Toshiba e-studio 160 - Exposure Lamp Control; Exposure Lamp Control Circuit - e-STUDIO160 Series

e-STUDIO160/200/250 SCANNER 7 - 10 December 2002 TOSHIBA TEC
7.5.2 Exposure Lamp Control Circuit
This circuit is made up of the motor control IC (IC4), and the transformer, capacitor and other peripheral
elements on the Inverter PWA and controls the lighting of the exposure lamp.
The circuit configurations are different on the e-STUDIO160 series and e-STUDIO200/250 series.
e-STUDIO160 series
The motor control IC (IC4) turns the LAMP signal to the HIGH level.
The transistor (Q3) turns on and the LAMP signal turns to the GND level.
The transistor (Q3) on the Inverter PWA turns on to apply +24V to the Inverter PWA.
The transistors (Q1, Q2) are biased by the starting resistors (R1, R2). At this time, either of Q1
and Q2 turns on due to the transistor characteristics.
The following explains a case where Q1 has turned on.
If Q2 has turned on, Q1 and Q2 should be substituted for each other.
Bias voltage of Q1 is produced in the Nb winding of the transformer (T1) to allow Q1 to completely
turn on. At this time, Q2 turns off because it is reverse biased.
When current flows through T1, the primary circuit resonates due to the Np winding and capacitor
(C1). This causes the bias voltage of the Nb winding to be reversed.
Q1 turns off due to the reverse bias voltage and Q2 turns on.
As Q1 and Q2 turn on and off alternately in this way, high-frequency voltage is produced in the
primary circuit of T1. This voltage is boosted by the Np winding and Ns winding and supplied to
the exposure lamp for lighting.
08-05-01
IC1
Scanner MPU
Exposure lamp
IC4
Motor
control IC
CN2
PG
PG
CPUA0~19
Scanner control PWA Inverter PWA
CPUD0~15
LAMP
58
+24V
ICP1
Q3
Q3
Q1
R1
C1
Np
T1
Nb
Ns
R2
Q2
2
1
1
4
3
2
1
3
CN1
CN2