Abstract: The present application discloses an electronic switching device in combination with a low noise, low input impedance preamplifier circuit. The resulting electronic preamp assembly is specifically configured so that it can be directly interchanged with existing mechanical relay/preamplifier assemblies such as those presently in use in recorder/reproducer apparatus having dual function record/playback heads, without disturbing the associated operating parameters of the record or playback channels. The electronic preamp assembly includes a balun transformer and a solid state switch coupled from a record amplifier to the record/playback head via a rotary transformer to define the record channel. The playback channel includes a diode bridge switch and a preamp circuit also coupled to the rotary transformer and head.

Abstract: A disk drive and a control method for the disk drive to reduce the number of unnecessary write inhibition operations. A microprocessor unit (MPU) 6 sets an allowable value Cv for the velocity of a magnetic head 1 to V0 until the head passes over N1 sectors after completion of a seek operation, Cv to V1 until the head passes over N2 sectors after passage of N1 sectors, and Cv to V2 after passage of N2 sectors. (N1<N2 and V0<V1<V2) A hard-disk controller (HDC) 10 detects the velocity of the magnetic head 1, based on a position error signal PES from a servo sector regeneration section 8a, and prohibits the write operation of the magnetic head 1 if the velocity exceeds Cv.

Abstract: A recording-medium mis-recording preventing mechanism for preventing recording from being made by mistake on a recording medium loaded in a recording unit, comprises: a push switch for detecting whether the recording medium is recordable or not; and an arm portion. The arm portion includes: a first arm member pivoted on the recording unit and having a detection portion for abutting against a judgement claw provided on the recording medium so as to be removable by bending; a second arm member for pushing the push switch; a thin plate portion for connecting the first arm member and the second arm member; a spring provided between the first arm member and the second arm member for urging the second arm member in the direction to push the push switch; and a plate spring portion provided on the first arm member for making the arm portion return to a position in which the arm portion is to be positioned when no recording medium is loaded.

Abstract: An apparatus for reproducing an information signal from a record carrier includes at least one read head (6,8) for reading the information signal from a track on the record carrier (4). Further, an A/D converter (12,34) is available for A/D converting the information signal read from the record carrier with a specific clock frequency (f.sub.s) in response to a first control signal (cs1). A bit detector unit (24) is provided having an input coupled to the A/D converter for retrieving a sequence of bits from the signal applied to its input, with a specific bit frequency (f.sub.b). A generator unit, for deriving the first control signal, as well as a generator for deriving the specific bit frequency, is available. The generator unit for deriving the first control signal includes a coarse control signal generator (48,60) for deriving a coarse control signal so as to generate such specific clock frequency (f.sub.

Abstract: A technique for the formation of servo information and its servo control capable of enlarging a total available area for data regions by reducing a servo region for servo information in a hard disk drive is used in a disk drive recording apparatus having at least one disk having tracks provided thereon with a plurality of servo sectors for recording the servo information and a plurality of data sectors, the servo sector and the data sectors each being arranged in sequence in a track of the disk in an alternate manner, and a transducer for reading out data from the data sectors as well as writing data onto the data sectors. The technique includes dividing a series of servo information into a plurality of subsections of servo information, the servo information being usable for positioning the transducer on a selected data sector in a target track, and respectively recording the divided subsections of servo information onto the same number of servo sectors as the number of the plurality of subsections.

Abstract: A servo demodulator (20) is provided for generating a track identification signal (148) and a position error signal (150) from a servo wedge signal, such as a filtered servo wedge signal (112), in response to the processing of the servo wedge signal by a read channel (18). The servo demodulator (20) includes a servo clock generation circuit (90), a position error signal circuit (92), and a track identification circuit (76). The servo clock generation circuit (90) generates a synchronous servo clock signal (102) in response to receiving a servo reference clock signal (110) and the filtered servo wedge signal (112). The synchronous servo clock signal (102) is provided to the read channel (18) for use in processing the servo wedge signal. The position error signal circuit (92) generates the position error signal (150) in response to receiving the synchronous servo clock signal (102) from the servo clock generation circuit (90) and a synchronously sampled servo wedge signal (114) from the read channel (18).

Abstract: A magnetic disk reproducing apparatus for reproducing data recorded at an arbitrary position on a rotating disk by a head includes a level detecting unit for detecting a level of a DC component of a reproduced signal outputted from the head; a delaying unit for delaying the reproduced signal by a predetermined value; and a correcting unit for correcting the level of the DC component of the reproduced signal outputted from the delaying unit when the level of the DC component detected by the level detecting unit becomes larger than a predetermined threshold level. Preferably, a control method of a magnetic disk reproducing apparatus having such a construction includes the steps of detecting a level of a DC component of a reproduced signal outputted from the head; delaying the reproduced signal by a predetermined value; and correcting the level of the DC component of the delayed reproduced signal when the level of the DC component so detected becomes larger than a predetermined threshold level.

Abstract: A magnetic storage system capable of separating thermal signals from data signals is disclosed. The magnetic storage system includes a magnetic media and a head associated with the magnetic media. The head includes a magneto-resistive element which is biased by a modulated bias current. The modulated bias current modulates thermal signals to a first frequency and modulates data signals to at least a second frequency. A method of separating thermal signals from data signals read from a magnetic storage media is also disclosed. The method includes the steps of (1) providing a head for reading information from the magnetic storage media, the head having an MR element; and, (2) biasing the MR element with a modulated bias current.

Abstract: A device for copying programs installed on an original hard disk drive into duplicating hard disk drives is disclosed. The storage area of an original HDD is divided into a plurality of sub-storage areas corresponding to different HDD models so as to store initial programs corresponding to the different HDD models in respective sub-storage areas. Thereby, the above original initial programs corresponding to the different HDD models are copied into respective duplicating HDDs.

Abstract: A disc certification process, apparatus and article of manufacture for improved testing efficiency employs a testing head having a write element and a read element supported adjacent a rotating disc recording surface. The write element has a width that defines a "wide" write track width of at least N times the read track width defined by the width of the read element, wherein N is an integer greater than 1. The write element writes a signal onto the recording surface of the disc during a first disc rotation, to define a first annular write track having a "wide" first write track width in the radial direction of the disc. Then, during a second rotation, the read element reads the signal written in a first reading track width defined within the "wide" first write track. Thereafter, the read element is stepped to another read position adjacent the first write track and the read element reads the signal written onto the recording surface in a second reading track width defined within the first write track.

Abstract: A technique for determining a position of a read/write head relative to a magnetic disk includes the steps of providing the magnetic disk having a plurality of odd servo sectors and a plurality of even servo sectors, reading a first gray code pattern in an odd servo sector from the plurality of odd servo sectors on the magnetic disk, reading a second gray code pattern in an even servo sector from the plurality of even servo sectors on the magnetic disk, the even servo sector adjacent to the odd servo sector on the magnetic disk and determining the position of the read/write head only in response to the first gray code pattern and the second gray code pattern.

Abstract: A write condition setting method includes a measuring step for measuring at least one of a track per inch margin, an offset margin and an on-track accuracy margin with respect to a head for each of a plurality of temperatures prior to writing data on a track of a disk, and a setting step for variably setting at least one of a write current applied to the head and an off-track slice as a write condition for each of the plurality of temperatures based on a parameter which is dependent upon temperature so that the at least one of the track per inch margin, the offset margin and the on-track accuracy margin becomes a maximum.

Abstract: When an information signal recorded in a magnetic card is updated by an information recording and updating apparatus, a spectrum spread signal corresponding to the updated information signal is generated and it is then recorded superimposed on to the information recorded previously in the magnetic card without erasing the old information. Since the information is spectrum spread, alteration is difficult. Moreover, the magnetic card may be discriminated whether it may be used or not by considering the old information recorded in the magnetic card when it is used.

Abstract: A magnetoresistive transducer biasing technique that provides a uniform transducer biasing in a product. The technique provides biasing for transducer constant power dissipation, constant sensor current density biasing, constant sensor bias voltage, constant sensor temperature rise biasing, and constant effective magnetic biasing of a transducer.

Abstract: A read channel for use in a disk drive having an MR head. The read channel comprises a compensation device which has a high-pass filter (HPF) for compensating a thermal asperity (TA). The read channel suppresses level changes of a data signal which have resulted from TA disturbance present in the data signal. The read channel has a switch circuit connected to the input of the HPF, for canceling the DC undershoot present in the data signal. The switch circuit maintains the DC level of the data signal at zero level while a thermal asperity is being detected in the data signal.

Abstract: An apparatus and method are disclosed for improving data recovery operations in a disc drive employing a redundant sync data block format. The disc drive includes a rotatable disc and a controllably positionable head which is used to store user data in a plurality of data blocks on tracks of the disc. Each data block includes a user data field to store user data, a first sync field and a redundant, second sync field, the sync fields storing first and second sync words, respectively, which establish symbol boundaries used by a read channel of the disc drive. User data are recovered from a selected data block by initiating a delay of selected duration during which a first portion of the selected data block passes proximate the head, allowing the second, remaining portion of the selected data block to be read at the completion of the delay.

Abstract: An improved disk cartridge has a light emitter and a light detector and a baffle plate disposed between the emitter and the detector. The detector functions to denote the presence of reflected light from a retroreflective marker disposed on a disk cartridge. The baffle plate acts as a filter to minimize the amount of light reflected from sources other than the retroreflective marker that is received by the detector. By minimizing the amount of light seen by the detector from sources other than the retroreflective marker, the retroreflective marker on a disk cartridge can be placed in close proximity to the emitter and detector. It is advantageous for a disk drive of compact design, such as those within a lap top computer.

Abstract: An apparatus and method for detecting low flying read/write heads provides for the detection of contact between an air bearing slider/transducer assembly and a surface feature developed on a surface of a data storage disk. The apparatus includes a transducer disposed on an air bearing slider. An actuator is coupled to the slider/transducer assembly typically by employment of a head suspension assembly. The processor, in response to position error signals developed from servo information provided on the disk surface, moves the actuator and slider/transducer assembly to prescribed disk surface locations. The processor further processes non-repeatable position error signal values developed at a plurality of disk surface locations to detect an occurrence of contact between the slider/transducer assembly and a surface feature arising from the disk surface.

Abstract: A method and apparatus for performing head switch operations in a magnetic disk system with a magnetic disk device that is segmented into a plurality of cylinders. The cylinders are grouped into an inner zone, a middle zone, and an outer zone. The inner zone is near the innermost area of the magnetic disk device. The outer zone is near the outermost area of the magnetic disk device. The middle zone is in between the inner zone and the outer zone. The head switch is performed from a current head at a current cylinder to a target head at a target cylinder. Prior to the head switch, the system determines if the current cylinder is in either the inner zone or the outer zone. If the current cylinder is in either the inner zone or the outer zone, then the system determines if the target cylinder is in either the inner zone or the outer zone. If the target cylinder is in either the inner zone or the outer zone, then the system seeks the current head to the middle zone and then performs the head switch.

Abstract: It is known in the case of digital helical track recording and replay apparatuses for audio, video and general data to be recorded for pilot tones to be interleaved in the data tracks, for tracking. The interleaving can be carried out simultaneously with the data by frequency decoupling (a) or by superimposition (b). The invention is based on the object of providing a helical track recording and replay system which carries out tracking in a simple manner. According to the invention, the ATF signal is obtained in a filter module, which also carries out the rectification of the filtered-out pilot tones. The two DC voltage levels are interrogated and processed in the servo microcontroller, with A/D converters. Coupled to the rotation of the head drum, pulses are produced by the servo system which switch the ATF conditioning over between direct operation and tracking operation, so that evaluation is achieved by the microcontroller during the fast ATF burst phase.