Auto Sp Control - KIP 9000 Service Manual

3. 5. 2

Auto SP Control

A proper voltage gap must be maintained between [Bias] (Developer Bias) and [SP; white]
(Surface Potential for white) for avoiding a foggy background problem.
But if the Auto Density Control increases (adjusts to more negative side) the [Bias], the voltage gap
between [Bias] and [SP: white] may become so small. Especially the Auto Density Control tends to
increase the [Bias] greatly when in a cold environment as bigger voltage gap is required between
[SP: black] (Surface Potential for Black) and [Bias] to have enough density. The foggy background
problem tends to occur in such case because of small voltage gap between [Bias] and [SP: white].
GND
SP black
Bias
SP white
In normal environment
If [SP: white] is adjusted to more negative side accompanying to the increment of [Bias], it is
possible to have enough voltage gap between [SP: white] and [Bias] so the foggy background can
be avoided. The Auto SP Control is thus a process to adjust the [SP: white] automatically to have
enough voltage gap against [Bias].
GND
SP black
Bias
SP white
Before the adjustment by Auto SP Control
(Between [Bias] and [SP: white] is small.)
GND
SP black
Bias
SP white
3-24
GND
SP black
Bias
SP white
In a cold environment
(Gap between [Bias] and [SP: white] is very
small.)
GND
SP black
Bias
SP white
After the adjustment by Auto SP Control
(Between [Bias] and [SP: white] is enough
large.)
K115sm3e2.doc