Travelling gap method of detection null

摘要

PROBLEM TO BE SOLVED: To detect that there is running shift when the detection signal generating points of time of two sensors provided at the point on a paper feed route and the predetermined position corresponding thereto and set along the outer periphery of a plate cylinder do not coincide with each other or exceed a tolerance range as the result of comparison. SOLUTION: A detection sensor S1' is provided at a position separated by (A+L) from a printing processing position to the upstream side of the running route of a sheet S and a detection sensor S1 capable of detecting the point P to be detected provided on a plate cylinder 8 when the point P passes the position separated by (A+L) from the printing processing position along the peripheral surface of the plate cylinder 8 is provided on the side of the plate cylinder 8. A counter 22 outputs a counter signal as ϕAB from the faster signal among the signal detected by the detection sensor S1' and the signal detected by the detection sensor S1. A comparison part 23 receives the counter signal ϕAB. from the counter 22 to compare the same with a reference signal FAB. When the counter signal ϕAB exceeds the reference signal FAB, a shift detection signal is sent to display the presence of running shift on a display device 25.