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2. LAMP POWER SUPPLY CIRCUIT
(LAMP DRIVER)
2-1. Configuration
The lamp power supply cicrcuit receives a DC220 to
390V (primary side) from the system power supply and
provides a AC voltage (70 to 100V
the lamp) to turn on the lamp. Fig. 2-1-1 shows the block
diagram.
EMC GND
The DC voltage is supplied to CB1 from the main power
supply unit through an interlock switch. This voltage
becomes AC input x 2Ö2 (= 340V for AC120V input)
when the lamp is off. CB2 is a connector for the lamp on
control signal input (SCI) and lamp off control signal
output (FLAG). When +5V is applied to SCI (CB2-1) in
the standby on, I122 FET transistor turns on, the igniter
develops a high voltage pulse (5 to 25 kV), and the lamp
starts to light up.
at ever turning on
AC
Lamp Driver
L1
Stabilizer
R1
C1
C2
I122
Rs
Cs
1K
CB3
CB2-1
SCI
(optional)
Commu-
Igniter
tator
Control
Mains
isolated
I121
100nF
CB2-2
Common
Flag
Fig. 2-1-1
The pulse normally continues to be developed until the
lamp turns on (for max. 3s.). But if the lamp does not
turn on, I121 does not turn on, the voltage of CB2-3
develops high. I121 turns on and develops low after the
lamp turned on, the igniter circuit stops the operation.
Then the AC70 to 100V is applied to the lamp.
2-1
L1
L2
Lamp
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