Epson Stylus Pro 9500 - Page 47

EPSON Stylus Pro 9500 Revision A
Operating Principles Component List & Illustrations 47
2.1.1.1 Carriage Mechanism
CR GUIDE RAIL
To print on paper as wide as B0 Wide, the printhead carriage must be more
stable and must travel further than the usual carriage. To make the printheads
more stable, EPSON added the CR Guide Rail to the SP 9000.
Every EPSON ink jet printer until now has used a carriage guide shaft to
stabilize the carriage during printing and horizontal movement. SP 9000 does
away with the carriage guide shaft and relies on the printer frame for its
stability.
The CR motor uses a DC motor to move the carriage, and the Linear Encoder
determines the lateral position of the carriage by counting the shaded areas of
the plastic Step Ruler (timing fence). See Figure 2-5 below. The Linear
Encoder reads the shaded stripes to determine the position of the carriage as
well as the carriage speed, and this data is sent to the software servo. To allow
for the extra distance the carriage must travel during printing, the rubber timing
belt has been changed to a belt made from steel.
The following sensors are used in combination with the CR Guide Rail
components:
o HP Sensor
This optical sensor activates when the CR Guide Rail flag (flag) enters the
space between the light emitter and the light receiver. The flag is located
just above the home position, and the HP sensor sends an “On” signal
when the carriage is in the home position.
o Linear Encoder
This encoder is mounted on the back of the carriage and outputs pulses
corresponding to the position of the slits in the timing fence that is
incorporated into the CR guide rail which are used for CR motor software
servo control and PTS (Print Timing Signal) generation. This linear
encoder has a 2-channel digital output format, with phase A and phase B,
and the resolution of each phase is 1/180 inch. Each phase is output so
that it deviates 1/720 inch from the other phase and if full edge output of
both phases is used, the minimum resolution is 1/720 inch. The CR moving
direction is monitored by the CPU through the combination of the phase A
and phase B output waveforms.
Figure 2-5. Carriage Mechanism & CR Guide Rail
Carrige
CR
MOTOR
Step Ruler
(Plastic strip w/ Shaded striper)
Linear
Encorder
HP Sensor
CR Guide Rail Flag
(Projected Area)
No HP Signal HP Signal
Carriage