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(4) Developing
Toner is attracted to the electrostatic latent image on the image drum surface, converting it
into a visible toner image. Developing takes place through the contact between the image
drum and the developing roller.
1 As the toner supply roller rotates while rubbing on the developing roller, a friction
charge is generated between the developing roller and the toner, allowing the toner
to be attracted to the developing roller (the developing roller surface is charged
positive and the toner, negative).
Charge roller
Doctor blade
Toner supply roller
Developing roller
Image drum
2 The toner attracted to the developing roller is scraped off by the doctor blade, forming
a thin coat of toner on the developing roller surface.
3 Toner is attracted to the exposed portion (low-potential part) of the image drum at the
contact of the image drum and the developing roller, making the electrostatic latent
image visible.
–300V
–750V –100V –750V –750V
Developing roller
Toner
Image drum
–100V
Exposed
part
Exposed
part
An illustration of activities at the contact point of the
image drum surface and the developing roller (arrow
marks denote the direction of the electric field).
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