Browse Prior Art Database

Rotary Tachometer Encoder

IP.com Disclosure Number: IPCOM000084962D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Clark, GA: AUTHOR

Abstract

The device, as depicted schematically in the figures, outputs a plurality of controlled switch closures per shaft revolution. The device comprises a magnetized wheel 10 (see Fig. 1), ferromagnetic backing disc 12 and a conventional reed switch 16.

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Rotary Tachometer Encoder

The device, as depicted schematically in the figures, outputs a plurality of controlled switch closures per shaft revolution. The device comprises a magnetized wheel 10 (see Fig. 1), ferromagnetic backing disc 12 and a conventional reed switch 16.

Magnetized wheel 10 is comprised of flexible permanent magnet material 14. Magnetic material 14 is selectively magnetized according to any desired pattern. For example, in Fig. 1 the disc is divided into an even number of pie-shaped sector magnetic poles. The direction of magnetization is perpendicular to the faces of the disc 12. Ferromagnetic steel backup disc 12 is attached to one face of the magnetic material 14, thereby increasing the magnetic field intensity on the opposite side.

In operation, wheel 10 is attached to rotating shaft 20 whose rotation is to be monitored. Sensitive reed switch 16 is rigidly mounted in spaced relationship with wheel 10. As the wheel rotates, the reed switch 16 is opened and closed by the resultant alternating magnetic field, thereby generating one switch closure per revolution per magnetic pole on the wheel 10. The number of switch closures from reed switch 16 are equivalent to the number of divisions of magnetic material 14.

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