Ricoh A028 Service Training Manual page 15

Outline of Mechanism 1 July 1994
This is because the originals copied on the front and reverse side
are alternately copied due to the alternate paper feeding system.
As the margin can be adjusted by changing the original flash
(exposure) timing, the original stop on the exposure glass must
correspond to the adjusted flash timing. (If a margin is created at
the left, the flash timing is advanced. If a margin is created at the
right, it is delayed.) When the margin is created on the front and
rear of copies separately, two different flash timings alternate with
each other. If the difference in the flash timing between two
originals becomes greater, i.e. 15 mm (5/8") or more in the margin,
the original transportation cannot correspond to the alternate two
different flash timings due to the limit of the original transportation
speed.
For example, if a margin is created at the left on the front side of
copies, after an original for which no margin is created, the original
which has the margin must be transported to the exposure glass
faster than usual in order to catch up with the advanced flash
timing. If the margin is 15 mm (5/8") or greater, the original cannot
catch up with the advanced flash timing.
This copier has one more copying speed: 81 cpm. However, this
is not used in case of a slow down in the margin adjustment mode.
To enable 81 cpm, the copy mode for B4 size paper (B4 size copy
mode), where the images of 4 originals are produced for one
rotation of the OPC belt, must be used. In the A4 size copy mode
three originals are fed into the RDH from the stack original feed
tray before the first original is flashed. For the B4 size copy mode,
it is two originals. Due to this, the original transport speed in the
B4 size copy mode is almost the same as that in the A4 size copy
mode, even though the copying speed of the B4 size copy mode
is 81 cpm. Therefore, even if A4 size copies are made using the
B4 size copy mode, there is not enough margin in the original
transportation speed.
Duplex original to duplex copy mode
The front side of originals is copied during one cycle of
original feeding. The copies are stacked in the duplex
tray. At the same time the originals are inverted and
returned onto the original table as the originals do not
switch back, unlike the simplex original to simplex copy
or duplex copy mode. Due to this, the reverse side of the
originals is copied during the next cycle of the original
feeding. The images are copied on the reverse side of
the copies from the duplex tray and the duplex copies
are automatically delivered to the finisher shift tray, not
to the copier copy tray. The copies are stacked in page
order on the tray without the inversion of copies as in the
simplex originals to duplex copy mode.
To make more sets of copies, the above motion is
repeated. (Copies are always collated into sets.) This
means that the original feeding cycle is repeated twice
the desired number of copy sets.
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