JP2001110154A - Voice coil motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide concrete constitution for reducing or eliminating the generation of vibrations in the direction orthogonal to the moving direction of a coil caused by the fact that magnetic flux in the vicinity of the terminal end of a coil movable range is not orthogonal to the moving direction of the coil, in a voice coil motor used for transferring heads of a magnetic disk drive or an optical disk drive or the like. SOLUTION: In the voice coil motor which is provided with a pair of yokes 9, 10 facing in parallel each other at a prescribed interval, an annular movable coil which is movably arranged within the pre-determined coil movable range 14 along the yoke between the yokes, and a two-pole magnetized permanent magnet 12 which is attached to one side yoke 10 and imparts a magnetic field to the movable coil, differences in level are formed in the opposite direction of the permanent magnet 12 in the yoke 9 of the side to which the permanent magnet 12 is not attached toward the outside from the vicinity of the terminal end parts of the coil movable rang 14 on the surface facing the permanent magnet 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil motor used for moving a head such as a magnetic disk drive or an optical (or magneto-optical) disk drive. When a magnet is provided, the magnetic flux applied to the movable coil is perpendicular to the coil moving direction.

[0002]

2. Description of the Related Art An example of a conventional voice coil motor will be described below. In FIG. 6, reference numerals 30 and 31 denote plate-like yokes which face each other in parallel at a predetermined interval 36, and 32a and 32b are arranged so as to be movable along the yoke gap 36 along the yokes 30, 31. Reference numeral 33 denotes a permanent magnet which is attached to one yoke 31 between the yokes and applies a magnetic field to the movable coil. The permanent magnet 33 is magnetized in two poles as shown in the figure, and applies a magnetic flux 34 to the movable coil.
The movable coil is wound so that when a current flows through the winding portion 32a from the front to the back of the drawing, the current flows through the winding portion 32b from the back to the front. When a current is applied to the movable coil as described above, a force is generated in the movable coil according to Fleming's left hand rule,
The movable coil moves in the direction of arrow 37. When a current in the opposite direction flows, the movable coil moves in the direction opposite to the arrow 37. The movable coil is set by a stopper (not shown) so that only the coil movable range 35 can be moved.

[0003]

However, in the above configuration, near the end of the coil movable range 35, the magnetic flux generated by the permanent magnet 33 is not perpendicular to the coil moving direction. As a result, when the movable coil is near the end of the movable range, a force is generated in the movable coil in a direction perpendicular to the moving direction. On the other hand, the movable coil is mounted on an actuator to which a magnetic or optical head is attached, and this actuator has a natural vibration mode in a direction perpendicular to the direction of movement of the coil. The actuator oscillates when a force in a direction perpendicular to the coil moving direction excites the natural vibration mode. This vibration has a problem in that recording or reproduction of a magnetic or optical recording device is hindered and acoustic noise is increased.

Further, since the magnetic flux generated by the permanent magnet is not uniform near the end of the movable range of the coil and in the center of the movable range, the generated force is not uniform. As a result,
In addition, there is a problem that the control characteristics of the data are different between the vicinity of both ends and the center, which hinders the recording and reproduction of the apparatus.

[0005]

In order to solve the above-mentioned problems, a voice coil motor according to the present invention comprises a permanent magnet and a permanent magnet attached to a surface of the yoke on which the permanent magnet is not attached. A step is formed in the opposite direction.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Claims 1 to 3 of the present invention
The voice coil motor described in (1) is a voice coil motor having a permanent magnet magnetized in two poles, wherein the yoke on the side where the permanent magnet is not attached has a coil movable range on a surface facing the permanent magnet. By providing a step from the vicinity of the end to the outside in the direction opposite to the permanent magnet, the magnetic path near the end of the movable range of the coil is elongated. According to this configuration, the yoke has a higher magnetic permeability than air, and the magnetic flux has a shorter magnetic path and goes to the higher magnetic permeability. As a result, the magnetic flux near the coil movable range is also close to a right angle to the coil moving direction. In other words, the problem can be solved. Further, by making the shape of the step incline outward, processing becomes easier.

Next, claims 4 to 6 of the present invention will be described.
The voice coil motor described in (1) above is a voice coil motor having a permanent magnet magnetized in two poles, in which two poles are magnetized on a surface facing the permanent magnet of the yoke on which the permanent magnet is not attached. By providing a step near the neutral point of the pole of the permanent magnet in the direction opposite to the permanent magnet coil, the magnetic path near the neutral point of the pole of the permanent magnet is lengthened. According to this configuration, the yoke has a higher magnetic permeability than air, and the magnetic flux has a shorter magnetic path and goes to a higher magnetic permeability. As a result, the magnetic flux is close to a right angle to the coil moving direction, thereby solving the problem. can do. Further, by inclining the shape of the step toward the outside, it becomes easy to process and the leakage of magnetic flux can be reduced.

Next, a voice coil motor according to a seventh to ninth aspect of the present invention is a voice coil motor having a single-pole-magnetized permanent magnet. By providing a step in the opposite direction from the end of the coil movable range on the surface facing the permanent magnet from the end of the movable range of the coil to the outside, the magnetic path near the end of the movable range of the coil is lengthened. According to this configuration, the yoke has a higher magnetic permeability than air, and the magnetic flux has a shorter magnetic path and goes to a higher magnetic permeability. As a result, the magnetic flux is close to a right angle to the coil moving direction, thereby solving the problem. can do.
Further, by making the shape of the step incline outward, processing becomes easier.

(Embodiment 1) Next, an embodiment of the invention described in claims 1 to 3 of the present invention will be described with reference to FIG.

In FIG. 1, reference numerals 9 and 10 denote predetermined intervals 15
Are plate-shaped yokes facing each other in parallel with each other,
Numerals 11a and 11b denote winding portions of an annular movable coil wound movably along the yoke in the air of the gap 15, and 12 is attached to one yoke 10 between the yokes and is movable. A plate-shaped permanent magnet that applies a magnetic field to the coil. This permanent magnet is magnetized with two poles so as to have a neutral point at the center as shown in the figure.
Give 3. When a current flows from the front to the back of the drawing in the winding portion 11a of the movable coil, the winding is wound so that the current flows from the back to the front in the winding portion 11b. There is a case.

On the surface of the yoke 9 on which the permanent magnet 12 is not mounted, facing the permanent magnet 12, a step is provided in the direction opposite to the permanent magnet 12 from the vicinity of the end of the coil movable range 14 to the outside. The magnetic path near the end of the movable range of the coil is elongated by the step. According to this configuration, the yoke has a higher magnetic permeability than air, and the magnetic flux 13 has a shorter magnetic path and goes to a higher magnetic permeability. As a result, the magnetic flux 13 becomes close to a right angle to the coil moving direction even near the end of the coil movable range. The position of the step provided on the yoke is such that the direction of the magnetic flux impinging on the movable coil is closest to the right angle. Therefore, when the movable coil is located at the end of the movable range of the coil, the coils of the winding portions 11a and 11b of the coil on the movable range end side are used. The center of the width is most preferable, but from the center of the coil width at this time, in the coil moving direction, between minus half of the width of the winding portion and half of the width of the plus winding portion, that is, the coil 11a, 11b The effect can be expected even between the left end and the right end.

In this configuration, when a current is applied to the winding portion 11a from the front to the back of the drawing, a force is generated in the movable coil according to Fleming's left-hand rule, and the movable coil moves in the direction of arrow 16. If a current flows in the opposite direction to the winding part 11a, it moves in the direction opposite to the arrow. On the other hand, the movable coil is mounted on an actuator to which a magnetic or optical head is mounted, and this actuator has a natural vibration mode in a direction perpendicular to the coil moving direction. However, due to the effect of the yoke of the present invention, the magnetic flux generated by the permanent magnet becomes almost perpendicular to the moving direction of the coil, and almost no force is generated in the coil in the direction perpendicular to the moving direction. As a result, the actuator does not vibrate in a direction perpendicular to the coil moving direction, and the apparatus operates normally.

Further, claims 1 to 3 of the present invention.
Another embodiment of the invention described in (1) will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the permanent magnet 12
The yoke 17 facing the coil is a yoke which is a feature of the present invention. The yoke 17 is inclined obliquely in the opposite direction to the permanent magnet 12 from the vicinity of the end of the coil movable range 14 toward the outside on the surface facing the coil. A step is provided. Due to this step, the magnetic path near the end of the coil movable range becomes longer as in the above-described embodiment, and the magnetic flux becomes close to a right angle to the coil moving direction.
The position of the step provided on the yoke 17 is such that the direction of the magnetic flux impinging on the coil is closest to the right angle, and therefore, when the movable coil is located at the end of the movable range of the coil, the coils of the winding portions 11a and 11b of the coil at the end of the movable range. The center of the width is most preferable. From the center of the width at this time, in the coil moving direction, between minus half of the width of the winding part and half of the width of the plus winding part, that is, the left ends of the coils 11a and 11b. It may be between the section and the right end. By making the shape of the step incline outward, processing becomes easier.

Further, claims 1 and 3 of the present invention.
Another embodiment of the invention described in (1) will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the permanent magnet 12
The total length of the yoke 18 on the side where no coil is provided is limited to near the end of the coil movable range 14, and a step is formed near the end of the coil movable range. As a result,
As in the above-described embodiment, the magnetic flux 13 near the end of the movable range of the coil is directed toward the yoke having a high magnetic permeability, and the magnetic flux is perpendicular to the direction in which the coil moves. The positions of both ends of the yoke are such that the direction of the magnetic flux impinging on the coil is closest to the right angle, so that when the movable coil is located at the end of the movable range of the coil, the coil width of the winding portions 11a and 11b of the coil on the movable range end side is determined. The center is most desirable, but from the center of the winding portions 11a and 11b, in the coil moving direction, between minus half the width of the winding portion and half the width of the plus winding portion, that is, the left ends of the coils 11a and 11b. The center of the width 11c of the winding portion is best even between the portion and the right end. However, the coil 11
It is also effective to provide between a left end and a right end of a and 11b.

(Embodiment 2) Next, an embodiment of the present invention described in claims 4 and 6 of the present invention will be described with reference to FIG. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, on the side of the yoke 20 on which the permanent magnet 12 is not provided, facing the permanent magnet 12, a permanent magnet is provided near the neutral point of the pole of the two-pole magnetized permanent magnet 12. A step is provided in a direction opposite to the magnet 12.
When the step 20a is provided and the cross-sectional area at the center of the yoke is too small and the magnetic flux leaks, the shape as shown by the broken line may be used. The step 20a allows the permanent magnet 12
The magnetic path near the neutral point of the pole becomes longer, and as a result, the magnetic flux becomes closer to a right angle to the coil moving direction. The position of the step 20a provided on the yoke 20 is such that the direction of the magnetic flux impinging on the movable coil is closest to the right angle, so that when the movable coil is located at the end of the movable range of the coil, the winding portions 11a, The center of the width of 11b is most desirable,
From the center of the winding portions 11a and 11b, in the coil moving direction, between minus half the width of the winding portion and half the width of the plus winding portion, that is, from the left end to the right end of the winding portions 11a and 11b. May be between. Further, by inclining the shape of the step toward the outside, it becomes easy to process and the magnetic flux leakage can be reduced.

(Embodiment 3) Next, an embodiment of the present invention described in claims 7 and 9 of the present invention will be described with reference to FIG.

In FIG. 5, reference numerals 21 and 22 denote plate-shaped yokes which face each other in parallel at a predetermined interval.
Numeral 3 is a yoke arranged at both ends to form a magnetic path. 24a, 24b are the yokes 21,
One of the yokes 21 is a winding part that penetrates and forms an annular movable coil movably disposed within a predetermined coil movable range 27 along the yoke 21.

A permanent magnet 25 is attached to one yoke 22 between the opposing yokes 21 and 22 and applies a magnetic field to the winding portion 24a of the movable coil. This permanent magnet 2
Reference numeral 5 denotes a single-pole magnetized magnet as shown in FIG. The movable coil is wound so that when a current flows from the front to the back of the drawing in the winding portion 24a, the current flows from the back to the front in the winding portion 24b. The drawing shows a case where the movable coil is at the left end of the coil movable range 27. On the surface of the yoke 21 on which the permanent magnet 25 is not provided and facing the permanent magnet 25, a step is provided in a direction opposite to the permanent magnet 25 from the vicinity of the end of the coil movable range 27 to the outside. Due to this step, the magnetic path near the end of the coil movable range becomes longer.

As a result, the magnetic flux becomes close to a right angle to the coil moving direction. The position of the step provided on the yoke 21 is most preferably the center of the width 24c of the winding portion 24a of the coil when the movable coil is located at the end of the movable range of the coil since the direction of the magnetic flux impinging on the coil is closest to the right angle. From the center of the winding portion 24a, in the coil moving direction, minus half the width 24c of the winding portion and the width 24 of the plus winding portion.
It may be between half of c, that is, between the left end and the right end of the winding part 24a.

When a current flows from the front to the back of the drawing in the winding portion 24a of the movable coil, a force is generated in the movable coil according to Fleming's left-hand rule, and the movable coil moves in the direction of arrow 29. If current flows through the coil in the opposite direction, it moves in the direction opposite to the arrow. On the other hand, the coil is mounted on an actuator to which a magnetic or optical head is mounted, and this actuator has a natural vibration mode perpendicular to the direction of movement of the coil. However, due to the effect of the yoke of the present invention, the magnetic flux generated by the permanent magnet becomes almost perpendicular to the moving direction of the coil, and almost no force is generated in the coil in the direction perpendicular to the moving direction. As a result, the actuator does not vibrate in a direction perpendicular to the coil moving direction, and the apparatus operates normally. Further, the processing is facilitated by inclining the shape of the step toward the outside.

[0024]

As described above, according to the voice coil motor of the present invention, the magnetic flux near the end of the movable range of the coil is made perpendicular to the moving direction of the coil, so that the vibration in the direction perpendicular to the moving direction of the coil of the actuator can be obtained. The advantageous effect of eliminating is obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a voice coil motor according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a voice coil motor according to another example of the first embodiment of the present invention.

FIG. 3 is a side sectional view showing a voice coil motor according to another example of the first embodiment of the present invention.

FIG. 4 is a side sectional view showing a voice coil motor according to a second embodiment of the present invention.

FIG. 5 is a side sectional view showing a voice coil motor according to a third embodiment of the present invention.

FIG. 6 is a side sectional view showing a conventional voice coil motor.

[Explanation of symbols]

9, 10, 11, 17, 18, 20, 20a, 21, 22, 23, 30, 31 Yoke 11a, 11b, 24a, 24b, 32a, 32b Coil winding section 11c Coil width 12, 25, 33 Permanent magnet 13 , 26, 34 Magnetic flux 14, 27, 35 Coil movable range 15, 28, 36 Gap 16, 29, 37 Coil moving direction

Claims (9)

[Claims] A pair of yokes opposed to each other in parallel at a predetermined interval, and an annular movable member arranged between the yokes and movable along a yoke within a predetermined coil movable range. In a voice coil motor including a coil and a two-pole magnetized permanent magnet attached to one yoke between the yoke and applying a magnetic field to the movable coil, a yoke on a side where the permanent magnet is not attached is provided. A step formed in a direction opposite to the permanent magnet on the surface facing the permanent magnet from the vicinity of the end of the movable range of the coil to the outside. 2. In the vicinity of the coil movable range end portion, when the center of the winding portion of the coil on the movable range end side is 0 when the movable coil is located at the coil movable range end, in the coil movable direction, 2. The voice coil motor according to claim 1, wherein the width of the voice coil motor is between half the width of the minus winding and half the width of the plus winding. 3. The voice coil motor according to claim 1, wherein the shape of the step is formed by an inclined surface inclined outward. 4. A pair of yokes facing each other in parallel at a predetermined interval, and an annular movable member movably disposed between the yokes along a yoke within a predetermined coil movable range. A voice coil motor comprising a coil and a two-pole magnetized permanent magnet mounted on one yoke between the yoke and applying a magnetic field to the movable coil, wherein the yoke on which the permanent magnet is not mounted is: A voice coil motor, wherein a step is formed near a neutral point of a pole of a two-pole magnetized permanent magnet on a surface facing the permanent magnet in a direction opposite to the permanent magnet. 5. The vicinity of the neutral point of the pole of the permanent magnet means that when the movable coil is located at the end of the movable range, the center of the winding portion of the movable coil located on the neutral point side of the permanent magnet is 0. 5. The voice coil motor according to claim 4, wherein in the coil movement direction, the width is between half of the width of the winding part and half of the width of the plastic winding part.
Ta. 6. The voice coil motor according to claim 4, wherein the shape of the step is formed by an inclined surface inclined outward. 7. A pair of yokes, which are opposed to each other in parallel at a predetermined interval and have a magnetic path formed at both ends thereof, and one of the yokes is penetrated, and is preliminarily formed along the yoke. An annular movable coil movably arranged within a predetermined coil movable range, and a single-pole magnetized permanent magnet attached to one yoke between the yoke and applying a magnetic field to the movable coil. In the voice coil motor provided, a step is formed on a side of the yoke on which the permanent magnet is not attached, from the vicinity of the end of the movable range of the coil to the outside on a surface facing the permanent magnet, in a direction opposite to the permanent magnet. A voice coil motor characterized by: 8. When the movable coil is located at the end of the coil movable range, the center of the winding portion of the coil at the end of the movable range is 0, and the vicinity of the coil movable range end is in the coil movable direction. 6. The voice coil motor according to claim 5, wherein the width is between half the width of the minus winding and half the width of the plus winding. 9. The voice coil motor according to claim 7, wherein the shape of the step is formed by an inclined surface inclined outward.