Media Tray Assembly; Detection Of Media Size; Media Feed Unit Assembly; Media Feed Lift Motor - Lexmark W850n Service Manual

4024-110

Media tray assembly

Rear media tray guide
Bottom plate

Detection of media size

The media size set for the media tray assembly is transmitted to the switch (media size) by moving these guides.
The media size is detected by the on/off information of these switches.

Media feed unit assembly

Since tray 1 and tray 2 are functionally equivalent in terms of the switch (media size), sensor (media out),
sensor (media level) and sensor (pre-feed), only the components of one tray are described here.
The media feed unit assembly is a mechanical unit supplying media from the media tray assembly to the printer.
The driving force, from the media feed lift motor on the media feed unit assembly, is transmitted to the three
media feed rolls to feed media.
When the pick roll picks up media, the remaining media decreases, and the actuator of the
sensor (media level) lowers accordingly. When the sensor (media level) detects the lowering, the media feed lift
motor is activated to lift the lift up shaft and the bottom plate accordingly. Thus, the remaining media is ready to
be fed.

Media feed lift motor

This motor is activated to feed media and to lift the bottom plate. When feeding media, it rotates forward to drive
the pick roll. When lifting the bottom plate, it rotates reversely to drive the tray module gears to lift the lift up shaft.

Switch (media size)

This switch (media size) sets the size of media supplied from each media tray assembly. A signal indicating the
media size is transmitted as a voltage to the printer engine card assembly.

Sensor (media out)

If media runs out in a media tray assembly, the actuator lowers and the actuator flag, unlocks the sensing area of
the sensor (media out). The sensor light is transmitted. When the sensing area is blocked (media is present), the
signal is off.
3-32
Options Service Manual
Media end guide
Front media tray guide assembly