Kyocera FS-1920 Service Manual page 132

2FP/2FY/2FR
The latent image constituted on the drum is developed into a visible image. The developing roller contains a 4-pole (S-N-
S-N) magnet core and an aluminum cylinder rotating around the magnet core. Toner attracts to the developing roller
since it is powdery ink made of black resin bound to iron particles. The magnetic blade to which an auxiliary magnet
piece is attached is positioned approximately 0.3 to 0.4 mm above the developing roller. It constitutes a smooth layer of
toner in accordance with the revolution of the roller.
Magnetic blade
Magnet piece
Magnetism
0.1 mm
Drum
Toner
Developing roller
The developing roller is applied with the AC-weighted, positive DC power source. Toner on the developing roller is given
a positive charge. The positively charged toner is then attracted to the areas of the drum which was exposed to the laser
light. (The gap between the drum and the developing roller is approximately 0.3 mm.) The non-exposed areas of the
drum repel the positively charged toner as these areas maintain the positive charge. The developing roller is also AC-
biased to ensure contrast in yielding by compensating the toner's attraction and repelling action during development.
2-1-14
0.3 to 0.4 mm
N
S
S
N
N
S
Magnet core
Figure 2-1-14 Development
High
voltage
unit
150 V DC + AC
B
Developing bias
output
Engine board
HVCLK
YC5-8
CN2-11