Technical information

D. Controlling the Primary/
Transfer Corona Current and
the Grid Bías Voltage
1. Outline
Figure 3-27 shows the circuii which controls the
current for the primary/transfer corona unit and the
voltage level of the grid bias; it has the following
functions:
@ Turns the primaryltransfer corona current ON
and OFF;
@ Controlstheprimary/transfercoronacurrenttoa
constan! value;
@ Switches the grid bias voltage level of the pri-
mary corona unit.
@ Controls the grid bias voltage of the primary
corona unit.
Theoutputtotheprimarycoronaunit iscontrolled
toa constant value; the shield current is controlled to
eliminate the effects of environmental changes on
the corona discharge.
The primary corona current and transfercorona
current are turned ON and OFF by the high-voltage
output signa1 (HVTON).
The grid bias voltage level is switched by the grid
bias control signa1 (GRDON).
WI¶ OPERATIONS ANDTIMING
2. Turning the PrimaryiTransfer Corona
Current ON and OFF
@ When HVTON = 1,
bdifferential amplifier circuit goes OFF.
4variablepulsegeneratorcircuitgoesOFF.
bHigh-voltage transformer goes OFF.
0 When HVTON = 0,
bdifferential amplifier circuit goes ON.
bvariablepulse generatorcircuit goes ON.
b High-voltage transformer goes ON.
3. Controlling the Primary/Transfer Corona
Current Constant
If a corona current larger than the specific value
flows from the primary corona unit because of
changes in the environment. the level of the feed-
backsignal totheifferentialamplifiercircuit increases
andtheoutputofthecircuitdecreaseqthecondition
in turn decreases the corona current from the pri-
maryltransfer corona unit, thereby controlling the
current to a specific value.
If an over-current flows on the output side of the
high-voltage transformer used for primary/corona
unit, the limit control mechanism is activated to keep
the flow to a specific value.
r
DC controller PCS
High-voltage transler (HVT)
1
7.
Primary corona unit
3-28
Figure 3-27
COPYRIGNT 0 1992 CANON ING.
CANON NPZ12O/ZMO REY.0 MAY 1990 PRINIKI IN JAPAN IIMPRIME AU JAPONI