Abstract: A magnetic disk apparatus includes a magnetic disk accommodated for rotation in a housing, a spindle mechanism for driving the magnetic disk to rotate, a magnetic head for writing and reading out information onto and from the magnetic disk, a suspension for supporting the magnetic head thereon, an actuator for driving the suspension in order to move the magnetic head in a radial direction of the magnetic disk, and a retraction mechanism for retracting the magnetic head to a particular area on the magnetic disk when the spindle mechanism is rendered inoperative. The magnetic disk apparatus further includes a mechanism provided at a location above the magnetic disk in an opposing relationship to the particular area of the magnetic disk for pressing at least one of the magnetic head and the suspension against the magnetic disk. In lieu of the pressing mechanism, a displacement restriction member may be provided.

Abstract: An acceleration sensor is provided which has a plurality of piezoelectric elements having polarization directions which are different from the direction of the acceleration to be detected and which have electrodes provided on both sides are mounted to a substrate, or a singly formed piezoelectric element having a plurality of polarizations with independent electrodes provided for each region is mounted to a substrate, a series electrical connection being made between the substrate side electrodes and the free end electrodes of the piezoelectric elements, the electrodes between which the piezoelectric element are series connected being led out to two electrodes provided on the substrate, and a weight being mounted over and such a manner as to straddle the plurality of piezoelectric elements or singly formed piezoelectric element. When an acceleration acts on this acceleration sensor, the force of inertia of the weight applies a stress to each piezoelectric element, causing the generation of a voltage.

Abstract: A storage device includes an MR element; write circuit responsive to input of binary storage data indicative of either a first state or a second state, and applying a write magnetic field in a first direction correspondingly to the first state, or applying the write magnetic field in a reverse second direction correspondingly to the second state; and read circuit for applying a bias magnetic field to the MR element and discriminating between the first and second states in accordance with the volume resistivity of the MR element.