Smoke Detector Light Shield for False Alarm Reduction
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Solution Overview
Problem
Photoelectric smoke detectors often trigger false alarms due to ambient light from sources like germicidal systems, operating room lights, and remote controls, which can interfere with their light receivers and cause incorrect smoke detection.
Innovation Solution
The integration of a light shield that attenuates ambient light, specifically designed to block or minimize the transmission of infrared, ultraviolet, and visible light to the electro-optical light receivers in smoke detectors, using materials such as black neoprene rubber, polypropylene, and metals, and configured to surround the light source or receiver, or integrated into the external housing to prevent false triggering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light receiver is exposed to ambient light sources in the room, then the smoke detector can detect smoke through light changes, but false alarms are triggered due to interference from external light sources
Solution Approach 1:
A light shield is introduced as an intermediary component between the ambient light sources and the light receiver. The shield selectively blocks harmful ambient light (infrared, ultraviolet, and visible light from external sources) while allowing the detection of smoke-induced light changes, thus resolving the contradiction between maintaining detection accuracy and preventing false alarms from light interference
Solution Approach 2:
The light shield is positioned specifically around the light receiver to provide localized protection. By applying the shielding function only where needed (at the receiver location) rather than throughout the entire detector, the solution maintains smoke detection capability while preventing false triggering from ambient light sources in specific directions
2Reliability
If a light shield is added to block ambient light, then false alarms are reduced, but the device complexity increases
Solution Approach 1:
The light shield is designed to perform multiple functions simultaneously: it blocks infrared light, ultraviolet light, and visible light from various external sources (germicidal systems, operating room lights, remote controls, etc.). This multi-functional approach reduces the need for multiple separate shielding components, thereby limiting the increase in device complexity while achieving comprehensive protection against false alarms
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
Effectively reduces the occurrence of false alarms by shielding the light receivers from ambient light, ensuring accurate smoke detection and minimizing interference from external light sources.
Implementation Method 1
a shield distinct from the external housing that includes a material which attenuates a majority amount of light within the particular range of light that the light source may be configured to only emit and/or the range of light the electro-optical light receiver may configured to only convert to photocurrent
Implementation Method 2
an electro-optical light receiver arranged within the smoke detector to receive direct and/or indirect light from the light source
Data Source
AI summary
Smoke detectors and smoke alarms are provided which have one or more light shields configured to block or minimize the transmission of ambient light to their light receivers. Light shield configurations for facilitating such functionality are provided as well. The shield/s include a material which attenuates a majority amount of light within a particular range of light that a light source of the smoke detector may be configured to only emit and/or the range of light the light receiver may configured to only convert to photocurrent. In some cases, the shield/s surrounds the light source and/or the light receiver arranged external to an interior chamber of the smoke detector. In some cases, the shield/s may at least partially span a connection side of an external housing of the smoke detector. Alternatively, the shield may be arranged in a space between the interior chamber and the connection side of the housing.