Brother MFC-7220 - Page 57

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When the new toner detection switch detects that the toner cartridge is replaced with a new one,
the developing bias voltage is initialized at the same time.
The toner used for the printer has a property that print density is light first and gradually darker in
the course of usage. The developing bias controls the toner property so that the print density is
constant from first to last.
Tonerproperty Actualcontrol
[Usedtoneramount] [Usedtoneramount]
Printdensity
Biasvoltage
Biasvoltage
Printdensity
[Density]
[Voltage]
[Density]
[Voltage]
To always obtain a print result of a constant density, the printer counts the number of print pages
immediately after the toner cartridge is replaced and changes the bias voltage according to the
accumulated number of prints with the toner cartridge.
The bias voltage is changed with the steps described below:
(1) When the new toner sensor detects that the toner cartridge is replaced with a new (full) one,
the developing bias is set to 450V (initialized).
(2) After that, the bias voltage is stepped down according to the number of prints.
<Initialization Procedure>
(1) Open the front cover.
(2) Press the Options key.
(3) When using the starter toner
Press the keys in the order of *, 1, 0.
When using the standard toner
Press the keys in the order of *, 1, 1.
(4) Close the front cover.
 Counter reset during indication of “Toner Life End”
The counter resetting method during indication of “Toner Life End” depends on the cause of toner
life end and the condition of the inserted toner cartridge. Refer to the following table for details.
Toner Life End
(Toner empty)
Toner Life End
(Developer count full)
When a used toner is inserted
(Reset gear is at the position
of in use)
Toner exchange count: +0
Page counter of each toner: Continued
Coverage of each toner: Continued
Development bias: Reset (Default)
Not used.
When a new toner is inserted
(Reset gear is at the position
of factory set)
Toner exchange count: +1
Page counter of each toner: Reset (0)
Coverage of each toner: Reset (0)
Development bias: Reset (Default)