Ricoh AC205 - Sensor Input Circuit; Paper Empty Sensor; By-Pass Tray Sensor; Paper Feed Sensor

CONTROLLER
B273 6-10 SM
6.3.7 SENSOR INPUT CIRCUIT
Paper Empty Sensor
The Paper Empty Sensor (photointerrupter) is monitored by the CPU signal
“nP_EMPTY”. The machine shows a message on the LCD when the cassette is
empty.
By-pass Tray Sensor
Paper in the By-pass Tray is detected by operation of the By-pass Sensor
(photointerrupter). The CPU monitors signal “MP_EMPTY” to recognize paper in
the by-pass tray. Paper is fed from the by-pass tray if there is paper present in the
by-pass tray
.
Paper Feed Sensor
When paper passes the actuator on the Feed Sensor, it is detected by the
photointerrupter signal “nP_FEED”. The signal is monitored by the CPU, and starts
the process of creating the image after a specific time delay. Jam0 shows on the
operation panel if the Feed Sensor is not detected within 1 sec. after paper is fed.
The toner cartridge also operates the Paper Feed Sensor when it is inserted into
the machine. A message shows on the operation panel if no cartridge is detected.
Paper Exit Sensor
An Exit Sensor on the Engine Board and an actuator on the frame detect when the
paper exits cleanly from the machine. The sensor checks the signal “P_EXIT” and
detects the on/off time of the Exit Sensor. Jam2 shows on the operation panel if a
jam status is detected.
Cover Open Sensor
The Cover Open Sensor actuator is located on the front cover, (the sensor is
located in the mainframe). Power (+24V) is cut to the following when the front cover
is opened:
• DC fan
• Solenoid
• Main motor
• Polygon motor part of LSU
The CPU monitors signal COVER_OPEN to recognize when the cover is opened
.
DC Fan/Solenoid Driving
These are driven by a transistor and controlled by the signal “FAN SMPS, CON2-
23 bit” of the CPU. The fan is activated by turning the transfer roller when the
signal is high. The fan is deactivated when sleep mode is selected.
There are two solenoids and both are driven by the paper pick-up and MP signals.
The drive time is 300ms. A diode protects the driving TR from the back-EMF pulse,
which is generated when the solenoid is de-energized.
Motor Driving
The motor driving circuit is activated when the driver IC is enabled. The resistance
value of sensing and the voltage value of the V reference can be changed via the
motor driving voltage value.