Xerox Phaser 4500 Service Manual

2-8 Phaser 4500 Service Manual
Sensors
The printer contains a number of sensors of various types that perform a variety of
functions. One group of sensors track the progress of the paper along the paper path,
and detect if a paper jam occurs. Other sensors detect the presence of the Print
Cartridge, stop printer activity if a door is open, and monitor the fusing temperature.
The basic printer has 18 sensors, while a fully-optioned printer has 30 sensors.
The types of sensors in use vary with their function. In general, there are four basic
type in use:
■ Photo
■ Microswitch
■ Soft Touch Sensors (STS)
■ Magnetic
Most of the photo sensors consist of a LED in one arm of a U-shaped holder, and a
photo-transistor in the other arm. When nothing is between the arms of the sensor,
light from the LED falls on the photo-receptor, turning it on. If the light is interrupted,
the photo-transistor turns off. The on- or off-state of the transistor is used as a signal.
The microswitches are used primarily as interlocks in the printer. They are in a
normally open state, and close when actuated. A bank of switches in a holder is used
for detecting the size of paper in use in a tray. Cams in the tray close the switches in
various combinations (see “Control of Paper Size” on page 2-18) to send a size signal
to the controller.
The Soft Touch Sensor has a known value of resistance whose sensitivity varies with
temperature.
The magnetic sensor detects the magnetic properties of the toner in the print cartridge.
A fifth sensor in use in the printer is the antenna used to communicate with the
CRUM in the print cartridge.
The list of Sensor and Interlocks that follows gives each sensor by its name, lists
which of the types it is, and briefly describes its function in the printer. The reference
column lists manual pages where illustrations show the location of the sensor.
List of Sensors and Interlocks
Name Type Function Reference
Paper low Mechanically
actuated photo
sensor
Detects low paper condition in
550-Sheet trays 2, 3, and 4
(there is no low-paper sensing
in tray 1).
page 2-11
page 2-17

Xerox Phaser 4500 Specifications

General

Brand	Xerox
Model	Phaser 4500
Category	Printer
Language	English