Abstract: A self-sufficient electronic device to retract and park a voice coil actuator in a resistive parking position in,hard disk drives whose kinetic energy obtained from the rotating disk stack is not sufficient to be utilized as an energy source for the power-off retract and parking of the actuator. The invention uses electric energy stored in one or more capacitors to perform the necessary tasks. An initial electrical pulse is imposed on the actuator to propel the actuator towards a resistive parking ramp. In the event the actuator bounces off a crash stop barrier a bounce detector recognizes a polarity change of a reactive voice coil voltage and gives a signal for a secondary energy pulse to return the bouncing actuator to the resistive parking position. The simple logical concept of the device conserves space and energy making it suitable for miniature hard disk drives.

Abstract: A disk drive includes a read/write head mounted on an actuator, a disk having an inner diameter region and an outer diameter region, the head being radially movable by the actuator between the inner diameter region and the outer diameter region. An unload ramp is positioned at the outer diameter region. A controller outputs control signals upon sensing a power down condition. A feedback circuit is adapted to sense a back emf generated by the actuator and to use the back emf to apply a counter-acting voltage to the actuator that tends to bring the actuator to a stop. A switch is responsive to the control signals to (i) connect the feedback circuit to the actuator to enable the actuator to be brought to a stop while the disk continues to rotate and (ii) for then causing the actuator to move the head to the unload ramp. The switch further applies a voltage which causes the actuator to bring the head to the inner diameter region of the disk, before causing the actuator to move the head to the unload ramp.

Abstract: In a magnetic read/write assembly, the magnetoresistive (G)MR sensor element is protected against electrostatic discharge (ESD) and electrical overstress (EOS) by using a low resistance bypass. The low resistance bypass shunts current away from the magnetoresistive sensor element during an ESD or EOS event. This low resistance bypass is made up of two or more resistors connected in series, and positioned in parallel to the magnetoresistive sensor element. The use of electronic circuitry to temporarily disable this low resistance bypass allows the magnetoresistive sensor element to be tested during manufacturing. The low resistance bypass is removed prior to placing the (G)MR head into operation in the magnetic storage system or at any other desired step in the manufacturing process.

Abstract: Flying height Adjustment for Air Bearing Sliders An air bearing slider for sliding over a medium surface of a recording medium and having an air bearing surface facing the disk surface, a back surface perpendicular to the air bearing surface and a head at the back surface. During operation the head is maintained at a flying height above the disk surface with the aid of a flying height adjustment mechanism consisting of one or more ducts, each having an inlet at the air bearing surface and an outlet at the back surface. A valve mechanism controls an air flow through the duct or ducts by opening and closing the valve or valves together or independently. Alternatively, a deformable surface feature located on the back surface of the slider is used to alter the air flow to thus control the flying height. The mechanism of the invention allows one to achieve accurate flying height control in a range between 5 and 50 nm and between 0 nm and 15 nm as required for near-field or contact disk drives.

Abstract: A capacitor powered electronic emergency device retracts and parks an actuator into a resistive parking position with a crash stop barrier. Due to variations of the kinetic status of the actuator at the begin of the retraction, the actuator reaches the resistive parking position with different velocities, which can be at a level that causes the actuator to bounce off the crash stop barrier. A modulating pulsing of the energy flow extends the discharge time of the capacitor long enough to provide sufficient energy to compensate an eventual bounce-off. The use of transistors in the device keeps the internal energy consumption low. An increase of the pulsing frequency in dependence on the capacitor voltage results in a high average current flow.