Ricoh Di-C1.5a Manual page 125

Automatic Line Position Adjustment
The spaces between the lines are measured by
the front, center, and rear ID sensors. The
controller takes the average of the spaces. Then
it adjusts the following positions and
magnification.
Sub scan line position for CMY
Main scan line position for CMY
Magnification ratio for CMY
Skew for CMY
This process prevents:
Color registration errors
Skew
Slide 125
Color registration errors: These are when the four color toner images (CMYK)
are not written exactly on top of each other)
Sometimes, this type of error is called 'color shift'. This is not the correct
term. Color shift is a change in the actual color.
In this model, the improved mechanisms have reduced color registration
errors a lot. This means that the default setting for 'black overprint' is
changed to 'off'.
When black overprint is on, if there is black superimposed on a color image,
the black toner is superimposed on the color toner image. This means that
a lot of toner is deposited on the paper and scattering can occur.
When black overprint is off, if there is black superimposed on a color image,
color toner is not deposited on the places where black toner will be. This
reduces the quantity of toner. But, if color registration is not good, a white
gap could appear at the border between the color toner area and the black
toner area.
Skew: The main scans of the four laser beams across the OPCs must be
parallel. If not, the four color toner images will be skewed in relation to each
other.
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