JPH04258855A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the number of parts to the extreme small and to obtain a device with low cost, high function and high quality by constituting a voice- coil motor out of 1st and 2nd yokes opposite to a movable coil. CONSTITUTION:The voice-coil motor for driving an arm is composed of one movable coil 4, the 1st yoke 22 fixed with a magnet 21 and the opposit 2nd yoke 26. The 2nd yoke 26 possesses a flat surface adjacent to the movable coil 4 and two side walls 26b and 26c bent from end parts of the flat surface, and also possesses buffer parts 6a and 6b for regulating the arm in its operation, and these constitute a magnetic circuit unit. Consequently, the side walls 26b and 26c act as the function of the so-called side yokes of a magnetic circuit of a head positioning device, absorbing impact energy of the arm at high efficiency, so that the subject device with a reduced number of parts, high performance and of thin type can be realized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive, and more particularly to a head positioning device for positioning a magnetic head.

0002

2. Description of the Related Art As a conventional head positioning device, the structure disclosed in Japanese Utility Model Application Laid-Open No. 62-83265 is generally known, and more details are shown in FIGS. 7 and 8.

FIG. 7 is a partially cutaway plan view showing a conventional positioning device, and FIG. 8 is a view taken along arrow A in FIG.

In FIGS. 7 and 8, reference numeral 71 denotes an arm, and the arm 71 has a flat moving coil 72 fixed to one end and a magnetic head (not shown) fixed to the other end. It is rotatably disposed via a shaft 73 so as to be located within the portion 81 . Further, the magnet 82 is fixed to the upper yoke 83 and the lower yoke 84 by adhesive or other means, and is disposed at a position facing the movable coil 72. Furthermore, the upper yoke 83 and the lower yoke 84 are connected by yoke spacers 85a and 85b, and are fixed with screws 86a and 86b, so that a magnetic circuit unit 87
It consists of Here, a portion of the yoke spacers 85a and 85b includes restraining members 88a and 88b made of urethane rubber, for example, which restrict the operating range of the arm 71.
are mated.

In the head positioning device employing the configuration described above, when a signal current is applied to the moving coil 72, a driving force is applied to the moving coil 72 around the shaft 73 according to Fleming's left hand rule. , the arm 71
is rotated to position the magnetic head fixed to the arm 71 at a desired recording track on a magnetic disk (not shown).

By the way, if an accidental failure occurs in the head positioning device, such as an error in reading position information or a device drive circuit failure, the device may cause a so-called runaway operation other than the permissible operation. If this runaway operation occurs, the urethane rubber restraint member 88a or 8
8b stops the rotation of the head positioning device, thereby preventing the device from moving beyond a predetermined range.

[0007]Although not shown in the drawings, there are various known buffer members that use spring elements such as plate springs to buffer and stop this runaway state.

Generally, in this type of head positioning device, in order to secure as large an information recording area on the magnetic disk surface as possible, it is desirable that the distance required to stop the device from running out of control is as small as possible. In addition, in order to prevent the magnetic head moved by the device from coming into contact with the magnetic disk when buffering and stopping runaway operation, the device must ensure that the acceleration applied to the magnetic head during runaway buffering is below a permissible value. something is required. Furthermore, modern magnetic disk drives are required to be extremely light, thin, and compact so that they can be installed in portable personal computers and the like.

[0009]

However, the above-mentioned prior art has the following problems. first of all,
In FIG. 8, the yoke spacers 85a and 85b, which serve as the middle side yoke of the magnetic circuit 87, are constructed as separate parts from approximately cylindrical members.
The magnet 82 is attracted to the magnet 82 by the magnetic force of 2. Therefore, the yoke spacers 85a and 85b are connected to the magnet 8.
There was a problem in that it required a considerable amount of ingenuity and effort to assemble without reaching 2, resulting in high costs.

As a means to avoid this, if the yoke spacers 85a and 85b are made of a non-magnetic material such as brass or stainless steel, the assembly process will be relatively easy, but the magnetic path of the magnetic field generated by the magnet 82 will be It will be small and limited. Therefore, in order to prevent the upper yoke 83 and the lower yoke 84 from becoming magnetically saturated, it is necessary to increase their plate thickness, which has been an obstacle to making the magnetic disk device thinner.

Next, the above-mentioned prior art also has the following problems. When the head positioning device goes out of control, the runaway energy becomes extremely large. Here, FIG. 9 is a diagram showing the load-displacement characteristics of general rubber.
The amount of energy that rubber can absorb as a buffer member is indicated by diagonal lines in the figure. Therefore, when rubber is used as a buffer member, as can be seen from the figure, the amount of displacement of the rubber must be large in order to absorb a large amount of runaway energy. Therefore, in the prior art as shown in FIGS. 7 and 8, in order to buffer and stop the runaway state, the restraining member 88 made of urethane rubber is required.
Sufficient elastic deformation must be caused in a and 88b. For this purpose, it is necessary to compress the rubber to the order of a fraction of its thickness, and it is necessary to increase the mounting volume. Further, the normal operating range of the head positioning device is limited to only θ shown in FIG. 7, and therefore the operating range of the magnetic head is also θ. Here, if the mounting volume of the rubber is set to be large, θ will inevitably become small, and the recordable area on the magnetic disk will be limited to a small size, resulting in a problem that the information recording capacity will be reduced. Furthermore, the device itself has become larger, which is contrary to the recent demand for lighter, thinner, shorter, and smaller devices. Furthermore, if the mounting volume of the rubber is sacrificed in pursuit of miniaturization of the device, the permissible displacement amount of the rubber will be reduced, making it impossible to sufficiently absorb large runaway energy, and the head positioning device will be forced to It is not possible to reduce the acceleration applied to the magnetic head as desired, and there is a high possibility that a head crash will occur when the magnetic head runs out of control.

[0012] Also, those using a metal elastic body such as a leaf spring as a buffer member have the following problems. FIG. 10 is a diagram showing the load-displacement characteristics of a spring element used as a buffer member. Similarly to FIG. 9, the shaded area in the figure is the amount of energy that can be absorbed by the buffer member. Figure 1
As shown in Figure 0, spring elements are more efficient than rubber materials, that is, they can absorb runaway energy with a relatively small amount of displacement, but on the other hand, in the stopped state during normal normal operation, their cushioning effect is lower than that of rubber materials and is relatively large. Acceleration will be applied to the device. For this reason, after tens of thousands of stop operations required of a magnetic disk drive, there is a high possibility that the magnetic head and head positioning device will become relatively "misaligned" and read errors will occur.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a buffer member that efficiently buffers the runaway state of a head positioning device with a small mounting volume. It is an object of the present invention to provide a magnetic disk device that is excellent in durability, inexpensive, compact, and guarantees high quality and high functionality.

[0014]

Means for Solving the Problems In order to solve the above problems, a magnetic disk device according to the present invention includes at least one magnetic disk and at least one magnetic disk that faces the magnetic disk and achieves recording and reproduction of information. A magnetic head, an arm that supports the magnetic head and is rotatably supported, a voice coil motor that drives the arm, and a buffer that comes into contact with a part of the arm to buffer and stop the rotation of the arm. In the magnetic disk device comprising a base frame on which the arm and the voice coil motor are arranged, the voice coil motor has at least one moving coil held between the arms and at least one magnet fixed thereto. a first yoke; a flat surface facing the first yoke and close to the movable coil; and at least two side walls bent from an end of the flat surface, the side walls engaging with the first yoke. The first yoke is characterized by comprising a second yoke provided with engagement means for performing relative positioning and holding.

[0015] Furthermore, the buffer member of the magnetic disk drive according to the present invention is arranged substantially perpendicular to the rotating surface of the arm, has flexibility, and can come into contact with a part of the arm. , and is characterized in that it is engaged with and held by a portion of the first yoke and the second yoke.

[0016]

[Operation] According to the above configuration of the present invention, the magnetic disk drive of the present invention has the side wall serving as a so-called side yoke of the magnetic circuit of the head positioning device, and has high performance despite the small number of components. It becomes possible to realize a thin magnetic disk device. Further, the first yoke and the second yoke directly engage and hold each other to achieve a magnetic circuit with a simple structure, making it possible to realize an inexpensive magnetic disk device that is highly mass-producible.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below. FIG. 1 is a plan view showing a positioning device for a magnetic disk drive to which the present invention is applied, and FIG. 2 is an exploded perspective view of a magnetic circuit of the positioning device for a magnetic disk drive to which the present invention is applied.

In FIGS. 1 and 2, an arm 1 has a magnetic head 3 at one end for recording and reproducing information on a magnetic disk 2.
A movable coil 4, which forms part of a voice coil motor, is fixed to the other end of each of the movable coils 4, and is rotatably arranged via a shaft 5. Here, as shown in FIG. 1, approximately trapezoidal pressing portions 1c and 1d are integrally formed at the ends of the arm portions 1a and 1b of the arm 1 which clamp and fix the movable coil 4. Further, on one side facing the movable coil 4 in the plane direction, a first yoke 22 mainly made of iron is arranged, to which a magnet 21 is fixed by means such as adhesive. moreover,
Approximately track-shaped first openings 23a and 23b are provided at approximately both ends of the first yoke 22, and other rectangular openings 24a and 24b are provided at positions close to these first openings 23a and 23b. are arranged side by side.

On the other hand, at a position facing the first yoke 22 and with the movable coil 4 disposed therebetween, a second yoke 26 is arranged, which is mainly made of iron and has a structure as detailed below. has been done.

Here, the second yoke 26 has a flat surface 26a having substantially the same shape as the first yoke 22,
Both ends thereof are bent at substantially right angles to form side walls 26b and 26c. The ends of the side walls 26b and 26c are connected to the first openings 23a, 23b of the first yoke 22 and the opening 2.
Projections 27a, 27b and 28 that fit into 4a and 24b
a and 28b are integrally formed. Further, the plane 26
First openings 23a of the first yoke 22 are provided at substantially both ends of the first yoke 23a.
and 23b, second openings 29a and 29b having substantially the same shape are provided. In the magnetic circuit configured as described above, the first yoke 22 is connected to the screw 25a as shown in FIG.
and 25b to a base frame (not shown), and in a position sandwiching the movable coil 4, the protrusions 27a, 27b and 28a, 28b of the second yoke 26 are fixed to the openings 23a, 23b and 25b of the first yoke 22. 24a, 24
b, thereby connecting the first yoke 22 and the second yoke 26.
is positioned. Further, since the second yoke 26 is mainly made of iron, it is attracted by the magnetic force of the magnet 21, and the first yoke 22 and the second yoke 26 are attracted to each other by the magnetic force of the magnet 21.
holds the bond.

Further, cylindrical buffer members 6a and 6b made of, for example, nitrile rubber, which restrict the operating range of the arm 1, are arranged in the openings 23a, 29a, and 23b.
29b and is held to constitute a magnetic circuit unit.

In the magnetic disk drive according to the present invention described in detail above, when a signal current is applied to the movable coil 4, a driving force is applied to the movable coil 4 around the shaft 5 according to Fleming's left hand rule. Then, the arm 1 is rotated, and the magnetic head 3 fixed to the arm 1 is positioned at a desired recording track on the magnetic disk 2.

Next, regarding the case where an accidental failure such as an error in reading position information or a failure in the positioning device drive circuit occurs in the magnetic disk device according to the present invention, that is, a so-called runaway operation other than the permissible operation of the positioning device occurs. explain. Here, FIG. 3 is a sectional view of a main part of the magnetic disk device according to the present invention, and shows a mode in which a runaway state is buffered and stopped.

In FIG. 1, consider a case where the arm 1 runs out of control in the direction B in the figure. In this case, first, the pressing portion 1c provided at the end of the arm portion 1a of the arm 1 comes into contact with the buffer member 6a. Thereafter, as shown in FIG. 3, the runaway energy possessed by the arm 1 causes compressive deformation and bending deformation to the buffer member 6a, and the buffer member 6a bends as shown in FIG. 3 to absorb the runaway energy. Absorb.

Further, the normal normal stopping operation of the head positioning device of the magnetic disk device according to the present invention is as described below. FIG. 4 is a cross-sectional view of the main parts of the magnetic disk device according to the present invention, showing a normal stopping operation.

In this case, the kinetic energy possessed by the arm 1 is extremely small compared to that in the runaway state. Therefore, the pressing portion 1c of the arm 1 is
Even if the shock absorber 6a collides with the shock absorber 6a, it does not cause obvious bending deformation in the shock absorbing member 6a, and the shock absorbing member 6a only undergoes compressive deformation. The buffer member 6a absorbs the kinetic energy of the arm 1 by receiving this compressive deformation, and stops the arm 1 at a desired position.

The magnetic disk device according to the present invention described in detail above has the following advantages. First of all, because of the structure in which the first yoke 22 and the second yoke 26 directly engage and are coupled and held together by the magnetic force of the magnet 21 fixed to the first yoke 22, The assembly process becomes extremely easy. That is, if the second yoke 26 is simply fed from above to the first yoke 22 fixed to the base frame, the first yoke 22 is fixed in advance with the screws 25a and 25b. This is an innovative configuration in which the assembly is completed without suction and floating on the second yoke, making automatic assembly extremely easy.

Further, the yoke spacers 85a and 85b, which are used in the conventional example to connect the upper yoke 83 and the lower yoke 84, and the screw 8
6a and 86b can be reduced. As a result, a significant reduction in component cost and assembly cost is achieved, resulting in a magnetic disk device with extremely high cost performance. Furthermore, the second planes 26b and 26c of the second yoke 26
plays the role of a so-called side yoke in the magnetic circuit,
The magnetic field generated by the magnet 21 is generated substantially uniformly throughout the magnetic circuit without reducing its magnetic force. As a result, when a signal current is passed through the movable coil 4, the driving force acting on the arm 1 becomes extremely constant, resulting in a magnetic disk device that is easy to control. Furthermore, it is possible to reduce the thickness of the first yoke 22 and the second yoke 26, which greatly contributes to making the magnetic disk device thinner.

Next, the magnetic disk device according to the present invention also has the following advantages. FIG. 5 is a diagram illustrating the difference in buffering efficiency for buffering a runaway state between the conventional example and the embodiment according to the present invention. Further, FIG. 6 is a diagram illustrating the difference in buffer efficiency between the conventional example and the embodiment according to the present invention in a stopped state during normal normal operation.

In FIGS. 5 and 6, the horizontal axis represents the displacement of the shock absorbing member during shock absorption, and the vertical axis represents the load applied to the member. In the figure, the solid line shows the embodiment according to the present invention, the one-dot chain line shows the spring element, and the two-dot chain line shows the load-displacement when the conventional rubber material is used as a buffer member. It is a characteristic. Now, when the actuator 1 goes into a runaway state and a runaway load is applied to the buffer member 6a or 6b, the buffer member 6a or 6b initially receives compressive stress. Next, as shown in FIG.
and using the engaging portion with the second yoke 26 as a fulcrum,
The beams on both sides are subjected to large bending stress as if bending. Therefore, as shown in FIG. 5, initially it exhibits characteristics equivalent to the load-displacement characteristics of a rubber material, but in the middle of deformation, the characteristics become linear and become load-displacement characteristics similar to those of a spring element. Here, the buffer member 6a or 6b receives a runaway load x
1, the buffer member 6a or 6
The runaway energy absorbed by b is the integral of the load over the displacement, and is therefore shown by diagonal lines in FIG. Therefore, when trying to absorb the same amount of runaway energy as the runaway energy absorbed by the embodiment of the present invention using the rubber material shown in the prior art as a buffer member, the amount of displacement larger than x1 in FIG. It is clear that this is necessary. Therefore, in the embodiment according to the present invention, it is possible to absorb a large amount of runaway energy with a small amount of displacement, almost in the same way as a spring element. In other words, it is possible to effectively absorb large runaway energy with a small mounting volume. As a result, the operating range of the magnetic head 3 fixed to the arm 1 can be increased, and a large recordable capacity on the magnetic disk 2 can be secured. Furthermore, it greatly contributes to the miniaturization of the device.

Furthermore, since the buffer member 6a or 6b is arranged in parallel with the side wall 26c or 26b, the side wall 26c also serves as a stopper for the deflection of the buffer member 6a, as shown in FIG. Therefore, even if the runaway energy is greater than expected and the buffer member 6a is largely deflected, the buffer member 6a comes into contact with the side wall 26c and is compressed without being deflected any further, thereby buffering the runaway energy. At the same time, the magnetic head 3 supported and fixed on the arm 1 is prevented from moving out of the flying guaranteed area. That is, in the embodiment according to the present invention, even if more runaway energy than expected is applied, the runaway state is reliably buffered without causing the magnetic head 3 to deviate from the flying guaranteed area.

On the other hand, during the normal normal stopping operation of the arm 1, the buffer member 6a or 6b is subjected to compressive stress as shown in FIG. 4, as described above. At this time, Figure 6
Assuming that the buffer member 6a or 6b receives a normal load and is displaced by an amount x2 as shown in FIG. 6b, and the arm 1 stops. Here, as is clear from FIG. 6 and as described above, when a spring element is used as a buffer member, the buffering effect during normal normal stopping operation is extremely low, and a relatively large acceleration is applied to the arm 1. . However, in the embodiment according to the present invention, a sufficient damper effect is exerted, so that the arm 1 is stopped only by receiving an extremely small impact. Therefore, even after tens of thousands of stop operations required of a magnetic disk device, the magnetic head and the arm do not shift relative to each other, and the recording and reproducing characteristics of the magnetic disk device are guaranteed semi-permanently, resulting in extremely high performance. It becomes a great device.

In this embodiment, a plurality of openings and a plurality of protrusions that fit into the openings are used as the means for engaging the first yoke and the second yoke, and a substantially circular cylinder is used as the buffer member. Although the shape is shown as an example, the shape is not limited to this, and can be freely set as long as it does not depart from the gist of the present invention.

[0034]

[Effects of the Invention] As described above in detail, the magnetic disk drive according to the present invention includes a voice coil motor for driving an arm, which has at least one moving coil held between the arms and at least one magnet fixed to the voice coil motor. a first yoke; a flat surface facing the first yoke and close to the movable coil; and at least two side walls bent from an end of the flat surface, the side walls engaging with the first yoke. Since the second yoke is comprised of a second yoke that is provided with an engaging means that performs relative positioning and is retained,
The number of parts added is extremely small, and the assembly process is easy.
Moreover, it can greatly contribute to making the device thinner without deteriorating its functionality. That is, it is possible to provide an inexpensive, highly functional, and high quality magnetic disk device.

[0035] Furthermore, a buffer member for stopping the arm is disposed substantially perpendicular to the rotating surface of the arm,
It has flexibility, can come into contact with a part of the arm, and is held in engagement with a part of the first yoke and the second yoke, so that the mounting volume of the buffer member can be reduced. Can be made small,
Moreover, it is possible to absorb the impact energy of the arm with high efficiency. Furthermore, the operating range of the magnetic head fixed to the arm can be increased, and a large information recording capacity on the magnetic disk can be secured.

Furthermore, even after tens of thousands of normal stop operations required of a magnetic disk device, its recording and reproducing characteristics are guaranteed to remain unchanged from the state of initial use, resulting in an extremely high-performance device. At the same time, the space inside the magnetic disk device can be effectively utilized, making a significant contribution to making devices smaller and thinner, which are desired by today's customers. As described in detail above, the practical effects of the present invention are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a positioning device for a magnetic disk drive to which the present invention is applied.

FIG. 2 is an exploded perspective view of a magnetic circuit of a positioning device for a magnetic disk drive to which the present invention is applied.

FIG. 3 is a cross-sectional view of the main parts of the magnetic disk device according to the present invention.

FIG. 4 is a sectional view of the main parts of the magnetic disk device according to the present invention.

FIG. 5 is a diagram illustrating the difference in buffering efficiency for buffering a runaway state between a conventional example and an embodiment according to the present invention.

FIG. 6 is a diagram illustrating the difference in buffer efficiency between a conventional example and an embodiment according to the present invention in a stopped state during normal normal operation.

FIG. 7 is a partially cutaway plan view showing a conventional positioning device.

8 is a view taken along arrow A in FIG. 7. FIG.

FIG. 9 is a diagram showing the load-displacement characteristics of general rubber.

FIG. 10 is a diagram showing the load-displacement characteristics of a spring element used as a buffer member.

[Explanation of symbols]

1 Arm 2
magnetic disk 3
magnetic head 4
Moving coils 6a, 6b
Buffer member 21 Magnet 22
First yoke 23a, 23b
First openings 24a, 24b Opening 26 Second yoke 26a
Planes 26b, 26c Side walls 27a, 27b Projections 28a, 28b Projections 29a, 29b Second opening

Claims (1)

[Scope of Claims] [Claim 1] At least one magnetic disk, at least one magnetic head that faces the magnetic disk and accomplishes recording and reproduction of information, and supports the magnetic head and is rotatable. The arm and the voice coil motor are arranged: an arm supported by the arm, a voice coil motor that drives the arm, a buffer member that comes into contact with a part of the arm to buffer and stop rotation of the arm, and the arm and the voice coil motor. In a magnetic disk drive including a base frame, the voice coil motor includes at least one moving coil held between the arms, a first yoke to which at least one magnet is fixed, and a voice coil motor facing the first yoke. and has a plane close to the movable coil and at least two side walls bent from the ends of the plane, and the side walls are engaged with the first yoke to perform relative positioning and to be held. A magnetic disk device comprising a second yoke including an engaging means. 2. The engaging means includes at least one opening formed in the second yoke so as to engage with at least one opening disposed in the first yoke directly fixed to the base frame. 2. The magnet according to claim 1, comprising a protrusion and a magnetic circuit that attracts and holds the second yoke by the magnetic force of the magnet fixed to the first yoke. Disk device.Claim 3: The buffer member is arranged substantially perpendicular to the rotating surface of the arm, has flexibility, can come into contact with a part of the arm, and is connected to the first member. A magnetic disk device characterized by being held in engagement with a yoke and a portion of a second yoke. 4. The buffer member has a substantially rod-like shape, and includes a first opening in the first yoke, a second opening in the second yoke, and a second opening in the first yoke. 4. The magnetic disk device according to claim 3, wherein the magnetic disk device is inserted into and held in the second opening. 5. The buffer member is arranged in parallel with the side wall,
4. The magnetic disk drive according to claim 3, wherein a portion of said arm is configured to abut at a substantially symmetrical position with said side wall. 6. The magnetic disk device according to claim 4, wherein the buffer member is made of a rubber material. 7. The magnetic disk drive according to claim 4, wherein the buffer members are arranged at both moving ends of the arm.