JPH0817090A - Position adjusting method of magnetic head - Google Patents

Abstract

PURPOSE:To remarkably improve the yield and reliability of products by very easily and surely adjusting the position of a magnetic head against an optical spot. CONSTITUTION:A magneto-optical disk for adjustment provided with the magnetic layer having two layers structure is used, and a head element 12 is moved in the radial direction of disk on this magneto-optical disk by a head moving means 7 to detect the position of the head element 12, where the amplitude of an RF output becomes maximum. Subsequently, the head element 12 is moved on the line in the tangential direction of disk passing the position where the amplitude of the radial direction of disk becomes maximum, to similarly detect the position of head element 12, where the amplitude of the RF output becomes maximum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head position adjusting method for determining an optimum position for a light spot of a magnetic head in a magneto-optical disk device.

[0002]

2. Description of the Related Art In a conventional magneto-optical disk which is a magneto-optical recording medium, when new data is recorded, it is necessary to go through three processes of erasing old data, recording and verifying. Therefore, the magneto-optical disk must be rotated at least three times when recording data, and it is difficult to increase the transfer rate during recording.

As one of the methods for improving this problem,
A system using so-called magnetic field modulation overwrite technology is currently in the stage of practical application. This technique does not require an erasing process at the time of recording and is a technique capable of increasing the transfer rate by about 1.5 times as compared with the conventional magneto-optical disk. In this case, it is indispensable to modulate the recording magnetic field at a high speed, but in a fixed magnetic head in which the distance between the recording medium and the magnetic head is large, it is necessary to simultaneously satisfy the sufficient recording magnetic field and the high speed modulation. It is also very difficult from the perspective of.

Therefore, it becomes necessary to use a so-called floating magnetic head that is generally used in hard disks. In order to avoid wear and damage due to contact with the surface of the recording medium, this flying type magnetic head causes a head element to be spaced a minute distance from the surface of the recording medium (so-called flying height) by an air flow generated on the surface of the recording medium when the recording medium rotates at high speed. Is a magnetic head configured to generate a magnetic field while levitating and traveling, and has a structure in which a coil is wound by providing an extremely small head element on a part of a wing-shaped member called a slider. ing.

By the way, in magneto-optical recording, recording is performed by applying a recording magnetic field from a magnetic head to a portion heated to a high temperature by irradiating the magneto-optical disk with laser light. The position and the magnetic field generation area must match. However, since the flying height of the flying magnetic head is on the order of several microns to submicron, the magnetic field generation region is very narrow, and it is difficult to perform alignment with only mechanical accuracy.

For this reason, mainly in the present situation, the floating magnetic head is moved little by little with respect to the magneto-optical disk for recording, and the signal is read to obtain the signal amplitude and signal quality (for example, C / N, etc.). The position of the head element of the floating magnetic head with respect to the light spot is adjusted by sequentially performing the confirmation of (1).

[0007]

However, the above-mentioned position adjusting method is very complicated and takes a lot of time and labor, which is a big problem in production. Of course, a method of visually adjusting the position of the head element is often used, but this method has a problem in that accuracy is remarkably lacking.

The present invention has been proposed in view of the above-mentioned problems, and the position adjustment of the magnetic head with respect to the light spot is performed even for a magnetic head having a very narrow magnetic field generation region such as a head element of a floating magnetic head. It is an object of the present invention to provide a magnetic head position adjusting method that can be performed very easily and reliably and that can significantly improve the yield and reliability of products.

[0009]

The object of the present invention is a method for adjusting the position of a magnetic head with respect to a light spot in a magneto-optical recording / reproducing apparatus. In the present invention, as a magneto-optical recording medium for position adjustment inspection, first and second magnetic layers having magnetic layers having two or more perpendicular magnetic anisotropies having different Curie temperatures and exchange-coupled to each other. And a detection temperature that is substantially equal to the Curie temperature of the first magnetic layer and sufficiently lower than the Curie temperature of the second magnetic layer, the effective coupling effect of the first and second magnetic layers is achieved. A coercive force that is smaller than the recording magnetic field, whose magnetization direction can change according to this recording magnetic field, and which exhibits a detectable Kerr rotation angle is used.

Here, when the magnetic layer is only the first magnetic layer, the Curie temperature and the detected temperature are substantially equal to each other, so that the change of the coercive force with respect to the temperature is sharp and the magnetic characteristics are slightly changed. However, the temperature at which the coercive force in the first magnetic layer becomes smaller than the recording magnetic field is hard to change, but
Since the reversal of magnetization occurs near the Curie temperature, there is a problem that a sufficient Kerr rotation angle cannot be obtained.

On the other hand, when the magnetic layer is only the second magnetic layer, the change in the magnetization direction occurs at a temperature sufficiently lower than the Curie temperature, so that a sufficient Kerr rotation angle can be obtained and the perpendicular magnetization anisotropy can be obtained. Although large and good recording characteristics can be obtained,
Since the Curie temperature is sufficiently higher than the detection temperature, the change in coercive force with respect to temperature is gradual, and even if a slight change in magnetic characteristics occurs, the temperature at which the coercive force in the first magnetic layer becomes smaller than the recording magnetic field changes. There is a problem that it is easy.

Therefore, the present invention has a structure in which two layers are exchange-coupled by forming the magnetic layer into a two-layer structure in which the first and second magnetic layers are laminated as described above. Therefore, when the temperature rises by irradiating the magneto-optical recording medium with a laser, the coercive force of the first magnetic layer is increased up to around the Curie temperature of the first magnetic layer in the effective coercive force due to exchange coupling. Is dominant, the change in coercive force with respect to temperature is steep, and even if there is some variation in magnetic characteristics, this first
The temperature at which the coercive force in the magnetic layer becomes smaller than the recording magnetic field is hard to change. Further, since the change of the magnetization direction occurs at a temperature sufficiently lower than the Curie temperature of the second magnetic layer, a sufficient Kerr rotation angle can be obtained at the detection temperature. Further, the first magnetic layer has a large perpendicular magnetization anisotropy and good recording characteristics are obtained, and the exchange coupling double layer having the first magnetic layer also has good recording characteristics.

The magneto-optical recording medium is mainly intended for a magneto-optical disk in which the magnetic layer is formed on a transparent disk-shaped substrate.

Further, it is necessary that the thickness of the second magnetic layer of the magneto-optical recording medium is 8 nm or more. this is,
This is because if the thickness of the second magnetic layer is smaller than 8 nm, it becomes difficult to sufficiently detect the state of magnetization change.

The position adjustment is mainly performed in a state where the magneto-optical recording / reproducing apparatus is provided with an optical pickup and a magnetic head,
That is, it is performed in the assembled state of the mechanical deck, and the maximum magnetic field generation position of the magnetic head with respect to the light spot is found by detecting the reproducing signal which changes on the magneto-optical recording medium.

Here, in the magneto-optical recording medium, it is necessary that the value of the saturation magnetization of the second magnetic layer is larger than the value of the residual magnetization. This is accurate because the magnetization direction may not change at the maximum magnetic field generation position of the magnetic head when the saturation magnetization value of the second magnetic layer is less than or equal to the residual magnetization value. It is difficult to find the maximum magnetic field generation position.

A specific method of detecting the maximum magnetic field generation position is, for example, a method of detecting the maximum magnetic field generation position by examining a change in the amplitude of the reproduction signal. That is, first, for example, the magnetic head is moved back and forth to detect the position where the amplitude of the reproduction signal is maximum. Then, the magnetic head is moved to the left and right, and the position where the amplitude of the reproduction signal is maximum is similarly detected. At this time, if the amplitude of the reproduced signal in the front-rear direction is less than or equal to a threshold value, the maximum amplitude error in the front-rear direction may be large. Search for the position. By performing the above work, the position of the magnetic head is set to a position where the maximum magnetic field is generated with respect to the light spot.

As a method of detecting the maximum magnetic field generation position of the magnetic head, the maximum magnetic field generation is performed by detecting the error number or C / N of the reproduction signal instead of measuring the amplitude of the reproduction signal as described above. You may find out a position.

Further, the present invention is suitable for position adjustment of a magnetic head, in particular, a magnetic head such as a head element of a flying type magnetic head in which a magnetic field generation region is extremely narrow.

Furthermore, as the materials of the first and second magnetic layers having the above-mentioned characteristics, for example, Tb-Fe-Co for the first magnetic layer and Gd- for the second magnetic layer.
The magnetic layer of the above-described magneto-optical recording medium made of an Fe-Co based material is used.

[0021]

In the magnetic head position adjusting method according to the present invention, the maximum magnetic field generation position of the magnetic head with respect to the light spot is determined when the magnetic head is moved back and forth and left and right on the adjusting magneto-optical recording medium. Since it is equivalent to the maximum amplitude position of the reproduction signal of, the position of the magnetic field can be adjusted by observing the change of the amplitude waveform while moving the magnetic head in each direction, so that the accurate maximum magnetic field generation position can be easily found visually. It will be possible.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment in which the magnetic head position adjusting method of the present invention is applied to a magneto-optical disk device having a so-called floating magnetic head will be described in detail below with reference to the drawings.

In order to avoid wear and damage due to contact with the surface of the magneto-optical disk, the flying magnetic head has a head element that is smaller than the surface of the magneto-optical disk by an air flow generated on the surface of the magneto-optical disk when the recording medium rotates at a high speed. It is a magnetic head that is configured to generate a magnetic field while flying while traveling at intervals (so-called flying height, here, of the order of several microns to submicron), and it is extremely effective for a part of a wing-shaped member called a slider. It has a structure in which a small head element is provided and a coil is wound.

Further, as shown in FIG. 1, a magneto-optical disk as a magneto-optical recording medium used for adjusting the position of a magnetic head has a dielectric layer 2, a second magnetic layer 3, and a dielectric layer 2 on a surface of a substrate 1, as shown in FIG. The first magnetic layer 4, the dielectric layer 5, and the reflective layer 6 are D
It is formed by sequentially stacking films by C magnetron sputtering or the like.

Here, the first magnetic layer 4 is made of Tb-Fe-C.
The second magnetic layer 3 is made of an o-based material and has a Gd
It is made of a —Fe—Co-based material.

In this embodiment, the specific composition of the magnetic layer is such that the first magnetic layer 4 has Tb0.18 (Fe0.95).
Co0.05) 0.82 and the second magnetic layer 3 is Gd
It is 0.18 (Fe0.95Co0.05) 0.82. Further, the material of the magnetic layer shown here is an example, and it is also possible to use a generally known rare earth transition metal amorphous material, PtCo material, oxidization material such as garnet.

In the magneto-optical disk for position adjustment used in this embodiment, the coercive force Hc1 of the magneto-optical disk of the first magnetic layer 4 is around room temperature Tr as shown by the curve A in FIG. It is extremely larger than the recording magnetic field H _REC, and the coercive force Hc1 becomes equal to or lower than the recording magnetic field H _REC only in the vicinity of the Curie temperature Tc1. On the other hand, the Kerr rotation angle near the Curie temperature Tc1 is almost zero, and it is impossible to detect the change in the magnetization direction of the magneto-optical disk.

Further, for the second magnetic layer 3, as shown by curve B shown in FIG. 2, the magnetization direction by the recording magnetic field H _REC to larger than the room temperature Tr in the coercive force Hc is the recording magnetic field H _REC Although it cannot be changed, if the temperature is higher than the room temperature Tr and sufficiently lower than the Curie temperature Tc2 and equal to or higher than a predetermined temperature T _{th, the} coercive force Hc2 becomes a value lower than the recording magnetic field H _REC , so that a sufficient Kerr rotation angle is also obtained. Thus, the recording magnetic field can be detected.

Therefore, in this embodiment, a magneto-optical disk is used in which the magnetic layer has a two-layer structure of the first and second magnetic layers 3 and 4 as described above. When the temperature is increased by irradiating the magneto-optical disk with a laser, an effective coercive force H due to exchange coupling is obtained as shown by a curve C in FIG.
Regarding _eff , the coercive force Hc1 of the first magnetic layer 4 is dominant up to near the Curie temperature Tc1 of the first magnetic layer 4, so that the change of the coercive force with respect to temperature is abrupt and the magnetic characteristics are slightly changed. Even if it occurs, the temperature at which the coercive force Hc1 of the first magnetic layer 4 becomes smaller than the recording magnetic field is hard to change. Furthermore, since the change of the magnetization direction occurs at a temperature sufficiently lower than the Curie temperature Tc2 of the second magnetic layer 3, a sufficient Kerr rotation angle can be obtained at a predetermined detection temperature. In addition, the first magnetic layer 4 has a large perpendicular magnetization anisotropy and good recording characteristics are obtained, and the exchange coupling double layer having the first magnetic layer 4 also has good recording characteristics.

In the magneto-optical disk, the value of the saturation magnetization of the second magnetic layer 3 needs to be larger than the residual magnetization. This is accurate because when the value of the saturation magnetization of the second magnetic layer 3 is less than or equal to the value of the residual magnetization, the magnetization direction may not change at the maximum magnetic field generation position of the magnetic head. It is difficult to find the maximum magnetic field generation position.

The position of the flying magnetic head is adjusted using the above-described position adjusting magneto-optical disk. In this embodiment, as shown in FIG. 3, the mechanical deck 1 of the magneto-optical disk device is assembled. The position of the floating magnetic head is adjusted in the raised state. A board 3 (main board and mechanical control board), a magnet head drive board 4 (hereinafter simply referred to as a magdra board 4) are mounted on the mechanical deck 1 to which the flying magnetic head 2 is fixed at one end of its head arm 11. Is connected to the floating magnetic head 2
The floating magnetic head 2 is attached to the front / rear / left / right (that is,
Head moving means 7 for moving the magneto-optical disk in the disk radial direction and the disk tangential direction) is provided.

A radio frequency (RF) level meter 5 is connected to the substrate 3 and an EFM generating means 6 is connected to the magdra substrate 4. In addition, this EFM generating means 6
Instead of, a DC generating means, a single frequency generating means or the like may be used.

In order to adjust the position of the light spot of the floating magnetic head 2 (this is due to the optical pickup provided on the lower portion of the substrate 3 and not shown), first, the above-mentioned adjustment is performed. The cartridge holder 1 is the disk cartridge 8 provided with the magneto-optical disk
3 into the reproduction mode in the test mode, and the EFM generating means 6 inputs the EFM random pattern or the fixed pattern to the magdra substrate 4. Then, an AC magnetic field is generated from the head element 12 provided at the tip of the head arm 11 of the floating magnetic head 2.

In this state, while observing the RF output of the RF level meter 5, the head moving means 7 moves the head element 12 in the disk radial direction to find the position of the head element 12 where the amplitude of the RF output is maximum. Then, the head element 12 is moved on a straight line in the disc tangential direction passing through a position where the amplitude in the disc radial direction is maximum, and R is similarly moved.
The position of the head element 12 where the amplitude of the F output is maximum is found. At this time, if the maximum value of the initial output amplitude in the disk radial direction is less than or equal to a certain value, the position error of the head element 12 at which the output amplitude in the disk radial direction becomes maximum may be large. , Again, find a position where the output amplitude in the radial direction of the disk becomes maximum. With the above work, the position adjustment of the head element 12 of the floating magnetic head 2 with respect to the light spot is completed.

The above working steps are shown in FIG. As shown in this flowchart, the position can be adjusted by performing scanning at most three times in the disk radial direction or the disk tangential direction.

By the way, during the above-mentioned position adjustment, there is a case where the RF output amplitude becomes broad in the vicinity of the position where the RF output amplitude is maximum, and the amplitude change is poor and the position adjustment becomes difficult. R
When the change in the amplitude at the position where the F output amplitude is maximized in each of the disk radial direction and the disk tangential direction was examined, the results shown in FIG. 5 were obtained. As shown in this characteristic diagram, the changes are shown almost completely symmetrically with respect to the maximum amplitude position in both the disk radial direction and the disk tangential direction. Therefore, it is understood that there is almost no problem even if an appropriate amplitude value is selected and the center positions of the two points having the value are regarded as the maximum amplitude position.

Here, the results of an examination of the relationship between the film thickness of the first and second magnetic layers 4 and 3 of the magneto-optical disk and the signal amplitude of the reproduced signal will be shown. In this experiment, the total film thickness of the first and second magnetic layers 4 and 3 was set to 24 nm, and the film thickness ratio of each magnetic layer was changed. As the measurement conditions, the linear velocity of the magneto-optical disk was 1.22 m / s, and the recording magnetic field H _REC was 200 oersted. The measurement result at this time is shown in FIG. FIG. 6 shows the signal amplitude with respect to the film thickness of the second magnetic layer 3 out of the total film thickness of 24 nm.

In general, the signal amplitude during normal reproduction under the same conditions is about 140 mV. Therefore, in order to monitor the change of the magnetization direction, the second
It can be seen from the results of this experiment that the magnetic layer 3 must have a thickness of at least 8 nm.

As described above, in the magnetic head position adjusting method of the present embodiment, the maximum magnetic field generation position of the magnetic head with respect to the light spot is set so that the flying magnetic head 2 is moved forward and backward and left and right on the adjusting magneto-optical disk. Since it is equivalent to the maximum amplitude position of the RF output which is the reproduction signal when moved in the disk radial direction and the disk tangential direction, the amplitude waveform changes while moving the flying magnetic head 2 in each direction. By adjusting the position by looking at it, it becomes possible to easily find the accurate maximum magnetic field generation position through vision.

Therefore, the position of the magnetic head can be adjusted easily and with high accuracy, and the yield and reliability of products can be greatly improved. Also, for example,
By making the magnetic field sensitivity characteristic of the RF output amplitude of the adjusting magneto-optical disk equal to that of the ordinary magneto-optical disk for recording / reproducing, the positional deviation between the optical spot and the magnetic head due to the change in the disk thickness or the tracking trace. It is possible to grasp the decrease state of the RF output amplitude due to.
This makes it possible to perform various evaluations such as the minimum magnetic field current and the core shape.

As a method of detecting the maximum magnetization generation position of the magnetic head, the recording magnetic field H shown in this embodiment is used.
_In addition to the method of evaluating the signal amplitude of the reproduced signal obtained with the magnetization by the _REC, the method of inputting the reproduced signal into the spectrum analyzer to evaluate the C / N, or the recording magnetic field modulated by an arbitrary modulation method There is a method of evaluating an error based on a reproduction signal obtained with the magnetization by H _REC .

For example, a method of evaluating an error based on a reproduced signal will be described. First, the relationship between the recording magnetic field H _REC and the number of errors is examined. As the measurement conditions, the relationship between the signal and the error number obtained by the magnetization due to the recording magnetic field H _REC was measured with the linear velocity of the magneto-optical disk being 1.4 m / s and the laser power being 4.8 mW. It was a result. As shown in this characteristic diagram, the recording magnetic field H _REC
The number of errors decreases almost monotonically with the increase of
The relationship is almost linear. Therefore, it is sufficiently possible to monitor the recording magnetic field H _REC based on this relationship, and the position of the magnetic head can be adjusted using this magneto-optical disk.

As a method for adjusting the position of the magnetic head, the magnetic head is moved on the optical disk while generating an arbitrary recording magnetic field H _REC, and the error number shown in FIG. 7 is most _suitable for the recording magnetic field H _REC . The position of the magnetic head may be adjusted so that the values are close to each other.

An experiment for investigating the relationship between the laser power and the number of errors at the time of recording using the magneto-optical disk will be described. In this experiment, the relationship between the laser power during recording and the number of errors is shown for the case of using an output signal monitored during recording and for the case of performing normal reproduction after recording. As the measurement conditions, the linear velocity of the magneto-optical disk was 1.
The recording magnetic field H _REC was 4 m / s and 200 Oersted.

The measurement results at this time are shown in FIG. From these results, in any case, there is a characteristic that the number of errors sharply decreases when the laser power during recording exceeds a certain value. Therefore, the laser power should be fair based on the value that causes this sudden change. It is possible.

Further, the C / N was measured when a signal of a single frequency with a mark length of 0.847 μm was recorded with a laser power of 5.5 mW during recording under the same linear velocity and recording magnetic field as in the above experiment. However, it was 51 dB. From this, it can be said that the magneto-optical disk can sufficiently withstand the evaluation of the reproducing characteristic.

[0047]

According to the magnetic head position adjusting method of the present invention, the first and second magnetic layers in which the magnetic layers have two or more perpendicular magnetic anisotropies having different Curie temperatures and are exchange-coupled to each other. The magnetic layer has a two-layer structure, and is effective due to exchange coupling of the first and second magnetic layers at a detection temperature substantially equal to the Curie temperature of the first magnetic layer and sufficiently lower than the Curie temperature of the second magnetic layer. The magnetic coercive force is smaller than the recording magnetic field, the magnetization direction can be changed according to the recording magnetic field, and a magneto-optical recording medium exhibiting a detectable Kerr rotation angle is used. Move the head,
Since the maximum magnetic field generation position of the magnetic head with respect to the light spot is found by detecting the reproduction signal that changes at that time, even for a magnetic head having a very narrow magnetic field generation area such as the head element of a floating magnetic head, the magnetic head The position adjustment with respect to the light spot can be performed very easily and reliably, and the yield and reliability of products can be significantly improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the basic structure of a magneto-optical disk used in this embodiment.

FIG. 2 is a characteristic diagram showing temperature dependence of Kerr retention time of a magneto-optical disk.

FIG. 3 is a perspective view schematically showing how the position of the flying magnetic head is adjusted in this embodiment.

FIG. 4 is a flowchart showing a work process for adjusting the position of the flying magnetic head.

FIG. 5 is a characteristic diagram showing the relationship between the position of the head element and the RF output amplitude.

FIG. 6 is a characteristic diagram showing a relationship between a film thickness of a magnetic layer of a magneto-optical disk and a signal amplitude of a reproduction signal.

FIG. 7 is a characteristic diagram showing a relationship between a recording magnetic field and the number of errors.

FIG. 8 is a characteristic diagram showing the relationship between laser power and the number of errors during recording.

[Brief description of reference numerals]

 1 Mechanical Deck 2 Floating Type Magnetic Head 3 Substrate 4 Magnet Head Drive Substrate 5 High Frequency Level Meter 6 EFM Generating Means 7 Head Moving Means 8 Disk Cartridge 11 Head Arm 12 Head Element

Claims (8)

[Claims] 1. A first magnetic layer, which has two or more perpendicular magnetic anisotropies having different Curie temperatures and is exchange-coupled to each other.
And a second magnetic layer, which has a two-layer structure and is substantially equal to the Curie temperature of the first magnetic layer and is sufficiently lower than the Curie temperature of the second magnetic layer. A magneto-optical recording medium having an effective coercive force due to exchange coupling smaller than that of the recording magnetic field, the magnetization direction of which can change in accordance with the recording magnetic field, and which exhibits a detectable Kerr rotation angle. A method of adjusting the position of a magnetic head, characterized in that the maximum magnetic field generation position of the magnetic head with respect to a light spot is found by moving the magnetic head above and detecting a reproduction signal that changes at that time. 2. Amplitude of reproduced signal, number of errors, or C / N
2. The method for adjusting the position of a magnetic head according to claim 1, wherein the maximum magnetic field generation position of the magnetic head with respect to the light spot is found by detecting the. 3. The position adjusting method for a magnetic head according to claim 1, wherein the thickness of the second magnetic layer of the magneto-optical recording medium is 8 nm or more. 4. The method for adjusting the position of a magnetic head according to claim 1, wherein in the magneto-optical recording medium, the value of the saturation magnetization of the second magnetic layer at the detected temperature is larger than the value of the residual magnetization. 5. The method for adjusting the position of a magnetic head according to claim 1, wherein the magneto-optical recording medium is a magneto-optical disk in which a magnetic layer is formed on a transparent disk-shaped substrate. 6. The magnetic head position adjusting method according to claim 1, wherein the magneto-optical recording / reproducing apparatus adjusts the position of the magnetic head in a state where the optical pickup and the magnetic head are provided. 7. The magnetic head position adjusting method according to claim 1, wherein the magnetic head is a floating magnetic head. 8. The first magnetic layer of the magneto-optical recording medium is Tb-
The second magnetic layer is made of Fe-Co based material and the second magnetic layer is Gd-F.
2. The magnetic head position adjusting method according to claim 1, wherein the magnetic head position adjusting method is made of an e-Co based material.