JP3754665B2 - Rotary actuator and disk device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary actuator that supports a head for reading a signal from a storage medium and rotates and moves the recording medium, and a disk device using the rotary actuator.
[0002]
[Prior art]
In a magnetic disk apparatus, a head is positioned at an appropriate position on a disk by a carriage to perform recording and reproduction. The carriage is driven and rotated by a rotary actuator.
[0003]
The rotary actuator includes a pair of opposing yokes. A permanent magnet is fixed to one yoke or both yokes, and a vertical magnetic field is generated in the magnetic gap. In addition, a movable coil 7 connected to the carriage through a bearing diameter is disposed in the magnetic gap. When the movable coil is energized, the movable coil is operated by the Lorentz force generated by the action of the vertical magnetic field, and the carriage rotates. Driven.
[0004]
The movable coil includes a thermoplastic coil and a metal adhesive coil.
[0005]
A thermoplastic coil is a moving coil connected to a bearing via a thermoplastic material and a connecting member, and a metal bonded coil is a moving coil connected to a bearing via an adhesive layer and a metal aggregate. is there.
[0006]
In the magnetic disk apparatus, it is effective to increase the seek performance by making the effective length of the movable coil as long as possible (see FIG. 4). However, in recent years, hard disk drives have been downsized (the diameter of the disk has been reduced), and in such a small magnetic disk device, it is difficult to increase the effective length of the movable coil due to space limitations. Therefore, a movable coil having a long effective length is realized by arranging the suspension center line and the actuator center line to be bent in a "<" shape.
[0007]
[Problems to be solved by the invention]
However, as described above, when the suspension center line and the actuator center line are bent in a "<" shape, the direction of the contour line of the coil bending mode amplitude is often relative to the suspension center line. As a result, the magnetic head moves in the track direction during the coil bending mode vibration, and the positioning performance may deteriorate.
[0008]
In addition, thermoplastic coils are often used for movable coils because of their ease of molding, ease of handling of coil wiring, and high damping ratio. Thermoplastic coils have a modulus of elasticity of that of metal compared to that of metal. Therefore, the rigidity is lower than that of the metal adhesive coil. For this reason, a rotary actuator using a thermoplastic coil has a wall in broadening seek.
[0009]
The present invention has been made in order to solve this problem. Even when the suspension center line and the actuator center line are bent in a "<" shape, the coil bending mode vibration is generated. A rotary actuator and a disk device in which the bending mode does not move the magnetic head in the track direction and the positioning performance is not deteriorated.
[0010]
In addition, the present invention provides a rotary actuator and a disk device that can obtain high rigidity even when a thermoplastic coil is used and can achieve a broad band of seek.
[0011]
Furthermore, the present invention provides a rotary actuator and a disk device that can eliminate the deviation between the center of gravity of the carriage and the rotation center of the actuator.
[0012]
[Means for Solving the Problems]
To achieve the above object, a rotary actuator according to the present invention comprises a pair of opposing yokes, a permanent magnet provided on one or both of the yokes, and a bearing that is rotatable via a connecting member. The movable coil is supported at one end and is movable by the action of the magnetic field formed by the pair of yokes and the permanent magnet, and is provided at one end with a movable coil held by an injection-molded thermoplastic material having a lower elastic modulus than the coupling member. And an actuator provided with a suspension for supporting the head at the other end, and the center line of the actuator and the center line of the suspension are bent in a "<" shape, and are divided into two according to the center lines. The rigidity of the part on the corner side where the angle formed between the center lines is 180 ° or less is 18 degrees. ° to be higher relative to the stiffness of the part above the corner side, the rate of coupling member for coupling to the bearing occupies relative to the thermoplastic material, said angle than the site of more than 180 ° of angle side, the The angle is set to be larger at a corner of 180 ° or less, and the center line of the suspension and the contour line of the bending mode of the movable coil are orthogonal to each other.
[0013]
According to the present invention, it becomes possible to make the center line of the suspension and the direction of the contour line of the bending mode orthogonal, and the magnetic head does not move in the track direction during the coil bending mode vibration, so that the positioning performance is not deteriorated.
[0014]
Further, in the rotary actuator of the present invention, the connecting member may have an extension that reaches the magnetic field only at a corner portion of 180 ° or less .
[0015]
According to the present invention, the rigidity of the actuator in the sway direction is increased, and a wide band of actuation can be realized. In addition, since the connecting portion is extended only on the corner side of 180 ° or less, the connecting portion has a higher density than the thermoplastic material. Therefore, the center of gravity of the carriage that has been biased to the corner side of 180 ° or more so far is the center of rotation. You can get closer.
[0016]
Furthermore, in the rotary actuator of the present invention, the size of the magnetic field direction of the magnetic field of the thermoplastic material located at the corner side portion of 180 ° or more is the same direction as that of the thermoplastic material located at the corner side portion of 180 ° or less . It may be smaller than the size.
[0017]
According to the present invention, the rigidity of the part on the corner side of 180 ° or less can be set higher than the rigidity of the part on the corner side of 180 ° or more.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a plan view showing a configuration of a magnetic disk device 1 which is an embodiment employing a rotary actuator of the present invention.
[0024]
As shown in the figure, the magnetic disk device 1 includes a rectangular box-like case 2 having an upper surface opened and a top cover (not shown) that is screwed to the case 2 by a plurality of screws and closes the opening on the upper surface of the case 2. ).
[0025]
In the case 2, a magnetic disk 3 that is a disk-shaped storage medium, a spindle motor (SPM) 4 as a disk drive mechanism that supports and rotates the magnetic disk 3, and a carriage 5 are arranged.
[0026]
An HGA (Head Gimbal Assy) 6 including a head that is an element for reading and writing signals to the disk 3 and a suspension that supports the head is supported at one end of the carriage 5, and a VCM is provided at the other end. A movable coil 7 which is an element constituting the rotary actuator is attached. The carriage 5 is rotatably supported by a bearing 8 erected on the bottom surface of the case 2.
[0027]
Next, the configuration of the VCM rotary actuator 10 will be described with reference to FIGS.
[0028]
As shown in these drawings, the VCM rotary actuator 10 includes a pair of yokes 11, 12 arranged opposite to each other, permanent magnets 13, 14 fixed to the yokes 11, 12, and a magnetic gap 15. The movable coil 7 is arranged. A vertical magnetic field represented by a magnetic force line 16 is formed in the magnetic gap 15. When a current is passed through the movable coil 7, the movable coil 7 has a magnetic field line 16 of the vertical magnetic field due to Lorentz force generated by the action with the vertical magnetic field. And the carriage 5 is configured to rotate.
[0029]
In the example of FIG. 2, a thermoplastic coil 7 is used as the movable coil 7, that is, the thermoplastic coil 7 includes a winding coil 17, a thermoplastic member 18, and a connecting member 19. The connecting member 19 is connected to the bearing 8.
[0030]
Further, as shown in FIG. 3, the VCM rotary actuator 10 can take a configuration in which the permanent magnet 13 is attached only to one yoke 11. In this case, a magnetic gap 15 is formed between the permanent magnet 13 and the yoke 12, and the movable coil 7 is disposed here.
[0031]
Further, the configuration of the VCM rotary actuator 10 will be described in detail with reference to FIG.
[0032]
A Lorentz force effective for rotating the movable coil 7 is generated at each portion (hereinafter referred to as an effective portion) indicated by reference numeral 21 of the movable coil 7. Since these effective portions 21 are two straight lines opened at a certain angle with the rotation center 22 (the axial center of the bearing 8) as a fulcrum, the shape of the movable coil 7 is substantially trapezoidal.
[0033]
In order to obtain a large torque, the effective portion 21 may be made as long as possible. However, in a small magnetic disk device, there is a limit to the length of the effective portion 21 that can be taken due to space limitations. Therefore, a measure is taken to extend the length of the effective portion 21 by arranging the suspension center line 23 and the actuator center line 24 to be bent in a "<" shape. However, the angles formed by the two effective portions 21 and 21 with respect to the center line 24 of the actuator are made equal.
[0034]
Further, in this VCM rotary actuator 10, as shown in FIG. 5, the movable coil 7 is configured such that the angle formed by the suspension center line 23 and the actuator center line 24 is 180 ° or less and the A side of 180 ° or more. The B side is considered separately, and the rigidity of each side is in a relationship of A> B.
[0035]
As a result, as shown in FIG. 6, the suspension center line 23 and the bending mode contour line 25 are perpendicular to each other, and the magnetic head does not move in the track direction during the coil bending mode vibration, resulting in poor positioning performance. No longer. Incidentally, 26 is a contour line of the conventional bending mode.
[0036]
In order to make the movable coil 7 have a rigidity of A> B, the rigidity on the B side may be lowered or the rigidity on the A side may be increased.
[0037]
In order to reduce the rigidity on the B side, the thickness of the thermoplastic material 18 and the connecting member 19 on the B side is reduced in the case of the thermoplastic coil, and the thickness of the metal aggregate on the B side is reduced in the case of the metal bonded coil. Good. However, if the rigidity on the B side is weakened, the rigidity in the sway mode is also weakened at the same time, so it is more preferable to increase the rigidity on the A side.
[0038]
In order to make the A side rigidity higher than the B side, in the case of a thermoplastic coil, the thickness of the A side thermoplastic material 18 and the connecting member 19 may be increased. Since the thickness of the winding coil 17 is originally set to the maximum thickness that can be accommodated in the magnetic gap 15, it cannot be increased any more.
[0039]
Further, as shown in FIG. 7, in the region on the A side, a part (extension portion 19 a) of the connecting member 19 that is a member having a higher elastic modulus than the thermoplastic material 18 is extended so as to reach the inside of the magnetic gap 15. There is a way to set up. In this way, the rigidity of the movable coil 7 can be in a relationship of A> B by increasing the ratio of the connecting member 19 that is a member having a higher elastic modulus than the thermoplastic material 18 on the A side compared to the B side. it can.
[0040]
Moreover, the following advantage arises by comprising in this way.
[0041]
The carriage 5 is required to coincide with the center of gravity of the carriage 5 and the rotation center 22 (the axis of the bearing 8) so that no rotational torque is applied when the carriage 5 is subjected to vibration / impact. However, in the magnetic disk device, as shown in FIG. 1, a flexible printed circuit board 27 for connecting a read / write signal, an actuator drive signal, etc. between the carriage 5 and the main printed circuit board, or deterioration of the read / write signal. An amplifier (not shown) or the like for preventing this is connected and disposed at a position off the center of gravity of the carriage 5. For this reason, there is a problem that the center of gravity of the carriage and the center of rotation 22 (the axial center of the bearing 8) are shifted due to the influence of their masses. By providing the extended portion 19a of the connecting member 19 having a larger mass so as to reach the magnetic gap 15, the mass on the A side is increased, and the mass balance can be achieved.
[0042]
In order to integrate the extended portion 19a of the connecting member 19 and the thermoplastic material 18, for example, as shown in FIG. 8, in addition to the method of enclosing the extended portion 19a in the thermoplastic material 18, for example, FIG. As shown in FIG. 4, there is a method of bonding and joining to the thermoplastic material 18 in a state where a part of the extension portion 19a of the connecting member 19 is exposed in consideration of the injection property of the thermoplastic material 18.
[0043]
The present invention is not limited to any of the above-described embodiments, and can be implemented with appropriate modifications within the scope of the technical idea of the present invention.
[0044]
In the above embodiment, the present invention is applied to a magnetic disk device. However, the present invention can also be applied to a disk device using a disk-shaped storage medium other than a hard disk.
[0045]
In the above embodiment, the method for increasing the rigidity on the A side when the movable coil 7 is a thermoplastic coil has been described. However, in the case of a metal adhesive coil, the relationship between the A side and the B side for the elastic modulus of the adhesive layer. The same effect can be obtained by setting A> B.
[0046]
【The invention's effect】
As described above, according to the present invention, the center line of the suspension and the direction of the contour line of the bending mode can be orthogonal to each other, and the magnetic head does not move in the track direction during the coil bending mode vibration, so that stable positioning is achieved. Performance is obtained.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of a magnetic disk device which is an embodiment employing a rotary actuator of the present invention.
FIG. 2 is a cross-sectional view showing the configuration of the VCM rotary actuator of the embodiment of FIG.
FIG. 3 is a cross-sectional view showing a configuration of another type of VCM rotary actuator of the embodiment of FIG. 1;
4 is a plan view showing a configuration of a VCM rotary actuator of the embodiment of FIG.
FIG. 5 is a diagram for explaining that the VCM rotary actuator of the embodiment of FIG. 1 is divided into two parts by a suspension center line and an actuator center line;
6 is a plan view showing a relationship between a suspension center line and a bending mode contour line in the VCM rotary actuator of the embodiment of FIG. 1; FIG.
7 is a view for explaining a method for making the A side rigidity higher than the B side in the VCM rotary actuator of the embodiment of FIG. 1; FIG.
FIG. 8 is a cross-sectional view showing a connection relationship between an extension portion of a connecting member and a thermoplastic material.
FIG. 9 is a cross-sectional view showing another connection relationship between the extension portion of the connecting member and the thermoplastic material.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Magnetic disk apparatus, 3 ... Disk, 5 ... Carriage, 7 ... Moving coil, 8 ... Bearing, 10 ... VCM rotary actuator, 11, 12 ... Yoke, 13 , 14 ... Permanent magnet, 15 ... Magnetic gap, 16 ... Magnetic field line, 17 ... Winding coil, 18 ... Thermoplastic material, 19 ... Connecting member, 19a ... Extension , 21 ... Effective portion, 23 ... Suspension center line, 24 ... Actuator center line, 25 ... Bending mode contour

Claims (4)

A pair of opposing yokes,
Permanent magnets provided on the one or both yokes;
An injection-molded thermoplastic material that is rotatably supported by a bearing via a connecting member and is moved by the action of a magnetic field formed by the pair of yokes and the permanent magnet, and has an elastic modulus lower than that of the connecting member. Comprising a movable coil held at one end and an actuator having a suspension supporting the head at the other end;
The center line of the actuator and the center line of the suspension are bent in a “<” shape, and the angle between the center lines is 180 ° or less among the parts divided into two according to the center lines. The proportion of the connecting member connected to the bearing to the thermoplastic material is such that the rigidity of the corner portion is higher than the rigidity of the corner portion where the angle is 180 ° or more , The angle is set to be larger than the angle-side portion of the angle of 180 ° or more compared to the angle-side portion of the angle of 180 ° or more, and the center line of the suspension and the contour line of the bending mode of the movable coil are rotary actuator characterized in that is orthogonal. Rotary actuator according to claim 1, before Symbol connecting member is only a portion of the 180 ° following angle side, and having an extension reaching into the magnetic field. The size in the direction of the magnetic field lines of the magnetic field of the thermoplastic material located at the corner side portion of 180 ° or more is smaller than the size of the thermoplastic material located at the corner side portion of 180 ° or less in the same direction. The rotary actuator according to claim 1. A disk device having the rotary actuator according to any one of claims 1 to 3 .

Images