Xerox Phaser 8560MFP Service Documentation page 284

Two types of photo sensors are used, photo-reflective and photo-receptive. Photo-reflective System Drive
sensors use light reflected back from an object to detect its presence. Photo-receptive sensors
use an actuator or the object itself to block the light path to detect an object or condition. Photo-
reflective sensors have the light emitter and light receiver aligned on a single surface. Output of
the photo-receptor is High when light is being reflected back and Low when it isn't. Photo-
receptive sensors consist of a LED in one arm of a U-shaped holder, and a photo-transistor in
the other arm. When the sensing area is vacant, nothing is between the arms of the sensor,
light falls on the photo-receptor sending the signal High. If the light is interrupted, the photo-
transistor goes Low.
Microswitches are used primarily as paper size sensors and cover interlocks. They are in a nor-
mally open state, and close when actuated. A bank of microswitches is used to detect paper
size in the universal trays. Microswitches also employ hooks or catches for retention in the
bracket or frame.
Temperature Sensors (Thermistors) have a known value of resistance whose value varies with
temperature. Used primarily in the Drum and Printhead for temperature sensing.
Figure 6 System Drive Component Locations
Theory of Operation Initial Issue
10/2006
Image Output Terminal
8-12 Phaser 8510/8560MFP Multifunction Product