In this block, the machine uses a toner projection method in which it deposits toner over the surface of the photosensitive drum, thus turning the static image into

a visible image. The developer used here is a 2-component developer, composed of non-magnetic toner and carrier.

Step 3: development

The drum unit consists of a photosensitive drum, developing cylinder, and a blade.

The developer is composed of toner (mainly of resin and dye) and carrier (iron powder) mixed in a specific ratio. The friction occurring between toner and carrier

causes the toner to become negatively charged and carrier to become positively charged.

The developer adheres to the surface of the developing cylinder by the work of a fixed magnet, and a blade is used to form a uniform layer of developer.

At this time, the areas of the photosensitive drum exposed by the laser beam will have a positive potential in relation to the developing cylinder.

As a result, the toner charged to a more or less identical potential as the developing cylinder will move to and stick to the areas of the photosensitive drum exposed

by the laser beam. This phenomenon is referred to as "toner projection," and is used to turn the image on the surface of the photosensitive drum into a visible image.

The "light area" of the photosensitive drum is charged to a negative potential; however, the diagram below shows it as being charged to a positive potential, indi-

cating that its potential is higher than that of the developing cylinder when the cylinder is used as the reference.

Toner

Carrier

Developing cylinder

AC bias

DC bias

Toner feedscrew A

Toner feedscrew B

-V

Time (t)

Blade

F-7-6