Inductive Proximity Sensor with Novel Structure of Ferrite Core
Inductive proximity sensors (proximity sensors) are noncontact sensing devices used to detect the approach of a target by an increase in coil impedance due to eddy current loss. Extending the operating distance of these sensors is demanded. The flux of a conventional proximity sensor has difficulty in reaching the target because of the presence of the center magnetic pole of ferrite core. Therefore, in this paper, we examine a proximity sensor using a novel structure of ferrite core without the center magnetic pole. In this novel structure, flux easily reaches the target because of the absence of the center magnetic pole. In addition, it is possible to reduce AC resistance due to the proximity effect for the use of a magnetoplated wire. As a result, the operating distance for the novel structure is 1.3-fold that for the conventional structure.
A.G. Mamalis, M. Enokizono and A. Kladas
T. Mizuno et al., "Inductive Proximity Sensor with Novel Structure of Ferrite Core", Materials Science Forum, Vol. 670, pp. 142-150, 2011