Analog Image Processing - Canon 1000 Service Manual

3. OPERATION AND TIMING
C. Analog Image Processing
The analog video signals from the CCD driver is processed on the analog processor PCB (gain
adjustment) and converted into digital video signals. The analog processor PCB has the following functions:
1 Corrects the gain of R, G, and B analog video signals.
2 Corrects the offset in the CCD output.
3 Executes A/D conversion.
4 Supplies power to the CCD driver.
5 Generates clock signals for CCD driver and main scanning direction sync signals.
Analog processor PCB
R analog video signal
ODD,EVEN
G analog video signal
ODD,EVEN
B analog video signal
ODD,EVEN
CLK/SP
The analog video signals from the CCD driver are subjected to gain correction and offset correction:
specifically, the output voltages in the absence of light are made even (offset correction) and the ratio of
amplification is made constant to even out the photo-conversion efficiencies of CCD pixels (gain adjustment)
The RGB video signals of the odd and even channels are integrated into a single channel in the offset
correction block and are converted into 8-bit digital signals (A/D conversion) according to the voltage level
and sent to the image processor PCB.
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COPYRIGHT © 2001 CANON INC.
ODD,EVEN
Offset correction
Gain correction
SH/SEL
Sync control
clock generation
Figure 3-304
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
R digital video signal
8
G digital video signal
8
B digital video signal
8
ADCLK
Main scanning
direction signal
(HSYNC)