JPH11285201A - Subminiature dynamic pressure bearing spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose the constitution of a subminiature dynamic pressure bearing spindle motor capable of eliminating conventional weak points, realize low power consumption with a simple construction and shows superior cost- performance. SOLUTION: An annular permanent magnet 105 which is magnetized in the thicknesswise direction is attached to the outer circumference of the center part in the axial direction of a sleeve 102 retained with a rotary shaft 101 of a rotor 100, on which herringbone grooves are formed. A pair of disc-shaped upper and lower yokes 103 and 104 have cylindrical upper and lower yokes 103a and 104a respectively in their axial directions so as to be fitted to the sleeve 102. A 1st coil group 107 and a 2nd coil group 108, which are a plurality of armature drive coil groups are provided in a space defined by the annular permanent magnet 105 and the disc-shaped upper and lower yokes 103 and 104 for keeping the axial direction of the sleeve 102 magnetically, so that a thrust bearing can be dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor using a dynamic pressure bearing, and more particularly to a structure of a dynamic pressure bearing spindle motor which can be miniaturized.

[0002]

2. Description of the Related Art In recent information processing terminal devices, the storage devices and HDDs, recording / reproducing devices and DVDs have been increased in speed and performance with the dramatic increase in storage capacity required for video processing and the like. , Laser printer,
There is a need for a spindle motor capable of high-speed rotation and high accuracy at the same time for image scanners. For example, in HDD, 10,000 rpm or more, NRRO (Non Repeatab)
le Run Out) is required to be about 0.05 μm. On the other hand, in a ball bearing bearing used in a conventional spindle motor, 7,000 rpm
m is difficult to use, and at present, the aforementioned targets cannot be achieved in terms of vibration, noise, durability, and rotational accuracy. As a result, a dynamic pressure bearing having a so-called helical groove or herringbone groove formed on either the rotating shaft or the sleeve has been used in place of the ball bearing bearing. Further, a spindle motor using the above-described dynamic bearing is required to be further reduced in size, higher in performance, and energy saving.

[0003] The structure of a hydrodynamic bearing in which a so-called helical groove or herringbone groove is formed in either a rotating shaft or a sleeve is known. Conventionally, various types of spindle motors using dynamic pressure bearings have been proposed according to their applications. In the following, some of the conventional examples will be examined from the viewpoint of miniaturization and high performance. FIG.
FIG. 1 is a schematic diagram of a spindle motor using a dynamic pressure bearing corresponding to FIG. 1 of Japanese Patent Application Publication No. 0816 (hereinafter referred to as Document A). FIG.
FIG. 1 of JP-A-8-16381 (hereinafter referred to as Document B)
FIG. 2 is a schematic view of a spindle motor using a dynamic pressure bearing corresponding to FIG. FIG. 10 is a schematic view of a spindle motor using a dynamic pressure bearing corresponding to FIG. 1 of Japanese Patent Application Laid-Open No. 4-69404 (hereinafter referred to as Document C).

According to FIG. 8, a helical groove 223 is provided.
A, 223B and a herringbone groove 223C are formed, and a shaft 223 to which a table 225 on which a disk 228 is mounted and a motor rotor 226 are fixed is fixed to a frame 221 and is engaged with a sleeve 221A. Although there is no direct explanation in Document A, the motor rotor 22
Reference numeral 6 denotes a disk-shaped permanent magnet which is magnetized to a plurality of poles in the thickness direction, and the rotor stator 227 is formed by winding a magnet wire on an iron substrate 250 (the reference numeral entered by the inventor of the present application for the sake of explanation). Thus, the coil is formed. The shaft 223 has a thrust member 222 on which a thrust bearing surface 223D is held. The spindle motor disclosed in Document A includes a dynamic pressure bearing, a rotor stator 227 having an iron substrate 250, and a thrust member 222 of a shaft 223.

According to FIG. 9, a sleeve 306 having a herringbone groove formed on the inner periphery thereof is mounted on a through hole 307 of a shaft 305 fitted at the center of a bracket 303 holding a stator 304, and the sleeve 306 is compressed. Diameter 306
A polygon mirror 314 is fitted to a. Sleeve 306
A push lot 311 is fitted above the through hole 307, and a thrust plate (not shown) is disposed on the push lot 311 and the shaft 305. The rotor 308 on which the rotor magnet 310 is mounted is fixed to the sleeve 306 and magnetically engages with the stator 304 via a gap. The spindle motor disclosed in Document B is
The iron core stator 304 and the push lot 311 as a thrust receiver are separated from the shaft 305 in the axial direction.

Referring to FIG. 10, a herringbone groove 412 is provided.
Shaft 40 with spiral and shallow groove 413 machined
1 includes a yoke 40 to which a driving magnet 408 is attached.
9 is fixed via a flange 406, and a rotating polygon mirror 407 is further mounted. The rotating shaft 401 is a sleeve 4
02, and the thrust receiver is supported by a piezoelectric element 417 or a holding rod (not shown in FIG. 5 of Document C) on a fixed plate 419 mounted on the outer cylinder 405 when stopped. With the rotation of the rotating shaft 401, the holding rod is lowered by opening and closing the electromagnet and the like, and the thrust of the rotating shaft 401 is supported by the thrust plate 416 on which the dynamic pressure bearing 418 is formed.
The spindle motor disclosed in Document C has a cored stator 410, and a thrust receiver is formed by a thrust plate 416 on which a dynamic pressure bearing 418 is formed. It is configured to be supported by another holding rod.

[0007]

The spindle motors using the dynamic pressure bearings disclosed in the above-mentioned documents have the following problems. First, in Document A, (1)
When the shaft 223 is received on the thrust bearing surface 223D, and the motor stator 227 has a strong suction force from the motor rotor 226 due to the iron substrate 250, an excessive thrust load is generated, and the stopping friction increases, and the environmental temperature is low. If it is difficult to start from the stop state and try to achieve it, power consumption increases and low power consumption cannot be achieved. (2)
Since the motor stator 227 is the iron substrate 250, when the motor rotor 226 is rotated at a high speed, the iron loss increases and the energy conversion efficiency of the electric machine cannot be increased. (3) Since the thrust dynamic pressure bearing is provided in addition to the journal dynamic pressure bearing, the structure is complicated and it is difficult to reduce the size.

In Document B, it is described that the shaft 305 is fixed and the sleeve 306 rotates, so that the structure can be downsized. (1) The thrust is received by a separate push lot 311. However, the structure is complicated and miniaturization is difficult. (2) Due to the rotation angle dependency of the magnetic energy with the rotor magnet 310 due to the salient pole core stator 304, a so-called detent torque is generated to cause torque ripple, which causes vibration and noise, and makes it difficult to obtain rotation accuracy. In particular, when an anisotropic high energy product magnet is used to achieve low power consumption, the detent torque and the torque ripple increase. (4) Iron loss occurs and high conversion efficiency cannot be obtained.

In Document C, (1) the so-called detent torque is generated due to the rotation angle dependency of the magnetic energy with the driving magnet 408 for the salient-pole iron core stator 410, torque ripple is generated, and vibration and noise are reduced. This is the cause and it is difficult to obtain rotation accuracy. In particular, when an anisotropic high energy product magnet is used to achieve low power consumption, the detent torque and the torque ripple increase. (2) Iron loss occurs and high conversion efficiency cannot be obtained. (3) Rotating shaft 4 when stopped
In order to receive the thrust of 01, a special piezoelectric body 417 or a holding rod is required, so that the structure is complicated and the size cannot be reduced.
SUMMARY OF THE INVENTION An object of the present invention, which has been achieved in view of the above, is to eliminate the above-mentioned disadvantages of the conventional example, to achieve an ultra-compact hydrodynamic bearing with a simple structure, low power consumption, and excellent cost / performance. This proposes a configuration of a spindle motor.

[0010]

According to a first aspect of the present invention, there is provided an ultra-small hydrodynamic bearing spindle motor comprising: a rotating shaft fixed to a housing;
A sleeve rotatably engaged with the rotating shaft via a space filled with a lubricant, and a dynamic pressure having a herringbone groove formed on either an outer peripheral portion of the rotating shaft or an inner peripheral portion of the sleeve. A spindle motor having a bearing and arranged so that a permanent magnet rotor held by the sleeve is magnetically engaged with a plurality of armature drive coils fixed to the housing, the spindle motor being made of a magnetic material. A ring magnetized in the thickness direction on the outer periphery of the axial center part of a sleeve made of a cylindrical non-magnetic material rotatably engaged with the large diameter part, the large diameter part being provided at both ends of the rotating shaft. And a disk-shaped yoke made of a pair of magnetic materials having a cylindrical yoke in the axial direction so as to be fitted with the sleeve is provided on the upper and lower surfaces of the permanent magnet. Between a pair of disc-shaped yokes A plurality of groups of armature drive coils are arranged in substantially parallel to the formed gap and fixed to the housing, so that the magnetic flux of the ring-shaped permanent magnet forms a gap formed between the pair of disc-shaped yokes. And a magnetic circuit formed between the pair of cylindrical yokes and the rotating shaft. The sleeve is magnetically held in the axial direction.

According to a second aspect of the present invention, there is provided an ultra-small dynamic bearing spindle motor comprising: a rotating shaft fixed to a housing; and the rotating shaft and a lubricant filled therein. A sleeve that rotatably engages through an air gap, and a dynamic pressure bearing in which a herringbone groove is formed in either the outer peripheral portion of the rotating shaft or the inner peripheral portion of the sleeve, and is held by the sleeve. A plurality of armature drive coils fixed to the housing, the permanent magnet rotor being magnetically engaged with a plurality of groups of armature drive coils. A ring-shaped permanent magnet that is magnetized in the thickness direction is disposed on the outer periphery of the central portion in the axial direction of a sleeve made of a cylindrical nonmagnetic material rotatably engaged with the large-diameter portion. Front and bottom of magnet A disk-shaped yoke made of a pair of magnetic materials having a cylindrical yoke in the axial direction so as to be fitted to the sleeve is provided, and a multi-pole magnetization is provided in a thin disk-shaped thickness direction on opposing surfaces of the disk-shaped yoke. At least one permanent magnet is mounted, and a plurality of groups of armature drive coils are arranged in parallel in a gap formed between the permanent magnet and the disk-shaped yoke and fixed to the housing. Wherein the magnetic flux of the ring-shaped permanent magnet is formed in a magnetic circuit formed by the pair of cylindrical yokes and a rotating shaft, and the sleeve is magnetically held in the axial direction. And

In order to solve the problem, the structure of the ultra small hydrodynamic bearing spindle motor according to claim 1 or 2 of the present invention is further arranged such that the plurality of groups of armature drive coils are arranged according to the number of phases. A plurality of disc-shaped or sector-shaped coils each formed by two or more coils having one magnetic pole pitch, and the armature coils of the plurality of groups are arranged to have an electrical angle of about 90 degrees according to the number of phases. Alternatively, it is arranged at about 120 degrees and fixed to the housing.

According to a third aspect of the present invention, which has been made to solve the problem, the structure of the microminiature dynamic bearing spindle motor further comprises:
It is characterized by being formed by plating or etching.

According to another aspect of the present invention, there is provided an ultra-small hydrodynamic bearing spindle motor having a sleeve and a sleeve rotatably engaged with the rotating shaft via an air gap. It is characterized in that a magnetic fluid is filled between them.

In order to solve the problem, the structure of the ultra small hydrodynamic bearing spindle motor according to claim 1 or 2 of the present invention is further preferable that the ring-shaped magnet or the thin disk-shaped magnet has a maximum energy product of 20 MGOe or more. Is 3
It is characterized by being formed of 0MGOe or more.

In order to solve the problem, the structure of the micro hydrodynamic bearing spindle motor according to claim 1 or 2 of the present invention is characterized in that a rotary load object is further disposed at the upper end of the sleeve.

[0017] The structure of the ultra-compact hydrodynamic bearing spindle motor according to claim 1 or 2 of the present invention for solving the problems is further characterized in that the rotating load object is a polygon mirror.

According to another aspect of the present invention, there is provided a microminiature dynamic pressure bearing spindle motor according to the present invention, wherein the disk-shaped yoke has a plurality of sector shapes corresponding to the number of pole pairs of a rotor. In this case, there is provided a window hole provided at intervals of one magnetic pole pitch.

In order to solve the problem, in the configuration of the ultra-small dynamic bearing spindle motor according to claim 1 of the present invention, the fan-shaped window hole of the disc-shaped yoke is extended substantially in the diameter direction. It is characterized by being formed of a straight portion, an inner peripheral portion along the outer periphery of the disk-shaped yoke, and an inner peripheral portion along the outer periphery of the ring-shaped permanent magnet.

[0020]

An embodiment of the present invention will be described below with reference to the drawings. In each drawing, FIG.
FIG. 1 is a sectional view of a main part of a first embodiment of a micro hydrodynamic bearing spindle motor according to the present invention. FIG. 2 is a top view of the micro hydrodynamic bearing spindle motor of the present invention shown in FIG. FIG. 3 is a detailed top view of the disc-shaped upper yoke of FIG. FIG. 4 shows FIG.
3 is a sectional view taken along line AA of FIG. FIG. 5 shows another dynamic pressure bearing structure of the microminiature dynamic bearing spindle motor of the present invention. FIG.
FIG. 4 is a sectional view of a main part of a second embodiment of the microminiature dynamic bearing spindle motor of the present invention. FIG. 7 is a configuration diagram of another armature drive coil of the microminiature dynamic bearing spindle motor of the present invention.

1 and 2, large-diameter portions 101a are formed at both ends of a rotating shaft 101 made of a magnetic material, and helical grooves or herringbone grooves 11 are formed in the large-diameter portions 101a.
Oa is processed by etching, machining, or the like, and one end of the rotating shaft 101 is fixed to the housing 106 by caulking or the like. The rotary shaft 101 has an air hole 101b for removing air bubbles contained in a lubricant or the like generated with the rotation.
Is provided between the center and the side surface of the rotating shaft 101, but may be provided in the axial direction of the inner periphery of the sleeve 102. The large-diameter portion 101a is provided with a sleeve 102 formed of a rotatable and inserted nonmagnetic material engaged with a gap 114 through a gap 114 and provided with a hollow disk-shaped seal plate 111 at the end. The above-mentioned sleeve 102 may be formed of a non-magnetic stainless steel or a ceramic such as alumina. The rotor 100 has a ring-shaped permanent magnet 105 magnetized in the thickness direction on the outer periphery of a central portion of the sleeve 102 in the axial direction.
2, a disk-shaped upper yoke 103 and a disk-shaped lower yoke 104 made of a pair of magnetic materials having a cylindrical upper and lower yokes 103a and 104a extended in the axial direction so as to be fitted. . A first coil group 107 which is a plurality of groups of armature drive coils fixed to the support plate 112a in a gap formed between the ring-shaped permanent magnet 105 and the pair of disk-shaped upper and lower yokes 103 and 104; The second coil group 108 is arranged in parallel, supported by the coil support 112 on the housing 106, and fixed to the housing 106. The support plate 112a may be made of a synthetic resin or a metal having low conductivity, for example, a Mg alloy, and may be divided into a thin ring shape or a plurality of groups of armature drive coils. First coil group 107 and second coil group 108
Are coils 107a and 107b wound in a disk shape, respectively.
And 108a, 108b. Further, the shapes of the coils 107a and 107b and 108a and 108b may be fan-shaped, or may be formed by plating or etching without using windings. Ring permanent magnet 10
The magnetic flux of 5 is applied to the pair of disc-shaped upper and lower yokes 103, 10
A first magnetic circuit 120 having an air gap formed in 4;
A second magnetic circuit 121 formed on a pair of cylindrical upper and lower yokes 103a and 104a, and a second magnetic circuit 12
A third magnetic circuit is formed in which the magnetic flux of the ring-shaped permanent magnet 105 branches off from the first and the rotating shaft 101 via the pair of cylindrical upper and lower yokes 103a, 104a, the shield plate 111, and the gap 114. 122. The driving force of the rotor 100 is controlled by the first magnetic circuit 120.
Is formed. The sleeve 102 is magnetically held in the axial direction so that the magnetic energy of the second magnetic circuit 121 formed between the sleeve 102 and the large-diameter portion 101a of the rotary shaft 101 is minimized. The seal plate 111 magnetically holds and prevents the outflow of the magnetic fluid lubricant to the upper surface when the magnetic fluid is used as the lubricant by the third magnetic circuit 122. The energy product of the ring-shaped permanent magnet 105 is anisotropic rare earth N
20MGOe for dFeB bonded magnet, anisotropic rare earth N
A dFeB sintered magnet has reached 50 MGOe and is in practical use. In the present embodiment, if the magnet is 20 MGOe or more, it can be sufficiently used practically. However, if the permanent magnet is 30 MGOe or more, the effect of further reducing power consumption can be obtained. A polygon mirror 109 is mounted on the upper end of the sleeve 102 as a rotating load object.

1 and 2 will be described in more detail. The rotor 100 of the present invention includes a disc-shaped upper yoke 103
And the disk-shaped lower yoke 104 is configured to have substantially the same shape in which the lower yoke 104 is vertically opposed. Therefore, the disc-shaped upper yoke 103 will be described below. The disc-shaped upper yoke 103 is composed of an upper yoke window 103b which is opened in a fan shape and an adjacent upper yoke window frame 103c. Upper yoke window frame 103
c denotes a magnetic pole having the same polarity, a linear portion 103e extending substantially in the diameter direction, an inner peripheral portion 103f along the outer periphery of the disk-shaped upper yoke 103, and the ring-shaped permanent magnet 105.
And the inner peripheral portion along the outer peripheral portion 105a, and the upper yoke window 103b does not have the different polarity magnetic poles of the same polarity. That is, if the adjacent upper yoke window frame 103c has the N pole, the S y pole is omitted from the opened upper yoke window 103b. In FIG. 2, the rotor 100 has an eight-pole configuration, but is not limited thereto. The upper yoke window frame 103c is provided with a yoke ring 10 to obtain mechanical strength.
Although connected by 3d, the yoke ring 103d may be omitted if the mechanical strength is sufficient. First coil group 10
7, the coils 107a and 107b have an overall outer shape of substantially one magnetic pole pitch, that is, an electric angle of 180 degrees (mechanical angle = 1).
80/4 = 45 degrees).
1, 107a2 and 107b1, 107b2 are formed. Similarly, the coil 1 forming the second coil group 108
08a and 108b have an overall outer shape of approximately one magnetic pole pitch,
That is, each of the coil sides 108a1, 108a2 and 1 is set so that the electric angle becomes 180 degrees (mechanical angle = 180/4 = 45 degrees).
08b1 and 108b2 are formed. The first coil group 107 and the second coil group 108 have an electrical angle of 9
It is arranged so as to be separated by 0 degrees (mechanical angle = 90/4 = 22.5 degrees). In the embodiment of the present invention, the motor is configured as an eight-pole, two-phase motor. However, the present invention is not limited to this. In this case, depending on the specifications of the drive control method, the support plate 112
A may be provided with a Hall element to perform full-wave or half-wave drive, or sensorless drive control without providing a Hall element.

3 and 4, the disc-shaped upper yoke 10
The upper yoke window frame 103c improves the efficiency of the magnetic circuit by providing a step 103c1 at the magnetic pole facing the lower yoke window frame 104c (not shown) of the disc-shaped lower yoke 104 to narrow the gap. It is configured.

FIG. 5 shows that the herringbone groove 115 is formed on the inner periphery at both ends of the sleeve 102. The rotating shaft 101 is of course without the herringbone groove, and the other structures are the same as those of FIG. Since they are the same, duplicate description is omitted.

In FIG. 6, the rotor 200 has a disk shape.
At least one thin-film multi-pole permanent magnet 116 multi-polarized in the thickness direction of a thin disk is mounted on the opposing surfaces of the lower yokes 103 and 104. in this case,
Although the disk-shaped yoke is not shown, it is not necessary to open a window. The thin-film multipole permanent magnet 116 is made of a rare earth magnet such as NdFeB.
Sputtering, machining, etc. magnets 30 to 500 μm
Formed. The thin-film multipole permanent magnets 116 may be mounted in a pair on a disk-shaped upper surface and a lower surface of the lower yokes 103 and 104, for example, depending on the specification of a product requiring a high torque. 123 is formed. The ring-shaped permanent magnet 105 only needs to hold the lubricant 113 and may be thin, and forms the magnetic circuit 124.
Herringbone grooves 115 are formed in the inner peripheral portions at both ends of the sleeve 102, and the sleeve 102 engages with the large-diameter portion 101 a of the rotating shaft 101 via the lubricant 113 injected into the gap 114.

FIG. 7 shows an arrangement of three-phase coils.
The three-phase coil group 117, the three-phase coil group 118, and the three-phase coil group 119 have a ring-shaped support plate 11 having an electrical angle of 120 degrees.
2a. The support plate 112a formed of anodized aluminum material or resin may be integrally formed of a thin hollow disk, or may be divided into a plurality of pieces. If the integrally formed support plate 112a is used, the rotor 100 may be inserted between the disc-shaped upper and lower yokes 103 and 104 when the rotor 100 is assembled.
Each coil 117a, 117b, 118a, 118b, 1
The relationship between 19a and 119b is the same as the content already described, and a description thereof will be omitted.

In the above description of the present invention, magnetic fluid has been mainly used as a lubricant. However, even when a normal lubricant is used, the present invention can be applied to the microminiature dynamic bearing spindle motor of the present invention. it can. 1, 5 and 6, if an oil repellent is applied to the inner surface of the seal plate 111, a normal lubricant can be used.

As can be seen from FIGS. 1 and 2, in the first microminiature dynamic bearing spindle motor of the present invention, since the armature drive coil is an air-core coil, no detent torque is generated, and the cause of uneven rotation is eliminated. Have been. Further, a common magnetic circuit, that is, the first magnetic circuit 12 of the rotor 100 for driving the spindle motor only by the ring-shaped permanent magnet 105 is used.
0, the cylindrical upper and lower yokes 103a and 104a, and the large-diameter portion 101a of the rotating shaft 101 form the second magnetic circuit 121. The axial direction is maintained, and the rotor 100 can be configured to be lightweight as understood from the above description, so that the thrust bearing is unnecessary.

FIG. 6 shows that the second microminiature dynamic bearing spindle motor according to the present invention has no armature driving coil, and therefore has no detent torque and eliminates the cause of rotational unevenness. Further, the ring-shaped permanent magnet 105 and the rotor 2
A magnetic circuit 1 of the rotor 200 for driving the spindle motor only uses the thin-film multipole magnet 116.
23, cylindrical upper yoke 103a, cylindrical lower yoke 10
4a and the large-diameter portion 101a of the rotating shaft 101, the magnetic circuit 124
Is formed, the axial direction of the sleeve 102 is held by the force generated by the axial variation of the magnetic energy, and the rotor 200 can be configured to be lightweight as understood from the above description. Not required.

[0030]

According to the present invention, an ultra-small dynamic bearing spindle motor having a diameter of 20 mm or less and a thickness of 10 mm or less can be realized since the structure of the spindle motor using the dynamic pressure bearing is simple and no thrust bearing is required. For example, the diameter of the rotating shaft may be 1 to 2 mm, the outer diameter of the rotor may be 10 to 20 mm, and the overall thickness may be 2 to 10 mm or less.

According to the present invention, since the armature drive coil is air-core, there is no detent torque, little torque ripple, no rotation unevenness, no iron loss, low power consumption, and ultra-small dynamic pressure with high rotation accuracy. A bearing spindle motor can be realized.

Further, according to the present invention, a small amount of a permanent magnet having a high energy product of, for example, 20 MGOe or more, desirably 30 MGOe or more is used, and the torque constant is greatly increased to reduce the power consumption, thereby reducing the cost / performance of the motor. Can be improved.

Further, according to the present invention, the present invention is effective for use in a micro image scanner, a micro rotary storage device and the like.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a first embodiment of a micro hydrodynamic bearing spindle motor according to the present invention.

FIG. 2 is a top view of the micro hydrodynamic bearing spindle motor of the present invention shown in FIG. 1;

FIG. 3 is a detailed top view of the disc-shaped upper yoke of FIG. 2;

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is another dynamic pressure bearing structure of the microminiature dynamic bearing spindle motor of the present invention.

FIG. 6 is a sectional view of a main part of a second embodiment of a microminiature dynamic bearing spindle motor according to the present invention.

FIG. 7 is a configuration diagram of another armature drive coil of the micro hydrodynamic bearing spindle motor of the present invention.

FIG. 8 is a schematic diagram of a spindle motor using a dynamic pressure bearing corresponding to FIG. 1 of Japanese Patent Application Laid-Open No. 62-270816 (Document A).

FIG. 9 of JP-A-8-16381 (Document B)
FIG. 2 is a schematic view of a spindle motor using a dynamic pressure bearing corresponding to FIG.

FIG. 10 is a schematic diagram of a spindle motor using a dynamic pressure bearing corresponding to FIG. 1 of JP-A-4-69404 (Document C).

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Rotor 101 Rotating shaft 101a Large diameter portion 101b Air hole 102 Sleeve 103 Disc-shaped upper yoke 103a Cylindrical upper yoke 104 Disc-shaped lower yoke 104a Cylindrical lower yoke 105 Ring-shaped permanent magnet 106 Housing 107 First coil group 108 second coil group 109 polygon mirror 110a herringbone groove 111 seal plate 112 coil support 113 lubricant 114 air gap 120 first magnetic circuit 121 second magnetic circuit 122 third magnetic circuit

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // F16C 17/02 F16C 17/02 A

Claims (11)

[Claims] 1. A rotary shaft fixed to a housing, a sleeve rotatably engaged with the rotary shaft via a space filled with a lubricant, and an outer peripheral portion of the rotary shaft or an inner portion of the sleeve. A permanent magnet rotor held by the sleeve is magnetically engaged with a plurality of groups of armature drive coils fixed to the housing; In the spindle motor arranged so as to be provided, a large diameter portion is provided at both ends of a pair of rotating shafts made of a magnetic material, and a cylindrical sleeve made of a non-magnetic material rotatably engaged with the large diameter portion. A ring-shaped permanent magnet magnetized in the thickness direction is disposed on the outer periphery of the central portion in the axial direction, and a pair of magnets having a cylindrical yoke in the axial direction to be fitted to the sleeve on the upper and lower surfaces of the permanent magnet. A disk-shaped yoke made of material A plurality of groups of armature drive coils are disposed substantially in parallel in a gap formed between the permanent magnet and the pair of disk-shaped yokes and fixed to the housing, and a magnetic flux of the ring-shaped permanent magnet is provided. A magnetic circuit having a gap formed between the pair of disk-shaped yokes, and a magnetic circuit formed on a rotating shaft through the pair of cylindrical yokes and the gap are configured to diverge into a magnetic circuit, An ultra-compact hydrodynamic bearing spindle motor, wherein the sleeve is magnetically held in the axial direction. 2. A rotating shaft fixed to a housing, a sleeve rotatably engaged with the rotating shaft via a space filled with a lubricant, and an outer peripheral portion of the rotating shaft or an inner portion of the sleeve. A permanent magnet rotor held by the sleeve is magnetically engaged with a plurality of groups of armature drive coils fixed to the housing; In the spindle motor arranged so as to be provided, a large diameter portion is provided at both ends of a pair of rotating shafts made of a magnetic material, and a cylindrical sleeve made of a non-magnetic material rotatably engaged with the large diameter portion. A ring-shaped permanent magnet magnetized in the thickness direction is disposed on the outer periphery of the central portion in the axial direction, and a pair of magnets having a cylindrical yoke in the axial direction to be fitted to the sleeve on the upper and lower surfaces of the permanent magnet. A disk-shaped yoke made of material At least one permanent magnet that is multipolarly magnetized in the thickness direction of a thin disk is mounted on opposing surfaces of the disk-shaped yoke, and is formed between the permanent magnet and the disk-shaped yoke. A plurality of armature drive coils are arranged in parallel in the air gap and fixed to the housing, and the magnetic flux of the ring-shaped permanent magnet is applied to a magnetic circuit formed on the pair of cylindrical yokes and the rotating shaft. An ultra-small hydrodynamic bearing spindle motor configured to be formed, wherein the sleeve is magnetically held in the axial direction. 3. The plurality of armature drive coils are arranged in accordance with the number of phases, and are formed of a plurality of disc-shaped or sector-shaped two or more coils each coil side of which has one pole pitch. 3. The method according to claim 1, wherein the armature coils of the plurality of groups are arranged at an electrical angle of about 90 degrees or about 120 degrees according to the number of phases, and are fixed to the housing. The ultra-small hydrodynamic bearing spindle motor as described. 4. The micro hydrodynamic bearing spindle motor according to claim 3, wherein the conductor portions of the plurality of groups of armature drive coils are formed by plating or etching. 5. The microminiature dynamic pressure bearing according to claim 1, wherein a magnetic fluid is filled between the rotary shaft and a sleeve rotatably engaged with a gap. Spindle motor. 6. The micro hydrodynamic bearing according to claim 1, wherein a maximum energy product of the ring-shaped permanent magnet or the thin disk-shaped permanent magnet is formed in a range of 20 MGOe or more, preferably 30 MGOe or more. Spindle motor. 7. The microminiature hydrodynamic bearing spindle motor according to claim 1, wherein a rotating load object is disposed on an upper end of the sleeve. 8. The micro hydrodynamic bearing spindle motor according to claim 1, wherein the rotating load object is a polygon mirror. 9. The disk-shaped yoke has a plurality of fan-shaped window holes corresponding to the number of pole pairs of the rotor and arranged at intervals of one magnetic pole pitch. 2. The microminiature dynamic pressure bearing spindle motor according to 1. 10. The disk-shaped yoke has a fan-shaped window hole formed in a substantially diametrically extending linear portion, an inner peripheral portion along an outer periphery of the disk-shaped yoke, and a ring-shaped permanent magnet. The ultra-small hydrodynamic bearing spindle motor according to claim 9, wherein the spindle motor is formed by an inner peripheral portion along an outer peripheral portion. 11. A yoke frame adjacent to a window hole disposed at intervals of one magnetic pole pitch and facing each other with a step formed so as to narrow a gap between the pair of disk-shaped yokes. 11. The micro hydrodynamic bearing spindle motor according to claim 9, wherein the spindle motor is disposed on a spindle motor.