GB2178219A

GB2178219A - Magnetic head support assembly

Info

Publication number: GB2178219A
Application number: GB08616942A
Authority: GB
Inventors: Makoto Hirakawa
Original assignee: Victor Company of Japan Ltd; Nippon Victor KK
Current assignee: Victor Company of Japan Ltd; Nippon Victor KK
Priority date: 1985-07-12
Filing date: 1986-07-11
Publication date: 1987-02-04
Also published as: JPS6215165U; KR870002876U; GB8616942D0; KR900008860Y1

Abstract

A magnetic head support is swingably supported on a gimbal spring 26 mounted on a carriage 17, and is movable radially across a rotating flexible magnetic storage medium such as a magnetic storage disk, a torsion spring 34 acts on the carriage for normally urging the magnetic head resiliently toward the magnetic storage medium, and a spring-supported pivot pin 33 is coupled to the carriage via leaf spring 29 and held against the gimbal spring. The magnetic head is swingable on the gimbal spring about the tip of the pivot pin, the pin being resiliently movable for normally urging the magnetic head toward the magnetic storage medium. Through the combined action of the torsion spring, the gimbal spring, and the resiliently supported pivot pin, the magnetic head remains in stable, uniform, and intimate contact with the magnetic storage disk irrespective of disk surface oscillation or swaying over a wide range of frequencies. The cantilevered leaf spring (51) may be differently positioned (Fig. 9), and may be an L-shaped spring (55) (Fig. 13). <IMAGE>

Description

SPECIFICATION Magnetic head support assembly BACKGROUND OF THE INVENTION The present invention relates to a magnetic head support assembly having a magnetic read/write head for radially scanning a rotating magnetic storage disk to read data from and write data on the storage disk.

Many disk drives are used as computer peripherals for storing data on and retrieving data from magnetic storage disks employed as mass storage mediums in computer systems.

There are known rigid and flexible magnetic storage disks. The flexible magnetic disks are encased in plastic disk cartridges such as hard cases so that they can be handled and stored with ease. The flexible magnetic disks are widely used in the art since disk drives therefor are simpler than those for the rigid magnetic disks and also structures supporting magnetic read/write heads for the flexible magnetic disks are less expensive to construct.

The disk drives for the flexible magnetic disks are classified into two types. In one type, the disk drive includes a single magnetic read/write head disposed for slidingly contacting one side of a single-sided magnetic disk.

The disk drive of the other type has a pair of magnetic read/write heads disposed for slidingly contacting opposite sides, respectively, of a double-sided magnetic disk.

One conventional magnetic head support assembly for use in the disk drive for doublesided magnetic disks includes a lower carriage supporting a lower magnetic head and an upper carriage supporting an upper magnetic head and angularly movably connected to the lower carriage. The lower magnetic head is swingably supported on a gimbal spring mounted on the lower carriage, and the upper magnetic head is swingably supported on a gimbal spring mounted on the upper carriage.

The upper carriage includes an integral pivot arm having a pivot pin hed against the gimbal spring. The upper carriage is normally urged by a torsion spring to hold the upper magnetic head against a magnetic disk supported on a turntable. Therefore, while the magnetic disk is in rotation, the upper and lower magnetic heads are resiliently biased by the gimbal springs and the torsion spring to be kept in sliding contact with the both sides of the magnetic disk.

According to another conventional magnetic head support assembly, a gimbal spring which supports an upper magnetic head has an integral pivot pin held against an arm integrally projecting from an upper carriage that is resiliently urged by a torsion spring.

Magnetic disks available today have a maximum data storage area in order to meet demands for higher packing density and higher recording wavelengths. The innermost track position on such a magnetic disk is positioned closely to a metal or plastic hub bonded by an adhesive to the center of the disk. When bonding the hub to the disk, however, the disk is apt to become undulated or wavy near the disk center. When the wavy disk is rotated, the disk surface oscillates or sways in an axial direction thereof, producing forces tending to lift the upper magnetic head off the disk surface. To prevent the upper magnetic head from being brought out of contact with the magnetic head, the upper magnetic head is resiliently biased against the magnetic disk under the resilient force of the torsion spring acting on the upper carriage.The resilient force of the torsion spring is selected to be of such a level (generally in the range of from 15 to 20 grams) that is large enough to hold the upper magnetic head in contact with the magnetic disk, but small enough not to impair the durability of the magnetic disk and the upper and lower magnetic heads. However, since the combined mass of the upper carriage and the torsion spring is relatively large, the upper magnetic head cannot follow sharp disk surface unsulations or swaying, and hence is liable to bound from the disk surface upon hitting such an abrupt surface irregularity. The waveform envelope of a signal read out from the magnetic disk by the bounding magnetic head becomes uneven, as shown in FIG. 1#1 of the accompanying drawings, resuling in variations in the level of recorded and reproduced signals and sometimes in write and readout errors.

The disk surface undulations are larger toward the center of the magnetic disk as described above, and hence the disk surface oscillates to a larger extent near the disk center.

As the magnetic heads approach the disk center, they are forced by such larger disk surface irregularities out of intimate contact with the magnetic disk, thus lowering recording and reproducing characteristics due to spacing loss. One solution would be to increase the resilient force or spring constant of the torsion spring for forcibly holding the upper magnetic head against the magnetic disk thereby to eliminate the disk surface oscillation between the upper and lower magnetic heads. This would however cause the gimbal spring supporting the upper magnetic head to be deformed through the pivot pin on the upper carriage or the gimbal spring. The gimbal spring thus deformed would make the upper magnetic head less swingable with respect to the upper carriage to the extent that the upper magnetic head would not follow the disk surface roughness.Accordingly, recording and reproducing errors would be produced. Furthermore, the forced contact between the magnetic heads and the magnetic disk would reduce the service life thereof.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic head support assembly for supporting a magnetic read/write head so as to be kept in stable, uniform, and close sliding contact with a rotating magnetic disk irrespective of surface irregularities or swaying thereof.

According to the present invention, there is provided a magnetic head support assembly comprising a angularly movable carriage, a gimbal spring mounted on the carriage, a magnetic head swingably supported on the gimbal spring and movable radially across a rotating flexible magnetic storage medium, a spring acting on the carriage for normally urging the magnetic head resiliently toward the magnetic storage medium, and a pivot pin coupled to the carriage and held against the gimbal spring, the pivot pin being resiliently movable for normally urging the magnetic head toward the magnetic storage medium.

BRIEF DESCRIPTION OF THE DRA WINGS The present invention will be described in detail by way of illustrative example with reference to the accompanying drawings, in which; FIG. 1 is a top plan view of a magnetic disk drive in which a magnetic head support assembly according to the present invention is incorporated; FIG. 2 is side elevational view of the magnetic disk drive shown in FIG. 1; FIG. 3 is an enlarged bottom plan view of an upper carriage of the magnetic head support assembly; FIG. 4 is an enlarged top plan view of an upper carriage of the magnetic head support assembly; FIG. 5 is an enlarged plan view of a leaf spring; FIG. 6 is an enlarged side elevational view of the leaf spring; FIG. 7 is an enlarged top plan view of a torsion spring; FIG. 8 is a top plan view of a lower carriage of the magnetic head support assembly;; FIG. 9 is a side elevational view showing a magnetic head support assembly according to another embodiment of the present invention; FIG. 10 is a diagram illustrating how a magnetic disk swings in one cycle of rotation thereof; FIG. 11 is a diagram showing a waveform envelope of a signal reproduced by a conventional magnetic head support assembly; FIG. 12 is a diagram showing a waveform envelope of a signal reproduced by the magnetic head support assembly according to the present invention; and FIG. 13 is an enlarged side elevational view of a modified spring.

DETAILED DESCRIPTION Like or corresponding parts are denoted by like or corresponding reference characters throughout several views.

FIG. 1 shows a magnetic disk drive, generally denoted at 10, for use with double-sided magnetic storage disks, the disk drive including a stepping motor 11 with its output shaft supporting a pinion 12 meshing with a rack 13 attached to a lower carriage 14 (FIG. 2).

As shown in FIG. 2, the lower carriage 14 supports a lower magnetic read/write head 15 swingably mounted on one end thereof by a known gimbal spring 16 for sliding contact with the upper side of a magnetic disk D. An upper carriage 17 is attached at one end thereof to the lower carriage 14 by a leaf spring 18 fastened to the lower carriage 14 by a pair of bolts 19. The uppwer carriage 17 has a pair of lugs 20 on opposite lateral sides thereof, each lug 20 having a knob 21 projecting downwardly. The magnetic disk drive 10 includes a disk cartridge holder 22 disposed between the lower and upper carriages 14, 17 (FIG.2) and having on an inner end thereof a pair of arms 23 positioned below the lugs 20, respectively.When the magnetic disk D is to be loaded into and unloaded from the magnetic disk drive 10, the disk cartridge holder 22 is displaced away from the lower carriage 14 to cause the arms 23 to push the respective lugs 21 upwardly (FIG. 2), thus angularly moving the upper carriage 17 to the two-dot-and-dash-line position against the resiliency of the leaf spring 18 which is bent at 24.

An upper magnetic read/write head 25 is swingably mounted by a gimbal spring 26 on the distal end of the upper carriage 17 in vertical alignment with the lower magnetic read/write head 25 for sliding contact with the upper side of the magnetic disk D. As shown in FIG. 3, the gimbal spring 26 is disposed in a hole 27 defined in the upper carriage 17 and bonded at four corners thereof by adhesive deposits 28.

As illustrated in FIGS. 1 and 2, a leaf spring 29 is fastened in a cantilevered fashion by a screw 30 to the upper carriage 17. More specifically, as shown in FIGS. 4, 5 and 6, one end 31 of the leaf spring 29 is secured to a support tongue 32 of the upper carriage 27 which projects from an edge of the hole 27 close to the distal end of the upper carriage 27 into the hole 27 over the gimbal spring 26. The leaf spring 29 has a pivot pin 33 mounted on the opposite end thereof and projecting downwardly into abutment against the gimbal spring 26 where the upper magnetic head 25 is attached, so that the magnetic head 25 will swing on the gimbal spring 26 about the tip of the pivot pin 33 which contacts the gimbal spring 26. The leaf spring 29 normally urges the pivot pin 33 to turn clockwise (FIG. 2) about the secured end 31.

The upper carriage 17 is normally urged to turn counterclockwise about the portion 24 by a torsion spring 34 (FIGS. 1, 2, 5 and 7) having one end 35 engaging the upper carriage 17 through a block 36 and an opposite end 37 coiled and supported by a shaft 38 fixed with respect to the lower carriage 14.

As shown in FIG. 8, the gimbal spring 16 on the lower carriage 14 is disposed in a hole 39 defined in the upper carriage 14 and bonded at four corners thereof by adhesive deposits 40.

In operation, the magnetic disk D is loaded into the disk drive 10 and placed on a turntable 41 (FIG. 1). While the magnetic disk D is being rotated by the turntable 41, the upper and lower magnetic read/write heads 15, 25 are radially moved across the magnetic disk D in sliding contact therewith to write data on and read data from the magnetic disk D.

Where the magnetic disk D has surface undulations or warpage, it vertically swings or oscillates as shown in FIG. 10 to cause the upper magnetic head 25 to be displaced vertically during rotation of the magnetic disk D.

For vertical displacement of relatively high frequencies, the magnetic head 25 is resiliently pressed downwardly by the pivot pin 33 of the leaf spring 29 so as to remain in contact with the upper surface of the magnetic disk D while at the same time the magnetic head 25 is allowed to move swingably on the gimbal spring 26 with respect to the upper carriage 17. Therefore, the magnetic head 25 can vertically follow surface undulations of the magnetic disk D at high frequencies. Since the leaf spring 29 including the end 31 and the pivot pin 33 has a relatively small mass, it permits the magnetic head 25 to keep close contact with the magnetic disk D even when the magnetic head 25 encounters sharp or sudden surface irregularities or swaying of the disk D.

For vertical displacement of relatively low frequencies, the magnetic head 25 is maintained in intimate contact with the magnetic disk D under the resilient forces of the torsion spring 34 acting on the upper carriage 17. Because the leaf spring 29 is provided for additional biasing on the magnetic head 25, the torsion spring 34 may be designed to reduce its resilient forces or spring constant which would otherwise be required to be large for preventing the magnetic head 25 from bounding.

Through the combined action of the leaf spring 26, the torsion spring 34, and the gimbal 26, therefore, the magnetic head 25 is resiliently kept in stable, uniform, and close sliding contact with the magnetic disk D irrespective of surface undulations or vertical swinging movement of the magnetic disk D over a wide range of frequencies.

As a consequence, the upper and lower magnetic heads 15, 25 remain even sliding contact with the rotating magnetic disk D without any spacing loss caused there between, so that the recording and reproducing characteristics of the magnetic heads 15, 25 will not be lowered. FIG. 12 shows, by way of example, the waveform envelope of a signal which is read out by the magnetic heads 15, 25. With the arrangement of the present invention, recorded and reproduced signals are subject to reduced level variations, and no write and readout errors will be produced. In addition, inasmuch as the magnetic disk D and the magnetic heads 15, 25 can be held in contact with each other without increasing the resiliency of the torsion spring 34, their frictional wear is small and their service life is not reduced thereby.

FIG. 9 illustrates a modified magnetic disk drive 50. The magnetic disk drive 50 differs from the magnetic disk drive 10 shown in FIG.

1 in that the gimbal spring 26 is normally biased by a cantilevered leaf spring 51 with one end 52 thereof secured to a support tongue 53 of the upper carriage 27 which projects from an edge of the hole 27 remote from the distal end of the upper carriage 17 into the hole 27 over the gimbal spring 26.

The leaf spring 51 has a pivot pin 54 mounted on the opposite end thereof and projecting downwardly into abutment against the gimbal spring 26 where the upper magnetic head 25 is attached. The leaf spring 51 normally urges the pivot pin 54 to turn counterclockwise (FIG. 9) about the secured end thereof.

According to a modification shown in FIG.

13, an L-shaped spring 55 in the form of a rod may be used to bias the upper magnetic head, the spring 55 having an end 56 to be secured to the upper carriage and a bent opposite end 57 serving as a pivot pin to rest on the gimbal spring for urging the upper magnetic head against the magnetic disk.

Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.

Claims

1. A magnetic head support assembly comprising: a angularly movable carriage; a gimbal spring mounted on said carriage; a magnetic head swingably supported on said gimbal spring and movable radially across a rotating flexible magnetic storage medium; a spring acting on said carriage for normally urging said magnetic head resiliently toward the magnetic storage medium; and a pivot pin coupled to said carriage and held against said gimbal spring, said pivot pin be ing resiliently movable for normally urging said magnetic head toward the magnetic storage medium.

2. A magnetic head support assembly ac cording to claim 1, further including a leaf spring having one end attached to said carriage and an opposite end supporting said pivot pin.

3. A magnetic head support assembly according to claim 2, wherein said carriage has a hole defined therein and a support tongue projecting from an edge of the hole close to a distal end of the upper carriage, said gimbal spring being disposed in said hole, said one end of the leaf spring being mounted on said tongue.

4. A magnetic head support assembly according to claim 2, wherein said carriage has a hole defined therein and a support tongue projecting from an edge of the hole remote from a distal end of the upper carriage, said gimbal spring being disposed in said hole, said one end of the leaf spring being mounted on said tongue.

5. A magnetic head support assembly according to claim 1, further including a substantially L-shaped spring having one end attached to said carriage and an opposite end serving as said pivot pin.

6. A magnetic head support assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.