DRUM UNIT 15 February 2006
6-60
6.8.11 PROCESS CONTROL
Drum potential gradually changes for the following reasons:
• Dirty scanning optics (lenses, mirrors), dirty exposure glass
• Dirty charge corona casing, grid plate
• Deterioration of drum sensitivity
What Happens at Power On
Here is a description of what happens while the fusing temperature is below 100
o
C
immediately after the main power switch is switched on (process control must also
be enabled with SP3901, or this will not happen).
At any time, this process can also be executed manually by using SP2962.
However, process control must be enabled with SP3901 and the fusing
temperature must be below 100
o
C, or this will not work.
1. Potential sensor is calibrated.
2. Drum starts first rotation after fusing temperature reaches 140
o
C.
3. Readout from the potential sensor is used to adjust:
• Development bias (Vb)
• Grid voltage (Vg)
• Laser diode (LD) power.
NOTE: This step occurs only if process control is enabled with SP3901 (Auto
Process Control On/Off Setting). If this SP is disabled, then:
• Development bias is set to the value stored in SP 2201 001
• Grid voltage is set to the value stored in SP 2001 001
• Laser power is set to a fixed value
4. ID sensor is calibrated (Vsg).
5. TD sensor is calibrated (Vref).
NOTE: These calibrations are used to determine toner supply, so it is very
important that the developer be initialized with SP2963 (Installation
Mode) at installation and with SP2801 (TD Sensor Initialization) when
the developer is replaced.
Any SC codes that are generated during auto process control are logged in the
memory and do not appear. The machine will continue to operate.
B140 series: Steps 2, 4, and 5 are not done if SP3904 is set to 0 (default) or 1.
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