International Business Machines Corporation

Jerry Lee Highnote

Richard Lewis O'Day

A unique concentric rotary transformer for use in a rotating head tape transport, wherein a length of tape is positioned relative to the rotating head and data is recorded and/or reproduced therefrom, is disclosed. The rotary transformer comprises two assemblies one of which rotates relative to the other and thereby transmits electrical signals. Each assembly includes a ferrite cylindrical core piece with two grooves machined in the core piece. The grooves are axially and circumferentially displaced along a longitudinal axis of said core piece. A continuous coil with two legs, is positioned within the grooves of the core piece whereat mutual inductances generated in the ferrite core by each leg of the coil effectuate signal transfer across the transformer interface.

Rotary transformer with unique physical and electrical characteristics

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

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

Jerry Lee Highnote