August 2006 PROCESS CONTROL
6-79
Detailed
Descriptions
TD Sensor
There is a TD sensor [A] below the development unit of each PCU.
The TD sensor directly measures the amount of toner in the developer/toner
mixture. Unlike previous machines, this TD sensor is not in direct contact with the
developer/toner mixture.
Vt is the output voltage of the TD sensor. When Vt goes high, toner is added to the
developer to bring Vt back to the Vtref value.
Temperature/Humidity Sensors
Two temperature/humidity sensors are used for process control. One is above the
black PCU, and one is below the waste toner bottle.
Temperature/humidity sensor – PCU K
This sensor is in the black PCU (the last PCU on the right).
The output of this sensor is used to:
• Set the level of the ac charge applied to the charge roller of each PCU
• Set the length of time the agitator in the development unit rotates to mix the
developer and toner.
• Co ntrols the Peltier unit
Bottom temperature/humidity sensor
This sensor is below the waste toner bottle.
The output of this sensor is used to control the amount of current applied to the ITB
and paper transfer roller. It is also used to correct the fusing idling temperature.
B132D905.BMP
[A]