The basic principle of the inkjet system is made up of a reservoir of ink held in the cartridge, and a method of moving the ink from the reservoir to the paper via the print head, in a very precise and accurate procedure.
Air plays an important part in the whole operation it replaces the ink as it is used, so there must be a way for the air to get into the cartridge, while not causing the ink to drip out of the cartridge until it is required for printing. The popular cartridges (HP 51626A, 51629A and Canon BC01, BC02) all have air vents to allow the passage of air into the cartridge. With the HP cartridges it’s in the top and Canon place theirs above the print head in the front.
The reservoir itself takes many forms with the various manufacturers the internals invariably contain a sponge that hold the ink until required, but again this is not always the case. Some manufacturers have a completely separate "tank" that filters the ink through to the inner chamber before printing.
To get the ink onto the page, the cartridge print head has many very small (less than a human hair) nozzles or holes that allow the ink to flow through to do your printing. These nozzles hold the ink until an electronic impulse causes the ink to be sent to the paper. The popular method (bubble-jet) is to selectively heat the ink at the nozzles, by resistors. As the ink heats, a bubble forms and the heat source is then removed and the formed bubble then "bursts" and the resulting ink is transferred to the paper. This is all happening at very high speed, so that the dots that are being sprayed (up to 6000 per second) onto the paper will form the characters or graphics. Another method, popularized by Epson is the "piezoelectric" method, where crystals are subjected to an electric field, which causes them to expand and contract. The movement this generates then allows a precise amount of ink to be put down on the paper.
It’s been established over time that the resistors in the cartridge do not necessarily break down after the first use it is at this point that the cartridge can be recycled for reuse. However, 5% of all cartridges cannot be recycled once, while many can be recycled many times. It is dependent on many factors temperature, cartridge quality, Ink quality, has the cartridge been "burned out"? – each is an individual case! The only thing that you can be sure of is that the cartridges will eventually wear out – and not necessarily because it’s out of ink. You must remember that because you are recycling, you will eventually have to buy a new cartridge – they don’t last forever but if you do recycle watch your savings grow.
How does an Ink-jet cartridge work?