Epson Stylus Color 640 Service Manual page 50

EPSON Stylus Color 440/640/740
Papers on the ASF (auto-sheet-feeder) supplied by the user are carried
to the printer inside by paper pick up sequence. Unlike the previous
models, ASF of Stylus Color 440/640/740 has mufti feed prevention
mechanism. Following explains this function and figure below shows its
mechanism.
[1. Multi-feed prevention mechanism]
When the Load/Eject button is pressed, reversed rotation of PF motor is
performed. The return lever resets papers which are already in the out
of stand by position in the stand by position and make it possible to
perform stable paper feeding by picking up the paper again. Following
explains process of multi-feed prevention step by step. Refer to the
figure above and confirm its operation.
Pintch Roller
D-Cut Roller CAM
Pad spring
Pad
Return Lever
[Standby state]
Figure 2-7. ASF Unit Operation
Chapter 2 Operating Principles
Hopper
Hopper spring
2)
1)
2)
[Returning state]
[Step 1]
When the load/Eject switch is pressed or printing order is input from
the PC, PF motor rotates counterclockwise and makes the CAM
rotate towards direction of 1 in the figure above.
[Step 2]
When the CAM covers the notch by the return lever, that position is
considered as home position, being monitored by ASF sensor.
[Step 3]
When the CAM rotates toward 1 in the figure above, the return lever
is pushed by the notch of CAM and falls towards 2. At this time, the
return lever moves to direction 3 by this motion, and push down the
pad which is waiting in the below part. At this time, friction of pinch
roller and pad will be canceled.
[Step 4]
The papers which are out of stand by position by the previous paper
feed motion are returned to the paper stand by position by flip over
strength of return lever. After this, PF motor rotates clockwise and
the printer goes to pick up sequence.
In the paper pick up mechanism of Stylus Color 440/640/740, same
mechanism as Stylus Color 400, 600, Photo, Photo EX are applied. This
mechanism changes adjoined lines of gear by colliding trigger lever with
carriage unit and convey the motive power on the platen to the ASF side
(paper roller). The figure below shows mechanism with explanation.
Revision A
50