Abstract: Embodiments of the invention improve utility of a magnetic disk drive in which a head is retracted if the magnetic disk drive is in a dropping state. In one embodiment, an HDC/MPU provided in a magnetic disk drive judges whether the magnetic disk drive is in a dropping state based on an output from an acceleration sensor which may detect an acceleration and performs a retraction operation of a head. After the HDC/MPU judges that a drop is occurring, the HDC/MPU detects whether the drop judgment is incorrect according to whether a shock sensor detects a shock occurrence and changes the drop judgment condition based on a detection history of detected incorrect judgments.

Abstract: Embodiments of the invention prevent the magnetic head from dropping to the magnetic disk when it is retracted. If the power supply Vcc to the drive is interrupted, a power supply voltage detecting section detects that the power supply to the drive is interrupted. A control section sets switches to the ON state in order to discharge the charged retract capacitor and supply the discharge current to a voice coil. The control section retains the switches in the ON state for a period which is determined based on the discharge period specifying control data stored in a register and the count signal from a counter. A voice coil motor, to which the current is supplied, turns the actuator in the unloading direction to retract the actuator to the ramp.

Abstract: Embodiments of the invention prevent the magnetic head from dropping to the magnetic disk when it is retracted. If the power supply Vcc to the drive is interrupted, a power supply voltage detecting section detects that the power supply to the drive is interrupted. A control section sets switches to the ON state in order to discharge the charged retract capacitor and supply the discharge current to a voice coil. The control section retains the switches in the ON state for a period which is determined based on the discharge period specifying control data stored in a register and the count signal from a counter. A voice coil motor, to which the current is supplied, turns the actuator in the unloading direction to retract the actuator to the ramp.

Abstract: A hard disk drive has an enclosure with disk construction members and is characterized by covering the enclosure with an electrically conductive sheet. The electrically conductive sheet protects the drive regardless of which direction an ESD charge is applied. The electrically conductive sheet does not permit ESD to pass through the disk construction members stored in the enclosure. Therefore, it is possible to form a structure in which a GMR head or the like in an enclosure is not damaged due to ESD even if the enclosure is handled by a general end user. Moreover, the present invention relates to an electrically conductive sheet for covering at least both principal planes of the enclosure of a hard disk drive constituted as described above. Other modes of the invention include at least both principal planes of an enclosure being covered by the electrically conductive sheet in such a way that both sheets on both principal planes are electrically connected.

Abstract: An improved process for producing an aqueous polymer emulsion is provided wherein a radically polymerizable unsaturated monomer is polymerized in an aqueous medium in the presence of a water-soluble copolymer. The water-soluble copolymer is derived from a combination of (a) a nitrogen-containing ethylenically unsaturated compound with (b-1) an unsaturated carboxylic acid or its salt and/or (b-2) an ethylenically unsaturated sulfonic acid or its salt.