Patent attributes
An ink jet printhead that has an array of ejection devices formed on a wafer substrate by lithographic etching and deposition techniques. Each device has a chamber for holding a liquid, an inlet to the chamber in fluid communication with a supply of the liquid, a heater with a generally planar heater element for heating the liquid to form a vapor bubble, the heater element being suspended in the chamber parallel to the plane of the wafer substrate, and a nozzle through which a drop of the liquid is ejected in response to the vapor bubble formed by the heater element, the nozzle being formed in the chamber wall opposing the inlet, and drive circuitry for controlling the operation of the heater element. The drive circuitry is formed in an area of the wafer substrate, the area having a centre point that is offset from a center point of the corresponding nozzle by less than 200 microns in order to minimize resistive losses in the electrical connections between the drive transistors and the heater element.
