conversion material comprising at least one phosphor
Data Source
AI summary
Disclosed is a light-emitting diode chip comprising a semiconductor layer sequence suitable for emitting primary electromagnetic radiation and further comprising a converter layer that is applied to at least one main face of the semiconductor layer sequence and comprises at least one phosphor suitable for converting a portion of the primary radiation into secondary radiation, at least a portion of the secondary radiation and at least a portion of the unconverted primary radiation overlapping to form a mixed radiation with a resulting color space. The converter layer is purposefully structured to adjust a dependence of the resulting color space on viewing angle. Also disclosed is a method of making a light-emitting diode chip in which a converter layer is purposefully structured.