6570/5570 SCANNER
7 - 10
Mar. 1999 © TOSHIBA TEC
7.5.3
Control section
The control section consists of the folllowing 2 blocks:
1
Scanner CPU
Comprised of software, the main CPU calculates the voltage to be applied to the lamp according to
the normal mode and check mode.
2
PWM timer circuit
This comprised by the following circuit. The exposure data is converted to PWM signals by the
scanner CPU, and output to J9-26 via IC2 from the scanner CPU PWM output terminal.
[B] The exposure control circuit has two functions:
(1) Normal mode
The duty ratio of the PWM signal is controlled at 55% (lamp voltage : 61.25V).
(2) Check mode
Through input from the digital keys, the PWM signal output is varied from 30% ~ 70% to allow the
exposure to be set arbitrarily.
7.5.2
Lamp regulator function
The figure below shows a typical characteristic diagram. Control is performed so that a voltage across
the lamp voltage proportional to the duty ratio of PWM signal is produced.
Characteristic diagram of the lamp regulator
Lamp voltage
Actual-use range
Actual-use range
Setting for normal operation
50
10
55
90
PWM duty [%]
61.25
70
[V]
S-CPU
Lamp regulator
PWM
7407
IC2
J9-26
PS-ACC
LRG
Содержание 4580
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