Process Control and MUSIC
566
Trigger Operative Condition Notes
Control
Toner End
Recovery
When a Toner End is resolved. -
Initial Setting When an initial developer setting is completed. -
Vc is the charge bias, which is applied to the charge rollers.
Vd is the potential of the unexposed (charged) drum.
The value of Vc is not equal to Vd.
For example, if applying a Vc of 700 [-V], the actual drum potential (Vd) tends to be about 650 [-V].
Vb is the potential when toner starts to stick to the drum (Development bias).
When the potential gets to Vb or greater, toner starts to stick to the drum in proportion to the potential.
Development gamma is the coefficient showing the relation between the potential and the volume of toner
adhesion.
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 for the toner density in the developer is when the output from the toner density sensor is Vtref.
Process Control is done as shown in the following chart, which includes development gamma determination,
Vtref correction, and LD power control.