Load cell requirements for capacitance and electric field

First, the capacity of the load cell is more susceptible to the geometrical size of the electrode, so it can't be made very large. Therefore, the output impedance of the load cell is relatively high, which leads to the poor load capacity of the load cell, which is susceptible to external interference and unstable phenomena, and even causes the load cell to fail to work normally.

Second, the output characteristics of the load cell are nonlinear. Although the differential method is used to improve the design, it cannot be completely eliminated. Moreover, the output is only when the edge effect of the electric field is ignored. Can be linear. Because the edge effect will produce additional capacitance, the capacitor of the sensor will be directly superimposed, resulting in a nonlinear output characteristic.

Third, the initial capacitance of the load cell is very small, but the capacitance of the lead wire connecting the sensor and the electronic circuit, the stray capacitance of the electronic circuit, and the capacitance formed by the inner plate of the sensor and the surrounding conductors are relatively large. , Not only the sensitivity of the sensor is reduced, but also these capacitances often change randomly, making the work of the instrument extremely unstable, thereby affecting the accuracy of the measurement.

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