Unit 2 part 2transducers and sensors power

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1. Encoder uses

2. How does a capacitive encoder work? A capacitive encoder works by measuring the change in capacitance from the change in dimensions of the capacitor. A capacitive encoder uses the change in capacitance value of a capacitor as a means to measure displacement. Typically, the capacitive sensor’s principle elements are arranged so that the capacitance changes as a moving elements displace relative to the stationary plates of the capacitor.

3. Typically comprises of three main elements; a transmitter, conductive plates separated by a non-conductive material and a receiver board. Capacitance varies in proportion to the distance of the plates (d), as well as their overlap (A). Displacement can be measured axially (variation in d) or in the planar direction of the plate overlap (variation in A).

4. Structure model of the capacitive encoder

5. Capacitive vs Inductive sensors

6. Types of capacitor encoders Parallel Plate capacitor Composite capacitor Cylindrical capacitor Variation in capacitor Change in distance Change in common plate area Change in dielectric

7. Change in distance

8. Change in common Plate area

9. Change in dielectric