Toshiba 4560 Service Manual page 77

7.5.5 Lamp regulator circuit
The lamp regulator monitors the AC input voltage to control the exposure lamp to a fixed intensity.
(Method) • The AC input voltage is detected.
• The waveform rectifying circuit rectifies the AC input voltage to a DC voltage approxi-
mated to the effective value of the input voltage.
• This DC voltage and pulse signal are rectified, and compared with the reference voltage
and amplified.
• According to the output, the trigger pulse generation circuit generates a trigger pulse
synchronous with the power source frequency.
• The energization angle of the TRIAC is controlled.
Makes the voltage at both ends of the lamp constant.
Waveform
rectifying circuit
Nov. 1997 © TOSHIBA
TRIAC
Trigger pulse
(PWM)
generation
Pulse signal
circuit
Pulse
Differential
waveform
amplifier
rectifying circuit
7 - 15
Reference pulse signal
setting circuit
4560/4570 OPTICAL