Epson DFX-9000 Service Manual page 95

Epson DFX-9000
Main excitation / flyback time selection circuitry
This section utilizes an 8-bit Analog/Digital converter to monitor the
head drive voltage (42 V), the 16-byte front main excitation time table,
front flyback time table, and rear flyback time table. The values in the
tables are changed by the firmware on a line-by-line basis according to
the temperature of the printhead. A best control time is selected and sent
to the print timing control section according to the print job.
Print trigger generation
The trigger pulses are generated based on the linear encoder pulse input
for SP motor control and the density value predetermined by the
firmware. The following shows the print trigger generation timing.
CLK(24M)
TRIGEN
Phase A
Phase B
480dpi
240dpi
120dpi
96dpi
80dpi
60dpi
48dpi
Figure 2-35. Print trigger generation timing
Since the CR encoder resolution is 1/120 inch, some print densities do
not match the resolution of the CR encoder input. In those cases, the
print timing is calculated based on the last CR encoder cycle. The print
density supports 480, 360, 240, 180, 144, 2880/21, 120, 96, 90, 80, 72,
and 60 dpi.
Operating Principles
Printhead timing control
After the required offset time is set on a print trigger basis, the main and
flyback pulses are generated based on the input from the main
excitation/ flyback time selection circuit and print trigger generation
circuit. The head control timing is shown below.
Print Trigger
Offset Timer
Parallel Timer
Parellel Enable
Mask Signal
MFTIM_11
MAINF_11
FLYBK_11
Current Signal
Circuit operation
Figure 2-36. Head control timing
Revision B
88