Capacitor displacement sensor works - News - Global IC Trade Starts Here Free Products

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Capacitive sensors are widely used in precision measurement systems, especially when detecting small displacements. One common method involves using a capacitor as a sensitive element, where mechanical displacement is converted into a change in capacitance. The capacitance of a parallel plate capacitor depends on the area of the plates and the distance between them. By designing a sensor with a fixed and a movable plate, changes in the overlapping area can be used to measure displacement accurately.

The capacitive grid displacement sensor operates on the same principle but uses a grid-like electrode structure instead of simple parallel plates. This design effectively combines multiple variable-area capacitors in parallel, enhancing sensitivity and resolution. As shown in Figure 2.2.1, the stationary plate consists of several equally spaced gates, while the moving plate has matching grid patterns. When the moving plate shifts relative to the fixed one, the effective capacitance changes, which can be converted into an electrical signal through a circuit for further processing.

A practical example of this technology is found in electronic digital scales used in physics experiments. These scales often use a multi-stage chip-type capacitive grid sensor, as illustrated in Figure 2.2.2. The moving ruler contains multiple sets of grids that are connected in parallel, allowing for higher accuracy and reducing the need for extremely precise manufacturing. During operation, the moving plate forms differential capacitors with small electrodes. As the ruler moves, the capacitance undergoes periodic changes, generating pulse signals that are amplified, processed by the chip, and finally displayed as a displacement value.