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Browse Prior Art Database

Punched Card Reader

IP.com Disclosure Number: IPCOM000098907D
Original Publication Date: 1958-Dec-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Smith, JT: AUTHOR

Abstract

The photo-magneto-electric (PME) effect in semiconductors is utilized to sense perforations in a punched card.

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Punched Card Reader

The photo-magneto-electric (PME) effect in semiconductors is utilized to sense perforations in a punched card.

When a semiconductor is placed in a magnetic field and is illuminated in a direction perpendicular to this field, a voltage is developed across the semiconductor by the PME effect in a direction mutually perpendicular to the direction of illumination and of the magnetic field.

A matrix is formed of a plurality of semiconductor strips corresdonding to the rows of perforations in the punched card. Across each of these strips a plurality of magnetic fields is applied. These are produced by electromagnets spaced along the length of the strip. The electromagnets are serially energized by columns, which correspond to the columns in the punched card. The different intersections of the strips with the magnetic fields correspond to the positions of the perforations in the punched card which overlies the matrix.

Light from the source above the card passes through the card perforations and impinges on the semiconductor strips to generate an output voltage in those strips which also have a magnetic field at the point of light impingement.

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