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C. Controlling the Scanning
Lamp
1.
Outline
The scanning
lamp (LAl)
is controlled
by the DC controller
PCB; see Figure 3-22.
Specifically,
the DC controller
l
turns the scanning lamp ON and OFF.
l
controls the intensity of the scanning lamp.
2.
a.
b.
Mechanism
Turning
the Scanning
Lamp ON and
OFF
The microprocessor
(Q303) on the DC
controller
PCB
controls
the
lamp
regulator.
The scanning lamp goes ON
when
the
scanning
LAMP
ON
command
(LAON)
is 'l',
and it goes
OFF when the signal is '0'.
Controlling
the
Intensity
of
the
Scanning
Lamp
The machine exerts phase control by
the
zero-cross
signal
(ZXDP)
to
stabilize the light intensity.
CT unit
I
The intensity
of the scanning
lamp
is
switched
between
when
the
black
'-
developing
assembly
is used and when the,
__
CT unit is used.
When the CT unit is used, the LIGHT
INTENSITY
CONTROL
command.
(m)
goes '1' to raise the lamp voltage
by about
3.5
V
higher
than
when
the
black
developing
assembly is used.
During
AE exposure,
however,
the
voltage (70 V) applied to the scanning lamp
remains the same.
The NP6020
adjusts
the copy density
using its development
bias; see p, 3-26.
c.
Error Protection
The condition
of the scanning
lamp is
monitored using the LIGHT signal (LGHT).
If the LIGHT signal (LGHT) is received
,----
by the DC controller
for about 20 set, the
error
detection
circuit
generates
the AC
SHUTGFF
signal
(ACOFF)
to force
the
relay
(KlOl)
on the AC driver/DC
power
supply PCB to go OFF, thereby
cutting AC
power supply (P. 3-45). In this case, E220
error is displayed.
ACOFF
DC controller
PcB-
Lamp reg&tor
PCB
Figure 3-22
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