JPH0744991A - Recording disk driving device - Google Patents

Abstract

PURPOSE:To limit the effect of electromagnetic noises. on a recording head by setting the winding number of the magnetic pole coils of at least three magnetic poles corresponding to areas for seeking by the recording head smaller than those of other magnetic coils. CONSTITUTION:Among the magnetic pole coils of an armature coil 6, the winding number of the ones of at least three magnetic poles corresponding to the areas for seeking of the recording head is set smaller than those of the other magnetic pole coils. That is, the coils of these three magnetic poles are disposed so as to include all the areas for seeking by a magnetic head 7. Thus, electricity is conducted to a stator 1, a magnetic flux is generated, electromagnetic noises are generated in a part corresponding to the recording head accompanying it but a radiant level of the electromagnetic noises is made small and thus, the effect of electromagnetic noises on the recording head is limited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording disk drive device for rotationally driving a recording disk such as a magnetic disk or a magneto-optical disk.

[0002]

2. Description of the Related Art For example, as a recording disk drive device for rotationally driving a magnetic disk, there is one disclosed in Japanese Patent Application Laid-Open No. 3-286488. According to this disk drive device, a bracket portion for holding and fixing the device itself,
A hub on which a hard disk is mounted and a bearing provided between the hub and the hard disk are provided, and the hub is rotatably supported by the bracket portion. The hard disk is rotationally driven by the stator provided on the bracket portion and the rotor magnet provided on the hub.

Such recording disk drive devices are being miniaturized, and the storage capacity is increasing and the density is increasing. Therefore, the accuracy and the mounting density of the components to be incorporated are greatly improved. On the other hand, a recording head for reading / writing information from a recording disk has been dramatically improved as compared with the conventional one, and a high-sensitivity one has begun to be adopted.

[0004]

By the way, according to the above-mentioned structure, the stator and the rotor magnet, which are responsible for the rotational drive, are more and more restricted by the space.
In order to obtain the required rotational driving force, a strong magnetic circuit is constructed. For this reason, the recording head is more difficult to escape from the electromagnetic influence generated from this magnetic circuit, and the information read / write failure is more likely to occur than ever before. To deal with this, a leakage flux generated from the stator or the rotor magnet can be dealt with by providing a shield member. However,
Electromagnetic noise generated from the stator (especially electromagnetic interference; EL
ECTRO-MAGNETIC INTERFEREN
CE popular name E.I. M. Say I. In order to reduce the size of the device, there is no such measure, and some improvement is desired.

The present invention has been made in view of the above-mentioned problems existing in the prior art, and its problem is to cope with the miniaturization of the device and the increase in the density and the capacity.
An object of the present invention is to provide a highly reliable recording disk drive device in which electromagnetic interference is effectively prevented and information read / write errors are avoided.

[0006]

In order to achieve the above object, a first means of a recording disk drive device of the present invention is a stationary member, a rotor hub on which a recording disk is mounted, the stationary member and the rotor hub. Bearing means provided between the stationary member and the stator,
And a rotor magnet fixed to the rotor hub and arranged to face the stator, wherein the stator is wound by a plurality of phases of armature coils, and the armature coils are The magnetic pole coils having a plurality of poles are arranged substantially in the same arrangement, and the magnetic pole coil having at least three magnetic poles corresponding to the area to be sought by the recording head has a smaller number of turns than the other magnetic pole coils. It is configured.

Next, the second means of the recording disk drive device according to the present invention is a stationary member, a rotor hub on which a recording disk is mounted, and bearing means provided between the stationary member and the rotor hub. And a stator mounted on the stationary member, and a rotor magnet fixed to the rotor hub and facing the stator, wherein the stator is a multi-phase armature coil. The armature coil is provided with magnetic pole coils having a plurality of poles arranged substantially in the same manner, and the magnetic pole coil corresponding to the region where the recording head seeks is the armature coil of each phase. The same number of poles are applied to each of the magnetic pole coils, and the number of turns of each of the applied magnetic pole coils is set to be smaller than that of the other magnetic pole coils in the relevant phase.

And in the above first and second means,
The number of turns of the magnetic pole coil is set to a magnetic pole coil having a small number of turns:
It is desirable that the magnetic pole coil having a large number of turns = 0.4 to 0.9: 1.

[0009]

According to the first means of the recording disk drive apparatus of the present invention, among the magnetic pole coils of the armature coil, the magnetic pole coils of at least three magnetic poles corresponding to the area to be sought by the recording head are more than the other magnetic pole coils. Also, the number of turns is set to be small. That is, the magnetic pole coil having three magnetic poles is arranged so as to cover the seek area of the recording head.
For this reason, the stator is energized by the commutation signal to generate a magnetic flux, and the electromagnetic noise generated therewith is reduced in the level of generation and radiation at the portion corresponding to the recording head, which causes electromagnetic noise to be given to the recording head. The influence of can be suppressed.

The three magnetic poles serve to close the magnetic fluxes of N poles and S poles generated by the energization of each magnetic pole coil by one magnetic pole and two magnetic pole coils sandwiching the magnetic poles, a total of three magnetic poles. In addition to this, a relatively large (strong) magnetic flux generated from a magnetic pole coil other than the above three magnetic poles is radiated in the circumferential direction, but a magnetic flux from a magnetic pole coil positioned near the above three magnetic poles is It converges to the magnetic pole and is closed. Therefore, the electromagnetic noise generated from the magnetic poles other than the three magnetic poles has a small generation / radiation level particularly near these three magnetic poles, that is, in the area where the recording head seeks, and therefore the influence of the electromagnetic noise on the recording head is prevented. It

According to the second means, among the magnetic pole coils in each phase, the number of turns of the magnetic pole coil corresponding to the region where the recording head seeks is set to be smaller than the number of turns of the other magnetic pole coils of the same phase. ing. Therefore, it operates in the same manner as the above-mentioned first means. Since the magnetic pole coils having a small number of turns applied from each phase are the same in number, the electrical characteristics of the armature coil are well balanced among the phases, and therefore good driving characteristics can be obtained.

Further, in these first and second means,
By setting the turn ratio to 0.4 to 0.9: 1, the generation and radiation level of electromagnetic noise can be further reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a recording disk drive device according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a recording disk drive device according to the present invention. This device drives two magnetic disks for rotation. In FIG. 1, the bracket 1 is in the shape of a shallow dish, and a flange portion 36 protruding to the outer peripheral side is fixed to the base plate 11. The bracket 1 is made of, for example, an aluminum material and has a predetermined shape, and a steel fixed column 13 is firmly fixed to the hole 31 at the center of the bracket 1. A pair of ball bearings 9 and 10 are mounted on the fixed support column 13.
The rotor hub 3 is rotatably supported via. Ball bearing 9,1
The inner and outer rings of 0 are bonded to the outer peripheral surface 23 of the fixed column 13 and the hole 32 of the rotor hub 3, respectively, are positioned by the step 33 of the rotor hub 3, and are fixed in a state in which a preload is applied.

The rotor hub 3 is made of magnetic stainless steel, and the flange portion 20 is coaxially formed on the outermost peripheral portion. The magnetic disk 2 is placed on the upper end of the collar portion 20. The rotor hub 3 has spacers 14 as shown in the figure.
The two magnetic disks 2 and 2 are mounted via the, and the clamp member 15 is mounted by the mounting screw 17, whereby the magnetic disks 2 and 2 are integrally fixed. A hanging portion 37 is formed in an annular shape at a lower portion of the collar portion 20 of the rotor hub 3, and the rotor yoke 12 is caulked and fixed by the hanging portion 37 and the lower end portion of the collar portion 20.
The rotor yoke 12 is formed of steel into an annular shape, and a ring-shaped rotor magnet 5 is fixed to the inner peripheral side thereof. The rotor magnet 5 has a rotor yoke 12
Is positioned on the bent portion and fixed by adhesion. The rotor magnet 5 is magnetized in the circumferential direction in such a manner that N poles and S poles are alternately magnetized.

A stator 4 is arranged so as to face the rotor magnet 5 in the radial direction. The stator 4 is externally fitted and fixed to the annular wall 24 of the bracket 1. The stator 4 is formed by winding a three-phase armature coil around a stator core (which will be described later). The coil lead wire 25 pulled out from the stator is electrically connected to the flexible substrate 19 attached to the bottom portion (notch portion 35) of the bracket 1 through the insulating tube 26. The end of the flexible substrate 19 is led out to the device side.

In order to seal the inside and outside of the device, an adhesive 27 is filled and applied to the lead-out portion of the coil lead wire 25. A magnetic fluid seal 18 is fixed to the outside of the ball bearing 9 (upward in the drawing) via a holding member 30 to seal the inside and outside of the device. (The member 22 is a protective cap.) A labyrinth seal structure is formed outside the ball bearing 10 (downward in the drawing). The labyrinth seal structure has the boss portion 34 of the bracket 1 and the ball bearing 1.
0 side surface, the annular wall 24 of the bracket 1 and the rotor hub 3
Of the bracket 1 and the annular wall 29 of the bracket 1 and the rotor yoke 12, thereby substantially sealing the inside and outside of the device.

When a predetermined electric signal is supplied from the lead-out portion of the flexible substrate 19, the rotor hub 3 is rotationally driven by the electromagnetic action of the stator 4 and the rotor magnet 5. The two magnetic disks 2 and 2 mounted on the rotor hub 3 are sought by the magnetic head 7 shown on the right side of FIG. The (four) magnetic heads 7 are fixed to the four supporting members 8 respectively, and substantially move by seeking in the lateral direction (in the arrow direction) in FIG. An area 38 corresponding to the area where the magnetic head 7 moves is susceptible to electromagnetic influence from the stator 4. Area 38
Can be defined as the moving range of the magnetic head 7 including the portion where the lowermost magnetic head 7 (the lowermost portion in FIG. 1) of the magnetic head 7 is closest to the rotor hub 3.

FIG. 2 is a plan view showing an outline of only the stator 4 in the magnetic disk drive apparatus of FIG. In FIG. 2, an area 38 in which the magnetic head 7 seeks and moves and is easily influenced by the stator 4 is shown in an upward direction toward the drawing. In the stator 4, a three-phase armature coil 6 is wound around a stator core formed by laminating a required number of thin electromagnetic steel plates. As shown in the drawing, nine electromagnetic poles (41 to 49) extending outward in the circumferential direction are provided on the base of the stator core in a substantially even arrangement. The three-phase, that is, the u-, v-, and w-phase armature coils are wound around the respective electromagnetic poles.

Of the three phases shown in FIG. 2, one phase, v
Looking at the phase armature coil, the beginning of winding is the electromagnetic pole 42
Is wound as the magnetic pole coil 4b, the end of the winding is continuously wound around the electromagnetic pole 45 as the magnetic pole coil 4e, and the end of the winding is continuously wound around the electromagnetic pole 48 as the magnetic pole coil 4h. The winding ends of the v-phase are collected together with the winding ends of the other two-phase armature coils, connected as a common line x (Y connection), and extracted. In addition, the winding direction of each magnetic pole coil is wound in the same direction (for example, clockwise rotation) with respect to each electromagnetic pole. The relationship between the electromagnetic poles and the magnetic pole coils in the u-phase and the w-phase is connected according to the connection method shown in FIG. 4, and the winding directions are all the same. (Both armature coils.)

In FIGS. 1, 2 and 4, the number of turns of the magnetic pole coils 4a, 4b and 4c wound around the electromagnetic poles 41, 42 and 43 of the stator 4 corresponding to the region 38 is the same as that of the other electromagnetic pole 44. The number is smaller than the number of turns of the magnetic pole coils 4d to 4i. Therefore, when a predetermined electric signal (commutation signal) is applied to (the armature coil 6 of) the stator 4, N poles and S poles are alternately generated in each electromagnetic pole, and a predetermined rotating magnetic field is generated. Although generated, the electromagnetic poles 41, 42, 4 corresponding to the magnetic pole coils 4a, 4b, 4c
3, the generated magnetic flux is small. For this reason, the generation level of electromagnetic noise including harmonic components due to commutation is small, and radiation to the magnetic head 7 is suppressed. Therefore, even in a region 38 where the magnetic head 7 seeks and approaches the rotationally driven portion and the magnetic head 7 has an electromagnetic action, the influence on the magnetic head 7 is small. For this reason,
Information read / write errors on the magnetic disk 2 by the magnetic head 7 are effectively prevented.

The above-mentioned three electromagnetic poles 41, 42, 43
When the armature coil 6 is energized, acts as follows. By energizing, the magnetic pole coils 4a, 4b, 4c
The N-pole and S-pole magnetic poles are generated alternately in the electromagnetic pole 42 and the electromagnetic poles 41 and 43 that sandwich it.
The magnetic flux accompanying this is converged on these electromagnetic poles 41, 42, 43 through the rotor magnet 5. Therefore, the electromagnetic noise radiated from the stator 4 does not substantially reach the region 38, in addition to the fact that the above-mentioned generation level itself is small.

In addition to the above-mentioned structure, as shown in FIGS. 2 and 4, the electromagnetic poles 41, 42, 43 are connected to respective phases (u, v, w) of the three-phase armature coil 6 and The magnetic pole coils 4a, 4b and 4c are successively applied. Therefore, 3
It supplements the balance of energization and generated torque between each phase. Further, the number of turns of the magnetic pole coil in each phase is larger than that of the magnetic pole coil corresponding to the region 38, and the number of turns of the other magnetic pole coil in the relevant phase is larger than that in the case of performing the normal even winding, and the counter electromotive force is increased. The required torque can be obtained by maintaining the torque equal to or higher than the above. In this case, the winding ratio varies depending on the shape and size of the stator 4, the wire diameter of the coil, the space factor, etc., but the winding ratio is (the number of windings of the magnetic pole coil corresponding to the region: the number of other windings of the magnetic pole coil) = 0.4 to 0.9. It is desirable to set the ratio to: 1 and it is particularly desirable to center the ratio at 0.6: 1.

In the illustrated example, the electromagnetic poles corresponding to the area 38 have three magnetic poles, but the number of magnetic poles can be freely changed depending on the size of the stator 4 and the shape of the driving device. In that case, if the same number of magnetic poles is set for each phase (in the example shown, one magnetic pole coil is set for each phase), various electrical characteristics of the armature coil 6 such as inductance between phases and generated torque will be described. Therefore, it is possible to obtain a good rotational drive characteristic.

Next, FIGS. 3 and 5 show another embodiment of the recording disk drive device according to the present invention, and are a plan view and a connection diagram showing only the stator alone. The other parts are the same as those shown in FIG. Figure 3
Also, in FIG. 5, in this embodiment, the same stator as in the previous embodiment is composed of three-phase armature coils. The different point is that the number of electromagnetic poles is 12, and other winding directions and connection methods have the same configuration as that of the above embodiment, as shown in FIG. Also in this case, the electromagnetic poles 51, 5 are moved according to the area 38 corresponding to the recording (magnetic) head.
The number of turns of the magnetic pole coils 5a, 5b, 5c wound around 2, 53 is set smaller than that of the other magnetic pole coils.

By the way, it has a diameter of about 25.6 mm,
Regarding the stator core having a shape of 2.8 mm in thickness,
Originally, in the present embodiment, the number of turns of the magnetic pole coils 5a, 5b, and 5c is 40, and the number of turns of the other magnetic pole coils 5d to 5l is 67, in contrast to the number of turns of 58 when the magnetic poles are evenly wound. Is set. (The winding ratio is 0.
6: 1) and the measurement result of the electromagnetic noise shows that the electromagnetic noise level is reduced by about 56% in this embodiment, compared with the case where the armature coil is uniformly wound in the normal stator. At that time, the counter electromotive force (or torque constant) of the stator
Was 142 gcm / A in the present example, compared to 130 gcm / A in the usual case.

In addition to the above, the magnetic pole coils 5a, 5b,
5c, each having 28 turns, magnetic pole coils 5d, 5e, 5
The number of turns f is 60, and the magnetic pole coils 5g, 5h, 5i
66 turns each, and the magnetic pole coils 5j, 5k,
The number of windings of 5 l is set to 60. Magnetic pole coils 5g, 5
When the number of turns of h and 5i is 66, the magnetic pole coils 5d and 5i
The number of turns of e, 5f, 5j, 5k, 5l is more than 60, in addition to supplementing the energization and torque balance between the phases described in the above-described embodiment, in particular, this embodiment is point-symmetrical. It is set in order to further supplement the magnetic pole balance between the magnetic pole coils positioned in a shape.

The electromagnetic noise measurement results were also similar to the above. At that time, the counter electromotive force (or torque constant) was 142 (gcm / A) in the present example, compared to 130 (gcm / A) in the related art. In both of the above-mentioned two embodiments, the electromagnetic poles are always arranged at the same intervals, so that the above-mentioned respective balances can be easily balanced and easily supplemented.

As described above, design changes and modifications can be freely made without departing from the spirit of the present invention. That is, although the recording disk drive device of this embodiment uses the three-phase armature coil, the invention is not limited to this. Although the stator of this embodiment has been shown to have the outer rotor type rotary drive structure, it may be used for the inner rotor type. The number of electromagnetic poles of the stator and the number of magnetic poles of the rotor magnet corresponding thereto can be freely selected. Further, in the present embodiment, the magnetic pole coil has the structure of the electromagnetic pole having the stator core at all times, but the magnetic pole coil may be implemented by the air-core coil having no stator core. At that time, a so-called axial gap type drive system in which the air-core coil and the rotor magnet are arranged to face each other in the direction of the rotation axis of the rotor hub can also be adopted. In addition, it goes without saying that the number of turns of the magnetic pole coil and the number of electromagnetic poles can be freely set corresponding to the seek area of the recording head.

[0029]

According to the recording disk drive apparatus of the present invention, the stator is wound by a multi-phase armature coil, and the required number of magnetic pole coils are substantially evenly arranged in each phase. The number of turns of the magnetic pole coil corresponding to the region where the recording head seeks is set to be smaller than the number of turns of the other magnetic pole coils of the relevant phase. Therefore, it is possible to effectively suppress the influence of electromagnetic noise that acts on the recording head from the stator, so that the recording head is prevented from suffering electromagnetic interference, and information read / write errors with respect to the recording disk do not occur.
Further, in order to prevent the electromagnetic noise, the prevention means is not newly added in the conventional manner, so that no member, necessary space and man-hours associated therewith are required. In this way, it is possible to obtain a highly reliable recording disk drive device that can be downsized even when the information density and capacity are increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing a recording disk drive device according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view showing a part of the recording disk drive device shown in FIG.

FIG. 3 is a schematic plan view showing a part of a recording disk drive device according to a second embodiment of the present invention.

FIG. 4 is a connection diagram in FIG.

FIG. 5 is a connection diagram in FIG.

[Explanation of symbols]

 1 Bracket 2 Magnetic Disk 3 Rotor Hub 4 Stator 5 Rotor Magnet 6 Armature Coil 7 Magnetic Head 8 Arm 9, 10 Ball Bearing 18 Magnetic Fluid Seal 19 Flexible Board

Claims (3)

[Claims] 1. A stationary member, a rotor hub on which a recording disk is mounted, bearing means provided between the stationary member and the rotor hub, a stator mounted on the stationary member, and the stator. And a rotor magnet fixed to the rotor hub, the stator being wound with a plurality of phases of armature coils, and the armature coils having a plurality of armature coils. Pole magnetic pole coils are provided in a substantially equal arrangement, and among the magnetic pole coils, at least three magnetic pole coils corresponding to the region where the recording head seeks are set to have a smaller number of turns than other magnetic pole coils. A recording disk drive device characterized by the above. 2. A stationary member, a rotor hub on which a recording disk is mounted, bearing means provided between the stationary member and the rotor hub, a stator mounted on the stationary member, and the stator. And a rotor magnet fixed to the rotor hub, the stator being wound with a plurality of phases of armature coils, and the armature coils having a plurality of armature coils. Pole magnetic pole coils are provided in a substantially equal arrangement, and the magnetic pole coils corresponding to the areas to be sought by the recording head are filled with the same number of poles from the armature coils of each phase, respectively. Is set to have a smaller number of turns than the other magnetic pole coils in the relevant phase, respectively. 3. The winding ratio of the magnetic pole coil is such that the number of windings of the magnetic pole coil is small: the number of windings of the magnetic pole coil is large.
The recording disk drive device according to claim 1 or 2, wherein the ratio is 9: 1.