JPS593415Y2 - magnetic disk cartridge - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic disk cartridge used for magnetic recording and reproduction of audio signals, video signals, data signals, etc.! Recently, magnetic disk cartridges have been put into practical use that enable recording and playback by driving the magnetic disk externally while the magnetic disk remains housed in the jacket, and pressing a magnetic recording and playback head against the recording surface of the magnetic disk. There is.

This type of magnetic disk cartridge does not remove the jacket during use, which prevents dust from adhering to the recording surface compared to conventional magnetic disks that are used with exposed surfaces. Another advantage is that magnetic powder and the like separated from the magnetic disk can be wiped off using a cleaning sheet interposed between the jacket and the magnetic disk.

However, since nonwoven fabrics made of intertwined long fibers are generally used as cleaning sheets,
When used for a long period of time, due to the sliding contact with the magnetic disk, the fibers become fluffy, especially around the opening where the long fibers of the nonwoven fabric are cut, and eventually fall off, and these fallen fibers adhere to the recording surface of the magnetic disk. This method has drawbacks such as deterioration of the S/N ratio and increase in dropouts.

Therefore, it has been proposed to form a heat-sealed portion around the opening of the cleaning sheet to prevent the fibers from falling off and fluffing without impairing the cleaning effect.

This magnetic disk cartridge will be explained with reference to FIGS. 1 and 2.

The magnetic disk cartridge consists of a jacket 1 and a magnetic disk 2 wrapped in the jacket 1. The magnetic disk 2 has a flexible and elastic plastic base film coated with a magnetic recording layer on one or both sides. It has a hole 3 in the center that engages with a drive shaft, and a recording track is formed between the recording band width a.

The jacket 1 includes a rectangular outer sheet 4 made of a material such as hard vinyl or synthetic resin such as polyester;
This outer sheet 4 is provided with bonding edges 5A, 5B, and 5C.

A cleaning sheet 6 made of a nonwoven fabric containing thermoplastic fibers such as polyester fibers, nylon fibers, and polypropylene fibers is arranged on one side of the outer sheet 4, and the surface thereof is heat-pressed to form a linear bonding sheet. Fusion part 7A
, 7B, and 7C, the cleaning sheet 6 is fused to the outer sheet 4.

The two square parts 4A, 4B and 6A, 6B of the outer sheet 4 and the cleaning sheet 6, which are already separated by the central fold line, have a peripheral part of the central hole 3, which has a larger diameter than the central hole 3 of the magnetic disk 2. A central opening 8 for exposure, a slot 9 for the magnetic head to access the recording band width a of the magnetic disk 2, and a track start point in the circumferential direction of the magnetic disk 2 are detected, thereby detecting the magnetic disk. A starting point sensing hole 10 is provided for determining the starting point of radial movement of the radial direction and for correct tracking.

Further, around the central opening 8 and the slot 9 of the cleaning sheet 6, heat-sealed parts 11A and I for preventing falling off are formed by a heat press and run in two or three lines along the circumferential direction of these openings.
IB is formed.

A rectangular outer sheet 4 with a cleaning sheet 6 fused to one side is folded along its center fold line with the cleaning sheet 6 side facing inside, and a magnetic disk 2 is placed between both square portions 6A and 6B of the cleaning sheet 6. is inserted.

In this state, each of the bonding edges 5A, 5B, and 5C is bent along the folding line C and bonded to the outer surface of one square portion 4A of the outer sheet 4.

In this magnetic disk cartridge, a portion corresponding to the upstream side in the rotational direction of the magnetic disk 2 around the starting point sensing hole 10 formed in the cleaning sheet 6 is not fused and fixed to the outer sheet 4.

Therefore, if you use a magnetic disk cartridge,
Due to the rotation of the magnetic disk 2, the fibers in the peripheral area corresponding to the upstream side become fluffy and fall toward the starting point sensing hole 10,
-Alternatively, its peripheral portion often stretches due to sliding contact with the magnetic disk 2 and approaches the starting point sensing hole 10 side.

When such a phenomenon occurs, the detection sensitivity of the starting point sensing hole 10 decreases, causing malfunction.

The purpose of the present invention is to eliminate such drawbacks of the conventional technology,
To provide a magnetic disk cartridge that provides high detection sensitivity.

In order to achieve this object, the present invention is characterized in that a heat-sealed portion to the jacket is provided on the upstream side in the direction of rotation of the magnetic disk around the starting point sensing hole of the cleaning sheet.

Next, embodiments of the present invention will be described with reference to FIGS. 3 to 8.

As in the conventional case, the magnetic disk cartridge is composed of a jacket 1 and a magnetic disk 2 rotatably housed in the jacket 1.

The magnetic disk 2 consists of a base film with a magnetic recording layer coated on one or both sides, and a hole 3 is bored in the center to engage with a drive shaft, as shown in FIG.
Further, a through hole 12 for detecting a track start point is formed at a predetermined location on the magnetic disk 2.

As the magnetic disk 2 rotates within the jacket 1, the through hole 12 passes under the starting point sensing hole 10 formed in the jacket 1, and the rotation state of the magnetic disk 2 is optically detected by a photosensor. detected.

The jacket 1 is composed of an outer sheet 4 made of a synthetic resin such as hard polyvinyl chloride, and a cleaning sheet 6 made of a nonwoven fabric made of a mixture of polypropylene fibers and rayon fibers.The cleaning sheet 6 is arranged on one side of the outer sheet 4. There is.

As shown in FIG. 3, there are three heat-sealing parts 7A, 7B, 7C, and 7D for pasting in the longitudinal direction of the cleaning sheet 6 with the two central openings 8, 8 in between.

7E and 7F are formed.

The heat-sealed parts 7A to 7F have a predetermined width of about 4 mm.
It extends linearly with an inclination of 5 degrees, and has heat-sealed parts 7A to 7C.
The inclination directions of the heat-sealing parts 7D to 7F are completely opposite, and the cleaning sheet 6 is formed by these heat-sealing parts 7A to 7F.
is pasted on the outer sheet 4.

A central opening 8, a slot 9, and a starting point sensing hole 10 are formed at predetermined locations on the outer sheet 4 and the cleaning sheet 6.

The peripheral part of the central opening 8 in the cleaning sheet 6 is
As shown in FIGS. 4 and 5, it is adhered and fixed to the outer sheet 4 by a large number of square dot-shaped first heat-sealing parts 13 for preventing falling off.

This dot-shaped first heat-sealing part 13 for preventing falling off is formed in multiple strips along the circumferential direction of the central opening 8, and each strip is finely and discontinuously divided. There is a non-fused portion around the fused portion 13, and heat dissipation during fusion is performed evenly and quickly.

The overall distribution state of the dot-shaped first heat-sealed parts 13 is such that the areal density (number of heat-sealed parts per unit area) of the dot-shaped first heat-sealed parts 13 is not uniform, and the magnetic field relative to the jacket 1 is not uniform. The dot-shaped dots around the opening correspond to the downstream side of the disk 2 insertion direction The areal density of the first thermally fused portion 13 is higher than that of other parts around the opening.

The opening angle θ of the central opening 8 from the center O in this high-density region is about 20 to 180 degrees, preferably 30 to 60 degrees.

In this embodiment, the areal density of the dot-shaped first heat-sealed portions 13 in the high-density region is approximately twice that of the other portions around the opening.

In the portion of the cleaning sheet 6 where the starting point sensing hole 10 is to be drilled, a minute interval is formed along the rotational direction Y of the magnetic disk 2 (see FIGS. 4 and 8) before the hole is drilled. A plurality of dot-shaped second fall-off prevention heat-sealed parts 14
is formed, whereby the cleaning sheet 6 is adhered to the outer sheet 4.

When the starting point sensing hole 10 is bored in the outer jacket 4 and the cleaning sheet 6, the starting point sensing hole 10
The size of the starting point sensing hole 10 is taken into consideration so that the dot-shaped second heat-sealed portion 14 is always located at a portion corresponding to the upstream side in the rotational direction Y of the magnetic disk 2 around the magnetic disk 2. The size of the fused portions 14 and the spacing between them are designed.

Furthermore, the position at which the starting point sensing hole 10 is formed differs depending on whether the magnetic recording layer of the magnetic disk 2 is on one side or on both sides.

Therefore, a plurality of rows of dot-shaped second heat-sealed portions 14 are provided so that they can be applied to both magnetic disks 2.

FIG. 4 shows a state in which the starting point sensing hole 10 has been drilled, and dot-shaped holes are formed around the starting point sensing hole 10 in areas corresponding to both the upstream and downstream sides in the rotational direction Y of the magnetic disk 2. A two-thermal fusion portion 14 is formed.

The peripheral part of the slot 9 in the cleaning sheet 6 is
As shown in FIGS. 3 and 7, a strip-like heat-sealing part 16 (shaded area in FIG. 7) for preventing falling off is formed by leaving a large number of independent circular minute non-thermal-sealing parts 15 (shaded area in FIG. 7). It is attached to sheet 4.

The periphery of the slot 9 can also be attached using a large number of discontinuous dot-shaped heat-sealed parts, similar to the case where the periphery of the central opening 8 is attached.

In this case, the pattern of the dot-shaped heat-sealed portions is formed so that the areal density of the dot-shaped heat-sealed portions on the downstream side in the insertion direction of the magnetic disk in the periphery of the slot 9 is higher than that in other parts of the periphery of the slot 9. It is good to design.

FIG. 8 is a bottom view of the magnetic disk cartridge.

A rectangular outer sheet 4 with a cleaning sheet 6 pasted on one side is folded along its center fold line with the cleaning sheet 6 inside.
Both square parts 6A.

A magnetic disk 2 is inserted between 6B.

Thereafter, each of the bonding edges 5A, 5B, and 5C is bent along the folding line C, and placed on the periphery of the other square portion 4A of the outer sheet 4.

Each of the bonding edges 5A to 5C is a dot-shaped outer sheet bonding heat-sealing portion 17 arranged in multiple rows at predetermined intervals.
Laminated by.

In the above embodiment, a dot-shaped heat-sealed part was provided around the starting point sensing hole in the cleaning sheet, but the shape of the heat-sealed part is not limited to this, and for example, it may be formed in a plurality of lines or in a mesh shape. It may be formed as follows.

As described above, the present invention fixes the cleaning sheet around the hole by providing a heat-sealed portion to the jacket on the upstream side in the rotational direction of the magnetic disk around the starting point sensing hole of the cleaning sheet.

Therefore, the rotation of the magnetic disk prevents fluffy fibers or a part of the periphery of the hole from entering the starting point sensing hole, so that accurate tracking is always performed and reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a magnetic disk cartridge, FIG. 2 is a plan view showing the inner surface of a jacket of a conventional magnetic disk cartridge developed, and FIG. 3 is an inner surface of a jacket of a magnetic disk cartridge according to an embodiment of the present invention. FIG. 4 is an enlarged plan view showing the welding pattern around the central opening of the jacket, FIG. 5 is an enlarged sectional view taken along line I-I in FIG. 4, and FIG. 4 Figure II-II
FIG. 7 is an enlarged plan view showing the fusion pattern around the slot of the jacket, and FIG. 8 is a bottom view of the magnetic disk cartridge. 1... Jacket, 2... Magnetic disk, 4... Outer sheet, 6... Cleaning sheet, 8... Center opening, 10・・・・・・
. . . Starting point sensing hole, 14 . . . Dot-shaped second heat-sealed part for preventing falling off, Y . . . Rotation direction of the magnetic disk.

Claims (1)

[Scope of utility model registration request] a magnetic disk, an opening for rotatably accommodating the magnetic disk and for externally driving and recording/reproducing the accommodated magnetic disk; and a start point sensing hole for detecting a track start point in the circumferential direction of the magnetic disk; and a cleaning sheet made of a nonwoven fabric interposed between the magnetic disk and the jacket and having openings and starting point sensing holes similar to those of the jacket; A magnetic disk cartridge characterized in that a heat-sealed portion to the jacket is provided on the upstream side in the direction of rotation of the disk.