II -
8
3.2.2
Developing stage
Development places particles of toner onto the areas of the drum that have been cleared of
charge by the laser beam. This makes a visible image. This printer uses the toner projection
development method with a single-component toner.
Blade
Stirrer
Developing cylinder
Cylinder
Magnet
DC bias
AC bias
Photo-
sensitive
drum
Figure 2.11
Note: The charges on the light areas on the photosensitive drum are shown as positive in this
figure. Actually they are negative, but they are more positive than the developing
cylinder and explanation is simplified by regarding them as positive.
As shown in Figure 2.11, the developing unit consists of a developing cylinder and rubber blade.
The developing cylinder rotates around a fixed internal magnet. The single-component toner
consists of magnetite and a resin binder, and is held to the cylinder by magnetic attraction. The
toner is an insulator, and acquires a negative charge by friction due to the rotation of the cylinder.
The areas on the drum that were exposed to the laser beam have a higher potential (are less
negative) than the negatively charged toner particles on the developing cylinder. When these
areas approach the cylinder, the potential difference projects the toner particles onto them. This
is called toner projection, and the latent image on the drum becomes visible.
Developing cylinder
surface potential
Drum surface
potential
(exposed area)
DC bias
Drum surface
potential
(unexposed area)
Time t
+V
0
-V
Voltage (V)
Figure 2.12
An AC bias is applied to the developing cylinder to help project the toner particles to the drum
surface and improve the contrast of the printed image. The center voltage of the AC bias (1600
Vp-p) varies with the DC bias voltage.
The IMAGE DENSITY ADJUSTMENT signal (sent from the Engine CPU to the high-voltage
power supply) changes the DC bias, and thus the potential difference between the cylinder and
drum. This changes the density of the print.
This printer has a stirring mechanism to supply toner in the cartridge smoothly to the cylinder.
Step 3
Development
Содержание 1660e - B/W Laser Printer
Страница 1: ...MECHANICS ELECTRONICS SERVICE MANUAL LASER PRINTER ...
Страница 108: ...Appendix 2 Paper Feed Size SW PCB Circuitry Diagram 1 1 A 2 CODE NAME UK2516000 B48K139 140CIR JW 27 95 P053 ...
Страница 109: ...Appendix 3 Main PCB Circuitry Diagram 1 7 CODE UK3787000 B48K294 295CIR 1 7 NAME A 3 ...
Страница 110: ...Appendix 4 Main PCB Circuitry Diagram 2 7 CODE UK3787000 B48K294 295CIR 2 7 NAME A 4 ...
Страница 111: ...Appendix 5 Main PCB Circuitry Diagram 3 7 CODE UK3787000 B48K294 295CIR 3 7 NAME A 5 ...
Страница 112: ...Appendix 6 Main PCB Circuitry Diagram 4 7 CODE UK3787000 B48K294 295CIR 4 7 NAME A 6 ...
Страница 113: ...Appendix 7 Main PCB Circuitry Diagram 5 7 CODE UK3787000 B48K294 295CIR 5 7 NAME A 7 ...
Страница 114: ...Appendix 8 Main PCB Circuitry Diagram 6 7 CODE UK3787000 B48K294 295 CIR 6 7 NAME A 8 ...
Страница 115: ...Appendix 9 Main PCB Circuitry Diagram 7 7 CODE UK3787000 B48K294 295CIR 7 7 NAME A 9 ...
Страница 116: ...Appendix 10 Control Panel PCB Circuitry Diagram 1 1 A 10 CODE NAME UK2527000 B48K143CIR ...
Страница 117: ...Appendix 11 Scanner LD PCB Circuitry Diagram 1 1 A 11 CODE NAME UK2674000 B48K165CIR ...
