Flexible LED Filament with Conductive Sections for Uniform Illumination
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Solution Overview
Problem
LED light bulbs with traditional hard or soft filaments face challenges in achieving uniform illumination due to the rigidity of the substrate, light blocking, and thermal expansion issues, leading to poor light distribution and increased production costs. Additionally, the power supply circuitry for LED filaments requires stabilization to minimize flicker and heat dissipation improvements.
Innovation Solution
The proposed solution involves an LED filament structure comprising LED chips, conductive electrodes, a Polyimide film, and a copper foil, with a light conversion layer and silver plating to enhance thermal radiation and light emission efficiency, along with a power supply module that includes a rectifying, filtering, and driving circuit to provide stable current and reduce flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a glass substrate is used in LED hard filament, then structural stability is improved, but illumination uniformity deteriorates due to light blocking and rigid structure
Solution Approach 1:
The patent replaces the rigid glass substrate with a flexible printed circuit board (FPC) substrate that allows the LED filament to be bent into various shapes while maintaining structural integrity. The FPC substrate is thin and flexible enough to enable bending without breaking, yet provides sufficient mechanical support for the LED chips and conductive patterns.
Solution Approach 2:
The patent arranges LED chips in a specific spatial pattern on the FPC substrate, with chips positioned at different locations and orientations to achieve uniform 360-degree illumination. This multi-dimensional arrangement of light sources compensates for the substrate's light-blocking properties and creates omnidirectional lighting效果.
2Adaptability or versatility
If FPC substrate is used in LED soft filament, then flexibility and bendability are improved, but thermal expansion mismatch causes LED chip displacement
Solution Approach 1:
The patent selects an FPC substrate material with thermal expansion coefficients that closely match those of the LED chips and bonding materials. By carefully controlling the substrate's physical parameters, particularly its thermal expansion properties, the patent minimizes relative displacement between components during thermal cycling while maintaining the necessary flexibility for bending.
Solution Approach 2:
The patent uses a composite structure combining FPC substrate with specific adhesive materials that have intermediate thermal expansion properties between the FPC and LED chips. This composite approach creates a gradual transition in thermal expansion coefficients, reducing stress and displacement at the interfaces during temperature changes.
3Area of stationary object
If LED chips are densely arranged on flexible substrate, then illumination coverage is improved, but metal wire bonding becomes vulnerable to stress concentration during bending
Solution Approach 1:
The patent removes the vulnerable metal wire bonding from the flexible FPC substrate area where bending stress is concentrated. Instead, the patent uses rigid substrate mounting with direct soldering or wire bonding on a separate rigid support structure, extracting the bonding function from the flexible region to eliminate the stress concentration problem while maintaining dense LED chip arrangement for full illumination coverage.
4Illumination intensity
If multiple LED filaments are installed in single bulb, then aesthetic appearance and illumination uniformity are improved, but assembly complexity and production cost increase
Solution Approach 1:
The patent integrates multiple LED chip units onto a single FPC substrate, merging what would traditionally be separate filament assemblies into one integrated structure. The FPC substrate serves as a common platform that holds multiple LED chips in the desired spatial arrangement, allowing the entire multi-element illumination system to be manufactured and assembled as a single unit, thereby reducing assembly complexity and production costs while achieving uniform omnidirectional illumination.
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 improves heat dissipation and light emission efficiency, reduces the likelihood of conductive wire failure, and achieves uniform and omnidirectional illumination, while also stabilizing the power supply to eliminate flicker, resulting in a high-quality and efficient LED light bulb.
Implementation Method 1
a copper foil and at least one LED chip are attached on the LED filament substrate... to enhance thermal radiation and light emission efficiency
Implementation Method 2
a light conversion layer and silver plating to enhance thermal radiation and light emission efficiency... achieves uniform and omnidirectional illumination
Data Source
AI summary
An LED filament comprises at least one LED section, a conductive section, two conductive electrodes and a light conversion layer. The conductive section is used to electrically connect two adjacent LED sections. The two conductive electrodes are electrically connected to each of the LED sections. Each of the LED sections includes at least two LED chips electrically connected to each other. The light conversion layer covers the LED sections, the conductive sections and the conductive electrodes, and a part of the two electrodes is exposed respectively. Since the LED filament includes the LED section and the conductive section, when the LED filament is bent, the stress is easily concentrated on the conductive section. Therefore, the breakage probability of the conductive wires connected within the LED section is reduced during bending. The quality of the LED filament and its application is improved.