JP2000232761A - Diskette with permanent magnet generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To substantially eliminate the leakage of a magnetic flux to the outside from a generator permanent magnet in a diskette, such as a 3.5" floppy diskette or the like, in which a permanent magnet generator and a space used to insert a memory card are provided side by side. SOLUTION: In this diskette, a generator 2 having a rotor permanent magnet and a space, which is used to insert a memory card, are provided side by side. An opening 21 in which a rotor is situated is opened in the center of the rear plate 12 on the side of the generator of a diskette case. A magnetic shield ring plate 241, whose outside diameter is substantially identical to or a slightly larger than that of the permanent magnet, is pasted on the upper-side end face of a rotor permanent magnet 212. The height of the magnetic shield ring plate 241 is made nearly identical to that of the rear plate 12. With this structure, excess space is eliminated between the generator and the diskette case, the diskette can be made thin, and the leakage of a magnetic flux to the outside can be practically eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diskette having a permanent magnet generator, and more particularly to a diskette inserted into and attached to a floppy disk drive. When a memory such as an IC card is incorporated in the diskette, input / output of the memory is performed. The present invention relates to a diskette having a permanent magnet generator that can be used as a power source.

[0002]

2. Description of the Related Art Information such as the results of an individual's medical examination is stored in an IC card, and when visiting a medical institution with the IC card, medical treatment is performed based on the information in the IC card. Can be performed, and the contents of the medical chart at the time of medical treatment can be stored in the IC card. The use of IC cards as electronic money is also being considered. That is, a bank account, a personal identification number, and an account balance of a person who uses the IC card are stored, and the payment with the bank account is performed via the IC card every time money is used.

[0003] In addition, since image information of a digital camera has a relatively large amount of information, it has been proposed to store it in a large-capacity flash memory. The flash memory has a capacity of several megabytes to 10 megabytes, so the image information of the digital camera is stored in the flash memory, and the flash memory can be connected to a personal computer to perform processing. Storing the results in flash memory eliminates the need for an additional external storage device such as an MO.

[0004] Both the IC card and the flash memory require a unique device as their input / output device, and this necessity has hindered their spread. A floppy disk drive, especially a 3.5 "floppy disk drive is generally used as an input / output device of a computer, particularly a personal computer widely used.
The use of a 3.5 "floppy disk drive for input and output of a memory card such as an IC card or a flash memory is expected to spur the spread.
Using a 3.5 "floppy disk drive, a memory card such as an IC card or flash memory
It is called a memory card. ) It is contemplated to perform input and output, and adapters have been proposed that can be inserted into a 3.5 "floppy disk drive. However, a 3.5" floppy disk drive has a 3.5 "diskette inserted into it. A magnetic head for inputting / outputting information and a drive shaft for rotating the floppy disk at 300 rpm are provided between the optical disk and a (normal 3.5 "floppy diskette), but no power supply terminal is provided. Therefore, a button-type battery is incorporated in the adapter as a power supply for the CPU incorporated in the diskette-shaped adapter. Since a battery is consumed as it is used, it needs to be replaced every few months at the longest.

[0005] Therefore, if a generator is incorporated in the diskette and the generator can be operated using the rotation of the drive shaft of a 3.5 "floppy disk drive, it becomes extremely useful. In fact, it has already been proposed to incorporate the generator in a 3.5 "diskette, as disclosed in Japanese Patent Publication No. 7-86912 and PCT International Publication No. It is described in Table 7-500238.

Japanese Patent Publication No. 7-86912 discloses that a generator is incorporated in a 3.5 ″ diskette, and that the generator has a rotor, a stator, and a regulator.
Its detailed configuration is not shown. Also, Tokiohei 7-5002
No. 38 has a permanent magnet that rotates with the boss as a generator built into a 3.5 ″ diskette, and the boss with the permanent magnet is rotated by a drive shaft of a floppy disk drive. The permanent magnet has a cylindrical shape and is magnetized in the direction of the rotation axis so that there are a large number of magnetic poles on the cylindrical end surface.The magnetic pole of the stator yoke sandwiches the cylindrical permanent magnet. And the stator coils are provided between the stator yokes on both sides of the cylindrical permanent magnet.
There is also shown an example in which magnetic poles are provided on the circumferential surface of the cylindrical permanent magnet, in which case the magnetic poles of the stator yoke are claw-pole type.

[0007]

As described above, these publications describe the incorporation of a permanent magnet generator into a 3.5 "diskette. Since the detailed structure of the rotor and the detailed structure of the stator are not described, it is unclear what output has been obtained.

A permanent magnet generator sized to be incorporated into a 3.5 ″ floppy diskette as disclosed in Japanese Patent Publication No. Hei 7-500238, and a cylindrical rotor permanent magnet. Consider a magnet that is magnetized in the direction of the axis of rotation so as to have a large number of magnetic poles on the end face of the cylinder, where stator poles are arranged on both sides of the end face of the cylinder via small magnetic gaps. Allowed thickness is 2.0
~ 2.5mm, so the permanent magnet thickness is 0.5 ~
Only 0.8 mm is allowed. As described above, even if a magnet having a short distance between magnetic poles has a large coercive force, a magnet having a small magnetomotive force will be used. In addition, when the magnetomotive force is increased by increasing the thickness of the magnet, the thickness allowed for the stator magnetic pole is reduced, and the magnetic flux cannot be sufficiently transmitted.

In the case of a permanent magnet generator in which a magnetic pole is provided on a circumferential surface of a cylindrical permanent magnet and a stator yoke opposed thereto is a claw pole type, both claw poles are provided. The end yokes of the magnetic poles are provided facing each other in the thickness of 2.0 to 2.5 mm allowed for the generator, and the stator winding is applied to the outside of the permanent magnet between the two end yokes. Become. The allowable length of the stator winding is 1 mm or less, which is slightly longer than the thickness of the permanent magnet, and the output voltage is low because a sufficient number of windings cannot be provided.

In order to increase the output of the generator as much as possible without distortion, the magnetic poles on the circumferential surface of the cylindrical permanent magnet are arranged at equal angular intervals, and the magnetic poles of the stator yoke are provided. It is considered necessary to make the number the same as the number of magnetic poles of the rotor permanent magnet so that the stator magnetic pole faces the permanent magnet magnetic pole.

In order to use the diskette as an information input / output device with a memory card having a magnetic stripe such as an IC card, it is necessary to provide a space for inserting the card on the diskette. The size of the memory card is usually 85 mm in length, 54 mm in width, 0.8 mm in thickness,
Since this thickness does not include embossing, it is actually a little thicker. When the space for storing the memory card and the permanent magnet type generator are provided in the diskette, they are overlapped. Therefore, in the 3.5 mm diskette 3.5 mm thick, the two-sided cover thickness 0.2 mm is 2 mm. Assuming that the memory card has a thickness of 0.8 mm, the generator has a thickness of 2.
It must be 0 mm or less.

The present applicant has already filed an application for a diskette having this permanent magnet generator as Japanese Patent Application No. 10-224051. The diskette in this application is shown in FIG.
The illustrated diskette 5 incorporates a permanent magnet type generator 6 around a boss 611 at the center thereof, and an annular permanent magnet 612 having magnetic poles on the outer peripheral surface can rotate with the boss. The stator 62 of the generator is provided with a magnetic gap between the outer periphery of the permanent magnet 612 of the rotor 61 and the magnetic pole on the outer peripheral surface of the permanent magnet 612,
Attached inside the diskette. Since the diskette 5 is used as an input / output device of a memory card, a space 55 for inserting the memory card is provided.
A card contact terminal 56 for exchanging information with a memory card is provided.
An input / output terminal 57 for exchanging information between the diskette and the magnetic head of the floppy disk drive is provided at an opening 53 opened for the magnetic head to enter. A CPU 58 is provided as needed to process information between the input / output terminal 57 and the card contact terminal 56. The permanent magnet generator 6 is used as a power supply for driving the CPU 58 and driving the card contact terminals 56 and the like. Normally, the output of the generator passes through a stabilized power supply circuit 59 in the diskette as a drive power supply.

The diskette 5 has the same shape as a 3.5 "floppy disk and is usually handled together with a floppy disk. A diskette with a permanent magnet generator is located near one end plate of the diskette case. Provided with a permanent magnet generator, magnetic flux from the permanent magnet may leak to the outside through the end plate and adversely affect other floppy disks being handled together.

In view of this, the back plate 52, which is one of the end plates, is formed of a magnetic shield plate, and the size of the central opening 521 is such that only the boss 611 protrudes therefrom. The permanent magnet 612 and the stator 62 are all covered with the back plate 52 to prevent leakage of magnetic flux. In order to prevent the magnetic flux of the permanent magnet 612 from leaking into the space of the memory card and adversely affecting the information on the memory card, it has already been proposed to form the housing 63 of the generator with a magnetic shield plate.

However, the back plate 5 made of a magnetic shield plate
2 has a structure that covers one entire side surface of the rotor permanent magnet 612, a part of the magnetic flux to be guided from the magnetic pole of the permanent magnet 612 to the stator magnetic pole is located near the outer peripheral end of the permanent magnet. There was a case where the power leaked to a certain back plate 52 and the generator output was reduced. Further, since the back plate 52 is fixed, and the rotor permanent magnet 612 rotates with respect to the back plate 52, a certain gap is required between them in order to avoid contact between them. For these reasons back plate 52
A gap in the thickness direction of at least 0.2 to 0.3 mm was required between the permanent magnet 612 and the permanent magnet 612 so that they did not come into contact with each other. The allowable thickness of the generator is 2.0 mm or less as described above.
Providing an air gap of mm should be avoided because it leads to the need to further reduce the thickness of the permanent magnet.

Therefore, in the present invention, a permanent magnet type having a structure capable of substantially eliminating leakage magnetic flux from a built-in generator permanent magnet to maintain the generator output and reducing the thickness of the generator. The purpose is to provide a diskette with a generator.

[0017]

DISCLOSURE OF THE INVENTION A diskette having a permanent magnet generator according to the present invention has an annular permanent magnet having a plurality of magnetic poles arranged on a circumferential surface and capable of rotating with a boss. A rotor affixed to one end surface of the annular permanent magnet and having a magnetic shield ring plate whose outer diameter is substantially the same as or larger than the annular permanent magnet; A permanent magnet type generator having a magnetic pole of an annular permanent magnet and a stator facing each other via a magnetic gap is provided therein, and an opening is provided at substantially the center of one end plate of the diskette case. The magnetic shield ring plate of the annular permanent magnet is located in the opening, and the height of the magnetic shield ring plate and the end plate are substantially the same. .

Thus, the end plate of the diskette case and the magnetic shield ring plate do not interfere in the thickness direction,
Substantially the same surface can be formed to cover the rotor permanent magnet. Therefore, it is possible to provide a diskette in which external leakage magnetic flux is reduced and high power generation output is maintained without providing useless air gaps.

Also, an IC inserted into the diskette
Since the coercive force of a magnetic stripe of a card or the like varies, when a card having a low coercive force is placed on a diskette, information may be lost.
In such a case, it is necessary to enhance the magnetic shielding effect regardless of the type of the card. With respect to this, in the present invention, it has been found that it can be adjusted by the magnetic air gap and the amount covering the magnetic air gap, and the thickness and material of the shield plate. First, it is effective to make the magnetic shield ring plate larger than the outer diameter of the annular permanent magnet so as to protrude beyond the permanent magnet. The amount of protrusion is considered to be at least about 0.1 to 1.0 mm so as to cover at least the magnetic gap, but in practice, the length is about 0.3 to 0.6 mm with a length of about twice the magnetic gap. It is desirable to select with. Next, it is conceivable to consider the thickness of the magnetic shield ring plate, and the thicker the better, the better.
In practice, a range of 0.1 to 0.5 mm is selected. However, when it is more important to reduce the thickness of the entire diskette, 0.1 to 0.3 mm is more preferable. Further, the material of the magnetic shield ring plate must be taken into account. This is more preferable as the permeability is higher, but it is necessary to consider cost, ease of processing, etc.,
Even if the protrusion amount and the thickness are appropriately balanced, the material must have a magnetic permeability of at least 50 or more.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a diskette having a permanent magnet generator according to the present invention will be described in detail with reference to the drawings. 1 is a diskette having a permanent magnet type generator according to the present invention. FIG. 1 (a) is a plan view (bottom view) of the diskette, FIG. 1 (b) is a cross-sectional view taken along line 1B-1B of FIG. 1 (a),
FIG. 1 (c) is a partially enlarged view of FIG. 1 (b). FIG. 2 is an exploded perspective view of a diskette having the permanent magnet generator of the present invention. FIG. 3 is a plan view of a permanent magnet generator incorporated therein. FIG. 4 shows a cross section 4A-4A of FIG. 3 in (a) and a cross section 4B-4B of FIG. 3 in (b).

The structure of a diskette incorporating a permanent magnet generator according to an embodiment of the present invention will be described. Here, a description will be made using a diskette structured to be attached to the most widely used 3.5 "floppy disk drive, but it will be apparent from the following description that the present invention can be applied to diskettes having other sizes or structures. 3.5 "diskette (usually
3.5 "floppy disk) 1
Has a structure shown in a plan view (bottom view) in FIG. 1 (a), and its size is 94 mm in length, 90 mm in width, and 3.5 mm in thickness. In the figure, the diskette case has a front plate 11 and a back plate 12 which are end plates on both sides thereof.
The back plate 12 has a boss 211 in the center.
Is made of a thin plate having an opening 121 so as to face the outside. One end of the case has an opening 13 into which a magnetic head for input and output enters, and a boss 211 that can transmit rotation of a drive shaft of a floppy disk drive is provided at substantially the center of the case. In the case of a floppy disk, a floppy disk is mounted coaxially with the boss so that it can rotate.

In the embodiment of the diskette 1 incorporating the permanent magnet generator of the present invention, the permanent magnet generator 2 is incorporated around the center boss 211 of the diskette 1, and the rotor of the generator 2 21 is the boss 211,
An annular permanent magnet 212 attached to the outer periphery of the boss 211 and having a magnetic pole on the outer peripheral surface so that it can rotate together.
It is composed of The stator 22 of the generator is provided on the outer periphery of the rotor permanent magnet 212 with a magnetic gap of substantially the same size as the magnetic pole on the outer peripheral surface of the permanent magnet 212, and is mounted inside the diskette. I have.

The diskette 1 shown in FIG. 1 is used as an input / output device of an IC card or an IC card having a magnetic stripe (hereinafter, referred to as a "memory card"), so that a space 15 for inserting the memory card is provided. And a card contact terminal 16 for exchanging information with a memory card. An input / output terminal 17 for exchanging information between the diskette and the magnetic head of the floppy disk drive is provided at an opening 13 opened for the magnetic head to enter. A CPU 18 is provided as needed to process information between the input / output terminal 17 and the card contact terminal 16.
The permanent magnet generator 2 is used as a power supply for driving the CPU 18 and for driving the card contact terminal 16 and the like. However, since electricity from the generator may include ripples and the like, rectification and stabilization are required. In some cases, the stabilized power supply circuit 19 is incorporated in an output line of the generator 2 provided in a diskette.

The boss 211 of the rotor 21 of the permanent magnet generator 2 is engaged with the drive shaft of the floppy disk drive, and the rotor 21 is rotated by the rotation of the drive shaft. In the case of a 3.5 "floppy disk drive, the rotational speed is usually 300 rpm. Since the boss 211 engages with the drive shaft of the floppy disk drive, the structure of the engaging portion of the boss 211 with the drive shaft is provided. Is preferably the same as the structure of a normal diskette boss.

FIG. 1A shows a permanent magnet type generator 2 with a broken line.
Input / output terminal 17 and card contact terminal 16
When the outer circumference of the stator yoke of the permanent magnet type generator 2 is a perfect circle, the outer circumference of the stator yoke 221 and these input / output terminals 17 and card contact terminals 16 are There is a risk of interference. Therefore,
It is preferable that the external shape of the generator be rectangular and cut out at these portions.

FIG. 2 is an exploded perspective view of the diskette 1 for explaining the structure of the housing 23 and the diskette 1. FIG. In this figure, the front plate 11 of the case of the diskette 1 is shown at the bottom, and the back plate 12 is shown at the top.
In this embodiment, the front plate 11 is made of plastic,
In order to impart strength, a metal plate is preferable, and a magnetic or non-magnetic stainless steel material may be used. On the other hand, here, back plate 1
2 is a non-magnetic stainless steel (SUS30
4) It is made. The back plate 12 is desirably formed of a non-magnetic stainless steel or a non-magnetic material such as a plastic material. However, for example, a stainless steel material which is slightly magnetic after heat treatment can be used. Permanent magnet generator 2
Are mounted in the housing 23 and are attached to the generator rotor 21 by a shaft 232 attached to the housing 23.
The bearing 233 attached to the center of the boss 211 is supported. The housing 23 incorporating the generator 2 overlaps with and is adjacent to the card space 15. The magnetic stripe 151 of the memory card inserted into the card space 15 has a substantially bearing 233 as shown in FIG.
It comes to the upper position around. The housing 23 is made of a cold-rolled steel plate having a thickness of 0.1 mm (saturation magnetic flux density of about 1.5 T), and semicircular notches 236 are provided at upper and lower portions corresponding to the side surfaces of the generator rotor 21. ,
A transition 237 of the magnetic shield plate is provided at a position corresponding to the magnetic stripe 151 between these two notches. The shaft 232 is mounted on the transition 237 of the shield plate.

The transition 237 of the magnetic shield plate completely covers the magnetic stripe 151 and prevents the magnetic flux leaking from the rotor permanent magnet 212 from affecting the magnetic stripe. Is preferably slightly larger than the width of the magnetic stripe 151. For example, the width of the transition 237 may be set to 6 to 10 mm. In addition, if the memory card is inserted by mistake in the opposite direction, the magnetic stripe will not be located at the crossing portion of the original magnetic shield plate, so there is a possibility that the magnetic stripe will be affected by the leakage magnetic field at this time .
Assuming such a case, the crossing portion of the magnetic shield plate may be provided at the position of the magnetic stripe when the card is inserted from both the forward and reverse directions. The semicircular notch 236 provided in the housing has a diameter larger than the diameter of the rotor permanent magnet 212, preferably larger than the inner diameter of the stator magnetic pole surface, and the generator 2 When viewed, the side surface of the stator magnetic pole may be slightly visible through the semicircular notch 236. For example, the inner diameter of the stator magnetic pole surface is 29.4 mm
In the case of 1 to 5 mm from the inner diameter so that the diameter becomes 32 mm.
It is preferable to increase the size by about mm.

By opening the semicircular notch 236 in the housing 23, the rotor permanent magnet 212
The magnetic shield plate does not exist around the side surface and the outer periphery of the end surface except for the part of the transition 237 of the magnetic shield plate. In particular, when there is a magnetic pole on the circumferential surface of the permanent magnet 212, the magnetic flux is concentrated at the outer peripheral line of the end surface of the permanent magnet. The short circuit of the magnetic flux is reduced, and the magnetic flux guided to the stator magnetic pole is increased. By providing the shield plate transition 237 only at the position corresponding to the magnetic stripe 151 on the side surface of the rotor 21, the short circuit of the magnetic flux between the permanent magnet magnetic poles can be reduced, and the influence on the magnetic stripe 151 can be eliminated.

Next, the center opening 121 of the back plate 12 has a diameter slightly larger than the outer diameter of the rotor 21. A magnetic shield ring plate 241 made of a soft magnetic material plate having a thickness of about 0.1 mm is attached to an end surface of the permanent magnet 212 of the rotor 21 on the back plate 12 side. The outer diameter of the magnetic shield ring plate 241 of this example is substantially the same as the outer diameter of the permanent magnet 212, and the inner diameter is substantially the same as or slightly smaller than the inner diameter of the permanent magnet 212. Therefore,
The magnetic shield ring plate 241 completely covers one end face of the permanent magnet 212. Here, if the outer diameter of the magnetic shield ring plate 241 is small, the outer peripheral end of the permanent magnet comes out of the outer periphery of the magnetic shield ring plate, and the magnetic flux leaks to the outside. Regarding the coercive force of a card such as a memory card (a force capable of holding input information against an external magnetic field), there are currently several types of cards (for example, 2750 Oe, 650 Oe).
Or 300 Oe). It has become common to use a high coercivity memory card to reduce the effect on externally recorded information. For such a card having a high coercive force, even if it is placed on a diskette having a small amount of external magnetic flux leakage, the influence thereof is small. For a card having a low coercive force, the influence of external leakage magnetic flux cannot be ignored. For this reason, the minimum size of the magnetic shield ring plate that has an effect on the external leakage magnetic flux is substantially the same as the outer diameter of the permanent magnet. It is desirable to make the protrusion larger than this, from the viewpoint of reducing the external leakage magnetic flux, but on the other hand, since it affects the efficiency of the power generation output, it is preferable to set the range of the protrusion amount on the outer diameter side. . This will be described in the following embodiment.
Although the inner diameter side does not cause a problem in terms of function, it is preferable that the inner circumference of the magnetic shield ring plate fits tightly with the outer circumference of the boss.

With the permanent magnet generator 2 installed in the diskette 1, as shown in FIG. 1C, the magnetic shield ring plate 241 and the back plate 12 are set to be substantially the same height. In this case, a small gap is provided between the inner periphery of the opening 121 of the fixed back plate 12 and the outer periphery of the magnetic shield ring plate 241. This gap is 0.1 to 1.0 mm
About. If the size is larger than this, there is a possibility that foreign matter such as dust may enter from the gap.
It is good to make it about 2 to 0.5 mm. In this way, by setting the gap between the outer periphery of the magnetic shield ring plate 241 and the inner periphery of the opening of the back plate 12 to be about 0.1 to 1.0 mm, the short circuit of the magnetic flux of the permanent magnet is reduced, and the entire surface is shielded. The same shielding effect as when a plate is provided can be exhibited. And, this diskette has an opening 12 in the back plate 12 in appearance.
The magnetic shield ring plate 241 is provided with a slight gap from
Is located where it can be seen from the outside,
The gap between the and the magnetic shield ring plate 241 is visible from the outside of the finished diskette.

On the other hand, when the shield plate is provided on the entire surface, the rotor can be rotated with respect to the fixed shield plate, and the back plate made of the shield plate and the rotor It was necessary to provide a gap in the thickness direction of at least 0.2 to 0.3 mm between the magnet 212 and the end face. Providing such a gap has resulted in a corresponding increase in the thickness of the generator. However, by adopting the structure as in this embodiment, it is not necessary to provide a useless space in the generator,
The thickness of the diskette can be reduced.
The diskette referred to in the present invention is not limited to a 3.5 "type floppy disk, but can be arbitrarily changed in its shape, size, and structure. The present invention is not limited to a card, but can be used for a memory card in a broad sense including a flash memory.

Next, the structure of the permanent magnet type generator 2 is shown in FIG.
4 will be described. 21 is a rotor, and a boss 21
An annular permanent magnet 212 is fixed to the outer circumference of the
The permanent magnet 212 has a plurality of rotor magnetic poles arranged substantially equiangularly on its outer circumferential surface, and these magnetic poles have circumferentially different polarities, that is, NSNS.
... lined up.

A plurality of stator magnetic poles are provided on the stator 22 so as to face the outer periphery of the permanent magnet 212 via a magnetic gap. The stator magnetic pole is provided at one end of the magnetic pole teeth 223 made of a soft magnetic material on the side facing the outer periphery of the permanent magnet 212. The magnetic pole 227 of these magnetic pole teeth 223
Is to be able to face simultaneously with the rotor poles,
Like the rotor magnetic poles, they are arranged on the inner diameter surface of the stator at substantially equal angular intervals. As a result, the stator magnetic poles and the rotor magnetic poles have the same number of poles.
, The stator poles 227 are reduced accordingly. Each pole tooth 223 is wound with a stator coil 225, which is preferably connected in series. The magnetic pole teeth 223 having each magnetic pole at one end thereof are arranged substantially in parallel.
The stator poles are arranged at substantially equal angular intervals, i.e., radially with respect to the rotor, so that the stator poles can face the rotor poles, but at least the coil 225 of the pole teeth 223 is wound. The bent portions are bent near the magnetic pole at the tip of the magnetic pole teeth so as to be arranged in parallel. The pole teeth 223 are divided into two blocks, a left block and a right block. Magnetic pole teeth 2 in each block
Reference numeral 23 denotes an end on the opposite side of the magnetic pole connected by a back yoke 224. The number of blocks can be one block with all magnetic pole teeth, but can be about 2 to 4 blocks. However, when various devices are installed in a narrow space such as a diskette, it is necessary to make the space of the generator as small as possible, so it is better to use two blocks.

It is preferable that the magnetic pole teeth 223 in each block have adjacent stator magnetic poles connected by an inner yoke 222. Since the stator magnetic poles are provided at positions that can simultaneously face the rotor magnetic poles, the cogging torque tends to be large,
By connecting the stator magnetic poles with the inner yoke 222, magnetic flux leaks between the magnetic poles, so that the cogging torque can be reduced. However, if the leakage between the magnetic poles is made too large in order to reduce the cogging torque, the effective magnetic flux passing through the magnetic pole teeth becomes small and the output drops. Therefore, the cross-sectional area of the inner yoke 222 between the stator magnetic poles is made smaller than the cross-sectional area of the stator magnetic pole teeth 223.
For example, the magnetic pole tooth width is set to 3 mm, and the radial thickness of the transition portion between the tips of the inner yoke is set to 0.5 mm, so that most of the magnetic flux emitted from the rotor magnetic pole passes through the stator magnetic pole teeth.

By dividing the magnetic pole teeth 223 into two blocks on the left and right sides, the length of the generator 2 (the length in the vertical direction in FIG. 3) is reduced by the diameter of the rotor 21 and the size of the stator magnetic pole portion. It takes up just as much space and takes up less space to fit on a diskette. This is because the adjacent coils 225 are arranged in parallel with each other so that there is almost no useless space between the coils.

As described above, the diskette 1 is provided with a card contact terminal 16 for a memory card and an input / output terminal 17 for a floppy disk drive for inputting and outputting information. Since the card contact terminal 16 and the input / output terminal 17 are near the boss 211 of the generator 2, it is possible to avoid interference between the card contact terminal 16 and the generator 2 in this generator. Magnetic pole teeth 2
By dividing 23 into left and right blocks, the rotor 2
The pole teeth that should be at the top and bottom of 1 are gone. No stator magnetic poles are provided at the portions where the magnetic pole teeth are lost, that is, at the notches 226 and 226 ′ made in the generator 2. When the stator magnetic poles are made to face the rotor magnetic poles at the same time, some of the rotor magnetic poles come to the notches 226, 226 'and do not face the stator magnetic poles. This non-opposed rotor magnetic pole has at least one pole, preferably two to five poles, and at most six poles. On the inner peripheral surface of the stator facing the non-facing rotor magnetic poles, a soft magnetic material piece 22 is provided.
8, 228 'are provided. This soft magnetic piece 22
8, 228 'connect the magnetic poles on both sides of the rotor magnetic poles. In the generator shown in FIG.
8, 228 'connect the rotor poles 213 and 214 or three poles 213' to 215 ', and have a radial length of two normal pole teeth 2 as shown in FIG.
It is shorter than 23. In FIG. 3, the upper rotor poles S213 and N214 do not face the stator poles. Here, the left end 228a of the soft magnetic material piece 228 is
Magnetic pole 216 between pole 213 and N pole 215 on the left
And the soft magnetic piece 228 extends rightward therefrom. And the non-opposed N pole 214 at the top
And the magnetic pole 218 between the S pole 217 on the right side thereof and the S pole 217. The soft magnetic piece 228 is provided with a groove 229 in the axial direction on the surface facing the S pole and the N pole.

Also, the lower rotor magnetic pole N213 ',
S214 'and N215' do not face the stator magnetic poles. Instead of the stator magnetic poles, soft magnetic material pieces 228 'are provided facing each other. The soft magnetic material piece 228 '
Magnetic pole 2 between pole 213 'and S pole 216' at the upper right
Starting from 17 ', it continues to the magnetic pole 219' between the non-opposed north pole 215 'and the south pole 218' at the upper left. The soft magnetic piece 228 'has an N pole 213',
Grooves 229 'are provided in the portions facing the S pole 214' and the N pole 215 ', respectively, in the axial direction.

When the stator magnetic pole comes to a position facing the rotor magnetic pole, a soft magnetic material piece 2 connecting the magnetic poles is provided on the inner circumferential surface of the stator facing the rotor magnetic pole not facing the stator magnetic pole.
28, 228 'are provided. Grooves (extending in the axial direction) 229, 229 'are provided on the soft magnetic pieces 228, 228' at positions facing the rotor magnetic poles. Therefore, when the rotor magnetic pole is at a position displaced from the stator magnetic pole, the soft magnetic piece short-circuits between the rotor magnetic poles.
At this time, the soft magnetic piece attracts the rotor magnetic pole facing the end. On the other hand, when the rotor magnetic pole is located at a position facing the stator magnetic pole, the groove extending in the axial direction provided on the soft magnetic piece faces the rotor magnetic pole, and the rotor magnetic pole is stationary at that position. Becomes unstable and acts to move the rotor toward the end of the soft magnetic piece.

The rotor magnetic pole facing the stator magnetic pole tries to stop the rotor at the position facing the rotor magnetic pole.
Since the rotor magnetic pole facing the groove provided in the soft magnetic piece tries to move the rotor from that position, the cogging torque of the rotor is reduced.

Although the soft magnetic pieces 228 and 228 'have been described as "connecting the magnetic poles on both sides of the rotor magnetic pole", the term "between the magnetic poles" refers to the outer peripheral surface of the cylindrical permanent magnet. When many magnetic poles are arranged in a row, they do not necessarily mean an intermediate point between adjacent magnetic poles of different polarities, but refer to a peripheral portion excluding a substantial center of the magnetic poles. If one of the rotor magnetic poles faces the stator magnetic pole and the other rotor magnetic pole faces the groove provided in the soft magnetic piece, the attractive force at the position of the other rotor magnetic pole Is reduced, and the end of the soft magnetic material piece is shifted from the rotor magnetic pole to such an extent that the rotor magnetic pole is attracted to the soft magnetic material piece on the side of the groove and a rotational moment is given.

Since the output of the generator is obtained from the stator coil wound around the stator magnetic pole teeth provided so as to be able to face the rotor magnetic pole, the number of rotor magnetic poles is 16 and one pole is fixed. When the rotor permanent magnet is not opposed, the loss of the magnetic force of the rotor permanent magnet is reduced by 1/16, but it can be compensated by increasing the number of turns of the coil. Thus, the number of stator poles removed is at least one.
It is good to keep it as a pole. Preferably, two or more poles are continuous. In addition, the number is 6 or less, preferably 5 or less. As the width of the groove provided in the soft magnetic material piece,
It is preferably 0.1 to 0.4 of the magnetic pole width of the rotor permanent magnet. Here, the magnetic pole width of the rotor permanent magnet is calculated as 2π (360 °) / n, where n is the number of poles. The depth of the groove may be at least the magnetic gap between the rotor and the stator.

The magnetic pole teeth 223 of the stator 22 and the inner yoke 22
2 and the back yoke 224 are both made of a soft magnetic material. Since such a large saturation magnetic flux density Bs is preferable from the viewpoint of reducing the cross-sectional area of parts and reducing the size of the entire generator, soft iron, electromagnetic soft iron having a saturation magnetic flux density Bs of 1.2 T or more, Powder core, 4-6% S
A silicon steel sheet containing i can be used. Each magnetic pole tooth 223
Is wound with a coil 225 for extracting an output. Since the generator 2 has a flat plate shape as a whole and needs to be 2 mm or less even at the thickest point, the outermost diameter of the coil 225 wound around the magnetic pole teeth 223, that is, the thickness in the rotation axis direction is 2 mm. It is necessary to:

As described above, the permanent magnet 212 used for the rotor 21 is preferably an annular permanent magnet.
The permanent magnet 212 is fixed to the outer periphery of the boss 211 with an adhesive or the like. This annular permanent magnet has an appropriate length, that is, a thickness in the direction of the rotation axis. The thickness of the permanent magnet is at most 2.0 mm, and can be used in the range of 0.8 to 2.0 mm, preferably 1.0 to 1.8 m.
m. However, it will be apparent that this size will vary depending on the size of the diskette used and the configuration of the equipment to be incorporated.

It is desirable from the viewpoint of magnetomotive force that the annular permanent magnet 212 be as thick as possible in the direction of magnetization. In the case where the boss 211 is made of a ferromagnetic material in the case of having an easy axis of magnetization, that is, a radial anisotropy in the radial direction, the magnetic flux entering the magnet in the radial direction from the adjacent magnetic poles on the circumferential surface causes the magnetic flux of the ferromagnetic material. In the boss 211, the magnetic flux is coupled to a magnetic flux that has entered in a radial direction from a magnetic pole having an opposite polarity. In the case of polar anisotropy, magnetic flux connects magnetic poles of opposite polarities inside the magnet. In any case, the thickness of the permanent magnet 212 in the radial direction may be 1/3 to 1/4 or more of the distance between the magnetic poles.
It is preferable that there is the above.

The material of the permanent magnet 212 is sintered Nd
FeB magnets are preferred. Despite being a permanent magnet with a relatively small thickness (thickness in the direction of magnetization),
Since a large inverse magnetic field is applied and the shape is used with a large demagnetizing coefficient, a magnet having a large coercive force and a large magnetic flux density, such as an NdFeB magnet, is preferable. A sintered NdFeB magnet has magnetic anisotropy, but has an easy axis of magnetization in the radial direction, that is, has radial anisotropy, and connects adjacent magnetic poles of different polarities on the circumferential surface. Those having an easy axis of magnetization in the direction, that is, those having polar anisotropy are preferred. NdFeB magnet powder, which is called a NdFeB bonded magnet, which is bonded with a plastic binder or the like can also be used. However, in the case of a bonded magnet, since the ratio of the magnet component is smaller than that of a sintered NdFeB magnet, it is generated. The magnetic flux decreases. However, if the required output is small, a permanent magnet generator made with bonded magnets may be sufficient.

As the permanent magnet of the permanent magnet generator used in the present invention, in addition to the NdFeB magnet, (1) a nitride magnet such as an SmFeN magnet, and (2) SmFeN which is called an exchange spring magnet contains α iron. Magnets, magnets containing α-iron in NdFeB, magnets containing Fe ₃ B in NdFeB,
(3) HDDR (hydrogenation / decomposition / dehydrogenation / recombination) magnets such as NdFeB and SmFeN, and (4) SmCo magnets can also be used in view of required characteristics.

In the figure, the magnet having 16 magnetic poles on the outer peripheral surface of the annular permanent magnet 212 is shown. In the present invention, the number of magnetic poles is preferably 12 to 24, and 16 to 20 is preferable. It is more preferable to use a pole. When the number of poles is small, the amount of magnetic flux per pole increases, but the maximum output of the generator is 16 to 24 poles. However, as the number of poles increases, the space between the magnetic pole teeth extending in the radial direction of the stator decreases, and the number of turns of the coil of the magnetic pole teeth decreases. In addition, there are problems such as difficulty in manufacturing the stator and distortion of the output voltage waveform, so that 16 to 20 poles are optimal.

It is necessary that the thickness of the magnetic pole teeth of the stator magnetic pole teeth 223 be smaller than the length of the permanent magnet 212 in the rotation axis direction, that is, the thickness. That is, if the stator magnetic pole tooth thickness is greater than or equal to the rotor axial length,
The stator becomes thicker than the rotor by the thickness of the stator winding. In the case of a generator such as the present invention, in which the axial length is extremely limited, in order to increase the space utilization efficiency for a limited axial length, the stator magnetic pole thickness and the number of windings wound around it are required. It is important that the overall axial length of the line be approximately the same as the axial length of the rotor. In order to achieve this high space utilization efficiency, the tooth thickness of the stator poles must be thinner than the rotor thickness, and the overall thickness of the stator, including the windings, should be closer to the axial length of the stator. Is valid.
By making the thickness of the stator magnetic pole teeth 223 smaller than the thickness of the permanent magnet, a large output can be obtained as the generator 2. However, the pole thickness of the stator pole teeth 223 needs to be thick enough not to be saturated by the magnetic flux emitted from the permanent magnet 212. FIG. 4A shows a cross section of the main part of the stator 22 and the rotor 21 of the permanent magnet type generator 2, and shows the thickness t1 of the stator magnetic pole teeth and the magnet thickness t2. In this figure, it is necessary that t1 <t2. This is because the magnetic flux emitted from the magnetic poles of the permanent magnet 212 is concentrated in the magnetic pole teeth 223 constituting the stator 22 to increase the magnetic flux density in the magnetic pole teeth. Permanent magnet 21
2 and the saturation magnetic flux density of the stator magnetic pole teeth 223, the stator magnetic pole teeth 223 are made of a soft magnetic material, as described above. 1.2T or more, the permanent magnet 212
The residual magnetic flux density of the sintered NdFeB magnet having the strongest magnetic force is 1.2 to 1.3 T, so that the magnetic flux density at the operating point is about 1.0 T. When the sintered NdFeB magnet is used as the rotor permanent magnet 212 and the stator 22 having a saturation magnetic flux density of 1.2 T or more is used, the stator has a thickness of 30% to 70% of the permanent magnet thickness. Magnetic pole teeth 223 are preferred.

[0049]

EXPERIMENTAL EXAMPLE The diskette having the permanent magnet type generator of the present invention will be described in more detail by the following experiments, and the conditions for its execution will be clarified.

A diskette having a permanent magnet generator having the structure shown in FIGS. 1 to 4 was manufactured based on the design conditions shown in Table 1. Here, the diskette (A) according to the present invention has a housing 23 having a saturation magnetic flux density Bs of 1.5T and a diameter of 0.1 mm.
Produced using a cold-rolled steel sheet with a thickness of 1 mm and a diameter of 32 mm
Were provided with two semicircular notches, and a 9 mm-wide shield plate was provided between them. Also, the opening 12 in the center of the plastic back plate 12 of the diskette case.
1 is 29.2 mm, and B is attached to the end face on the back plate side of the permanent magnet.
A magnetic shield ring plate made of a cold-rolled steel plate having a thickness of 1.5 T and a thickness of 0.1 mm (outer diameter 29.0 mm × inner diameter 25.0)
mm) with an epoxy adhesive. The difference in height between the back plate 12 of the diskette case and the magnetic shield ring plate attached to the end surface of the permanent magnet is set to 0.1.
mm.

The diskette (B) of the comparative product has the same housing structure as the diskette (A), the back plate 12 of the diskette case is made of a cold-rolled steel plate having a thickness of 0.1 mm. Assuming a diameter of 26.0 mm,
That is, the gap in the thickness direction was provided between the end surface of the permanent magnet and the back plate 12 so that the opening portion of the back plate 12 and the end surface of the permanent magnet overlapped each other. However, no magnetic shield ring plate was provided on the end face of the back plate side of the permanent magnet.
As a comparative diskette (C), the back plate 12 and the housing were both made of a non-magnetic plastic material, the magnetic shield ring plate was not provided on the end face of the permanent magnet, and the other conditions were the same as those of the diskette (A). Table 2 summarizes the magnetic shield structures of these diskettes.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

Table 3 shows the results of measuring the output voltage and the leakage magnetic field strength outside the back plate. Both the diskette (A) of the present invention and the comparative product (B) had a smaller external leakage magnetic field intensity than the comparative product (C), and had no level of external influence. However, the thickness of the generator of the diskette (A) was 0.3 mm thinner than that of the diskette (B).

Next, another embodiment of the present invention will be described. FIGS. 5A and 5B show another embodiment of the diskette having the permanent magnet type generator of the present invention. FIG. 5A is a perspective view of the appearance of the diskette, FIG. 5B is a sectional view thereof, and FIG. It is sectional drawing of a rotor part. In the embodiment described above, the magnetic shield ring plate having substantially the same outer diameter as the permanent magnet is provided. The magnetic shield ring plate did not significantly affect a memory card having a magnetic memory having a relatively large coercive force. However, the shield effect is insufficient for a card having a weak coercive force (about 300 Oe) by itself. Therefore, in this embodiment, the outer diameter of the annular permanent magnet 212 is made larger than that of the annular permanent magnet 212, and the overhanging magnetic shield ring plate 251 is attached. In other words, as shown in FIGS. 5B and 5C, the magnets are made to protrude beyond the outer diameter of the permanent magnet 212 by the projection amount s to cover the magnetic gap g. Also in this example, as shown in FIG. 5B, the magnetic shield ring plate 251 is
A gap of about 0.5 mm is provided between the back plate 12 and the opening 121, and the back plate 12 is opposed to the back plate 12 at substantially the same height. Has formed. Other structures are the same as those of the above-described embodiment, and thus the same reference numerals are given and the description thereof is omitted.

When a memory card having a low coercive force is left on a diskette, information may be erased due to an external leakage magnetic field, and the accuracy of information reading may be reduced. In this embodiment, this point is solved by making the magnetic shield ring plate 251 protrude further than the permanent magnet. On the other hand, since the output of the generator tends to be reduced even if the amount of protrusion is too large, a desirable amount of protrusion of the magnetic shield ring plate has been found. Further, since the thickness of the magnetic shield ring plate at this time also has an adverse effect in the same manner as the protrusion amount, the dimensional balance of the magnetic shield plate taking these facts into consideration is newly found.

Hereinafter, a description will be given based on experimental results. The diskette used in this experiment was based on the specifications shown in Table 1 with the size of the aperture of the magnetic shield ring plate changed based on the structure of the diskette (A). The magnetic gap is set to about 0.15 mm. In the experiment, first, using a memory card with a relatively high coercive force (650 Oe) and a memory card with a low coercive force (300 Oe), the change in the card reading output and the generator output by changing the protrusion amount s of the magnetic shield ring plate, and Similarly, the change in the card reading output due to the change in the thickness t of the magnetic shield ring plate was examined. 6 and 7 are graphs showing the experimental results. FIG. 6 shows the card reading output when the thickness of the magnetic shield ring plate is fixed at 0.2 mm (▲ for coercive force of 650 Oe card, 300 Oe for coercive force). This is the result of measuring the case of a card with ●) and the power generation output ratio (○) with the protrusion amount s of the magnetic shield plate as a parameter. In FIG. 7, the protrusion amount of the magnetic shield ring plate is 0.2 m.
card reading output when fixed at m (coercive force 650
These are the results of measurement of the Oe card with ▲, the coercive force of 300 Oe card with ●) and the power generation output ratio (○) using the thickness t of the magnetic shield ring plate as a parameter. Here, the card reading output means that when a card in an initial state in which information is input 100% is placed on a diskette and the information is slightly erased, the percentage of the information that can be read thereafter is measured by the amount of change in the signal waveform. is there. The power generation output ratio is defined as 100% when the amount of protrusion is zero in FIG. 6 and 100% when there is no shield ring plate (shield ring thickness t = 0 mm) in FIG. 7. It was done.

First, as shown in FIG. 6, every time the protrusion amount s is increased, the card reading output increases, and in the case of a 300 Oe memory card, the protrusion amount becomes 0.1% or more, and becomes 60% or more.
When it is 2 mm or more, 90% or more can be maintained. That is,
It can be seen that when the protrusion amount is 0.2 mm or more, the external leakage magnetic flux is almost suppressed. The coercivity is relatively high (65
0 Oe) In the case of a card, even if the protrusion amount is 0 mm, 50
% Card reading output. But,
Conversely, the power generation output gradually decreases as the protrusion amount increases, but a power generation output of 90% or more is obtained up to 1.0 mm.
Up to 0.6 mm, the result exceeded 95%.
This is because when the amount of protrusion is less than 0.1 mm, much magnetic flux leaks to the outside, but 0.2 m
When the distance is about m, the leakage magnetic flux is cut off by the protrusion, and external leakage is eliminated. However, increasing it beyond that does not affect the external leakage magnetic field. Conversely, it is considered that the magnetic flux short-circuited by the shield ring plate increases and the output of the generator decreases. From this, even if the protrusion amount is 0 in a relatively high coercive force card, it is not affected by the external leakage magnetic flux, so the protrusion amount s is 0 to 1.0 mm,
Preferably, it is 0 to 0.6 mm. In a relatively low coercive force card, the protrusion amount s of the magnetic shield ring plate has a region in which the external leakage magnetic flux and the power generation output can be balanced at a position that is about twice as large as covering the magnetic gap g. The range that satisfies both the leakage magnetic flux and the generated power is approximately 0.
1 to 1.0 mm, more preferably 0.2 to 0.6
mm.

FIG. 7 shows the effect of the thickness of the magnetic shield ring plate. As shown in FIG. 7, as the plate thickness increases, the card reading output increases. Becomes approximately 0.2
It can be seen that an output of 90% or more can be maintained at mm or more.
With a 650 Oe card, an output of 80% or more can be obtained at 0.1 mm or more. However, conversely, the power generation output decreased as the thickness increased, and the result was less than 90% at 0.4 mm or more, and less than 60% at 0.5 mm or more. In other words, the thicker the shield plate, the more the external leakage magnetic flux can be prevented. However, if the shield plate is too thick, the degree of short-circuiting increases, and the output of the generator rapidly decreases. From the above, the thickness of the magnetic shield ring plate also has a range satisfying both the amount of external leakage magnetic flux and the generated power, which is approximately 0.1 to 0.5 mm, and more preferably 0.2 to 0.5 mm. ０．４0.4 mm. However, since it is important for the diskette to reduce the thickness of the generator, the thickness is first reduced to a thin value in the range of 0.1 to 0.5 mm, for example, 0.1 to 0.3 mm. If the memory card used is relatively high in coercivity (65
0 Oe or more), the protrusion amount is 0 to 0.6 mm, and when the coercive force is low (about 300 Oe), the protrusion amount is 0.1 to 0.6 mm.
It will be preferable to choose a value in the range of 1.0 mm, preferably 0.2-0.6 mm.

As for the material of the magnetic shield ring plate, it is desirable to use a soft magnetic material having a magnetic permeability of 50 or more and a high saturation magnetic flux density in terms of function, but in consideration of cost and workability. Normal thin steel plates are practical.

In the embodiment shown in FIG. 5, the magnetic shield ring plate 251 is formed by cold rolling in consideration of reduction of the external leakage magnetic flux, thinning of the diskette, maintenance of the output of the generator, ease of production, cost, and the like. The thickness t is 0.2 mm, the protrusion amount s is 0.3 mm, and the magnetic gap g is 0.2 mm.
It was set to 15 mm. In this example, when the same experimental data as in Table 3 above were taken, the leakage magnetic field strength at the magnetic stripe portion was 10 gauss, and the external leakage magnetic field strength was 150 gauss, which was a level having no influence on the outside. The output of the generator was as high as 20 mW.

[0063]

As described in detail above, according to the diskette having the permanent magnet type generator according to the present invention, it is possible to substantially eliminate the external leakage magnetic flux from the permanent magnet of the generator and maintain the power generation output high. The thickness of the diskette could be reduced.

[Brief description of the drawings]

FIG. 1 is a diskette having a permanent magnet generator according to the present invention, wherein (a) is a plan view (bottom view) of the diskette;
(B) is a 1B-1B sectional view of (a), and (c) is a partially enlarged view of (b).

FIG. 2 is an exploded perspective view of a diskette having the permanent magnet generator of the present invention.

FIG. 3 is a plan view of a permanent magnet type generator used for the diskette of FIG. 1;

4A is a cross-sectional view of the permanent magnet type generator shown in FIG. 3, and FIG. 4B is a cross-sectional view of 4B-4B.

5A and 5B show another embodiment of the diskette having the permanent magnet type generator of the present invention, wherein FIG. 5A is a perspective view of the appearance of the diskette, FIG. 5B is a sectional view of the entire diskette,
(C) is an enlarged sectional view showing a rotor portion extracted.

FIG. 6 is a graph showing the results of measuring the card reading output and the generated power when the thickness of the magnetic shield ring plate is set to 0.2 mm using the protrusion amount of the magnetic shield ring plate as a parameter.

FIG. 7 is a graph showing the results of measuring the card reading output and the generated power with the thickness of the magnetic shield ring plate as a parameter when the protrusion amount of the magnetic shield ring plate is 0.2 mm.

FIG. 8 is a diskette having a permanent magnet type generator of which application is pending, wherein (a) is a plan view (bottom view) of the diskette,
(B) is an 8B-8B sectional view of (a), and (c) is a partially enlarged view of (b).

[Explanation of symbols]

1, 5 Diskette 11 Front plate 12, 52 Back plate 121, 521 Opening 13, 53 Opening 14 Cover 15, 55 (Memory card) space 151 Magnetic stripe 16, 56 Card contact terminal 17, 57 Input / output terminal 18, 58 CPU 19, 59 Stabilized power supply circuit 2, 6 (permanent magnet type) generator 21, 61 rotor 211, 611 boss 212, 612 permanent magnet 213, 214 ', 217, 216', 218 'S
Poles 213 ', 214, 215, 215' N
Pole 216, 217 ', 218, 219' Between magnetic poles 22, 62 Stator 221 Stator yoke 222 Inner yoke 223 Magnetic pole teeth 224 Back yoke 225 Stator coil 226, 226 'Notch 227 (stator) magnetic pole 228, 228' Soft magnetic piece 228a Left end 229, 229 'Groove 23, 63 Housing 232 Shaft 233 Bearing 236 Notch 237 Transfer of magnetic shield plate 241, 251 Magnetic shield ring plate

Continued on the front page (72) Inventor Toshiko Takahashi 5200 Sankajiri, Kumagaya-shi, Saitama Hitachi Metals, Ltd.Magnetic Materials Research Laboratory (72) Inventor Masahiro Mita 5200 Sankajiri, Kumagaya-shi, Saitama Hitachi Metals Magnetics Research Laboratory

Claims (4)

[Claims] An annular permanent magnet having a plurality of magnetic poles arranged on a circumferential surface and capable of rotating together with a boss, and is attached to one end surface of the annular permanent magnet and has an outer diameter of a circle. A rotor having a magnetic shield ring plate substantially the same as or larger than the annular permanent magnet; and a stator facing the magnetic pole of the annular permanent magnet via a magnetic gap. The diskette case has an opening substantially in the center of one end plate of the diskette case, and the magnetic shield ring plate of the annular permanent magnet is located in the opening. A diskette having a permanent magnet generator, wherein the height of the magnetic shield ring plate and the height of the end plate are substantially the same. 2. The projecting amount of the magnetic shield ring plate is:
The diskette having the permanent magnet generator according to claim 1, wherein the diskette has a diameter of 0.1 to 1.0 mm. 3. The thickness of the magnetic shield ring plate is:
The diskette having the permanent magnet generator according to claim 1, wherein the diskette has a diameter of 0.1 to 0.5 mm. 4. The diskette having a permanent magnet generator according to claim 1, wherein said magnetic shield ring plate is made of a material having a magnetic permeability of 50 or more.