Ricoh B064 Service Manual page 388

COPY PROCESS OVERVIEW
3. LASER EXPOSURE
The processed image data from the scanned original is retrieved from the hard
disk and transferred to the drum by four laser beams, which form an
electrostatic latent image on the drum surface. The amount of charge
remaining as a latent image on the drum depends on the laser beam pulse
duration, which is controlled by the BICU.
4. DRUM POTENTIAL SENSOR
The drum potential sensor detects the change in drum potential, caused by
variable conditions around the drum (heat, humidity, drum service) and adjusts
the following voltages:
• Grid bias voltage (Vg or Vgrid)
• Laser diode power
• Development bias voltage (Vb)
5. DEVELOPMENT
The magnetic developer brush on the development roller contacts the latent
image on the drum surface. Toner particles are electrostatically attracted to the
areas of the drum surface where the laser reduced the negative charge on the
drum.
6. IMAGE TRANSFER
Paper is fed to the area between the drum surface and the transfer belt at the
proper time to align the copy paper and the developed image on the drum. The
transfer roller applies a high positive charge to the reverse side of the paper
through the transfer belt. This positive charge pulls the toner particles from the
drum to the paper while the paper is electrostatically attracted to the transfer
belt.
7. PAPER SEPARATION
Paper separates from the drum as a result of the attraction between the paper
and the transfer belt. The pick-off pawls also help separate the paper from the
drum.
8. ID SENSOR
The laser writes a sensor pattern on the drum surface. The ID sensor
measures the reflectivity of the pattern and outputs this data (Vsp) to the CPU.
The Vsp output signal is one of the factors used for toner supply control.
9. CLEANING
The cleaning brush removes toner remaining on the drum after image transfer
and the cleaning blade scrapes off all remaining toner.
10. QUENCHING
The light from the quenching lamp electrically neutralizes the charge on the
drum surface. After cleaning and quenching, the drum surface is ready for the
next cycle.
B064/B065 6-2 SM