Paper Feed Control Mechanism - Ricoh LDD280 Service Manual

PAPER FEED

6.8.5 PAPER FEED CONTROL MECHANISM

Registration Roller
[B]
[C]
[A]
C262D077.WMF
The paper feed timing around the registration roller [A] is monitored by two different
photo-sensors. The first is the paper registration sensor [C], which is located before
the registration roller. The second sensor is the paper feed timing sensor [B], which
is located after the registration roller.
The paper registration sensor [C] detects the paper arriving at the registration roller.
The paper feed motor start timing is determined by this sensor. When the paper
comes into contact with the rollers, the motor remains stopped to create a buckle in
the paper to obtain precise paper registration and to prevent paper skew. The
motor starts turning a pre-determined period after the sensor is activated by the
paper. The sensor is also used to detect jams.
Paper Slip Correction
The paper feed timing sensor [B] is also used to detect paper jams. It is also used
to compensate for delays in paper feed caused by slippage at the registration roller.
The CPU monitors the paper feed timing sensor after the registration motor starts
turning. If the sensor turns on late, the CPU determines that there has been
slippage at the registration roller. Depending on the size of the delay, the
registration motor speeds up to recover the delay.
Feed Speed Correction
The speed of the pressure cylinder rotation depends on the speed of printing. The
paper is fed 1.4 times faster than the pressure cylinder rotation. When the paper
clamper is closing, the paper catches up with the pressure cylinder, and slows
down to the same speed as the pressure cylinder.
C262/C265 6-86 SM