Minolta CF910 Service Manual page 31

1. AIDC Sensor UN20 Fine Adjustment
• This function corrects variations in the AIDC detection level (the amount of toner
attracted to the surface of the PC Drum) that occur due to a contaminated UN20.
• It is carried out when the Power Switch is turned ON.
Operation Flow
A. UN20 detects the background level on the drum surface.
B. Density patterns 1 to 5 of five different gradation levels in cyan (C) and black (Bk) are
produced, respectively, on the surface of the PC Drum to let UN20 detect the amount
of toner attracted.
C. The toner density characteristics are detected through these steps of A and B and
according to the solid level of cyan (C) and black (Bk) detected by "AIDC Offset
Adjustment." (See the chart below.)
D. Requirements of the amount of toner attracted (a, b and c) for AIDC detection are plot-
ted on the chart.
E. Of density patterns 1 through 5, the ones that are closest to a, b and c, respectively
are selected.
F. The three density patterns selected are used in AIDC detection.
These operations are performed while the PC Drum turns one complete turn.
(V)
Background Level
1
UN20
2
Output
3
4
a b
Amount of Toner Attracted
M-14
Solid Pattern
5
c
1144M162CA
(mg/cm ) 2