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Optical Switching Using Light Pipes

IP.com Disclosure Number: IPCOM000096195D
Original Publication Date: 1963-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Dersch, WC: AUTHOR

Abstract

This device is a light pipe memory interrogator. Recorded bits,for instance dots on a disc, are selectively interrogated according to the reflectivity conditions at that point. The light pipe, positioned over the bit, is selectively illuminated by a light source. A reflected-light signal is received or not (binary information) according to whether a dot has sufficient reflectance to reflect the light back along the pipe to a sensor. This surface can also be a touchplate surface on a keyboard. This is rendered reflective (or not) according to the position of the operator's finger over it. In either case, the reflective state of a surface switches a light transducer.

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Optical Switching Using Light Pipes

This device is a light pipe memory interrogator. Recorded bits,for instance dots on a disc, are selectively interrogated according to the reflectivity conditions at that point. The light pipe, positioned over the bit, is selectively illuminated by a light source. A reflected-light signal is received or not (binary information) according to whether a dot has sufficient reflectance to reflect the light back along the pipe to a sensor. This surface can also be a touchplate surface on a keyboard. This is rendered reflective (or not) according to the position of the operator's finger over it. In either case, the reflective state of a surface switches a light transducer.

In the large drawing, the light pipe interrogator has forked, double ended light pipes which are joined in bundles B. Bundles B comprise 1000 light pipes each in this case, as shown in bundles B(1)... B(6). The input ends of each of these light pipes are gathered at one point, as are the output ends. Thus, any given bundle B can be selectively interrogated by a light source such as LS(1)...LS(5) the reflection (or not) of which being sensed at a photomultiplier tube output PMT. PMT is positioned at a common output station where all the output ends of all the bundles o light pipes merge into light-funnel LF.

The medium interrogated is a storage disc D with 6000 information tracks upon it (one track for each pipe). Disc D stores information in binary according to the presence or absence of a given reflectivity, e. g., polished or not, at bit spots. Any variable-reflectivity surface can constitute the medium. Selective interrogation is effected by positioning servos PS. PS(1) and P...