Printhead Drive Circuit - Epson STYLUS 4001968 Service Manual

800 Service
STYLUS Manual
2.3.2.6
The printhead drive circuit for this printer is composed of the following two parts:
Common drive circuit (trapezoidal drive pulse generation)
Head drive circuit (nozzle control built on the printhead)
The 64-bit thermal head driver SED5620D 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 E05A85EB (IC3) and is output from port S1 (pin 63) to the head drive circuit on the
array E05A85BE 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 E05A85BE outputs the common drive pulse PWC (charge pulse) and PWD
(discharge pulse) to the common drive circuit. The co mmon drive circuit then generates the
trapezoidal pulse and applies it to the printhad 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.
CPU
(lCl)
Figure 2-19. Printhead Drive Circuit Block Diagram
Rev. A
GND .--------: ------- j----------------------- --'-------------------------
5
4
AN1 7
4
Operating Principles
2
SI
2
' TH
I I
I
HEAD-2
2-17