Self cooling inkjet printhead for preventing inadvertent boiling

Abstract

An inkjet printhead that has an array of ejection devices, each device having a chamber for holding a liquid, an inlet to the chamber in fluid communication with a supply of the liquid, a heater for heating the liquid to form a vapor bubble, and a nozzle through which a drop of the liquid is ejected in response to the vapor bubble formed by the heater. During use, the drop of liquid ejected from the nozzle is replaced with an equivalent volume of the liquid drawn through the inlet, the drop having a heat energy that differs from the heat energy of the equivalent volume drawn through the inlet. The difference in heat energy being substantially equal to the heat energy added to the liquid in the chamber by the heater when forming the vapor bubble. After the vapor bubble collapses and before the heater subsequently activates, the temperature of the liquid is at least 10 degrees Celsius below its boiling point in order to avoid any inadvertent boiling.

Dependencies are inferred from the claim text.