Print Process In Operation; Printhead Tilt - Tektronix Phaser 380 Service Manual

5
Theory of Operation

Print process in operation

5-20 Phaser 380 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; 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
compound gear. 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 inside surface of the rotating cam gear,
tilting 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.)
With the printhead 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. To tilt the printhead back, the head tilt
solenoid is energized to allow the head tilt cam gear (with a slight spring assist)
to advance enough to engage its drive gear.