JPH01184684A - Magnetic recording disk - Google Patents

Abstract

PURPOSE:To prevent deformation by a temperature change by making a expansion coefficient isotropic and the same as the one of a disk base or slightly higher than it in a member of a ring shape to support the periphery of a circular magnetic recording sheet. CONSTITUTION:A magnetic recording sheet 12 of a video floppy or the like consists of a PET or the like, and a magnetic recording layer is formed at the one face. In the periphery of the sheet 12, an L type ring 50 of high flatness and a ring 60 to engage it are provided, and they hold the sheet 12. The ring 50 and 60 mold with a metal or a plastic. Then, the expansion coefficient is made to be isotropic and the same as the one of a disk base of the sheet 12 made of the PET or the like, or slightly higher than it. Thus, the deformation of the sheet 12 by the temperature change on the using or the keeping of a disk is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating magnetic recording medium, particularly to a magnetic recording disk using a flexible disk.

Traditionally, magnetic recording disks such as Videoflow 2P disks, which use flexible disks for recording and playback, have a disk base (made of PET, for example) that shrinks due to heat when stored in high-temperature locations. Further, there is a problem in that the disk base expands or contracts anisotropically due to changes in temperature and humidity in the environment in which the magnetic recording disk is used, resulting in so-called track misalignment. Further, in the case of a flexible disk, there is a problem in that when the disk is rotated, the surface runout of the disk becomes large, making it impossible to obtain a good head touch. These problems with magnetic recording disks using flexible disks have been an obstacle to creating higher density and more reliable systems.

One way to solve these problems is to create a magnetic disk that has almost the same characteristics as a fixed disk by arranging high-density magnetic media on the front and back sides of a plastic substrate that has the same coefficient of thermal expansion as an aluminum substrate. -11
Magnetic disks such as 9730 were proposed. However, all of these magnetic disks have a structure in which magnetic recording sheets are placed on both sides of the substrate, making it impossible to use both sides of the magnetic recording sheet, and due to the thickness of the magnetic disk. There was a problem in that the magnetic disk itself became larger. Furthermore, for example, in the case of a magnetic disk, a problem arises in that the head support mechanism of a conventionally used flexible disk cannot be used, as in the case of using a floating head mechanism of a hard disk.

the purpose The present invention overcomes these drawbacks of the prior art.

An object of the present invention is to provide a magnetic recording disk that is resistant to temperature changes and suppresses surface runout of the disk during driving.

&''11. According to the present invention, in a magnetic recording disk having a magnetic recording medium sheet made of a circular flexible sheet having an opening in the center, the magnetic recording disk has at least one ring on the outer periphery of the magnetic recording medium sheet. The ring-shaped member has an isotropic coefficient of thermal expansion, and is characterized in that the coefficient of thermal expansion is equal to or slightly higher than the coefficient of thermal expansion of the disk base of the magnetic recording medium sheet. It is something to do.

Section 1 ff1 Next, embodiments of the magnetic recording disk according to the present invention will be described in detail with reference to the accompanying drawings.

In the following embodiment, the present invention is applied to a video floppy of electronic still camera standard. A video floppy is a flexible disk in which a circular magnetic recording sheet is rotatably housed in a molded plastic package. Note that the mold package, which is a housing member, is not directly related to the present invention, and thus its illustration and description will be omitted in the embodiments shown below.

1 to 3 show a first example in which the present invention is applied to the above-mentioned video floppy.

The magnetic recording sheet 12 consists of a circular magnetic recording sheet made of a thin plastic material such as PET and has a small diameter of about 50 mm.A magnetic recording material layer is formed on one side of the sheet, and 50 track video signals are recorded on this. Recordable.

An opening is formed in the center of the magnetic recording sheet 12, and a center core 18 is disposed in this opening. Further, an opening 20 is formed in the center core 1B, and this opening 20
However, the sheet 12 is held by engaging with the tip of a spindle (not shown) which is a shaft for driving a magnetic disk in a magnetic disk recording mechanism or reproducing mechanism of an electronic still camera system in which this video floppy 10 is used. Ru.

On the outer periphery of the magnetic recording sheet 12, an L-shaped tongue 50 having high flatness and formed into an oval shape, and a ring 60 that engages with the L-shaped tongue 50 are disposed.

As shown in FIG. 2, the recording sheet 12 is held between an L-shaped hinge 50 and a ring 60. Further, the structure of the outer periphery of this magnetic recording sheet 12 will become clearer when looking at FIG. FIG. 3 shows a partially enlarged view of the magnetic recording sheet 12 taken along line BB as shown in FIG. The magnetic recording sheet 12 is set on the L-shaped swing 50, and the ring 60 is placed on the L-shaped swing 5.
It is clamped by engaging 0. In these figures, the thickness of the sheath 12 and the dimensions of the rings 50 and 80 are relatively exaggerated for clarity.

4 and 5 show a second example in which the present invention is applied to the video floppy described above. In the example shown in FIG. 1, the outer circumference of the magnetic recording sheet 12 is L-shaped 5.
0 and a ring 60, but in this example, the magnetic recording sheet 12 is fixed by being glued to the L-shaped hinge 50. magnetic recording sheet) 12 to C-
As is clear from the partially enlarged view taken at C (FIG. 5).

A magnetic recording sheet 12 is adhered to the lower part 100 of the step of the L-shaped portion of the L-shaped hinge 50.

Note that the L-shaped hinge 50 and ring 60 in the above embodiments are molded from metal or plastic and have a monoisotropic coefficient of thermal expansion.

The thermal expansion coefficient used is the same as that of the disk base such as PET of the magnetic recording sheet 12, or a value slightly higher than that of the magnetic recording sheet 12, for example 0.

If the temperature coefficient of the disk base is the median value of 8~25X 10-8 cm/"O, which is the standard for video floppies, that is, 17X 1G-6 cm/"0, then the thermal expansion coefficient of the ring is 17X 10-6 cm/° C Alloyha 17X 10-6+ 10% am/''O or less is used.

For reference, examples of conventionally used magnetic recording disks are shown in FIGS. 6 and 7.

In the magnetic recording disk of this example, an opening is formed in the center of a circular magnetic recording sheet 120 that is a flexible disk, a center core 180 is disposed in this opening, and an opening 200 is formed in the center core. This opening 20
The sheet is held by engagement with the tip of the spindle (not shown) of the electronic still camera system used. This conventional magnetic recording disk is made of disk-based (PET) material by storage at high temperatures.
) shrinks due to heat, and changes in temperature and humidity in the environment in which the magnetic recording disk is used can cause the disk base to expand or contract anisotropically, resulting in so-called track misalignment. Moreover, in the case of flexible disks, when the magnetic recording disk is driven, the surface runout of the disk becomes large, causing a problem that good head touch cannot be obtained. This is particularly true for small-diameter, high-speed rotating disks such as video floppies.

However, according to the magnetic recording disk according to the present invention, the outer periphery of the circular magnetic recording sheet 12, which is a flexible disk, has an isotropic thermal expansion coefficient, and the temperature expansion coefficient is different from that of the magnetic recording sheet 12. Base (PET
) has a thermal expansion coefficient that is the same as or slightly higher than that of Deformation of the magnetic recording sheet 12 due to temperature changes can be prevented. Furthermore, since the magnetic recording disk according to the present invention has a simple structure, it can be easily realized, and a conventional head support mechanism can be used as is.

In the above embodiment, an example was shown in which the present invention was applied to a video floppy according to the electronic still camera standard. However, instead of a video floppy according to the electronic still camera standard, a flexible disk is used, for example, where both sides of the disk can be recorded. Needless to say, the present invention can also be applied to magnetic recording disks such as those that do not include a center core or those that do not include a center core.

As described above, according to the present invention, the outer periphery of a circular magnetic recording sheet, which is a flexible disk, is supported by at least one ring-shaped member, and this ring-shaped member has an isotropic coefficient of thermal expansion. Moreover, the coefficient of thermal expansion is the same as or slightly higher than that of the disk space of the magnetic recording medium sheet, so it is 81% less likely to deform the magnetic recording sheet due to temperature changes during use or storage of the recording disk. Moreover, it is possible to suppress the surface runout of the magnetic recording disk when the disk is driven.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a magnetic recording disk according to the present invention, and FIG. 2 is a cross-sectional view showing a cross section of the Ti1 magnetic recording disk shown in FIG. 1 along a two-dot chain line AA. FIG. 3 shows the magnetic recording disk shown in FIG.
FIG. 4 is an external perspective view showing another example of the magnetic recording disk according to the present invention; FIG. 5 is an enlarged sectional view showing a partial cross section of the magnetic recording disk of FIG. 4; FIG.
An enlarged cross-sectional view showing a partial cross section in FIG. FIG. 6 is an external perspective view of a conventional magnetic recording disk, and FIG. 7 is a sectional view showing a cross section of the conventional magnetic recording disk shown in FIG. Description of main parts 12, Magnetic recording sheet 1B, Center core 20, Opening 50, L-shaped ring 80, Ring Patent applicant Fuji Photo Film Co., Ltd. Agent Takao Kitori Big Takao Qin 1 Figure Tail 2 Figure Wei 3 Figure Zhu 4 Figure Ice 5 Figure Weiro Figure Ne 7 Figure

Claims (1)

[Claims] 1. A magnetic recording disk having a magnetic recording medium sheet made of a circular flexible sheet having an opening in the center, wherein the magnetic recording medium sheet has at least one ring-shaped outer periphery. The ring-shaped member is supported by a member, and the ring-shaped member has an isotropic coefficient of thermal expansion, and the coefficient of thermal expansion is equal to or slightly higher than the coefficient of thermal expansion of the disk base of the magnetic recording medium sheet. magnetic recording disk. 2. The magnetic recording disk according to claim 1, wherein the ring-shaped member is made of metal. 3. The magnetic recording disk according to claim 1, wherein the ring-shaped member is made of plastic. 4. In the magnetic recording disk according to any one of claims 1 to 3, the ring-shaped member includes a first ring having a substantially L-shaped cross section; a second ring that engages with the first ring, and the outer periphery of the magnetic recording medium sheet is between the first ring and the second ring;
A magnetic recording disk characterized by being held between a ring and a ring. 5. The magnetic recording disk according to any one of claims 1 to 3, wherein the ring-shaped member is a ring having a substantially L-shaped cross section, and the magnetic recording medium A magnetic recording disk characterized in that the outer periphery of the sheet is joined to the substantially L-shaped ring.