Sony VPL-FX50 Manual page 65

the FET Q1008. When this current reaches the thresh-
old value corresponding to the peak current value
flowing into the chalk coil L1002, the comparator set
the FET Q1008 turned OFF.
The threshold value, by the multiplier, is sent to the
comparator as the product of the AC voltage waveform
by the output voltage of the control amplifier while the
FET Q1008 reserves OFF state until the current of the
chalk coil L1002 reaches zero.
With the PWM control of switching, the output is set
to maintain approx.345 ±10 V that is performed by the
R1042R1048 shunt resistor.
Maximum Switching
VPL-FX50
D1002
L1002
Control Circuit
Fig.2 Principle of Active Filter
Rulse Voltage
Current
Switching Current
Inductor Current
D1009
+HV
+
Q1008
C1013&C1016
0 V
IC1000
Fig.3 Voltage to Current Relative
D1002 : Bridge Rectifier
L1002 : Smoothing Choke coil
C1013,C1016 : Smoothing Capacitor
Q1008 : FET for Switching
D1009 : Smoothing Diode
IC1000 : Control IC
4-5