JPH03201271A - Head positioning mechanism for magnetic disk device - 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 [Field of Industrial Application] The present invention relates to the structure of a magnetic disk device head positioning mechanism, and particularly to realizing high reliability of a swing type positioning mechanism using a VCM.

[Prior Art] As described in Japanese Utility Model Application Laid-Open No. 60-159566, a conventional device forms a coil and a bobbin that supports the coil independently, and adheres the bobbin and the coil.

Further, Japanese Patent Laid-Open No. 63-99756 discloses a VCM coil in which the coil is covered with a bobbin.

[Problems to be Solved by the Invention] The above-mentioned prior art has a problem in that the VCM coil is likely to break due to thermal stress. for example.

In a VCM coil where the bobbin and the coil are made of aluminum, the coefficients of thermal expansion are matched, and the coil is placed outside the bobbin, when current is passed through the coil, the temperature of the coil becomes higher than that of the bobbin. , shear stress is generated on the bonding surface between the bobbin and the coil, and force acts in the direction of increasing the gap between the bobbin and the coil. As a result, in severe cases, the coil may peel off from the bobbin, or repeated energization and de-energization of the coil may cause minute cracks in the adhesive layer between the bobbin and the coil, making the coil fixation unstable. This may seriously impede head positioning accuracy in a magnetic disk device using this VCM coil.

The same thing applies to VCM coils where the coil is covered with a bobbin, and if the coil is repeatedly energized and de-energized, a small gap will be created between the coil and the bobbin, causing damage to magnetic disk drives etc. that use this coil. This may seriously impede positioning accuracy.

An object of the present invention is to solve the above-mentioned problems and provide a highly reliable VCM coil.

[Means for Solving the Problems] In order to achieve the above object, in a VCM coil in which the expansion coefficients of the VCM coil support portion and the parts constituting the bobbin are made approximately equal, and the coil is disposed outside the bobbin, the bobbin is The coefficient of thermal expansion of the material constituting the coil is made larger than the coefficient of thermal expansion of the material constituting the coil.

In a VCM coil in which the coil is placed inside the bobbin, the coefficient of thermal expansion of the material that makes up the bobbin is determined by
The coefficient of thermal expansion should be smaller than that of the material to be cut.

Further, a member made of a material having a coefficient of thermal expansion between the bobbin and the coil is provided between the bobbin and the coil.

Furthermore, the member between the bobbin and the coil is an insulator.

[Function] Since the coefficients of thermal expansion of the VCM coil support and the parts that make up the bobbin are almost the same, thermal stress caused by temperature changes may cause deformation or weaken the bonding strength between the parts (for example, loosening of screws, etc.) There is no problem in head positioning accuracy.

Furthermore, by passing a current through the VCM coil, the coil generates heat, the temperature of the coil becomes higher than that of the bobbin, and a difference in thermal expansion occurs between the coil and the bobbin.

In this case, in a VCM coil in which the coil is placed outside the bobbin, by making the coefficient of thermal expansion of the material that makes up the bobbin larger than the coefficient of thermal expansion of the material that makes up the coil, even when the VCM coil is energized, The coils will come into close contact with each other, and compressive stress will be applied to the bobbin.

In addition, in a VCM coil in which the coil is placed inside the bobbin, the coefficient of thermal expansion of the material constituting the bobbin is made smaller than the coefficient of thermal expansion of the material constituting the coil, and the difference in coefficient of thermal expansion is reduced in the energized state of the VCM coil. However, the bobbin and coil come into close contact with each other, and compressive stress is applied instead.

As a result, when the VCM coil is energized, the coil and bobbin are in close contact with each other, so that the coil does not separate from the bobbin or the coil is not fixed unstable.

In addition, if the thermal expansion coefficients of the bobbin and coil are significantly different, by providing a member between the bobbin and the coil whose thermal expansion coefficient is between that of the coil and the bobbin, the thermal stress caused by temperature changes will be alleviated, and the bobbin and the coil will be The strength of the joints is ensured.

Furthermore, by using an insulator as the member between the coil and the bobbin, there is no deterioration of the edge characteristics due to thermal stress, and there is no possibility of short-circuiting between the bobbin and the coil.

[Example 1] Hereinafter, a vertical flat type VC which is an example of the present invention will be described.
A head positioning mechanism of a magnetic disk device using M coils will be described in detail with reference to the drawings.

FIG. 1 shows a vertical flat type VCM coil in which the coil is arranged outside the bobbin.

The VCM coil 3 in FIG. 1 has a structure in which the coil 2 is arranged outside the bobbin 1.

FIG. 2 is a configuration diagram of a head positioning mechanism of a magnetic disk device constructed using the VCM coil 3 of FIG. 1.

In Figure 2, VCM coil 3 and VCM magnet 4
This constitutes the VCM. The magnetic head 5 is supported by a VCM coil support section 8 via a support spring 6 and a head arm 7. The bobbin 1 has a coil support portion 101 and a V
It is composed of a connecting part 102 to the CM coil support part 8. Between the hub 9 and the clamp 11, there are a head arm 7, a coupling part 102, and an arm spacer 10. The hub 9 has a bearing 12 at one end, has a shaft shape at the other end, and the shaft end is supported by an inner ring of a bearing in a bearing holder 13. Bearing 12 inside hub 9
The inner ring of is supported by a shaft protruding from a base (not shown), and the bearing holder 13 is also fixed to the base,
As a result, the coil 2 of the CM coil 3 is supported by the bobbin 1 so as to be able to swing integrally with the helad arm 7. The VCM magnet 4 is composed of a yoke 14 and a magnet 15, and has a gap 16 inside thereof.

The VCM magnet 4 is connected to the VCM holder 17 via the VCM holder 17.
A base supporting the CM coil support section 8 (not shown)
Fixed. The actual VCM is VCM magnet 4
The VCM coil support part 8 and the VCM holder 17 are arranged so that the coil 2 of the VCM coil 3 is inserted between the gap 16 of the VCM coil support part 8 and the VCM holder 17.
is supported by the base. In the head positioning mechanism of this magnetic disk drive, bobbin 1. Head arm 7, hub 9, arm spacer 10. The clamp 11 is made of a material having substantially the same coefficient of thermal expansion, and the coil 2 is made of a material having a smaller coefficient of thermal expansion than the material of the member constituting the VCM coil support portion 8. Specifically, for example, the member constituting the VCM support part 8 is made of A1 alloy with a thermal expansion coefficient of 21 to 25 x 10-''/''C, and the coil 2 is made of copper wire with a thermal expansion coefficient of 16 to 17 x 10-'C. Form. In this case, the coil support part 10 of the bobbin]
When the bobbin 1 and the coil 2 are bonded with an epoxy adhesive, even when the temperature of the coil 2 reaches 140° C., the adhesive strength between the bobbin 1 and the coil 2 is sufficiently maintained and they are firmly fixed.

In addition, the object of the invention can also be achieved by forming the members constituting the VCM coil support part 8 from an Mg alloy with a thermal expansion coefficient of 26 to 28 x 10-r'/°C (7), and forming the coil 2 from copper wire. .

The same effect can be obtained even if most of the VCM coil support part 8 is made of A1 alloy, a part, for example, the bobbin 1 is made of PF resin whose thermal expansion coefficient matches that of A1 alloy, and the coil 2 is made of copper wire. Most of the members of the VCM coil support section 8 are made of Mg.
It can also be realized by forming the coil 2 from an alloy, a part from a PF resin whose thermal expansion coefficient matches that of the Mg alloy, and forming the coil 2 from a copper wire.

Further, in this embodiment, the VCM coil support section 8 is connected to the head arm 7, the bobbin head, the hub 9. Although the arm spacer 10 and the clamp 11 are formed individually and assembled together, it is also possible to form them integrally.

FIG. 3 shows another embodiment of the present invention, in which the vertical flat type VCM in FIG. 1 is replaced with a rectangular cylindrical type.
This is an example of a configuration of a head positioning mechanism of a magnetic disk device using a CM coil 3.

FIG. 4 is a diagram showing the VCM coil 3 of FIG. 3,
FIG. 5 is a diagram showing a cross section taken along line II in FIG. 4.

In this embodiment, the coil support portion 101 of the bobbin 1 and the coil 2
An insulating sheet 20 is provided between them. or.

The coil support portion 101 and the coupling portion 102 of the bobbin 1 are formed separately and are joined by screws, adhesive, or the like. Here again, the coupling portion 102 of the bobbin 1 forming the VCM support portion 8. Head arm 7° hub 9. arm spacer
10, Clamp 11 and coil support part 101 of bobbin 1
are made of a material having approximately the same coefficient of thermal expansion, and the coil 2 is made of a material having approximately the same coefficient of thermal expansion.
The insulating sheet 20 is made of a material that has a coefficient of thermal expansion smaller than that of the materials that make up the CM coil support part 8, and the insulation sheet 20 is made of a material that has a coefficient of thermal expansion that is between the material that forms the coil support part 101 and the material that forms the coil 2. to form.

Specifically, the parts constituting the VCM coil support part 8 and the coil support part 101 are made of A1 alloy, the coil 2 is made of copper wire, and the thermal expansion coefficient of the material of the insulating sheet 20 is set to 18 to 10.
2 Q x 10-”/C.

In addition, the parts constituting the VCM coil support part 8 and the coil support part 101 are made of Mg alloy, the coil 2 is made of copper wire, and the coefficient of thermal expansion of the material of the N edge sheet 20 is 18 to 25X1.
It can also be realized by setting it to 0-"/"C. Furthermore, the parts constituting the VCM coil support part 8 are made of A1 alloy or Mg alloy.
The coil 20 is made of copper wire, and the coil support part 101 is made of VC.
The same effect can be obtained even if the M coil support part 8 is made of a PF resin whose coefficient of thermal expansion is approximately the same as the material of the parts composing the coil support part 8.Instead of the insulating sheet 20, it has the same coefficient of thermal expansion and insulation properties as the insulating sheet 20. Coil support part 1 with paint or resin
The present invention can also be implemented by coating the surface of the coil 2 in the 01.

FIG. 6 shows an example of the configuration of a head positioning mechanism for a magnetic disk device showing still another embodiment of the present invention, in which a VGM coil 3 in which a coil 2 is arranged inside a bobbin 1 is used.

FIGS. 7 and 8 are diagrams showing a cross section taken along the line -■ in FIG. 6.

In FIG. 6, bobbin 1. By stacking the head arm 7° arm spacer 10 on the hub 9 and screwing it, the VC
It constitutes an M coil support section 8, and is swingably supported by a shaft 19 via a bearing (not shown) inside a hub 9. The shaft 19 has both ends or one end fixed to the base. This positioning mechanism is composed of a VCM coil 3 and a 70M magnet (not shown).
Activated in commercials. A 70M magnet is also directly or indirectly fixed to the base fixing the shaft 19. Here, the bobbin 1. which constitutes the VCM coil support part 8. Head arm 7, arm spacer 10. The hub 9 is made of a material with approximately the same coefficient of thermal expansion, and the coil 2 is made of a material with approximately the same coefficient of thermal expansion.
It is made of a material having a larger coefficient of thermal expansion than the material of the parts constituting the M coil support part 8. Specifically, stainless steel with a thermal expansion coefficient of 17 to 18X10-'/''C is used for the VCM coil support part 8, and stainless steel with a thermal expansion coefficient of 23 to 24 is used for the coil 2.
In this embodiment, the bobbin 1 and the coil 2 are formed separately and bonded together using an Al wire of This makes it possible to improve positioning accuracy during bonding.

In addition, as shown in FIG. 8, this can also be achieved by adding a step to the adhesive surface. In addition, in this embodiment, the VCM coil support section 8 includes the bobbin 1, the head arm 7, and the arm spacer 1.
0. Although the hub 9 and the hub 9 are formed separately and assembled together, the present invention can also be realized by integrally molding the hub 9.

[Effects of the Invention] According to the present invention, since the bobbin and the coil are tight even under high temperature conditions, it is possible to provide a highly reliable VCM coil.

[Brief explanation of drawings]

1 is a diagram showing a VCM coil of a head positioning mechanism of a magnetic disk device showing an embodiment of the present invention, FIG. 2 is a diagram showing a head positioning mechanism of a magnetic disk device using the VCM coil of FIG. 1, FIG. 3 is a diagram showing a head positioning mechanism of a magnetic disk device showing another embodiment of the present invention;
Fig. 4 is a diagram showing the VCM coil used in the head positioning mechanism of the magnetic disk device shown in Fig. 3, and Fig. 5 is a diagram showing the VCM coil shown in Fig. 4.
-■ A diagram showing a cross section, FIG. 6 is a diagram showing a head positioning mechanism of a magnetic disk device showing another embodiment of the present invention, and FIG.
This figure is a diagram showing the nn cross section of FIG. 6, and FIG. 8 is a diagram showing the nn cross section of FIG. 6, showing an alternative to FIG. 7. 1...Bobbin 2...Coil 3...VCM coil 4...VCM magnet 5...Magnetic head 6...Support spring Figure 4 Figure Figure ■ Figure A ¥! Figure 78

Claims (7)

[Claims] 1. A coil assembly comprising a bobbin and a coil wound around the bobbin, wherein the coil is made of a material having a coefficient of thermal expansion smaller than that of the bobbin. 2. A coil assembly comprising a coil and a bobbin that supports the coil, the coil being located inside the bobbin, characterized in that the coil is made of a material having a coefficient of thermal expansion larger than that of the bobbin. assembly. 3. 3. The coil assembly according to claim 1, further comprising a member interposed between the bobbin and the coil whose coefficient of thermal expansion is between the bobbin and the coil. 4. Claim 1, characterized in that the member has a coefficient of thermal expansion between the bobbin and the coil, and the member is formed of an insulator and is interposed between the coil and the bobbin. The coil assembly according to item 1 or 2. 5. Supporting the coil on the bobbin to form a VCM coil,
In a head positioning mechanism of a magnetic disk device that enables a head arm carrying a magnetic head to rotate around a predetermined rotation axis through the cooperative action of the VCM coil and a magnet, the head arm and the bobbin have a coefficient of thermal expansion. 1. A head positioning mechanism for a magnetic disk device, characterized in that the head positioning mechanism is formed of a material having substantially the same characteristics. 6. 6. A head positioning mechanism for a magnetic disk drive according to claim 5, wherein said coil is made of a material having a coefficient of thermal expansion smaller than that of said bobbin. 7. 6. A head positioning mechanism for a magnetic disk drive according to claim 5, wherein said coil is made of a material having a coefficient of thermal expansion larger than that of said bobbin.