Modified Kalman filter for reducing the effect of noise in toner concentration control

Control is required to keep the toner concentration (TC) constant for a long print job. If TC is too low, the print image cannot be properly developed, while a too high TC will lead to high background development. The latitude for TC is narrow. The basic TC control loop comprises of making TC measurement on a regular basis using a sensor and then comparing the sensor values with the setpoints. The sensor measurement generally contains noise, and is particularly large for for the TC sensor. The performance of the TC controller, and ultimately, the print quality, is therefore adversely affected by the sensor noise. In this paper, we introduce a modified Kalman filter to the TC control loop. The conventional Kalman filter is modified to accommodate the delay in the toner delivery process. The result shows remarkable improvement of the controller performance because of the effective reduction of the sensor noise by the Kalman filter