Browse Prior Art Database

Total Angle and Center Angle Encoder Scheme

IP.com Disclosure Number: IPCOM000084761D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Holdaway, DO: AUTHOR [+2]

Abstract

The device, as depicted schematically in the figures, shows an encoder which determines a total angular segment (beta) and the center portion of the segment.

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Total Angle and Center Angle Encoder Scheme

The device, as depicted schematically in the figures, shows an encoder which determines a total angular segment (beta) and the center portion of the segment.

The device is comprised of a conventional encoder disc 10 with a unique pattern 12 positioned on the periphery of the disc. Although only one pattern is shown, a plurality of other patterns may also be positioned on disc 10. Mask 14 is positioned relative to disc 10. Patterns or masked windows 16 and 18 are positioned on mask 14. Conventional light sources 20 and 22 are positioned relative to disc 10. Light photosensors 24 and 26 are positioned to be in optical alignment with light sources 20 and 22.

In operation, the disc 10 rotates in the direction shown by arrow 28. As the leading edge of pattern 12 approaches line 30, photosensor 26 begins to conduct. The output from photosensor 26 is equivalent to curve A in Fig. 2. Photosensor 26 will conduct until the trailing edge of pattern 12 passes line 30.

Simultaneously, as leading edge of pattern 12 approaches line 32, photoconductor 24 begins to conduct. Photoconductor 24 will conduct until the trailing edge of pattern 12 passes line 32. The output from photosensor 24 is equivalent to curve B. By logical addition of curve A and curve B, curve C is obtained with pulse theta defining the center of angle beta.

The angular segments are determined by the following:

The total angular segment is the length of disk window 12...