# US 4,400,752 A · Magneto-electric transducer for a magnetic recording system and recording system comprising such a transducer

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- Number: US 4,400,752 A
- Document ID: US4400752A
- Status: Granted
- Kind: A
- Application number: 06/169,353
- Filed: 1980-07-16
- Granted: 1983-08-23
- Earliest claimed: 1979-07-20
- Assignees: LCC-CICE Compagnie Europeene de Composants Electroniques
- Inventors: Jacques Chabrolle
- Web page: https://patentgrep.com/patent/US4400752A

## CPC

- G11B 5/035: Equalising
- G11B 5/33: Structure or manufacture of flux-sensitive heads, {i.e. for reproduction only; Combination of such heads with means for recording or erasing only}({Single head using magnetic domains for scanning G11B5/4946; multiple head for scanning G11B5/4907 and subgroups } ; general details therefor G11B5/133 - G11B5/255)
- G11B 5/37: using galvano-magnetic devices, e.g. Hall-effect devices (G11B5/39 takes precedence){using Hall or Hall-related effect, e.g. planar-Hall effect or pseudo-Hall effect}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

The invention is directed to transducers for recording on (writing) and playback from (reading) a magnetizable support medium. A single transducer (head) provides both record and playback functions. Recording is carried out using a winding for inducing an external magnetic flux across a gap in the transducer and playback is carried out by sensing an internal leakage flux using a Hall effect magneto-resistive element placed outside of a gap in the head. The magneto-resistive element delivers a substantially linear electrical signal response as a function of the magnetic field applied by relative motion between the transducer gap and the support medium.

## Claims

### Claim 1

A magneto-electric read/write transducer, comprising:
a magnetic circuit in the form of a flat ring having external and internal faces and a single non-magnetic gap therein, for producing (a) an external flux across the gap at its external face for interacting with a magnetizable support medium and (b) a leakage flux across the gap at its internal face;
a coil wound about the ring for inducing a flux in the magnetic circuit; and
a magneto-sensitive element positioned internal of the ring substantially within a region that would be subjected to the leakage flux for generating an electrical signal responsive to the leakage flux in the magnetic circuit.

### Claim 2 (depends on 1)

A transducer according to claim 1, wherein the internal and external faces have a generally cylindrical form with generatrices perpendicular to the plane of the ring.

### Claim 3 (depends on 1)

A transducer according to claim 1, wherein the portions of said external and internal faces on to which said air-gap opens are respectively convex and concave.

### Claim 4 (depends on 1)

A transducer according to claim 1, wherein the portions of said external and internal faces on which said air-gap opens are convex.

### Claim 5 (depends on 1)

A transducer according to claim 1, wherein said magneto-sensitive element is of the "Hall effect" type.

### Claim 6

A magnetic recording/playback system comprising
a magneto-electric read/write transducer including
a magnetic circuit in the form of a flat ring having external and internal faces and a single non-magnetic gap therein, for producing (a) an external flux across the gap at its external face for interacting with a magnetizable support medium and (b) a leakage flux across the gap at its internal face;
a coil wound about the ring for inducing a flux in the magnetic circuit; and
a magneto-sensitive element positioned internal of the ring substantially within a region that would be subjected to the leakage flux for generating an electrical signal responsive to the leakage flux in the magnetic circuit;
a recording amplifier having an input for coupling to a signal to be recorded and an output coupled to the coil;
a playback amplifier having an input coupled to a signal output of the magneto-sensitive element for amplifying a read signal generated thereby and providing at an output thereof an amplified playback signal.

### Claim 7 (depends on 6)

A system according to claim 6 further comprising a feedback circuit for coupling a signal from the output of the playback amplifier to the input of the recording amplifier.