Segmented Light Pipe Reflector for Low-Angle Daylight Capture
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Solution Overview
Problem
Existing light pipe systems struggle to maximize natural daylight entry, particularly in temperate regions where the sun's angle is low, leading to significant light loss, and require effective reflector arrangements that balance light direction and efficiency without blocking unnecessary light on overcast days.
Innovation Solution
A reflector arrangement for cylindrical light pipes featuring a convex main reflector inclined at 22.5°, paired with concave side reflectors, which extends around 150°, optimizing light capture from various angles and weather conditions by directing sunlight into the pipe while minimizing blockage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a concave reflector arrangement is used to increase light entry at low solar angles, then light entry is improved, but light loss occurs when sunlight passes over the top of the light pipe
Solution Approach 1:
The reflector is divided into multiple segments: a lower concave reflector segment to capture low-angle sunlight and direct it into the light pipe, and an upper convex reflector segment to prevent sunlight from passing over the top. This segmentation allows each segment to perform its specific function optimally without interfering with the other.
Solution Approach 2:
Different portions of the reflector have different geometric properties tailored to their specific functions. The lower portion is concave to focus and direct low-angle light, while the upper portion is convex to block overhead light. This local differentiation of geometric quality optimizes performance for different solar angles.
2Illumination intensity
If the reflector angle is increased to direct low-angle light into the light pipe, then light direction is improved, but light efficiency loss increases due to steeper angles
Solution Approach 1:
The reflector angle is optimized to a specific range (15-30 degrees from vertical, preferably 22.5 degrees) that balances two competing requirements: directing low-angle sunlight into the light pipe while minimizing the steepness of the reflected light angle. This parameter optimization ensures adequate light direction without excessive efficiency loss.
3Illumination intensity
If a reflector is used to increase light entry on clear days, then light entry is improved, but more light is blocked on overcast days
Solution Approach 1:
The segmented reflector design with distinct concave and convex portions allows the system to capture beneficial direct sunlight on clear days while minimizing blockage of diffuse skylight on overcast days. The concave lower portion captures low-angle sunlight without significantly blocking the broader sky dome illumination available on overcast days.
4Illumination intensity
If a complex rotating reflector mechanism is used to optimize light capture throughout the day, then light entry is improved, but device complexity increases
Solution Approach 1:
Instead of using a complex rotating mechanism to actively track the sun, the invention uses a fixed reflector with optimized geometry that passively captures sunlight across a range of angles. The inverted approach is to accept a fixed position and optimize the reflector shape to handle varying solar angles, rather than keeping the reflector simple and rotating it to track the sun.
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 reflector arrangement enhances light entry by over 300% on clear days and maintains performance on overcast days, providing consistent lighting throughout the day without the need for complex rotating mechanisms, thus simplifying and cost-reducing the system.
Implementation Method 1
a main reflector (26) comprising an at least generally convex reflector surface which extends upwardly and is also inclined downwardly so as to be inclined towards the upper end of a light pipe
Implementation Method 2
a pair of side reflectors, one on each side of the main reflector to reflect light onto the main reflector or directly into the light pipe, characterised in that each side reflector is concave
Data Source
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AI summary
A reflector arrangement 10 for use on the upper end of a light pipe 12. The arrangement 10 includes a bell shape glassed dome 20 in which is provided a main reflector 26 in the form of a convex frusto conical part which diverges up wardly, with a side reflector 32 on each side of the main reflector 26. Each reflector 32 has a substantially part cylindrical form decreasing in width upwardly to an apex 34 adjacent to upper corners of the main reflector 26.