Paper Feeding Mechanism - Epson STYLUS Scan 2500 Service Manual

EPSON Stylus Scan 2500

2.2.4 Paper Feeding Mechanism

The paper feeding process begins at the ASF, continues through the PF
roller, and ends at the paper eject roller (and star-wheel gear).
The ASF unit, which is common with the Stylus COLOR 740 printers, is
driven by the PF motor (stepping motor). Torque sent from this motor
switches between the ASF unit and pump/PF roller depending on the
position of the disengage lever (described later).
In the EPSON Stylus Scan 2500, a four-phase hybrid type pulse motor is
used in the PF motor as a motive power of the paper mechanism. The
torque is sent at 2-Double 1-2, Double 1-2, 1-2, and 2-2 phase drives. This
motor drives the paper-feeding mechanism as well as the pump
mechanism which is necessary for printhead cleaning. By using this pulse
motor, it becomes possible to use variable drive levels for many
purposes, such as paper feed, slight paper feed, and high or low speed
absorption of pump operations. The following table shows PF motor
specifications.
PF Motor Specifications
Item
Motor type 4-phase/200-pole Stepping motor
Drive voltage 42VDC
7.8 Ohms
Coil Resistance
environment)
Control method Bi-Polar Drive
Phase drive 1-2, 2-2, Double 1-2, 2-Double 1-2
Phase drive
Phase Drive
2-2
1-2
Double 1-2
2-Double 1-2
Operating Principles
Description
5%
10%(per 1 phase under 25 C
Inch/pulse mm/pulse
1/720 0.035
1/1440 0.018
1/2880 0.0088
1/5760 0.0044
Printer Mechanism Operation
Rotor
Figure 2-7. PF Motor Internal Circuit Diagram
Motor Control for Each Mode
Drive Speed
Printing mode
[CPS]
High Speed Skip 340
Normal Printing 200
Capping 80
Wiping 40
Cap (Valve
20
Release)
Withdrawal of cap 5
Drive from the PF motor is sent to the PF rollers and paper eject rollers as
described below.
To the PF rollers:
PF motor pinion gear (CCW rotation)
Revision A
A
1
/A
2
3
B
4
/B
Drive frequency
Drive method
[PPS]
Double 1-2, 2-2,1-2
4080
phase drive*
Double 1-2, 2-2 phase
2400
drive
2-Double 1-2, 2-2 phase
960
drive
2-Double1-2, 2-2 phase
480
drive
4-Double1-2, 2-2 phase
240
drive
4-Double 1-2, 2-2 phase
60
drive
Gear 73.6 PF rollers
40