Motorized Window Treatment Control for Sunrise Glare Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing load control systems for motorized window treatments struggle to accurately distinguish between sunny and cloudy days, leading to potential glare issues around sunrise and sunset on sunny days due to incorrect threshold settings.
Innovation Solution
The system measures total light intensity and solar elevation angle to dynamically adjust the cloudy-day threshold, enabling or disabling the sunlight penetration limiting mode based on these conditions, ensuring accurate differentiation between sunny and cloudy days to prevent glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant threshold is used to detect cloudy conditions, then the system can operate with simple logic, but it fails to accurately distinguish between sunny and cloudy days around sunrise and sunset
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a static constant threshold to a dynamic time-varying threshold. The threshold is adjusted based on the time of day, specifically lowering it during sunrise and sunset periods when natural light levels are naturally low. This allows the system to accurately distinguish between sunny and cloudy conditions during these critical transition periods while maintaining simple operational logic throughout the day.
Solution Approach 2:
The patent implements parameter changes by modifying the threshold parameter based on temporal conditions. A time-of-day parameter is introduced that adjusts the threshold value: during sunrise and sunset periods, the threshold is set to a lower value to account for naturally reduced light levels, while during midday hours, the higher constant threshold is used. This parameter adaptation resolves the detection accuracy issue without significantly increasing system complexity.
2Object-affected harmful factors
If the system controls window treatments to limit sunlight penetration on sunny days, then occupant comfort is improved, but glare may occur around sunrise and sunset due to incorrect threshold detection
Solution Approach 1:
The dynamic threshold adjustment prevents premature or incorrect activation of glare control measures during sunrise and sunset. By lowering the threshold during these periods, the system allows natural light entry even when total light levels are low, avoiding unnecessary window treatment adjustments that would block beneficial ambient light while still preventing glare when appropriate.
Solution Approach 2:
The system uses feedback from the time-of-day parameter to continuously adapt the threshold setting. This feedback mechanism ensures that the threshold reflects current environmental conditions, enabling accurate differentiation between cloudy days (where glare control is unnecessary) and sunny days during sunrise/sunset (where glare control should be activated).
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 effectively prevents sun glare by accurately controlling sunlight penetration, enhancing occupant comfort and reducing distractions during critical times, such as sunrise and sunset on sunny days.
Implementation Method 1
The load control system may comprise a photosensor (i.e., a daylight sensor or a radiometer) mounted to a window or to the outside of the building for detecting a cloudy condition. The load control system may detect the cloudy condition, for example, if a total light level measured by the photosensor is below a constant threshold THCONST.
Data Source
AI summary
A method comprises measuring a light intensity at a window; determining if the light intensity exceeds a cloudy-day threshold; operating in a sunlight penetration limiting mode to control the motorized window treatment to control the sunlight penetration distance in the space; enabling the sunlight penetration limiting mode if the light intensity is greater than the cloudy-day threshold; and disabling the sunlight penetration limiting mode if the total lighting intensity is less than the cloudy-day threshold. The cloudy-day threshold is maintained at a constant threshold if a calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold varies with time if the calculated solar elevation angle is less than the predetermined solar elevation angle. The cloudy-day threshold is a function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.