Canon NP6012F Service Manual page 60

3. Turning On and Off the Scanning
Lamp
a. Outline
When pre-activation pre-heating is over,
the microprocessor (QlOl) on the DC con-
troller PCB instructs the microprocessor
(Q501) on the composite power supply PCB
to generate the scanning lamp on signal
(FLAON*). At this time, the fluorescent lamp
driver circuit operates to apply the output of
the primary side of the main transformer
(T102) to both ends of the scanning lamp so
as to turn on the scanning lamp at a high fre-
quency.
5. Controlling (automatic)
the
Fluorescent
Lamp Intensity (ALVC control)
The ,copier executes ALVC control in which
the ON voltage of the scanning lamp is automati-
tally corrected to prevent changes in the copy
images caused by deterioration of the photosen-
sitive drum.
4. Controlling the Intensity of the
Scanning Lamp
a. Outline
The intensity of the scanning lamp is
controlled by the microprocessor (Q501) on
the composite power supply PCB.
The intensity sensor checks the intensity
of the scanning lamp and generates activa-
tion power to suit the intensity. The micropro-
cessor, on the other hand, finds out the
intensity of the scanning lamp based on the
activation power to send the scanning lamp
on signal (FLON*) to the on control circuit.
b. Intensity Lower Than the Specified
Value
The microprocessor increases the duty
ratio of the scanning lamp on signal (FLON*)
sent to the fluorescent lamp driver. The fluo-
rescent lamp driver, in turn, increases the
current flowing to the scanning lamp, there-
by increasing the intensity of the scanning
lamp.
c. Intensity Higher Than the Specified
Value
The microprocessor decreases the duty
ratio of the scanning lamp on signal (FLON*)
sent to the fluorescent lamp driver. The fluo-
rescent lamp driver, in turn, decreases the
current flowing to the scanning lamp, there-
by decreasing the intensity of the scanning
lamp.
3-22 COPYRIGHT 0 1995 CANONINC. CANON NP6012/NP6012FINP6212 AEV.I SEPT.1995 PRlNTEDINJAPAN(IMPAIMiAUJAPON)