JPH10106207A - Magnetic disk cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a magnetic disk cartridge from being misloaded into a small- capacity type disk driving apparatus, and prevent dust from entering the magnetic disk, by locking a shutter member at a closing position so as to prevent the shutter member from unnecessarily opening, thereby achieving high reliability. SOLUTION: The magnetic disk cartridge can rotatably house a large-capacity disk-shaped magnetic disk medium 6 within a case 2. The case 2 is provided with openings 11 and 12 through which a magnetic head is to be inserted, and a shutter member 13 for opening and closing these openings 11 and 12. The case 2 has a planar shape which is common to a small-capacity magnetic disk cartridge, while a size in the thickness direction of the case 2 is about 1.3 to 2.0 times as thick as the smallcapacity magnetic disk cartridge, thereby preventing misloading. The case 2 has a locking member 4 for locking the shutter member 3 at a closing position, while a recessed portion 25 is formed on a front end face 2c of the case into which a shutter opening and closing pin is to be inserted at the initial period of the opening operation. A portion of the locking member 4 is exposed in the recessed portion 25. The shutter opening and closing pin is allowed to come into contact with the locking member 4, thereby releasing its locking condition.

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 large-capacity magnetic disk medium is accommodated in a case, and the magnetic disk medium is rotated and used for magnetic recording and reproduction. The present invention relates to a magnetic disk cartridge which is prevented from being erroneously loaded into another small capacity type magnetic disk cartridge recording / reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk (a so-called floppy disk) in which magnetic layers are formed on both surfaces 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 rotating. Disc) is provided, and is mainly used as a recording medium for a computer because of its advantages such as easy handling and low cost.

Recently, this type of magnetic disk, such as a so-called 3.5-inch type, is rotatably housed in a small hard case and used as a magnetic disk cartridge. More.

In a magnetic disk cartridge of this type using a hard case, an opening for inserting a magnetic head is provided in the case, and this opening is always closed by a shutter urged in one direction except during use.
Therefore, consideration is given to prevent foreign matter such as dust from entering the case.

By the way, such a magnetic disk cartridge is always required to have a large capacity.
5 inch type storage capacity 1MB (megabyte) or 2
MBs have already been put into practical use and now have a storage capacity of 100M
B and more are also being offered.

[0006]

As described above, when a magnetic disk cartridge having a recording capacity higher than that of a conventional product is provided, a disk drive for driving the large-capacity type magnetic disk cartridge is newly provided. May be provided. This new disk drive device can drive a new large-capacity type magnetic disk cartridge, and in many cases, for the convenience of the user, a so-called "lower compatibility" function, that is, a lower capacity in terms of recording capacity. Such a conventional magnetic disk cartridge is often formed to have a function of driving.

In order to realize the function of backward compatibility, a new large-capacity magnetic disk cartridge is formed such that the outer shape of the case or the like substantially matches the conventional small-capacity magnetic disk cartridge. For this reason, there is a risk that a new large-capacity magnetic disk cartridge that looks similar to a conventional small-capacity magnetic disk cartridge may be erroneously loaded into a disk drive for a small-capacity magnetic disk cartridge.

Conventional disk drives for small-capacity magnetic disk cartridges often do not provide sufficient protection for new large-capacity magnetic disk cartridges. If the disk drive device operates when a disk cartridge is erroneously loaded, information recorded on the magnetic disk cartridge may be destroyed.

In the above situation, the occurrence of erroneous recording / erase can be prevented by providing a capacity discriminating hole or the like. However, a large-capacity magnetic disk cartridge loaded into a small-capacity type magnetic disk drive is There is a possibility that the lower magnetic head comes into contact with the magnetic disk medium by inserting the shutter member into the proper loading position and opening the shutter member. At the time of this contact, foreign matter, dust, and the like adhering near the magnetic head may adhere to the large-capacity magnetic disk medium.

[0010] In this large-capacity magnetic disk, the increase in capacity can be obtained by increasing the density. As a result, the recording wavelength is shortened and the recording track width is narrowed. If there is, there is a possibility that a read error of recorded data occurs.

Further, the shutter member of the magnetic disk cartridge is simply closed by being urged by a spring member. When the user slides the shutter member by hand, the shutter member moves to open the magnetic head insertion opening. What is done
Accordingly, dust may enter, and it is preferable to prevent the occurrence of such a state and to prevent the adhesion of dust.

Accordingly, the present invention does not provide a magnetic disk cartridge which prevents loading of a lower disk drive for a magnetic disk cartridge in terms of capacity and prevents the shutter member from being opened unnecessarily. It is assumed that.

[0013]

A magnetic disk cartridge according to the present invention, which has solved the above-mentioned problems, accommodates a disk-shaped large-capacity magnetic disk medium rotatably in a case, and has a magnetic head insertion opening in the case. A shutter member for opening and closing this opening, and a spring member for urging the shutter member in the closing direction are provided. The planar shape of the case is the same as that of the small-capacity magnetic disk cartridge, The shutter member has a thickness of about 1.3 to 2.0 times the thickness of the small-capacity magnetic disk cartridge, and the shutter member has the same planar position and open / close direction as the small-capacity magnetic disk cartridge. A lock member for locking the shutter member in a closed position by locking the shutter member to a part of the shutter member, The front end face of the case is provided with a recess in which a shutter opening / closing pin provided in advance in a magnetic disk drive engaging with one end of the shutter member in the closed position is inserted at an early stage of the opening operation. A part of the lock member is exposed, and the shutter opening / closing pin contacts the lock member to release the locked state.

When the magnetic disk cartridge as described above is to be inserted into a drive for a small-capacity magnetic disk cartridge, the magnetic disk cartridge cannot be physically inserted through the insertion opening of the small-capacity magnetic disk drive because of its large thickness. Erroneous loading can be prevented without opening the shutter member. Also, in this unused magnetic disk cartridge, the shutter member is operated to the closed position by the spring member to close the magnetic head insertion opening,
The shutter member in the closed position is locked by locking with the lock member, and is locked even if the user touches the shutter member to move the shutter member in the opening direction, so that the shutter member is unnecessarily opened. This prevents the intrusion of dust even further, thereby preventing dust from adhering to the magnetic disk medium.

Further, when the magnetic disk cartridge of the present invention is inserted into a large-capacity type magnetic disk drive, the shutter opening / closing pin engages one end of the shutter member to open the shutter member at an initial stage. The shutter opening / closing pin comes into contact with the lock member to release the locked state of the shutter member, and at the same time, moves the shutter member to open a magnetic head insertion opening, through which the magnetic head is inserted. Magnetic recording and reproduction are performed. When used and ejected, the shutter member moves in the closing direction to close the magnetic head insertion opening, and when taken out of the magnetic disk drive, the shutter member is locked by the lock member in the closed position and held in the locked state. You.

When a small-capacity magnetic disk cartridge is inserted into the large-capacity magnetic disk drive, the insertion opening is large and a lower magnetic disk cartridge can be inserted. When the external shape is the same, the magnetic head is set at the same position, the magnetic head can be approached to the magnetic disk medium in the same way, and by using a multi-track head for the magnetic head, it is possible to cope with each recording density, And a backward compatible function is obtained.

In addition, a wall portion is extended above the concave portion,
It is preferable to cover the lock member exposed in the concave portion, since the lock release operation of the lock member is protected and the lock release other than the release operation by the shutter opening / closing pin can be prevented. At this time, it is preferable from the viewpoint of backward compatibility that the height of the concave portion should be greater than the thickness of the small-capacity magnetic disk cartridge. Further, it is also preferable that the planar shape of the concave portion is the same as that of the small-capacity magnetic disk cartridge from the viewpoint of backward compatibility.

On the other hand, the lock member is constituted by an elastic member, a locking portion provided at the tip is provided so as to engage with the shutter member, and after the lock is released by the shutter open / close pin, the open / close pin releases the lock member. If not pressed, no excessive force is generated in the lock member except during the shutter opening / closing operation, so that so-called creep deformation does not occur, which is preferable in terms of durability and the like.

[0019]

According to the present invention as described above, the case for rotatably accommodating the large-capacity magnetic disk medium has the same planar shape as the case of the small-capacity magnetic disk cartridge, Dimensions about 1.3 ~
The thickness of 2.0 times prevents erroneous loading of the small-capacity magnetic disk drive, preventing damage to recorded data and avoiding contact with the magnetic head, thereby preventing foreign matter such as dust. Adhesion can also be prevented, and the occurrence of read errors and the like can be suppressed. Furthermore, by locking the shutter member closed position with the lock member,
Unnecessary opening operation can be prevented, and further entry of dust and adhesion to a magnetic disk medium can be further prevented, recording quality can be improved, and reliability can be improved. In addition, since the lock member can be unlocked by using an opening / closing pin of a shutter member applicable to a small-capacity magnetic disk cartridge, simplification and cost reduction can be achieved by using a common disk drive device, and backward compatibility is secured. It becomes possible.

Further, the wall provided above the concave portion prevents the lock member from being erroneously released by a member other than the shutter opening / closing pin, thereby further reducing the erroneous opening operation of the shutter member and preventing the intrusion of dust. Can be prevented. In particular, if the height of the recess is greater than the thickness of the small-capacity magnetic disk cartridge, the shutter opening / closing pin is also less than the height of the recess, so that the shutter opening / closing mechanism of the small-capacity magnetic disk cartridge can be used in common and better backward compatibility Is obtained.

Further, the lock member is made of an elastic member to perform a lock operation and a release operation by its elastic deformation, so that the lock member is not always pressed by the shutter opening / closing pin, so that the lock member is cost-effective. It is possible to secure the lock operation reliability without any settling due to creep or the like, and the operation can be automatically performed in conjunction with the insertion of the magnetic disk cartridge and the ejector operation.

[0022]

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 plan view of an example of a large-capacity magnetic disk cartridge, FIG. 2 is a front view of the magnetic disk cartridge with a shutter member opened, FIG. 3 is a bottom view thereof, and FIG. 4 is an enlarged sectional view.
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 is held in a case 2 (hard case) made of a synthetic resin such as acrylonitrile-butadiene-styrene copolymer, with a central portion attached to a center core member 5. A disk-shaped magnetic disk medium 6 is rotatably accommodated. The center core member 5 magnetically engages with a rotating spindle of a magnetic disk drive (not shown) to transmit a rotating force to the magnetic disk medium 6. The magnetic disk medium 6 has a disk-shaped base made of a flexible polyester sheet or the like and a magnetic layer formed on both sides.

The case 2 is formed by fixing two shell halves, an upper case 21 constituting the upper surface 2a and a lower case 22 constituting the lower surface 2b, in a lid-like manner.
The planar outer shape of the case 2 is a small-capacity magnetic disk cartridge 50 whose partial cross section is shown in FIG.
(Recording capacity 3.5-inch magnetic disk cartridge of 1～2MB) is a common shape with the thickness dimension H ₁ of the case 2 of the present invention, the thickness H ₀ of the casing 52 of the small-capacity magnetic disk cartridge 50 Approximately 1.3 to
It has a thickness of 2.0 times.

The position of the large-capacity magnetic disk medium 6 built in the case 2 in the rotationally driven state is determined by the height h of the lower surface 2b (reference surface) of the case 2 and the magnetic capacity of the small-capacity magnetic disk cartridge 50. The height is set to be the same as the height h from the lower surface (reference surface) of the disk medium 56. That is, the large-capacity magnetic disk medium 6
Is the lower case 2 below the center of the thick case 2
2 is held at a position offset to the inner surface of the upper case 2
A large space is formed between the inner surface and the inner surface for inserting a magnetic head.

A lower surface magnetic head insertion opening 11 extending in a rectangular shape from the front end to the center portion is provided in the lower surface 2b of the case 2, and the lower surface magnetic head insertion opening 11 is provided.
The front end face 2c of the case 2 is provided with an end face magnetic head insertion opening 12 having the same width and opening up to the upper part.

At the center of the lower case 22, a hub hole 23 for exposing the center core member 5 is formed in a circular shape. A liner 7 made of a nonwoven fabric fixed to the lower case 22 is interposed between the lower surface of the magnetic disk medium 6 and the inner surface of the lower case 22. A liner may be interposed also on the upper surface side of the magnetic disk medium 6.

Further, a shutter member 3 slidable in the left-right direction in the figure is assembled to the case 2 to open and close the magnetic head insertion openings 11 and 12, and the case 2 in the sliding range is mounted. Shallow sliding groove 24 on the surface of
Are formed. The shutter member 3 is made of, for example, a stainless steel plate or an aluminum plate, or a plastic such as polyacetal resin. FIG. 5 is a perspective view from the upper side and FIG. As shown in the perspective view of FIG. 2, an upper surface plate portion 31 having a shorter length in a direction orthogonal to the opening and closing direction covering the front upper surface 2a of the case 2 and a lower portion having a longer length in a direction orthogonal to the opening and closing direction covering the case lower surface 2b. The face plate portion 32 and the case front end surface 2
are connected by a connecting plate portion 33 that covers c. Also,
A window 34 is provided which is opened from the lower surface plate 32 of the shutter member 3 to communicate with the connecting plate 33, and can communicate with the magnetic head insertion openings 11 and 12 of the case 2.

The upper plate portion 31 is provided with a linear ridge 35 protruding inward, and the ridge 35 extends along the shutter opening / closing direction.
4 is formed longer than the width. Corresponding to the formation of the ridge 35, a guide groove 27 extending in the shutter opening and closing direction is provided on the upper surface 2a of the case 2, and the ridge 35 slides while engaging. Further, guide claws 37 are formed on both sides of the lower surface plate portion 32 of the shutter member 3 so as to be bent inward, and correspondingly, the guide claws 37 are formed on the lower surface 2b of the case 2. A guide groove 28 is provided in parallel with the front edge.

The shutter member 3 is urged by a torsion spring member 8 and normally maintains a closed state (the state shown in FIG. 1). When the shutter member 3 is in the closed state, the window portion 34 of the shutter member 3 is provided with each magnetic head insertion opening 1.
1 and 12 are provided at positions where they are not exposed. Therefore, the magnetic head insertion openings 11 and 12 are always closed by the shutter member 3 to prevent foreign matter such as dust from entering the case 2 therefrom.

Further, a lock member 4 for locking the shutter member 3 in a closed position is provided at a front end of the case 2. As shown in FIG. 8, the lock member 4 is integrally formed of an elastic member such as plastic, and has a fixed base 41 fixed to the case 2 and a part connected to the fixed base 41 formed in a thin and spring-like shape. An arm portion 42 is provided, and a groove-shaped locking portion 43 is provided at the tip of the arm portion 42. A portion at the tip of the locking portion 43 is formed on a tapered surface 43a.

The arm 42 of the lock member 4
Is attached so as to be exposed in a later-described concave portion 25 opened in the front end face 2 c of the case 2, and a locking portion 43 is provided.
Engages with a claw portion 36 described later provided on the connecting portion 33 of the shutter member 3 in the closed position. A thin rod-shaped auxiliary spring portion 44 is connected to the front end of the arm portion 42.
The auxiliary spring portion 44 has a tip abutting on the projection 44a and urges the arm portion 42 outward when the arm portion 42 is pressed and deformed inward, and has a creep preventing action of the arm portion 42.

As shown in FIG. 9, the concave portion 25 is formed in a concave shape on the bottom side of the front end surface 2c of the case 2, and
An upper wall 26 extends above the recess 25.
The height of the concave portion 25 is higher than the height H _{0 of the} small-capacity magnetic disk cartridge 50 from the reference surface of the lower surface 2b. The upper upper wall portion 26 is provided such that the upper surface 2a of the case 2 is extended so as to be flush with the front end surface 2c at the opening positions of the magnetic head insertion openings 11, 12, and the lock member 4 is provided.
The intermediate portion of the arm portion 42 faces the concave portion 25 and is exposed on the front end face 2c side. Further, a vertical groove 25a communicating with the recess 25 and extending toward the magnetic head insertion opening 12 is opened, and the arm 4 of the lock member 4 is formed in the vertical groove 25a.
The two front end locking portions 43 are arranged to face each other.

On the other hand, the shutter member 3 is provided with a claw portion 36 substantially perpendicular to the opening and closing direction on the connecting plate portion 33 having a small width corresponding to the locking portion 43 of the lock member 4. The claw portion 36 is cut and raised within a range where the vertical groove 25a is formed, and the claw portion 36 is engaged beyond the tapered surface 43a by the shutter member 3 moving in the closing direction by the urging force of the spring member 8. It is provided to automatically engage with the stop 43.

The release of the lock member 4 from the locked state is performed by a shutter opening / closing pin 45 (see FIG. 9) for opening the shutter member 3. The shutter opening / closing pin 45 is installed inside a magnetic disk drive (not shown) that drives the large-capacity type magnetic disk cartridge 1. The shutter member 3 is locked at one end of the shutter member 3 in the closed state at the front end of the disk cartridge 1, and the shutter opening / closing pin 45 moves in the lateral direction in conjunction with the insertion operation of the magnetic disk cartridge 1 to open the shutter member 3. It works. In the initial stage of the opening operation, the shutter opening / closing pin 45 is inserted into the concave portion 25 of the front end face 2c of the case, and comes into contact with the arm portion 42 of the lock member 4 at this portion to press the arm 2 inward. By this operation, the arm portion 42 is elastically deformed, the locking portion 43 is displaced inward, and the engagement with the claw portion 36 is released, and the locked state of the shutter member 3 is released.

The height of the upper end of the shutter opening / closing pin 45 is set lower than the upper end of the recess 25, that is, the lower surface of the upper wall 26.
The height of 5 is a dimension that can be similarly locked to one end of the shutter member on the front end face 2c of the case when the small-capacity magnetic disk cartridge 50 is inserted instead of the large-capacity magnetic disk cartridge 1.

Further, since the shutter opening / closing pin 45 presses the arm portion 42 of the lock member 4 only at the time of shutter opening / closing operation, normally no excessive force is applied to the lock member 4, so-called creep deformation. Is unlikely to occur. Therefore, a plastic member or the like that is inexpensive in cost can be used for the lock member 4.

In the small-capacity magnetic disk cartridge 50 shown in FIG. 7B, magnetic head insertion openings 52a and 52b are formed in a rectangular shape on the upper and lower surfaces of the case 52, and the upper and lower openings 52a and 52b are formed. , The magnetic head 9 is inserted. The magnetic head 9 has a case 52
Opening beyond the front end wall 52c of the
Closed and approached at positions a and 52b.

On the other hand, in the large-capacity magnetic disk cartridge 1 shown in FIG. 7A, the magnetic head insertion openings 11 and 12 are formed so as to communicate from the front end face 2c to the lower face 2b of the case 2 so that the magnetic head can be used. The head 9 can be inserted into the magnetic disk medium 6 with a small opening degree, and the magnetic head 9 can be inserted from the front end face side even with a fixed type that does not open and close.

In the above embodiment, the length of the upper surface plate portion 31 of the shutter member 3 in the direction perpendicular to the opening / closing direction is short, but this is long as shown by the chain line in FIG. In that case, the formation of the ridge 35 may not be necessary.

In FIG. 1 and FIG.
Three identification holes 15 are provided on the upper surface and the lower surface of the left part behind the insertion to identify the recording capacity, and the erroneous erasure prevention display part 16 is provided on the right part.

The large-capacity magnetic disk cartridge 1 as described above is driven by a disk drive (not shown) having a so-called "lower compatibility" function.
In this disk drive device, the height of the cartridge insertion opening is set to a size corresponding to the large thickness of the magnetic disk cartridge 1, and the shutter member 3 is opened and locked simultaneously with the insertion of the magnetic disk cartridge 1. A shutter opening / closing mechanism having the shutter opening / closing pin 45 for releasing the member 4 is provided, and is further held in an inserted state, and the magnetic head 9 is moved closer to the magnetic disk medium 6 from the magnetic head insertion openings 11 and 12, A magnetic spindle 9 magnetically engages with the center core member 5 to rotate and drive the magnetic disk medium 6 at a predetermined number of revolutions, while performing magnetic recording and reproduction by the magnetic head 9. When the small-capacity magnetic disk cartridge 50 is inserted into this disk drive, it is set in the same manner as described above, and its shutter member is
5 is opened similarly, and the magnetic disk medium 6 is opened.
In addition, magnetic recording and reproduction can be performed by the magnetic head 9.

In the large-capacity type disk drive, in order to reliably guide magnetic disk cartridges having a large cartridge insertion opening and different thicknesses to a predetermined set position, an insertion / ejection mechanism corresponding thereto is required. Must be configured. Further, the thickness of the inserted magnetic disk cartridge is detected, and, for example,
The opening angle of the magnetic head 9 may be changed.

When the large-capacity magnetic disk cartridge 1 is to be loaded into a small-capacity type disk drive, the size of the large-capacity magnetic disk cartridge 1 is small due to the small size of the cartridge insertion opening. Insertion is physically impossible and will not be inserted into the drive.

Further, in the magnetic disk cartridge 1 of the above embodiment, the position of the built-in large-capacity magnetic disk medium 6 from the reference surface of the case lower surface 2b is set to be the same as that of the small-capacity magnetic disk cartridge 1. The lower compatibility function of the small-capacity magnetic disk cartridge 50 with respect to the large-capacity magnetic disk drive has been improved. In this case, the magnetic disk medium 6
Are housed in an asymmetric dimensional relationship deviated to the lower surface side with respect to the upper and lower inner walls of the case 2, so that when the magnetic disk medium 6 rotates, the negative pressure on the lower surface side is large due to the Bernoulli effect, and The magnetic disk medium is regulated in the direction of the inner wall, so that the rotating surface is stable, a good head touch effect with the magnetic head 9 can be obtained even during high-speed rotation, and high reliability of the magnetic recording / reproducing performance can be obtained.

Further, by making the height of the reference surface of the magnetic disk medium 6 the same as that of the small-capacity magnetic disk cartridge 50, the structure of the insertion / eject function only in the height direction of the magnetic disk drive can be changed to design the drive. Since many components can be shared between the large-capacity type and the small-capacity type, such as a common shutter opening / closing mechanism, an inexpensive and highly reliable drive device can be obtained.

In the magnetic disk cartridge 1 according to the above-described embodiment, the magnetic head insertion opening is formed on the lower surface and the front end surface 2c of the case 2, but the magnetic head insertion opening is formed on the upper and lower surfaces of the case 2. And may be provided so as to open to the front end face 2c. The shape and the shutter member 3 of the lock member 4 are described.
The design of the locking structure can be changed as appropriate.

[Brief description of the drawings]

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

FIG. 2 is a front end view of the magnetic disk cartridge with a shutter member opened.

FIG. 3 is a bottom view of the magnetic disk cartridge with a shutter member opened.

FIG. 4 is a central longitudinal sectional view of the magnetic disk cartridge with a shutter member removed.

FIG. 5 is a perspective view of a shutter member.

FIG. 6 is a perspective view showing a state where the shutter member is turned upside down;

FIG. 7 is a cross-sectional side view of a main part showing a form of a magnetic head insertion portion in comparison with a small capacity type magnetic disk cartridge.

FIG. 8 is a bottom view of a main part of the magnetic disk cartridge, showing a lock member installation part in a cross section of a shutter member.

FIG. 9 is a perspective view of a main part showing the installation portion of a lock member of the magnetic disk cartridge and a shutter opening / closing pin.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Large-capacity magnetic disk cartridge 50 Small-capacity magnetic disk cartridge 2 Case 2a Upper surface 2b Lower surface 2c Front end surface 3 Shutter member 4 Lock member 6 Magnetic disk medium 9 Magnetic head 11,12 Magnetic head insertion opening 25 Recess 26 Upper wall 31 Upper Face plate 32 Lower plate 33 Connecting plate 34 Window 36 Claw 41 Fixed base 42 Arm 43 Locking part 45 Shutter release pin

Claims (2)

[Claims] 1. A disk-shaped large-capacity magnetic disk medium is rotatably accommodated in a case, a magnetic head insertion opening, a shutter member for opening and closing the opening, and a shutter member in a closing direction. In the magnetic disk cartridge provided with a biasing spring member, the planar shape of the case is common to the small-capacity magnetic disk cartridge, and the thickness of the case is smaller than that of the small-capacity magnetic disk cartridge. About 1.3 ~
The shutter member has a thickness of 2.0 times, and the planar position and the opening / closing direction of the shutter member are common to the small-capacity magnetic disk cartridge. While a lock member for locking the member in the closed position is provided, a shutter opening / closing pin provided in the magnetic disk drive device that is engaged with one end of the shutter member in the closed position is provided on the front end surface of the case. A magnetic disk characterized by being provided with a concave portion to be initially inserted, a part of the lock member being exposed in the concave portion, and the shutter opening / closing pin abutting on the lock member to release the locked state. cartridge. 2. The lock member comprises an elastic member,
2. The magnetic disk cartridge according to claim 1, wherein the leading end locking portion is deformed in conjunction with the closing movement of the shutter member and is locked on a part of the shutter member.