HP 2500c Service Manual - Page 127

Paper Paths and Components Output Management Output Mechanism Schematic holder-starwheel(sec) starwheel(secondary) cockle rib holder-starwheel(main) carriage chassis starwheel(main) output shaft platen ramp separator Star-wheels There are two rows of star-wheels, main and secondary. The main row contains ten sets of active starwheels (each set consists of 2 starwheels) and two passive starwheels . Active starwheels are preloaded by starwheel springs and are driven by output roller. The linear speed of starwheels is 2 % greater than that of drive roller thus creating paper stiffness to maintain the critical parameter pps distance. Also, once the media leaves the outpinch rollers, these starwheels become the only driving force to eject the media to the output tray. Two passive starwheels (not shown in figure) are provided to control A/A4 media shape such a way that the bow shape created by ramp does not propagate into the print zone. There are four sets of secondary starwheels in between the main row starwheels and cockle ribs. Locating the outer profile of these starwheels at the tangential line connecting the main row active starwheels and cockle rib tip make sure that media is not lifted above the tangential line and also the media does not touch the chassis once it leaves outpinch roller after printing. Functional Overview 6-7