Toshiba e-STUDIO453 Service Manual page 87

• Switching of developer bias polarity
With the area which has no negative charge,
background fogging is decreased by switching
the bias to the positive polarity (approx. +150 V).
• Developer material
The developer material consists of a mixture of
the toner and carrier. The toner is charged to
the negative polarity and the carrier to positive
polarity due to the friction with each other caused
by mixing.
Toner : Mainly consists of the resin and carbon.
Carrier : Consists of the ferrite and resin coating
on its surface to provide consistent
frictional electrification.
Note:
If the developer material is used for a long time
(beyond its normal life span), the toner is caked
onto the carrier.
The charging performance of the carrier is low-
ered.
Symptom : 1. I mage density is lowered.
2. T oner scattering occurs.
3. B ackground fogging occurs.
Solution : Replace the developer material.
• Magnetic roller
- Magnetic brush development -
The south and north poles are arranged inside
the magnetic roller as shown in the right figure.
The developer material forms a brush-like fluff
which contacts the photoconductive drum sur-
face.

This is caused by the magnetic force lines be-
tween the south and north poles.
© 2003 - 2008 TOSHIBA TEC CORPORATION All rights reserved

Magnetic roller
3 - 5
04/01
Carbon
(5-10%)
5-20 µm
Resin (90-95%)
[Toner]
[Carrier]
Fig. 3-210
Toner
No frictional electrification occurs on
the area where the toner is caked.
Fig. 3-211
Photoconductive
drum
N
Fig. 3-212
e-STUDIO350/352/353/450/452/453
Ferrite
30-100 µm
Carrier
Magnetic force
line
COPY PROCESS
3