HP Color LaserJet Enterprise CP4020 Service Manual - Page 81

The face-down tray media full sensor on the output bin detects whether the tray is full of printed pages. The DC controller notifies the formatter when the sensor is on for a specified time. Figure 1-40 Fuser and delivery unit Simplex media path Duplex media path Fusing-and-delivery block SR6 Face-down tray media full sensor Loop control The loop control stabilizes the paper feed operation before the paper enters the fuser. If the pressure roller rotate slower than the secondary transfer roller, the paper loop increases and an image defect or paper crease occurs. If the pressure roller rotate faster than the secondary transfer roller, the paper loop decreases and a vertical scanning magnification failure occurs because the pressure roller pulls the paper. To prevent these problems, loop sensor 1 and loop sensor 2 detect the paper loop before the paper enters the fuser. The DC controller adjusts the rotational speed of the fuser motor according to the output signals from the loop sensors and maintains the paper loop. Loop sensor 1 is for light media, and loop ENWW Pickup, feed, and delivery system 49