Disk device and method of manufacturing disk device

1. A disk device comprising:

a rotatable disk-shaped recording medium;

a head which processes data on the recording medium; and

a housing accommodating the recording medium and the head, the housing comprising a base with a side wall including a first region having a first width and a second region having a second width less than the first width, and a cover comprising a welded portion welded to the side wall by laser welding,

the welded portion including a first welded portion welded to the first region of the side wall and comprising weld beads with a first shape, and a second welded portion welded to the second region of the side wall and comprising welded beads with a second shape different from the first shape.

2. The disk device of claim 1 , wherein

the first welded portion includes a belt shaped continuous weld bead formed by continuous irradiation of a laser beam, and

the second welded portion includes a plurality of stacked circular weld beads welded by pulse irradiation of a laser beam.

3. The disk device of claim 1 , wherein

the first welded portion includes a belt shaped continuous weld bead with a first width formed by continuous irradiation of a laser beam, and

the second welded portion includes a belt shaped continuous weld bead with a second width less than the first width of the weld portion, formed by continuous irradiation of a laser beam.

4. The disk device of claim 1 , wherein

the base comprises a bottom wall, a plurality of side walls provided along a periphery of the bottom wall and a rib provided at an upper portion of the plurality of side walls and extending over all circumferences of the plurality of side walls, the rib including a first region having a first width and a second region having a second width less than the first width of the first region,

the cover includes a peripheral portion welded to the rib, and

the second welded portion is located in the second region of the rib.

5. The disk device of claim 1 , wherein

the housing is enclosed with a gas of a density lower than that of air.

6. A method of manufacturing a disk device comprising a housing comprising a base with a side wall including a first region having a first width and a second region having a second width less than the first width, and a cover which covers the base, and a rotatable disk-shaped recording medium in the housing, the method comprising:

placing the recording medium in the base; and

welding a peripheral portion of the cover to the side wall of the base by laser welding, the laser welding comprising welding a part of the peripheral portion of the cover to the first region of the side wall by a laser beam under a first laser irradiation condition and welding another part of the peripheral portion of the cover to the second region of the side wall by a laser beam under a second laser irradiation condition different from the first laser irradiation condition.

7. The method of claim 6 , further comprising:

filling the housing with a low-density gas having a density lower than that of air after the laser welding.

8. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated at a first laser output, and

under the second laser irradiation condition, the laser beam is irradiated at a second laser output lower than the first laser output.

9. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated continuously, and

under the second laser irradiation condition, the laser beam is irradiated in pulses.

10. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated at a first scanning speed, and

under the second laser irradiation condition, the laser beam is irradiated at a second scanning speed lower than the first scanning speed.

11. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated in pulses at a first pulse frequency, and

under the second laser irradiation condition, the laser beam is irradiated in pulses at a second pulse frequency higher than the first pulse frequency.

12. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated in pulses at a first pulse pitch, and

under the second laser irradiation condition, the laser beam is irradiated in pulses at a second pulse pitch less than the first pulse pitch.

13. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated in pulses by a first beam spot diameter, and

under the second laser irradiation condition, the laser beam is irradiated in pulses at a second beam spot diameter less than the first pulse spot diameter.

14. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated in pulses by a beam spot of a first focal depth, and

under the second laser irradiation condition, the laser beam is irradiated in pulses by a beam spot having a second focal depth less than the first focal depth.

15. The method of claim 6 , wherein

under the first laser irradiation condition, the laser beam is irradiated continuously at a first scanning speed, and

under the second laser irradiation condition, the laser beam is irradiated continuously at a second scanning speed lower than the first scanning speed.

16. The method of claim 6 , wherein

under the first laser irradiation condition, a laser irradiated position is set at a center of the first region in a width direction, and

under the second laser irradiation condition, a laser irradiated position is set at a center of the second region in a width direction.