JPS61115291A - Magnetic disc recording device - Google Patents

Abstract

PURPOSE:To prevent the generation of a thermal off track, by constructing the housing so that the inside pressure can be reduced with the similar effect as in case of using the enclosed gaseous He. CONSTITUTION:The inside of the airtight housing composed of an airtight cover 7 and a base rack 1 is evacuated by a vacuum pump through a vacuum open/close valve, and the pressure of the inside the housing is reduced to, for example, 20% of the atmospheric pressure. When the pressure is reduced to such an extent, the static viscosity coefficient mu changes only little extent without making a bit difference, and it can be regarded approximately as the same. The viscous friction loss T in the low pressure is about 27% which is roughtly the same to the case where the gaseous helium is enclosed, thus bringing about the similar effect. Namely, it is possible to reduce the viscous friction loss against the inside of atmosphere of the magnetic disc device rotating in high speed and the heat due to the air friction, by reducing the pressure instead of enclosing the gaseous helium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk recording device, and relates to a device configuration that prevents a temperature rise in an airtight housing in a sealed magnetic disk recording device and reduces thermal off-track. It is about improvement.

In recent years, in magnetic disk recording devices, dust has been removed from the atmosphere surrounding the magnetic disk medium that rotates at high speed.
In order to prevent the occurrence of head cracking, a sealed structure is adopted in which the magnetic disk medium rotated by a rotational drive mechanism and the magnetic head mechanism section that records and reproduces information on the medium are hermetically housed. There is.

However, in the above-mentioned sealed magnetic disk recording device, the temperature inside the airtight housing increases significantly due to heat generation due to air friction (windage damage) that occurs when the magnetic disk medium rotates at high speed, and thermal off-trunk etc. occur. There were problems with reliability.

For this reason, some device configurations have been proposed in which outside air is circulated inside the sealed cover via a dust filter to prevent the internal temperature from rising. However, with the above configuration, it is difficult to completely remove outside air dust. In this case, there is a need for a structure that not only removes dust from the atmosphere surrounding the magnetic disk medium but also prevents a rise in temperature within the airtight housing.

[Conventional technology]

Conventionally, as a device configuration capable of removing dust from the atmosphere surrounding the magnetic disk medium and preventing a rise in temperature within the airtight housing, air is replaced with air in the housing of a sealed magnetic disk recording device. Stable, low-density helium (He) gas, etc. is hermetically sealed in the disk to reduce air friction (windage loss) that occurs when the magnetic disk medium rotates at high speed.
Attempts have been made to create a structure that reduces the heat generated by the engine, equalizes the temperature inside the housing, and prevents thermal off-trunk and the like.

[Problem that the invention seeks to solve]

However, the device configuration in which helium (He) gas or the like is hermetically sealed in the housing as described above has the advantage of being extremely effective in preventing thermal off-track, etc., but on the other hand, the helium (He) Since He) gas has a very small atomic radius and low viscosity, it has the property of leaking much more easily than other inert gases, rare gases, and the like.

For this reason, the structure of the gas-filled portion requires a highly airtight structure, and there is a problem in that the sealed magnetic disk recording device becomes bulky.

[Means for solving problems]

The above-mentioned problem arises in a device configuration in which a magnetic disk medium rotated by a rotary drive mechanism and a magnetic head for recording and reproducing information on the medium are housed in an airtight housing, and the air pressure inside the housing is reduced. This problem is solved by a magnetic disk recording device according to the present invention.

[Effect]

That is, instead of filling the housing that airtightly houses the functional parts of the device with helium gas, the viscous friction loss against the internal atmosphere of the magnetic disk medium rotating at high speed is reduced.
By creating a configuration in which the pressure is reduced to at least the same level as when filled with helium gas, it is possible to reduce heat generation due to wind damage of the high-speed rotating magnetic disk medium over a long period of time, comparable to when filled with helium gas, which tends to leak. Therefore, it is possible to prevent the occurrence of thermal off trunk.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

The drawing is a schematic cross-sectional view for explaining an embodiment of a magnetic disk recording device according to the present invention.

As shown in the figure, a plurality of magnetic disk media 4 are attached to a spindle 3 of a rotating mechanism 2, and an access mechanism 5 is accessed by the access mechanism 5 to record information on each of the magnetic disk media 4. On top of the device base 1, which is equipped with a magnetic head 6 for reproducing the recorded information and has a rib-reinforced structure, a sealing cover 7, which also has a rib-reinforced structure, is attached to a vacuum O-ring as in the past. etc. are sealed through.

Further, the inside of the airtight housing constituted by the sealing cover 7 and the base 1 is evacuated by a vacuum pump or the like via the vacuum opening/closing pulp 8 to reduce the internal pressure to at least 2 atmospheric pressure.
The pressure is reduced to approximately 0% (0.2 atm).

When the internal pressure inside the housing is reduced to about 0.2 atmospheres, the viscous friction loss torque T between the magnetic disk medium 4, which rotates at high speed, and the air is expressed as follows: ρ: Heavy density μ
: static viscosity coefficient, R: disk radius, ω: rotational speed, it is expressed by the following formula.

T=0.0622・ρ÷・μ・R1・ω Therefore, in the above equation, the density ρ is simply proportional to the pressure, and the static viscosity coefficient μ changes only slightly, without much difference, and is almost constant. As can be seen, the viscous friction loss torque T in the reduced pressure state is about 27%, which is about the same level as when helium gas is sealed, and the same effect can be obtained.

Note that the sealed structure in the above embodiment requires considerable rigidity and airtightness due to the pressure difference with atmospheric pressure due to depressurization, but the purpose can be sufficiently achieved by creating an airtight structure equivalent to that of a vacuum device, etc. I can do it.

[Effects of the Invention] As is clear from the above description, according to the magnetic disk recording device of the present invention, instead of filling the housing that airtightly houses the above-mentioned functional parts of the device with helium gas, which tends to leak. By reducing the pressure to the internal atmosphere of the magnetic disk medium rotating at high speed,
That is, it has excellent advantages such as being able to significantly reduce heat generation due to windage damage, improving reliability and saving power.

Therefore, it is extremely advantageous for use in high-density recording and large-capacity magnetic disk recording devices.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view for explaining an embodiment of a magnetic disk recording device according to the present invention. In the figure, l is the device base, 2 is the rotation mechanism, 3 is the spindle,
4 is a plurality of magnetic disk media; 5 is an access mechanism; 6
7 indicates a magnetic throat, 7 indicates a sealing cover, and 8 indicates a vacuum opening/closing valve.

Claims (1)

[Claims] A magnetic disk medium rotated by a rotation drive mechanism and a magnetic head for recording and reproducing information on the medium are housed in an airtight housing. Disc recording device.