Magnetic disk device with improved shielding

1. A magnetic disk device comprising:

a rotary disk-type magnetic disk;

a magnetic head for recording information into said magnetic disk and for reproducing information from said magnetic disk;

a magnetic head support mechanism configured to support said magnetic head;

a shroud having an opening in which said magnetic head support mechanism is inserted, and surrounding the outer circumference of said magnetic disk; and

a housing including a base and a cover, and accommodating said magnetic disk, said magnetic head, said magnetic head support mechanism and said shroud within said housing;

wherein said base comprises a nonmagnetic material and said shroud comprises magnetic material;

wherein said shroud is in continuous contact with said base and said cover of said housing.

2. A magnetic disk device according to claim 1 , wherein said shroud has at least an upper end or a lower end which is continuous over the whole circumference to form said opening.

3. A magnetic disk device comprising:

a rotary disk-type magnetic disk;

a magnetic head for recording information into said magnetic disk and for reproducing information from said magnetic disk;

a magnetic head support mechanism configured to support said magnetic head;

a shroud having an opening in which said magnetic head support mechanism is inserted, and surrounding the outer circumference of said magnetic disk; and

a housing including a base and a cover, and accommodating said magnetic disk, said magnetic head, said magnetic head support mechanism and said shroud within said housing;

wherein said base comprises a nonmagnetic material, said cover comprises a magnetic material to cover said magnetic disk, and said shroud comprises a magnetic material so as to be joined to said cover;

wherein said shroud is in continuous contact with said base and said cover of said housing.

4. A magnetic disk device according to claim 3 , wherein said cover has a thickness in a range of from about 0.5 mm to about 1.5 mm.

5. A magnetic disk device according to claim 3 , wherein said shroud has a thickness of about 1-3 mm.

6. A magnetic disk device comprising:

a rotary disk-type magnetic disk;

a spindle mechanism which supports the central portion of said magnetic disk to turn said magnetic disk;

a magnetic head for recording information into said magnetic disk and for reproducing information from said magnetic disk;

a magnetic head support mechanism configured to support said magnetic head;

a shroud having an opening in which said magnetic head support mechanism is inserted, and surrounding the outer circumference of said magnetic disk; and

a housing including a base and a cover, and accommodating said magnetic disk, said spindle mechanism, said magnetic head, said magnetic head support mechanism and said shroud within said housing;

wherein said base comprises a nonmagnetic material, said shroud comprises a magnetic material, and the shaft of said spindle mechanism comprises a magnetic material;

wherein said shroud is in continuous contact with said base and said cover of said housing.

7. A magnetic disk device according to claim 6 , wherein said cover comprises a magnetic material, and the shaft of said spindle mechanism is joined to said cover via a fastening fitting made of a magnetic material.

8. A magnetic disk device comprising:

a rotary disk-type magnetic disk;

a spindle mechanism which supports the central portion of said magnetic disk to turn said magnetic disk;

a magnetic head for recording information into said magnetic disk and for reproducing information from said magnetic disk;

a magnetic head support mechanism configured to support said magnetic head;

a shroud having an opening in which said magnetic head support mechanism is inserted, and surrounding the outer circumference of said magnetic disk; and

a housing including a base and a cover, and accommodating said magnetic disk, said spindle mechanism, said magnetic head, said magnetic head support mechanism and said shroud within said housing;

wherein said base comprises a nonmagnetic material, said cover comprises a magnetic material to cover said magnetic disk, said shroud comprises a magnetic material and is joined to the cover via said magnetic material, and the shaft of said spindle mechanism comprises a magnetic material and is joined to said cover;

wherein said shroud is in continuous contact with said base and said cover of said housing.

9. A magnetic disk device according to claim 8 , wherein said cover has a thickness in a range of from about 0.5 mm to about 1.5 mm.

10. A magnetic disk device comprising:

a rotary disk-type magnetic disk;

a magnetic head for recording information into said magnetic disk and for reproducing information from said magnetic disk;

a magnetic head support mechanism configured to support said magnetic head;

a shroud having an opening in which said magnetic head support mechanism is inserted, and surrounding the outer circumference of said magnetic disk;

a housing including a base and a cover, and accommodating said magnetic disk, said magnetic head, said magnetic head support mechanism and said shroud within said housing; and

an upper shield provided on the inside of said cover;

wherein said base and said cover each comprise a nonmagnetic material, said upper shield comprises a magnetic material so as to cover said magnetic disk, and said shroud comprises a magnetic material and is joined to said upper shield;

wherein said shroud is in continuous contact with said base and said cover of said housing.

11. A magnetic disk device according to claim 10 , wherein said spindle mechanism and said upper shield are not in contact with each other.

12. A magnetic disk device according to claim 10 , wherein said upper shield has an outer circumferential portion in contact with an upper end of the shroud.