Print Process In Operation; Printhead Tilt - Tektronix Phaser 340 Service Manual

5
Theory of Operation

Print process in operation

5-18 Phaser 340 Color Printer
Once a PostScript image has been processed and a printing bitmap created, a
print cycle begins. The printhead and drum are brought up to their operating
temperatures and the ink levels in the ink reservoir are checked and ink is added
from the ink loader, if necessary. Next, the printhead is driven horizontally to its
home position and the drum is rotated to its home position.
Warning Keep your fingers away from the process gear drive system; it uses
a closed-loop drive system. A closed-loop servo drive system is
inherently dangerous. Since the motor speeds up if it senses the
process gears drive system slowing down, fingers caught in the
process belts and gears can be severely injured.

Printhead tilt

The printhead is tilted forward into its print position. The process motor is
activated, which drives the process drive belt. The belt, in turn, drives a one
way clutch compound gear (clutched for this counter-clockwise direction of
rotation). Through a pair of follower gears, the compound gear drives the head
tilt cam gear clockwise. A cam follower, mounted on the lower end of the head
tilt arm, follows a groove in the rotating cam gear, which tilts the printhead. The
cam gear rotates until a set of missing teeth in the cam gear "disengages" it from
the cam drive gear. The head tilt solenoid latches the head tilt cam gear in this
position. At this point, the printhead is in its upright print position (home
position). (The head tilt cam gear is principally rotated in a clockwise direction
to tilt the printhead forward and back. It only rotates counterclockwise during
some printhead cleaning operations.)
Tilted forward, the missing teeth of the head tilt cam gear allow the process
motor and gear train to perform other print functions without affecting the
printhead's tilt position. The head tilt solenoid must be energized to allow the
head tilt cam gear (with a slight spring assist) to advance forward enough to
engage its drive gear and tilt the printhead back.