Development Bias Adjustment - Ricoh B246 Series Manual

Development Bias Adjustment

A latent image is written to the drum, using the
default values for development bias, grid voltage,
and laser power
The drum potential sensor reads the potential on
this latent image.
The potential (VL) should be -130V
If the potential is not correct, the development bias
is adjusted to make the potential correct.
Service manual, section 6.8.11, Development Bias, Bias Grid, and LD Adjustment
The next step is to calibrate the development bias.
This step was not done in the Mojito or SP5. In the Mojito, development bias was
fixed at -900V.
The slide describes how it is done.
For example, if VL is -200V, the difference from the target (-130V) is 70 Volts. So
the development bias is changed from the default (-800V) to -870 Volts to keep the
potential at -130V.
This system compensates for dirty laser optics, which would affect the potential on
exposed areas of the drum (Vd), because the full power of the laser would not
reach the drum.
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