JPH0452809Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a flexible magnetic disk and to improving the output stability thereof.

[Conventional technology]

Small flexible magnetic disks are used in smaller equipment and are therefore placed in extremely limited locations within the equipment, so they cannot be fitted into the center of a disk-shaped recording medium like conventional flexible magnetic disks. Unlike those that have mating holes and are supported from both directions, the structure is such that a hub is provided in the center of the disk-shaped recording medium to fit into a rotating shaft that is inserted from one side.

When the hub is made of plastic, the recording medium and the hub can be joined using ultrasonic bonding, thermal fusion, or adhesives, and when the hub is made of metal, adhesives may be used to connect the recording medium to the hub. .

In either of these methods, it is difficult to bond the adhesive surfaces uniformly. The effect of this non-uniformity appears on thinner recording media, resulting in distortion of the recording medium.

[Problem that the invention attempts to solve]

As flexible magnetic disks become smaller, the diameter of the recording medium becomes smaller, and in order to secure the recording capacity,
The recording area will be set up close to the hub. Furthermore, since the diameter is smaller, even if a sheet made of the same material and thickness as a sheet with a larger diameter is used, the rigidity will be increased.

For the above reasons, the distortion of the recording medium caused by the uneven bonding between the hub and the recording medium extends to the recording portion.

Furthermore, when a metal center hub is used, the temperature and humidity expansion coefficients of the recording medium and the hub are significantly different, so that if the usage environment changes, the distortion will become even greater.

When the recording medium is distorted in this way, the contact between the magnetic head and the recording medium becomes uneven, resulting in large output fluctuations. This ultimately leads to a decrease in the reliability of the recording medium.

[Means to solve the problem]

It has been found that in order to solve the above-mentioned drawbacks, it is sufficient to provide a portion having lower rigidity than the recording portion between the recording portion of the recording medium and the joint portion with the hub.

There are two ways to reduce the rigidity: constructing the part with a material with a small elastic modulus, and structurally reducing the rigidity if the material is the same.
The street can be considered. However, using materials with different moduli of elasticity is not suitable for mass-produced products, so we investigated ways to reduce structural rigidity.

As a result, by reducing the thickness between the recording part of the recording medium and the joint part with the hub, or by drilling multiple holes concentrically in this part, the rigidity can be reduced and uneven joints can be prevented. It was possible to reduce output fluctuations based on strain.

〔Example〕

The present invention will be specifically explained based on examples.

Example 1 FIG. 1 shows an example of the present invention.

It has a structure in which a disk-shaped recording medium 1 made of a synthetic resin film coated with magnetic paint and a metal center hub 2 are joined using a mounting agent, and magnetic recording is performed in the shaded area in the figure.

This magnetic disk rotates by fitting the rotation mechanism (not shown) of the recording/reproducing device to the hub portion of the disk, and writes data by bringing the magnetic head (not shown) into contact with the recording portion of the disk. Reading is performed. At this time, the disk is rotated at high speed, so even a slight distortion of the disk causes a difference in the contact pressure with the head, resulting in a difference in recording intensity and an uneven read voltage. For this reason, by providing a plurality of holes 3 concentrically between the recording portion and the center hub of the recording medium, that is, in the non-recording portion, the rigidity of this portion is made smaller than the rigidity of the recording portion. Thereby, it is possible to prevent distortion of the medium due to non-uniform bonding between the center hub and the recording medium from reaching the recording portion.

Embodiment 2 As shown in FIG. 2, the non-recording portion between the recording portion of the recording medium and the center hub is ground to reduce its thickness, and the rigidity of this portion is made smaller than the rigidity of the recording portion. The figure shows an example in which grinding is performed to remove a magnetic coating film, for example.

Embodiment 3 As shown in FIG. 3, by providing a plurality of concentric grooves in the non-recording part between the recording part and the center hub of the recording medium, the rigidity of that part is made lower than the rigidity of the recording part. Also make it smaller.

[Effect of idea]

As mentioned above, the present invention aims to reduce the stiffness of the area between the recording part and the center hub by reducing the influence of the momentum of the recording medium that occurs when joining center hubs made of metal or plastic in small flexible magnetic disks. By making the rigidity smaller than that of , it is possible to prevent the influence from reaching the recording part, to reduce output fluctuations, and to improve reliability.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are schematic diagrams showing embodiments of the present invention.

Claims (1)

[Scope of utility model registration request] 1. A flexible magnetic disk having a center hub, wherein the rigidity of a portion inside the innermost recording track is smaller than the rigidity of the recording portion.