Sensors And Actuators - Brother FAX4759 Service Manual

2.3

Sensors and Actuators

This equipment has eleven sensors: eight photosensors, two thermistors and a mechanical switch
as described below.
Sensor name
Document front sensor
Document rear sensor
Manual insertion sensor
Registration sensor
Cassette sensor
Paper ejection sensor
Toner sensor
Cover sensor
Heater thermistor
In-casing temperature sensor
Hook switch*
• Document front sensor which detects the presence of documents.
• Document rear sensor which detects the leading and trailing edges of pages to tell the control
circuitry when the leading edge of a new page has reached the starting position and when the
scan for that page is over.
• Manual insertion sensor which detects whether paper is inserted manually through the paper
slot or whether paper fed through the paper cassette has jammed.
• Registration sensor which detects the leading and trailing edges of recording paper, which
allows the controller to determine the registration timing and check paper jam.
• Cassette sensor which detects whether the paper cassette is loaded.
• Paper ejection sensor which detects whether the recording paper goes out of the equipment.
• Toner sensor which detects whether there is toner or a toner cartridge is loaded.
• Cover sensor which detects whether the front cover is closed.
• Heater thermistor which allows the controller to monitor the temperature of the heater roller of
the fixing unit.
• In-casing temperature sensor which allows the controller to monitor the temperature inside the
equipment.
• Hook switch* which detects whether the handset is placed on the handset mount*.
The above photosensors are a photo-
interrupter consisting of a light-emitting
diode and a light-sensitive transistor. Each
of them has an actuator separately arranged
as shown on the next page.
Type
Photosensor
Photosensor
Photosensor
Photosensor
Photosensor
Photosensor
Photosensor
Photosensor
Thermistor
Thermistor
Mechanical switch
III - 10
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Located on
Control panel PCB
Document sensor PCB
Engine PCB
Engine PCB
Engine PCB
Paper ejection sensor PCB
Toner sensor (LED) PCB and toner
sensor (light-receiver) PCB
Toner sensor (LED) PCB
Heat-fixing unit
Left-hand plate of the main chassis
Hook switch PCB*
*For models equipped with a handset
Control panel
PCB ASSY