Magnet Roller - Minolta EP1080 Service Manual

7-2. Magnet Roller

The Magnet Roller of the Sleeve/Magnet Roller of this copier has the
following magnetic characteristics. Part of pole S2 before the principal N1
pole (i.e., the area marked as S2b in the Fig. below) provides a very weak
magnetic force. If developer is compacted and clogs at the Doctor Blade
and, as a result, part of the surfaces of the Sleeve/Magnet Roller is not
covered with developer, the nearby developer around S2b goes to those
uncovered surfaces because of its weak magnetic force. This helps prevent
blank lines from occurring on the copy.
The Sleeve Roller, onto which developer is attracted by the magnetic fields
of force set up by the poles of the Magnet Roller, turns to convey the
developer toward the point of development. It also means that the developer
fresh from the Developer Mixing Chamber is always brought to the point of
development.
As we noted earlier, the Imaging Unit integrates the Developing Unit with the
PC Drum into one body. Because of that, it is impossible to move the
Developing Unit against the PC Drum, thereby providing a certain distance
between the PC Drum and Sleeve/Magnet Roller. The Magnet Roller has
therefore been made movable: the Bushing is pressed by compression
springs thereby pressing the Positioning Collars on both ends of the Magnet
Roller against the PC Drum. This ensures a given distance between the PC
Drum and the Sleeve/Magnet Roller.
(Magnetic Pole Positioning)
Pole Having Weak
Magnetic Force
Movable Bushing
Compression Spring
Fixed Bushing
PC Drum
M-19