Tunable LED Filament Layout for Warm Dimming
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Solution Overview
Problem
LED-filament lamps lack color temperature tunability and warm dimming capabilities, as the color temperature remains constant when dimmed, unlike traditional incandescent bulbs, which is undesirable for many applications.
Innovation Solution
The development of tunable LED-filaments with two arrays of LED chips on the same substrate, each with distinct photoluminescence materials to generate different color temperatures, allowing for color and color temperature adjustment, and the inclusion of a diffusing layer to enhance light mixing and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LED-filament lamps use single-color LED chips with phosphor materials, then manufacturing simplicity is maintained, but color temperature tunability is lost
Solution Approach 1:
The LED-filament is divided into multiple LED chip arrays, where each array contains LED chips of a specific color temperature (e.g., first array with 2700K-3500K, second array with 5000K-6500K). Each array is independently controllable, enabling color temperature tuning by adjusting the intensity ratio between arrays while maintaining manufacturing simplicity through modular segmentation.
Solution Approach 2:
Different segments of the LED-filament (different chip arrays) are assigned different local qualities (different color temperatures). The first array uses LED chips emitting at 2700K-3500K with corresponding phosphor materials, while the second array uses LED chips emitting at 5000K-6500K, allowing each local region to contribute its specific color temperature to the overall output.
2Adaptability or versatility
If LED-filament lamps include multiple LED chip arrays for color tuning, then color temperature tunability is achieved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into standardized modules, where each LED chip array is independently fabricated and tested before final assembly. This modular approach allows parallel production of different array types, simplifying quality control and reducing overall manufacturing complexity despite the multi-array configuration.
Solution Approach 2:
The LED-filament design incorporates universal mounting structures and electrical connections that can accommodate different array configurations. The same basic substrate and bonding wire infrastructure supports various array arrangements, reducing the need for custom manufacturing processes for each color temperature configuration.
3Shape
If LED-filament lamps omit diffuser components, then visual appeal is enhanced, but light mixing uniformity deteriorates
Solution Approach 1:
The patent merges the light mixing function directly into the LED chip array structure itself. By interleaving different color temperature arrays and using shared phosphor materials, the design achieves color mixing without requiring a separate diffuser component, thereby maintaining visual appeal while ensuring uniformity.
Solution Approach 2:
Phosphor materials serve as intermediaries that facilitate color mixing between different LED chip arrays. The phosphors convert excess blue light and facilitate spectral overlap between different color temperatures, achieving uniform perceived color without mechanical diffusers that would compromise visual appearance.
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
Enables color and color temperature tunability, achieving a range of desirable lighting effects, including warm dimming, while reducing the complexity and cost of manufacturing and maintaining visual appeal by eliminating the need for a diffuser.
Implementation Method 1
White light emitting LEDs (white LEDs) include one or more photoluminescence materials (typically inorganic phosphor materials), which absorb a portion of the blue light emitted by the LED and re-emit light of a different color (wavelength)
Implementation Method 2
The LED-filaments are spaced apart too far to achieve adequate mixing. While it is possible that the bulb envelope could include a diffuser
Data Source
AI summary
An LED-filament includes first and second connectors for receiving a variable power; an at least partially light-transmissive substrate; a first LED array of serially connected first LED chips on a front face of the substrate; a second LED array of serially connected second LED chips on the front face of the substrate; a first photoluminescence layer covering the first LED array for generating a first color temperature; a second photoluminescence layer covering the second LED array for generating a second different color temperature; and at least one resistor serially connected to one of the first LED chips, where the first LED array and second LED array are connected in parallel to the first and second connectors, and where current flowing through the first LED and second LED arrays depends on the power applied to the first and second connectors and where the final color temperature of light generated by the LED-filament depends on the power applied to the first and second connectors.