Fire Detector Sensor Date Code via Resistor Potential Divider
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Solution Overview
Problem
Fire detectors with multiple sensing elements face challenges in accurately tracking the decay of sensitivity over time, leading to more frequent and costly manual inspections, as different sensors decay at varying rates.
Innovation Solution
A fire detector system that uses a potential divider circuit with resistors to provide a date code indicative of the sensor's manufacturing period, allowing remote monitoring and self-testing, minimizing hardware and maintenance costs by encoding the date code in the voltage midpoint, which can be read by an A/D converter and communicated to a central control unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a manufacturing date code is entered into an EEPROM to track sensor decay, then the ability to monitor sensor sensitivity changes is improved, but the hardware cost increases
Solution Approach 1:
The patent replaces the expensive EEPROM with a simple resistor that serves as a one-time date code indicator. The resistor is selected during manufacturing to represent the sensor's production date and is never changed, providing a permanent, read-only date code without requiring programmable memory hardware.
Solution Approach 2:
The patent replaces the electronic EEPROM memory system with a passive electrical component (resistor) that stores information through its resistance value. This substitution eliminates the need for programmable memory while achieving the same date code storage function using a simpler, cheaper component.
2Adaptability or versatility
If multiple different types of sensors are provided in a fire detector, then the detection capability is improved, but the frequency of manual inspection increases due to different decay rates
Solution Approach 1:
The patent implements a feedback mechanism where the system automatically reads the resistor-based date codes, calculates the age of each sensor, and compares it against predetermined replacement thresholds. This automated monitoring provides continuous feedback on sensor status, eliminating the need for manual inspections to track sensor decay.
Solution Approach 2:
The system performs self-monitoring of sensor age and decay status by automatically reading the resistor date codes and calculating sensor lifespan. This self-service capability allows the fire detector to track its own maintenance requirements without external intervention, reducing manual inspection needs.
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
Enables cost-effective and efficient monitoring of sensor decay, reducing the need for frequent manual inspections and allowing for predictive maintenance, improving the reliability of fire detection systems by ensuring timely replacement of sensors.
Implementation Method 1
first and second resistors connected in series, a DC voltage source connected to the resistors, and means for monitoring the voltage at the midpoint of a potential divider constituted by the series-connected resistors
Data Source
AI summary
A detector comprises a detector base and a sensor, first and second resistors connected in series, a DC voltage source (Vref) connected to the resistors, and means for monitoring the voltage at the midpoint of a potential divider constituted by the series-connected resistors. The first and second resistors are rated so that the midpoint voltage is indicative of the date of manufacture of the sensor.