Patent Application
20130057978
The present application claims priority from Japanese Patent Application No. 2011-194646, which was filed on Sep. 7, 2011, the disclosure of which is herein incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a magnetic recording reproducing apparatus and a magnetic recording medium, which adopt a Shingle recording technology and capable of densely recording information.
2. Description of the Related Art
Improvement in high quality pictures and images causes a considerable increase in the volume of information handled by a user. For the purpose of realizing a larger capacity magnetic recording apparatus so-called HDD (Hard Disk Drive), approaches for increasing the surface recording density have been discussed. One high-density magnetic recording technology that seems to be promising is a Shingle recording technique which is disclosed in Japanese Unexamined Patent Publication No. 2011-8881 (Tokukai 2011-8881) for example, in which recording is performed so that a recording column currently being recorded partially overlap with another recording column adjacent in a track width direction, the other recording column having been subjected to immediately previous recording.
In general, the pitch of tracks formed on a magnetic recording medium is a several times greater than a shortest mark formed. However, Shingle recording technique performs recording so as to partially overlap with an adjacent recording column having been subjected to immediately previous recording. Therefore, the pitch of tracks to be formed at the end is reduced to a pitch which is approximately the same as the shortest mark length. In other words, recording is performed so as to partially overwrite the adjacent recording column having been subjected to immediately previous recording. This increases the number of tracks per unit length to several times more, and makes it possible a significant improvement in the recording density.
However, with the apparatus of the Japanese Unexamined Patent Publication No. 8881/2011 (Tokukai 2011-8881), rewriting of a recording column necessitates rewriting of all the subsequently-formed recording columns. This may lead to a lower substantial recording rate (the information amount of recording column rewritten/time required for rewriting recording columns to be rewritten and not rewriting the information of the other recording columns). This is elaborated with reference to
The recording column for forming a track Tr101 is formed prior to formation of the recording column for forming a track Tr102. Therefore, the information on the track Tr101 remains without being rewritten. On the other hand, a track Tr103 is overwritten with the recording column for forming the Tr102′, and an attempt to reproduce the track Tr103 under such a condition will result in a reproduction error. Therefore, the recording column for forming the track Tr103 formed after the formation of the recording column for forming the track Tr102 needs to be overwritten with a recording column for forming the track Tr103′ with information identical to that on the recording column for forming the track Tr103.
As described, rewriting only the track Tr102 requires, in total, a time for forming the recording column for forming the track Tr102′, and a time for overwriting all the recording columns formed after the recording column for forming the track Tr102. This requires a rewriting time which is several times longer than the prior recording technique.
It is therefore an object of the present invention to provide a magnetic recording reproducing apparatus and a magnetic recording medium, in which a decrease in the substantial recording rate for rewriting operation is prevented and a reproduction error hardly occurs, in cases of adopting a Shingle recording technique which allows a densely recording.
A magnetic recording reproducing apparatus of the present invention includes: a disc-shaped magnetic recording medium having thereon information recording areas; a magnetic recording element configured to perform information recording, by applying a magnetic field to the magnetic recording medium to form recording columns extending in a circumferential direction of the magnetic recording medium; a magnetic reproducing element, which performs information reproduction by detecting leaked magnetic field from the magnetic recording medium; a moving mechanism configured to move the relative position of the magnetic recording medium to the magnetic recording element and the magnetic reproducing element, in the circumferential direction and a radial direction of the magnetic recording medium; and a magnetic recording element control unit configured to control the magnetic recording element and the moving mechanism so that, in the information recording area, recording columns adjacent to each other relative to the radial direction are overlapped with each other in the radial direction. The magnetic recording element control unit performs control so that each of the recording columns has an overlapping portion which partially overlaps with either of the adjacent recording columns in the radial direction, and a non-overlapping portion which does not overlap with any of the recording columns in the radial direction.
A magnetic recording medium of the present invention is a disc-shaped magnetic recording medium comprising information recording areas each having a plurality of recording columns extending in a circumferential direction. Each of the recording columns has an overlapping portion which partially overlaps with either of the adjacent recording columns in a radial direction, and a non-overlapping portion which does not overlap with any of the recording columns in the radial direction.
Other and further objects, features and advantages of the invention will appear more fully from the following description taken in connection with the accompanying drawings in which:
The following describes a first embodiment of present invention. As shown in
The suspension 5 has one end portion fixed to the voice coil motor 7 and another end portion far from the voice coil motor 7 having a recording reproducing head 9 which applies a magnetic field to the magnetic recording medium 3. The spindle 6 rotates the magnetic recording medium 3 counterclockwise (the direction of the arrow shown in
Note that, the spindle 6, a not-shown motor (relating to movement in the circumferential direction) which rotates the spindle 6, the suspension 5 (related to movement in the radial direction), and the voice coil motor 7 (related to movement in the radial direction) structure a “moving mechanism” of the present embodiment.
The recording reproducing head 9 is for recording and reproducing magnetic information. Specifically as shown in
The magnetic recording element 10, when recording information to the magnetic recording medium 3, applies a magnetic field of a recordable intensity to the magnetic recording medium 3, thereby forming a recording column extended in a circumferential direction (track direction) of the magnetic recording medium 3. This way, for example, the direction of magnetization on the magnetic recording medium 3 is determined. The magnetic reproducing element reads a magnetization pattern by detecting a leaked magnetic field from the magnetic recording medium 3, thereby reproducing the information. Note that the positional relation between the magnetic recording element 10 and the magnetic reproducing element 11 relative to the circumferential direction when viewed from the magnetic recording medium 3 is such that, when the recording reproducing head 9 passes any given position of the magnetic recording medium 3, the magnetic reproducing element 11 passes that position first, followed by the magnetic recording element 10.
As described, the magnetic recording reproducing apparatus 4 is capable of performing recording and reproduction to a predetermined position of the magnetic recording medium 3, with the operations of the spindle 6 and the suspension 5, and by controlling application of the magnetic field by the recording reproducing head 9. In other words, the magnetic recording reproducing apparatus 4 includes a controller 20 which performs a predetermined computing process for controlling various functions of the suspension 5, spindle 6, or the like. For example, the controller 20 is realized by a CPU (Central Processing Unit) or the like. As shown in
Next, the following describes a magnetic recording medium 3 included in the magnetic recording reproducing apparatus 4. The magnetic recording medium 3 of the present embodiment is manufactured by: forming a magnetic layer on a glass substrate; polishing the surface to smoothen the same; and applying a lubricant. The material (magnetic layer) which forms a magnetic recording part may be, for example, Co, Pt, Fe, Ni, Cr, Mn, or an alloy of any of these metals. Examples of the above alloy include, for example, CoPt, SmCo, CoCr, and TbFeCo alloy. Further, in the present embodiment, the magnetic recording surface is formed only on one side of the magnetic recording medium 3. However, the present invention is not limited to this, and the magnetic recording surface may be formed on both sides of the magnetic recording medium 3. In such a case, the above mentioned processes of the manufacturing method are carried out on both sides of the magnetic recording medium 3. Note that application of the lubricant on the magnetic recording surfaces on both sides of the magnetic recording medium 3 may be carried out at the same time.
Next, the following describes control performed by the controller 20. As mentioned hereinabove, the controller 20 controls the suspension 5, the voice coil motor 7, and the recording reproducing head 9 to form on the magnetic recording medium 3 a plurality of recording columns shown in
As shown in
The following describes steps of a process, particularly a recording method, performed in the controller 20.
To form an n-th recording column (n=any given natural number ranging from 1 to N at the maximum) on the magnetic recording medium 3 in the magnetic recording reproducing apparatus 4 of the present embodiment, the controller 20 which controls the suspension 5, the voice coil motor 7, and the recording reproducing head 9 controls formation of the n-th recording column so that the n-th recording column partially overlaps an (n−1) th recording column which is the immediately previous track, in the radial direction.
The controller 20 serving as the magnetic recording element control unit performs control so that a plurality of recording columns are formed at a constant pitch in the radial direction. More specifically, where the radial positions of the inner and outer circumferential edges of the n-th recording column for forming an n-th track are R(n)in and R(n)out, respectively, and where the inner and the outer adjacent recording columns of the n-th recording column are an (n−1) th recording column and an (n+1) th recording column, respectively, the controller 20 performs control so as to achieve
R(n−1)in<R(n)in<R(n−1)out<R(n+1)in<R(n)out<R(n+1)out (1).
This leaves at least a radial range from R(n−1)out to R(n+1)in as a non-overlapping portion which does not overlap with any of the recording columns, at any given condition. In this non-overlapping portion remains information of the n-th recording column.
This is elaborated below with reference to
However, in the present embodiment,
R(4)in<R(3)out<R(5)in<R(4)out
Therefore, the information of the fourth track Tr4 is retained in the radial range having a width W(Tr4), which ranges from R(3)out to R(5)in. There is no need of overwriting the fifth and the subsequent recording columns. This shortens the total time taken for rewriting, and prevents a decrease in the substantial recording rate.
Supposing that the width of each recording column relative to the radial direction is the same,
R(n)in<R(n−1)out<R(n+1)in<R(n)out (2).
Similarly, supposing that the width of each recording column relative to the radial direction is the same and the track pitch is the same, the equation (1) may be expressed as follows, using the track pitch WTr(e.g. R(n)in−R(n−1)in) and the width WW (e.g. R(n)out−R(n)in) of the magnetic pattern relative to the radial direction which is formed by the magnetic recording element,
W
W/2<WTr<WW (3)
Since the equation (1) is satisfied in the present embodiment, the information of the n-th recording column is retained in the radial range from R(n−1)out to R(n+1)in. Thus, in an area of a magnetic recording medium where no information is recorded, the recording columns do not necessarily have to be formed in a direction from the inner circumference to the outer circumference or in the opposite direction. In other words, it is possible to perform control such that recording columns are formed in a random order.
In the present embodiment, where the width (width of sensing area) of the magnetic reproducing element 11 relative to the radial direction is Wr, the following condition is satisfied:
{R(n+1)in−R(n−1)out}>Wr/2 (4).
Suppose the equation (4) is not satisfied. In this case, at the time of reproducing the n-th track Tr (n) after the n-th track Tr (n) is rewritten, the portion of the track Tr (n) retaining information has a width relative to the radial direction, which is less than a half of the width Wr of the magnetic reproducing element 11. Therefore, a half or more of the detected leaked magnetic field could be a component of inter-track cross-talk or the like from adjacent tracks, no matter how the tracking is performed. Such a component may be greater than that from the track to be reproduced.
On the contrary, suppose the equation (4) is satisfied. In this case, at the time of reproducing the m-th track Tr (n) after the n-th track Tr (n) is rewritten, the area retaining information of the track Tr (n) has a width relative to the radial direction, which is wider than a half of the width Wr of the magnetic reproducing element 11. Thus, by tracking the track to be reproduced with the magnetic reproducing element 11, the leaked magnetic field contains less component of the inter-track cross-talk or the like from the adjacent tracks than that from the track to be reproduced. Therefore, reproduction error less likely takes place.
This way, signals from the track to be reproduced is more clearly detected than signals from the adjacent tracks on the inner and the outer circumference sides. It is therefore possible to restrain reproduction errors.
The following describes a modification of the first embodiment. As shown in
As described, by forming the recording columns so that, for each of the recording column, there is an overlapping portion in which adjacent recording columns overlap with each other relative to the radial direction, and a non-overlapping portion in which a recording column does not overlap with any other recording column relative to the radial direction, the information recorded in the non-overlapping portion which does not overlap with any other recording columns (a radial range from R(6)in to R(7)in, a radial range from R(8)out to R(7)out, a radial range from R(8)in to R(9)in, a radial range from R(8)out to R(9)out) is retained without being rewritten, even if the information of another recording column is rewritten. For example, in the state shown in
Next, a second embodiment of the present invention is described. Parts and members that are identical to those of the first embodiment are given the same reference numerals, and no further description is provided for them.
The controller 20 serving as the magnetic recording element control unit performs control so that a plurality of recording columns are formed in the radial direction. More specifically, where the radial positions of the inner and outer circumferential edges of the n-th recording column for forming an n-th track are R(n)in and R(n)out, respectively, and where the inner and the outer adjacent recording columns of the n-th recording column are an (n−1) th recording column and an (n+1) th recording column, respectively, the controller 20 performs control so that the equation (1) is satisfied. This leaves at least a radial range from R(n−1)out to R(n+1)in as a non-overlapping portion, at any given condition. In this non-overlapping portion remains information of the n-th recording column.
To record information in an area where no magnetic information is recorded, a plurality of recording columns are formed so that, starting from formation of the first recording column for forming the first track, the second recording column, the third recording column, . . . are sequentially formed to satisfy the equation (1). In other words, as in the above first embodiment, where the second, third, and fourth tracks are the track Tr1, track Tr2, and track Tr3, respectively as shown in
R(12)in<R(11)out<R(13)in<R(12)out.
Therefore, the information on the third track Tr12 is retained at least in a non-overlapping portion which is a radial range from R(11)out to R(13)in. When rewriting only the recording column for forming the third track Tr12, there is no need of overwriting the fourth and subsequent recording columns. This shortens the total time taken for rewriting, and prevents a decrease in the substantial recording rate.
The magnetic reproducing element 11 reproduces information by detecting the tracking pattern 12 to specify the radial position of a targeted track on the magnetic recording medium 3, and by performing tracking with respect to the track (radial position). In the present embodiment, the tracking pattern 12 (specifically, later-described small patterns excluding those for distinguishing an even-number-th track from an odd-number-th track) is formed at a track pitch equal to that of tracks.
An inner edge of the small pattern 12-1, and an outer edge of the small pattern 12-2 are both in the center of the track Tr12, i.e., at a radial position expressed as {R(11)out+R(13)in}/2. Thus, the radial position of the magnetic reproducing element 11 is controlled so that a signal amplitude detected at the position of the small pattern 12-1 relative to the circumferential direction, and that detected at the position of the small pattern 12-2 relative to the circumferential direction are equal to each other. This enables positioning of the center position Pr of the magnetic reproducing element 11 relative to the radial direction to the center of the track Tr12, i.e., the radial position expressed as {R(11)out+R(13)in}/2.
The small patterns 12-3 are patterns for determining whether the track to be reproduced is an even-number-th track or an odd-number-th track. In the present embodiment, signals of the small pattern 12-1 and the small pattern 12-2 are continuously detected prior to reproduction of the track Tr12. After this, if there is a certain interval (an interval equivalent to a single small pattern) before a signal of the small pattern 12-3 is detected, the track Tr12 is determined as to be an odd-number-th track. For example, in cases of Tr11 and Tr13, signals of the small pattern 12-1′ and the small pattern 12-2, or signals of the small pattern 12-1 and small pattern 12-2′ are continuously detected. Then the signal of the small pattern 12-3 is also continuously detected, and no signal is detected thereafter for a certain interval (an interval equivalent to a single small pattern). Therefore, these tracks are determined as to be an even-number-th track.
The tracking pattern is not limited to the above, and the arrangement of the small patterns in the tracking pattern may be different from the arrangement described above. Further, the tracking pattern may be such that tracking is performed based on the phase of signal detected. Further, it is possible to arrange an address pattern storing address information, on or after the tracking pattern.
The center position Pr of the magnetic reproducing element 11 does not necessarily have to be at the center of the track Tr12, i.e., the radial position expressed as {R(11)out+R(13)in}/2. By controlling the center position Pr of the magnetic reproducing element 11 to achieve R(11)out<Pr<R(13)in, signals from the track Tr12 are more clearly detected than signals from the adjacent track Tr11 and track Tr13, even after the track Tr12 is rewritten. This restrains reproduction errors.
In this case, the inner edge of the small pattern 12-1 and the outer edge of the small pattern 12-2 are positioned in radial positions between R(11)out and R(13)in. This way, the radial position of the magnetic reproducing element 11 is controlled so that a signal amplitude detected at the position of the small pattern 12-1 relative to the circumferential direction, and that detected at the position of the small pattern 12-2 relative to the circumferential direction are equal to each other. This enables positioning of the center position Pr of the magnetic reproducing element 11 relative to the radial direction so that R(11)out<Pr<R(13)in. Note that, for the purpose of optimizing the reproduction signal quality such as the error rate, according to the signal level, inter-track cross-talk, or noise level, it is possible to electrically offset the radial position of the magnetic reproducing element 11 within a range such that R(11)out<Pr<R(13)in is satisfied, so that the radial position of the magnetic reproducing element 11 during reproduction is slightly different from the position of the same where the amplitudes of the detected signals from the small pattern 12-1 and the small pattern 12-2 are equal to each other.
Further, the magnetic recording element 10 may form a recording column while the magnetic reproducing element is performing tracking based on the signal detected from the tracking pattern 12. If the center position of a track to be reproduced is different from that of the recording column formed, relative to the radial direction, it is possible to track a radial position different from the position where the amplitudes of detected signals from the small pattern 12-1 and the small pattern 12-2 are equal to each other, by means of electric offset at the time of forming a recording column. This enables tracking when forming the recording columns, by using the tracking pattern 12 corresponding to the radial positions of the tracks. There is no need for an extra tracking pattern for forming a recording column separately from the tracking pattern for reproducing a recording column. As the result, recording error is reduced without a need of reducing the recording capacity.
The present invention is also applicable to a laser (heat)-assisted magnetic recording reproducing apparatus. In this case, the magnetic recording reproducing apparatus has a laser (heat) source for locally heating the recording medium. The recording medium in this case may be a magnetic recording medium having a magnetic recording film whose magnetic switching field is lowered to a desirable level when heated by the laser (heat).
While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-194646 | Sep 2011 | JP | national |
