Process control adjusts the image creation process to maintain a constant image density. Process control is executed at the following times.

Trigger

Operative Condition

Notes

Power ON

  • When a certain time passes after the previous job end, AND:
    1. More than six hours pass after the last OPC drum operation (SP3-530-001).
    2. More than 100 full color copies or more than 250 B/W copies are made between the second latest power-on and the latest power-on.
  • When a certain time passes after the previous job end, OR, the change of temperature/humidity after the last OPC drum operation exceeds the following condition:
    1. The change of temperature is more than or equal to the threshold [deg] (SP3-530-002).
    2. The change of relative humidity is more than or equal to the threshold [%RH] (SP3-530-003).
    3. The change of absolute humidity is more than or equal to the threshold [g/m3] (SP3-530-004).

Default settings:
Time: 360 minutes

Temperature: 10 deg

Relative humidity: 50%RH

Absolute humidity: 6 g/m3

Other related SPs:

SP3-530-005/006

Except when recovering from an SC or jam

Job End

When the job end counter becomes more than the threshold.

Related SPs:

SP3-534-001/011

-

Job Interruption

When the job interrupt counter becomes more than the threshold.

Related SPs:

SP3-533-001/011

-

Non-use (Idle)

Non-use time becomes more than the value in SP3-531-001.

-

Manual Process Control

When SP3-011-001 is executed.

-

Toner End Recovery

When a Toner End is resolved.

-

Initial Setting

When an initial developer setting is completed.

-

Vc is the charge bias, which is applied to the charge rollers.

Vd is the potential of the unexposed (charged) drum.

The value of Vc is not equal to Vd.

For example, if applying a Vc of 700 [-V], the actual drum potential (Vd) tends to be about 650 [-V].

Vb is the potential when toner starts to stick to the drum (Development bias).

When the potential gets to Vb or greater, toner starts to stick to the drum in proportion to the potential. Development gamma is the coefficient showing the relation between the potential and the volume of toner adhesion.

In addition to the development gamma and the potential, the toner density in the developer needs to be controlled. This is done to maintain the proper toner density (the amount of toner adhesion).

The target for the toner density in the developer is when the output from the toner density sensor is Vtref.

Process Control is done as shown in the following chart, which includes development gamma determination, Vtref correction, and LD power control.