Patent ID: 7140554

Claim:
A liquid ejection head, comprising: a liquid chamber, which stores liquid therein; a nozzle orifice, adapted to eject a liquid droplet therefrom; a pressure generating portion, provided in a liquid channel communicating with the liquid chamber and the nozzle orifice; an elastic plate, which defines a part of the pressure generating portion, a piezoelectric vibrator, comprising: a first common electrode, provided on a surface of the elastic plate which is opposite to a surface facing the pressure generating portion, and electrically connected to a common potential; a first piezoelectric layer, provided on the first common electrode; a drive electrode, provided on the first piezoelectric layer, and electrically connected to a signal source for supplying a drive signal; a second piezoelectric layer, provided so as to cover the drive electrode; and a second common electrode, provided on the second piezoelectric layer, and electrically connected to the common potential, the piezoelectric vibrator being deformed in accordance with the drive signal supplied to the drive electrode, so that the elastic plate is deformed to vary a volume of the pressure generating portion, thereby ejecting the liquid droplet from the nozzle orifice, a liquid supply port, arranged between the liquid chamber and the pressure generating portion to serve as an orifice; and a pressure chamber which is a part of the pressure generating portion; wherein a value of the entire length of the nozzle orifice divided by a cross section of the nozzle orifice and a value of the entire length of the liquid supply port divided by a cross section of the liquid supply port are greater than a value of the entire length of the pressure chamber divided by a cross section of the pressure chamber.