Capacitance Thickness Gauge / Displacement Gauge Frequently Asked Questions

The capacitive thickness gauge and displacement measurement system measures the capacitance between the sensor and the object being measured to calculate the distance.

Capacitance refers to the ability to store charge between insulated conductors. The VE series gap detector, which is a capacitive displacement sensor, has a structure similar to that of a capacitor.

The diagram below illustrates a sensor and a measurement target. The sensor and the measurement target are electrically connected and positioned facing each other. This creates capacitance between the sensor and the measurement target, which can be expressed by the formula in the right diagram. In this formula, the permittivity of air (ε) and the electrode area of the sensor (S) remain constant. On the other hand, it is clear that when the distance (D) between the sensor and the measurement target changes, the capacitance (C) also changes. Therefore, by measuring the capacitance (C), one can determine the distance (D) between the sensor and the measurement target.

Using this principle, the capacitive displacement sensor measures the distance between the sensor and the object being measured. Since measuring capacitance requires an electric current, it is necessary for the sensor, the object being measured, and the measuring instrument to be electrically connected. If this is neglected or if the connections are not secure, it can result in noise, unstable measurements, and increased measurement errors, so please remember to ensure proper continuity.