Toner Control; Sensor Toner Low; Toner Presence Control - Brother HL-4000CN Service Manual

7.7

Toner Control

Whether the toner bottle is installed is detected by the switch toner cartridge ASSY, and
the presence of toner in the toner bottle is detected by the sensor toner low. These
switches and sensors are provided for respective colors, and detection is made for each
color.
7.7.1

Sensor toner low

The sensor toner low is provided for each color, but the printer cannot detect all colors at
a time, but detects one color each. It detects one color per 3.5 seconds, thus requiring
14 seconds for detecting four colors. Accordingly, the presence of toner is detected once
per 14 seconds for each color.
The sensor toner low is attached to the holder toner cartridge ASSY, and it detects the
presence of toner dispensed by the toner motor from the toner bottle into the holder toner
cartridge ASSY.
Also, the sensor toner low could make a wrong detection if the toner sticks to the sensor
surface. To prevent this, the film attached in the vicinity of the auger in the holder toner
cartridge ASSY cleans the sensor surface when the toner is dispensed. This film rotates
together with the auger at the toner dispensation to scrape the toner off the sensor toner
low surface. However, the sensor may detect the toner even if the toner is not present or
may not detect the toner even if the toner is present, depending on the film position when
the toner motor stopped. This is avoided by the printer internal control.
7.7.2

Toner presence control

The control is outlined below.
1) Check timing
When the power is turned on, or the front cover is opened and closed
Every 14 seconds
2) Output of "Toner Empty Warning"
The "Toner Empty Warning" is outputted, if the sensor toner low detects toner empty
two ore more times continuously and also the toner is dispensed during the time of
2-time detection. This is taken place to prevent a wrong detection depending on the
film position as described in"7.7.1 Sensor toner low".
3) Output of "Toner Empty Error"
After the output of "Toner Empty Warning", the toner dispense time is counted up,
and if it exceeds the specified value, the "Toner Empty Error" is outputted.
4) Reset of "Toner Empty Warning"/"Toner Empty Error"
After the output of "Toner Empty Error", the toner is dispensed for 1.5 seconds when
the toner bottle installation is detected. At the subsequent toner presence control
timing, if the sensor toner low detects the toner presence, the "Toner Empty
Warning" and "Toner Empty Error" are reset.
However, in such a case, the controller regards this status as "toner empty". When
the toner is dispensed and the sensor toner low detects the toner presence three or
more times continuously, the controller regards this status as "toner presence".
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