Patent ID: 7334872

Claim:
A method for producing a nozzle plate of an inkjet head having a plurality of nozzles for ejecting ink, comprising the steps of: preparing a nozzle plate base which has an electrical conductivity, the nozzle plate base including a nozzle plate, an outer frame surrounding the nozzle plate, and a plurality of connecting portions which connect the nozzle plate to the outer frame; forming the plurality of nozzles through the nozzle plate; dipping the nozzle plate base into an electrolytic solution; and energizing the outer frame of the nozzle plate base to plate the nozzle plate with a water repellent film, wherein a gap formed between the nozzle plate and the outer frame is smaller than or equal to 10 mm, wherein the nozzle plate has a rectangular form, wherein the nozzle plate has a plurality of nozzle groups, each of which has a plurality of nozzles arranged in a matrix, the plurality of nozzle groups being arranged in parallel with a longitudinal side of the rectangular form of the nozzle plate at predetermined intervals, wherein adjacent ones of the plurality of nozzle groups are shifted, in directions opposite to each other, by the same distance with respect to a center line of a shorter side of the nozzle plate, and wherein the plurality of connecting portions are arranged alone both of longitudinal sides of the nozzle plate, each of the connecting portions arranged along one of the longitudinal sides of the nozzle plate being opposed to each of the nozzle groups shifted to the other of the longitudinal sides of the nozzle plate with respect to the center line of the shorter side of the nozzle plate.