Patent ID: 7942998

Claim:
A method for laser welding thermoplastic resin members which comprises bringing a first member formed of a transmissive thermoplastic resin that transmits a laser beam into contact with a second member formed of an absorptive thermoplastic resin that absorbs the laser beam, and melting their contact surfaces with the laser beam for joining the members, said method further comprising: pressing the first member and the second member together by a pressing force; irradiating the contact surfaces of the two members with a laser beam shone from the side of the first member; melting at least one of the contact surfaces of the two members; and welding the two members while adjusting the pressing force applied to the first member and the second member; wherein the adjustment of the pressing force is directly controlled based on a detected temperature at a melted portion of the contact surfaces that is melted by laser beam irradiation, and wherein in the adjustment of the pressing force, the pressing force is increased to a first pressing force when a detected temperature is greater than a predetermined value, and the pressing force is further increased to a second pressing force when another detected temperature indicates cooling at the melted portion.