Brother MFC6800 - Sensors and Actuators

3-10
3.2.3 Sensors and Actuators
This machine has ten sensors: seven photosensors, two thermistors and a mechanical switch as
described below.
Sensor name Type Located on
Document front sensor Photosensor
Document rear sensor Photosensor
Document sensor PCB in the
ADF
Document tray open sensor Mechanical switch Document tray
Scanner open sensor Photosensor Control panel PCB
Registration sensor Photosensor Main-fan PCB
Paper ejection sensor Photosensor High-voltage power supply PCB
CCD HP sensor Photosensor CCD PCB on the CCD unit
Toner sensor Photosensor
Toner thermistor Thermistor
Toner sensor PCB
Heater thermistor Thermistor Heat-fixing unit
• 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.
• Document tray open sensor which detects whether the document tray is closed.
• Scanner open sensor which detects whether the scanner unit is closed.
• Registration sensor which detects the leading and trailing edges of paper, which allows the
controller to determine the registration timing and check paper jam.
• Paper ejection sensor which detects whether the recording paper goes out of the machine.
• CCD HP sensor which detects whether the CCD unit is placed in the home position.
• Toner sensor which detects whether there is toner or a toner cartridge is loaded.
• Toner thermistor which allows the controller to monitor the ambient temperature of the toner
cartridge.
• Heater thermistor which allows the controller to monitor the temperature of the heater roller of
the fixing unit.
These photosensors are a photointerrupter
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.