JP4799571B2 - Magnetic data eraser - Google Patents

Description

  The present invention relates to a magnetic data erasing apparatus, and more specifically, to a magnetic data erasing apparatus desirable in an era in which a parallel magnetic recording medium and a perpendicular magnetic recording medium coexist.

  Magnetic recording media such as magnetic tapes and fixed disks can write and store large amounts of data, and are therefore used in large quantities in all fields of modern society. When the magnetic recording medium whose storage deadline has passed is discarded, there is a risk of leakage of personal information, and thus the written data must be completely erased. Many devices have been proposed for erasing magnetic data on a magnetic recording medium. For example, a method has been proposed in which a magnetic tape is stored in an air-core coil and a sinusoidal alternating current is applied to the air-core coil so that an alternating magnetic field with a gradually decreasing peak value is applied to the magnetic tape to erase magnetic data. (Patent Document 1).

In order to erase the magnetic data of a large magnetic tape, it is necessary to form a high magnetic field in an air-core coil having a large space. For this reason, it is necessary to enlarge the apparatus including a capacitor of a power supply unit. However, since the product value decreases when the apparatus is enlarged, proposals have been made to suppress the increase in size. For example, there has been proposed a device that partially stores a large magnetic tape in an air-core coil, applies an alternating attenuation magnetic field, and erases the magnetic data of the entire magnetic tape while shifting the position (Patent Document 2). According to such an apparatus, it is possible to erase data on a large magnetic tape using a relatively small coil or capacitor. In addition, an apparatus for erasing magnetic data written on a hard disk instead of a magnetic tape has been proposed (Patent Document 3).
JP 61-170904 A JP-A-2-132604 Utility model registration No. 3083683

  In the above prior invention, although there is a great difference in the concept of the magnetic data erasing magnetic field time pattern, the easy axis of magnetization of the storage medium material is arranged parallel to the surface of the plate-like magnetic recording medium, and the recording medium This is common in that binary (digital) information is recorded by making the direction of magnetization of the parallel or antiparallel to the magnetization easy axis direction. These are all horizontal magnetic recording systems. Due to recent technological advances in magnetic recording medium materials, a perpendicular magnetic storage type recording medium capable of recording at a higher density than the horizontal magnetic recording type has been put into practical use. In the perpendicular magnetic recording method, binary information is stored by arranging the easy magnetization axis of the recording medium material perpendicular to the plate surface and making the magnetization direction of the recording medium parallel or antiparallel to the easy magnetization axis direction. . Since the storage device of the perpendicular magnetic recording system can be downsized, its use is rapidly expanding. On the other hand, the use of the conventional horizontal magnetic recording medium is still continued due to the low price. Therefore, a horizontal magnetic recording type recording medium and a perpendicular magnetic recording type recording medium coexist in the present and the future.

  As described above, in the era when the horizontal magnetic recording medium and the perpendicular magnetic recording medium coexist, what kind of magnetic data erasing device is desired is currently being searched for, and it is currently unknown. In other words, it is unclear what concept the magnetic data erasing apparatus should be configured with. In the present invention, in an era where horizontal magnetic recording media and perpendicular magnetic recording media coexist, magnetic data can be securely erased by a single operation without making a distinction between horizontal magnetic recording media and perpendicular magnetic recording media. An object of the present invention is to provide a magnetic data erasing apparatus capable of performing the above. The horizontal recording method or the vertical recording method may be abbreviated as a horizontal method or a vertical method.

The magnetic data erasing apparatus of the present invention is a magnetic data erasing apparatus for erasing the magnetic data of the horizontal and vertical magnetic recording media. The apparatus includes a storage unit for storing a magnetic recording medium, a coil that is positioned to include the storage unit and generates a magnetic field for erasing magnetic data, and a resin bobbin around which the coil is wound. , and one or more capacitors for storing charge for supplying current to one coil, and the thyristor which is located between one coil and one or more capacitors, thyristor and coil And a diode connected in the forward direction from the negative side of the coil to the positive side of the coil, and one operation switch for operating the magnetic data erasing device. The coil is arranged such that the axis direction of one coil forms an angle of more than 0 ° and less than 90 ° with the direction perpendicular to the plate surface of the magnetic recording medium housed in the storage unit. The electrical resistance is 0.2 mΩ to 150 mΩ, the inductance is 0.3 mH to 1.3 mH, and 1 / (L · C) ^1/2 is in the range of 250 (1 / second) to 650 (1 / second). And the capacitance of one or more capacitors is 7000 μF or more, and the thyristor is turned on by one on operation of the operation switch, and the charge accumulated in one or more capacitors is stored. To generate a pulse magnetic field for erasing magnetic data in both the parallel and vertical directions of the magnetic recording medium stored in the storage unit in one coil. In the center part of the shaft core, Is the peak value of the flux density 0.6T～1.2T, and the magnetic flux density 0.6T or more duration to form a pulsed magnetic field which is 3Ms～35ms, the electromagnetic force by the pulse magnetic field in the use of multiple impact In order to withstand this, the resin bobbin is characterized in that it is a bobbin formed by processing resin plates into a fitting shape and fitting them together.

  According to the above configuration, even if the magnetic recording medium is not known whether it is a horizontal method or a vertical method, the magnetic recording medium is simply stored in the storage unit and turned on once. Magnetic field components are generated in the plane parallel direction and the vertical direction, and magnetic data can be erased reliably. In this case, there is no need to use two types of magnetic data erasing devices or to determine the recording method of the magnetic recording medium, so that the efficiency of the erasing operation is not hindered and the personal information is not erased. Risk can be reduced. A magnetic recording medium is identified only by a model code, and unless it is a trader in the distribution process, it cannot be easily discriminated whether it is a horizontal system or a vertical system only by a model code. Since the person who operates the magnetic data erasing device is not a trader in the distribution process of the magnetic recording medium, the recording method cannot be easily determined only by the model code. The above-mentioned magnetic data erasing device states that, “In the era when horizontal magnetic recording media and perpendicular magnetic recording media coexist, the operator of the magnetic data erasing device does not know the magnetic recording method of the magnetic recording medium to be erased. It is a magnetic data erasing device created based on the concept of “data can be erased”. Note that “horizontal” or “vertical” in the horizontal method or the vertical method means the same as parallel or orthogonal to the surface of the recording medium, and is independent of the direction of the gravitational field.

Since the axial center direction of the one coil is arranged so as to form an angle of more than 0 ° and less than 90 ° with the direction perpendicular to the plate surface of the magnetic recording medium housed in the storage unit, one coil The magnetic recording medium is obliquely arranged inside the magnetic recording medium so that the direction of the magnetic field is inclined from the vertical direction of the plate surface of the magnetic recording medium, and both the plate surface parallel direction component and the vertical direction component are generated by one pulse magnetic field. be able to. Even with this configuration, the magnetic data on the magnetic recording medium can be securely erased without knowing whether the recording method is parallel or perpendicular.
In addition, since one end is connected between the thyristor and the coil and a diode is connected in the forward direction from the negative side of the coil to the positive side of the coil, the electric charge discharged by the capacitor is a transient current. After flowing through the coil and forming the first pulse magnetic field, it also flows into the negative electrode of the capacitor. However, when a certain amount of charge is accumulated on the negative electrode side and the potential on the negative electrode side increases, the positive side of the coil, that is, the capacitor It also flows to the positive electrode side. For this reason, since charge is replenished from the negative side of the coil while discharging from the positive electrode of the capacitor, the duration of the pulse current flowing through the coil becomes longer, and as a result, the duration of the pulse magnetic field also becomes longer. In order to destroy the magnetization arrangement of the magnetic data, it is preferable that the duration of the pulse magnetic field is long, and the magnetic data can be erased reliably. In addition, such an arrangement of the diode can avoid a situation where a high reverse voltage is applied to the capacitor after the electric charge is discharged, and the life of the capacitor can be extended. With a very simple element called a diode, it is possible to obtain the above two important actions (extension of the magnetic field duration and long life of the capacitor). This diode can naturally be replaced by various circuits or elements having a rectifying action.
The one coil is formed of a rectangular enamel wire, and has an electric resistance of 0.2 mΩ to 150 mΩ, an inductance of 0.3 mH to 1.3 mH, and 1 / (L · C) ^1/2 of 250 (1 / Second) to 650 (1 / second), and the capacitance of one or more capacitors is 7000 μF or more. As is well known here, L of 1 / (L · C) ^1/2 is the inductance of the coil and C is the capacitance of the capacitor, so 1 / (L · C) ^1/2 is Needless to say, it is a determined index.
By using a flat wire for the coil winding, the space factor can be improved. As a result, the current density of the coil can be increased, and as a result, a high magnetic flux density can be formed in the air core (housing).
The capacitance of the capacitor determines the peak value of the transient current, determines the peak value of the strength of the pulsed magnetic field that is substantially in direct proportion to the current, and determines the duration of the magnetic flux density above a predetermined value together with the coil inductance. By increasing the capacitance of the capacitor to 7000 μF or more, a pulse magnetic field having a high magnetic flux density peak value can be formed in the air core (storage part) of the coil, and the duration of the magnetic flux density exceeding the predetermined value can be increased. it can. When erasing magnetic data, it is necessary to continue the strong magnetic field for the time required to force the magnetic array to penetrate into the magnetic recording part on which the magnetic array corresponding to the digital signal is formed, and forcibly align the magnetization array. There is. When 1 / (L · C) ^1/2 is smaller, the width (duration) of the pulse-like transient current can be increased, and by setting the above range, the magnetic data of various magnetic recording media can be erased reliably. can do. If 1 / (L · C) ^1/2 is less than 250 (1 / second), the capacitance of the capacitor and the inductance of the coil must be increased. It becomes an appropriate large-scale configuration. On the other hand, if 1 / (L · C) ^1/2 exceeds 650 (1 / second), the duration of the pulse magnetic field becomes too short, and the magnetization arrangement cannot be completely destroyed. Furthermore, by ensuring the coil inductance and setting the coil electrical resistance to 150 mΩ or less, the initial peak magnetic flux density can be prevented from abruptly decreasing, that is, the duration can be shortened, and the magnetic data can be securely erased. Can be promoted. The electrical resistance of the coil cannot be made zero as long as the copper wire is used, and even if it is as low as possible while securing the inductance of the coil, the limit is 0.2 mΩ, so 0.2 mΩ is the lower limit.
By having the above structure, the above coil has, for example, a peak value of magnetic flux density of 0.4T to 1.2T and a magnetic flux density of 0.4T at the central portion of the shaft core. A pulse magnetic field having a duration of 4 ms to 45 ms is formed. Above the pulsed magnetic field is sufficiently deep penetration into the magnetic recording unit, to change the direction of magnetization, Oh the case of predetermined as a reference example Gereba, magnetic flux density 0.4T or more duration, 4 ms or more is required is there. When the duration of 0.4T or more is less than 4 ms, the pulse magnetic field does not penetrate deeply enough, and even if the magnetization direction starts to change, it does not change completely. When the duration of the pulse magnetic field ends, the magnetic field is applied. The previous magnetization array is restored and the destruction of the magnetic data is incomplete. Some of the magnetic recording medium is also one having a magnetic recording portion formed of hard material and the direction change of the magnetization, ensures magnetic data by the onset Ming such a magnetic recording unit one operation directed to also is intended to erase the magnetic flux density peak must be at least 0.6 T. In that case, the duration of the magnetic flux density of 0.6 T or more is 3 ms or more .

The peak value of the magnetic flux density of the pulse magnetic field is 0.6 T or more. However, if it is too high, the capacitor capacity, the impact load at the time of generation of the pulse magnetic field, etc. become excessive, and the harmful effect becomes large. The following. Further, the duration of 0.6T or more is 35 ms or less. When such a pulse magnetic field is generated, a large electromagnetic force is instantaneously generated in the coil. For this reason, a large impact is applied to the bobbin around which the coil winding is wound, and a rigid structure using metal or the like is deformed or cracked and cannot be used many times. The durability of the bobbin can be improved by combining a resin plate that can be elastically deformed and has sufficient strength. A general resin plate may be used, but a resin plate having a high strength, for example, an ABS (acrylonitrile-butadiene-styrene) resin plate is preferably used. By using the assembled bobbin by laser processing the ends of the resin plates into each other and using the assembled bobbin, the resin plate is restored after being deformed.

  According to the above configuration, the pulse magnetic field is a magnetic field with sufficient strength for erasing magnetic data in any of the above-described both types of magnetic recording media, and the magnetic field can be reliably detected by a single ON operation. Data can be erased.

  The above coil and capacitor allow a high magnetic field to penetrate from the surface of a magnetic recording unit such as a hard disk to a predetermined depth so as not to end the fluctuation of the magnetization direction. As a result, it is possible to reliably destroy the digitized magnetization array in the magnetic recording unit and erase the magnetic data. Further, heat generation in the coil when magnetic data erasing is repeatedly performed continuously can be suppressed, and durability can be improved.

  You may make it the structure arrange | positioned so that the axial center direction of said coil may make the angle in the range of 45 degrees +/- 35 degrees with respect to a plate surface perpendicular | vertical direction. As a result, the magnetic recording medium stored in the storage unit can generate a magnetic field having the same strength so as to correspond to the case of either method without biasing to either the horizontal method or the vertical method. it can. The angle range is as wide as 10 ° to 80 °. However, as will be described later, the change in the direction of the magnetic field toward the easy magnetization direction of the magnetic recording medium corresponds to a wide angle range in an oblique arrangement. be able to. However, from the viewpoint of generating an equivalent magnetic field in any method, the above range is preferably 45 ° ± 25 °.

  The magnetic data erasing device in which one coil is inclined includes an installation position of the storage unit when a magnetic recording medium is installed outside the coil, and an erasure position of the storage unit when a pulse magnetic field is applied to the coil. The storage unit moving mechanism can be provided so that the storage unit can move. As a result, the accuracy of the inclination of the magnetic recording medium can be improved, and magnetic field components exactly as intended can be generated in the plate surface parallel direction and the plate surface vertical direction. In addition, the operability when mounting the magnetic recording medium can be improved.

  In the magnetic data erasing apparatus described above, a triac can be used in the current path for charging the capacitor. With this configuration, a large current can flow from the general power supply to the capacitor, so the capacitor can be charged in a short time, and it contributes greatly to improving work efficiency in erasing a large number of magnetic recording media. Can do. In addition, the capacitor is lowered from the optimal charging state due to electric leakage after charging, but the triac can automatically replenish by taking in the voltage of the capacitor, thus avoiding a situation where much time is spent for supplementary charging by greatly reducing the charge. it can. Further, the step-up transformer may not be disposed in the current path for charging the capacitor. If a transformer is incorporated in a charging circuit and used for boosting, charging takes a very long time, and the efficiency of repeated erasing operations is hindered. For this reason, it is better not to use the transformer in the charging circuit if possible.

  Unlike the present invention, in a magnetic data erasing apparatus that is a reference of the present invention, a parallel magnetic field coil that generates a magnetic field in a direction parallel to the plate surface of the magnetic recording medium stored in the storage unit, and the parallel magnetic field coil A perpendicular magnetic field coil having an axis perpendicular to the axis and generating a magnetic field in a direction perpendicular to the plate surface of the magnetic recording medium can be provided. With this configuration, in the case of a horizontal type magnetic recording medium, the parallel direction magnetic field coil is the main share of erasure, and in the case of the vertical type magnetic recording medium, the vertical direction magnetic field coil is the main share of erasure, The magnetic data on the magnetic recording medium can be erased without the operator knowing which type of magnetic recording medium. The vertical magnetic field coil is electrically connected in series to the first portion and the first portion, has the same axial direction as the first portion, and is spaced from the first portion. It has the 2nd part located in an open position, and the storage part can take the composition provided between the 1st part and the 2nd part of a coil. As a result, a vertical magnetic field having a sufficient strength can be generated in the vertical magnetic field coil. The capacitor includes a parallel magnetic field capacitor connected in parallel to the parallel magnetic field coil and a vertical magnetic field capacitor connected in parallel to the vertical magnetic field coil. As discharge elements for discharging electric charge, a parallel magnetic field thyristor for flowing electric charge from the parallel magnetic field capacitor to the parallel magnetic field coil, and a vertical magnetic field thyristor for flowing electric charge from the vertical magnetic field capacitor to the vertical magnetic field coil Can be provided. With this configuration, it is possible to reliably control the current flow to the two coils almost instantaneously or simultaneously with a single ON operation while obtaining a simple circuit configuration. In addition, a control unit that performs control for causing current to flow in the parallel and vertical magnetic field coils is provided, and the control unit is configured to switch the parallel magnetic field thyristor and the vertical magnetic field thyristor by turning on the operation switch once. It is possible to adopt a configuration in which control is performed so as to conduct at a predetermined time or simultaneously. As a result, the operator can perform the work with the same feeling and the same work efficiency as the conventional magnetic data erasing work.

  According to the magnetic data erasing apparatus of the present invention, a function desirable for consumers is given in an era in which a horizontal magnetic recording medium and a perpendicular magnetic recording medium coexist. That is, magnetic data can be reliably erased by one ON operation without determining whether the magnetic recording medium to be erased is a vertical type or a horizontal type.

(Point of the present invention)
(1) Magnetic Recording Medium FIG. 1 is a diagram showing a hard disk that is a magnetic recording medium. In the hard disk 51, a magnetic data magnetization array is formed along a spiral track 58. The spiral track 58 is formed as a disk that rotates around the rotation shaft 57. The magnetic head 59 tracks the track and writes and reads magnetic data in accordance with the rotation of the disk. Writing magnetic data is the same as forming an array of parallel magnetization (for example, corresponding to 0) or antiparallel magnetization (corresponding to 1 when parallel is 0) for each unit region along the easy axis direction. is there. Reading is the same as detecting the above-described magnetization arrangement. The hard disk 51 shown in FIG. 1 has a general structure used for both the vertical recording method and the horizontal recording method. In the case of the horizontal recording method, the direction of parallel or antiparallel magnetization formed along the track 58 is along the direction of the track in the xy plane. On the other hand, in the case of the perpendicular recording system, the direction of the parallel or antiparallel magnetization is the z direction, that is, the direction perpendicular to the track surface.

  FIG. 2 is a cross-sectional view showing a magnetization arrangement of a hard disk 51 which is a horizontal recording type recording medium. Various underlayers are formed on the glass substrate 52, and a horizontal magnetization arrangement layer 55 is disposed on the underlayer. A protective film 56 is disposed on the magnetization arrangement layer 55. When viewed in conjunction with FIG. 1, this horizontal parallel or anti-parallel magnetization is along a spiral track 58. The easy axis direction of the unit region varies depending on which part of the spiral is located.

  FIG. 3 is a cross-sectional view illustrating the magnetization arrangement of the hard disk 51, which is a perpendicular recording type recording medium. A thick soft magnetic layer 53 is disposed on a glass substrate 52, and a magnetization arrangement layer 55 is provided thereon with a base layer interposed therebetween, and is covered with a protective film 56. The parallel or antiparallel magnetization directions of the magnetization array are perpendicular to the xy plane which is the track plane, that is, aligned in the z direction. In the perpendicular recording type hard disk 51, since a magnetic field is perpendicularly applied to the thin planar recording layer 55 in writing or the like to form an array of parallel magnetization and antiparallel magnetization, the demagnetizing field is large and the magnetic field is difficult to enter. The magnetic layer 53 is provided below the recording layer 55 so that the demagnetizing field does not substantially become a problem.

  For the perpendicular recording type hard disk 51 as described above, the pulse magnetic field is applied perpendicular to the xy plane, that is, in the z direction as described above. Since this pulse magnetic field also has the soft magnetic layer 53, the demagnetizing field in the recording layer 55 becomes small, and a pulse magnetic field with a high magnetic flux density can be reliably applied in the vertical direction. In the perpendicular recording type hard disk 51, the parallel or antiparallel magnetization is perpendicular at any position on the track. As described above, since a perpendicular magnetic field is applied to the perpendicular recording type hard disk 51, magnetic data is not easily erased depending on the track position, and the pulse magnetic field has a magnetic flux density of a predetermined value or more and a continuation. If time is available, the magnetic data can be securely erased.

  It has been confirmed that even when a vertical pulse magnetic field is applied to a horizontal recording type hard disk, the hard disk operates without any problem, and therefore magnetic data cannot be erased. It has also been confirmed that magnetic data cannot be erased by applying a horizontal pulse magnetic field to a perpendicular recording type hard disk.

(2) Problems when horizontal magnetic recording media and vertical magnetic recording media coexist The above-mentioned horizontal recording type hard disk (horizontal type HDD) and vertical recording type hard disk (vertical type HDD) are both model codes. In many cases, it is difficult to specify whether the recording method is a horizontal recording method or a vertical recording method. Further, from the standpoint of erasing the magnetic recording data, even if the horizontal recording method or the vertical recording method is known, the magnetic force of the vertical HDD can be obtained only by using the erasing device for erasing the magnetic data of the conventional horizontal HDD. Data cannot be erased. Also, if there is a magnetic data erasing device for a vertical HDD, depending on the horizontal HDD and the vertical HDD, two types of magnetic data erasing devices are used separately, so that both the horizontal HDD and the vertical HDD can be used. Magnetic data can be erased.

(3) Technical idea of the present invention As described above, it is discriminated whether the hard disk to be erased is a horizontal recording system or a vertical recording system (there may be unknown even if it is examined), and two types of magnetic data erasing devices are used properly. In this case, work efficiency is hindered and magnetic data is not easily erased. Banks, insurance, mail-order sales, and other companies that handle personal information pay close attention to preventing leakage of personal information, and it can be said that erasure operations that leave concerns about erasure are next to major risks. I must. The companies mentioned above use a large number of magnetic recording media in personal computers and other office processing devices, and a large amount of magnetic recording media whose storage deadline has passed must be disposed of. At the time of disposal, it is necessary to erase a large number of magnetic data such as hard disks.

  The technical idea of the present invention is as shown in FIG. It is not necessary to determine whether the hard disk 51 to be erased is a horizontal recording system or a vertical recording system. In either recording method, after the hard disk 51 is inserted into the magnetic data erasing apparatus 10, the magnetic field in the parallel direction and the vertical direction of the hard disk 51 is applied simultaneously or for a time (less than 1 second, usually 0. Occurs in less than 1 second). Both the magnetic field in the parallel direction and the magnetic field in the vertical direction are magnetic fields having such an intensity that the magnetic data of the corresponding recording type hard disk 51 can be erased. As a result, the magnetic data can be erased by one operation regardless of which type of hard disk is used, without determining whether the hard disk is a horizontal recording system or a vertical recording system.

(Embodiment 1)
(1) Outline of Device FIGS. 5A and 5B show a magnetic data erasing device 10 according to Embodiment 1 of the present invention. The magnetic data erasing apparatus 10 shown in FIGS. 5A and 5B generates a magnetic field obliquely on the plate surface of the hard disk 51 so that the horizontal and vertical magnetic fields of the hard disk 51 are generated simultaneously. In order to make the strength of the magnetic field uniform in the horizontal direction and the vertical direction, the axial direction of the coil 1 and the vertical direction of the plate surface of the hard disk 51 are preferably set to 45 °. However, as will be described later, although the decisive reason is unknown, the object of the present invention can be achieved even if it is slightly inclined from the plate surface vertical direction or the plate surface parallel direction, and therefore, 45 °. There is no need to stick to the direction.

  In FIG. 5A, the storage unit 15 protrudes from the air core part of the coil 1 and facilitates the mounting of the hard disk 51. The storage portion 15 is preferably formed of a high-strength resin or a nonmagnetic metal such as aluminum. A hinge 49 is attached to the portion for holding the storage portion 15 and the coil housing, and the storage portion 15 is taken out from the air core portion of the coil 1 (FIG. 5A). It arrange | positions in an air core part (FIG.5 (b)). A hinge or the like that rotates both positions constitutes the storage unit moving mechanism. In order to obtain accuracy such as the inclination of the storage unit 15, it is preferable to attach a stopper to the rotation mechanism.

  FIG. 6 is a diagram showing the plane parallel component Hp and the vertical component Hv of the magnetic field H when the surface of the hard disk 51 is arranged at an angle of more than 45 ° with respect to the direction of the pulse magnetic field H. In the case of the arrangement of the hard disk 51 as shown in FIG. 6, if the hard disk 51 is a vertical HDD, Hv = Hsinθ, which is advantageous for erasing magnetic data and disadvantageous for erasing magnetic data for a horizontal HDD. Therefore, when the plane orthogonal direction of the hard disk 51 is set to 45 ° with respect to the direction of the magnetic field H, the magnetic data can be erased in both the horizontal HDD and the vertical HDD, but in the case of FIG. There may be a suspicion that it may be difficult to erase the magnetic data of the system HDD. However, actually, even if there is a deviation from the 45 ° direction as shown in FIG. 6, the magnetic data can be erased as long as it is tilted.

  The reason is not an assertive conclusion, but is considered to be based on the mechanism (in the case of a horizontal HDD) shown in FIG. That is, even if the hard disk 51 is standing with respect to the magnetic field H above 45 °, the easy axis of magnetization is along the in-plane direction of the hard disk 51 because the hard disk 51 is horizontal. For this reason, the pulse magnetic field H, which is an external magnetic field, changes its direction in the direction of the easy axis of the hard disk 51 at the interface between the air and the hard disk 51, and the horizontal component of the hard disk 51 becomes higher. It becomes easy to erase. Further, when the hard disk 51 is a vertical HDD and the in-plane direction is inclined at 45 ° with respect to the magnetic field H as shown in FIG. 8, as shown in FIG. The direction of the magnetic field H changes in the direction perpendicular to the plane. In other words, the direction is changed so as to be along the plane perpendicular direction which is the easy axis direction of magnetization of the vertical HDD. For this reason, the magnetic data can be erased for the vertical type hard disk 51 even in the case of a slanting inclination (FIG. 8) considerably compared to the case of the 45 ° arrangement.

  A modification of the magnetic data erasing apparatus shown in FIG. 5 is shown in FIGS. The coordinate axis of the coil is indicated by capital letters XYZ, and the axial center direction of the coil is parallel to the Z direction. 9 and 10, the hard disk 51v indicated by a broken line is a virtual one parallel to the axis of the coil 1. Any of the lower-case coordinate axes xyz attached to the virtual hard disk 51v is perpendicular or parallel to each surface of the hard disk 51v, and there is no diagonal direction. On the other hand, in the actual hard disk 51, the x direction of the lower-case coordinate axis is not parallel to the plate surface direction. In other words, the direction perpendicular to the plate surface of the hard disk 51 is not parallel to the z direction, but forms an angle of less than 90 ° and is obliquely arranged. 9 and 10, it is not necessary for the perpendicular direction of the plate surface of the hard disk 51 and the coil axis direction to form 45 °, and on the basis of the reason explained in FIGS. 7 and 8, it is about 45 ° ± 35 °. If it is in the range. In the case of FIG. 9, the storage unit 15 is inserted from the end surface. In the case of FIG. 10, the surface of the hard disk 51 is inclined so that the surface is moved in parallel. There is no problem with the manner in which it is placed, or the posture during wearing. For example, in the case of FIG. 10, the hard disk 51 may be inserted into the storage unit 15 so as to slide obliquely from the upper right side.

(2) Time Pattern of Pulsed Magnetic Field FIG. 11 is a diagram showing measurement data of the current flowing through the coil after discharging the capacitor and the magnetic flux density at the center of the storage unit. This magnetic flux density is a magnetic flux density corresponding to the magnetic field H in FIGS. From FIG. 11, it can be seen that there is a one-to-one correspondence between the change in current and the change in magnetic field. In the embodiment of the present invention, the decaying alternating magnetic field is not used, and the magnetic data is erased by the first (first) pulse magnetic field. In Figure 11, the magnetic flux density of the first peak Ru 0.95T der. Also, the magnetic flux density 0.4T or more of the duration Ru 30ms Tsuyoa. In the embodiment of the present invention, the peak value of the magnetic flux density may be in the range of 0.6T to 1.2T, and the duration of the magnetic flux density of 0.6T or more may be in the range of 3 ms to 35 ms .

  In FIG. 11, after the first pulse magnetic field, a pulse magnetic field having a short duration and a small peak is generated for a half cycle in the opposite direction. Such a reverse half cycle may or may not appear depending on the configuration of the capacitor, and it is confirmed that the magnetic data erasing performance (test result) is not affected by the presence or absence of the reverse half cycle. Yes. As shown in FIG. 11, the reason why a pulse magnetic field having a long duration is generated is largely due to the fact that a forward diode is arranged from the negative side of the coil to the positive side of the capacitor, as will be described later.

(3) coil and a capacitor first pulse magnetic field above conditions: (1) the magnetic flux density peak value of the first pulse magnetic field is 0.6 T~1.2T, (2) the magnetic flux density 0.6 T or more duration May be realized with any circuit configuration as long as 3 ms to 35 ms is satisfied. For example, (1) and (2) can be satisfied by increasing the capacitance C of the capacitor and the capacitance L of the coil. When the pulse magnetic field peak is flattened and the duration is increased, the LC unit in which a capacitor (capacitance C) and a coil (inductance L) are connected in series is set as one unit, and the LC unit is stacked in m stages. Connect to the pulsed magnetic field generating coil. With this circuit configuration, the peak of the pulse magnetic field can be flattened, and the duration of the flat part can be 2 m (LC) ^1/2 . And in the case of a lower magnetic field strength that skirts the peak, the duration can be further extended.

  FIG. 12 is a diagram showing a pulse magnetic field generator using a typical LC circuit. A current from the charging circuit 31 flows into the capacitor 2 and charges are accumulated. When the predetermined electric charge is accumulated and the voltage of the capacitor reaches a predetermined value, the electric charge of the capacitor 2 is discharged by the discharge element 5 and a current flows through the coil 1, and the coil axis core is placed in the air core (storage part) of the coil 1. A directional pulsed magnetic field is formed. Although the current path including the coil 1 is formed of a copper wire, the electric resistance is not zero, and a finite electric resistance 3 is attached.

  The capacity or combined capacity of the capacitor 2 is preferably 7000 μF or more in order to increase the peak value of the magnetic flux density and to increase the duration of the magnetic flux density of 0.4 T or more. The upper limit of the capacity of the capacitor 3 or the combined capacity is about 13000 μF. Usually, the capacity is about 9000 μF to 11000 μF (see FIG. 13A). In order to increase the amount of electric charge stored in the capacitor, it is preferable to use a capacitor of approximately 9000 μF to 11000 μF connected in parallel. For example, as shown in FIG. 13 (b), by connecting two capacitors of 9000 μF to 11000 μF connected in parallel and using a total of four capacitors of 9000 μF to 11000 μF, the accumulated charge amount is reduced to 2 Can be doubled.

FIG. 14 is a partial cross-sectional view of a coil when a flat conducting wire 21 is used. A copper wire 21a having a rectangular cross section covered with a varnish 21b or the like is wound around the bobbin 11, and the gap between the conducting wire or enameled wire 21 is small and the copper wire 21a is wound closely. FIG. 15 is a partial cross-sectional view of a coil when a round cross-section enamel wire 23 is used. A copper wire 23a having a round cross section covered with a varnish 23b is wound around the bobbin 11, but it can be seen that there are more gaps and the space factor is lower than that of the flat wire of FIG. . Normally, enameled wire having a round cross section is used for forming the coil. However, by using the flat wire 21, the space factor can be improved. As a result, the current density of the coil can be increased, and as a result, high magnetic flux. The density can be formed in the air core part (storage part). For example, 3 mm × 9 mm (cross-sectional area 27 mm ² ), 2 mm × 5 mm (cross-sectional area 10 mm ² ), or the like can be used for the cross section of the above-described flat enameled wire. A coil (number of turns 50 to 150) is formed using such a flat enameled wire to set the coil inductance to 0.3 mH to 1.3 mH, and the electrical resistance is set to 0.2 mΩ to 150 mΩ, for example. Is good.

(4) Circuit configuration for extending the duration time FIG. 16 is a diagram showing a circuit configuration for extending the duration time of the pulse magnetic field generated in the air core portion of the coil 1. The point is to arrange the forward diode 7 from the minus side of the coil 1 toward the plus side. When a voltage is applied to the gate G, the thyristor 5 as a discharge element is turned on by the conduction between the cathode K and the anode A. The voltage application to the gate G is performed by a voltage signal from the control unit described later. The voltage of the capacitor 2 is detected. When the capacitor 2 is charged and reaches a predetermined voltage, the voltage is applied to the gate of the thyristor 5. As a result, the capacitor 2 starts discharging and causes a current to flow through the coil 1.

  The current flowing through the coil 1 is accumulated on the negative side of the capacitor to increase the negative side potential. However, when the potential becomes higher than the positive side potential of the capacitor 2, the current flows from the negative side to the positive side through the diode 7. As a result, the capacitor 2 is supplemented with the current after passing through the coil 2 while flowing the current toward the coil 1. As a result, the duration of the pulse current is extended, and the duration of the magnetic field that is directly proportional to the current is also extended. That is, the duration of the pulse magnetic field generated by the circuit configuration including the diode 7 shown in FIG. 16 is very long compared to the pulse magnetic field generated by the circuit configuration without the diode 7.

  Further, the arrangement of the diode 7 as described above can avoid a situation in which a high reverse voltage is applied to the capacitor 2 after the electric charge is discharged, and the life of the capacitor can be extended. Further, the diode 7 suppresses the accumulation of electric charge on the negative side of the capacitor 2, thereby suppressing the generation of an alternating current and, as a result, suppressing the generation of an alternating magnetic field. Looking at the overall action of the diode on the pulse magnetic field, the diode suppresses the formation of an alternating current that is attenuated by the electrical resistance in the LC circuit exemplified in FIG. It can be seen that it has the effect of extending the duration.

  As a result, two very important actions (extension of the magnetic field duration and longer life of the capacitor) can be obtained by a very simple element such as the diode 7. This diode can naturally be replaced by various circuits or elements having a rectifying action. Of the operational effects of the diode 7, the extension of the duration of the pulse magnetic field will be described with respect to the results measured in the examples.

(5) Configuration of Charging Circuit for Shortening Charging Time As described above, magnetic data erasing work usually targets a large number of discarded hard disks, so high work efficiency is important. In particular, it is important to shorten the charging time of the capacitor. FIG. 17 is a diagram showing a charging circuit using the triac 18 for supplying power from a general outlet 33. The power supplied from the general outlet 33 is boosted by the voltage doubler rectifier S through the triac 18 that is turned on with respect to the power supply and charges the capacitor 2. The control unit 19 detects the voltage of the capacitor 2 and determines whether the capacitor 2 has been charged. When the capacitor 2 needs to be charged, the triac 18 is turned on, and a current is introduced from the voltage doubler rectifier S to the capacitor 2. When charging of the capacitor 2 is completed and a magnetic field generation switch (not shown) is pressed from the outside, a signal of about 5V is applied to the gate of the thyristor 5 to turn on the thyristor 5 and discharge from the capacitor 2. Is started, and a pulse magnetic field is generated in the air core part (storage part) of the coil 1.

  FIG. 18 is a diagram showing a circuit of a system for charging the capacitor 2 using the resistance element 36 without using the triac. The electric power fed from the general outlet 33 charges the capacitor 2 from the resistance element 36 through the voltage doubler rectifier S and the switch 46 in the on state. When a display is made that the capacitor 2 is sufficiently charged, the switch 45 is turned on to discharge the capacitor 2 and generate a pulse magnetic field in the air core of the coil 1.

  By using the triac 18, the capacitor 2 is charged at a constant rate as shown in FIG. 19 regardless of the initial state (the capacitor voltage is low) and the end (the capacitor voltage is high). The The triac 18 can supply a constant current to the voltage doubler rectifier S side regardless of the voltage of the capacitor 2. On the other hand, when charging is performed using the resistance element 36, the voltage of the capacitor 2 is affected as the charging of the capacitor 2 proceeds. As the voltage of the capacitor 2 rises, the current passing through the resistance element decreases, and the charging speed gradually decreases as shown in FIG. As a result, in the charging method shown in FIG. 18, the work efficiency is greatly reduced. Further, as a practical problem, a predetermined voltage that does not satisfy the rated capacity of the capacitor 2 must be set as the charge completion voltage, and the pulse magnetic field generated by the discharge of the capacitor 2 must be reduced accordingly. Absent.

  Another factor that reduces the work efficiency is a problem of leakage from the capacitor 2 after the end of charging. A small amount of charge is constantly leaking from the capacitor 2 after charging. For this reason, in the charging method shown in FIG. 17 using the triac 18, the control unit 19 detects the voltage of the capacitor 2, and when the voltage reaches 94% of the rated voltage, issues a command to the triac 18 to start charging. Thus, it is possible to perform automatic charging that continues charging up to 104% of the rated voltage. FIG. 20 shows the time course of the capacitor potential in the above charging. As a result, the magnetic data erasure operator can press the external switch almost any time, discharging a sufficient amount of charge to form a pulsed magnetic field with a sufficiently high peak magnetic flux density and sufficient duration. it can.

  On the other hand, in the system using the resistance element 36 shown in FIG. 18, since the control using the triac 18 cannot be performed, the charge is adjusted while manually operating the switch 46 and looking at the meter displaying the potential of the capacitor. Will do. For this reason, if the magnetic data erasure operator takes care of handling the hard disk and leaves the leakage of the capacitor 2, the voltage of the capacitor 2 greatly decreases, and charging often takes a lot of time again. . The use of the triac 18 (1) allows charging from the general outlet 33 at a constant speed from the beginning to the end with certainty, so that the charging time can be shortened compared to the method using an electric resistance element. (2) The replenishment of leakage from the capacitor after charging can be automated, and the voltage of the capacitor is constantly kept within a certain range, so that it is not necessary to replenish the leakage.

  The charging circuit does not use a step-up transformer for charging the capacitor. If a step-up transformer is used in the charging path of the charging circuit, it takes a long time to charge and quick charging cannot be performed. Therefore, in order to increase the efficiency of the erasing operation of magnetic data, which has an important factor in short charging time, it is preferable not to use a boosting transformer in the charging circuit of the magnetic data erasing device.

(6) Measures against shock When a current from the capacitor 2 flows through the coil 1 at once, a large electromagnetic force is instantaneously generated in the coil 1. For this reason, a large impact is applied to the bobbin 11 around which the winding of the coil 1 is wound, and a rigid structure using metal or the like is deformed or cracked and cannot be used many times. The durability of the bobbin can be improved by combining a resin plate that can be elastically deformed and has sufficient strength. A general resin plate may be used, but a resin plate having a high strength, for example, an ABS (acrylonitrile-butadiene-styrene) resin plate is preferably used. FIG. 21 is a perspective view showing the assembled bobbin 11 by laser processing the end portions of the ABS resin plate into a mutually fitted shape. After assembly, an adhesive is injected into the gap to firmly adhere. Since the bobbin 11 assembled with such a resin plate is restored after being deformed against an impact, it can withstand a large number of impacts without any problem.

  During the magnetic data erasing operation, the operator may receive a magnetic field generated by the magnetic data erasing apparatus according to the embodiment of the present invention. The magnetic field measurement for confirmation about this point was performed. As a result, it was confirmed that at a position about 5 cm away from the above device, the strength of the magnetic field received by the ear when the telephone handset was put on the ear was smaller.

(Embodiment 2)
FIG. 22 is a perspective view showing the magnetic data erasing apparatus 10 according to the second embodiment, which is different from the present invention and is given as a reference of the present invention. The magnetic data erasing apparatus 10 according to the present embodiment is characterized in that a coil 1 composed of two coil portions 1a and 1b spaced apart from each other and a coil 61 are combined. In the coordinate axis XYZ associated with the magnetic data erasing device 10, the axis of the coil 1 is parallel to the Z direction, and the axis of the coil 61 is parallel to the X direction.

  FIG. 23 is a diagram schematically showing the coil of FIG. 22, the direction of the magnetic field, and the direction of the hard disk 51. 22 and 23, the coil 1 generates a magnetic field (Hv) in the Z direction between the two coil portions 1a and 1b, and the coil 61 generates a magnetic field (Hp) in the X direction. The coil 1 and the coil 61 may be supplied with current simultaneously to generate magnetic fields in the Z direction and the X direction at the same time. The magnetic fields in the Z direction and the X direction may be generated at a time of about 100 ms or less. Each may occur. When stored in the storage unit 15, the plane perpendicular direction (z direction) of the hard disk 51 is parallel to the Z direction of the apparatus, and the x direction in the plane of the hard disk 51 is parallel to the X direction of the apparatus. The second embodiment is different from the magnetic data erasing apparatus of the first embodiment in that the coil 1 for Z direction (for vertical direction) and the coil 61 for X direction (for horizontal direction) are arranged. To do.

  FIG. 24 is a circuit diagram of the magnetic data erasing apparatus 10 shown in FIG. A diode 7a is arranged in parallel with the coil 1 in the forward direction, and a diode 7b is arranged in parallel with the coil 61 in the forward direction. A capacitor 2a for accumulating electric charges for the coil 1 and a capacitor 2b for accumulating electric charges for the coil 61 are provided, and thyristors 5a and 5b are used as discharge elements for instructing the capacitors 2a and 2b to release electric charges. Is provided. That is, the vertical magnetic field Hv coil 1 and the horizontal magnetic field Hp coil 61 store charges independently of each other, and a magnetic field generating current flows independently of each other. The control circuit 19 determines the timing of current discharge or magnetic field generation. When the operation switch 45 is turned on once, discharge signals S1 and S2 are transmitted from the control circuit 19. The deviation in the timing of discharging the current flowing through the coil 1 and the coil 61, that is, the deviation between the discharge signals S1 and S2, is preferably less than 100 ms. The human sensation cannot sense this shift in charge discharge timing, and it is recognized that the erasure of magnetic data is completed by a single operation.

  In the magnetic data erasing apparatus 10, both the capacitors 2a and 2b are preferably set to 7000 μF or more. Each of the capacitors 2a and 2b may be a single capacitor as shown in FIG. 13A, or may be a combination of a plurality of capacitors as shown in FIG. 13B.

The capacitors 2a and 2b are also charged by an instruction from the control circuit 19 to the triac 18 of the charging circuit 31. The voltages of the capacitors 2a and 2b are monitored, and the control circuit 16 receives the voltage signals M1 and M2. Only when the monitor voltages M1 and M2 are both zero, in other words, when both the capacitors 2a and 2b are empty due to discharge of electric charge, the control circuit 19 issues a signal for turning on the triac 18 and charging the capacitor 2a. , 2b, when it is in the charge accumulation state, it is not instructed to charge. Thereby, safety can be ensured. FIG. 25 is a diagram showing a computer simulation result of the time transition of the currents of the coil 1 and the coil 61 when the electric charges are sequentially released from the capacitors 2a and 2b in the circuit of FIG. The difference between the current rising times t1 and t2 of the coils 1, 61 (L1, L2) is preferably less than 100 ms. Further, the current value is in each coil, the magnetic flux density is 0.6 T～1.2T, also the magnetic flux density 0.6 T or more duration in the range of 3 ms through 35 ms Like that.

(2) Pulse magnetic field time pattern, (3) Coil and capacitor, (4) Circuit configuration for extending the duration, (5) Configuration of the charging circuit for shortening the charging time in the first embodiment ( 6) The impact countermeasures can be applied to the coils 1 and 61 as they are, and the same contents are also implemented in the present embodiment. That is, in both the coils 1 and 61, (2) the time pattern of the pulse magnetic field is that the peak value of the magnetic flux density is 0.6 T to 1.2 T in both the coil 1 and the coil 61 at the central portion of the shaft core. And a pulse magnetic field having a magnetic flux density of 0.6 T or more and a duration of 3 ms to 35 ms is formed. (3) The coil is a flat wire, and the electric resistance and inductance of the coil are the coils 1 and 61. Both are within the same range as the coil 1 of the first embodiment, and the capacitances of the capacitors 2a and 2b are also within the same range as the capacitor 2 of the first embodiment. (4) In addition to the inductance and capacitance, the duration time The diodes 7a and 7b are used for extension, (5) the triac 18 is used in the power receiving circuit, and (6) the ABS resin plate is fitted into the bobbin 11 of each coil 1 (1a, 1b), 61. It is used the structure (see Figure 21).

  In the magnetic data erasing apparatus 10 according to the present embodiment, both the magnetic field Hv in the vertical direction of the hard disk stored in the storage unit and the in-plane direction Hp of the hard disk stored in the storage unit are simultaneously or almost instantaneously performed by a single ON operation. Occur. In this case, the capacitor and the coil for generating the magnetic fields Hv and Hp have a sufficiently large capacity, inductance, etc., respectively. As a result, the magnetic data on the hard disk can be erased without determining whether the hard disk stored in the storage unit is a vertical system or a horizontal system. In the magnetic data erasing apparatus 10 described above, since the capacitors 2a and 2b may be charged, the charging time is important. However, since the triac 18 is used for the charging circuit 31, the charging time is not long and is limited. You can do it. Also, full consideration is given to ensuring safety.

(Example 1-Measurement of magnetic flux density / time pattern of pulsed magnetic field)
Next, the measurement results of the pulse magnetic field / time and current / time for the case where the diode 7 is arranged in the forward direction from the negative side to the positive side of the coil 1 (see FIG. 16) and the case where the diode 7 is not arranged are shown. . An apparatus of the type shown in FIG. 9 was used as the magnetic data erasing apparatus. The coil used was a 68 mm turn of a 3 mm × 9 mm rectangular enamel wire. The inductance L of the coil is 0.46 mH, and the resistance R is 36 mΩ. One capacitor having a capacity of 10,000 μF was used. Triac was used for the charging circuit. The magnetic field is measured by placing Hall elements at two points, the central part of the storage part and the lower part (floor position) 20 mm from the entrance, and the signal from the Hall element is set as an amplifier (set with the Hall element: The signal was input to an oscilloscope (TDS3012: manufactured by Tektronix) via GAUSS METER MODEL HGM 8300P3 (manufactured by ADS). In addition, the current is attached so that the coil for current measurement circulates in the wiring between the capacitor and the coil, and the signal passes through an amplifier (set with current measurement coil: peak ammeter PHS-CO: made by IMS Co., Ltd.) Entered in. On the oscilloscope, the magnetic field and current were displayed on the vertical axis in synchronization with the time axis (horizontal axis).

  The results are shown in FIGS. FIG. 26 is a display image of an oscilloscope showing the measurement results of the current and the magnetic field at the center of the storage unit when no diode is arranged. The peak magnetic flux density is as high as 0.81T. The duration of the magnetic flux density of 0.4T or more is 6 ms to 7 ms. It can be seen that the current time pattern is the same as the magnetic flux density time pattern. On the other hand, when the diode 7 is arranged (see FIG. 16), the peak magnetic flux density is 0.81 T, which is the same as the case where no diode is arranged, as shown in FIG. It is greatly extended. For example, the duration of a magnetic flux density of 0.4 T or more is greatly extended from 10 ms to 11 ms from 6 ms to 7 ms when no diode is arranged. Such extension of the duration of the pulse magnetic field is very effective for erasing magnetic data, as described repeatedly, and erasure by a single pulse magnetic field can be reliably obtained.

  FIG. 28 is a display image showing the measurement result of the magnetic field at the floor (lower) position 20 mm deep from the opening before the storage unit. The peak magnetic flux density is 0.63T, which is greatly reduced from the peak value 0.81T in FIG. 26, and the duration of 0.4T or more is also shortened to about 5 ms. On the other hand, when the diode 7 is arranged, as shown in FIG. 29, the peak magnetic flux density is 0.63T, but the duration of 0.4T or more is over 7 ms, and the diode 7 is not arranged. Compared to the above, an extension of the duration of 40% or more can be obtained.

  By arranging the forward diode from the negative side of the coil (capacitor) to the positive side of the capacitor as described above, the pulse magnetic field duration can be greatly extended. The extension of the duration of the pulse magnetic field has been obtained by using a simple element such as a diode, which can make a great contribution to providing a device with excellent magnetic data erasability at low cost. Further, since the generation of a high reverse voltage to the capacitor can be prevented, it is useful for improving the durability of the capacitor, which occupies a large specific gravity in the apparatus.

  However, the magnetic data erasing apparatus of the present invention most widely has a peak magnetic flux density of 0.4T to 1.2T and a duration of the magnetic flux density of 0.4T or more is 4 ms or more. It is not necessary to use the above diode.

(Example 2: Magnetic field measurement of magnetic data erasing apparatus shown in FIG. 5)
The magnetic field was measured using the following specimens (Invention Examples A and B).
(Invention Sample A): Capacitor capacity 9000 μF; coil winding 3 × 9 rectangular wire 67 turns, inductance 0.79 mH, winding electrical resistance 33 mΩ, diode arrangement Capacitor voltage during charging is 680 V, during discharging The peak current was 1.81 kA.
(Invention Sample B): Capacitor capacity 11000 μF; coil winding 3 × 9 rectangular wire 67 turns, inductance 0.79 mH, winding electrical resistance 33 mΩ, diode arrangement Capacitor voltage during charging is 680 V, discharging The peak current was 1.47 kA.

  FIG. 30 shows magnetic field measurement positions in the coils of Examples A and B of the invention. Table 1 shows the magnetic field measurement results at each position. The position A1 is the center position in the coil, but shows a sufficiently high magnetic field strength. Similarly, a high magnetic field can be obtained for other positions. Although the time transition was not measured, it was confirmed by the program that obtained the simulation of FIG. 25 that the duration of the magnetic flux density of 0.4 T or more was more than 4 ms.

(Example 3: Magnetic field measurement of coil 1 of magnetic data erasing apparatus shown in FIG. 22)
In the magnetic data erasing apparatus shown in FIG. 22 or FIG. 23, the magnetic field measurement was performed in the space between the coil portion 1a and the coil portion 1b of the coil 1. This measurement is a measurement of the pulse magnetic field / time and current / time for one of the two coils, but can be regarded as a measurement of the pulse magnetic field / time and current / time for one coil tilted in the present invention. it can. The test specimens are as follows.
(Invention Sample C): Capacitor capacity 10000 μF; coil winding 3 × 9 rectangular wire coil portion 1a 97 turns, coil portion 1b 97 turns, inductance 0.79 mH, winding electrical resistance 33 mΩ, diode arrangement Capacitor The voltage was 390 V, and the peak current during discharge was 1.2 kA.
(Invention Sample D) Capacitor capacity 9000 μF; coil winding 3 × 9 rectangular wire coil portion 1a 97 turns, coil portion 1b 97 turns, inductance 0.79 mH, winding electrical resistance 33 mΩ, diode arrangement Capacitor The voltage was 650 V, and the peak current during discharge was 1.86 kA.

  FIG. 31 shows magnetic field measurement positions in the coils of the invention examples C and D described above. Table 2 shows the magnetic field measurement results at each position. The position A2 is the center position in the coil, but shows a sufficiently high magnetic field strength. Similarly, a high magnetic field can be obtained for other positions. Although the time transition was not measured, it was confirmed by the program that obtained the simulation of FIG. 25 that the duration of the magnetic flux density of 0.4 T or more was more than 4 ms. The above-described inventive examples C and D have been described as corresponding to the coil 1 of the magnetic data erasing apparatus 10 shown in FIG. That is, the present invention example C or D is used for the coil 1 in the circuit diagram of FIG. 24, and this and a normal coil such as the present invention example A or B are used for the coil 61, and the coils 1 and 61 in the second embodiment are used. Can be configured. However, Invention Examples C and D may be viewed as the coil 1 of FIG.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The magnetic data erasing apparatus according to the present invention does not determine which method in the situation where it is difficult to determine which method from the display of the magnetic recording medium in the present and the future where the horizontal and vertical magnetic recording media coexist. In any type of magnetic recording medium, magnetic data can be erased by a single operation. In the era when protection of personal information is regarded as important, it is expected to make an important contribution to the prevention of leakage of personal information.

It is a figure which shows the hard disk of a magnetic recording medium. It is sectional drawing which shows the magnetization arrangement | sequence of the hard disk of a horizontal recording system. It is sectional drawing which shows the magnetization arrangement | sequence of the hard disk of a perpendicular recording system. It is a figure for demonstrating the technical idea of the magnetic data erasing apparatus of this invention. It is a figure which shows the magnetic data erasing apparatus of Embodiment 1 of this invention, (a) is the state which put out the storage part out of the coil, (b) is a storage part in a coil using a rotation mechanism. It is a figure which shows the state arrange | positioned. It is a figure which shows the formal magnetic field component at the time of inclining a hard disk. It is a figure which shows the direction change of the magnetic field which actually arises when the hard disk of a horizontal recording system is tilted. It is a figure which shows the direction change of the magnetic field which actually arises when the perpendicular recording hard disk is tilted. It is a figure which shows the modification of the magnetic data erasing apparatus of Embodiment 1 of this invention. It is a figure which shows another modification of the magnetic data erasing apparatus of Embodiment 1 of this invention. It is a figure which shows the time pattern of the pulse magnetic field in Embodiment 1 of this invention. It is a figure for demonstrating the circuit structure of the magnetic data erasing apparatus in Embodiment 1 of this invention. It is a figure which shows the structural example of the capacitor | condenser in Embodiment 1 of this invention, (a) is a figure which shows the structure of one capacitor | condenser, (b) is a figure which shows the structure of four capacitors | capacitors. It is sectional drawing of the coil winding part using a flat-angle enameled wire. It is sectional drawing of the coil winding part using a round enameled wire. It is a figure which shows the circuit structural example which has arrange | positioned the diode of the forward direction toward the positive side from the coil negative side in Embodiment 1 of this invention. It is a figure which shows the example which used the triac for the charging circuit in Embodiment 1 of this invention. It is a figure which shows the example which used the resistive element for the charging circuit. It is a figure for demonstrating shortening of the charge time at the time of using a triac. It is a figure for demonstrating the effect of carrying out automatic replenishment of the electric leakage of a capacitor | condenser using a triac. It is a figure which illustrates the bobbin in Embodiment 1 of this invention. It is a figure which shows the magnetic data erasing apparatus of Embodiment 2. FIG. It is a figure for demonstrating the coil of FIG. 22, the direction of a magnetic field, and the direction of a hard disk. FIG. 23 is a circuit diagram of the magnetic data erasing apparatus of FIG. 22. It is a figure which shows the simulation result of the pulsed current which flows into two coils. It is a figure which shows the pulse magnetic field and electric current when not using a diode in Example 1 (magnetic field measurement position = storage part center). It is a figure which shows the pulse magnetic field and electric current at the time of arrange | positioning a diode in Example 1 (magnetic field measurement position = storage part center). It is a figure which shows the pulse magnetic field and electric current when not using a diode in Example 1 (magnetic field measurement position = floor surface 20 mm depth from opening). It is a figure which shows the pulse magnetic field and electric current at the time of arrange | positioning a diode in Example 1 (magnetic field measurement position = floor surface 20 mm depth from opening part). 6 is a diagram illustrating magnetic field measurement positions in Example 2. FIG. 6 is a diagram illustrating magnetic field measurement positions in Example 3. FIG.

Explanation of symbols

  1 coil, 1a, 1b coil part, 2, 2a, 2b capacitor, 3 electrical resistance, 5, 5a, 5b thyristor, 7, 7a, 7b diode, 10 magnetic data erasing device, 11, 11a, 11b bobbin, 15 storage Part, 18 triac, 19 control part, 21 rectangular enameled wire, 21a copper wire, 21b varnish layer, 23 round enameled wire, 23a copper wire, 23b varnish layer, 31 charging circuit, 33 outlet, 36 electrical resistance element, 45 discharge Switch, 46 Switch, 51 Hard disk (magnetic recording medium), 52 Glass substrate, 53 Soft magnetic layer, 55 Magnetic recording layer, 56 Protective film, 57 Rotating shaft (axis), 58 Track, 59 Magnetic head, S Double pressure rectification Department.

Claims (4)

A magnetic data erasing apparatus for erasing magnetic data of a horizontal type magnetic recording medium and a vertical type magnetic recording medium,
A storage unit for storing the magnetic recording medium;
A coil positioned to include the storage and generating a magnetic field for erasing the magnetic data;
A resin bobbin around which the coil is wound;
One or more capacitors that store charge to supply current to the one coil;
A thyristor positioned between the one coil and the one or more capacitors;
One end connected between the thyristor and the coil, and a diode connected in a forward direction from the negative side of the coil to the positive side of the coil;
One operation switch for operating the magnetic data erasing device,
The axial center direction of the one coil is arranged so as to form an angle of more than 0 ° and less than 90 ° with the direction perpendicular to the plate surface of the magnetic recording medium housed in the storage unit,
The one coil is formed of a rectangular wire, has an electric resistance of 0.2 mΩ to 150 mΩ, an inductance of 0.3 mH to 1.3 mH, and 1 / (L · C) ^1/2 of 250 (1 / second) to 650. In the range of (1 / second),
The capacitance of the one or more capacitors is 7000 μF or more;
When the operation switch is turned on once, the thyristor is turned on, discharges the electric charge accumulated in the one or more capacitors, and is stored in the storage unit in the one coil. In addition, a pulse magnetic field for erasing the magnetic data is generated in both the plate surface parallel direction and the plate surface vertical direction of the magnetic recording medium,
The one coil forms a pulse magnetic field having a peak value of the magnetic flux density of 0.6T to 1.2T and a duration of the magnetic flux density of 0.6T or more of 3 ms to 35 ms in the central part of the shaft core. ,
In order to withstand the impact of electromagnetic force due to the pulsed magnetic field in multiple uses, the resin bobbin is a bobbin that is formed by fitting resin plates into a fitting shape and fitting them together. , Magnetic data erasing device.   2. The magnetic data erasing apparatus according to claim 1, wherein the axial direction of the coil is arranged so as to form an angle within a range of 45 ° ± 35 ° with respect to a direction perpendicular to the plate surface.   The storage unit moves between a mounting position of the storage unit when the magnetic recording medium is mounted outside the coil and an erasing position of the storage unit included in the coil when the pulse magnetic field is applied. The magnetic data erasing apparatus according to claim 1, further comprising a storage unit moving mechanism.   The magnetic data erasing apparatus according to claim 1, wherein a triac is used for a current path for charging the capacitor.

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