40931201TH Rev. 4 24 /2.3.2 Electro-photographic processThe electro-photographic processing is outlined below. Figure 2-5 shows the electro-photo-graphic printing process.1 ChargingThe surface of the image drum is uniformly charged with negative charges by applying anegative voltage to the charge roller.2 ExposureLight emitted from the LED head irradiates the negatively charged surface of the image drum.The surface potential of the irradiated part of the image drum surface is lowered, so that anelectrostatic latent image associated with the print image is formed.3 Developing and toner recoveryWhen the negatively charged toner is brought into contact with the image drum, it is attractedto the electrostatic 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 rollerby static electricity.4 TransferWhen paper is placed over the image drum surface and a positive charge, opposite in polarityto the toner, is applied to the reverse side of the paper from the transfer roller, the toner isattracted by the positive charge and is transferred to the paper. As a result, the toner imageformed on the image drum is transferred to the paper.5 Temporary cleaningResidual toner that remains on the image drum without being transferred is made uniform bythe cleaning roller and is temporarily attracted to the cleaning roller by static electricity.6 FusingThe toner image transferred to the paper is fused under heat and pressure.Figure 2-6 shows an electro-photographc process timing chart.
