Platen Gap Adjustment Mechanism - Epson Stylus Pro 3800 Service Manual

Epson Stylus Pro 3800/3800C/3850/3880/3885/3890

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.
APG Motor
Combination Gear, 20, 34.4
Combination Gear, 13.6, 31.2
Spur Gear, 29.6
Spur Gear, 34.4
Sub Carriage
Figure 2-16. Drive Transmission Path
The relation between the printer status and the platen gap amount is described below.
Table 2-7. PG Positions in Operations
Operation
At power ON
Cleaning starts
Capping
Board paper tray is open
OPERATING PRINCIPLES
PG Shaft
Cam
PG
1.2
1.5
Capping is done in the current PG.
3.5
Operation
Detecting paper width
(ASF feeding, Rear/Front manual feeding)
Detecting paper width
(ASF feeding after receiving data)
Starts printing
At power OFF
PG Sensor
Light-
shielding
Plate Cutout
Sub Carriage
Cam
Figure 2-17. Platen Gap Adjustment Mechanism
Carriage Mechanism
Table 2-7. PG Positions in Operations
Switch PG according to the print setting.
Switch PG according to the print setting.
Main Carriage
Cam
Spur Gear, 34.4
Narrow
Revision C
PG
3.5
1.2
APG Motor
Combination
Gear,20, 34.4
Combination
Gear,13.6, 31.2
Spur Gear, 29.6
Wide
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