Method for manufacturing resin molding and laser beam irradiation apparatus

A laser beam irradiation apparatus for welding a resin molding, with the resin molding including a light-absorbing resin member having a weld region extending in a predetermined extending direction and a light-transmitting resin member having a corresponding weld region extending in the predetermined extending direction, the apparatus comprising:

• a plurality of scanning heads each including a laser oscillator configured to emit a laser beam with predetermined properties and a laser optical system configured to guide the laser beam emitted from the laser oscillator, wherein
• the weld region of the light-absorbing resin member and the corresponding weld region of the light-transmitting resin member are arranged and pressed so that they are opposed to each other and are brought into contact with each other,
• in this state, while the plurality of scanning heads are disposed near the light-transmitting resin member, the plurality of scanning heads are configured to emit a plurality of laser beams to scan along a scanning line along the extending direction of the weld regions with the scanning line being divided into trajectories of the plurality of laser beams,
• the plurality of scanning heads are also configured to scan by connecting the trajectories of the laser beams which are the divided parts of the scanning line and changing over time positions where the trajectories of the plurality of laser beams are connected along the extending direction.

A method for manufacturing a resin molding, comprising:

• preparing a light-absorbing resin member having a weld region and a light-transmitting resin member having a weld region corresponding to the weld region of the light-absorbing resin member;
• forming a light reflecting film on the light-absorbing resin member at a predetermined area;
• irradiating the weld region of the light-absorbing resin member with a laser beam having a beam spot diameter of 1.0 mm or less as a first focusing state to remove the light reflecting film in the weld region of the light-absorbing resin member;
• and
• pressing the light-absorbing resin member and the light-transmitting resin member so that the weld regions of the light-absorbing resin member and the light-transmitting resin member are brought into contact with each other, and repeatedly irradiating the weld region of the light-absorbing resin member with a laser beam having a beam spot diameter of 1.5 mm or more and 3.5 mm or less as a second focusing state to weld the light-absorbing resin member and the light-transmitting resin member.