Panasonic UF-E1 Service Manual page 186

UF-E1
6.6.2. Carriage Movement
The carriage is belt driven, using a 3-to-1 gear set for coupling to the motor. The gear set minimizes side-
loading of the motor, because the belt is not attached directly to the motor. The belt is supported and driven
at the left end by the belt gear, and supported at the right end by the idler pulley. The belt is mounted to a
clip that snaps into the back of the carriage.
The top of the carriage travels across the carriage bar on a flat bearing that maintains the tilt of the carriage.
The bearing provides low overall friction with the steel carriage chassis. A sintered bronze bushing impreg-
nated with lubricant provides both low friction levels and environmental stability with changes in tempera-
ture or humidity. Interface oil holds the friction level constant. The oil is a synthetic, low vapor-pressure oil
that is compatible with the plastic parts and resistant to evaporation.
The carriage rocks slightly, as a function of clearance between the carriage rod and the bushing on the bot-
tom of the carriage, as well as the bearing at the top of the carriage. To minimize the impact of carriage
rocking, relative to the encoder system, a mylar encoder strip is positioned closely to the nozzle plate of the
print cartridge. The mylar material is resistant to fingerprints, paper dust, and so forth. It is slightly sensitive
to temperature and humidity, so a flat spring (on the right side of the steel carriage bar) maintains tension on
the encoder strip.
The quadrature optical encoder and a decoupling capacitor are soldered onto the flex circuit on the rear
side of the carriage. The flex circuit comes out through the front side of the carriage, where it splits and
folds over itself in order to travel within the compact carriage path.
The flex circuit carries signals for the encoder system, as well as drive voltage for the print cartridge. Signal
lines for the print cartridge terminate at the flex-circuit contacts on the interconnect pad in the front of the
carriage. These contacts interface with contacts on the back of the print cartridge.
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