Xerox 6250N Service Manual - Page 47

If toner density is too great (excess toner) and 16 dispense counts are required to subtract this amount, the adjustment is accomplished by subtracting 2 counts from the calculated PCDC count over each of the subsequent 8 prints. If the excess amount cannot be subtracted in 8 print cycles, it is subtracted in the ninth and subsequent prints. Total dispense counts Correction amount by ADC +16 Dispense counts by PCDC Correction amount by ADC -8 Total dispense counts 4534223432 Even allotment in first 8 prints 2 3 1 2 0 0 1 2 3 2 1201000022 6250-067 High-Area Coverage Mode Continuous printing of an image with density exceeding the toner dispense capability causes the toner density in the developer to be lowered below the target toner density. The high area coverage mode delays feeding of the next page, and dispenses toner during this time so that the toner density time reaches the specified value during continuous printing. Admix Mode If the high area coverage mode can not deal with the reduction of toner density in the developer or if the machine is moved to an environment with a different humidity level, the reference value for the toner density will change. This causes a large discrepancy between the measured values from the CTD sensor and the referenced value for the toner density. Admix mode dispenses the toner immediately to prevent low-toner density. If the patch density result measured by the CTD Sensor is lower than the reference value from the toner density control, then the admix mode is initiated. LED Light Density CTD (ADC) Control of Sensor The CTD (ADC) sensor is a reflective sensor that emits light from an LED in the sensor and detects the reflected light from the transfer roller. For exact density measurement, the sensor output value (reflected light density) must be the specified value when no toner is put on the Transfer Roller. The reflected light density varies 2-8 Phaser 6250 Color Laser Printer Service Manual