Service manual

The video signal for each pixel obtained during image scanning is corrected
by the shading circuit as follows:
(Video data for each pixel) – (Black shading data for each line)
(White shading data for each pixel) – (Black shading data for each line)
x
255
The white shading data are updated before every first scanning (2C and 4C
mode) or every scanning (1C mode). The black shading data are updated
every scan line. The white shading data corrects the image data for
irregularities in the CCD and the optics across the main scan. The black
shading data corrects the image data for any changes in black level with
time, as the machine scans down the page.
(2) Main Scan Timing
The GA1 block generates the synchronization signal for the CCD to scan
and for feedback.
(3) Sub Scan Timing
The GA1 and GA2 blocks generate the synchronization signal for the scan
line correction.
IMAGE PROCESSING
A166/A187/A189 2-42 SM
CÓPIA NÃO CONTROLADA
CÓPIA NÃO CONTROLADA