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Optical Tachometer With Plural Hole Openings

IP.com Disclosure Number: IPCOM000085611D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Garcia, JL: AUTHOR [+3]

Abstract

The device, as depicted schematically in Fig. 1, shows an artwork pattern for a mask or disc of an optical tachometer which results in higher density than prior art designs.

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Optical Tachometer With Plural Hole Openings

The device, as depicted schematically in Fig. 1, shows an artwork pattern for a mask or disc of an optical tachometer which results in higher density than prior art designs.

As shown in Fig. 1, element 10 depicts the transparent window on a conventional optical tachometer mask or disc. Generally, this window has a rectangular shape. With a rectangular-shaped pattern, there is an optimum limit (due to photolithography) beyond which the rectangular windows cannot be made smaller and still maintain the desired light-to-dark ratio. The result is that the density of the tachometer is limited. However, by replacing the rectangular window 10 by a pattern comprised of rows of tangential holes 12, the density of the tachometer is significantly improved and still maintains the desired light-to- dark ratio.

As shown in Fig. 2, the output from photosensors, not shown, of a holed pattern and a nonholed pattern shows that the output from the holed pattern has excellent dark base and light output.

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