Magnetic disk device

In a magnetic disk device, a magnetic circuit drives an actuator carrying a magnetic head, so that the magnetic head is moved to a target track on a surface of a magnetic disk. A base has a threaded-hole part to which the magnetic circuit is fastened with a screw. A blocking member is provided to enclose a gap which is formed between the magnetic circuit and the threaded-hole part when the magnetic circuit is fastened to the threaded-hole part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2005-219109, filed on Jul. 28, 2005, the entire contents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a magnetic disk device, and more particularly to a magnetic disk device which performs recording/reproducing processing to a magnetic disk by driving an actuator on which a magnetic head is provided, by using a magnetic circuit attached to a base.

2. Description of the Related Art

FIG. 1throughFIG. 4are diagrams for explaining the composition of a conventional magnetic head device100.

FIG. 1is a perspective view showing the conventional magnetic disk device100, andFIG. 2is a cross-sectional view of the magnetic disk device100taken along the line X1-X1indicated inFIG. 1.FIG. 3is a perspective view showing the mounting structure of a magnetic circuit150(described later) in the magnetic disk device100, andFIG. 4is an enlarged cross-sectional view showing the neighborhood portion of a screw126in the state where the magnetic circuit150is fixed to the base113.

As shown inFIG. 1throughFIG. 4, the actuator122supports the head slider114on which a magnetic head is mounted, and the actuator122is supported on the shaft140such that the actuator122can be swung around the shaft140. The voice coil151is mounted at the rear-end part of the actuator122behind the shaft140.

The voice coil151is driven by the magnetic circuit150so that the actuator122is swung around the center of the shaft140.

The magnetic circuit150is constituted by the upper yoke153A, the lower yoke153B, the upper magnet155A, and the lower magnet155B. As shown inFIG. 2andFIG. 3, the upper magnet155A is disposed on the bottom surface of the upper yoke153A, and the lower Magnet155B is disposed on the top surface of the lower yoke153B.

A gap is formed between the upper magnet155A and the lower magnet155B, and the voice coil151of the actuator122is movably disposed in this gap.

The voice coil151, the upper yoke153A, the lower yoke153B, the upper magnet155A, and the lower magnet155B constitute the voice coil motor123(VCM). This voice coil motor123serves as a source of a drive which swings the actuator122around the center of the shaft140.

In the following explanation, it is supposed that the upper and lower yokes153A and153B and the upper and lower magnets155A and155B, excluding the voice coil151, among the components of the voice coil motor123, constitute a magnet circuit150, and these are called the components of the magnetic circuit150.

In the magnetic disk device100, it is necessary to position the head slider114(magnetic head) at a given location on the magnetic disk101with high precision, in order to perform proper magnetic recording/reproducing processing.

For this reason, the actuator122and the shaft140which supports the actuator122are disposed on the base113with high precision. Under the present circumstances, in order to keep an appropriate state of the head slider114(magnetic head) and the magnetic disk101at the time of recording/reproducing, accurate positioning of the actuator122and the shaft140in the height direction on the base113is important.

Moreover, the voice coil151of the actuator122which is disposed with high precision is inserted in the magnetic circuit150, and it is also necessary to raise the accuracy of positioning of the magnetic circuit150in the height direction on the base113.

For this reason, as shown inFIG. 3, a reference-height projection124is formed in the bottom plate113A of the base113, and the magnetic circuit150is placed on this reference-height projection124, so that the height arrangement of the magnetic circuit150on the base113is thereby determined.

The reference-height projection124is formed with high precision, and placing the magnetic circuit150on the reference-height projection124enables good height accuracy to be attained.

Moreover, the magnetic circuit150is provide with washer parts150, and each washer part150has a through hole which passes through the screw126being inserted. Therefore, the magnetic circuit150is fixed to the base113by inserting the screws126in the through holes of the washer parts156and fastening them to the threaded-hole parts125.

Moreover, the magnetic circuit150is provided with washer parts156, and each washer part156has a through hole which passes through the screw126being inserted. Therefore, the magnetic circuit150is fixed to the base113by inserting the screws126in the through holes of the washer parts156and fastening them to the threaded-hole parts125.

As described above, if the height accuracy of the actuator122and the magnetic circuit150on the base113is kept good, it is possible to maintain an appropriate state of the head slider114(magnetic head) and the magnetic disk101at the time of recording/reproducing.

In order to maintain an appropriate state of the head slider114(magnetic head) and the magnetic disk101, it is necessary to ensure that dust (contamination) may not enter the magnetic disk device100. If dust enters the space between the magnetic disk101and the head slider114, there is a possibility that the magnetic surface formed in the surface of the magnetic disk101, and the sliding-contact surface of the magnetic head may be damaged (head crash).

To obviate the problem, various countermeasures for preventing occurrence of dust have been proposed conventionally. For example, see Japanese Laid-Open Patent Application No. 2004-296011.

By the way, when the mounting structure in which the magnetic circuit150is placed on the reference-height projection124is used to raise the height accuracy of the mounting structure as mentioned above, it is difficult to firmly fix the magnetic circuit150to the threaded-hole parts125. In other words, if the magnetic circuit150is firmly fixed to the threaded-hole parts125, the reference-height projection124is crushed and the height accuracy will deteriorate.

For this reason, it is necessary to provide a design gap between the upper surface of the threaded-hole part125and the washer part156in the state where the magnetic circuit150is attached to the base113as shown inFIG. 4. InFIG. 4, ΔH indicates this gap.

However, because of the use of the gap ΔH, there is a possibility that the threaded-hole part125remains exposed to the inside of the magnetic disk device, which causes occurrence of dust (contamination).

When the screws126are fastened to the threaded-hole parts125, or when the screws126are removed from the threaded-hole parts125, a possibility that dust from the threaded-hole parts125may be scattered inside the magnetic disk device100becomes high. Thus, if dust (contamination) from the threaded-hole parts125is scattered inside the magnetic disk device100, such dust may cause a head crash to take place as described above.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved magnetic disk device in which the above-mentioned problems are eliminated.

Another object of the present invention is to provide a magnetic disk device which is capable of preventing the dust from being scattered inside the magnetic disk device, even when a gap is provided between the upper surface of the threaded-hole part and the washer part in the state where the magnetic circuit is attached to the base.

In order to achieve the above-mentioned objects, the present invention provides a magnetic disk device comprising: a magnetic circuit driving an actuator carrying a magnetic head, so that the magnetic head is moved to a target track on a surface of a magnetic disk; a base having a threaded-hole part to which the magnetic circuit is fastened with a screw; and a blocking member provided to enclose a gap which is formed between the magnetic circuit and the threaded-hole part when the magnetic circuit is fastened to the threaded-hole part.

According to the above-mentioned magnetic disk device of the invention, the gap formed between the magnetic circuit and the threaded-hole part is enclosed by the blocking member, and even if dust occurs from the threaded-hole part when the magnetic circuit is fastened to the threaded-hole part, such dust does not leak out of the exterior of the blocking member. Therefore, the dust from the threaded-hole part does not adhere to the space between the magnetic head and the magnetic disk, and it is possible to increase the reliability of the magnetic disk device.

Moreover, the above-mentioned magnetic disk device may be configured so that the blocking member is a tubular member which is made of an elastic material.

According to the above-mentioned magnetic disk device of the invention, the blocking member is the tubular member which is made of the elastic material, and the tubular member made of the elastic material as the blocking member can be easily obtained and it is possible to attain low-cost production of the blocking member.

Moreover, the above-mentioned magnetic disk device may be configured so that the tubular member comprises a fixed portion fixed onto the threaded-hole parts and a projecting portion upwardly projecting from the threaded-hole part and contacting the magnetic circuit with an elastic deformation.

According to the above-mentioned magnetic disk device of the invention, the tubular member comprises the fixed portion and the projecting portion. The fixed portion of the tubular member is fixed onto the threaded-hole part, and the attaching characteristic of the blocking member to the threaded-hole part can be increased. And the projecting portion of the tubular member upwardly projects from the threaded-hole part and contacts the magnetic circuit with an elastic deformation. The adhesion of the blocking member to the magnetic circuit becomes appropriate, and it is possible to prevent more certainly the leakage of dust out of the exterior of the blocking member.

Moreover, the above-mentioned magnetic disk device may be configured so that a reference-height projection is formed on the base, and the magnetic circuit is placed on the reference-height projection so that positioning of the magnetic circuit in a height direction on a bottom plate of the base is performed.

According to the above-mentioned magnetic disk device of the invention, the reference-height projection is provided on the base, and the magnetic circuit is placed on the reference-height projection so that positioning of the magnetic circuit in the height direction on the bottom plate of the base is performed.

In this composition, it is inevitably necessary to form a gap between the threaded-hole part and the magnetic circuit, in order to raise the accuracy of the positioning in the height direction. However, this gap is enclosed by the blocking member, and it is possible to prevent the leakage of dust while the accuracy of the positioning is maintaining at a high level.

Moreover, the above-mentioned magnetic disk device may be configured so that the threaded-hole part is arranged in a column formation which projects from the bottom plate of the base. According to the above-mentioned magnetic disk device of the invention, the blocking member can be easily attached to the threaded-hole part.

Moreover, the above-mentioned magnetic disk device may be configured so that the tubular member is made of an elastic material which is either a rubber or a resin. The elastic material, such as a rubber or a resin, is inexpensive and very stable, and it is possible to increase the adhesion of the blocking member to the magnetic circuit.

Moreover, the above-mentioned magnetic disk device may be configured so that the blocking member is a packing member which is made of an elastic material. The elastic material, such as a rubber or a resin, is inexpensive and very stable, and it is possible to attain low-cost production of the blocking member.

According to the above-mentioned invention, it is possible to prevent the dust from the threaded-hole part from being scattered inside the magnetic disk device. Thus, there is no possibility that the dust from the threaded-hole part adheres to the space between the magnetic head and the magnetic disk, and it is possible to increase the reliability of the magnetic disk device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A description will now be given of a preferred embodiment of the invention with reference to the accompanying drawings.

FIG. 5throughFIG. 8are diagrams for explaining the composition of a magnetic disk device10in an embodiment of the invention.

FIG. 5is a perspective view showing magnetic disk device10in the embodiment of the invention, andFIG. 6is a cross-sectional view of the magnetic disk device10taken along the line X2-X2indicated inFIG. 5.FIG. 7is a perspective view showing the mounting structure of a magnetic circuit15(described later) in the magnetic disk device10, andFIG. 8is an enlarged cross-sectional view showing the neighborhood portion of a screw26in the state where the magnetic circuit15is fixed to a base13.

As shown inFIG. 5throughFIG. 8, the magnetic disk device10comprises a magnetic disk11, a spindle motor12, an actuator22, and a voice coil motor (VCM)23, and these components are accommodated in the enclosure including a cover (its illustration being omitted) and the base13. The magnetic disk11is a data recording medium. The spindle motor12is provided to rotate the magnetic disk11. In the actuator22, a head slider14on which a magnetic head is mounted is implemented. The voice coil motor (VCM)23drives the actuator22so that the actuator22is swung around a shaft40.

The magnetic disk11is fixed to the rotor part of the spindle motor12. The magnetic disk11is rotated by the spindle motor12at the time of operation of the magnetic disk device10(or at the time of recording/reproducing processing). The rotation of the magnetic disk11is stopped in the non-operating state of the magnetic disk device10.

The actuator22is rotatably supported on the shaft40provided on the base13, such that the actuator22can be swung around the shaft40. This actuator22includes a support arm and a coil arm. The head slider14is disposed on the front end part of the support arm of the actuator22through a support spring.

The head slider14is disposed so that the head slider14faces the magnetic disk11. The head slider14is provided with the magnetic head (not shown), and the magnetic head is provided to write the data from the control part (not shown) to a track on the surface of the magnetic disk11, and provided to read the data from the track of the magnetic disk11and transfer the read data to the control part. This head slider14is provided so that the head slider14is lifted over the surface of the rotating magnetic disk11when the magnetic disk device10is in the operating state.

Moreover, the voice coil51is disposed at the rear-end part of the coil arm of the actuator22. This voice coil51is associated with the magnetic circuit15and constitutes the voice coil motor23. The magnetic circuit15is provided to drive the actuator22so that the actuator22is swung around the center of the shaft40and the magnetic head carried on the actuator22is moved to a target track on the surface of the magnetic disk11.

The magnetic circuit15is constituted by the upper yoke53A, the lower yoke53B, the upper magnet55A, and the lower magnet55B. As shown inFIG. 6andFIG. 7, the upper magnet55A is disposed on the bottom surface of the upper yoke53A, and the lower magnet55B is disposed on the top surface of the lower yoke53B.

A gap is formed between the upper magnet55A and the lower magnet55B, and the voice coil51of the actuator22is movably disposed in this gap. The voice coil motor23(VCM) is constituted by the voice coil51, the upper yoke53A, the lower yoke53B, the upper magnet55A, and the lower magnet55B.

In this embodiment, it is supposed that the upper and lower yokes53A and53B and the upper and lower magnets55A and55B, excluding the voice coil51among the components of the voice coil motor23, constitute the magnetic circuit15.

As previously described, it is necessary to position the head slider14(magnetic head) at a given location on the magnetic disk11with high precision, in order for the magnetic disk device10to perform proper magnetic recording/reproducing processing.

For this reason, the actuator22and the shaft40which supports the actuator22are disposed on the base13with high precision. Under the present circumstances, in order to keep an appropriate state of the head slider14(magnetic head) and the magnetic disk11at the time of recording/reproducing processing, accurate positioning of the actuator22and the shaft40in the height direction on the base13is important as previously described.

Moreover, the voice coil51of the actuator22which is disposed with high precision is inserted in the magnetic circuit15, and it is also necessary to raise the accuracy of positioning of the magnetic circuit15in the height direction on the base13.

For this reason, as shown inFIG. 7, a reference-height projection24is formed in the bottom plate13A of the base13, and the magnetic circuit15is placed on this reference-height projection24, so that the height arrangement of the magnetic circuit15on the base13is thereby determined.

The reference-height projection24is formed with high precision, and placing the magnetic circuit15on the reference-height projection24enables good height accuracy to be attained.

Moreover, to fix the magnetic circuit15to the base13, screws26are used as shown inFIG. 7. The threaded-hole parts25in which the threaded holes are formed are provided in the base13so that the screws26are fastened to the threaded-hole parts25. The threaded-hole parts25are arranged in a column formation which projects from the bottom plate13A of the base13. In addition, the magnetic circuit15is provided with washer parts56, and each washer part56has a through hole which passes through the screw26being inserted.

Therefore, the magnetic circuit50is fixed to the base13by inserting the screws26in the through holes of the washer parts56and fastening the screws26to the threaded-hole parts25. Under the present circumstances, in this embodiment, the magnetic circuit15is placed on the reference-height projection24, and thereby the height accuracy of the actuator22and the magnetic circuit15to the base13is determined with high precision. Thus, it is possible to keep an appropriate state of the head slider14(magnetic head) and the magnetic disk11at the time of recording/reproducing.

Moreover, the magnetic disk device10in this embodiment comprises blocking members30which are provided between the washer parts56and the threaded-hole parts25respectively (seeFIG. 7andFIG. 8).

The blocking members30are made of an elastic material, such as a rubber or a resin. The blocking members30are arranged in a tubular formation. The inside diameter of the blocking members30is set up so that it is slightly smaller than the outside diameter of the threaded-hole parts25.

Before the magnetic circuit15is attached to the base13, the blocking members30of the tubular formation are attached to the threaded-hole parts25.

The threaded-hole parts25are arranged in a column formation which projects from the bottom plate13A of the base13, and the blocking members30are arranged in a tubular formation. Thus, attaching the blocking members30to the threaded-hole parts25can be performed easily.

Moreover, the blocking members30are made of an elastic material, such as a rubber or a resin, and have the tubular formation, and they can be obtained with low cost. For this reason, even if the magnetic disk device10is equipped with the blocking members30, the cost of the magnetic disk device10does not become excessively high.

After the blocking members30are attached to the threaded-hole parts25, the upper parts of the blocking members30upwardly project by a predetermined height on the upper end of the threaded-hole parts25.

In the following description, in the state where each blocking member is attached to the threaded-hole part25, a portion of the blocking member30currently fixed onto the threaded-hole part25is called a fixed portion30A, and the remaining portion of the blocking member30which is projecting from the upper end of the threaded-hole part25is called a projecting portion30B (refer toFIG. 8).

By the way, when the mounting structure in which the magnetic circuit15is mounted on the reference-height projection24to raise the height accuracy of the mounting structure as described above, it is difficult to firmly fix the magnetic circuit15to the threaded-hole parts25. In order to prevent the reference-height projection24from being crushed, it is necessary to provide a gap ΔH between the upper surface of the threaded-hole part25and the washer part56. InFIG. 8, ΔH indicates this gap.

In the conventional magnetic disk device, there is a possibility that the dust from the threaded-hole part125may be scattered inside the magnetic disk device, because of the use of the gap ΔH. Such dust may cause a head crush to take place.

However, according to this embodiment, the blocking members30are attached to the threaded-hole parts25, and the projecting portions30B of the blocking members30upwardly project from the upper ends of the threaded-hole parts25.

Moreover, the projection height of each projecting portion30B is set up so that it is larger than the height of the above-mentioned gap ΔH. Therefore, when the magnetic circuit15is fastened to the threaded-hole parts25by the screws26, the projecting portions30B of the blocking members30contact the washer parts56, and the gap ΔH formed between the magnetic circuit15and the threaded-hole parts25is enclosed by the blocking members30(or specifically by the projecting portions30B of the blocking members30).

Under the present circumstances, the projecting portions30B contact the washer parts56with an elastic force, and the fitting of the blocking members30and the washer parts56can be maintained with high airtightness.

Accordingly, even if dust occurs from the threaded-hole parts25when attaching the screws26to the threaded-hole parts25or detaching the screws26from the threaded-hole parts25, such dust does not lead out from the exterior of the blocking members30.

The dust from the threaded-hole parts25does not adhere to the space between the magnetic head and the magnetic disk11, and it is possible to prevent occurrence of a head crush. Therefore, the reliability of the magnetic disk device10can be increased.

In the above-mentioned embodiment, the tubular-form rubber parts are used as the blocking members30. However, the blocking members30are not limited to the tubular-form rubber parts. For example, it is also possible to use packing parts made of an elastic material as the blocking members30.

Moreover, in the above-mentioned embodiment, the head parts of the screws26contact the washer parts56directly. Alternatively, in order to prevent the scattering of the dust into the magnetic disk device more certainly, packing materials may be provided between the head parts of the screws26and the washer parts56, which prevent the scattering of dust inside the magnetic disk device10, by using the through holes of the washer parts56.

The present invention is not limited to the above-described embodiment, and variations and modifications may be made without departing from the scope of the present invention.