Print Head Drive Circuit - Epson Stylus Photo Service Manual

Chapter2 Operating Principles

2.2.2.5 Print Head Drive Circuit

The head drive circuits consist of the common driver IC7on the C209 main board and nozzle selectors on
the head driver boards. Each common driver produces trapezoidal pulses according to the signals sent
from the IC2 gate array, and transfer them to the nozzle selector on the head driver board. Printing data is
converted into serial data [Sl1(B,M), Sl2(LM,C) and Sl3(LC,Y)]at the gate array and is then transferred to
the nozzle selector on the head driver board to select the nozzles to be activated. The nozzles selected by
the printing data are driven by the trapezoidal drive pulse generated on the common driver.
Figure 2-25. Print Head Drive Block Diagram
[Common Drive Circuit]
The common driver IC7 H8D2813E produces trapezoidal pulses by combining the 6 different signals
CHG, KC1, ND1,ND2, MD1, and MD2 output from the IC2 gate array using VM voltage as the basis.
By the combinations of signal width from these 6 different signals, total 6 particular types of trapezoidal
waveforms such as normal dot and micro dot. etc are generated. The rising form is determined by the
CHG and KC1 signals regardless of the printing mode. The falling form is determined by ND1, ND2, MD1
and MD2 signals. The VH voltage adjusting values stored in the EEPROM, which are unique to each head
and, are read into the gate array, and then are set in the common driver from HVD0 in the IC2 gate array.
With this procedure, the number of the internal resistance is determined and the drive waveform is
adjusted individually according to each head as the result.
Figure 2-26. Head Drive Waveform
2-25
Rev. A