Image Pixel Count Mode; Toner Near End - Ricoh D009 Service Manual

Development
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 copy cycle, the TD sensor directly checks the toner
density in the developer mixture, and after 10 copies 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
copies 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.
6.9.6 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 either of the following two conditions occur.
The machine detects (1) the toner supply rate (amount of toner supplied per second set
with SP2209-1) drops to 25, (2) the current output of the TD sensor (Vt) has dropped
below the target value after 40 samples, and then (3) still fails to detect the target Vt
after an additional 40 samples.
The machine determines that the toner density is too light after it detects that (1) the
difference between Vref (the TD sensor reference voltage) and the averaged density of
the previous 10 copies is more than 0.2V, and (2) Vsp (the reflectivity of the ID sensor
pattern) is greater than 0.7V.
D009/D011/D012/D013 6-38 SM