JPS6391893A - Moisture absorption mechanism for sealed type magnetic disk device - Google Patents

Abstract

PURPOSE:To improve life and reliability by providing a long pipe of a thin diameter on a respiration hole of a head disk assembly HDA and a moisture absorbent container opening part, and strengthening the functions of diffusive invasion suppressing throttle and a moisture absorption speed adjusting throttle. CONSTITUTION:As for a respiration hole 3 of a main filter 5 part, a slender pipe is used, by which a diffusive invasion suppressing effect of humidity which invades the IDA inside is strengthened. Also, when this mechanism is mounted to a personal computer, etc., such a danger as a head crush is generated due to adsorption, and an invasion caused by a diffusion is further suppressed, therefore, the constitution for strengthening an effect of the throttle by attaching externally a pipe 3' to the respiration hole 3 is also available. In this way, humidity in the HDA can be kept moderately for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention suppresses moisture that enters the inside of the HDA through the breathing holes of a head disk assembly (hereinafter abbreviated as HDA), and prevents moisture from entering the HDA. This invention relates to a moisture absorption mechanism that adjusts the rate at which moisture is absorbed by the HDA, keeps the inside of the HDA in an appropriately dry state, and prevents the magnetic disk and magnetic head from adhering to each other due to localized dew condensation when the spindle is stopped.

(2) Conventional technology In order to achieve high recording density in magnetic disk devices,
Miniaturization and stabilization of the flying gap between the magnetic disk medium surface and the recording/reproducing head are required, and for this purpose, cleaning the inside of the HDA is one of the most important issues. To achieve this, recent magnetic disks have adopted a sealed HDA structure in which the magnetic disk medium, magnetic head, magnetic head positioning 8i structure, etc. are housed in a sealed structure to prevent dust from entering from the outside. ing.

When a closed HDA is completely airtight, temperature changes create a difference in pressure between the inside of the assembly and the surroundings. This pressure difference needs to be expected to be about 0.1 atmosphere, and the pressure difference causes distortion in the sealed structure and causes track deviation. Although it is possible to increase the rigidity of the sealed structure and reduce distortion,
The size and superposition of the structure become large. In addition, the airtight seal is not only a dustproof seal, but also a 0.1
It must be a pressure seal that can withstand more than atmospheric pressure.

For this reason, a closed HDA structure that does not create a pressure difference, that is, a structure that provides a breathing hole that allows air to pass through the inside of the assembly and the outside air, should be used. Although an air filter can be installed in this hole to prevent dust from entering, it cannot prevent moisture from entering. Therefore, as the surface precision of the magnetic disk improves, the phenomenon in which the magnetic disk and magnetic head stick together due to localized dew condensation when the spindle is stopped becomes more noticeable. Even with conventional coated discs, the humidity is 80%.
If RHQ is exceeded, adsorption will occur. Furthermore, since the continuous T4 film type disk for high recording density has high surface precision, there is a risk of adsorption even in a low humidity environment. For this reason, in order to prevent moisture from entering the HD A through the breathing holes, we investigated the mechanisms of moisture intrusion and found that one is caused by air flow due to pressure difference, so-called breathing; It is produced by the diffusion of water molecules even without respiration.

As a result of quantitatively measuring these two intrusion effects,
It has become clear that when the pore size is on the order of a few, most of the moisture enters through diffusion.

Therefore, we developed a structure that does not create a significant pressure difference, limits the amount of moisture that enters through diffusion, and allows the moisture absorbent installed inside the assembly to maintain a lifespan of several years. There is a mechanism.

The base 1 and the cover 2 constitute a sealed structure, and the breathing hole 3
has a diameter of 0.25+wa and a length of IWm, and has an aperture function to suppress the diffusion and intrusion of moisture, and a pre-filter 4 is installed before and after it.
, a main filter 5 is installed to remove dust from the air. 6 is an O-ring for sealing. On the other hand, in order to control the moisture absorption rate of the moisture absorbent 7 and extend the life of the moisture absorbent, the moisture absorbent container opening 9 of the moisture absorbent container 8 has a diameter of 0.
A moisture absorption rate adjusting orifice of 6M and length 1- is provided. 10 is a filter.

With this configuration, even if the HDA is installed and the environmental humidity is 80% RH, the inside of the HDA will remain at 50% RH for more than 5 years.
%RH or less can be achieved. At this time, the amount of moisture absorbent (silica gel) required to be installed in the HDA is approximately 400 cc.

On the other hand, magnetic disks have become smaller, such as 5-inch and 3.5-inch disks.
Although HDA configurations using 5-inch disks are popular,
In many cases, the moisture absorption mechanism is implemented in the conventional configuration as shown in FIG. However, the method of configuring the moisture absorption mechanism as described above requires a large amount of silica gel to be mounted, and it is physically impossible to mount it as is. For example, 3.
The number of moisture absorbers that can be mounted on a 5-inch HDA is at most 3 c.
It is about c. Therefore, there is a need to develop a new moisture absorbing 8N structure that can absorb moisture for several years at approximately 3 CC.

(3) Purpose of the Invention The purpose of the present invention is to provide a compact moisture absorbing mechanism that has a long life and is highly reliable, which is mounted on the HDA of a small magnetic disk device.

(4) Structure of the invention (4-1) Features of the invention and differences between the prior art Therefore, in the present invention, the moisture that diffuses into the HDA is suppressed as much as possible, and in response to this, the moisture absorbent in the HDA is In order to suppress the moisture absorption capacity of the OD A, a long pipe with a narrow diameter is installed at the OD A breathing hole and the moisture absorbent container opening to strengthen the functions of the diffusion/infiltration suppressing aperture and the moisture absorption rate FJJ regulating aperture.

Furthermore, in accordance with the installation environment of the HDA, a pipe for restricting diffusion and intrusion can be added from outside the HDA, and the moisture absorbent can be replaced if it deteriorates.

(4-2) Embodiment FIG. 1 is a diagram explaining the first embodiment of the present invention.
It shows the breathing hole.

Components having the same functions as those in the prior art are given the same reference numerals, and their explanations will be omitted. 2 is the cover, 3 is the breathing hole, 5
is the main filter. A long and narrow pipe is used as the breathing hole 3, which strengthens the effect of suppressing the diffusion and intrusion of moisture entering the HDA.

FIG. 2 shows a container for a moisture absorbent installed inside the HDA, which strengthens the function of the moisture absorption rate adjusting aperture. 7 is a moisture absorbent, 9 is an opening of the moisture absorbent container, and 10 is a filter.

3. The components of FIGS. 1 and 2 are configured as shown in FIG. 6.
It was installed in a 5-inch HD A, and the performance of the moisture absorption III structure was confirmed through experiments. In the experiment, the inner diameter of the pipe for the diffusion/intrusion suppression restrictor of the breathing hole 3 was 0.3 m, the length was 20I+1!11,
A pipe with an inner diameter of 0.3+nl1l and a length of 5 was installed in the moisture absorption rate adjusting orifice of the opening 9 of the moisture absorbent container, and the pipe was kept at 25°C and 80%RH (continuously for 16 hours) in a constant temperature and humidity chamber. 4
Set an environment of 0℃, 80% R1-1 for 8 hours continuously, -
As a result of conducting an experiment with one cycle per day, the degree of gas in HDA was
43-46%RH at 25℃, 33-35% at 40℃
%, which satisfies the HDA internal humidity control target of 50% RH or less to prevent adhesion between the magnetic disk and magnetic head. According to this experiment, the water absorption type of the filter moisture absorbent is 0.33.
g/year, and if silica gel is used as a moisture absorbent, the amount of silica gel is equivalent to 1.8 cc in terms of its moisture absorption capacity.

Even under the bad environmental conditions mentioned above, the 3cc implementation achieves 1.
It has a moisture absorption life of about 7 years.

Furthermore, when implemented in personal computers etc.
Environmental conditions can be poor, increasing the risk of head crashes due to adsorption. For this reason, as shown in FIG. 3, in order to further suppress the intrusion due to diffusion, it is also possible to attach a pipe 3' to the breathing hole 3 from outside the HDA to enhance the effect of the embossment. Furthermore, Fig. 4 shows a configuration method in which a screw hole is made in the base 1 and the moisture absorbent can be replaced by attaching and removing the screw 11 so that the moisture absorbent can be replaced from outside the HDA when the moisture absorbent deteriorates. .

As explained above, the diffusion/intrusion suppression aperture and the moisture absorption rate v!
By using a thin pipe for the 4-way aperture, the humidity inside HD A can be maintained at an appropriate level. Note that when mounting the pipe, the pipe can be bent or spiraled to such an extent that the inner diameter of the pipe is not crushed.

(5) As described in detail, according to the present invention, the humidity inside the HDA can be maintained at an appropriate level over a long period of time, so that the magnetic disk surface and the magnetic head are attracted to each other due to localized condensation when the spindle is stopped. This phenomenon can be prevented, and furthermore, it is possible to add a pipe to strengthen the aperture from the outside in order to adapt to poor RR conditions, and to make it possible to replace deteriorated moisture absorbent, so it is possible to prevent the phenomenon caused by adsorption. This has the advantage of preventing head crashes and improving the reliability of the device.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the breathing hole portion of the HDA of the present invention, Fig. 2 is a block diagram of the moisture absorbent container in the HDA of the present invention, and Fig. 3 is a block diagram of the HDA of the present invention.
Figure 4 is a configuration diagram in which a diaphragm pipe is attached to the breathing hole from outside A, Figure 4 is a configuration diagram in which the moisture absorbent is replaced from outside the HDA, and Figure 5 is a partially cutaway front view of a conventional HDA. , FIG. 6 is a sectional view of a conventional small HDA. In the drawings, 1 is the base, 2 is the cover, 3 is the breathing hole, 4 is the pre-filter, 5 is the main filter, 5 is the O-ring for sealing, 7 is the 2nd agent, 8 is the moisture absorbent container, and 9 is the moisture absorbent. The agent container opening, 10 is a filter, 11 is a screw, and 3' is a pipe. Fig. 1 Fig. 3 Fig. 3' Fig. 2 Fig. 4

Claims (3)

[Claims] (1) A head disk assembly in which a base and a cover form a sealed structure includes a breathing hole for adjusting the pressure inside the assembly to be almost the same as the outside air, and a breathing hole for controlling moisture that has entered the inside of the assembly through the breathing hole. A moisture absorbing mechanism for a sealed magnetic disk drive, characterized in that an opening of a moisture absorbent container installed in the assembly for absorbing moisture is formed using a long and thin pipe having an inner diameter of a fraction of a millimeter. (2) A moisture absorption mechanism for a sealed magnetic disk drive according to claim 1, characterized in that a pipe can be added to the breathing hole from the outside of the assembly. (3) The moisture absorbing mechanism for a sealed magnetic disk drive according to claim 1 or 2, wherein the moisture absorbent in the moisture absorbent container is configured to be exchangeable from outside the assembly.