Compact Optical Smoke Detector With Ambient-Light Shielding
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Solution Overview
Problem
Optical smoke detectors are typically large and prone to false alarms due to dust and ambient light interference, limiting their use in residential and business settings, while ionization detectors pose regulatory challenges with radioactive isotopes.
Innovation Solution
A compact optical smoke detector design using opto-isolating structural chamber columns with matched refractive indices and smooth surfaces to minimize light reflection and absorption, combined with geometric elements to redirect ambient light away from the detection area, ensuring reliable smoke detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If optical smoke detectors use a compact design, then the device size is reduced, but light reflection and ambient light interference increase causing false alarms
Solution Approach 1:
A light shield is introduced as an intermediary element between the light source and the photosensitive sensor. This shield blocks direct light paths and prevents ambient light from reaching the sensor, thereby eliminating false alarms while maintaining a compact detector design.
Solution Approach 2:
The interior surfaces of the detection chamber are selectively treated with different properties: the light shield has light-absorbing or light-blocking characteristics, while the chamber walls have light-reflecting properties to redirect scattered smoke-laden light toward the sensor. This local differentiation of surface properties optimizes light management in the compact space.
2Volume of moving object
If optical smoke detectors use a compact design, then the device size is reduced, but dust accumulation increases causing false alarms
Solution Approach 1:
A dust cap is introduced as a removable component that can be extracted from the detector. This dust cap seals the internal optical components when not in use, preventing dust accumulation on the light shield and sensor surfaces, thereby maintaining detection accuracy in compact designs.
Solution Approach 2:
The dust cap provides preliminary protection by preventing dust from settling on critical optical surfaces before contamination can occur. This proactive approach maintains optical clarity without requiring complex cleaning mechanisms in the compact device.
3Volume of moving object
If optical smoke detectors use a compact design, then the device size is reduced, but manufacturing complexity increases
Solution Approach 1:
The light shield serves multiple functions simultaneously: it blocks direct light from reaching the sensor, reflects scattered smoke-laden light toward the sensor, and provides a mounting structure for the dust cap. This multi-functionality reduces the number of separate components needed, simplifying manufacturing despite the compact design.
Solution Approach 2:
The dust cap and light shield are integrated into a unified assembly where the dust cap attaches to the light shield structure. This merging of components reduces part count and assembly steps, making the compact design manufacturable without excessive complexity.
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 design enhances the longevity and efficacy of optical smoke detectors by reducing false alarms and maintaining sensitivity to smoke particles, allowing for a compact, robust, and cost-effective solution suitable for widespread use.
Implementation Method 1
the light emitted by the light source passes through the air being tested and reaches the photosensor. The received light intensity will be reduced by absorption due to smoke, air-borne dust, or other substances
Implementation Method 2
If the air in the chamber contains particles (smoke or dust), the light is scattered and some of it reaches the sensor, triggering the alarm
Implementation Method 3
opto-isolating structural chamber columns with matched refractive indices and smooth surfaces to minimize light reflection and absorption
Data Source
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AI summary
Device for optically detecting smoke and implementing thereof. Apparatus and methods for detecting the presence of smoke in a small, long-lasting smoke detector are disclosed. Specifically, the present disclosure shows how to build a very compact housing around the smoke detector while keeping the reflections from the housing structure to a very low value while satisfying all the other peripheral needs of fast response to smoke and preventing ambient light. This allows very small measurements of light scattering of the smoke particles to be reliable in a device resistant to the negative effects of dust. In particular, geometrical optical elements, e.g., cap and optical defection elements, are disclosed.