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Browse Prior Art Database

Fine Position Transducer

IP.com Disclosure Number: IPCOM000093659D
Original Publication Date: 1966-Jan-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Hertrich, FR: AUTHOR

Abstract

This position transducer is used for detecting coarse and fine position of a movable member, such as an access arm in a disk memory.

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Fine Position Transducer

This position transducer is used for detecting coarse and fine position of a movable member, such as an access arm in a disk memory.

Rack 1 is attached to movable member 2. Permanent magnet 4 is attached to fixed member 3. Pole piece 5 and small flexible beam 6 are attached to the opposite poles of magnet 4. Pole piece 5 carries magnetic flux from magnet 4 to the teeth of rack 1. The magnetic circuit is completed through a flexible beam 6. Two strain gauges 7 are mounted on the sides of the flexible beam 6 and are connected as two sides of a bridge circuit.

At any given position of member 2, magnetic forces act upon beam 6 to align it with the point of the nearest rack 1 tooth. The deflection of beam 6 stresses strain gauges 7 so as to unbalance the bridge. A very sharp null in bridge output occurs when beam 6 is aligned with a rack 1 tooth in a vertical undeflected condition. The null and the opposite polarity bridge unbalance which occurs in two directions away from the null provide a way of detecting fine position of the movable member. The coarse position is detected by counting the number of null crossings as the rack 1 teeth move past beam 6.

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