Epson DFX-5000+, Service Manual

Page: 54 / 223

Operating Principles
Interlock switch
Because the carriage moves at a very high speed, it would be dangerous if a hand
or finger were inserted inside the printer mechanism during printing. Therefore,
as a safety measure, when the top cover is opened, the interlock switch cuts the
drive voltage to the CR motor to slow down the carriage speed and prevent
accidents. A control circuit controls CR motor driver deceleration. (See
CR
Drive Circuit, later in this chapter.) Printing resumes when the top cover is closed.
Auto platen gap adjustment mechanism
The printer mechanism has an automatic platen gap adjustment function that
measures the thickness
paper and provides the appropriate gap between
the platen and printhead. The platen gap is adjusted by moving the carriage (and
printhead) either forward or backward. Because the front and rear carriage guide
shafts which hold the carriage are purposely mounted off-center, the carriage
moves as the PG motor rotates the shafts. The PG sensor transmits the amount of
movement (= gap) to the control circuit.
Ribbon feed mechanism
The printer’s ribbon cartridge contains an endless ribbon. The ribbon feed
mechanism takes up the ribbon so that the portion hit by the pins is constantly
changing. The RF motor drives the ribbon feed mechanism. Figures 2-2 and 2-3
show the operation
ribbon feed mechanism.
Position
Figure 2-2. Printer Mechanism Operation 1
Paper feed mechanism
The CR motor controls printing in the horizontal direction, and the paper feed
mechanism controls movement in the vertical direction (line feeding and form
feeding). The paper feed mechanism feeds paper vertically. The PF motor drives
the paper feed mechanism.
2-2
EPSON Service Manual