Magnetic disk drive with mechanism for fixing flexible printed circuit assembly

A magnetic disk drive is provided which can attain the reduction in size and thickness without deteriorating the sealing performance for a space defined by a base and a cover. In one embodiment, a cover member is fixed to a base member with fixing screws. An FPC assembly is formed with leg portions extending from respective appropriate positions toward the cover member. The edges of the leg portions are abutted against the cover member fixed to the base member. Further, a stress member is provided between the base member and the FPC assembly. When the cover member is fixed to the base member to urge the FPC assembly adjacent the stress member, the stress member collapses to induce stress from the stress member, whereby a frictional force is generated at abutment surfaces of the cover member and the leg portions, thus fixing the FPC assembly.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. JP-2005-209205, filed Jul. 19, 2005, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to magnetic disk drives and more particularly to a magnetic disk drive using an improved method for fixing a flexible printed circuit assembly.

Heretofore, magnetic disk drives have been used in various fields. Recently, small-sized magnetic disk drives mounted on portable music players and on small-sized mobile devices have been becoming popular. In such magnetic disk drives, a flexible printed circuit (hereinafter referred to as “FPC”) is used for transfer of information to be read and/or written by a magnetic head.

FIG. 5shows a layout example of an FPC used in a conventional magnetic disk drive and various components located near the FPC. InFIG. 5, a magnetic disk12is mounted to a base member10through a spindle motor (not shown). A magnetic head assembly14is mounted on the base member10and a magnetic head16for write and read of information to and from the magnetic disk12is provided at a front edge of the magnetic head assembly14.

Signals of information which the magnetic head16writes to and reads from the magnetic disk12are exchanged with an external circuit with an FPC20coupled to an FPC assembly22. The FPC assembly22is configured such that a metallic plate or the like is bonded to the FPC and a connector and other components are attached onto the FPC. The FPC assembly22is fixed to the base member10with screws24.

For example, Patent Literature 1 (Japanese Patent Laid-open No. 8-106761) discloses an FPC assembly fixed to a base with screws.

BRIEF SUMMARY OF THE INVENTION

In the above prior art the screws24are used to fix the FPC assembly22to the base member10. However, more reduced size and thickness of the magnetic disk drive sometimes cause interference between the screws24and the cover member fixed to the base member10. In order to avoid such interference, the cover member is formed with holes at positions corresponding to the heads of the screw members24, respectively. Consequently, there has arisen a problem in that the sealing performance for the space defined between the base member10and cover member of the magnetic disk drive may be deteriorated.

Moreover, to fix the FPC assembly22to the base member10with the screws24, it is necessary that holes adapted to insert the screws24therethrough be formed in the FPC assembly22. This poses another problem in that, when the magnetic disk drive is reduced in size and thickness, the holes greatly restrict the layout of an electronic circuit in the FPC assembly22.

The present invention has been accomplished in view of the above-mentioned problems and it is a feature of the invention to provide a magnetic disk drive which can attain the reduction of size and thickness without deteriorating sealing performance for the space defined between the base and the cover.

According to an aspect of the present invention, a magnetic disk drive comprises a base member; a spindle motor installed on the base member; a magnetic disk adapted to be driven rotationally by the spindle motor to record information thereon; a magnetic head for read and write of information from and to the magnetic disk; a magnetic head assembly which positions the magnetic head; a cover member fixed to the base member to define a space adapted to receive therein the spindle motor, the magnetic disk, the magnetic head and the magnetic head assembly; a flexible printed circuit assembly disposed within the space so as to be urged by the cover member, the flexible printed circuit assembly transferring information to be read or written from or to the magnetic disk; and a stress member disposed between the base member and the flexible printed circuit assembly and adapted to induce stress against an urging pressure provided from the cover member.

In some embodiments, the flexible printed circuit assembly is abutted against the cover member through a leg portion extending toward the cover member.

According to the present invention, the flexible printed circuit assembly is disposed so as to be urged by the cover member. Stress against an urging pressure induced from the cover member is created by the stress member disposed between the base member and the flexible printed circuit assembly to fix the flexible printed circuit assembly. Therefore, it is not necessary to use screws and it is possible to attain the reduction in size and thickness of the magnetic disk drive without deteriorating the sealing performance for the space defined between the base and the cover.

DETAILED DESCRIPTION OF THE INVENTION

A specific embodiment for carrying out the present invention will be described below with reference to the drawings.

InFIG. 1there is shown a configuration example of a magnetic disk drive according to an embodiment of the present invention. On a base member10is provided a magnetic disk12as an information recording medium which is rotationally driven by a spindle motor30. A magnetic head assembly14is pivotably mounted to the base member10and a magnetic head16for read and write of information from and to the magnetic disk12is provided at a front edge of the magnetic head assembly14. The magnetic head assembly14is pivoted radially of the magnetic disk12by means of a voice coil motor18to position the magnetic head16.

Signals of information which the magnetic head16writes and reads from the magnetic disk12are exchanged with an external circuit with an FPC20coupled to an FPC assembly22. The FPC assembly22is urged toward the base member10by means of a cover member (not shown) and is fixed with both this urging pressure and stress of a stress member (not shown) which is disposed on the base member10. The details of how to fix the FPC assembly22will be described later.

FIG. 2is a partial sectional view of the FPC assembly shown inFIG. 1and the vicinity thereof. InFIG. 2, a cover member26is fixed to the base member10with fixing screws36to define a space therebetween adapted to receive therein the spindle motor30, magnetic disk12, magnetic head assembly14, magnetic head16, FPC20and FPC assembly22.

The FPC assembly22is formed with leg portions32extending from respective appropriate positions toward the cover member26. It is optional whether the leg portions32are to be formed by bending suitable end portions of the FPC assembly22toward the cover member26or by forming projections extending from respective appropriate positions toward the cover member26. The leg portions32are formed so that their extreme ends are abutted against the cover member26fixed to the base member10.

A stress member34is provided between the base member10and the FPC assembly22. The stress member34may preferably use, e.g., fluorine rubber, EPDM (ethylene-propylene-diene rubber) or other materials having elasticity and sealing performance, but no limitation is made thereto. Metal or the like is also employable.

FIG. 3is a partial sectional view of the FPC assembly22and the vicinity thereof for explaining how to fix the FPC assembly22. InFIG. 3, when the cover member26is fixed to the base member10, the FPC assembly is urged through the leg portions32in abutment against the cover member26. On the other hand, the stress member34is formed to a thickness greater than a gap defined between the base member10and the FPC assembly22when the cover member26is fixed to the base member10. As a result, when the FPC assembly22is urged by the cover member26, the stress member34collapses under the resulting urging pressure F1and stress F2is developed from the stress member34in a direction opposite to the urging pressure F1. With the urging pressure F1and stress F2, the FPC assembly22is fixed in the vertical direction (directions of F1and F2) inFIG. 3. Further, a frictional force is created at an abutment surface38between the cover member26and the leg portion32, whereby the FPC assembly22is fixed also in the transverse direction inFIG. 3.

Thus, the FPC assembly22can be fixed without using screws, and it becomes unnecessary to form holes in the cover member26for avoidance of interference with screws, so that the deterioration in sealing performance of the space defined by the base member10and the cover member26can be prevented. Furthermore, since it is no longer required to form tapped holes in the FPC assembly22, the restriction on the layout of the electronic circuit in the FPC assembly22can be diminished even when the size and thickness of the magnetic disk drive are reduced.

FIG. 4is a partial perspective view showing an example of formation of the stress member34. InFIG. 4, a signal transfer terminal formed in the FPC assembly22is drawn out to the exterior of the magnetic disk drive from a terminal hole40formed in the base member10. The stress member34is formed so as to surround the terminal hole40. As noted above, if the stress member34is formed of a material having sealing performance, it is possible to seal between the base member10and the FPC assembly22and hence to prevent the ingress of the outside air and dust from the terminal hole40into the magnetic disk drive.

Although inFIG. 4the stress member34formed in a rectangle with one side open, the stress member34may be formed in a rectangle so as to surround the terminal hole40.