Temperature and pressure sensor for Cummins 3408627

Piezoelectric effect

When some dielectrics are deformed by applying force in a certain direction, charges are generated on a certain surface, and when the external force is removed, they return to the uncharged state. This phenomenon is called positive piezoelectric effect. When an electric field is applied in the polarization direction of the dielectric, the dielectric will produce mechanical deformation or mechanical pressure in a certain direction. When the external electric field is removed, the deformation or stress will disappear, which is called inverse piezoelectric effect.

Piezoelectric element

Piezoelectric sensor is a physical sensor and a power generation sensor. Commonly used piezoelectric materials are Shi Ying crystal (SiO2 _ 2) and synthetic piezoelectric ceramics.

The piezoelectric constant of piezoelectric ceramics is several times that of Shi Ying crystal, and its sensitivity is high.

4) photoelectric transducer

1. photoelectric effect

When light irradiates an object, it can be regarded as a string of photons with energy e bombarding the object. If the energy of photons is large enough, the electrons inside the substance will get rid of the constraints of internal forces and have corresponding electrical effects, which is called photoelectric effect.

1) Under the action of light, the phenomenon that electrons escape from the surface of an object is called external photoelectric effect, such as photoelectric tube and photomultiplier tube.

2) Under the action of light, the phenomenon that the resistivity of an object changes is called internal photoelectric effect, such as photoresistor, photodiode, phototransistor and phototransistor.

3) Under the action of light, an object produces electromotive force in a certain direction, which is called photovoltaic phenomenon, such as photovoltaic cell (a device sensitive to the position of the incident light spot on the photosensitive surface).

2 Photosensitive resistor

When the photoresistor is irradiated by light, electrons migrate to produce electron-hole pairs, which makes the resistivity smaller. The stronger the light, the lower the resistance. The incident light disappears, the electron-hole pair recovers, and the resistance value gradually returns to its original value.

3. Photosensitive tube

Photosensitive tubes (photodiode, phototransistor, phototransistor, etc.) belong to semiconductor devices.

4. Electroluminescence

The luminescence phenomenon produced by solid luminescent materials under the excitation of electric field is called electroluminescence. Electroluminescence is a process of directly converting electric energy into light energy. Light-emitting diode (LED) is a semiconductor electroluminescent device doped with special materials. When the PN junction is forward biased, excess energy is generated due to electron-hole recombination, which is released in the form of photons and emits light.