JPS60223093A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the generation of a thermal off-track, etc. and to improve the performance of a magnetic disk device by providing an elastic member between a lock member and a base plate assembly or an assembly of accessory parts to absorb the distortions due to a difference of heat expansion. CONSTITUTION:When the ambient temperature has a change, both a base plate assembly 2 and a printed base board assembly 3 of a magnetic disk device 1 are expanded toward arrow heads F1 and F2 respectively by the heat expansion. In this case, both assemblies 2 and 3 have different coefficients of heat expansion. A boss 10 gives the elastic deformation to an O-ring 11 within a hole 3b and at the same time has a relative shift within a range of a gap (d) even through the distortions are produced owing to the difference of heat expansion between both assemblies. Thus those distortions are absorbed to eliminate the generation of a thermal off-track. This improves the performance of a magnetic disk device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device that eliminates distortion caused by differences in thermal expansion.

[Prior art and its problems]

In recent years, as magnetic storage devices have become smaller, lighter, and more dense, magnetic disk drives have also undergone changes in the materials of their component parts, and efforts have been made to make them lighter and thinner, contributing to an increase in packaging density.

Conventionally, in a magnetic disk drive, in order to assemble a printed circuit board assembly, which is an example of an accessory assembly, to a base plate assembly (accommodating a magnetic disk and a magnetic head), a locking member is attached to each of a plurality of bosses provided on the base plate assembly. The screws were stuck in multiple places.

However, according to this, when the environmental temperature of the device changes, distortion occurs due to the difference in thermal expansion coefficient between the base plate assembly and the printed circuit board assembly, resulting in performance problems such as so-called thermal off-track. It has the disadvantage of causing negative effects.

[Purpose of the invention]

The present invention eliminates the above drawbacks by not directly fixing the base plate assembly and accessory parts assembly to the locking member, but by interposing an elastic member between them to absorb the strain caused by the difference in expansion. The purpose of the present invention is to provide a magnetic disk device with the following features.

[Structure of the invention]

To achieve this, the configuration of the present invention includes a base plate assembly that houses a rotatable magnetic disk and a magnetic head for recording and reproducing information on the magnetic disk, and accessories such as a control circuit. Instead of an accessory parts assembly that is fixed at a plurality of locations through respective locking members, the base plate assembly is provided by interposing an elastic member between the base plate assembly or the accessory parts assembly and the locking member described in 1 above. Alternatively, the elastic member is configured to absorb strain caused by a difference in thermal expansion between the accessory assembly and the locking member.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to the drawings.

Figures 1 and 03) are a partially cutaway plan view and a partially cutaway side view of an embodiment of the magnetic disk device according to the present invention, respectively, and Figure 2 is an enlarged vertical sectional view of the main parts of the device. be.

In the figure, the magnetic disk device assembly consists of a base plate assembly 2 and a printed circuit board assembly 3 as an accessory parts assembly.

The base plate assembly 2 has a plurality of magnetic disks 5 rotatably arranged therein on the same rotation shaft 4, and a magnetic head 7 of a head assembly 6 disposed movably in the radial direction of the magnetic disk 5. Compatible with disc 5. Also, the base plate assembly 2 has a plurality of boss parts 2 on the bottom surface.
It has a.

The printed circuit board assembly 3 has various circuit components 3a mounted on its lower surface and has a plurality of holes 3b (only one is shown in FIG. 2). This printed circuit board assembly 3 is attached to the base plate assembly 2.
To assemble it, first, as shown in FIG. 1 (Q3) and FIG. 2, six holes 3b are arranged below the base plate assembly 2 so as to correspond to each boss part 2a. Subsequently, in the 6-hole 3b,
A screw 8 as a locking member is screwed into the lower end of the boss portion 2a through the hole 3b with the washer 9, boss 101 and O-ring 11 interposed in this order. In this case, the value of the tightening torque of the screw 8 is set to a predetermined value.

Also, the outer diameter of the boss (0) is slightly smaller than the inner diameter of the hole 3b of the printed circuit board assembly 3, creating a radial gap d,
Furthermore, the flange of the boss 10 is in contact with the printed circuit board assembly 3 via the O-ring 11.

Next, the effect will be explained. When the environmental temperature changes, the base plate assembly 2 and the printed circuit board assembly 3 of the magnetic disk device 1 move as indicated by the arrows F1. F
It stretches in the z direction due to thermal expansion. However, the base plate assembly 2 and the printed circuit board assembly 3 have different coefficients of thermal expansion. Therefore, if there is no gap d in the O-ring 11,
For example, if the coefficient of thermal expansion of the base plate assembly 2 is larger than that of the base plate assembly 2, distortion will occur between the base plate assembly 2 and the base plate assembly 2, and the entire device 1 will deform into an arcuate shape with the upper part convex. Then, the relative position between the magnetic head 7 and the track of the magnetic disk 2 shifts, resulting in a so-called thermal off-track state in which accurate recording and reproduction cannot be performed.

In other words, in the case of the present invention, even if the distortion caused by the above-mentioned thermal expansion difference occurs, the boss IO is not inserted into the hole ab in the O-ring 11 as shown in FIG.
is elastically deformed while relatively moving within the range of the gap d, and as a result, the strain is absorbed. Therefore, performance can be improved without causing the thermal off-track.

〔Effect of the invention〕

As explained above, the present invention does not directly fix the base plate assembly and accessory parts assembly to the locking member.
Since an elastic member is interposed between them to absorb the strain caused by the difference in thermal expansion, there are advantages such as preventing the occurrence of thermal off-track, etc., and improving performance.

[Brief explanation of drawings]

FIG. 1 (5) and ω) are a partially cutaway plan view and a partially cutaway side view of an embodiment of the magnetic disk device according to the present invention, respectively, and FIG. 2 is an enlarged longitudinal section of the main parts of the device. It is a diagram. 1... Magnetic disk device 2... Base plate assembly 2a... Boss portion 3... Printed circuit board assembly 3b...
- Hole 5... Magnetic disk 6... Head assembly 7... Magnetic head 8... Screw lO... Boss 11... 0 ring Applicant NEC Corporation Figure 1 (A) (B ) Figure 2

Claims (1)

[Claims] It has a base plate assembly that houses a rotatable magnetic disk and a magnetic head for recording and reproducing information on the magnetic disk, and accessories such as a control circuit, and each has a locking member at a plurality of locations for the base plate assembly. An elastic member is interposed between the base plate assembly or the accessory parts assembly and the locking member, and the base plate assembly or the accessory parts assembly and the locking member are fixed together through the base plate assembly or the accessory parts assembly and the locking member. 1. A magnetic disk drive characterized in that the elastic member is configured to absorb strain caused by a difference in thermal expansion between the elastic member and the elastic member.