Datasheet

78 Chapter 1

Hardware
The photosensitive drum now has toner stuck to it where the laser has written. The photo-
sensitive drum continues to rotate until the developed image is ready to be transferred to
paper in the next step.
Step 5: Transferring At this point in the EP process, the developed image is rotating
into position. The controller notifies the registration rollers that the paper should be fed
through. The registration rollers move the paper underneath the photosensitive drum, and
the process of transferring the image can begin, with the transferring step.
The controller sends a signal to the corona wire or corona roller (depending on which one
the printer has) and tells it to turn on. The corona wire/roller then acquires a strong positive
charge (+600VDC) and applies that charge to the paper. The paper, thus charged, pulls the
toner from the photosensitive drum at the line of contact between the roller and the paper,
because the paper and toner have opposite charges. Once the registration rollers move the
paper past the corona wire, the static-eliminator strip removes all charge from that line of
the paper. Figure 1.34 details this step. If the strip didn’t bleed this charge away, the paper
would attract itself to the toner cartridge and cause a paper jam.
FIGURE 1.34 The transferring step of the EP process
Print drum
Toner
Paper
Static-eliminator strip
Transfer corona wire
EP cartridge
The toner is now held in place by weak electrostatic charges and gravity. It won’t stay there,
however, unless it’s made permanent, which is the reason for the fusing step.
Step 6: Fusing In the final step, the fusing step, the toner image is made permanent. The
registration rollers push the paper toward the fuser rollers. Once the fuser grabs the paper,
the registration rollers push for only a short time more. The fuser is now in control of mov-
ing the paper.
As the paper passes through the fuser, the fuser roller melts the polyester resin of the toner,
and the rubberized pressure roller presses it permanently into the paper (Figure 1.35). The
paper continues on through the fuser and eventually exits the printer.
Once the paper completely exits the fuser, it trips a sensor that tells the printer to finish
the EP process with the cleaning step. At this point, the printer can print another page,
and the EP process can begin again.
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