Development
G179 6-28 SM
TD Sensor: When new developer of standard toner concentration is installed, namely
20 g of toner per 500 g of developer (4.0% by weight), the TD sensor must be set to its
initial setting of 3.0V with SP2-801. This initial setting is used as the toner supply
reference voltage or Vref. For every print cycle, the TD sensor directly checks the toner
density in the developer mixture, and after 10 prints these 10 readings are averaged
and this value becomes TD sensor output voltage Vt(10).
The machine compares Vt(10) with Vref. If Vt(10) is greater than Vref, the toner
concentration in the development unit judged to be low. When Vt(10) is detected to be
greater than Vref 20 times, then this indicates that the toner concentration is
consistently low, Vref is incremented by 0.1V, and the conditions are checked again.
The result of this check determines the value of K, the toner supply rate coefficient,
which is one of the factors for the toner supply motor on-time calculation.
ID Sensor: In addition to comparing Vt(10) from the TD sensor and Vref, after every 10
prints the ID sensor, located at the lower right area of the drum, checks both the
reflectivity (Vsg) and the pattern on the drum (Vsp), created by the laser diodes and
charge roller. If the reflected light is too strong, this indicates that toner is low and toner
is added to the development unit. (The frequency of these checks can be adjusted with
SP2-210 (ID Sensor Pattern Interval).
Image Pixel Count Mode
This mode should only be used as a temporary measure while waiting for replacement
parts, such as a TD sensor. This mode controls the toner supply amount using the same
method for determining the toner bottle motor on time. However, the values that were in
effect when the toner density control mode was changed over to image pixel count mode
with SP2-208-1 (Toner Supply Mode) remain in effect and cannot be changed.
6.7.6 TONER NEAR END/END DETECTION
Toner Near End
The machine triggers the toner near-end alert and starts to rotate the toner supply bottle
when the following conditions occur.
Detected by SP2975-001
Vt (10) - Vref ≥ 0.2 and Vsp ≥ 0.6
Vt (10) - Vref ≥ 0.45
0.45 > Vt (10) - Vref ≥ 0.2 and toner end counter ≥ 300
Toner End
After the machine enters the toner near-mode, it will trigger the toner end alert if any of the
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