Theory of Operation 2-9depending on the Transfer Roller surface condition or dirty condition of CTD (ADC)sensor surface. The light density emitted from the LED is controlled so that thereflected light density meets the specified value.This control is implemented in two ways:■ Sets the light density so that the light reflected satisfies a specific value.■ Adjusts the subsequent light density to be within a specific tolerance value.1. Light Density SettingThe reflected light density can vary greatly if the transfer roller has been replaced orthe CTD (ADC) sensor has been cleaned. To deal with this variance the light densityis reset when the power is turned on or the front cover is opened and closed.The intensity of the LED increases gradually and the set value is adjusted when theoutput of the CTD (ADC) sensor does not meet the specified value. If the output ofthe CTD (ADC) sensor does not reach the specified value, even though the lightdensity is increased to the maximum limit, the controller signals the sensor is dirty. Ifthe sensor output is extremely high, the controller will signal that the sensor is faulty.2. Light Density AdjustmentAt the execution of automatic density control, the light density adjustment is madejust before the patches for toner density control are generated.Light is emitted from the LED using the current light density setting, to check if theoutput value of the CTD (ADC) sensor is within the specified range. If the outputvalue is low, light density is increased. If the output value is high, the light density isdecreased.If the output value is less than the first lower limit, the controller signals the sensor asdirty and generates a warning. If the output value is less than the second lower limit,the controler signals that the sensor is faulty and stops the printing.Color Registration ControlThe printer uses a quad system where drums and developers are used exclusively foreach of the four colors (yellow, magenta, cyan, and black). Images are formed on thedrums, in the respective colors, and then layered to form one image. To avoid apositional shift between the different color images, the color registration controlcalculates how much the registration has shifted by comparing each of the other colorpatches in the registration string to the black bar that precedes it. Shift is corrected byadjusting the laser write timing to compensate.Color registration control is made depending on the internal temperature and printcount at the execution of process control.manuals4you.commanuals4you.com
