THERMAL TYPE INK JET PRINTER AND THERMAL TYPE INK JET PRINTING HEAD USED FOR SAID PRINTER

摘要

An improved thermal ink jet printhead is disclosed for ejecting and propelling ink droplets on demand along a flight path toward a recording medium spaced therefrom in response to receipt of electrical input signals representing digitized data signals. Each printhead has one or more capillary filled ink channels. The channels have a droplet emitting nozzle on one end and connect to an ink supplying manifold on the other end. Each channel has a heating element upstream from the nozzle that is located in a recess. The heating elements are selectively addressable with a current pulse for substantially instantaneous vaporization of the ink contacting the addressed heating element to produce a bubble that expels a droplet of ink during its growth and collapse. The recess walls containing the heating elements prevent the lateral movement of the bubbles through the nozzle and therefore the sudden release of vaporized ink to the atmosphere, known as blowout which causes ingestion of air and interrupts the printhead operation.