Magnification Change; Image Processing - Canon Color Image Reader - L1 Service Manual

2
Technology
Magnifi cation change
Magnifi cation change in main scanning direction
In main scanning direction, image is always scanned by 100% size at copyboard scanning
and DADF scanning, and then magnifi cation is changed at image processing on the main
controller block.
Magnifi cation change in sub scanning direction
In sub scanning direction, image is always scanned by 100% size at copyboard scanning and
DADF scanning, and then magnifi cation is changed at image processing on the main control-
ler block.
At image SEND, reading size is changed by 100% or 50% depending on the specifi ed resolu-
tion.
Service Mode
(Lv.1) FEEDER > ADJUST > ADJMSCN1
Zoom adj in 2-sided main scan way: front
(Lv.1) FEEDER > ADJUST > ADJMSCN2
Zoom adj in 2-sided main scan way: back
(Lv.1) FEEDER > ADJUST > ADJSSCN1
Zoom adj in 2-sided sub scan way: front
(Lv.1) FEEDER > ADJUST > ADJSSCN2
Zoom adj in 2-sided sub scan way: back
2
Technology

Image processing

Following is the main functions of image processing system.
•
CMOS (image sensor) Number of lines: 4 (R, G, B, B/W)
Number of photo cells: 7488 (each line)
•
Shading correction Shading adjustment
Shading correction
Analog image Digital image
processing block processing block
CMOS PCB Reader controller PCB
CMOS
line sensor
A/D
Analog
conver- Shading processing
image
sion
processing
Following is functions of each PCB of image processing system
CMOS PCB: Analog image processing, A/D conversion
Reader controller PCB: Drive of scanner drive unit, shading correction
Error code
E248 Error in EEPROM
-0001 Error when EEPROM power supply for reader controller PCB (PCB1) is charged.
-0002 Error during EEPROM for reader controller PCB (PCB1) is written.
-0003 Error during EEPROM for reader controller PCB (PCB1) is read after being written.
E423 Error in SDRAM
-0001 Error in the SDRAM access.
-0002 Error in the SDRAM verifi cation.
CMOS output gain correction, offset correction
The analog video signal from the CMOS is processed so that the rate of amplifi cation is even
(gain correction) while the output voltage in the absence of incident light is also processed for
a specifi c level (offset correction).
CMOS output A/D conversion
The odd-numbered and even-numbered pixel analog video signals after the foregoing correc-
tion are then converted into 10-bit digital signals by the A/D converter according to their pixel
voltage levels.
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In service mode
Performed per very copy
Controller block
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