JPH0731421Y2 - Magnetic disk cartridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a disk cartridge, which is a type of floppy disk, and more particularly to a metal hub thereof.

Conventional technology Conventionally, magnetic disk cartridges have been used for micro floppy disks (MFD), video floppy disks (VFD) and the like. This magnetic disk cartridge has a thick and hard hard case that rotatably stores a magnetic disk having a metal hub in the center, and a magnetic head insertion window hole opened in the case has a shutter. A metal hub is exposed to the magnetic disk drive window hole. The surface of this metal hub is a mirror surface, and the + point average roughness Rz of the surface is less than 2.0 μm, usually 0.5
It is about μm.

However, when such a magnetic disk cartridge is mounted on a drive (magnetic recording / reproducing apparatus), sliding friction between the metal hub and the drive section of the drive becomes large.
Defects such as tracking deviation (deterioration of modulation) and index deviation (timing deviation) occur due to chucking failure. Also, chucking scratches due to contact between the metal hub and the drive unit of the drive are noticeable.

The present invention has been made in view of such conventional problems, and provides a magnetic disk cartridge in which a chucking defect does not occur and chucking scratches are not noticeable by improving a metal hub. With the goal.

Means for Solving the Problems Means for achieving the above object will be described with reference to FIGS. 1, 2, and 4 corresponding to the embodiment.

In this magnetic disk cartridge, a magnetic disk 12 having a metal hub 14 in the center is rotatably housed inside a hard case case 10. The metal hub 14 has a roughened surface and the + -point average roughness of the roughened surface is 2.0 to 5.0 μm for a measured length of 2.5 mm.

Operation The above means operates as follows.

When the surface of the metal hub 14 is roughened, the sliding friction is reduced, so that the drive pin 30 of the drive easily slips on it during chucking, and the drive pin 30 rotates while sliding to quickly move to a predetermined position in the drive hole 18. Reach At that time, the sliding mark of the drive pin 30 remains as a scratch on the hub 14. However, for this chucking scratch, the + point average roughness of the rough surface is measured and the length is 2.5 mm.
When it is 2.0 μm or more, it becomes almost invisible.
However, if the thickness exceeds 5.0 μm, the adhesive strength of the flange portion 20 with the magnetic disk 12 decreases, which is not preferable.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a vertical sectional view of a magnetic disk cartridge according to an embodiment of the present invention. In the figure, 10 is a plastic hard case in which upper and lower halves are combined, 12 is a magnetic disk rotatably housed in the case, and 14 is a metal hub installed in the center of the disk. The metal hub 14 has a drive shaft insertion hole 16 in the center and a drive hole 18 near the outer periphery, and is fixed to the magnetic disk 12 by a flange portion 20 thereof. However, since the bottom outer surface 22 is a contact surface with the drive portion of the drive and serves as a reference surface of the cartridge with respect to the drive, it is exposed to the outside from a disk drive window hole 24 formed in the center of the case 10. . The surface of such a hub 14, for example, the outer surface 22 of its bottom and the inner surface of the drive hole 18 are roughened.

Here, a measurement example of the surface roughness Rz of the metal hub will be shown. To measure the + point average roughness Rz of the surface of this metal hub 14,
First, the measurement length L is determined to be, for example, 2.5 mm in the direction of the arrow in FIG. 2, and the unevenness of the reference surface is indicated by a waveform along the length. 2 is a view in which the metal hub 14 shown in FIG. 1 is turned upside down, and FIG. 2A is a plan view and FIG. 2B is a front view. A graph showing such a measurement result is as shown in FIG. Therefore, parallel to the average line of the waveform over the measurement length of 2.5 mm, and from the straight line that does not cross the waveform, measured in the direction of longitudinal magnification, the average value of the highest to fifth peaks and the deepest to fifth valley bottoms. When the difference from the average value of the altitudes up to is calculated, the + point average roughness Rz of the surface is 3.3 μm. By the way, when a conventional metal hub is similarly measured, the graph showing the measurement result is as shown in FIG. 8, and the measurement length L =
The surface roughness per 2.5 mm is Rz = 0.5 μm.

When such a magnetic disk cartridge is mounted on the drive, the metal hub 14 is moved to the drive unit as shown in FIG.
It is chucked by 26 and rotates. At that time, the cartridge moves in the direction of the arrow shown in FIG. Abuts on the reference surface 22 of. The drive pin 30 rotates while sliding on the reference surface 22,
When it reaches the drive hole 18, it enters there to position the hub 14 relative to the drive 26 and start its rotation. The fourth
In the figure, 32 is a receiving member and 34 is a magnet. When the drive pin 30 rotates while sliding on the reference surface 22 as described above, a scratch is generated there. FIG. 6 shows each of these steps from contact to chucking in order. In step a, the drive pin 30 is sliding on the reference surface 22 of the hub 14, and in step b, the drive pin 30 is sliding in the drive hole 18 of the hub 14, c.
In the process, the hub 14 is chucked by the driving unit 26, d
The process shows the hub 14 rotating with the drive 26, respectively. Then, the measurement result of the sliding force of the metal hub 14 is shown in a graph of FIG. From this figure, in the hub 14 having a surface roughness Rz of 3.3 μm, the driving pin 30 has a sliding force of 2 g on the reference surface 22, and a chucking force of 7.5 g.
It can be seen that it is. Incidentally, the sliding force of the conventional metal hub is similarly measured and shown in a graph as shown in FIG. From this figure, it can be seen that in a hub having a surface roughness Rz of 0.5 μm, the driving pin 30 has a sliding force of 4 g on the reference surface and a chucking force of 9.5 g.

As described above, the larger the surface roughness Rz of the metal hub, the smaller the sliding friction, and the more slippery it is, and the smaller the force required for chucking becomes. As a result, the chucking failure does not occur, and as shown in FIG. 10A, the chucking is normally performed and the chuck rotates. By the way, if a chucking failure occurs, the drive pin 30 will move into the drive hole 36 as shown in FIG. 10B.
The magnetic disk rotates together with the drive unit 26 without reaching a predetermined position therein. For this reason, positioning of the hub with respect to the drive unit becomes incomplete, deterioration of modulation due to tracking deviation and timing deviation due to index deviation occur, and output becomes unstable. This is the surface roughness
This is because a hub having an Rz of about 0.5 μm has high adhesion to the drive unit 26, so sliding friction during chucking becomes large and a large chucking force is required.

However, the preferred surface roughness Rz range for metal hubs is 2.0-
It is at 5.0 μm. This is because the above-mentioned chucking scratches were easily noticeable on the conventional hub having a surface roughness Rz of about 0.5 to 1.0 μm, but become almost invisible when the hub is 2.0 μm or more. Since the assembled magnetic disk cartridge is always inspected and shipped, chucking scratches naturally occur, so it is necessary to improve the appearance. However, when the thickness exceeds 5.0 μm, the adhesive force between the flange and the magnetic disk is reduced, so that the deflection of the reference surface becomes large and the output becomes unstable. In addition, the appearance is impaired.

Effect of the Invention According to the present invention described above, since the surface of the metal hub provided in the center of the magnetic disk is made rough, sliding friction can be reduced and chucking defects can be eliminated. Moreover, the + point average roughness of the rough surface is 2.0 per 2.5 mm of measuring length.
When the thickness is up to 5.0 μm, the chucking scratches, which are likely to be recognized as poor appearance, can be made inconspicuous without significantly lowering the adhesive strength of the flange portion with the magnetic disk.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a magnetic disk cartridge according to an embodiment of the present invention, FIG. 2 is a view in which a metal hub thereof is turned upside down, FIG. A is a plan view, and FIG. B is a front view. FIG. 3 is a graph in which the + point average roughness of the surface of the metal hub is measured. FIG. 4 is a vertical cross-sectional view showing a state in which the magnetic disk cartridge is mounted on a drive unit of a drive, FIG. 5 is a perspective view showing a mounting process of a metal hub to the drive unit, and FIG. It is a top view showing each process to chucking in order. FIG. 7 is a graph in which the sliding force of the metal hub is measured. FIG. 8 is a graph in which the + -point average roughness of the surface of the conventional metal hub is measured, and FIG. 9 is a graph in which the sliding force is measured. FIG. 10 is a plan view showing a rotating state of the metal hub by chucking. FIG. 10A corresponds to this embodiment, and FIG. 10B corresponds to the conventional example. 10 …… Hard case, 12 …… Magnetic disk, 14 …… Metal hub

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-114179 (JP, A) Actually opened 61-13377 (JP, U) Actually opened 60-85719 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. In a magnetic disk cartridge in which a magnetic disk having a metal hub in the center is rotatably housed in a hard case, the entire surface on the side where the drive pin of the metal hub slides is + point average roughness. At a measurement length of 2.5 mm
A magnetic disk cartridge having a rough surface of 2.0 to 5.0 μm, wherein the magnetic disk is bonded to the rough surface side of a peripheral flange of the metal hub.