JPH04243070A - Head actuator - Google Patents

Abstract

PURPOSE:To offer a head actuator having a large generation power and a magnetic flux density of center yoke difficult to saturate and further capable of performing high speed access with high efficiency, regarding the head actuator accessing read/write heads of a disk device used for outer storage device of a calculator, etc. CONSTITUTION:This head actuator is the one to drive the head 1 taking a rotary shaft 2 as the center in a disk storage device provided with the heads 1 for reading/writing the information on every recording medium and to move them to an objective track on the recording medium, and the part to generate the rotational force consists of more than one pair of voice coils 3 including a parallel plane vertical to the rotary shaft 2 of actuator and a magnetic circuit to make the voice coils 3 to generate a magnetic field, and the constitution is made in such a manner that the magnetic field in the opposite direction to the adjacent voice coils 3 is generated by the aforementioned magnetic circuit and currents in the opposite direction are made to flow in the adjacent voice coils 3 respectively.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head actuator, and more particularly to a head actuator for accessing read/write heads of magnetic disk devices, optical disk devices, etc. used as external storage devices for computers and the like. In recent years, the storage capacity of magnetic disk devices, optical disk devices, and the like used as external storage devices for computers has increased dramatically. For example, the recording density of hard disk devices that use magnetic disks as storage media has increased more than 10 times over the past 10 years, and the storage capacity of large-capacity devices has reached 1 GB/spindle.

[0002] The actuator of the head that reads and writes data on such a recording disk is generally a swing-type actuator that can rotate (swing) only within a predetermined angle and that can finely control the rotation angle. be done. As the recording capacity of disk devices has increased as described above, thinner, higher-performance disk devices are required.Therefore, head actuators are desired to be thinner and have high-speed head access performance.

0003

2. Description of the Related Art FIG. 5 shows the structure of a head actuator 50 called a flat coil type, which has been commonly used in the past. In the conventional flat coil type head actuator 50, an arm 53 corresponding to the number of magnetic disks is attached to a rotor 52 that swings around a rotating shaft 51. A magnetic head 55 provided at the tip reads and writes from and to the magnetic disk. A flat coil 56 is provided on the back side of the attachment surface of the arm 53 of the rotor 52, and a pair of stators 58 to which permanent magnets 57 are attached are provided so as to sandwich the flat coil 56 from above and below. Then, by energizing the coil 56, the rotor 52 swings, and the magnetic head 55 provided at the tip of the head support spring 54 accesses the magnetic disk.

However, although this flat coil type head actuator 50 has the advantage that the coil 56 is thin and has a simple shape, the efficiency of the coil 56 is poor (usually
0% or less) and the return portion R that does not generate force in the coil 56 has a large inertia, which is a major obstacle to high-speed access. Therefore, a voice coil type head actuator 60 as shown in FIG.
is used. This voice coil type head actuator 60 also has a rotor 6 that swings around a rotating shaft 61.
An arm 63 corresponding to the number of magnetic disks is attached to 2, and a magnetic head 65 provided at the tip of a head support spring 64 protruding from this arm 63 reads and writes on the magnetic disk. A coil 66 wound around a coil bobbin is provided on the back side of the mounting surface of the arm 63 of the rotor 62, and has a substantially E-shaped yoke with permanent magnets 67 attached to sandwich the coil 66 from above and below. A swing motor is configured with the stator 68 inserted. Then, by energizing the coil 66, the rotor 62
swings, and the magnetic head 6 at the tip of the head support spring 64
5 accesses the magnetic disk.

This voice coil type head actuator 60 is more efficient than the flat coil type head actuator 50 shown in FIG.

[0006]

However, the voice coil type head actuator 60 shown in FIG. 6 has the following problems. ■ To increase the force generated by the coil 66, it is necessary to increase the width W of the coil 66 in the movable direction to increase the magnetic flux, but in order to prevent saturation of the magnetic flux, the thickness of the center yoke 68a must be increased. need to be increased, resulting in a decrease in efficiency.

■ As shown in FIG. 7, the center yoke 6
Since 8a becomes the magnetic path of the two magnets, the center yoke 68
Since the magnetic flux density of a is easily saturated and cannot be made thin, the return portion 66a of the coil 66 that does not contribute to the generated force and parallel to the axis of rotation of the actuator becomes large, which also limits efficiency. (2) Since the coil 66 has a structure surrounding the center yoke 68a having high magnetic permeability, the inductance becomes large. Therefore, the rise time of the drive current (
(proportional to L/R) is slow and becomes an obstacle to high-speed access. The present invention solves the problems inherent to voice coil type head actuators, generates a large force, makes it difficult for the magnetic flux density of the center yoke to saturate, and enables high-speed access with high efficiency. The purpose is to provide a head actuator.

[0008]

[Means for Solving the Problems] The head actuator of the present invention achieves the above-mentioned object in a disk storage device having an information reading head for each recording medium for at least one recording medium. A head actuator that is driven around a rotational axis and moved to a target track on a recording medium, the part that generates rotational force including one or more pairs of voice coils including a parallel plane perpendicular to the rotational axis of the actuator; It consists of a magnetic circuit that generates a magnetic field in this voice coil, and this magnetic circuit is configured to generate a magnetic field in the opposite direction to the adjacent voice coil, and to cause current to flow in the opposite direction to each adjacent voice coil. It is characterized by Specifically, the magnetic circuit described above includes a center yoke that passes through one or more pairs of voice coils, a back yoke that faces parallel surfaces of the voice coils, and a center yoke and a back yoke. A side yoke is connected at both ends thereof, and a back yoke is attached to the center yoke side of the back yoke so as to face each of the voice coils, and is magnetized to generate a magnetic field in the opposite direction to the adjacent voice coil. It is characterized by being composed of a magnet.

[0009]

[Operation] According to the head actuator of the present invention, the voice coils that generate rotational force are located at multiple locations, and the magnetic circuit that generates a magnetic field in the voice coil generates a magnetic field in the opposite direction to the adjacent voice coil. As a result, the magnetic flux passing through the center yoke of the magnetic circuit is dispersed and the magnetic flux density of the center yoke is reduced, making it possible to reduce the thickness of the center yoke and making the head actuator thinner.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present invention, the coil is separated into two or more parts in order to increase the force generated by the coil without increasing the width of the voice coil. This embodiment will be explained using FIG. 1. FIG. 1 shows the configuration of the rotor side of a voice coil type head actuator 10 according to an embodiment of the present invention. In this embodiment, the head actuator 1
0 has a rotor 9 that swings around a rotating shaft 2, and arms 11 corresponding to the number of magnetic disks are attached to this rotor 9. Further, one or two head support springs 12 are provided on the tip side of the arm 11, and the magnetic head 1 is attached to the tip of the head support spring 12. As the rotor 9 rotates, the magnetic head 1 provided at the tip of a head support spring 12 protruding from the arm 11 reads and writes on a desired track of the magnetic disk. Furthermore, in this embodiment, the rotor 9
Two coils 3 wound around a coil bobbin are provided at a predetermined angle on the back side of the mounting surface of the arm 11.

FIG. 2 shows a magnetic circuit (stator) 4 of a voice coil type head actuator 10 according to an embodiment of the present invention.
This shows the configuration of The magnetic circuit 4 of this embodiment is
Equivalently one center yoke 5 passes through the plurality of voice coils 3 provided on the rotor 9, and is provided above and below the voice coil 3 so as to face the upper and lower parallel surfaces of the voice coil 3, respectively. Two back yokes 6 and
It is provided with two side yokes 7 that connect the center yoke 5 and the back yoke 6 at their respective ends, and on the surface of each back yoke 6 on the side of the center yoke 5, there is a groove for each voice coil 3. Two sets of four permanent magnets 8 are attached, each of which can exert a magnetic force. Note that the four permanent magnets 8 are magnetized so as to generate a magnetic field in the opposite direction to the adjacent voice coil 3.

FIG. 3 is a horizontal sectional view of the head actuator 10 in which the voice coil 3 of FIG. 1 is incorporated into the magnetic circuit 4 of FIG. 2. As shown in the figure, in the head actuator 10, the center yoke 5 is inserted into the hole of the voice coil 3 protruding from the rotor 9, and the permanent magnet 8 is positioned to sandwich the voice coil 3 from above and below. The magnetic circuit 4 is assembled so that the side yokes 7 are located at both ends of the back yoke 6 and the center yoke 5. In this head actuator 10, when the coil 3 is energized, the rotor 9 swings, and the magnetic head 1 at the tip of the head support spring 12 accesses the magnetic disk.

The number of voice coils 3 protruding from the back surface of the rotor 9, the mounting angle, the width of the voice coils 3, etc. may be determined as appropriate depending on the moving distance of the magnetic head 1, that is, the swing angle of the rotor 9. . In addition, in this embodiment, in order to alleviate the magnetic saturation of the center yoke 5, the coil 3 is divided into two as described above, and the permanent magnet 8 is also divided into two with a common center yoke 5. each coil 3
The magnetization directions of the magnetic gaps of the magnetic circuits 4 corresponding to the two are formed in opposite directions. That is, the coil 3 is divided into two or more parts having a common center yoke 5, and the magnetization directions of the magnetic gaps of the magnetic circuits 4 corresponding to the respective coils 3 are formed in opposite directions.

Specifically, as shown in FIG. 4, two sets of magnets 8 corresponding to the two coils 3 are magnetized in opposite directions. For example, the magnetic flux generated from the magnets 8a and 8a' passes through the magnetic gap MG and heads toward the center yoke 5, but half of it passes through the side yoke 7 and back yoke 6 and returns to the same magnets 8a and 8a', while the remaining half goes from the side yoke 5 to the adjacent magnets 8b and 8b. Flows in the direction of '. Similarly, the magnetic flux generated from the magnets 8b and 8b' passes through the back yoke 6, and half of it returns to the same magnets 3b and 3b' via the side yoke 7, center yoke 5, and magnetic gap MG, but the remaining half goes back to the back yoke 6. From the yoke 6 to the adjacent magnet 3a
, 3a'. By passing currents in opposite directions to the two coils 3, the rotor 9 can obtain a force in the rotational direction.

In this way, by reversing the polarity of the magnetic circuits 4 made up of the two sets of permanent magnets 8 and connecting them with the side yoke 7, half of the magnetic flux generated from each permanent magnet 8 is distributed between the two magnetic circuits. cancel each other out at the joint surface. As a result, the thickness of the center yoke can be reduced to 1/2 compared to the conventional one. In the above configuration, the two coils 3 can be connected either in series or in parallel. In either connection, currents in opposite directions flow through the two coils 3 surrounding the common center yoke 5, so the total inductance is significantly reduced. Therefore, the drive current rises quickly, allowing high-speed head access.

In the embodiment described above, the voice coil 3
Since the voice coil 3 is divided into two parts without increasing the width, the thickness of the center yoke 5 can be reduced to 1/2 compared to the conventional method in which the voice coil 3 is not divided. Half of the magnetic flux generated from 8 cancels out at the joint surface of the two magnetic circuits, making it possible to reduce the thickness of the center yoke by half compared to the conventional one. It can be reduced to 1/4 of that. Therefore, the return portion (
3a in FIG. 1) can be made smaller, improving efficiency.

Note that the magnetic circuit 4 can be divided into two parts at the portion shown by the two-dot chain line in FIG. 2, and assembly becomes easier by dividing the magnetic circuit 4 into two parts.

[0018]

[Effects of the Invention] As explained above, according to the present invention,
(1) A thin and highly efficient voice coil motor can be realized. (2) Since the inductance is small, the drive current rises quickly and high-speed head access can be achieved, making it possible to create a small, high-speed, low-power head actuator. The effect is that it can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a rotor side of an embodiment of a head actuator of the present invention.

FIG. 2 is a perspective view showing the configuration of the magnetic circuit side of an embodiment of the head actuator of the present invention.

FIG. 3 is a horizontal sectional view of one embodiment of the head actuator of the present invention.

FIG. 4 is an explanatory diagram illustrating the operation of the magnetic circuit of the head actuator shown in FIGS. 1 to 3;

FIG. 5 is a perspective view showing the configuration of a conventional flat coil head actuator.

FIG. 6 is a perspective view showing the configuration of a conventional voice coil type head actuator.

7 is an explanatory diagram illustrating the operation of the magnetic circuit of the head actuator shown in FIG. 6; FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Magnetic head, 2...Rotating shaft, 3...Voice coil, 4...Magnetic circuit, 5...Center yoke, 6...Back yoke, 7...Side yoke, 8...Permanent magnet, 9...Rotor, 10...One embodiment Head actuator, 11... Arm, 12... Head support spring,

Claims (3)

[Claims] [Claim 1] For at least one recording medium,
In a disk storage device equipped with an information reading head (1) for each recording medium, the head (1) is connected to a rotating shaft (
2) A head actuator that is driven around the head and moved to a target track on the recording medium, in which the part that generates rotational force has one or more pairs of parallel surfaces perpendicular to the rotation axis (2) of the actuator. Voice coil (3) and
It consists of a magnetic circuit (4) that generates a magnetic field in this voice coil (3), and this magnetic circuit (4) generates magnetic flux in the opposite direction to the adjacent voice coil (3), and (3) A head actuator characterized in that the head actuator is configured so that currents flow in opposite directions. 2. The head actuator according to claim 1, wherein the magnetic circuit (4) includes equivalently one center yoke (5) passing through the one or more pairs of voice coils (3). , a back yoke (6) facing parallel surfaces of the voice coil (3), a side yoke (7) that connects the center yoke (5) and the back yoke (6) at both ends thereof, and the back yoke. (
6) The voice coil (
3) A magnet (8) is attached to face each of the voice coils (3) and is magnetized to generate a magnetic field in the opposite direction to the adjacent voice coil (3). head actuator. 3. The magnetic head actuator according to claim 1, wherein each of the voice coils (3)
A head actuator characterized in that a magnetic circuit (4) corresponding to the magnetic circuit (4) is divided into two parts in a plane parallel to the rotation axis (2) of the actuator.