Ricoh LDD250, Руководство по обслуживанию

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SCANNER AND OPTICS
C262/C265 6-16 SM
6.2.4 AUTO BACKGROUND CORRECTION
For the platen cover
For the ADF
Auto background correction mode can be used in Photo/Letter, Photo, and Pale
modes. The default setting does not allow the user to select auto background
correction mode. Use a user tool to enable this mode (Master Making/Print Settings
– Original Setting – Background Correction).
Auto background correction prevents the background of an original from appearing
on copies.
While scanning the original, the background density detection area [A] is also
scanned. This area [A] is a narrow strip at the start of the main scan line, as shown.
As the scanner scans down the page, the ECU board detects the peak white level
for each scan line, within this narrow strip only. From this peak white level, the ECU
board determines the reference value for the A/D conversion for the scan line. The
ECU board then sends the reference value to the reference controller on the SBU.
When an original with a gray background is scanned, the density of the gray area is
the peak white level density. Therefore, the original background will not appear on
copies. This feature corrects any changes in background density down the page,
because peak level data is taken for each line scanned.
75mm
10mm
0.5mm
Sub scan direction
C262D802.WMF
75 mm
C262D346.WMF
[A]