Gestetner G060, Service Manual

Page: 639 / 1106

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IMAGE PROCESSING
SM 6-7 G570
6.2.2 SBU BLOCK DIAGRAM
Signal Processing
1. Signal Amplification
•
Odd-pixel and even-pixel RGB analog signals from the CCD are amplified by
operational amplifiers.
2. Signal Composition
•
The amplified signals (even-pixel and odd-pixel for each RGB color) are
combined by the MPX circuit after A/D conversion.
A/D Conversion
•
The analog signals (CCD output) are converted to 10-bit (1024 gradations) digital
signals.
White Level Correction:
•
White reference plate scanned before the original.
•
Data is updated before each scan.
•
Corrects for variations in the white level across the page, including irregularities
in the CCD and the optics across the main scan.
Others
The SBU controller exchanges the R and B signals if the original is scanned by
using ARDF.
Analog Amplifier
A/D Converter
C C D
SBU
Analog Amplifier
A/D Converter
Analog Amplifier
A/D Converter
S B U
Controller
R ( B ) O
E
O
E
O
E
G
B ( R )
10 bit
10 bit
10 bit
Field
M e m o r y
E E P R O M
Field
M e m o r y
A S I C
IPU
10 bit
10 bit
10 bit
R
G
B
8 bit
8 bit
8 bit
G570D901.WMF