Oki OKIOFFICE 84 Service Manual page 402

IOGA4 ports for referring to and processing by the IOGA4 (CPU).
Figure A3.1.13 shows sensors and switch control.
l
Inlet sensor 1
l
Write sensor (To detect the paper top position for printing)
l
Outlet sensor
l
Toner end sensor
l
Cover status switch
The functions of various sensors are described in the following table.
Sensor Type Sensor Name
PSIN-N Inlet sensor
WRNS-N Write sensor
PSOUT-N Outlet sensor
TNRSNS-N Toner sensor
CVOPN-N Cover open sensor
2) Fuser unit temperature control
The heater in the fuser unit is controlled by the thermister, IOGA4 keeps the heater roller surface within a prescribed
temperature range. The IOGA4 supervises the status of THCHK (A/D converter input section) periodically, turning
HEATON signal on and off according to IOGA4 of THCHK status to exercise temperature control.
At power on time, the IOGA4 switches the output signal THON from pin 59 (between high and low states) to check
for a blown or shorted thermister according to the status of the THCHK signal.
A built-in thermostat in the fuser unit prevents the heater from being overheated in event of failures in the thermister,
or temperature control circuit, etc.
Figure A3.1.14 shows the fuser unit temperature control.
Note:
Heater control
Temperature of the heater at the time of printing is 150 °C to 180 °C. This temperature is maintained by controlling
the on and off operation of heater according to the input of the thermister converted into analogue-digital (A/D)
values by the IOGA4.
2)-1 Heater control
Function
This photosensor is positioned before the resist roller to
detect whether the paper has entered into the printer section.
Detects the arrival of paper at designated position on the
paper transport route inside the printer in order to turn on the
light of the LED head.
0: Paper exists, 1: Paper does not exist
Located at the exit of the printer to supervise the paper exit
operation.
0: Paper exists, 1: Paper does not exist
Detects the remaining toner in the toner cartridge.
"The length of time of low-toner state within fixed time
interval" detects a low-toner state.
Detects whether the cover of the printer section is open or
not.
0: Cover is open, 1: Cover is close