Development (Step 4) - Canon 1000 Service Manual

F. Development (step 4)
Magnet
Cylinder
Photosensitive
drum
Stray-toner collecting electrode
Figure 2-107
The process in which the latent static image
on the surface of the photosensitive drum is turned
into a visible image is called development.
Since the CLC1000 is designed so that the
areas on the surface of the photosensitive drum
exposed to a laser beam will attract toner, the toner
is charged to a negative potential (the same
potential as in primary charging).
As shown in Figure 2-107, the developing
assembly consists of a developing cylinder and a
magnetic blade. The developing cylinder in turn
consists of a fixed magnet and a cylinder which
rotates around the magnet.
The developer is composed of toner (mainly
resins and dye) and carrier (iron powder) mixed at
a specific ratio. The toner and the carrier are
charged to a negative and a positive potential,
respectively, by friction against the rotating
cylinder.
The developer is held in the form of a brush
over the surface of the cylinder within the magnetic
field of the fixed magnet, and is deposited in a
uniform layer by a blade.
COPYRIGHT © 2001 CANON INC.
Blade
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
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Photosensitive
drum
Toner
Figure 2-108
Double blanking pulses and a DC bias
(negative component) are applied to the
developing cylinder to improve development
efficiency and reproduction of highlighted areas,
resulting in a developing bias with a larger negative
than positive component.
During copying, toner is attracted to the light
areas of the photosensitive drum because of the
drum surface potential and the negative potential
of the developing bias, turning the latent static
image into a visible image. Excess toner is then
repelled by the photosensitive drum because of the
drum surface potential and the positive component
of the developing bias.
The electrode plate under the developing
cylinder is supplied with a high voltage (positive) to
attract stray toner, thereby preventing soiling of the
inside of the machine.
2. COPYING PROCESS
Blade
Cylinder
Magnet
2-5