Abstract: Improvements in placement of timing patterns in self-servowriting include correcting for random errors. Random errors may be caused by variations in disk velocity and therefore, one technique for correcting for random errors includes reducing velocity jitter. Additionally, random errors can be corrected by improving interval control during the propagation of trigger patterns used in writing timing information on storage media. Further, random errors, in the writing of timing information, can be corrected during a single revolution of the storage media. This eliminates additional rotations, thereby providing a large capital cost savings.

Abstract: A method and apparatus for positioning a head over a track in an information recording medium to eliminate head positioning error. Data tracks are concentrically formed on a magnetic disk, and identification information for identifying each data track is recorded so as to correspond to each data track. The identification information consists of first and second gray codes, and the first gray code is of n-1 bits where n represents the number of bits of a track address and set for each block so that it has a value different among a plurality of blocks each consisting of a plurality of data tracks. The second gray code is of three bits, and set for each data track so that it represents a value which differs between data tracks contiguous in the radial direction of the disk and circulates for every three or more blocks continuous in the radial direction of the disk. Head positioning is determined based on reading the first and second gray codes by the head.

Abstract: A write current is set to be an optimum write current. The write current is supplied to a recording head when information is recorded on a recording medium. First margin characteristics are measured which are used for obtaining a lower limit value of the write current to be supplied to the recording head. Second margin characteristics are measured which are used for obtaining an upper limit value of the write current to be supplied to the recording head. As the lower limit value of the write current, a write current value is set for which a margin has a predetermined value in the first margin characteristics. As the upper limit value of the write current, a write current value is set for which a margin has a predetermined value in the second margin characteristics. As the optimum write current, a write current is set which has a middle value between the lower limit value of the write current and the upper limit value of the write current.

Abstract: A servo stripe pattern for determining the longitudinal position of the tape with respect to the tape head. A data field on each frame of the servo pattern includes a digital one or a zero. An adjacent series of data fields are arranged in a predetermined sequence defining synchronization and position count fields. The position count field allows the tape controller to accurately determine where, along the length of the tape, the tape head is currently positioned.

Abstract: A method formats disc surfaces in a disc drive for storage of data in a group of tracks on the disc surfaces. The disc drive performs seek operations to seek among cylinders on the disc surfaces as a function of time according to an actual seek profile. An approximation of the actual seek profile is determined such that the actual seek profile falls within the approximation. The disc surfaces are formatted according to the approximation of the actual seek profile.

Abstract: A retroactive recording device, having a main recording medium, temporarily stores past information in a memory. In particular, an audio tape recorder includes a solid state retroactive memory which is operated continuously to temporarily store a past time interval of digital audio information. To begin retroactive recording, all or a portion of the past information stored in the retroactive memory is transferred to the recording medium. After transferring the desired past information, recording is continued in real time. In one embodiment, where the recording medium is a magnetic audio tape, temporarily stored past information is transferred to the audio tape by operating the audio tape transport mechanism at a higher than normal speed so as to catch up to present time. In another embodiment, where the recording medium is a non-volatile memory, temporarily stored past audio information is transferred to the non-volatile memory, and the present recording is continued in real time.

Abstract: A method for adjusting the frequency response of a servo loop is provided that positions a servo head at a nominal position over a medium and determines the frequency response of the servo loop. A compensation gain is determined at the nominal position such that when the compensation gain is combined with the servo loop's frequency response, the compensation gain causes the frequency response to approach a desired frequency response. In addition, a servo loop and a disc drive with such compensation gain are provided.

Abstract: Apparatus, and an associated method, protects against damage to a magnetoresistive sensor of a disk drive assembly, or other magnetic storage device, responsive to a thermal asperity event. Detection is made of the resistance of the magnetoresistive sensor. If the resistance increases, indicative of a temperature increase occurring as a result of a thermal asperity event, a full-sense current, or current of other appropriate magnitude is applied to the sensor, thereby to prevent alteration by the magnetic field of portions of the magnetoresistive sensor.

Abstract: An optimum write current, which is supplied to a recording head when the recording head is used for recording information onto a recording medium, is set. An ambient temperature is set. A plurality of write currents are set in the set ambient temperature. A signal is written onto the recording medium with the set plurality of write currents and a demodulation margin is detected for each write current of the plurality of write currents. An optimum write current is determined from the plurality of write currents for the ambient temperature based on the demodulation margins detected for the respective write currents. The above-mentioned operations are performed for each of a plurality of ambient temperatures, and an optimum write current is obtained for each ambient temperature of the plurality of ambient temperatures.

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 performance characteristics of the read/write transducer associated with the surface. The performance of the read/write transducer from the aspects of the width of the track written by the transducers as well as the recording performance at the expected recording frequency, are both utilized in building disk drives. Since the zone boundaries are established uniquely for the performance of each transducer, rather than by defining the boundaries of all zones for all surfaces in advance based on assumed performance characteristics 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.

Abstract: A detector in an informational handling system and a method of detection is provided. An input circuit is used to receive an input signal. A second circuit determines boundaries based on the input signal. However, at least two of the boundaries specified by the second circuit are monotonically related to each other. The detector can be implemented in a magnetic disc drive. A read circuit is operably coupled to the disc to read data stored on the disc. The read circuit includes an input circuit, a boundary calculation circuit, and a logic circuit operably coupled to one another. The input circuit serves to receive the data and provide an input to the boundary calculation circuit. The boundary calculation circuit calculates several boundaries based on the input. At least two of the boundaries are monotonically related. The boundary circuit provides an output to the logic circuit which provides a binary decision.

Abstract: A method and circuit in a digital recording/reproducing apparatus are provided for adaptively processing symbol timing recovery and equalization for an input signal including known signal sequence. The adaptive signal processing method includes the steps of sampling the input signal according to a sampling clock and outputting sampled data, detecting whether the sampled data is a known signal sequence and detecting a track mode from the detected known signal sequence according to a predetermined track pattern. The sampled data is equalized according to a predetermined equalization coefficient to generate equalized data. The equalization coefficient is renewed using an error between a prestored reference signal according to the track pattern and the equalized data.

Abstract: A data recording system includes media such as a magnetic disk or tape, a read/write head assembly, and a circuit that provides a write signal having edge placement equalization. The circuit responds to a binary serial data signal such as a run length limited signal of the type (1,x) and provides a write signal having data transitions corresponding to one of the two binary data values, the absence of a transition corresponding to the other data value. In addition, the write signal is provided with a pair of equalization transitions during periods of no data transitions. A first data transition is shifted away from the last provided equalization transition by a predetermined offset. A second data transition, provided immediately after the first data transition, may be shifted toward the last provided equalization transition. Timing of the data transitions is derived from a clock used to provide the equalization transitions.

Abstract: A magnetic disk unit is provided with a storage device for storing a signal output value in each position on a first circumference of a magnetic disk, and a contact detector for relating a signal output value in each position on a second circumference of the magnetic head slider to each position on the first circumference. The latter signal output values are standardized by dividing by the corresponding signal output value stored in the storage device. Contact between the magnetic disk and the magnetic head slider is detected if the standardized output exceeds a preset reference value. The contact detector outputs a signal for instructing an actuator control circuit to move the magnetic head slider to a predetermined home position if contact between the magnetic disk and the magnetic head slider is detected.

Abstract: An apparatus for recording information signals in a track (T.sub.i) on a record carrier (2) is disclosed, comprising an input terminal (30) for receiving an information signal, a signal processing unit (32) for processing the information signal so as to make the information signal suitable for recording in at least one track on said record carrier, and a writing unit (33) for writing, after processing, the information signal in said at least one track on said record carrier, starting from a start position (s) viewed in the length direction of the record carrier and in a direction towards one of the end positions of the record carrier.The portion of the record carrier (2) between said start position (s) and said one end position (L.sub.2) is fictitiously divided into a first sub portion lying (P.sub.1) adjacent the start position and a second sub portion (P.sub.2) lying adjacent the end position of the record carrier.

Abstract: Disclosed are an asymmetrical signal detector for detecting an asymmetrical quantity of an asymmetrical signal and a signal regenerating apparatus using this detector. This detector includes a first delaying element for delaying the input signal, a first subtracting element for subtracting an output of the first delaying element from the input signal, a second delaying element for delaying an output of the first subtracting element, an adding element for adding an output of the second delaying element to an output of the first subtracting element, a gate signal generating element for generating a gate signal by comparing an output of the adding element with a predetermined threshold value, a second subtracting element for subtracting the output of the subtracting element from the input signal and a selecting element for selecting an output of the second subtracting element in accordance with the gate signal, thereby obtaining an offset quantity.

Abstract: A sampled amplitude read channel is disclosed for disk storage systems employing a run-length limited (RLL) d=1 channel code which compensates for partial erasure, and a parity channel code for enhancing the operation of a remod/demod sequence detector. During a write operation, after encoding the user data into codewords comprising the RLL d=1 constraint, the parity over one interleave of a block of NRZI bits is computed and two parity bits appended to form a parity codeword. For an even number of "1" bits in the block, the parity bits are set to "00". For an odd number of "1" bits in the block, the parity bits are set to "10" if the codeword ends with a "0" bit and to "01" if the codeword ends with a "1" bit, thereby maintaining the RLL d=1 constraint. Thus, a parity codeword will always comprise an even number of "1" bits (even parity).

Abstract: A servo signal processing apparatus for processing a servo signal corresponding to servo information from a servo area on a recording medium for controlling a head. The servo area includes a servo mark area for storing a servo mark indicative of a head of the servo area, a gray mark area for storing a gray mark indicative of a head of information for position control for the head, and a gray code area for storing information. An A-D converter converts the servo signal to digital data. A digital filter filters the converted data based on a sampling clock, and outputs the filtered digital data. A servo mark detector detects a servo mark based on a continuity of a first predetermined logical value. A gray code decoder detects a gray code based on a continuity of a predetermined logical value. The gray code decoder decodes information stored in a gray code area following the detected gray mark.

Abstract: An adaptive feed forward device for decreasing current control errors, includes an adaptive feed forward controller which provides adaptive feed forward values, establishing a linear slope flexibly adjusting to the current command values for the servo control of the hard disk drive, in a deceleration section of the servo control during a track seek.

Abstract: A method and apparatus for improving the data readability in a disk drive is described. The disk drive uses an error recovery mode in which the rotational speed of the motor is decreased below the normal operating speed and a rereading is performed. The reduced speed lowers the energy generated in collisions with a foreign object and the data error length is shortened allowing data to be read which cannot be read at the normal operating speed.