Canon MultiPASS C50 Service Manual page 250

Part 2: Printer
2.8 Optimum Printing Direction Control
To prevent vertical misalignment of the printed characters, etc., when printing data is printed continuously
in the direction of the paper feeding direction, printing is executed with the carriage moving from only one
direction.
However, when the printing in the paper feeding direction is not continuous, since vertical misalignment is
not so noticeable the printing direction is alternated so that printing is also executed from the opposite
carriage direction. This improves the throughput.
If four or more successive null rasters are detected in the lower (in the direction of paper ejection) 64
nozzles (24 nozzles with a color BJ cartridge) for the printing data in the printer buffer during single-pass
printing, printing is executed up to the null raster. From the null raster onward, the printing is executed
from the opposite carriage direction. From the next raster onward, the printing is executed from the same
carriage direction until the direction changes again.
2.9 Ink Smear Control
Immediately after the printed sheet is ejected from the printer, the ink dries naturally on the Paper output
tray. If the next printed sheet is ejected before the ink dries on the preceding sheet on the Paper output tray,
the ink may be smeared when the sheet slides over the preceding one. To prevent this, a wait is applied
during the printing so that the sheet is ejected with a delay, giving more time for the ink on the preceding
sheet to dry.
When a black BJ cartridge is used (whose printing speed is faster) and high duty printing is completed, the
printer automatically detects the printing position of the high duty printing and the time elapsed from which
the printing starts.
It is not need to execute ink smear control when a color BJ cartridge is used.
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