5-8
Phaser 440 Color Printer
5
Theory of Operation
Paper path in operation
This topic discusses the movement of a piece of paper from the paper tray,
through the printing process, to the printer's output tray.
Paper pick-up
Paper pick-up takes place at the paper-feed unit. It begins when the pick-up
solenoid energizes and the paper-feed motor rotates forward. This causes the
pick-up roller (gear-driven by the paper-feed motor through a one-way clutch)
to force a sheet of paper from the tray to the feed rollers. The pick-up solenoid
allows the pick-up roller to rotate only long enough to force the paper into the
feed rollers. The pick-up solenoid then de-energizes so that the pick-up rollers
are disengaged from the gear train. The feed motor continues to rotate forward,
causing the feed rollers (also gear-driven by the paper-feed motor) to carry the
sheet of paper to the aligning rollers. As the paper passes through the
paper-feed unit, it triggers paper-pass sensor 1 which checks to see if the paper
made it to the aligning rollers.
Note that the action of the feed rollers forcing a sheet of paper into the aligning
rollers aligns the sheet of paper to the paper path. There is a slight pause
between the time the paper strikes the aligning rollers (resulting in a slight
buckle in the paper, at which time the alignment takes place) and when the
aligning roller solenoid is energized, which allows the aligning rollers to rotate
and drive the paper to the paper clamp.
Also note that, although unrelated to the paper pick-up process, the drum
rotates backward (counterclockwise) against a pair of stops that force the clamp
open to receive and clamp the leading edge of the paper when it reaches the
drum.
Lower Tray Assembly.
Picking paper in a manner identical to the printer's
paper-feed unit, the Lower Tray Assembly's front door routes the sheet of paper
to the feed roller in the paper-feed unit.