Toshiba 4580, Service Manual

Page: 52 / 379

6570/5570 COPYING PROCESS 3 - 4 Mar. 1999 © TOSHIBA TEC
(5) Development
Development is the process of converting the
electrostatic latent image into “visible image.”
The developing agent is “brushed” unto the
surface of the photosensitive drum by means
of magnetic roller(s). The developing agent,
commonly called “developer,” is coated with
toner (which has a minus/negative charge).
Toner is attracted to the latent image on the
drum surface on the areas whose surface po-
tential is lower than the developer bias voltage
of the magnetic roller. At this point, the latent
image becomes developed image.
Drum Magnetic roller
Toner
Carrier
(always attracted on to the
magnet)
Toner
Photoconductor layer
Aluminum base
Intermediate tones
White background
Image is not developed
by bias potential
Bias
voltage
White background Black solid
•
About Developing Agent
Two materials comprise the Developing
Agent (developer): the toner material and the
carrier material. The toner has a minus
(negative) charge applied to it and the de-
veloper, a plus polarity (positive charge).
Mixing and agitating the carrier material dur-
ing the mixing process produces electrostatic
charge of the material. This action produces
a plus polarity (positive charge) on the car-
Magnet
Magnetic roller
Bias voltage
–400 VDC
Drum
Carbon
(5 ~ 10%)
Resin
(90 ~ 95%)
[Toner]
Ferrite
[Carrier]
When the d potential of
the photosensitive drum
is lower than the
developer bias:
When the d potential of
the photosensitive drum
is higher than the
developer bias:
30 ~ 100 µm
5 ~ 20 µm
Toner
0
– 100V
– 200V
– 300V
– 400V
– 650V
Image is developed by toner