Oce 3121 Technical & Service Manual page 691

c. Monitoring the position of the trays
The position of the trays is monitored by the microprocessor Q7 on the tray
control PBA. The tray position detection signal (TPD) is emitted by the posi-
tion sensor PI12.
Moving the tray to the rear
I
The microprocessor (Q7) on the tray controller PCB judges that the special
tray has shifted to the rear when the edge of the crescent pulley blocks the
tray position sensor (PI12), i.e., when TPD goes from '0' to '1', and stops the
tray shift motor (M7).
Moving the tray to the front
I
The microprocessor Q7 considers the tray to be in the front position when the
crescent leaves the position sensor PI12. The tray movement motor M7
stops.
tray position
Tray position
sensor PI12
Sensor (PI12)
direction
Direction
of rotation
crescent
Crescent
pulley
pulley
special tray at rear
Special tray at rear
(top view)
(top view)
crescent pulley
Crescent pulley
(makes a 1/2 rota-
(makes a 1/2 rotation for
tion for each shift of
each shift of the tray)
the tray)
ed.1
direction
Direction
of rotation
special tray at rear
Special tray at front
(top view)
(top view)
tray shift motor M7
Tray shift motor
(M7)
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