Browse Prior Art Database

Optical Sensor

IP.com Disclosure Number: IPCOM000076165D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Burke, MJ: AUTHOR

Abstract

The purpose of optical sensor 10 is to provide an indication of the position of a moving body, such as a scan head or the like. Light-emitting diode 11 and lens 12 are carried on the moving scan head (not shown), and provide a small spot of light to phototransistor 13 when the scan head reaches a predetermined position. In one form, several phototransistors 13 are positioned along the path of the scan head to provide unique output signals for a number of locations of the scan head. In another form, a single transistor 13 is mounted on the scan head along with LED 11 and lens 12. Fixed transparent bar 14 is then provided with apertures 15 on an opaque mask 16, so that transistor 13 produces an output whenever the scan head reaches one of the apertures 15.

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Optical Sensor

The purpose of optical sensor 10 is to provide an indication of the position of a moving body, such as a scan head or the like. Light-emitting diode 11 and lens 12 are carried on the moving scan head (not shown), and provide a small spot of light to phototransistor 13 when the scan head reaches a predetermined position. In one form, several phototransistors 13 are positioned along the path of the scan head to provide unique output signals for a number of locations of the scan head. In another form, a single transistor 13 is mounted on the scan head along with LED 11 and lens 12. Fixed transparent bar 14 is then provided with apertures 15 on an opaque mask 16, so that transistor 13 produces an output whenever the scan head reaches one of the apertures 15.

Lens 12 images LED 11 into a spot about 0.01 inch in diameter. Lens 12 is formed of a cylindrical body of transparent plastic. Molded spherical depression 17 and spherical protrusion 18 provide the required focussing. The radius of protrusion 18 is preferably somewhat larger than that of depression 17. Circumferential groove 19 near the center of lens 12 prevents reflections off of sidewall 20 from forming multiple images of LED 11.

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