Kenichi,
HP does put the print head (it's actually a series of very minute nozzles) on
some printers which is great because the print head is the achilles heal of inkjet printers. Replace the cartridge and bingo you get a new print head. However many of their newer printers use separate print heads. They have some where the print heads are replaceable and some where they are not. The OfficeJet Pro series of printers tend to use replaceable print heads. So the question becomes how do they create printers like Epson, Canon, Brother etc. that have a permanent print head but not waste as much ink keeping the print head primed and cleaned. The solution was really simple, but first let me explain how all other manufacturers (except HP of course) do it so you get the idea. They use an open loop system, meaning that ink intended for priming or cleaning passes through the print head it ends up inside the printer collected in a diaper (yes that is it's technical name) which simply soaks up the excess ink, in other words the ink is going from the cartridge directly to the garbage. Don't believe me read the fine print of your Epson or Canon printer in the back of your manual. The manufacturers that use an open loop system waste up to 70% of the ink for priming and cleaning meaning sometimes only 30% only ends up printing on paper. HP uses a different system, it's called a closed loop system which simply means instead of wasting ink by dumping it in a diaper it recycles the ink so it is circulated back to the print cartridge, the end result is that about 94% of the ink ends up on the paper.
Last HP is the only manufacturer (at least that I know) who publishes print yields based on the type of printing you do. Go to
http://www.hp.com/pageyield
Regards,
Roger
Message was edited by: rkaufmann87
