JP2851325B2 - Magnetic storage device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a head positioning method for an information recording device such as a magnetic disk device, a magnetic tape device, a magneto-optical disk device, a magnetic card device, and a magnetic method using the method. The present invention relates to a storage device, and more particularly to a technique applicable to a large-capacity storage device aiming at a high track density for positioning a target data track with high accuracy.

[Conventional technology]

In the magnetic disk device, the track density as well as the bit density has been increased with the large-capacity writing. Due to the increase in track density, the track pitch is now on the order of several μm, and increasing the precision of head positioning has become an increasingly important issue. The conventional servo surface servo method with relatively high positioning accuracy requires a design that takes into account the spread track width that always occurs due to the characteristics of magnetic recording, such as the spread of recording bits when writing a signal or the erase width when erasing a signal. Because of the necessity, the track pitch had much more margin than the effective magnetic recording area. In contrast,
As described in JP-A-51-104805 and JP-A-62-256225, the above-mentioned spread area can be eliminated by physically separating adjacent tracks. That is, a method is provided in which grooves are provided regularly along the track width direction, and signals are recorded on convex portions between the grooves.

[Problems to be solved by the invention]

When the above method is adopted as a recording medium, some problems occur when the system is configured. As one of them, there is a problem of positioning a conversion element for servo (hereinafter, servo head). With the grooved medium of the above method (hereinafter referred to as a discrete track medium), the track density can be increased to about 2 to 10 times as compared with the conventional method, and accordingly, the positioning accuracy of the servo head must be increased. Is required. As a method of positioning a discrete medium, there are a method of recording sector servo information in a convex portion, a method of recording information using a reflectance or a phase change in a groove portion, and reading servo information by light.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic storage device which can simplify a head configuration and perform high-precision positioning as means for magnetically extracting a servo signal.

[Means for solving the problem]

 The above object can be achieved as follows.

A recording film on which ordinary data can be recorded is provided on the convex portion of the discrete medium, and is used as a data signal area. Servo information is recorded by providing a recording film also in the concave portion of the discrete medium and used as a servo area. Basically, reading of servo information and reading and writing of data are performed by one head. The servo information write current and the data write current may be different. In addition, the magnetic properties of the magnetic films of the protrusion and the recess may be different. Alternatively, the servo head and the data head may be two heads having different characteristics. The servo information may be written in advance when the medium is manufactured. The write frequency of the data signal area is set to be three times or more higher than the write frequency of the servo area.

Further, the magnetic storage device of the present invention incorporates a plurality of additional recording media having the above-described data recording and positioning servo information recording and a magnetic layer on at least one surface, and includes a plurality of magnetic heads corresponding to each surface. The magnetic heads are independently driven.

[Action]

If you want to read information from a given data track,
First, positioning and settling are performed based on the servo information of the medium concave portion. The data signal and the servo signal are frequency-separated, and at the time of following, the data signal and the servo signal are simultaneously extracted to separate each signal, and positioning at the time of track following and data reading are simultaneously performed.

When the recording medium is incorporated in the apparatus, the center of the track circle on the recording medium does not always coincide with the rotation center of the spindle mounted on the recording medium. On the other hand, since all magnetic heads are in a fixed positional relationship,
Since it is not possible to keep tracks on all recording media on-track at all times, individual actuators are added on the head mounting arms, and the magnetic heads are driven independently.

Further, in the present invention, a magnetic layer is provided on at least the surface of the convex portion and the bottom surface of the concave portion of the uneven shape regularly formed in the direction perpendicular to the direction of the recording information on the surface of the recording medium, and the recording data is written on the convex portion. Since the positioning servo information is recorded in the concave portion, the signal intensity of the servo information hardly deteriorates, and therefore, the accuracy of the servo information hardly deteriorates. Further, the data information and the servo information hardly magnetically cross each other, and each information is hardly deteriorated.

Further, in the present invention, the coercive force or the film thickness of the magnetic layer on the convex surface and the concave bottom is made different, so that the servo information is relatively easy to record, but the servo information is less affected by the data signal recording. Patterns can be provided. Also, since the formation accuracy of the servo information pattern is high and continuous servo information can be provided,
Suitable for high track density and large capacity magnetic recording devices.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional perspective view showing a basic shape of a discrete medium according to an embodiment of the present invention. A magnetic layer is provided on the convex portion formed on the medium surface along the recording medium information traveling direction indicated by the arrow, and is referred to as data tracks 1a, 1b, 1c, 1d. Further, a magnetic layer is provided on the bottom of the concave portion between the data tracks, and the tracks are used as servo tracks 2a, 2b, 2c, 2d. For example, when accessing data on the data track 1b, the magnetic head 3 has a gap width extending at least over a part of each of the servo tracks 2a and 2b. Each magnetic layer is formed on the medium substrate 4 in which a groove is formed in advance.

In FIG. 1, the track width _TW is, for example, 1 to 3
μm, pitch T _P is 2.5~5μm. Also, track / inch (TPI) is 5000 TPI or more (previously 2000 TPI) and bit / inch (BPI) is 60-100 aBPI (previously 30-40 kBP)
I).

2 and 3 are diagrams showing another embodiment of the method for forming a magnetic layer. FIG. 2 shows a magnetic layer uniformly formed on a groove formed on a substrate in advance. Third
In the figure, a magnetic layer for servo and a magnetic layer for data are formed at different heights on a flat substrate. The recording method of the data signal and the servo signal is the same as described above. The process of forming the above magnetic layer will be described later.

4 to 6 are diagrams showing the relationship between the track width of the magnetic head and the track pitch of the recording medium, respectively.

FIG. 4 is a view showing an example in which the head travels so as to include the servo areas 42a and 42b on both sides thereof so as to straddle one convex portion 41a. Width t ₁ in the track direction of the head corresponds to a width comprising a portion of one convex part and both sides of the recess. The servo signal records a one-phase dibit signal or a magnetic servo signal similar thereto. That is, the head 43 may be positioned so that the amplitudes of the servo signals 42a and 42b on both sides of the data track 41a are always the same. The head does not need to be settled on the data track 41a exactly as in the case of normal magnetic recording positioning, and there is room for positioning by the width of the grooves (recesses) 42a and 42b on both sides of the data track.

FIG. 5 shows that the head travels over a plurality of convex portions 51a, 51b, 51c. The width of the head 53 is determined by a plurality of protrusions and grooves (recesses) 52a, 52b, 52c, 52d on both sides thereof.
It is enough to cover ... Accordingly, the width t ₂ of the substantive data tracks will span multiple projections in the region which covers the head. As the servo signal, a one-phase or multi-phase dibit signal or a similar magnetic servo signal is recorded. FIG. 6 shows an example of a multi-phase case. Heads such as the positioning of the conventional magnetic recording, need not be settled exactly on a data track width t _2, there is positioned a margin of width of the sides of the groove of the data track (recess).

FIG. 7 and FIG. 8 are diagrams schematically showing the intensity of current when writing data and servo signals. In FIG. 7, when the write current I is plotted on the horizontal axis and the output E of the head is plotted on the vertical axis, a characteristic generally represented by a curve 71 is shown. When writing signals to the servo track, I ₂
Current value, in case of for example a thin film-type inductive head is to be written by flowing. 30mA to 40mA _0-P, when writing signal to the data track, the current value of I _1, for example a similar thin-film inductive head 10 when the write 20mA _0-P flowed, it can be seen that unchanged head output value E ₁ is both cases. In FIG. 8, when the write current I is plotted on the horizontal axis and the overwrite O / W (S / N) is plotted on the vertical axis, a characteristic generally represented by a curve 81 is shown. Similar to the above description, when writing signal to the servo track, writing the current value of I _2, when a signal is written to the data track, for writing a current value of I _1, overwriting of the servo track P _2, For example, the head has a size represented by 40 to 50 dB, while the overwrite amount in the data track is P ₁ , for example, 10 to 20 dB with the head. Here, since the data track does not exceed the specified overwrite amount P, for example, 30 dB in the above example, overwriting cannot be performed under this condition. However, since the data track is in the convex portion and is closer to the head than the servo track, If the distance of the step between the convex portion and the concave portion is appropriately set, the characteristic of the data track portion is actually represented by a curve 82 due to the spacing effect. Therefore, P _3> P becomes a current value I _1, is possible enough overwriting. Data tracks in Figure 7 when considering this case likewise the aforementioned step distance becomes as represented by the curve 72, the output value E ₁ of the head, a current value be I ₁
It does not change still be an I _2. Therefore, by appropriately setting the step difference between the medium concave and convex portions, in other words, the depth of the groove of the discrete medium and the head write current value, respectively,
It does not affect the servo signal when rewriting the data signal.

FIG. 9 shows another embodiment of the present invention. In general, the output of a perpendicular recording head largely depends on the distance between the recording medium and the head, that is, the spacing.
According to the combination of a T (single pole type) head and a two-layer film medium, the characteristics are as shown in FIG.
Here, the horizontal axis represents spacing, and the vertical axis represents generated magnetic field intensity. When writing on the medium using such a specific head, since the data track is closer to the head than the servo track, the magnitude of the magnetic field exerted on each track is H _y1 at the data track position, It becomes _Hy2 at the servo track position. Therefore, if _Hy1 and _Hy2 , that is, the spacings _hg1 and _hg2 are set as shown in this figure, the servo signal is less affected when the data signal is rewritten.

FIG. 10 is a diagram schematically showing the shapes and magnetic characteristics of a servo head and a data head when two types of heads, one for servo and one for data, are used. On the horizontal axis, the linear recording density D,
The vertical axis indicates the head gap length G or the saturation magnetic flux density Bs. Here, the linear recording density D corresponds to the recording and reproduction frequencies. Comparing the head for servo and the head for data, the gap length G is relatively large for servo 102 compared to data 101, or the saturation magnetic flux density Bs is relatively large for servo 104 compared to data 103, etc. Thereby, the characteristics of the embodiment of the present invention can be sufficiently satisfied.

FIG. 11 is a block diagram of a circuit for performing frequency separation between a servo signal and a data signal according to the embodiment of the present invention. When a data write signal is sent from 110, data is recorded on the medium from the head 111 via a servo notch filter and a high-pass filter. On the other hand, at the time of reading, the servo signal is reproduced as a servo signal 113 through a low-pass filter and a servo preamplifier. The data signal is reproduced as a data signal 112 through a high-pass filter and a data preamplifier.

When the head for writing and the head for reading are divided into two, it is possible to separate reading and writing by appropriately selecting the gap length and the saturation magnetic flux density of the head as described above. At this time, a data signal rewriting head having a small gap length and a small saturation magnetic flux density is used. The head for reading the data and the servo signal has a large gap length and a large saturation magnetic flux density, and the data signal and the servo signal are separated by the above-described frequency separation circuit.

FIG. 12 is a view for explaining still another embodiment of the present invention. When the linear recording density D is plotted on the horizontal axis and the output E of the medium is plotted on the vertical axis, the characteristic generally shown by a curve 121 is shown. For example, as a magnetic layer 124 of the data tracks on the medium protrusions, and chose coercivity Hc ₁ and thickness t _11, a curve 121. As the magnetic layer of the servo tracks on the medium recess, the coercive force Hc ₂ than the data tracks are small, or form what thickness t ₁₂ is larger properties (Hc _1> Hc ₂ or t
₁₁ <t _12). The magnetic layer 125 has a characteristic represented by a curve 122 in FIG. Since the servo track has a larger spacing than the data track, the output of the curve 122 as a whole is reduced in consideration of the spacing loss. If the output value of the magnetic layer of the data part and the output curve 121 of the magnetic layer of the servo part are overlapped with each other and the depth h of the recess or groove is set so that the output value overlaps with the output curve of the magnetic layer of the servo part, it is expressed as a curve 123 You. At this time, by setting the recording frequency of the data head, i.e. the linear recording density so that D _1, when the data signal rewriting the servo signals recorded in the medium is not affected. On the other hand, setting the recording frequency of the servo head, i.e. the linear recording density so that D _2. The servo signal and the data signal are separately extracted by the above-described frequency separation method. For example, as the magnetic layer 124 to form the convex portion, a large cobalt coercive force Hc ₁ - platinum-based, film thickness t ₁₁ is to put of about 500 Å. And the depth h of the groove to approximately 5000 Å, the magnetic layer 125 of the recess for example Co-Ni, etc. The film thickness t ₁₂ of 1000
The above-described characteristics can be obtained by forming {Å to several thousand}. 12
The coercive force Hc of No. 2 is relatively small (800 Oe), the saturation magnetic force Ms is relatively large, the coercive force Hc of 121 is relatively large (1500 Oe), and the saturation magnetic force Ms is relatively small.

FIG. 13 and FIG. 14 are diagrams for explaining a process of creating a discrete medium used in the present invention. No.
FIG. 13 shows a process for producing a desired medium based on a substrate on which track grooves have been formed in advance.
First, a medium substrate having a predetermined pitch is prepared, and a mask having the same pitch is prepared by a mask process (not shown). First, a magnetic layer 131 for a servo track is formed on the formed substrate 130 by vapor deposition, sputtering, or the like. This state is exactly the same as the configuration shown in FIG. A resist 132 is applied thereon by spin coating or the like. Then, exposure and development are performed using the above-mentioned mask, and unnecessary portions of the magnetic layer are removed by etching. Next, a magnetic layer 133 for a data track is formed thereon. Finally, when the resist 132 is removed, a medium having a desired configuration is obtained as shown in FIG.

FIG. 14 shows a process for producing a desired medium based on a flat substrate. First, a magnetic layer 135 for data tracks is formed on the flat substrate 134 by vapor deposition, sputtering, or the like. A resist 136 is applied thereon by spin coating or the like. Then, exposure and development are performed using the same mask as described above, and unnecessary portions of the magnetic layer are removed by etching.
Next, a servo track magnetic layer 137 is formed thereon. Finally, when the resist 136 is removed, a medium having a desired configuration is obtained as shown in FIG.

Before incorporating the created discrete media into the device,
It is also possible to perform servo track writing by a dedicated device for each medium as one of the disk creation processes.

FIG. 15 is a diagram showing an embodiment as an apparatus of the present invention. The magnetic disk media 151a, 151b, 151c,... Are assembled in a laminated structure as described in FIG. 1 and others, are mounted on a spindle 155, and are driven to rotate at a predetermined rotation speed by a spindle motor 156. 152a-1, 152a-
Reference numerals 2, 152b-1, 152b-2,... Are magnetic heads for accessing the disk medium, respectively, and are connected to the carriage 153. The magnetic head is shown in the previous embodiment,
A magnetic head for both data and servo, or a magnetic head for data, servo individually, or read / write
It is mounted on one slider that floats in the air.
The carriage is connected to a VCM (voice coil motor) 154 and drives the head in the radial direction of the disk.
The above-described components, including the circuit and the like, are housed in the housing 157 and are sealed so that external dust does not enter.

When a recording medium is manufactured by the above process, the center of the track circle on the recording medium surface does not always coincide with the rotation center of the spindle when the recording medium is assembled into the apparatus.
On the other hand, since all the magnetic heads have a fixed positional relationship, it is impossible to always keep tracks on all recording medium surfaces on-track. This is an important concept for increasing the throughput as a concept of a cylinder, and in order to realize this, it is necessary to add individual actuators 158a, 158b,.

〔The invention's effect〕

According to the present invention, on a recording medium surface, a magnetic layer is provided on at least a convex surface and a concave bottom surface of an irregular shape regularly formed in a direction perpendicular to a traveling direction of recording information, and recording data is recorded on the convex portion. Since the positioning servo information is recorded in the concave portion, the signal intensity of the servo information hardly deteriorates, and therefore, the accuracy of the servo information hardly deteriorates. Further, the data information and the servo information hardly magnetically cross each other, and each information is hardly deteriorated. In addition, since the coercive force or the film thickness of the magnetic layer on the surface of the convex portion and the bottom surface of the concave portion are made different, it is possible to provide a servo information pattern which is relatively easy to record servo information but is less affected by when recording data signals. be able to. Further, since the servo information pattern can be formed with high accuracy and continuous servo information can be provided, it is suitable for increasing the track density and increasing the capacity of the magnetic recording apparatus. In addition, the head positioning of the device using the discrete medium can be accurately performed with almost the same concept as the conventional method of positioning using a servo disk and a servo head and with a simple head configuration. This greatly contributes to improving the performance of magnetic recording and reproducing devices such as magnetic disk devices, magnetic tape devices, and magnetic card devices aiming at high track density in the future.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an embodiment of the present invention, FIGS. 2 and 3 are diagrams schematically showing different configurations of the above embodiment, and FIGS. 4 to 6. Is a diagram schematically showing the relationship between the track pitch and the head width in the present invention, FIG. 7 is a diagram showing the relationship between the write current of the head and the output, and FIG. 8 is the write current of the head and the overwrite amount. FIG. 9 shows the relationship between vertical head spacing and magnetic field strength, and FIG. 10 shows the relationship between head gap length and saturation magnetic flux density and linear recording density. Figure, No.
FIG. 11 is a circuit diagram for separating the frequency of a servo signal and a data signal, FIG. 12 is a diagram showing a relationship between a linear recording density and an output of a magnetic medium, and FIGS. 13 to 14 are discrete circuits of the present invention. FIG. 15 is a diagram for explaining the process of creating a medium, and FIG. 15 is a diagram showing an embodiment of the magnetic recording disk device of the present invention. 1a, 1b, 1c, 1d ... Data track 2a, 2b, 2c, 2d ... Servo track 3 ... Head 4 ... Board, 41a, 41b, 41c ... Data Tracks 42a, 42b, 42c, 42d Servo track 43 Heads 51a, 51b, 51c Data tracks 52a, 52b, 52c, 52d Servo track 53 Head 111 Head 112 Data signal 113 Servo signal 124 Data track 132 Servo track 130, 134 Substrate 131, 137 Servo magnetic layer 132, 136 Resist 133, 135 Data magnetic layer 151a, 151b , 151c ... magnetic disk medium 155 ... spindle 156 ... spindle motor 152a-1, 152a-2, 152b-1, 152b-2 ... magnetic head 153 ... carriage 154 ... VCM ( Voice coil motor) 157 ... Housing 158a, 158b ... Actuator

──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshinori Miyamura 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Inside the Central Research Laboratory (72) Inventor Yoshifumi Matsuda 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Mikio Suzuki 1-280 Higashi-Koikekubo, Kokubunji-shi, Tokyo (72) Inventor Takeshi Nakao 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Takayuki Munemoto 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref. Person Hirotsugu Fukuoka 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture (72) Inventor Makoto Aihara 4026 Kuji-cho, Hitachi City, Ibaraki Pref. Hitachi Research Laboratory, Ltd. (56) References JP-A-1-113913 (JP, A) JP-A-61- 24021 (JP, A) JP-A-62-298016 (JP, A) JP-A-62-256225 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5/596

Claims (12)

(57) [Claims] 1. An apparatus for positioning a discrete medium using an information recording file for reading or writing information recorded on a recording medium by using a converting means, wherein the recorded information is recorded on the surface of the recording medium. In the uneven shape regularly formed in the direction perpendicular to the direction of travel, a magnetic layer is provided on at least the convex surface and the concave bottom, recording data on the convex, recording positioning servo information on the concave, and A magnetic storage device, wherein the coercive force or the film thickness of the magnetic layer on the surface of the convex portion and the magnetic layer on the bottom surface of the concave portion are different. 2. The recording data section records a signal having a frequency of at least 1 MHz, and the positioning servo information recording section records a signal having a frequency of at least 0.4 MHz or less. Magnetic storage device. 3. An apparatus for positioning a discrete medium using an information recording file in which information recorded on a recording medium is read or written using a conversion means, wherein the positioning is performed in a direction orthogonal to the direction of travel of the recorded information. A magnetic layer is provided at the bottom of grooves regularly formed on the surface of the recording medium and at the top between the grooves, and the coercive force of the magnetic layer at the bottom is smaller than the coercive force of the magnetic layer at the top. Alternatively, the thickness of the bottom magnetic layer is larger than the thickness of the top magnetic layer, and the positioning servo information signal area magnetically recorded at a low frequency on the bottom, and a high frequency magnetic signal on the top. And a data signal area recorded in the data storage area, and simultaneously reads the servo information signal and the data signal, and performs positioning and data reading / writing. 4. The magnetic storage device according to claim 1, wherein one track width includes one data signal area and two positioning servo information signal areas on both sides of the data signal area. 5. A single track width includes a plurality of data signal areas and a plurality of positioning servo information signal areas between and at both ends thereof.
4. The magnetic storage device according to 2 or 3. 6. The head according to claim 1, wherein a vertical recording head or an in-plane recording head is used as one conversion element for both servo and data. Magnetic storage device. 7. Using two types of conversion elements for data and servo supported by the same slider, writing servo information by the conversion element for servo to the extent that the servo information is not erased when data is rewritten by the conversion element for data. 6. The magnetic storage device according to claim 1, wherein the current is sufficiently larger than the current for writing data information. 8. Using two types of conversion elements for data and servo supported on the same slider, the magnetic characteristics of the conversion element material for the servo or the structure of the conversion element are changed to the magnetic characteristics or conversion characteristics of the conversion element material for data. 8. The magnetic storage device according to claim 1, wherein the magnetic storage device has a structure different from that of the element. 9. A read conversion element using two types of conversion elements for writing and reading supported by the same slider, wherein the writing conversion element has a magnetic characteristic or structure such that only data information can be rewritten. Has a magnetic characteristic or structure that allows both servo information and data information to be read out.
9. The magnetic storage device according to 5, 7, or 8. 10. The magnetic property or structure of the magnetic layer at the bottom of the concave portion or the groove and the magnetic layer at the top between the convex portion or the groove are different from each other. 10. The magnetic storage device according to 3, 4, 5, 6, 7, 8, or 9. 11. The servo information to be recorded is written in advance into the concave portion or the bottom of the groove before assembling the recording medium into the apparatus.
11. The magnetic storage device according to 4, 5, 6, 7, 8, 9, or 10. 12. A plurality of recording media having at least one magnetic layer for recording data and recording servo information on at least one surface thereof, and a plurality of magnetic heads corresponding to the respective surfaces. 12. The magnetic storage device according to claim 1, wherein the magnetic storage device is driven independently.