Abstract: A power source control circuit prevents a generation of a spark between a magnetic head and a magnetic disk by accurately controlling an electric potential provided to the magnetic head. A signal processing circuit provides to the magnetic head an intermediate electric potential between a positive source voltage and a negative source voltage supplied by a power source unit. A first circuit provides the positive and negative source voltages to the signal processing circuit. A second circuit controls one of the positive and negative source voltages in response to a reference voltage fed back from the signal processing circuit. The reference voltage is provided from the signal processing circuit to the magnetic head for setting the head at the intermediate electric potential.

Abstract: An apparatus and a method of reproducing a synchronization signal in a disc storage system. The apparatus includes disc mechanism having a plurality of information storage discs in one of which a predetermined servo pattern is recorded, and a corresponding plurality of reproducing heads, one of the heads reading the servo pattern from the corresponding disc to thereby output a servo signal, a synchronization signal demodulating unit, responsive to the servo signal from the disc mechanism, for demodulating a synchronization signal in synchronization with a rotation of the discs, a synchronization clock generating unit for generating a clock signal with a predetermined frequency in synchronization with the synchronization signal, and a gate unit. For a predetermined period, the gate unit prohibits a supply of the synchronization signal from the synchronization signal demodulating unit to the synchronization clock generating unit.

Abstract: A method of positioning a magnetic head on a target cylinder of a magnetic disk uses a position signal derived from a servo signal which is read from a magnetic disk using a magnetic head. The servo signal includes at least first and second servo signal components on even cylinders of the magnetic disk and includes at least third and fourth servo signal components on odd cylinders of the magnetic disk. The position signal is used for moving the magnetic head to a desired cylinder.

Abstract: A servo circuit for a magnetic disk apparatus includes a target speed generating circuit which generates a target speed in accordance with an amount of movement. A speed signal producing circuit produces a real speed from a position signal from a servo object. A speed error generating circuit controls the speed of the servo object based on an error between the target speed and the real speed. Acceleration and deceleration control are performed to position the servo object at the target position. An acceleration detection circuit detects acceleration and outputs an acceleration-in-progress detection signal for changing a cut-off frequency of the speed error generating circuit between acceleration and deceleration. The servo circuit has a servo loop which supplies a seek current based on an error signal between a target speed and real speed to a voice coil motor and performs speed control on a head carriage.

Abstract: A control system for a servo circuit has a speed control unit for controlling the speed of a servo object, a position control unit for controlling the position of the servo object, a switching unit for switching between the speed control unit and the position control unit, a main control unit, and optionally a speed zero detection circuit which compares the real speed and a slice level and detects if the real speed is less than a fixed value. The control system includes a method for producing a target speed using an amount of movement X in an amount of movement d as a remaining amount of movement, and producing a target speed of equal speed for a remaining amount of movement Y.

Abstract: A magnetic disk drive which releases adhesion between a magnetic head and a magnetic disk by radially moving the head before the disk begins to rotate. The head movement is accomplished by compressing an elastic stopper by driving a head actuator motor with drive current which flows at half of the voltage previously applied to a motor drive circuit. This is accomplished by grounding one terminal of the motor and forcing all of the motor drive transistors OFF except for one transistor in the motor drive circuit. This provides the benefit that smaller and cheaper transistors can be used and power consumption is considerably reduced, thus contributing to a smaller, cheaper drive circuit which consumes less power.