Patent ID: 8038262

Claim:
A unit cell for an inkjet printhead, the unit cell comprising: a substrate defining an ink inlet passage, the substrate incorporating drive circuitry; side walls arranged on the substrate; a nozzle plate arranged on the side walls such that the nozzle plate and the side walls define an ink chamber in fluid communication with the inlet passage, the nozzle plate defining an aperture in fluid communication with the ink chamber; and a heater element connected to the drive circuitry, the heater element being configured to generate a bubble of ink to be ejected from the aperture on receipt of an electrical signal from the drive circuitry, the heater element being suspended in the ink chamber such that, when ink is supplied to the chamber, the heater element is immersed in the ink, the heater element being configured so that a collapse point of the bubble is at a position spaced from the heater element, wherein the heater element and the aperture are configured such that the collapse point of the bubble is less than 50 microns from the aperture.