HP Color 9850mfp Service Manual - Page 103
Control path, Developing bias control
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II UNIT EXPLANATION hp Color 9850mfp 4.2.4 Developing bias control DEVELOPING UNIT A. Control path The developing bias Y, M, C and K are supplied from the high voltage unit 1 (HV1) and controlled by the printer control board (PRCB). Each developing bias is supplied with AC + DC to secure the uniformity of developing. 4.2.5 Durability of the developer A. Concept of the durability of the developer The durability (deterioration) of the developer depends on the developing sleeve drive distance (the moving distance of the developing sleeve surface) in the developing unit. The developing sleeve drive distance includes the distance at idle time (the time when the developing sleeve does not perform the developing operation but rotates) and the job output pattern has a significant effect on it. The idle time has a significant effect on the drive distance in such cases as followings. • Continuous copy count in a job: the rate of the idle time increases if the continuous copy count is small. • Switching the processing speed in a job: There is the idle time at switching the processing speed. • Switching mode in ACS: There is the idle time at switching between the color mode and the black and white mode. • The color mode operation of the black and white original in ACS: There is the idle time for the color developing sleeves when the black and white original is printed in the color mode. • Double-sided operation: The operation is circulated in set of 4 sheets if the paper size is A4 If the copy count is not an integral multiple of 4, for example if it is 9, only 1 sheet is circulated for the operation, so the idle time is increased. The relationship between the drive distance and actual copy/print count is affected by those output patterns and it is hard to be defined. The count could be significantly different even if the drive distance is same. B. Specification of the durability of the developer The durability of the drive distance for all color is specified as below. Durability: 83,000km/color As described in the previous section, the relationship between the drive distance and actual copy/print count is hard to be defined; however, 83,000km of drive distance corresponds to 100,000 copies/prints if 5 sheets are printed intermittently in the A4 single-sided copy mode as defined for the maintenance. 2-29