发明名称 Apparatus for detecting splices in the web of a printing press
摘要 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.
申请公布号 US4901577(A) 申请公布日期 1990.02.20
申请号 US19880187339 申请日期 1988.04.28
申请人 WORLD COLOR PRESS, INC. 发明人 ROBERTS, CHRISTOPHER C.
分类号 B41F33/02;B41F33/06;B41F33/18;B65H26/02;G01B17/02;G01N29/11 主分类号 B41F33/02
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