JPH0254480A - head access motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding the head access motor of a magnetic disk device, an optical disk device, etc. used as an external storage device of a computer system, for the purpose of enabling high-speed access, a magnetic head or an optical head is used. This is a magnetic head access motor for driving a head support mechanism that supports a magnetic head and seeks on a recording medium, and is equipped with bearings at both ends of a fixed shaft made of a magnetic material, and a magnetic head on the outer diameter surface of the fixed shaft between the bearings. A plurality of magnets are fixed, a rotor made of a magnetic material is supported by the bearing, and a plurality of coils, each of which is a flat coil shaped to form a part of a cylinder, are fixed on the inner diameter surface of the rotor. The magnet, fixed shaft, and rotor constitute a magnetic circuit, and a coil in the magnetic circuit generates torque.

[Industrial application field]

The present invention relates to a head access motor for a magnetic disk device, an optical disk device, etc. used as an external storage device of a computer system.

[Conventional technology]

FIG. 4 is a diagram showing a conventional magnetic disk device. This consists of multiple magnetic disks 2, which are recording media, inside a housing 1.
is attached to a shaft 3 that is rotationally driven by a motor, and a magnetic head 4 for writing or reading information on or from the magnetic disk 2 is supported by a carriage 7 via a support spring 5 and an arm 6. Reference numeral 7 allows the magnetic head 4 to be positioned on any desired track 8 of the magnetic disk 2.

As a head access motor for such a magnetic disk device or an optical disk device, a rotary access motor that can be designed relatively compactly and has a simple structure is generally used.

FIG. 5 is a diagram showing a conventional rotary access motor.

The magnetic head 4, support spring 5ζ arm 6 are supported on one side, and a coil 9 is attached to the other side of a rotatable carriage 7, and the coil 9 is arranged in an E-shape so that the magnetic flux crosses the conductor wire of the coil 9. iron core 10 and permanent magnet 11,
A magnetic circuit 13 consisting of 12 is arranged as shown by a two-dot chain line.

Then, by passing current through coil 9, arrow A or A'
It is designed to rotate in the direction.

[Problem to be solved by the invention]

In the above-mentioned conventional head access motor, the bobbin of the coil 9 is generally made of thin-walled resin, etc., so its rigidity is low, and the main resonance point of the vibration characteristics of the system is almost determined by this bobbin (generally, the bobbin has a frequency of 2 to 2 Hz). degree) High-speed access is difficult. Furthermore, if the rotation radius of the coil bobbin is increased in order to increase torque, there is a problem that the moment of inertia of the coil bobbin portion increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head access motor that has a small moment of inertia and a high natural frequency to enable high-speed access.

[Means for Solving the Problems] In order to achieve the above object, as shown in FIG. 1, the head access motor of the present invention includes a head support mechanism that supports a magnetic head or an optical head and seeks over a recording medium. A head access motor for driving the head access motor, which is equipped with bearings 22 and 22' at both ends of a fixed shaft 20 made of a magnetic material, and a plurality of magnets 2 on the outer diameter surface of the fixed shaft between the bearings.
3 is fixed, a rotor 24 made of a magnetic material is supported by the bearings 22 and 22', and a plurality of coils are formed such that a flat coil is formed on the inner diameter surface of the rotor 24 to form a part of a cylindrical shape. 25 is fixed, the magnet 23, the fixed shaft 20, and the rotor 24 constitute a magnetic circuit, and the coil 25 in the magnetic circuit generates torque.

[For production]

The fixed shaft 20 is the stator, and the carriage is the rotor 24.
By doing so, it is not necessary to provide a coil outside the carriage as in the conventional case, so the moment of inertia of the rotor is reduced, and high-speed access is possible.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, in which (a) is a longitudinal sectional view, and (b) is a sectional view taken along line bb in FIG. 1 (a).

In the figure, reference numeral 20 denotes a fixed shaft made of a magnetic material such as carbon steel or martenitic stainless steel, which is fixed to a housing 21, and has outer ring rotating bearings 22 at both ends.
A plurality of magnets 23 are adhesively fixed to the outer diameter surface of the shaft between the cough bearings 22 and 22'. Note that the fixed shaft 20 may be directly fixed to the base and cover of the device instead of the housing 21.

Further, 24 is a rotor (carriage) made of the same magnetic material as the fixed shaft, and the bearings 22, 22'
A plurality of coils 2 (two in the figure) are supported on the inner diameter surface by a flat coil formed to match the curvature of the inner diameter surface.
5 (see Figure 2) is fixed with adhesive. This rotor 2
A heft arm 26 is attached to a part of the outer diameter side of the head 4, and a magnetic head 27 is attached to the tip of the arm 26.

In this embodiment configured as described above, a magnetic circuit is configured by the magnets 22, 22' fixed shaft 20, and the rotor 24, so that the rotor 24 is rotated by passing a current through the coil 25 in the magnetic circuit. This allows the magnetic head 27 to seek the surface of the recording medium.

- When performing high-speed access to Jl, the inductance of the coil becomes a problem, but the increase in inductance in this example is suppressed to several tens of percent more than that of an air-core coil, so it is not a big problem (general iron-core coils). In addition, since there is no coil outside the rotor, higher rigidity and a higher resonance point can be obtained than before, and the generated torque /
By increasing the moment of inertia ratio, high-speed access becomes possible. Further, according to this embodiment, the number of parts is reduced, making it possible to downsize and reduce costs, and since the magnetic circuit is completely shielded by the rotor, there are advantages such as a reduction in leakage magnetic flux.

FIG. 3 is a diagram showing a modification of the embodiment of the present invention. The basic structure of the modification is exactly the same as the above embodiment, but the effective length of the magnet (effective length of the coil) is )
The difference is that a groove is formed on the inner diameter side of the rotor to accommodate the coil 25, and the bearings 22, 22' are attached via a sleeve 28 in order to increase the resistance. Note that this sleeve 28 is fixed to the rotor 24 by shrink fitting, press fitting, adhesive, or the like.

Although the above embodiment has been explained by taking a magnetic disk device as an example, it is of course applicable to an optical disk device as well.

〔Effect of the invention〕

As explained above, according to the present invention, when compared with the conventional example in terms of generated torque/moment of inertia, the generated torque is the same (the smaller radius compensates for the increase in coil length), but the moment of inertia is (The conventional bobbin is not required, and the conventional rotor is also required. However, in the present invention, the rotor must be made of magnetic material, and although it is heavier than the conventional product, the radius is small, so the moment of inertia is (small) As a result, even higher speeds are possible.

In addition, the rotor part is sleeve-shaped, making it possible to significantly improve the resonance point of the system compared to conventional bobbins.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a perspective view showing a coil of the embodiment of the invention, Fig. 3 is a sectional view showing a modification of the embodiment of the invention, and Fig. 4 is a diagram showing a modification of the embodiment of the invention. FIG. 5 is a diagram showing a conventional magnetic disk device, and FIG. 5 is a diagram showing a conventional rotary head access morph. In the figure, 20 is a fixed shaft, 21 is a housing, 22 and 22' are bearings, 23 is a magnet, 24 is a rotor, and 25 is a coil.

Claims (1)

[Claims] 1. A head access motor for driving a head support mechanism that supports a magnetic head or an optical head and seeks on a recording medium, comprising: a fixed shaft (20) at both ends made of a magnetic material; bearings (22, 22'), a plurality of magnets (23) are fixed to the outer diameter surface of the fixed shaft between the bearings, and a rotor (24) made of magnetic material is attached to the bearings (22, 22'). ), and a plurality of coils 25 shaped so that a flat coil becomes a part of the cylindrical shape on the inner diameter surface of the rotor (24).
fixed, the magnet (23), the fixed shaft (20),
A head access motor characterized in that a rotor (24) constitutes a magnetic circuit, and a coil (25) in the magnetic circuit generates torque.