JP2001236759A - Magnetic disk cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin type magnetic disk cartridge which is as thin as to be loadable together with a drive assembly to a PC card slot, has a large memory capacity and is mounted with a shutter member for opening and closing a window part for accessing a magnetic head while subjecting the member to prevention of disengagement and having stable operation and assemblability. SOLUTION: The cartridge case C for housing a magnetic disk medium 10 comprises a base plate 2 and cover cases 3 and 4 of an approximately plane shape to be put thereon. The case window part 8 for accessing the magnetic head is formed by penetrating and removing the front end and the top and under surfaces succeeding thereto. The cover shutter member 5 of a U shape in section having the shutter window part 54 communicatable with the cave window part 8 is mounted at the base plate 2 and thereafter the cover cases 3 and 4 are put therein. Upper and lower surface plate parts 51 and 52 of the shutter member 5 and a connecting part 53 are made slidable in the spacings disposed between the base plate 2 of a region near the window part 8 and the cover cases 3 and 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin magnetic disk cartridge having a large recording capacity and containing a disk-shaped magnetic disk medium in a case.

[0002]

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

The magnetic disk cartridge is provided with a magnetic head insertion window through which a magnetic head for magnetic recording / reproducing is inserted into or removed from one or both sides of the magnetic disk medium because the magnetic head comes in contact with or approaches from outside. Further, the window is provided with an opening / closing shutter member for preventing dust and the like from entering when not in use.

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 is now being sold. The adoption of this external method is excellent in terms of portability of small personal computers, but, for example, the problem of not being able to record and reproduce large amounts of data because magnetic disk cartridges cannot be used at the destination of small computers, This causes a problem that data cannot be recorded on a plurality of magnetic disk cartridges.

[0005] In view of the above, some small personal computers are provided with a PC card slot (compliant with the PCMCIA specification) for an external interface and additional memory, and are used by mounting a PC card using an electronic circuit such as a memory card. You. Therefore, it has been proposed to configure an external storage device using a magnetic disk cartridge using the PC card slot.

A PC that can be inserted into the PC card slot
The specification of the card is type II, the thickness is 5.0 mm, and the magnetic disk cartridge and the disk drive are to be included in this thickness. Therefore, the thickness as a magnetic disk cartridge is 2-3 mm by design. It is necessary to make it ultra-thin.

[0007] Even when such a thin magnetic disk cartridge is constructed, the recording capacity required as a recording medium is large, and in order to increase the recording density and secure the maximum recording capacity, the transfer rate is increased. The drive rotation speed needs to be increased, and the magnetic head of the drive device needs to adopt the same mechanism as that used in the hard disk drive device. In addition, it is necessary to provide a magnetic head access window so that the recording / reproducing magnetic head can access the magnetic disk medium in a small space.

In a conventional general magnetic disk cartridge, a shutter member for opening and closing the window is provided in an external shutter structure slidably mounted on a surface portion of the cartridge case. A guide claw protrudes from the inner surface of the shutter member so that the shutter member does not come off the case, and the guide claw is engaged with a guide groove provided in the opening and closing direction on the surface of the case.

[0009]

However, when the above-described ultra-thin magnetic disk cartridge is constructed,
As with the shutter member of a conventional magnetic disk cartridge, even if an external shutter structure is provided with a mechanism for preventing detachment by a guide claw, the guide groove becomes shallower as the case becomes thinner, and the guide claw becomes larger. It is difficult to provide the case, and there is a problem that a sufficient detachment preventing function cannot be obtained with a decrease in the strength of the case.

Accordingly, when the magnetic disk cartridge is inserted into or removed from the drive, the shutter member is caught and detached from the case and is left in the apparatus, or the shutter member is removed from the case due to an impact when the magnetic disk cartridge falls. It is easy to cause malfunctions such as deviating or tilting, and malfunctions that affect the recording / reproducing characteristics due to dust entering through the opened windows.

Therefore, in the present invention, the shutter member is configured to be of a built-in type to prevent the shutter member from coming off. In such a configuration, the stable operation of the thin and miniaturized components is achieved. Therefore, it is necessary to secure the function stability and to secure the productivity with a structure that is easy to assemble even small parts.

In view of the above circumstances, the present invention is thin and has a large recording capacity so that it can be loaded into a PC card slot together with a disk drive, and it is preferable that a shutter member for opening and closing a window for magnetic head access is not removed. It is an object of the present invention to provide a magnetic disk cartridge which can be installed with an easy assembling property.

[0013]

A magnetic disk cartridge according to the present invention which has solved the above-mentioned problems has a flat cartridge case for rotatably storing a disk-shaped magnetic disk medium, and the magnetic head accesses the cartridge case. In a magnetic disk cartridge having a possible window formed therein and a shutter member for opening and closing the window, the cartridge case is attached to a base plate having a circular concave portion for accommodating a magnetic disk medium, and is mounted on and under the base plate. A cover case having a substantially planar shape, wherein the shutter member is slidably disposed between the base plate and the cover case, and the window has a front end portion of the base plate and the cover case and upper and lower surfaces following the front end portions. The shutter member has upper and lower face plate portions and this face A shutter window portion is formed in a substantially U-shaped cross section from a connecting portion connecting the portions, and a shutter window portion that can communicate with the window portion is formed in the connecting portion and the upper and lower face plate portions, and a base plate and a cover case in a region near the window portion are formed. The upper and lower plate portions and the connection portion of the shutter member are slidable in a gap provided therebetween, and the cover case is attached after attaching the shutter member to the base plate.

The shutter member has a guide claw on at least one of the upper and lower surface plate portions, and the base plate has a guide groove which allows the guide claw to slide in a direction perpendicular to the cartridge insertion direction. Preferably, the shutter member mounted on the base plate is engaged and held by a guide claw and a guide groove.

A slit groove extending in the opening and closing movement direction of the shutter member is formed in a front wall portion of the cover case, and a drive-side shutter opening and closing member is inserted through the slit groove to engage an engagement end of a connecting portion of the shutter member. It is preferable that the opening and closing operation be performed by engaging with the portion.

[0016]

According to the magnetic disk cartridge of the present invention as described above, a flat cartridge case for rotatably storing a disk-shaped magnetic disk medium is provided on a base plate and a cover case having a substantially planar shape to be attached to the base plate. A shutter having a magnetic window access window portion formed by penetrating and removing the front end portion of the base plate and the cover case and the upper and lower surfaces following the front end portion, and having a U-shaped cross section and communicating with the window portion. After the member is mounted on the base plate, the cover case is attached, and the upper and lower plate portions and the connection portion of the shutter member are slidable in the gap provided between the base plate and the cover case in the area near the window, so that the shutter Even if it is thin, it is basically a shutter part by incorporating a member and covering the front side with a cover case. The shutter member slides between the base plate and the cover case, so that a stable sliding operation can be obtained.Thus, even if it is thin and small, functional stability can be secured. Productivity can be improved with an easy-to-assemble structure.

Further, when the shutter member mounted on the base plate is held by engaging the guide claw provided on at least one of the upper and lower plate portions with the guide groove of the base plate, the shutter member is prevented from coming off from the base plate during the assembly. Good assemblability can be obtained.

Further, the drive-side shutter opening / closing member engages with the engagement end of the shutter member through the slit groove formed in the front wall portion of the cover case to perform the opening / closing operation of the shutter member. Open / close operation can be obtained.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 is a perspective view of an upper surface side of a magnetic disk cartridge according to this embodiment.
FIG. 1 is a perspective view of the lower surface side. FIG. 1 shows a state where the shutter member is closed, and FIG. 2 shows a state where the shutter member is open. 3 is an exploded perspective view of the magnetic disk cartridge, FIG. 4 is a perspective view of the lower surface side of the base plate, and FIG. 5 is a sectional side view of a main part of a front end portion of the magnetic disk cartridge. In addition, in each figure, in order to clarify the structure, the thickness and the like of each part 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 includes a base plate 2 serving as a central member,
An upper cover case 3 and a lower cover case 4 are attached to the upper and lower sides of the base plate 2 and have a substantially planar shape. The magnetic disk medium 10 has a disk-shaped base made of a flexible polyester sheet or the like, on both sides of which magnetic layers are formed.
(Center core) is fixedly integrated.

A hub hole 7 is provided on the lower surface of the cartridge case C so that the drive motor of the drive unit and the rotary drive hub 11 can be chucked, and the bottom of the rotary drive hub 11 faces the hub hole 7. The magnetic disk medium 10 is housed in the cartridge case C. Also,
Insertion direction D of cartridge case C with respect to drive
A window 8 is formed at the front end with respect to (the arrow in FIG. 1) so that the magnetic head for recording and reproduction can be accessed. Window 8
The front end portions of the base plate 2 and the upper and lower cover cases 3 and 4 are opened, and a portion communicating with the upper and lower surfaces is subsequently opened vertically in a rectangular shape (see FIG. 2). Shutter member 5 for opening and closing this window 8
Are slidably mounted in the left and right directions inside the upper and lower cover cases 3 and 4. With the structure of the window 8 as described above, the magnetic head for recording / reproducing can access the inside of the window 8 from the front side without opening and closing greatly.

The structure of each component will be specifically described with reference to FIG. First, the base plate 2 is made of, for example, an acrylonitrile-butadiene-styrene copolymer (ABS resin)
Alternatively, it is a substantially rectangular flat plate formed of a synthetic resin such as a POM resin or the like. A circular recess 21 for accommodating the magnetic disk medium 10 is provided at the center of the upper surface. A hub hole 7 is opened in the portion. Further, the front side portion of the bottom plate is removed in a substantially rectangular shape to form a sliding portion 22 (see FIG. 4) into which a lower surface plate portion 52 of the shutter member 5 described later is slidably inserted. The central portion is removed in the front-rear direction, and a window 8 penetrating vertically is opened. The upper surface portion corresponding to the sliding portion 22 is formed slightly lower than other portions. If there is a margin in the thickness direction of the base plate 2, the sliding portion 22 may be formed in a thin groove shape from the bottom side.

The front end of one of the front ends of the base plate 2 has its front face retracted from the other front wall to form a spring accommodating portion 23, in which a shutter spring 6 described later is disposed.
Further, a tapered portion 24 is provided at a front corner facing the window portion 8 of the front wall on the opposite side of the spring storage portion 23, so that the shutter member 5 is guided when the shutter member 5 is closed. Are provided so that the base plate 2 can be securely closed and the base plate 2 is not scraped by interference.

Further, four corners 25 of the four corners of the base plate 2 are provided so as to protrude in the vertical direction and have a large thickness and protrude outward. Four corners of the upper and lower cover cases 3 and 4 corresponding to these corners are provided. When the upper and lower cover cases 3 and 4 are fitted to the base plate 2, the corners 25 of the base plate 2 are exposed to the outside. Each corner portion 25 is provided in such a shape that its surface protrudes flush or outward with the surface of the upper and lower cover cases 3 and 4.

The corner portion 25 of the base plate 2 is exposed to the outside, so that when a shock or the like at the time of a drop is applied, the shock can be absorbed by the corner portion 25 and at the time of insertion and removal operations with respect to the drive device. , Which prevents it from getting stuck and ensures stable operation. Also, holes 26 penetrating in the vertical direction are provided in each corner 25.
(It may be a hole of intermediate depth without penetrating),
Greater buffering action at the time of a drop impact is obtained. The base plate 2 is a magnetic disk medium 1
0 has a strength that allows deformation that does not hinder recording and reproduction. It is preferable that the base plate 2 is made of an elastic plastic from the viewpoint of absorbing the impact, and it is preferable that the base plate 2 contains a lubricant from the viewpoint of sliding with the shutter member 5 to improve dimensional accuracy. From the viewpoint of assembling with the cover cases 3 and 4, it is preferable to include a filler material.

A notch-shaped concave portion 15 is provided on the side surface of the corner portion 25 on both sides of the front portion of the base plate 2 as shown in FIG. 1, and this concave portion 15 is used for positioning when mounted on the drive device, or Are formed to prevent 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 shown in the figure, the corner of one of the front corners 25 is formed in the oblique cutout 16 to serve as an erroneous insertion prevention part.

Further, a part of the side surface of the cartridge case C is located at a position different from the concave portion 15, for example, as shown in FIG.
The identification portion 17 is provided on the side wall portion of the recording device 4, and a disc type (for example, a recording capacity type) and a write protector portion may be provided. The identification unit 17 may be provided with an identification piece that enables the detection function to be turned on / off so that it can be inserted or inserted / extracted. The concave portion 15 and the identification portion 17 are formed on the side surface, so that a drive-side detection mechanism or the like having no installation space in the vertical direction can be arranged on the side.

Next, the upper and lower cover cases 3 and 4 are formed of a high-strength material such as a pressed stainless steel plate.
The upper cover case 3 and the lower cover case 4 are substantially symmetrical, the corners of the four corners are removed in a rectangular shape, a plane rectangular window 8 is opened in the center of the front part, and the front, rear, left and right edges are squared. It is bent, and the front wall portions 31 and 41 and the side wall portions 3 are respectively provided.
2, 42, and rear wall portions 33, 43.

As shown in FIG. 5, the bent portions of the front wall portions 31 and 41 are formed in an arc shape in cross section. One of the front wall portions 31 and 41 is lower in height than the window portion 8, and when the upper and lower cover cases 3 and 4 are attached to the base plate 2, the slit groove 18 (see FIG. 1), and the leading end of the drive-side shutter opening / closing member 60 can be inserted and moved. The opposite front wall 31,
41, that is, a portion located in front of the spring storage portion 23 is provided with a notch on the end side,
When the front wall portions 31 and 41 of the shutter 4 are fitted together, they form a rectangular spring insertion port 19 (see FIG. 1), and are used for mounting the shutter spring 6. The shutter opening / closing member 60 (opening / closing lever) is moved by a driving mechanism (not shown) in accordance with the insertion operation of the magnetic disk cartridge 1.
Is rotated in the opening direction, and the return spring 61 is rotated.
Are connected so as to return to the closing direction. Note that the magnetic disk cartridge 1 is turned upside down in FIG.
When the shutter opening / closing member 60 is
Is locked by engaging with the spring insertion port 19.

At the center of the upper cover case 3, a rectangular or semicircular concave portion 35 serving as a label sticking portion is formed on the upper surface, and the bottom surface of the concave portion 35 projects downward into the circular concave portion 21. The recess 35 reduces the upper space according to the thickness of the bottom plate of the base plate 2 so that the magnetic disk medium 10 is located at the center in the thickness direction in the assembled state, and the upper and lower spaces thereof are even. The rotational stability of the disk medium 10 is improved. Lower cover case 4
A hub hole 7 is opened at a central portion of.

When the upper and lower cover cases 3 and 4 are assembled to the base plate 2, the front surface of the base plate 2 and the upper and lower cover cases 3 and 4
The dimension is set such that a thin gap in which the shutter member 5 can slide is formed in the area near the window 8 in the lateral direction between the inner surface of the shutter 4 and the inner surface of the shutter 4. The method of fixing the base plate 2 to the upper and lower cover cases 3 and 4 may be such that the contact portions of the upper and lower cover cases 3 and 4 are mutually joined by spot welding, bonding, caulking, or the like. This is performed by fixing the cases 3 and 4 by caulking, bonding or the like.

Next, the shutter member 5 is inserted into a sliding portion 22 formed on the base plate 2 between the base plate 2 and the upper and lower cover cases 3 and 4, particularly on the lower surface side, so as to be slidable in the left and right opening and closing directions. Be attached. The shutter member 5 is made of metal, for example, formed in a substantially U-shaped cross section from a stainless steel plate or an aluminum plate. The upper plate portion 51 and the lower plate portion 52 are connected by a connecting portion 53 at the front end. The height of 53 is substantially equal to the thickness of the front part of the base plate 2. A rectangular shutter-opening portion 54 is provided from the connecting portion 53 to communicate with the upper surface plate portion 51 and the lower surface plate portion 52, and the window portion 8 of the cartridge case C is provided.
Can be communicated with this at the time of the opening operation. The shutter window 54 is provided at a position offset from the center of the shutter member 5.

As shown in FIG. 5, the cross-sectional shape of the connecting portion 53 is such that the front wall portions 31,
The connecting portion 53 is separated from the front end surface of the shutter opening and closing member 60 when it is assembled to the base plate 2 so as to be easily engaged with the shutter opening / closing member 60. The shutter window 54
A spring receiving projection 55 bent from the connecting portion 53 is provided on the inner surface of one of the front ends, and a shutter spring 6 made of a coil spring is compressed on the back of the projection 55 in the opening and closing direction and urged in the closing direction.

The upper plate 51 and the lower plate 5
2, a reinforcing rib 56 is formed to prevent deformation due to pressing by the shutter opening / closing member 60 during the opening operation. The reinforcing ribs 56 are formed in a projecting shape protruding outward to suppress the generation of abrasion powder and the like caused by the tips of the upper and lower plate portions 51 and 52 contacting the upper and lower cover cases 3 and 4. It also has the effect of reducing the frictional resistance of the device and ensuring the stability of the opening and closing operation.

Further, guide claws 57 (see FIG. 5) are cut and raised at both ends of the lower surface plate portion 52, while guide grooves extending in a direction perpendicular to the cartridge insertion direction D are formed on the front bottom surface of the base plate 2. 27 (see FIG. 4) is provided, and a guide claw 57 is slidably engaged with the guide groove 27 to prevent detachment during assembly. The guide claw 5
7 may be provided on the upper surface plate portion 51, and the upper and lower plate portions 5
1, 52 may be provided.

The shutter member 5 may be provided in a structure in which the hub hole 7 on the bottom surface is also opened and closed. In this case,
The lower plate portion 52 of the shutter member 5 is extended to the portion of the hub hole 7, and the hub hole 7 is closed by the lower plate portion 52 at the time of closing movement.
The hub hole 7 is formed so as to open according to the opening movement.

Above and below the magnetic disk medium 10, a protective sheet 12 made of a plastic sheet or the like having a PET sheet surface subjected to a sliding process (Teflon process) is interposed. The protective sheet 12 is provided in a substantially C shape in which a portion corresponding to the window portion 8 is removed in the radial direction.
An opening 12a is formed in a portion opposite to the above, and a cleaning member 13 is fixed to the inner surface of the upper cover case 3 and the bottom surface of the base plate 2 from the magnetic disk medium 10 side in this portion. Fixed. The cleaning member 13 is provided with a raised surface on the side facing the magnetic disk medium 10 to contact the surface of the magnetic disk medium 10 to remove dust on the surface, and has an adhesive on the opposite surface.

The magnetic disk cartridge 1 as described above
Is assembled by fixing the protection sheet 12 to the circular recess 21 of the base plate 2 and the lower surface of the upper cover case 3 in advance by fixing the cleaning member 13, and setting the magnetic disk medium 10 in the circular recess 21 of the base plate 2. Slide the shutter member 5 from the front to the guide claw 5
7 is engaged with the guide groove 27 and mounted. Subsequently, the upper cover case 3 is fitted to the base plate 2 from above and the lower cover case 4 is fitted and held from below to integrate them. Thereby, the circular concave portion 21 of the base plate 2
Is covered with the upper cover case 3, and the upper cover case 3
The flat space defined by the circular concave portion 21 defined by the bottom surface of the magnetic disk medium 10 is a storage space for the magnetic disk medium 10, and the magnetic disk medium 10 is rotatably stored. Thereafter, the spring insertion holes 19 in the front wall portions of the upper and lower cover cases 3 and 4 are formed.
The flexible shutter spring 6 is inserted into the internal spring accommodating portion 23 while being bent, and the leading end thereof is brought into contact with the spring receiving projection 55 of the shutter member 5, and is pushed into the accommodating portion 23 while contracting the rear end. To complete the assembly. In addition,
The opening shape of the spring insertion port 19 prevents the assembled shutter spring 6 from coming off. Since the slits 18 are narrower than the thickness of the cartridge case C, the sliding of the shutter member 5 does not become unstable even if the slits 18 are formed.

The magnetic disk cartridge 1 as described above
When inserted into the drive device, the leading end of the shutter opening / closing member 60 is inserted into the slit groove 18 at the front end,
The shutter member 5 is engaged with an end portion thereof and is moved in the opening direction. The drive unit has a magnetic head at the back, and a drive unit below the drive unit so as to be able to move up and down.
The spindle is locked to the rotation drive hub 11 of the magnetic disk medium 10 and is driven to rotate.

With the structure of the cartridge case C as described above, the strength of the magnetic disk
Is formed within a predetermined thickness, and the thickness of the magnetic disk cartridge 1 can be reduced while ensuring operation reliability, so that an external storage device that can be mounted in a PC card slot can be configured. In particular, sufficient strength is secured by integrating the base plate 2 and the cover cases 3 and 4. The cover cases 3 and 4 are made of thin metal and easily deformed in a single piece state, and the base plate 2 is also made of plastic and easily twisted and deformed.
Magnetic disk cartridge 1 by combining both
Suffices to meet the requirements and maintain dimensions.

Further, since the shutter member 5 has a built-in structure, the shutter member 5 covered with the upper and lower cover cases 3 and 4 is not caught at the time of insertion and removal from the drive even if the case member is thin and the case strength is reduced. ,Also,
It does not come off even when it is dropped, and reliability in use is increased. Furthermore, the shutter member can slide in the gap provided between the base plate and the cover case, so that the shutter member slides between the base plate and the cover case. Even so, functional stability can be ensured. The cover case is attached after the shutter member is mounted on the base plate. In particular, by holding the shutter member mounted on the base plate by engaging the guide claws with the guide grooves, the cover cases 3 and 4 can be easily assembled, Good assemblability can be obtained with a structure that is easy to assemble even small parts.

[Brief description of the drawings]

FIG. 1 is a top perspective view of a magnetic disk cartridge according to one embodiment of the present invention.

FIG. 2 is a perspective view of the lower surface side of the magnetic disk cartridge of FIG. 1 in a state where a shutter member is opened.

FIG. 3 is an exploded perspective view of the magnetic disk cartridge of FIG. 1;

FIG. 4 is a perspective view of a lower surface side of a base plate.

FIG. 5 is a sectional view of a main part of a front end portion of the magnetic disk cartridge.

[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 7 Hub hole 8 Window 10 Magnetic disk media 11 Hub 18 Slit groove 19 Spring insertion opening 21 Circular recess 22 Sliding part 27 Guide groove 51 Upper plate 52 Lower plate 53 Connecting part 54 Shutter window 57 Guide claw 60 Shutter opening / closing member

Claims (3)

[Claims] A flat cartridge case for rotatably accommodating a disk-shaped magnetic disk medium, a window portion accessible to a magnetic head is formed in the cartridge case, and a shutter member for opening and closing the window portion is provided. In the magnetic disk cartridge provided, the cartridge case comprises: a base plate having a circular concave portion for accommodating a magnetic disk medium; and a substantially planar cover case attached to the top and bottom of the base plate. The shutter member is slidably disposed therebetween, and the window portion has a base plate and a front end portion of a cover case and an upper and lower surface following the front end portion are removed therethrough. The shutter member has upper and lower face plate portions and this face plate A cross section is formed in a substantially U-shape from a connecting portion connecting the portions, and the connecting portion and the upper and lower face plate portions are formed. A shutter window portion that can communicate with the window portion is formed, and the upper and lower plate portions and the connection portion of the shutter member are slidable in a gap provided between the base plate and the cover case in a region near the window portion, and the base plate is A magnetic disk cartridge wherein the cover case is attached after attaching a shutter member. 2. The shutter member has a guide claw on at least one of the upper and lower surface plate portions, and the base plate has a guide groove that allows the guide claw to slide in a direction perpendicular to the cartridge insertion direction. 2. The magnetic disk cartridge according to claim 1, wherein the shutter member mounted on the base plate is engaged and held by a guide claw and a guide groove. 3. A slit groove extending in the opening and closing movement direction of a shutter member is formed in a front wall portion of the cover case,
3. The magnetic disk cartridge according to claim 1, wherein a shutter opening / closing member on a drive side is inserted through the slit groove and is engaged with an engagement end of a connecting portion of the shutter member.