JPH05342840A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To keep tight closure without blocking up a respiration passage and to promote assembling properties by taking the open air in from the respiration passage of a diaphragm structure, absorbing its moisture with a silica gel, passing it through a respiration filter and supplying it into a shroud and also securing the respiration passage with a groove of a cap. CONSTITUTION:A respiration chamber is arranged at a hole of a lower end of a base 12, and is composed of the respiration filter 13, the cap 16 having a diaphragm respiration passage, the silica gel 14 covered with a cover and a silica gel room cover 15. The cap 16 is formed in a two-stepped cylindrical shape, where the groove in a cruciate shape is engraved on its upper surface, having a diaphragm respiration ventilating through hole 22 in the center. A step part 23 of the cap 16 is inserted into a hole of the room cover 15 to introduce the air into the cover 15 from the ventilating hole 22. The ventilating hole of the cap 16 is made to be of a diaphragm structure to reduce the intrusion of the air containing moisture, and intruded moisture is absorbed by the silica gel 14, and then the air at low humidity is passed through the respiration filter 13 to remove dust and is taken into a magnetic disk chamber. The open air is secured in communication by the groove 21 even in case the silica gel 14 is scattered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device capable of reducing the humidity inside a shroud that integrally houses a magnetic head and a magnetic disk.

[0002]

2. Description of the Related Art Generally, a magnetic disk device has a shroud (housing) for accommodating a magnetic disk and a magnetic head integrally, and a breathing passage for adjusting a pressure difference between the inside of the shroud and the outside air is provided. The inside of the shroud is required to have low humidity in order to prevent oxidation of a magnetic disk or the like and adhesion of the magnetic disk and the magnetic head by the contact start stop method (CSS method).

Therefore, in the magnetic disk device according to the prior art, as described in, for example, Japanese Patent Laid-Open No. 62-281186, a cap having an annular elongated passage in a part of the breathing passage is screwed and bonded to the shroud. The air-tight structure is adopted, and the labyrinth structure in the cap achieves low humidity, and as described in JP-A-62-73484, a hygroscopic agent (silica gel) is attached to the inner wall in a part of the breathing passage. It has been proposed to provide a desiccant case room to reduce the humidity.

[0004]

However, in the former magnetic disk device, since the cap having the annular labyrinth structure is attached to the shroud by screwing and bonding, the flatness of the contact portion between the cap and the shroud is improved. There was a problem that it was difficult to maintain a sufficient degree of sealing depending on the assembly accuracy. Specifically, if the flatness of the cap and shroud is not good and the amount of adhesive is small, it is not possible to obtain a sufficient degree of sealing, and if the amount of adhesive used is large, the passage is blocked. There was a possibility that it would end up. In addition, the former device, in relation to the pressure resistance of the magnetic fluid seal used to seal the spindle,
There is also a problem that a sufficiently low humidity cannot be secured because the pressure loss cannot be increased so much. That is, the pressure loss inside the housing of the magnetic disk device is 100 to 200 m of pressure resistance of the magnetic fluid seal used for the spindle seal.
Since it must be smaller than mAg, considering the pressure loss of the breathing filter etc., the pressure loss of the cap part is at most 50-
It has to be 100 mmAg, and there is a problem that it is difficult to secure a sufficiently low humidity because the passage cannot be lengthened.

On the other hand, in the latter magnetic disk device, the humidity is reduced by passing external air through a desiccant case chamber in which a hygroscopic agent is attached to the inner wall, but the silica gel on the inner wall of the desiccant case falls off. There was a problem that there is a possibility that it will block the vent hole to the outside air. Further, even if the silica gel is covered with the cover, there is a problem that the silica gel may scatter and block the vent hole due to an impact during transportation of the apparatus.

An object of the present invention is to eliminate the above-mentioned problems caused by the prior art, and to provide a magnetic disk device which maintains the hermeticity without blocking the breathing passage and improves the assemblability.

[0007]

To achieve the above object, in a magnetic disk drive according to the present invention, the breathing chamber has a hygroscopic material covered with a cover, a breathing passage communicating with the outside air by a throttle structure, and It is characterized by including a groove smaller than particles of a hygroscopic material engraved around the breathing passage and a breathing filter for trapping dust entering the shroud.

[0008]

The magnetic disk device constructed as described above reduces the invasion of the outside air by taking in the outside air through the breathing passage of the throttle structure, and then removes the dust absorbed by the moisture absorbing material such as silica gel by the breathing filter. Since the supplemented air is supplied into the shroud, air with low humidity and low dust can be supplied into the shroud, and even if particles of the hygroscopic material are scattered by the groove of the cap, the breathing passage is not blocked. Ingress of outside air can be secured. The grooves are not limited to those engraved on the cap, and in the present invention, in the case of a cap made of a porous material, it is considered that a plurality of small porous flow passages are randomly present on the entire surface. The entire quality opening also serves as the groove of the above embodiment.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic disk device according to an embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a cross-sectional view showing the overall configuration of the magnetic disk device according to this embodiment, FIGS. 2, 3 and 5 are views showing examples of throttle caps into which external air flows, and FIG. 4 is a silica gel life of 8 years. It is a figure which shows the relationship of a ventilation hole diameter at the time of doing, a ventilation hole length, and a pressure loss.

The magnetic disk drive according to this embodiment is shown in FIG.
As shown in FIG. 2, a magnetic disk 2 rotatably attached to a motor 1 via a spindle 3, a magnetic head 4 for recording and reproducing data on the magnetic disk 2, and a head arm 5 for supporting the magnetic head 4. A carriage 7 that supports the head arm 5 so as to be movable in the radial direction of the magnetic disk 2 by a ball bearing 8 along a guide rail 9, a coil 10, and a magnetic circuit 11.
Coil motor for linearly driving the motor, and a housing 6 for accommodating the magnetic disk 2, the spindle 3 and the like.
And a base 12 which is connected to the housing 6, accommodates the carriage 7 and the boil coil motor, and has a breathing chamber, which is a feature of this embodiment described later.
In the present embodiment, the housing composed of the base 12 and the housing 6 is called a shroud.

Now, the breathing room which is the feature of this embodiment is
As shown in FIG. 1, a cap 1 having a breathing filter 13 arranged in a hole at the lower end of the base 12 and a throttle breathing passage.
6, a silica gel 14 covered with the cap 16 and the cover, and a silica gel chamber cover 15 that covers the respiratory filter 13. The cap 16 is
It has a two-stage cylindrical outer shape, and a cross-shaped groove 21 is formed on the upper surface as shown in the plan view of FIG. 2A and the perspective view of FIG.
It is configured by opening a throttle breathing vent hole 22 penetrating through the center, and by inserting the step portion 23 of the cap 16 into the hole of the silica gel chamber cover 15 as shown in FIG.
External air is passed through the throttle structure of 2 to cover the silica gel chamber 1
5 is configured to enter.

As described above, in the magnetic disk device according to the present embodiment, the vent hole 22 of the cap 16 is formed into a narrow structure to reduce the invasion of outside air containing water, and the invading water is absorbed by the silica gel 14. The air maintained at low humidity is taken into the magnetic disk chamber after removing dust through the breathing filter 13. Further, since the vent hole 22 of the cap 16 has a limit to the water absorption performance of the silica gel 14, in order to extend the life of the silica gel, the breathing action and the spindle 3 due to the pressure change due to the temperature change at the time of starting and stopping the magnetic disk device. , Housing 6
The diameter is thin and long with a pressure loss that does not impair the sealing action of the magnetic fluid interposed between them and does not impair it.

Specifically, as shown in FIG. 4, when the life of the silica gel is 8 years, the diameter of the vent hole is d (mm, horizontal axis), the length of the vent hole is L (mm), and the pressure loss is h (mmA
g, vertical axis), the pressure loss needs to be 50 mmAg or less based on the experimental data shown in FIG. 4, and accordingly, the vent hole diameter d may be 0.6 mm or more. Considering the margin, if the diameter is 0.8 mm, the length of the vent hole is required to be 9 mm or more, so it may be determined to be 11 mm, for example. With such a size, it is a sufficiently compact size for a device incorporating the magnetic disk 2 of about 8 to 10 inches.

Further, the cross-shaped groove 21 formed on the upper surface of the cap 20 prevents the particles of the silica gel 14 covered with the cover from closing the ventilation hole 22 of the cap 16 when the particles leak. The particles are smaller than the particles. That is, even if the particles of the silica gel 14 leak from the cover and get on the cap 20, the groove 21 can ensure communication with the outside air.

As described above, in the magnetic disk drive according to the present embodiment, the cap 16 that allows the outside air to enter the silica gel chamber cover 15 has a throttle structure to suppress the amount of outside air entering, and the silica gel inside the silica gel chamber 14 prevents the moisture contained in the outside air. The reduced air can be supplied to the inside of the shroud through the breathing filter 13. Further, by providing the cross-shaped groove 21 on the upper surface around the vent hole 22 of the cap 16, it is possible to prevent the vent hole 22 from being blocked even when the particles of the silica gel 14 leak. .. Further, in the magnetic disk device according to the present embodiment, since the step of the cap is fitted in the hole of the silica gel chamber, the assembling workability is good and the surface processing accuracy of these parts is not required as compared with the conventional one.

FIG. 3 is a view showing a cap 30 according to another embodiment. The cap 30 according to the present embodiment has a plurality of through holes 32 formed therein, and has the same throttle structure as the through holes 22 according to the above embodiments, so that the amount of invasion of outside air can be suppressed.

The caps 20 and 3 in the above embodiments
Although the groove of 0 has a cross shape, the groove according to the present invention is not limited to the cross shape, and more grooves may be provided.
Further, each of the caps 20 and 30 may be formed by integral molding of, for example, plastic or the like, and may be bonded to the cover of the silica gel 14. Further, the cap according to the present invention is not limited to the one having the through hole, and may be constituted by a cap 40 made of a water repellent porous material as shown in FIG. Since it is considered that a plurality of small flow passages are randomly present on the entire surface of the cap 40, the entire porous opening portion also serves as the groove of the above embodiment. However, the thickness and size of the cap 40, the size of the cap 4 and the size of the cap 4 should be large enough to prevent the invasion of outside air containing water.
It is necessary to set the hole diameter of the silica gel chamber cover 15 to which 0 is attached.

[0018]

As described above, the magnetic disk device according to the present invention reduces the invasion of the outside air by taking in the outside air through the breathing passage of the throttle structure, and then the air absorbed by the moisture absorbing material such as silica gel is used as the breathing filter. To supply air supplemented with dust into the shroud,
Air with low humidity and low dust can be supplied into the shroud, and even if particles of the hygroscopic material are scattered by the groove of the cap, it is possible to ensure the invasion of outside air without blocking the respiratory passage. Further, the groove is not limited to the one engraved in the cap, and in the present invention, in the case of a cap made of a porous material, it is considered that a plurality of small flow passages are randomly present on the entire surface, and therefore the porous opening is formed. The whole also serves as the groove of the above-mentioned embodiment.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment of a cap according to the present invention.

FIG. 3 is a view showing another embodiment of the cap according to the present invention.

FIG. 4 is a diagram showing the relationship between the vent hole diameter, the vent hole length, and the pressure loss of the cap according to the present invention.

FIG. 5 is a view showing still another embodiment of the cap according to the present invention.

[Explanation of symbols]

1 ... Motor, 2 ... Magnetic disk, 3 ... Spindle, 4 ...
Magnetic head, 5 ... Head arm, 6 ... Housing, 7 ...
Carriage, 8 ... Ball bearing, 9 ... Rail, 10 ... Coil,
11 ... Magnetic circuit, 12 ... Base, 13 ... Breathing filter,
14 ... Silica gel, 15 ... Silica gel chamber cover, 16 ...
Caps, 16a, 16b, 16c ... Caps.

Front page continued (72) Inventor Kenki Nagaya 2880 Kokufu, Odawara-shi, Kanagawa Hitachi Ltd. Odawara factory (72) Inventor Satoshi Matsuki 2880, Kozu, Odawara, Kanagawa Hitachi Ltd. Odawara factory

Claims (1)

[Claims] 1. A magnetic disk device comprising a rotating magnetic disk and a magnetic head for recording / reproducing data on / from the magnetic disk, which is integrally housed in a shroud, the shroud having a breathing chamber communicating with the outside air. The breathing chamber enters the shroud, the moisture-absorbing material covered by the cover, the breathing passage communicating with the outside air in a throttle structure, the groove smaller than the particles of the moisture-absorbing material engraved around the breathing passage, and the groove. A magnetic disk device comprising: a breathing filter for capturing dust.