Printhead Drivecircuh - Epson Stylus 800 Service Manual

2.3.2.6
The printhead drive circuit for this printer is composed of the following two parts:
•
The SED5620D 64-bit thermal head driver in the head drive circuit on the printhead is used as a
nozzle selector to drive the printhead nozzles selectively. Print data is converted into serial data by
gate array E05BO0 (IC3) and is output from port S1 (pin 63) to the head drive circuit on the
gate array E05BO0 outputs the LAT signal, and the latched data becomes 48-bit parallel data, with
one bit corresponding to each nozzle of the printhead. When data transfer and nozzle selection is
complete, gate array E05BW outputs the common drive pulse PWC (charge pulse) and PWD
(discharge pulse) to the common drive arcuit. The common drive circuit then generates the
trapezoidal pulse and applies it to the printhead as a common drive pulse. After this, the nozzle
selected by the head data is activated to inject ink by energizing the MLP element drive with the
applied trapezoidal drive pulse.
Rev. A
l Commondrivecircuit(trapezoidal
Head drive circuit (nozzle control built on theprinthead)
Figure 2-22. Printhead Drive Pulae
CPU
AN1
(lCl)
Figure 2-23. Printhead Drive Circuit Diagram
drivepulsegeneration)
74
1
HEAD-1
2
+5 v +
2
' TH
HEAD-2
2-17