Toshiba e-STUDIO4500c Service Manual page 728

COPY PROCESS OVERVIEW
4. DRUM POTENTIAL SENSOR
The drum potential sensor in each PCU detects the drum potential. Changes in
conditions near the drum (heat, humidity, drum condition) change the drum
potential. The machine uses the output from this sensor to adjust the voltages
that are used during auto process control.
5. DEVELOPMENT
The magnetic developer brush of 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
The developed toner images are transferred from the drums to the ITB. Rollers
inside the ITB apply a high positive charge to the reverse side of the ITB. This
positive charge pulls the toner particles from the drum to the ITB.
7. 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.
8. DRUM CLEANING
First, a soft cleaning brush roller removes toner from the drum. Next, a
lubrication roller, with a lubricant bar behind it, cleans the drum. Finally, an
opposing cleaning blade removes remaining toner.
9. ID SENSORS, MUSIC SENSORS
Two ID sensors and three MUSIC sensors are in a straight line across the ITB.
At fixed intervals, the laser in each PCU writes an ID sensor pattern on each
drum surface (Y, M, C, K). These patterns are transferred to the ITB. The two
ID sensors above the ITB (one for black and one for Y, M, C) measure the light
reflected from each of the four patterns and output this data (Vsp) to the CPU.
This Vsp is used for toner supply control. The MUSIC sensors read a different
set of patterns to make adjustments to the laser main scan start timing, angle of
the 3rd mirror, and the drum drive speeds. The MUSIC sensors ensure that the
alignment of the images on the ITB is correct.
10. PAPER TRANSFER AND SEPARATION
A strong negative charge applied to the PTR idle roller repulses the image from
the ITB onto the paper. A paper discharge plate neutralizes the charge on the
paper and ITB. Then the curvature of the feed path allows the paper to
separate from the ITB.
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August, 2006