Multi-nozzle ink jet head and manufacturing method thereof

A multi-nozzle ink jet head having a plurality of nozzles and a plurality of pressure chambers, comprising:

• a nozzle member in which is formed said plurality of nozzles;
• a pressure chamber wall member in which is formed said plurality of pressure chambers;
• piezoelectric type actuators for applying pressure to each of said plurality of pressure chambers for ejecting ink from said nozzles;
• a reinforcing member that is provided on surfaces of said pressure chamber wall member facing said pressure chambers and reinforces said pressure chamber wall member, wherein said reinforcing member forms a portion of sidewalls that separate said plurality of pressure chambers, wherein said reinforcing member forms parts of said sidewalls from wall surfaces to cores of the sidewalls, wherein said portion of said reinforcing member corresponds to half of said sidewalls in a height direction, wherein said reinforcing member is formed from an electrically conductive member;
• and a diaphragm that is provided on a surface of said plurality of pressure chambers facing the piezoelectric type actuators, wherein said reinforcing member, which is provided on each of the pressure chambers of said pressure chamber wall member, is electrically connected together and serves as a common electrode for said plurality of pressure chambers, wherein said diaphragm is formed of the same electrically conductive material as said reinforcing member, said diaphragm also serving as said common electrode for said plurality of pressure chambers, wherein said reinforcing member is being formed as an integrated unit, wherein said reinforcing member and said diaphragm are joined in an integrated fashion so as to have a unified structure, wherein said piezoelectric type actuators are disposed above said plurality of pressure chambers respectively, wherein said reinforcing member acts as an diaphragm.