Ricoh G035 Service Manual page 84

DEVELOPMENT
Toner near end is detected using the TD sensor output data.
If Vtref-Vt (10) is less than or equal to –0.45, the toner concentration is very low.
"K" becomes 0.25 and the machine enters the toner near end condition. Then, the
toner supply motor turns on to supply toner.
If Vtref-Vt (10) is greater than –0.45, the toner concentration is still not terribly low,
but the machine does further tests by comparing Vtref and Vt (10). If the machine
has detected 40 times that Vt (10) is greater than Vtref, the toner supply motor
turns on for double the time that it would be with the previous formula. If the toner
concentration is still low, the machine enters the toner near end condition.
Toner end is detected using the ID sensor.
If Vsp is bigger than 2.0V, the density of the ID sensor pattern is very light, so the
machine detects a toner end condition. However, if Vsp stays less than 2.0V but 90
sheets printed have been made after toner near end was determined, the machine
enters the toner end condition.
G035 2-32 SM