JP3656675B2 - Spindle motor with turntable - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle motor having a turntable for supporting and rotating a recording medium such as an optical disk or a magneto-optical disk.
[0002]
[Prior art and problems to be solved by the invention]
In the spindle motor having the conventional turntable as shown in FIG. 4, an annular protrusion c for supporting the lower surface of the recording disk b is formed near the outer periphery on the upper side of the rotor hub a having a substantially inverted cup shape. In addition, a clamping magnet e for magnetically attracting and holding the recording disk b is disposed in an annular recess d in an upper opening formed on the inner peripheral side of the annular projection c. A turntable f is configured. The upper surface of the clamping magnet e is arranged in a state slightly lower than the annular protrusion c.
[0003]
Since there is a strong demand for thinning a recording medium driving device in which this type of spindle motor is incorporated, and a computer such as a notebook computer, the spindle g having the conventional turntable shown in FIG. Is provided at the same vertical position as the bearing h, so that the thickness is reduced.
[0004]
However, while the demand for further thinning is increasing, there is a limit to the thinning of the member, and the gap w between the stator coil i and the rotor hub a is also limited by the stator coil i wound around the stator core j. Since there is variation in the upper end position, it cannot be reduced beyond the allowable gap. That is, the configuration of a spindle motor having a conventional turntable is reaching the limit of thinning, and it has been difficult to meet the demand for further thinning.
[0005]
The present invention has been made in view of the above-mentioned problems existing in the prior art, and an object of the present invention is to provide a spindle motor having a thinner turntable.
[0006]
[Means for Solving the Problems]
The spindle motor having the turntable of the present invention is
A rotor hub, a rotor magnet, a stator core facing radially inward with respect to the rotor magnet, and a stator coil wound around the stator core, and a recording medium on one side in the rotational axis direction of the rotor hub A spindle motor in which a turntable is configured by forming a support portion and providing a recording medium holding means on the inner peripheral side of the recording medium support portion on the one side of the rotor hub,
The rotor hub is formed by pressing,
Of the rotor hub, a second annular portion facing the stator coil in the rotational axis direction on the outer peripheral side of the first annular portion from the other side in the rotational axis direction of the first annular portion where the recording medium holding means is located. The other side of the part is located on the one side,
The recording medium support portion on the one side of the second annular portion;
The end of the one side of the stator coil is positioned on the one side of the first annular portion or on the other side of the first annular portion, with a clearance with the rotor hub being more than an allowable gap. Or the same position in the direction of the rotation axis as in the above, or a position in the rotation direction in the rotation axis that is smaller than the permissible gap between the stator coil and the rotor hub. To do.
[0007]
The permissible gap refers to a minimum necessary distance between the rotor hub and the stator coil in order to reliably avoid contact between the rotor hub and the stator coil.
[0008]
In the spindle motor having the turntable of the present invention, the recording medium support portion is formed on one side of the rotor hub in the rotational axis direction (for example, the upper side when the rotational axis direction is the vertical direction). The turntable is configured by providing recording medium holding means on the inner peripheral side of the recording medium support portion on the one side (for example, the upper side) of the rotor hub. Accordingly, the recording medium is driven to rotate while being supported by the recording medium support portion (for example, the upper side) of the rotor hub and held by the recording medium holding means on the inner peripheral side thereof.
[0009]
Of the rotor hub, the stator coil and the direction of the rotation axis (in the direction of the axis of rotation) on the outer peripheral side of the first annular portion from the other side (for example, the lower side) of the first annular portion where the recording medium holding means is located. For example, the other side (for example, the lower side) of the second annular portion facing in the vertical direction is positioned on the one side (for example, the upper side). Therefore, the end of the one side (for example, the upper side) of the stator coil is set to be more than the other side (for example, the lower side) of the first annular portion while taking the gap with the rotor hub more than the allowable gap. ), The same rotational axis center position as the other side (for example, the lower side) of the first annular portion, or a rotational axial distance smaller than the allowable gap between the stator coil and the rotor hub It can be located on the other side (for example, lower side) than the other side (for example, lower side) of the first annular portion. As a result, the dimension in the direction of the rotational axis of the radial portion of the spindle motor where the stator coil is located is shortened.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. 1 to 3.
[0011]
FIG. 1 is a cross-sectional view of a spindle motor (electric motor) having a turntable as an example of an embodiment of the present invention.
[0012]
In the spindle motor of FIG. 1, a stator core 16 around which a stator coil 14 is wound is fixedly fitted on the upper side of an annular projecting portion 10 a provided at the upper and lower intermediate positions of a substantially cylindrical stator frame 10. ing.
[0013]
Ball bearings 18 and 20 are fitted on the inner peripheral side of the stator frame 10 on the upper and lower sides of the inner protrusion 10b projecting from the upper and lower intermediate positions, respectively, and are rotated via the ball bearings 18 and 20. The shaft 22 is rotatably supported. The bottom of the stator frame 10 is sealed with a cap 24.
[0014]
The rotor hub 26 has a substantially inverted saddle shape, and includes a short cylindrical portion 26a at the inner peripheral end, a top plate portion 26b, and a cylindrical outer peripheral wall portion 26c. The inner peripheral end of the top plate portion 26b is connected to the lower outer peripheral portion of the short cylindrical portion 26a, and the upper end portion of the outer peripheral wall portion 26c is connected to the outer peripheral end portion of the top plate portion 26b. The rotor hub 26 is configured so that the inner periphery of the short cylindrical portion 26a is fitted on the rotary shaft 22 and the lower end surface of the short cylindrical portion 26a is in contact with the upper surface of the inner ring of the upper ball bearing 20, and The outer fitting is fixed. The inner peripheral surface and the lower end surface of the short cylindrical portion 26a have a cylindrical surface shape centered on the axial center line of the rotor hub 26 and perpendicular to the axial center line with high accuracy by cutting or the like in order to increase assembly accuracy. It is processed into a flat surface.
[0015]
The top plate portion 26b is mainly composed of an annular plate portion 26b1 on the inner peripheral side and an annular groove-shaped portion 26b2 having a lower opening on the outer peripheral side. In this example, the annular groove-shaped portion 26b2 has a substantially inverted V-shaped cross section, and the entire rotor hub 26 can be formed by press working. However, the present invention is not limited to this. As shown in FIG. 3, the cross section may be a substantially inverted U shape.
[0016]
On the upper side of the annular groove-shaped portion 26b2, an annular ridge 28 as a recording medium support portion is formed. The recording medium support portion is not necessarily required to have such a shape. For example, it may be discontinuous in the circumferential direction, or it may not be such a ridge, but the upper side of the annular groove-shaped part 26b2 may be used as it is as a recording medium support part. In any case, the upper surface (recording medium support surface) of the recording medium support portion is a reference surface at the height position of the removable recording medium 30 (for example, an optical disk, a magneto-optical disk, etc.). Therefore, it is processed into a plane perpendicular to the axis of the rotor hub 26 with high accuracy.
[0017]
On the upper side of the annular flat plate portion 26b1 (first annular portion) formed between the short cylindrical portion 26a and the annular groove-shaped portion 26b2 and formed in the annular recess of the upper opening, an annular plate shape as an example of a recording medium holding means. The clamp magnet 32 is arranged and fixed by an adhesive 34. Since the adhesive 34 easily accumulates between the upper inner peripheral portion of the annular groove-shaped portion 26b2 and the outer peripheral portion of the clamping magnet 32, the adhesive fixing work is easy and reliable. In order for the lower surface of the recording medium 30 to be supported by the annular ridge 28, the upper surface of the clamping magnet 32 and the upper surface of the short cylindrical portion 26 a are configured to be lower than the upper surface of the annular ridge 28. The top plate portion 26b, in which the clamping magnet 32 is arranged and fixed, the annular protrusion 28 is provided, and is configured to be manually rotatable, constitutes a turntable.
[0018]
A cylindrical rotor magnet 36 is fitted and fixed to the inner peripheral side of the outer peripheral wall portion 26c of the rotor hub 26, and is opposed to the stator core 16 via a radial gap.
[0019]
The material of the rotor hub 26 is preferably a ferromagnetic material that functions as a yoke for the clamping magnet 32 or the rotor magnet 36, and in particular, a ferromagnetic stainless steel that does not rust even when subjected to cutting. When the rotor hub 26 is made of a ferromagnetic material, the magnetic attractive force acting between the rotor hub 26 and the clamping magnet 32 or the rotor magnet 36 also acts as a fixing force between them.
[0020]
The annular groove-shaped portion 26b2 constitutes a second annular portion that faces the stator coil 14 in the vertical direction (rotation axis direction), and the lower surface of the annular groove-shaped portion 26b2 is higher than the lower surface of the annular flat plate portion 26b1. Located in. Therefore, as shown in FIG. 1, the upper end portion of the stator coil 14 allows a gap M between the rotor hub 26 and an allowable gap (for example, about 2 to 5 times, preferably about 3 times the wire diameter of the stator coil 14). In addition to the above, the lower flat surface of the annular flat plate portion 26b1 can be positioned lower than the allowable gap by a distance N. As a result, the vertical dimension (rotational axis direction) dimension of the portion where the annular groove-shaped portion 26b2 and the stator coil 14 are located, that is, the outer peripheral side of the spindle motor, is shortened, that is, thinned. In addition, if the vertical dimension of the rotating shaft is equal to or less than the portion where the annular groove-shaped portion and the stator coil are located, the vertical dimension of the entire spindle motor is shortened.
[0021]
In the example shown in FIGS. 2 and 3, the upper end portion of the stator coil 14 has a gap with the rotor hub 26 that is larger than the allowable gap, and is in the annular recess 38 of the lower opening formed by the annular groove-shaped portion 26b2. Is located above the lower side surface of the annular flat plate portion 26b1. Thereby, the vertical direction dimension of the part in which the annular groove-shaped part 26b2 and the stator coil 14 are located can be further shortened, that is, thinned. The other symbols have the same meaning as in the example of FIG.
[0022]
The embodiment of the present invention has been described above by taking the shaft rotation type spindle motor as an example. However, the scope of the present invention is applicable to a spindle motor in which a rotor hub is rotatably supported via a bearing with respect to a fixed shaft body. It does not deviate from.
[0023]
In the above description of the embodiment, the vertical positional relationship is merely for convenience of explanation based on the drawings, and does not limit the actual use state or the like. Further, the dimensions, number, material, shape, relative arrangement, etc. of the component parts are not intended to limit the scope of the present invention only to those unless otherwise specified, This is just an example.
[0024]
【The invention's effect】
According to the present invention, since the dimension in the direction of the rotational axis of the radial direction portion where the stator coil is located in the spindle motor having the turntable is shorter than the conventional one, the whole is thin, or at least the stator coil is located. A spindle motor having a turntable that is thin in a radial position can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a spindle motor having a turntable as an example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a main part of a spindle motor having a turntable as another example of an embodiment of the present invention.
FIG. 3 is a cross-sectional view of a main part of a spindle motor having a turntable as still another example of an embodiment of the present invention.
FIG. 4 is a cross-sectional view of a spindle motor having a conventional turntable.
[Explanation of symbols]
14 Stator coil 26 Rotor hub 26b Top plate part 26b1 Annular flat plate part 26b2 Annular groove-shaped part 28 Annular ridge 32 Clamping magnet M Gap N Distance

Claims (1)

A rotor hub, a rotor magnet, a stator core facing radially inward with respect to the rotor magnet, and a stator coil wound around the stator core, and a recording medium on one side in the rotational axis direction of the rotor hub A spindle motor in which a turntable is configured by forming a support portion and providing a recording medium holding means on the inner peripheral side of the recording medium support portion on the one side of the rotor hub,
The rotor hub is formed by pressing,
Of the rotor hub, a second annular portion facing the stator coil in the rotational axis direction on the outer peripheral side of the first annular portion from the other side in the rotational axis direction of the first annular portion where the recording medium holding means is located. The other side of the part is located on the one side,
The recording medium support portion on the one side of the second annular portion;
The end of the one side of the stator coil is positioned on the one side of the first annular portion or on the other side of the first annular portion, with a clearance with the rotor hub being more than an allowable gap. Or the same position in the direction of the rotation axis as in the above, or a position in the rotation direction in the rotation axis that is smaller than the permissible gap between the stator coil and the rotor hub. A spindle motor having a turntable.

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