Compact Optical Smoke Detector Using Geometric Light Isolation

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Solution Overview

Problem

Optical smoke detectors are typically large in size and prone to false alarms due to noise light reflection and dust contamination, making them unsuitable for widespread domestic and business use.

Innovation Solution

A compact optical smoke detector design utilizing geometric optical elements and opto-isolating structural chamber columns with matched refractive indices to minimize noise light reflection and dust scattering, ensuring reliable smoke detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical smoke detector components are arranged inside a chamber, then smoke detection function is achieved, but the detector size becomes large

Engineering Contradiction:
Improvesmoke detection functionVSAvoiddetector size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent combines the light source and light sensor into a single integrated optical detection component, merging multiple functions into one element. This integration significantly reduces the space required for separate component arrangements while maintaining the smoke detection capability through the combined optical functions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a nested structural arrangement where the optical detection component is positioned within a compact chamber configuration. The light source and sensor are arranged in a nested geometry that optimizes space utilization, allowing the optical path to be contained within a minimal volume while still enabling effective smoke particle detection.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If conventional optical components are used in smoke detectors, then smoke detection is enabled, but false alarms occur due to noise light reflection and dust contamination

Engineering Contradiction:
Improvesmoke detection capabilityVSAvoidnoise light reflection and dust contamination
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of dust particles and noise light into a beneficial detection mechanism. By designing the optical system to detect light scattering patterns characteristic of smoke particles while filtering out reflections from stationary dust, the system transforms potential interference into a refined detection capability that distinguishes between temporary smoke events and permanent dust contamination.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies different optical properties to different regions of the detection chamber. The optical components are designed with specific surface treatments and geometric arrangements that create localized optical zones - one optimized for detecting smoke particle scattering and another that minimizes reflection from dust deposits on chamber walls. This spatial differentiation of optical quality reduces false alarms from dust while maintaining smoke detection sensitivity.

Inventive Principle:
Principle #3Local quality

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 achieves a compact, robust smoke detector that is resistant to dust contamination and ambient light interference, providing reliable smoke detection with minimal false alarms.

Implementation Method 1

The received light intensity will be reduced by absorption due to smoke, air-borne dust, or other substances

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

a photoelectric receiver (typically a photodiode)

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 3

If the air in the chamber contains particles (smoke or dust), the light is scattered and some of it reaches the sensor

Methodology Applied
Scientific EffectScattering: Scattering

Data Source

PatentEP4036884B1Compact optical smoke detector system and apparatus
Publication Date: 2025.09.10 ANALOG DEVICES INC
  • EP4036884B1 patent drawingFigure 1
  • EP4036884B1 patent drawingFigure 2
  • EP4036884B1 patent drawingFigure 3

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.