Gain Correction And Offset Correction Of The Ccd Output; A/D Conversion Of The Ccd Output - Canon Image Reader-A1 iR5000i Service Manual

2.3 Gain Correction and Offset Correction of the CCD Output

To correct discrepancies in the efficiency of photoconversion among pixels, the analog
video signals from the CCD are corrected: in gain correction, the rates of amplification are
standardized; in offset correction, on the other hand, the output voltage in the absence of in-
coming light is set to a specific level.

2.4 A/D Conversion of the CCD Output

The analog video signals of odd-number and even-number pixels after correction are con-
verted into 8-bit digital signals that correspond to specific pixel voltage levels by the A/D
converter.
COPIER/ADJUST>ADJ-XY>ADJ-Y (CCD read start position adjust-
ment)
It is used to adjust the parameter used determining the read start position in
main scanning direction.
Range: 0 to 400
(A change by '12' results in a shift of 1 mm.)
COPYRIGHT © 2001 CANON INC.
Decrease
Increase
Original
Vertical size plate
F03-205-01
2000 2000 2000 2000 CANON iR5000i/iR6000i REV.0 JUNE 2001
CHAPTER 3 IMAGE PROCESSING SYSTEM
Read start position
3-3 R