Patent ID: 6801113
Filing Date: 2004-10-05
Classification: H01F,H03K

Abstract:
A proximity sensor comprising:a detection coil; a detection circuit including an oscillation circuit having the detection coil as a resonance circuit element; a coil spool including a hollow cylindrical wire-winding drum around which a lead wire of the detection coil is wound, a detection-side flange provided on a detection side end of the wire-winding drum, and a circuit side flange provided on the detection circuit side end of the wire-winding drum; a core, made of a magnetic member, including a shaft inserted into the wire-winding drum of the coil spool, and a plate-shaped base located between the coil spool and the detection circuit; a cylindrical coil case housing the coil spool and the core and having a bottom on the detection side end; and a main body case, fitted to the coil case, for housing the detection circuit, wherein the wire-winding drum of the coil spool includes protrusions that protrude toward the center from not less than three points distributed in the range exceeding a semi-circle on the circumference of the wire-winding drum and that are elastically brought into contact with a shaft of the core, respectively, thereby coaxially positioning the coil spool and the shaft of the core.