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IP.com Disclosure Number: IPCOM000092291D
Original Publication Date: 1968-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Brue, BM: AUTHOR [+3]

Abstract

A variable reluctance read sensing mechanism has a series of read fingers 10. These confront a magnet pickup assembly including magnet pole 11 and surrounding coil 21 confronting each read finger 10. During passage of a punched card traveling in the direction of arrow A, the card thickness normally separates sensing fingers 10 and pole 11. When a hole appears finger 10 drops toward the confronting pole causing a change of flux in the magnetic field and the generation of a voltage pulse from coil 12. If foreign particles are present or the hole is not properly oriented, finger 10 may not drop sufficiently to generate a read pulse, thus causing an error. Finger 10 is longitudinally split into three distinct elements only one of which need fall toward pole 11 to generate a read signal.

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Read Head

A variable reluctance read sensing mechanism has a series of read fingers
10. These confront a magnet pickup assembly including magnet pole 11 and surrounding coil 21 confronting each read finger 10. During passage of a punched card traveling in the direction of arrow A, the card thickness normally separates sensing fingers 10 and pole 11. When a hole appears finger 10 drops toward the confronting pole causing a change of flux in the magnetic field and the generation of a voltage pulse from coil 12. If foreign particles are present or the hole is not properly oriented, finger 10 may not drop sufficiently to generate a read pulse, thus causing an error. Finger 10 is longitudinally split into three distinct elements only one of which need fall toward pole 11 to generate a read signal. To avoid any problem which might occur as a result of sequential operation of various elements of the same finger 10 during passage of a single punched hole, the output from each coil 12 is inhibited for a predetermined length of time following each read signal.

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