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Epson Stylus COLOR 800 Service Manual: Asf Mechanism

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2.2.7 ASF Mechanism

ASF mechanism, which consists of the Pump motor, slider mechanism, disengage mechanism, and ASF
unit, loads paper into the paper feed mechanism. When the CR unit returns to the home position, it
pushes the slider in the slider mechanism to the right and the Gear (16) in the slider mechanism then
comes to engage with the Change cam in the disengage mechanism. With this motion, the Pump motor
rotates with the specified steps in the counter clock wise, which switches the Change cam to the ASF unit
side, then the torque from the Pump motor is transmitted to the ASF unit. The process in which the drive
from the pump unit is switched to the ASF unit side is described below. Figure 2-8 illustrates the process
for the switching operation.
‰Disengage mechanism switch process
1) CR shifts to the home position.
2) Slider shifts to the right end. (Slider mechanism)
3) The Gear (16) is engaged to the Change cam in the disengage mechanism. (Slider mechanism)
4) The Change Cam is switched to the ASF side. (Disengage mechanism)
5) The Combination Gear (14.4, 21.6) shifts to the left.
The figure below shows movement of above mentioned process 3) to 5).
‰Transmission process of the Pump motor's torque
1) Pump motor pinion gear 2) Combination gear 12, 26
4) Gear 16.8
7) LD roller shaft (ASF unit)
Note) This order has no relevance to the order in the figure above.
The ASF home position is sensed by the detection wheel attached to the right end of the LD roller shaft
and ASF HP sensor, and the detected condition is fed back to the IC2 E05B33CB. The ASF motor is
controlled based on the home position which is detected by the ASF HP sensor. A 4-phase/48 -pole PM
type pulse motor is used for the pump motor which is controlled by the constant current bipolar drive. The
current control signal for each phase and phase control signal output from the IC2 gate array E05B33CB
are converted into the pump motor control signal by the IC6 bipolar driver UDN2917EB to control the PF
motor. Table 2-6 and Table 2-7 show the pump motor specification and pump motor drive frequency,
Rev. A
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Figure 2-8. ASF Mechanism
5) Combination gear 12, 20.8 6) Gear 27.2 (ASF unit)
Table 2-6. Pump Motor Specification
Motor type
4-phases / 48-pole / PM type pulse motor
42 VDC ± 5% (The voltage applied to the driver)
Drive voltage
9.3 Ω ± 10% (at 25° C per 1 phase)
Coil resistance
Drive frequency
272 ~ 654 Hz
Excitation mode
Bipolar drive
Minimum step
1/218 inch / pulse (2-2 phase drive)
3) Combination gear 14.4, 21.6
Operating Principles


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