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Optical Position Sensing Device

IP.com Disclosure Number: IPCOM000092201D
Original Publication Date: 1968-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Hayes, LP: AUTHOR

Abstract

In order to overcome detector drift and variation in light sources, light from a common source is optically split into multiple beams, directed via mirrors at the object edges, and recombined to register on a single photodetector. Light rays from single light source 1 are separated by beam splitter 2 into two beams 3 and 4. The latter is directed by mirror 5 in a direction parallel with beam 3. Light chopper 6 alternately gates the beams to produce intermittent pulses, thus enabling a comparison of the light quantities passing opposite edges of object 8 being positioned. The light pulses are combined by mirror 9 and beam splitter 10 which direct the light to single photoresistor 11. The amplified output from the detector is fed to a null circuit via switch 12 which is synchronized with the light chopper as indicated by 7.

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Optical Position Sensing Device

In order to overcome detector drift and variation in light sources, light from a common source is optically split into multiple beams, directed via mirrors at the object edges, and recombined to register on a single photodetector. Light rays from single light source 1 are separated by beam splitter 2 into two beams 3 and
4. The latter is directed by mirror 5 in a direction parallel with beam 3. Light chopper 6 alternately gates the beams to produce intermittent pulses, thus enabling a comparison of the light quantities passing opposite edges of object 8 being positioned. The light pulses are combined by mirror 9 and beam splitter 10 which direct the light to single photoresistor 11. The amplified output from the detector is fed to a null circuit via switch 12 which is synchronized with the light chopper as indicated by 7. The output of the detector, assuming the object is positioned as shown, consists of a series of alternate high and low pulses that are indicative of the relative position of the object with respect to the beams.

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