JP2002050145A - Magnetic disk cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an inward deflection of the face plate part of a shutter member in a magnetic disk cartridge in which a cartridge case is composed of a base plate having a recessed part for housing a magnetic disk medium and coated cover cases on each upper and lower surface of the base plate, and the shutter member to open and close a window for inserting a magnetic head are mounted on the base plate in the inner side of the upper and lower cover cases. SOLUTION: The rear edge part of the shutter active region of the base plate 2 is provided with a bridge shaped body 61 and a flange part 62 for preventing the inward deflection of the tip of the upper and lower face plate parts 51 and 52 of the shutter member 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin, large-capacity magnetic disk cartridge in which a disk-shaped magnetic disk medium is accommodated in a flat cartridge case, and more particularly to a magnetic disk cartridge for inserting a magnetic head into the cartridge case. The present invention relates to a magnetic disk cartridge in which a shutter member for opening and closing a window is slidably provided in a cartridge case.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk medium (a so-called floppy disk) provided with magnetic layers on both sides of a disk-shaped base made of a flexible polyester sheet or the like is housed in a flat case, and the magnetic disk medium is stored in a flat case. A magnetic disk cartridge that performs magnetic recording on the magnetic layer by a magnetic head while rotating is provided, and is widely used mainly as a recording medium for a computer because of its advantages such as easy handling and low cost.

The cartridge case is provided with a window for inserting a magnetic head for inserting and removing a magnetic head for magnetic recording / reproduction from one side or both sides of a magnetic disk medium from the outside so as to be in contact with or close to the outside. In order to prevent intrusion of dust and the like in the above, a shutter member slidable between an open position for opening the window and a closed position for closing the window is mounted.

By the way, the miniaturization of the computer using the above-mentioned magnetic disk cartridge has progressed, and the notebook type personal computer has become widespread. An external system without a built-in disk drive device has been used. The adoption of this external method is excellent in terms of portability of small personal computers.However, for example, there is a problem that a large amount of data cannot be recorded and reproduced because magnetic disk cartridges cannot be used at the carrying destination of small personal computers. This causes a problem that data cannot be recorded on a plurality of magnetic disk cartridges.

[0005] From these points, some small personal computers have a PC card slot (PCMC IA specification compliant) in which a PC card is mounted for external interface and additional memory, and this PC card slot is used. It has been proposed to configure an external storage device using a magnetic disk cartridge.

A PC that can be inserted into the PC card slot
The card is Type II and has a thickness of 5.0 mm, and the magnetic disk cartridge and the disk drive device are to be included in this thickness. Therefore, the magnetic disk cartridge has an ultra-thin thickness of about 2 mm. Must be configured.

[0007]

Even in such an ultra-thin magnetic disk cartridge, a large recording capacity is required as a recording medium. In order to increase the transfer rate, the magnetic disk medium must be moved at a high speed (2600-200).
4500 rpm).

In consideration of this point, it is necessary to design the fundamental structure of the magnetic disk cartridge. In particular, the space for accommodating the magnetic disk medium in a rotatable manner while securing the strength of the cartridge case is required. Securing is an important issue.

That is, since the dimensional regulation in the thickness direction of the cartridge case is strict, the upper and lower shells formed by joining the upper and lower shells made of a synthetic resin having a divided structure like a cartridge case of a conventional magnetic disk cartridge in a lid-like manner. Becomes thinner, and it becomes impossible to maintain a desired mechanical strength. If the strength of the cartridge case is insufficient, the cartridge case will be deformed when loading or unloading it from the drive unit or when handling it outside the drive unit. It causes a decline.

Therefore, a cartridge case is constituted by a base plate and a pair of cover cases attached to the upper and lower surfaces of the base plate, and a magnetic disk medium is rotatably housed in a recess formed in the upper surface of the base plate. There is a possible configuration. In this case, the shutter member for opening and closing the window for inserting the magnetic head is mounted on the base plate inside the upper and lower cover cases to secure the fitting stability.

FIG. 9 is a perspective view showing the structure of such a shutter member. The shutter member 5 has upper and lower face plate portions 5.
The upper and lower face plate portions 51 and 52 are formed to have a U-shaped cross section by the upper and lower face plate portions 51 and 52. A magnetic head insertion window 54 is formed over the entire surface.

However, in a magnetic disk cartridge provided with such a shutter member 5, unlike a normal floppy disk provided with an exterior shutter member, the shutter member 5 has a connecting plate portion 53 of its face plate portions 51 and 52. Is held by the base plate 2 only in the vicinity, and the front ends of the face plate portions 51 and 52 are not supported at all.

Therefore, the position where the shutter member 5 closes the window for inserting the magnetic head of the cartridge case (FIG. 9)
), The face plate portion 51 of the shutter member 5 exposed from the magnetic head insertion window of the cover case.
If a force is applied to the inside 52 by mistake, the front sides of the face plates 51 and 52 bend inward as indicated by arrows, which causes a problem that a gap is formed in the magnetic head insertion window. This problem can be solved by increasing the plate thickness of the shutter member 5, but in this case, it is necessary to reduce the thickness of the base plate 2 in the shutter operation area by the thickness of the shutter member 5, so that the strength is reduced. A problem arises in terms of points.

In view of the above circumstances, it is an object of the present invention to provide a magnetic disk cartridge in which the shutter member is prevented from being bent inside the face plate portion without increasing the thickness of the shutter member.

[0015]

In order to achieve the above object, the present invention provides a disk-shaped magnetic disk medium rotatably housed in a flat cartridge case having a window for inserting a magnetic head. A magnetic disk cartridge comprising a shutter member slidably mounted on the cartridge case between an open position to open the window and a closed position to close the window. A base plate formed on the upper surface, and cover cases respectively attached to the upper and lower surfaces of the base plate,
The shutter member is configured by upper and lower face plate portions and a connection plate portion connecting these face plate portions at a front end,
A regulating means mounted on the base plate inside the upper and lower cover cases, and provided with a restricting means for preventing the inward bending of the front end of the face plate portion of the shutter member in a shutter operation area of the base plate. It is.

The front and rear ends of the face plate of the shutter member mean the front and rear ends of the magnetic disk cartridge in the direction of insertion into the drive device.

The restricting means is cross-linked on the magnetic disk medium accommodating recess of the base plate such that the upper surface is closely opposed to the inner surface of the front end portion (lower surface of the rear end portion) of the upper plate portion of the shutter member. A bridge-like body extending substantially in parallel with the sliding direction of the shutter member; and the magnetic disk medium accommodating recess so that the lower surface thereof is in close proximity to the inner surface of the front end portion of the lower plate portion of the shutter member (the upper surface of the rear bridge portion). Protruding from the bottom wall of the shutter member to the shutter operation area and extending in parallel with the sliding direction of the shutter member.

Although the bridge-like body can be formed integrally with the base plate, it may be formed as a separate member.

Also, instead of the bridge-like body and the protruding edge,
The regulating means may be constituted by a frame-like body having an upper frame and a lower frame extending parallel to each other at a predetermined interval and fixed to the base plate so as to be parallel to the sliding direction of the shutter member. .

Also in this case, the upper frame of the frame-like body is bridged over the concave portion for accommodating the magnetic disk medium, and the upper surface thereof is closely opposed to the inner surface (lower surface) of the front end portion of the upper plate portion of the shutter member. The lower surface of the lower frame of the frame-shaped body is configured to be close to and opposed to the inner surface (upper surface) of the tip of the lower plate portion of the shutter member.

[0021]

According to the magnetic disk cartridge of the present invention, for example, the bridge-like body and the projecting edge are provided in the shutter operation area of the base plate in order to prevent the inward bending of the front end of the face plate of the shutter member. Part, or by the provision of the frame-shaped restricting means, when the shutter member is in the position to close the magnetic head insertion window, the face plate portion exposed from the magnetic head insertion window On the other hand, even when a force is applied inward, the face plate portion is prevented from bending inward, whereby the inconvenience of creating a gap in the magnetic head insertion window can be eliminated.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

1 to 7 show a first embodiment of a magnetic disk cartridge according to the present invention. FIG. 1 is a top view showing a state in which a window for inserting a magnetic head is closed by a shutter member. FIG. 2 is a perspective view showing a state where the window for inserting a magnetic head is opened, as viewed from the lower surface side.
FIG. 4 is an exploded perspective view of the magnetic disk cartridge, FIG. 4 is an exploded perspective view of the base plate and a shutter member assembled thereto viewed from the back side, FIG. 5A is a plan view of the base plate, and FIG. FIG. FIG. 6 is an enlarged cross-sectional view of a main part along line VI-VI of FIG. 5A, and FIG. 7 is an enlarged cross-sectional view of a main part along line VII-VII of FIG. 5A. In addition, in order to clarify the structure, the thickness and the like of each part in the drawings are shown in a ratio different from the actual size.

The magnetic disk cartridge 1 has a disk-shaped magnetic disk medium 10 (see FIG. 3) rotatably housed in a flat cartridge case C.
The cartridge case C is composed of a base plate 2 serving as a central member, and upper and lower cover cases 3 and 4 having a substantially planar shape attached to the upper and lower sides of the base plate 2. The magnetic disk medium 10
A disk-shaped base member made of a flexible polyester sheet or the like is provided with magnetic layers on both sides, and a metal center core 11 is fixed at the center.

At the center of the base plate 2, a hole 27 (see FIG. 3) for accommodating the lower portion of the center core 11 is provided.
Further, a hole 7 having a size substantially equal to the hole 27 is formed in the lower cover case 4 at a position overlapping the hole 27.
The magnetic disk medium 10 is inserted into the cartridge case C such that the bottom surface of the center core 11 faces the outside from the hole 7.
Housed within.

At the front end of the cartridge case C in the direction of insertion D (arrow in FIG. 1) into the drive device, there is formed a window 8 accessible by a recording / reproducing magnetic head. The window 8 is vertically penetrated and opened from the front end surfaces of the base plate 2 and the upper and lower cover cases 3 and 4 toward the center thereof in a rectangular shape (see FIG. 2). Shutter member 5 that opens and closes
(See FIG. 9) are mounted on the base plate 2 inside the upper and lower cover cases 3 and 4 so as to be slidable in the left-right direction.

With such a structure of the window 8, the recording / reproducing magnetic head can be inserted into the window 8 from the front end face side of the cartridge case C without largely opening and closing up and down, and the built-in shutter member 5 is employed. Therefore, the shutter member 5 is prevented from coming off due to insufficient strength due to miniaturization, becomes strong against falling, etc., and the assemblability is improved.

The base plate 2 is made of a synthetic resin such as an acrylonitrile-butadiene-styrene copolymer (ABS resin) or a POM resin, and has a substantially square plate shape. (A)
As is apparent from FIG. 2, a circular recess 21 having a flat inner bottom surface for accommodating the magnetic disk medium 10 is formed, and the hole 27 is formed at the center of the thin bottom plate of the recess 21.
Is open. Further, the front end portion of the bottom plate of the concave portion 21 is cut into a substantially rectangular shape to form a space 22 into which a below-described lower plate portion 52 of the shutter member 5 is movably inserted.
The central portion of the front end portion of the base plate 2 is removed in the front-rear direction, and the window 8 is opened vertically. And
One side of the window 8 of the base plate 2 (right side in FIG. 3)
The front surface of the front wall is retracted from the front surface of the front wall on the other side (the left side in FIG. 3) to form a spring storage portion 23. In this portion,
A shutter spring 6 described later is arranged.

At the rear edge of the shutter operation area on the upper surface of the base plate 2, a bridge-like body 61 formed integrally with the base plate 2 is provided, as is particularly clear from FIGS. 5 (a), 6 and 7. Above the magnetic disk medium accommodating recess 21, the bridge is bridged substantially parallel to the sliding direction of the shutter member 5. The upper surface 61a of the bridge 61 is
Upper surface 2 of front edge of shutter operation area of base plate 2
5a and 5b are on the same plane as FIG.
(A) is shown by hatching.

The rear edge of the shutter operation area on the lower surface of the base plate 2 is shown in FIGS.
As is apparent from FIG. 5, a protruding edge portion 62 extending from the bottom wall of the magnetic disk medium accommodating recess 21 to the shutter operation area and extending in parallel with the sliding direction of the shutter member 5 is formed. The lower surface 62a of the bridge-like body 62 is connected to the lower surfaces 2c and 2 of the front edge of the shutter operation area of the base plate 2.
5 (b), which is on the same plane as that of FIG.
Are shown by hatching.

5 (a), 5 (b) and FIG. 6, the bridge-like body 61 formed on the base plate 2 is not bridged by the protruding edge 62 so that the bridge-like body 62 does not overlap. The body 61 can be integrally formed.

Further, a guide groove 28 with which a guide claw 56 of the shutter member 5 is engaged is formed on the front edge surfaces 2c and 2d of the lower surface of the base plate 2, as shown in FIGS. A notch 29 is formed to guide the guide claw 56 into the guide groove 28 when the shutter member 5 is mounted on the base plate 2.

Four corners 25 of base plate 2
Are formed so as to protrude in the vertical direction and have a large thickness and project outward, and the four corner portions of the upper and lower cover cases 3 and 4 corresponding to this portion are cut out in a shape corresponding to the planar shape of the corner portion 25, When the upper and lower cover cases 3 and 4 are fitted to the base plate 2, the corner portions 25 of the base plate 2 are exposed to the outside. Each corner portion 25 is provided in such a shape that its surface projects flush with the surface of the upper and lower cover cases 3 and 4 or outwards.

By exposing the corner portion 25 of the base plate 2 to the outside as described above, when a shock or the like at the time of drop acts, the corner portion 25 can absorb the shock, and can be inserted into the drive device and inserted. At the time of unloading operation, it is prevented from getting stuck and stable operation is ensured. In addition, each corner portion 25 is provided with a hole 26 that penetrates in the vertical direction as needed (a hole having an intermediate depth without penetrating) may be provided (not shown in FIG. 5). In the above, a larger buffering action is obtained. The base plate 2 has a strength that allows a deformation that does not hinder the recording and reproduction of the magnetic disk medium 10. However, from the viewpoint of shock absorption, the base plate 2 is preferably made of an elastic plastic. ,
In addition, a material containing a lubricant is preferred in terms of sliding with the shutter member 5, and a material containing a filler material is preferred in terms of increasing dimensional accuracy and improving the assemblability with the cover cases 3 and 4. Good.

As shown in FIGS. 1 and 2, a notch-shaped concave portion 15 (not shown in FIG. 5) is formed on the side surface of the corner portion 25 on both sides of the front portion of the base plate 2. Reference numeral 15 is used for positioning when loaded in the drive device, or for preventing erroneous insertion in the front-back direction or the front-back direction. The recess 15 may be provided only on one side surface or on the side surface of the rear corner portion 25. In the case of the present embodiment, the corner of one front corner 25 is cut off obliquely, and
It is 6.

The upper and lower cover cases 3 and 4 are formed of a high-strength material such as a pressed stainless steel plate, and the upper and lower cover cases 3 and 4 are substantially symmetrical.
The corners of the four corners are removed in a rectangular shape, a flat rectangular window 8 is opened in the center of the front part, and the front, rear, left and right edges are bent at right angles, and the front wall parts 31, 41, both side wall parts 32, 42,
The rear wall portions 33 and 43 are configured. The front wall 3 on one side (left side in FIGS. 1 and 3 and right side in FIG. 2) with respect to the window 8.
The slits 18 (see FIGS. 1 and 6) are formed between the upper and lower front wall portions 31 and 41 when the upper and lower cover cases 3 and 4 are attached to the base plate 2. It is supposed to be. The shutter opening / closing member on the drive device side is inserted into the slit 18 and moves along the slit 18 to open the shutter member 5.

The front walls 31 and 41 on the opposite side of the window 8 (the right side in FIGS. 1 and 3 and the left side in FIG. 2), that is, a notch is provided on the end side of the portion located in front of the spring housing 23. Are formed, and front wall portions 31 and 4 of upper and lower cover cases 3 and 4 are formed.
1 is abutted against the rectangular spring insertion port 19.
(See FIGS. 1 and 2) are formed and used for mounting the shutter spring 6.

At the center of the upper surface of the upper cover case 3, a concave portion 35 serving as a label attaching portion is formed. As shown in FIG. 6, the bottom surface of the concave portion 35 projects toward the magnetic disk medium 10, and the upper cover case 3 The strength of No. 3 is improved.

The shutter member 5 is inserted between the base plate 2 and the upper and lower cover cases 3 and 4 and into the space 22 opened in the base plate 2 on the lower surface side, and is slidably mounted in the left and right opening and closing directions. The shutter member 5 is made of metal, for example, formed from a stainless steel plate or an aluminum plate so as to have a substantially U-shaped cross section. As is clear from FIG. 6 are connected by a connecting plate 53 at the front end. As is clear from FIG. 6, the inner dimension in the height direction of the connecting plate 53 is slightly larger than the front thickness of the base plate 2. Further, a shutter window 54 cut out in a substantially rectangular shape is formed from the connecting plate portion 53 to the upper surface plate portion 51 and the lower surface plate portion 52. This shutter window 54
Is approximately the same size as the window 8 of the cartridge case C, and communicates with the window 8 during the opening operation. The shutter window 54 is provided at a position deviated from the center of the shutter member 5, and a closed area for closing the window 8 of the cartridge case C together with the connection plate 53 is formed adjacent to the shutter window 54.

A spring receiving projection 55 bent from the connecting plate portion 53 of the shutter member 5 is provided on the inner surface of the front end of the shutter window 54 on the closed area side, and the shutter spring 6 is compressed by a coil spring in the opening and closing direction on the back. Dressed up,
The shutter member 5 is biased in the closing direction. As shown in FIG. 4 and FIG.
6 and 56 are cut and raised, and are engaged with guide grooves 28 extending in the left-right direction along the front edge of the lower surface of the base plate 2, thereby helping to prevent detachment during assembly.

As shown in FIG. 3, a sliding sheet 12 made of a plastic sheet or the like obtained by subjecting a PET sheet to sliding processing (Teflon processing) is interposed above and below the magnetic disk medium 10. In this sliding sheet 12, a portion corresponding to the window 8 is removed in the radial direction to form a substantially C-shape.
An opening 12a is formed at a portion opposite to the window 8, and a cleaning member 13
From the 0 side, the sliding sheet 12 is fixed to the inner top surface of the upper cover case 3 and the inner bottom surface of the concave portion 21 of the base plate 2 by the fixing of the cleaning member 13. The cleaning member 13 is brushed on the side facing the magnetic disk medium 10 and comes into contact with the surface of the magnetic disk medium 10 to remove dust on the surface. An adhesive is applied to the opposite surface of the cleaning member 13.

The assembling of the magnetic disk cartridge 1 having such a configuration is performed by the circular recess 2 of the base plate 2.
A sliding sheet 12 is fixed to the inner bottom surface of the upper cover case 3 and the inner top surface of the upper cover case 3 in advance by fixing a cleaning member 13, and the base plate 2 is inserted in a manner that the magnetic disk medium 10 is inserted below the bridge 61 from behind. After setting in the circular concave portion 21, the shutter member 5 is mounted from the front.

By mounting the shutter member 5, the shutter member 5 shown in FIG.
As is clear from FIG.
The inner surface of the front end (lower surface of the rear end) of the shutter member 5 is opposed to the upper surface 61a of the bridge-like body 61 of the base plate 2, and the inner surface of the front end of the lower plate 52 of the shutter member 5 (the upper surface of the rear end) is the base plate. The lower surface 62a of the second protruding edge 62 is closely opposed to the lower surface 62a. Subsequently, the upper cover case 3 is attached to the base plate 2 from above with the lower cover case 4 from below.
Is fitted.

Next, the upper and lower cover cases 3 and 4 are spot-welded at the portions indicated by reference symbol S in FIGS. Then, the coil-shaped shutter spring 6 is inserted into the internal spring accommodating portion 23 while bending the coil-shaped shutter spring 6 from the spring insertion opening 19 in the front wall portion of the upper and lower cover cases 3, 4, and the tip end thereof is formed by the spring receiving projection 55 of the shutter member 5. , And pushed into the storage portion 23 while shrinking the rear end to complete the assembly. The shape of the spring insertion opening 19 prevents the assembled shutter spring 6 from coming off.

When the magnetic disk cartridge 1 is loaded in the drive device, the pawl of the opening / closing mechanism is inserted into the slit 18 at the front end, engages with the end of the shutter member 5 and moves it in the opening direction. I do. Along with this, the window 8 of the base plate 2 is opened and the state shown in FIG. 2 is obtained.

As is apparent from the above description, in the present embodiment, the cartridge case C includes the base plate 2 and the cover cases 3 and 4 attached to the upper and lower surfaces of the base plate 2, respectively. Since the flat concave portion 35 is formed on the upper surface of the upper cover case 3, the strength required as a flat case can be secured.

In the present embodiment, the rear edge of the shutter operation area on the upper surface of the base plate 2
A bridge 61 integrally formed with the base plate 2 is bridged in a direction substantially parallel to the sliding direction of the shutter member 5 above the concave portion 21 for accommodating the magnetic disk medium. The inner surface (lower surface) of the distal end portion of the upper plate portion 51 of the member 5 is close to and opposed to the rear edge portion of the shutter operation area on the lower surface of the base plate 2 and from the bottom wall of the magnetic disk medium accommodating recess 21 to the shutter operation area. A protruding edge portion 62 that extends and extends in parallel with the sliding direction of the shutter member 5 is formed.
2 with respect to the lower surface 62a of the shutter member 5.
Since the inner surface (upper surface) of the front end portion of the shutter member 5 is closely opposed, the bridge-like body 61 and the protruding edge portion 62 constitute a position regulating means for the upper and lower plate portions 51 and 52 of the shutter member 5.

Therefore, when the shutter member is at the position for closing the magnetic head insertion window, a force is applied inward to the upper and lower plate portions 51, 52 exposed from the magnetic head insertion window 8. However, these face plate portions 5
The inward bending of the magnetic heads 1 and 52 is prevented, so that the inconvenience of forming a gap in the magnetic head insertion window can be eliminated.

FIGS. 8 (a) and 8 (b) are enlarged cross-sectional views of essential parts showing the second and third embodiments of the magnetic disk cartridge according to the present invention, corresponding to FIG.

In the second embodiment shown in FIG. 8 (a), the bridge-like body 61 and the protruding edge 62 in the above-mentioned first embodiment are parallel to each other at a predetermined interval. A frame 65 made of, for example, a metal material and provided separately from the base plate 2 and having an upper frame 63 and a lower frame 64 extending therefrom.
Is fixed to the base plate 2 so as to be parallel to the sliding direction of the shutter member 5. In the same manner as in the first embodiment, the inner surface (the lower surface at the rear end) of the upper end plate portion 51 of the shutter member 5 is made to closely approach the upper surface 63a of the upper frame 63, and the lower surface of the lower frame 64 The inner surface (upper surface of the rear end portion) of the lower end plate portion 51 of the shutter member 5 is made to closely approach the 64a.

In the third embodiment shown in FIG. 8B, the bridge-like body 6 in the first embodiment described above is used.
Instead of 1, only the upper frame 63 of the frame body 65 in the second embodiment is fixed to the base plate 2 so as to face the upper plate 51 of the shutter member 5, This is a case where an eclectic structure in which the protruding edge portions 62 face each other is the same as in the first embodiment.

In the second and third embodiments, also,
It is clear that the same effects as in the first embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a magnetic disk cartridge according to the present invention.
In the embodiment, a perspective view from the top side showing a state in which a window for inserting a magnetic head is closed by a shutter member.

FIG. 2 is a perspective view of the magnetic disk cartridge shown in FIG. 1, showing a state in which a window for inserting a magnetic head is opened, as viewed from a lower surface side;

FIG. 3 is an exploded perspective view of the magnetic disk cartridge shown in FIGS. 1 and 2;

FIG. 4 is an exploded perspective view of the base plate and a shutter member attached thereto viewed from the back side.

5 (a) is a plan view of a base plate, FIG.
(B) is a bottom view of the base plate.

FIG. 6 is an enlarged sectional view taken along line VI-VI of FIG.

FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG.

8 (a) is an enlarged sectional view corresponding to FIG. 6 showing a magnetic disk cartridge according to a second embodiment of the present invention, and FIG. 8 (b) is a third embodiment of the magnetic disk cartridge according to the present invention. FIG. 6 is an enlarged cross-sectional view illustrating the embodiment and corresponding to FIG. 6.

FIG. 9 is an explanatory diagram of an operation of the shutter member when no regulating means is provided.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic disk cartridge C cartridge case 2 Base plate 3 Upper cover case 4 Lower cover case 5 Shutter member 6 Shutter spring 8 Window for inserting a magnetic head 10 Magnetic disk media 11 Center core 18 Slit 19 Spring insertion port 21 Circular recess 23 Spring storage section 25 Corner Parts 51, 52 Face plate part of shutter member 53 Connecting plate part of shutter member 61 Bridge-like body (restriction means) 62 Projection edge part (restriction means) 63 Upper frame of frame-like body (restriction means) 64 Lower frame of frame-like body (Regulatory means) 65 Frame

Claims (1)

[Claims] 1. A disk-shaped magnetic disk medium is rotatably accommodated in a flat cartridge case having a window for inserting a magnetic head, and between an open position for opening the window and a closed position for closing the window. A magnetic disk cartridge comprising a shutter member slidably mounted on the cartridge case, wherein the cartridge case covers a base plate having a concave portion for accommodating a magnetic disk medium formed on an upper surface and upper and lower surfaces of the base plate. The shutter member is constituted by upper and lower face plate portions and a connecting plate portion that connects the face plate portions at a front end, and is mounted on the base plate inside the upper and lower cover cases. The shutter member is provided in a shutter operation area of the base plate. And a restricting means for preventing the front end of the face plate portion from bending inward.