JP2008310932A - Demagnetizing device and demagnetizing method of magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a demagnetizing device and a demagnetizing method of a magnetic recording medium which are satisfactory in demagnetization efficiency and simple in configuration. <P>SOLUTION: In the demagnetizing device provided with a pair of permanent magnet rows 3a and 3b each formed by arranging a plurality of permanent magnets in a row and a guide 2 on which the magnetic recording medium 1 abuts and runs, the pair of permanent magnet rows 3a and 3b are disposed opposite to each other; magnetic poles of the permanent magnets forming the pair of permanent magnet rows 3a and 3b are disposed so that alternate magnetic fields where the directions of the magnetic fields are repetitively reversed in the row directions of the permanent magnet rows 3a and 3b are formed, and the pair of permanent magnet rows 3a and 3b are disposed so that the interval between the pair of permanent magnet rows 3a and 3b are made wider as the permanent magnet rows advances from an upstream side to a downstream side of a conveyance direction of the magnetic recording medium 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a demagnetizing device and a demagnetizing method for a magnetic recording medium.

  The magnetic recording medium is manufactured by providing a demagnetization process in order to erase the residual magnetization caused by the magnetic field orientation in the manufacturing process. The demagnetization of the magnetic recording medium can be performed by demagnetizing the wide sheet in the coating machine, the demagnetizing of the pancake after cutting, demagnetizing on the tape conveying device after cutting, demagnetizing the cartridge incorporating the magnetic tape. Is common.

  In either case, an electromagnet is often used. For example, demagnetization of a scroll-like (pancake or the like) magnetic recording medium is such that an alternating current is passed through an electromagnet to generate an alternating magnetic field, and the scroll is moved away from the alternating magnetic field. Also, in the demagnetization of a sheet-like magnetic recording medium, a sheet, which is a magnetic recording medium, is moved away through an alternating magnetic field by a device composed of a dedicated degaussing head and a driver that applies an alternating current to the degaussing head. is there.

  These devices incur a cost of current flowing through the electromagnet, and further require a cooling device for cooling the heat generated when an alternating current is passed through the electromagnet and a cooling structure inside the electromagnet. There was a problem of consuming energy.

  On the other hand, a demagnetization method using a permanent magnet that does not generate current costs and consumes cooling energy has been proposed (for example, Patent Documents 1-4).

  Patent Document 1 proposes a multi-pole magnet that is a demagnetizing mechanism of a magnetic ink transfer drum and generates a periodic magnetic field that is attached along the transfer drum and attenuates. Patent Document 2 proposes an apparatus that generates an alternating magnetic field by rotating a pair of rolls, each having a plurality of magnets arranged on the circumference, facing each other.

Patent Document 3 proposes a method in which a plurality of permanent magnets having different magnetic field strengths are arranged facing each other to form a decelerating alternating magnetic field and demagnetize. Patent Document 4 proposes a technique of tilting a magnetic head at a predetermined angle with respect to the tape in order to create a magnetic field strength that gradually decreases as the tape advances.
Japanese Unexamined Patent Publication No. 63-220188 Japanese Patent Laid-Open No. 1-271917 Japanese Patent Laid-Open No. 2-101630 JP-A-9-97402

  However, the technique proposed in Patent Document 1 has a problem in that the multipolar magnets remain in a single row and the magnitude of the magnetic field strength is insufficient. In the technique proposed in Patent Document 2, there is a problem that the apparatus becomes large in order to rotate a roll provided with a magnet and cannot be used when vibration is disliked.

  The technique proposed in Patent Document 3 has a problem that it is difficult to prepare magnets having slightly different magnetic field strengths. In the technique proposed in Patent Document 4, as in the technique proposed in Patent Document 1, there is a problem in that the permanent magnet erasing heads remain in one row and the magnitude of the magnetic field strength is insufficient.

  An object of the present invention is to solve the conventional problems as described above, and to provide a demagnetizing device method and a degaussing method for a magnetic recording medium having a good demagnetizing efficiency and a simple configuration.

  In order to achieve the above object, a degaussing device of the present invention includes a pair of permanent magnet rows in which a plurality of permanent magnets are arranged in a row, and a guide that a magnetic recording medium is in contact with and travels. The permanent magnet rows are arranged to face each other, and the magnetic poles of the permanent magnets forming the pair of permanent magnet rows form an alternating magnetic field in which the direction of the magnetic field is repeatedly reversed in the row direction of the permanent magnet row. The pair of permanent magnet rows are arranged such that the distance between the pair of permanent magnet rows increases from the upstream side to the downstream side in the conveyance direction of the magnetic recording medium. Features.

  The demagnetization method of the present invention is a demagnetization method of a magnetic recording medium in which the magnetic recording medium is demagnetized while conveying the magnetic recording medium, wherein a pair of permanent magnet rows are arranged so as to face each other, and the row of the permanent magnet rows The magnetic poles of the permanent magnets forming the pair of permanent magnet rows are arranged so as to form an alternating magnetic field in which the direction of the magnetic field is repeatedly reversed in the direction from the upstream side to the downstream side in the conveyance direction of the magnetic recording medium The pair of permanent magnet rows are arranged so that the distance between the pair of permanent magnet rows becomes larger toward the head, and the magnetic recording medium is transported between the pair of permanent magnet rows to It is characterized by demagnetizing.

  A first method of manufacturing a magnetic recording medium according to the present invention is a method of manufacturing a magnetic recording medium including a demagnetizing step, wherein the demagnetizing device uses the demagnetizing device for the magnetic recording medium according to the present invention. To do.

  A second magnetic recording medium manufacturing method of the present invention is a magnetic recording medium manufacturing method including a degaussing step, wherein the demagnetizing method uses the demagnetizing method of the magnetic recording medium of the present invention. To do.

  According to the present invention, the demagnetization efficiency is good and the configuration is simple.

  According to the demagnetizing device, demagnetizing method, and manufacturing method of the magnetic recording medium of the present invention, a strong alternating magnetic field can be formed, and this alternating magnetic field can be gradually attenuated, so that the demagnetizing efficiency is improved. Moreover, since the main structure is a permanent magnet and its fixing structure. Configuration is also simplified.

  In the degaussing device of the present invention, the pair of permanent magnet rows are arranged such that the tip surfaces of the permanent magnets and the tip surfaces of the permanent magnets facing the permanent magnets are substantially symmetrical with respect to the symmetry axis. The guide is preferably arranged so that the magnetic recording medium travels at a position substantially coincident with the plane of symmetry. According to this configuration, since the magnetic recording medium travels in a portion where the strength of the magnetic field component in the longitudinal direction is strong, the demagnetization efficiency of the magnetization in the longitudinal direction of the magnetic recording medium is improved.

  Further, the guide is arranged such that, on the upstream side in the conveyance direction of the magnetic recording medium, the magnetic recording medium is biased toward one permanent magnet row of the pair of permanent magnet rows, and the magnetic recording medium is It is preferable that the magnetic recording medium is arranged so that the deviation decreases from the upstream side to the downstream side in the conveyance direction of the magnetic recording medium. According to this configuration, since the magnetic recording medium travels in the part where the magnetic field components in both the longitudinal direction and the thickness direction of the magnetic recording medium are formed, demagnetization in both the longitudinal direction and the thickness direction of the magnetic recording medium is prevented. It becomes possible.

  Moreover, it is preferable that the magnetic forces of the plurality of permanent magnets are substantially the same. According to this configuration, an alternating magnetic field that gradually attenuates can be obtained easily and reliably, and the magnet itself can be easily obtained.

  Each permanent magnet row is preferably fixed to a magnetic yoke. According to this configuration, a stronger magnetic field strength can be obtained, and the positional relationship between the permanent magnet array and the tape guide can be easily adjusted.

  Moreover, it is preferable that the positional relationship between the pair of permanent magnet rows and the guide is adjustable. According to this configuration, an optimal positional relationship can be set according to the degaussing target.

  In the demagnetization method of the present invention, the pair of permanent magnet rows are arranged so that the tip surfaces of the permanent magnets and the tip surfaces of the permanent magnets facing the permanent magnets are substantially symmetrical with respect to the symmetry axis. Preferably, the magnetic recording medium is transported to a position that substantially coincides with the symmetry axis plane. According to this configuration, since the magnetic recording medium travels in a portion where the strength of the magnetic field component in the longitudinal direction is strong, the demagnetization efficiency of the magnetization in the longitudinal direction of the magnetic recording medium is improved.

  In addition, on the upstream side in the transport direction of the magnetic recording medium, the magnetic recording medium is biased toward one of the pair of permanent magnet rows and on the upstream side in the transport direction of the magnetic recording medium. It is preferable that the magnetic recording medium is transported so that the deviation decreases from the downstream side toward the downstream side. According to this configuration, since the magnetic recording medium travels in the part where the magnetic field components in both the longitudinal direction and the thickness direction of the magnetic recording medium are formed, demagnetization in both the longitudinal direction and the thickness direction of the magnetic recording medium is prevented. It becomes possible.

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

(Embodiment 1)
FIG. 1 shows a schematic diagram of a degaussing device according to Embodiment 1 of the present invention. The degaussing device shown in this figure shows an example used for degaussing a magnetic tape that is a magnetic recording medium. The first yoke 4a is provided with a first permanent magnet row 3a in which a plurality of permanent magnets are arranged in a row. Similarly, the second permanent magnet row 3b is provided in the second yoke 4b. The first yoke 4a and the second yoke 4b are opposed to each other, and the tip of each permanent magnet row forming the first permanent magnet row 3a and the tip of each permanent magnet row forming the second permanent magnet row 3b are Opposite.

  The first yoke 4a and the second yoke 4b are made of a material having a high relative magnetic permeability (pure iron, sendust, permalloy, etc.). By arranging the permanent magnet in such a yoke, a stronger magnetic field strength can be obtained. Further, since the yoke and the permanent magnet row can be moved together, the positional relationship between the permanent magnet row and the tape guide as described later can be easily adjusted.

  A tape guide 2 is disposed between the first yoke 4a and the second yoke 4b. The material of the tape guide 2 is a nonmagnetic material such as aluminum, copper, ceramic, or plastic. The magnetic tape 1 is in contact with the guide surface 2a of the tape guide 2 and travels.

  The broken line shown with the code | symbol 6 has shown the axis of symmetry. When the degaussing device is viewed from the side as shown in FIG. 1, the tip surfaces of the permanent magnets constituting the first permanent magnet row 3a of the first yoke 4a and the second permanent of the second yoke 4b opposed thereto. The tip surfaces of the permanent magnets constituting the magnet array 3 b are arranged substantially symmetrically with respect to the symmetry axis surface 6.

  The tape guide 2 is disposed so that the guide surface 2 a of the tape guide 2 substantially coincides with the symmetry axis surface 6. The permanent magnets constituting the first permanent magnet row 3a are arranged such that one magnetic pole is on the first yoke 4a side and the other magnetic pole is on the tape guide 2 side.

  Similarly, each permanent magnet constituting the second permanent magnet row 3b is arranged so that one magnetic pole is on the second yoke 4b side and the other magnetic pole is on the tape guide 2 side. Further, in each of the first permanent magnet row 3a and the second permanent magnet row 3b, the permanent magnets are arranged so that the adjacent magnetic poles are reversed. Thus, an alternating magnetic field is formed in which the direction of the magnetic field is repeatedly reversed in the row direction of the permanent magnet row. Specifically, it is as follows.

  The arrows 7a and 7b in FIG. 1 schematically show the state of the magnetic field. The arrows 7a and 7b are attached to only a part of the permanent magnet row for convenience of illustration, but the state of the magnetic field is the same in any part of the permanent magnet row. The magnetic tape 1 runs in a portion where the magnetic field of the first permanent magnet row 3a and the magnetic field of the second permanent magnet row 3b overlap (a portion where the arrows 7a overlap each other, a portion where the arrows 7b overlap each other). For this reason, the magnetic field in the traveling portion of the magnetic tape 1 is substantially composed of components in the longitudinal direction of the magnetic tape 1.

  As described above, the permanent magnets are arranged so that the adjacent magnetic poles are reversed. For this reason, the direction of the magnetic field is reversed between the arrow 7 a and the arrow 7 b, and the direction of the magnetic field component formed in the longitudinal direction of the magnetic tape 1 is also reversed. That is, the magnetic tape 1 travels in a portion where an alternating magnetic field is formed in which the direction of the magnetic field is repeatedly reversed (rightward and leftward).

  FIG. 2 is an enlarged view of a portion indicated by arrows 7a and 7b in FIG. The magnetic tape 1 and the tape guide 2 are not shown for easy viewing. The point b corresponds to the position of the apex of the lines of magnetic force, and the magnetic tape 1 travels through this portion as described above. At point b, as indicated by reference numeral 10, the magnetic field is substantially composed of components in the longitudinal direction of the magnetic tape 1.

  The point c is a point at a position closer to the permanent magnet row than the vertex among the magnetic field lines. At point c, as indicated by reference numeral 11, a magnetic field directed in the upper right direction is formed. This magnetic field is composed of a component in the longitudinal direction of the magnetic tape 1 as indicated by reference numeral 11a and a component in the thickness direction of the magnetic tape 1 as indicated by reference numeral 11b.

  The magnetic field strength of the permanent magnet is preferably 3000 G or more, and more preferably 5000 G or more. As such a permanent magnet, a neodymium magnet is suitable. The width dimension of the permanent magnet is preferably larger than the tape width of the magnetic tape 1 to be demagnetized.

  Spacers 5 made of a non-magnetic material having a predetermined size are disposed between the permanent magnets of the permanent magnet row as necessary. The thickness of the spacer 5 is not particularly limited, but is preferably 0.1 to 10 mm. This preferred range also takes into account the miniaturization of the degaussing device. That is, as the thickness of the spacer 5 increases, the pitch of the permanent magnet rows also increases. For this reason, when importance is attached to downsizing of the degaussing device, the thickness of the spacer 5 is desirably 10 mm or less. Further, the thickness of the spacer 5 and the presence / absence of the spacer 5 may be set according to the demagnetizing effect, and the configuration may be such that the permanent magnets are in direct contact with each other without the spacer 5 interposed.

  The permanent magnets of the first permanent magnet row 3a and the permanent magnets of the second permanent magnet row 3b are arranged so that the same poles face each other. Thus, by making a pair of permanent magnet row | line | columns oppose, compared with the case where it is not made to oppose, a strong magnetic field can be formed and demagnetization efficiency can be improved.

  Here, the distance between the end portions of the permanent magnets of the first permanent magnet row 3a and the end portions of the permanent magnets of the second permanent magnet row 3b facing the first permanent magnet row 3a is defined as an end-to-end distance d. The distance d between the ends is set so as to increase from the upstream side (left side in FIG. 1) in the traveling direction of the magnetic tape 1 toward the downstream side (right side in FIG. 1). As a result, an alternating magnetic field that gradually attenuates is obtained from the upstream side toward the downstream side.

  As for the change in the distance d between the end portions, as shown in FIG. 1, the arrangement surface of the permanent magnets of the first yoke 4a and the second yoke 4b is a plane, and the distance d between the end portions is changed linearly. Alternatively, the permanent magnet arrangement surface of the first yoke 4a and the second yoke 4b may be a curved surface, and the distance d between the end portions may be changed in a curved shape.

  Further, the end-to-end distance d varies depending on the magnetic field strength of the magnet used and the coercive force (Hc) of the magnetic tape to be demagnetized. For example, it is preferably 1 to 6 mm on the upstream side where the distance d between ends is smallest, and the magnetic field strength in this case is preferably 3000 Oe or more, and preferably 5000 Oe or more. Further, 10 to 30 mm is preferable on the downstream side where the distance d between ends is the largest, and the magnetic field strength in this case is preferably 50 Oe or less, and more preferably 20 Oe or less.

  Moreover, it is preferable that the magnetic force of each permanent magnet is substantially the same. According to this configuration, since the magnetic field strength changes in accordance with the change in the distance d between the ends, the alternating magnetic field that gradually decreases as described above can be obtained easily and reliably. In addition, the magnet itself can be easily obtained.

  The tape guide 2 is disposed between the first permanent magnet array 3a and the second permanent magnet array 3b that are disposed to face each other, and the length thereof is the length of the first permanent magnet array 3a and the second permanent magnet array 3b. Or larger than that.

  Next, the operation of the degaussing device according to the present embodiment will be described. In FIG. 1, a magnetic tape 1 unwound from a take-up reel (not shown) and taken up by a take-up reel (not shown) is conveyed into the demagnetizer from the left side of FIG.

  At this time, as shown in FIG. 1, the magnetic tape 1 is preferably set so as to be wound around one end of the tape guide 2 at an angle θ and to enter the magnetic field of the degaussing device. In this way, by providing the angle θ, the accompanying air accompanying the magnetic tape 1 being transported is blocked at the entrance of the tape guide 2, and the magnetic tape 1 can travel on the table guide 2 stably.

  On the entrance side of the demagnetizer, that is, the upstream side in the transport direction of the magnetic tape 1 (left side in FIG. 1), the end portion distance d is small, and a strong magnetic field is formed. The magnetic field strength in the vicinity of the entrance is preferably larger than the coercive force (Hc) of the magnetic tape 1, and more preferably twice or more the coercive force. As described above, usually, the magnetic field intensity near the entrance is preferably 3000 Oe or more, and more preferably 5000 Oe or more. The magnetic field strength near the exit is preferably close to 0 Oe, usually 50 Oe or less, and more preferably 20 Oe or less.

  As described above, an alternating magnetic field that gradually decays from the upstream side to the downstream side in the transport direction of the magnetic tape 1 is obtained between the first permanent magnet row 3a and the second permanent magnet row 3b. Further, an alternating magnetic field in which the magnetic field component in the longitudinal direction is repeatedly reversed is formed in the traveling portion of the magnetic tape 1. This demagnetizes the longitudinal magnetization of the magnetic tape.

  FIG. 3 shows an example of the magnetic field intensity on the tape guide 2 in the degaussing device shown in FIG. The broken line indicates the strength of the magnetic field component in the longitudinal direction (X direction) of the magnetic tape 1. The solid line indicates the strength of the magnetic field component in the thickness direction (Y direction) of the magnetic tape 1.

  The magnetic field indicated by the broken line is an alternating magnetic field and gradually attenuates toward the downstream side. As described above, the end-to-end distance d in FIG. 1 increases from the demagnetizer inlet side to the outlet side, that is, from the upstream side to the downstream side in the conveyance direction of the magnetic tape 1 (from the left side to the right side in FIG. 1). It is because it has become.

  On the other hand, as indicated by the solid line, in the thickness direction of the magnetic tape 1, almost no magnetic field is formed from the upstream side to the entire downstream side. As described above, the degaussing device shown in FIG. 1 is arranged such that the guide surface 2a of the tape guide 2 substantially coincides with the symmetry axis surface 6, so that the magnetic tape 1 has the thickness of the magnetic tape 1. This is for traveling in a position where the magnetic field component in the direction is hardly formed.

  That is, almost no magnetic field component in the thickness direction of the magnetic tape 1 is formed in the traveling portion of the magnetic tape 1, and an alternating magnetic field in which the magnetic field component in the longitudinal direction is repeatedly reversed is formed. As a result, as described above, the magnetization in the longitudinal direction of the magnetic tape is efficiently demagnetized.

  In the above description, the tip surfaces of the permanent magnets constituting the pair of permanent magnet rows are arranged substantially symmetrically with respect to the symmetry axis surface 6, and the guide surface 2 a of the tape guide 2 is substantially aligned with the symmetry axis surface 6. The example in which they are arranged so as to coincide with each other has been described. Even if the tip surfaces of the permanent magnets are not arranged completely symmetrically with respect to the symmetry axis plane 6, the positions of the symmetry axis plane 6 are arranged so that the strength of the magnetic field component in the longitudinal direction is increased. This is because it does not change to a strong part. Similarly, even if it is not a position that completely coincides with the symmetry axis plane 6 but a position that substantially coincides, it does not change to a portion where the strength of the magnetic field component in the longitudinal direction is strong.

  On the other hand, depending on the degree of setting of the arrangement position of each member, the magnetic tape 1 may travel in a portion where a magnetic field component in the thickness direction of the magnetic tape 1 is formed, for example, a portion c in FIG. . Even in such a case, since the magnetic field component in the longitudinal direction of the magnetic tape 1 is secured, demagnetization of the magnetization in the longitudinal direction of the magnetic tape 1 is possible as described in the second embodiment below. is there.

(Embodiment 2)
FIG. 4 shows a schematic diagram of a degaussing device according to Embodiment 2 of the present invention. The demagnetizing device shown in FIG. 4 has the same components as the degaussing device in FIG. 1, but the arrangement of the tape guide 2 is different from the demagnetizing device in FIG. Components having the same configurations as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The arrangement of the tape guide 2 of the degaussing device shown in FIG. 4 corresponds to a state in which the tape guide 2 in FIG. 1 is rotated in the clockwise direction (arrow a direction) around the point A. Point A is a point on the symmetry axis plane 6 corresponding to the downstream end in the transport direction of the magnetic tape 1 among the ends of the permanent magnet rows 3a and 3b.

  Therefore, the tape guide 2 in FIG. 4 is biased toward the first permanent magnet array 3a side on the upstream side in the conveyance direction of the magnetic tape 1 compared to the arrangement in FIG. 1, and this bias is directed from the upstream side to the downstream side. It will gradually decrease. For this reason, the magnetic tape 1 travels at a position deviated from the position of the point b corresponding to the apex of the magnetic field lines as shown in FIG. That is, the magnetic tape 1 passes through a portion where a magnetic field is constituted by a component in the longitudinal direction of the magnetic tape 1 and a component in the thickness direction of the magnetic tape 1.

  According to this configuration, an alternating magnetic field that attenuates toward the downstream side in both the longitudinal direction of the magnetic tape 1 and the thickness direction of the magnetic tape 1 is obtained in the traveling portion of the magnetic tape 1. This will be specifically described with reference to FIG.

  FIG. 5 shows an example of the magnetic field intensity on the tape guide 2 in the degaussing device shown in FIG. The broken line indicates the strength of the magnetic field component in the longitudinal direction (X direction) of the magnetic tape 1. The solid line indicates the strength of the magnetic field component in the thickness direction (Y direction) of the magnetic tape 1.

  The magnetic field component in the longitudinal direction indicated by the broken line is an alternating magnetic field and gradually attenuates toward the downstream side. This is because, in the demagnetizer of FIG. 3 as well, as in the demagnetizer of FIG. 1, the end portion distance d does not change from the demagnetizer inlet side toward the outlet side.

  In the configuration of FIG. 4, as described above, the tape guide 2 is arranged so as to be biased toward the first permanent magnet row 3a. Therefore, the guide surface 2a is at a position where a magnetic field component in the thickness direction of the magnetic tape 1 is formed. Also in the configuration of FIG. 4, the permanent magnets adjacent to each other in the permanent magnet row are arranged so that their magnetic poles are reversed. For this reason, the magnetic field component in the thickness direction of the magnetic tape 1 is also formed with an alternating magnetic field in which the direction of the magnetic field component is repeatedly reversed (upward and downward), similarly to the magnetic field component in the longitudinal direction of the magnetic tape 1. Become.

  Further, since the bias of the guide surface 2a decreases as it goes downstream in the magnetic tape transport direction, the magnetic field strength of the magnetic field component in the thickness direction of the magnetic tape 1 at the position of the guide surface 2a increases toward the downstream side. Will be reduced. The solid line in FIG. 5 shows this state, and the alternating magnetic field in the thickness direction of the magnetic tape 1 is gradually attenuated toward the downstream side.

  That is, in the configuration in which the guide surface 2a is offset from the symmetry axis plane 6 as shown in FIG. 4, an alternating magnetic field that attenuates toward the downstream side is obtained in both the X direction and the Y direction as shown in FIG. Therefore, it is possible to demagnetize not only the longitudinal direction of the magnetic tape 1 but also the magnetization of the magnetic tape 1 in the thickness direction. When demagnetization in the thickness direction is required, it is necessary to demagnetize in the thickness direction again. Disappear.

  In addition, since the one where the bias of the guide surface 2a is large is preferable and it is preferable to approach a magnet row | line | column, it is preferable to arrange | position so that the guide surface 2a may be biased to the 1st permanent magnet row | line | column 3a side facing the guide surface 2a.

(Embodiment 3)
FIG. 6 shows a schematic diagram of a degaussing device according to Embodiment 3 of the present invention. The present embodiment relates to a position adjusting mechanism for components of the demagnetizer and can be used in each of the above embodiments. Components having the same configurations as those of the respective embodiments are denoted by the same reference numerals and description thereof is omitted.

  In the configuration of FIG. 6, the first yoke 4 a and the second yoke 4 b are fixed via the first fixing jig 8 and the second fixing jig 9. More specifically, on the upstream side in the conveyance direction of the magnetic tape 1, the fixing screws 8a and 8b are tightened at the positions of the slit holes of the first fixing jig 8, and the first yoke 4a and the second yoke 4b Is fixed. Similarly, on the downstream side in the conveyance direction of the magnetic tape 1, the fixing screws 9a and 9b are fastened to the positions of the slit holes of the second fixing jig 9, and the first yoke 4a and the second yoke 4b are fixed. Yes.

  According to this configuration, the facing distance between the first permanent magnet row 3a and the second permanent magnet row 3b can be freely set on the upstream side and the downstream side in the transport direction of the magnetic tape 1 by loosening each fixing screw. Can be changed.

  This makes it possible to adjust the positional relationship between the first permanent magnet row 3a, the second permanent magnet row 3b, and the tape guide 2. For example, the setting can be changed from the setting shown in FIG. 1 to FIG.

  4 has been described as an example in which the tape guide 2 is rotated while maintaining the positional relationship between the first permanent magnet row 3a and the second permanent magnet row 3b in the setting of FIG. Although the adjusting mechanism of the third embodiment does not adjust the position of the tape guide 2, the adjustment of the positions of the first permanent magnet row 3a and the second permanent magnet row 3b can be changed from the setting of FIG. The change to the setting of 4 becomes possible.

  Further, it is only necessary to adjust the positional relationship between the first permanent magnet row 3a, the second permanent magnet row 3b, and the tape guide 2, and not only the example of FIG. 6 but also a known fixing method can be used.

  As described above, the demagnetizing device and the demagnetizing method of the magnetic recording medium have been described. However, these can be used in a demagnetizing process included in a series of manufacturing processes of the magnetic recording medium.

  According to the present invention, a demagnetizing device and a demagnetizing method for a magnetic recording medium having good demagnetization efficiency and a simple configuration can be obtained. Therefore, the present invention is useful as a demagnetizing device and a demagnetizing method in a manufacturing process of a magnetic recording medium.

1 is a schematic diagram of a demagnetizing device according to Embodiment 1 of the present invention. The enlarged view of the part which attached | subjected the arrows 7a and 7b of FIG. The figure which shows an example of the magnetic field intensity on the tape guide 2 of the degaussing apparatus which concerns on Embodiment 1 of this invention. Schematic of the degaussing apparatus which concerns on Embodiment 2 of this invention. The figure which shows an example of the magnetic field intensity on the tape guide 2 of the degaussing apparatus which concerns on Embodiment 2 of this invention. Schematic of the degaussing apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic tape 2 Tape guide 2a Guide surface 3a 1st permanent magnet row | line | column 3b 2nd permanent magnet row | line | column 4a 1st yoke 4b 2nd yoke 5 Nonmagnetic spacer 6 Symmetrical axial surface 8 1st fixing jig 8a, 8b, 9a, 9b Fixing screw 9 Second fixing jig

Claims (11)

A pair of permanent magnet rows in which a plurality of permanent magnets are arranged in rows;
A guide that the magnetic recording medium contacts and travels,
The pair of permanent magnet rows are arranged to face each other,
The magnetic poles of the permanent magnets forming the pair of permanent magnet rows are arranged to form an alternating magnetic field in which the direction of the magnetic field is repeatedly reversed in the row direction of the permanent magnet rows,
The pair of permanent magnet arrays are arranged such that the distance between the pair of permanent magnet arrays increases from the upstream side to the downstream side in the conveyance direction of the magnetic recording medium. Demagnetizer.   The pair of permanent magnet rows are arranged such that the tip surfaces of the permanent magnets and the tip surfaces of the permanent magnets opposed to the permanent magnets are substantially symmetrical with respect to a symmetry axis surface, The demagnetizing device for a magnetic recording medium according to claim 1, wherein the magnetic recording medium is disposed so as to run in a position substantially coinciding with the plane of symmetry.   The guide is biased toward one of the pair of permanent magnet rows on the upstream side in the conveyance direction of the magnetic recording medium, and the magnetic recording medium is the magnetic recording medium. The demagnetizing device for a magnetic recording medium according to claim 1, wherein the bias is arranged so that the deviation decreases from an upstream side to a downstream side in a conveyance direction of the medium.   The demagnetizing device for a magnetic recording medium according to claim 1, wherein the plurality of permanent magnets have substantially the same magnetic force.   The demagnetizing device for a magnetic recording medium according to claim 1, wherein each of the permanent magnet rows is fixed to a magnetic yoke.   The demagnetizing device for a magnetic recording medium according to claim 1, wherein a positional relationship between the pair of permanent magnet rows and the guide is adjustable. A demagnetizing method of a magnetic recording medium for demagnetizing the magnetic recording medium while conveying the magnetic recording medium,
Arrange a pair of permanent magnet rows to face each other,
The magnetic poles of the permanent magnets forming the pair of permanent magnet rows are arranged so as to form an alternating magnetic field in which the direction of the magnetic field is repeatedly reversed in the row direction of the permanent magnet rows,
Arranging the pair of permanent magnet rows so that the interval between the pair of permanent magnet rows is increased from the upstream side to the downstream side in the conveyance direction of the magnetic recording medium,
A method of demagnetizing the magnetic recording medium, wherein the magnetic recording medium is demagnetized by conveying the magnetic recording medium between the pair of permanent magnet arrays.   The pair of permanent magnet rows are arranged so that the tip surfaces of the permanent magnets and the tip surfaces of the permanent magnets facing the permanent magnets are substantially symmetrical with respect to the symmetry axis, and substantially coincide with the symmetry axis. The method for demagnetizing a magnetic recording medium according to claim 1, wherein the magnetic recording medium is transported to a position to be moved.   On the upstream side in the conveyance direction of the magnetic recording medium, the magnetic recording medium is biased toward one permanent magnet row of the pair of permanent magnet rows, and downstream from the upstream side in the conveyance direction of the magnetic recording medium. 2. The method of demagnetizing a magnetic recording medium according to claim 1, wherein the magnetic recording medium is transported so that the deviation decreases toward the side.   A method for manufacturing a magnetic recording medium including a demagnetizing step, wherein the demagnetizing step uses the demagnetizing device for a magnetic recording medium according to any one of claims 1 to 6. .   A method of manufacturing a magnetic recording medium including a demagnetizing step, wherein the method of demagnetizing a magnetic recording medium according to claim 7 is used in the demagnetizing step. .

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