Measuring and testing – Vibration – By mechanical waves
Patent
1988-04-28
1990-02-20
Chapman, John
Measuring and testing
Vibration
By mechanical waves
73159, G01B 1702
Patent
active
049015770
ABSTRACT:
The web in a high speed printing press passes between a transmitter and receiver, the former of which produces ultrasonic sound which the latter receives, after attenuation by the web, and the latter of which converts the sound into an oscillating electrical signal of corresponding frequency. This electrical signal, after being amplified and filtered, is impressed upon a peak detector and a comparator. The peak detector produces a constant potential equal to the amplitude of the peaks in the amplified signal, and this constant potential is reduced a predetermined proportion and is applied to the comparator as a reference potential. The comparator compares the reference potential with the amplified oscillating signal. The reference potential remains undisturbed even though the oscillating signal may momentarily drop due to the further attenuation of the sound caused by a splice moving through it. The comparator produces an oscillating signal when the peaks of the amplified signal rise above the reference potential, but when the peaks of the amplified signal drop below the reference potential as a result of further attenuation by a splice, the comparator creates a discontinuity in its oscillating signal. This discontinuity is detected and is utilized to trigger a marking device for imparting a suitable mark to the web both before and after the splice.
REFERENCES:
patent: 3519222 (1970-07-01), Nash et al.
patent: 4117732 (1978-10-01), Brazhnikov
patent: 4446735 (1984-05-01), Weilacher
patent: 4519249 (1985-05-01), Hunt
Chapman John
World Color Press, Inc.
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