JP2008021400A - Disk apparatus and disk medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce cross-talk noise in a disk apparatus that reproduces magnetically recorded informtion and a disk medium that has a plurality of concentrically arranged tracks. <P>SOLUTION: The disk medium is provided to the disk apparatus including a recording head that records information on a track for writing using a perpendicular magnetic recording method, a reproducing head that reproduces the information recorded on a track for reading, a sampling section that samples a voltage waveform which changes according to a change of electric resistance of a magnetoresistance effect element provided to the reproducing head, and a data reproducing section that reproduces data recorded on the track for reading based on the shape of the sampled voltage waveform. The disk medium has the plurality of concentrically arranged tracks and has a shield section that shields between magnetic materials of the tracks. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a disk device and a disk medium. In particular, the present invention relates to a disk device for reproducing magnetically recorded information and a disk medium having a plurality of tracks arranged concentrically.

  2. Description of the Related Art Conventionally, a magnetic disk recording / reproducing apparatus that records and reproduces information magnetically on a disk medium is known. A conventional magnetic disk recording / reproducing apparatus employs a horizontal magnetic recording system in which a disk medium is magnetized in a direction parallel to the main surface (in-plane direction). However, in recent years, magnetic disk recording / reproducing apparatuses employing a perpendicular magnetic recording method in which a disk medium is magnetized in a direction perpendicular to the main surface have been proposed (for example, see Non-Patent Documents 1 and 2).

  Further, the signal read from the magnetic disk magnetized by the horizontal magnetic recording method is a signal that does not include a DC response. Further, the conventional magnetic disk recording / reproducing apparatus performs the reproducing process after differentiating the signal read from the perpendicular magnetic recording type magnetic disk to remove the DC response. Furthermore, in recent years, when a signal recorded on a perpendicular magnetic recording type magnetic disk is read in order to increase the density of the magnetic disk, the magnetic disk recording / reproducing apparatus reproduces a signal including a DC response. It has come to process.

Isatake Kaitsu, Ryosaku Inamura, Junzo Toda, Toshihiko Morita, "Ultra High Density Perpendicular Magnetic Recording Technologies", [Online], January 2006, Fujitsu homepage, [August 11, 2006 search], Internet <URL: http: //www.fujitsu.com/downloads/MAG/vol42-1/paper14.pdf> TDK Corporation SQ Laboratories Next Generation Magnetic Recording Device Development Group, “Development of Magnetic Recording Media for Ultra High Density Hard Disks”, [Online], [Search August 11, 2006], Internet <URL: http: // www .business-i.jp / sentan / jusyou / 2006 / tdk.pdf>

  FIG. 6 shows the characteristics of a perpendicular magnetization type magnetic disk measured by the inventor of the present application. More specifically, in a magnetic disk recording / reproducing apparatus adopting a perpendicular magnetic recording system, adjacent patterns having the same code are adjacent to each other. This shows the error rate of the signal including the DC component reproduced from the read target track with respect to the continuous number (run length T) of the same code of the pattern when recorded on the track. 6A shows the error rate when the run length T of the pattern recorded in the adjacent track on the inner periphery side of the read target track is changed, and the graph of B shows the outer periphery of the read target track. The error rate when the run length T of the pattern recorded in the adjacent track on the side is changed is shown. The graph of C shows the run length T of the pattern recorded in the adjacent track on both the inner peripheral side and the outer peripheral side. The error rate in the case of changing is shown.

  As shown in FIG. 6, a magnetic disk recording / reproducing apparatus that reproduces a signal including a DC response from a magnetic disk adopting a perpendicular magnetic recording system has an error rate when the run length T of a pattern recorded in an adjacent track increases. Goes up. Here, when the run length T of the signal recorded in the adjacent track increases, the crosstalk noise mixed in the reproduction signal from the adjacent track has a lower frequency. Therefore, when reproducing a signal including a DC response from a magnetic disk adopting a perpendicular magnetic recording system, the magnetic disk recording / reproducing apparatus mixes low frequency crosstalk noise from an adjacent track into the reproduced signal, so that the error rate Goes up.

  Therefore, an object of the present invention is to provide a disk device and a disk medium that can solve the above-described problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.

  In order to solve the above problems, in the first embodiment of the present invention, a disk medium having a plurality of tracks arranged concentrically and a recording head for recording information on a track to be written by a perpendicular magnetic recording method A reproducing head that reproduces information recorded on a track to be read, a sampling unit that samples a voltage waveform that changes in accordance with a change in electrical resistance of a magnetoresistive element provided in the reproducing head, and And a data reproducing unit that reproduces data recorded on the read target track based on the shape of the voltage waveform, and the disk medium provides a disk device having a blocking unit that blocks between magnetic bodies of the tracks. .

  In the second embodiment of the present invention, a recording head for recording information on a track to be written by a perpendicular magnetic recording method, a reproducing head for reproducing information recorded on a track to be read, and a reproducing head are provided. A sampling unit that samples a voltage waveform that changes in accordance with a change in electrical resistance of the magnetoresistive effect element, and a data reproduction unit that reproduces data recorded on the read target track based on the shape of the sampled voltage waveform; A disk medium having a plurality of tracks arranged concentrically and having a blocking portion that blocks between magnetic bodies of the tracks is provided.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  According to the present invention, crosstalk noise can be reduced.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows a configuration of a disk device 10 according to the present embodiment. The disk device 10 is a magnetic recording / reproducing apparatus that magnetically records and reproduces information on the disk medium 20, and functions as a storage device of an information processing apparatus such as a computer. The disk device 10 includes a disk medium 20, a disk drive unit 22, a recording head 24, a reproduction head 26, a slider 28, an arm 30, and an arm drive unit 32.

  The disk medium 20 has a plurality of tracks 40 arranged concentrically, and digital information is magnetically recorded along the tracks 40. The disk medium 20 holds digital information magnetically recorded on the track 40. The disk drive unit 22 holds the disk medium 20 rotatably. The disk drive unit 22 rotationally drives the disk medium 20 during recording and reproduction.

  The recording head 24 records information on the track 40 to be written by the perpendicular magnetic recording method. The reproducing head 26 reproduces information recorded on the track 40 to be read by the perpendicular magnetic recording method.

  The slider 28 holds the recording head 24 and the reproducing head 26. As an example, the recording head 24 and the reproducing head 26 are disposed on a surface of the slider 28 that faces the recording surface of the disk medium 20. The slider 28 floats slightly on the recording surface of the disk medium 20 by the rotation of the disk medium 20 at the time of recording and reproduction, and the recording head 24 and the recording head 24 reach a position where recording and reproduction can be performed on the rotating disk medium 20. The reproducing head 26 is brought close.

  The arm 30 supports the slider 28 so as to be movable in the radial direction of the disk medium 20, and opposes the recording head 24 and the reproducing head 26 from the position facing the innermost track 40 to the outermost track 40. Move to the position where you want to. For example, the arm 30 may hold the slider 28 at one end in the longitudinal direction.

  The arm driving unit 32 drives the arm 30 to move the recording head 24 and the reproducing head 26 disposed on the slider 28 to a position facing the write target or read target track 40 in the disk medium 20. For example, the arm driving unit 32 may move the recording head 24 and the reproducing head 26 by rotationally driving the arm 30 around an end in the longitudinal direction where the slider 28 is not held.

  The disk device 10 may include a plurality of disk media 20 that are simultaneously driven to rotate by one disk drive unit 22 and a plurality of sliders 28 provided corresponding to each of the plurality of disk media 20. .

  The disk apparatus 10 as described above moves the recording head 24 or the reproducing head 26 provided on the slider 28 while rotating the disk medium 20 in the radial direction of the disk medium 20, thereby moving the recording head 24 or the reproducing head 26. It is moved to a position facing the track 40 to be written and read. Then, the disk device 10 performs recording or reproduction with respect to the disk medium 20 by the perpendicular magnetic recording method in a state where the recording head 24 and the reproducing head 26 are moved to a position facing the track 40 to be written or read. To do. Thereby, according to the disk device 10, information can be magnetically recorded and reproduced with respect to the plurality of tracks 40 of the disk medium 20.

  FIG. 2 shows a track 40 included in the disk medium 20 according to the present embodiment. FIG. 3 shows an example of a cross-sectional structure of a part in the radial direction of the disk medium 20 according to the present embodiment.

  As shown in FIG. 2, the disk medium 20 has a thin plate shape (disk shape) with a circular main surface. The disk medium 20 has a plurality of concentric tracks 40 on which information is recorded.

  As shown in FIG. 3, the disk medium 20 includes a substrate 42, a soft magnetic layer 44, a magnetic layer 46, a protective layer 48, a lubricating layer 50, and a blocking portion 52. The substrate 42 has a disk shape. As an example, the substrate 42 may be formed of glass, aluminum, or the like.

  The soft magnetic layer 44 is laminated on the substrate 42 by, for example, sputtering. The soft magnetic layer 44 is formed of a soft magnetic material or a high magnetic permeability material. For example, the soft magnetic layer 44 may be formed of NiFe or the like. The soft magnetic layer 44 forms a part of a magnetic circuit for returning the magnetic flux output from the recording head 24 and passing through the magnetic layer 46 to the recording head 24 again through the magnetic layer 46 during recording.

  The magnetic layer 46 is laminated on the soft magnetic layer 44 by sputtering, for example, and each track 40 is formed. For example, the magnetic layer 46 may have perpendicular anisotropy so that it can be easily magnetized in the perpendicular direction. For example, the magnetic layer 46 may be formed of CoCrPt or the like. The magnetic layer 46 is magnetized in the direction of the vertical magnetic field (upward or downward) when a vertical magnetic field is applied, and can maintain a magnetized state even after the application of the vertical magnetic field is completed. Therefore, the magnetic layer 46 can store information corresponding to the direction (upward or downward) of the vertical magnetic field applied from the recording head 24, and further, can generate a vertical magnetic field in a direction corresponding to the stored information. It can be given to the reproducing head 26.

  The protective layer 48 is laminated on the magnetic layer 46 by, for example, sputtering. For example, the protective layer 48 may be formed of a carbon material or the like. The protective layer 48 prevents the soft magnetic layer 44 and the magnetic layer 46 from being damaged due to impact caused by contact between the recording head 24 and the reproducing head 26 and the disk medium 20. The lubricating layer 50 is laminated on the protective layer 48 by, for example, coating. For example, the lubricating layer 50 may be perfluoropolyether or the like. The lubricating layer 50 reduces friction between the recording head 24 and the reproducing head 26 and the disk medium 20.

The blocking unit 52 blocks between the magnetic bodies of the tracks 40. Each of the plurality of tracks 40 formed concentrically by the material having a low permeability compared to the magnetic material of the track 40 such as a non-magnetic material and relatively difficult to transmit the magnetic flux. It may be formed between. As an example, the blocking part 52 may be formed of SiO ₂ or the like. As an example, the blocking portion 52 opens between each of the plurality of tracks 40 formed concentrically after the magnetic layer 46 is stacked by etching or the like, and the blocking portion 52 is stacked by sputtering, for example. You may form by doing.

  Such a blocking portion 52 magnetically blocks the track 40 formed by the magnetic layer 46 and the adjacent track 40. That is, when the information recorded on the track 40 to be read is magnetically read by the reproducing head 26, the blocking unit 52 has a low frequency equal to or lower than a predetermined frequency due to crosstalk from an adjacent track adjacent to the track to be read. In order to prevent the frequency noise from being applied to the voltage waveform, the magnetic flux generated from the adjacent track 40 is reduced or blocked from being input to the reproducing head 26. Thereby, according to the interruption | blocking part 52, the crosstalk noise from the adjacent track | truck 40 contained in a reproduction | regeneration signal can be reduced.

  In the present embodiment, the blocking portion 52 is provided so as to penetrate the magnetic layer 46 and the soft magnetic layer 44, and the magnetic layer 46 and the soft magnetic layer 44 corresponding to each track 40 are separated by a nonmagnetic material. . Further, as an example, the blocking portion 52 may be a non-magnetic material formed in a groove extending from the surface of the disk medium 20 on the magnetic material layer 46 side to a depth of at least 1/2 or more of the track width. According to such a blocking portion 52, the leakage magnetic field applied to the reproducing head 26 from an adjacent track can be sufficiently reduced because the blocking portion 52 is formed at a depth of at least half of the track width.

  Further, as an example, the blocking section 52 has a period in which the continuous number (run length) of the same code is 50 or more from the surface on the magnetic layer 46 side of the disk medium 20 between the magnetic bodies forming the track 40. It may include a non-magnetic material that reaches a predetermined depth so that the influence of the low frequency noise on the voltage waveform of the signal detected by the reproducing head 26 when the reproduced signal is restored is within an allowable range. As shown in FIG. 11, the error rate of the signal reproduced by the reproducing head 26 increases remarkably when the run length of the adjacent track is 50 or more. Therefore, according to the blocking unit 52 of this example, the leakage magnetic field applied to the reproducing head 26 from the adjacent track is sufficiently suppressed by suppressing the low-frequency noise having a run length from the adjacent track of 50 or more. Can be reduced.

  Further, as an example, the blocking unit 52 performs sampling for sampling the signal detected by the reproducing head 26 during restoration of the reproduction signal from the surface of the magnetic layer 46 side of the disk medium 20 between the magnetic bodies of the track 40. Includes a non-magnetic material that reaches a predetermined depth to suppress the influence of low-frequency noise having a frequency of 1% or less of the frequency (for example, the sampling frequency of the sampling unit 132 described later) on the voltage waveform within an allowable range. It's okay. According to the blocking unit 52 of this example, reproduction from an adjacent track is performed by suppressing low-frequency noise having a frequency of 1% or less of the sampling frequency (for example, a frequency having a run length of 50 or more from the adjacent track). The leakage magnetic field applied to the head 26 can be sufficiently reduced.

  As described above, according to the disk medium 20, information can be recorded and reproduced by the perpendicular magnetic recording method with respect to the recording head 24 and the reproducing head 26 that are close from the lubricating layer 50 side. Furthermore, according to the disk medium 20, it is possible to reduce the magnetic field leaking from the adjacent track to the reproducing head 26 during information reproduction, and to reduce crosstalk noise included in the reproduction signal.

  FIG. 4 shows an example of the configuration of the recording head 24 and the reproducing head 26 according to the present embodiment. As an example, the recording head 24 may be integrally formed in a slider substrate 58 that forms the slider 28. As an example, the recording head 24 may be formed on the surface of the slider substrate 58 facing the disk medium 20 (disk facing surface 60) so that a part of the recording head 24 is exposed from the disk facing surface 60.

  For example, the recording head 24 may include a recording magnetic pole 62, a return magnetic pole 64, a magnetic yoke 66, and a recording coil 68. The recording magnetic pole 62 and the return magnetic pole 64 are, for example, a thin film-like magnetic material having a high magnetic permeability and disposed substantially perpendicular to the main surface of the disk medium 20. The recording magnetic pole 62 and the return magnetic pole 64 are arranged with a predetermined gap in the recording direction of the disk medium 20 (that is, the tangential direction of the track 40). Each of the recording magnetic pole 62 and the return magnetic pole 64 may have an end face on the disk facing surface 60 side exposed from the disk facing surface 60.

  The magnetic yoke 66 is, for example, a thin film-like magnetic material having a high magnetic permeability, which is disposed substantially parallel to the main surface of the disk medium 20. The magnetic yoke 66 connects the recording magnetic pole 62 and the return magnetic pole 64 at a predetermined distance inside the slider substrate 58 from the disk facing surface 60. The recording coil 68 is wound around the magnetic yoke 66 approximately.

  In such a recording head 24, a recording current is passed through the recording coil 68 during recording. When a recording current is passed through the recording coil 68, the magnetic circuit formed by including the recording magnetic pole 62, the return magnetic pole 64, the magnetic yoke 66, and the soft magnetic layer 44 at a position facing the recording head 24 is shown in FIG. Magnetic flux as shown by the arrow passes through. As a result, the magnetic layer 46 at the position facing the recording head 24 is magnetized in the direction of the magnetic flux because the magnetic flux in the vertical direction passes therethrough. Thus, according to the recording head 24, information can be recorded on the disk medium 20 by the perpendicular magnetic recording method.

  As an example, the reproducing head 26 may be integrally formed in a slider substrate 58 that forms the slider 28. As an example, the reproducing head 26 may be formed on the side of the slider substrate 58 facing the disk medium 20 (disk facing surface 60) so that a part thereof is exposed from the disk facing surface 60.

  The reproducing head 26 includes a first shield 72, a second shield 74, and a magnetoresistive effect element 76. As shown in FIG. 4, the first shield 72 and the second shield 74 are magnetic bodies having a high magnetic permeability disposed substantially perpendicular to the main surface of the disk medium 20. The first shield 72 and the second shield 74 form a gap 78 having a predetermined width in the recording direction of the disk medium 20 (that is, the tangential direction of the track 40). That is, the first shield 72 and the second shield 74 are magnetic bodies provided with a gap 78 between the shields substantially perpendicular to the track 40. Further, as an example, the first shield 72 and the second shield 74 may have their end faces on the disk facing surface 60 side exposed from the disk facing surface 60. According to the first shield 72 and the second shield 74 as described above, it is possible to prevent magnetic fluxes other than the vertical direction from passing through the gap 78.

  FIG. 5 shows a block configuration of signal processing of the disk device 10 according to the present embodiment. The disk device 10 includes a recording head 24, a reproducing head 26, a drive control unit 110, a writing unit 120, and a reading unit 130.

  The drive control unit 110 performs rotation drive control of the disk medium 20 at the time of recording and reproduction, movement control of the arm 30 that moves the recording head 24 and the reproduction head 26 to a position facing the track 40 to be read, and the like. Do. At the time of recording, the writing unit 120 inputs write data to be recorded on the disk medium 20 from, for example, an information processing device, and generates a recording signal corresponding to the input write data. Then, the writing unit 120 supplies the generated recording signal to the recording head 24 and records write data on the disk medium 20.

  The reading unit 130 includes a sampling unit 132 and a data reproduction unit 134. The sampling unit 132 samples a voltage waveform that changes according to a change in electrical resistance of the magnetoresistive effect element 76 in the reproducing head 26 during reproduction. The data reproducing unit 134 reproduces the data recorded on the track 40 to be read from the disk medium 20 based on the shape of the voltage waveform sampled by the sampling unit 132. For example, the data reproducing unit 134 may sample a voltage waveform including a DC response in the sampled voltage waveform, and reproduce the data based on the voltage waveform.

  In the present embodiment, the sampling unit 132 includes a preamplifier unit 140, a variable gain amplifier unit 142, a waveform equalization unit 144, and an AD conversion unit 146. The preamplifier unit 140 detects a change in the electrical resistance of the magnetoresistive effect element 76 in the playback head 26 and outputs a playback signal in which the change in the electrical resistance is represented by a voltage level. The variable gain amplifier unit 142 amplifies the reproduction signal output from the preamplifier unit 140.

  The waveform equalization unit 144 performs waveform equalization on the reproduction signal output from the variable gain amplifier unit 142. As an example, the waveform equalization unit 144 equalizes the reproduction signal according to PR (Partial Response) class transmission path characteristics suitable for the perpendicular magnetization recording type reproduction head 26. For example, the waveform equalizing unit 144 may perform waveform equalization on the reproduction signal according to the transmission path characteristics of the class including the DC response. That is, the waveform equalizing unit 144 performs waveform equalization on a voltage waveform including a direct current response corresponding to the resistance change of the magnetoresistive effect element 76 of the reproducing head 26, so that a signal magnetized with respect to the disk medium 20 is obtained. Reproduce the waveform. The AD conversion unit 146 samples and digitizes the analog reproduction signal waveform-equalized by the waveform equalization unit 144 at a predetermined sampling frequency, and outputs a digital reproduction signal.

  In the present embodiment, the data reproducing unit 134 includes an FIR filter 150 and a Viterbi decoding unit 152. The FIR filter 150 precisely equalizes the digital reproduction signal output from the sampling unit 132. The Viterbi decoding unit 152 restores and outputs the data recorded on the read target track 40 of the disk medium 20 by Viterbi decoding the digital reproduction signal precisely equalized by the FIR filter 150.

  According to the disk device 10 as described above, since low-frequency crosstalk noise from adjacent tracks is reduced, a signal waveform including a DC response is reproduced from the disk medium 20 on which information is recorded by the perpendicular magnetic recording method. The information can be restored.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

1 shows a configuration of a disk device 10 according to an embodiment of the present invention. 2 shows a track 40 of a disk medium 20 according to an embodiment of the present invention. 1 shows a layer structure of a disk medium 20 according to an embodiment of the present invention. 2 shows a configuration of a recording head 24 and a reproducing head 26 according to an embodiment of the present invention. 1 shows a block configuration of signal processing of a disk device 10 according to an embodiment of the present invention. In a magnetic disk recording / reproducing apparatus employing a perpendicular magnetic recording system, when a pattern having the same code is recorded on an adjacent track, a direct current reproduced from the read target track with respect to the continuous number of the same code of the pattern (run length T) Indicates the error rate of the signal including the component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Disc apparatus 20 Disc medium 22 Disc drive part 24 Recording head 26 Playback head 28 Slider 30 Arm 32 Arm drive part 40 Track 42 Substrate 44 Soft magnetic layer 46 Magnetic layer 48 Protective layer 50 Lubricating layer 52 Shut off part 58 Slider substrate 60 Disc Opposing surface 62 Recording magnetic pole 64 Return magnetic pole 66 Magnetic yoke 68 Recording coil 72 First shield 74 Second shield 76 Magnetoresistive element 78 Gap 110 Drive control unit 120 Writing unit 130 Reading unit 132 Sampling unit 134 Data reproducing unit 140 Preamplifier unit 142 Variable Gain Amplifier 144 Waveform Equalizer 146 AD Converter 150 FIR Filter 152 Viterbi Decoder

Claims (5)

A disk medium having a plurality of tracks arranged concentrically;
A recording head for recording information on a track to be written by a perpendicular magnetic recording method;
A reproducing head for reproducing information recorded on a track to be read;
A sampling unit that samples a voltage waveform that changes in accordance with a change in electrical resistance of a magnetoresistive element provided in the read head;
A data reproducing unit for reproducing the data recorded on the read target track based on the shape of the sampled voltage waveform, and
The disk medium has a blocking unit that blocks a magnetic material of each track. The disk medium is
A disk-shaped substrate;
A soft magnetic layer laminated on the substrate;
A magnetic layer laminated on the soft magnetic layer and having each track formed thereon,
The disk device according to claim 1, wherein the blocking unit is provided so as to penetrate the magnetic layer and the soft magnetic layer, and separates the magnetic layer and the soft magnetic layer corresponding to each track by a nonmagnetic material. . The disk medium is
A disk-shaped substrate;
A soft magnetic layer laminated on the substrate;
A magnetic layer laminated on the soft magnetic layer and having each track formed thereon,
2. The disk device according to claim 1, wherein the blocking portion is a non-magnetic material formed in a groove extending from the surface on the magnetic material layer side of the disk medium to a depth of at least a half or more of a track width.   The blocking unit includes the low-frequency noise having a frequency of 1% or less of the sampling frequency of the sampling unit from the surface on the magnetic layer side of the disk medium between the magnetic bodies of the tracks. 2. The disk device according to claim 1, further comprising a non-magnetic material that reaches a predetermined depth so as to suppress the influence exerted within an allowable range. A recording head for recording information on a track to be written by a perpendicular magnetic recording system, a reproducing head for reproducing information recorded on a track to be read, and an electric resistance of a magnetoresistive effect element provided in the reproducing head Provided in a disk device having a sampling unit that samples a voltage waveform that changes in accordance with a change, and a data reproduction unit that reproduces data recorded on a read target track based on the shape of the sampled voltage waveform, and is concentric A disk medium having a plurality of tracks arranged in
A disk medium having a blocking portion for blocking between magnetic bodies of tracks.

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