Development - Xerox Phaser 7500 Service Manual

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Development

Phaser 7500 Printer Service Manual

The electrically charged toners adhere to the electrostatic latent image on the

Drum surface to form a visible image (a toner image that can be seen) on it. This is

performed in parallel for each color - Yellow, Magenta, Cyan, and Black.

The Toner in the Cartridge is transported into the Developer Housing

Assembly by the Agitator and Auger that are driven by the Dispense Motor.

Toner Cartridge

The Toner and the Developing Beads (toner + carrier) in the Developer

Housing Assembly is agitated by the Auger, and then supplied to the Magnet

Roll that is located close to the Drum surface. Friction generated by the

agitation charges the toner and the carrier (toner becomes negative and

carrier becomes positive) and causes them to stick together by mutual

electrical attraction. Since the carrier is a magnetic substance, it is attracted to

the magnetized Magnet Roll and formed into an even layer by the Trimmer.

The Magnet Roll surface is covered with thin semi-conductive sleeve. DB

(Developing Bias) voltage is supplied from the HVPS to this semi-conductive

sleeve. The DB voltage consists of overlapping AC voltage and negative DC

The DC voltage is used to maintain the Magnet Roll at a constant negative

potential compared to the Drum conductive layer. Therefore, sections of Drum

surface where the negative charges have not been reduced will have lower

potential than the Magnet Roll, while sections where the negative charges

have been reduced will have higher potential than the Magnet Roll.

The AC voltage is used vibrate the toner on the Magnet Roll surface so that it

can be transferred more easily. Hence, the negatively charged toner is only

attracted to the sections with reduced negative charges on the Drum surface

(the electrostatic latent image) to form a toner image on the Drum. (Since the

attraction of the positive charge on the Drum conductive layer is stronger

than the repulsive force of the negative charge on the Drum surface, the toner

still gets pulled to the Drum despite being affected by repulsive force of the

Theory of Operation

Developer Housing

(Developer Housing Assembly)

Dispense Motor