A load cell (or loadcell) is a transducer which converts force into a measurable electrical output. Although there are many varieties of force sensors, strain gauge load cells are the most commonly used type.
The load cell is composed of base, load cell block, bolt, cable, etc. The load cell block is a load-bearing element, and the resistance strain gauge is pasted on the load cell block according to a certain process to form a Wheatstone bridge, which provides a stable and high-precision power supply from the outside. When the load cell block does not bear the load, the bridge is in a balanced state and the output voltage is zero. When the load cell block bears the load, due to the deformation of the load cell block, the internal resistance of the strain gauge changes, which makes the bridge lose balance, and the voltage signal is output. The magnitude of the signal output is proportional to the load on the load cell block.
The load cell is usually used with the weighing indicator. The weighing indicator provides precise power supply for the load cell. At the same time, the output signal of the load cell is amplified and actively filtered. After processing such as analog-to-digital conversion and photoelectric isolation, the weight value can be displayed directly through the indicator, and the digital signal output by the indicator can also be sent to the microcomputer for data processing.
According to the international organization of Legal Metrology (OIML), the error band δ of the load cell accounts for 70% of the error band δ of the weighing instrument, and the sum of the linear error, the lag error of the weighing load cell and the error caused by the influence of temperature on the sensitivity within the specified temperature range cannot exceed the error band δ. This allows the manufacturer to adjust the components that make up the total measurement error to achieve the desired accuracy.