Storage Technology Corporation

International Business Machines Corporation

Richard Lewis O'Day

Steven Gregory Trabert

John Paul Mantey

Ronald Dean Gillingham

Jerry Lee Highnote

Richard H Dee

James C Cates

Fernando Castro

A servo track writer head writes servo tracks on a data storage tape with increased accuracy. The servo track writer head includes a leading writer for each servo track. Each leading writer writes a synchronization field on the tape. The servo track writer head also includes a sequence of trailing writers for each servo track. Each trailing writer produces at least one trailing field on the tape a fixed distance behind the synchronization field. The servo track writer head also includes one timing writer. Each timing writer writes a timing field on the tape at a timing distance in the tape direction from each of the synchronization fields. The servo track writer head also includes a sequence of timing readers corresponding to each timing writer. The number of timing readers in the sequence is equal to the number of trailing writers in the sequence of trailing writers. Each timing reader reads the timing field on the tape written by the corresponding timing writer and generates a signal used to initiate writing of corresponding trailing fields. The positioning of timing readers permits the appropriate fixed distance behind synchronization fields for writing trailing fields to be determined.

Tape head with pattern timing for servo writing application

A magnetic tape servo pattern including track identification. Information from a track identification area intersecting one or more tracks on each frame in combination with information identifying the track as odd or even, is used to uniquely identify the track.

Tape servo pattern with embedded servo track number identification

A method for identifyng a servo track. Information from the servo track about the odd or even number of the track is combined with information about the presence or absence of a track identification area to identify the track number.

Method for servo track identification

A differential amplifier comprises a pair of Darlington configuration amplifier halves operating in the Class A mode. Each Darlington half is provided with a feedback, difference amplifier, which functions as an analog comparator, and an emitter current control resistor to precisely control the emitter current and thereby to control the idling or quiescent current passing through a load in the collector circuit. Each difference amplifier is connected to its respective half by coupling one of its two inputs to the control resistor in the Darlington emitter circuit and coupling the other input to a source of reference voltage. The respective emitter current control resistors are precisely matched. In operation, the output of each difference amplifier drives the base circuit of its respective Darlington half. The difference amplifier maintains the voltage at the terminal of the emitter current control resistor at a value substantially equal to the reference voltage, thereby biasing the Darlington half at a constant value representative of emitter current. Because the control resistors are precisely matched, the emitter currents are equal; and, because the gain of the Darlington halves is very high, the load or collector currents are substantially equal to the respective emitter currents and to one another. Thus, a load driven by both collector circuits is provided with a substantially zero d.c. offset current.

Darlington configuration high frequency differential amplifier with zero

The equivalent of D.C. erase in magnetic tape using a rotating head is accomplished by transmitting a time asymmetric square wave across a rotary transformer to the rotating head. The time asymmetry of the square wave in combination with passage of the square waveform across the rotary transformer creates in the rotating head an erase current asymmetric in amplitude about an average value. The short interval of the square wave has a large amplitude in one direction and the long interval portion of the square wave has a short amplitude in the opposite direction. This current signal in the head produces alternately a large flux bubble above the head and a small flux bubble above the head. By maintaining the relative head to tape speed such that the large flux bubble always overlaps the small flux bubble, the tape can be D.C. erased by an asymmetric waveform. A double-ended driving circuit and a single-ended driving circuit are shown for driving across a rotary transformer to the rotating head with the asymmetric waveform.

Asymmetric erase across a rotary transformer to a rotating magnetic head

A rotating head magnetic tape unit having a fixed stator and a rotating rotor is disclosed. A plurality of transformers are positioned between the rotor and the stator so as to establish an interface for the transmission of electrical signals. Circuit means is provided on the rotor of the rotating head magnetic unit for reclocking data phase shifted by the transformer interface, for protecting against inadvertent write on a magnetic tape, and for synchronizing the clock with the data in a write driver whereby the clock may be used as A.C. bias for the written signal. An N times data frequency clock signal received on the rotor is divided N/2 to obtain the reclocking signals. With regard to the synchronization between the clock and write driver, the N times data frequency clock on the rotor is synchronized on the write driver with the data to accomplish A.C. bias recording.

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Boulder, CO, United States of America

Richard Lewis O'Day