Toshiba 4511, 3511 manual Details of Copying Process

3.3 Details of Copying Process

(1) Photoconductive drum

The photoconductive drum consists of two layers. The outer layer is a photoconductive layer made of an organic photoconductive carrier (OPC), and the inner layer is an aluminum conductive base in a cylindrical form.

The photoconductive carrier has a special property: when it is exposed to light, the electrical resistance it possesses increases or decreases with the strength of the light.

Example:

·Strong incident light→

Decreases resistance (works as a conductor.)

·Weak incident light→

Increases resistance (works as an insulator.)

[Formation of electrostatic latent images]

In the processes of charging, data reading, data writing, and discharging described below, the areas on the drum corresponding to colored areas on the original are deprived of negative charge, while the areas on the drum corresponding to white areas retain the negative charge. Thus it forms a negative charge image on the drum surface.

As this negative charge image on the drum is not visible to the human eye, it is called an “electrostatic latent image.”

(2) Charging

Charging is a process to apply charge evenly to the drum surface.

The charger wire produces negative corona discharge, which is controlled by the grid so that the drum surface is evenly charged with negative potential.

The surface potential on the drum is determined by the grid potential and is controlled to a fixed value by the grid control circuit.

	Photoconductive layer
	Base
	Structure of the photoconductive drum
	(Example of OPC)
	Fig. 3-301
	Time (t)
potential (V)	0
Surface	Colored area of original
	- 500

White area of original

Discharge Charging

-1000 process process

Electric potential of the photoconductive drum

Fig. 3-302

Main charger

Rotation of drum

Grid control circuit		High-voltage
		transformer
	Fig. 3-303

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November 2003 © TOSHIBA TEC 3 - 3 e-STUDIO3511/4511 COPY PROCESS