Sensor Input Circuit - Xerox Phaser 3450 Service Manual

CIRCUIT DESCRIPTION

11.2.3.4 Sensor Input Circuit

1) Paper Empty Sensing
The Paper Empty Sensor(Photo Interrupter), which is
located in the Engine Board informs the CPU the status
of paper volume through the operation of actuator fixed
on the frame. If there is no paper in the Cassette, it notifies
the second LED(yellow) of the panel LED by reading the
#103 of U18.
2) Paper Feeding Sensing
When the fed paper passes through the actuator of the
feed sensor, it notifies that the paper is being transferred
to CPU by detecting the Photo Interrupter signal and the
image data is distributed after set amount of time
passes.(related to top layer of paper) If the feed sensor
does not detect within 1 second of paper feeding, JAM
0(U18 #105) will occur.
3) Paper MP Sensing(Photo Interrupt)
By operating of actuator, which is attached to frame, MP
sensor detects existence of paper in MP, and informs
status to CPU. Paper status is detected by U27 K26pin.
If paper exists, it is fed in MP status.
4) Paper Exit Sensing(Photo Interrupt)
Actuator, which is attached to frame and connected to
Engine Board (SMPS) CN4, detects if paper exits from
fusing unit. CPU detects information of normal operation
and jam by that U18109pin detects on/off signal of exit
sensor (photo interrupt), and it display jam2 status on
LCD Panel.
5) Paper Duplex Sensing(Photo Interrupt)
Sensor (OP1) attached on engine board(SMPS) detects
paper information when operating duplex printing. CPU
detects information of jam and normal operation by that
U18 102pin detects the detecting signal, and it displays
duplex jam1 or duplex jam2 on LCD panel according to
status of entering duplex paper.
6) Paper Out Bin Full Sensing(Photo Interrupt)
Out Bin Full Sensor detects existing paper amount by
operating actuator attached to frame, and informs the
status to CPU. U18 114pin detects existing paper
amount and displays the status on LCD panel.
7) Paper Size Sensing(tact switch)
It detects each size of fed papers in cassette, and it
arranges and manages data when printing.
distinguishes 8 kinds of paper by 3 switch combinations,
and it is consisted of 8 combinations of U18
106/107/108pin.
Service Manual
11-12
8) Cassette Sensing(micro switch)
By U27 K25pin, cassette detecting function checks
whether tray2 is open or not. When Tray2 is open, LCD
panel displays error status.
9) Toner Cartridge Sensing
It controls memory data of EEPROM in developing unit by
contacting to contacting point of joint board mounted to
frame, and it detects supplier, manufacturing date, toner
remained amount. It writes and reads data by U27
A25/D23/J24 pin and operates with 2-WIRE bus method.
When toner remaining amount is 15%, it displays low
toner on LCD panel to inform toner cartridge detecting
signal.
It