Epson 3800 Service Manual - Page 47

EPSON Stylus Pro 3800/3800C/3850 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 PG Shaft Cam 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 PG 1.2 1.5 Capping is done in the current PG. 3.5 Revision A Table 2-7. PG Positions in Operations Operation Detecting paper width (ASF feeding, Rear/Front manual feeding) Detecting paper width (ASF feeding after receiving data) Starts printing At power OFF PG 3.5 Switch PG according to the print setting. Switch PG according to the print setting. 1.2 PG Sensor Lightshielding Plate Cutout Cam Cam Sub Carriage Main Carriage APG Motor Spur Gear, 34.4 Combination Gear,20, 34.4 Combination Gear,13.6, 31.2 Spur Gear, 29.6 Narrow Wide Figure 2-17. Platen Gap Adjustment Mechanism OPERATING PRINCIPLES Carriage Mechanism 47