6 – 50Chapter 6 Principles of OperationVersion 2 2006.03.285.4 Process ControlFor a stable printing, the parameters related to the image forming must be corrected as necessary. Thecontrol of the entire printing process including parameter correction control is called "process control".Mainly, the process control is performed in the following two methods, both of which are performedafter every 25 cumulative prints upon termination of a print run or during a continuous run.:• Potential control• Toner density controlTo supplement these two controls, the following controls are provided:• High Area Coverage Mode• Admix Mode5.4.1 Potential ControlTo attain stable printing image density, the drum charging voltage, the developing DC voltage and thePRINT HEAD light amount are adjusted according to the developing capability of each color carrier thatvaries momentarily. The adjusted drum charging voltage, the developing DC voltage and the PRINTHEAD light amount are fed back to keep the printing image density constant.The outline of control is as follows.1) The HUMIDITY SENSOR (temperature and humidity sensor) detects the temperature andhumidity.2) The patches of respective colors (yellow, magenta, cyan, and black) for the potential control aregenerated and transferred on the Belt.3) The ADC Sensor (density sensor) detects the density of the patch on Belt.4) The drum charging voltage, the developing DC voltage and the PRINT HEAD light amount areadjusted for each color according to the detected patch density.
