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Browse Prior Art Database

Synchronized Counter with Redundant Reset

IP.com Disclosure Number: IPCOM000081557D
Original Publication Date: 1974-Jun-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 46K

Publishing Venue

IBM

Related People

Boll, KF: AUTHOR [+2]

Abstract

This counter arrangement insures periodic counter synchronization by selecting a counter modulus equal to the expected number of minor pulses to be received, and additionally providing a redundant synchronizing pulse to the counter's reset input, thereby insuring that counter reset will occur in the event that one or more minor counts does not arrive as expected.

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Synchronized Counter with Redundant Reset

This counter arrangement insures periodic counter synchronization by selecting a counter modulus equal to the expected number of minor pulses to be received, and additionally providing a redundant synchronizing pulse to the counter's reset input, thereby insuring that counter reset will occur in the event that one or more minor counts does not arrive as expected.

In Fig. 1, motor 10 rotates head-wheel 11 at a constant speed, causing one or more magnetic heads to move generally transversely across magnetic recording tape 12. This tape is moved in the direction of arrow 13, either continuously or step-by-step, by a tape moving motor, not shown. A digital tachometer disc or encoder 14 is also driven by motor 10. The outer circumference of disc 14 includes a large number of equally spaced indicia 15, representing the above mentioned minor pulses, which are sensed by sensor 16. One indicia 17, representing the redundant synchronizing pulse, is located radially inward from indicia 15 and is sensed by sensor 18. Sensors 16 and 18 are radially aligned relative to disc 14.

The modulus of counter 19 is selected to be equal to the total number of indicia 15 contained in one revolution of disc 14. Thus, counter 19 will roll-over as indicia 17 moves past sensor 18, if all indicia 15 have been sensed by sensor
16. However, if one or more of indicia 15 have been missed, indicia 17 and sensor 18 insure synchronization of counter 19 for the next revolution of disc 14.

Tape 12 includes one longitudinal track along one edge thereof. This track consists of a large number of equally spaced indicia 20, representing the above- mentioned minor pulses, which are sensed by sensor 21. Indicia 20 may be revers...