Dpi Resolution - Ricoh B234 Service Manual

6.10.6

1200-DPI RESOLUTION

Sub Scan
7
5
42.3 μm
(600 dpi)
0 LDA 1-0
1 LDA 2-0
2 LDA 1-1
3 LDA 2-1
The original is scanned at 600 dpi, then the 600 dpi output is boosted to 1200 dpi
1-bit data during image processing in the IPU.
This machine can produce an image at 1200 dpi by writing each dot twice, possibly
with two different values, depending on the results of image processing. This is
achieved with the LD unit, which has two laser diode arrays, each with 4 channels
which together produce 8 beams. As shown in the illustration above, the beams
from each laser diode are emitted in two parallel lines.
For copying, 1200 dpi is used. For printing, the default is 600 dpi, but 1200 dpi can
be selected.
The diagram shows how the two sets of four beams are interlaced to produce a
sub scan resolution of 1200 dpi.
There are two parallel rows of four beams, separated by 22.3 mm in the main scan
direction. In each of these rows, the beams are spaced at 42.3 micrometer
intervals (this is the same as 600 dpi).
The rows are also offset in the sub scan direction by 21.2 micrometers.
The net result is that we have dots at 21.2 micrometer intervals, which is the same
as 1200 dpi.
SM
3 1
22.3 mm
Main Scan
4 LDA 1-2
5 LDA 2-2
6 LDA 1-3
7 LDA 2-3
6-61
LASER EXPOSURE
2
0
4
6
21.2 μm (1200 dpi)
B234D938.WMF
B234/B235/B236/D101/D102/D103
42.3 μm (600 dpi)