Mar. 1999 © TOSHIBA TEC
7 - 9
6570/5570 SCANNER
7.5
Exposure Control Circuit
7.5.1
Overview
[A] The exposure control circuit is comprised of the following four blocks:
(1) Lamp regulator
This circuit applies voltage to the exposure lamp correspondent to the duty ratio of the PWM signal.
(2) CCD sensor circuit
This circuit reads the amount of light from the shading correction plate. This information is used to
compare the light intensity reflected from the original document and the light from the shading cor-
rection plate. Adjustments are made in the image processing circuit for enhancement of signals.
(3) Image processing circuit
This circuit converts the signals from the CCD into binary values and performs a series of image
processing operations such as gamma correction, shading correction, etc.
(4) Control panel
The duty ratio of PWM signal can be set at increments of 1% through the digital keys by the operator.
Note: The ON/OFF switching of the exposure lamp is carried out by a unique signal (EXPO-ON) sepa-
rate from the PWM signal.
Construction of exposure control circuit
1
4
5
2
6
3
7
8
9
PWA-CCD
PWA-CCD/PWA-SLG
Image processing
circuit
A/D
PWA-SLG
Main CPU
IC37
Original
Shading correction plate
Exposure lamp
Lamp
regulator
CCD sensor
Control panel
Key input
Содержание 4580
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Страница 252: ...8070 6570 5570 4580 FUSER UNIT 14 6A Mar 1999 TOSHIBA TEC ...
Страница 369: ...8070 6570 5570 4580 ADF 16 78 Mar 2000 TOSHIBA TEC 16 13 PC Board 1 PWA F LGC 794 ...
Страница 370: ...Mar 2000 TOSHIBA TEC 16 79 8070 6570 5570 4580 ADF 2 PWA F SEN 794 ...
Страница 374: ...Mar 1999 TOSHIBA TEC 18 1 6570 5570 PC BOARD 18 PC BOARD 1 PWA F SYS 300 ...
Страница 375: ...6570 5570 PC BOARD 18 2 Mar 1999 TOSHIBA TEC 2 PWA F MTB 300 ...
Страница 376: ...Mar 1999 TOSHIBA TEC 18 3 6570 5570 PC BOARD 3 PWA F LGC 300 ...
Страница 377: ...6570 5570 PC BOARD 18 4 Mar 1999 TOSHIBA TEC 5 PWA F MOT 300 4 PWA F ADU 300 ...
Страница 378: ...Mar 1999 TOSHIBA TEC 18 5 6570 5570 PC BOARD 6 PWA F SLG 300 7 PWA F SDV 300 ...
Страница 379: ...6570 5570 PC BOARD 18 6 Mar 1999 TOSHIBA TEC 8 PWA F PLG 300 ...