Structure Of The Paper Feed Components - Canon BJC-3000 Service Manual

Part 5: Appendix

1.1.2 Structure of the paper feed components

The paper feed of this printer can be divided into the paper pick-up section, paper
feed section, and paper delivery section, structurally.
a) Paper pick-up section
If the paper meets specifications, it can be fed without selecting the paper type
mechanically. This printer therefore has no mechanical paper selection lever on the
auto sheet feeder.
When paper is stacked, the slanted ASF holds the paper to avoid misfeeding caused
by paper bending.
When printing starts, through the drive of the paper feed motor, the pick-up roller
starts to rotate. The paper is loaded in the sheet feeder such that one corner of it is
suppressed by the paper separator. When the pick-up roller rotates further, the
paper, with one corner held by the paper separator, is separated and fed to the
paper feed roller.
When printing on resilient paper like envelopes, as the paper is stiffer than the
return force of the paper separator's spring, the paper separator is pressed down to
feed the paper.
Pick-up Roller
Paper Separator
b) Paper feed section
Paper feeding during printing is controlled by the rotation of the paper feed roller.
Paper is fed in increments of 1/720 inch.
Between the pressure roller/paper feed roller and the spurs/eject roller, as the paper
in pressed onto the platen, the head to paper distance is stabilized. After the cut
sheets reach the print start position, they will be printed on over the platen.
c) Paper delivery section
This part is composed of the eject roller and spurs.
To prevent contaminating the paper's printed surface, the sharp tips of the spurs
press down on the printed side of the paper, onto the eject roller, and with the drive
of the eject roller, paper delivery is performed.
Paper
<Plain Paper Pick-Up>
Figure 5-2 Paper Pick-Up Mechanism
5-2
<Thick Paper Pick-Up>
BJC-3000