Toshiba e-studio 250 - Page 119

December 2002 TOSHIBA TEC 7 - 11 e-STUDIO160/200/250 SCANNER
e-STUDIO200/250 series
The motor control IC (IC4) turns the LAMP signal to the HIGH level.
The transistor (Q3) turns on and the LAMP turns to the GND level.
The transistor (Q3,Q5,Q7) on the Inverter PWA turns on to apply +24V to the switching regulator
IC(IC1).
IC1 turns on FET (Q1).
Current flows through the Np winding of the transformer (T1) where energy is accumulated.
IC1 turns off Q1. At this time, the energy accumulated in winding Np is supplied from the Ns
winding of the secondary circuit as electric power. As IC1 turns on and off Q1 in this way, high-
frequency electric power is supplied from the secondary circuit of T1 and fed to the exposure lamp
for lighting.
IC1 monitors the input voltage and controls the on/off time in response to the fluctuation in the
input voltage. It shortens the on time of Q1 when the input voltage rises, and extends the on time
of Q1 when the voltage drops.
IC1
Scanner MPU
Exposure lamp
IC4
Motor
control IC
IC1
Switching
regulator
CN2
PG
PG
CPUA0~19
Scanner control PWA Inverter PWA
CPUD0~15
LAMP
58
+24V
F1
VCC
Q3
Q2
Q5
2
1
3
1
3
2
1
3
14
1
Q2
CN1
CN2
Np Ns
T1
Q7
08-05-02