Scanning Smoke Detector Power Interlock for Eye-Safe Operation

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Solution Overview

Problem

Existing scanning smoke detectors using high-powered laser beams pose a risk of eye damage, especially when individuals use magnifying optics, making them unsuitable for autonomous operation in environments where people may be present.

Innovation Solution

Implement a safety interlock system that uses the LiDAR signal to detect the presence of a solid object, reducing high-power laser pulses until the obstruction is cleared, ensuring the system operates at Class 1 safety levels even when magnifying optics are used.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-powered laser beams are used for smoke detection, then detection range and sensitivity are improved, but eye safety deteriorates

Engineering Contradiction:
Improvesmoke detection sensitivityVSAvoideye damage risk
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The laser beam power is made dynamic rather than static. The system automatically adjusts the laser power level based on detected conditions: operating at high power when safe for smoke detection sensitivity, and rapidly reducing to low power when objects enter the beam path. This dynamic adaptation resolves the contradiction between maintaining high detection sensitivity and ensuring eye safety.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements a feedback mechanism where the LiDAR signal detects the presence of solid objects in the beam path, and this information feeds back to control the laser power level. The feedback loop enables automatic safety interlock functionality, allowing the system to maintain optimal detection performance while preventing eye damage through real-time monitoring and adjustment.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If the laser power is reduced to ensure safety, then eye safety is improved, but smoke detection sensitivity deteriorates

Engineering Contradiction:
Improveeye safetyVSAvoidsmoke detection sensitivity
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The laser operates at two distinct power levels dynamically switched based on safety conditions. At low power level, the system ensures eye safety while maintaining basic operational functionality. At high power level, the system achieves optimal smoke detection sensitivity. This dynamic power management resolves the contradiction by applying the appropriate power level contextually.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system periodically scans the environment with the laser beam and rhythmically adjusts power levels between high and low states based on detected conditions. This periodic scanning and power adjustment enables the system to maintain safety while periodically achieving high-sensitivity detection during safe operating cycles.

Inventive Principle:
Principle #19Periodic action

3Object-affected harmful factors

If a safety interlock system is implemented, then eye safety is improved, but device complexity increases

Engineering Contradiction:
Improveeye safetyVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The LiDAR signal serves multiple functions: it detects smoke particles for fire detection and simultaneously detects solid objects for safety interlock purposes. This multi-functionality allows the system to implement eye safety protection without adding separate dedicated sensors or systems, thereby limiting the increase in device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The safety interlock functionality is merged with the existing smoke detection system by utilizing the same LiDAR signal and processing infrastructure. The object detection and power control functions are integrated into the existing system architecture rather than implemented as separate standalone systems, reducing overall complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

Prevents eye damage from high-powered laser beams by rapidly reducing power when individuals enter the beam path, allowing the system to maintain Class 1 safety classification and operate safely in populated areas.

Implementation Method 1

a light receiver configured to receive a reflected portion of the beam of light and determine a presence of smoke particles in the area based on the reflected portion

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

When a beam of laser light is emitted in an indoor environment, it may encounter an object, substance, or material (e.g., smoke particles) and light may be reflected and/or scattered to the light receiver

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

a rotational component configured to rotate the emitter such that the beam periodically scans across an area

Methodology Applied
Scientific EffectRotational motion:

Data Source

PatentEP4174810B1Operating a scanning smoke detector
Publication Date: 2026.01.28 HONEYWELL INTERNATIONAL INC
  • EP4174810B1 patent drawingFigure 1
  • EP4174810B1 patent drawingFigure 2
  • EP4174810B1 patent drawingFigure 3

AI summary

Apparatuses, methods, and computer-readable media for operating a scanning smoke detector are described herein. One apparatus a laser emitter configured to emit a beam of light, a rotational component configured to rotate the emitter such that the beam periodically scans across an area, and a light receiver configured to receive a reflected portion of the beam of light and determine a presence of smoke particles in the area based on the reflected portion. The smoke detection apparatus can be configured to operate at a first power level, decrease the beam to a second power level responsive to a determination that an object in the area is in a path of the beam, and increase the beam to the first power level responsive to a determination that the object is no longer in the path of the beam.