Canon imageRUNNER 2270 Service Manual page 192

CCD8 CCD7
Light-receiving block
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5.3.6.3 Gain Correction and Offset Correction of the CCD Output
The analog video signal generated by the CCD is corrected so that it will have a specific
level (gain correction); moreover, the output voltage occurring in the absence of incident
light is also corrected so that it will have a specific level (offset correction).
5.3.6.4 A/D Conversion of the CCD Output
The analog video signal is further converted into a digital signal that is suited to the voltage
level of individual pixels by the A/D converter.
5.3.6.5 Shading Correction (outline)
The output of the CCD is not necessarily even for the following factors even when the
density of the original is uniform:
1) Variation in the Sensitivity Among Pixels of the CCD
2) Variation in the Intensity of the Rod Lens Array
The machine executes shading correction to even out the output of the CCD. Shading
correction may be shading adjustment executed at power-on or shading correction executed
CCD6 CCD5
L L H H L
CCD2 CCD1
output
H L H H H L
Chapter 5
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0006-5933
0006-5936
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