Browse Prior Art Database

Head Alignment Check on a Magnetic Card Deck

IP.com Disclosure Number: IPCOM000088788D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Wheeler, DR: AUTHOR

Abstract

The drawings depict a procedure and apparatus which provides a quick and simple way of checking read/write head alignment on a magnetic card.

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Head Alignment Check on a Magnetic Card Deck

The drawings depict a procedure and apparatus which provides a quick and simple way of checking read/write head alignment on a magnetic card.

The operation requires the writing of two magnetic cards in a special way and then reading the cards for misalignment. Fig. 1 shows a normally written magnetic card with 50 tracks. The center line of each track is spaced approximately 0.0625 inches apart.

Fig. 2 depicts the two cards which are needed to perform the alignment tests. On one of the cards (for example, card 1) the tracks are written so that the center lines are placed at an increasing distance to the left of the normal position of the tracks.

On the other card, for example card 2, the tracks are written so that the center lines are positioned at an increasing distance to the right of the normal tracks. When these two cards are read on a typical deck that is in correct alignment or adjustment, the deck will be able to read a predetermined number of tracks without error on each card. If the deck is not in adjustment, the number of tracks that will be read without error will be different on each card depending on the type of misadjustment. For example, if the head is offset to one side, the deck will read more tracks on one card than is normal and less tracks on the other card than normal. If the head is not aligned relative to the card (due-to skew, pitch, roll, etc.), the deck will read less tracks on both cards. Thus, by establishing a pass/fail threshold (that is, the number of tracks read indicating sufficient signal level for...