Sensors And Actuators - Brother 8250P - FAX B/W Laser Printer Service Manual

2.3

Sensors and Actuators

This equipment has ten sensors: seven photosensors, two thermisters and a mechanical switch as
described below.
Sensor name
Document front sensor
Document rear sensor
Top cover sensor
Sheet feeder cover sensor
Registration sensor
Paper ejection sensor
Toner sensor
Toner thermister
Heater thermister
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.
• Top cover sensor which detects whether the top cover is closed.
• Sheet feeder cover sensor which detects whether the sheet feeder cover 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 equipment.
• Toner sensor which detects whether there is toner or a toner cartridge is loaded.
• Toner thermister which detects the ambient temperature of the toner cartridge.
• Heater thermister which detects the temperature of the heater roller of the fixing unit.
• Hook switch* which detects whether the handset is placed on the handset mount.
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.
Type
Photosensor
Photosensor
Photosensor
Photosensor
Photosensor
Photosensor
Photosensor
Thermister
Thermister
Mechanical switch
III - 10
Located on
Control panel PCB ASSY
(Document sensor PCB)
Control panel PCB ASSY
(Document sensor PCB)
Main PCB
Main PCB
Main PCB
High-voltage power supply
PCB
Toner sensor PCB
Toner sensor PCB
Heat-fixing unit
Hook switch PCB*
*Not provided on the FAX-8250P/MFC-9050.