Brother DCP-9010CN Service Manual page 75

■ Developing bias voltage
Toner in use tends to have a low print density at the beginning of its use, but the density
gradually becomes higher after a certain period of use if the bias voltage is kept at a certain
level during development.
The properties of the toner is controlled by means of the developing bias voltage. The values
are varied according to counts of the amount of toner used immediately after a toner cartridge
is changed so that excellent print quality of even contrast can be obtained constantly from the
printing start time to the stop time.
In addition, the developing bias voltage of each toner cartridge is periodically corrected so as
to eliminate variation in the density of the four colors.
When the new toner detection mechanism detects the change to a new toner cartridge, the
developing bias voltage is reset.
[Density]
[Voltage]
Note:
If a toner cartridge in use is replaced to a cartridge which has previously been in use before
reaching a toner life, the developing bias voltage will become incorrect and the density will
be changed, and consequently it may cause print failures. Toner cartridges being used
must not be replaced with other ones.
Actual control
Print density
Developing bias voltage
[Used toner amount]
Fig. 2-17
2-20
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