40718401TH Rev.5 22 /2.3.2 Electrophotographic ProcessThe electrophotographic processing is outlined below. The electrophotographic printing process isshown in Figure 2-4.1 ChargingThe surface of the image drum is charged uniformly with a negative charge by applying the negativevoltage to the charge roller.2 ExposureLight emitted from the LED head irradiates the negatively charged surface of the image drum. Thesurface potential of the irradiated portion of the image drum surface becomes lower, forming theelectrostatic latent image associated with the print image.3 Developing and toner recoveryWhen the negatively charged toner is brought into contact with the image drum, it is attracted to theelectrostatic latent image by static electricity, making the image visible.At the same time, the residual toner on the image drum is attracted to the developing roller by staticelectricity.4 TransferWhen paper is placed over the image drum surface, the positive charge which is opposite in polarityto that of the toner, is applied to the reverse side of the paper by the transfer roller. The toner isattracted by the positive charge and is transferred onto the paper. This results in the transfer of thetoner image formed on the image drum onto the paper.5 Temporary cleaningResidual toner which remains on the image drum without being transferred is evened out by thecleaning roller and is temporarily attracted to the cleaning roller by static electricity.6 FusingThe toner image transferred onto the paper is fused to the paper by heat and pressure.An electrophotographic process timing chart is shown in Figure 2-5.
