The basic premise of thermal inkjet is phase change of a liquid. The ink is boiled by an electrically heated miniature pad, creating a bubble, which displaces ink in the nozzle chamber, forcing out droplets at the heads operating frequency in Khz. (Kilo hertz)
Because the ink is held in place by a slight negative pressure, the boiling creates a positive pressure in the nozzle chamber. pumping out droplets. The collapsing bubble then creates a negative pressure allowing for ink to flow into the head structure.
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