PURPOSE: To effectively provide nonmagnetic films between magnetic films and a substrate so as to improve the reproduction output voltage at the time of measurement by forming the nonmagnetic films of a nonmagnetic material on the surface of the substrate and forming the magnetic films of a magnetic material which is capable of recording magnetic signals on the surfaces of the nonmagnetic films.
CONSTITUTION: Since porous nonmagnetic films 5 and 5 having a 5-10% porosity are provided between the surface of a turbine shaft 2 and magnetic films 3 and 3 in this sensor 1, the magnetic permeability of the films 5 and 5 can be effectively lowered at the time of reading magnetic signals with magnetic read heads 4 and 4 by preventing a magnetic flux from passing through the inside of the shaft 2 by means of the low magnetic permeability of the air contained in the pores in the films 5 and 5 and the reproduction output voltage of the films 3 and 3 can be improved.
KAWATO YASUSHI
KONDO JIRO
IWAKUNI HIDEJI
