Printing Process - Ricoh B230 Service Manual

6.1.5 PRINTING PROCESS

This machine uses four PCUs, and four laser beams for color printing. Each PCU consists
of the drum unit and the development unit. Each drum unit has a drum, charge roller,
cleaning brush, and blade. From the left, the PCU stations are yellow, cyan, magenta, and
black.
The drum [A] is charged with a negative voltage, and is exposed by the laser from the laser
optics housing unit [B]. The laser neutralizes the negative charge on the surface of the
drum. So, the white parts of the image correspond to areas of the drum that still have a high
negative charge. The toner has a negative charge, and it moves to the areas of the drum
that have the smallest negative charge (i.e., the areas written by the laser beam).
The image on each drum is moved to the transfer belt by the positive bias that is applied to
the transfer belt [C]. All four toners are put on the belt at the same time. Then, the
completed four-color image is moved to the paper by a negative charge applied to the ITB
drive roller [D] (the transfer roller [E] is an idle roller).
1. Drum charge: The charge roller gives the drum a negative charge
2. Laser exposure: The laser beam from the laser diode (LD) goes through the lens and
mirrors and reaches the drum. The machine turns the laser beam on and off to make a
latent image on the drum.
3. Development: The development roller carries negatively charged toner to the latent
image on the drum surface. This machine uses four independent development units
(one for each color).
4. Transfer:
Image transfer: Bias rollers opposite the OPC drums transfer toner from the drums to
the transfer belt. Four toner images are super-imposed onto the belt.
Paper transfer: Then, the ITB drive roller pushes the toner from the transfer belt to the
paper (the transfer roller is an idle roller).
B230/B237 6-6 SM