Epson LQ-2550 Technical Manual page 112

REV.-A
2.3.4.4 Printhead Temperature Detection Circuit
Figure 2-61 shows the printhead
using a thermistor in the printhead.
The temperature of the printhead rises as the solenoids in the printhead continue to be driven. To prevent
the solenoids from burning, printer operates as shown in Figure 2-62.
- — - - - - - - ResI f o r
— - — - — H o I f S p e e d P r i n t i n g
90" c ~ • €
80° C
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Figure 2-62. Printhead Temperature and Printing Operation
If the printhead temperature exceeds the upper limit (90"C), printing is "automatically stopped. In this
state, the ON LINE LED blinks. When the printhead temperature drops to the upper limit or less, printing
is resumed at half speed. When the printhead temperature drops to the lower limit (80" C) or less, the
normal printing speed is automatically resumed.
NOTE: "Half speed" actually means to drop down to the next lower print speed.
Table 2-41 shows the relationship between the upper/lower limit values for printhead
the voltage at the AN 1 terminal of the
temperature detection circuit. This circuit detects the temperature
AN1 4
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Figure 2-61. Printhead Temperature Detection Circuit
P r i n t i n g
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Upper Limif Value
Lower Limit Value
temperature, and