JPS6235177B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device that uses a flexible disk as a recording medium.

In general, magnetic disk devices that use a flexible disc such as a magnetic sheet as a recording medium are inexpensive because the recording medium can be manufactured using the same process as magnetic tape. can be converted into

FIG. 1 is a sectional view showing a part of a conventional magnetic disk device of this type, in which a flexible disk 1 is attached to a rotating shaft 2, and a back plate 3 having a plane facing the flexible disk 1 is placed on the surface of the back plate 3. and rotate the magnetic head structure 4.
The structure is such that information is recorded and reproduced by bringing the disc close to the flexible disc 1.

However, conventional magnetic disk devices of this type have the following drawbacks.

Since the back plate 3 does not rotate, the viscous frictional force of the air between the flexible disc 1 and the back plate 3 is large, resulting in a large torque loss.

If the flexible disc 1 is thin and has low rigidity, wrinkles may occur due to friction with the back plate 3 when rotation is started.

When a large number of flexible discs 1 are mounted coaxially with the rotary shaft 2, a back plate 3 must be installed on each of them in a non-rotatable manner, which complicates the structure.

In addition, a rotating rigid disc is used instead of a fixed back plate, and the outer periphery of the rigid disc is raised, and a flexible disc is glued to that part, pressed with a fixing member, or brought into close contact with it by air suction. , there is a conventional structure in which both disks are rotated as one.
If these structures are used, the above-mentioned drawbacks can be solved, but the following drawbacks arise.

Thermal expansion forces between the rigid disk and the flexible disk cause the flexible disk to sag or develop excessive tension, making information recording and reproduction unstable.

In the case of adhesives, there is a risk of the adhesive peeling off.

In the case of press contact or close contact, the structure becomes complicated.

This invention was made in order to eliminate these drawbacks, and by arranging a flexible disc to face a rigid disc and rotating them as one, the back plate is unnecessary and the rigid disc is flexible. The outer periphery of the disk can be held without contact with a narrow gap by air flow. The present invention will be explained in detail below with reference to the drawings.

FIG. 2 is a sectional view showing a part of a magnetic disk device showing an embodiment of the present invention, in which a flexible disk 1
is fixed coaxially with the rigid disk 5 by a presser ring 6, and these are attached to the rotating shaft 2 as one body. A shallow annular recess 7 is formed on the surface of the rigid disc 5 facing the flexible disc 1, and a ventilation hole 8 communicating with the outside air is provided on the inner peripheral side of the annular recess 7. ing.

Next, the operation will be explained. When the rotary shaft 2 is rotated, the flexible disk 1 is tensioned outward in the radial direction by centrifugal force, and rotates in a substantially flat state. On the other hand, although centrifugal force also acts on the air inside the annular recess 7, the rigidity of the flexible disc 1 itself
A very narrow gap 9 is formed between the outer peripheries of the flexible disk 1 and the rigid disk 5 due to the fluid force caused by the rotating airflow present on the upper surface of the disk. Since the flow path resistance due to this gap 9 is large, the amount of air leaking to the outer circumference of the annular recess 7 is small, and the air between the flexible disk 1 and the rigid disk 5 has a slightly positive pressure. Further, air to compensate for this leakage amount flows in through the vent hole 8. The gap in the annular recess 7 is several millimeters or less, and the air in that area is the boundary layer itself in the rigid disk 5 and flexible disk 1, so it does not cause turbulence and does not cause abnormalities in the flexible disk 1. It will not vibrate. In addition, an air flow is generated on the upper surface of the flexible disc 1 due to rotation, and when the rotation speed is high, it often becomes a turbulent state, but the thin air between the flexible disc 1 and the rigid disc 7 The viscous damping force of the membrane suppresses abnormal vibrations of the flexible disk 1 due to the turbulent flow.

By installing a magnetic head structure 4 attached to an arm 10 on the upper surface of the flexible disk 1, stable information recording and reproduction can be performed.

FIG. 3 shows that in the embodiment shown in FIG. 2, the shallow annular recess 7 provided on the surface of the rigid disk 5 facing the flexible disk 1 is not uniform, but is made shallower in the outward radial direction. This is an example, whereby the flexible disk 1 rotates in a state closer to a plane. It should be noted that the magnetic head structure 4 and arm 10 in the embodiment shown in FIG. 2 are omitted in FIG. 3 as well as FIGS. 4 and 5 which will be described later.

FIG. 4 is a cross-sectional view showing a part of a magnetic disk device showing another embodiment of the present invention, in which one flexible disk 1 is attached to each side of a rigid disk 5 by a retainer ring 6, and the rotating shaft is Fix it coaxially to 2. The inner diameter of the rigid disc 5 is provided with several ventilation holes 8 on the circumference to allow air to flow, and shallow holes are provided on the surface of the rigid disc 5 facing the flexible disc 1. A circular annular recess 7 is formed to produce an effect similar to that of the embodiment shown in FIG. 2 above. According to this embodiment, the recording area can be increased without complicating the structure.

FIG. 5 is a sectional view showing a part of a magnetic disk device showing still another embodiment of the present invention, in which a rigid disk 5 and a flexible disk 1 are each formed into a pair and stacked coaxially. Similarly to the embodiment shown in FIG. 4, a vent hole 8 is provided to allow air to flow from the inner diameter portion.

In any of the above embodiments, a stable flying clearance for the magnetic head can be obtained with respect to the magnetic head structure 4 fixed to the arm 10 shown in FIG.

Note that by changing the depth and the slope of the bottom surface of the annular recess 7 in each of the above embodiments, the surface shape of the flexible disk 1 during rotation can be changed as appropriate.

As explained above, this invention eliminates the need for a back plate, reduces friction loss because the flexible disk and rigid disk rotate as one, and fixes the flexible disk to the outer periphery of the rigid disk. Since there is no sagging or excessive tension, there is an advantage that it can be realized with a simple structure even when a large number of sheets are attached coaxially.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a part of a conventional magnetic disk device using a flexible disk, and FIG. 2 is a sectional view showing a part of a magnetic disk according to an embodiment of the present invention.
3 is a sectional view showing another shape of the annular recess in the embodiment shown in FIG. 2, FIG. 4 is a sectional view showing a part of a magnetic disk device showing another embodiment of the present invention, and FIG. 5 FIG. 2 is a sectional view showing a part of a magnetic disk device showing still another embodiment of the present invention. In the figure, 1 is a flexible disk, 2 is a rotating shaft, 4 is a magnetic head structure, 5 is a rigid disk, 6 is a presser ring, 7 is an annular recess, 8 is a ventilation hole, 9 is a gap, and 10 is a It is an arm.

Claims (1)

[Claims] 1. In a magnetic disk device using a flexible disk as a recording medium, a rigid disk facing the flexible disk and coaxially rotating as one unit is provided, and a surface of the rigid disk facing the flexible disk is provided. An annular recess is provided, and a ventilation hole is provided in the inner diameter portion to communicate the annular recess with outside air, and the air that enters through the ventilation hole is discharged from the opposing outer periphery of the flexible disk and the rigid disk. A magnetic disk device characterized in that the opposing surfaces form a narrow gap in a non-contact manner at the outer periphery.