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4.1.3 Projection Lamp Voltage Control Circuit
The intensity of the light emitted by the Projection Lamp is adjusted to a
level optimum for the image density by controlling the voltage applied to
the Projection Lamp.
The exposure data optimum for film image density is determined through
auto exposure data sampling made during prescan.
This exposure data is output as a Projection Lamp clock from the Main
Control Board (PWB-BB) to the Projection Lamp Regulator (PU2).
The ON and OFF periods of the Projection Lamp clock extending 606
µsec. are varied to control the Lamp voltage. The longer the OFF time,
the
higher the Lamp voltage.
H
L
ON OFF
606 µsec
.
Projection Lamp clock