In the security industry, sensors are a fairly widespread application and have a very important role to play. A sensor is a physical device or biological organ that detects and senses external signals, physical conditions (such as light, heat, humidity) or chemical components (such as smoke) and transmits the detected information to other devices or organs. Introduce several common sensors:
Resistive sensor:
Load cell
Resistance strain sensor
Piezoresistive sensor
Radar sensor
Resistive sensor:
A resistive sensor is a device that converts measured physical quantities such as displacement, deformation, force, acceleration, humidity, temperature, etc. into resistance values. There are mainly resistive strain sensors such as resistance strain type, piezoresistive type, thermal resistance, heat sensitive, gas sensitive and humidity sensitive.
Load cell
The load cell is a force-electrical conversion device that converts gravity into an electrical signal and is a key component of the electronic scale.
There are many kinds of sensors that can realize force-electric conversion, and common ones are resistance strain type, electromagnetic force type and capacitance type. The electromagnetic force type is mainly used for electronic balances, and the capacitive type is used for some electronic crane scales, and most of the scale products use resistance strain gauge load cells. The resistance strain gauge load cell has a simple structure, high accuracy, wide application range, and can be used in a relatively poor environment. Therefore, the resistance strain type load cell is widely used in the scale.
Resistance strain sensor
The strain gauge in the sensor has a strain effect of the metal, that is, mechanical deformation under the action of an external force, so that the resistance value changes accordingly. There are two types of resistance strain gauges: metal and semiconductor. Metal strain gauges are available in wire, foil and film. Semiconductor strain gauges have the advantages of high sensitivity (usually dozens of times of silk and foil) and small lateral effects.
Piezoresistive sensor
Piezoresistive sensors are devices that are fabricated by diffusion resistance on a substrate of a semiconductor material in accordance with the piezoresistive effect of the semiconductor material. The substrate can be directly used as a measuring sensing element, and the diffusion resistor is connected in the form of a bridge in the substrate. When the substrate is deformed by an external force, the resistance values ​​will change, and the bridge will produce a corresponding unbalanced output. The substrate (or diaphragm) used as a piezoresistive sensor is mainly made of silicon wafer and tantalum. The silicon piezoresistive sensor made of sensitive material is getting more and more attention, especially in measuring pressure. And speed solid state piezoresistive sensors are most commonly used.
Radar sensor
The radar sensor is a replacement device that can convert the microwave echo signal into an electrical signal, and is a core chip of a radar speedometer, a water level gauge, an automobile ACC auxiliary cruise system, an automatic door sensor, and the like. High degree of formation, sensitive sensitivity, no need to touch.
The low location lighting is an unique system that allows all evacuation routes to stay illuminated, thereby communicating a clear, continuous and unambigous 'means of escape' message which lead to a safe place. The locations of fire fighting equipment are also clearly marked as part of the system along the escape routes. This reduces possible confusion and panic, factor that hamper the safe egress from occupied areas.
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