Epson Stylus Pro 3800 - Platen Gap Adjustment Mechanism

Epson Stylus Pro 3800/3800C/3850/3880/3885/3890 Revision C
OPERATING PRINCIPLES Carriage Mechanism 47
2.5.2 Platen Gap Adjustment Mechanism
Platen gap adjustment mechanism consists of an APG motor, carriage unit, and PG sensor.
The carriage unit is equipped with two carriages; main carriage that moves horizontally to
the carriage guide shaft, and the sub carriage that moves vertically to the main carriage.
When the carriage unit moves to the PG adjustment position and the APG motor starts to
rotate, the oval cam turns to move the sub carriage vertically and change the platen gap
amount. Light-shielding plate with a cutout is installed at the end of the shaft to which the
cam is attached, and moves together with the cam. A transmissive photo interrupter sensor
(PG sensor) detects the cutout, determines the detected position as the origin, and changes
the platen gap according to the number of pulses from the origin.
Figure 2-16. Drive Transmission Path
The relation between the printer status and the platen gap amount is described below.
Figure 2-17. Platen Gap Adjustment Mechanism
Table 2-7. PG Positions in Operations
Operation PG
At power ON 1.2
Cleaning starts 1.5
Capping Capping is done in the current PG.
Board paper tray is open 3.5
PG Shaft
Cam
Sub Carriage
Spur Gear, 29.6
Spur Gear, 34.4
APG Motor
Combination Gear, 13.6, 31.2
Combination Gear, 20, 34.4
Detecting paper width
(ASF feeding, Rear/Front manual feeding)
3.5
Detecting paper width
(ASF feeding after receiving data)
Switch PG according to the print setting.
Starts printing Switch PG according to the print setting.
At power OFF 1.2
Table 2-7. PG Positions in Operations
Operation PG
PG Sensor
Light-
shielding
Plate
Cam
Cutout
Spur Gear, 34.4
Spur Gear, 29.6
Combination
Gear,20, 34.4
Sub Carriage
Main Carriage
Cam
APG Motor
Combination
Gear,13.6, 31.2
Narrow Wide