Browse Prior Art Database

Multiple Channel Optical Reader

IP.com Disclosure Number: IPCOM000083424D
Original Publication Date: 1975-May-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 57K

Publishing Venue

IBM

Related People

Keller, RJ: AUTHOR [+2]

Abstract

Conventional optical readers for cards, pulse emitters and the like have used one light source and one detector for each sense position, or have used fiber-optic light pipes with a single source or with a single detector.

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Multiple Channel Optical Reader

Conventional optical readers for cards, pulse emitters and the like have used one light source and one detector for each sense position, or have used fiber- optic light pipes with a single source or with a single detector.

Optical reader 10 achieves close channel spacing with relatively large and inexpensive phototransistors, by multiplexing both the light sources and detectors through low-cost transparent plastic blocks. A light-emitting diode (LED) 11 is mounted in leg 12 of Y-shaped plastic block 13.

A light ray from LED 11, indicated by dashed lines 14, is internally reflected from surfaces 15 and 16, then passes through end 17 to one hole position of a card or other medium, not shown, lying perpendicular to the plane of the page and parallel to end 17. Another ray 18 from LED 11 is internally reflected from surfaces 19 and 20 of block 13, and passes through end 21 thereof.

LED's 22 and 23 are mounted in further plastic blocks 24 and 25, respectively. These blocks are laterally offset from and behind block 13. Dashed lines 26 and 27 indicate the rays emanating from block 24, while lines 28 and 29 show the rays from block 25.

Phototransistor 30 fits into transparent plastic block 31, which has molded arms 32, 33 on both sides of flat surface 34. Light ray 14 from LED L1 passes through end 35 of arm 32, and is thence internally reflected from angled surfaces 36 and 37 into phototransistor 30. Ray 26 from LED 22 is transmitted from block 24 through flat surface 34 of block 31 to transistor 30. Ray 28 from LED 23 pass...