Epson EPL-N4000, Service Manual

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EPSON EPL-N4000/EPL-N4000+ Chapter 2 Operating Principles
Rev.B 71
2.4.3 Develop
The toner contained within the EP Cartridge has a slight magnetic
property that causes it to adhere to the Magnetic Roll. The Charge
Metering Blade (CM Blade) spreads the toner into a very thin layer on
the Magnetic Roll. Friction between the Magnetic Roll and the CM Blade
generates a small electrical charge that is transferred to the toner.
The surface of the Magnetic Roll is made up of a thin sheet of
conductive material. The HVPS supplies the Magnetic Roll with two
voltages; a DC voltage and an AC voltage. The DC voltage is used to
transfer toner from the Magnetic Roll to the surface of the drum. The AC
voltage agitates the toner on the Magnetic Roll, making toner transfer
easier.
The Magnetic Roll maintains a negative DC electrical potential.
Negative charged areas of the drum have a lower electrical potential, or
higher relative negative value than the Magnetic Roll. Discharged areas
of the drum have a higher electrical potential, or lower relative negative
value, than the Magnetic Roll. A discharged point on the surface of the
drum now appears less negative, or positive, in relation to the negative
charge on the Magnetic Roll.
The toner adhering to the Magnet Roll is always in contact with the
drum surface. When a less negative point on the drum (a discharged
area) comes in contact with the more negative charged toner on the
Magnet Roll, toner transfers from the Magnet Roll to that point on the
drum. There is now a visible toner image on the drum surface. The
image is called a developed image.
Figure 2-27. Developing
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