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Browse Prior Art Database

Optical Sensor for Rectangular Marks

IP.com Disclosure Number: IPCOM000076164D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Burke, MJ: AUTHOR

Abstract

Lens body 10 transforms a round light source 11 (about 0.055 inch diameter) into a rectangular spot (about 0.010 by 0.100 inch) to enable the detection of marks on document plane 12 by a phototransistor 13.

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Optical Sensor for Rectangular Marks

Lens body 10 transforms a round light source 11 (about 0.055 inch diameter) into a rectangular spot (about 0.010 by 0.100 inch) to enable the detection of marks on document plane 12 by a phototransistor 13.

Lens body 10 is a bar of transparent plastic having a rectangular cross section. Light-emitting diode 11 is mounted in molded spherical depression 14 which, along with molded spherical protrusion 15, demagnifies the circular spot of light from LED 11 by a factor of about 0.18. Surfaces 16 are formed and treated by conventional methods to minimize internal reflections, in order to preserve the small spot dimension in the direction of arrow 17. The relatively large width of body 10 also minimizes expansion of the spot in the direction 17. On the other hand, the relatively small thickness of body 10 in the direction of arrow 18, and the treatment of surfaces 19 to enhance total internal reflection, cooperate to produce multiple images of LED 11 on document plane 12 in the direction 18. These images fuse to provide a long, narrow bar of light for illuminating rectangular marks on document 12.

One corner 20 of body 10 is cut away to allow transistor 13 to be positioned very close to document plane 12. This eliminates the need for an additional optical system for transmitting reflections to the transistor. Several lens bodies 10, each having its own LED 11 and phototransistor 13, may be mounted in an array for sensing multiple ma...