Pg/Po Motor (Stepping Motor); Pg Phase Sensor; Pg/Po Motor Rotation Directions And Functions; Pg Setting Positions - Epson Stylus Pro 4400 Service Manual

EPSON Stylus Pro 4400/4450/4800/4880/4880C

PG/PO Motor (Stepping motor)

When the transmission path is switched to the platen gap adjustment side
by the Carriage unit movement and DE Lock Lever, the PG/PO Motor can
automatically shift (rotation movement of Carriage Shafts, both front and
rear) the PG position up or down.
Movements of the PG/PO Motor drive transmission to the Platen Gap
adjustment side are shown below.
Table 2-7. PG/PO Motor Rotation Directions and Functions
PG/PO Motor Rotation Direction
Clockwise
Counterclockwise
Note : Rotation of the motor in the clockwise direction as seen from the Motor Pinion
Gear is considered "clockwise".
The Adjustment Lock Bushing rotates with the rotation of the Carriage Shaft.
When Carriage Shaft rotation stops, the PG Lock Lever locks the Adjustment
Lock Bushing. Securing the Adjustment Lock Bushing suppresses rotation of
the Carriage Shaft and prevents fluctuation in platen gap.
The locking position has 4 levels to match PG.
Adjustment Lock Bushing
PG large side
Figure 2-23. PG Setting Positions
Operating Principles
Function
PG small side → PG large side
PG large side → PG small side
PG Lock Lever
PG minimum side
Printer Mechanism Components
The sensors used in the platen gap adjustment components are described
below.

PG Phase Sensor

This is a transmissive sensor installed on the left side of the printer that
detects the PG position (height of head from paper surface) and machine
home position (home) at the time of adjustment movements. A reflective
sensor is used to detect the flag position of the shield plate attached to the
right side of the front Carriage Shaft. With machine home position as the
standard, 4 head positions can be obtained.
Table 2-8. PG Setting
Gap
Position Application
Width
Macimum 2.6mm Platen gap for thick paper
Large 2.1mm Platen gap for paper which can be
soiled if setting is for thin paper
Medium 1.5mm Platen gap fot specified thin paper
which has frictional force more
than the other thin paper.
Small 1.2mm Platen gap for thin paper
Minimum 0.7mm Platen gap for film
Revision C
Pulse Count from Origin
(Converted to 2-2 Phase
Excitation)
244
176
96
60
0
130