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DEVELOPMENT
The active sensing element is a very small transformer with three coils. When
iron ferrite (carrier) is near the sensing element, the inductance of the coils
changes, causing the current through the transformer to change. As the
amount of toner in the developer increases, the effect of the carrier particles
decreases and the voltage applied to CN101-2 decreases. Conversely, when
the toner concentration drops due to use, the effect of the carrier on the
sensor coils increases and the voltage at CN101-2 also increases.
Service call "Ed" lights if the toner sensor output becomes less than 1.6 V or
more than 4.7 V.
Toner Density Sensor Output
(= Vts)
Vts ≥4.7
4.7 > Vts > 3.8
3.8 ≥ Vts ≥ 2.4
2.4 > Vts > 1.6
1.6 ≥ Vts
Upper limit
Lower limit
Toner End Condition
When the main PCB senses that Vsp/Vsg is 0.225 or more ten times in a row
under 2.4 ≤ Vts < 4.7 conditions, the toner near end condition is detected and
the add toner indicator start flashing.
When in the toner near end condition, 5.49 meters (=610 mm x 9) can be
copied. After that, the toner end condition is reached. The Add Toner
indicator will light and the machine will not operate.
Toner Density Condition
Abnormal
Normal
Abnormal
2.4 V
3.8 V
Service Call "Ed"
Toner density sensor control
Low
(Toner is supplied.)
ID sensor control
Toner density sensor control
High
(No toner supply)
Service Call "Ed"
2-24
31 December 1992
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