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Browse Prior Art Database

Checking Circuit

IP.com Disclosure Number: IPCOM000096219D
Original Publication Date: 1963-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Smith, GL: AUTHOR

Abstract

The circuit checks a sequence of electrical signals such as the outputs of optical transducers and indicates when the sequence is incorrect. The proper sequence of pulse signals produced by optical transducers in response to the passage of a document is shown by waveforms P1, P2, P3 and P4.

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Checking Circuit

The circuit checks a sequence of electrical signals such as the outputs of optical transducers and indicates when the sequence is incorrect. The proper sequence of pulse signals produced by optical transducers in response to the passage of a document is shown by waveforms P1, P2, P3 and P4.

The first P1 pulse is applied to single shot (SS) 10. This is responsive to the trailing edge of the input pulse and provides a negative going pulse of predetermined duration at its output. The pulse from SS 10 is inverted by inverter (I) 11 and applied to Or 12.

After passing through a driver (D) 13 having an inherent time delay, the positive pulse from Or 12 sets trigger (T) 14 so that one input of And 15 is at the positive voltage level. The positive pulse from Or 12 is also directly applied to the other input of And 15.

However, And 15 is not energized since the pulse applied directly from Or 12 has disappeared by the time T14 is set.

If the next pulse is P2, then T14 is reset to its original state through a circuit comprising SS16, 117, Or 18, D19 and Or 20. T21 is set at the same time by a signal applied through Or 22 and D23. Signals are taken from Or's 18 and 22 and supplied to the inputs of And's 24 and 25, respectively. These are not energized since T14 has not been reset and T21 has not been set at this time.

When the pulses P1, P2, P3 and P4 occur in proper sequence as shown, T's 14, 21 and 26 are set and reset so that the And's 15, 24, 25, 31, 32...