Patent Application
20090268595
1. Field of the Invention
The present invention relates to an information recording medium on which servo patterns, where recording regions and non-recording regions are disposed corresponding to servo data, are formed in servo pattern regions, and to a recording/reproducing apparatus equipped with such information recording medium.
2. Description of the Related Art
As one example of this type of information recording medium, Japanese Laid-Open Patent Publication No. 2006-40354 discloses a patterned disk medium (hereinafter simply “magnetic disk”) where servo pattern portions are physically formed by the presence or absence of magnetic bodies and a magnetic disk drive equipped with such magnetic disk. When manufacturing such magnetic disk, first a pattern lithography process, a developing process, an electroforming process, and the like are carried out in the mentioned order to fabricate a stamper, a mask to be used during an etching process is then formed by imprinting using such stamper, and then a preform for manufacturing a magnetic disk is etched.
More specifically, first a matrix (a substrate used to fabricate a stamper) on which a resist has been applied is set in an electron beam exposing apparatus and regions corresponding to non-magnetized parts of the magnetic disk (i.e., regions corresponding to concaves in a concave/convex pattern to be formed in a magnetic layer on a magnetic disk) are irradiated with an electron beam. By doing so, a concave forming pattern is drawn on the resist layer on the matrix. Next, the matrix for which the drawing of the concave forming pattern on the resist layer has been completed is subjected to a developing process to remove the resist layer at parts irradiated with the electron beam from the matrix. By doing so, the parts where the resist layer is removed become concaves, thereby forming a concave/convex pattern in the resist layer. After this, a concave/convex pattern is formed in the matrix by an etching process that uses the formed concave/convex pattern as a mask. After the formation of the concave/convex pattern is complete, the matrix is made electrically conductive, and then by carrying out an electroforming process, the concave/convex pattern of the matrix is transferred to an electroforming material (i.e., nickel). Next, the nickel layer is separated from the matrix and is punched out (cut out) into a predetermined shape to complete a disk-shaped nickel stamper.
After this, a preform for manufacturing a magnetic disk and the stamper that has been fabricated are set in an imprinting apparatus and the concave/convex pattern of the stamper is transferred to a resist layer formed on the preform. Next, an ion milling process is carried out on a magnetic layer of the preform with the resist to which the concave/convex pattern has been transferred as a mask (guard layer). At this time, the magnetic layer at parts exposed from the layer of resist used as the mask (i.e., at the base surfaces of the concaves in the concave/convex pattern) is removed, thereby forming a desired concave/convex pattern in the magnetic layer. Next, after the resist layer used as a mask has been removed, a non-magnetic material is sputtered. After this, the layer of the non-magnetic material is reverse-sputtered until the surface of the magnetic layer is exposed from the layer of non-magnetic material. By doing so, the surface of the magnetic disk is smoothed. After this, by carrying out a process that forms a DLC protective layer and a process that applies a lubricant, the magnetic disk is completed.
On the other hand, by investigating the conventional magnetic disk described above, the present inventors found the following problem. More specifically, as shown in
On the other hand, to respond to demands for information recording media to be smaller and have a higher recording density, it is necessary on current magnetic disks to make the formation pitch in the direction of rotation (in the example described above, the pitch Px or the like) of the convexes 25ax and the concaves 25bx described above much smaller. Accordingly, when fabricating a stamper used to manufacture this type of magnetic disk, it is necessary to make the pitch in the direction of rotation of regions corresponding to the convexes 25ax and the concaves 25bx described above much smaller. For this reason, as shown in
In this case, as described earlier, when etching a matrix using a concave/convex pattern formed in a resist layer on the matrix as a mask, not only the matrix but also the resist layer used as the mask (that is, the convexes of the concave/convex pattern) will be etched. Accordingly, since the convexes in the concave/convex pattern used as the mask pattern become gradually narrower as the etching process progresses (that is, the length along the direction of rotation and/or the length along the radial direction become shorter), to form concaves of the desired width (i.e., concaves with openings of the desired size) in the matrix, it is necessary to make the width (length) of the convexes of the concave/convex pattern formed on the resist layer on the matrix quite wide (long). When, the drawing of the concave forming pattern Epz described above has been completed and, as described earlier, the parts irradiated with the electron beam have been removed from the matrix by a developing process to form a concave/convex pattern (mask pattern) on the matrix, if the width of the convexes in the concave/convex pattern is narrow (that is, if the length of the convexes in a direction corresponding to the direction of rotation of the magnetic disk is short), there will be the risk of damage or loss of the convexes during the period from the completion of the developing process to the formation of the concave/convex pattern in the matrix by the etching process, so that the convexes will not function sufficiently as a mask during the etching of the matrix. Accordingly, when drawing the concave forming pattern Epz described above during the manufacturing of a stamper for manufacturing this type of magnetic disk, it is necessary to set the length L4z of the regions irradiated with the electron beam (i.e., the length in the direction corresponding to the direction of rotation of the magnetic disk) sufficiently short to avoid a situation where the length along the direction of rotation of the convexes formed after the developing process become excessively short.
For this reason, when drawing the concave forming pattern Epz described above, as shown by the arrow Z1z in
Accordingly, when convexes with a sufficient length to function as a mask are formed while sufficiently reducing the pitch Pez at which the electron beam is irradiated during the manufacturing of a stamper, on a magnetic disk 10z manufactured using a stamper manufactured in accordance with this method, positions where the convexes 25az are continuous for the length L11z in the direction of rotation will be produced inside the preamble pattern region Apz. Here, as shown in
This means that on the magnetic disk 10z on which the convex parts 25az of the length L11z are formed inside the preamble pattern region Apz as described above, there is the risk that the convexes 25az of the length L11z will be erroneously detected as the convexes 25az of the length L3z, for example, inside the servo address mark region Amz, which makes it difficult to carry out tracking servo control correctly.
More specifically, for the magnetic disk 10z described above where the length along the direction of rotation of the convexes 25az inside the preamble pattern region Apz is the length L11z, during recording and reproducing there are cases where the control unit erroneously judges that a read of servo data from the servo address mark region Amz has started (that is, the read of the servo data from the preamble pattern region Apz has ended) based on the signal outputted from the magnetic head when a convex 25az of the length L11z has passed below the magnetic head due to rotation of the magnetic disk 10z. When such erroneous judgment occurs, even though the signal outputted from the magnetic head when the convexes 25az that are formed next to the convex 25az with the length L11z and are indicated by the arrows Z3z, Z4z passes below the magnetic head actually forms part of the preamble signal read from the preamble pattern region Apz, the signal will be erroneously identified as some of the servo address marks read from the servo address mark region Amz, resulting in a read error occurring for the servo data.
In this way, the present inventors found that if the formation pitch of the convexes 25az that construct the servo patterns in the servo pattern regions Asz (such as the preamble pattern inside the preamble pattern region Apz) is made sufficiently smaller when manufacturing a magnetic disk, there will be positions where the amount of irradiation with an electron beam (that is, the amount of exposure for the resist) is insufficient when drawing a concave forming pattern Epz during the fabrication of a stamper for manufacturing such magnetic disk, and as a result, convexes 25az that are supposed to be formed independently end up being connected in the direction of rotation. This means that when the recording density of a magnetic disk is increased, it becomes difficult to read the servo data from the servo pattern regions Asz, resulting in the problem that tracking servo control errors may occur.
The present invention was conceived in view of the problem described above and it is a principal object of the present invention to provide an information recording medium where the recording density can be increased while still ensuring that the servo data can be correctly read and a recording/reproducing apparatus equipped with such information recording apparatus.
To achieve the stated object, on an information recording medium according to the present invention, servo patterns, in which recording regions and non-recording regions are disposed corresponding to servo data, are formed in servo pattern regions, and the information recording medium includes: a first region where first recording regions that are long in a radial direction of the information recording medium are disposed at a predetermined pitch with first non-recording regions in between in a preamble pattern region provided in each servo pattern region; and a second recording region that connects the first recording regions that are adjacent in a direction of rotation of the information recording medium, the second recording region being provided in the first region, wherein a second non-recording region is provided at a position that is adjacent in the direction of rotation to the first region and where a read of the servo data is carried out following the first region, and a length of the second non-recording region is longer in the direction of rotation than a length in the direction of rotation of the first non-recording regions at corresponding same-pattern-radius positions.
In this specification, data read when a servo pattern region passes below a magnetic head during the recording or reproducing of data on an information recording medium (that is, data corresponding to recording regions and non-recording regions inside a servo pattern region) is all defined as “servo data”. The expression “recording regions” in the present specification refers to regions that are constructed so as to hold a recorded magnetic signal in a readable manner (that is, regions constructed so as to have the ability to hold a magnetic signal in a readable manner). Similarly, the expression “non-recording regions” in the present specification refers to regions that are constructed so that an ability thereof to hold a magnetic signal in a readable manner is lower than that of the recording regions, or regions constructed so as not to effectively have such ability. More specifically, the expression “non-recording regions” in the present specification refers to regions that emit a smaller magnetic field than the recording regions described above in a state where a magnetic signal has been recorded, or regions that effectively do not emit a magnetic field. In addition, the expression “first region” in the present specification refers to a region that is long in the radial direction and extends from a position of a first recording region at one end in the direction of rotation out of the first recording regions disposed at a predetermined pitch inside the preamble pattern region (for example, from a position of a first recording region at the end where the first servo data is read during a read of servo data from the preamble pattern region) to a position of a first recording region at the other end in the direction of rotation (for example, to a position of a first recording region at the end where the last servo data is read during a read of servo data from the preamble pattern region).
A recording/reproducing apparatus according to the present invention includes: the information recording medium described above; a magnetic head that reads the servo data from the servo pattern regions; and a control unit that carries out tracking servo control based on the read servo data.
For the information recording medium and the recording/reproducing apparatus described above, the second non-recording region is provided at a position that is adjacent in the direction of rotation to the first region on the information recording medium and where a read of the servo data is carried out following the first region. Therefore, according to this information recording medium and recording/reproducing apparatus, when manufacturing an information recording medium where the formation pitch of the recording regions inside the servo pattern regions is sufficiently reduced to increase the recording density, even if the irradiation amount of the beam used for lithography (an electron beam or the like) at a position corresponding to a first non-recording region inside the first region of the information recording medium is insufficient when drawing a concave forming pattern used to manufacture a stamper, resulting in a state where plural first recording regions inside the first region become connected via a second recording region, it will still be possible to avoid a situation where it is erroneously judged, based on the servo data read when a position where the first recording regions are connected via the second recording region (i.e., a position where the length in the direction of rotation of the recording regions that are continuous in the direction of rotation inside the first region is longer than the length in the direction of rotation of one first recording region) passes below the magnetic head, that a read of the preamble pattern from the preamble pattern region has ended.
Also, on the recording/reproducing apparatus according to the present invention, the control unit in the recording/reproducing apparatus described above judges that a read of preamble data in the servo data has ended when the servo data corresponding to the second non-recording region is read by the magnetic head. Therefore, according to this recording/reproducing apparatus, even when plural first recording regions become connected via a second recording region due to the formation pitch of the recording regions inside the preamble pattern region being sufficiently reduced to increase the recording density, it will still be possible to correctly read the various servo data from the servo pattern regions and as a result it will be possible to reliably avoid a situation where tracking servo control errors occur. Here, the expression “when the servo data corresponding to the second non-recording region is read” includes “when plural servo data including the servo data corresponding to the second non-recording region are read”. More specifically, the present invention includes a construction where it is judged, when the servo data corresponding to the second non-recording region and servo data corresponding to recording regions and non-recording regions that are formed so as to be aligned with the second non-recording region are read, that the read of the preamble data ends immediately preceding the time at which the servo data corresponding to the second non-recording region is read.
On the information recording medium according to the present invention, the second non-recording region may be provided at one of: a position where a read of the servo data in the preamble pattern region is carried out last; and a position that is adjacent in the direction of rotation to the preamble pattern region and where a read of the servo data is carried out following the servo data inside the preamble pattern region. Accordingly, unlike a construction where the second non-recording region is provided far from the preamble pattern region, there will be no recording regions or non-recording regions where servo data is recorded present between (i) the preamble pattern region where a second recording region that connects first recording regions is likely to occur during manufacturing and (ii) the second non-recording region. This means that it is possible to reliably read the servo data from the region in which the servo data is recorded following the region (i.e., the preamble pattern region) in which the recording regions and the non-recording regions for the preamble pattern are disposed.
In addition, on the information recording medium according to the present invention, the length in the direction of rotation of the second non-recording region may be equal to or longer than the predetermined pitch at same-pattern-radius positions. Therefore, according to this information recording medium, compared to an information recording medium where the length in the direction of rotation of: the second non-recording region is only slightly longer than the length in the direction of rotation of the first non-recording regions, the time required for the second non-recording region to pass below the magnetic head will be sufficiently long, and therefore it will be possible to reliably detect the signal when the second non-recording region passes below the magnetic head. In this way, according to this information recording medium, it is possible to reliably avoid a situation where it is erroneously judged, based on the servo data read when a position where the first recording regions are connected via a second recording region passes below the magnetic head, that a read of the preamble pattern from the preamble pattern region has ended.
In addition, on the information recording medium according to the present invention, the length in the direction of rotation of the second non-recording region may be a length that is N times the length in the direction of rotation of the first non-recording regions at corresponding same-pattern-radius positions, where N is a natural number of 2 or higher. Therefore, according to this information recording medium, unlike a construction where the length in the direction of rotation of the second non-recording region is set at a non-natural number multiple (such as 1.5 times) the length in the direction of rotation of the first non-recording regions used in the preamble pattern at same-pattern-radius positions, it will be possible to read the servo data from the entire servo pattern region without having to switch between plural reference clocks to read the servo data from the servo pattern region. By doing so, according to this information recording medium, it is possible not only to easily carry out tracking servo control but also to sufficiently lower the manufacturing cost of a recording/reproducing apparatus equipped with the information recording medium by an amount corresponding to it being no longer necessary to use control data of a complex data structure.
On the information recording medium according to the present invention, servo patterns, in which recording regions and non-recording regions are disposed corresponding to servo data, are formed in servo pattern regions, and the information recording medium includes: a second region where third non-recording regions that are long in a radial direction of the information recording medium are disposed at a predetermined pitch with third recording regions in between in a preamble pattern region provided in each servo pattern region; and a fourth non-recording region that connects the third non-recording regions that are adjacent in the direction of rotation of the information recording medium, the fourth non-recording region being provided in the second region, wherein a fourth recording region is provided at a position that is adjacent in the direction of rotation to the second region and where a read of the servo data is carried out following the second region, and a length in the direction of rotation of the fourth recording region is longer than a length in the direction of rotation of the third recording regions at corresponding same-pattern-radius positions.
In this case, the expression “second region” in the present specification refers to a region that is long in the radial direction and extends from a position of a third non-recording region at one end in the direction of rotation out of the third non-recording regions disposed at a predetermined pitch inside the preamble pattern region (for example, from a position of a third non-recording region at the end where the first servo data is read during a read of servo data from the preamble pattern region) to a position of a third non-recording region at the other end in the direction of rotation (for example, to a position of a third non-recording region at the end where the last servo data is read during a read of servo data from the preamble pattern region).
A recording/reproducing apparatus according to the present invention includes: the information recording medium described above; a magnetic head that reads the servo data from the servo pattern regions; and a control unit that carries out tracking servo control based on the read servo data.
For the information recording medium and the recording/reproducing apparatus described above, the fourth recording region is provided at a position that is adjacent in the direction of rotation to the second region on the information recording medium and where a read of the servo data is carried out following the second region. Therefore, according to this information recording medium and recording/reproducing apparatus, when manufacturing an information recording medium where the formation pitch of the non-recording regions inside the servo pattern regions is sufficiently reduced to increase the recording density, even if the irradiation amount of the beam used for lithography (an electron beam or the like) at a position corresponding to a third recording region inside the second region of the information recording medium is insufficient when drawing a concave forming pattern used to manufacture a stamper, resulting in a state where plural third non-recording regions inside the second region become connected via a fourth non-recording region, it will still be possible to avoid a situation where it is erroneously judged, based on the servo data read when a position where the third non-recording regions are connected via the fourth non-recording region (i.e., a position where the length in the direction of rotation of the non-recording regions that are continuous in the direction of rotation inside the second region is longer than the length in the direction of rotation of one third non-recording region) passes below the magnetic head, that a read of the preamble pattern from the preamble pattern region has ended.
Also, on the recording/reproducing apparatus according to the present invention, the control unit in the recording/reproducing apparatus described above judges that a read of preamble data in the servo data has ended when the servo data corresponding to the fourth recording region is read by the magnetic head. Therefore, according to this recording/reproducing apparatus, even when plural third non-recording regions become connected via a fourth non-recording region due to the formation pitch of the non-recording regions inside the preamble pattern region being sufficiently reduced to increase the recording density, it will still be possible to correctly read the various servo data from the servo pattern regions and as a result it will be possible to reliably avoid a situation where tracking servo control errors occur. Here, the expression “when the servo data corresponding to the fourth recording region is read” includes “when plural servo data including the servo data corresponding to the fourth non-recording region are read”. More specifically, the present invention includes a construction where it is judged, when the servo data corresponding to the fourth recording region and servo data corresponding to non-recording regions and recording regions that are formed so as to be aligned with the fourth recording region are read, that the read of the preamble data ends immediately preceding the time at which the servo data corresponding to the fourth recording region is read.
On the information recording medium according to the present invention, the fourth recording region may be provided at one of: a position where a read of the servo data in the preamble pattern region is carried out last; and a position that is adjacent in the direction of rotation to the preamble pattern region and where a read of the servo data is carried out following the servo data inside the preamble pattern region. Accordingly, unlike a construction where the fourth recording region is provided far from the preamble pattern region, there will be no recording regions or non-recording regions where servo data is recorded present between (i) the preamble pattern region where a fourth non-recording region that connects third non-recording regions is likely to occur during manufacturing and (ii) the fourth recording region. This means that it is possible to reliably read the servo data from the region in which the servo data is recorded following the region (i.e., the preamble pattern region) in which the recording regions and the non-recording regions for the preamble pattern are disposed.
In addition, on the information recording medium according to the present invention, a length in the direction of rotation of the fourth recording region may be equal to or longer than the predetermined pitch at same-pattern-radius positions.
Therefore, according to this information recording medium, compared to an information recording medium where the length in the direction of rotation of the fourth recording region is only slightly longer than the length in the direction of rotation of the third recording regions, the time required for the fourth recording region to pass below the magnetic head will be sufficiently long, and therefore it will be possible to reliably detect the signal when the fourth recording region passes below the magnetic head. In this way, according to this information recording medium, it is possible to reliably avoid a situation where it is erroneously judged, based on the servo data read when a position where the third non-recording regions are connected via a fourth non-recording region passes below the magnetic head, that a read of the preamble pattern from the preamble pattern region has ended.
In addition, on the information recording medium according to the present invention, a length in the direction of rotation of the fourth recording region may be a length that is N times the length in the direction of rotation of the third recording regions at corresponding same-pattern-radius positions, where N is a natural number of 2 or higher. Therefore, according to this information recording medium, unlike a construction where the length in the direction of rotation of the fourth recording region is set at a non-natural number multiple (such as 1.5 times) the length in the direction of rotation of the third recording regions used in the preamble pattern at same-pattern-radius positions, it will be possible to read the servo data from the entire servo pattern region without having to switch between plural reference clocks to read the servo data from the servo pattern region. By doing so, according to this information recording medium, it is possible not only to easily carry out tracking servo control but also to sufficiently lower the manufacturing cost of a recording/reproducing apparatus equipped with the information recording medium by an amount corresponding to it being no longer necessary to use control data of a complex data structure.
These and other objects and features of the present invention will be explained in more detail below with reference to the attached drawings, wherein:
Preferred embodiments of an information recording medium and a recording/reproducing apparatus according to the present invention will now be described with reference to the attached drawings.
First, the construction of a recording/reproducing apparatus according to the present invention will be described with reference to the drawings.
A hard disk drive 1 shown in
The motor 2 rotates the magnetic disk 10A at a constant velocity, for example 4200 rpm, in accordance with control by the control unit 6. The controller 2a rotates the motor 2 in accordance with a control signal S4 outputted from the control unit 6. Out of the magnetic heads 3, one magnetic head 3 is disposed facing one surface (the upper surface in
Note that although the magnetic heads 3 are each actually constructed by forming a recording element and a reproducing element on the base surface (i.e., air bearing surface) of a slider for causing the magnetic head 3 to fly above the magnetic disk 10A, the sliders, the recording elements, the reproducing elements, and the like are omitted from the description and drawings. According to a driving current supplied from the driver 5 under the control of the control unit 6, the actuator 3b swings the swing arms 3a to move the magnetic heads 3 to a freely chosen recording/reproducing position above the magnetic disk 10A. The detector unit 4a extracts servo data from an output signal S0 (analog signal: servo signal) outputted from the magnetic heads 3 to generate a detection signal S1, and outputs the generated detection signal S1 to the control unit 6. During the recording of data on the magnetic disk 10A, the power supply unit 4b supplies an AC voltage whose potential is reversed at predetermined periods to the magnetic heads 3 in accordance with a control signal S2 outputted from the control unit 6. The driver 5 controls the actuator 3b in accordance with a control signal S3 outputted from the control unit 6 to make the magnetic heads 3 on-track to desired data recording tracks.
The control unit 6 is one example of a “control unit” for the present invention and carries out overall control over the hard disk drive 1. Also, based on the detection signal (servo data) S1 outputted from the detector unit 4a and control data D stored in the storage unit 7, the control unit 6 controls the controller 2a, the power supply unit 4b, and the driver 5 (i.e., the control unit 6 carries out a tracking servo control process and a recording/reproducing process for data). The storage unit 7 stores the control data D mentioned above and the like.
On the other hand, the magnetic disk 10A is installed inside the case of the hard disk drive 1 together with the motor 2, the magnetic heads 3, and the like. As shown in
In this case, on the magnetic disk 10A, formation regions of the convexes 25a correspond to “recording regions” for the present invention and formation regions of the concaves 25b correspond to “non-recording regions” for the present invention. In addition, on the magnetic disk 10A, a protective layer 16 (a DLC film) with a thickness of around 4 nm is formed of diamond-like carbon (DLC) or the like so as to cover the surface of the non-magnetic material 15 filled in the concaves 25b (i.e., filled between the adjacent convexes 25a) and the surface of the magnetic layer 14 (the convexes 25a) on both surfaces of the magnetic disk 10A. A lubricant is also applied onto the surfaces of both protective layers 16 to prevent damage to both the magnetic heads 3 and the magnetic disk 10A.
The glass substrate 11 is formed in a circular plate shape with a thickness of around 0.6 mm by polishing the surface of a glass plate, for example. Note that the base plate used when forming the magnetic disk 10A is not limited to a glass substrate and it is possible to use a base plate formed in a circular plate shape using various types of non-magnetic material such as aluminum and ceramics. On each surface, the soft magnetic layer 12 is formed in a thin film shape with a thickness of around 20 nm to 200 nm, inclusive by sputtering a soft magnetic material such as CoZrNb alloy. The intermediate layer 13 functions as an underlayer for forming the magnetic layer 14 and is formed in a thin film shape with a thickness of around 5 nm to 40 nm by sputtering an intermediate layer forming material such as Ru, Cr or a non-magnetic CoCr alloy. As described earlier, the magnetic layer 14 is a layer that constructs the concave/convex pattern 25 (the data track patterns 25t and the servo patterns 25s shown in
As shown in
The hard disk drive 1 equipped with the magnetic disk 10A is constructed so that the magnetic disk 10A is rotated at a fixed angular velocity by the motor 2 in accordance with control by the control unit 6 as described earlier. Accordingly, as shown in
Also, as shown in
On the other hand, in each servo pattern region As, plural regions are aligned in the direction of rotation, and concave/convex patterns 25 (the servo patterns 25s) with plural convexes 25a and plural concaves 25b that construct various servo patterns for tracking servo control are formed inside such regions. More specifically, as shown in
In the preamble pattern region Ap, preamble patterns for correcting a reference clock for reading a variety of control signals from the servo address mark region Am, the address pattern region Aa, and the like in accordance with a rotational state (i.e., the rotational velocity) of the magnetic disk 10A and for adjusting the gain of the output of the servo data and user data (i.e., data recorded on data recording tracks) are formed. In this case, on the magnetic disk 10A, the entire preamble pattern region Ap constructs a “first region” for the present invention and the convexes 25a and the concaves 25b are alternately disposed in accordance with a preamble signal as servo data between a leading end and a trailing end of the preamble pattern region Ap in the direction of rotation. More specifically, as shown in
In this case, as shown in
On the magnetic disk 10A, the convexes 25a of the length L1a and the concaves 25b of the length L2a described above are formed so as to be alternately disposed up to a servo address mark region Am end of the preamble pattern region Ap, and a convex 25a of the length L1a described above that corresponds to a “first recording region” for the present invention is formed at the servo address mark region Am end of the preamble pattern region Ap. In addition, on the magnetic disk 10A, the convexes 25a inside the preamble pattern region Ap are formed as described above at the extremely narrow pitch Pa. This means that for the magnetic disk 10A, as described later, during manufacturing, at some positions inside the preamble pattern region Ap, a connecting portion 25c is formed by a convex 25a (one example of a “second recording region” for the present invention) so that convexes 25a that are adjacent in the direction of rotation become connected in the direction of rotation. In this case, as described above, since the length L1a of the convexes 25a at a position where the distance from the center O of the data track patterns 25t is 15 mm is 55 nm and the length L2a of the concaves 25b is 55 nm, when the connecting portion 25c described above is formed at a position where the distance from the center O is 15 mm, the length L11a where convexes 25a are continuous along the direction of rotation is 165 nm.
Servo address marks for specifying a read start position of an address pattern is formed in the servo address mark region Am. Also, the magnetic disk 10A uses a construction where a concave 25b that corresponds to a “second non-recording region” for the present invention is formed at a front region of the servo address mark region Am (i.e., the preamble pattern region Ap end in the direction of rotation: one example of a “position where a read of servo data is carried out following the servo data inside the preamble pattern region” for the present invention), with such concave 25b being used to identify the end of a read of a preamble pattern from the preamble pattern region Ap. In this case, as one example, the length L3a of the concave 25b that corresponds to the “second non-recording region” for the present invention at a position where the distance from the center O of the data track patterns 25t is 15 mm is set at 110 nm that is equal to the pitch Pa described above and twice the length L2a of the concaves 25b inside the preamble pattern region Ap described above (one example where “N times” for the present invention is “twice”).
As shown in
Next, a method of manufacturing the magnetic disk 10A will be described with reference to the drawings.
When manufacturing the magnetic disk 10A described above, first a stamper 60 (see
Note that the arrow R2 shown in
Here, when drawing the concave forming pattern Ep for manufacturing the magnetic disk 10A or the like, as described earlier, it is necessary to set the length L4a of the regions irradiated with the electron beam EB sufficiently short to avoid a situation where the length along the direction of rotation of the convexes formed on the B1 mask forming layer 33 after the developing process is excessively short. This means that as shown by the arrow Z1 in
Next, the developing process is carried out on the B1 mask forming layer 33 for which the drawing of the concave forming pattern Ep has been completed. By doing so, the B1 mask forming layer 33 is removed from above the A1 mask forming layer 32 in elimination regions where the amount of irradiation with the electron beam EB reached a resist-layer-elimination level during the lithography process of the concave forming pattern Ep by the pattern lithography apparatus, and as shown in
After this, by carrying out an etching process using the B1 mask forming layer 33 (i.e., the convexes 35a of the concave/convex pattern 35) for which the drying process has been completed as a mask, the A1 mask forming layer 32 that is exposed from the B1 mask forming layer 33 is removed from above the silicon substrate 31 at the base surfaces of the concaves 35b. By doing so, as shown in
Next, after a nickel layer (conductive layer) 41 has been formed by a vapor deposition process, for example, on the surface of the concave/convex pattern 37 as shown in
More specifically, as one example, a nickel layer 51 (see
Next, the magnetic disk 10A is manufactured using the manufactured stamper 60. When doing so, as one example, first a preform 80 (see
Next, after the resin material remaining at the base surfaces of the concaves 85b of the concave/convex pattern 85 transferred to the B2 mask forming layer 82 has been removed by an etching process, another etching process is carried out on the A2 mask forming layer 81 using the concave/convex pattern 85 as a mask. By doing so, as shown in
Next, after the non-magnetic material 15 has been formed with sufficient thickness so as to cover the concave/convex pattern 25, an etching process is carried out on the layer of the non-magnetic material 15 to expose the protruding end surfaces of the convexes 25a from the layer of the non-magnetic material 15 (not shown). By doing so, the surface of the preform 80 is smoothed. After this, the protective layer 16 is formed so as to cover the protruding end surfaces of the convexes 25a and the surface of the non-magnetic material 15 filled in the concaves 25b, and then a lubricant is applied onto the surface of the protective layer 16. Next, as one example, by applying a magnetic field in a direction that passes through the magnetic disk 10A in the thickness direction using a DC magnetizing apparatus, the convexes 25a are DC magnetized. By doing so, as shown in
In the hard disk drive 1 equipped with the magnetic disk 10A described above, the control unit 6 carries out tracking servo control based on the servo data read via the magnetic heads 3 and control data D inside the storage unit 7. More specifically, the control unit 6 controls the controller 2a to rotate the magnetic disk 10A at a fixed angular velocity and controls the driver 5 to drive the actuator 3b and move the magnetic heads 3 to an arbitrary radial position above the magnetic disk 10A. When doing so, the detector unit 4a generates a detection signal S1 by extracting servo data from the output signal S0 (servo signal) outputted from the magnetic heads 3 and outputs the generated detection signal S1 to the control unit 6. The control unit 6 also carries out tracking servo control based on the detection signal S1 (servo data) outputted from the detector unit 4a and the control data D stored in the storage unit 7 to make the magnetic heads 3 on-track to a predetermined track.
When doing so, based on the detection signal S1 (preamble signal) outputted from the detector unit 4a when the preamble pattern region Ap (the “first region” for the present invention) of the magnetic disk 10A passes below the magnetic head 3, the control unit 6 corrects a reference clock for reading a variety of control signals from the servo address mark region Am, the address pattern region Aa, and the like, in accordance with the rotational state (i.e., the rotational velocity) of the magnetic disk 10A and adjusts the gain of the output of the servo data and user data. When doing so, the control unit 6 assumes that the read of the preamble pattern from the preamble pattern region Ap has not ended and continues correcting the reference clock described above based on the detection signal S1 outputted from the detector unit 4a until the detection signal S1 corresponding to the concave 25b of the length L3a described above formed in the servo address mark region Am is outputted from the detector unit 4a.
Accordingly, as described earlier, even if plural convexes 25a that are connected in the direction of rotation via connecting portions 25c are present inside the preamble pattern region Ap of the magnetic disk 10A so that a convex 25a with a length in the direction of rotation equal to the length 11a, for example, is present inside the preamble pattern region Ap, it will still be possible to avoid a situation where the read of the preamble pattern from the preamble pattern region Ap is erroneously judged to have ended based on a signal outputted from the detector unit 4a when such connected convexes pass below the magnetic head 3 (in this example, a detection signal S1 with three times the length of the detection signal S1 corresponding to one convex 25a inside the preamble pattern region Ap). Therefore, it is possible to avoid a situation where the detection signal S1 outputted from the detector unit 4a when convexes 25a disposed on the servo address mark region Am side of the connected convexes 25a pass below the magnetic head 3 are erroneously detected as servo address marks read from the servo address mark region Am.
On the other hand, when the concave 25b of the length L3a described above passes below the magnetic head 3 due to the rotation of the magnetic disk 10A, the control unit 6 judges that the read of the preamble pattern from the preamble pattern region Ap has ended based on the detection signal S1 outputted from the detector unit 4a when the concave 25b of the length L3a passes. When doing so, the control unit 6 identifies that the detection signal S1 outputted from the detector unit 4a after such detection signal S1 is servo data corresponding to the servo address marks read from the servo address mark region Am on the magnetic disk 10A and the address pattern read from the address pattern region Aa that follows afterward, and carries out tracking servo control based on such control data D to make the magnetic head 3 on-track to a desired track.
In this way, according to the magnetic disk 10A and the hard disk drive 1 equipped with the magnetic disk 10A, a concave 25b (i.e., a “second non-recording region”) whose length in the direction of rotation is the length L3a that is longer than a length L2a in the direction of rotation of the concaves 25b (“first non-recording regions”) inside the preamble pattern region Ap at corresponding same-pattern-radius positions is provided at a position (in this example, a front position of the servo address mark region Am) that is adjacent in the direction of rotation to the first region on the magnetic disk 10A (a region where convexes 25a that are long in the radial direction are disposed at the pitch Pa with the concaves 25b in between: in this example, the preamble pattern region Ap) and where the read of the servo data is carried out following the first region described above. By doing so, when manufacturing the magnetic disk 10A where the formation pitch of the convexes 25a inside the servo pattern regions As is sufficiently reduced to increase the recording density, even if the irradiation amount of the electron beam EB at a position corresponding to a concave 25b inside the preamble pattern region Ap of the magnetic disk 10A is insufficient when drawing the concave forming pattern Ep, resulting in a state where plural convexes 25a inside the preamble pattern region Ap become connected via a connecting portion 25c, it will still be possible to avoid a situation where it is erroneously judged, based on the servo data read when a position where the convexes 25a are connected via the connecting portion 25c (a position where the length in the direction of rotation of the convexes 25a that are continuous in the direction of rotation is longer than the length in the direction of rotation of one convex 25a) passes below the magnetic head 3, that a read of the preamble pattern from the preamble pattern region Ap has ended.
Also, according to the magnetic disk 10A and the hard disk drive 1 equipped with the magnetic disk 10A, the control unit 6 judges that a read of preamble data in the servo data has ended when servo data corresponding to the concave 25b of the length L3a described above has been read by the magnetic head 3. By doing so, even when plural convexes 25a become connected via a connecting portion 25c due to the formation pitch of the convexes 25a inside the preamble pattern region Ap being sufficiently reduced to increase the recording density, it will still be possible to correctly read the various servo data from the servo pattern regions As and as a result it will be possible to reliably avoid a situation where tracking servo control errors occur.
Also, according to the magnetic disk 10A and the hard disk drive 1 equipped with the magnetic disk 10A, by providing the concave 25b of the length L3a described above at a position that is adjacent to the preamble pattern region Ap in the direction of rotation and where a read of servo data is carried out following the servo data inside the preamble pattern region Ap (in this example, the front position of the servo address mark region Am provided after the preamble pattern region Ap), unlike a construction where a concave 25b corresponding to the second non-recording region for the present invention is provided far from the preamble pattern region Ap, there will be no convexes 25a and concaves 25b where servo data is recorded present between (i) the region (the preamble pattern region Ap) where convexes 25a and concaves 25b for preamble patterns are aligned in the direction of rotation where connecting portions 25c are likely to occur during manufacturing and (ii) the concave 25b that corresponds to the second non-recording region for the present invention. This means that it is possible to reliably read the servo data from the region (in this example, the servo address mark region Am) in which the servo data is recorded following the region (i.e., the preamble pattern region Ap) in which the convexes 25a for the preamble pattern are disposed at the pitch Pa with the concaves 25b in between.
Also, according to the magnetic disk 10A and the hard disk drive 1 equipped with the magnetic disk 10A, by setting the length L3a in the direction of rotation of the concave 25b that corresponds to the second non-recording region for the present invention equal to or longer than the formation pitch (the pitch Pa) (in this example, the length L3a=pitch Pa) of the convexes 25a for the preamble pattern at same-pattern-radius positions, compared to a magnetic disk where the length in the direction of rotation of the concave 25b corresponding to the second non-recording region for the present invention is only slightly longer than the length L2a of the concaves 25b used in the preamble pattern, the time required for the concave 25b that corresponds to the second non-recording region to pass below the magnetic head 3 will be sufficiently long, and therefore it will be possible to reliably detect the signal when the concave 25b that corresponds to the second non-recording region passes below the magnetic head 3. In this way, according to the magnetic disk 10A and the hard disk drive 1 equipped with the magnetic disk 10A, it is possible to reliably avoid a situation where it is erroneously judged, based on the servo data read when a position where the convexes 25a are connected via a connecting portion 25c passes below the magnetic head 3, that a read of the preamble pattern from the preamble pattern region Ap has ended.
In addition, according to the magnetic disk 10A and the hard disk drive 1 equipped with the magnetic disk 10A, by setting the length L3a in the direction of rotation of the concave 25b that corresponds to the second non-recording region for the present invention at N times (N is two in the present example) the length L2a in the direction of rotation of the concaves 25b used in the preamble patterns at the corresponding same-pattern-radius positions, unlike a construction where the length L3a in the direction of rotation of the concave 25b that corresponds to the second non-recording region for the present invention is set at a non-natural number multiple (such as 1.5 times) the length L2a in the direction of rotation of the concaves 25b in the preamble pattern at the same-pattern-radius positions, it will be possible to read the servo data from the entire servo pattern region As without having to switch between plural reference clocks to read the servo data from the servo pattern region As. By doing so, according to the magnetic disk 10A and the hard disk drive 1, it is possible not only to easily carry out tracking servo control but also to sufficiently lower the manufacturing cost of the hard disk drive 1 by an amount corresponding to it being no longer necessary to use control data D of a complex data structure.
Next, another embodiment of an information recording medium and a recording/reproducing apparatus according to the present invention will be described with reference to the drawings. Note that component elements that are the same as in the magnetic disk 10A and the hard disk drive 1 described earlier have been assigned the same reference numerals and duplicated description thereof is omitted.
A magnetic disk 10B shown in
In this case, on the magnetic disk 10B, the entire preamble pattern region Ap is formed of a “second region” for the present invention and the convexes 25a and the concaves 25b are alternately disposed between one end and the other end in the direction of rotation of the preamble pattern region Ap corresponding to the preamble signal used as servo data. More specifically, in the preamble pattern region Ap of the magnetic disk 10B, plural belt-shaped concaves 25b (one example of “third non-recording regions” for the present invention) that are long in the radial direction of the magnetic disk 10B (the up-down direction in both figures: the direction of the arrow Rb1 shown in
In this case, in the servo pattern 25s that constructs the preamble pattern, as one example, at a position where the distance from the center O (see
On the magnetic disk 10B, the concaves 25b of the length L1b and the convexes 25a of the length L2b described above are formed so as to be alternately disposed up to a servo address mark region Am end of the preamble pattern region Ap, and a concave 25b of the length L1b described above that corresponds to a “third non-recording region” for the present invention is formed at the servo address mark region Am end of the preamble pattern region Ap. In addition, on the magnetic disk 10B, the concaves 25b inside the preamble pattern region Ap are formed as described above at the extremely narrow pitch Pb. This means that for the magnetic disk 10B, as described later, during manufacturing, at some positions inside the preamble pattern region Ap, a connecting portion 25d is formed by a concave 25b (one example of a “fourth non-recording region” for the present invention) so that concaves 25b that are adjacent in the direction of rotation become connected in the direction of rotation. In this case, as described above, since the length L1b of the concaves 25b at a position where the distance from the center O of the data track patterns 25t is 15 mm is 55 nm and the length L2b of the convexes 25a is 55 nm, when a connecting portion 25d is formed at a position where the distance from the center O is 15 mm, the length L11b where concaves 25b are continuous along the direction of rotation is 165 nm.
Also, on the magnetic disk 10B, as described earlier, the concaves 25b are formed at positions where the convexes 25a are formed inside the servo address mark regions Am of the magnetic disk 10A and the convexes 25a are formed at positions where the concaves 25b are formed inside the servo address mark regions Am of the magnetic disk 10A. Accordingly, on the magnetic disk 10B, in place of the concave 25b with the length L3a on the magnetic disk 10A described earlier, a convex 25a corresponding to a fourth recording region for the present invention is formed at a front region of the servo address mark region Am (the preamble pattern region Ap end in the direction of rotation: one example of a “position where a read of the servo data is carried out following the servo data inside the preamble pattern region” for the present invention), with such convex 25a being used to identify the end of a read of a preamble pattern from the preamble pattern region Ap. Note that the length L3b of the convex 25a that corresponds to the “fourth recording region” for the present invention at a position where the distance from the center O of the data track patterns 25t is 15 mm is set at 110 nm that is equal to the pitch Pb described above and twice the length L2b of the convexes 25a inside the preamble pattern region Ap described above (one example where “N times” for the present invention is “twice”).
When manufacturing the magnetic disk 10B described above, as one example, a child stamper (not shown) similar to the stamper 60 fabricated when manufacturing the magnetic disk 10A described earlier is fabricated using a metal material (for example, nickel) and injection molding is carried out using this child stamper to fabricate a stamper to be used for imprinting for forming a mask pattern in the B1 mask forming layer 33 on the matrix 30. When doing so, as described above, on the magnetic disk 10B, the formation positions of the convexes 25a and the concaves 25b in two regions that are the preamble pattern region Ap and the servo address mark region Am are reversed compared to the magnetic disk 10A described above. Also, when manufacturing a magnetic disk 10B manufactured by carrying out a pattern transferring process an odd number of times counting from the silicon substrate 31 in the state where the concave/convex pattern 37 has been formed, in the first concave forming pattern Ep (not shown) to be drawn when fabricating a stamper, the electron beam EB is irradiated onto regions corresponding to the convexes 25a in the concave/convex pattern 25. Accordingly, in the concave forming pattern Ep drawn when fabricating the stamper for manufacturing the magnetic disk 10B, the positions irradiated with the electron beam EB match the concave forming pattern Ep for the magnetic disk 10A described above in regions corresponding to two regions that are the preamble pattern region Ap and the servo address mark region Am, and the positions irradiated with the electron beam EB differ from the concave forming pattern Ep for the magnetic disk 10A described above in regions corresponding to the servo pattern regions As aside from the preamble pattern region Ap and the servo address mark region Am and also the data track pattern regions At.
In this case, as described above, since the formation pitch (i.e., the pitch Pb) of the concaves 25b on the magnetic disk 10B is extremely small in the same way as the formation pitch (i.e., the pitch Pa) of the convexes 25a on the magnetic disk 10A, in the concave forming pattern Ep drawn during the fabrication of the stamper for manufacturing the magnetic disk 10B also, in the same way as the position shown by the arrow Z1 in
In the hard disk drive 1 equipped with the magnetic disk 10B, based on the detection signal S1 (preamble signal) outputted from the detector unit 4a when the preamble pattern region Ap (the “second region” for the present invention) of the magnetic disk 10B passes below the magnetic head 3, the control unit 6 corrects a reference clock for reading a variety of control signals from the servo address mark region Am, the address pattern region Aa, and the like in accordance with the rotational state (i.e., the rotational velocity) of the magnetic disk 10B and adjusts the gain of the output of the servo data and the user data. When doing so, the control unit 6 assumes that the read of the preamble patterns from the preamble pattern region Ap has not ended and continues correcting the reference clock described above based on the detection signal S1 outputted from the detector unit 4a until the detection signal S1 corresponding to the convex 25a of the length L3b described above formed in the servo address mark region Am is outputted from the detector unit 4a.
Accordingly, as described earlier, even if plural concaves 25b that are connected in the direction of rotation via connecting portions 25d are present inside the preamble pattern region Ap of the magnetic disk 10B so that a concave 25b with a length in the direction of rotation equal to the length 11b, for example, is present inside the preamble pattern region Ap, it will still be possible to avoid a situation where the read of the preamble pattern from the preamble pattern region Ap is erroneously judged to have ended based on a signal outputted from the detector unit 4a when such connected concaves pass below the magnetic head 3 (in this example, a detection signal S1 with three times the length of the detection signal S1 corresponding to one concave 25b inside the preamble pattern region Ap). Therefore, it is possible to avoid a situation where the detection signal S1 outputted from the detector unit 4a when a concave 25b disposed closer to the servo address mark region Am side than the concaves 25b connected via the connecting portion 25d passes below the magnetic head 3 is erroneously detected as a servo address mark read from the servo address mark region Am.
On the other hand, when the convex 25a of the length L3b described above passes below the magnetic head 3 due to the rotation of the magnetic disk 10B, the control unit 6 judges that the read of the preamble pattern from the preamble pattern region Ap has ended based on the detection signal S1 outputted from the detector unit 4a when the convex 25a of the length L3b passes. When doing so, the control unit 6 identifies that the detection signal S1 outputted from the detector unit 4a after such detection signal S1 is servo data corresponding to the servo address marks read from the servo address mark region Am on the magnetic disk 10B and the address pattern read from the address pattern region Aa that follows afterward, and carries out tracking servo control based on the control data D to make the magnetic head 3 on-track to a desired track.
In this way, according to the magnetic disk 10B and the hard disk drive 1 equipped with the magnetic disk 10B, a convex 25a (i.e., a “fourth non-recording region”) whose length in the direction of rotation is the length L3b that is longer than a length L2b in the direction of rotation of the convexes 25a (“third recording regions”) inside the preamble pattern region Ap at corresponding same-pattern-radius positions is provided at a position (in this example, a front position of the servo address mark region Am) that is adjacent in the direction of rotation to the second region on the magnetic disk 10B (a region where concaves 25b that are long in the radial direction are disposed at the pitch Pb with the convexes 25a in between: in this example, the preamble pattern region Ap) and where the read of the servo data is carried out following the second region described above. By doing so, when manufacturing the magnetic disk 10B where the formation pitch of the concaves 25b inside the servo pattern regions As is sufficiently reduced to increase the recording density, even if the irradiation amount of the electron beam EB at a position corresponding to a convex 25a inside the preamble pattern region Ap of the magnetic disk 10B is insufficient when drawing the concave forming pattern Ep, resulting in a state where plural concaves 25b inside the preamble pattern region Ap are connected via a connecting portion 25d, it will still be possible to avoid a situation where it is erroneously judged, based on the servo data read when a position where the concaves 25b are connected via the connecting portion 25d (a position where the length in the direction of rotation of the connected concaves 25b is longer than the length in the direction of rotation of one concave 25a) passes below the magnetic head 3, that a read of the preamble pattern from the preamble pattern region Ap has ended.
Also, according to the magnetic disk 10B and the hard disk drive 1 equipped with the magnetic disk 10B, the control unit 6 judges that a read of preamble data in the servo data has ended when servo data corresponding to the convex 25a of the length L3b described above has been read by the magnetic head 3. By doing so, even when plural concaves 25b become connected via a connecting portion 25d due to the formation pitch of the concaves 25b inside the preamble pattern region Ap being sufficiently reduced to increase the recording density, it will still be possible to correctly read the various servo data from the servo pattern regions As and as a result it will be possible to reliably avoid a situation where tracking servo control errors occur.
Also, according to the magnetic disk 10B and the hard disk drive 1 equipped with the magnetic disk 10B, by providing the convex 25a of the length L3b described above at a position that is adjacent to the preamble pattern region Ap in the direction of rotation and where a read of servo data is carried out following the servo data inside the preamble pattern region Ap (in this example, the front position of the servo address mark region Am provided after the preamble pattern region Ap), unlike a construction where a convex 25a corresponding to the fourth recording region for the present invention is provided far from the preamble pattern region Ap, there will be no convexes 25a and concaves 25b where servo data is recorded between (i) the region (the preamble pattern region Ap) where convexes 25a and concaves 25b for preamble patterns are aligned in the direction of rotation where connecting portions 25d are likely to occur during manufacturing and (ii) the convex 25a that corresponds to the fourth recording region for the present invention. This means that it is possible to reliably read the servo data from the region (in this example, the servo address mark region Am) in which the servo data is recorded following the region (i.e., the preamble pattern region Ap) in which the concaves 25b for the preamble pattern are disposed at the pitch Pb with the convexes 25a in between.
Also, according to the magnetic disk 10B and the hard disk drive 1 equipped with the magnetic disk 10B, by setting the length L3b in the direction of rotation of the convex 25a that corresponds to the fourth recording region for the present invention equal to or longer than the formation pitch (the pitch Pb) (in this example, the length L3b=pitch Pb) of the concaves 25b for the preamble pattern at same-pattern-radius positions, compared to a magnetic disk where the length in the direction of rotation of the convex 25a corresponding to the fourth recording region for the present invention is only slightly longer than the length L2b of the convexes 25a used in the preamble pattern, the time required for the convex 25a that corresponds to the fourth recording region to pass below the magnetic head 3 will be sufficiently long, and therefore it will be possible to reliably detect the signal when the convex 25a that corresponds to the fourth recording region passes below the magnetic head 3. In this way, according to the magnetic disk 10B and the hard disk drive 1, it is possible to reliably avoid a situation where it is erroneously judged, based on the servo data read when a position where the concaves 25b are connected via a connecting portion 25d, that a read of the preamble pattern from the preamble pattern region Ap has ended.
In addition, according to the magnetic disk 10B and the hard disk drive 1 equipped with the magnetic disk 10B, by setting the length L3b in the direction of rotation of the convex 25a that corresponds to the fourth recording region for the present invention at N times (N is two in the present example) the length L2b in the direction of rotation of the convexes 25a in the preamble pattern at the corresponding same-pattern-radius positions, unlike a construction where the length L3b in the direction of rotation of the convex 25a that corresponds to the fourth recording region for the present invention is set at a non-natural number multiple (such as 1.5 times) the length L2b in the direction of rotation of the convexes 25a in the preamble pattern at the same-pattern-radius positions, it will be possible to read the servo data from the entire servo pattern region As without having to switch between plural reference clocks to read the servo data from the servo pattern region As. By doing so, according to the magnetic disk 10B and the hard disk drive 1, it is possible not only to easily carry out tracking servo control but also to sufficiently lower the manufacturing cost of the hard disk drive 1 by an amount corresponding to it being no longer necessary to use control data D of a complex data structure.
Note that the present invention is not limited to the construction and method described above. For example, although the magnetic disk 10A where the concave 25b with the length L3a corresponding to the second non-recording region for the present invention is provided at the front position of the servo address mark region Am (a position closest to the preamble pattern region Ap in the servo address mark region Am that is provided adjacent to the preamble pattern region Ap) and the magnetic disk 10B where the convex 25a with the length L3b corresponding to the fourth recording region for the present invention is provided at the front position of the servo address mark region Am (a position closest to the preamble pattern region Ap in the servo address mark region Am that is provided adjacent to the preamble pattern region Ap) have been described as examples, the positions of the second non-recording region and the fourth recording region for the present invention are not limited to such. For example, it is possible to use a construction where the second non-recording region or the fourth recording region is provided at a position where a read of servo data is carried out last in the preamble pattern region (i.e., a construction where the second non-recording region or the fourth recording region is part of the preamble pattern). It is also possible to use a construction where the position at which the second non-recording region or the fourth recording region is provided is set between the preamble pattern region and another servo pattern (for example, the servo address mark region) provided following the preamble pattern region.
Even when such construction is used, in the same way as the magnetic disk 10A or 10B and the hard disk drive 1 equipped with the magnetic disk 10A or 10B described above, even if the magnetic disk is manufactured with a sufficiently reduced formation pitch for the convexes or concaves inside the servo pattern regions to increase the recording density and the amount of irradiation of the electron beam EB at positions corresponding to the concaves or positions corresponding to the convexes inside the preamble pattern region of the magnetic disk becomes insufficient during the drawing of the concave forming pattern, resulting in a state where plural convexes or plural concaves are connected via a connecting portion inside the preamble pattern region, it will still be possible to avoid a situation where it is erroneously judged, based on the servo data read when a position where the convexes or concaves are connected via the connecting portion passes below the magnetic head, that a read of the preamble pattern from the preamble pattern region has ended.
Also, although the magnetic disks 10A, 10B where the convexes 25a of the concave/convex pattern 25 (that is, the data track patterns 25t and the servo pattern 25s) are entirely formed of the magnetic layer 14 (magnetic material) from the protruding end portions to the base end portions thereof have been described as examples, the construction of the information recording medium according to the present invention is not limited to this. As a specific example, it is possible to construct the data track patterns 25t and the servo patterns 25s described above of a concave/convex pattern (not shown) including convexes whose protruding end portions are composed of the magnetic layer 14 and whose base end portions are composed of the intermediate layer 13 and/or the soft magnetic layer 12 and concaves whose base surfaces are formed inside the thickness of the intermediate layer 13 and/or the soft magnetic layer 12. It is also possible to construct the data track patterns 25t and the servo patterns 25s from a concave/convex pattern (not shown) where not only the convexes but also the base surfaces of the concaves are formed of the magnetic layer 14.
In addition, by forming a thin magnetic layer 14 so as to cover a concave/convex pattern formed in the glass substrate or the like (a concave/convex pattern where the concaves and convexes have the same positional relationship as the concave/convex pattern 25), it is possible to construct the concave/convex pattern 25 (the data track patterns 25t and the servo patterns 25s: not shown) from plural convexes whose surfaces are formed of magnetic material and plural concaves whose base surfaces are formed of the magnetic material. It is also possible to construct the concave/convex pattern 25 (the data track patterns 25t and the servo patterns 25s: not shown) from plural convexes where only the protruding end portions of convexes of the concave/convex pattern formed in a glass substrate or the like are formed of the magnetic layer 14 and the base end portions are formed of a non-magnetic material or a soft magnetic material. In addition, it is possible to construct the concave/convex pattern 25 (the data track patterns 25t and the servo patterns 25s: not shown) by forming the magnetic layer 14 not only on the protruding end portions of convexes of a concave/convex pattern formed in a glass substrate or the like but also on the base surfaces of the concaves (i.e., by forming the magnetic layer 14 on surfaces aside from the side surfaces of the convexes).
In addition, it is also possible to construct a magnetic disk (not shown) by filling concaves of a concave/convex pattern formed in a layer of non-magnetic material with the magnetic material that constructs the magnetic layer 14 described above and setting the positions of the convexes in the layer of the non-magnetic material as the non-recording regions (i.e., regions corresponding to the concaves 25b of the magnetic disk 10A or the like) and positions of the magnetic material filled in the concaves as the recording regions (i.e., regions corresponding to the convexes 25a of the magnetic disk 10A or the like). Also, although examples where the magnetic disks 10A, 10B are manufactured by carrying out imprinting using a stamper manufactured using the concave forming pattern Ep drawn by irradiation with the electron beam EB and then carrying out etching using the formed mask pattern have been described, the information recording medium according to the present invention is not limited to a medium manufactured by an etching process. More specifically, as one example, a mask pattern may be formed on the magnetic layer by carrying out imprinting using a stamper manufactured using the concave forming pattern Ep and an ion irradiation process, a reaction process that uses reactive gas, or the like may be carried out using the mask pattern to selectively modify positions where the magnetic layer is exposed from the mask pattern. By carrying out such processes, it is also possible to construct a magnetic disk (not shown) by forming regions whose ability to hold a magnetic signal in a readable manner is lower than that of the periphery thereof or regions that effectively cannot hold a magnetic signal, setting regions whose ability to hold a magnetic signal in a readable manner is high as recording regions, and setting regions whose ability to hold a magnetic signal in a readable manner is low as non-recording regions.
Also, although the magnetic disks 10A, 10B have been described where the length of each data track pattern region At along the direction of rotation of the magnetic disks and the length of each servo pattern region As along the direction of rotation are set so as to increase as the distance from the center O of the data track patterns 25t increases (i.e., the data track pattern regions At and the servo pattern regions As are set so as to widen from an inner periphery region to an outer periphery region) in proportion to the length of a part of the magnetic disk 10 that passes below the magnetic head 3 per unit time, the construction of the information recording medium according to the present invention is not limited to this. For example, a magnetic disk 10C shown in
In this case, on the magnetic disks 10A, 10B described above where the length along the direction of rotation of the servo pattern regions As gradually increases from the innermost periphery to the outermost periphery, the lengths along the direction of rotation of the convexes 25a and the concaves 25b inside each preamble pattern region Ap gradually increase toward the outer periphery. For this reason, in the concave forming pattern Ep drawn when manufacturing the stampers described above for manufacturing the magnetic disks 10A, 10B, the length along the direction of rotation of regions sufficiently irradiated with the electron beam EB until the resist layer is eliminated during the developing process gradually increases toward the outer periphery. Accordingly, when drawing the concave forming pattern Ep used to manufacture the magnetic disks 10A, 10B, it is possible to avoid a situation where irradiation with the electron beam EB is insufficient (i.e., the reason why the connecting portions 25c, 25d described above are formed) at the outer periphery of the concave forming pattern Ep.
On the other hand, on the magnetic disk 10C described above, in the ring-shaped regions Ac2 to Ac4 that are further outside than the ring-shaped region Ac1, the length along the direction of rotation of the servo pattern regions As is set shorter than at corresponding pattern radius positions in the servo pattern regions As of the magnetic disks 10A, 10B. This means that in the concave forming pattern drawn when manufacturing a stamper for manufacturing a magnetic disk 10C, the length along the direction of rotation of regions sufficiently irradiated with the electron beam EB until the resist layer is eliminated during the developing process becomes shorter in the ring-shaped regions Ac2 to Ac4 that are further outside than the ring-shaped region Ac1. Accordingly, during the drawing of a concave forming pattern for manufacturing the magnetic disk 10C, there is the risk of positions where the irradiation of the electron beam EB is insufficient being produced in the outer periphery also, and due to this, connecting portions that are the same as the connecting portions 25c, 25d described above may be formed in the preamble pattern region Ap. For this reason, by applying the present invention to the magnetic disk 10C, even if a connecting portion is formed inside a preamble pattern region Ap in the outer periphery of the magnetic disk 10C, it will be possible to avoid a situation where it is erroneously judged that a read of a preamble pattern from the preamble pattern region Ap has ended.
