JP2002288822A - Magnetic disk device and defective registration method on magnetic disk medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability of a magnetic disk device by detecting a defective area on a magnetic disk medium with high sensitivity over large area, registering the defective area and not carrying out the data read/write on a registered area. SOLUTION: This method is a defective registration method on the magnetic disk medium in a magnetic disk device comprising a magnetic disk 2, a spindle motor, and a magneto resistive head 1 utilizing a magneto resistive element as a reading element of data. In this method, a whole magnetic disk device is held in a constant temperature bath 6 used in the temperature performance test, and a temperature in the constant temperature bath is set to the range from 50 deg.C to 60 deg.C higher than a normal operation temperature of the magnetic disk device. An area on the magnetic disk medium where a read error generates in a reading examination by using the magneto resistive head 1 is beforehand registered as the defective area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic disk drive, and more particularly, to a method for registering a defect on a magnetic disk medium used in the magnetic disk drive and a magnetic disk drive.

[0002]

2. Description of the Related Art In a magnetic disk drive, when a plurality of magnetic recording defects exist on a magnetic disk medium, those positions are registered as defectives. At the time of actual operation, based on the registered data, a control method in which data is not read / written in a sector having a defect is employed.

[0003] A conventional method for registering a defective portion on a magnetic disk device medium will be described. Before assembling the magnetic disk medium into the magnetic disk device, it is confirmed in advance that there is no defective portion on the magnetic disk medium. As a checking method, the surface of the magnetic disk medium is scanned using a contact detection type head having a lower flying height than the magnetic head in a normal state. When a defect exists on the magnetic disk medium, the contact detection sensor mounted on the head reacts and generates an output signal. When the magnetic disk medium is shipped, if the output signal falls below the criterion, it is determined that there is no defect.

Next, after assembling the confirmed magnetic disk medium into a magnetic disk device, the magnetic head is scanned over all cylinders on the magnetic disk medium to search for a defective portion of the magnetic disk medium. When a defect is found, the position information is recorded at a predetermined position on the magnetic disk medium. And
A series of operations described above were performed in a normal temperature state.

Further, T.I. A. A technique for preventing a read error caused by the phenomenon beforehand is disclosed in Japanese Patent Application Laid-Open No. 8-279239.
No. 6,086,045. According to the disclosure of this publication, in order to ensure the reliability of the operation of the magnetic disk device at high altitude, the pressure of the magnetic disk device is reduced to a pressure matching the device specifications, and the search for abnormal protrusions on the magnetic disk medium is performed. The registration is shown to be performed.

[0006]

Due to the miniaturization and high-density of the magnetic disk drive, the magnetic head used in the magnetic disk drive has recently been mainly a magnetoresistive head (hereinafter, MR head). The MR head employs a method in which the electric resistance of the ferromagnetic MR element changes due to the influence of an external magnetic field written on the medium, and the change is reproduced and used as a signal. Therefore, a sudden change in the electric resistance of the magnetoresistive element (MR element) causes a movement of the DC component of the reproduction signal, which causes a read error.

Actually, when the magnetic disk medium comes into contact with the MR head element portion, the contact heat often causes a rapid temperature rise in the MR element portion, and the electrical resistance of the MR element often changes. The phenomenon that leads to a read error due to this contact is called a thermal asperity (hereinafter TA) phenomenon.

[0008] T. A. Is caused by the contact between the MR head and the magnetic disk medium. In particular, it often occurs due to the contact with a protrusion existing on the surface of the magnetic disk medium. These protrusions are dust particles generated during film formation on the magnetic disk medium,
These are defects that the magnetic disk medium initially has, such as surface defects of a glass substrate. Therefore, a read error caused by a defect can be prevented to some extent by the initial registration of the defective portion.

However, the distance between the MR head of a recent magnetic disk drive and the magnetic disk medium has been reduced to 10 to 20 nm. On the other hand, the height of a protrusion on a magnetic disk medium is often about 10 nm. For this reason, the gap between the protrusion tip height and the MR element has a margin of only several nm. Since the flying height of the MR head fluctuates due to external factors, there is a possibility that the MR element and the protrusion on the medium surface come into contact with a certain probability. A. Will occur.

Although the magnetic disk medium has been confirmed in advance to be free of protrusions by a contact detection type head, the output signal from the contact detection sensor mounted on the head is actually less than the judgment reference output. In this case, it is determined that there is no protrusion. For this reason, a small protrusion near the determination reference may slip through at a certain probability. Even with such a small protrusion, by directly contacting the MR element, the T.V. A.
It may be.

Even when the magnetic disk medium is initially in a normal state without protrusions, foreign matter such as dust is embedded in the magnetic disk medium when the magnetic disk apparatus is incorporated, and the MR element comes into contact with the buried substance. A. May occur. Further, an organic substance existing in the magnetic disk device adheres to the surface of the magnetic disk medium, and the adhered substance comes into contact with the MR element. A. In some cases,

Further, according to the technique disclosed in Japanese Patent Application Laid-Open No. Hei 8-279239, an environment and conditions equivalent to those at the time of operation of a magnetic disk drive at a high altitude are created, and abnormal projections are detected under the environment and conditions. However, when a read error is detected, an extra step of preparing the decompression tank and performing a check in the decompression tank is required.

An object of the present invention is to provide the above-described T.A. A. In order to avoid the problem caused by the phenomenon and improve the reliability of the magnetic disk drive, and to detect the possibility of contact of the MR element with the recording medium,
An object of the present invention is to efficiently detect a read error in combination with a high-temperature operation test (essential test) of a magnetic disk device.

[0014]

In order to solve the above problems, the present invention employs the following configuration. A magnetic disk drive comprising: a magnetic disk; a spindle motor for rotating the magnetic disk at a constant speed; and a magnetoresistive head using a magnetoresistive element as a read element for recording data on the magnetic disk. In the method for registering defects on a disk medium, the entire magnetic disk device is housed in a thermostat used for a temperature operation test, and the temperature of the thermostat is set to 50 to 50 which is higher than a normal operating temperature of the magnetic disk device.
A method for registering a defect on a magnetic disk medium in which the temperature is set in a range of 60 ° C. and a location on the magnetic disk medium where a read error occurs in the reading inspection of the magnetoresistive head is registered as a defective portion in advance.

Further, the magnetic disk includes a magnetic disk, a spindle motor for rotating the magnetic disk at a constant speed, and a magnetoresistive head using a magnetoresistive element as an element for reading recorded data from the magnetic disk. In a magnetic disk drive, a position on a magnetic disk medium where a read error occurs in reading of the magnetoresistive head under a condition of 50 to 60 ° C. higher than a normal operating temperature of the magnetic disk drive is previously determined as a defective portion Disk device registered as.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic disk drive and a method for registering defects on a magnetic disk medium according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration for searching and registering a defective portion on a magnetic disk medium according to an embodiment of the present invention. In FIG.
The magnetic disk drive 5 includes a magnetic disk medium 2 composed of one or more sheets and a carriage 3 capable of high-precision positioning.
And an MR head 1 fixed to the carriage 3 and a drive controller unit 4 for performing carriage positioning control, data recording / reproduction control, spindle rotation control, and the like.

After assembling the magnetic disk device 5, the magnetic disk device 5 is set in a thermostat 6 in order to search for and register a defective portion such as a protrusion existing on the magnetic disk medium 2. Here, the thermostat 6 is used for a temperature operation test which is an essential test item among various tests of the magnetic disk drive, and is not specially prepared for the defect registration method of the present invention. The magnetic disk device is required to have a high-temperature and low-temperature continuous operation test as an essential test item. Therefore, a thermostat is a necessary test facility.

The temperature of the thermostat 6 is higher than 25 ° C., which is the normal operating temperature of the magnetic disk device, and is in accordance with the specification of the magnetic disk device 5, for example, in the range of 50 to 60 ° C. Set within. Thereafter, the MR head 1 is scanned over all the cylinders of the magnetic disk medium 2 with the spindle rotated.

In this way, the defective portions on all the cylinders of the magnetic disk medium 2 are searched, and the corresponding cylinder number, sector number and the like are recorded at predetermined positions on the magnetic disk medium 2 as the position information of the detected defective portions. I do. The above series of operations is controlled by the drive controller 7. This operation may be controlled by the drive control unit 4 of the magnetic disk device 5.

FIG. 2 shows a magnetic disk drive equipped with an MR head. A. Generation part read (Read)
The waveform is the result of observation.
When observed at 5 ° C., the lower side shows a waveform when the same portion is observed at a high temperature of 55 ° C. T. A. It can be seen that the waveform change corresponding to is small at normal temperature, but remarkably changes at high temperature. For this reason, searching on a magnetic disk medium at a high temperature is better for T.V. A. Can be detected with high sensitivity.

FIG. 3 shows how the flying height of the magnetic head slider changes with temperature. At a high temperature, the mean free path of the molecules in the air becomes large, so that the viscosity decreases, and accordingly, the flying height of the magnetic head slider decreases. According to calculations, in the case of a magnetic head slider currently used with a flying height of about 20 nm, when the temperature changes from 25 ° C. to 55 ° C., the flying height decreases by 0.5 to 1.5 nm. Therefore, when the temperature is increased, the magnetic head slider and the defective portion of the magnetic disk medium are likely to come into contact with each other. A. The phenomenon becomes more pronounced. Further, according to a recent investigation example, it has been found that when the temperature is increased, a physical phenomenon occurs in which the MR element itself projects toward the recording medium. This phenomenon also increases the possibility that the MR element contacts the recording medium due to a rise in temperature.

T. A. Most of the problems were caused by initial defects of the magnetic disk medium such as protrusions, but recently, some organic matter in the device after the magnetic disk device was assembled, for example, solidified gas in the device. Alternatively, dust or the like from a jig or a tool at the time of assembly adheres to the magnetic disk medium, and the adhered matter comes into contact with the MR head to cause T.V. A. It may be. Observation of the deposit on the magnetic disk medium with an optical microscope revealed that the diameter was 1 to 3 μm and the height was 10 to 20 nm.
Of the nucleus and a length of 3 to 10 μm stretched from the nucleus
Often looks like a shape composed of tails. It is considered that the tail portion was generated because the core portion was dragged in contact with the magnetic head slider.

FIG. 4 shows an example of a case where the medium-attached portion is registered as a defect by changing the temperature. In the example shown on the left side of FIG. 4, it is shown that black circles have been detected and registered as defects in cylinders and sectors. Comparing the case of the normal temperature of 25 ° C. and the case of the high temperature of 55 ° C., it can be seen that the defect is registered more widely at the high temperature. The first reason may be that the flying height of the magnetic head slider is reduced at a high temperature, so that a defective portion can be detected with higher sensitivity. Secondly, it is conceivable that the medium deposit is composed of a soft organic substance, but its viscosity is lowered by high temperature, it is easily stretched by the magnetic head slider, and it spreads over time.

According to the present invention, T.I. A. A defect on a magnetic disk medium that causes the above can be detected with high sensitivity and in a wide range. The reliability of the magnetic disk device is improved by registering the detected defective portion and not reading / writing data at the registered portion. Here, regarding the registration of the defective portion on the magnetic disk medium, a well-known registration method may be adopted. That is, if a defect signal waveform is detected from the output from the MR head as shown in FIG. 2, it is registered in a management area on the magnetic disk medium in the form of a combination of a cylinder number, a sector number, and a head number. At the time of writing to a magnetic disk medium, writing is not performed to a defective portion registered in the management area.

Although the present invention mainly focuses on shipping inspection before shipping a magnetic disk device, it can be applied even after the magnetic disk device is mounted on a personal computer. As shown in FIG. 5, a personal computer 9 on which a magnetic disk drive 8 is mounted is placed in a thermostat 6 and a defect is registered while the temperature is set at 50 to 60 ° C. If the magnetic disk device 8 is operated for a long period of time, a late defect may occur on the magnetic disk medium for some reason. According to the present invention, a read error caused by a late defect can be efficiently prevented by detecting a late defect portion in advance with high sensitivity and in a wide range and registering the location.

As described above, in the magnetic disk drive according to the embodiment of the present invention, the flying height of the head is set by setting the temperature to a high temperature within the range of 50 to 60 ° C. using the constant temperature bath for the temperature operation test. As a result, the location where a read error occurs due to the occurrence of a thermal asperity (TA) phenomenon peculiar to the MR head at a location that did not occur at a normal operating temperature is registered in advance as a defective portion, and the defect registration is performed. That is, the data read / write of the part is not performed. here,
The test according to the defect registration method of the present embodiment is performed before the temperature operation test (there is no problem even if it is performed later), but the thermostat is also used. Then, by lowering the flying height of the head, searching for a defective portion on the magnetic disk medium with high sensitivity, and registering the position, the T.C. A. Thus, a read error caused by the above can be prevented beforehand, and the reliability of the magnetic disk device can be improved.

[0027]

According to the present invention, by setting the high-temperature state within the range of 50 to 60 ° C., the flying height of the head is reduced, so that the MR at a portion which does not occur at the normal operating temperature is obtained.
When a thermal asperity (TA) phenomenon peculiar to the head occurs, a place where a read error occurs is highly sensitive,
Detection can be performed over a wide range, and by registering this portion as a defective portion, the reliability of the magnetic disk device can be improved.

Further, the constant temperature bath set to the high temperature state includes:
Since it is used in the essential temperature operation test of the magnetic disk drive, the defect registration method of the present invention can be used in combination with the defect registration method, thus enabling efficient defect detection.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration for searching and registering a defective portion on a magnetic disk medium according to an embodiment of the present invention.

FIG. 2 is a graph showing T.C. at normal temperature of 25.degree. C. and high temperature of 55.degree. A. FIG. 6 is a diagram showing a comparison of waveforms of parts.

FIG. 3 is a diagram illustrating a relationship between a temperature and a head flying height according to the embodiment;

FIG. 4 is a diagram showing a comparison of defect registration areas at a normal temperature of 25 ° C. and a high temperature of 55 ° C.

FIG. 5 is a PC of the magnetic disk device according to the embodiment;
FIG. 9 is a diagram showing a method of searching for and registering a defective part after mounting on a (personal computer).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 MR head 2 Magnetic disk medium 3 Carriage 4 Drive control part 6 Constant temperature chamber for temperature operation test 7 Drive controller 8 Magnetic disk device 9 Personal computer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) G11B 20/18 572 G11B 20/18 572D 572F (72) Inventor Kiyoshi Makino 2880 Kofu, Odawara City, Kanagawa Pref. Hitachi, Ltd. Storage Systems Division (72) Inventor Hiroshi Shimamoto 2880 Kozu, Odawara-shi, Kanagawa Prefecture F-term in Hitachi Storage Systems Division 5D044 BC01 CC04 DE64 EF05 5D091 AA10 FF02 HH20 5D112 JJ05

Claims (4)

[Claims] A magnetic disk; a spindle motor for rotating the magnetic disk at a constant speed; and a magnetoresistive head using a magnetoresistive element as an element for reading recorded data from the magnetic disk. In the method for registering defects on a magnetic disk medium of a magnetic disk device, the entire magnetic disk device is housed in a thermostat used for a temperature operation test, and the temperature of the thermostat is higher than a normal operating temperature of the magnetic disk device by 50 to 50 ° C. A method for registering a defect on a magnetic disk medium, wherein the temperature is set within a range of 60 ° C., and a location on the magnetic disk medium where a read error occurs by reading inspection of the magnetoresistive head is registered in advance as a defective portion. 2. The method for registering defects on a magnetic disk medium according to claim 1, wherein, prior to a temperature operation test of a magnetic disk device using the constant temperature bath, the temperature of the constant temperature bath is set in the range of 50 to 60 ° C. A method for registering a defect on a magnetic disk medium, wherein the method performs the above-mentioned read inspection after setting. 3. The method for registering defects on a magnetic disk medium according to claim 1, wherein the entire personal computer on which the magnetic disk device is mounted is housed in a thermostat instead of the entire magnetic disk device. Defect registration method on magnetic disk media. 4. A magnetic disk, a spindle motor for rotating the magnetic disk at a constant speed, and a magnetoresistive head using a magnetoresistive element for reading data recorded on the magnetic disk. In the magnetic disk drive, 50 to 60 which is higher than the normal operating temperature of the magnetic disk drive
A magnetic disk device wherein a position on a magnetic disk medium where a read error occurs in reading of the magnetoresistive head under a condition of a temperature range of ° C. is registered in advance as a defective portion.