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Browse Prior Art Database

Magnetically Encoded Keyboard

IP.com Disclosure Number: IPCOM000078826D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Johnson, PM: AUTHOR

Abstract

The figure illustrates a magnetic key and sensor for use in producing encoded electrical outputs, which signify the depression of a given keg and produce an encoded character for that key.

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Magnetically Encoded Keyboard

The figure illustrates a magnetic key and sensor for use in producing encoded electrical outputs, which signify the depression of a given keg and produce an encoded character for that key.

The key stem 1 is made hollow and carries, either on an interior surface as shown, or on its exterior surface, a magnetic strip 2 which is encoded with the character information to be depicted on the key top. A spring 3 rigidly mounted at a base, carries a magnetoresistive semiconductor sensor 4 in intimate contact with the magnetic strip 2. The electrical leads 5 from magnetoresistive device 4 carry the signals picked up by 4, whenever the key is depressed and when it is released. Spring 3 should maintain a force of approximately 5 to 10 grams against the face of the key, which carries magnetic strip 2 to ensure accurate reading. Such forces do not cause significant wear of the sensor or of the strip.

Suitable electronic means such as a buffer may be attached to electrical leads 5, to receive the signals during the depression of the key and the release thereof. Inasmuch as the sensor reads when the key is depressed and when it is released, an inherent checking for full depression of the key can be made, by simply reversing either the down stroke or the up stroke read signals and comparing them with the opposite stroke signals. This device simplifies any keyboard changes, since the code for a given key is carried by the key itself. Merely interchan...