Abstract: A signal reproducing apparatus is arranged to have two reproduced signals reproduced from a plurality of tracks formed on a magnetic medium by two rotary heads arranged to rotate 180 degrees out of phase with each other and which trace positions shifted from each other, to extract, from the two reproduced signals, two signals having respective different levels used for tracking control, and to perform tracking control by using the two extracted signals to cause the heads to trace positions shifted from a predetermined track. The arrangement enables the heads to stably trace track positions shifted from positions to be traced in the normal reproduction.

Abstract: An erasing device includes a first erasing mode for erasing the signal of an area of a recording medium, and a second erasing mode for erasing the signal of designated plural areas. The erasing operation in the first or second erasing mode is rendered possible as long as a necessary power supply is available, by selecting the limit power source voltage prohibiting the start of operation in the second erasing mode to be equal to or higher than the power source voltage prohibiting the start of operation of the first erasing mode, and also selecting the limit power source voltage prohibiting the continuation of operation in the second erasing mode, in the course of erasing operation in the second erasing mode, lower than the power source voltage prohibiting the start of operation of the first erasing mode. Also the operation can escape from the second erasing mode in suitable manner if the power supply becomes deficient in the course of operation in the second erasing mode.

Abstract: An erasing apparatus in which an erase standby mode is set before executing an erase operation. Circuitry is provided for measuring an elapsed time of the erase standby mode during which the erasing operation is not executed. Circuitry is provided for automatically releasing the erase standby node in accordance with a measuring result of the measuring circuitry.

Abstract: The digital VTR includes an extractor, variable-length decoder, quantizer and variable-length encoder. The extractor receives digital data divided into blocks, and which is quantized and variable-length coded on a block-by-block basis. Portions of the digital data are encoded according to a first type of encodation, and other portions of the digital data are encoded according to a second type of encodation. The extractor identifies and extracts the digital data encoded according to the first type of encodation. The variable-length decoder variable-length decodes the extracted portions of the digital data, while the quantizer quantizes the decoded data output by the variable length decoder. The variable length encoder variable-length encodes the quantized decoded data to form special-playback data. Alternatively, a convertor converts the extracted portions of the digital data into variable-length coded data having different quantization steps to form the special-playback data.

Abstract: A disk recording medium includes a servo track pattern where a gray code field has been deleted, capable of embodying a high capacity hard disk drive. The hard disk drive which uses as a recording medium, a disk having a plurality of servo sectors for each track, includes: a first plurality of servo track patterns on each track, the number of first servo track patterns equal to the total number of first servo sectors existing on each track divided by the number of heads of the hard disk drive, each of the plurality of servo track patterns having a gray code field for providing information for each track; and a second plurality of servo track patterns on each track, the number of second servo track patterns equal to the total number of servo sectors existing on each track minus the number of first servo track patterns, each of the second plurality of servo track patterns corresponding to the first servo track pattern but with the gray code field deleted.

Abstract: A preamplifier bias circuit for use in an AC coupled magnetoresistive read head amplifier which includes a pair of head contacts, a pair of amplifier inputs, a pair of coupling capacitors and a means for selectively shunting the amplifier inputs and rapidly charge the coupling capacitors. The pair of head contacts and the pair of amplifier inputs couple the preamplifier bias circuit to a magnetoresistive element and a read amplifier, respectively. Each of the coupling capacitors is connected between one of the head contacts and one of the amplifier inputs to block a static potential across the magnetoresistive element. The means for selectively shunting the amplifier inputs selectively provides a low impedance path to rapidly charge the coupling capacitors and clamps the amplifier inputs to a known potential. By selectively providing a low impedance path, the AC coupled magnetoresistive read head amplifier can be protected and its associated delay time prior to operation can be decreased.

Abstract: Disclosed is a PRML regenerating apparatus for regenerating a signal read by a head from a storage medium. This PRML regenerating apparatus has a waveform equalizing circuit for waveform-equalizing the read signal, a maximum-likelihood decoder for maximum-likelihood-decoding, after obtaining a determination value by comparing the equalized output with upper and lower slice levels, this determination value and a control circuit for setting variable a distance between the upper slice level and the lower slice level of the maximum-likelihood decoder. The distance between the upper and lower slice levels can be thereby set variable in accordance with an equalization characteristic. A ternary determination circuit of the maximum-likelihood decoder is constructed of a memory for storing a correspondence table of the equalized output and the upper or lower slice level versus the determination result and the next upper or lower slice level.

Abstract: In an optical information recording-reproduction apparatus, a focus servo control circuit generates a focus error signal and a light beam is accurately converged on a surface of an optical disk according to a focus servo control signal based upon the focus error signal. In accordance with the present invention, the focus error signal is compensated by selecting a land section focus offset amount by a switch when land sections are tracked, and it is compensated by selecting a groove section focus offset amount when groove sections are tracked. As a result, since the land sections and the groove sections are controlled by different focus servo control signals, recording and reproducing operations are carried out at the most optimal focusing positions respectively obtainable, thereby making it possible to significantly improve the quality of a reproduced signal.

Abstract: A multi-track density direct access storage device is disclosed. In accordance with a preferred embodiment of the present invention, a direct access storage device for data storage within a data processing system comprises a housing, a rotatable spindle, at least one disk, and several heads. The disk is fixedly mounted to the rotatable spindle, and the rotatable spindle is rotated by a motor within the housing. A first disk surface of the disk has a first track density and a second disk surface of the disk has a second track density; wherein the second track density is preferably greater than the first track density. Each of the several heads contains a transducer to read and write information from and to the disk during the disk rotation.

Abstract: Adaptive channel optimization in a disk drive is achieved by selecting a track of the recording medium and then writing a first data pattern to opposite sides of the selected track. The first data pattern is written a certain percentage off-track in relation to the centerline of the selected track. A second data pattern is then written directly on the selected data track and the off-track margin is determined as a function of how far the recording head can be positioned away from the center of the selected track during reading of the second data pattern while meeting a specified error rate. The off-track margin test is repeated iteratively using a combination of channel variable settings in order to find a set of variable settings which provides an optimal performance criteria for the drive.

Abstract: A switch device switchable as a first channel (200) to an inactive state and a dummy channel (201) to an active state the switching device switches the dummy channel to an inactive state while switching a second channel 300 to an active state.

Abstract: A magnetic disk device of embedded-servo type is capable of performing dummy operation for suppressing waveform degradation of signal reproduced by magnetic heads at a high speed with high reliability. When a waveform deformation occurs in a No.0 head, a controller changes over the No.0 head to a No.1 head operating normally, whereupon a cylinder portion for which dummy operation is to be performed is sought on the basis of the servo information supplied from the No.1 head. The cylinder portion destined for the dummy write operation contains servo information at timing positions that are the same for the individual magnetic heads. When passing of the No.1 head over the cylinder portion is confirmed, the No.1 head is changed over to the No.0 head for performing dummy write operation for suppressing the waveform deformation of the reproduce signal outputted from the No.0 head. Before the timing for succeeding information, the No.1 head is restored-by issuing a head change command signal.

Abstract: A method for magnetically recording/reproducing comprising recording an information signal by forming a pattern of a soft magnetic material in a magnetic recording medium; providing a magnetoeletric converting element in a place neighboring a face of forming the pattern of the magnetic recording medium on which the pattern is formed, applying a magnetic field to the pattern; and reproducing the information by detecting a variation of the magnetic field caused by the pattern of the soft magnetic material of the magnetic recording medium while relatively moving the magnetoelectric converting element and the magnetic recording medium.

Abstract: An AGC circuit is used for read channels of a disk storage apparatus, by controlling a level of a reading output of a head to be kept constant. This AGC circuit has a gain control amplifier and a feedback circuit for digitally feeding back an output thereof. A maximum current value of a current type D/A converter is varied for every zone in zone bit recording. A gain adjusting time of the AGC circuit can be therefore minimized in each zone. A GAP length in the respective zones can be thereby reduced, and a storage capacity is increased. A maximum current value of the current type D/A converter is varied in a read/write area and a data surface servo area on a disk storage medium. It is therefore feasible to minimize the gain adjusting time of the AGC circuit in each of the servo area and the read/write area. The current type D/A converter is set so that a plus-side maximum current value is different from a minus-side maximum current value.

Abstract: An analog waveshaping circuit is capable of performing waveshaping of an AC analog signal in which the positive and negative peak levels with respect to a reference level are not the same, while considering a DC offset component of the reference level of the analog waveform, so that the positive and negative levels with respect to the reference level are made equal.

Abstract: The invention provides an image signal processing apparatus for processing an image signal. When an image signal is supplied and the input image signal is stored onto a memory medium and the image signal stored on the memory medium is generated, only the image signal generated from the memory medium in the image signal stored on the memory medium can be erased, so that the image signal can be stored by a simple construction without erroneously erasing the image signal stored on the memory medium.

Abstract: A write driver, having a pair of head nodes for connection to a write head, includes two diodes connected respectively the head nodes and the emitters of first and second upper drive transistors. The diodes, which are preferably Schottky diodes, increase the voltage necessary to breakdown the emitter pn junctions of the upper drive transistors, thereby enabling a greater head swing voltage, higher switching rates, and ultimately closer spacing of data on a magnetic medium. Additionally, a preferred embodiment of the write driver includes two voltage clamps, each coupled between a respective head node and a first supply node, to limit the magnitude of voltage spikes resulting from self-inductance of the write head.

Abstract: A cartridge for a data storage disk drive has a thin retroreflective marker. Light from a source is reflected from the marker almost exactly on its incident path. A planar light shaping optical structure such as a holographic light shaping diffuser (LSD) ruled or blazed diffraction grating, holographic diffraction grating, binary optics or holographic diffraction grating directs light to the detector. The LSD has degrees of angular diffusion in different orthogonal axes. This property makes possible unique identification of different types of cartridges.

Abstract: An information storing device and an information processing device having a memory for registering a plurality of working modes at recording/reproduction and a switching circuit for selecting one of the plurality of working modes, which select the optimum working mode automatically or by an instruction of an operator according to power supply capacity of a device of higher rank to effect recording/reproduction.

Abstract: A data storage system that uses a magnetic head assembly having a write head and a read head mounted on a slider to write on and read from a disk. A portion of the coil of the write head is used as a wear sensor for detecting wear on the surface of the slider. A head IC monitors the coil voltage and, when it goes lower than a reference voltage, detects the occurrence of a fault in the write head due to excessive wear on the slider surface. In response to the detection of the fault in the write head by the head IC, a control driver prohibits a write operation and saves data already recorded on the disk.