Patent ID: 6938341

Claim:
A method for manufacturing an ink discharge port of an ink jet recording head provided with the ink discharge port for discharging an ink liquid droplet for adhesion thereof to a recording medium, a liquid chamber for retaining ink to be supplied to the discharge port, an ink flow path communicating with the discharge port and the liquid chamber, an energy generating element provided for a part of the ink flow path, and an ink supply port for supplying ink from outside to the liquid chamber, comprising the step of: processing and forming a wall face inside an ink discharge surface of the ink discharge port to a surface condition having irregularities of not less than 0.3 micrometers and not more than 1 micrometer as the standard deviation value for the surface roughness thereof, wherein the ink discharge port is processed and formed by a laser beam emitted from a laser oscillator continuously emitting laser light pulses of large spatial and temporal energy concentration at a pulse emission time of 1 picosecond or less, for irradiating a designated pattern image at a designated energy concentration with a designated numerical aperture (NA) at a designated focal point.