JPH10255428A - Magnetic disk cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a deformation such as bending during forming by specifying the relationship between the thickness of the thickest part in a section more outside than the outer peripheral edge of an annular rib and opposed to a disk recording medium and average thickness of a part more inside than the inner peripheral edge of the annular rib in an upper shell. SOLUTION: A label sticking region nearly square-shaped and recessed is formed outside an annular rib 6 so as not to overlap the annular rib 6 projected on the surface of the opposite side of an upper shell 1. Then, an average thickness (t') is calculated from the respective areas of 7a, 7b and 7c parts having thickness of 1.17, 0.88 and 0.56 and the area of a part inside more than the inner peripheral edge of the annular rib 6. Also, a relationship between the thickness (t) of a thickest part outside more than the outer peripheral edge of the annular rib 6 and t' is set to 0.6t<=t'<=1.2t, and in the case shown in the drawing, the relationship is satisfied with an average thickness t'=0.95mm and t=0.93mm. Thus, the problem such as the increase of driving torque the wearing of the disk and the dusting caused by the wearing can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk cartridge in which a disk-shaped magnetic recording medium is rotatably housed in a cartridge composed of an upper shell and a lower shell, and in particular, prevents deformation during molding. The shape of the upper shell.

[0002]

2. Description of the Related Art As shown in a perspective view of FIG. 1, a magnetic disk cartridge has a flat cartridge formed by joining an upper shell 1 and a lower shell 2 made of a synthetic resin. The disk-shaped magnetic disk fixed to the disk is stored in a rotatable state.

A magnetic head insertion hole 3 for recording and reproduction is opened in the upper shell 1 shown in FIG. 3 which is a plan view of FIG. 2 and a sectional view taken along the line III-III of FIG. A concave portion forming an assembly portion 4 of a shutter member for opening and closing the head insertion hole portion 3 and a concave portion forming a label attaching region (label area) 5 are provided on the outer surface. An annular rib 6 is provided on the inner surface of the upper shell 1 to rotatably support the center hub of the magnetic disk.

In the present specification, for convenience of explanation, as shown in FIG. 4, a region inside the inner peripheral edge of the annular rib 6 is referred to as a center portion 7, and a region outside the outer peripheral edge of the annular rib 6 is shown in FIG. The area facing the magnetic disk among the areas that spread out is referred to as the outer peripheral portion 8. As shown in FIG. 4, one side 5 a of the label attaching region 5 is provided so as not to overlap with the annular rib 6 shown by a dashed line. Here, the annular rib 6 is not included in the central portion 7 and the outer peripheral portion 8.

The thickness of the central portion 7 of the conventional upper shell 1 is substantially equal to the thickness of the outer peripheral portion 8 as is clear from FIG. 3 which is a sectional view of FIG. It was thicker than.

[0006]

The upper shell 1
There are the following problems in the molding of

(1) A portion corresponding to the center portion 7 of the mold, especially the center portion on the core side, often has a nested structure, and it is difficult to take a cooling circuit sufficiently as compared with other portions.
Insufficient cooling of the molded resin.

(2) The outer peripheral portion 8 may have a thickness different from that of the central portion 7 in forming the cartridge, and the cooling rate in the thickness direction of the molded product is inversely proportional to the square of the thickness of the molded product. In particular, as shown in FIG. 5, when the thickness of the central portion 7 is thicker than the thickness of the outer peripheral portion 8, the cooling of the central portion 7 is delayed, and when the molded product is taken out from the mold. In the center 7
Is higher than that of the outer peripheral portion 8.

As described above, due to the problem of the equipment of the mold and the problem of the dimension of the cartridge, the central portion 7 and the outer peripheral portion 8 are not provided.
When there is a temperature difference between the mold and the mold, when the molded product is taken out from the mold, the shape of the mold is not restricted by the mold. If the degree is large, the molded article is deformed such as warpage as shown by a solid line in FIG.

In a disk cartridge, if the cartridge is deformed such as warpage, a large frictional force is generated between the disk-shaped recording medium (hereinafter, simply referred to as "disk") and the cartridge, and the disk driving torque increases. In addition, there arises a problem that reading and writing of a record become impossible due to wear and abrasion powder of the disk itself.

Such a problem is remarkable in a cartridge as shown in FIG. 4, that is, a cartridge having a structure in which the label attaching region 5 does not overlap with the annular rib 6, in other words, a structure in which the center portion 7 is thicker.

In view of the above circumstances, an object of the present invention is to provide an upper shell of a disk cartridge which can reduce the above-mentioned deformation during molding.

[0013]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have noticed the relative relationship between the thickness of the central portion 7 of the upper shell of the cartridge and the thickness of the outer peripheral portion 8. We have found what we need to do and arrived at the present invention.

That is, according to the present invention, a disk-shaped recording medium is rotatably housed in a resin cartridge composed of an upper shell and a lower shell, and recording / reproducing is performed on at least one surface of the cartridge. And a shutter member for opening and closing the hole is slidably provided in a direction orthogonal to a direction in which the cartridge is inserted into a recording / reproducing apparatus having a magnetic head. An annular rib for rotatably supporting the disk-shaped recording medium is provided on the surface of the side facing the disk-shaped recording medium, and at least an upper shell of the upper shell and the lower shell is provided for the disk-shaped recording medium. On the surface on the opposite side, a substantially rectangular and concave label attaching region is formed such that one side thereof is substantially parallel to the sliding direction of the shutter member. In the magnetic disk cartridge has a label attaching area of the concave in the almost square,
The upper shell is formed outside the outer peripheral edge of the annular rib so as not to overlap with the annular rib projected on the surface on the opposite side of the upper shell, and the upper shell is outside the outer peripheral edge of the annular rib, and When the thickness of the thickest portion facing the disk-shaped recording medium is t, and the average thickness of the portion inside the inner peripheral edge of the annular rib is t ', the relationship between t and t' is 0. .6t ≦ t ′ ≦ 1.2t is achieved by the magnetic disk cartridge.

Here, the average thickness t 'of the portion inside the inner peripheral edge of the annular rib is such that the portion inside the inner peripheral edge of the annular rib is n (n is a natural number of 2 or more). The thickness of each component is t1, t2,
If t3,... tn, t '= (thickness t1 of first component) × (area of first component / area of inner portion of inner peripheral edge of annular rib) + (Thickness t2 of second component) × (Area of second component / Area of entire portion inside inner peripheral edge of annular rib) + ... (Thickness of nth component) tn) ×
(Area of the n-th component / area of the entire portion inside the inner peripheral edge of the annular rib).

The effect of the present invention as described above is as follows. By setting the relationship between the thicknesses t and t 'within this range, the resin flow between the different thicknesses during molding can be kept good. As a result, it is considered that the temperature difference between the central portion and the outer peripheral portion can be reduced so that the temperature difference can be obtained.

If the dimensional relationship of t 'to t exceeds 1.2t, the above-mentioned flow state cannot be maintained in a good state any more and deformation such as warpage occurs.

On the other hand, if t 'is less than 0.6 t, the flow resistance of the resin between different thicknesses increases, and the resin does not flow uniformly, which causes a new problem of so-called short-circuit. Such a range is effective.

Further, the above range is 0.8t≤t'≤1.
More preferably, it is 1t.

The reason for this is that in the regions of 0.6t ≦ t ′ <0.8t and 1.1t <t ′ ≦ 1.2t, the flow state of the resin is unstable, and there are slight differences in the lot and molding conditions of the resin. Because it is easily affected.

The present invention is effective not only for the above effects but also for improving productivity.

In general, the molding cycle is short, ie 1
Reducing the time required for each molding means that the resin molded in the mold is immediately taken out of the mold.

Accordingly, as described above, the molded resin is not restricted by the metal mold and can be freely deformed by natural cooling, so that its accuracy is reduced.

Therefore, there is a limit in shortening the molding cycle.

However, according to the present invention, since the relationship between t and t 'is as described above, deformation such as warpage hardly occurs, so that the molding cycle can be shortened.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Table 1 shows that the value of t 'is changed from 0.5t to 1.4.
When the amount of warpage of the upper shell 1 has been changed to t, one day or more after molding, as shown in FIG. 8, an optical displacement sensor 10 is used to label the sensor 10 with a label on the upper shell. It shows the amount of displacement obtained by operating the sticking area in a direction parallel to the shutter opening and closing direction.

The direction of warping as shown by the solid line in FIG. 6 is defined as minus.

[0029]

[Table 1]

As is clear from this table, 0.6t ≦
If t '≦ 1.2t, warpage can be effectively suppressed.

FIG. 5 is an enlarged sectional view of a portion A in FIG. 3, that is, an enlarged sectional view near the central portion 7 of the upper shell 1 and a bottom view for explaining the region. It is.

Although the scale is not always accurate for the sake of explanation, the dimensions of the main parts are as shown in FIG. Based on these dimensional specifications, each of the components 7a, 7b, 7c, 7d, 7e
When the respective areas are obtained, the area of the portion 7a (portion with a thickness of 1.17 mm) is 172.03 mm ² , and the portion 7b (portion with a thickness of 1.28 mm)
The area of 90.56mm ² , the area of 7c part (part of 1.38mm thickness) is 83.79mm ² , the area of 7d part (part of 1.06mm thickness) is
13.36mm ² , area of 7e part (part of wall thickness 0.96mm) is 3.31
a mm ^2.

The area of a portion inside the inner peripheral edge of the annular rib 6 is 364.05 mm ² .

When t 'is obtained from these specifications, t' = 1.17 × (172.03 / 364.05) + 1.28 × (90.56 / 364.05) + 1.38 × (83.79 / 364.05) + 1.06 × (13.36 / 364.05) + 0.96 × (3.31 / 364.05) = 1.24 mm On the other hand, in FIG. 5, the dimension of t is 0.93 mm.

Therefore, the relationship between t and t 'is t' = 1.
33t.

FIG. 7 is an enlarged cross-sectional view near the center 7 of the upper shell 1 designed to have a relationship between t and t 'according to the present invention, and a bottom view for explaining the region.

As in FIG. 5, the scale is not necessarily accurate for the sake of explanation, but the main dimensions are as shown in FIG.

[0038] than its dimension specifications, 7a unit area of the area 105.68mm ^2, 7b of the (wall portion of the thickness 1.17 mm) (part of the wall thickness 0.88 mm) is 240.70mm ^2, 7c section (thickness 0.56mm Part)
Has an area of 16.67 mm ² .

The area of the portion inside the inner peripheral edge of the annular rib 6 is 364.05 mm ² .

When t 'is obtained from these specifications, t' = 1.17 × (105.68 / 364.05) + 0.88 × (240.70 / 364.05) + 0.56 × (16.67 / 364.05) = 0.95mm On the other hand, in FIG. The dimension of t is 0.93 mm.

Therefore, the relationship between t and t 'is t' = 1.
02t.

FIG. 9 shows a molding cycle when the upper shell having the structure of t '= 1.02t is (I) and the upper shell having the structure of t' = 1.33t is (II) and the molding cycle at that time. The results of measuring the amount of warpage by the same measurement method as in Table 1 are summarized.

As is clear from FIG. 9, even in the same molding cycle, the amount of warpage is smaller in the case of (I), and
Also, the degree of increase in the amount of warpage when the molding cycle is shortened is small.

[0044]

According to the present invention, deformation such as warpage can be effectively suppressed by setting the average thickness of the upper shell at t 'of 0.6t≤t'≤1.2t.

As a result, it is possible to improve the disk drive torque due to warpage or the like, the wear of the disk itself, and the accompanying problem of dust generation.

The present invention provides not only the above-described effects but also
It is also effective for improving productivity.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a conventional disk cartridge.

FIG. 2 is a plan view of an upper shell of the disk cartridge.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a plan view for explaining a central portion, an outer peripheral portion, and the like of an upper shell of the disk cartridge.

FIG. 5 is an enlarged cross-sectional view of a portion A in FIG. 3 and a bottom view for explaining the region thereof;

FIG. 6 is a schematic view for explaining deformation (warpage) of the upper shell;

FIG. 7 is an enlarged cross-sectional view corresponding to FIG. 5 of the upper shell according to the embodiment of the present invention and a bottom view for explaining the area thereof;

FIG. 8 is a perspective view showing a method of measuring the amount of warpage.

FIG. 9 is a graph showing the amount of warpage with respect to a molding cycle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper shell 2 Lower shell 3 Magnetic head insertion hole part 4 Assembly part of shutter member 5 Label sticking area 6 Annular rib 7 Center part 8 Outer part

Claims (1)

[Claims] 1. A disk-shaped recording medium is rotatably housed in a resin cartridge composed of an upper shell and a lower shell, and at least one surface of the cartridge has a magnetic recording / reproducing medium. A head insertion hole is formed, and a shutter member for opening and closing the hole is slidably provided in a direction orthogonal to a direction in which the cartridge is inserted into a recording / reproducing apparatus having the magnetic head. An annular rib for rotatably supporting the disk-shaped recording medium is provided on the surface facing the disk-shaped recording medium, and among the upper shell and the lower shell,
At least on the surface of the upper shell on the side opposite to the disk-shaped recording medium, a substantially rectangular and concave label attaching region is formed so that one side thereof is substantially parallel to the sliding direction of the shutter member. In the magnetic disk cartridge, the substantially square and concave label attaching area is formed outside an outer peripheral edge of the annular rib so as not to overlap with the annular rib projected on the surface on the opposite side of the upper shell. And the thickness of the thickest part of the upper shell, which is outside the outer peripheral edge of the annular rib and faces the disk-shaped recording medium, is t, and the inner peripheral edge of the annular rib is A magnetic disk cartridge characterized in that the relationship between t and t 'is 0.6t≤t'≤1.2t, where t' is the average thickness of the inner part.