Epson DLQ-3000 Service Manual page 92

2.3.12 Other Sensor Circuits
This printer is equipped with other sensors to monitor printer condition in detailed.
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Head thermistor
The head thermistor detects temperatures around the head and sends the information
with the analog signal to the CPU A/C converter using the internal resistance (16.5K
This information prevents worn-out and shorter life of the drive coils due to over duty
printing, and protects printhead during operation at low temperatures.
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+35 VDC monitor
The CPU monitors head drive voltage by detecting the +35 VDC line with the internal A/D
converter. The printer changes the print mode according to the detected change in the
head drive voltage.
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Cover open sensor
Cover open sensor, located at the top right of the upper housing, detects the printer
cover's open/close condition. The output signal is reversed by the digital transistor and
input to the CPU interruption port via the filter circuit which consists of the resistor and
condenser.
Detecting method
Power supply voltage
Detecting mode
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Color HP (Home Position) sensor
Color HP sensor uses a photo interrupter system. When the home position for the color
ribbon cartridge is detected, the output signal is pulled up to 10 K , then input to the
CPU port via the filter circuit which consists of the resistance and the condenser.
Detecting method
Output system
Switch mode
Note) After the printer is powered on or the cover open is detected, the printer refers to
the switching mode of this sensor.
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Rear paper sensor
Rear paper sensor is located on the right side of the paper jam sensor. The output signal
is pulled up by 6.2 K , then input to the CPU port via the filter circuit which consists of
the resistor and the condenser.
Detecting method
Rated
current/voltage
Switch mode
Rev. A
Table 2-21. Cover Open Sensor Specification
Mechanical switch
5 VDC
Cover open : LOW
Cover closed : HIGH
Table 2-22. Color HP Sensor Specification
Photo interrupter system
Open collector system
Resistance to voltage:30V or less
Sink current : 0.3 mA or less
In the home position : LOW
Off the home position : HIGH
Table 2-23. Rear Paper Sensor Specification
Mechanical switch (connector switch) system
0.6 1.0mA, 5VDC
Paper detected : LOW
No paper detected : HIGH
5%
5%
Operating Principles
2-31
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