This is an older technology by Canon - most commonly known as the Canon Bubblejet series of printers. Bubblejet is Canon's trade name for its thermal drop on demand inkjet printer technology. The ink is heated, which produces a bubble that expands and ejects the ink out of the nozzle. As the bubble cools, the vacuum created draws fresh ink back into the nozzle. The principal difference between bubble-jet printers and other ink-jet printers is that bubble-jet printers use special heating elements to prepare the ink whereas ink-jet printers use piezoelectric crystals.

See also:

Ink Jet Printer,

Piezo Inkjet,

Thermal Printer,