JPH0650594B2 - Swing-type dual actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oscillating actuator for a magnetic disk device in which two oscillating actuators are compactly mounted.

[Conventional technology]

Most conventional magnetic disk devices write and read information by associating one actuator with one disk spindle. However, for a recent large-capacity magnetic disk device, a type in which two actuators are provided for one disk spindle to improve the processing capacity of the device has been proposed and put to practical use. Has been done.

[Problems to be solved by the invention]

As a dual actuator configuration in which multiple actuators are arranged on one disk spindle, there is a type in which individual actuators are arranged around the disk spindle, but in this configuration, the area occupied by the actuator is large and the device becomes large. It has the serious drawback of becoming larger.

On the other hand, in Japanese Patent Laid-Open No. 58-23362, a plurality of swing actuators are arranged at a high packing density by being constituted by a plurality of rotary carriages that are independently rotatable with respect to a common fixed shaft. The structure of such an oscillating dual actuator is disclosed. This structure is shown in Fig. 4 (a),
Shown in (b). To briefly explain this, 10 is a fixed shaft whose lower end is fixed to the sub-base 21, and the rotary carriage 11 is supported by the bearings 12 and 12 'so as to be independently swingable with respect to the fixed shaft 10. , 11 ',
Head arms 13, 13 'and flat coils 15, 1
Coil supports 14 and 14 'supporting 5'are joined to form two sets of rocking bodies. Since this type of oscillating dual actuator shares the shaft, the bearings are inevitably fixed to the inner ring and rotated to the outer ring. The bearings are preloaded evenly on the four bearings 12, 12 'by a preload spring 22 via a spacer 23 between the upper bearing 12' and the lower bearing 12. 16, 16 'are permanent magnets, 1
Reference numerals 7, 17 ', and 18 denote yokes which form a magnetic circuit. Reference numeral 19 denotes a magnetic circuit housing. The housing 19 includes the sub-base 21, a top plate 20 for supporting the upper end of the fixed shaft 10, and a top plate 2.
0 and a box-shaped member 9 interposed between the sub base 21. Reference numerals 25, 26, 25 'and 26' are stopper mechanism assemblies that define the swing range of each swing body. The head arms 13, 13 'are connected to the rotary carriages 11, 11' by means of draw bolts 24.

By the way, in order to enhance the dynamic positioning performance of the swing actuator for a magnetic disk, the transfer function (mechanical impedance) between the coil portion, which is the point of force application, and the tip of the head arm on which the magnetic head is mounted is high. It is required to be constant up to the frequency. In other words, in the structure shown in FIG. 4, it is necessary that the combination of the coil supports 14, 14 ', the rotary carriages 11, 11' and the head arms 13, 13 'have a high rigidity including the joints. is there. Further, the head arms 13 and 13 'are required to have high dimensional stability in the swinging direction (in-plane direction in FIG. 4 (a)) and in the height direction (axial direction). Head arm 13,1
Each of the 3'arms is equipped with a dedicated servo head (not shown) for reading the position signal previously written on the magnetic disk surface. Based on this position information, each rocker moves and positions. However, if another head arm is displaced relative to the arm equipped with the servo head (hereinafter referred to as the servo arm) in the rocking direction due to rocking or thermal strain, information writing and reading is performed. The magnetic head will not be positioned correctly. If the dimensional accuracy of the head arms 13 and 13 'in the height direction is poor, the floating magnetic head mounted on the tip end and floating up to a submicron levitation clearance with respect to the rotating magnetic disk surface may have a levitation characteristic. There is a risk that the recorded information will be destroyed due to the contact between the magnetic head and the disk rotating at a high speed.

As described above, the swing type multi-actuator shown in FIG.
Since 3'is connected to the rotary carriages 11 and 11 ', the rigidity of the connecting portion is insufficient and the mechanical impedance of the rocking motion cannot be sufficiently increased. Further, the head arms 13 and 13 'are pressed against the reference surfaces of the rotary carriages 11 and 11' by the tension of the draw bolts 24, but the draw bolt tensions for securing the coupling force are respectively applied to the rotary carriages 11 and 11 '. Swing direction,
It acts as a component force applied to each reference surface in the arm longitudinal direction and the height direction. Ideally, these component forces should act only on the forces in the vertical direction on each reference plane, but in reality they form a complex system that includes frictional forces, and the joint surface has strains and frictional forces perpendicular to the planes. Causes shear strain. If an impact force exceeding the frictional force acts on the head arm in this coupled state, the head arm may be displaced from the reference position, and there is a risk that it will not return to its original position. In addition, the head arm may deviate from its normal position due to a change in strain generated on the reference surface due to a change in ambient temperature or a deformation of the reference surface itself. This kind of head arm position change does not cause any problems if it changes exactly the same as the servo head arm quantitatively, but a slight relative displacement occurs due to part variations, draw bolt tension variations, etc. Even if it is positioned at
There is a drawback in that the reproducing head is displaced from the original recording track and the operation as a storage device becomes defective.

Further, the height direction component of the draw bolt tension is added to the height direction reference surface of the carriages 11 and 11 'to define the height of the head arms 13 and 13'. In other words, the head arms 13 and 13 'have The draw bolt tension and the reaction force from the carriage reference surface add to balance. More specifically, the draw bolt tension is applied at a constant angle with respect to the longitudinal direction of the head arms 13, 13 'as shown in FIG. 4, and the rotary carriage 11, 11' is applied.
Receives a reaction force from the reference planes of the two sides that are substantially orthogonal to each other. That is, since an asymmetrical force is applied to the head arms 13 and 13 'in the longitudinal direction, the head arm having a thickness of about 3 to 4 mm is warped or twisted. For this reason, the draw bolt tension must be strictly controlled so that this head arm deformation does not exceed a certain amount. If there are two magnetic heads mounted on the tip of the head arm (one magnetic head corresponds to the disk surface), it is relatively easy because only the height of one magnetic head mounting surface at the tip needs to be managed. As shown in Fig. 4, in the case of a structure in which four magnetic heads are mounted on the tip of the head arm (two magnetic heads correspond to the disk surface), the heights of the two tip portions must be controlled at the same time. If the deformation accompanied by twisting occurs, it becomes impossible to control the dimension of the head arm in the height direction.

On the other hand, as an example of the structure of an oscillating actuator which does not use the draw bolt connection method, there are JP-A-55-67975, JP-A-56-9582 and Japanese Patent Application No. 55-59965.
There is a structure disclosed in No. FIG. 5 shows a structural diagram thereof, and elements having the same functions as those in FIG. 4 are denoted by the same reference numerals and the description thereof will be omitted. This is because a flat head arm 13 having a circular hole that fits into a rotary cylinder 11 that is rotatably supported with respect to a fixed shaft 10 is successively fitted into the rotary cylinder 11 so as to be stacked and fixed to form an oscillator. Unlike the draw bolt connection method, the structure is such that no stress that causes warping or twisting deformation of the head arm 13 is applied. Further, since the coil support 14 can be directly connected to the head arm 13, there is an advantage that the rigidity of the oscillator is improved. However, an example in which this structure is applied to an oscillating multi-actuator is not disclosed. The head arm 1 is attached to a rotary cylinder 11 rotatably supported by bearings 12 and 12 ′ on a fixed shaft 10 fixed to a sub base 21 by a method such as press fitting or shrink fitting.
Since a receiving portion 31 for stacking and fixing 3 is necessary, that is, a step which should be a reference surface of the stacking arm is necessary at the lowermost part, even if this structure is simply configured in two steps, Head arm 13 having a fitting circular hole
This is because it cannot be fitted into the lower rotary cylinder. In order to make this possible, the rotary cylinder 11 can be easily attached and detached, and the rocking body in which the head arm 13 is laminated and fixed to the rotary cylinder 11 can be set on the fixed shaft 10. However, highly accurate fitting conditions are required. The inner ring or outer ring of the bearing 12, 12 '
It is extremely difficult to insert it after every attachment and detachment. Rather, all of the bearings 12 and 12 'except the fitting surface (inner ring of the bearing 12' in Fig. 5), which must inevitably have a clearance fit to give a preload, are press-fitted and bonded. The rotary cylinder 11 cannot be configured to be easily attachable / detachable because the fitting condition without play must be satisfied by such a method.

In FIG. 5, 27 is a screw for fixing the laminated arm 13 to the rotary cylinder 11, 28 is a connecting pin for connecting and fixing the respective arms to each other, and 29 is an arm spacer for adjusting / defining the interval between the head arms 13. Is.

[Means for solving problems]

The oscillating dual actuator according to the present invention has been made to solve the above-mentioned problems, and is independently rotated with respect to a fixed shaft having a step forming a reference surface for positioning a bearing in a central portion. Two rotary cylinders that are movably supported and are arranged symmetrically with respect to an imaginary center plane that is orthogonal to the fixed axis; and head arms that are fixed to each rotary cylinder by stacking and fixing from both shaft end sides. A driving coil and a coil support for applying a driving force to the head arm and a member forming a magnetic circuit are provided, and the fixed shaft is configured to be attachable to and detachable from the housing.

Further, another invention of the present invention is such that it is rotatably supported with respect to a fixed shaft having a step forming a reference surface for positioning a bearing in the central portion and is orthogonal to the fixed shaft. Two rotary cylinders arranged substantially symmetrically,
Each rotary cylinder is equipped with a head arm fitted and fixed from both shaft ends, a driving coil for applying a driving force to the head arm and a coil support, and a member forming a magnetic circuit. Of the head arm, a servo arm equipped with a servo head for reading the position information written on the magnetic disk surface is different in plate thickness from the head arm, and a virtual central plane orthogonal to the fixed axis is provided. It is arranged in a plane-symmetrical position.

[Action]

In the present invention, since the fixed shaft is configured to be attachable to and detachable from the housing, it is possible to assemble the head arm without attaching and detaching the bearing having severe fitting conditions. The stage of the fixed shaft positions the bearing with its axial end face as a reference plane.

Further, in another invention of the present invention, since the two rotary cylinders and the servo arm are respectively arranged at positions symmetrical with respect to the virtual center plane orthogonal to the fixed axis,
The inertia of each oscillator can be made substantially the same.
Therefore, the drive system parameters of each oscillator are almost the same, and the sameness as a dual actuator is secured.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a partially cutaway plan view showing an embodiment of an oscillating dual actuator according to the present invention, and FIG. 2 is a partially cutaway side view of the actuator. In these figures, components having the same functions as those shown in FIGS. 4 and 5 are designated by the same reference numerals.

Reference numeral 10 denotes a fixed shaft that is detachably fixed to a sub-base 21 and a top plate 20 that form a housing 19 together with the member 9, and 11, 11 ′ (however, 11 is not shown) with respect to the fixed shaft 10. Bearings 12b and 12 positioned with a step 31 provided in the center as a reference plane
b'and shaft end side bearings 12a, 12a 'are rotatably supported, and a virtual center plane A- that is orthogonal to the fixed shaft 10
Rotary cylinders arranged symmetrically with respect to A ', 13,
Reference numeral 13 'is a flat head arm having a circular hole that fits into the rotary cylinders 11 and 11'. The head arms are sequentially fitted into the rotary cylinders 11 and 11 'from both shaft end sides, respectively, and laminated and fixed together with the arm spacers 29 and 29'. To be done. 27 and 27 'are screws for fixing the laminated arms 13 and 13' to the rotary cylinders 11 and 11 ', 2
Reference numerals 8 and 28 'denote connecting pins for connecting and fixing the head arms 13 and 13' and the arm spacers 29 and 29 'to each other. Reference numerals 15 and 15 'are flat driving coils fixed to the coil supports 14 and 14'.
14 'is a spacer arm 2 located substantially in the center of the oscillator.
9a and 29a 'are fixedly coupled to the protrusions provided on the magnetic circuit side to give a driving force to the oscillator. Bearings 12a, 12
b, 12'a, 12'b have preloaded springs 22, 2
2'provides preload respectively. Central bearing 1
2b and 12'b are steps 31 provided at the center of the fixed shaft 10.
Is used as a reference surface and is fixed by press-fitting or gluing. The inner rings of the shaft end side bearings 12a and 12'a are provided with a clearance fitting condition in order to give a stable preload.
The play of this inner ring is caused by the spring 3 built in the fixed shaft 10.
Absorbed by applying radial preload by 2, 32 '. The bearings 12b and 12'b on the shaft center side may be loosened in the inner ring and a similar play absorbing mechanism may be provided.
Reference numerals 16 and 16 'are permanent magnets and reference numerals 17, 17' and 18 are yokes, which form a magnetic circuit. 37,3
7'is an arm presser.

The assembly of this dual actuator is performed by the following procedure. First, the rotary shaft 11, 1 is attached to the fixed shaft 10.
After the head arms 13, 13 'and the arm spacers 29, 29' are laminated and fixed from the shaft end side to the assembly in which 1'is provided, the coil supports 14, 14 'are joined to assemble the oscillator. Complete. This assembly is arranged in a housing 19 composed of a member 9, a sub-base 21 and a top plate 20 so that the coils 15, 15 'can be inserted into the gears of the permanent magnets 16, 16'.
The lower and upper ends of the dual actuator are fixed to the sub-base 21 and the top plate 20, respectively, to complete the assembly of the dual actuator.

Reference numerals 30 and 30 'are holding plates for fixing the fixed shaft 10 to the sub base 21 and the top plate 20. The method of fixing the fixed shaft 10 is not limited to the embodiment, and may be directly screwed or fixed as long as it can be stably fixed to the reference surface provided on the sub base 21 and the top plate 20. Various methods such as a fixing method using the wedge effect can be used.

Since the present invention has the structure described above,
There is no warping or twisting deformation of the head arms 13 and 13 ', and the coupling portion that causes bending vibration of the oscillator is the coil support 1.
Since there is only one connecting portion between the armrests 4, 14 'and the arm spacers 29, 29', it is possible to realize an arm-stacking type rocking type dual actuator having a high rocking body rigidity. The embodiment shown in FIGS. 1 and 2 shows the case where each rocker has four head arms 13 and 13 ', so that the center arm spacer is arranged so that a driving force is applied to the center of gravity of the rocker. 29
The coil supports 14 and 14 'are connected to a and 29a', but when the number of head arms of each oscillator is odd, the coil support is similarly provided on the magnetic circuit side of the head arm located at the center. Mounting surfaces for the bodies 14, 14 'are provided and joined. Not only in the swinging type actuator but also in the straight-moving type actuator, the center of gravity of this movable portion, the point of action of the driving force and the center of the movable portion supporting point (in FIG. 2, the bearings 12a-12b, 12'a-12'b It is well known to those skilled in the art that the coupling vibrations that adversely affect the positioning performance can be suppressed by making the (center) coincide.

Furthermore, the most important characteristic of the vibration of the magnetic disk actuator is the vibration transfer function between the coil support 14 and 14 'that supports the coil that provides the driving force of the servo head that reads out the positioning reference signal. It is necessary that the area is constant. For this reason,
Servo arms are required to be vibrationally more stable than other data arms. In order to realize this, it is effective that only the servo arm has a specially thick plate or the frame structure is strengthened to have a different structure and size from the data arm. In this case as well, it is important that the center of gravity of the oscillator be configured to coincide with the center of the action point of the driving force and the center of the oscillator support point. In the embodiment of the present invention shown in FIGS. 1 and 2, since the movable portion is arranged plane-symmetrically with respect to the virtual center plane A-A 'as described above, the center of gravity of both rockers is also A-. It is symmetrical with respect to the A ′ plane. Since FIG. 2 shows a case where the servo arm has the same structure and dimensions as the data arm, in this case, the servo arm may be arranged at an arbitrary position, for example, the second from the bottom of each rocking body. .

FIG. 3 shows another embodiment of the present invention. Head arm 1
Reference numerals 13a and 13'a of 3, 13 'are servo arms, and the structure is shown when the plate thickness is made thicker than other head arms. The other structural elements are the same as those in the above-mentioned embodiment. The servo arm 13a 'is the second from the bottom for the upper swing body, and the servo arm 1a is for the lower swing body.
3a are arranged at the third position from the bottom, that is, they are arranged symmetrically with respect to the virtual center plane AA 'so that the center of gravity of each oscillator is symmetrical with respect to the plane AA'. It has become. Therefore, when the center of gravity of each oscillating body of the oscillating type dual actuator is made coincident with the center of the driving force acting point and the center of the supporting point, it can be realized by performing the same operation for the upper and lower oscillating bodies.

That is, the oscillators shown in FIGS. 2 and 3 have an asymmetric structure with respect to the axial direction, but the center of gravity of each oscillator cannot be aligned with the center plane of the driving force acting point and the supporting point. This can be easily realized by calculating the position of the center of gravity at the design stage, or by installing a balance weight on the arm presser 37, 37 '. When the method of installing the balance weight is adopted, it is possible to adjust by changing the balance weight amount even if the shift amount of the center of gravity of each oscillator is not the same. Virtual center plane A including the position of the servo arm
By arranging in a plane symmetry with respect to -A ', the balance weights to be installed at the arm pressers 37, 37' can be almost the same amount, and the inertia of each oscillator can be made almost the same. Can be the same. As a result, the drive system parameters of each oscillator can be made substantially the same, the sameness as a dual actuator can be secured, and the productivity and the stability of the positioning characteristics can be improved.

〔The invention's effect〕

As described above, the swing type dual actuator according to the present invention is independently swingably supported with respect to the fixed shaft having the step forming the reference surface for positioning the bearing in the central portion, and the fixed shaft is fixed. An oscillating body is configured by two head cylinders, which are fitted and fixed to two rotary cylinders, which are arranged symmetrically with respect to an imaginary center plane AA 'orthogonal to the axis, from both ends of the shaft, and the fixed shaft is fixed. Since the structure is detachable from the housing, the head arm can be assembled without attaching or detaching the bearing, and the rigidity of the oscillator is not reduced and the head arm is not warped or twisted due to the draw bolt connection method. The oscillating dual actuator can be realized. This has the advantage that the positioning accuracy of the oscillating dual actuator can be dramatically increased with a compact structure, the positioning speed can be increased, and the performance of the magnetic disk device can be improved. Further, according to the present invention, since the head arm and the servo arm on which the servo head is mounted are made to have different thicknesses and the servo arm is arranged at a position symmetrical with respect to the virtual center plane orthogonal to the fixed axis, each rocking body is provided. The parameters of the drive system can be set to be almost the same, which not only ensures the sameness as a dual actuator, but also improves the stability of productivity and positioning characteristics.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing an embodiment of an oscillating dual actuator according to the present invention, FIG. 2 is a partially cutaway side view of the same actuator, and FIG. 3 is another embodiment of the present invention. Partially broken side view showing an example, FIGS. 4 (a) and 4 (b) are partially broken plan views and partially broken side views showing a conventional oscillating dual actuator, and FIG. 5 is a conventional arm. FIG. 3 is a partially cutaway side view showing a laminated single actuator. 10 ... Fixed shaft, 11, 11 '... Rotary carriage or rotary cylinder, 12, 12', 12a,
12b, 12'a, 12'b ... Bearings, 13, 13 '...
... Head arm, 13a, 13'a ... Servo arm,
14, 14 '... Coil support, 15, 15' ... Driving coil, 16, 16 '... Permanent magnet, 17, 17',
18 ... Yoke, 19 ... Housing, 20 ... Top plate, 21 ... Sub base, 31 ... Step.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Kakizaki 3-9-11 Midoricho, Musashino-shi, Tokyo Inside Nippon Telegraph and Telephone Corporation, Institute of Electronics and Mechanical Engineering (72) Inventor Koji Ohtani 3-chome Midoricho, Musashino-shi, Tokyo No. 11 In the Institute of Electronics Technology, Nippon Telegraph and Telephone Corporation (72) Inventor Hiroshi Koriyama 5-33-1, Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Inventor Takashi Kajiura 5 Shiba, Minato-ku, Tokyo 33-1-1, NEC Corporation

Claims (2)

[Claims] Claims: 1. A centrally supported rotatably supported independently of a fixed shaft having a step forming a reference plane for positioning a bearing, and substantially plane symmetric with respect to an imaginary central plane orthogonal to the fixed shaft. And two rotary cylinders, a head arm fitted and fixed to each rotary cylinder from both axial ends, a driving coil and a coil support for applying a driving force to the head arm, and a magnetic circuit are formed. And a member for controlling the fixed shaft, wherein the fixed shaft is configured to be attachable to and detachable from the housing. 2. A center portion is rotatably supported independently of a fixed shaft having a step forming a reference surface for positioning a bearing, and is substantially plane-symmetric with respect to an imaginary center plane orthogonal to the fixed shaft. And two rotary cylinders, a head arm fitted and fixed to each rotary cylinder from both axial ends, a driving coil and a coil support for applying a driving force to the head arm, and a magnetic circuit are formed. And a member that allows the fixed shaft to be attached to and detached from the housing,
Of the head arms, a servo arm equipped with a servo head for reading position information written on the magnetic disk surface has a plate thickness different from that of the head arm, and has a position symmetrical to a virtual center plane orthogonal to the fixed axis. Swing type dual actuator characterized in that it is arranged in the.