Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. According to yet another embodiment, the temperature in the disk drive is measured by a thermometer 18, and if the temperature is higher than a reference value, information is automatically copied at shorter intervals than when the temperature is less than the reference value.

Abstract: Copying, dubbing or reproducing copyrighted digital data can be inhibited or restricted to properly protect a copyright. AV data recorded on a pre-recorded tape is output from a reproducing unit of a first digital VCR with protective information indicating whether the copy of the AV data is inhibited or not. The protective information is input with the A/V data to a second digital VCR. Copy permission information of a blank tape loaded in the second digital VCR is discriminated and the second digital VCR records the AV data supplied from the first digital VCR based on the protective information and the copy permission information.

Abstract: A gray code decoding circuit of a hard disk drive includes a servo pattern area, a data pick-up device, and a pattern detecting device. The servo pattern area has data recorded as a gray code. The data pick-up device detects the recorded data, converts it into encoded read data, and outputs the encoded read data. The pattern detecting device detects a position of the servo pattern area in response to the encoded read data and outputs a reference pulse. The gray code decoding circuit also contains a gray window generating device, a synchronous signal generating device, a gray code extracting device, and a gray-binary converting device. The gray window generating device divides the encoded read data by a division ratio, converts the divided encoded read data into gray data, outputs the gray data, and generates a first synchronous signal after counting by a system clock to a first value. The synchronous signal generating device outputs first and second window signals in response to a second synchronous signal.

Abstract: The invention provides a clock signal extraction circuit which can extract a synchronizing clock signal accurately from a readout waveform reproduced from information recorded in a high density and which includes substantial intersymbol interferences. An analog readout signal is converted into binary information with a synchronizing clock signal from a voltage controlled oscillator. A replica signal is produced from the binary information by a waveform replica production circuit while time corrected readout waveform data are produced from the analog readout signal by a delay circuit, and a phase amount is detected from the time corrected readout waveform data and the replica signal by a phase amount detection circuit. The base amount is used to control the voltage controlled oscillator, thereby forming a phase locked loop to perform a follow-up operation to the readout signal.

Abstract: Momentary contact with a defect site of a data storage disk or free particle by a magnetoresistive read element of a flying head causes momentary heating and unwanted increase in element resistance (thermal asperity) which can disrupt hard disk drive data reading operations. Since the disk carries a predetermined data format, the disk drive controller correlates location of a thermal asperity to the format and thereupon selects from several available thermal asperity recovery methods a method most likely to minimize thermal asperity effect upon disk drive operation during rereading of data at the thermal asperity location.

Abstract: Inserting operational data onto a magnetic disk allows information to be transferred from a servowriter station to a verifier station. This operational data allows disk specific operational data to follow the disk without separate means for attaching data to each disk. The servowriters, which cannot write information to disks at the data sector frequency, inserts the operational data into selected greycodes in the servo sectors. When the disks are verified, the operational data may be moved from the servo sectors to the data sector in the Z-tracks for more permanent storage.

Abstract: A method and apparatus for verifying that data written on magnetic disk media can be successfully recovered in subsequent read operations and ensuring that the data to be written is held by a buffer until a read-verify operation indicates that the buffer space storing the data may be relinquished for new operations.

Abstract: In a data reproducing device using a read channel of a PRML system, during a period of a continuous reproducing operation mode for continuous reproduction processing of adjacent data sectors, a restart RG generator switches a restart read gate signal RRG ON in synchronization with switching ON of a reference read gate signal RG. Therefore, when data is reproduced from a data sector before continuous data sectors, data reproduction processing is started by means of the restart read gate signal RRG equivalent to the reference read gate signal RG. When data is continuously reproduced from a next data sector adjacent to the previous data sector, the restart RG generator keeps the restart read gate signal ON for a predetermined period of time before the reference read gate signal RG is generated.

Abstract: A storage device includes a predetermined number of disks on which servo information is recorded, and a predetermined number of heads. The heads are positioned on target cylinders on the basis of the servo information read from the disks through the heads, so that information recording/reproducing can be performed. The disks include outer guard band areas located further out than data areas and inner guard band areas located further in than the data area. Analysis information concerning disk surfaces are recorded on the outer guard band areas. Each of the outer guard band areas is segmented into first and second outer guard band areas in a radial direction. The analysis information is recorded on the first outer guard band area. The servo information for an off-track correction is recorded on the second outer guard band area.

Abstract: An analog and digital combination recording and reproduction apparatus uses the existing head layout found in an analog recording and reproduction apparatus such as an existing VHS system, for recording and reproduction of both analog and digital signals on a magnetic tape. Using a video signal head or a hi-fi audio signal head for use in an extended play mode, digital video and audio signals are simultaneously recorded on tracks obtained by bisecting the standard play mode track width. Thus, the analog and digital signals can be recorded and reproduced without having additional heads for digital recording and reproduction, thereby providing a simple structure and minimizing costs.

Abstract: A quad burst servo demodulator with adjustable slew rate for hard disk drives. The quad burst servo demodulator includes a peak voltage detecting system for detecting the peak voltages of an input signal, a plurality of storage capacitors for holding voltages proportional to the peak voltages observed by the peak voltage detecting system, and a programmable current source for charging (via an adjustable slew rate) the storage capacitors to voltages proportional to the detected peak voltages of the input signal.

Abstract: A disc drive data recovery system for recovering data from a magnetic disc having asperities is disclosed. The data recovery system includes a magnetoresistive head for reading magnetically encoded data from the magnetic disc and providing in response a signal indicative of the magnetically encoded data. Contact between the magnetoresistive head and an asperity corrupts the signal such that the signal contains thermal asperity noise. The data recovery system includes an asperity recovery filter coupled to the magnetoresistive head for receiving the signal from the magnetoresistive head and reducing the thermal asperity noise in the signal.

Abstract: The present invention provides an apparatus and method of partitioning a recording medium data track into two longitudinal regions and erasing any preexisting signal on each region with a DC bias signal of polarity opposite to that of the other region. Magnetic transitions subsequently recorded over the two track regions will be shifted differently depending on the relationship of the polarity of the signal being encoded to that of the DC bias erase signal applied to each region. The complementary lead/lag errors from the two track regions produce a combined read head waveform in which the timing errors are substantially eliminated, thereby reducing system bit error rates and allowing increased data density on the medium. An apparatus and method of controlling the lateral position of the various heads are also disclosed.

Abstract: The disk drive, which is used for performing at least a reproducing operation for a disk-shaped recording medium having a PEP region where information relating to the at least a reproducing operation is recorded, includes: a rotator for rotating the recording medium; a pickup for reading a signal from the recording medium; processing circuits for thresholding a length of a period in which the level of the signal remains unchanged; a demodulating circuit for receiving the thresholding result and for demodulating the signal to reproduce the information based on the thresholding result; a detector for detecting the rotation speed of the recording medium and for outputting a rotation speed signal indicative of it; correcting circuits for receiving the rotation speed signal, and for supplying a discrimination value in accordance with the rotation speed of the recording medium. The discrimination value is used for thresholding the length of the period.

Abstract: An amplifier in which a clamping circuit is an integral part of the output stage structure is used as a voice coil driver for positioning the heads of a memory disk drive. The output stage, operating in class AB, comprises two bipolar transistors, the source and the sink transistors, serially connected between a power supply and a ground terminal, the serial connection between the emitter of the first transistor and the collector of the second transistor being the output terminal of the output stage. The base terminals of the two output transistors are connected to a bias circuit and to an input transistor, used as the signal control element. The clamping circuit is directly connected with the base terminals of the output transistors to limit the voltage on said base terminals between a first and a second voltage reference.

Abstract: A magnetic reproduction apparatus with a cross-talk reduction system that includes first and second magnetic heads, wherein the distance between the first magnetic head which has a plus azimuth angle and the second magnetic head which has a minus azimuth angle is provided so that the second head scans a track which is previously scanned by the first magnetic head. The apparatus also provides (i) a delaying circuit for delaying a first reproduction signal of the first magnetic head, (ii) a first filter for extracting a cross-talk component from an output of the delaying circuit, (iii) a second filter for extracting a cross-talk component from a second reproduction signal of the second magnetic head, (iv) a first adder for adding the second reproduction signal's cross-talk component which is inverted and the output of the delaying circuit, and (v) a second adder for adding the first reproduction signal's cross-talk component which is inverted and the second reproduction signal.

Abstract: A magnetic tape recording with a new signal encoding format, apparatus for recording this format and reproducing apparatus for reproducing signals from this format. A standard VHS signal is recorded as a first set of parallel slant tracks having a predetermined spacing between each slant track. A high definition television signal is recorded in pairs of slant tracks of a second type that flank a slant track of the first type and are narrower in width than the slant track of the first type they flank. Additionally, the azimuth angle of the tracks of the first type alternates between different predetermined values for successive tracks, and the azimuth angle of the tracks of the second type differ both from the azimuth angle of the tracks of the first type which they flank, and from the azimuth angle of the tracks of the second type which are positioned next to them in the space between tracks of the first type.

Abstract: A device and system for the reading of a recording medium, which enables the reading of high-density information and the removal of disturbance (or cross-talk) from the information. The invention includes chiefly a reading device carrying out the parallel reading of the information from N pixels of an optical detector array and giving at least two sub-trains of samples in series (X, Y, Z), a cross-talk correction circuit for each sub-train of samples, each sub-train giving a train of cross-talk corrected samples (X', Y', Z'), and an input sequencer giving each correction circuit a train of samples to be corrected (Ys) from a first sub-frame of samples (Y) and samples (XN-1, Z0) from at least one second frame of samples (X,Z). This device and system can be applied to the reading of high-density recording media (magnetic or optical).

Abstract: A high-recording-density magnetic disk drive is provided which minimizes changes in the distance between a magnetic disk and a magnetic head and is reduced in size and weight. The magnetic head and a support spring which supports the magnetic head are rotated over the magnetic disk which is stationary, and a base which supports the support spring is rotated by a rotary actuator for tracking on the magnetic disk.

Abstract: A magnetic recording system utilizing a plurality of surfaces on a magnetic recording disk with recording zone boundaries established on the respective surfaces of the disk based on the performance characteristic of the read/write head associated with the surface. Since the zone boundaries are established uniquely for the performance of each head rather than by defining the boundaries of all zones for all surfaces in advance based on an assumed performance characteristic of the heads, the zone boundaries on one surface of the disk will not necessarily align with the zone boundaries on another surface of the disk. Similarly, when a plurality of disks are utilized, the zone boundaries will not necessarily be aligned. Improved utilization of the available stroke on the disk drive permits further improvement in recording density.