Epson DFX-9000, Service Manual

Page: 67 / 333

Epson DFX-9000 Revision B
Operating Principles Printer mechanism 60
2.2.1.2 Pin assignment for printing
The printhead drive circuit is equipped with a print data register that has
data capacity for 9 pins × 69 columns. The print data register controls
pin assignment based on the data in the register so that the pin use is
evenly distributed. For example, Pin 1of each of the four printheads is
used the same number of times to print one line. The image below
illustrates the print data assignment to print the characters
THE .
Figure 2-4. Print data and pin assignment example.
2.2.1.3 Printhead protection control
There are two types of controls to protect the printhead and they work as
follows.
Undervoltage protection
The nominal operating voltage of the printhead is 42 V. When the
voltage drops below 39.76 V, printing momentarily stops and then
resumes at half the normal print speed.
Thermal protection
When temperatures detected by the thermal sensors on the front and rear
of the printhead are substantially different from each other, printing is
paused or stopped.
The following processes are performed when the thermal sensors detect
an abnormally high temperature level.
1. If the printhead temperature reaches114 °C, the printer will pause for
0.5 second each time the Carrier reaches the right and left end.
2. When the temperature is 116 °C, printing stops.
3. When the temperature level drops below 114 °C, normal printing
resumes.
1 1 1 2 2
2
2
2 3 4 1
2
2
2
2 3
1
1
1
1
1
1
3
3
3
2
3
3
3
3 4 4
4
4
3 4 1 2
4
4
4 1 2 3 4
4
No.1
No.2
No.3
No.4
No.5
No.6
No.7
No.8
No.9
Table 2-2. Thermal sensor and print operation control
Temperature Printing operation
Thermistor
resistance
114 °C Carriage paused at each pass 0.727 k
Ω
Less than 114 °C Normal printing resumes 0.728 k
Ω
116 °C Printing stops 0.695 k
Ω
Less than 114 °C Normal printing resumes if it
had stopped > 0.727 k
Ω