Lamp Regulator Circuit - Toshiba 1550 Service Manual

7.6 Lamp Regulator Circuit

The lamp regulator performs control to maintain the amout of light of the exposure lamp at a constant
value by monitoring the AC input voltage.
(Method) • Detects the AC input voltage.
• Changes the input voltage to a DC voltage approximate to its effective value by means
of the waveform shaping circuit.
• This DC voltage is compared with the reference voltage made by shaping the pulse
signal and is amplified.
• Based on the reference voltage and the input voltage, the trigger pulse generation cir-
cuit generates trigger pulses in synchronism with the frequency of the power supply.
• Controls the conduction angle of the triac.
The voltage applied across the lamp is kept consistent.
Waveform
shaping circuit
1550/1560 OPTICAL
Trigger pulse
(PWM)
generation
Pulse signal
circuit
Pulse
Operational
waveform
amplifier
shaping circuit
7 - 22
Reference pulse signal setting circuit
Mar. 1998 © TOSHIBA