Phaser 6500/WorkCentre 6505 Service Manual Xerox Internal Use Only 2-17
Theory of Operation
Sensors
The printer contains sensors of various types that perform a variety of functions.
One group of sensors track media along the media path to detects jams. Other
sensors detect the presence of the Toner Cartridges, stop printer activity if a door is
open (interlock), detect the presence of media in the trays, and monitor fusing
temperature.
Sensor Types
The types of sensors used vary with function. In general, there are three types:
Photo Sensors
Two types of photo sensors are used, photo-reflective and photo-receptive. Photo-
reflective sensors have the light emitter and light receiver aligned on a single
surface. Output of the photo-receptor is High (> +4.5 V) when light is being
reflected back and Low (< +.3 V) 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.
List of Sensor and Interlock Functions
Name Type Function
No Paper Photo-receptive Detects no paper condition in all trays.
Registration Photo-receptive Detects paper at the registration rollers.
Exit Photo-receptive Detects paper as it leaves the Exit.
Stack Full Photo-receptive Detects when the Output Tray is full.
K Mode Photo-receptive Detects Black-only print mode.
Temperature Thermistor Monitor temperature of the Heat Roller.
Cover Interlock Microswitch Interrupts +24 V to the Main Motor
Start of scan Photo Detects laser at the start of a scan.
Fuser
Thermostats
Thermostatic
switches
Interrupts AC power to the Fuser.
Humidity Integrated circuit Monitors the printer’s environment.
Actuator
Optic_Sensor_Actuator
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