With the development of the times, traditional electronic weighing instruments have become less and less satisfied with the needs of social development, which has promoted the development of electronic weighing instruments to a certain extent. The progress of its load cell technology is the main driving force for its development. The principles of the technology are based on a certain scientific basis, but most of them have advantages and disadvantages. This requires the market to measure it. People’s first choice. Let’s talk about the types and types of common load cells below.
1 Resistance strain gauge sensor
The resistance strain gauge is tightly bonded to the substrate through a special adhesive. When the substrate is deformed by the force, the strain gauge deforms at the same time, so that the resistance value of the strain gauge changes, and the resistance change is converted through the Wheatstone bridge. It is an electrical signal, thus completing the process of changing the external force into an electrical signal.
2 Electromagnetic force balance sensor
The weighing process of the electromagnetic force balance sensor is based on the ampere force. Add a weighing pan to the wire, the gravity of the weighing pan and the wire itself is downward, and the energized wire is subjected to upward electromagnetic force. When the current value through the wire reaches a certain value, the two forces balance each other. The sensor is in equilibrium.
3 Capacitive sensor
Capacitive sensor is a kind of sensor that converts the measured mechanical quantity, such as pressure, displacement, etc. into capacitance change. The sensitive component capacitor usually consists of two parallel electrodes filled with air between the poles.
4 Electric sensor
Photoelectric sensors include two types: grating type and code disc type. The working principle of the grating sensor is to convert the angular displacement of the moiré fringe formed by the grating into a photoelectric signal; the photocell receives the light signal through the code disc and converts it into an electrical signal, which is processed by the circuit and the measurement result is obtained.
5 Hydraulic sensor
The hydraulic sensor uses hydraulic oil pressure to be proportional to the weight (mass) of the measured object. As long as the increase in hydraulic oil pressure is measured, the quality of the measured object can be obtained.
6 Magnetic pole change form sensor
When the ferromagnetic element of the magnetic pole deformation sensor is mechanically deformed under the action of the gravity of the measured object, internal stress is generated and the permeability changes, so that the induced voltage of the secondary coil wound on both sides of the ferromagnetic element (magnetic pole) also follows The change. By measuring the change in voltage, the force applied to the magnetic pole can be obtained, and then the quality of the measured object can be determined.
7 Moving sensor
After the elastic element is stressed, its natural vibration frequency is proportional to the square root of the force. By measuring the change of the natural frequency, the force of the measured object acting on the elastic element can be obtained, and then its mass can be obtained.
8-fiber grating sensor
The sensing process of the fiber grating sensor is to obtain sensing information through the modulation of the fiber Bragg wavelength by external physical parameters, and it is a wavelength modulation type fiber sensor.
The above several types of load cells have their advantages and disadvantages, and the market also uses their actual value performance as a measurement standard. Among them, the electromagnetic force balance and resistance strain gauge type sensors are relatively mature, and then they are widely used; photoelectric and magnetic pole change types of sensors are not suitable for social development; vibration and spiral sensors are more accurate in value, but more expensive in price. Expensive; compared to hydraulic sensors, capacitive sensors have more applications. In real life, because the first two sensors have great advantages in terms of interference, etc., they are also frequently used weighing instruments, but fiber grating sensors also have a lot of room for development.