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EPL-N2700 Revision A
Operating Principles Printer Mechanism Operating Principles 73
Rush current preventing circuit for heater lamp
To prevent rush current when an AC voltage is applied to the heater
lamp, the CPU turns off the Remote 1 signal and turns on the
Remote 2 signal in the form of pulse. By outputting Remote 2, the
additional resistor is connected in series to the heater lamp to
suppress the rush current flowing into the heater lamp.
Thermostat (TS1) and heater lamp fuse (TF1)
If an abnormal current flows into the heater lamp because of
thermistor trouble, etc. and the upper fusing roller temperature
reaches about 220°C, the contact of the thermostat automatically
opens to shut off an AC voltage. (As the temperature decreases, the
contact of the thermostat closes again. However, once the
thermostat has been activated, it must be replaced with new one.)
When a large abnormal current suddenly flows into the heater lamp,
since the thermostat cannot respond quickly, the heater lamp fuse is
blown to protect the heater lamp.
Fusing temperature control
1. When the main switch is turned ON, the fuser starts warm-up
until the upper fusing roller temperature reaches approximately.
200°C. (It will take about one minute.)
2. To maintain the upper fusing roller temperature above 190°C,
the control circuit raises the temperature and keeps at
approximately. 210°C for approximately. five minutes. (Mode 1)
3. The control circuit gradually decreases the temperature by
190°C in five minutes. (Mode 2)
4. Preparing for printing, the control circuit keeps the upper fusing
roller temperature at approximately. 190°C. (Mode 3)
5. While the printer is in the idle status, the control circuits maintain
the temperature at 180 °C.
6. In energy saving mode, the control circuit turns OFF the heater
lamp.
NOTE:190°C --> 183°C for overseas versions (TBD)
Figure 2-28. Fuser Temperature Control
Fuser temperature control depending on the paper type
Normal paper:190°C
Special paper (thick paper):200°C
OHP:180°C
PPM (Print Per Minute) control
When the printer prints on more than specified number of paper
whose width is 250 mm or less, the temperature of the fuser rises by
its edge areas. To avoid abnormal rise of the temperature, the
printer prints with larger intervals than normal. (Print speed
reduces.) When the interval is more than 2 minutes, the printer
release the PPM control.
In Mode 3:After 1000 sheets, PPM control is activated.
In Mode 1 or 2:After 30 sheets, PPM control is activated.