The potential of the unexposed drum is called the electrified potential (Vd), whereas the potential when toner starts to adhere to the drum is called the development bias (Vb).
Toner starts to adhere to the drum in proportion to the potential when the value of potential becomes more than Vb. The value (coefficient) which shows the relation between the potential and the amount of adhesion is called development gamma.
In addition to the development gamma and the potential, the toner density in the developer needs to be controlled. This is done to maintain the proper toner density (the amount of toner adhesion).
The target figure for the toner density in the developer is called Vref.
Process Control is done as shown in the following chart, which includes development gamma determination, Vref correction, and LD power control.
