Fluid dynamic bearing and hard disk drive employing the same

A fluid dynamic bearing comprising:

• a journal bearing part supporting a rotary shaft of a hard disk in a radial direction of the rotary shaft;
• a thrust part formed at one end of the rotary shaft;
• a thrust bearing part facing the thrust part and supporting the rotary shaft in a longitudinal direction of the rotary shaft;
• and
• a plurality of grooves formed on a surface of at least one of the thrust bearing part and the thrust part,
• wherein the plurality of grooves comprise:
• a first groove group disposed on a first portion of the surface and including a plurality of grooves having the same shape and arrangement;
• and
• a second groove group disposed on a second portion of the surface corresponding to a portion of the hard disk where a load is applied by a head, and including at least one groove asymmetric with respect to the grooves of the first groove,
• wherein the second groove group includes a plurality of grooves having the same size, shape, and arrangement, a width of each of the grooves of the second groove group is relatively less than a width of each of the grooves of the first groove group, and intervals between adjacent grooves of the second groove group are less than intervals between adjacent grooves of the first groove group.

A hard disk drive comprising:

• a hard disk with one recording surface on which information is recorded;
• a fluid dynamic bearing rotatably supporting a rotary shaft of the hard disk, and including a journal bearing part supporting the rotary shaft in a radial direction of the rotary shaft, a thrust part formed at one end of the rotary shaft, a thrust bearing part facing a thrust part and supporting the rotary shaft in a longitudinal direction of the rotary shaft, and a plurality of grooves formed on a surface of at least one of the thrust bearing part and the thrust part;
• a driving source providing a rotational force to the hard disk;
• and
• a head for recording and reproducing information while flying over the recording surface of the hard disk,
• wherein the plurality of grooves comprise:
• a first groove group disposed on a first portion of the surface and including a plurality of grooves having the same shape and arrangement;
• and
• a second groove group located on a second portion of the surface corresponding to a portion of the hard disk where a load is applied by the head, and including at least one groove asymmetric with respect to the grooves of the first groove group,
• wherein the second groove group includes a plurality of grooves having different widths, and among the plurality of grooves of the second groove group, a width of a groove located at a center of the second groove group is relatively less than a width of a groove adjacent to the first groove group.

A hard disk drive comprising:

• a hard disk with one recording surface on which information is recorded;
• a fluid dynamic bearing rotatably supporting a rotary shaft of the hard disk, and including a journal bearing part supporting the rotary shaft in a radial direction of the rotary shaft, a thrust part formed at one end of the rotary shaft, a thrust bearing part facing a thrust part and supporting the rotary shaft in a longitudinal direction of the rotary shaft, and a plurality of grooves formed on a surface of at least one of the thrust bearing part and the thrust part;
• a driving source providing a rotational force to the hard disk;
• and
• a head for recording and reproducing information while flying over the recording surface of the hard disk,
• wherein the plurality of grooves comprise:
• a first groove group disposed on a first portion of the surface and including a plurality of grooves having the same shape and arrangement;
• and
• a second groove group located on a second portion of the surface corresponding to a portion of the hard disk where a load is applied by the head, and including at least one groove asymmetric with respect to the grooves of the first groove group,
• wherein the second groove group includes a plurality of grooves having the same size, shape, and arrangement, a width of each of the grooves of the second groove group is relatively less than a width of each of the grooves of the first groove group, and intervals between adjacent grooves of the second groove group are less than intervals between adjacent grooves of the first groove group.