Konica Minolta Magicolor 3300 Service Manual page 454

7.4.3 High Area Coverage Mode
A continuous printing of the image of area coverage exceeding the toner dispense capability causes the
toner density in the developer to be lowered.
The High Area Coverage Mode extends the next page feed and dispenses the toner during this time, if the
toner dispense time reached the specified value during a continuous printing.
7.4.4 Admix Mode
Even the High Area Coverage Mode may not be able to cope with the reduction of toner density in the
developer. Also, if the machine used in high humidity environment is relocated to the place in low humidity
environment, the reference value of toner density is different in respective environments, thus causing large
discrepancy between measured value by SENSOR ADC ASSY and reference value of toner density.
The Admix Mode dispenses the toner immediately to prevent the reduction of toner density, if the patch
density result measured by the SENSOR ADC ASSY is far lower than the reference value when the
patches for toner density control are generated.
7.4.5 LED Light Quantity Control of SENSOR ADC ASSY
The SENSOR ADC ASSY is a reflection type density sensor that radiates the light to an objective from the
LED in the sensor and detects the reflected light from the objective to output electric signal according to the
light quantity. For exact density measurement, the sensor output value (reflected light quantity) must be the
specified value when no toner is put on the BTR as an objective. The reflected light quantity varies
depending on the BTR surface condition or dirty condition of SENSOR ADC ASSY surface. The light
quantity emitted from the LED is controlled so that the reflected light quantity satisfies the specified value.
This control is made in two ways; one to set the light quantity so that the reflected light quantity satisfies the
specified value, and one to adjust the subsequent light quantity to be within the tolerance.
1) Light quantity setting
The reflected light quantity may vary largely, if the BTR Assy was replaced or the SENSOR ADC ASSY
was cleaned. Assuming this fact, the light quantity is set when the power is turned on, or the front cover
is opened and closed.
The light quantity of LED is increased gradually, and the set value is fixed when the output of SENSOR
ADC ASSY exceeds the specified value. At this time, if the output of SENSOR ADC ASSY does not
reach the specified value even though the light quantity is increased to the upper limit, the controller
judges the sensor as dirty. Also, the controller judges the sensor as faulty in the event of extremely high
output.
2) Light quantity adjustment
At the execution of ADC, the light quantity adjustment is made immediately before the patches for toner
density control are generated.
The light is emitted from the LED with current setting of light quantity to check if the output value of the
SENSOR ADC ASSY is within the specified range. If the output value is low, the light quantity is
increased by the specified amount at the next ADC, or if high, the light quantity is reduced at the next
ADC.
At this time, if the output value is less than the first lower limit, the controller judges the sensor as dirty
and outputs the warning. Further, if less than the second lower limit, the controller judges the sensor as
faulty and stops the printing.
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