On a web press, an auxiliary electronic device which automatically controls the register of printed images with respect to the web cutoff point, or the point ay which the web is cut into signatures. Without a cutoff register control device, the colors or images may be in register with respect to each other, but the entire image may vary from page to page or signature to signature. Such devices usually use photoelectric detectors which, in combination with a signal directed by the printing unit, measure and keep consistent the interval between impressions.
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