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PCDU (Photo Conductor and Development Unit)
TD Sensor
In the TD sensor (also called the 
sensor), there is an ID chip storing the machine identification information, the running distance information of Development unit and PCU, and other information used by image density control.
ID chip
PCDU replacement information and toner density information are stored. In the ID chip, the following data is stored.
Model series ID
New PCDU information
Color information
Developer replacement information
PCU replacement information
TD sensor serial no., date of manufacture
Date of unit installation
Unit total counter at installation (no. of sheets, travel distance)
Date of unit operation
Unit total counter during operation (no. of sheets, travel distance)
Unit parts information
Total counter
Total color counter
Pressure Release Filter
To prevent scattering of toner, the air pressure in the development unit is released via a filter.
Development Drive
A gear for developer coil rotation is provided on the front side of the unit (downstream side).
Drive source for Bk | Drive source for C, M, Y |
PCU motor: Black / ITB drive motor | Development motor: CMY |
The PCU motor: Black / ITB drive motor is also used for the image transfer unit and waste toner bottle. Drive is switched by the development solenoid.
Development Bias
Applied from the development power pack via a plate spring on the front cover of the PCDU.