Browse Prior Art Database

Magnetoresistive Contact Less Switch

IP.com Disclosure Number: IPCOM000090915D
Original Publication Date: 1969-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Mcdowell, JJ: AUTHOR [+3]

Abstract

The phenomenon of magnetoresistivity is utilized to eliminate contacts in switches for keyboards. This phenomenon differs from the Hall effect in that a longitudinal voltage is generated rather than a transverse voltage. Thus, this device has the advantage of eliminating the two transverse electrical contacts required in a device operating according to the Hall effect.

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Magnetoresistive Contact Less Switch

The phenomenon of magnetoresistivity is utilized to eliminate contacts in switches for keyboards. This phenomenon differs from the Hall effect in that a longitudinal voltage is generated rather than a transverse voltage. Thus, this device has the advantage of eliminating the two transverse electrical contacts required in a device operating according to the Hall effect.

In this switch, a magnetic field is brought within the vicinity of a current carrying semiconductor. A longitudinal electromotive force is established which is related to the mobility of the semiconductor, the strength of the magnetic field, and the magnitude of the current. As the velocity of the current through the semiconductor is a distribution of velocities, the presence of a magnetic field and the associated Lorentz force affects the components of the velocity in direct relationship to their magnitude causing the magnetoresistive phenomenon to occur. A net ohmic drop occurs in the direction of current flow which is reflected in the circuit formed of the semiconductor.

Plastic housing 1 carries force displacement transducer 2 having key top 3 mounted on top of it. Semiconductor module 4 is seated within housing 1 and, through pin connections 5, makes contact with the wiring pattern on etched board
6. Also contained within housing 1 is plunger 7 positioned to ride within grooves
8. Plunger 7 has permanent magnet 9 fixed to it. When key top 3 is depressed, ma...