Canon NP6012 Service Manual page 67

Lamp
a. Outline
When pre-activation pre-heating is over,
the microprocessor (Q101) 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.
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 © 1895 CANON INC.
Lamp Intensity (ALVC control)