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Pressure sensor working principle

time£º2018-04-23 16:56    source£ºoem pressure sensor

 Pressure sensor working principle 

1 Introduction


Pressure sensors are the most commonly used sensors in industrial practice. The output of a common ordinary pressure sensor is an analog signal, or in a segment

During the interval of the renewal, the output is a digital signal. The commonly used pressure sensors are mainly made using piezoelectric effect.

Sensors are also called piezoelectric sensors.


2. Classification of pressure sensors


There are many types of pressure sensors, mainly strain gauge pressure sensors, ceramic pressure sensors, diffusion silicon pressure sensors, sapphire pressure

Force sensors, piezo-electric pressure sensors, etc. Below, I introduce them to these types of operating principles.


3. Strain gauges How pressure sensors work


The center of the strain gage pressure sensor is some resistance strain gage. When the wire is affected by external force, the length and cross-sectional area will change. From the above formula, it is easy to see that the resistance value will change, assuming that the metal When the filament is elongated by the external force effect, its length is added, and the cross-sectional area decreases, and the resistance value increases. When the wire is tightened by the external force effect, the length decreases and the cross section is added, and the resistance value decreases. Simply measuring the change in the resistance (usually the voltage at the two ends of the measuring resistor), the strain of the strained wire can be achieved.


4. How Ceramic Pressure Sensors Work


The principle of ceramic pressure sensor: anti-corrosion ceramic pressure sensor does not transfer the liquid, the direct effect of pressure on the front surface of the ceramic diaphragm,

Make small deformation of the diaphragm, and the thick film resistor is printed on the opposite side of the ceramic diaphragm, connecting it into a Wheatstone bridge (closed bridge), because the pressure sensitive electricity

The piezoresistive effect of the resistor causes the bridge to generate a voltage signal proportional to the pressure, which is highly linear and proportional to the energizing voltage.

No. according to the pressure range is not the same as 2.0 / 3.0 / 3.3 mV / V, etc., can be compatible with the strain sensor. After laser calibration,

The sensor has high temperature stability and time stability, the sensor comes with a temperature compensation of 0 ~ 70 °C, and can be directly touched with the vast majority of media

5. Diffusion Silicon Pressure Sensor Operation


Operation principle: The pressure of the measured medium directly affects the diaphragm of the sensor (stainless steel or ceramic), so that the diaphragm undergoes micro displacement proportional to the pressure of the medium, so that the resistance value of the sensor changes, and the electronic circuit is used to inspect this. Change, and convert to output a gauge measurement signal that corresponds to this pressure.

6. How Sapphire Pressure Sensors Work


Principle of sapphire pressure sensor: Using the principle of strain-resistance operation, under the effect of pressure, the titanium alloy receiving diaphragm is deformed. After the deformation is perceived by the silicon-sapphire sensitive element, the output of the bridge will change and the fluctuation and change will be changed. Measuring pressure is proportional.

The circuit of the sensor can ensure the power supply of the strain bridge circuit and convert the unbalanced signal of the strain bridge into a uniform electrical signal output (0-5, 4-20mA or 0-5V). In the absolute pressure sensor and transmitter, the sapphire sheet is connected with the solder of the ceramic base glass and functions as an elastic element. The measured pressure is converted into deformation of the strain gauge and then the pressure is measured.

7. Piezoelectric pressure sensor works


Operating principle: When the inner side of a thin cylinder is subjected to a pressure effect, the internal tension of the cylinder increases, and then its natural oscillation frequency increases. Use this effect. Simply measuring the natural oscillation frequency of the vibrator can tell the pressure. The measurement accuracy of the natural oscillation frequency of the cylinder is determined by the resonance quality factor Q of the cylinder, the signal processing circuit, and the accuracy of the clock signal. It has the characteristics of simple structure, small size, light weight, long service life and other excellent features. Piezoelectric acceleration sensors have been widely used in the oscillation and impact measurement of aircrafts, cars, ships, bridges, and constructions, especially in the aviation and aerospace fields.

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