JPH0837766A - Spindle motor for disk drive - Google Patents

Abstract

PURPOSE:To mount and attach a disk stably while the thin shape of a motor is being maintained by a method wherein a thin plate composed of a ferromagnetic substance is interposed between a freely rotatable turntable supported by a shaft and a main magnet facing via a gap in the axial direction, with a coil installed on one side of the turntable. CONSTITUTION:A turntable 8 is constituted in such a way that it is fixed to the upper part of a shaft 1 which is extended to the axial direction and that it can be turned together with the shaft 1. A main magnet 7 is arranged at a coil 6 via a gap in the axial direction, and the main magnet 7 is held by the turntable 8 while a thin plate 11 composed of a ferromagnetic substance is interposed. By means of the ferromagnetic thin plate 11 interposed between the turntable 8 and the main magnet 7, a proper magnetic field is formed in a disk-hub housing part 12, and a disk 20 can be mounted on, and attached to, the turntable stably while a thin shape is being maintained by an attraction force between the thin plate and a disk hub 21 composed of a magnetic substance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive device, for example, a disk drive spindle motor in a magneto-optical disk drive device or the like.

[0002]

2. Description of the Related Art A conventional disk drive device, for example, a disk drive spindle motor in a magneto-optical disk drive device has been shown in FIG. In FIG. 2, reference numeral 1 is an axis, and this axis 1 has an axial direction of 2
The bearings 2 and 3 are fitted into each other, and the housing 4 is fixed to the outer circumferences of the bearings 2 and 3. A stator substrate 5 such as a flexible printed substrate is arranged above the housing 4, and a plurality of coils 6 formed by winding a winding into an air core type are arranged on the stator substrate 5. There is.

A main magnet 7 is arranged in the coil 6 with a gap in the axial direction.
Are held on the turntable 8. The turntable 8 is made of a hard non-magnetic material such as stainless steel, and has a recess or the like for accommodating the disk hub 21 formed therein by, for example, cutting. The turntable 8 is fixed above the shaft 1 extending in the axial direction and is rotatable with the shaft 1. A chuck magnet 9 for attracting and fixing the mounted disk is provided inside the turntable 8. A neodymium plastic magnet was used as the chuck magnet 9.

When the disk 20 is inserted into, for example, a magneto-optical disk driving device equipped with the disk driving spindle motor having the above-mentioned structure, the disk hub 21 is made of a magnetic material and is provided at the center of the disk 20. By the attractive force acting between the chuck magnet 9 and
The disc 20 is mounted on the turntable 8.

3 and 4 show another example of the conventional disk drive motor. In the conventional example shown in FIG. 3, the main magnet 7 also has the function of the chuck magnet 9 shown in FIG. That is, the difference between FIG. 3 and FIG.
The thick portion A of the turntable 8 is formed thin to improve the passage of the magnetic flux of the main magnet 7, and the magnetic field is formed in the disk hub housing portion by the leakage magnetic flux that penetrates the thick portion in the axial direction. . With the above configuration, the leakage magnetic flux of the main magnet 7 acts as an attraction force for mounting the disc, and the chuck magnet 9 used in FIG. 2 becomes unnecessary.

In the conventional example shown in FIG. 4, the rotor case 10 is fixed above the shaft and is rotatable with the shaft.
The main magnet 7 is held in the rotor case 10. In addition, a plurality of holes are formed in the portion of the rotor case 10 where the main magnet 7 is held, over the entire circumference. A ring-shaped turntable 8 is provided above the rotor case 10 so as to abut. Even with the above configuration, the magnetic flux of the main magnet 7 can be improved.

[0007]

However, in the structure shown in FIG. 2, the chuck magnet 9 and the main magnet 7 are arranged in the thickness direction of the apparatus. Therefore, it is necessary to secure a space in the thickness direction in advance. The motor must be thicker,
As a result, there is a problem that the entire device becomes thicker.

Therefore, there is a motor having a structure as shown in FIG. 3 to reduce the thickness of the motor. However, with such a structure, an excessive suction force acts on the disk, which rather hinders the mounting of the disk. Will come.

Therefore, there is a structure as shown in FIG. 4 in which the motor is made thin and the mounting of the disk is stabilized, but it is necessary to provide a hole in the thinly formed thick portion, and The rigidity deteriorated remarkably, causing a problem in impact resistance. Further, in FIG. 5, the magnetic flux distribution is uneven in the portion having the hole and the portion having no hole over the circumference of the rotor case, which adversely affects the motor characteristics. Further, when the main magnet 7 is attached to the rotor case 10, it is necessary to adjust the positions of the rotor case 10 and the main magnet 7, and the number of holes, the formation position, etc. are also restricted, and in terms of productivity and disk mounting. There was a problem.

Therefore, the present invention is intended to solve the above-mentioned problems and to provide a stable disk drive spindle motor with a simple structure while maintaining a thin motor.

[0011]

DISCLOSURE OF THE INVENTION A disk drive spindle motor according to the present invention includes a shaft, a rotatable turntable supported by the shaft, and an axial gap in a coil provided on one side of the turntable. And a main magnet facing through the main magnet, and a thin plate made of a ferromagnetic material is interposed between the turntable and the main magnet. Further, the thickness of the thin plate may be 1/5 to 1/20 of the thickness of the main magnet.

[0012]

[Function] By interposing a thin plate made of a ferromagnetic material between the turntable and the main magnet, the leakage flux of the main magnet that axially cuts the thick portion of the turntable can be adjusted. A magnetic field of appropriate strength is formed in the hub housing. Also,
The thickness of the thin plate is 1/5 to 1/2 of the thickness of the main magnet
When set to 0, a desired magnetic field for attracting the disk hub is formed in the disk storage portion of the turntable, and stable disk mounting is achieved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of the essential parts of a disk drive spindle motor in a magneto-optical disk drive apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a shaft, and two bearings 2 and 3 are fitted to the shaft 1 in the axial direction, and a housing 4 is fixed to the outer circumferences of the bearings 2 and 3. . A stator substrate 5 such as a flexible printed substrate is arranged above the housing 4, and a plurality of coils 6 formed by winding a winding in an air-core type are arranged on the stator substrate 5.

A main magnet 7 is arranged in the coil 6 with a gap in the axial direction.
Is held on the turntable 8 with a thin plate 11 made of a ferromagnetic material interposed. A ferromagnetic material such as iron, nickel, or cobalt is used for the thin plate 11, and a neodymium-based sintered material is used for the main magnet 7. The turntable 8 is made of a hard non-magnetic material such as stainless steel, and the disc hub housing portion 12 and the like are formed by cutting or the like. The turntable 8 is fixed above the shaft 1 extending in the axial direction and is rotatable with the shaft 1.

Here, the thickness of the thin plate 11 will be described. If the thin plate 11 is made too thick, the magnetic flux of the main magnet 7 will be saturated in the thin plate 11. In this case, a leakage magnetic flux that penetrates the thick portion of the turntable 8 in the axial direction does not occur, and a magnetic field is not formed in the disc hub housing portion 12. Moreover, the motor itself becomes thick. On the contrary, if the thickness of the thin plate 11 is too thin, a strong magnetic field is formed in the disk hub housing portion 12, the adjusting function by the ferromagnetic material is not utilized, and the disk mounting is hindered. Therefore, the thickness of the thin plate 11 may be set to 1/5 to 1/20 of the thickness of the main magnet 7 in consideration of the amount of leakage magnetic flux for stably mounting the disk. Ideally, about 1/10 of the thickness of the main magnet is desirable.

With the above construction, the magnetic flux of the main magnet 7 can be adjusted with a simple structure to form a magnetic field of appropriate strength in the disk hub housing 12.

When the disk 20 is inserted into the magneto-optical disk drive equipped with such a spindle motor, the ferromagnetic thin plate 11 interposed between the turntable 8 and the main magnet 7 A magnetic field having an appropriate strength is formed in the disc hub housing portion 12, and the disc 2 is formed by a suction force acting between the disc hub housing portion 12 and the disc hub 21 formed of a magnetic material and provided in the central portion of the disc 20.
0 will be stably mounted on the turntable 8.

In this embodiment, the shaft rotary type motor in which the shaft and the turntable are both rotatable is described in detail, but the present invention is not limited to this, and the turntable is fixed, for example. A shaft-fixed motor, which is configured to be rotatable only, may be used. Further, in this embodiment, the disk drive spindle motor of the magneto-optical disk drive device is described in detail, but the present invention is not limited to this, and can be applied to disk drive spindle motors of all disk drive devices.

[0020]

As described above, according to the present invention, the thin plate made of a ferromagnetic material is interposed between the turntable and the main magnet, so that the turntable has a proper strength in the disk hub housing portion. Since the magnetic field can be formed, the disk can be stably mounted with an extremely simple configuration while maintaining the thinness.

[0021]

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a disk drive spindle motor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a conventional disk driving spindle motor.

FIG. 3 is a sectional view of a main part of another conventional disk driving spindle motor.

FIG. 4 is a sectional view of a main part of another conventional disk driving spindle motor.

[Explanation of symbols]

 1 ... Shaft 2, 3 ... Bearing 4 ... Housing 5 ... Stator board 6 ... Coil 7 ... Main magnet 8 ... Turntable 9 ... Chuck magnet 10 ... Rotor case 11 ... Thin plate 20 ... Disc 21 ... Disc hub

Claims (2)

[Claims] 1. A shaft, a rotatable turntable supported by the shaft, and a main magnet which is provided on one side of the turntable and faces a coil through an axial gap. A spindle motor for driving a disk, wherein a thin plate made of a ferromagnetic material is interposed between a turntable and the main magnet. 2. The disk drive spindle motor according to claim 1, wherein the thickness of the thin plate is 1/5 to 1/20 of the thickness of the main magnet.