JP2000182201A - Magnetic recording medium evaluation equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically measure the output variation of an signal with the lapse of time by making a magnetic head seek different tracks for calibrating it with a head sensitivity calibration signal after the preset waiting time lapses, measuring an off-track profile by letting the head seek the original track, etc. SOLUTION: When an algorithm for this automatic measurement of heat demagnetization is started, this equipment firstly DC-erases the neighborhood of the track to be used for the measurement, and records a set signal A. Next, the equipment waits for a pre-set time before measuring the signal, and makes a magnetic head seek another track, and records and reproduces a signal B for calibrating the head sensitivity, to calibrate the head sensitivity. Following this, the equipment makes the magnetic head seek the track where the signal A is recorded, and measures an off-track profile of the signal A, and records the peak value and the signal A before storing the elapsed time, and the measurement is carried out by repeating these operations at arbitrary tome intervals. All of this series of the operations are carried out automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium of a magnetic storage device used as an auxiliary storage device of a computer, and more particularly, to an evaluation of a magnetic recording medium suitable for realizing a high recording density.

[0002]

2. Description of the Related Art In recent years, the amount of information handled by computers has increased, and the capacity of auxiliary storage devices has been further required.
To cope with this, for example, in a magnetic disk device, the bit density per unit area is increased. When the recording density of the magnetic disk device is increased, the medium area per recording bit is reduced, so that the output is reduced and reproduction becomes difficult. In order to solve such a problem, the reproducing sensitivity of the magnetic head is enhanced by utilizing the magnetoresistive effect or the giant magnetoresistive effect as the reproducing magnetic head. But,
A head using these effects reproduces noise with high sensitivity at the same time as the reproduction output, so it is necessary to further reduce the medium noise. Effective techniques for reducing medium noise include miniaturization of magnetic crystal grains and reduction of intergranular interaction, but at the same time, the recording magnetization becomes thermally unstable.

As a method of measuring the influence of thermal fluctuation of a magnetic recording medium, for example, as described in Japanese Patent Application Laid-Open No. 8-77543, a change in static magnetic characteristics of a medium is measured using a vibrating sample magnetometer (VSM). And a computer simulation method. However, what actually becomes a problem is a change in output when a signal recorded on a magnetic recording medium is reproduced using a magnetic head, which is insufficient for an examination at an experimental level.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a magnetic recording medium evaluation apparatus capable of accurately evaluating the influence of thermal fluctuation using a magnetic head and a magnetic recording medium. It is to be.

[0005]

A drive unit for rotating at least one magnetic recording medium and a drive unit for moving a magnetic head for recording / reproducing on / at least one magnetic recording medium relative to the magnetic recording medium. Recording and reproduction processing means for performing waveform processing on an input signal and a reproduction signal to the magnetic head, and a control circuit system for processing control signals for the magnetic recording medium drive unit, the magnetic head drive unit, and operation control signals for the entire apparatus. In the magnetic recording medium evaluation device having, (1) record the signal A on the magnetic recording medium, (2) after a predetermined waiting time has elapsed, (3) seek the magnetic head to a different track (4) head sensitivity After recording the calibration signal B and calibrating the head sensitivity using the signal B, (5) seek the magnetic head to the track where the signal A was recorded, (6) measure the off-track profile, 7) Off Determine the peak value of the track profile as the reproduction output of the signal A, from (2)
The operation of (7) is repeated at an arbitrary time interval, and has a function of automatically measuring an output change amount of the signal A recorded on the magnetic recording medium with time. After calibrating the head sensitivity, the recording head is not used while the output of the signal A is being measured. This is to prevent the leakage magnetic field from affecting the reproducing head by using the recording head and changing the head sensitivity. In addition, the measurement of the off-track profile is sufficient if the range of about -4 μm to +4 μm is measured around the radius at which the signal A is recorded, and the step width may be 0.2 μm or less, but the step width is reduced. The more the measurement accuracy is improved. It is also desirable to interrupt the measurement when a peak is detected during the measurement of the off-track profile, because the measurement time can be reduced. further,
For the results obtained with the off-track profile
It is desirable to perform the fitting using the Gauss distribution function and use the resulting peak value as the output of the signal A because the measurement accuracy can be improved.

Alternatively, the off-track profile near the center of the recording track can be measured without seeking the magnetic head by utilizing the fact that the position of the magnetic head and the recording track deviate due to thermal expansion as a method of measuring the output of the recorded signal A. However, when the peak value of the off-track profile is used as the output of the signal A, the measurement accuracy is dramatically improved. It is considered that this thermal expansion is caused by a temperature change in the measurement environment, such as heat generated by a spindle motor, rotation of a magnetic recording medium, seek of a magnetic head, and heat generated by a circuit system. Under the influence, the output is continuously measured while the position of the recording track and the position of the reproducing head are shifted, and the maximum point of the off-track profile obtained therefrom is the maximum value of the signal A. Although it depends on the operating environment, the deviation is about 1 nm / sec, and the positioning resolution is much higher than when the off-track profile is measured by seeking the magnetic head. In addition, thermal expansion may be induced at the time of measurement. If the rotation speed of the spin stand is temporarily changed and the rotation speed is returned to the original value at the time of measurement, the influence of thermal expansion is suddenly exerted, so that the measurement can be performed in a short time.

A drive unit for rotating at least one magnetic recording medium, a drive unit for moving a magnetic head for recording / reproducing on / at least one magnetic recording medium relative to the magnetic recording medium, and a driving unit for the magnetic head. Recording and reproduction processing means for performing waveform processing on an input signal and a reproduction signal, a control circuit system for processing a control signal of the magnetic recording medium driving unit and the magnetic head driving unit, and an operation control signal of the entire apparatus, a temperature adjusting device, In a magnetic recording medium evaluation device having a protective cover that covers the entire measurement system, (1) the signal A is recorded on the magnetic recording medium, (2) after a predetermined waiting time has elapsed, (3) the magnetic head is moved to a different track. After seeking, (4) a signal B for head sensitivity calibration is recorded, and the head sensitivity is calibrated using the signal B. (5) The magnetic head is sought to the track on which the signal A is recorded, and (6) off. Truck Measuring profile (7)
Find the position where the output peaks, (8) seek the head to a position slightly shifted from it, (9) change the temperature inside the protective cover with a temperature controller to induce thermal expansion of the measurement system, 10) Continue to reproduce the output of the signal A, (11) set the measured output peak value as the reproduction output of the signal A, repeat the operations of (2) to (11) at an arbitrary time, and elapse the time of the signal A. Has a function of automatically measuring the output change amount accompanying the Use a temperature controller to keep the inside of the protective cover at a constant temperature, change the temperature at the start of measurement, raise the temperature, move the head outside the center of the signal A, and when lowering the temperature, the inner side of the center of the signal A. It is preferable to measure the output from a position shifted by 0.2 μm. Since the thermal expansion can be controlled, the measurement time can be greatly reduced. Further, the temperature control function can be applied to various measurements such as an acceleration test and a test at a real machine level.

Further, as a method of confirming the measurement accuracy of the present invention, a function of measuring the output envelope of the recorded signal A and interrupting the measurement depending on the shape is provided. When performing such an evaluation, since one signal is measured for a long time, it is not known what factors will be added in the middle. In particular, if the center of the magnetic recording medium shifts during the measurement, the output will be greatly reduced as a result. As a judgment, it is preferable to compare the shape of the output envelope immediately after recording with the shape of the output envelope at the end of measurement. If the center of the magnetic recording medium is shifted in the middle, if the shape of the output envelope immediately after recording is subtracted from the output envelope at the end of the measurement, the shape of the sine waveform will remain. Although it is possible to estimate the amount of center deviation using this and the off-track profile of the output, it is not preferable to pursue absolute accuracy.

Preferably, the output is measured using a digital multimeter, digital oscilloscope, spectrum analyzer, or the like.

By using the magnetic recording medium evaluation apparatus of the present invention as described above, it is possible to evaluate a change in output due to the influence of thermal fluctuation using a magnetic head and a magnetic recording medium.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows a schematic diagram of a magnetic recording medium evaluation apparatus according to an embodiment of the present invention.
This device is a magnetic recording medium evaluation device having a well-known configuration including an evaluation unit 11 and an operation unit 12. As shown in FIG. 2, the evaluation unit 11 includes a spindle motor 21 that rotationally drives the magnetic recording medium, a head carriage 22 that moves the magnetic head relative to the magnetic recording medium, and a magnetic head 23.
A control circuit system 24 processes a recording signal to be read from the head and a reproduction signal from the head, and also processes a control signal for operation of the entire apparatus. The control circuit system 24 includes a spindle motor 21, a head carriage 22, a magnetic head 23, and an operation unit. Connected to 12.

The above-described apparatus can measure the read / write characteristics of the magnetic recording medium in the same manner as the conventional evaluation apparatus, but differs from the conventional apparatus in that the operation section 12 includes an automatic thermal demagnetization measurement item. Is a point.

FIG. 3 shows an algorithm for automatic measurement of thermal demagnetization. When this algorithm is started, (1) DC erase is performed around the track used for measurement, and (2) the set signal A is recorded. (3) Wait for a preset time before measuring the signal A, (4) Seek the magnetic head to another track
(5) Recording / reproducing the signal B for head sensitivity calibration, and after calibrating the head sensitivity by this, (6) seek the magnetic head to the track where the signal A was recorded, and (7) set the off-track profile of the signal A. The measurement and (8) the time elapsed since the peak value and the signal A were recorded are stored, and the operation of (3) to (8) is repeated at an arbitrary time to perform the measurement. This series of operations are all performed automatically. It is sufficient to use an existing evaluation device, and this evaluation device is configured by adding a thermal demagnetization automatic measurement algorithm. Further, the seek step resolution in the radial direction of the head carriage 22 is desirably 0.1 μm or less. To achieve an areal recording density of 10 gigabits per square inch or more, the recording track width must be set to 1 micron or less.To measure the profile of recorded signal A, at most 1/10 of the recording track width Some degree of seek step resolution is required.

In the magnetic recording medium evaluation apparatus having the structure shown in the above embodiment, the magnetostatic characteristics of the magnetic recording medium using the Co-based sputtered magnetic film are as follows: a coercive force of 2.2 kOe, a residual magnetic flux density and a magnetic film thickness product of 70 Gμm. , The coercive force orientation ratio is 0.6, and
The rotation speed of the spindle motor 21 is 4000 rpm, the magnetic head 23 uses a self-induction type head for the recording unit and a magnetoresistive head for the reproducing unit, and has a recording track width of 0.9 μm, a reproducing track width of 0.7 μm, and a recording gap length. Using a spectrum analyzer to measure the output, 0.4 μm and a reproduction gap length of 0.2 μm, and a similar thermal demagnetization with a seek step of 0.1 μm for off-track profile measurement for 185 kFCI signal by automatic measurement and manual measurement FIG. 4 shows the time dependence of the output decay measured for the characteristics. Solid line a
Indicates the result of automatic measurement, and broken line b indicates the result of manual measurement. As shown in the figure, substantially the same value was obtained in both the output change amount and the time dependency. From this, it was found that the magnetic recording medium evaluation apparatus configured in this example can automatically measure the thermal demagnetization characteristics using the magnetic head and the magnetic recording medium.

In this embodiment, the seek step at the time of measuring the off-track profile is set to 0.1 μm.
μm or less may be sufficient, and more preferably 0.02 μm or less because measurement accuracy is improved. Further, it is preferable to stop the measurement at the time when the peak value is obtained during the measurement of the off-track profile, because the measurement time can be shortened. Although the automatic demagnetization measurement algorithm is included in the operation unit 12, the algorithm may be incorporated in the control circuit system 24.

Embodiment 2 In this embodiment, an output measuring unit 31 shown in FIG. 5 is used as an output measuring unit 31 in a magnetic recording medium evaluation apparatus having a configuration similar to that of the first embodiment. As shown in the figure, this algorithm measures the off-track profile of signal A, and then
The fitting is performed using the Gauss distribution function, and the time elapsed since the peak value and the signal A were recorded is stored. This series of operations are all performed automatically. It is sufficient to use an existing evaluation device, and this evaluation device is configured by adding a thermal demagnetization automatic measurement algorithm.

In the first embodiment, the result of the measurement of the off-track profile is output as it is. This embodiment differs from the first embodiment in that the result of the off-track profile is fitted using a function and its peak value is used. Is a point.

In the magnetic recording medium evaluation apparatus having the configuration shown in the above embodiment, the magnetostatic characteristics of the magnetic recording medium using the Co-based sputtered magnetic film are as follows: the coercive force is 1.24 kOe;
The magnetic film thickness product is 32 Gμm, the coercive force orientation ratio is 0.4, the rotation speed of the spindle motor 21 is 4000 rpm, and the magnetic head 23 uses a self-induction type head for the recording unit and a magnetoresistive head for the reproducing unit. , The recording track width is 0.9 microns, the reproduction track width is 0.7 microns, and the recording gap length is
Using a digital oscilloscope to measure the output and measuring the same thermal demagnetization characteristics of a 50 kFCI signal by automatic measurement and manual measurement with 0.4 μm and the reproduction gap length of 0.2 μm, the time dependence of the output decay is shown in Fig. 6. Show. The solid line c shows the result of automatic measurement, and the broken line d shows the result of manual measurement. As shown in the figure, substantially the same value was obtained in both the output change amount and the time dependency. From this, it was found that the magnetic recording medium evaluation apparatus configured in this example can automatically measure the thermal demagnetization characteristics using the magnetic head and the magnetic recording medium.

In the present embodiment, the automatic demagnetization measurement algorithm is included in the operation unit 12, but this algorithm may be incorporated in the control circuit system 24.

Embodiment 3 In this embodiment, an output measuring unit 71 shown in FIG. 7 is used as the output measuring unit 31 in a magnetic recording medium evaluation apparatus having the same configuration as that of the first embodiment. As shown in the figure, this algorithm first measures the off-track profile and confirms the peak position of the output. Next, the head is sought to the position where the output is about 50%, and the output is continuously measured for 30 seconds. When the center of the signal A is directed toward the inner circumference, the head is sought to the inner circumference 0.2 μm of the peak obtained from the off-track profile, and when the signal A is directed toward the outer circumference, the seek is performed to the outer circumference 0.2 μm. Continue to measure the output while keeping the magnetic head radial position fixed, measure the off-track profile from increasing to decreasing the output, and save the peak value obtained and the time elapsed since the signal A was recorded Things. This series of operations are all performed automatically.
This evaluation device is an existing one. Is sufficient, and is configured by adding a thermal demagnetization automatic measurement algorithm.

In the first embodiment, the off-track profile is measured by seeking the magnetic head. In this embodiment, the off-track profile is measured without seeking the magnetic head using thermal expansion. The difference is that the output change can be measured without being affected by the seek step resolution.

In the magnetic recording medium evaluation apparatus having the structure shown in the above embodiment, the magnetostatic characteristics of the magnetic recording medium using the Co-based sputtered magnetic film are as follows: a coercive force of 2.5 kOe, a residual magnetic flux density and a magnetic film thickness product of 70 Gμm. , The coercive force orientation ratio is 0.7, and
The rotation speed of the spindle motor 21 is 4000 rpm, the magnetic head 23 uses a self-induction type head for the recording unit and a magnetoresistive head for the reproducing unit, and has a recording track width of 0.9 μm, a reproducing track width of 0.7 μm, and a recording gap length. Using a spectrum analyzer to measure the output and measuring the same thermal demagnetization characteristics of a 185 kFCI signal by automatic measurement and manual measurement with the reproduction gap length set to 0.4 μm and the reproduction gap length set to 0.2 μm, the time dependence of the output decay is shown in Fig. 8. Shown in The solid line e shows the result of automatic measurement, and the broken line f shows the result of manual measurement. As shown in the figure, substantially the same value was obtained in both the output change amount and the time dependency. From this, it was found that the magnetic recording medium evaluation apparatus configured in the present example can automatically measure the thermal demagnetization characteristics using the magnetic head and the magnetic recording medium even when utilizing thermal expansion. Was.

In this embodiment, the measurement is performed with the rotation speed of the spindle motor fixed. However, if the rotation speed is changed until immediately before the output measurement, thermal expansion occurs rapidly, so that the measurement time can be reduced, which is desirable. . Although the automatic demagnetization measurement algorithm is included in the operation unit 12, the algorithm may be incorporated in the control circuit system 24.

Embodiment 4 FIG. 9 is a schematic view of a magnetic recording medium evaluation apparatus according to an embodiment of the present invention. This device is a magnetic recording medium evaluation device having a well-known configuration including an evaluation unit 91 and an operation unit 12. The evaluation unit 91 includes a protective cover 92 that shuts off the entire upper part of the device from the outside air, and a protective cover 92. A temperature control device 93 for controlling the temperature of the inside to a constant value is added.
In this embodiment, the output measuring unit 31 shown in FIG. 10 is used as the output measuring unit 31 shown in the first embodiment. As shown in the figure, this algorithm first measures the off-track profile,
Check the radius position where the output peaks. Next, the magnetic head is sought to the inner side 0.2 μm of the output peak position, and the temperature inside the protective cover is lowered by the temperature controller.
In this state, keep measuring the output while keeping the magnetic head radial position fixed until the maximum value when the output changes from increasing to decreasing is obtained, and the time after recording the obtained peak value and signal A is What you save. This series of operations are all performed automatically. It suffices to use an existing evaluation device, which consists of adding a protective cover, a temperature controller, and an automatic thermal demagnetization measurement algorithm.

The above-described apparatus is different from the fourth embodiment in that the temperature inside the protective cover 112 is adjusted and thermal expansion is induced to perform automatic measurement of thermal demagnetization.

The inside of the protective cover was set in an atmosphere of 25 ° C. using the magnetic recording medium evaluation apparatus having the structure shown in the above embodiment, and the same thermal demagnetization characteristics were obtained by the automatic measurement and the manual measurement under the same conditions as in the fourth embodiment. FIG. 11 shows the time dependence of the measured output attenuation. solid line
g is the measurement result by the automatic measurement, and the wavy line h is the result by the manual measurement. The solid line e in Example 4 is shown for reference. As shown in the figure, substantially the same value was obtained in both the absolute value and the elapsed time dependency of the output change amount. However, it can be seen that the measurement time of the broken line g, which should have been measured under the same conditions, is slightly slower than the result of this example. This is because it took time until the first measurement of the first point. From this, the magnetic recording medium evaluation apparatus configured in the present embodiment can evaluate the magnetic recording medium in a shorter time than when utilizing the thermal expansion that occurs naturally by adjusting the temperature of the thermal demagnetization characteristic of the magnetic recording medium. I understood.

In this embodiment, at the start of the output measurement, the head is sought to 0.2 μm on the inner side of the output peak position.
μm or less is sufficient, and the measurement time can be shortened as close to the peak position as possible, which is preferable. Also, when measuring the output, the temperature inside the protective cover was reduced,
The temperature may be raised by seeking the head to the outer peripheral side of the output peak. Further, in this embodiment, the temperature inside the protective cover is set to 25 ° C., but it is also possible to set the temperature to a higher temperature to perform an acceleration test, or to set the temperature to the level of an actual machine. Although the automatic demagnetization measurement algorithm is included in the operation unit 12, the algorithm may be incorporated in the control circuit system 24.

Embodiment 5 In this embodiment, an algorithm for automatic measurement of thermal demagnetization shown in FIG. 12 was used in a magnetic recording medium evaluation apparatus having the same configuration as in Embodiment 1. When this algorithm is started, (1) DC erase is performed around the track used for measurement, and (2) the set signal A is recorded. (3) Wait for a preset time before measuring the signal A, (4)
The magnetic head is sought to another track (5) The signal B for head sensitivity calibration is recorded and reproduced, and the head sensitivity is calibrated using this. Then, (6) seek the magnetic head to the track where the signal A was recorded, (7) measure the off-track profile of the signal A, (8) save the peak value and the time since the signal A was recorded, The operation from (3) to (8) is repeated at an arbitrary time and measurement is performed. After that, the output envelope of the signal A is measured, the output envelope of the signal A newly recorded there is measured, the shapes are compared, and the measurement accuracy of the result of measuring the thermal demagnetization based on the shape is determined. This series of operations are all performed automatically. It is sufficient to use an existing evaluation device, and this evaluation device is configured by adding a thermal demagnetization automatic measurement algorithm.

In the first embodiment, no judgment was made with respect to the accuracy of the measurement result. However, in this embodiment, the center of the magnetic recording medium was not displaced during the measurement by using the shape of the output envelope. The difference is that it can be determined.

In the magnetic recording medium evaluation apparatus having the configuration shown in the above embodiment, the magnetostatic characteristics of the magnetic recording medium using the Co-based sputtered magnetic film are as follows: the coercive force is 0.77 kOe;
The magnetic film thickness product is 33.5 Gμm, the coercive force orientation ratio is 0.76, the rotation speed of the spindle motor 21 is 4000 rpm, and the magnetic head 23 has a self-induction type head in the recording unit and a magnetoresistive head in the reproducing unit. The recording track width is 0.9 microns, the reproduction track width is 0.7 microns, and the recording gap length is
0.4 μm, read gap length 0.2 μm, using a spectrum analyzer to measure the output, 50kF for normal measurement and when the center of the medium is shifted during measurement
Figure 13 (a) shows the time dependence of the output decay measured for the same thermal demagnetization characteristics for the CI signal, and Fig. 13 (b) shows the output envelope shape for one round of the magnetic recording medium immediately after recording and after the measurement was completed. Show. The solid line i shows the result in the normal case, and the broken line j shows the result in the case where the center of the magnetic recording medium is shifted. As shown in FIG. 9A, when the center of the medium is shifted, the output change amount is large. Same figure
Looking at the shape of the output envelope as shown in (b), the normal measurement has almost the same shape as immediately after recording, but the shape of the output envelope seems to be significantly different when the center of the medium is shifted. From this, the magnetic recording medium evaluation device configured in the present embodiment can automatically measure the thermal demagnetization characteristics using the magnetic head and the magnetic recording medium, and can further confirm the measurement accuracy. I knew there was.

In the present embodiment, at the end of the measurement, the shape of the output transition for a certain period of time is measured, and a new signal A is recorded and compared there. At the start of the measurement, the output envelope immediately after the recording is measured. After measuring the time, the output envelopes are measured and compared, and if the shapes are significantly different, the measurement may be interrupted. Also, the automatic demagnetization measurement algorithm is included in the operation unit 12, but this algorithm is used in the control circuit system 24.
It may be incorporated in

[0032]

According to the present invention, it is possible to measure thermal demagnetization characteristics using a magnetic head and a magnetic recording medium, and it is possible to accurately evaluate even a high recording density region.

[Brief description of the drawings]

FIG. 1 is a schematic view of a magnetic recording medium evaluation apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an evaluation unit according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating an algorithm for automatic measurement of thermal demagnetization according to an embodiment of the present invention.

FIG. 4 is a diagram showing thermal demagnetization characteristics measured by a magnetic recording medium evaluation apparatus according to one embodiment of the present invention.

FIG. 5 is a diagram illustrating an algorithm of an output measuring unit according to an embodiment of the present invention.

FIG. 6 is a diagram showing thermal demagnetization characteristics measured by a magnetic recording medium evaluation apparatus according to one embodiment of the present invention.

FIG. 7 is a diagram illustrating an algorithm of an output measuring unit according to an embodiment of the present invention.

FIG. 8 is a diagram showing thermal demagnetization characteristics measured by a magnetic recording medium evaluation apparatus according to one embodiment of the present invention.

FIG. 9 is a schematic view of an apparatus according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating an algorithm of an output measuring unit according to an embodiment of the present invention.

FIG. 11 is a diagram showing thermal demagnetization characteristics measured by a magnetic recording medium evaluation apparatus according to one embodiment of the present invention.

FIG. 12 is a diagram illustrating an algorithm for automatic measurement of thermal demagnetization according to an embodiment of the present invention.

FIG. 13 is a diagram showing thermal demagnetization characteristics measured by a magnetic recording medium evaluation apparatus according to one embodiment of the present invention.

[Explanation of symbols]

11 ... Evaluation unit, 12 ... Operation unit, 21 ... Drive unit, 22 ... Head carriage, 23 ... Magnetic head, 24 ... Control circuit system, 31 ... Output measurement unit, 51 ... Output measurement unit, 71 ... Output measurement unit, 91 … Evaluation department,
92: protective cover, 93: temperature controller, 101: output measuring unit.

Continuing on the front page (72) Inventor Kaoru Tanahashi 1-280 Higashi Koikekubo, Kokubunji City, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Tetsuya Kanbe 1-280 Higashi Koikekubo, Kokubunji City, Tokyo Research Center for Hitachi, Ltd. (72) Inventor Satoru Matsunuma 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd.Central Research Laboratory (72) Inventor Akira Ishikawa 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo F-term in the Central Research Laboratory, Hitachi, Ltd. Reference) 5D091 AA10 CC01 FF02 GG01 5D112 AA24 GB03 JJ02 JJ06 JJ07 JJ09

Claims (5)

[Claims] A driving unit for rotating at least one magnetic recording medium; a driving unit for moving a magnetic head for recording / reproducing on / at least one magnetic recording medium relative to the magnetic recording medium; Recording / reproducing processing means for performing waveform processing on an input signal and a reproduced signal to a magnetic recording medium, and a control circuit system for processing a control signal of the magnetic recording medium driving section, a control signal of the magnetic head driving section, and an operation control signal of the entire apparatus. In the evaluation device, (1) record the signal A on the magnetic recording medium, (2) after a predetermined waiting time has elapsed, (3) seek the magnetic head to a different track, (4) the signal for head sensitivity calibration After recording B and calibrating the head sensitivity using the signal B, (5) seek the magnetic head again to the track on which the signal A was recorded, (6) measure the off-track profile, and (7) measure the off-track profile. Off-track prof Determine the peak value of the file as the reproduction output of the signal A, repeat the operations (2) to (7) every arbitrary time, and have a function of automatically measuring the output change amount of the signal A with the passage of time. An apparatus for evaluating a magnetic recording medium, comprising: 2. The magnetic recording medium evaluation apparatus according to claim 1, wherein the output of the recorded signal A is measured by Gaussian.
An apparatus for evaluating a magnetic recording medium, comprising: fitting an output of an off-track profile obtained by using a distribution function, and using a peak value of the fitted result as an output of the signal A. 3. The magnetic recording medium evaluation apparatus according to claim 1, wherein the magnetic head is sought by utilizing the fact that the position of the magnetic head and the recording track are shifted by thermal expansion as a method of measuring the output of the recorded signal A. A magnetic recording medium evaluation apparatus, comprising: measuring an off-track profile near the center of a recording track, and using a peak value of the off-track profile as an output of the signal A. 4. A drive unit for rotating at least one magnetic recording medium, a drive unit for moving a magnetic head for recording / reproducing on / at least one magnetic recording medium relative to the magnetic recording medium, and a magnetic head. Recording / reproducing processing means for performing waveform processing on an input signal and a reproduced signal to the magnetic disk drive, a control circuit system for processing a control signal of the magnetic recording medium driving unit and the magnetic head driving unit, and an operation control signal of the entire apparatus, and a temperature control device And, in the magnetic recording medium evaluation device having a protective cover covering the entire measurement system, (1) record the signal A on the magnetic recording medium, (2) after a predetermined waiting time has elapsed (3) different magnetic head After seeking to the track, (4) recording a signal B for head sensitivity calibration, and calibrating the head sensitivity using the signal B, (5) seeking the magnetic head again to the track on which the signal A was recorded, 6) of the signal A Seek the magnetic head to a position slightly shifted from the force peak, (7) change the temperature inside the protective cover with a temperature controller to control the thermal expansion of the measurement system, (8) measure the output, and (2) A magnetic recording medium evaluation apparatus having a function of repeating the operations of (1) to (8) at an arbitrary time interval and automatically measuring an output change amount of the signal A over time. 5. The magnetic recording medium evaluation apparatus according to claim 1, further comprising a function of measuring an output envelope of the signal A, and determining whether the center of the magnetic recording medium is displaced by the shape of the output envelope. A magnetic recording medium evaluation device characterized by the above-mentioned.