JP3201100B2 - Magneto-optical disk spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a magneto-optical disk spindle motor having a hydrodynamic bearing.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers, large-capacity and small external storage devices have become indispensable. Magneto-optical disk drives are expected to be large-capacity, low-bit-cost, random-access and disk-replaceable external storage devices, and are rapidly being developed with the aim of increasing capacity and miniaturization with the aim of personal use. Is underway. Accordingly, there has been a demand for higher precision, smaller size, and thinner disk drive spindle motors. The magneto-optical disk spindle motor includes a driving unit that generates a disk driving force, a chucking mechanism that transmits the driving force to the disk, and a bearing that holds the center of rotation. And thinning are indispensable technologies. In general, ball bearings have been used for bearings.However, small diameter and thin ball bearings have low impact resistance, which makes assembly work difficult and reduces the reliability of the magneto-optical disk drive in the operating environment. There is a problem of inhibiting portability. In addition, the magneto-optical disk drive records and
In order to enhance the reliability of reproduction, it is necessary to precisely control the laser head to a target position. However, complicated mechanical resonance in which a ball bearing easily occurs makes it difficult to perform high-precision position control.

[0003] As a solution to the above-mentioned problem, a hydrodynamic bearing is attracting attention. A hydrodynamic bearing is, if a radial bearing is described, composed of a cylindrical shaft and a hollow cylindrical sleeve metal fitted with an appropriate gap between the shaft and a herringbone groove or the like. A bearing having a structure in which the gap is filled with a fluid (generally oil) and the rotor is supported by pressure generated in the fluid as the shaft or sleeve metal rotates. Hydrodynamic bearings have excellent shock resistance because they support the rotor through a fluid, and there is no mechanical contact or sliding, resulting in extremely low rotational noise. In principle, it is suitable for solving the above-mentioned problems, for example, the mechanical resonance generated in the bearing portion can be suppressed. On the other hand, a magneto-optical disk device is a device that frequently exchanges a disk, and a magnet clamping system using magnetic attraction is used as a disk chucking method as a standard for a 3.5-inch size magneto-optical disk device. And
It is also a typical method in a magneto-optical disk device of 5.25 inch size. Therefore, when the disk is taken out, an external force (510 gf or more for 3.5 inch size and 1 kgf or more for 5.25 inch size) acts in the thrust direction of the bearing to remove the disk from the chucking mechanism. The radial hydrodynamic bearing does not have the ability to support the load in the thrust direction and the ability to maintain the position in the thrust direction, and it is necessary to provide a dedicated bearing and a stopper for the rotor.

As a hydrodynamic thrust bearing for solving the above-mentioned problems, a two-face opposed structure has been conventionally proposed. FIGS. 4 (a) and 4 (b) are examples of such a case.
32,428. The thrust bearing force is generated in the opposite directions on two different surfaces by the same operation as that of the radial bearing, so that the relative positions of the shaft and the sleeve do not change over the gaps δ1 and δ2 in the drawing. However, this structure is complicated and expensive because there are two thrust-facing surfaces that require high precision, is not suitable for thinning because the occupied height of the thrust bearing mechanism increases, and the loss torque increases and the current consumption increases. There was a problem of increasing. As a hydrodynamic thrust bearing that solves the problem of the two-surface opposing structure, a structure in which a retaining member is added to a hydrodynamic thrust bearing having a single-surface opposing structure has been proposed. 5 (a) and 5 (b) show an example thereof, which are disclosed in JP-A-59-110917 and JP-A-63-1671 respectively.
This is a quote from No. 15. Briefly describing these proposals, the thrust-facing surface is a single surface, and a ring or a pin fixed to the sleeve is engaged with a groove provided on the shaft to prevent the thrust from coming off. According to this configuration, the loss torque is small and the rotor can be prevented from coming off at a lower cost than in the two-face opposing structure.

[0005]

However, the conventional structure described above does not solve the problem that the height in the thrust direction is increased by the retaining portion, which is not suitable for thinning. Further, since the magneto-optical disk device is a device that frequently exchanges disks, the retaining ring or the retaining pin frequently contacts the groove provided on the shaft, and fine wear powder enters the fluid bearing. There is a new problem that reliability is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magneto-optical disk spindle motor having a hydrodynamic bearing suitable for high precision, miniaturization and thinning.

[0007]

In order to achieve this object, the present invention provides, in a first aspect, a method for providing a stopper outside a rotor. A concave portion provided in the inner peripheral direction by utilizing a portion which does not interfere with other mechanical members on the outer peripheral surface of the rotor, and a space in which the concave portion is opposed to the concave portion in the axial direction and the laser head of the magneto-optical disk device is in proximity. It is constituted by a locking member arranged so as to avoid. The second means provides a method of providing a stopper inside the rotor of the motor having the circumferentially opposed core. It is constituted by a locking member fixed to the stator by utilizing the space between the winding portions of the stator core, in close proximity to the end surface in the thrust direction of the field magnet.

[0008]

According to this structure, high precision is required for both the first and second means, and the retaining mechanism is not provided in the other mechanism, but in the bearing mechanism where a small amount of foreign matter causes a decrease in reliability. Eliminates the effect on reliability. Also, the first
Means is provided with a concave portion in the inner circumferential direction by utilizing a portion which does not interfere with other mechanical members on the outer peripheral side surface of the rotor, and is arranged outside the rotor and engaged with a locking member fixed to the stator. Accordingly, the second means is a locking member fixed to the stator using a thrust end surface of the field magnet of the motor with the circumferentially opposed core and the space between the winding portions of the core. By engaging and contacting with each other, the retaining mechanism can be configured without increasing the occupying height in the thrust direction.

[0009]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1A provides an embodiment in which a stopper is provided outside the rotor according to the first aspect of the present invention. FIG.
In FIG. 1A, 101 is a magneto-optical disk, 202 is a shaft that is engaged with the magneto-optical disk 101 while positioning the center of rotation, and rotates at a predetermined rotation speed integrally with the magneto-optical disk 101; Numeral 203 denotes a disk support for mounting the magneto-optical disk 101 on its upper end surface and positioning the magneto-optical disk 101 in the height direction. Numeral 204 denotes an attraction plate 102 formed of a soft magnetic material at the center of the magneto-optical disk 101.
And a chucking magnet for fixing the magneto-optical disk 101 to the disk support 203.
05 is a field magnet, 206 is the field magnet 2
A magnetic path yoke for forming the magnetic path No. 05. The shaft 202 is mounted at the center of the magnetic path yoke 206, the field magnet 205 is mounted at the inner periphery, and the disk support 203 and the chucking magnet 204 are pressed, bonded and caulked at the top. Etc. fixed,
The rotor 201 is constituted as a whole. 302 is a stator core, 303 and 304 are drive coils, 305 is a circuit board on which elements such as an IC for driving a motor or a printed pattern are mounted, and the circuit board 305 and the stator core 302 are bonded, press-fitted or screwed. The stator 3 is fixed to the housing 306 as a whole.
01. The rotor 201 is radially supported by a sleeve metal 104, and a thrust plate 501 is provided.
Is supported in the thrust direction. The shaft 202
A lubricating fluid (not shown), for example, oil is filled between the shaft and the sleeve metal 401 and between the shaft and the thrust plate 501, respectively. The shaft 20
2, a herringbone groove 202a is formed, and a pressure is generated in the lubricating fluid by the rotation of the shaft 202 to constitute a hydrodynamic bearing mechanism. Also, the shaft end face 2
02b and the thrust plate 501 constitute a thrust bearing mechanism while preventing wear with a lubricating fluid filled therebetween.

A structure for preventing the magneto-optical disk spindle motor configured as described above from coming off will be described below.

In FIG. 1A, a concave portion (dent) 20 is formed on the outer peripheral side surface of the disk support portion 203 on the boundary surface with the magnetic path yoke 206 over the entire circumference in the rotational direction.
3a is provided. On the other hand, on the stator 301, the locking member 6
Numeral 01 is fixed at a position avoiding the space where the laser head of the magneto-optical disk drive seeks (in the present embodiment, the position opposite to the space where the laser head of the magneto-optical disk drive seeks). Limits the amount of directional movement.

As described above, according to this embodiment, since the concave portion is provided in the inner circumferential direction by using the portion which does not interfere with the other mechanical members of the rotor, the magneto-optical device can be provided without increasing the dimension in the height direction. A stopper can be provided outside the rotor without hindering the seek operation of the laser head of the disk device. In the present embodiment, the rotor 201 and the stator 301 have the core-faced circumferential facing structure. However, the coreless flat face-facing structure does not impair the effects of the present invention.

(Embodiment 2) Next, the rotor 20 of the first embodiment will be described.
A description will be given of a second embodiment in which a retainer is provided outside of the first embodiment. In FIG. 2, 101 is a magneto-optical disk, 202
Is a shaft that engages while positioning the center of rotation of the magneto-optical disk 101, and rotates at a predetermined number of revolutions integrally with the magneto-optical disk 101, and 203 has the magneto-optical disk 101 on its upper end surface. A disk support portion 204 for mounting and positioning in the height direction is provided at a central portion of the magneto-optical disk 101 with an attraction plate 1 made of a soft magnetic material.
A chucking magnet for magnetically attracting the magnetic disk 02 and fixing the magneto-optical disk 101 to the disk support 203, a field magnet 205, and a magnetic path yoke 206 for forming a magnetic path of the field magnet 205. The shaft 202 is placed at the center of the magnetic path yoke 206, the field magnet 205 is placed at the inner periphery, and the disk support 203 and the chucking magnet 204 are placed at the top surface by press-fitting, bonding, and caulking. And the like to form the rotor 201 as a whole. 302
Is a stator core, 303 and 304 are drive coils, 3
Reference numeral 05 denotes a circuit board on which elements such as an IC for driving a motor or a printed pattern are mounted. The circuit board 305 and the stator core 302 are fixed to a housing 306 by bonding, press fitting, screwing, or the like. Make up. The rotor 201 is supported in a radial direction by a sleeve metal 401 and is supported in a thrust direction by a thrust plate 501. A space between the shaft 202 and the sleeve metal 401 and a space between the shaft and the thrust plate 501 are filled with a lubricating fluid (not shown), for example, oil. A herringbone groove 202a is formed in the shaft 202, and a pressure is generated in the lubricating fluid by the rotation of the shaft 202 to constitute a hydrodynamic bearing mechanism. Further, the shaft end face 202b and the thrust plate 501 constitute a thrust bearing mechanism while preventing wear by a lubricating fluid filled therebetween. At a position on the stator 301 that avoids the space where the laser head of the magneto-optical disk device seeks (in this embodiment, the position opposite to the space where the laser head of the magneto-optical disk device seeks), the locking member 601 is provided. Fixed. The above is the same as the configuration in FIG. The difference from the configuration of FIG.
A continuous recess (dent) 20 is formed on the outer peripheral side surface of the boundary surface with the disk support portion 203 over the entire circumference in the rotation direction.
3a is provided so as to be closely opposed to the locking member 601 in the axial direction to limit the axial movement amount of the rotor 201.

As described above, according to the present embodiment, since the concave portion is provided in the inner circumferential direction by using the portion which does not interfere with the other mechanical members of the rotor, the light is not increased without increasing the dimension in the height direction. A stopper can be provided outside the rotor without hindering the seek operation of the laser head of the magnetic disk drive. The concave portion on the outer peripheral surface of the rotor 201 is formed by combining the first embodiment and the second embodiment, and
3 does not impair the effects of the present invention.

Next, an embodiment of a method for providing a retainer inside the rotor 201 of the present invention will be described with reference to the drawings.

(Embodiment 3) FIG. 1B is a side sectional view of a main part of this embodiment, and FIG. 1C is a plan sectional view of a main part. 1B and 1C, reference numeral 101 denotes a magneto-optical disk, and 202 denotes a predetermined position integrally with the magneto-optical disk 101 while positioning and engaging the center of rotation of the magneto-optical disk 101. A shaft 203 that rotates at the number of rotations of the disk; a disk support portion 203 for mounting the magneto-optical disk 101 on the upper end surface thereof and positioning the magneto-optical disk 101 in the height direction;
Numeral 04 denotes a chucking magnet for magnetically adsorbing an attraction plate 102 made of a soft magnetic material at the center of the magneto-optical disk 101, and fixing the magneto-optical disk 101 to the disk support 203. The magnetized hollow cylindrical field magnet, 206 is the field magnet 2
This is a substantially cup-shaped magnetic path yoke that forms the magnetic path No. 05.
The shaft 202 is provided at the center of the magnetic path yoke 206.
However, the field magnet 205 is fixed to the inner peripheral portion, and the disk support portion 203 and the chucking magnet 204 are fixed to the top surface portion by press-fitting, bonding, caulking, and the like. I have.
302 is a stator core, 303 is a drive coil, 305 is a circuit board on which elements such as an IC for driving a motor or a printed pattern are mounted, and the circuit board 305 and the stator core 302 are bonded to, pressed into, or screwed into a housing 306. And the stator 3 as a whole
01. The rotor 201 is radially supported by a sleeve metal 401, and a thrust plate 501 is provided.
Is supported in the thrust direction. The shaft 202
A lubricating fluid (not shown), for example, an oil is filled between the shaft metal and the sleeve metal 401 and between the shaft and the thrust plate 501. The shaft 20
2, a herringbone groove 202a is formed, and a pressure is generated in the lubricating fluid by the rotation of the shaft 202 to constitute a hydrodynamic bearing mechanism. Also, the shaft end face 2
02b and the thrust plate 501 constitute a thrust bearing mechanism while preventing wear with a lubricating fluid filled therebetween.

A structure for preventing the magneto-optical disk spindle motor configured as described above from coming off will be described below.

In FIG. 1C, the stator core 3
02 denotes a plurality of winding portions 3 around which the driving coil 304 is wound.
02a, 302b, etc., and a locking member 601 is provided between the winding portion 302a and another winding portion 302b as shown in FIG. And is fixed to the stator 301 so as to face the thrust direction end surface 205a facing in the axial direction.

With the above arrangement, when the magneto-optical disk 101 adsorbed and fixed to the disk support portion 203 by the chucking magnet 204 is taken out, the locking member 601 is in contact with the thrust end face 205a of the field magnet 205 in the thrust direction. The contact limits the axial movement of the rotor.

As described above, according to the present embodiment, since the locking member is provided by utilizing the space between the winding portions of the stator core, the light is not increased without increasing the dimension in the height direction. A stopper can be provided inside the rotor 201 without hindering the seek operation of the laser head of the magnetic disk drive.

(Embodiment 4) Next, a rotor 20 according to a fourth embodiment will be described.
Another embodiment in which a retainer is provided inside 1 will be described. 3 differs from the configuration of FIG. 1B in that the locking member 601 is formed so as to be movable in the radial direction when the rotor 201 is inserted and assembled in the axial direction.

As described above, according to this embodiment, it is possible to provide a stopper inside the rotor 201 without increasing the dimension in the height direction and without hindering the seek operation of the laser head of the magneto-optical disk drive. it can.

[0024]

As described above, according to the present invention, the means for providing the retaining member on the outside of the first rotor utilizes the portion which does not interfere with the other mechanical members on the outer peripheral side of the first rotor to move in the inner peripheral direction. It is constituted by a provided concave portion and an engaging member which is closely opposed to the concave portion in the axial direction and is arranged so as to avoid a space where the magneto-optical disk laser head seeks. In the means for providing a retainer inside the rotor of the second circumferentially opposed cored motor, the space between the winding portions of the stator core is utilized by closely opposing the thrust end surface of the field magnet. And a locking member fixed to the stator. High accuracy is required for both the first and second means, and the influence on reliability by configuring a retaining mechanism in other mechanism parts, not the bearing mechanism part where slight inclusion of foreign matter causes a decrease in reliability, will be discussed. Can be eliminated. Further, the retaining mechanism can be configured without increasing the occupying height in the thrust direction. further,
In both the first and second means, since there is no convex portion on the outer peripheral side surface of the rotor, the outer diameter of the driving force generator can be occupied up to the limit near the space where the magneto-optical disk laser head approaches, so that the rotational torque generating efficiency is improved. it can. Similarly, the outer diameter of the magneto-optical disk mounting surface of the disk support can be occupied up to the limit near the space where the magneto-optical disk laser head comes close, so that the friction torque at the time of magnetic attraction of the magneto-optical disk can be increased, thereby causing slip. Does not occur.

As described above, since the rotor is supported via the fluid, the rotor has excellent impact resistance, and since there is no mechanical contact or sliding, the rotation noise is extremely small. An excellent magneto-optical disk spindle motor employing a hydrodynamic bearing having excellent characteristics such as small runout and suppression of mechanical resonance generated in a bearing portion can be realized by solving the problem.

[Brief description of the drawings]

FIG. 1A is a side sectional view of a main part of a magneto-optical disk spindle motor according to a first embodiment of the present invention. FIG. 1B is a side cross-sectional view of a main part of a magneto-optical disk spindle motor according to a third embodiment of the present invention. (C) Plane sectional view of a main part of a magneto-optical disk spindle motor according to a third embodiment of the present invention.

FIG. 2 is a side sectional view of a main part of a magneto-optical disk spindle motor according to a second embodiment of the present invention;

FIG. 3 is a side sectional view of a main part of a magneto-optical disk spindle motor according to a fourth embodiment of the present invention.

FIG. 4 (a) is a cross-sectional side view of an example of a conventional hydrodynamic thrust bearing having a two-surface opposed structure.

FIG. 5 (a) is a sectional side view of an essential part of an example of a structure in which a retaining member is added to a conventional hydrodynamic thrust bearing having a single-face opposed structure; and (b) a conventional hydrodynamic thrust bearing having a single-face opposed structure. Side cross-sectional view of main part of another example of structure with added stopper

[Explanation of symbols]

 101 Magneto-optical disk 102 Attraction plate 201 Rotor 202 Shaft 202a Herringbone groove 202b Shaft end face 203 Disk support 203a Depression 204 Chucking magnet 205 Field magnet 205a Thrust end face 206 Magnetic path yoke 206a Depression 301 Stator 302 Stator core 302a, 302b winding Mounting part 303, 304 Drive coil 305 Circuit board 306 Housing 401 Sleeve metal 501 Thrust plate 601 Locking member

Claims (2)

(57) [Claims] 1. A magnetically attracted magnetic disk between a shaft and a magneto-optical disk.
Chucking magnet to be placed and disk support
And a multi-pole magnetized hollow cylindrical field magnet and
And a rotor comprising a substantially cup-shaped magnetic path yoke;
Hydrodynamic bearing for radially supporting the rotor
Thrust bearing that supports the rotor on one side in the thrust direction.
The drive coil is disposed so as to face the field magnet.
A stator having a stator core comprising a plurality of wound portions
Magneto-optical disk spindle motor consisting of data
Between the drive coil winding portion of the stator core and the winding portion.
A locking member disposed on the stator is fixed to the stator,
Thrust direction facing the magnetic path yoke of the field magnet
To limit the axial movement of the rotor.
A magneto-optical disk spindle motor. 2. An assembling member, wherein a rotor is inserted and assembled in an axial direction.
2. The method according to claim 1, wherein the movable member is formed so as to be movable in a radial direction.
The magneto-optical disk spindle motor as described in the above.