JP2003111369A - Thin-model permanent magnet type generator and diskette fitted with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin-model permanent magnet type generator which is thin, does not have wasteful spaces, and is reduced in cogging torque simultaneously. SOLUTION: This is a thin-model permanent magnet generator which has a disk 11 of a soft magnetic substance which rotates with a shaft, and a permanent magnet 212 fixed to one end surface of the disk. The permanent magnet has a plurality of rotor poles 213, 214, etc., arranged side by side in the circumferential direction. These poles are formed in a disk-shaped rotor 21 into polarities differently and alternately in the circumferential direction. Moreover, the generator has a stator 22 provided with a plurality of pole teeth 221 which have, at one-side ends, a plurality of stator poles 222 opposed to the rotor poles with axial magnetic air gaps between, and stretch toward the radial outside from the stator poles, coils 224 wound between the pole teeth, and a yoke 223 of a soft magnetic substance which connects the other ends of the pole teeth to one another. Soft magnetic pieces 228, 228' are formed in at least parts of the stator pole surfaces opposed to the rotor poles, when the rotor is stopped so as to make the stator poles opposed to the rotor poles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet generator, and more particularly, it can be incorporated in a diskette to be inserted and attached to a flexible disk drive, and when a memory such as a magnetic card is incorporated in the diskette, the memory is inserted. The present invention relates to a permanent magnet generator that can be used as an output power source.

[0002]

2. Description of the Related Art Information such as personal health checkup results is stored in an IC card, and when an IC card is brought to a medical institution or the like, medical treatment is performed based on the information in the IC card. It can be performed, and the contents of the medical record at the time of medical treatment can be stored in the IC card. In addition, the use of IC cards as electronic money is also being considered. That is, the IC card stores the bank account of the person who uses it, the personal identification number, and the balance of the account if necessary, and each time the money is spent, communication settlement with the bank account is performed via the IC card. is there.

Since the image information of a digital camera has a relatively large amount of information, it has been proposed to store it in a flash memory having a large capacity. Since the flash memory has a capacity of several megabytes to 10 megabytes, it is possible to store the imaging information of the digital camera in the flash memory and connect the flash memory to the personal computer to perform processing on the personal computer. By storing the result in the flash memory, no additional external storage device such as MO is required.

Both IC cards and flash memories require their own devices as their input / output devices, and their necessity hinders their widespread use. A flexible disk drive, particularly a 3.5 ″ flexible disk drive is generally used as an input / output device of a computer, particularly a personal computer which is widely used.
IC with 3.5 "Flexible Disk Drive
It is thought that the spread will be accelerated if the input / output of cards and flash memory can be performed. It is also considered to use a 3.5 ″ flexible disk drive to input / output an IC card, flash memory, or the like.
An adapter that can be inserted and installed in a 5 ″ flexible disk drive has also been proposed.
A 5 ″ flexible disk drive has a magnetic head for inputting / outputting information between a 3.5 ″ diskette (normal 3.5 ″ flexible diskette) to be inserted therein and a drive shaft for rotating the flexible disk at 300 rpm. However, it does not have a power supply terminal, so a button-type battery is used in the adapter as the power source for the CPU incorporated in the diskette-shaped adapter. It will be consumed as a result, so it will need to be replaced every few months at the longest.

Therefore, it would be extremely useful if a generator was incorporated in this diskette and the generator could be operated by using the rotation of the drive shaft of a 3.5 "flexible disk drive, which would be extremely useful. In order to use a diskette as an input / output device for information with a memory card having a magnetic stripe such as an IC card, it is necessary to provide a space for the memory card on the diskette. The size of a memory card is usually 85
The width is mm, the width is 54 mm, and the thickness is 0.8 mm. Since this thickness ignores embossing, it actually becomes a little thicker. If a space for this memory card and a permanent magnet generator are installed in the diskette, they will overlap, so in a 3.5 "diskette with a thickness of 3.5 mm,
If the thickness of both sides of the cover is 0.2 mm, the thickness of the memory card is 0.8 mm, and if there is enough room to insert and remove it, the thickness of the generator should be about 2 mm. is there.

The thickness t allowed for a permanent magnet generator that can be incorporated in a 3.5 "diskette is 2.0 to 2.5 mm as described above, but the size (width and length) S) is allowed up to a size close to that of a 3.5 ″ diskette, and when the size is expressed by the diagonal length d (mm), the diagonal length d becomes 90 mm. t: 2.3 mm,
If d: 90 mm, the aspect ratio (t / d) is about 2.
6%.

As a commercially available motor or generator having a small thickness, there is an FDD spindle motor. A commercially available thin motor is illustrated in Table 1, and the position of the gap of the permanent magnet for the motor is also shown together with the diagonal length d, the thickness t, and the aspect ratio (t / d) of each. As can be seen from Table 1, the aspect ratio of the generator that can be incorporated in the 3.5 ″ diskette is extremely small as compared with the commonly used thin motors and generators.

[0008]

[Table 1]

It has already been proposed to incorporate a generator in a 3.5 "diskette, and Japanese Patent Publication No. 7-
86912 (US Pat. No. 5,159,182) and PCT International Publication Gazette No. 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 structure is not shown. In addition, special table flat 7-5002
No. 38, a permanent magnet that rotates with a hub is attached as a generator incorporated in a 3.5 ″ diskette, and the hub with the permanent magnet is rotated by a drive shaft of a flexible disk drive. This permanent magnet has a cylindrical shape and is magnetized in the direction of the rotation axis so that there are many magnetic poles on both end faces of the cylinder. The stator coils are arranged so as to sandwich the stator coil between the stator yokes on both sides of the cylindrical permanent magnet.

A permanent magnet generator having a size that can be incorporated into a 3.5 "flexible diskette as disclosed in Japanese Patent Publication No. 7-500238, and a cylindrical rotor permanent magnet. Consider a magnet which is magnetized in the direction of the rotation axis so as to have a large number of magnetic poles on both end faces of the cylinder.
In this case, the stator magnetic poles are arranged on both sides of the cylindrical end face with a small magnetic gap therebetween. Since the thickness allowed for the generator is 2.0 to 2.5 mm, the thickness of the permanent magnet is 0.
Only 5 to 0.8 mm is allowed. In this way, a magnet having a short magnetic pole size has a small magnetomotive force even if a magnet having a large coercive force is used. Further, since both end surfaces of the cylindrical permanent magnet are opposed to the stator magnetic pole via the magnetic gap, it is necessary to make the rotor rotate without mechanical interference with the stator magnetic pole. A few millimeters of void is required. In order to secure the air gap of this size, even if the thickness of the permanent magnet is set to 0.5 mm, the thickness of the stator magnetic pole becomes 0.5 mm or less, and the magnetic flux cannot be sufficiently passed. Further special table flat
In No. 7-500238, since the stator coil is provided away from the stator magnetic pole, the magnetic path is long. Combined with the use of thin stator poles, the magnetic reluctance was large, so it was inevitably a generator with a small output.

The present applicant has already proposed a diskette having a new permanent magnet generator that can be used for this purpose, and has filed a patent application No. 10-224051 (US application No. 09 / 369,420,
Filing date August 6, 1999, European Published Patent No. EP0978930
A1 and publication date February 9, 2000). The diskette filed in this application is shown in FIG. The diskette 9 shown in the figure has a permanent magnet generator 90 incorporated around a hub 911 in the center thereof, and an annular permanent magnet 912 having magnetic poles on its outer peripheral surface can rotate together with the hub. The stator 92 of the generator is provided on the outer periphery of the permanent magnet 912 of the rotor 91 with a magnetic gap between the permanent magnet 912 and the magnetic poles on the outer peripheral surface of the permanent magnet 912, and is mounted inside the diskette. Note that FIG.
, 95 is a memory card insertion space, 96 is a card contact terminal, 97 is an input / output terminal, and 98 is a CP.
U and 99 are stabilized power supply circuits.

[0013]

The permanent magnet type generator filed in Japanese Patent Application No. 10-224051 has a rotor having magnetic poles on the outer peripheral surface of an annular permanent magnet. Stator magnetic poles are arranged on the outer circumferential surface at positions that can face the magnetic poles, and have magnetic pole teeth extending radially outward from each of the stator magnetic poles. In order to increase the output of the permanent magnet generator, the permanent magnet used is one that has as large a coercive force and residual magnetic flux density as possible, preferably an anisotropic sintered NdFeB magnet. The number of coils wound around each magnetic pole tooth is 6000 turns in total.

However, since the rotation of the flexible disk drive is used as it is to rotate the rotor, the rotation is usually as small as 300 rpm. Therefore, although the sintered NdFeB magnet having excellent magnetic characteristics was used as the rotor permanent magnet, the output was at most 20 mW.

The inventors of the present invention have made various studies to obtain a large output, but in the generator shown in Japanese Patent Application No. 10-224051, the output should be greatly improved except for increasing the rotational speed of the rotor. It turns out that you can't. This means that the magnetic flux area entering the magnetic pole teeth is small because the individual magnetic pole areas of the rotor permanent magnets used are small, and the leakage magnetic flux from the magnetic poles of the rotor permanent magnets is large, and the magnetic shield This is because it is necessary to attach the magnetic flux to prevent the magnetic flux from leaking from adversely affecting the surroundings, which would increase the magnetic flux loss and reduce the effective magnetic flux amount.

In order to increase the output of the generator as much as possible without causing distortion, the rotor poles of the permanent magnet are arranged at equal angular intervals, and the number of stator poles of the stator yoke is set. Same as the number of permanent magnet rotor poles,
It is necessary to make the stator magnetic poles face the rotor magnetic poles. However, in this case, the force of magnetic attraction and repulsion between the stator magnetic pole and the rotor magnetic pole becomes large, and so-called cogging torque becomes large.

Therefore, the present invention is to provide a permanent magnet type generator which is thin and has no wasted space so that it can be incorporated in a diskette, for example. At the same time, it is an object of the present invention to provide a permanent magnet type generator that can obtain a large output and reduce cogging torque. More specifically, the present invention provides a thin permanent magnet generator in which a low torque driving source such as a 3.5 "flexible disk drive smoothly rotates and a stable output is obtained. Another object of the present invention is to provide a diskette incorporating this thin permanent magnet generator.

[0018]

DISCLOSURE OF THE INVENTION The present invention has a soft magnetic disk that can rotate about a rotation axis and a permanent magnet fixed to one end surface of the disk. The magnet has a plurality of rotor magnetic poles arranged in the circumferential direction on the surface opposite to the disc, and the plurality of magnetic poles are discoidal rotors having different polarities alternately in the circumferential direction. And a plurality of magnetic pole teeth each having at one end a plurality of stator magnetic poles that can face the rotor magnetic poles through an axial magnetic gap, and extend radially outward from the stator magnetic poles, A coil is wound between the magnetic pole teeth, and the other end of the magnetic pole teeth has a stator coupled to each other by a soft magnetic yoke so that the stator magnetic pole faces the rotor magnetic pole. With the rotor stopped, at least the stator pole faces facing the rotor poles In part, a thin permanent magnet generator, wherein a soft magnetic strip is provided.

In the thin permanent magnet generator of the present invention, at least two rotor magnetic poles that do not face the stator magnetic poles are continuous, and face the rotor magnetic pole that does not face the stator magnetic pole. It is preferable that the magnetic pole surface of the stator is provided with soft magnetic material pieces connecting the magnetic poles on both sides of the rotor magnetic pole, which continuously has at least two poles. Further, it is preferable that an axial groove is provided on the surface of the soft magnetic material piece that faces the stator magnetic pole.

The present invention has a soft magnetic disk that can rotate about a rotation axis and a permanent magnet fixed to one end surface of the disk. The permanent magnet is a disk. A disk-shaped rotor having a plurality of rotor magnetic poles arranged in the circumferential direction on the opposite surface, and the plurality of magnetic poles having different polarities alternately in the circumferential direction, and the rotor magnetic pole. Between each of the plurality of magnetic pole teeth, which have at one end a plurality of stator magnetic poles that can face each other via an axial magnetic gap and extend radially outward from the stator magnetic pole, and between the magnetic pole teeth. The coil is wound around, the other end of the magnetic pole tooth has a stator coupled to each other by a soft magnetic material yoke, and the magnetic pole tooth portion is divided into at least two blocks, and
The thin permanent magnet generator is characterized in that the magnetic pole teeth in each block are substantially parallel to each other. At this time, the stator magnetic poles extend radially from a position where they can face the rotor magnetic poles via an axial magnetic gap, and then extend in a lateral straight line and are connected to magnetic pole tooth portions that are adjacent to each other in parallel, At this time, it is preferable that the intervals between the adjacent magnetic pole teeth are unequal intervals.

Further, the present invention is a diskette characterized by incorporating the above-mentioned thin permanent magnet type generator.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of a diskette in which the permanent magnet generator of the present invention is incorporated will be described first. Although the description will be given using a diskette having a structure that can be attached to the most widely used 3.5 ″ flexible disk drive, it will be apparent from the following description that a diskette having another size or structure can be applied. Of course, the permanent magnet generator of the present invention is not limited to diskettes. A 3.5 ″ diskette (commonly referred to as a 3.5 ″ flexible disk) 1 is shown in FIG. It has the structure shown in the plan view (bottom view), and its size is 94 mm in length and 90 in width.
It is a plastic case with a thickness of 3.5 mm and a thickness of 3.5 mm. FIG. 2 shows a plan view with the back plate (cover 14) removed. There is an opening 13 at one end of the case for making an electromagnetic contact with the input / output magnetic head. At a substantially central portion of the case, there is a hub 11 adapted to transmit the rotation of the drive shaft of the flexible disk drive. In the case of a flexible disk, this hub has a magnetic recording disk mounted coaxially with it so that it can rotate. Since the diskette 1 shown in FIGS. 1 and 2 is used as an input / output device for a memory card, it has a space 15 into which the memory card can be inserted, and a card contact terminal for exchanging information with the memory card. 16 are provided.

An input / output terminal 17 for exchanging information between the diskette and the magnetic head of the flexible disk drive is provided at the opening 13 opened for the magnetic head to enter. A CPU 18 is provided between the input / output terminal 17 and the card contact terminal 16 to process information. The permanent magnet generator 2 is used as a power source for driving the CPU 18 and the card contact terminal 16 and the like, but the output power from the generator may contain ripples and the like, and thus requires rectification and stabilization. The stabilized power supply circuit 19 is incorporated in the output line of the generator 2 provided in the diskette.

When the hub 11 of the diskette engages with the drive shaft of the flexible disk drive and the drive shaft rotates, the rotor 21 of the permanent magnet generator 2 is rotated.
Is rotated. In the case of a 3.5 ″ flexible disk drive, the rotation speed is usually 300 rpm. Since the hub 11 engages with the drive shaft of the flexible disk drive in this manner, the structure of the engaging portion of the hub 11 with the drive shaft is It is preferable to keep the same structure as the hub of a normal diskette.

As the memory card, an IC card or an ordinary magnetic card, which has the same size as a credit card and has a length of 85 mm, a width of 54 mm and a thickness of 0.8 mm can be used. What is called smart media can also be used.

As shown in FIG. 1, since the permanent magnet generator and the space for inserting the memory card are overlapped with each other in plan view, if the diskette has the same size as a 3.5 "diskette, its thickness Since the thickness is 3.5 mm, if the thickness of the diskette case cover required is 0.2 mm, it is necessary to set the thickness of the permanent magnet generator to about 2.3 mm.

When a smart medium smaller than an IC card is used as a memory card, it is possible to prevent the memory card insertion space 15 and the generator from overlapping, so that the thickness of the generator in the rotation axis direction is about 3 mm. Can be thickened.

Of course, the diskette shape is 3.5 "
If it is a little thicker than the diskette, say 4.0
If it becomes ~ 4.5mm, the thickness allowed for the generator is 3.5.
It can be set to 4.0 mm.

In a diskette 1 incorporating a permanent magnet type generator according to an embodiment of the present invention, a hub 11 is provided substantially at the center of the diskette 1, and a permanent magnet type generator 2 having the hub at the center portion is a diskette. Built in. A plan view (view from the side of the hub 11), a sectional view and a bottom view (view from the side opposite to the hub 11) of the permanent magnet generator are shown in FIGS. Here, the sectional view FIG. 4 is also a partial sectional view of FIGS. 1 and 2, in which a diskette cover 14 and a memory card insertion space 15 are provided.
Are shown. The rotor 21 of the generator 2 is the hub 1
It is fixed to the one end surface of the hub 1 and rotates with the hub 11. The rotor 21 of the generator has a disk-ring-shaped permanent magnet 212 that is rotatable about its rotation axis. Disc-shaped permanent magnet 2
Reference numeral 12 has a plurality of rotor magnetic poles arranged in the circumferential direction on one end face in the axial direction thereof, and these rotor magnetic poles have different polarities alternately in the circumferential direction. FIG. 6 is a perspective view of the disk-ring permanent magnet 212 of the preferred embodiment, FIG. 7 is an upper plan view thereof, and FIG. 8 is a bottom view thereof. As shown in FIGS. 6, 7 and 8, the disc ring-shaped permanent magnet 212 is magnetized in the axial direction alternately in opposite directions, and magnetic poles adjacent to each other in the circumferential direction on the disc end face alternate. Have different polarities. That is, as shown in FIG. 7, the disc ring-shaped permanent magnet 212 has N, S, and
It has magnetic poles with polarities of N, S, ..., And on the other end face, S, N, S, clockwise from the top of the figure as shown in FIG.
It has magnetic poles with N ... Since the hub 11 is preferably made of a soft magnetic material in the shape of a disk, it may be referred to as a "soft magnetic disk-shaped hub". The hub 11 is fixed to one end surface of the disk ring-shaped permanent magnet, and magnetic poles on the one end surface of the disk ring-shaped permanent magnet are magnetically coupled to each other. Only the magnetic poles on the other end face of the disc ring-shaped permanent magnet act as rotor magnetic poles.

The permanent magnet generator 2 that can be installed in a 3.5 "diskette has a thickness of about 2.3 mm as described above. Its size is at most 84 in width.
mm and the length is 34 mm. The maximum width of the permanent magnet generator that can be installed in the 3.5 "diskette is 90mm, so the maximum width is 8mm.
It will be 4 mm. Further, since the distance from the center of the hub to the center side end of the opening 13 is about 17 mm, the length on one side of the permanent magnet generator 2 having the rotor 21 that rotates with the hub also needs to be within 17 mm, which is the maximum. 34m long
m. Since the diagonal length d of this permanent magnet generator 2 is 90 mm at the maximum, the aspect ratio (thickness t / diagonal length d) in that case is about 2.5%. The width and length of the permanent magnet generator can be made smaller, but it is impossible to make the diagonal length 40 mm or less from the viewpoint of the required output, so the maximum aspect ratio is 6%.

According to a preferred embodiment of the present invention, a disc ring-shaped permanent magnet 212 is concentrically fixed to one end surface of the soft magnetic disc-shaped hub 11 to form the rotor 21. Since the rotor 21 is engaged with an external drive mechanism, that is, the drive shaft of the FDD and is rotated about the rotation axis, the rotor 11 is connected to the hub 11 by a drive shaft as shown in FIG. 4 and FIG. Has an engaging portion 111 of.
The engaging portion 111 includes a central hole 112 provided at the center of the hub and a concave hole 11 located at a position about 9 mm away from the central hole on the hub surface.
It consists of three. The drive mechanism of the FDD is approximately 9 from the center of the center shaft attached to the spindle motor.
Hooking pin of 4 mm diameter (protrusion amount 0.
5 mm) is attached. Center hole 1 provided in the center of the hub
The center shaft is fitted to 12. Further, the hooking pin fits into the recessed hole 113 which is eccentric from the center of the hub surface, and transmits the rotation of the spindle motor to the rotor 21.

Since the thickness of the hub 11 is set to about 0.6 mm, the recessed hole 113 is provided as a through hole provided in the hub, and the recessed hole following this through hole is formed into the disc ring-shaped permanent magnet 21.
It is desirable that the permanent magnet is not pressed by the pin even if the hooking pin of the external drive mechanism fits into the recessed hole 113 by being provided on the joint surface of the second hub. If a concave hole is formed in the permanent magnet, the inner surface of the concave hole is exposed to the outside through the opening of the concave hole. Therefore, the bottom plate 114 made of a soft magnetic material is adhered to the bottom surface of the concave hole of the permanent magnet 212. That
This is preferable from the viewpoint of preventing magnetic leakage.

9 mm from the center of the center hole 112 in the radial direction
The outer diameter of the hub 11 and the permanent magnet 212 is at least 2 in order to provide the recessed hole 113 of 4 to 5 mm at a separated position.
It will preferably be 4 mm.

In order to prevent the permanent magnet type generator from interfering with the opening 13 of the diskette opened for the FDD magnetic head to enter, the outer diameter of the permanent magnet type generator must be at most 34 mm. Accordingly, the outer diameters of the hub 11 and the permanent magnet 212 are set to 34 mm or less.

In the permanent magnet generator of the present invention, as shown in FIGS. 3, 4, 5 and 9, a disc-ring permanent magnet is formed on one end surface of the soft magnetic disc-shaped hub 11. 21
2 is fixed concentrically with the hub. The hub 11 is slightly larger than the outer diameter of the permanent magnet 212, and the outer circumference of the hub is preferably 0.3 mm or more from the outer circumference of the permanent magnet.
More preferably, the protrusion is 0.5 mm or more. Since one end surface of the hub is exposed to the outer surface of the generator, it is preferable to reduce magnetic leakage from the outer circumference of the hub to the outside of the generator. The relationship between the leakage magnetic flux density (G) from the outer circumference of the hub to the outside and the dimension (mm) of the outer circumference of the hub protruding from the outer circumference of the permanent magnet is shown in FIG.
As shown in 0, the leakage magnetic flux density becomes half or less when the protrusion amount is 0.3 mm or more, and becomes the minimum when the protrusion amount is 0.5 mm or more.

As is apparent from the above description, the outer diameter of the hub and the permanent magnet is 24 to 34 mm, and the outer diameter of the permanent magnet is set to be 0.6 mm or more (0.3 mm or more in radius) smaller than the hub outer diameter. It is preferable to keep.

The stator 22 of the generator has a plurality of magnetic pole teeth 221.
Each of the magnetic pole teeth 221 has a stator magnetic pole 222 at one end thereof at a position where it can face the rotor magnetic pole via an axial gap. Therefore, as shown in FIGS. 3 to 5, the stator magnetic poles 222 of the magnetic pole teeth 221 are the disc ring-shaped permanent magnets 21.
2 is on the end face opposite the hub 11. That is, the plurality of magnetic poles on one end surface of the disk ring-shaped permanent magnet 212 are magnetically connected to each other by the soft magnetic disk-shaped hub 11, and the plurality of magnetic poles on the other end surface of the disk ring-shaped permanent magnet 212 are connected to each other. The magnetic pole can face the stator magnetic pole 222 or can face the stator magnetic pole 222.

The pole pitch of the stator poles 222 is the same as the pole pitch of the rotor poles, but the spacing between adjacent stator poles varies depending on the width of the poles. The wider the stator magnetic pole width, the more effectively the magnetic flux emerging from the rotor magnetic pole can be guided into the magnetic pole teeth, but the magnetic leakage between the magnetic pole teeth also increases. Therefore, the gap between the stator magnetic poles is set to 0.3 mm to 1.0
It is preferably about mm.

The plurality of magnetic pole teeth 221 are connected to each other at the other end by a soft magnetic material back yoke 223.
As is clear from FIGS. 1 to 5, the rotor 21 has a 7
Four magnetic pole teeth 221 are provided, and four magnetic pole teeth 2 are provided on the right side.
21 are provided, and the left and right magnetic pole tooth groups are magnetically coupled by one soft magnetic back yoke 223 each. By dividing the magnetic pole teeth 221 into left and right groups in this way, the contour of the permanent magnet generator 2 can be made substantially rectangular. As a result, the outline of the permanent magnet generator 2 and the input / output terminal 17
It is possible to prevent interference with the card contact terminal 16 and other electronic devices. Generator housing 2
The rotor 21 and the stator 22 are held by 3 and the housing 23 is fixed to the diskette cover 14.

A stator coil 224 is wound around an intermediate portion between one end and the other end of the plurality of magnetic pole teeth 221. The stator coils 224 are connected in series or so that the total output can be obtained by adjusting the output phase, but the method of connecting them is obvious to those skilled in the art, and therefore description thereof is omitted.

In the permanent magnet generator of the present invention, as shown in FIGS. 4 and 9, the magnetic pole teeth 221 and the rotor permanent magnet 212 are used.
Are opposed to each other through a small axial gap, the rolling bearing 26 supports between the stator and the rotor, and maintains this gap size against the thrust load.

The tips of the magnetic pole teeth 221, that is, the tips of the magnetic pole teeth on the side having the stator magnetic poles, are fixed and positioned on the bush 25, and the rolling bearing 26 is provided between the bush 25 and the hub 11. Even if a large thrust load is applied, the rotor can be easily rotated by the rolling bearing. It is preferable that the hub surface and the bush surface, which are in contact with the balls of the rolling bearing, have a hardness of HRC 35 or more in order to prevent abrasion. As a material of the hub, for example, a material obtained by subjecting a magnetic stainless steel to a surface nitriding treatment or a hardened carbon steel (JISS45C) is preferable. Bush 2
Since it is necessary to make the portion of No. 5 near the tip of the magnetic pole tooth non-magnetic, it is preferable to use beryllium copper material, non-magnetic stainless steel, or the like. Further, if a U-shaped groove 115 is provided in a portion of the hub surface where the balls of the rolling bearing contact and rotate, the relative position of the bearing and the hub is fixed.

The disk-shaped permanent magnet 212 has a length of 12 m in order to prevent interference with the rolling bearing 26 and its retainer.
It must have an inner diameter of at least m. Further, the tip of the magnetic pole tooth on the magnetic pole side protrudes radially inward in the central opening of the disk-shaped permanent magnet 212 by preferably 0.3 mm or more, more preferably 0.5 mm or more. By protruding by 0.3 mm or more, the leakage flux from the permanent magnet to the rear of the tip of the magnetic pole tooth can be reduced to half or less. Further, when the protrusion is 0.5 mm or more, the leakage magnetic flux can be minimized.

As shown in FIG. 4 which is a sectional view of the permanent magnet generator 2, each magnetic pole tooth 221 has a substantially S-shaped longitudinal cross section with a step in the central portion of the magnetic pole tooth 221. . As a result, each magnetic pole tooth 221 is located on the bottom surface of the generator at the end portion having the stator magnetic pole 222, and at the intermediate portion around which the stator coil 224 is wound and the other end portion connected to the back yoke 223. It is located in the center of the generator in the thickness direction. By adopting this structure, the total thickness of the hub, the permanent magnet, the magnetic gap, and the magnetic pole teeth is equal to the thickness of the stator coil (since the stator coil is wound around the magnetic pole teeth, , And can be close to 2.0 mm).

In order to form a step in the central portion of the magnetic pole tooth, an inclined portion is provided at the step, and the inclined portion has an angle of 30 ° to 60 ° with respect to the length direction of the entire magnetic pole tooth. Good. If the angle becomes too large, the cross-sectional area of the bent portion becomes small, and the magnetic resistance may increase extremely.

In this case, if the hub thickness is 0.8 mm, the permanent magnet thickness is 0.5 mm, and the size of the magnetic gap is 0.2 mm, the thickness of the magnetic pole teeth can be about 0.8 mm. Thus, the total thickness becomes 2.3 mm. If the thickness of the stator coil portion is 2.0 mm and the thickness of the generator housing is 0.3 mm, the total thickness is 2.3 mm. In this way, the thickness of the generator portion can be kept within 2.3 mm from the end surface of the diskette case on the back plate side.

Here, it is verified that when the magnetic pole teeth 221 having a thickness of 0.8 mm are used, the magnetic pole teeth can pass the magnetic flux generated from the rotor permanent magnet.

Let N be the number of magnetic poles of the rotor permanent magnet, R be the outer radius, r be the inner radius, SR be the area per pole, Bd be the magnetic flux density at the operating point, and Bg be the average magnetic flux density in the magnetic gap. When the thickness of the magnetic pole teeth is t, the tooth width of one pole is Ws, and the saturation magnetic flux density is Bs, the following conditions must be satisfied in order for all the air gap magnetic fluxes to pass through the magnetic pole teeth. . SR · Bg− (leakage magnetic flux) ≦ Ws · t · Bs If the leakage magnetic flux is ignored, SR · Bg ≦ Ws · t ·
Bs.

If the distribution of the surface magnetic flux density of the rotor magnetic poles of the rotor permanent magnet (that is, the magnetic flux density of the magnetic air gap) is a sine curve, the magnetic flux density Bd between the operating point and the average magnetic flux density Bg of the magnetic air gap will be described. Has a relationship of Bg = 2 / π · Bd. From these equations, SR · 2 / π · Bd ≦ Ws · t · Bs, and further Ws≈2πR / N, so π / N · (R2−r2) · 2 / π · Bd ≦ 2πR / N ·
From t · Bs, Bd ≦ πRt / (R2 −r2) · Bs.

As shown in FIGS. 3 and 4, the rotor permanent magnet 212 has the same outer diameter as the hub 11 of the 3.5 "flexible disk, that is, the outer radius is 12 mm.
The inner radius is 6 mm. When normal soft iron is used as the magnetic pole teeth, the saturation magnetic flux density Bs is 1.5 T or more,
Since electromagnetic soft iron is 2.2T or more, Bs is set to 1.7T. Further, the magnetic pole tooth thickness t is set to 0.8 mm, which is the same as the above example. If these numbers are added to the above formula, Bd ≦ π · 12 ·
Since 0.8 / (144-36) · 1.7 = 0.47 (T), all the magnetic flux can be passed through the magnetic pole teeth when the magnetic flux density at the operating point is 0.47T or less. . Since the magnetic circuit has magnetic leakage of at least several tens of percent and also has magnetic resistance, the magnetic flux density at the operating point is 0.6T.
It can be seen that up to a point all magnetic flux can pass through the pole teeth.

As described above, the magnetic pole teeth used in the present invention have a small magnetic resistance, and easily pass the magnetic flux. Since the stator coil is wound in the middle of these magnetic pole teeth, it is possible for the stator coil to pick up the change in the magnetic flux due to the rotation of the permanent magnet rotor without waste, so that the generator output is large. can do.

The magnetic pole teeth 221 and the back yoke 223 of the stator 22 are both made of a soft magnetic material. It is preferable that the saturation magnetic flux density Bs is large from the viewpoint of reducing the cross-sectional area of the component and the size of the entire generator. Therefore, the saturation magnetic flux density Bs is 1.2 T or more, preferably 1.
5T or more of soft iron, electromagnetic soft iron, dust core, silicon steel sheet containing 4 to 6% Si or low carbon steel having a carbon content of 0.05 mass% or less is heat-treated and strained (magnetic What has been annealed) can be used for the stator pole teeth. However, since the back yoke does not pass as much magnetic flux as the magnetic pole teeth, it is possible to use low carbon steel having a carbon content of 0.6 mass% or less.

As the permanent magnet 212 used in the rotor 21, a segment permanent magnet, a rectangular parallelepiped permanent magnet, or a disk-shaped permanent magnet can be used. However, FIG.
A disk ring-shaped permanent magnet as shown in FIG. 8 is preferable. The permanent magnet 212 is fixed to one end surface of the hub 11 with an adhesive or the like. The permanent magnet has an appropriate length, that is, a thickness in the rotation axis direction. The thickness of the thin permanent magnet generator that can be incorporated into a 3.5 ″ diskette is 2.0 to 2.5 mm, so the thickness of the permanent magnet is 1.0 mm at the most, and 0.3 to 1.0 mm is used. However, it is preferably 0.3 to 0.8 mm.
That is, the thickness of the permanent magnet in the magnetization direction is approximately 10% or more and 30% or less, preferably approximately 10% of the diskette thickness.
It is above 23%. In order to reduce the magnetic resistance in the magnetic air gap, the air gap between the magnet and the stator magnetic pole is 2% or more and 15% or less, and more preferably 5% or more and 15% or less of the thickness of the diskette. However, it is clear that this size will vary depending on the size of the diskette used and the configuration of the equipment with which it is incorporated.

It is desirable from the viewpoint of magnetomotive force that the thickness of the disk-shaped permanent magnet 212 in the magnetization direction is as thick as possible. However, if a soft magnetic material piece, for example, a hub 11 made of a soft magnetic material is adhered to one end face and magnetic poles on the end face are magnetically short-circuited, the effective magnetic pole distance becomes long.

As a characteristic of the permanent magnet, it is preferable that the magnetic flux density distribution along the rotor magnetic pole surface has a substantially sine curve. This magnetic flux density distribution can be measured with a Gauss meter or the like along the magnetic pole surface of the magnetized rotor permanent magnet. By combining the stator and the rotor, placing a Gauss meter probe on the stator, and rotating the rotor, the magnetic flux density distribution in the closed magnetic circuit can be measured. What was measured without using the stator is the magnetic flux density distribution in the open magnetic circuit.

When the distribution of the magnetic flux density has a substantially sine curve, there is no abrupt change in the magnetic flux density between the magnetic poles of the rotor, so the cogging torque of the rotor becomes small. On the adjacent magnetic poles, the vicinity of the center is magnetized most strongly and becomes weaker away from it, and the magnetization reversal point (where the radial component of the magnetic flux density is almost zero) is located at the center between two magnetic poles of different polarities. It is magnetized in a certain way, and the magnetic flux density distribution is almost sine curve. Since the attraction force between the stator magnetic poles and the rotor magnetic poles is determined by this magnetic force, the cogging torque can be reduced by the sine curve-shaped magnetic flux density distribution.

When the magnetic poles of the magnetic pole teeth are made to face the rotor magnetic poles at the same time, several poles of the rotor magnetic poles do not face the magnetic pole teeth (stator) magnetic poles in FIG. As shown in FIG. 5, soft magnetic material pieces 228, 228 'are provided at positions facing the rotor magnetic poles, which do not face the stator magnetic poles. FIG. 11 is an enlarged cross-sectional view taken along the line 11-11 of FIG. 5 in order to facilitate understanding of the positional relationship between the soft magnetic piece 228 and the rotor permanent magnet. Soft magnetic material piece 228
Starts from the middle of the rotor magnetic pole S213 and the rotor magnetic pole N214 and extends to the middle of the rotor magnetic pole S217 and the rotor magnetic pole N218 facing the rotor magnetic poles N214, S215, N216 and S217. The soft magnetic piece 228 connects the middle of five continuous rotor magnetic poles. The soft magnetic piece 228 'starts from the middle of the rotor magnetic poles S213' and N214 'to N214'.
And extend halfway between N214 'and S215',
It connects two consecutive middle points. Soft magnetic material pieces 228, 22
8'is an axial groove 2 on the surface facing the south pole and the north pole.
29 and 229 'are provided (see FIG. 11).

When the stator magnetic pole comes to a position facing the rotor magnetic pole, the soft magnetic material piece 2 for connecting the magnetic poles is formed on the inner peripheral 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 and 229 'are provided on the soft magnetic pieces 228 and 228' at positions facing the rotor magnetic poles. Therefore, when the rotor magnetic pole is displaced from the stator magnetic pole, the rotor magnetic pole is displaced from the position of the groove on the soft magnetic material piece at the soft magnetic material piece, and the rotor magnetic pole is displaced from the soft magnetic material piece. Since it is close to the protruding portion, the soft magnetic material piece is short-circuited between the rotor magnetic poles. At this time, the soft magnetic material piece attracts the rotor magnetic pole facing the protruding portion. On the other hand, when the rotor magnetic pole is in a position facing the stator magnetic pole, the axially extending groove provided in the soft magnetic material piece faces the rotor magnetic pole, so that the rotor magnetic pole remains stationary at that position. Becomes unstable and acts to move the rotor toward the protruding portion of the soft magnetic piece.

The rotor magnetic poles facing the stator magnetic poles try to make the rotor stand still at the facing position.
Since the rotor magnetic pole facing the groove formed in the soft magnetic piece tends to move the rotor from that position, the cogging torque of the rotor becomes small.

The soft magnetic material pieces 228 and 228 '"start from the middle of the rotor magnetic pole S213 and the rotor magnetic pole N214 and extend to the middle of the rotor magnetic pole S217 and the rotor magnetic pole N218. . ", The term" intermediate "does not necessarily mean the exact midpoint between adjacent magnetic poles of different polarities when many magnetic poles are arranged on the end surface of the ring-shaped permanent magnet. Rather, it means the peripheral portion excluding the substantial center of the magnetic pole. If one rotor magnetic pole faces the stator magnetic pole and another rotor magnetic pole faces the groove provided in the soft magnetic material piece, the attractive force at the position facing the groove is reduced. However, it suffices if the end of the soft magnetic material piece is offset from the rotor magnetic pole so that the rotor magnetic pole is attracted to the soft magnetic material piece beside the groove and a rotational moment is applied.

Considering the magnetic flux density and the magnitude of coercive force, a sintered magnet is preferable, and a sintered NdFeB magnet is particularly preferable. As illustrated in FIG. 12, the magnetic characteristics of the sintered NdFeB magnet and the bonded NdFeB magnet are about 2/3 of that of the sintered magnet.

The permanent magnet used in the rotor of the permanent magnet generator according to the embodiment of the present invention described above has a permeance coefficient of 0.8 before being incorporated in the generator and 2.5 in the assembled state. Since the above is preferably about 3, the magnetic flux density at the operating point in the assembled state is about 0.83 in the sintered NdFeB magnet having the magnetic characteristics shown in the graph of FIG.
T (8300G), that of a bonded NdFeB magnet is about 0.58T (5800G). Considering together the cross-sectional areas of the magnetic pole teeth shown above, it can be seen that the bonded NdFeB magnet is sufficient. Sintered NdFeB magnet and bond Nd
Comparing FeB magnets, bonded NdFeB magnets are more preferable in terms of manufacturing cost and ease of manufacturing.

Since the sintered NdFeB magnet is made by sintering, when making a magnet having a thickness of about 0.5 mm, a sintered body having a thickness twice or more that of the sintered NdFeB magnet is grinder-polished to 0. It is necessary to make the thickness 0.5 mm and further polish the inner and outer circumferences to finish it to a desired size. On the other hand, the bonded NdFeB magnet is obtained by compressing a mixture of a resin binder and NdFeB magnetic powder to obtain a disk-ring permanent magnet having a desired size, or rolling the mixture with a roll into a sheet having a desired thickness. After that, a disk ring-shaped bonded magnet can be formed by punching or the like. As described above, the bonded NdFeB magnet is suitable for the present invention not only because its magnetic characteristics conform to the present invention but also because it is easy to manufacture.

As the permanent magnet of the permanent magnet type generator of the present invention, in addition to the NdFeB magnet, (1) a nitride magnet such as S is used.
mFeN magnets, (2) magnets containing α iron in SmFeN, which are called exchange spring magnets, magnets containing α iron in NdFeB, magnets containing Fe 3 B in NdFeB, etc. (3) N
HDDR such as dFeB and SmFeN (hydrogenation / decomposition /
Dehydrogenation / recombination magnets, (4) SmCo magnets, etc. can also be used in consideration of the required characteristics. Of these, a nitride magnet, for example, an SmFeN magnet, is suitable for use in the present invention because it can obtain a sheet-shaped bonded magnet having relatively good characteristics.
The magnetic characteristics on the BH demagnetization curve of the bonded SmFeN magnet are
As shown in FIG. 12, the residual magnetic flux density is 0.47T (47
00G) and a coercive force bHc of 300 kA / m (377
0 Oe). Therefore, the magnetic flux density at the operating point is about 0.33T (3300G), and the output is slightly reduced.

5-8, the disk-shaped permanent magnet 21 is shown.
Although 2 has an end face having 16 magnetic poles, the number of poles is preferably 12 to 24, and more preferably 16 to 20 in the present invention. When the number of poles is small, the amount of magnetic flux per pole is large, but the maximum output of the generator is 16-
It has 24 poles. However, as the number of poles is increased, the space between the magnetic pole teeth extending in the radial direction of the stator becomes smaller. In addition, the stator is difficult to manufacture, and there is a problem that the output voltage waveform is distorted. Therefore, 16 to 20 poles are optimal.

The magnetic poles of the magnetic pole teeth extending outward are preferably at the same angular intervals so that they can face the magnetic poles of the rotor permanent magnet via a magnetic gap.

[0067]

EXAMPLES A diskette incorporating the permanent magnet generator of the present invention will be described in more detail by the following experiments and the conditions for its implementation will be clarified.

Experiments, diskettes incorporating the thin permanent magnet generator according to the present invention shown in FIGS. 1 to 9 (invention) and diskettes incorporating the thin permanent magnet generator according to the present application shown in FIG. (Comparative example)
Its properties were measured. The specifications of these diskettes and permanent magnet generators are shown in Tables 2 and 3, respectively.

[0069]

[Table 2]

[0070]

[Table 3]

[0071]

[Table 4]

Table 4 shows the results of measuring the amount of magnetic flux per rotor pole, the power generation output, and the strength of the leakage magnetic field into the space for inserting the memory card in the permanent magnet generator used for these diskettes. The diskette of the present invention does not have a shield plate between the permanent magnet generator and the memory card insertion space, but the diskette of the comparative example has a shield plate between the permanent magnet generator and the memory card insertion space. If not, the leakage magnetic field is large, so the measured values are also shown for the case where a 0.1 mm permalloy shield plate is attached.

As is clear from this experiment, compared with the comparative example, the amount of magnetic flux per pole is increased and the power generation output is increased in the present invention, although the bonded NdFeB permanent magnet is used. Further, in the comparative example, if the shield plate is not used, the leakage magnetic field strength to the memory card insertion space is large, so that the adverse effect is caused by the leakage magnetic field to the memory card inserted therein. The leakage magnetic field to the insertion space is small.

[0074]

As described above, in the thin permanent magnet generator of the present invention, the output of the generator can be increased even if the inexpensive bond magnet is used. For that, the output
40mW or more can be secured. The diskette incorporating this generator was able to realize an adapter compatible with 5V IC cards, which occupy most of the market. Further, the leakage magnetic field is reduced, and the influence on the memory card and the like and the influence of the leakage magnetic field around the diskette can be eliminated.

[Brief description of drawings]

FIG. 1 is a plan view (bottom view) of a diskette incorporating a permanent magnet generator according to an embodiment of the present invention.

FIG. 2 is a plan view of the diskette of FIG. 1 with a back plate removed.

FIG. 3 is a plan view of a permanent magnet type generator used in the present invention.

4 is a cross-sectional view taken along line 4-4 of FIG. 3 and is a view partially showing the cross-section taken along line 4-4 of FIG.

FIG. 5 is a bottom view of a permanent magnet type generator used in the present invention, showing the bottom of the generator housing.

FIG. 6 is a perspective view of a disc ring-shaped permanent magnet used in the present invention.

FIG. 7 is a plan view of a disc ring-shaped permanent magnet used in the present invention.

FIG. 8 is a bottom view of the disc ring-shaped permanent magnet used in the present invention.

9 is an enlarged cross-sectional view of FIG.

FIG. 10 is a graph showing the relationship between the leakage magnetic flux density and the amount of protrusion of the outer circumference of the hub from the outer circumference of the permanent magnet.

11 is an enlarged cross-sectional view taken along line 11-11 of FIG.

FIG. 12 is a magnetic characteristic diagram of a permanent magnet used in the present invention.

13A and 13B show a diskette having a permanent magnet type generator according to a prior application, FIG. 13A is a plan view thereof, and FIG. 13B is 13B-1.
3B is a cross-sectional view, and (c) is an enlarged view of a main part of (b).

[Explanation of symbols]

1, 9 Diskette 11, 911 Hub 13 Opening 14 Cover 15, 95 Memory card insertion space 16, 96 Card contact terminal 17, 97 Input / output terminal 18, 98 CPU 19, 99 Stabilized power supply circuit 2, 90 Permanent magnet type generator 21, 91 rotors 212, 912 permanent magnets 213, 214, 215, 216, 217, 218, 2
13 ', 214', 215 'Rotor magnetic poles 22, 92 Stator 221 Magnetic pole teeth 222 Stator magnetic poles 223 Back yoke 224 Stator coils 228, 228' Soft magnetic material pieces 229, 229 'Grooves 23 Housing 25 Bushing 26 Rolling bearing

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiko Takahashi             5200 Mikkajiri, Kumagaya-shi, Saitama Hitachi Metals Co., Ltd.             Inside the Advanced Electronics Research Laboratory F-term (reference) 5H002 AA09 AB04 AE07 AE08                 5H621 AA02 BB07 GA04 GA16 GA17                       JK03 JK13

Claims (6)

[Claims] 1. A soft magnetic disk capable of rotating around a rotation axis and a permanent magnet fixed to one end surface of the disk, the permanent magnet being opposite to the disk. A plurality of rotor magnetic poles arranged in the circumferential direction on the side surface, and the plurality of magnetic poles are disc-shaped rotors having different polarities alternately in the circumferential direction; and the rotor magnetic pole and the shaft. A plurality of stator poles that can face each other with a directional magnetic gap at one end, and a plurality of pole teeth that extend radially outward from the stator poles, and a coil between these pole teeth. Is wound, and the other ends of the magnetic pole teeth have a stator coupled to each other by a soft magnetic yoke, and in a state where the rotor is stopped so that the stator magnetic pole faces the rotor magnetic pole. , A soft magnetic material piece is provided on at least a part of the stator magnetic pole surface facing the rotor magnetic pole. Thin permanent magnet generator, wherein a being. 2. A rotor magnetic pole which does not face the stator magnetic pole has at least two poles continuously, and the rotor magnetic pole surface which faces the rotor magnetic pole which does not face the stator magnetic pole has a continuous pole. 2. The thin permanent magnet generator according to claim 1, further comprising soft magnetic material pieces connecting between magnetic poles on both sides of the rotor magnetic pole having at least two poles. 3. The thin permanent magnet generator according to claim 1, wherein an axial groove is provided on a surface of the soft magnetic piece facing the stator magnetic pole. 4. A soft magnetic disk capable of rotating around a rotation axis and a permanent magnet fixed to one end face of the disk, the permanent magnet being opposite to the disk. A plurality of rotor magnetic poles arranged in the circumferential direction on the surface of the disk, and the plurality of magnetic poles are disc-shaped rotors having different polarities alternately in the circumferential direction, and the rotor magnetic pole and the axial direction. A plurality of stator magnetic poles that can face each other via a magnetic gap are provided at one end, and a plurality of magnetic pole teeth extending outward from the stator magnetic pole in the radial direction and a coil are provided between the magnetic pole teeth. The magnetic pole teeth are wound, and the other ends of the magnetic pole teeth have a stator connected to each other by a soft magnetic yoke, and the magnetic pole tooth portions are divided into at least two blocks, and the magnetic pole teeth in each block are Thin permanent magnet type characterized in that they are substantially parallel to each other Denki. 5. The stator magnetic poles extend radially from a position where they can face the rotor magnetic poles via an axial magnetic gap, and then extend in a lateral straight line and are connected to parallel magnetic pole tooth portions adjacent to each other. The thin permanent magnet generator according to claim 4, wherein the magnetic pole teeth adjacent to each other are unequal. 6. A diskette in which the thin permanent magnet generator according to claim 1 is incorporated.