Variable Prism Skylight Dome for Consistent Light Output
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Solution Overview
Problem
Skylights face challenges in maintaining constant light output throughout the day, as low-angle sunlight during mornings and evenings results in reduced light entry, while high-angle sunlight at midday can cause over-illumination and 'hotspots' due to uneven light distribution.
Innovation Solution
A tubular skylight with a transparent dome and a variable prism cover, featuring circular parallel grooves with different cross-sections near the apex and periphery, directs low-angle light into the tube and reflects high-angle light, achieving a more consistent light output by refracting and reflecting sunlight at varying angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the skylight is designed to maximize light collection during morning and evening hours, then low-angle light entry is improved, but the skylight over-illuminates the room at midday creating hotspots
Solution Approach 1:
The dome cover incorporates a variable prism structure where different regions have different groove geometries. Grooves nearer the apex have one cross-sectional configuration while grooves nearer the periphery have different cross-sectional configurations. This local variation in prism properties enables different light manipulation at different locations, directing low-angle light into the tube while reflecting high-angle light away, thus achieving consistent illumination without hotspots
Solution Approach 2:
The prism grooves are designed with varying cross-sectional parameters across the dome surface. The groove geometry changes from the apex region to the periphery region, creating a gradient in light refraction and reflection characteristics. This parameter variation allows the skylight to adapt its light collection behavior throughout the day, maintaining optimal performance across different solar angles
2Ease of manufacture
If the dome uses a uniform prism structure, then manufacturing is simplified, but it cannot achieve consistent light output throughout the day
Solution Approach 1:
Rather than using a uniform prism structure throughout, the invention implements local quality variation by configuring grooves differently in different regions of the dome. The groove cross-sections change from apex to periphery, allowing each region to be optimized for its specific function while maintaining manufacturability through consistent molding processes
Solution Approach 2:
The dome's prism structure is segmented into multiple groove elements distributed across the surface. Each groove acts as an independent optical element with specific geometry tailored to its location. This segmentation allows the complex variable prism function to be achieved through repeated patterning that can be manufactured using standard molding techniques
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 design ensures a more uniform light distribution throughout the day, reducing glare, hotspots, and chromatic aberrations, while minimizing the risk of fire from intense sunlight and maintaining average illumination levels.
Implementation Method 1
The cover is formed with a variable prism that directs low-angle light into the skylight tube and that reflects away some high-angle light
Implementation Method 2
The cover is formed with a variable prism that directs low-angle light into the skylight tube and that reflects away some high-angle light
Data Source
Figure 1
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Figure 6~8
AI summary
The inside surface of a cover (21) for a skylight is molded to have a variable prism that directs low-angle light into the skylight tube and that reflects away some high-angle light, to achieve a more constant light output over the course of the day. The prism is established by a series of circular parallel grooves (44), with grooves nearer the apex of the cover having cross-sections that are different than the cross-sections of grooves nearer the periphery (42) of the cover.