| 摘要 |
<p>PURPOSE:To detect the duplex fed paper regardless of the size of the displacement between both tips and the presence or not of printed pictures by detecting the duplex feeding by means of leading edges of transmitted waveforms and the transit time of the paper passing through a projector section on a conveyance passage of a copying machine, etc. CONSTITUTION:When the duplex fed paper P with both paper tips aligned are passed, photoelectric element PT signals go into comparators 9, 10, giving an output signal H, and an AND circuit 15 gives an output signal H as long as the output signal of a differential circuit 16 is kept H as long as the output signal of a differential circuit 16 is kept H. On the other hand, an L sigal from a timer T1 is fed into an AND circuit 18 of the second duplex feed detection circuit 6, therefore no H signal is output from it. Next, when the duplex fed paper with both paper tips displaced are passed, an H signal is output from the comparator 10 while the paper are passing and actuates the timer T1, giving an H signal output from the AND circuit 18. On the other hand, no H signal is output from the AND circuit 15 of the first duplex feed detection circuit 5. Then, H signals from the circuits 5, 6 are fed into an OR circuit 35 of an exhaust circuit 7, actuating a timer T2 to energize a solenoid 32 for a predetermined time, and the duplex fed paper P are exhausted.</p> |
