Tunable LED Filament with Scattering Layers
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Solution Overview
Problem
Current LED filament lamps lack color and color temperature control, resulting in non-uniform light distribution and appearance, which is a limitation in achieving a decorative look similar to incandescent bulbs.
Innovation Solution
A color tunable and color temperature tunable LED filament design featuring an elongated carrier with LEDs of different colors and color temperatures, covered by transparent or substantially transparent layers and light scattering layers to achieve omni-directional and homogeneous light emission, utilizing RGB or CW-WW LEDs for improved mixing and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single unitary wavelength conversion layer with light scattering particles is used, then scattering is reduced and manufacturing is simplified, but color temperature uniformity deteriorates
Solution Approach 1:
The patent divides the single unitary wavelength conversion layer into multiple separate wavelength conversion layers, each with different phosphor compositions and light scattering properties. This segmentation allows each layer to be optimized for specific color temperature ranges while maintaining overall uniformity through controlled layering and thickness variations.
Solution Approach 2:
Different regions of the LED filament are equipped with wavelength conversion layers having locally optimized phosphor compositions and light scattering particle distributions. This enables each section to convert light optimally for its specific position, ensuring uniform color temperature across the entire filament while maintaining manufacturing simplicity through modular layer application.
2Adaptability or versatility
If RGB or CW-WW LEDs are used on a transparent substrate, then color and color temperature control is achieved, but light distribution uniformity and appearance quality deteriorate
Solution Approach 1:
Multiple wavelength conversion layers act as intermediaries between the RGB or CW-WW LEDs and the final light output. These layers convert the LED light into a balanced spectrum with uniform color temperature, mediating the transition from non-uniform LED emission to homogeneous light distribution while preserving color control capability.
Solution Approach 2:
The patent employs composite wavelength conversion layers combining multiple phosphor materials with different emission characteristics and light scattering properties. This composite approach enables simultaneous achievement of color tunability from RGB/CW-WW LEDs and uniform light distribution across the filament 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 solution enables uniform color and color temperature control, providing a visually appealing and efficient light distribution that mimics traditional incandescent filaments while being compact and aesthetically preferable.
Implementation Method 1
a first elongated light scattering layer, arranged to at least partially cover the first transparent or substantially transparent layer
Data Source
AI summary
The present invention relates to a color tunable and/or color temperature tunable LED filament (20, 22, 24), said LED filament comprising an elongated carrier (220), said elongated carrier comprising a first major surface (222) and a second major surface (224) arranged opposite to said first major surface, a plurality of LEDs (210) arranged in at least one linear array on said first surface of said elongated carrier, wherein the plurality of LEDs includes LEDs of different colors and/or different color temperatures, a first elongated transparent or substantially transparent layer (230) covering the plurality of LEDs on the first major surface and also at least partly covering said first major surface, and a first elongated light scattering layer (240), arranged to at least partially cover said first transparent or substantially transparent layer.