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Optical Shaft Encoder

IP.com Disclosure Number: IPCOM000074562D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Davies, PJ: AUTHOR

Abstract

The drawing shows an encoder for a rotatable shaft 2, having the encoder components mounted independently of the shaft, so that the shaft has particularly low inertia. A light source is mounted on a stationary support to illuminate the end of shaft 2. The shaft includes a fiber-optic bundle 3 that conducts light from the end of the shaft to openings along the side of the shaft and toward coded openings 5 in a cylindrical stationary support 6 that surrounds the shaft. Fiber-optics, not shown, are located in openings 5 of support 6 to conduct the light to detectors and associated circuitry. As the shaft rotates, the pattern of light in openings 5 signifies the shaft position.

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Optical Shaft Encoder

The drawing shows an encoder for a rotatable shaft 2, having the encoder components mounted independently of the shaft, so that the shaft has particularly low inertia. A light source is mounted on a stationary support to illuminate the end of shaft 2. The shaft includes a fiber-optic bundle 3 that conducts light from the end of the shaft to openings along the side of the shaft and toward coded openings 5 in a cylindrical stationary support 6 that surrounds the shaft. Fiber-optics, not shown, are located in openings 5 of support 6 to conduct the light to detectors and associated circuitry. As the shaft rotates, the pattern of light in openings 5 signifies the shaft position.

For counting multiple turns, a portion 9 of shaft 2 is threaded to carry a nut
10. A stationary shaft 11 holds nut 10 from rotating so that it travels axially along the shaft as the shaft turns. Nut 10 includes a mirror 12 that directs light to fiber- optics, not shown, located in a second set of coded holes 13 in support 6. During a revolution of shaft 2, nut 10 advances the reflected light beam from one opening to the next.

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