JPH11213310A - Information recording medium and information storage device using the medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a recording medium have satisfactory recording and reproducing characteristics to be strong against a medium noise and to be free from reduction of an information output even in an area of a high recording density, especially of a high linear recording density. SOLUTION: A reference track 2 where marks are recorded at equal intervals and an information track 1 which is adjacent to the reference track 2 and where plural mark columns 3 and 4 consisting of marks at equal intervals are formed are provided, and each of mark columns 3 and 4 of the information track bears the phase difference between marks of this mark column and those of the reference track adjacent to this mark column as information. Mark columns 3 and 4 of the information track 1 and marks of the reference track 2 adjacent to it are recorded at equal intervals so that reproduced signals of the same frequency can be obtained at the time of reproducing marks of two tracks and the phase difference between the phase of the information track reproduced signal and that of the reference track reproduced signal can be detected. The number of marks included in a mark column of the information track corresponding to one information unit is arbitrary, but it is desirably <=15 because too many marks reduce the linear recording density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium and an information storage device, and more particularly, to an information recording medium such as a hard disk, a floppy disk, or the like, in which a head temporarily or constantly contacts. The present invention relates to an information storage device.

[0002]

2. Description of the Related Art For example, a magnetic recording disk (hereinafter referred to as a magnetic disk) used as a large-capacity storage device such as a large computer, a personal computer, a network server, a movie server, a mobile PC, etc. A ferromagnetic thin film such as a cobalt alloy is formed by a sputtering method or the like, and a protective film and a lubricating film are formed on the ferromagnetic thin film to enhance sliding resistance and corrosion resistance. In recent years, with the increase in capacity of magnetic storage devices, there has been a demand for improvements in the recording density of magnetic disks. In the currently used thin-film in-plane magnetic recording medium, generally, the medium noise increases as the recording density increases. In addition, a magnetoresistive head (hereinafter, referred to as a head) often used in small high-density magnetic storage devices recently.
In the case of the MR head, since the head noise is lower than that of the conventional electromagnetic induction type head, the medium noise affects the S / N of the entire apparatus more than before. Under such circumstances, improvement of the S / N ratio (signal intensity ratio to noise intensity) of the magnetic recording film has become a very important issue.

It is considered that the medium noise is caused by the formation of a magnetization transition region in which the magnetization direction is irregularly distributed in the reversal magnetization of the recording magnetization. The disturbance of magnetization in the magnetization transition region further increases due to interference between bits in a high recording density region where the bit interval is smaller than the width of the magnetization transition region. In addition, it has been clarified that the narrowing of the track, which is one of the methods for increasing the recording density, that is, the narrowing of the track interval causes disturbance or partial disappearance of the magnetization transition region due to disturbance of the magnetization.

As means for solving such a problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 6-342511, a magnetic layer is formed into a multilayer structure including a lower magnetic layer and an upper magnetic layer, and the magnetic layer is provided between these magnetic layers. A technique of providing an intermediate layer containing a nitride of a magnetic substance alloy has been proposed.

[0005]

In the above-mentioned prior art (Japanese Patent Laid-Open No. 6-342511), the unit of magnetization is reduced in the direction of the magnetic film thickness, and the medium noise is reduced. However, in a region having a high linear recording density, for example, about 250 kFCI, there is a tendency that the disturbance of the magnetization particularly in the magnetization transition region increases and the signal output decreases. That is, the reduction of the medium noise becomes insufficient only by the miniaturization of the magnetization unit. This means that the conventional recording / detection method of detecting bits based on the magnetic flux intensity from the magnetization transition region cannot cope with high recording density.

SUMMARY OF THE INVENTION An object of the present invention is to provide an information recording medium having good recording / reproducing characteristics, which is resistant to medium noise and does not reduce information output even in a region having a high recording density, particularly in a region where the linear recording density is high. . Another object of the present invention is to provide an information storage device having a high device S / N and a low number of bit errors even at a high recording density of 3 gigabits / square inch or more.

[0007]

According to the present invention, the above object is achieved by recording marks at equal intervals with a predetermined phase difference on two adjacent tracks and carrying information on the phase difference.

That is, the information recording medium according to the present invention comprises:
It has a reference track on which marks at equal intervals are recorded, and an information track adjacent to the reference track and on which a plurality of mark rows composed of marks at equal intervals are recorded. And a phase difference between a mark of the reference track and a mark of a reference track adjacent to the mark row as information.

The information recording medium may have a disk-shaped substrate, and the reference track and the information track may be provided concentrically. When the information recording medium is a long medium such as a tape, the reference track and the information track are provided in parallel.

[0010] The mark sequence of the information track and the mark of the reference track adjacent thereto have a reproduction signal of the same frequency when the marks of the two tracks are reproduced, and the phase of the information track reproduction signal and the phase of the reference track reproduction signal are obtained. It is recorded at equal intervals so that the phase difference between the phases can be detected. Here, the number of marks included in the mark row of the information track corresponding to one information unit may be any number. However, if the number is too large, the linear recording density is reduced.

A plurality of types of marks having different mark intervals may be recorded on a reference track, and address information such as sector information may be carried at the mark intervals. Further, a plurality of types of marks having different mark intervals may be recorded on the reference track, and each mark row of the information track may carry as information the combination of the mark interval of the reference track mark and the phase difference. .

An information recording medium according to the present invention comprises: a magnetic recording film;
The magnetic recording film may include a protective film provided on the magnetic recording film, and a lubricating layer provided on the protective film. The mark may be recorded by a magnetization transition region due to in-plane magnetization of the magnetic recording film. The mark may be recorded by using a film, a protective film provided on the magnetic recording film, and a lubricating layer provided on the protective film, and using a magnetization transition region caused by perpendicular magnetization of the magnetic recording film.

When information is recorded by magnetic recording,
As a substrate of the information recording medium, a non-magnetic substrate such as an aluminum substrate, a glass substrate, and a graphite substrate is used.
The surface of the aluminum substrate may be plated with nickel phosphorus. Alternatively, a process for improving the flying characteristics of the head may be performed by forming concentric fine grooves on the substrate by pressing diamond abrasive grains or polishing tape while rotating the substrate. Furthermore, with a glass substrate,
The surface may be chemically etched with a chemical such as a strong acid to form fine irregularities, to reduce the area in contact with the head, and to reduce the tangential force during sliding. In these, the same effect can be expected even if the surface of the protective film is masked with fine particles and etched. Furthermore, when the CSS zone and the data zone are separated, the innermost CS zone is
Regular irregularities may be provided in the S zone.

Before the magnetic recording film is formed on the substrate of the magnetic recording medium, a base film such as chromium may be formed by sputtering or the like in order to improve the magnetic properties of the recording film. Good. When using a glass substrate or a ceramic substrate, in order to orient the easy axis of magnetization in the plane and to improve the magnetic characteristics, a cobalt-chromium alloy of 5n is formed before forming the underlayer film.
It is also effective to precoat with a film thickness of not more than m.

As the magnetic recording film, a material obtained by mixing a small amount of platinum, tantalum, vanadium, samarium, etc. with cobalt nickel, cobalt chromium, cobalt chromium is used. As a method for forming a magnetic recording film, a method is generally used in which these alloy targets are formed on a substrate by a sputtering method using argon. The thickness of the magnetic recording film is preferably 10 nm or more and 40 nm or less from the viewpoint of magnetic characteristics. The medium has a coercive force of 2 kOe (Oersted) or more, and Br · t, which is the product of the magnetic layer thickness t and the residual magnetic flux density Br, is 10
It is desirably in the range of １３０130 G · μm (Gauss / micron). If the coercive force is smaller than 1.8 kOe, the output at a high recording density (150 kFCI or more) becomes small, which is not preferable. Also, Br · t is 130 G · μ
When it is larger than m, the resolution is reduced, and when it is smaller than 10 G · μm, the output becomes too small. Therefore, when performing high-density recording of 3 gigabits / square inch, sufficient recording / reproducing characteristics cannot be obtained.

A lubricant is applied on the protective film in order to improve the sliding resistance. As the lubricant, a perfluoropolyether polymer lubricant having a main chain structure of three elements of carbon, fluorine and oxygen is used. Fluorine-substituted alkyl compounds can also be used as lubricants. Other organic lubricants and inorganic lubricants may be used as long as they have stable sliding and durability. These lubricants are generally applied by a solution, but may be applied by photo CVD of fluorinated olefin and oxygen. An appropriate film thickness of the lubricant is 1 to 3 nm. If the thickness is smaller than that, the lubricating properties decrease, and if the thickness is larger, the meniscus force increases, and the static friction force (stiction) between the head and the disk
Is undesirably large.

Further, the protective film may be made of any of amorphous carbon, silicon-containing amorphous carbon, nitrogen-containing amorphous carbon, boron-containing amorphous carbon, silicon oxide, zirconium oxide and cubic boron nitride. Is preferably used. As a method of forming these amorphous carbon protective films, a method of forming by sputtering in an inert gas targeting graphite or a mixed gas of an inert gas and a hydrocarbon gas such as methane, a hydrocarbon gas, Organic compounds such as alcohol, acetone, and adamantane are used alone or mixed with hydrogen gas, inert gas, etc.
There is a method of forming by VD, or a method of ionizing an organic compound, applying a voltage, accelerating, and colliding with a substrate.

Further, the information recording medium of the present invention includes a magneto-optical recording film, and heats the magneto-optical recording film to a temperature exceeding the Curie point while applying an external magnetic field to form a mark by the recorded magnetization. Alternatively, the mark may be recorded by the unevenness formed on the recording medium. When a mark is recorded by unevenness, a recorded signal is reproduced using a change in light amount due to a phase shift of reflected light due to the unevenness.

An information storage device according to the present invention comprises: an information recording medium; a recording / reproducing head having a recording unit and a reproducing unit; a driving unit for moving the recording / reproducing head relative to the information recording medium; The information recording medium includes: a reference track on which marks at equal intervals are recorded; and an information track adjacent to the reference track, on which a plurality of mark trains composed of marks at equal intervals are recorded. Is characterized in that each mark row carries, as information, a phase difference between a mark in the mark row and a mark of a reference track adjacent to the mark row.

When the information recording medium is a magnetic recording medium, a magnetic head having, for example, an electromagnetic induction type recording section and a magnetoresistive effect type reproduction section can be used as the recording / reproducing head. It is possible to realize a recording density of square inches or more. When the information recording medium is disk-shaped and the reference track and the information track are provided concentrically, the position of the mark row recorded concentrically on the information track and the position of the mark concentrically recorded on the reference track are set. The phase difference detection is performed, for example, as follows. First, while rotating the disk at a constant speed, the read head reads the reference track mark and the information track mark,
It is subjected to fast Fourier transform to calculate the phase angle. That is, the mark of each track detected by the head on the information recording medium rotating at a constant speed is defined as a function h (t) using time t as a variable. Let H (f) be the Fourier transform of h (t).
H (f) is a function of the frequency f and is generally a complex quantity. H (f) = R (f) + iI (f), where R (f) is the real part of the Fourier transform and I (f) is the imaginary part of the Fourier transform. The phase angle θ of the Fourier transform is θ = arctan [I (f) /
R (f)]. Thus, the phase difference between the reference track mark and the information track mark is calculated. The amplitude is given by the square root of the sum of the square of the real part and the square of the imaginary part of the Fourier transform. The S / N ratio is obtained by dividing the peak area of the signal by the area of the background in a spectrum obtained by squaring the amplitude and plotting against the frequency.

The marks on the reference track and the information track are detected by a reading head, but are simultaneously detected by a head having two reproducing sections, one reproducing section for the reference track and the reproducing section for the information track. Alternatively, the reference track and the information track may be read by a single head having one reproducing unit by seeking. Also,
Reading may be performed with higher spatial resolution using a magnetic force microscope or the like.

Taking a magnetic disk as an example, on a disk-shaped substrate, concentric, equally-spaced marks are provided immediately beside the reference tracks, which have equally-spaced marks on the circumference of concentric circles. When an information track is provided and a phase difference between marks of two tracks for reference and information is recorded as numerical information, information can be recorded without lowering the S / N ratio even at a high linear recording density. That is, the signal intensity decreases due to the disturbance of the magnetization in the magnetization transition region, and the medium noise relatively affects. However, when converted into a phase signal and detected, even if the amplitude is reduced, it does not appear in the phase difference. Noise is not affected because it is not synchronized with the phase difference between the two tracks. That is, the periodic noise can be suppressed by taking the phase difference.

Further, when the magnetic recording medium according to the present invention is combined with a magnetic head using a magnetoresistive element in the reproducing section, a highly reliable information storage device having a higher recording density than before can be realized. It is possible to do. That is, the magnetoresistive head has high sensitivity, but has a disadvantage that it is easily damaged by static electricity and heat. Conventionally, at high recording densities, the output is reduced and the S / N is reduced, so it has been necessary to reduce the head flying height. However, when the flying height is reduced, the number of true contact points between the head and the recording medium increases, and the head sensitivity fluctuates instantaneously due to the thermal asperity, that is, the flash temperature, and the probability of occurrence of a noise phenomenon increases. Since the information recording medium according to the present invention has higher sensitivity than the conventional information recording medium for detecting the amplitude intensity, it is not necessary to reduce the flying height of the head. Therefore, it is possible to realize a highly reliable information storage device with a high device S / N ratio, which reduces the possibility of real contact and reduces the possibility of thermal asperity.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. The information recording medium includes a disk-shaped medium such as a magnetic disk (hard disk, floppy disk), a magneto-optical disk, and an optical disk, and a tape-shaped medium such as a magnetic tape. Although a recording medium will be described as an example, the present invention is applicable not only to a disk-shaped recording medium but also to a tape-shaped recording medium.

<First Embodiment> FIG. 1 is a schematic view of a recording pattern on a longitudinal recording magnetic disk which is an example of an information recording medium according to the present invention. The reference track 2 and the information track 1 are arranged adjacent to each other on the magnetic disk.
The reference track 2 includes a positive magnetization transition region 5a and a negative magnetization transition region 6a formed by alternately reversed in-plane magnetic domains.
Are formed at equal intervals. The information track 1 has a mark row 3 of information A and a mark row 4 of information B.
Is recorded. The mark row 3 of information A and the mark row 4 of information B are composed of equally-spaced marks of a positive magnetization transition region 5b and a negative magnetization transition region 6b formed by alternately reversed in-plane magnetic domains. The mark interval of the mark rows 3 and 4 of the information track 1 is the same as the mark interval of the reference track 2. The mark row 3 of the information A and the mark row 4 of the information B recorded on the information track 1 have a phase difference determined for each information with respect to the mark of the reference track 2, and the information is recorded by the phase difference. .

The magnetic disk of this example was manufactured by the following method. First, a 30 nm thick Cr-15 at% Ti base film and a 25 nm thick Co-16 at% Cr-4 at% T are formed on a glass substrate by a well-known continuous sputtering apparatus.
An a-alloy magnetic film and a sputtered carbon protective film having a thickness of 20 nm were sequentially formed. Thereafter, the magnetic disk was taken out of the film forming apparatus, and a perfluoropolyether-based lubricant was
The solution was applied with a thickness of m. The magnetostatic properties of the magnetic disk thus prepared are as follows: the coercive force is 2.9 kOe, the residual magnetic flux density / film thickness product is 82 G · μm, and the coercive force squareness ratio is 0.65.
Met.

FIG. 2 is a view of the outflow side end face showing the structure of the thin film magnetic recording head used for mark recording. In this thin-film magnetic recording head, an electromagnetic induction type thin-film magnetic recording head having the same structure as a reference track head 8 and an information track head 9 is arranged on a slider 7 at a distance of 10 μm, which is the distance between the reference track and the information track. It is formed.

A recording pattern as shown in FIG. 1 was recorded on the magnetic disk using a thin-film magnetic recording head whose end face on the outflow side is schematically shown in FIG. An all-ones pattern was recorded on the reference track 2 by the reference track head 8 at a linear recording density of 250 kFCI (the number of magnetization reversals per inch). At the same time as the recording on the reference track 2, the information track 1 adjacent to the reference track 2 is applied to the information track head 9 by the information track head 9 at the same linear recording density and the magnetization reversal number
Only the mark rows 3 and 4 were recorded.

The information recorded on the information track is represented by the phase difference between the reference track 2 and the mark of the information track 1. For example, the mark row 3 of the information A shown in FIG. 1 has a phase difference of -160 degrees with respect to the mark of the reference track 2, and the mark row 4 of the information B has a phase difference of +90 degrees with respect to the mark of the reference track 2. There is a phase difference of These were digitized by 10 degrees from -170 degrees to +180 degrees to obtain numerical information from 1 to 36. That is, the information A consisting of the mark string 3 represents the numerical information “2”, and the information B consisting of the mark string 4 represents the numerical information “27”.

The number of disks was plural, and the sector information was written on an independent disk. The recorded information was reproduced by a reproducing head using a magnetoresistive element. In the reproducing head used, two magnetoresistive elements for reproducing the information track and the magnetoresistive element for reproducing the reference track are separated from each other by 10 μm, which is the same as the distance between the information track 1 and the reference track 2. It is a reproducing head provided. The phase difference between the signal reproduced from the information track 1 and the signal reproduced from the reference track 2 was calculated by fast Fourier transform.

FIG. 3 is a block diagram of an example of the signal reproducing circuit. As shown in FIG. 3, the signal of the information track 1 and the signal of the reference track 2 are simultaneously detected by the information track head and the reproduction track head of the reproduction head, respectively. The data is supplied to a conversion unit and subjected to fast Fourier transform, and the result is input to an arithmetic circuit. The arithmetic circuit calculates the phase angle difference by comparing the phase angle of the mark row of the reference track with the phase angle of the mark rows 3 and 4 of the information track, and calculates the phase angle difference based on the above-described rule of digitization. Mark row 3, 4
Is reproduced. In this example, mark column 3,
The number of marks (magnetization reversals) 5b and 6b recorded in No. 4 was about 5, and a clear phase difference could be calculated. The medium S / N of the recording medium was 4.5.

Here, recording and reproduction are performed using a slider having two head elements. However, the recording pattern shown in FIG. 1 can be written by using a slider having one head element. In this case, first, the pattern of the reference track 2 is written in the first round, and then the pattern of the information track 1 is recorded in the next round. Therefore, the time required for recording and reading is doubled, but since only one head element is required, the apparatus cost can be reduced as compared with the case where two head elements are used.

<Embodiment 2> In this embodiment, a magnetic recording disk having the same magnetostatic characteristics as in Embodiment 1 is used. Then, as shown in FIG.
Sector information including two frequency components. That is, the reference track 10 is provided with two types of mark rows, that is, a mark row 11 in which marks with a narrow mark interval are recorded at equal intervals and a mark row 12 in which marks with a wide mark interval are recorded at equal intervals. The mark interval of the mark row 12 was constant, and the mark interval of the mark row 11 was variable. The mark trains 3 and 4 representing the information of the information track 1 are recorded adjacent to the mark train 12 of the reference track 10 and the mark train 1 of the reference track 1 is recorded.
Mark string 11 indicating sector information between the mark string 2 and the mark string 12
Was recorded.

FIG. 5 shows a power spectrum measured in a certain sector portion of the reference track 10. Here, the measurement conditions were a rotation speed of 1500 rpm and a radial position of 22 mm. The reference mark of the mark row 12 is recorded at a linear recording density of 250 kFCI, and a 17.0 MHz signal 1
Appears as 3. At 18.4 MHz, a signal 14 giving sector information reproduced from the mark sequence 11 is seen. The latter is 18.4 MH, depending on the sector position.
z, 18.5 MHz, 18.6 MHz,... are gradually shifted to sector information. With these ideas, the number of recording surfaces could be increased.

<Embodiment 3> In this embodiment, a perpendicular magnetic recording medium is used as a magnetic disk. The configuration of the information recording medium is such that a Pt underlayer with a thickness of 20 nm, Pt (1.1 nm) /
16 layers of Co (0.5 nm) and a thickness of 20 n
m of the sputtered carbon protective film was formed. Thereafter, the magnetic disk was taken out of the film forming apparatus, and a perfluoropolyether-based lubricant was applied with a solution having a thickness of 2 nm. The magneto-static characteristics of the magnetic disk thus prepared have a coercive force in the direction perpendicular to the film surface of 2.1 kOe and a saturation magnetization of 350 kA / m.
Met.

A recording pattern as shown in FIG. 1 was recorded on this magnetic disk by using a thin-film magnetic recording head whose outflow side end face is schematically shown in FIG. On the reference track 1, an all-ones pattern is recorded at a linear recording density of 250 kFCI. On the information track 1 adjacent to the reference track 2, mark rows 3 and 4 for the same number of magnetization reversals at the same linear recording density are provided. Recorded.

In the signal reproduction, the information track 1 signal and the reference track 2 signal are simultaneously detected by the information track head and the reproduction track head of the reproduction head, respectively.
As shown in FIG. 3, after the detection signals are amplified by the preamplifiers respectively, they are subjected to fast Fourier transform by the high-speed conversion unit, and the result thereof is calculated by the arithmetic circuit. The phase angle difference is calculated by comparing the phase angles, and the calculation is performed based on the same rules of digitization as in the first embodiment, thereby reproducing the digitized information of the mark rows 3 and 4. As a result, the medium S / N of this recording medium was 3.5.

<Embodiment 4> In this embodiment, a magnetic disk having the same magnetostatic characteristics as in Embodiment 1 is used.
Then, as shown in FIG. 4, the reference track 10 includes two frequency components (mark intervals). Here, at a rotation speed of 1500 rpm and a radial position of 22 mm, the reproduction frequency of the mark row 12 having a fixed frequency was set to 17 MHz.
An information track 1 having mark rows 3 and 4 having the same frequency (mark interval) as the mark row 12 having a fixed frequency and having a predetermined phase difference with respect to the mark row 12 was formed adjacently. The mark rows 3 and 4 of the information track 1 correspond to the first embodiment.
In the same manner as described above, the phase difference was quantified at 10-degree intervals. That is, in the example shown in FIG. 4, the mark row 3 of the information track 1 has a phase difference of -160 degrees with respect to the mark row 12, and this is set to a numerical value "2".
Has a phase difference of +90 degrees, which is represented by a numerical value “27”.
And

In the reference track 10, a mark row 11 having a variable frequency (mark interval) lower than the fixed frequency mark row 12 (for example, 2.125 MHz) is used to detect the phase of the mark rows 3 and 4 of the information track 1. The mark rows 3 and 4 of the information track are formed in portions that are not adjacent to each other so as not to hinder the recording. Therefore, the value of the possible frequency of the mark sequence 11 of the reference track 10 is obtained by dividing a fraction of the frequency of the fixed frequency mark sequence 12 of the reference track 10 by 2. 2.125 MHz, 1.0625 MHz, 53
It becomes a value such as 1.25 kHz and 265.63 kHz.

For example, for the frequency-variable mark row 11 of the reference track 10, a numerical value “1” is set at a frequency of 2.125 MHz, a numerical value “2” is set at a frequency of 1.0625 MHz,
Numerical value “3” for frequency 531.25 kHz, frequency 26
The numerical value “4” is assigned to 5.63 kHz. Numericalization based on the frequency of the variable frequency mark train 11 in the reference track 10 and the fixed frequency mark train 1 in the reference track 10 of the mark trains 3 and 4 in the information track 1
By combining the digitization by the phase difference with 2,
Numerical information up to 4 × 36 = 144 can be recorded. In the example shown in FIG. 4, the mark row 3 has numerical information “2” which is a product of a numerical value “1” based on the frequency of the mark row 11 immediately before and a numerical value “2” based on the phase difference. Column 4 has numerical information “27” which is the product of the numerical value “1” based on the frequency of the immediately preceding mark column 11 and the numerical value “27” based on the phase difference. Medium S of recording medium of the present embodiment
/ N was 4.6.

<Embodiment 5> In this embodiment, a magneto-optical disk is used as an information recording medium. The magneto-optical disk was manufactured as follows. A 90-nm-thick recording film made of a rare-earth iron-group amorphous alloy is formed by sputtering on a 3.5-inch-diameter substrate made of polycarbonate, in which guide grooves for irradiating a laser beam are formed in advance by a stamper, and oxidized thereon. An aluminum nitride protective film for prevention was formed to a thickness of 20 nm to obtain a magneto-optical disk.

As in the first embodiment, a recording pattern including a reference track and an information track was formed on this magneto-optical disk. However, as a recording method, by condensing a laser beam on the recording surface of the disk to a diameter of about 1 μm, the temperature of the portion hit by the laser spot increases,
When the temperature exceeded the Curie point (200 ° C.), the magnetization direction was changed by an external magnetic field, thereby recording a signal. The reference track has an all-ones pattern with a linear recording density of 250 kFC.
In the information track 1 adjacent to the reference track, a mark train of the same number of magnetization reversals as the number of magnetization reversals was recorded on the information track 1 adjacent to the reference track with a phase difference of 90 degrees from the mark of the reference track.

In the signal reproduction, the signal was detected by utilizing the fact that the polarization plane of the laser beam reflected from the recording film changes due to the direction of magnetization due to the Kerr effect. Reproduction of information was performed by the signal reproduction circuit shown in the block diagram of FIG. 3, as described in the first embodiment. That is, the information track signal and the reference track signal are simultaneously detected by the information track reproduction head and the reference track reproduction head, respectively, and the detected signals are respectively amplified by the preamplifier and then supplied to the fast Fourier transform unit. Fourier transform is performed, and the result is input to an arithmetic circuit. The arithmetic circuit calculates the phase angle difference by comparing the phase angle of the mark row of the reference track and the phase angle of the mark row of the information track, and calculates the phase angle difference based on the rule of digitization as described in the first embodiment. By doing so, the numerical information was reproduced. At this time, the medium S / N was 3.2.

<Embodiment 6> In this embodiment, an optical disc is used as an information recording medium. This optical disk was manufactured as follows. That is, as in the first embodiment, a disc having a diameter of 12 cm is formed by injection molding polycarbonate on a stamper in which a recording pattern is formed on a reference track and an information track, and an aluminum reflective film is deposited on a pit surface, and a protective film is formed. Was applied, and two sheets were stuck together with the surface facing inward to obtain an optical disk. In the reference track, equally spaced pits have a linear recording density of 25.
0 kFCI is recorded, and on an information track adjacent to the reference track, a mark train composed of five equally spaced pits having the same linear recording density and a phase difference of 90 degrees from the pits of the reference track is recorded. I have.

The reading of the information on the optical disk was performed by irradiating the optical disk with a red semiconductor laser beam focused to a diameter of 1 μm and detecting a change in the amount of reflected light due to the phase on the pit surface (uneven surface). Reproduction of information was performed by the signal reproduction circuit shown in the block diagram of FIG. 3, as described in the first embodiment. That is, the information track signal and the reference track signal are simultaneously detected by the information track reproduction head and the reference track reproduction head, respectively, and the detected signals are respectively amplified by the preamplifier and then supplied to the fast Fourier transform unit. Fourier transform is performed, and the result is input to an arithmetic circuit. The arithmetic circuit calculates the phase angle difference by comparing the phase angle of the mark row of the reference track and the phase angle of the mark row of the information track, and calculates the phase angle difference based on the rule of digitization as described in the first embodiment. By doing so, the numerical information was reproduced. The medium S / N in this case was 3.3.

<Embodiment 7> FIGS. 6A and 6B are schematic views showing an example of a magnetic storage device according to the present invention. FIG. 6A is a schematic plan view, and FIG. FIG. This magnetic storage device has a well-known configuration including a magnetic recording medium 15, a driving unit 16 for rotating the magnetic recording medium 15, a magnetic head 17, its driving unit 18, and a recording / reproducing signal processing unit 19 for the magnetic head 17. Is a magnetic storage device having Here, two magnetic recording / reproducing elements as shown in FIG. 2 were formed on the outflow side end face of the magnetic head 17.

The magnetic head 17 used in this magnetic storage device
FIG. 7 shows a schematic diagram of the structure of one of the recording / reproducing elements. This magnetic head is a read / write separation type head in which an electromagnetic induction type magnetic head for recording and a magnetoresistive head for reproduction formed on the base 26 are combined. A portion where the magnetoresistive sensor 20 is sandwiched between the lower shield layer 21 and the upper shield recording pole layer 22 functions as a read head, and the coil 2
3 and the upper recording magnetic layer 2 and the upper recording magnetic pole 2
4 works as a recording head. An output signal from the magnetoresistive sensor 20 is taken out through the electrode pattern 25 to the outside.

FIG. 8 shows a longitudinal sectional structure of the magnetoresistive sensor. This magnetoresistive sensor has a thin film magnetoresistive conductive layer 29 of a ferromagnetic material formed on a gap layer 27 between a shield layer and a magnetoresistive sensor, and a thin film magnetoresistive conductive layer for forming a single magnetic domain. An antiferromagnetic domain control layer 28; a nonmagnetic layer 31 for cutting off exchange interaction between the thin film magnetoresistive conductive layer and the antiferromagnetic domain control layer in the magnetosensitive portion 30 of the thin film magnetic conductive layer; As means for generating a bias magnetic field for the magnetic sensing unit 30, the current shunt ratio between the soft magnetic layer or the permanent magnet film bias layer 33 and the soft magnetic layer or the permanent magnet film bias layer 33 and the thin film magnetoresistive conductive layer 29 is adjusted. A high-resistance layer 32 for performing the operation.

As the magnetic recording medium 15, the first embodiment
The magnetic disk described above was used. Using the magnetic storage device of the present embodiment, the recording / reproducing characteristics were evaluated under the conditions of a head flying height of 30 nm, a shield layer interval of 0.35 μm or less, a linear recording density of 250 kFCI, and a track density of 10 kTPI.
Reproduction of information was performed by the signal reproduction circuit shown in the block diagram of FIG. 3, as described in the first embodiment. That is, the information track signal and the reference track signal are simultaneously detected by the information track reproduction head and the reference track reproduction head, respectively, and the detected signals are respectively amplified by the preamplifier and then supplied to the fast Fourier transform unit. Fourier transform is performed, and the result is input to an arithmetic circuit. The arithmetic circuit compares the phase angle of the mark row of the reference track with the phase angle of the mark row of the information track,
Numerical information was reproduced by calculating the phase angle difference and calculating the phase angle difference based on the digitization rule as described in the first embodiment. The equipment S / N was 3.2.

Here, an example in which a recording / reproducing separation head in which two electromagnetic induction magnetic heads for recording and two magnetoresistive heads for reproduction are combined is used as the magnetic head has been described. It is also possible to mount one electromagnetic induction type magnetic head for recording and one magnetoresistive head for reproduction on the assembly, and write and read to and from the reference track and the information track separately. To do this, trace the reference track on the first lap,
Trace the information track on the lap. In this way,
Reading and writing can be performed by two rounds of operation.

<Comparative Example 1> A linear recording density similar to that of the first embodiment was applied to the same longitudinal recording magnetic disk as that of the first embodiment.
The all-ones pattern was recorded on the adjacent portion of the reference track by the phase difference. A signal was reproduced by a method of expressing the magnetization reversal by a binary number as in conventional digital recording, and the medium S / N was measured. As a result, the medium S / N was 2.8.

<Comparative Example 2> A linear recording density similar to that of the third embodiment was applied to a perpendicular recording magnetic disk similar to the third embodiment.
The all-ones pattern was recorded on the adjacent portion of the reference track by the phase difference. A signal was reproduced by a method of expressing the magnetization reversal by a binary number as in the conventional digital recording, and the medium S / N was measured. As a result, the medium S / N was 2.1.

Comparative Example 3 An all-ones pattern was recorded on a magneto-optical disk similar to that of the fifth embodiment at the same linear recording density and the same phase difference as that of the fifth embodiment in a portion adjacent to the reference track. The signal was reproduced in the same manner as in the conventional digital recording, and the medium S / N was measured. As a result, the medium S / N was 2.0.

<Comparative Example 4> On an optical disk similar to that of the sixth embodiment, a recording pattern was recorded adjacent to a reference track at the same linear recording density and phase difference as that of the sixth embodiment. The signal is reproduced in the same manner as in the conventional digital recording, and the medium S /
N was measured. As a result, the medium S / N was 2.1.

<Comparative Example 5> A drive unit for rotating and driving an information recording medium similar to that of the seventh embodiment, a magnetic head and its driving means, and a recording / reproducing signal processing means for the magnetic head are provided.
A magnetic storage device was manufactured by incorporating the magnetic disk described in Comparative Example 1 as an information recording medium. Using this magnetic storage device, the head flying height was 30 nm, and the shield layer interval was 0.35.
μm or less, linear recording density 250 kFCI, track density 1
When the recording and reproduction characteristics were evaluated under the condition of 0 kTPI,
An apparatus S / N of 1.7 was obtained.

[0056]

According to the present invention, the medium noise of the information recording medium can be reduced and the S / N ratio can be improved.
Even at a high recording density of gigabit / square inch, an information storage device having a high device S / N and a low number of bit errors can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an example of a recording pattern on a magnetic disk according to the present invention.

FIG. 2 is a schematic diagram of an outflow side end face of a magnetic recording / reproducing head used for signal recording.

FIG. 3 is a block diagram showing an example of a signal reproducing circuit according to the present invention.

FIG. 4 is an explanatory diagram of another example of a recording pattern on a magnetic disk according to the present invention.

FIG. 5 is a diagram showing a power spectrum of a reference track according to an example of the present invention.

FIGS. 6A and 6B are schematic views showing an example of a magnetic storage device according to the present invention, wherein FIG. 6A is a schematic plan view, and FIG.

FIG. 7 is a schematic three-dimensional view showing a cross-sectional structure near one recording / reproducing element of the magnetic head.

FIG. 8 is a schematic diagram of a longitudinal sectional structure of one magnetoresistive sensor section of the magnetic head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Information track, 2 ... Reference track, 3 ... Mark row | line showing information A, 4 ... Mark row | line showing information B, 5 ... Positive magnetization transition area, 6 ... Negative magnetization transition area, 7 ... Slider, 8 ... Reference track head, 9 Information track head, 10 Reference track having two frequency components, 11 Low frequency component, 12 High frequency component, 13 17
MHz information component, 14 ... 18.4 MHz information component,
15 ... magnetic recording medium, 16 ... magnetic recording medium drive, 17
... Magnetic head, 18 ... Magnetic head drive unit, 19 ... Recording / reproducing signal processing system, 20 ... Magnetic resistance sensor, 21 ... Lower shield layer, 22 ... Upper shield recording magnetic pole layer, 23 ... Coils, 24 ... Upper recording magnetic pole, 25: Conductive layer, 26: Substrate, 27: Gap layer between shield layer and magnetoresistive sensor, 28: Antiferromagnetic domain control layer, 29: Thin film magnetoresistive conductive layer, 30: Sensitivity of thin film magnetoresistive conductive layer Magnetic part, 31 ...
Non-magnetic layer, 32: high resistance layer, 33: soft magnetic layer or permanent magnet film bias layer

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[Procedure amendment]

[Submission date] February 1, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

1. A have a reference track adjacent the information track
Information recording medium, and recording a plurality of types of marks having different mark spacing on the reference track, characterized in that by supporting the address information in the mark distance.

2. An equidistant mark and a plurality of marks having different mark intervals.
The reference track on which the type mark is recorded,
A mark row consisting of marks at equal intervals adjacent to the track
A plurality of recorded information tracks, and each mark row of the information track has a mark in the mark row.
Mark and the mark of the reference track adjacent to the mark row.
A phase difference, and mark spacing of marks of the reference track
An information recording medium carrying a combination of the above as information.

3. The number of marks included in the mark sequence is fifteen.
3. The information recording medium according to claim 1, wherein the number is equal to or less than the number.

4. A magnetic recording film, a protective film provided on said magnetic recording layer, and a lubricating layer provided on the protective layer, the mark-plane magnetization of the magnetic recording film The information recording medium according to any one of claims 1 to 3 , wherein the information recording medium is a magnetization transition region according to:

5. A magnetic recording film, the protective film provided on the magnetic recording film, and a lubricating layer provided on the protective layer, the mark is due to the vertical magnetization of the magnetic recording film information recording medium of any one of claims 1-3, characterized in that the magnetization transition region.

Further comprising: a magneto-optical recording film, the mark is characterized by a mark by the magnetization recorded by heating to a temperature above the Curie point while applying external magnetic field to the magneto-optical recording film set forth in any one information recording medium according to claim 1-3.

Wherein said mark information recording medium according to any one of claims 1-3, characterized in that the mark due to the unevenness formed on the recording medium.

8. An information recording medium comprising: a recording / reproducing head having a recording unit and a reproducing unit; a driving unit for moving the recording / reproducing head relative to the information recording medium; and a recording / reproducing signal processing unit. In the information recording medium, the mark at equal intervals and the difference between the mark intervals are different.
A reference track on which a plurality of types of marks are recorded,
An information track adjacent to the reference track and having a plurality of mark rows formed of marks at equal intervals recorded thereon, wherein each mark row of the information track is adjacent to the mark in the mark row and the mark row. A combination of the phase difference with the reference track mark and the mark interval of the reference track mark
An information storage device characterized in that a matching is carried as information.

9. equidistant to one of the two adjacent tracks
Record marks and multiple types of marks with different mark intervals
On the other hand, at regular intervals with a predetermined phase difference
And a set of the phase difference and the mark interval.
Information recording method characterized by supporting the information to suit observed.

Claims (10)

[Claims] An information track includes a reference track on which marks at equal intervals are recorded, and an information track adjacent to the reference track and on which a plurality of mark trains composed of marks at equal intervals are recorded. An information recording medium, characterized in that a row carries, as information, a phase difference between a mark in the mark row and a mark of the reference track adjacent to the mark row. 2. The number of marks included in the mark sequence is one.
2. The information recording medium according to claim 1, wherein the number is five or less. 3. The information recording medium according to claim 1, wherein a plurality of types of marks having different mark intervals are recorded on the reference track, and address information is carried in the mark intervals. 4. A plurality of types of marks having different mark intervals are recorded on the reference track, and each mark row of the information track carries, as information, a combination of a mark interval of the reference track mark and the phase difference. The information recording medium according to claim 1, wherein the information is recorded. 5. A magnetic recording film, comprising: a protective film provided on the magnetic recording film; and a lubricating layer provided on the protective film, wherein the mark has an in-plane magnetization of the magnetic recording film. 5. The information recording medium according to claim 1, wherein the information recording medium is a magnetization transition region according to claim 1. 6. A magnetic recording film, comprising: a protective film provided on the magnetic recording film; and a lubricating layer provided on the protective film, wherein the mark is formed by perpendicular magnetization of the magnetic recording film. 5. The information recording medium according to claim 1, wherein the information recording medium is a magnetization transition region. 7. A mark provided with a magneto-optical recording film, wherein the mark is a mark of magnetization recorded by heating to a temperature exceeding the Curie point while applying an external magnetic field to the magneto-optical recording film. The information recording medium according to claim 1. 8. The information recording medium according to claim 1, wherein the mark is a mark formed by irregularities formed on the recording medium. 9. An information recording medium, comprising: a recording / reproducing head including a recording unit and a reproducing unit; a driving unit for moving the recording / reproducing head relative to the information recording medium; and a recording / reproducing signal processing unit. The information recording medium has a reference track on which marks at equal intervals are recorded, and an information track adjacent to the reference track and on which a plurality of mark trains composed of marks at equal intervals are recorded. An information storage device, wherein each mark row carries, as information, a phase difference between a mark in the mark row and a mark of the reference track adjacent to the mark row. 10. An information recording method comprising: recording marks at equal intervals on two adjacent tracks with a predetermined phase difference; and carrying information on the phase difference.