Patent ID: 7628472

Claim:
A liquid ejection head comprising: a substrate on which a plurality of electrothermal transducers for generating energy for ejecting liquid droplets are provided; a plurality of chambers having said electrothermal transducers, respectively, wherein a bottom face in the interior of each of said chambers has a rectangular shape; at least one supply path for supplying said chambers with liquid; a supply port for supplying said supply path with liquid; a plurality of ejection ports each facing a surface on which a corresponding one of said electrothermal transducers is disposed; and a plurality of ejection portions having said ejection ports, respectively, entire circumferences of said ejection portions being surrounded by a wall, wherein each of said ejection portions comprises a first portion communicating with a corresponding one of said ejection ports and a second portion communicating with said first portion and a corresponding one of said chambers, wherein A c >A e2 >A e1 , where A c =a cross-sectional area of said corresponding chamber, the cross-sectional area being parallel to a surface on which a corresponding one of said electrothermal transducers is disposed, A e2 =a cross-sectional area of said second portion, the cross-sectional area being parallel to the surface on which said corresponding electrothermal transducer is disposed, and A e1 =a cross-sectional area of said first portion, the cross-sectional area being parallel to the surface on which said corresponding electrothermal transducer is disposed, wherein a length of an opening shape of said second portion facing said corresponding chamber in a direction parallel to a direction of said supply path is longer than a length of the opening shape of said second portion facing said corresponding chamber in a direction perpendicular to the direction of said supply path, wherein a surface of said second portion facing said corresponding chamber, a surface of said second portion facing said first portion, and a cross-section of said second portion parallel to said substrate are oval, and wherein lengths of said electrothermal transducers and lengths of said chambers in the direction of said supply path are longer than lengths of said electrothermal transducers and lengths of said chambers in the direction perpendicular to the direction of said supply path.