A load cell is a force-to-electricity conversion device that can convert gravity into an electrical signal, and is a key component of an electronic weighing instrument. There are many kinds of sensors that can realize force-to-electricity conversion, and the common ones are resistance strain type, electromagnetic force type and capacitive type. The electromagnetic force type is mainly used for electronic balances, the capacitive type is used for some electronic crane scales, and the vast majority of weighing instruments use resistance strain type load cells. The resistance strain type load cell has a simple structure, high accuracy, wide application range, and can be used in a relatively poor environment. Therefore, resistance strain load cells have been widely used in weighing instruments.
The resistance strain type load cell is mainly composed of an elastic body, a resistance strain gauge and a compensation circuit. The elastic body is the force-bearing element of the load cell, which is made of high-quality alloy steel or high-quality aluminum profile. The resistance strain gauge is made of metal foil corroded into a grid shape, and four resistance strain gauges are glued to the elastic body in the form of a bridge structure. In the absence of force, the resistance values of the four resistors of the bridge are equal, the bridge is in a balanced state, and the output is zero. When the elastic body is deformed by force, the resistance strain gauge also deforms along with it. During the bending process of the elastic body, two strain gauges are stretched, the wire becomes longer, and the resistance value increases; the other two strain gauges are compressed, and the resistance value decreases. This will cause the original balanced bridge to become unbalanced, and a voltage difference will be generated at both ends of the bridge. This voltage difference is proportional to the force on the elastic body. By detecting this voltage difference, you can get the gravity of the sensor. This After the voltage signal is detected and calculated by the instrument, the corresponding weight value can be obtained.
(1) High reliability, strong anti-interference ability, and good lightning protection performance.
(2) Various protection circuits and lightning protection designs have been added to eliminate the surge interference from the power supply and lightning, making the signal of the digital weighing sensor stable and ensuring the normal operation of the sensor.
(3) Work without interruption.
(4) Exempt from calibration.
(5) There is a separate password.
Essentially, the difference between analog and digital load cells is how the signal is processed. Digital load cell systems differ from analog systems in three important ways: signal strength, signal content, and data sampling rate.
(1) Signal strength
In a digital load cell, the signal from a strain gauge (a device used to measure strain on an object) begins with an analog voltage. A microprocessor inside the load cell immediately converts them to digital signals. These digital signals typically use 2 to 6 volts for their signal range, which is less susceptible to fluctuations than the 0.03 volt range in analog units. In other words, digital signals are stronger.
(2) Signal content
Analog systems rely on voltage from load cells to determine weight readings. Instead, digital systems transmit data from each load cell. Signals consist of binary information (values of zero and one) used by computers. Because binary data is less susceptible to interference from radio frequency, electromagnetic, temperature, and other hazards, binary data streams are more stable and less prone to weighing errors.
(3) Data sampling rate
Data rate measures how quickly the load cell sends weight information. Analog load cells provide continuous weight information in real time. Digital load cells send weight information in bits, many times per second.
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