Brother FAX 560, Service Manual

Page: 21 / 194

III - 4
2.4 Sensors and Actuators
This equipment has two photosensors and five mechanical switches as described below.
Sensor name Type Located on
Document front sensor Microswitch (SEN1) Control panel PCB
Document rear sensor Microswitch (SEN2) Control panel PCB
Cover sensor Microswitch (SW2) Sensor PCB
Hook switch* Microswitch (SW1) Sensor PCB
Registration sensor Photosensor Sensor PCB
Ribbon sensor Photosensor Main PCB
Arm HP switch Leaf switch Drive unit
*Not provided on models w/o handset.
• 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.
• Cover sensor which detects whether the control panel ASSY is closed.
• Hook switch sensor* which detects whether the handset is placed on the handset mount.
• 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.
• Ribbon sensor which detects whether the ink ribbon is loaded.
• Arm HP switch which detects whether the switching arm of the drive unit is placed in the home
position.
The registration sensor and ribbon sensor is a photointerrupter consisting of a light-emitting diode
and a light-sensitive transistor. Each of them has an actuator separately arranged (see the next
page). When an actuator is not activated, its black end lies in the path of light issued from the light-
emitting diode and interrupts its light so that the emitted light does not enter the light-sensitive
transistor. If paper or ribbon comes in so as to activate the actuator, the actuator's black end goes
out of the light path and the emitted light enters the light-sensitive transistor. This way, the sensor
detects the presence of paper or ink ribbon.