Patent ID: 6450626
Filing Date: 2002-09-17
Classification: B41J

Abstract:
An ink jet head, comprising:a pressure chamber structure member comprising a plurality of pressure chambers which are filled with ink, and a plurality of openings respectively for the pressure chambers which are provided along a predetermined surface of the pressure chamber structure member; and a piezoelectric actuator provided on one surface of the pressure chamber structure member along which the openings of the pressure chambers are provided, wherein: the piezoelectric actuator comprises a piezoelectric layer which is provided substantially entirely across one surface of the pressure chamber structure member along which the openings of the pressure chambers are provided and which expands/contracts in a planar direction perpendicular to a thickness direction according to a direction of an electric field applied in the thickness direction; each portion of the piezoelectric actuator which corresponds to the opening of one of the pressure chambers and which generally corresponds to a center of the opening is defined as a displacement section, wherein when an electric field for expanding/contracting the piezoelectric layer in the planar direction is applied across a portion of the piezoelectric layer corresponding to the displacement section, the expansion/contraction of the piezoelectric layer in the planar direction is converted to a displacement in the thickness direction, whereby the displacement section is displaced in the thickness direction as a result of the conversion; each portion of the piezoelectric actuator which corresponds to the opening of one of the pressure chambers and which is in a vicinity of the displacement section is defined as an expansion/contraction section, wherein when an electric field for expanding/contracting the piezoelectric layer in the planar direction is applied across a portion of the piezoelectric layer corresponding to the expansion/contraction section, the expansion/contraction section expands/contracts in the planar direction by the expansion/contraction of the piezoelectric layer in the planar direction; and the displacement of the displacement section in the thickness direction is controlled by the expansion/contraction of the expansion/contraction section in the planar direction, so that the displacement of the displacement section in the thickness direction changes a volume of the corresponding pressure chamber, thereby discharging ink from the pressure chamber to the outside.