JP4580467B1 - Disk drive - Google Patents

Abstract

The disk drive device includes a hub configured to mount a recording disk, and the natural frequency at the time of non-rotation of secondary rocking mode resonance in a state where the recording disk is mounted on the hub is F0 (Hz). When the rotational speed of the hub is N (Hz), the radial dimension of the hub extension is such that the natural frequency F0 satisfies F0> N · (3 · P + 2). It is smaller than the axial dimension.
[Selection] Figure 2

Description

  The present invention relates to a disk drive device that rotationally drives a recording disk.

  A hard disk drive is known as a storage medium used for a computer storage device or the like. Hard disk drives have drastically improved rotational accuracy, and accordingly higher density and larger capacity are required (see, for example, Patent Document 1).

  In a hard disk drive, a recording disk on which recording tracks are formed is rotated at a high speed by a brushless motor. In order to record / reproduce magnetic data contained in the recording track, a recording / reproducing head is disposed with a small gap with respect to the surface of the recording disk.

JP 2007-198555 A

  Here, as one method for increasing the capacity of the hard disk drive, there is a method in which the width of the recording track is reduced and the arrangement of the recording / reproducing head is brought closer to the surface of the recording disk. The vibration due to the torque ripple of the brushless motor and the secondary rocking mode resonance may increase, and if the width of the recording track is narrowed, the recording / reproducing head may be vibrated by the vibration and the trace of the recording track may be disturbed. is there.

  Further, when the gap between the recording / reproducing head and the surface of the recording disk is made narrower, the gap changes greatly due to a slight vibration of the recording / reproducing head, and the amplitude of the output signal of the recording / reproducing head changes greatly. If the trace of the recording track is disturbed or the amplitude of the output signal of the recording / reproducing head changes, the frequency of malfunction at the time of recording / reproducing data of the hard disk drive can be increased.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a disk drive device that reduces vibrations that occur during driving.

  In order to solve the above-described problems, a disk drive device according to an aspect of the present invention includes a base member, a hub configured to mount a recording disk, and a hub that is rotatable relative to the base member. A three-phase coil formed so as to be wound around the plurality of salient poles, a bearing unit to be supported, a core fixed to the base member and including a ring portion and a plurality of salient poles extending radially from the ring portion And a yoke fixed to the hub, fixed to the inner periphery of the yoke, opposed to a plurality of salient poles in the radial direction, and subjected to drive magnetization of the P pole (P is an even number of 2 or more) in the circumferential direction. And a magnet. The hub is fitted with the central hole of the recording disk and extends in the axial direction. The hub is connected to the first outer cylinder and extends outward in the radial direction. A seating surface to be seated; a second outer cylinder portion extending in the axial direction and continuously provided on the seating surface; and an extension portion extending continuously outward in the radial direction and continuous with the second outer cylinder portion Have. In this disk drive device, when the natural frequency at the time of non-rotation of the secondary rocking mode resonance in the state where the recording disk is placed on the hub is F0 (Hz) and the use rotation speed of the hub is N (Hz), The radial dimension of the outer extension is formed smaller than the axial dimension of the second outer cylinder so that the natural frequency F0 satisfies F0> N · (3 · P + 2).

  According to this aspect, it is possible to reduce the vibration generated when the torque ripple frequency matches the natural frequency of the secondary rocking mode resonance.

  Another embodiment of the present invention is also a disk drive device. The apparatus includes a base member, a hub configured to mount a recording disk, a bearing unit that supports the hub so as to be rotatable relative to the base member, and an annular portion fixed to the base member. And a core including a plurality of salient poles extending in a radial direction from the annular portion, a three-phase coil formed so as to be wound around the plurality of salient poles, a yoke fixed to the hub, and an inner periphery of the yoke A fixed magnet that is opposed to a plurality of salient poles in the radial direction and is magnetized for driving with a P pole (P is an even number of 2 or more) in the circumferential direction. In this disk drive device, the natural frequency at the time of non-rotation of the secondary rocking mode resonance in the state where the recording disk is mounted on the hub is F0 (Hz), the use rotation speed of the hub is N (Hz) and the use rotation speed. When the rotation speed M (Hz) is larger than N, the natural frequency F0 is configured to satisfy N · (3 · P + 2) <F0 <M · (3 · P-2).

  According to this aspect, even when used at different rotational speeds, it is possible to reduce vibrations that occur when the torque ripple frequency matches the natural frequency of the secondary rocking mode resonance.

  Note that any combination of the above-described constituent elements, and those obtained by replacing the constituent elements and expressions of the present invention with each other among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to reduce vibrations that occur when the disk drive device is driven.

1 is a top view showing a disk drive device according to an embodiment. It is a figure which shows sectional drawing of the disk drive device which concerns on embodiment.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings. The same or equivalent components and members shown in the drawings are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. In the drawings, some of the members are omitted from the description of the embodiments.

  The disk drive device according to the embodiment is suitably used for a hard disk drive that mounts a recording disk and rotates. The disk drive device may be a device for driving a recording disk, for example, a brushless motor.

  FIG. 1 is a top view showing a disk drive device 100 according to the embodiment. FIG. 1 shows a state in which a top cover (not shown) is removed to show the internal configuration of the disk drive device 100. The disk drive device 100 includes a base member 50, a recording disk 200, a hub 10 on which the recording disk 200 is placed, a data read / write unit 8, and a top cover.

  The recording disk 200 is placed on the hub 10 and rotates as the hub 10 rotates. The base member 50 is formed by molding an aluminum alloy by die casting. The base member 50 rotatably supports the hub 10 via a bearing.

  The data read / write unit 8 includes a recording / reproducing head 8a, a swing arm 8b, a pivot assembly 8c, and a voice coil motor 8d. The recording / reproducing head 8 a is attached to the tip of the swing arm 8 b, approaches the upper or lower surface of the recording disk 200, records data on the recording disk 200, and reads data from the recording disk 200. By using both sides of the recording disk 200, the recording capacity of the recording disk 200 can be increased.

  The pivot assembly 8c supports the swing arm 8b in a swingable manner with respect to the base member 50 with the center of the pivot assembly 8c as a rotation axis. The voice coil motor 8d functions as a drive unit for the data read / write unit 8, swings the swing arm 8b, and moves the recording / reproducing head 8a to a desired position on the recording surface of the recording disk 200. The data read / write unit 8 may be configured using a known technique for controlling the position of the head.

  FIG. 2 is a sectional view of the disk drive device 100 according to the embodiment. 2 is a cross-sectional view taken along line AA in FIG. The disk drive device 100 mounts two 3.5-inch type recording disks 200 having a diameter of 95 mm, and rotates the recording disks 200. The diameter of each central hole of the two recording disks 200 assumed is 25 mm and the thickness is 1.50 mm.

  The disk drive device 100 includes a shaft 20, a flange 22, a yoke 30, a magnet 40, a laminated core 60, a coil 70, a sleeve 80, a plate 90, a lubricant, and a damping ring 110. Further prepare.

  The hub 10 is formed in a circular shape around the motor rotation axis R, and the outer shape is formed in a convex shape. The inner shape of the hub 10 is formed so as to surround the bearing. The hub 10 has a first outer cylinder portion 10b extending in the axial direction of the bearing unit to hold the recording disk 200, and a diameter that is connected to the first outer cylinder portion 10b to seat the recording disk. And a seating surface 10c extending outward in the direction. The center holes of the two recording disks 200 are fitted into the first outer cylinder portion 10b. The diameter of the first outer cylinder portion 10b is 25 mm. More precisely, the diameter of the first outer cylinder portion 10b is 24.978 ± 0.01 mm.

  On the seating surface 10 c of the hub 10, a protruding portion 13 protruding upward is formed for seating the lower recording disk of the two recording disks 200. The raised portion 13 is formed in an annular shape around the motor rotation axis R, and the surface of the raised portion 13 where the recording disk is seated is a smooth curved surface. The cross section of the curved surface is an arc shape, and the recording disk 200 is in linear contact with the seating surface 10c.

  The annular first spacer 202 is inserted between the two recording disks 200. The clamper 206 presses and fixes the two recording disks 200 and the first spacer 202 against the hub 10 via the annular second spacer 204. The clamper 206 is fixed to the upper surface 10 a of the hub 10 by a plurality of clamp screws 208.

  The hub 10 is formed with an annular recess 10g that is recessed radially inward in the outer periphery of the seating surface 10c in order to ensure a movable range of the recording / reproducing head 8a so as not to hinder the movement of the recording / reproducing head 8a. The movable range of the recording / reproducing head 8a refers to a space in which the recording / reproducing head 8a operates when data on the recording disk 200 is recorded / reproduced. The annular recess 10g includes a second outer cylinder portion 10d that is provided continuously with the seating surface 10c and extends in the axial direction, and an extension portion that is provided continuously with the second outer cylinder portion 10d and extends radially outward. 10e. Further, the hub 10 has an annular wall portion 10f that is connected to the outer extending portion 10e and extends in the axial direction.

  The yoke 30 is formed of a magnetic material such as iron in a ring shape, and its cross section is an inverted L shape. The yoke 30 is fixed to the inner peripheral surface of the annular wall portion 10f by using both adhesion and press fitting. On the inner peripheral surface of the annular wall portion 10f, a convex portion 16 is formed to which the yoke 30 is pressed when the yoke 30 is press-fitted. The convex portion 16 is formed in an annular shape and is arranged with the motor rotation axis R as an axis. An adhesive is filled between the inner peripheral surface of the annular wall portion 10 f and the outer peripheral surface of the yoke 30. This is realized by applying an appropriate amount of adhesive to the inner peripheral surface of the annular wall portion 10f when the yoke 30 is press-fitted into the hub 10.

  A magnet 40 is bonded and fixed to the inner peripheral surface of the yoke 30. That is, the magnet 40 is fixed to the hub 10 via the yoke 30. The magnet 40 is made of a rare earth material such as neodymium, iron, or boron, and faces the salient poles of the laminated core 60 in the radial direction. Magnet 40 is magnetized for driving with a P pole (P is an even number of 2 or more) in the circumferential direction.

  For example, the hub 10 is made of an aluminum alloy, and the shaft 20 is made of a stainless material called SUS420J2. When the hub 10 and the shaft 20 are formed of this material, the linear expansion coefficient of the hub 10 is larger than the linear expansion coefficient of the shaft 20. One end of the shaft 20 is fixed to an opening 10 h provided at the center of the hub 10 by an interference fit. A flange 22 is fixed to the other end of the shaft 20 by an interference fit. Note that an adhesive may be used in combination for these interference fittings.

  At the center of the base member 50, a protrusion 52 having the motor rotation axis R as the central axis is provided. The outer peripheral surface 52a of the protrusion 52 is a cylindrical side surface. The inner peripheral surface 52b of the protruding portion 52 forms a through hole, and the sleeve 80 is bonded and fixed. The sleeve 80 interpolates the shaft 20. A plate 90 is bonded and fixed to the open end of the sleeve 80 on the flange 22 side.

  Lubricant is injected into the gap formed by the shaft 20 and the flange 22, the sleeve 80 and the plate 90. The shaft 20, the flange 22, the lubricant, the sleeve 80, and the plate 90 constitute a bearing for rotatably supporting the hub 10.

  On the inner peripheral surface of the sleeve 80, a pair of herringbone-shaped radial dynamic pressure grooves 82 spaced apart in the vertical direction are formed. A herringbone-shaped first thrust dynamic pressure groove 24 is formed on the upper surface of the flange 22, and a herringbone-shaped second thrust dynamic pressure groove 26 is formed on the lower surface of the flange 22. When the disk drive device 100 is driven, the hub 10 and the shaft 20 are supported in the radial direction and the axial direction by the dynamic pressure generated in the lubricant by the dynamic pressure grooves.

  On the open end side of the sleeve 80, a capillary seal portion 98 is formed, which is a portion where the gap between the inner peripheral surface of the sleeve 80 and the outer peripheral surface of the shaft 20 gradually widens upward. The capillary seal portion 98 prevents the lubricant from leaking out by a capillary phenomenon.

  The laminated core 60 has an annular portion and nine salient poles extending radially outward from the annular portion. The laminated core 60 is formed by laminating eight non-oriented electrical steel sheets having a thickness of 0.35 mm and integrating them by caulking. As a method of manufacturing the laminated core 60, first, an electromagnetic steel sheet having a surface subjected to insulation treatment is pressed and punched into a desired shape while forming a half punch. The eight magnetic steel sheets that have been pressed are integrated by caulking by in-mold caulking using a half punch. After this integration, the laminated core 60 is subjected to a surface treatment in order to prevent surface peeling and the like. Various methods can be employed for this surface treatment. For example, a method of attaching an epoxy resin by a method such as spray coating or cationic electrodeposition is advantageous in that a uniform coating film can be formed.

  A coil 70 is wound around each salient pole of the laminated core 60. When a three-phase substantially sinusoidal drive current flows through the coil 70, a drive magnetic flux is generated along the salient poles.

  The damping ring 110 is a cylindrical member formed of a softer material than the electromagnetic steel plate of the laminated core 60, for example, aluminum that is light and easy to process. The damping ring 110 is provided by being press-fitted between the annular portion of the laminated core 60 and the protruding portion 52, and suppresses vibration of the laminated core 60.

  The operation of the disk drive device 100 configured as described above will be described. In order to rotate the recording disk 200, a three-phase drive current is supplied to the coil 70. When the driving current is supplied, the coil 70 forms a driving magnetic flux along each salient pole. Torque is applied to the magnet 40 by this driving magnetic flux, and the rotors such as the hub 10 and the shaft 20 rotate.

  Hereinafter, torque ripple and resonance in the disk drive device 100 according to the embodiment will be described. It is assumed that two recording disks are placed on the disk drive device 100.

First, torque ripple is considered. In the disk drive device 100, drive torque is generated by the interaction between the magnetic flux formed by the coil 70 and the magnetic pole of the magnet 40. The torque ripple is a pulsation component included in the drive torque, and the fundamental frequency of the torque ripple (hereinafter referred to as torque ripple center frequency) is the rotational speed N (Hz) per second of the disk drive device 100 and the magnet. It is proportional to the number of magnetic poles of 40 and is theoretically expressed by the following formula 1.
3 · P · N (Hz) (Formula 1)
In reality, since the driving torque acting on the rotor is not uniform throughout the rotation of the rotor, the torque ripple is modulated at a frequency equal to the rotational speed N (Hz). Therefore, the torque ripple includes a sideband component having a frequency represented by the following formula 2.
3 · P · N ± N = (3 · P ± 1) · N (Hz) (Formula 2)
Thereafter, the torque ripple includes a torque ripple center frequency 3 · P · N and two sideband components (3 · P ± 1) · N. When these three frequencies are not particularly distinguished, they are simply called torque ripple frequencies.

  Next, resonance is considered. In the disk drive device 100 on which the recording disk 200 is placed, resonance in the secondary rocking mode can occur with respect to the recording disk 200. The natural frequency of the secondary rocking mode resonance when the disk drive device 100 is not rotating is assumed to be F0 (hereinafter referred to as the natural frequency F0).

  The inventor has confirmed that when the recording disk 200 rotates, the natural frequency F0 of the secondary rocking mode resonance splits in the rotation direction and the counter-rotation direction due to the gyro effect as the rotation speed N (Hz) increases. Specifically, when the recording disk rotates at the rotation speed N (Hz), the split amount becomes ± N (Hz), and the two split frequencies Fs of the secondary rocking mode resonance are F0 ± N (Hz). It becomes. Therefore, the present inventor considered the two split frequencies Fs when using the second-order rocking mode resonance.

  When one of the three torque ripple frequencies described above matches one of the two split frequencies of the secondary rocking mode resonance, a large vibration is generated in the recording disk 200 due to the resonance. This vibration can cause a disturbance in the trace of the recording track and aggravate the frequency of malfunction at the time of data recording / reproduction, and can be an obstacle to increasing the density and capacity of a hard disk using the disk drive device 100.

Here, when the rotation speed N (Hz) of the disk drive device 100 is determined, the present inventor employs the disk drive device 100 according to the embodiment, so that the natural frequency F0 of the secondary rocking mode resonance is as follows. It has been found that the disk drive device 100 that satisfies the condition of Equation 3 can be realized.
F0> (3 · P + 2) · N (Hz) (Formula 3)
In the state where Equation 3 is satisfied, the lower of the two split frequencies can be higher than the highest frequency in the torque ripple frequency. Therefore, it is possible to avoid the torque ripple frequency and the split frequency from matching, and to reduce the vibration generated in the disk drive device 100.

Note that the frequency may change due to a change in temperature, a change with time, a variation in component accuracy, a variation in manufacturing, or the like, and there is a possibility that Equation 3 may not be satisfied. In order to cope with this, it is possible to satisfy the condition of the following expression 4 in consideration of a margin.
F0> N · (3 · P + 3) (Hz) (Formula 4)
Thereby, even when there is a fluctuation such as a temperature change, the vibration generated in the disk drive device 100 can be reduced.

  The inventor conducted the following experiment in order to determine the conditions for the disk drive device 100 according to the embodiment to satisfy Expression 3. First, the disk drive device 100 mounts two 3.5-inch recording disks 200 having a diameter of 95 (mm). The recording disk 200 has a central hole diameter of 25 (mm) and a thickness of 1.50 (mm). The magnet 40 has drive magnetization of P = 8 poles in the circumferential direction. The rotational speed of the disk drive device 100 is set to a rotational speed N = 90 (Hz) (corresponding to 5400 r / m). According to this condition, the natural frequency F0 that satisfies Expression 3 only needs to be larger than 2340 (Hz).

Hereinafter, the natural frequency F0 was confirmed by experiment. In addition, the unit of length shown below is mm.
[1] Axial dimension Ld = 1.65 of first experimental outer cylinder portion 10d
Diameter D1 of the first outer cylinder portion = 25.0
Diameter D2 of the second outer cylinder portion = 30.2
Annular wall diameter D3 = 33.9
Radial dimension Le of the extended part 10e Le = (33.9-30.2) /2=1.85
As described above, when the radial dimension Le of the extending part 10e of the hub 10 is longer than the axial dimension Ld of the second outer cylinder part 10d, the natural frequency F0 = 2330 Hz is obtained.

[2] Axial dimension Ld = 1.65 of second experimental outer cylinder portion 10d
Diameter D1 of the first outer cylinder portion = 25.0
Diameter D2 of the second outer cylinder portion = 30.6
Annular wall diameter D3 = 33.9
Radial dimension Le = (33.9-30.6) /2=1.65 of the extended portion 10e
As described above, when the radial dimension Le of the extending part 10e of the hub 10 and the axial dimension Ld of the second outer cylinder part 10d are equal, the natural frequency F0 = 2340 Hz is obtained.

[3] Axial dimension Ld = 1.65 of third experiment outer cylinder portion 10d
Diameter D1 of the first outer cylinder portion = 25.0
Diameter D2 of the second outer cylinder portion = 31.9
Annular wall diameter D3 = 33.9
Radial dimension Le of the extended portion 10e Le = (33.9-31.9) /2=1.00
As described above, when the radial dimension Le of the extending part 10e of the hub 10 is shorter than the axial dimension Ld of the second outer cylinder part 10d, the natural frequency F0 = 2380 Hz was obtained.

[4] Axial dimension Ld = 1.65 of the fourth experiment outer cylinder portion 10d
Diameter D1 of the first outer cylinder portion = 25.0
Diameter D2 of the second outer cylinder portion = 32.6
Annular wall diameter D3 = 33.9
The radial dimension Le = (33.9−32.6) /2=0.65 of the extended portion 10e
Thus, when compared with the third experiment, the natural frequency F0 = 2400 Hz was obtained when the radial dimension Le of the outer extension 10e of the hub 10 was made shorter than the axial dimension Ld of the second outer cylinder 10d. .

[5] Axial dimension Ld = 1.65 of the fifth experimental outer cylinder 10d
Diameter D1 of the first outer cylinder portion = 25.0
Diameter D2 of second outer cylinder portion = 33.2
Annular wall diameter D3 = 33.9
The radial dimension Le = (33.9-33.2) /2=0.35 of the extended portion 10e.
Thus, in comparison with the fourth experiment, the natural frequency F0 = 2420 Hz was obtained when the radial dimension Le of the outer extension 10e of the hub 10 was made shorter than the axial dimension Ld of the second outer cylinder 10d. .

  Examining the first to fifth experiments, it has been found that the natural frequency F0 tends to decrease when the radial dimension of the outer extension 10e is lengthened and increases when the radial dimension is shortened. Here, when the natural frequency F0 is larger than 2340 (Hz), Expression 3 is satisfied.

  In the case of Le> Ld in the first experiment, the natural frequency F0 = 2330 (Hz) is satisfied and Expression 3 is not satisfied. When Le = Ld in the second experiment, the natural frequency F0 = 2340 Hz, which does not satisfy Equation 3. When Le = 1.00 and Le <Ld in the third experiment, the natural frequency F0 = 2380 Hz is satisfied, and Expression 3 is satisfied. In the case of Le = 0.65 and Le <Ld in the fourth experiment, the natural frequency F0 = 2400 Hz, and Expression 3 is satisfied. In the case of Le = 0.35 and Le <Ld in the fifth experiment, the natural frequency F0 = 2420 Hz and Expression 3 is satisfied. Therefore, it can be seen that if the radial dimension of the outer extending part 10e of the hub 10 is formed shorter than the axial dimension of the second outer cylinder part 10d, the disk drive device 100 that satisfies Expression 3 can be obtained.

  Here, if the radial dimension Le of the extended portion 10e is reduced without changing the sizes of the yoke 30 and the magnet 40, the diameter D2 of the second outer cylindrical portion 10d is increased. When the diameter D2 of the second outer cylinder portion 10d is increased, the movable range of the recording / reproducing head 8a is limited, so that data cannot be read from or written to a portion near the central hole of the recording disk 200. There is.

  Therefore, when the radial dimension of the outer extension 10e is made smaller than the axial dimension of the second outer cylinder 10d by increasing the diameter of the second outer cylinder 10d, the second outer cylinder 10d is The movable range of the recording / reproducing head 8a is secured in the radial direction. For example, the diameter D2 of the second outer cylinder portion 10d is configured to form a gap with respect to the outermost periphery of the movable range of the recording / reproducing head 8a. From the experience as a person skilled in the art, it is known that there is a maximum of 0.1 mm in the dimensional error and mounting error of the member in such a gap. For this reason, the diameter D2 of the second outer cylinder portion may be a dimension that ensures a gap of 0.1 mm or more with respect to a predetermined movable range of the recording / reproducing head 8a. That is, the distance between the motor rotation axis R and the rotation axis of the pivot assembly 8c is determined by adding the diameter D2 of the second outer cylinder portion 10d and the length from the rotation axis of the pivot assembly 8c to the tip of the recording / reproducing head 8a. It is comprised so that it may become 0.1 mm or more larger than the measured distance. Thereby, even if individual differences occur in the manufacturing process, the recording / reproducing head 8a can be prevented from coming into contact with the second outer cylinder portion 10d. From the viewpoint of miniaturization of the disk drive device 100, the distance between the motor rotation shaft R and the rotation shaft of the pivot assembly 8c is preferably as small as possible.

  From the above examination results, as shown in the third experiment, when the diameter D2 of the second outer cylinder portion 10d is formed to be larger than 31.9 mm, the natural frequency F0 satisfies Expression 3, and the disk drive device 100 Can reduce the vibration generated. In the embodiment, when the diameter of the outermost periphery of the movable range of the recording / reproducing head 8a is 33.1 mm, the disk drive device 100 can be downsized if the diameter D2 of the second outer cylinder portion 10d is 33 mm or less. On the other hand, the movable range of the outermost periphery of the recording / reproducing head 8a can be secured.

  When the recording disk 200 is a magnetic recording medium, the leakage magnetic flux generated from the magnetic pole of the magnet 40 acts on the recording / reproducing head 8a and is superimposed as a noise signal on the output signal of the recording / reproducing head 8a. There is a possibility of increasing the frequency of malfunctions. For this reason, the magnet 40 is provided radially inward from the portion of the seating surface 10c that contacts the recording disk 200 so as not to overlap the portion of the seating surface 10c that contacts the recording disk 200 in the axial direction.

  If the recording / reproducing head 8a is too close to the magnet 40 in the radial direction, the leakage magnetic flux acts on the recording / reproducing head 8a and is superimposed on the output signal of the recording / reproducing head 8a as a noise signal, thereby causing a malfunction frequency during recording / reproducing. There is a possibility to increase. Therefore, the second outer cylindrical portion 10d is positioned closer to the outer peripheral surface of the yoke 30 than the outer peripheral surface of the magnet 40 in the radial direction so that the movable range of the recording / reproducing head 8a does not overlap with the magnet 40 in the radial direction. Provided.

  As the diameter D2 of the second outer cylinder portion 10d is increased, the movable range of the recording / reproducing head 8a is limited. Therefore, the diameter D2 of the second outer cylinder portion 10d is, for example, the same as the outer peripheral surface of the yoke 30 You may comprise in a magnitude | size. Thereby, it is possible to reduce the influence of the leakage magnetic flux while ensuring the movable range of the recording / reproducing head 8a. The same diameter includes the case where the difference between the diameters is within 0.1 mm.

  If the center of the second outer cylinder portion 10d is deviated from the center of the first outer cylinder portion 10b, the second outer cylinder portion 10d is shaken in the radial direction when the hub 10 is rotated. If this radial deflection increases, the recording / reproducing head 8a may come into contact with the second outer cylinder portion 10d. For this reason, the second outer cylinder portion 10d may be configured to be processed continuously with the processing of the first outer cylinder portion 10b so as to be concentric with the first outer cylinder portion 10b. For example, while rotating the hub 10, the first outer cylinder portion 10b, the second outer cylinder portion 10d, and the inner peripheral portion directly supported by the bearing unit of the hub 10 are continuously along the rotation axis. And cut to make it flat. As a result, when the hub 10 rotates, the radial runout of the second outer cylinder portion 10d can be set to a predetermined reference value or less. The concentricity includes the case where the distance between the centers is within 0.1 mm.

  In the production process of the disk drive device 100, the disk drive device 100 may accidentally collide with production facilities. At this time, the outer peripheral end of the seating surface 10c of the hub 10 may be deformed. When the outer peripheral end of the seating surface 10c is deformed, there is a problem that the recording disk 200 can be placed inclined.

  In response to this problem, the outer peripheral end of the seating surface 10c is disposed on the radially inner side of the circumscribed conical surface 500 that circumscribes the outer shape of the hub 10 so as to prevent deformation of the outer peripheral end of the seating surface 10c. Constitute. In FIG. 2, the circumscribed conical surface 500 circumscribes the outer shape of the hub 10 and decreases in diameter from the base member 50 side toward the hub 10. The outer peripheral end of the seating surface 10 c is provided inside the circumscribed conical surface 500 and is configured not to contact the circumscribed conical surface 500. As a result, when the disk drive device 100 collides with the production facility, any of the circumscribed conical surfaces 500 collides, and the possibility that the outer peripheral end of the seating surface 10c directly collides with the production facility is reduced. it can. That is, the possibility that the recording disk 200 can be placed at an inclination is reduced.

  When the disk drive device 100 is used as, for example, a consumer-use hard disk recorder for recording and reproducing video, the hub 10 is rotationally driven at a relatively low first use rotational speed NL (Hz) while suppressing power consumption. Let This is advantageous in that power consumption is reduced.

  On the other hand, when the disk drive device 100 is used as a business server, the disk drive device 100 rotates the hub 10 at a second use rotation speed NH (Hz) that is relatively faster than the first use rotation speed NL. Drive. In this case, it is advantageous in that the operation at the time of data recording / reproducing is high speed. Although there is a method of designing and manufacturing these separately, a plurality of molds and production facilities are required, which increases production costs and is not preferable in terms of resource saving. For this reason, there is a demand to use one disk drive device 100 at a plurality of speeds.

  When one disk drive is used at a second used rotational speed NH that is larger than the first used rotational speed NL, a large vibration may occur due to torque ripple and secondary rocking mode resonance. In the embodiment, for example, when the natural frequency F0 is 2420 (Hz) and the use rotational speed NH is 110 (Hz) (6600 r / m), the lower sideband component ((3 · P− There is a possibility that 1) · N) may cause a large vibration in accordance with the upper split frequency (F0 + N) of the secondary rocking mode resonance.

  Correspondingly, the natural frequency F0 is F0 + N <(3 · P−1) · N, that is, when the use rotation speed of the hub is added to NL and the use rotation speed of the hub is NH (Hz). The radial dimension of the outer extending portion 10e of the hub 10 is configured so as to satisfy the relationship of F0 <NH · (3 · P-2). For example, when the first use rotation speed NL and the second use rotation speed NH are used, the natural frequency F0 satisfies the relationship of NL · (3 · P + 2) <F0 <NH · (3 · P-2). The radial dimension Le of the outward extending portion 10e is configured. As a result, vibration can be reduced even when a plurality of rotational speeds are used.

  As an example, the diameter D2 of the second outer cylindrical portion 10d is configured so that the natural frequency F0 is a median value of NL · (3 · P + 2) and NH · (3 · P-2). Substituting NL = 90 (Hz), NH = 110 (Hz), and P = 8, the median value of the natural frequency F0 is obtained as (2340 + 2420) / 2 = 2380 (Hz). In order to obtain a desired natural frequency F0 = 2380 (Hz), the radial dimension Le of the outer extension 10e is equal to the diameter D3 of the annular wall 10f, the diameter D2 of the second outer cylinder 10d, and the second The axial dimension Ld of the outer cylindrical portion 10d is changed as a parameter, and is determined by experiments.

  In the embodiment, when the diameter D3 of the annular wall portion 10f is 33.9 mm and the axial dimension Ld of the second outer cylinder portion 10d is 1.65 mm, the diameter 31. F0 = 2380 (Hz) was obtained at 9 mm. With this configuration, a single disk drive device can be used at a plurality of rotation speeds of 90 (Hz) and 110 (Hz).

  In the embodiment, the case where it is mainly used for a hard disk drive has been described, but the present invention is not limited to this. For example, the disk drive device 100 having the structure shown in FIG. 2 may be manufactured, and the disk drive device 100 may be mounted on an optical disk recording / reproducing device such as a CD (Compact Disc) device or a DVD (Digital Versatile Disc) device. .

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art, and such modifications have been added. Embodiments may also be included within the scope of the present invention.

  The present invention can be used in a disk drive device that rotationally drives a hub on which a recording disk is placed.

  8 data read / write section, 8a recording / reproducing head, 8b swing arm, 8c pivot assembly, 8d voice coil motor, 10 hub, 10a upper surface, 10b first outer cylinder section, 10c seating surface, 10d second outer cylinder section, 10e outer extension, 10f annular wall, 10g annular recess, 13 raised portion, 16 convex portion, 20 shaft, 22 flange, 24 first thrust dynamic pressure groove, 26 second thrust dynamic pressure groove, 30 yoke, 40 magnet, 50 Base member, 52 projecting portion, 52a outer peripheral surface, 52b inner peripheral surface, 60 laminated core, 62 annular portion, 64 salient pole, 70 coil, 80 sleeve, 82 radial dynamic pressure groove, 90 plate, 98 capillary seal portion, 100 Disk drive unit, 110 vibration control Grayed, 200 recording disk 202 first spacer, 204 second spacer, 206 clamper 208 clamping screw 500 circumscribing conical face.

Claims (9)

A base member;
A hub configured to receive a recording disk; and
A bearing unit that supports the hub to be rotatable relative to the base member;
A core fixed to the base member and including an annular portion and a plurality of salient poles extending in a radial direction from the annular portion;
A three-phase coil formed to wrap around the plurality of salient poles;
A yoke fixed to the hub;
A magnet fixed to the inner periphery of the yoke, opposed to the plurality of salient poles in the radial direction, and magnetized for driving with a P pole (P is an even number of 2 or more) in the circumferential direction;
The hub is
A first outer cylinder portion fitted in the central hole of the recording disk and extending in the axial direction;
A seating surface that is continuous with the first outer cylinder portion and extends radially outward, and on which a recording disk is seated;
A second outer cylinder portion that is connected to the seating surface and extends in the axial direction;
An outwardly extending portion that is continuous with the second outer cylindrical portion and extends outward in the radial direction;
The outer peripheral end of the seating surface is configured to be provided on the radially inner side of a circumscribed conical surface circumscribing the outer shape of the hub,
When the natural frequency at the time of non-rotation of the secondary rocking mode resonance in the state where the recording disk is mounted on the hub is F0 (Hz) and the rotation speed of the hub is N (Hz), the natural frequency F0 The disk drive device is characterized in that the radial dimension of the outer extending portion is smaller than the axial dimension of the second outer cylinder portion so that F0> N · (3 · P + 2) is satisfied. A base member;
A hub configured to receive a recording disk; and
A bearing unit that supports the hub to be rotatable relative to the base member;
A core fixed to the base member and including an annular portion and a plurality of salient poles extending in a radial direction from the annular portion;
A three-phase coil formed to wrap around the plurality of salient poles;
A yoke fixed to the hub;
A magnet fixed to the inner periphery of the yoke, opposed to the plurality of salient poles in the radial direction, and magnetized for driving with a P pole (P is an even number of 2 or more) in the circumferential direction;
The hub is
A first outer cylinder portion fitted in the central hole of the recording disk and extending in the axial direction;
A seating surface that is continuous with the first outer cylinder portion and extends radially outward, and on which a recording disk is seated;
A second outer cylinder portion that is connected to the seating surface and extends in the axial direction;
An outwardly extending portion that is continuous with the second outer cylindrical portion and extends outward in the radial direction;
The diameter of the second outer cylinder portion is substantially the same as the diameter of the outer peripheral surface of the yoke;
When the natural frequency at the time of non-rotation of the secondary rocking mode resonance in the state where the recording disk is mounted on the hub is F0 (Hz) and the rotation speed of the hub is N (Hz), the natural frequency F0 The disk drive device is characterized in that the radial dimension of the outer extending portion is smaller than the axial dimension of the second outer cylinder portion so that F0> N · (3 · P + 2) is satisfied.   2. The disk drive device according to claim 1, wherein the diameter of the second outer cylinder portion is substantially the same as the diameter of the outer peripheral surface of the yoke. The second outer cylinder section, according to any one of claims 1-3, characterized by being configured to secure the radial direction of the movable range of the recording and reproducing head for recording and reproducing the recording disc Disk drive device. The magnet is a disk drive device according to any one of claims 1-4, characterized in that provided from the radially inner portion of the seating surface in contact with the recording disc. The second outer tubular portion, in the radial direction, the disc drive apparatus according to any one of claims 1 to 5, characterized in that from the outer peripheral surface of the magnet is provided at a position closer to the outer peripheral surface of the yoke . The second outer cylinder portion is configured to be processed continuously with the processing of the first outer cylinder portion so as to be substantially concentric with the first outer cylinder portion. the disk drive device according to any one of claims 1 to 6.   When used at a rotation speed M (Hz) larger than the rotation speed N in addition to the rotation speed N, the natural frequency F0 satisfies the relationship F0 <M · (3 · P-2). The disk drive device according to claim 1, wherein a radial dimension of the outer extending portion is configured. The hub further includes an annular wall portion that is connected to the outer extension portion and extends in the axial direction;
The disk drive device according to claim 1, wherein the yoke is fixed to an inner peripheral surface of the annular wall portion.

Images