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Digital Speed Checking Circuit

IP.com Disclosure Number: IPCOM000079195D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Dumstorff, EF: AUTHOR [+4]

Abstract

Rotating element 10 has permanent indicating means 11 on its periphery to indicate a complete revolution. Sensing device 12 detects the indicating means 11, and each revolution of the rotating element 11 sends a signal to circuit block 14 for amplifying and shaping, whereupon circuit block 14 provides a home pulse 17 over line 15. Home pulse 17 resets counter 20 through OR switch 21. Counter 20 is incremented by clock pulses over line 22 at a frequency very much greater then the period of the rotating element 10.

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Digital Speed Checking Circuit

Rotating element 10 has permanent indicating means 11 on its periphery to indicate a complete revolution. Sensing device 12 detects the indicating means 11, and each revolution of the rotating element 11 sends a signal to circuit block 14 for amplifying and shaping, whereupon circuit block 14 provides a home pulse 17 over line 15. Home pulse 17 resets counter 20 through OR switch 21. Counter 20 is incremented by clock pulses over line 22 at a frequency very much greater then the period of the rotating element 10.

Outputs T1, T2 and T3, taken from counter 20 provide the necessary timing pulses for operation of the circuit. T2 defines the minimum acceptable time for one revolution and T3 defines the maximum acceptable time for one revolution. At time T1, after the home pulse has dissipated, latch 30 will be conditioned to permit the next home pulse 17 to pass through and reset latch 40. This will occur if rotating element 10 is rotating too fast. If no home pulse 17 arrives before time T2, latch 30 will be conditioned to block home pulse 17 and latch 35 will be conditioned to pass it through to set latch 40, if rotating element 10 is rotating within the required tolerance (T2 period T3). If no home pulse 17 arrives by time T3, the rotating element 10 is rotating too slow and both latch 40 and counter 20 will be reset.

If the element 10 has been removed, sensing element 12 continues to condition latch 30 which holds latch 40 reset thus...