August 2006 PROCESS CONTROL
6-85
Detailed
Descriptions
Calculate Development Gamma
The laser diodes write a 10-grade potential sensor pattern on each drum. To make
the different densities, the machine changes the PWM duty of the laser diodes.
At this step, the development gamma (development capacity) is measured. The
necessary potentials are calculated. Next, the target values (necessary potentials)
for Vd (charge potential), Vb (development bias), and Vpl (drum potential after
exposure) are retrieved from the Potential Reference Table.
At this time:
• Development gamma must be in the range 0.3 to 6.0 V
• Development start voltage (Vk) must be in the range –150 to 150 V. This
development start voltage is used to indicate whether the developer has
deteriorated. However, this is only a rough measurement that can be affected by
ambient conditions and the condition of other electrical components.
ID Sensor Pattern Detection Errors
SC Codes SP3821 Procon OK?
For More Details:
SC410~SC413 55~56, 59
SC414~SC417 57~58
See "Process Control Troubleshooting" in
Section "4. Troubleshooting".
Adjust for Residual Potential
The laser unit fires at full power (PM = +127, PWM = 63) to compensate for a
possible high residual potential on the drum. Next, the amount of residual potential
is detected, and the charge is adjusted to achieve the target potential.
The detected Vr must be less than –200V.
Vr (Residual Potential) Errors
SC Codes SP3821 Procon OK?
For More Details:
SC432~SC435 62 See "Process Control Troubleshooting" in
Section "4. Troubleshooting".
Adjust Vd
This step adjusts Cdc, the charge applied to adjust dc bias target Vd. Vd is the
targeted bias after Vr (residual potential correction).
The targeted potential of Vd must be within ±5V.
Vd (Development Bias) Errors
SC Codes SP3821 Procon OK?
For More Details:
SC420~SC423 63 See "Process Control Troubleshooting" in
Section "4. Troubleshooting".
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