Canon LBP1760P, Service Manual

Page: 111 / 394

3. Duplexing unit pick-up
When the /PRNT signal is sent to the engine controller from the video controller, the main motor
(M1) of the printer starts rotation. When the main motor rotation reaches its prescribed speed,
the engine controller turns ON the feed roller clutch (CL101) of the printer and sends the duplex-
ing unit pick-up command to the duplexing unit driver.
When the duplexing unit driver receives the duplexing unit pick-up command from the print-
er, it rotates the duplex feed motor (M702) in the reverse direction (CCW) to feed the paper from
the duplexing unit pick-up wait position to the pre-feeder sensor (PS102) of the printer at the
same speed as the print speed of the printer.
The engine controller detects the conditions of the PS102 for a prescribed period of time after
the duplexing unit pick-up starts. If the PS102 does not detect no paper within the prescribed
period of time, the engine controller turns OFF the feed roller clutch (CL101) and sends the feed
stop command to the duplexing unit driver to stop feeding the paper in the prescribed period of
time after the top of page sensor (PS103) detects the paper present condition of the preceding
paper. When the top of page sensor (PS103) detects the trailing edge of the preceding paper, the
CPU resumes feeding the stopped paper. By this, the between-page distance appropriate for the
continuous printing is achieved.
The paper then reaches the registration arm where its skew is corrected, goes through trans-
fer, separation, fixing and delivery unit and is delivered to the tray.
• Duplexing unit pick-up timing
Figure 2-9-5
2 - 73
CHAPTER 2
/PRNT signal
Main motor (M1)
Feed roller clutch (CL101)
Duplex pick-up command
Feed stop command
Duplexing unit pick-up sensor (PS701)
Duplex feed motor (M702)
Pre-feed sensor (PS102)
(Unit: second)
STBY INTR PRINT
About 0.7
CCW CCW