15 February 2006 DRUM UNIT
6-63
Detailed
Descriptions
LD Power
Finally, the machine determines the laser diode power that will be used during
copying. This is done as follows.
1. The laser power is changed to the value needed to write a halftone pattern to
the drum.
2. The potential sensor reads the potential, Vh, from this pattern.
Vh: Standard halftone drum potential
3. Vh should be –300 ± 20 V. If it is within this range, the current value of the laser
power will be used for copying.
• If it is not, the laser power changes by 3 units, and the process starts again
from step 1.
• The laser power cannot be changed by more than ± 60 units.
4. If Vh cannot be adjusted to this standard within 25 attempts, LD power is set to
the most recent value and SC314 (Potential Sensor Calibration Error 4) is
logged.
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