User manual

95.08.23.11.29
Color LaserWriter 12/600 PS Basics & Theory 1–50
Stage 2: Developing
In this stage, the toner is placed on the electrostatic latent image on the
photosensitive drum, making the image visible.
Step 3:
Developing
The toner used for the printer is a single-component nonmagnetic toner
composed of resin. This toner is unique for its insulating property, and
is charged with negative potential by friction between the rotating
cylinder and blade surface.
The toner comes in four colors: magenta, cyan, yellow and black. Each
is contained in its own toner cartridge. Each toner cartridge is housed
within the toner carousel and is sequentially advanced to the photosen-
sitive drum in line with the rotation of the carousel. See “Carousel
Rotation” later in this chapter.
The laser-beam-irradiated area on the photosensitive drum is higher in
potential than the toner negatively charged on the cylinder. When this
area comes close to the negatively charged toner on the cylinder, the
toner jumps and adheres to the drum surface due to the difference in
potential between the drum surface and the cylinder.
This effect is called toner projection development and makes the elec-
trostatic latent image on the photosensitive drum surface visible.
AC bias is applied to the developing cylinder for ease of projecting
toner to the photosensitive drum surface and in order to improve the
contrast of the output image. DC bias varies in response to density cali-
bration and the operation of the density control panel.
Blade
Photosensitive
Drum
AC Bias
DC Bias
Developing
Cylinder
Toner Feed RollerStirring Plate
Note: The irradiated areas on the photosensitive drum have a neutral
charge. For sake of clarity, these irradiated areas are shown as plus
signs (+) since their potential is higher than the charge of toner particles
on the developing cylinder.