Patent ID: 7503644

Claim:
A liquid ejection head, comprising: a plurality of ejection ports through which liquid is ejected; a plurality of pressure chambers which are connected respectively to the ejection ports; a common liquid chamber in which the liquid to be supplied to the pressure chambers is accumulated; a plurality of supply flow channels which connect the common liquid chamber to the pressure chambers; and a plurality of supply restrictors each of which constitutes at least a portion of each of the supply flow channels, wherein at least a portion of one of the ejection ports connected to one of the pressure chambers and a portion of one of the supply restrictors connected to the one of the pressure chambers are processed by means of the same laser beam, each supply restrictor comprises an opening in a first plate on a first side of the plurality of pressure chambers, where the opening has a diameter d 1 and the first plate has a thickness t 1 , and each ejection port comprises an opening in a second plate on a second side of the plurality of pressure chambers, opposed to the first side, where the opening has a diameter d 2 and the second plate has a thickness t 2 , wherein d 1 <d 2 , and the relationship t 1/ d 1 4 ≈t 2/ d 2 4 is satisfied.