PURPOSE: To obtain a magnetic disk storage device superior in reliability by suppressing variation in output timing of an index signal in an index signal detecting circuit in particular.
CONSTITUTION: A single pole part 7 of north pole or south pole is provided in a magnetic recording starting position on a turntable 2, and moreover, an opposite pole 8 to the single pole part 7 is provided in a part other than the single pole part 7 on the same circumference. By this method, a bias circuit is excluded, and variation in a power source voltage, variation of a resistance value and variation in the output timing of the index signal due to an environmental change are suppressed, and hence the magnetic disk storage device superior in reliability is obtained.
TAKENO SHOICHI
TODA AKIO
MATSUMURA TOSHIAKI
