Sensors And Actuators - Brother 1920CN - Color Inkjet - Fax Service Manual

2.3

Sensors and Actuators

This machine has ten sensors: eight photosensors and two thermistors 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
• 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 machine.
• 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
machine.
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
III - 10
Located on
Document sensor 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