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Part 4: Technical Reference
Purge sensor
This photo-interrupter-type sensor detects the capping position of the purge unit.
Detection of the module phase at the capping position is performed by interruption of
the purge sensor by the cam gear flag inside the purge unit.
Paper end sensor
This photo-interrupter-type sensor detects the presence of paper on the paper feed
section. Interruption of the paper end sensor and feeding of paper on the paper feed
section are detected by the paper end sensor arm being pressed by the paper.
Pick-up roller sensor
This photo-interrupter-type sensor detects the initial position of the pick-up roller on
the sheet feeder. Pick-up roller at the initial position is detected by the pick-up roller
flag interrupting the pick-up roller sensor.
Encoder sensor
Refer to Part 4: 3.4.2 Carriage unit structure 3) Encoder section (page 4-29) .
Temperature sensor
This temperature sensor is a thermistor on the carriage board, and detects the
temperature inside the printer.
The printer reads the output voltage of the temperature sensor which changes
according to changes in the temperature at the A/D port of the MPU, and A/D-converts
this output voltage to detect the temperature. Optimum printing control and
overheating protection is performed based upon this temperature and the temperature
detected by the head temperature sensor.
Cover open sensor
When the top cover is closed, a protrusion on the top cover presses a switch on the
panel board. When the top cover is open, the switch on the panel board is not pressed,
and "cover open" is detected.
Paper size sensor
This sensor comprises a logic board and five switches located on the upper and lower
cassette units. When the printer is viewed from the front, the left end switch is not
pressed when the cassette body is drawn out, and is pressed when the cassette
receptacle is not drawn out.
The paper width is detected by the other four switches being pressed by the side guides
on the cassette body.
The paper size is detected is by the length and width of the paper.
The head temperature sensor is built into the heater board on each print
head. For details, see "Part 4: 3.2.5 BJ cartridge drive circuit" (page 4-22) .
The purge sensor, paper end sensor and pick-up roller sensor judge
whether or not an error has occurred by the detection states of the
sensors. (Errors are not displayed by the detection state of the
temperature sensor inside the printer.) For details of error indication, see
"Part 3: 3. PRINTER SERVICING FUNCTIONS" (page 3-17) .
The states of the purge sensor, paper end sensor and pick-up roller sensor
are detected at the input port of the printer controller. Detection signals
are inverted by opening and closing the sensors.
4-44
BJC-8500
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