Brother HL-3040CN - Manual (Page 2)

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When the toner reaches its life end as determined by either of these two methods, the printer
will notify users by displaying a message on the LCD. There are two messages indicated when
the toner nears or reaches its life end: “Toner Low” and “Replace Toner.”
“Toner Low” is displayed on the LCD when the optical sensor detects a certain amount of toner
has been used or when the number of rotations of the developer roller nears its maximum count,
“Replace Toner” is displayed on the LCD when the optical sensor detects that the
usable toner in the toner cartridge has dropped below the predetermined level, or when
the number of rotations of the developer roller reaches its maximum count.
When either of these occurs, the chemical properties of the toner remaining in the
cartridge have degraded to the point where poor print quality may occur. For that reason,
when “Replace Toner” is displayed on the LCD, print operations are suspended until
the toner cartridge in question is replaced with a new one.
The number of developer roller rotations that are counted may not only be for normal operations such
as printing and copying, but also for machine adjustments, such as Calibration and Registration.
 Calibration (Adjustment of Color Density)
To obtain stable print quality, the density of each toner cartridge needs to be maintained
at a fixed value. If the density balance between the colors cannot be kept, the tint becomes
unstable, and accurate color reproduction becomes unavailable. The toner density can
change due to chemical changes to the toner that affect its electrical charge, deterioration
of the developer unit, and temperature and humidity levels in the device.
Print density is maintained by changing the developer bias voltage, which provides the
baseline for electrical charges within the printer. When calibration occurs, the density level
adjustment test patterns are printed on the belt unit, and the density sensor reads them.
The density of each color read by the sensor and the density reference value are
compared. If any difference is found, the developer bias voltage is adjusted to make the
actual print density value match the reference value.
Calibration is mainly performed at the following times:-
- When a print command is received after a specified time has passed (the default is 72
hours).
- When the user manually selects calibration from the operation panel.
- When a used toner cartridge is replaced with a new one.
- When the printer senses that the ambient temperature has changed.
 Registration (Combination of Color Images)
In this device, the drum and developer unit are prepared for black (K), yellow (Y), magenta
(M), and cyan (C), respectively. Four color images are combined into one image, and
therefore color registration errors might occur. Auto color registration error correction
control calculates the color registration error amount and adjusts the exposure timing as
a means to prevent color registration error.
Registration is mainly performed at the following times:-
- When a designated period of time calculated to ensure optimal performance of the
device has elapsed, a time period that will vary depending on how long the device
remains in a state of continuous printing, intermittent printing or power ON ready state.
- When the user manually selects registration from the operation panel.
- Immediately after the top cover is opened and closed.
- After the power is turned OFF and ON, but only if the designated period of time calculated
to ensure optimal performance of the device has passed.
- When the printer senses that the ambient temperature has changed.