Epson SQ-B50/2550 Technical Manual page 132

REV.-A
2.4.3.2 Pump Motor Control and Drive Circuit
A block diagram of the pump motor control and drive circuits is shown in Figure 2-75. (Refer also to
Location 7/I-J of the SEIMA Board Circuit Diagram in the Appendix).
The pump motor is DC, and the drive circuit is formed by collector follow bridge TH3C 10 (1 B). During
driving, the CPU provides clockwise (CW) or counterclockwise (CCW) signals to PHC ports P 1 and PO.
For forward rotation, the CCW signal is high, and current ICCW flows to the motor by means of bipolar
connection TH3C 1O.
(The opposite is true for reverse rotation.) No acceleration or deceleration control is provided for the
motor control.
+ 24
PHC
(6 B)
CCW P1
cw
PO
TH3C10 (1 B)
GH
Figure 2-76. Pump Motor Control and Drive Circuit Block Diagram
2.4.3.3 Pump Mechanism
The pump sucks ink from the head toward the wasted ink pack side of the ink cartridge, by which means
it keeps the head full of ink, and the nozzle free of bubbles and dust. Pump reciprocation is the same
regardless of motor drive direction; therefore, the ink flow direction also remains the same (from the
cap side to the ink cartridge side).
Driving of the pump rotates the pump drive gear (see Figure 2-74). Because it is on the same axle as
the drive gear, the pin plate also rotates; the pin on the plate therefore moves in a circle. The pin follow
converts the circular motion to a reciprocating motion. The piston axis, mounted on the pin follower,
generates the pumping.
Pump Drive Gear
~
([11
. Piston /
AXis,'
/
~ ',Ill
---.-fi
Pin Follower
Figure 2-77. Pump movement
2-64