While the ink cartridges, or tanks, hold the ink, it is the electronic printhead which is responsible for firing the ink drops onto the page -- not the ink cartridges (tanks)! The Printhead is essentially the heart of the entire printing system. For the very popular 'on-axis' printer models, the carriage, which holds the ink cartridges and Printhead, quickly moves back and forth above the paper surface during printing.
At the base of the printhead, each ink drop is powered by a superheated vapor explosion, typically between 300 and 400 degrees Celsius, each occurring at 1-2 millionths of a second. The ink drop is rapidly expelled out of each chamber nozzle at a firing velocity of up to 20 meters per second.
Depending on the printer model, between 4,000 and 15,000 ink nozzles are used to fire ink drops down to the paper surface....shooting up to half a million ink drops per second during a typical printing job. To maximize print quality output, maintain printer health by printing once or twice a week and stop printing as soon as you notice a missing color.
Do not remove ink tanks from the printhead for too long or the printhead can dry out and may lead to image quality streaking - this will also help avoid accidental printhead damage.
If missing colors or streaking is observed it is suggested you perform a 'PRINTHEAD CLEAN', or similar, from the Maintenance/Tools menu - refer to Inkjet411 website for detailed printer recovery instructions.
For severe printer error messages which prohibit printing it is suggested you run a Print Quality Report (i.e. internal self test print), or for HP printer models, the PRINTHEAD health diagnostic's Tap 41 test print to evaluate whether or not the built-in PRINTHEAD is electrically damaged (i.e. internal micro-electronics). Please visit Inkjet411 HP Printer Diagnostic Tests page for procedures on your specific printer model: http://www.inkjet411.com