Angular or linear high precision capacitive position sensors

Abstract

Abstract The sensor is in the form of a compact integrated unit. In its basic version as a rotating sensor, it consists of a stator (1) with a series of electrodes (S1 to Sn) for creating a rotating field and a rotor (2) with a small number of electrodes (R1 to R3) having a different spacing between them. The latter electrodes pick up a voltage (SI) which is induced by the inter-electrode capacitive coupling and which depends on the angular displacement of the rotor (2). Circuits (7) integrate (12, 13) the induced voltage and determine the time corresponding to half the value at a reference time. In a preferred circular version, it amounts to two concentric sensors with one track forming a vernier, a second track enabling a rough absolute measurement to be made, and with a track to remove ambiguity by identifying the sector in which the capacitive coupling between the electrodes of the vernier and the electrodes of the stator occurs. The vernier is repeated sequentially and each sector is successively supplied with the same small set of polyphase voltages. <IMAGE>

Inventors

• 👤 Jean Girault

Bibliographic Details