Panasonic FA-DS72, Service Manual & Parts Manual

Page: 36 / 402

Sub Assemblies
3-3
(2) Developing
• The developer mixing unit contains developer which is a mixture of fine powder
(non-magnetic toner) and fine ferrite carrier.
• The developer is mixed by the transport screw and the mixing mill. The toner
becomes charged ( + ) and the carrier becomes charged ( – ). The developer
is magnetically stuck on the aluminum sleeve of the magnet roller, and the
magnetic brush is formed.
The developer is transfered counterclockwise in the rotating direction of the
sleeve.
The height of magnetic brush is controlled by the gap between the doctor blade
and the sleeve surface.
• The drum with an electrostatic latent image (negative charge) is rotating
clockwise and makes contact with the magnetic brush.
• The sleeve is charged opposite of the drum and an electric field is formed. The
positive toner is stuck on the electrostatic latent image on the drum.
• The sleeve has applied ( – ) bias voltage, which prevents the drum from covering
with toner. The distance between the drum and the sleeve is controlled with
the spacer rings.
Amount of developer Approx. 650 g
Initial toner density 4.0 %
DSD 0.8 mm
BSD 0.61 mm
Developing bias voltage –250 V reference
N2
N1
S1
S2
S3
N2
Reference:
• The twin field magnet roller presents enhanced developing performance by
a wider developing area which results from two pole peaks (S1 and S2 pole)
facing the drum surface.
• N2 through S3:Attract the developer to the sleeve from the mixing mill.
• S3 pole:
Raise the head of developer and control the head height with
the doctor blade.
• N2 through S1: Transfer the developer to the developing position.
• N1 through N2: Separate the developer from the sleeve.