Patent ID: 7809296

Claim:
A method for preventing excess supply of toner in an imaging device, the method comprising: detecting a change in a tribo-electric charge of toner with a sensor after a period of inactivity of the imaging device; calculating a toner dispense control value from the detected change in the tribo-electric charge of toner using an accumulated error value; compensating the toner dispense control value based on the detected change in the tribo-electric charge of toner; outputting the compensated toner dispense control value; and wherein the toner dispense control value is a PID (Proportional, Integral, Differential) value, the values P, I and D for the PID value are determined such that the compensated PID value is substantially zero, and the values P, a proportional constant, I, an integral constant, and D, a differential constant, are calculated by the following equations: P ( t )= P*ΔV*e −t/τ I ( t )= I *( R*ΔV+ΔV*τ−ΔV*τ*e −t/τ ) D ( t )=− D *(Δ V /τ)* e −t/τ where R is a rest recovery constant, ΔV is a change in sensor voltage during rest, t is a measure of the period of inactivity of the imaging device and τ is a time constant; and the PID value is calculated by the following equation: PID=P ( t )* E+I ( t )* AE+D ( t )*Δ E where E is an error between a target voltage and a measurement voltage of the sensor, AE is an accumulated error of E, and ΔE is a change in error since a last measurement.