JPH08235808A - Disk jacket - Google Patents

Abstract

PURPOSE: To obtain a good recording and reproducing state and a long life of a disk by adopting the constitution that the disk comes into contact with the outside only from the two holes; a disk center hole and a head insertion hole and that these holes are completely closed by a shutter. CONSTITUTION: This disk jacket is so formed that the disk comes into contact with the outside only from the two holes; the disk center hole 8 and the head insertion hole 10 and that these holes are completely closed by the shutter 18. The infiltration of worn particle of the inside surface of a jacket casing 7 or the slider 21 itself into a disk housing part is prevented by a circular rib 11 in case such worn particle is generated by the repetitive operation of the opening and closing of the shutter on the inner side of the jacket casing 7. As a result, the disk 1 which is less adhered with dust, etc., at all times is obtd. Consequently, the good recording and reproducing state is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk jacket used for an information recording / reproducing apparatus for recording / reproducing, for example, video information and document information on a disk-shaped magnetic sheet or an optical disk. The present invention relates to a disc jacket in which when a jacket is inserted into a jacket holder of an information recording / reproducing apparatus, a shutter is automatically moved to open a head insertion hole and a center hole of the disc jacket.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk for recording video information, document information, etc., or a disk jacket having an optical disk rotatably housed therein has been proposed for convenience of handling and storage. In this type of disc jacket, there is a so-called open disc jacket in which the window for the head is always open. However, since the window is always open, dust and the like come from this window. The window part can be opened and closed because it may invade the inside and adhere to the internal disk, or may accidentally attach a fingerprint or the like to the disk during handling and adversely affect recording and reproduction. Recently, a so-called automatic shutter-equipped disk jacket has been proposed in which a window is opened for the first time when a disk jacket is inserted into a jacket holder of an information recording / reproducing apparatus (hereinafter referred to as an apparatus) with a shutter disposed. It's been done.

However, even in the latter case, although the window for inserting the head is normally closed by a shutter or the like, a part of the slider that allows the shutter to move is exposed on the side of the jacket housing. Since the opening is formed, it is unavoidable that dust and the like enter the inside of the jacket housing from the gap formed between the slider and the opening and adhere to the disk.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks, prevents dust and the like from entering from the outside during handling or storage, and prevents dust and the like from adhering to the disk. The purpose is to always provide a good recording / reproducing state.

[0005]

According to the present invention, there is provided a disk jacket, comprising: a jacket housing for rotatably storing a disk and having a head insertion hole and a center hole formed therein;
A shutter movably attached to the jacket housing, a slider that moves the shutter to open and close the head insertion hole and a center hole, and the slider engages with the slider to attach the shutter to the head insertion hole. And an elastic member that elastically urges in the direction of closing the center hole, and inside the jacket housing, forms a concentric circle with the center hole and surrounds the entire outer peripheral portion of the disk. A circular rib for restricting movement in the radial direction is provided, the slider and the elastic member are arranged outside the circular rib, and the shutter is driven outside the circular rib. It is a feature.

According to the present invention, the disk center hole and the head insertion hole are contacted to the outside only through the minimum required two holes, and the center hole and the head insertion hole are completely closed by a shutter. The dust and the like will not enter from the outside of the jacket housing and adhere to the disc. In addition, even if abrasion powder of the inner surface of the jacket housing or the slider itself is generated due to the repetitive operation of opening and closing the shutter inside the jacket housing, the circular rib prevents entry into the disk storage unit. Abrasion powder does not adhere to the disk, and it is possible to always provide a disk with little dust and the like,
Not only can good recording and playback conditions be obtained,
This has the effect of prolonging the life of the disc.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS.

First, the structure of the disc jacket will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a disk having a recording area 4 and non-recording areas 5 and 5 '. Is formed with an engagement hole 3 for rotational support. 4a
Indicates a recording range inside the recording area 4, and
b indicates the outer recording range. 2 is disk 1
It is the outer peripheral portion of.

On the other hand, as shown in FIG. 1, the jacket casing 7 for accommodating the disc 1 is an upper half 7 made of an injection molded product such as ABS resin containing an antistatic agent.
a and a lower half 7b, and outer peripheral portions of the upper half 7a and the lower half 7b and a rib portion described later are welded to each other to form a substantially rectangular parallelepiped shape as shown in FIG. To be done. The upper half 7a and the lower half b each have a circular center hole 8 substantially at the center, and the center hole 8 is concentric with the center hole 8 and the disk 1 is rotatable inside the jacket housing 7. A circular rib 11 surrounding the outer peripheral portion 2 of the disk 1 and a head insertion hole 10 for inserting a head to be described later are provided, and a first ring-shaped projection 9 is provided at a peripheral portion of the center hole 8. On the inner peripheral edge of the circular rib 11, second ring-shaped projections 12 are integrally formed on the inner surfaces of the upper half 7a and the lower half 7b, respectively. Reference numeral 13 denotes a concave portion formed by the first ring-shaped projection 9 and the second ring-shaped projection 12, and is provided opposite to the recording area 4 of the disk 1 described above. The recording area 4 is not directly in contact with the inner surface of the jacket housing 7. That is, the disk 1 is mounted on the first ring-shaped protrusion 9 and the second ring-shaped protrusion 12 and is rotatably stored in the jacket housing 7. 1 non-recording area 5
Protects the recording area 4 of the disc 1 by contacting the first ring-shaped protrusion 9 and the non-recording area 5'of the disk 1 with the second ring-shaped projection 12, respectively. Even if the disc 1 is biased and a part of the outer peripheral portion 2 of the disc 1 is held in contact with the inner peripheral surface 11a of the circular rib 11, the recording area 4 has the first ring-shaped protrusion. 9
And the first ring-shaped protrusion 12 so as not to come into contact with the first ring-shaped protrusion 12.
The outer peripheral portion 9a of the ring-shaped protrusion 9 and the inner peripheral portion 12a of the second ring-shaped protrusion 12 are formed. That is, the relationship between the first ring-shaped protrusion 9, the second ring-shaped protrusion 12, and the circular rib 11 provided on the disk 1, the upper half 7a and the lower half 7b, respectively, is as follows. .

The outer peripheral portion 9a of the first ring-shaped projection 9 <the recording range 4a inside the disk 1 The recording range 4b outside the disk 1 <the inner peripheral portion 12a of the second ring-shaped projection 12 <the disk 1 Outer peripheral portion 2 Outer peripheral portion 2 of disk 1 <Inner peripheral surface 11a of circular rib 11 When the cassette housing 7 is assembled by stacking the upper half 7a and the lower half 7b on top of each other, the upper half 7a
The circular rib 11 of the lower half 7b and the circular rib 11 of the lower half 7b contact each other to form the same circumferential surface, completely surrounding the disk 1, and the center hole 8 and the head insertion hole 10 are not opened. As far as possible, dust and the like from the outside are prevented from entering.

Reference numeral 14 denotes an upper half 7a and a lower half 7 where the center hole 8 and the head insertion hole 10 are formed.
In FIG. 1, there are recesses provided on the outer surface of the housing b, and linear guide grooves 15 extending along side edges of the jacket housing 7 are formed. The guide groove 15
May be provided on either the upper half 7a or the lower half 7b. A protruding piece 16 is provided on the end 14a of the concave portion 14, and is integrally formed so that the cross section with the concave portion 14 becomes a U-shape. On the other hand, linear ribs 17 are formed on the inner surfaces of the upper half 7a and the lower half 7b, respectively, at the end 14b of the recess 14, and as shown in FIG. 2 when the upper half 7a and the lower half 7b are assembled. An opening 47 is formed in the.

Reference numeral 18 denotes a shutter having a U-shaped cross section that opens and closes the center hole 8 and the head insertion hole 10 and is made of, for example, stainless steel or synthetic resin. As shown in FIG. 2, the shutter 18 is slidably mounted in a predetermined direction in the recess 14 provided in the upper half 7a and the lower half 7b. That is, as shown in FIG. 1, at least two semi-circular projections 19 are formed on the shutter 18 in correspondence with the guide grooves 15 provided in the recesses 14 of the upper half 7a by pressing or integral molding. Has been formed and this protrusion 19
When is inserted into the guide groove 15, the shutter 18 is guided by the guide groove 15 and is slidable in the directions of arrows A and B as shown in FIG.
The protrusion 19 may be formed in a V shape or a U shape. On the other hand, a slider 21 is disposed inside the shutter 18 as shown by a dashed line in FIG. 1, and protrusions 24 a and 24 formed on the slider 21 are provided.
b and bent pieces 20a and 20b provided at both ends of the side portion 18c of the shutter 18 are configured to be integrally movable. That is,
When the bent pieces 20a and 20b of the shutter 18 are inserted between the protrusions 24a and 24b of the slider 21,
When the slider 21 moves, the shutter 18 also moves in the same manner because it is sandwiched by the protrusions 24a and 24b. 4 and 5 provided on the upper half 7a and the lower half 7b, respectively.
As shown in FIG. 2, the guide groove 26 is fitted and guided in a substantially right-angled guide groove 26 having a corner formed in an arc shape, and as shown in FIG.
And is slidable in the D direction. In addition, in FIG. 1, the longitudinal end of the slider 21 is bent in an arc shape, but it is shown that the slider 21 is fitted in the guide groove 26. The slider 21 is made of, for example, a leaf spring or an elastic member such as vinyl chloride so as to be normally linear when removed from the slider 26. Therefore, the slider 21
Is slidable even if a part of the guide groove 26 is formed in an arc shape, and as shown in FIG.
If the projection 23 is formed at the front end of the housing and inserted into the opening 45 formed along the side plate of the jacket housing 7 by the upper half 7a and the lower half 7b, the projection 23 As shown in FIGS. 2 and 3, the shutter 18 is moved from the inside of the opening 45 to the outside. The shutter 18 can be moved in the direction of arrow A by engaging with a projection provided on a jacket holder described later. it can.
However, the protrusion 22 of the slider 21 has one end 2 of an elastic member 25 made of a stretchable spring or the like.
5a is locked, and a pin 27 integrally formed on the inner surface of the lower half 7b is connected to the other end 2 of the elastic member 25.
Since the slider 5b is locked, the slider 21 is constantly pulled in the direction of arrow B by the urging force of the elastic member 25. Accordingly, the shutter 18 is also simultaneously elastically urged in the direction of arrow B, so that the center hole 8 and the head insertion hole 10 are always completely closed by the shutter 18 as shown in FIG. Intrusion of dust and the like from is prevented. Note that the side portion of the shutter 18 is locked to the side portion 14c of the concave portion 14, and is stopped at the position shown in FIG. 2 so that movement in the direction of arrow B in FIG. Has become. On the other hand, the end 18a of the shutter 18 is slidably inserted inside the protruding pieces 16 provided on the upper half 7a and the lower half 7b as shown in FIGS. 2 and 3, respectively. Even if a force is applied to push out the jacket housing 7 in any way, the end 18 a of the shutter 18 is configured to abut on the protruding piece 16. The configuration is such that the shutter 18 is prevented from spreading, and the center hole 8 and the head insertion hole 10 can be freely opened and closed in a good state at all times.
Further, the shutter 18 is provided on the outer side of the jacket housing 7 so that the bent pieces 20a and 20b of the shutter 18 are sandwiched between the protrusions 24a and 24b of the slider 21 exposed from the opening 47 of the jacket housing 7. Therefore, it can be easily attached to the jacket housing simply by inserting it into the concave portion 14 of the jacket housing 7.

Reference numeral 46 denotes an opening provided opposite to the opening 45 and symmetrical to the opening 45, and is necessary when the disk 1 is of a so-called double-sided disk type capable of being used on both sides. On the other hand, in the case of a so-called single-sided disc in which only one side of the disc 1 can be used, the opening 46 is unnecessary, but if so, at least two types of jacket housings are required depending on the type of disc (single-sided disc or double-sided disc). Therefore, it is impossible to share the two jacket casings, and the jacket casing becomes expensive in terms of productivity and cost. Therefore, in the jacket housing of the present invention, as shown in FIG.
As shown in FIG.
5 and 46 are formed so that two types of disks, a single-sided disk and a double-sided disk, can be used in one type of jacket housing.

The holes 40 to 43 and the long holes 44 are provided asymmetrically in the upper half 7a and the lower half 7b, and the holes 40 to 43 are used especially for discriminating the type of the disc 1. Is done. The hole 42 is provided for discriminating between the single-sided disk and the double-sided disk described above. For example, when the hole 42 is left as it is, the hole 42 is formed as a single-sided disk. If 42 is closed, a double-sided disk is set, and it can be determined by operating a microswitch or the like. 40 and 41 are constructed in the same manner as above.
These three holes are used to newly discriminate three types of disks, namely, a recording-only disk, a reproduction-only disk, and an erasable disk. For example, a case where the hole 40 is closed and the hole 41 is left as it is is a recording-only disk, and a case where the hole 40 is closed and the hole 41 is closed is a reproduction-only disk, and a case where the holes 40 and 41 are closed respectively. An erasable disk may be used. Four
The hole No. 3 is a hole for preventing erroneous erasure, and the means for discrimination is the same as the above-mentioned method. However, the inside of the hole 43 (the inside of the upper half 7a and the lower half 7b) is shown in FIG. As shown in FIG. 7, a concave portion 33 having V-shaped grooves 34a and 34b.
Are integrally molded, and the hole 43 is formed in the recess 33.
The erroneous erasure prevention claw 35 that allows the user to freely open and close is inserted slidably. The erroneous erasure prevention claw 35 is provided with the grooves 34a, 3a.
4b, an arm 36 having a V-shaped protrusion 36a for positioning the erroneous erasure prevention claw 35 in the recess 33 is formed of, for example, an elastic synthetic resin. It is integrally molded. Further, as shown in FIG.
A hole 37 into which a pen tip such as a ball-point pen can be inserted is provided at a position facing the above, and the hole 37 is configured to be exposed to the outside through the long hole 44. The erroneous erasure prevention claw 35 is normally positioned in the recess 33 by the engagement of the protrusion 36 a with the groove 34 a, and closes the hole 43. At this time, the state is set to, for example, a recordable state, and if the information is recorded on the disc and the information is not stored or erased, the erroneous erasure prevention claw 35 is moved to move the hole. It may be configured to open 43. In order to move the erroneous erasure prevention claw 35, a pen point such as a ball-point pen is inserted from the long hole 44 of the upper half 7a and the lower half 7b, and the erroneous erasure prevention disposed opposite the long hole 44 is performed. By fitting into the hole 37 of the claw 35 and pulling in the direction of the arrow E, the groove 34a and the protrusion 3
6a is disengaged, and the erroneous erasure prevention claw 35 is slid in the direction of the arrow E to open the hole 43. At this time, the protrusion 36a of the erroneous erasure prevention claw 35 is configured to engage with the groove 34b, and the erroneous erasure prevention claw 35 has a hole 43.
Positioned with the open. In this way, the erroneous erasure prevention claw 35 is moved, and when the stored information becomes old or unnecessary and needs to be replaced with new information, the reverse operation is performed to perform the erroneous erasure. The prevention claw 35 may be moved in the arrow F direction to close the hole 43 again. The width of the long hole 44 may be such that the tip of a pen such as a ballpoint pen can be freely inserted, as described above. Therefore, for example, about 2 mm is sufficient. For example, the erroneous erasure prevention claw 35 cannot be moved. Therefore, since the erroneous erasure prevention claw 35 is not moved by mistake during handling or storage, information to be saved is not erased or information to be recorded is not recorded. Reference numeral 28 is an opening provided to face the upper half 7a and the lower half 7b respectively for the side discrimination of the double-sided disk. As shown, if the jacket casing 7 is inserted, the micro switch is inserted into the opening 28 and does not operate. But,
When the jacket housing 7 is inserted in a state of being turned upside down in FIG. 2, the microswitch is actuated by contacting the outer side of the jacket housing 7. At this time, if the former is the A side of the double-sided disc and the latter is the B side, the side of the disc can be discriminated. Reference numerals 31 and 32 denote positioning holes of the jacket housing 7 provided asymmetrically on the upper half 7a and the lower half 7b, respectively. The positioning holes 31 are substantially positive as reference holes when the jacket housing 7 is positioned. The holes and the 32 positioning holes are respectively formed as substantially auxiliary holes as auxiliary holes. Numeral 48 denotes a concave portion provided outside the upper half 7a and the lower half 7b.
Labels that display the contents such as the recorded information are attached. Next, the operation of the disc jacket will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 2 shows the jacket housing 7 before being inserted into the apparatus, and the center hole 8 and the head insertion hole 10 are completely closed by a shutter 18 so that dust and the like do not enter the jacket housing 7 from the outside. . Grasping the label side of the jacket casing 7 with the shutter 18 side in front as shown by the alternate long and short dash line in FIG. As it is inserted in the direction, the jacket housing 7 is inserted into the jacket insertion hole 51 and the side walls 52a and 52b of the jacket holder 52, and the device 4 is inserted.
9 are inserted inside. The side walls 52a, 52b
Are formed with projection pieces 53a and 53b, respectively.
The shutter 18 is engaged with the projection 23 of the slider 21 exposed from the opening 45 of the jacket housing 7.
Is configured to be moved semi-automatically. Also,
Although not described in detail, the jacket holder 52 is configured so as not to move in the insertion direction of the jacket housing 7 but only in the vertical direction (directions of arrows H and I in FIG. 6). When the housing 7 is further inserted in the direction of the arrow G, the protrusion pieces 53a and 53b are inserted into the openings 45 and 46, respectively. After that, when the protrusion 23 comes into contact with the protrusion 53a, the protrusion 23a stops the protrusion 23 from being inserted into the apparatus 49, so that the jacket housing 7 is further inserted in the direction of the arrow G. Then, the slider 21 is slid in the direction of arrow C in FIG. 2, and the shutter 1
8 also starts sliding in the direction of arrow A. When the shutter 18 starts sliding in the direction of arrow A, the center hole 8
8, the head insertion hole 10 is opened next, and finally the center hole 8 and the head insertion hole 10 are completely opened as shown in FIG. At this time, for the first time, a head 54 for recording information on the disk 1 shown in FIG. 6 or reproducing the recorded information,
A disk motor 57 for rotating the disk 1 and a disk motor 57 (not shown)
The clamper or the like held above can be inserted. When the jacket housing 7 is inserted into the jacket holder 52 as shown in FIG. 5 and the center hole 8 and the head insertion hole 10 are completely opened, the jacket housing 7 is opened.
Is inserted into the jacket holder 52, as shown in FIG.
Is lowered in the direction of arrow H. Reference numeral 60 denotes a base provided inside the device 49. On the base 60, a positioning post for positioning the disk motor 57 and the head 54 or the jacket housing 7 at a predetermined position of the device 49 is provided. Microswitches 61 to 63 and the like provided for discriminating the type of the disc 1 are arranged at predetermined positions. The head 54 is integrally mounted on a head substrate 55 and is configured to be movable in the arrow J direction. 56 is the head substrate 5
5 is a guide shaft for guiding the head 54 in the direction of the arrow J by fitting with the head 5. As shown in FIG. 6, the positioning post 61 has a tip 62 formed in a conical shape so that the positioning holes 31 and 32 of the jacket housing 7 can be easily inserted. On the other hand, the positioning post 63 has a flat tip, and contacts the outside of the jacket housing 7 so that the jacket housing 7 positioned by the positioning post 61 does not further descend from the predetermined position in the arrow H direction. It is configured to block. Therefore, when the jacket housing 7 is lowered and the jacket housing 7 is set inside the device 49 by the positioning posts 61 and 63, the disk 1 is inserted into the center hole 8 of the lower half 7b. Although not shown, it is held by a clamper (not shown) inserted through the center hole 8 of the upper half 7a, and is rotatable in the jacket housing 7. The microswitches 70 to 74 are also of the type of the disk 1. The switch which operates and the switch which does not operate appear, but these are detected at the same time and the disc 1 is determined. Here, the microswitches 70 and 71 are provided to face the holes 40 and 41 of the lower half 7b. For example, if the hole 40 is closed by a jig or the like and the hole 41 is left as it is, One end 75 of a pin 75 provided on the microswitch 70
a is pushed in the direction of arrow K because the hole 40 is closed, the microswitch 70 is connected to the other end 7 of the pin 75.
The switch is turned on by being operated by 5b. On the other hand, in the micro switch 71, the one end 75 a of the pin 75 is inserted into the hole 41, so that the micro switch 71
Does not operate and the switch is in the OFF state, so that the disc 1 is determined to be a recording-only disc. The microswitch 72 is used to discriminate a single-sided disk or a double-sided disk provided opposite the hole 42 of the lower half 7b. The microswitch 73 has an opening 2 in the lower half 7b.
8, which is provided for facing the side and is configured to be directly operated by the jacket casing 7. In FIG. 6, the micro switch 73 has an opening 28.
The switch does not work because it is inserted into the switch
In this state, the disc 1 is determined to be the A side. Next, the microswitch 74 is provided for preventing erroneous erasure provided opposite to the hole 43 of the lower half 7b, and the switch is determined by whether the hole 43 is closed or opened by the erroneous prevention claw 35. ON / OFF is determined. Thereafter, when the disk 1 is rotated by the disk motor 57, the head 54 inserted into the head insertion hole 10 of the lower half 7b is moved in the direction of the arrow J, and information is recorded or reproduced. When the user presses the eject switch to take out the jacket housing 7 from the inside of the device 49, if a part of the jacket housing 7 is configured to protrude outside the front panel 50, the jacket housing 7 is manually operated thereafter. What is necessary is just to grasp the body 7 and pull it out. When the jacket housing 7 is pulled in the direction of the arrow L as shown in FIG.
Starts moving in the direction of arrow D shown in FIG. At the same time, the shutter 18 also starts to move in the direction of arrow B,
When the jacket housing 7 is pulled out to a position where the engagement with the projection piece 53a is released, the shutter 18 is automatically moved to completely close the center hole 8 and the head insertion hole 10 as shown in FIG. Will close. Thereafter, the jacket housing 7 is completely removed from the device 49. Incidentally, even if the jacket housing 7 is erroneously inserted into the device 49 from the opposite side, the end of the jacket housing 7 will be
a, 53b, so that it cannot be inserted any further.

[0015]

As is apparent from the above description, according to the present invention, a circular rib surrounding a disk is provided, and a slider or an elastic member for moving a shutter is arranged outside the circular rib. Therefore, the disc center hole and the head insertion hole are configured so as to be in contact with the outside only through the minimum two required holes, and the center hole and the head insertion hole are completely closed by a shutter. Therefore, even when handling the jacket or storing the jacket, dust and the like do not enter from the outside of the jacket housing and adhere to the disk. In addition, even if abrasion powder of the inner surface of the jacket housing or the slider itself is generated due to the repetitive operation of opening and closing the shutter inside the jacket housing, the circular rib prevents entry into the disk storage unit. No wear powder adheres to the surface. Therefore,
It is possible to always provide a disk with little adhesion of dust and the like, and not only to obtain a good recording / reproducing state, but also to prolong the life of the disk.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing the configuration of a disk jacket according to the present invention.

FIG. 2 is a perspective view showing a state where a shutter of the jacket is closed.

FIG. 3 is a perspective view showing a state in which the shutter is open.

FIG. 4 is a plan view of the jacket.

FIG. 5 is a partial cross-sectional plan view showing a state where the jacket is inserted into the apparatus.

FIG. 6 is a perspective view showing a state where the jacket is positioned in the apparatus.

FIG. 7 is a perspective view showing the configuration of an erroneous erasure prevention claw of the jacket.

[Explanation of symbols]

 1 Disc 7 Jacket Housing 8 Center Hole 10 Head Insertion Hole 11 Circular Rib 16 Projecting Piece 18 Shutter 21 Slider 25 Elastic Member 31 Positioning Hole 32 Positioning Hole 40 Disc Type Discrimination Hole 41 Disc Type Discrimination Hole 42 Disc Type discrimination hole 43 Erase prevention hole 45 Opening 46 Opening

Claims (4)

[Claims] 1. A jacket housing in which a disk is rotatably housed and a head insertion hole and a disk rotation center hole are formed, and a U-shaped shutter movably attached to the jacket housing. And a slider that moves the shutter to open and close the head insertion hole and the center hole, and forms a concentric circle with the center hole inside the jacket housing, and the entire outer peripheral portion of the disk. A circular rib having a diameter slightly larger than the diameter of the disc is provided so as to enclose the circumference and regulate the radial movement of the disc, the slider is arranged on the circular rib, and the shutter is attached to the jacket. A disc jacket, which is arranged outside the housing. 2. The disc jacket according to claim 1, further comprising a first ring-shaped protrusion at a position facing the inner peripheral non-recording area of the disc at the peripheral edge of the center hole. 3. The disc jacket according to claim 2, further comprising a second ring-shaped protrusion at a position facing an outer peripheral non-recording area of the disc at an inner peripheral edge of the circular rib. 4. The jacket casing is made up of upper half and lower half members having the substantially symmetrical circular rib structure,
The slider is disposed outside the circular rib, the shutter is disposed outside the jacket housing, the shutter and the slider are driven outside the circular rib, and 3. The circular ribs of the halves contact, and the first and second ring-shaped protrusions have a space between the upper and lower halves to rotatably mount the disc. Disc jacket described in 3.