Sensor Input Circuit - Xerox WorkCentre PE16 Service Manual

4.3.4 Sensor input circuit

1) Paper Empty Sensor
The Paper empty sensor (Photo Interrupter) on the engine board notifies the CPU when
the cassette is empty. The empty signal to the CPU sets the D0 Bit in the CPU, which
results in the CPU turning on the second LED (yellow) on the front panel.
2) MP Sensing
The MP Sensor (Photo Interrupter) on the engine board notifies the CPU if there is paper present
at the MP. It reads the D0 Bit of the CPU to recognize paper in MP, and the paper is fed from
MP if present.
3) Paper Feeding
When paper passes the actuator (Feed Sensor), the circuit detects the signal from the photo
interrupter, sends a status signal to the CPU, and enables image data after a certain delay. If it
doesn't detect the feed sensor within 1 sec. after paper is fed, paper Jam0 occurs (Red and Yellow
LEDs will be turned on at the Front Panel ). Developer insertion is detected using the same principle.
When the developer is mounted, it operates the actuator and the signal from the photo interrupter is
detected by the sensor input circuit. That process is called developer ID sensing.
4) Paper Exit Sensing
The system detects the paper exiting the unit with the exit sensor and actuator attached to the
frame. The circuit detects the on/off time of the exit sensor, and the normal operation or jam
information is passed to the CPU. If exit is not detected, JAM2 occurs.
5) Cover Open Sensing
The Cover Open sensor is located on the front cover. When the front cover is opened, +24V to the
DC fan, solenoid, main motor, polygon motor in the LSU, and HVPS is cut off. The cover-open sensing
is read from the D0 bit of CPU, and initiates developer ID sensing.
6) DC FAN / SOLENOID Driving
This function is driven by a transistor and controlled by the D6 bit of the CPU. When the bit is high,
the fan is driven by turning on the transistor, and it is off when the sleep mode is selected. There
are two solenoids, and they are driven by the paper pick-up and MP signal. The drive time is 300ms.
The diode protects the driving transistor from the noise pulse, which is emitted when the solenoid
is de-energizing.
7) Motor Driving
The motor driving circuit is formed when the Driver IC is selected. The A3977 (Motor driver IC) is
used in this case. The resistance Rs value of sensing and the voltage value of the V reference can
be changed by the motor driving voltage value.
WorkCentre PE16
Summary of product
Service Manual
4-11
July 2003