Paper Feeding And Ejection Mechanism - Brother MFC4820C Service Manual

4.2.2.2

Paper feeding and ejection mechanism

The paper feeding and ejection mechanism is driven by the paper feed motor (DC motor), located
on the rear left side of the engine unit, through the two PF timing belts and a gear train.
The rotational torque of the paper feed motor is transmitted via PF timing belt 135 to the PF roller
pulley. Engaged with the pulley, the paper feed roller rotates. In step 2 of paper feeding (as
described on the previous page), the paper feed roller rotates backwards to register the leading
edge of the paper being pulled in. Next, it reverses the direction of its rotation to feed the paper.
The rotation of the PF roller pulley is also transmitted via PF timing belt 160.5 to idle pulley gear
24/28. Engaged with the idle pulley gear, paper ejection gear 28B rotates so that the paper ejection
roller (urethane-coated) ejects the printed paper.
The idle pulley holder is spring-structured. The idle pulley applies tension to PF timing belt 160.5
and prevents the belt from deviating from its designated path.
On the outer side of the PF roller pulley is a PF encoder disk with a resolution of 300 dpi (0.084
mm pitch). Using this disk, the PF encoder sensor detects the rotational angle or speed of the paper
feed roller so that the controller can control the paper feeding position and speed. The PF encoder
sensor can output signals of two different phases, so the resolution can be a maximum of four
times 300 dpi.
Engine unit
Paper feed roller
Paper feed motor
PF timing belt 135
PF roller pulley
PF encoder disk
Paper ejection roller
PF encoder sensor
PF timing belt 160.5 Paper ejection gear 28B
Idle pulley holder
Idle pulley gear 24/28
(Supporting the idle pulley)
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