Brother FAX-545, Service Manual

Page: 32 / 198

3-5 Confidential
3.2.4 Sensors and Actuators
This machine uses the following photosensors and microswitches.
Sensor Name Sensor Type Location
Document front sensor Microswitch (SEN2)
Document rear sensor Photosensor (SEN1)
On the control panel PCB
Cover open sensor Microswitch (SW2)
Hook switch* Microswitch (SW1)
Registration sensor Photosensor
On the sensor PCB
Ribbon switch Microswitch In the main cover
Cam switch Microswitch On the drive unit
*Not provided on the FAX-T102.
• The document front sensor detects whether there is a document in the ADF.
• The document rear sensor detects the leading and trailing edges of document pages, indicating
to the control circuitry the point at which to start reading and when page scanning is complete.
• The cover open sensor detects whether the top cover is properly closed.
• The hook switch* sensor
detects whether the handset is placed on the handset mount.
• The registration sensor detects the leading and trailing edges of paper for use in determining
registration timing and detecting paper jams.
• The ribbon switch detects whether the print cartridge (ink ribbon) is loaded.
• The cam switch detects the drive positions of the switching cam in the drive unit.
The document rear sensor and registration sensor are 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 document or print cartridge.
Light-emitting
diode
Light-sensitive
transistor
Actuator's end