Beam Detector Distance Measurement Using Phase Shift
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Solution Overview
Problem
Projected beam smoke detectors face challenges in accurately measuring beam travel distance and detecting obstructions, which affect sensitivity and can be manually error-prone, especially when using a common housing for the transmitter and receiver.
Innovation Solution
The implementation of automatic distance measurement using a mono-chromatic light source or phase shift modulation to determine the distance between the transmitter and receiver, allowing for real-time adjustment of sensitivity and detection of obstructions, with the option of separate transmitters and receivers for divergent measurement requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual measurement of beam travel distance is performed during installation, then sensitivity parameter can be set accordingly, but the process is error-prone and labor-intensive
Solution Approach 1:
The detector automatically measures beam travel distance using its own transmitter and receiver components, eliminating the need for manual measurement during installation. The system performs self-diagnosis and self-configuration, setting the sensitivity parameter automatically based on the measured distance.
Solution Approach 2:
The patent replaces manual mechanical measurement methods with an optical measurement system. The transmitter emits a beam that travels to a reflector and back to the receiver, using the time of flight or phase shift of the optical signal to calculate distance automatically.
2Device complexity
If a common housing is used for transmitter and receiver with reflected beam, then device complexity is reduced, but beam travel can be improperly interfered with by reflective obstructions
Solution Approach 1:
The system continuously monitors the reflected beam signal and compares it against expected parameters. When an obstruction is detected (such as a reflective surface blocking the beam path), the system generates an alarm or error signal, providing feedback about the abnormal condition.
Solution Approach 2:
The patent measures beam travel distance continuously or periodically to detect obstructions before they cause false readings or detection failures. By monitoring the round-trip time or phase shift, the system can identify when an object has entered the beam path and alert users before accurate detection is compromised.
3Measurement precision
If automatic distance measurement is implemented, then sensitivity settings are accurate and obstructions are detected, but device complexity and cost increase
Solution Approach 1:
The patent designs the measurement circuitry to serve multiple functions: it measures beam travel distance for sensitivity calibration, detects obstructions in the beam path, and provides diagnostic information about system health. This multi-functionality justifies the added complexity by delivering multiple benefits from a single system.
Solution Approach 2:
The transmitter used for smoke detection is also used for distance measurement, and the receiver serves dual purposes for both functions. The housing structure is designed to accommodate both smoke detection and distance measurement operations, merging multiple functions into a unified system rather than adding separate dedicated components.
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 solution enables cost-effective, automatic measurement and detection of beam interference, ensuring accurate sensitivity settings and timely notification of obstructions to regional monitoring systems, enhancing the reliability and efficiency of projected beam smoke detectors.
Implementation Method 1
measuring the time it takes for the receiver to receive the signal. The distance would correspond to the time measures multiplied by the speed of light in air
Implementation Method 2
measuring the phase shift of the received signal relative to the transmitted signal. The phase shift would be proportional to the distance
Implementation Method 3
A reflector 26 is displaced from detector 12-1 and positioned so that the incident beam BE reflects therefrom, as beam BR and returns to housing 20
Data Source
AI summary
A projected beam smoke detector includes circuitry and control software to measure a distance a beam travels between the detector's transmitter and receiver. Either a time-based or a phase-based measurement methodology could be used. A sensitivity parameter of the detector could be set in response to the results of the measurement.