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Browse Prior Art Database

Optical Mark Read System

IP.com Disclosure Number: IPCOM000079187D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Estry, RH: AUTHOR [+4]

Abstract

This Optical Mark Read System is a high-density, high-performance modular mark read configuration. The head reads in parallel up to forty positions of mark read data with a density of five marks per inch (0.20O in. channel spacing).

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Optical Mark Read System

This Optical Mark Read System is a high-density, high-performance modular mark read configuration. The head reads in parallel up to forty positions of mark read data with a density of five marks per inch (0.20O in. channel spacing).

Light from an incandescent source is transmitted to the document via multichannel fiber optics distribution modules. Light exiting from a fiber-optic channel passes through a collimator channel, illuminating a small rectangular area on the document. A portion of the light striking the document is reflected and impinges on a photodetector, mounted above the document.

The fiber optics light distribution module, Fig. 1, consists of fourteen channels of fiber optics, which supplies light to the appropriate areas of the document. The complete read system requires three modules for a total of forty-data channels plus two timing-track channels.

The light collimator is shown in cross-section in Fig. 2. This unit performs the dual function of providing a mounting base on which the fiber optics and phototransistor cards are mounted, and produces collimation of the light to improve performance. As the gap between the document and read head changes, the resolution remains nearly constant.

The coaxial transistors 1 are mounted in notches cut in the edge of a printed- circuit paddle card 2. A fiat-ribbon cable 3 provides the connection between the paddle card and logic board 4. This method of mounting the phototransistors, along with the high resolution provided by the collimation, eliminates the need for any fiber optics between the document and photodetector. The fourteen phototransistors in a paddle card assembly are matched into one of five categories, according to their linearity factor. A jumper placed on the paddle card selects one of five lines in the flat ribbon cable 3. The line selected pr...