SPINDLE MOTOR

1 . A spindle motor comprising:

a fixed shaft member,

a sleeve component into which said fixed shaft member is inserted such that a narrow gap is defined between an outer peripheral surface of said fixed shaft member and an inner peripheral surface of said sleeve component, said narrow gap being filled with a lubricating fluid so as to define a hydrodynamic bearing, and

wherein said fixed shaft member has an annular collar protruding outward from and substantially perpendicular to the outer peripheral surface of said fixed shaft member, and also has a thrust flange provided a specific distance away from said annular collar, said annular collar being one of

(i) monolithic with said fixed shaft member, and

(ii) press fit onto said fixed shaft member,

wherein said sleeve component is monolithic with a hub component that is to fix a disk, and is rotatably supported by said fixed shaft member between said annular collar and said thrust flange such that a narrow gap exists between said sleeve component and said thrust flange, and

the sleeve component further comprising an annular chucking portion, the annular chucking portion being formed to include a surface along an axial direction outside said thrust flange in a diameter direction of said thrust flange, the annular chucking portion being disposed at a position in an axial direction that includes a vertical position of a surface to which said disk is attached, and

said surface to which said disk is attached is disposed at a position in an axial direction that is not aligned with a position of an annular magnet applying an rotational force to said hub component.

2 . A spindle motor comprising:

A fixed shaft member;

A sleeve component into which said fixed shaft member is inserted such that a narrow gap is defined between an outer peripheral surface of said fixed shaft member and an inner peripheral surface of said sleeve component said narrow gap being filled with a lubricating fluid so as to define a hydrodynamic bearing; and

wherein said fixed shaft member has an annular collar protruding outward from and substantially perpendicular to the outer peripheral surface of said fixed shaft member, and also has a thrust flange provided a specific distance away from said annular collar, said annular collar being one of

(i) monolithic with said fixed shaft member, and

(ii) press fit onto said fixed shaft member,

wherein said sleeve component is monolithic with a hub component that is to fix a disk, and is rotatably supported by said fixed shaft member between said annular collar and said thrust flange such that a narrow gap exists between said sleeve component and said thrust flange, and

the sleeve component further comprising an annular chucking portion, the annular chucking portion being formed to include a surface along an axial direction outside said annular collar in a diameter direction of said annular collar, the annular chucking portion being disposed at a position in an axial direction that includes a vertical position of a surface to which said disk is attached, and

said surface to which said disk is attached is disposed at a position in an axial direction that is not aligned with a position of an annular magnet applying an rotational force to said hub component.

3 . The spindle motor according to claim 1 , wherein:

a back yoke for attaching the annular magnet is monolithic with the hub component.

4 . The spindle motor according to claim 2 , wherein:

a back yoke for attaching the annular magnet is monolithic with the hub component.