Epson Stylus Photo 950, Service Manual

Page: 30 / 191

EPSON Stylus PHOTO 950 Revision A
OPERATING PRINCIPLES Printer Mechanism 30
2.2.3 Paper Feeding Mechanism
The Paper Feeding mechanism consists of components such as ASF, Manual Feed
Mechanism and Roll paper holder.
2.2.3.1 ASF Mechanism
The paper feeding mechanism consists of Paper feed motor (PF motor), PF roller,
Paper eject roller, Star wheel roller, and so on. The paper feeding mechanism feeds
paper loaded from ASF using the PF roller and Paper Eject Roller & Star wheel roller.
For this mechanism, the PF motor mentioned in the following Table 2-4 is used on this
product.
The paper feed motor used in previous models was a stepping motor and control was
carried out by means of open loop control. However, this printer employs closed loop
control via a DC motor and a rotary encoder to control the carriage speed and position
in order to improve the paper feeding accuracy. The rotary encoder is installed to the
left end of the PF roller shaft and controls the paper feeding amount. See "PF Motor
Driver Circuit" on page 50 of this chapter for details of the PF motor control circuit.
The PF motor drive force is transmitted to the PF roller and the paper eject roller along
the route described below.
†
PF roller drive force transmission route
PF motor pinion gear
→
PF rotary encoder
→
PF roller
†
Paper eject roller drive force transmission route
PF motor pinion gear
→
Combination gear 9.5, 14.7
→
Paper eject roller
A diagram of the PF motor drive force transmission route, including the names of the
components included in this route, is shown on the following page. The paper is
transported along the following path by means of the above drive force transmission
routes.
Figure 2-4. Paper Feeding Mechanism 1
Table 2-4. PF Motor Specifications
Item Description
Motor type
DC motor
Drive voltage
+42V +/- 5% (DRV IC voltage)
Coil Resistance
30.5
Ω
+/- 15% (per phase at 25 degree)
Inductance
22.8mH +/- 15% (1kH 1Vrms)
Driving method
PWM drive (PWM means Pulse Width Modulation)
Combination gear
12, 16
PF motor
pinion gear
Combination gear
9.5, 14.7
PF rotary
encoder
Spur gear 12
Spur gear 21.5