Bidirectional Spreading Lens for Stretched Leadframe LED Arrays
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Solution Overview
Problem
The high cost and material inefficiency of dense LED arrays mounted on long printed circuit boards in LED retrofit tube lamps for large indoor lighting applications, which are similar to fluorescent tube lamps, due to the large number of LEDs and the extensive area of the PCB required to maintain uniform lighting.
Innovation Solution
A stretchable leadframe assembly with connected leadframes and folded interconnects is used, allowing LEDs to be spaced out spatially, and optical elements are positioned to distribute light uniformly, reducing the material and processing needs compared to traditional PCBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a dense array of LEDs is mounted on a long PCB to provide uniform lighting in large indoor areas, then the lighting uniformity is improved, but the cost and material usage increase significantly
Solution Approach 1:
The patent divides the lighting system into multiple independent modules, each containing a small number of LEDs (e.g., 3-5 LEDs per module) mounted on compact PCB segments. These modules are arranged in series along the linear lighting structure, replacing the traditional single large PCB with dense LED arrays. This segmentation reduces the total number of LEDs required while maintaining uniform lighting through proper module spacing and optical design.
Solution Approach 2:
The patent transitions from a two-dimensional dense LED array on a large PCB to a one-dimensional linear arrangement of modular LED groups. By distributing LEDs along the length of the linear lighting apparatus in spaced-out modules rather than concentrating them on a large surface area, the design achieves uniform lighting with fewer total LEDs and less PCB material.
2Quantity of substance
If LEDs are spaced out with large pitches in linear lighting applications, then the number of LEDs and PCB area are reduced, but maintaining uniform light distribution becomes difficult
Solution Approach 1:
The patent applies different optical characteristics to different parts of the lighting system by using optical elements (lenses, reflectors, diffusers) with specific properties tailored to each module's position and function. For example, optical elements with different beam angles, refractive indices, or surface textures are used to compensate for variations in LED spacing and ensure uniform light distribution across the entire linear lighting apparatus.
Solution Approach 2:
The patent introduces optical elements as intermediary components between the LEDs and the illuminated space. These optical elements (such as diffusers, lenses, or reflectors) act as mediators that redistribute light from the spaced-out LEDs, smoothing out intensity variations and achieving uniform illumination despite the larger pitch between individual LEDs.
3Length of stationary object
If a long PCB is used to mount many LEDs for fluorescent tube replacement, then the lighting coverage is improved, but the manufacturing cost and complexity increase
Solution Approach 1:
The patent divides the long lighting structure into multiple short PCB modules, each containing a small number of LEDs and simple circuitry. These modules are connected in series through simple interconnections, replacing the single complex long PCB. This segmentation simplifies manufacturing, reduces PCB material usage, and lowers overall system cost while maintaining the required lighting coverage length.
Solution Approach 2:
The patent employs modular PCB segments that can be independently manufactured, tested, and assembled. This dynamic modular approach allows for flexible configuration and simplifies manufacturing processes compared to producing a single large complex PCB, enabling easier quality control and reduced manufacturing costs while achieving the same lighting coverage.
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 approach reduces the number of LEDs required and the material usage, resulting in a more cost-effective and efficient linear lighting solution with a uniform light distribution, similar to traditional fluorescent tube lamps.
Implementation Method 1
Each bidirectional spreading lens is directly molded over a corresponding LED. The bidirectional spreading lenses redirect light from the LEDs in predetermined patterns along the stretched leadframe assembly.
Data Source
AI summary
A solid state light-emitting device (LED) lighting apparatus comprising a leadframe assembly comprising leadframes spaced apart at a pitch, each leadframe comprising at least one pad, interconnects each linking two adjacent leadframes, LEDs mounted on the leadframes, and bidirectional spreading lenses disposed about the LEDs, each bidirectional spreading lens having a spreading axis and a null axis perpendicular to the spreading axis, each bidirectional spreading lens directing more light in opposite directions along the spreading axis than the null axis, the spreading axis being aligned along the length of the stretched leadframe assembly.