| MadSci Network: Engineering |
Great question!!
The ink cartridge is made up of basically two parts: an ink reservoir and a collection of thermal elements. The ink reservoir holds liquid ink which will be deposited onto the paper. The thermal elements contain tiny holes for the ink to flow through. The holes are sufficiently small that surface tension keep the ink from dripping out. If you squeeze the reservoir, you can force the ink through the holes.
Ink is deposited on the paper by heating the thermal elements. A short, controlled pulse of electricity heats the region surrounding a hole in the thermal element. Ink in contact with the thermal element will be heated causing rapid expansion which forces a tiny jet of ink through the hole. I think this where the term InkJet comes from.
This turns out to be a great way to make medium quality printers because all the parts a relatively inexpensive. The cartridge itself is durable and disposable. The only precision components (aside from the carriage) are the thermal elements in the cartridge. There are many low cost, high volume manufacturing processes available to make these elements.
Ink jet print quality is almost as good as laser print quality at a much lower price. Laser printers basically employ a xerographic process like a copy machine, so they are much more evolved when compared to ink jets.
If you have any further questions, don't hesitate to drop me a line at madhu@madhu.com
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