Non-contact Heat Radiation Sensor for Danger Detector
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Solution Overview
Problem
Existing danger detectors face challenges in accurately detecting ambient temperature due to the use of point-form NTC resistors, which require precise mechanical positioning and are susceptible to directional dependencies, and are complicated by the need for electrical connections that can cause optical scattering and installation difficulties.
Innovation Solution
A danger detector with a transparent housing part for mid-infrared heat radiation, equipped with a non-contact heat radiation sensor and processing unit that monitors sensor signals for flicker frequencies and ambient temperature, allowing for direction-independent temperature acquisition without the need for separate temperature sensors or complex electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a non-contact heat radiation sensor is used to detect ambient temperature, then directional dependency is eliminated and mechanical positioning precision is no longer required, but the housing must be made transparent to mid-infrared radiation which complicates the housing construction
Solution Approach 1:
The alarm cover is divided into two functional parts: a first housing part made transparent to mid-infrared radiation for the heat radiation sensor, and a second housing part that is light-tight for other components. This segmentation allows each part to be optimized for its specific function while reducing overall system complexity.
Solution Approach 2:
The heat radiation sensor serves dual purposes: it detects both open fire conditions and ambient temperature. By evaluating different characteristics of the same sensor signal (flicker frequencies for fire, steady component for temperature), the system eliminates the need for separate temperature sensing hardware, reducing device complexity.
2Ease of manufacture
If electrical connections are made through the measurement chamber for smoke detection, then the temperature sensor can be connected to the evaluation unit, but optical scattering occurs and the construction becomes complex
Solution Approach 1:
The electrical connection for the heat radiation sensor is routed through a separate path that does not pass through the optical measurement chamber. This extraction of the electrical connection from the optical path eliminates optical scattering while maintaining electrical connectivity between the sensor and evaluation unit.
3Use of energy by moving object
If an NTC resistor is used for temperature detection, then the temperature can be detected electrically, but precise mechanical positioning is required and the sensor must be mechanically protected from the environment
Solution Approach 1:
The mechanical contact-based NTC resistor temperature sensing is replaced with a non-contact heat radiation sensor that detects temperature through mid-infrared radiation. This substitution eliminates the need for precise mechanical positioning and mechanical protection, as the sensor can be positioned anywhere within the infrared-transparent housing part and naturally isolates the electronic components from the environment.
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 efficient and accurate detection of open fires and ambient temperatures with reduced installation complexity and directional dependencies, improving the reliability and precision of temperature measurements.
Implementation Method 1
a non-contact heat radiation sensor optically aligned to the housing part and sensitive for the incident heat radiation is disposed in the alarm housing
Implementation Method 2
the heat radiation sensor has a processing unit for further processing of a sensor signal output by the heat radiation sensor connected downstream from it and wherein the processing unit is configured to monitor the sensor signal for the occurrence of significant fluctuations or flicker frequencies for open fire as well as to establish from a steady component of the sensor signal a temperature value for an ambient temperature
Data Source
AI summary
A danger detector, for example a flame detector, includes an alarm housing with an alarm cover. The housing part of the alarm cover is permeable to heat radiation in the central infrared range. A non-contact, optical heat radiation sensor which is sensitive to the incoming heat radiation and optically oriented to the housing part is arranged in the alarm housing. A processing unit for further processing a sensor signal emitted by the heat radiation sensor is mounted downstream of the heat radiation sensor. The processing unit is designed to monitor the signal emitted by the sensor with respect to significant fluctuations or flicker frequencies for open flames and to determine, based on a direct component of the signal emitted by the sensor, a temperature value for the ambient temperature in the surroundings of the danger detector. The heat radiation sensor may be a thermopile or a bolometer.