Kyocera FS-1900 Service Manual page 87

The latent image constituted on the drum A is developed into a visible image. The developing
roller B contains a 4-pole (S-N-S-N) magnet core C and an aluminum cylinder rotating around
the magnet core C. Toner attracts to the developing roller B since it is powdery ink made of black
resin bound to iron particles. The magnetic blade D to which an auxiliary magnet piece E is
attached is positioned approximately 0.3 to 0.4 mm above the developing roller B. It constitutes a
smooth layer of toner in accordance with the revolution of the roller.
E
Magnetism
0.1 mm
A
F
B C
The developing roller B is applied with the AC-weighted, positive DC power source. Toner F on
the developing roller B is given a positive charge. The positively charged toner F is then attracted
to the areas of the drum A which was exposed to the laser light. (The gap between the drum A and
the developing roller B is approximately 0.3 mm.) The non-exposed areas of the drum A repel the
positively charged toner as these areas maintain the positive charge. The developing roller B is
also AC-biased to ensure contrast in yielding by compensating the toner's attraction and repelling
action during development.
FS-1900
D
0.3 to 0.4 mm
N
S
S
N
N
S
Figure 4-1-10 Development
150 V DC + AC
B
Developing bias
output
4-12
Engine board
High
voltage
unit
HVCLK
YC204-8
CN2-11