JPH0467352A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To reduce the influence of electromagnetic noise generated by means of the operation of a spindle motor on an electromagnetic device and to reduce reading/writing errors by surrounding a part facing an area to which at least the electromagnetic device moves among the total periphery of a stator by means of a rotary ferromagnetic member and a fixed ferromagnetic member. CONSTITUTION:The circular end part of the rotary ferromagnetic member 44 constituting a part of the rotary part of a spindle motor 12 and the outer peripheral end member of a plate-formed or sheet-formed fixed ferromagnetic member 52 provided for the fixed part composed of a non-ferromagnetic member in th spindle motor 12 are approximately confronted each other in the position of almost the same radius along the whole periphery of the rotary part in the spindle motor 12. Then, the outer peripheral side of the part facing the area to which the electromagnetic device is shifted in the direction of the radius and both sides of the direction of the shaft are surrounded by the rotary ferromagnetic part 44 and the fixed ferromagnetic member 52. Thus, the most part of electromagnetic noise passes through a magnetic path composed of them and the influence of electromagnetic noise on the electromagnetic device shifting the area facing the part of the magnetic path can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in magnetic recording devices such as hard disk drives.

[Prior Art and Problems to be Solved by the Invention] FIG. 5 shows a sectional view of essential parts of a hard disk device as an example of a conventional magnetic recording device.

A in FIG. 5 is a disk chamber, and FIG. 6 is a plan view of the main part inside the disk chamber a. b is a brushless spindle motor, C is a hard disk d is an electromagnetic head, e is an electromagnetic head d fixed at the tip of a hard disk C
This is a positioning device that performs positioning by moving in the direction of the arrow in FIG.

In the brushless spindle motor b, f is an aluminum stator frame, and g is a stator frame f.
h is a stator core fixed to the outer periphery of the cylindrical part g, i is a stator coil wound around the stator core h, and j is an aluminum cup-shaped rotor hub. A rotating shaft k protrudes from the center of the rotor hub j, and is inserted into the cylindrical portion g and rotatably supported via a bearing m. n
is a rotor yoke provided inside the rotor hub, and p is a rotor magnet fixed to the inside of the peripheral wall of the rotor yoke n.

When reading/writing from/to the hard disk C, the current supplied to the stator coil i is commutated according to the magnetic pole position of the rotor magnet p to create a rotating magnetic field, rotate the rotor, and drive the hard disk C to rotate. At the same time, the electromagnetic head d is operated by moving it to an appropriate position by the positioning device e.

In that case, electromagnetic noise is often generated due to current switching for each phase of the stator coil i. This electromagnetic noise extends from the stator frame f side to the electromagnetic head d and may affect reading/writing to the hard disk C. Especially when reading/writing digital signals, the electromagnetic noise is pulse-like. In some cases, this was difficult to eliminate and constituted a factor inducing reading/writing errors.

The present invention has been made in view of the above-mentioned problems existing in the prior art, and its purpose is to effectively reduce the influence of electromagnetic noise generated in a spindle motor on an electromagnetic device. An object of the present invention is to provide a magnetic recording device that can prevent read/write errors from occurring.

[Means for Solving the Problems] In order to achieve the above object, the magnetic recording device of the present invention has the following features:
A magnetic recording medium, a spindle motor that holds and rotates the magnetic recording medium on the outer circumferential side of a rotating part, an electromagnetic device that reads and/or writes magnetic information on the magnetic recording medium, and a magnetic recording device that performs magnetic recording. In a magnetic recording device comprising a positioning device for positioning on a medium, an annular end portion of a rotating ferromagnetic member constituting a part of the rotating portion of the spindle motor over the entire circumference of the rotating portion; The outer periphery of a plate-shaped or sheet-shaped fixed ferromagnetic member provided on a fixed part made of a non-magnetic material closely faces each other at approximately the same radial position, and at least the electromagnetic device The rotary ferromagnetic member and the fixed ferromagnetic member surround at least the outer circumferential side and both axial sides of the stator in a portion radially opposite to a region in which the stator moves.

[Operation] When reading and/or writing magnetic information to a magnetic recording medium, a spindle motor is driven to rotate the magnetic recording medium, and a positioning device is used to position the electromagnetic device at the required position on the magnetic recording medium. The electromagnetic device is activated one by one while moving or moving one after another.

When a spindle motor is operated, electromagnetic noise is often generated due to, for example, switching of current to each phase of the stator coil. The annular end of the rotating ferromagnetic member and the outer peripheral edge of the plate-shaped or sheet-shaped fixed ferromagnetic member provided on the fixed part made of non-magnetic material in the spindle motor are closely opposed to each other at approximately the same radial position, and the spindle Of the entire circumference of the stator in the motor, at least the outer circumferential side and both axial sides of the stator in a portion radially opposite to an area in which the electromagnetic device moves are surrounded by a rotating ferromagnetic member and a fixed ferromagnetic member. Therefore, a considerable portion of the generated electromagnetic noise passes through the magnetic path formed by the fixed ferromagnetic member and the rotating ferromagnetic member. Therefore, the influence of electromagnetic noise on the electromagnetic device moving in the area opposite to the part of the magnetic path is effectively reduced.

[Example] An example of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a sectional view of essential parts of a hard disk device as an embodiment of the magnetic recording device of the present invention. 1 in Figure 1
0 is a disk chamber, and FIG. 2 is a plan view of the main part inside the disk chamber 10.

12 is a brushless radial gap type spindle motor, 14 is a hard disk, 16 is an electromagnetic head,
Reference numeral 18 denotes a positioning device that moves and positions the electromagnetic head 16 fixed to the tip on the hard disk 14 in the direction of the arrow in FIG.

20 is a substrate of the disk chamber IO, 22 is a peripheral wall, and 24 is a lid. The substrate 20 is provided with a mounting hole 20a for mounting the spindle motor 12 thereon.

26 is a stator frame in the spindle motor 12. The stator frame 26 has an annular recess 26a
, a cylindrical portion 26b that protrudes in the axial direction from the center of the recessed portion 26a, and a bracket portion 26c that protrudes radially outward over the entire outer periphery. The stator frame 26 is mounted inside the disk chamber 10 by fixing it to the substrate 20 of the disk chamber 10 with a bracket portion 26c protruding from the periphery of the hole 20a. This stator frame 26 has particularly high machining accuracy of the bracket portion 26c (by making the substrate 26 of the disk chamber 10
It is made of aluminum so that it can be mounted with high precision.

28 is a stator core fixed to the outer periphery of the cylindrical portion 26b;
30 is a stator coil wound around the stator core 28. 32 is a lead wire of the stator coil 30, which is drawn out of the disk chamber 10 through a through hole 34 provided at the bottom of the stator frame 26, and is connected to a flexible circuit provided outside the substrate 20 of the disk chamber 10. It is connected to the board 36. Note that the through hole 34 is
It is occluded by filling material.

38 is a cup-shaped rotor hub;
A rotating shaft 40 is provided protruding in the axial direction of the central portion of the inner portion, and the rotating shaft 40 is inserted into the cylindrical portion 26b and a bearing 42 is provided.
It is rotatably supported via. Also rotor hub 3
8 has a flange portion 3 for mounting the hard disk.
8a is formed.

44 is a cup-shaped rotor yoke (rotating ferromagnetic member) made of a ferromagnetic material provided inside the rotor hub 38, and extends all around the outer circumferential side of the stator core 28 and the stator coil 30 and the upper side in the axial direction in FIG. are arranged so as to surround each other in a ring shape. 46 is a cylindrical rotor magnet fixed inside the inner circumferential wall of the rotor yoke 44. The rotor hub 38 is made of aluminum to improve machining accuracy.

Two hard disks 1 are installed on the outer periphery of the rotor hub 38.
4 is fixed concentrically with the spindle motor 12. The first hard disk 14 is placed on the upper surface of the flange portion 38a in FIG. ing.

52 is a permalloy plate (fixed ferromagnetic member) with a thickness of 0.2 mm. This permalloy plate 52 has an annular shape, and with one side facing the stator coil 30,
The other surface is bonded to the bottom surface of the recess 26a in the stator frame 26. Outer peripheral edge 5 of permalloy plate 52
2a is closely opposed to the outer circumferential end 44a (annular end) of the rotor yoke 44 in the axial direction with a slight gap in between at approximately the same radial position. As a result, the permalloy plate 52 and the rotor yoke 44 are connected to the stator core 28.
A magnetic path is formed that surrounds the outer circumferential side and both axial sides of the stator coil 30 over substantially the entire circumference thereof.

The electromagnetic head 16 reads and/or writes magnetic information on the hard disk 14;
The arm 56 of the positioning device 18 is the arm 56 of the positioning device 18
This is the rotating part. The rotating part 56 is powered by a stepping motor (
Illustrations are omitted. ), thereby moving the electromagnetic head 16 in the direction of the arrow in FIG. 2 and positioning it.

Reading and/or reading magnetic information from the hard disk 14
Alternatively, when writing, a rotating magnetic field is created by commutating the current supplied to the stator coil 30 according to the magnetic pole position of the rotor magnet 46.
is rotated to rotate the hard disk 14, and the positioning device 18 moves the electromagnetic head 16 to an appropriate position to operate the electromagnetic head 16.

In that case, pulsed electromagnetic noise is generated from the stator coil 30 due to the switching of current to each phase of the stator coil 30.

However, the outer periphery and both axial sides of the stator core 28 and stator coil 30 in the spindle motor 12 are surrounded by the permalloy plate 52 and the rotor yoke 44 over substantially the entire circumference. Since the peripheral edge portion 52a and the outer peripheral end portion 44a of the rotor yoke 44 are in a state in which they face each other closely in the axial direction with a slight gap at substantially the same radial position, a considerable portion of the generated electromagnetic noise is caused by the permalloy plate 52 and the outer peripheral end portion 44a of the rotor yoke 44. It passes through a magnetic path formed by the rotor yoke 44. Therefore, the influence of electromagnetic noise on the electromagnetic head 16 is effectively reduced.

FIG. 3 is a sectional view of essential parts of a hard disk device as another embodiment of the magnetic recording device of the present invention.

FIG. 4 is a plan view of the main parts inside the disk chamber 10.

60 is a ferromagnetic insulating sheet (164) formed on one surface of a polyimide sheet 62 which is an insulating material.
The 0 ferromagnetic coating film 64, which is a fixed ferromagnetic member, can be formed by applying and drying a paint made by dispersing ferromagnetic powder in a vehicle. This ferromagnetic insulating sheet 60 has a substantially fan shape that spreads outward, and with the polyimide sheet 62 side facing the stator coil 30,
The ferromagnetic m1l 164 side is bonded to the outer circumference of the cylindrical portion 26b and the bottom surface of the recess 26a in the stator frame 26. This ferromagnetic insulating sheet 60 covers the lower part of the stator core 28 and stator coil 30 in the axial direction, which extends to a center angle of approximately 90 degrees, and the outer peripheral edge of the ferromagnetic coating 64. The portion 64a faces the outer peripheral end portion 44a of the rotor yoke 44 in the axial direction with a gap therebetween. As a result, the ferromagnetic coating film 64 of the ferromagnetic insulating sheet 60 and the rotor yoke 44 form a magnetic path surrounding the outer circumferential side and both axial sides of the stator core 28 and the stator coil 30 in a range that spans approximately a 90-degree central angle. It consists of And stator coil 30
The insulation between the rotor hub 38 and the rotor hub 38 is provided by a polyimide sheet 62.
maintained by In addition, this ferromagnetic insulation sheet
0, it is of course possible to use, for example, a thin ferromagnetic metal plate whose one side is covered with an insulating synthetic resin film.

As shown in FIG. 4, the area in which the electromagnetic head 16 moves extends from the outer edge of the hard disk 14 to the inner periphery in the radial direction, and extends over a range of about 15 degrees in the circumferential direction. The area in which this electromagnetic head 16 moves is radially opposed to the magnetic path formed by the ferromagnetic portion 11164 of the ferromagnetic insulating sheet 60 and the rotor yoke 44, and is located approximately in the center of the central angle occupied by this magnetic path. do.

When the stator coil 30 is operated to rotate the hard disk drive 4, pulsed electromagnetic noise is generated from the stator coil 3°. The outer circumferential side and both axial sides of the stator core 28 and stator coil 30 facing each other in the direction are connected to the ferromagnetic part [1164 and the rotor yoke 4 of the ferromagnetic insulating sheet 60].
4, and its ferromagnetic coating 64
and the outer peripheral edge 44a of the rotor yoke 44.
Since the two are located close to each other in the axial direction with a slight air gap at almost the same radial position, a considerable portion of the generated electromagnetic noise is caused by the magnetic path formed by the ferromagnetic coating 64 and the rotor yoke 44. It will pass through. Therefore, the influence of electromagnetic noise on the electromagnetic head 16 is effectively reduced.

Note that in order to more effectively remove the influence of electromagnetic noise on the electromagnetic head 16, the outer circumferential edge 52a and the outer circumferential edge 64a of the permalloy plate 52 and the ferromagnetic coating 64 are made to It is particularly desirable that there is no radial outward protrusion. It goes without saying that it is preferable to make the gap distance between the permalloy plate 52 or the ferromagnetic coating 64 and the rotor yoke 44 as small as possible. Furthermore, although the spindle motor 12 in the embodiments described above is of the radial gap type, it is also possible to apply an axial gap type to the present invention.

Magnetic Noise - The spindle motor 12 in the above-mentioned hard disk drive shown in FIGS.
The operation is performed with the spacer 48 and the clamp member 50 removed, and the distance is 2 mm upward from the top surface of the flange portion 38a of the rotor hub 38 in FIG. 1, and 1. When electromagnetic noise was measured using an electromagnetic sensor at positions separated by 5 mm, the measurement results shown in FIG. 7 were obtained. The maximum value of the output voltage of the electromagnetic sensor was about 40 mV.

L crotch 11 The spindle motor in the conventional hard disk drive shown in FIGS. 5 and 6 was measured in the same manner as in the above measurement test, and the results are shown in FIG. 8. It can be seen that the level of pulsed electromagnetic noise is considerably higher than in FIG. Also, the maximum value of the output voltage of the electromagnetic sensor is approximately 52 m
A value 30% larger than the result of the above measurement test was obtained for V.

[Effects of the Invention] The magnetic recording device of the present invention effectively reduces the influence of electromagnetic noise generated by the operation of the spindle motor on the electromagnetic device when the electromagnetic device reads/writes magnetic information to a magnetic recording medium. This can prevent read/write errors from occurring.

[Brief explanation of the drawing]

1 and 2 relate to one embodiment of the present invention, in which FIG. 1 is a sectional view of a main part of a hard disk drive, and FIG. 2 is a plan view of a main part inside a disk chamber of the hard disk drive. It is. FIG. 3 is a sectional view of a main part of a hard disk device according to another embodiment, and FIG.
FIG. 3 is a plan view of a main part inside a disk chamber in the hard disk device. FIG. 5 is a sectional view of a main part of a conventional hard disk drive, and FIG. 6 is a plan view of a main part inside a disk chamber of the hard disk drive. Moreover, FIG. 7 shows the electromagnetic noise measurement test results, and FIG. 8 shows the comparative test results. In the drawing, 12 is a spindle motor, 14 is a hard disk, 16 is an electromagnetic head, 18 is a positioning device, 26 is a stator frame, 28 is a stator core, 30 is a stator coil, 38 is a rotor hub 44 is a rotor yoke, 44a
46 is a rotor magnet, 52 is a permalloy plate, 52a is an outer peripheral edge, 60 is a ferromagnetic insulating sheet, 6
4 is a ferromagnetic coating film, and 64a is an outer peripheral edge.

Claims (1)

[Claims] A magnetic recording medium, a spindle motor that holds and rotates the magnetic recording medium on the outer circumferential side of a rotating part, and an electromagnetic device that reads and/or writes magnetic information on the magnetic recording medium; In a magnetic recording device comprising a positioning device for positioning the electromagnetic device on a magnetic recording medium, an annular rotating ferromagnetic member forming a part of the rotating portion of the spindle motor extends around the entire circumference of the rotating portion of the spindle motor. The end portion and the outer peripheral edge of a fixed ferromagnetic member in the form of a plate or sheet provided on a fixed portion made of a non-magnetic material in the spindle motor closely face each other at approximately the same radial position, and the entire stator of the spindle motor At least the outer circumferential side and both axial sides of the stator in a portion of the stator that radially faces at least a region in which the electromagnetic device moves are configured to be surrounded by the rotating ferromagnetic member and the fixed ferromagnetic member. Features of magnetic recording device.