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Measuring Recorded Bit Location

IP.com Disclosure Number: IPCOM000073801D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Francis, W: AUTHOR

Abstract

This is an apparatus for measuring the distance X between recorded magnetic bits in a magnetic medium, such as magnetic tape or a magnetic stripe 12 on a credit card 10 or the like. An astable multivibrator including coils 70 and 72 alternately excites magnetic pole pieces 60 and 62. The magnetic fields produced by the pole pieces excite pendulum 50, mounted to the base 44 at pivot 40. Base 40 is attached to the dovetail mount 80 of a toolmakers microscope. By subjecting pendulum 50 to fields of sufficient power, a repeatable pattern of movement is achieved, which vibrates magnetic read head 20 over the stripe 12 on card 10. Card 10 is mounted to an X-Y table, not shown, and adjusted so the stripe 12 is directly under head 20.

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Measuring Recorded Bit Location

This is an apparatus for measuring the distance X between recorded magnetic bits in a magnetic medium, such as magnetic tape or a magnetic stripe 12 on a credit card 10 or the like. An astable multivibrator including coils 70 and 72 alternately excites magnetic pole pieces 60 and 62. The magnetic fields produced by the pole pieces excite pendulum 50, mounted to the base 44 at pivot 40. Base 40 is attached to the dovetail mount 80 of a toolmakers microscope. By subjecting pendulum 50 to fields of sufficient power, a repeatable pattern of movement is achieved, which vibrates magnetic read head 20 over the stripe 12 on card 10. Card 10 is mounted to an X-Y table, not shown, and adjusted so the stripe 12 is directly under head 20. Head 20 is mounted to pendulum 50 by aligning mount 30 which can be rotated so that the read gap of head 20 is aligned to the angle at which the bits were recorded in stripe 12.

As head 20 is vibrated over stripe 12 the output, which is monitored by an oscilloscope, will display a pulse. The magnetic stripe is positioned so that maximum amplitude is obtained. The X-Y table is then moved to the next location of maximum amplitude, the bit spacing X being the distance moved.

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