HP Color 9850mfp Service Manual - Page 108

II UNIT EXPLANATION TRANSFER BELT UNIT 5.2.3 1st transfer control hp Color 9850mfp Toner on the drum is transferred onto the transfer belt side by a bias value applied on the 1st transfer roller provided inside the transfer belt. The DC bias value of the 1st transfer roller changes according to the following conditions: • Process speed • Black-and-white mode or color mode • Humidity • No. of use counts of the 1st transfer roller For each operation timing of the 2nd transfer control, see "Image formation timing" in "3. Drum unit." 5.2.4 2nd transfer control Toner on the transfer belt is transferred onto the paper (which is pressed between the transfer belt and the 2nd transfer roller L on the ADU side). The 2nd transfer roller U is positioned inside the transfer belt directly above the 2nd transfer roller L, and applied with a DC bias value according to the following conditions: • Process speed • Black-and-white mode or color mode • Humidity • Type of copy paper • Front or rear side of paper For each operation timing of the 2nd transfer control, see "Image formation timing" in "3. Drum unit." 2-34