What are the types of weighing sensors? What is the basis of the selection?
Date：2023-06-08
Weighing sensors-sometimes called "force", "weighing" or "weight" sensors that can convert the load acting on it into a measurable output signal. The size of the output signal is proportional to the applied force or load. What are the types of weighing sensors? What is the basis of the selection? This article has collected some information, hoping to have a larger reference to the readers.
There are mainly six types of weighing sensors, namely, photoelectric type, hydraulic type, capacitive type, electromagnetic force type, magnetic pole variable form and plate ring type.
1. Photoelectric type
Photoelectric weighing sensor is divided into two types: grating type and code disk type.
(1) Raster-type sensor
Using the Moore stripe formed by the grating to convert the angular displacement into photoelectric signals. There are two gratings, one is a fixed grating, the other is a moving grating installed on the dial axis. The measured object added to the load-bearing table rotates the dial shaft through the force transfer lever system, driving the moving grating rotation, and causing the Moore stripe to move accordingly. Using the phototube, conversion circuit and display instrument, you can calculate the number of moved Moore stripes, measure the size of the grating rotation angle, so as to determine and read the quality of the measured object.
(2) Code disk sensor
The code plate (symbol board) is a transparent glass mounted on the shaft of the dial, with a black and white code compiled by a certain coding method. When the measured object added to the bearing stage rotates the watchplate shaft through the force transfer lever, the code plate then turns to a certain Angle. The optical cell will receive the optical signal through the code disk and convert it into an electrical signal, which is digitally processed by the circuit, and finally displays the number representing the measured quality on the display. Photoelectric sensors used to be mainly used on electromechanical binding scales.
2. Hydraulic type
Under the action of the measured gravity P, the pressure of the hydraulic oil increases, and the degree of the increase is proportional to P. The measurement of the mass of the measured object. The hydraulic type sensor structure is simple and firm, the measurement range is large, but the accuracy is generally not more than 1 / 100.
3. Capacitor type
The capacitive weighing sensor works using the positive proportion of the oscillation frequency f of the capacitor oscillation circuit and the plate spacing d. There are two plates, one is fixed and the other is movable. When the load-bearing platform loads the measured object, the plate spring bends, the distance between the two plates changes, and the oscillation frequency of the circuit also changes accordingly. With the change of the frequency measured, the mass of the measured object on the load-bearing table can be found. Capacitor sensor has less power consumption, low cost, and its accuracy is 1 / 200~1 / 500.
4. Electromagnetic force
The electromagnetic force type weighing sensor works on the principle of balancing the load with the electromagnetic force. When the measured object is placed on the bearing table, one end of the lever leans upward; the photoelectric device detects the inclination signal and enlarges into the coil to generate electromagnetic force to restore the lever to balance. The quality of the measured object can be determined by the digital conversion of the current generating the electromagnetic balance force. The electromagnetic force sensor has a high accuracy, up to 1 / 2000~1 / 60000, but the weighing range is only between a few dozens of milligrams to 10 kg.
5, the magnetic pole variable form
When the ferromagnetic element is mechanically deformed under the action of gravity of the measured object, the internal stress produces and causes the conductivity to change, so that the induced voltage of the secondary coil on both sides of the ferromagnetic element (magnetic pole) also follows
There are mainly six types of weighing sensors, namely, photoelectric type, hydraulic type, capacitive type, electromagnetic force type, magnetic pole variable form and plate ring type.
1. Photoelectric type
Photoelectric weighing sensor is divided into two types: grating type and code disk type.
(1) Raster-type sensor
Using the Moore stripe formed by the grating to convert the angular displacement into photoelectric signals. There are two gratings, one is a fixed grating, the other is a moving grating installed on the dial axis. The measured object added to the load-bearing table rotates the dial shaft through the force transfer lever system, driving the moving grating rotation, and causing the Moore stripe to move accordingly. Using the phototube, conversion circuit and display instrument, you can calculate the number of moved Moore stripes, measure the size of the grating rotation angle, so as to determine and read the quality of the measured object.
(2) Code disk sensor
The code plate (symbol board) is a transparent glass mounted on the shaft of the dial, with a black and white code compiled by a certain coding method. When the measured object added to the bearing stage rotates the watchplate shaft through the force transfer lever, the code plate then turns to a certain Angle. The optical cell will receive the optical signal through the code disk and convert it into an electrical signal, which is digitally processed by the circuit, and finally displays the number representing the measured quality on the display. Photoelectric sensors used to be mainly used on electromechanical binding scales.
2. Hydraulic type
Under the action of the measured gravity P, the pressure of the hydraulic oil increases, and the degree of the increase is proportional to P. The measurement of the mass of the measured object. The hydraulic type sensor structure is simple and firm, the measurement range is large, but the accuracy is generally not more than 1 / 100.
3. Capacitor type
The capacitive weighing sensor works using the positive proportion of the oscillation frequency f of the capacitor oscillation circuit and the plate spacing d. There are two plates, one is fixed and the other is movable. When the load-bearing platform loads the measured object, the plate spring bends, the distance between the two plates changes, and the oscillation frequency of the circuit also changes accordingly. With the change of the frequency measured, the mass of the measured object on the load-bearing table can be found. Capacitor sensor has less power consumption, low cost, and its accuracy is 1 / 200~1 / 500.
4. Electromagnetic force
The electromagnetic force type weighing sensor works on the principle of balancing the load with the electromagnetic force. When the measured object is placed on the bearing table, one end of the lever leans upward; the photoelectric device detects the inclination signal and enlarges into the coil to generate electromagnetic force to restore the lever to balance. The quality of the measured object can be determined by the digital conversion of the current generating the electromagnetic balance force. The electromagnetic force sensor has a high accuracy, up to 1 / 2000~1 / 60000, but the weighing range is only between a few dozens of milligrams to 10 kg.
5, the magnetic pole variable form
When the ferromagnetic element is mechanically deformed under the action of gravity of the measured object, the internal stress produces and causes the conductivity to change, so that the induced voltage of the secondary coil on both sides of the ferromagnetic element (magnetic pole) also follows