Patent ID: 7156486

Claim:
A liquid ejection head comprising: a nozzle plate having nozzle holes formed thereon for ejecting liquid droplets; a frame-shaped first support base; a head chip having a plurality of heater elements arranged on a semiconductor substrate; and a second support base, at least part of which being arranged within a region inside the frame of the first support base, the liquid ejection head having a plurality of the head chips joined onto the nozzle plate in a line so that the heater elements oppose the nozzle holes, respectively, wherein the linear expansion coefficient of the head chip is substantially the same as that of the first support base; the linear expansion coefficient of the nozzle plate is larger than that of the first support base; and the linear expansion coefficient of the second support base is larger than that of the first support base, wherein the nozzle plate is joined onto the first support base while under the circumstance of temperature at which a thermal stress is not generated on the junction surface between the first support base and the second support base, a tensile stress is produced in the nozzle plate by the first support base, wherein the second support base is joined onto the first support base so that at least parts of external side faces at both ends of the second support base in a longitudinal direction are fitted between at least parts of internal side faces of the first support base, and wherein when the second support base thermally expands relative to the first support base, a compression stress is produced in the second support base while a strain of the second support base is restricted by the first support base.