HP Pro 4300 C9H70UT C9H70UT#ABA manual Image-formation system

Image-formation system

The image-formation system is the main system in the printer. It consists of five stages:

●Electrostatic latent (potential) image formation

During this operation a uniform negative charge is applied to the surface of the photosensitive drum in the print cartridge. The drum is then exposed to the laser beam from the laser/scanner which neutralizes portions of the drum to create the electrostatic latent image, which is invisable.

●Developing the image

Toner is applied to the drum. The image is now visible.

●Transferring the image

The toner is transferred to the media and the media is separated from the photosensitive drum.

●Fusing the image

Heat and pressure are applied to the media and the toner is permanently bonded to the media.

●Cleaning the transfer charging roller and photosensitive drum

Residual (left over) toner is cleaned off of the transfer charging roller (this toner is transferred to the photosensitive drum) and then off of the photosensitive drum.

When the DC controller PCA receives the print signal, it drives the main motor, which rotates the photosensitive drum (the HP LaserJet 4300 uses a separate print cartridge motor to rotate the drum), the developing cylinder, the primary charging roller, the transfer charging roller, and the fuser pressure roller.

The primary charging roller places a uniform negative charge on the surface of the photosensitive drum.Mogulated laser beams strike the drum to form an electrostatic latent image.

The latent image formed on the photosensitive drum changes to a visual image when toner on the developing cylinder is transferred to the drum. The transfer charging roller transfers the image to the media. The fuser applies heat and pressure to permanently bond the image on the media. Then, residual toner on the photosensitive drum surface is scraped off with the cleaning blade.

The cartridge has a toner sensor that detects the presence of the cartridge and the remaining toner level.

If the toner in the cartridge becomes lower than a specific level, or if there is no cartridge in the printer, an error message appears on the control-panel display. See “Alphabetical printer messages” on page 258 or “Numerical printer messages” on page 274.

118 Theory of operation Q2431-90912