Browse Prior Art Database

Optical Card Reader

IP.com Disclosure Number: IPCOM000092897D
Original Publication Date: 1967-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 19K

Publishing Venue

IBM

Related People

Huang, SS: AUTHOR [+2]

Abstract

In order to improve the hole to no-hole light ratio in an optical card reader, filter 1 is placed between card 2 being read and phototransistor 3. Light from lamp 4 is conducted by fiber optic rod 5 that is oriented to emit light towards phototransistor 3. Card 2 is only partially opaque, in that a certain amount of light is transmitted through the card itself. Thus filter 1 is chosen so as to filter out light having the spectral characteristics of the light transmitted through card 2. The light from lamp 4 includes frequencies of a range wider than that of the light transmitted through the card itself. Thus the ratio of the light that passes through a hole in card 2 to that which passes through card 2 is increased by the use of filter 1.

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Optical Card Reader

In order to improve the hole to no-hole light ratio in an optical card reader, filter 1 is placed between card 2 being read and phototransistor 3. Light from lamp 4 is conducted by fiber optic rod 5 that is oriented to emit light towards phototransistor 3. Card 2 is only partially opaque, in that a certain amount of light is transmitted through the card itself. Thus filter 1 is chosen so as to filter out light having the spectral characteristics of the light transmitted through card 2. The light from lamp 4 includes frequencies of a range wider than that of the light transmitted through the card itself. Thus the ratio of the light that passes through a hole in card 2 to that which passes through card 2 is increased by the use of filter 1.

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