Copy sheet distinguishing device for rotary offset printing machines

Claim 1

In a rotary offset printing machine of the type comprising: a. a master cylinder on which a master plate is adapted to be mounted; b. a master plate feed device for mounting a master plate on the master cylinder; c. an etching device for applying an etching solution to the master plate mounted on the master cylinder; d. an inking device for applying ink to the master plate mounted on the master cylinder; e. a blanket cylinder on which an ink image of the master plate mounted on the master cylinder is adapted to be formed; f. a copy sheet feed device for feeding copy sheets; g. an impression cylinder for bringing each of the copy sheets fed into pressing engagement with the blanket cylinder to transfer the ink image from the blanket cylinder to the copy sheets to print the latter from the master plate mounted on the master cylinder; h. means for piling printed copy sheets in a stack on a printed copy sheet tray; i. a cleaning device for supplying a cleaning solution to the blanket cylinder for cleaning the same and removing the ink image therefrom each time duplication of a predetermined number of copy sheets from the master plate mounted on the master cylinder is completed; and j. a start switch adapted to actuate said copy sheet feed device; the improvement comprising a copy sheet distinguishing device comprising: k. a first pulse generator for producing a signal pulse indicative of the feeding of a copy sheet by said copy sheet feed device onto said impression cylinder; l. a second pulse generator for producing a signal pulse indicative of each revolution of said blanket cylinder; m. a counter circuit for receiving and counting the number of pulses produced concurrently by said pulse generators and for producing an output signal when a predetermined number of pulses are counted; n. a judging circuit for receiving the output signal from said counter circuit indicating when a predetermined number of pulses has been counted and for producing a plurality of output signals in response thereto, one of which signals deactivates said copy sheet feed device and one of which signals activates said cleaning device; o. timer means adapted to operate for a predetermined time interval upon receipt of an output signal from said judging circuit and for thereafter providing a plurality of output signals, one of which deactivates said cleaning device; p. a copy sheet marker logic control circuit responsive to an output signal from said timer means for producing signal pulses for actuating the copy sheet feed device to feed a predetermined number of additional copy sheets to the impression cylinder and the blanket cylinder to clean the latter; q. means for then placing the copy sheets used for cleaning on the uppermost sheet of the stack of printed copy sheets on the printed copy sheet tray each time a predetermined number of copy sheets have been printed from the master plate mounted on the master cylinder whereby the copy sheets used for cleaning can serve as printed copy sheet markers; and r. counting means responsive to the signal pulse from said second pulse generator and said copy sheet marker logic control circuit for deactivating said copy sheet feed device after the predetermined number of additional copy sheets have been fed to the blanket cylinder.