Epson SQ-1170 Service Manual page 74

(1) Charge/discharge circuit
Figure 2-44 shows the chargeidischarge circuit,
HI-48
When the gate array (E05A65) outputs HIGH pulse from CHG port, the transistors (Q3,9) go ON and
thus the Vh voltage charges the piezoelectric elements (PZD) through the diode (DCH) and resistor (RCH).
Figure 2-45 shows the head condition at this time.
The data for 48 nozzles stored in the gate array (E05A65) is serially transmitted from HDDAT port to
the printhead drive IC (pPD 16322). Following this, the discharge pulse is transmitted from E05A65
to KPD 16322. The KPD 16322 then discharges PZD according to the print data to cause the nozzles
to inject ink. (PZD is always charged by Vh.)
For cleaning operation, the E05A65 sends ALDSCHG signal to pPD 16322, which automatically
discharges ail the piezoelectric elements to cause all the nozzles to inject ink.
Figure 2-46 shows the nozzle in discharge condition.
R35
o
o
0 -
Figure 2-44. Charge/Discharge Circuit
Figure 2-45. Head Charge Condition
Figure 2-46. Head Discharge Condition
VH A
Q3
G
2-35
Rs
GH
REV.-A