Patent ID: 7537316

Claim:
An inkjet printhead comprising: a plurality of ink chambers on a first surface of a substrate, each ink chamber having an ink ejection nozzle; at least one heater arranged in each ink chamber so as to heat ink within the ink chamber to form a gas bubble therein and thereby cause ejection of an ink drop from the associated nozzle; and a plurality of ink supply passages formed in the substrate from an opposite, second surface of the substrate so that each ink supply passage supplies ink to an associated one of the ink chambers, wherein a length of the passages through the substrate from the second surface to the associated ink chambers is configured to prevent reverse ink flow into the passages after ink ejection, and each heater includes solid material and has a mass of less than 10 nanograms of the solid material, the solid material being configured to be heated to a temperature above a boiling point of the ink to thereby heat the ink to a temperature above the boiling point to cause formation of the gas bubble.