Abstract: A disk drive includes a disk having a recording surface and a write element for writing a sequence of symbols in a continuous-time signal on the recording surface. The disk drive includes a frequency generator for generating a plurality of primary phase write clock signals having a channel frequency fch. Each of the primary phase write clock signals has a selected primary phase shift from another one of the primary phase write clock signals. The disk drive includes a programmable phase synthesizer for generating a secondary phase write clock signal having the channel frequency fch and a selected secondary phase shift from one of the primary phase write clock signals. The programmable phase synthesizer includes programmable means for selecting two of the primary phase write clock signals and element for performing vector addition of the selected primary phase write clock signals to generate the secondary phase write clock signal.

Abstract: A magnetic recording apparatus has a magnetic head for writing data to a magnetic disk, a writing circuit for feeding a current to the magnetic head, a controller for controlling the operation of the writing circuit, and a temporary shutoff circuit for shutting off the current temporarily while the operation of the controller is in a transient period. The writing circuit has a first transistor, which is connected to the magnetic head. The temporary shutoff circuit has a second transistor so as to temporarily deactivate and thereafter activate the first transistor when electric power starts being supplied by pulling into the second transistor the transient current resulting from variation in the base voltage of the second transistor as a result of the parasitic capacitor present at the base of the second transistor being charged when electric power starts being supplied.

Abstract: The present invention provides a magnetic recording apparatus for recording/reproducing a data with a comparatively high density. The magnetic recording apparatus comprises: a magnetic recording medium having a data area and a spare area; a head for data write in the data area with a predetermined recording frequency; a head error detection circuit for detecting a head error during a data write; and a controller that operates as follows. When an error is detected by the head error detection circuit, a data write is carried out in the spare area and if this does not cause an error, it is decided that the head is normal.

Abstract: In a coding method which does not restrict a run length of “1” while data is recorded/reproduced, there are such a drawback that when an error correction is carried out, a total number of error data to be corrected is increased, and also errors of not-detectable data are increased. While data is coded, a continuous number of “1” contained in a code word is limited, and then an error correction is carried out inside a coding/decoding process operation. Thus, a recording/reproducing apparatus having a small number of decoding errors is available.

Abstract: A magnetic disk unit includes slider suspension assemblies, each of the assemblies having a slider with at least one magnetic head element and a suspension with one end portion and one surface, the slider being mounted on the one surface of the suspension at the one end portion, magnetic disks, each of the disks having at least one surface which opposes to the slider of the assembly, head IC chips electrically connected to the magnetic head elements, and a control circuit electrically connected with the head IC chips. The control circuit controls operations of each of the magnetic head elements so that the write current is applied to the magnetic head element for a first predetermined period of time and then the application of the write current to the magnetic head element is stopped for a second predetermined period of time which is equal to or longer than the first predetermined period.

Abstract: The present invention is a magnetic signal reproducing device for reproducing information from a magnetic recording medium in which a polarity of magnetization is inverted at a first temperature during temperature change. The device includes local temperature raising device for locally raising the temperature of the magnetic recording medium, and reproducing device for magnetically detecting information recorded on the magnetic recording medium. In the device, during a reproducing operation, the local temperature raising device forms an area having a lower temperature than the first temperature and an area having a higher temperature than the first temperature within an area in the magnetic recording medium, thereby reducing contribution to reproduced signal from magnetization of an area other than a reproduction target area.

Abstract: In accordance with the present invention, a magneto-resistive head read amplifier circuit is provided which can be incorporated into a magnetic reader for reading information stored in magnetic form on a storage medium. The magneto-resistive head read amplifier of the present invention incorporates an inductor in the bottom current drain of the head read amplifier circuit which reduces or eliminates noise generated by the bottom current source transistor of the head read amplifier circuit. In accordance with a first embodiment of the present invention, the magneto-resistive head read amplifier is a single-polarity head read amplifier circuit which utilizes a bias current having a particular polarity. In accordance with a second embodiment of the present invention, the magneto-resistive head read amplifier is a dual-polarity head read amplifier circuit capable of operating with bias currents of opposite polarity.

Abstract: A magnetic recording circuit includes a write driver output stage, a magnetic write head and an interconnect circuit. The write driver output stage has an output and an output impedance. The magnetic write head has an input and an input impedance. The interconnect circuit has an input, an output and a selected characteristic impedance Z0. The input of the interconnect circuit is coupled to the output of the write driver output stage, the output of the interconnect circuit is coupled to the input of the write head. The interconnect circuit can be one of, or both, source-terminated so that the output impedance of the write driver output stage is substantially equal to the selected characteristic impedance Z0 of the interconnect circuit, and load-terminated so that the input impedance of the write head is substantially equal to the characteristic impedance Z0 of the interconnect circuit.

Abstract: The hard disk testing and certifying device of the present invention includes a spin stand to rotate a disk to be tested. A single read/write head, including both a write head and a read head is mounted upon an armature which movably supports the read/write head. The device includes a computerized control system and signal processing system that provides write signals to the write head and receives and processes read head signals from the read head. In the preferred embodiment the read/write head simultaneously provides write signals to the disk and receives read signals from the disk. Preferably, the read/write head functions continually and the certification testing is conducted utilizing a spiral path. In the preferred read/write head the read head is disposed behind the write head and an electromagnetic field shield is disposed between them to reduce electromagnetic field interference between the write head and the read head during simultaneous operation.

Abstract: A magnetic recording and reproducing apparatus has a recording magnetic head and a reproducing magnetic head disposed on a rotary cylinder, and a magnetic head clogging detecting unit for detecting clogging of the recording magnetic head by monitoring the output of the reproducing magnetic head. In this magnetic recording and reproducing apparatus, for saving power consumption, magnetic head clogging is detected intermittently only in predetermined periods, and in other periods the operation of the head clogging detecting unit is stopped. As a method of stopping the operation of the magnetic head clogging detecting unit, the power supply of the magnetic head clogging detecting unit is turned off. The width and interval of detection periods and detection sensitivity of magnetic head clogging detection can be freely set by the user.

Abstract: A method and apparatus detects and filters pulse asymmetries in a read signal of a data storage device. A value indicative of the difference between the shape of a pulse from its first zero crossing to its peak and the shape of the pulse from its second zero crossing to its peak is determined. This value is minimized by adjusting at least one filter characteristic of a read signal filter.

Abstract: A highly reliable, low overhead method for determining a position of a magnetic storage medium that is divided into a plurality of servo sections is provided. The inventive method includes defining a predetermined bit pattern that corresponds to a known position of the magnetic storage medium. A positional index bit is associated with each servo section such that a known bit of the predetermined bit pattern is associated with the known position of the magnetic storage medium. A current positional index bit is read from the magnetic storage medium and a positional bit sequence comprising the current positional index bit is formed. The positional bit sequence is compared with the predetermined bit pattern and, based on the comparison, whether the position of the magnetic medium is the known position can be determined.

Abstract: A recording medium cartridge includes a memory circuit for storing information concerning signals recorded on the recording medium within the cartridge. The information is stored in the memory circuit in the form of a hierarchic data structure which includes a plurality of data packets having a predetermined form and length. Each data packet includes a code indicative of a level in the data structure to which the data packet belongs. At least some of the data packets include data indicative of starting and ending positions on the recording medium of recorded signals which the data packet represents. The hierarchic (or “tree”) data structure facilitates rapid retrieval and reproduction of the signals recorded on the recording medium, particularly when the recording medium is a magnetic tape. The tree structure also facilitates storage of information in connection with recording of additional signals on the recording medium.

Abstract: A recording apparatus for recording an information signal on a magnetic record carrier includes a write driver circuit and a magnetic write head. The write driver circuit comprises a first voltage driver and a second voltage driver. A first current driver and a second current driver are present for driving the write head. The first and second voltage driver each include a respective series circuit of an npn transistor and a bidirectional impedance element coupled between a point of constant potential and the respective outputs of the first and second voltage drivers.

Abstract: A method and system are disclosed for controlling the application of a reset voltage pulse to a GMR sensor in a direct-access storage device (DASD), such that existing data is not damaged or altered. Each sensor is positioned or parked at a location reserved for reset pulse application, where no valid data is stored. A complex interrelated set of commands is then initiated, and upon completion of the entire set of interrelated commands, a reset pulse is applied to the GMR sensor. Any variation or interruption in the complex interrelated set of commands will result in a disarming of the reset pulse circuitry, effectively preventing an accidental or inadvertent application of the GMR reset pulse. Alternately, a group of GMR sensors each may be tracked to a reserve track, forming a reserve cylinder. Servo marks on the reserve track are sensed by a selected sensor and utilized to ensure no valid data is present.

Abstract: The invention provides a high-speed interface that transfers user data and other data over a single unified interface between a read channel integrated circuit and another integrated circuit, such as the drive control integrated circuit. The high-speed interface eliminates the need for analog pins on the integrated circuits to lower the cost of the system. The high-speed interface also eliminates the use of the serial interface to transfer the servo position data and other data which speeds up the data transfer. Examples of the other data include read channel settings, read channel performance data, and servo data. A read channel integrated circuit exchanges the user data with a data bus when the disk drive system is reading or writing the user data. The read channel integrated circuit exchanges the other data with the data bus when the disk drive system is reading servo data. The other integrated circuit exchanges the user data with the data bus when the disk drive system is reading or writing the user data.

Abstract: A highly reliable, low overhead method for determining a rotational position of a magnetic storage medium that is divided into a plurality of servo sections is provided. The inventive method includes defining a predetermined bit pattern that corresponds to a known position of the magnetic storage medium. A rotational position indicator bit is associated with each servo sector such that a known bit of the predetermined bit pattern is associated with the known position of the magnetic storage medium. A current rotational position indicator bit is read from the magnetic storage medium and a rotational position bit sequence comprising the current rotational position indicator bit is formed. The rotational position bit sequence is compared with the predetermined bit pattern and, based on the comparison, whether the rotational position of the magnetic medium is the known rotational position can be determined.

Abstract: A disk storage device includes a data transfer control device for transferring data from a higher rank device to a storage medium and transferring data from the storage medium to the higher rank device, an identification device having identification information for determining whether it should be permitted or inhibited to write data into a predetermined recording area of the storage medium, and a data transfer command device, responsive to a data recording command given by the higher rank device, to order the data transfer control device to write data into the storage medium according to the identification information of the identification device. In response to a data write command given to the storage medium by the higher rank device, the data transfer command device collates a state of the data write command with the identification information possessed by a predetermined sector of the storage medium.

Abstract: A disk drive recording apparatus includes an actuator arm with first and second heads extending from the actuator arm for writing and reading data to and from a first surface of a disk recording medium. The first and second heads are spaced apart from each other in a circumferential direction along the first surface of the disk recording medium. A switching device switches a data input/output path between the first head and the second head in response to a control signal. A microprocessor identifies a target position on the first surface of the disk recording medium and determines which one of the first and second heads is closer to the target position. The microprocessor then generates the control signal to switch the data input/output path to the first head when the first head is closer to the target position, and generates the control signal to switch the data input/output path to the second head when the second head is closer to the target position.

Abstract: A combined read and write VCO for data channels is disclosed. The combined read and write VCO for data channels shares a common loop capacitor while providing optimal read and write VCO loop responses, and allows the VCO to relock to the write timebase after a read very quickly while maintaining an accurate timebase. The combined read and write VCO includes an oscillator providing an output signal having a frequency that varies proportionately to an oscillator input signal and an adjustable voltage source, the adjustable voltage source having a first configuration for a write mode and a second configuration for a read mode, and the adjustable voltage source providing the oscillator input signal to the oscillator in response to receiving an input current signal. The adjustable voltage source includes a first and second capacitor coupled in series and a switch coupled across the second capacitor, the switch being open to provide the first configuration and closed to provide the second configuration.