JPH01113966A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To suppress a resonance vibration and to execute a head positioning with high accuracy by constituting an arm part practically unsymmetrically to a center line. CONSTITUTION:A magnetic recording medium 1 to record information data is laminated in four pieces and fixed by a hub 2 of a revolving spindle motor. A magnetic head 5 to execute a record reproducing is fixed to the tip part of a head supporting body 6, which is a flexible spring member, and fixed to a head arm 7 for head positioning. In one part of the head arm 7, a notching part 9 is obtained to be unsymmetrical to the center line which connects a pivot center and the head 5. Thus, the resonance vibration of the head arm 7 is prevented and the head 5 can be exactly positioned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic disk devices, and is particularly suitable for high-speed, high-density devices.

[Conventional technology]

A conventional device of this type is one such as US Pat. No. 4,620,255.
As disclosed in the specification of No. 1, the actuator section consisting of a slider, a support body, and an arm section has a symmetrical structure with respect to its center line.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into account the vibration characteristics of the arm or between the plurality of arm parts.

This has been an obstacle in positioning the head with high precision.

An object of the present invention is to enable highly accurate head positioning by suppressing resonance vibration between a plurality of arm sections.

[Means for solving problems]

The above object is achieved by changing the cross-sectional shape of the head arm portion to which the head support is fixed for each arm.

[Effect]

If the shapes of the plurality of arm parts are all the same, each natural frequency will also be the same, and if one arm begins to vibrate, the other arms will also resonate and vibrate. Once resonant vibrations begin, their amplitude increases and adversely affects head positioning. Therefore.

In order to change the natural frequency of each arm, the plate thickness distribution was changed in consideration of primary bending and primary torsion to prevent resonance vibration between the arms.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1X1 to 5. Figure m1 is a plan view showing the magnetic disk device according to the present invention, Figure 2 is a sectional view of the laminated head arm shown in Figure 1, Figure 3 is a side view of the laminated head arm seen from the side, and Figure 4. Figure 5 is a cross-sectional view of the notch of the helad arm.
The figure is an explanatory diagram showing the resonance frequency of each notched head arm.

In FIG. 1, a magnetic recording medium 1 for recording information data
is a stack of four plates and fixed by a hub 2 of a one-rotation spindle motor. 5 is a magnetic head for recording and reproducing;
This magnetic head is fixed to the tip of a head support 6, which is a flexible spring member. 7 is a helad arm for positioning the head, 8 is a pivot shaft, and 4 is a voice coil motor for positioning and driving the helad arm 7.

A part of the head arm 7 has a notch 9 that connects the pivot center and the head and is asymmetrical with respect to the center line. These actuator parts are the magnetic head 5.
The head support 6 provided in 1 is as follows.

The voice coil motor 4 is attached to the tip of the head arm 7 which is rotatably driven around the pivot shaft 8.
-0 FIG. 2 is a side view of the laminated head arm 7 viewed from the magnetic head side. Since there are four recording media, there are a total of eight magnetic heads from 5-1 to 5-8, and a total of eight head supports from 6-1 to 6-8. There are a total of five head arms 7-1 to 7-5 to which these head supports are fixed. FIG. 3 shows a side view of this head arm 7 viewed from the outer circumferential side of the recording medium. There is a notch near the center of the head arm 7, and a cross section of this is shown in FIG. The average thickness is t, but a portion of length t from one side is thinned to thickness t', and this length t is different for all five head arms.

Therefore, the resonant frequencies of the bending mode of the head arm and the torsional mode of the head arm are different. FIG. 5 schematically shows the resonant frequencies of the bending and torsional modes of all helad arms. This is because the cross-sectional shape of each head arm is different.

The natural frequencies are also different. That is, the larger the thin plate length t, the lower both the screw vibration frequency and the bending vibration frequency tend to be.

In this embodiment, at the moment when the head is positioned by the voice coil motor 4 in an evacuation motion, a large outward force is applied to each head arm, generating minute natural vibrations. However, since the natural frequencies of the five Herad arms are different, they do not resonate with each other and quickly attenuate. therefore.

The head is quickly and accurately positioned on the target track.

〔Effect of the invention〕

According to the present invention, since the structure of a plurality of head arms has different degrees of asymmetry and different natural frequencies,
This has the effect of preventing resonance vibration of the head arm and accurately positioning the head.

[Brief explanation of the drawing]

1 is a plan view of a magnetic disk device showing an embodiment of the present invention, FIG. 2 is a sectional view of the helad arm portion of the magnetic disk device of FIG. 1, and FIG. 3 is a side view of FIG. Figure 4 is the third
FIG. 5 is a sectional view of a head arm cutout, and FIG. 5 is a diagram showing the natural frequencies of head arms having different cutouts. 5... Magnetic head, 6... Head support, 7...
Head arm, 9...notch part. Agent Patent Attorney Katsuo Ogawa ・ゝ゛Paso No. 1 Figure 51 Eaves (Hezuto. 6 To, -/￥° Support Book 7 Hezudo Ryomuq t, 77 Missing y ■ 5 Inside the mouth compartment (C) 44 go

Claims (1)

[Claims] 1. Having an air bearing type slider and the slider on the tip side,
A flexible support body that has a pressing force against a rotating disk medium, an arm member that holds the support body at its tip and extends substantially in a straight line with the center line of the support body, and a head positioning device that includes a plurality of these arms. What is claimed is: 1. A magnetic disk device having an actuator, wherein the arm portion is configured substantially asymmetrically with respect to the center line. 2. A magnetic disk drive characterized in that the asymmetric arm portion according to claim 1 changes the torsional vibration center line with respect to its cross-sectional center line by changing the shape of its cross-sectional end for each laminated arm.