HP 1050c Service Manual - Page 296

Functional Overview Cap The purpose of the caps is to prevent the nozzles from drying out while the printer is idle. The caps seal off the printhead, forming a closed, high humidity chamber with small volume that is vented to ambient through a long and narrow passage. The caps self-align to the printheads by referencing features on each printhead. Wiper The function of wiping is to remove ink residue and external debris from the printhead so that good drop ejection and nozzle performance is maintained throughout the life of the printhead. Linear wiper motion will occur in the direction of the nozzle rows (orthogonal to direction of carriage motion) at 0.2 to 6.0 ips programmable speed. The maximum wiping force is 2N. Spittoon Spitting is the act of firing all the print head nozzles into a container (spittoon). Spitting into the spittoon is done routinely to clear the nozzles of viscous plugs and to clear any loose debris from the nozzles. PHC Spittoon is designed to hold 50 cc of spat ink (which has almost no water content due to evaporation). In order to avoid ink spills when replacing PHC, color spittoons have foam that will keep the ink escaping due to capillary effect. Black ink does not have foam. The Black ink is pigmented, and it has been proven that pigmented inks build up over any surface when spat, including foams, creating stalagmites that may hit the Printhead and cause some nozzles out. Fortunately, black ink dries very fast, creating a solid block of ink that will not fall out off the spittoon when tilted. For most users, the probability of seeing enough liquid ink in the spittoon to create a spills problem is very low. To prevent the growth of tall and narrow stalagmites that may reduce spittoon life, the Printhead spits in four different locations (Scan-axis), randomly. 10-10 HP DesignJets 1050C and 1055CM Printers Service Manual