JP3755233B2 - Rotation drive mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a rotational drive mechanism, and more specifically, suppresses vibrations generated when a synthetic rotating body that is unbalanced in weight is rotated. It relates to expanding technology.
[0002]
[Prior art]
Many industrial machines, household appliances, computers, and the like are provided with a rotating member that is rotated by a motor or the like. For example, a disk drive device (rotary drive device) used in a computer reproduces an information signal by an optical pickup device or a magnetic head device while rotating an optical disk or a magneto-optical disk as a signal recording medium by a disk rotation drive mechanism. / Or record. In such a disk drive device, an optical disk rotated by a disk rotation drive mechanism is also included in a part of the composite rotating body.
[0003]
The disk drive device includes an optical pickup device that irradiates the optical disk rotated by the disk rotation driving mechanism with a laser beam. The disk rotation drive mechanism includes a disk table on which an optical disk is mounted and a spindle motor for rotating the disk table.
[0004]
The optical pickup device includes a light source for irradiating the optical disk with laser light, and a photodetector for receiving the reflected light of the laser light reflected on the signal recording surface of the optical disk. The optical pickup device and the disk rotation drive mechanism are mounted on, for example, a subchassis. The subchassis supports the optical pickup device so as to be movable in a direction in which the subchassis is moved toward and away from the disk rotation driving mechanism fixedly supported by the subchassis.
[0005]
The disk drive device configured as described above records and / or reproduces an information signal by irradiating an optical disk rotated by a spindle motor with a laser beam emitted from an optical pickup device.
[0006]
[Problems to be solved by the invention]
By the way, a recording disc such as an optical disc may be unbalanced in weight during manufacturing. When a recording disk having a heavy imbalance is rotated, the center of rotation does not coincide with the center of gravity, and the recording disk vibrates with the disk table. When such vibration occurs, focusing and tracking on the signal recording surface of the recording disk by the optical pickup device and tracking of the recording disk by the magnetic head device cannot be performed satisfactorily.
[0007]
In general, the amount of imbalance that occurs in a recording disk varies depending on the recording disk. That is, the substrate thickness of the recording disk is non-uniform or the density is non-uniform, and the center of gravity of the recording disk is not located at the center of the recording disk. Will occur.
[0008]
Furthermore, recently, it has become possible to record or reproduce data on a recording disk at a high speed, and there is also a problem that the vibration of the recording disk increases as the rotational speed increases.
[0009]
Therefore, if there is no vibration suppression means that can respond at any time according to the amount of weight imbalance or the rotational speed of each recording disk, the vibration of the recording disk cannot be suppressed.
[0010]
Accordingly, an object of the rotational drive mechanism of the present invention is to overcome the above-described problems and to perform the rotation performed by the rotational drive means in a state in which the eccentricity of the rotational center does not occur.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problem, the rotational drive mechanism of the present invention is rotated by a rotational drive means via a support shaft, and a case body having a moving space in which a cross-sectional shape in a direction orthogonal to the axial direction forms an annular shape, A balance member movably disposed in the movement space of the case body, and the balance member is moved relative to the other part of the synthetic rotator along with the rotation of the rotation driving means, Balance member that has an automatic alignment mechanism that aligns the center of gravity of the combined rotating body by positioning it on the rotation axis, and holds the balance member at the center of the case body until a predetermined number of rotations is achieved during rotation acceleration The holding means and the balance member that has been moved to the outer peripheral portion at a speed equal to or higher than the predetermined rotational speed do not return to the center of the case body until the rotational speed is lower than the predetermined rotational speed at the time of rotational deceleration. Like It is provided with a balancing member detent means.
[0012]
Therefore, in the rotation drive mechanism of the present invention, since the automatic alignment mechanism is provided, even if there is an eccentric center of gravity in the combined rotating body, the combined rotating body can be rotated in an aligned state, Since the balance member holding means is provided, when the rotation is accelerated, the balance member is released after the high speed rotation. Since the centering action is performed quickly and the balance member return restraining means is provided, the centering state can be maintained up to the low speed rotation at the time of rotational deceleration, so that the rotational speed of the rotational drive mechanism is used. The area can be expanded.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Details of the rotational drive mechanism of the present invention will be described below in accordance with an embodiment shown in the accompanying drawings.
[0014]
First, the principle of the automatic alignment mechanism in the rotation drive mechanism of the present invention will be described.
[0015]
Such an automatic alignment mechanism is described by Theear's automatic balancing device. For details on the automatic balancing apparatus of Thear, refer to “Mechanical Mechanics” (March 1982) P146, 147 published by Rigaku Corporation.
[0016]
In the present specification, the automatic balancing apparatus 1 of Thear will be briefly described with reference to FIG. The automatic balancing device 1 of Thearl is a rotating disk 2 and two steel balls (balance members) 4 and 4 arranged so as to freely move in a groove 3 of the rotating disk 2 and rotation. When the rotational speed of the rotating disk 2 exceeds the natural circular frequency (dangerous speed) of the rotating shaft 5, Me = 2 mr · cos α (M: rotating with the rotating disk 2). Rotor ball mass of shaft 5, e: rotor part eccentricity, m: mass of steel ball 4, r: steel ball starting radius, α: angle formed by eccentric direction and steel ball 4) 4 is an apparatus which is automatically positioned, eliminates the eccentricity of the rotating disk 2, and reduces the vibration of the rotor portion.
[0017]
Here, the reason why the automatic automatic collision device 1 of Theear operates when the natural frequency of the rotating shaft 5 is exceeded will be briefly described. The movement of the center of gravity G of the rotating disk 2 and the steel balls 4, 4 This is because the movement is in the opposite phase and the steel balls 4 and 4 are moved and positioned in the direction opposite to the eccentric direction.
[0018]
The rotational drive mechanism 6 of the present invention has an automatic alignment mechanism 7 based on the principle of the Theearl automatic balancing apparatus 1. In the above-mentioned Theearl automatic balancing apparatus 1, two steel balls 4 and 4 are used as the balance member. However, the balance member in the automatic alignment mechanism 7 of the rotary drive mechanism 6 of the present invention is described here. The present invention includes all balance members described in the specification of 1997 Patent Application No. 53704 filed on March 7, 1997 by the present applicant.
[0019]
The rotation driving mechanism 6 includes a rotation driving means 8 and an automatic alignment mechanism 7 fixed to a support shaft 9 of the rotation driving means 8. The rotation driving mechanism 6 is elastic to a base chassis 10 fixed to the apparatus main body. It is fixed to the subchassis 12 supported via the member 11 (see FIG. 2). As a result, the sub chassis 12 is floatingly supported with respect to the base chassis 10, and the vibration system 13 is configured by the sub chassis 12, the components (rotation drive mechanism 6 and the like) mounted on the sub chassis 12, and the elastic member 11. As will be described later, the vibration system 13 plays an important role in the automatic alignment mechanism 7 of the rotational drive mechanism 6 of the present invention.
[0020]
The automatic alignment mechanism 7 includes a case body 15 having an annular movement space 14 and a plurality of balance members 16, 16,..., Which are movably arranged in the movement space 14 of the case body 15. Provide (see FIG. 3). The case body 15 corresponds to the rotating disk 2 in the Automatic automatic balancing device 1 of the above-mentioned, and the balance members 16, 16, ... correspond to the steel balls 4, 4 respectively.
[0021]
Note that such an automatic alignment mechanism 7 only needs to be fixed to the support shaft 9 of the rotation driving means 8, and the position thereof may be, for example, inside the mechanism of the rotation driving means 8, and will be described later. You may make it incorporate in the inside of the disk table demonstrated in an Example, or the inside of a chucking member.
[0022]
In the central part of the case body 15, balance member holding means for holding the balance members 16, 16,... At the central part until a predetermined rotational speed (hereinafter referred to as “separation rotational speed”) is reached. .. Are provided, and the balance members 16, 16,... Are rotated together with the balance member holding means 17 until the rotational drive means 8 reaches the separation rotational speed at the time of rotational acceleration. Thereby, the relative speed with respect to the case body 15 of the balance members 16, 16,...
[0023]
If the balance members 16, 16,... Are allowed to move freely in the moving space 14 from the start of rotation of the rotation drive means 8, the inertia balances even if the case body 15 rotates. A state where the members 16, 16,... Are stopped or a state delayed with respect to the rotation of the case body 15 occurs, and the relative speed between the case body 15 and the balance members 16, 16,. This is because it takes time to reach “0”, and as described later, the alignment is delayed. Therefore, it is desirable to set the separation rotation speed as high as possible and slightly lower than the resonance frequency of the vibration system 13.
[0024]
Further, the balance member 16, 16,... Moved to the outer peripheral portion of the case body 15 is returned to the central portion of the case body 15 until the rotation speed is lower than the above-described separation rotation speed. Balance member return suppression means 18 is provided to prevent the balance members 16 and 16 from rotating until the rotational speed is lower than the above-mentioned separation rotational speed (hereinafter referred to as “return rotational speed”) during rotational deceleration. Are positioned on the outer peripheral portion of the case body 15. Thereby, even if it becomes lower than the said separation | separation rotation speed, an alignment state is maintained until it becomes a return rotation speed. In the case where the balance member return suppressing means 18 is not provided, for example, when the balance member holding means 17 described in the embodiment described later is a magnet, the return rotational speed is the balance members 16, 16,. · Means a rotational speed lower than the rotational speed at which the suction force against the centrifugal force applied to the balance members 16, 16,.
[0025]
Therefore, the balance members 16, 16,... Do not move to the outer periphery unless they are rotated at a high speed (the above-mentioned separation rotational speed) during rotation acceleration, and rotate at a low speed (return) during rotation deceleration. If the rotational speed does not reach the center, the balance does not return to the central portion, and the balance members 16, 16,...
[0026]
The elastic coefficient of the elastic member 11 is determined by the elastic member 11 and the mass of the sub-chassis 12 (including the mass of the sub-chassis 12 mounted), and the resonance frequency of the vibration system 13 constituted by these is determined as the rotational drive mechanism 6. Set lower than the number of rotations used. The elastic member 11 can be any elastic member, and may be a natural rubber, a synthetic rubber, a soft synthetic resin, or a spring.
[0027]
The rotation drive means 8 includes all components related to rotation control such as a drive system such as a spindle motor and a control system such as a motor driver.
[0028]
The composite rotator 19 includes all members rotated by the rotation driving means 8, such as a disk table, a chucking member, and an automatic alignment mechanism 7 in the disk drive device described in the embodiments described later, as well as rotation driving means. 8 includes a rotor 20 that is a rotating member and a recording disk mounted on the support shaft 9 and a disk table.
[0029]
The vibration system 13 has the following functions in the automatic alignment mechanism 7 of the rotary drive mechanism 6 of the present invention.
[0030]
That is, in the self-aligning mechanism 7, when the rotational speed of the rotation driving means 8 exceeds a so-called dangerous speed (speed at which shaft shake increases), the balance members 16, 16,. 19 is moved to a position that cancels the weight imbalance of 19 (hereinafter referred to as “retraction phenomenon”), and therefore, the centering action is performed. (Dangerous speed) is several 10 K At the normal rotation speed (about 1000 to 6000 rpm), the above critical speed is far below. Therefore, by constructing the vibration system 13, the retraction of the balance members 16, 16,... Can be caused by the resonance of the vibration system 13 without reaching the original critical speed.
[0031]
【Example】
Embodiments of the rotational drive mechanism of the present invention will be described below with reference to the accompanying drawings. In each of the embodiments shown below, the present invention is applied to a rotational drive mechanism of a 12 × speed disk drive device that performs reproduction or recording on a recording disk such as an optical disk or a magneto-optical disk.
[0032]
4 to 9 show a disk drive device 21 using a rotational drive mechanism according to the first embodiment.
[0033]
The recording disk 22 is configured by forming a signal recording surface on a transparent substrate formed into a disk shape having a diameter of 120 mm using a synthetic resin material such as polycarbonate. The recording disk 22 is provided with a circular opening (chucking hole) 22a at the center thereof. The recording disk 22 is positioned by fitting a positioning projection of a disk table, which will be described later, into the circular opening 22a.
[0034]
The disk drive device 21 includes a mechanical chassis 25 on which a spindle motor 23 and an optical pickup device 24 serving as rotational driving means are mounted, and a plurality of dampers 27, 27 for floatingly supporting the mechanical chassis 25 with respect to the base chassis 26,. (See FIG. 4). The mechanical chassis 25 corresponds to the sub chassis 12, and the damper 27 corresponds to the elastic member 11.
[0035]
The optical pickup device 24 is supported on the mechanical chassis 25 via guide shafts 28 and 28 so as to be movable in the radial direction of the recording disk 22 mounted on the disk table. The optical pickup device 24 includes a light source and a photodetector (not shown) such as a laser diode, irradiates the recording disk 22 with laser light emitted from the light source via the objective lens 29, and also records the laser light recording disk. The reflected light from 22 is detected by a photodetector.
[0036]
The rotary drive mechanism 30 is fixed to the upper end portion of the spindle shaft 31 in the same manner as the case body 32 fixed to the spindle motor 23 and a position near the upper end of the spindle (spindle shaft) 31 rotated by the spindle motor 23. And a disk table (turn table) 33 (see FIG. 5).
[0037]
The spindle shaft 31 is supported by a motor substrate 34 fixed on the mechanical chassis 25 so as to be rotatable around an axis via rotation bearings 35 and 35. A motor rotor 36 constituting the spindle motor 23 is attached to the spindle shaft 31. The motor rotor 36 is formed in a substantially cylindrical shape, and a drive magnet 37 is fixed to the inner surface portion. That is, the spindle shaft 31 is a spindle (drive shaft) of the spindle motor 23. Further, the drive magnet 37 faces the stator coil 38 fixed on the motor substrate 34 (see FIG. 5).
[0038]
The disk table 33 is formed in a substantially disc shape, and is fixed to the spindle shaft 31 by press-fitting the tip end portion of the spindle shaft 31 into a support shaft press-fitting hole formed in the center portion. The disk table 33 is provided with a positioning projection 33a for positioning the recording disk 22 at the center thereof. The positioning projection 33 a is provided so as to protrude in a substantially truncated cone shape, and is positioned in the circular opening 22 a of the recording disk 22 to position the recording disk 22.
[0039]
Further, a magnet is built in the positioning protrusion 33a, and a chucking member (clamper) (not shown) having a magnetic material is attracted. That is, the recording disk 22 is securely held by being sandwiched between the disk table 33 and the chucking member by the positioning projection 33a attracting the chucking member. When a drive current is supplied to the stator coil 38 of the spindle motor 23 and the motor rotor 36 rotates, the spindle mounted on the spindle shaft 31, the case body 32, the disk table 33, the chucking member, and the disk table 33 together with the motor rotor 36. The disk 22 is rotated integrally, and the balance balls 43, 43,... Are also rotated around the rotation axis of the spindle shaft 31 in the moving space 32a. That is, a rotating member (motor rotor 36, spindle shaft 31) included in the spindle motor 23 and a rotating member (disk table 33, chucking member, recording disk 22, automatic alignment mechanism 7) rotated by the spindle motor 23 are combined and rotated. The body 39 is configured (hereinafter, the center of gravity of each of these members, that is, the center of gravity of the combined rotating body 39 is referred to as “combined center of gravity”).
[0040]
.. And the mechanical chassis 25 (including everything mounted on the mechanical chassis 25 such as the spindle motor 23 and the optical pickup device 24 (including the disk table 33 and the chucking member)). The vibration system 40 is configured. Such a vibration system 40 corresponds to the vibration system 13 described in the above embodiment.
[0041]
The elastic coefficients of the dampers 27, 27,... Are set so that the resonance frequency of the vibration system 40 is, for example, 75 Hz (4500 rpm) when the disk drive device 21 has a 12-times speed. The This is because the rotational speed range of the 12 × disk drive device 21 is about 3000 to 6000 rpm, and in the case of many disk drive devices at present, the information signal on the innermost circumference side is read immediately after the start of rotational drive. This is because, when the information signal on the innermost circumference is read, the maximum rotational speed (6000 rpm) is obtained, and therefore it is sufficient that the alignment operation is performed before the maximum rotational speed is reached.
[0042]
Note that the resonance frequency of the vibration system 40 may be made closer to the maximum rotational speed of 6000 rpm. In this way, the separation rotational speed set to a rotational speed slightly lower than the resonance frequency of the vibration system 40 can be set high, and the relative speed between the case body 32 and the balance balls 43, 43,. It becomes possible to realize the pull-in phenomenon at an early stage.
[0043]
The case body 32 is formed of, for example, a synthetic resin material, and is positioned in a state of being fixed to the spindle shaft 31 between the motor rotor 36 and the disk table 33. The case body 32 includes a housing portion 41 and a top plate portion 42 that covers the housing portion 41, and the central portion of the housing portion 41 is fixed to the spindle shaft 31 coaxially with the spindle shaft 31.
[0044]
An internal space (hereinafter referred to as “moving space”) 32a of the case body 32 has an annular shape, and, for example, six balance balls 43, 43 serving as balance members are provided in the moving space 32a. Are accommodated to constitute the automatic alignment mechanism 7.
[0045]
The balance spheres 43, 43,... Are formed in a spherical shape from a magnetic material such as iron or nickel, and are movable in the radial direction and the circumferential direction in the moving space 32a.
[0046]
A magnet (permanent magnet) 44 serving as a magnetic field generating means is disposed at the center in the moving space 32a. The magnet 44 has an annular shape, is magnetized in two poles in the thickness direction (a direction parallel to the rotation axis direction), and is provided on the inner peripheral wall of the housing portion 41 so as to be fitted onto the spindle shaft. 31 is arranged coaxially. When the spindle motor 23 is not rotating or is rotating at a low speed, the balance balls 43, 43,... Are attracted to the magnet 44 and are positioned on the inner peripheral side in the moving space 32a. As a result, the magnet 44 attracts the balance balls 43, 43,... Until it reaches a predetermined rotation speed (separation rotation speed), and functions as the balance member holding means 17.
[0047]
In addition, the balance balls 43, 43,... Are attracted to the magnet 44, and the adjacent ones are magnetized in the same direction and repel each other, so that the six balance balls 43, 43,.・ Are located at equal intervals in the circumferential direction. For this reason, there is no eccentric center of gravity due to the presence of the balance balls 43, 43,... There is nothing wrong.
[0048]
The upper and lower surfaces of the magnet 44 are attracted by an annular yoke 45, 45 having a slightly larger diameter than the magnet 44, so that the magnetic field of the magnet 44 is generated between one yoke 45 and the other yoke 45. It is mainly formed between the outer peripheries, and the magnetic force is concentrated, so that the attractive force increases and the magnetic force hardly reaches the outer peripheral portion of the case body 32.
[0049]
As a result, the yokes 45, 45 enhance the function of the magnet 44 as the balance member holding means, and also apply the magnetic force of the magnet 44 to the balance balls 43, 43,... Moved to the outer peripheral portion of the case body 32. Until the centrifugal force applied to the balance balls 43, 43... Is reduced, that is, until the rotation speed is low (return rotation speed), the balance balls 43, 43. It functions as a balance member return suppression means that suppresses returning.
[0050]
In this embodiment, the yokes 45, 45 are provided on the upper surface and the lower surface of the annular magnet 44, but the present invention is not limited to this and may be provided only on the upper surface or only the lower surface. In this embodiment, the yokes 45 and 45 having a diameter slightly larger than that of the magnet 44 are used. However, in this way, the magnetic flux can be concentrated between the outer peripheral edges of the yokes 45 and 45. It is possible to increase the attractive force of the magnet 44 and reduce the influence of the magnetic force on the outer peripheral portion of the case body 32. Further, the diameter of the yokes 45, 45 may be the same as that of the magnet 44. In such a case, the attractive force of the magnet 44 against the balance balls 43, 43,. Can be increased.
[0051]
Thus, by appropriately selecting the size of the yokes 45, 45, the attractive force of the magnet 44 against the balance spheres 43, 43... Can be set, and thus the balance spheres 43, 43,. ... Can be appropriately designed for the separation rotation speed for separating the magnet 44 from the magnet 44 and the return rotation speed for returning. Further, the attractive force of the magnet 44 is appropriately changed depending on the shape (diameter, thickness, etc.) of the yokes 45, 45, the magnetic force of the magnet 44 itself, the size of the balance balls 43, 43. can do. Therefore, by appropriately selecting the attracting force by the magnet 44 and / or the yokes 45, 45, in the disk drive device 21, when the rotational speed of the balance balls 43, 43,. The return rotation speed of the balance balls 43, 43,.
[0052]
Next, the movement of the balance balls 43, 43,... Of the automatic alignment mechanism 7 in the rotational drive mechanism 30 of the disk drive device 21 will be described with reference to FIGS. 10 and FIG. 11 show (acceleration center of gravity) acceleration (G) in the radial direction of the mechanical chassis 25 when the recording disk 22 having an unbalance amount of 1 g · cm is mounted on the disk drive device 21 and the rotational speed of the spindle motor 23 ( rpm).
[0053]
FIGS. 12 and 13 are graphs showing the relationship between the acceleration of the mechanical chassis and the rotation speed of the spindle motor in the rotary drive mechanism that does not have the yokes 45, 45, and are combined for the purpose of comparison with the present embodiment. I will explain.
[0054]
Further, this rotational drive mechanism 30 provided with the yokes 45, 45 has a separation rotational speed of the balancing balls 43, 43... Of the automatic alignment mechanism 7 to 4000 rpm, a return rotational speed to 1500 rpm, and a vibration system 40. The resonance frequency is set to 75 Hz (4500 rpm). In addition, the rotational drive mechanism without the yoke has a low balance rotational speed of the balance balls 43, 43,... As low as 3000 rpm, and the magnetic field extends strongly to the outer periphery of the case body. The return rotation speed of the balls 43, 43,... Is 2000 rpm.
[0055]
Thus, when the spindle motor 23 of the rotation drive mechanism 30 starts rotating (during rotation acceleration), there is almost no vibration up to about 1500 rpm, and the vibration gradually increases after exceeding 1500 rpm (see FIG. 10).
[0056]
In the rotation drive mechanism 30, when the spindle motor 23 reaches 4000 rpm, the balance balls 43, 43,. At the moment of separation, the rotation speed of the balance balls 43, 43,... Is almost the same as that of the magnet 44. However, the rotation of the balance balls 43, 43,. The number is delayed with respect to the number of rotations of the case body 32. That is, when the balance balls 43, 43,... Are detached, the balance balls 43, 43,.
[0057]
After that, the balance balls 43, 43,... Move in the radial direction and the circumferential direction in the moving space 32a, but become unclear, but due to frictional resistance between the inner bottom surface of the case body 32 and the inner surface of the outer peripheral wall, the spindle motor Since the rotational force of 23 is transmitted to the balance balls 43, 43,..., The relative speed between the case body 32 and the case body 32 is about 4500 rpm. Almost “0”. In this state, the balance balls 43, 43... Are positioned on the outer peripheral portion of the case body 32 and are pressed against the inner surface of the outer peripheral wall by centrifugal force.
[0058]
When the rotational speed is around 4500 rpm, resonance of the vibration system 40 occurs, and the balance spheres 43, 43,. Note that, in the vicinity of 4500 rpm, the vibration does not appear to be particularly large in FIG. 10, but this is because the balance spheres 43, 43,. Although the movement of the case body 32 and the movement of the balance spheres 43, 43,... Are in opposite phases, the balance spheres 43, 43,. Retraction occurs by moving in the direction opposite to the balance direction (see FIG. 7).
[0059]
When the pull-in phenomenon occurs at about 4500 rpm, a centering action is performed, whereby the vibration of the mechanical chassis 25 is reduced and the acceleration is about 0.5 G.
[0060]
As described above, when the recording disk 22 having an unbalance is rotated, the balance spheres 43, 43,... Located on the axis. Accordingly, the combined rotating body 39 rotates without vibration. Therefore, even when the recording disk 22 having unbalance is mounted, the combined center of gravity can be rotated with the combined center of gravity positioned on the rotation axis.
[0061]
Thereafter, even if the rotation speed of the spindle motor 23 increases, the vibration increases slightly, but does not increase greatly. The acceleration is 0.7 to 0 even at the maximum use speed of 6000 rpm in the use speed range. It is within 8G.
[0062]
When the recording disk 22 having no weight imbalance (eccentric center of gravity) is attached to the disk drive device 21, the vibration of the vibration system 40 is originally small, so that the balance balls 43, 43,. When the number is exceeded, the balance spheres 43, 43,... Are somewhat out of order in the moving space 32a, but since there is no unbalance from the beginning, the centering action is performed early, and the balance spheres 43, 43,. In the moving space 32a, as shown in FIG. 8 and FIG.
[0063]
On the other hand, in the rotary drive mechanism without the yokes 45, 45, a graph (FIG. 12) almost the same as that of the rotary drive mechanism 30 is drawn up to 3000 rpm, but the balance sphere is detached from the magnet at 3000 rpm. The balance ball is exposed in the case body. And when the balance ball is detached at a low rotation speed, the relative speed with the case body Almost It takes some time to reach “0”. Although it does not appear in this graph, in practice, the acceleration of rotation must be reduced (the gradient of the graph is made gentle).
[0064]
And even in such a rotational drive mechanism, the relative speed between the case body and the balance ball is just before 4500 rpm. Almost In the vicinity of 4500 rpm, resonance of the vibration system 40 occurs, causing the pulling phenomenon of the balance spheres 43, 43,... Further, at 6000 rpm, the vibration slightly increases as the number of rotations increases as in the case of the rotation drive mechanism 30.
[0065]
Next, the operation at the time of rotational deceleration in the rotary drive mechanism 30 according to the present embodiment will be described.
[0066]
When the rotation of the spindle motor 23 is decelerated from 6000 rpm, the vibration does not change greatly and gradually decreases, and the vibration is almost eliminated at around 3000 rpm. The reason for little vibration during the rotation deceleration is that once the alignment operation is executed, the balance balls 43, 43,... Are attracted to the magnet 44, that is, the return rotation in the automatic alignment mechanism 7 is performed. This is because the alignment state is maintained until the number reaches (see FIG. 11).
[0067]
When the rotational speed reaches 1500 rpm, the attractive force of the magnet 44 against the balance balls 43, 43,... Is superior to the centrifugal force, and the balance balls 43, 43,. Is done. In such a low rotation range, even if there is a slight eccentric gravity center, the vibration due to this is small, and even if the signal information of the recording disk 22 is read and written even in the rotation speed range of this range. There is no.
[0068]
As described above, in the disk drive device 21 having the automatic alignment mechanism 7 provided with the yokes 45, 45, the recording disk 22 having a weight imbalance in the use rotation speed range (3000 to 6000 rpm) is provided. Even if it is rotated, vibration does not occur in the synthetic rotating body 39 due to the automatic aligning action, and even with such a recording disk 22, information signals can be written or read satisfactorily on the signal recording surface.
[0069]
The above-described rotational speed range is a normal rotational speed range of the 12 × disk drive device 21. In such a high-speed disk drive device, a high-speed mode and a low-speed mode can be set. There is something that looks like this. For example, there is a disk drive device having a high speed mode of 12 × speed and a low speed mode of 4 × speed, and the rotation speed range is 3000 to 6000 rpm in the high speed mode and 1000 to 2000 rpm in the low speed mode. Yes. Further, this type of disk drive device can be used even at a single speed, and in this case, the rotation speed range is about 200 to 500 rpm.
[0070]
In the disk drive device 21 described above, the alignment state can be maintained up to 1500 rpm, and since the vibration is small even if the alignment state is canceled in the low-speed rotation region as described above, In all of the rotation speed ranges of 0 to 6000 rpm as well as the use rotation speed range at 4 × speed and 1 × speed, vibrations that impede reading and writing of the recording disk do not occur.
[0071]
On the other hand, in the rotational drive mechanism having no yoke, when decelerating from 6000 rpm, the balance sphere is attracted to the magnet at about 2000 rpm, thereby eliminating the alignment state and synthesizing. It can be seen that the unbalance of the rotating body vibrates the vibration system as it is, and the acceleration value of the mechanical chassis slightly increases at about 2000 rpm (see FIG. 13).
[0072]
As described above, in a rotational drive mechanism that does not have a yoke, the alignment state is quickly eliminated during rotation deceleration, and unexpected vibration occurs.
[0073]
In short, when the balance ball is detached and returned only by the magnetic force of the magnet, if the magnetic force of the magnet is increased, the separation rotational speed can be increased, but the return rotational speed is also increased, and the magnetic force of the magnet is reduced. If it is reduced, the return rotational speed can be lowered, but the separation rotational speed is also lowered.
[0074]
Therefore, when the yokes 45 and 45 are provided as in the above-described embodiment of the present invention, the attractive force can be increased without increasing the magnitude of the magnetic force of the magnet 44. When the magnet 44 having the same magnetic force is used, The separation rotational speed can be increased, and the magnetic flux is concentrated, so that the influence of the magnetic force on the surroundings can be reduced, and the return rotational speed can be decreased.
[0075]
In the above embodiment, since the separation rotational speed is set to 4000 rpm which is relatively close to the resonance frequency 4500 rpm of the vibration system 40, the rotational speed of the case body 32 and the balance balls 43, 43,. Speed can be quickly set to “0”.
[0076]
Further, in the above embodiment, by setting the resonance frequency of the vibration system 40 within the use rotation speed range (3000 to 6000 rpm) of the disk drive device 21, the resonance frequency higher than this resonance frequency is within the use rotation speed range. Therefore, if the rotational speed of the rotary drive mechanism 30 matches the higher order resonance frequency of the vibration system 40, a vibration with a large amplitude that would be generated does not occur, and a more stable rotation can be obtained.
[0077]
Thus, in order not to include the high-order resonance frequency of the vibration system in the use rotation speed range of the rotation drive mechanism, assuming that the maximum use rotation speed is R and the primary resonance frequency of the vibration system is fr. ,
R / 2 <fr <R
It is sufficient to have a relationship of
[0078]
For example, in the case of the 12 × speed disk drive device 21 according to the present embodiment, the primary resonance frequency of the vibration system 40 is set within a range of 50 Hz (3000 rpm) to 100 Hz (6000 rpm). By doing in this way, the secondary resonance frequency of the vibration system 40 is in the range of 100 Hz to 200 Hz, the secondary resonance frequency is not included in the use rotation speed region, and the amplitude due to the secondary resonance is within the use rotation speed region. Large vibration does not occur.
[0079]
Furthermore, the resonance frequency of the vibration system 40 in the rotary drive mechanism 30 according to the above embodiment is set to be larger than the maximum use rotation speed, and once the rotation of the spindle motor 23 is increased to the rotation speed exceeding the resonance frequency, After the automatic centering action is produced, the rotational drive mechanism 30 can be used in the operating rotational speed range by reducing the rotational speed.
[0080]
That is, in the rotational drive mechanism 30, the resonance frequency of the vibration system 40 is set to 116 Hz (7000 rpm), the rotation speed of the spindle motor 23 is set to 7000 rpm or more to cause a centering action, and then the rotation is reduced and used. It is used at 3000-6000 rpm which is several ranges.
[0081]
In this way, once the automatic centering action is generated, the rotation of the synthetic rotating body 39 can be stabilized by decelerating, and the balance member holding means as in the rotation driving mechanism 30 according to the above embodiment. In the disk drive device 21 provided with the balance member return restraining means 18 and the balance member return suppressing means 18, the alignment state can be maintained in a wide rotational speed range. Can be realized.
[0082]
FIG. 14 shows a second embodiment of the rotational drive mechanism of the present invention.
[0083]
The difference between the second embodiment and the first embodiment is that the balance member return suppressing means is not a yoke, but a magnet magnetizing method. Further, the description will be given only for the above-mentioned differences, and the other parts will be explained by attaching the same reference numerals to the same parts in the rotary drive mechanism according to the first embodiment to the respective parts of the drawings. Is omitted.
[0084]
FIG. 14 shows a horizontal cross section of the automatic alignment mechanism 7A of the rotary drive mechanism 30A according to the second embodiment, and a magnet 46 magnetized in the circumferential direction at the center in the case body 32. Is arranged.
[0085]
The magnet 46 magnetized in the circumferential direction in this way is magnetized to 12 poles in the circumferential direction, and a magnetic field generated between the respective poles is generated between the poles adjacent in the circumferential direction. For this reason, the magnetic field generated here is narrower than that magnetized in the thickness direction of the magnet, and the magnetic force reaching the outer periphery of the case body 32 is reduced.
[0086]
Accordingly, the magnet 46 itself functions as the balance member holding means 17 and the balance member return suppressing means 18.
[0087]
Further, the influence of the magnet 46 on the outer peripheral portion of the case body 32 depends on the circumferential length of the outer peripheral surface of each multipolar magnetized pole, so the number of magnets 46 in the circumferential direction is increased. By shortening the circumferential length of the outer peripheral surface of each pole, the influence of the magnetic force on the outer peripheral portion can be reduced, and therefore the function as the balance member return suppressing means 18 can be increased.
[0088]
In each of the above-described embodiments, yokes 45 and 45 are used as the balance member return control means, or the magnet magnetization method as the balance member holding means is devised. The mechanism is not limited to this, and for example, a ring-shaped magnet may be provided on the outer periphery of the case body. In such a case, the magnetic force of the magnet as the balancing member control means may be weakened.
[0089]
Further, in each of the above-described embodiments, an example in which the automatic alignment operation is performed on the synthetic rotator 39 when the recording disk 22 having unbalance is mounted on the disc table has been described. Even when the members other than the recording disk 22 are unbalanced, the rotation driving mechanism 30 can execute the automatic alignment action to suppress vibration during rotation.
[0090]
Further, in each of the above-described embodiments, the rotation drive mechanism according to the present invention is applied to the rotation drive mechanism 30 of the disk drive device 21. However, the rotation drive mechanism according to the present invention is an industrial machine, It can also be applied to those provided in other electrical appliances.
[0091]
【The invention's effect】
As is apparent from the above description, according to the invention according to claim 1, in the rotational drive mechanism including the automatic alignment mechanism, the balance member is attached to the case body until the predetermined rotational speed is reached during the rotation acceleration. The balance member holding means that holds the central portion and the balance member that has been moved to the outer peripheral portion at a speed equal to or higher than the predetermined rotational speed are reduced until the rotational speed is lower than the predetermined rotational speed when the rotational speed is reduced. Since the balance member return suppression means is provided so that it does not return to the center, even if there is an eccentric center of gravity in the composite rotator, the composite rotator can be rotated in an aligned state, and the balance Since the member holding means is provided, the relative speed between the rotation of the balance member and the rotation of the case body is increased in order to release the balance member after high-speed rotation. Almost “0” is achieved, and the alignment operation is performed quickly, and the balance member return suppression means is provided, so that the alignment state can be maintained up to the low-speed rotation, and the use rotation speed range of the rotation drive mechanism is expanded. can do.
[0092]
According to the second aspect of the present invention, the balance member is formed of a magnetic material, and an annular magnet magnetized in the axial direction is disposed at the center of the case body to constitute the balance member holding means. At the same time, an annular yoke is provided on at least one end face in the axial direction of the magnet so that the balance member moved to the outer peripheral portion is less likely to receive the magnetic force of the balance member holding means, and the balance member is rotated until it rotates at low speed. Since the balance member return suppressing means is configured so as not to return to the center, the balance member holding means and the balance member return suppressing means can be configured with a simple structure, and the function of the balance member holding means Can be strengthened.
[0093]
According to the third aspect of the present invention, the balance member is formed of a magnetic material, and an annular magnet that is multipolarly magnetized in the circumferential direction is disposed at the center of the case body, and the balance member holding means is provided. When the magnet as the balance member holding means is multipolarly magnetized in the circumferential direction, the magnetic force of the balance member holding means is less likely to be exerted on the balance member moved to the outer peripheral portion, and at low speed rotation Since the balance member functions as a balance member return suppressing means that prevents the balance member from returning to the center, the balance member holding means and the balance member return suppressing means can be configured with a simple structure.
[0094]
It should be noted that the specific shapes and structures of the respective parts shown in each of the above-described embodiments are merely examples of implementation in carrying out the present invention, and as a result, the technical scope of the present invention. Should not be interpreted in a limited way.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram for explaining the principle of an automatic alignment mechanism used in a rotary drive mechanism according to the present invention.
2 conceptually shows the basic configuration of the rotational drive mechanism according to the present invention together with FIG. 3, and this figure is a schematic side view of the whole. FIG.
FIG. 3 is a schematic longitudinal sectional view conceptually showing the basic structure of an automatic alignment mechanism.
4 shows a first embodiment of the rotational drive mechanism of the present invention together with FIGS. 5 to 9, and FIG. 4 is a perspective view schematically showing a disk drive device using the rotational drive mechanism according to the present invention. FIG.
FIG. 5 is an enlarged longitudinal sectional view showing a synthetic rotating body.
FIG. 6 is an enlarged horizontal sectional view showing a state where a balance sphere is attracted to a magnet.
FIG. 7 is an enlarged horizontal cross-sectional view of the case body showing a state in which the automatic alignment action is performed.
FIG. 8 is an enlarged horizontal sectional view showing a state in which the balance sphere has been moved to the outer periphery of the case body.
FIG. 9 is an enlarged vertical sectional view showing a state where the case body is rotated.
FIG. 10 together with FIG. 11 represents the relationship between the acceleration of the mechanical chassis and the rotational speed in the rotational drive mechanism of the present invention, and this figure is a graph at the time of rotational acceleration.
FIG. 11 is a graph at the time of rotational deceleration.
FIG. 12 shows the relationship between the acceleration of the mechanical chassis and the rotation speed in the rotation drive mechanism when there is no yoke together with FIG. 13, and this figure is a graph at the time of rotation acceleration.
FIG. 13 is a graph at the time of rotational deceleration.
FIG. 14 is an enlarged horizontal sectional view of an essential part showing a second embodiment of the rotational drive mechanism of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 6 ... Rotation drive mechanism, 7 ... Automatic centering mechanism, 8 ... Rotation drive means, 9 ... Support shaft, 14 ... Moving space, 15 ... Case body, 16 ... Balance member, 17 ... Balance member holding means, 18 ... Balance member Return restraining means, 19: Synthetic rotating body, 23: Spindle motor, 30 ... Rotation drive mechanism, 31 ... Spindle shaft, 32 ... Case body, 32a ... Moving space, 39 ... Synthetic rotating body, 43 ... Balance ball, 44 ... Magnet 45 ... Yoke, 7A ... Automatic alignment mechanism, 30A ... Rotation drive mechanism, 46 ... Magnet

Claims (3)

The center of gravity (hereinafter referred to as “synthetic center of gravity”) of the rotating member rotated by the rotation driving means and the rotating members included in the rotation driving means (hereinafter, these rotating members are collectively referred to as “synthetic rotating body”). ) Is a rotary drive mechanism equipped with an automatic alignment mechanism that automatically positions on the rotation axis during rotation,
The automatic centering mechanism is rotated by a rotation drive means via a support shaft, and a case body having a moving space in which a cross-sectional shape in a direction perpendicular to the axial direction forms an annular shape, and can move within the moving space of the case body And the balance member is moved relative to the other parts of the synthetic rotating body along with the rotation of the rotation driving means, so that the composite center of gravity of the synthetic rotating body is on the rotation axis. As well as
During rotation acceleration, the balance member holding means for holding the balance member at the center of the case body until the predetermined number of rotations is reached, and the balance member that has been moved to the outer peripheral part at the above-mentioned predetermined number of rotations or more during rotation deceleration. And a balance member return suppressing means for preventing the case from returning to the center of the case body until the rotational speed is lower than the predetermined rotational speed. In the rotary drive mechanism according to claim 1,
The balance member is made of a magnetic material,
An annular magnet magnetized in the axial direction is arranged at the center of the case body to constitute a balance member holding means,
An annular yoke is provided on at least one end surface of the magnet in the axial direction so that the magnetic force of the balance member holding means is not easily applied to the balance member moved to the outer peripheral portion, and the balance member is centered until the low speed rotation is reached. A rotation drive mechanism characterized in that the balance member return suppressing means is configured so as not to return to the section. In the rotary drive mechanism according to claim 1,
The balance member is made of a magnetic material,
In the center of the case body, an annular magnet magnetized in the circumferential direction is arranged to constitute a balance member holding means,
When the magnet as the balance member holding means is multipolarly magnetized in the circumferential direction, the balance member does not reach the balance member moved to the outer peripheral portion so that the magnetic force of the balance member holding means does not reach even at low speed rotation. A rotation drive mechanism characterized by functioning as a balance member return restraining means that prevents return to the center.

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