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Magnetic Film Transducer Having Exchange Coupled Toroid Sensor

IP.com Disclosure Number: IPCOM000078811D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Nepala, DA: AUTHOR [+3]

Abstract

The thin-film magnetic transducer comprises three permalloy magnetic legs 10, 11 and 12, a nonmagnetic layer 14, and a conductor 15 completely surrounded by magnetic toroid 16. The transducer is deposited on a nonmagnetic substrate 20. Legs 10, 11 and 12 possess uniaxial anisotropy and have an easy magnetization axis perpendicular to the plane of the paper. Legs 10 and 12 form a magnetic shield to prevent undesired magnetic signals from being sensed. Toroid 16 comprises permalloy films 17 and 18, which are uniaxially anisotropic with their easy axis in a vertical direction. Film 17 of the toroid 16 exchange coupled to flux sensing leg 11.

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Magnetic Film Transducer Having Exchange Coupled Toroid Sensor

The thin-film magnetic transducer comprises three permalloy magnetic legs 10, 11 and 12, a nonmagnetic layer 14, and a conductor 15 completely surrounded by magnetic toroid 16. The transducer is deposited on a nonmagnetic substrate 20. Legs 10, 11 and 12 possess uniaxial anisotropy and have an easy magnetization axis perpendicular to the plane of the paper. Legs 10 and 12 form a magnetic shield to prevent undesired magnetic signals from being sensed. Toroid 16 comprises permalloy films 17 and 18, which are uniaxially anisotropic with their easy axis in a vertical direction. Film 17 of the toroid 16 exchange coupled to flux sensing leg 11.

In operation, as current flows through conductor 15 it sets up a bias magnetic field around the toroid 16, thus magnetizing films 17 and 18 in opposite directions. The magnitude of the bias field must be less than the coercive field necessary to switch the toroid. When a magnetic transition in an associated magnetic medium is under leg 11, it induces a vertical magnetization component in that leg. This component is magnetically exchange coupled to film 17 of the toroid. in a direction that is dependent upon the polarity of the magnetic transition. As the resultant field due to the sensed transition and the bias exceeds the coercive field the toroid switches, whereby an output voltage is generated. Upon detection of the output voltage the bias current is reversed in d...