JPH0765536A - Magnetic disc apparatus - Google Patents

Abstract

PURPOSE:To restrain a lubricating layer on a disc medium from vanishing and improve CSS characteristics by supplementing a lubricant from outside the disc medium selectively in space and instantaneously in time when a lubricating film of the disc medium is broken. CONSTITUTION:A magnetic disc medium 12 is set in a case 10 of a magnetic disc apparatus. A supplementing body 14 of a polarity (bipolar moment) lubricant impregnated with ethylene glycol or diethylene glycol is provided not on the magnetic disc medium 12, but on a fixed part. Molecules of the lubricant evaporating from the supplementing body 14 are deposited by chemical adsorption selectively on a part where a lubricating film on the disc is broken (active part), so that the lubricating film is quickly mended.

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 for recording / reproducing on / from a magnetic disk medium, and in particular,
The present invention relates to a technique for repairing a lubricating film that lubricates sliding between a magnetic disk medium and a magnetic head.

[0002]

2. Description of the Related Art A fixed magnetic disk device is often used as an external recording device of an information processing device such as a computer. A fixed magnetic disk device generally employs a CSS (contact start stop) method in which a magnetic head floats when the motor rotates and the head contacts the magnetic disk medium when the motor is stopped. The magnetic head and the magnetic disk medium come into contact with each other to be in a sliding state. When this cycle is repeated, if the wear resistance and lubrication characteristics of the magnetic disk medium are insufficient, the wear of the protective film formed on the surface of the medium progresses, and in severe cases, the magnetic layer is also damaged and crashes. May be.

FIG. 3 shows a layer structure of a general magnetic disk medium. In this magnetic disk medium, a nonmagnetic metal layer (hardened layer) 1b is formed on a nonmagnetic substrate 1a to form a nonmagnetic substrate 2, and a nonmagnetic metal underlayer 3 is laminated on the substrate 2. is there. Then, a magnetic layer 4 is formed in a thin film on the metal underlayer 3 by using a ferromagnetic alloy such as Co-Cr-Ta (cobalt-chromium-tantalum) or Co-Cr-Pt (cobalt-chromium-platinum). Laminated, and further
The protective layer 5 is formed on the magnetic layer 4. Then, a lubricating film 6 made of a liquid lubricant is provided on the protective layer 4 to form a magnetic disk medium. As the non-magnetic substrate 2, for example, an Al-Mg alloy non-magnetic substrate 1a on which a Ni-P plated layer 1b is formed by electroless plating, an alumite substrate, a glass substrate, a ceramic substrate, or the like is used. Then, the base body 2 may be polished as needed to form a rough surface (textured surface) 2a to some extent by texture or the like. This non-magnetic substrate
Nonmagnetic metal underlayer 3 made of Cr by sputtering in an Ar atmosphere while being heated to 200 ° C. 3, Co—Cr
A magnetic layer 4 made of —Ta or the like and a protective film 5 made of amorphous carbon are sequentially laminated. Then, a fluorocarbon liquid lubricant is applied on the protective film 5 to form the lubricating layer 6.

[0004]

In the fluorocarbon-based liquid lubricating layer 6 on the disk medium, the lubricant splashed from the sliding contact portion of the disk medium at the time of CSS is self-repairing to some extent by the surface tension at that portion. Since it returns and the lubricating film is re-formed, it contributes to the longer life of the disk by reducing the friction coefficient, but the repetition of the operation increases the amount of the lubricant that is splashed and scattered, and The lubricating layer 6 is consumed. For this reason, the cycle of lubricating film destruction is shorter than the film regeneration time due to surface tension, and before the self-healing function of the liquid lubrication layer 6 is exerted, the head slider moves on the disk medium without lubrication. Will slide. As a result, the self-repairing function of the liquid lubrication layer 6 becomes difficult to be exerted, deterioration of CSS characteristics and head crush are likely to occur, and there is a problem of longer life.

In view of the above problems, an object of the present invention is to replenish the lubricant from outside the disk medium spatially selectively and instantaneously with respect to the destruction of the lubricating film of the disk medium. Another object of the present invention is to provide a magnetic disk device capable of suppressing the dissipation of a lubricating layer on a disk medium and improving CSS characteristics.

[0006]

In order to solve the above problems, the means taken by the present invention is to provide a replenishing lubricant having a polarity for repairing a lubricating layer of a magnetic disk medium in a housing of a magnetic disk device. Is enclosed. The replenishing lubricant may be an inorganic substance or an organic substance, but is preferably a linear compound having no multiple bond. For example, polyhydric alcohols such as ethylene glycol or diethylene glycol. It is preferable to use a porous material impregnated with such a liquid phase supplement lubricant.

[0007]

In addition to the normal lubricating layer applied on the protective layer of the magnetic disk medium, a supplementary lubricant having the above-mentioned polarity (bipolar moment) is enclosed outside the magnetic disk medium inside the housing. In some cases, resorption lubricant chemisorption occurs on the magnetic disk media. That is, when the lubricating film is broken by sliding contact between the magnetic disk medium and the head slider, the protective layer surface (interface) is exposed as an active part at the broken part, so that a supplementary lubricant having a polarity (bipolar moment) (Gas) is adsorbed on this active site. The degree of this chemisorption depends on the strength of the polarity and the saturated vapor pressure, but as soon as an active site occurs, gas molecules of the replenishing lubricant are adsorbed to it. Therefore, when the lubricating film of the disk medium is broken, it acts spatially selectively only on the broken portion, and the repair speed is very fast. Due to the selective adsorption, the consumption of the replenishing lubricant is minimized. According to the lubrication film restoration by such chemical adsorption, dissipation of the lubrication layer on the disk medium can be suppressed, CSS characteristics can be improved, and the life of the disk and the head can be extended.

Lubricants that cause chemisorption may be those having a dipole moment, but those having multiple bonds (such as double bonds and triple bonds) that form a polymer, and cyclic compounds In some cases, particles of the lubricant itself may be a problem. This is because the presence of particles on the disk causes a head crash. Therefore, as the lubricant that does not cause such particle formation, it is desirable to use a linear compound having no multiple bonds. Experiments by the present inventor have revealed that polyhydric alcohols such as ethylene glycol or diethylene glycol are suitable. Ethylene glycol,
The dipolar moment of diethylene glycol is about 2.2 Debye, and the temperature inside the enclosure (usage temperature: usually 20-60
The saturated vapor pressure at 10 ° C is 10 ^-2 mmHg or more.
The larger the bipolar moment is, the stronger the adsorption is, and the higher the saturated vapor pressure is, the richer the gas atmosphere of the lubricant is.
A polar lubricant of 1.6 Debye or more seems to be good.

A liquid reservoir member filled with such a liquid phase replenishing lubricant may be provided in the housing of the magnetic disk device, but the liquid reservoir member is provided depending on the portability and installation method of the magnetic disk device. In this case, problems such as liquid leakage may occur, so it is advisable to use a material such as ceramic, clean paper (trade name), Kimwipe (trade name) impregnated with a porous material. Further, such a porous body can be used not only as an independent component but also as a component (washer, nut, etc.) of the magnetic disk device.

[0010]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a partially cutaway perspective view showing a magnetic disk device according to an embodiment of the present invention. In this magnetic disk device, the magnetic disk medium 12 is loaded in the housing 10 as in the conventional case. This magnetic disk medium 12
On the other hand, the magnetic head slider 13 operates by a CSS (contact start stop) method, and the magnetic head slider 13 and the magnetic disk medium 12 come into contact with each other and slide at the time of starting and stopping the rotation of the magnetic disk medium 12. It becomes a state. In the housing 10 of this magnetic disk device,
A polar (bipolar moment) lubricant replenisher 14 impregnated with ethylene glycol or diethylene glycol is provided on the fixed portion, not on the magnetic disk medium 12. This polar lubricant replenisher 14 is a sponge body (sponge body), clean paper (trade name), Kim wiper (trade name), porous ceramic body (sintered body), etc., and polyhydric alcohol such as ethylene glycol or diethylene glycol. Is impregnated with.

During operation of the magnetic disk device, the housing 10 of the magnetic disk recording device is generated by heat generated by a motor or the like.
The temperature inside is higher than room temperature, and the temperature inside the case is 20 to 6
It is about 0 ° C. At this temperature, part of the polar lubricant of ethylene glycol or diethylene glycol is vaporized (evaporated), and the saturated vapor pressure is 10 ^-2 mmHg.
As described above, the gas of the lubricant is filled around the magnetic disk medium 12. The lubricant film on the magnetic disk medium 12 may be broken by the magnetic head stider 13 when the disk starts and stops. However,
Chemical adsorption of the polar lubricant occurs on the magnetic disk medium 12. That is, when the lubricating film is destroyed by the sliding contact between the magnetic disk medium 12 and the head slider 13, the protective layer surface (interface) is exposed as an active site at the destroyed site, so that ethylene glycol having a polarity (bipolar moment) is exposed. Alternatively, the gas of diethylene glycol is immediately adsorbed on this active site to repair the lubricating film. According to the lubrication film restoration by such chemical adsorption, dissipation of the lubrication layer on the disk medium can be suppressed, CSS characteristics can be improved, and the life of the disk and the head can be extended.

FIG. 2 is a graph showing the CCSμ characteristic when diethylene glycol is used as the polar lubricant.
In the case of the conventional fluorocarbon-based liquid lubrication applied only on the magnetic disk, the dynamic friction coefficient becomes high when the number of CCS times exceeds 1000, and a head crash occurs at about 5000 times. It is presumed that this is because the lubricant in the magnetic disk was consumed and the lubrication effect decreased. However, in the CCSμ characteristic of this example, the dynamic friction coefficient does not significantly increase even when the number of CCS times exceeds 1,000. Generally, a magnetic disk requires about 10,000 times of CCS, but in this example, more characteristics can be obtained and long life is excellent. The reason why such good characteristics are obtained is considered to be that the vaporized diethylene glycol polar molecule is selectively adsorbed to the active site to restore the lubricating film.

Lubricants that cause chemisorption may be those having a dipole moment, but those having multiple bonds (such as double bonds and triple bonds) that form a polymer, and cyclic compounds In some cases, particles of the lubricant itself may be a problem. This is because the presence of particles on the disk causes a head crash. Therefore, a single bond linear compound having no multiple bond, such as ethylene glycol or diethylene glycol, is used as a polar lubricant that does not cause particle formation. Polyhydric alcohols are preferred, but --OH groups are --N
It can be inferred that the compound substituted with the H ₂ group has the same effect. Ethylene glycol and diethylene glycol have a dipole moment of about 2.2 Debye and have sufficient chemisorption. A substance with a value less than this may be used, but 1.6 Debye or more will be necessary.

Although the polar lubricant replenisher 14 is provided as a new independent component in the housing 10 in the above embodiment, the polar lubricant is added to the existing components such as washers and nuts made of a porous material. It may be impregnated. The disadvantages of increasing the number of parts and occupying space can be eliminated.

[0016]

As described above, the present invention is not based on the function of repairing a lubricating film by surface tension, but it is a polarity that repairs the lubricating film by selective chemical adsorption to the active site of the magnetic disk. It is characterized in that a lubricant having is enclosed in a housing of the magnetic disk device. Therefore, the following effects are obtained.

Since the lubricant is selectively replenished to the portion where the lubricating film is broken, it is possible to suppress the dissipation of the lubricating film on the disk and to extend the life of the lubricating effect on the disk and the head slider. It can exhibit excellent CCS characteristics.

Since the lubrication film is quickly restored by chemical adsorption, good CCS characteristics can be obtained even when the magnetic disk medium rotates at high speed.

When the replenishing lubricant is impregnated in the porous substance provided in the housing, liquid leakage can be prevented.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a graph showing CCSμ characteristics when diethylene glycol is used as a polar lubricant in Examples of the present invention.

FIG. 3 is a cross-sectional view showing a layer structure of a general magnetic disk medium.

[Explanation of symbols]

 1a ... Nonmagnetic Substrate 1b ... Nonmagnetic Metal Layer (Hardened Layer) 2 ... Base 2 3 ... Metal Underlayer 4 ... Magnetic Layer 5 ... Protective Layer 6 ... Lubrication Film 10 ... Housing 12 ... Magnetic Disk Medium 13 ... Magnetic Head Slider 14 ... Polar lubricant replenisher.

Claims (5)

[Claims] 1. In a magnetic disk device for recording / reproducing on / from a magnetic disk medium loaded in a housing, a replenishing lubricant having a polarity for repairing a lubricating layer of the magnetic disk medium is enclosed in the housing. A magnetic disk device characterized by being formed. 2. The magnetic disk device according to claim 1, wherein the replenishing lubricant is an organic substance. 3. The magnetic disk device according to claim 2, wherein the replenishing lubricant is a linear compound having no multiple bonds. 4. The magnetic disk device according to claim 3, wherein the replenishment lubricant is polyhydric alcohol. 5. The magnetic disk drive according to claim 1, wherein the replenishment lubricant is impregnated in a porous substance provided in the housing. Magnetic disk drive.