The principle and classification of Potentiometer displacement sensor

1, the line potentiometer displacement sensor

In order to overcome the disadvantages of wire wound potentiometer, people up and down the resistance of the material and manufacturing process a lot of time, the development of all kinds of wire wound potentiometer.

(1) synthetic membrane potentiometer

Potentiometer resistor body is to use synthetic membrane has a certain resistance resistance film is formed on the slurry spraying in insulating the skeleton, the potentiometer has the advantage of high resolution, resistance range is very wide (100-4.7 M Ω), good wear resistance, simple process, low cost, good linearity of input - output signal etc, its main disadvantage is that large contact resistance, power is not enough, easy to moisture absorption, noise big, etc.

(2) the metal film potentiometer

Metal film resistor by material such as alloy, metal or metal oxide by vacuum sputtering or plating method, a layer of film is deposited on the ceramic substrate.

Metal film resistor with infinite resolution, small contact resistance, good heat resistance, its full temperature can reach 70 ℃. Compared with wire wound potentiometer, it is the distribution of the distributed capacitance and inductance is small, so it is particularly well adapted for use under the condition of high frequency. It's just above wire wound potentiometer noise signal. Metal film resistor disadvantage is that the wear resistance is poorer, narrow range of impedance values between 10-100 k Ω commonly. As a result of these disadvantages limit the use of it.

(3) the conductive plastic potentiometer

Conductive plastic potentiometer, also known as organic solid potentiometer, the potentiometer resistor body is made from plastic powder and powder of conductive materials by the molding pressure. Conductive plastic potentiometer good abrasion resistance, long service life and allow the brush contact pressure is very big, so it is still under the harsh environment, such as vibration and shock can work reliably. In addition, its high resolution, good linearity, large range of resistance and can bear larger power. The disadvantage of the conductive plastic potentiometer is vulnerable to the effects of temperature and humidity resistance value, so the high precision is not easy to do.

(4) conductive glass glaze potentiometer

Conductive glass glaze potentiometer, also known as metal ceramic potentiometer, it is alloy, metal compounds, or refractory compounds as the conductive material, such as adhesive for glass glaze, made by the mixed sintering on the glass substrate. Good high temperature resistance of the conductive glass glaze potentiometer, good abrasion resistance, has a wide range of resistance, small temperature coefficient of resistance and moisture resistance is strong. Conductive glass glaze potentiometer disadvantage is that the change of contact resistance, noise big, not easy to ensure the high precision of measurement.

2, wire wound potentiometer displacement sensor

Wire-wound potentiometer resistor body consists of resistance wire winding on the insulation, many different kinds of resistance wire, resistance wire material is according to the structure of the potentiometer, hold the space of the resistance wire, resistance and temperature coefficient to choose. The resistance wire is fine, in a given space, the resistance value become larger and resolution. But the resistance wire is too thin, in use process is easy to disconnect, affect the service life of the sensor.

3, photoelectric displacement sensor potentiometer

Photoelectric potentiometer is a kind of non-contact potentiometer, it replace brush with light beam. Photoelectric potentiometer is mainly by the resistor body, photoconductive layer and a conductive electrode. The making process of the photoelectric potentiometer is first on the substrate a layer of cadmium sulfide deposit or cadmium selenide photoconductive layer, and then on the photoconductive layer deposition a resistance and a conductive electrode. Between the resistance and conductive electrode with a narrow gap. Light at ordinary times, the resistance between the body and the conductive electrode by the resistance being very high light conductance layer and show the insulation state. When beam on the resistance and conductive electrode gap, since light conductance layer parts by illuminate light resistance is small, make the resistor body parts by illuminate and conductive electrode conduction, then the output of the photoelectric potentiometer output voltage, output voltage and displacement of beam irradiation to the size of the position, so as to realize the displacement of the beams is converted into a voltage signal output. Photoelectric largest potentiometer is contact type, the advantages of no wear problems, it will not bring any harmful to the sensor system friction torque, so as to improve the accuracy, reliability and service life, the resolution of sensor. Photoelectric potentiometer disadvantage is that the contact resistance is big, poor linearity. Because of its high output impedance, need with high input impedance of the amplifier. Although photoelectric potentiometer has many shortcomings, but because of its advantages is unmatched by other potentiometer, so still been applied in many important occasions.