Irwin Magnetic Systems, Inc.

Michael L Bolt

Housan Dakroub

John M Chambors

Samuel N Irwin

Francis Lum

Marlin K Klumpp

Edmund L Sokolik

Richard A Farkas

Steven E Henke

The specification discloses means for correcting timing variations present in a data stream emanating from a data storage device such as a magnetic tape drive or the like before the data stream is applied to the data separator or other such input device of a computer. This is accomplished by remodulating the time-varying bits in the data stream in a manner which reduces or eliminates the undesired timing variations. Basically, the system utilizes frequency-modulation techniques to in effect remodulate the raw data stream. The application discloses, as one preferred embodiment, a pulse-width modulator which receives the error signal output of a phase-locked loop network, the input of the pulse-width modulator being coupled to the incoming raw data stream. The primary output of the phase-locked loop circuit is coupled to the input of the pulse-width modulator, and the output of the pulse-width modulator is coupled to the input of a pulse generator so as to produce output pulses of substantially uniform width which occur in synchronism with output pulses of the pulse-width modulator and thus constitute in effect a remodulated version of the raw data stream, in which the undesired timing variations have been removed or reduced by an acceptable level.

Method and apparatus for removing data stream variations

A magnetic core structure for a 'read-write' transducer head of the type known as a 'wide-write, narrow-read' head, having at least one magnetic gap, wherein the magnetic pole structure performing one of the transducing functions (e.g. the 'write' function) is in effect wider than that performing the other (e.g. the 'read') function. At least one such magnetic pole has a laminar structure comprising at least one medial layer or strata and at least one flanking layer or strata which is disposed adjacent to and overlying at least portions of the medial strata, to thereby define an included area of overlap therebetween. The thickness of the medial strata, measured along the length of the gap, is less than that of the magnetic core structure on the opposing side of the gap. At least one non-magnetic isolation member is disposed between the flanking strata and the medial strata, the flanking strata, comprising a magnetic material, being disposed in magnetic communication with the medial strata, to thereby magnetically shunt portions of the medial strata. The included area of overlap between the medial strata and the flanking strata is particularly configured so as to limit the transfer of magnetic flux between the flanking strata and the medial strata across the isolation members at the included area to less than about ten percent of the total magnetic flux in the magnetic circuit.

Magnetic transducer head structure with reduced leakage between core

A magnetic core structure for a 'read-write' transducer head of the type known as a 'wide-write, narrow-read' head, having at least one magnetic gap, wherein the magnetic pole structure performing one of the transducing functions (e.g. the 'write'function) is in effect wider than that performing the other (e.g. the 'read') function. At least one such magnetic pole has a laminar structure comprising at least one medial layer or strata and at least one flanking layer or strata which is disposed adjacent to and overlying at least portions of the medial strata, to thereby define an included area of overlap therebetween. The thickness of the medial strata, measured along the length of the gap, is less than that of the magnetic core structure on the opposing side of the gap. At least one non-magnetic isolation member is disposed between the flanking strata and the medial strata, the flanking strata, comprising a magnetic material, being disposed in magnetic communication with the medial strata, to thereby magnetically shunt portions of the medial strata. The included area of overlap between the medial strata and the flanking strata is particularly configured so as to limit the transfer of magnetic flux between the flanking strata and the medial strata across the isolation members at the included area to less than about ten percent of the total magnetic flux in the magnetic circuit.

Magnetic transducer head structure

A miniaturized tape cartridge drive for data processors in accordance with the invention has as peripherally-enclosing main frame providing an access opening for insertion to a tape cartridge and structurally mounting flat, pancake-type drive motors for tape transport and head-positioning translation laterally with respect to the tape, for accessing any of a plurality of adjacent recording tracks on the tape, such motors being disposed in tandem with respect to the cartridge-admitting opening and having their output shafts pointing in opposite directions. The head-positioning motor drives a directly-coupled rotary cam, and a positioning arm extends between the cam and the transducer head to move the head in response to movement of the cam. The positioning arm is pivotally journaled in opposite sides of the main frame upon a transverse pivot axis disposed medially of the arm, such that the arm operates as a fulcrumed lever.

Growing community of inventors

Ann Arbor, MI, United States of America

Michael L Bolt