Magnetic tape cartridge

A magnetic tape cartridge is provided, in which the mating of the lower half and the upper half can be easily performed and which is applicable to automated assembly, when the magnetic tape cartridge having a sliding door is assembled. The rib projects from the upper section of the first guide wall in the direction of the opposite second guide wall. On the other hand, the groove, which faces the rib, is carved on the inner side surface of the sliding door. The rib engages with the groove, thereby restricting the vertical displacement of the sliding door. Also, the engagement of the rib and the groove guides the sliding door in the guide channel freely.

FIELD OF THE INVENTION

The present invention relates to a magnetic tape cartridge, which has a sliding door for opening or closing the opening in order to extract a magnetic tape, and to a method for assembling the magnetic tape cartridge. It particularly relates to a magnetic tape cartridge, in which the lower half section and the upper half section can be mated easily in the assembly of the magnetic tape cartridge.

BACKGROUND OF THE INVENTION

Generally speaking, in magnetic tape cartridges used as external storage medium for data backup of computers and the likes, a single reel wound with a magnetic tape is housed in a flat square-like cartridge case, which is composed of the lower half section and the upper half section. When a magnetic tape cartridge is used, the tape loading mechanism of a record playback unit extracts the magnetic tape from the cartridge case and winds it around the reel placed in the record playback unit, thereby running the magnetic tape. It explains why an opening, which is for extracting the leading end of tape, is provided on the side of the cartridge case that houses a single reel of this type. This opening is normally closed to protect against the dust, and opened by the tape loading mechanism of a record playback unit only when either recording or playback is performed by the record playback unit.

Of the magnetic tape cartridges mentioned above, the magnetic tape cartridge represented by LTO (Linear Tape Open) standard is so arranged that the sliding door, which slides along inside the side wall of the cartridge case, opens or closes the opening. The sliding door is capable of sliding smoothly fitted in the guide channels, which are provided on both inner surfaces of the upper half section and the lower half section of the cartridge along their side walls. And a spring member imposes the force on the sliding door in the closing direction to close the opening except for the occasion when the magnetic tape cartridge is in use.

The assembly of the magnetic tape cartridge with a sliding door is performed in the following manner. The respective parts such as a reel and a claw for the protection of inadvertent erasing are set on the prescribed position of the lower half section, the spring member and the sliding door are inserted into the guide channel of the lower half section, and then the lower half section and the upper half section are mated. When the spring member is inserted into the guide channel, it is mounted compressed on the sliding door so as to impose the force on the sliding door in the closing direction.

However, before the lower half section and the upper half section are mated, the sliding door102is liable to lift from the guide channel103of the lower half section105by the force of the spring member101as shown inFIG. 29, since the spring member and the sliding door, which are inserted in the guide channel, are not restricted upward. Therefore, when the lower half section105and the upper half section are mated without any measures, there has been a problem that the sliding door102is not able to be inserted properly into the guide channel103of the lower half section or another guide channel of the upper half section (not shown).

Also before the lower half section and the upper half section are mated, the sliding door102inserted in the guide channel103is liable to fall in the opposite of the side wall104, namely inside the cartridge case as shown with the arrow inFIG. 30, since the guide channel103of the lower half section105is carved shallow as shown in the figure. Therefore, there has been a problem, the same as described above, that the sliding door102is not able to be properly inserted into the guide channel103of the lower half section105or another guide channel of the upper half section (not shown).

SUMMARY OF THE INVENTION

The object of the present invention to address the above issues is to provide a magnetic tape cartridge, in which the mating of the lower half section and the upper half section can be easily performed and is applicable to automated assembly, when the magnetic tape cartridge having a sliding door is assembled.

The first aspect of the present invention to address the above issues is to provide a magnetic tape cartridge, comprising: an opening, which is positioned on a side of a cartridge case lying across a lower half section and an upper half section of the cartridge case, for extracting a magnetic tape; and a sliding door for opening or closing the opening, which is inserted in a closed position with force imposed by a spring member into lower and upper guides, which are placed in the lower half section and the upper half section of the cartridge case respectively, wherein the sliding door and the lower guide of the lower half section are equipped with an engagement device, which is capable of restricting the vertical displacement of the sliding door and guiding the sliding door in its moving direction freely.

As the magnetic tape cartridge is arranged so that the vertical displacement of the sliding door is restricted by the engagement device, which is provided in the lower guide of the lower half section. This way the engagement device prevents the sliding door inserted in the lower guide from lifting, when the magnetic tape cartridge is assembled. It follows that the sliding door can be inserted properly into the lower guide of the lower half section, when the magnetic tape cartridge is assembled. Therefore, when the lower half section and the upper half section are mated, the mistakes associated with mating can be prevented, since the mating of the lower half section and the upper half section is improved by inserting the sliding door into the lower and upper guide channels of the lower half section and the upper half section properly. The guide according to the appended claims includes all that guides the slide movement of the sliding door, not only the lower and upper guide channels carved on the lower half section and the upper half section but also the discontinuous projections and ribs provided for the half section, the side wall and the base of the half section.

The second aspect of the present invention provides a magnetic tape cartridge, comprising: an opening, which is positioned on a side of a cartridge case lying across a lower half section and an upper half section of the cartridge case, for extracting a magnetic tape; and a sliding door for opening or closing the opening, which is inserted in a closed position with force imposed by a spring member into lower and upper guides, which are placed in the lower half section and the upper half section of the cartridge case respectively, wherein a restriction device, which restrains the sliding door from falling in the direction normal to the plane of the sliding door, is provided along the lower guide of the lower half section.

Thus, when the magnetic tape cartridge is assembled, the sliding door can be mounted properly to the lower guide of the lower half section, since the sliding door inserted in the lower guide of the lower half section can be prevented from falling in the direction normal to its plane in contact with the restriction device provided along the lower guide. Therefore, if the lower half section and the upper half section are mated, the mistakes of mating can be prevented, since the sliding door can be inserted into the lower and upper guide channels of the lower half section and the upper half section properly to result in an easy mating. The guide referred to here includes all that guides the slide movement of the sliding door, not only the lower and upper guide channels carved on the lower half section and the upper half section but also the discontinuous projections and ribs provided on the half section, the side wall and the base of the half section.

The third aspect of the present invention provides a method for assembling a magnetic tape cartridge, which comprises an opening, which is positioned on a side of a cartridge case lying across a lower half section and an upper half section of the cartridge case, for extracting a magnetic tape, and a sliding door for opening or closing the opening, which is inserted in a closed position with force imposed by a spring member into lower and upper guides placed in the lower half section and the upper half section of the cartridge case respectively, the method comprises the steps of: inserting the sliding door into the lower guide of the lower half section while the spring member is compressed; and mating the upper half section with the lower half section while the spring member or the sliding door is pressed toward a base of the lower half section.

The spring member and the sliding door are prevented from lifting and falling when they are pressed toward the base of the lower half section by a pressing means such as a finger or a small stick. So the upper half section can be easily mated with the lower half section while the sliding door is guided by the lower guide of the lower half section. If the possible lowest part of the spring member or the sliding door, which stands on the lower half section, is held and pressed, the upper half section can be mated with the lower half section more securely, since the sliding door can be held until it is guided by the upper guide of the upper half section sufficiently.

As the guides, the examples such as a line channel on the inner base surfaces of the lower half section and the upper half section, or on the contrary projections on the inner surfaces of the lower half section and the upper half section along the sliding door are presented, which restrict the movement of the sliding door. Any types of springs such as a compression coil spring, extension coil spring, torsion coil spring, laminated spring, torsion bar, spiral spring, coned disk spring and leaf spring may be employed. Their materials are not limited to metals but resins may be used instead.

In the assembly method described above, it would be preferable to press the spring member or the sliding door to the side wall of the lower half section in parallel with pressing them toward the base of the lower half section, when the upper half section is mated with the lower half section.

Assembling like this allows the mating of the upper half section with the lower half section of the magnetic tape cartridge while keeping the spring member and the sliding door standing vertically beside the side wall of the lower half section, rendering its assembly easier and resulting in the prevention of mistakes related to the mating of the upper half section and the lower half section.

Especially when the spring member is set inside the sliding door, it will be possible to assemble the magnetic tape cartridge more reliably if the spring member is pressed to the side wall of the lower half section, since the inner part (the spring member) can also press the outer part (the sliding door) to the side wall of the lower half section.

The fourth aspect of the present invention provides a method for assembling a magnetic tape cartridge case, which includes the lower half section and the upper half section, the opening lying across the lower half section and the upper half section for extracting the leading end of the magnetic tape, the sliding door for opening or closing the opening beside the inside of the side wall of the case, and the spring member imposing the force on the sliding door in the closing direction. The sliding door is mounted to the lower and upper guides on the lower half section and the upper half section while the spring member imposes the force on the sliding door. The mounting of the sliding door of the magnetic tape cartridge is performed as follows.

The sliding door is inserted into the lower guide of the lower half section with the spring member imposing the force on the sliding door. Since the sliding door is liable to fall in the direction normal to its plane without any assistance, the end of the sliding door is supported by a supporting arm with the groove of V-shape. The lower half section and the upper half section are mated while supported by the supporting arm and then the supporting arm is removed for the subsequent steps.

The sliding door is thus supported by the supporting arm, inserted in the V-shape groove. The sliding door is pressed to the slopes of the V by the spring member, thereby interposed between the slopes of the V and standing against the groove of the supporting arm. Therefore, the sliding door is prevented from falling and the mating of the lower half section and the upper half section can be performed accurately and easily. Other parts not in contact with the sliding door are not necessarily of V-shape, for the object of the V-shape groove is to interpose the end of the sliding door with the two slopes and guide it to stand stably. For example, the root of V-shape groove may be rounded with fillet and the vicinity of the opening of the V may be permitted to be of a different shape.

As the guide of the sliding door described above, the examples such as a line-channel on the inner surfaces of the lower half section and the upper half section, or on the contrary projections on the inner surfaces of the lower half section and the upper half section along the sliding door can be presented, which guide the movement of the sliding door. Any types of springs such as a compression coil spring, extension coil spring, torsion coil spring, spiral spring, and leaf spring may be employed. Their materials are not limited to metals but resins may be used instead.

In the assembly method described above, it would be preferable to provide the chamfering on the end of the sliding door, which fits to the slopes of the groove mentioned above, and perform the assembly in the following manner. The sliding door is mounted on the lower half section while the spring member imposes the force on the sliding door, the lower half section and the upper half section are mated by supporting the chamfered portion with the groove and then the assembly is continued after removing the supporting arm. The chamfering may be so arranged that the end surface has a flat portion or is of an edge with large chamfering. The circular contour of the end surface of sliding door may be an alternative instead of chamfering.

The chamfered portion of the sliding door is fitted into the V-shape groove deeply and the sliding door is thereby held upright, by assembling the magnetic tape cartridge this way. Therefore, the prevention of the falling of the sliding door is more ensured, which enables the accurate and easy mating of the lower half section and the upper half section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention will now be described in detail referring to the accompanying drawings.

First Embodiment

The referring drawings are as follows:FIG. 1is an exploded perspective view illustrating a magnetic tape cartridge;FIG. 2is an enlarged view illustrating the vicinity of a sliding door shown inFIG. 1;FIG. 3(a) is a section view taken along the line III—III inFIG. 2;FIG. 3(b) is a section view taken along the line III—III inFIG. 2for another rib position.FIG. 4(a) is a section view taken along the line IV—IV inFIG. 2;FIG. 4(b) is a section view taken along the line IV—IV inFIG. 2for another sliding door;FIG. 5is an enlarged perspective view illustrating the sliding door inserted in the lower guide channel;FIG. 6is a section view taken along the line VI—VI inFIG. 5.

As shown inFIG. 1a magnetic tape cartridge includes a lower half section2and an upper half section3, which form a cartridge case1. Inside the lower half section2and the upper half section3are housed a reel4wound with a magnetic tape41, a sliding door5, a spring member6, an inadvertent erasing protection claw71, an IC chip72and a compression coil spring73.

An opening11, which lies across the lower half section2and the upper half section3, for extracting the magnetic tape41is provided near the corner of a side wall21aof the cartridge case1. The opening11is opened or closed by the sliding door5, which slides along the side wall21aof the lower half section2and the side wall31of the upper half section3. The spring member6, which is a torsion coil spring with two coils, imposes the force on the sliding door5in the closing direction continuously.

A leader pin42is clamped at the leading end of the magnetic tape41with a clip43. The leader pin42will be held by the tape loading mechanism of a record playback unit, when the record playback unit retracts the magnetic tape41through the opening11.

The cartridge case1is formed by mating the two parts, the lower half section2and the upper half section3, which include half section of the cartridge case respectively. Reinforcing ribs22a,22band22care prepared on the base28of the lower half section2so positioned that they may not interfere with the reel4. The space between the reinforcing ribs22a,22band22cand the side walls21a,21b,21cand21dis so arranged that the supporting and mounting of parts can be performed.

As shown inFIG. 2, a lower guide channel24, referred to as the guide according to the appended claims, is carved on the base28so that the sliding door5can slide smoothly. The lower guide channel24is shallow and guides the sliding door5freely along with an upper guide channel34of the upper half section3to be described later (seeFIG. 1). The lower guide channel24includes, as shown inFIG. 3(a), a first guide wall24alocated relatively inside the cartridge case and a second guide wall24blocated the opposite side, nearer the side wall21a. A continuous rib81projects from the top and some rear end portion of the first guide wall24a(left direction inFIG. 1), toward the second guide wall24b. The rib81may be discontinuous instead. Also the rib81can be laid from the front to rear end of the lower guide channel24thoroughly if the sliding door5can be inserted into the lower guide channel24forcefully, when the material of the sliding door5or the shape of the lower guide channel24permits it.

The rib81, the details of which will be described later, restricts the vertical displacement of the sliding door5by engaging with a groove55of an inner side surface54aof the sliding door5(seeFIG. 4(a)). In this embodiment, the rib81projects from the first guide wall24a, though it can project from the second guide wall24bshown inFIG. 3(b). In that case a rib81′ engages with a groove55′ of an outer side surface54bof the sliding door5(seeFIG. 4(b)).

A spring holder23, which holds a fixing spring arm62of the spring member6, is a vertical slit, which is cut on the reinforcing rib22athat stands inside the side wall21aacross the lower guide channel24. A holder25, which holds the leader pin42(seeFIG. 1) attached on the leading end of the magnetic tape41, is provided in the corner inside the lower half section2. When a record playback unit opens the sliding door5, the arm of the tape loading mechanism of the record playback unit needs to press a front end5aof the sliding door5(right direction inFIG. 2). Therefore, a cutout27for introducing the arm, about upper two thirds of the side wall21b, is provided for the side wall21bwith which the front end5aof the sliding door5interferes. And under the cutout27is provided a contact member26, to which the front end5aof the sliding door5contacts when the sliding door is closed.

The inner surface of the upper half section3(not shown) is formed approximately symmetrical with that of the lower half section2. The upper guide channel34, which guides the top of sliding door5, is carved inside the opening along the side wall31in parallel with the opposite lower guide channel24(seeFIG. 1).

The spring member6is a torsion coil spring having two coils61. When the spring member6is mounted on the lower half section2, the fixing spring arm62of the rear end is held by the spring holder23of the reinforcing rib22aand an acting spring arm63is placed in the lower guide channel24. The acting spring arm63placed in the lower guide channel24, to be described in detail later, is held by a spring holder51provided in a rear end5bof the sliding door5(left direction inFIG. 2). Though the coil spring is employed for the spring member6in the explanation of the embodiment, any types of springs such as a compression coil spring, extension coil spring, torsion coil spring, laminated spring, torsion bar, spiral spring, coned disk spring and flat spring may be used for the spring member6. Their materials are not limited to metals but resins may be used instead.

The sliding door5is a thin rectangular plate, in the rear end5bof which the spring holder51for holding the acting spring arm63is formed in a U-shape cutout. The lower portion of the spring holder51has a wedge52so that the acting spring arm63of the spring member6lying in the lower guide channel24may be lifted and guided to the spring holder51, when the sliding door5is mounted on the lower half section2. A projection53, which protrudes toward the rear end5bof the sliding door5and the upper portion of which is cut out, is prepared for the spring holder51so that the coils61of the spring member6may not interfere with the sliding door5, when the sliding door5is opened.

The groove55is carved on the inner side surface54aof the sliding door5facing the rib81to engage with the rib81(seeFIG. 3(a)) projecting from the top of the first guide wall24a, as shown inFIG. 2andFIG. 4(a). The groove55is laid from the front end5ato the rear end5b. The groove55engages with the rib81of the first guide wall24a, and not only restricts the vertical displacement of the sliding door5but also guides the sliding door5in the lower guide channel24freely. When the rib81′ projects from the second guide wall24b, located nearer the side wall21aas shown inFIG. 3(b), the groove55′ engaging with the rib81′ will be carved on the outer side surface54bof the sliding door5as shown inFIG. 4(b).

When the magnetic tape cartridge described above is assembled, the fixing spring arm62of the spring member6is held by the spring holder23and the acting spring arm63is set in the lower guide channel24. Next, the sliding door5is inserted into the lower guide channel24tilted with the wedge52downward and carried to the acting spring arm63. After the wedge52hits the acting spring arm63, the wedge52is continued to slide in the lower guide channel24, bending the spring member6. When the load of the spring member6reaches a given value, the acting spring arm63is lifted by the wedge52and then held by the spring holder51. When the spring member6is compressed till the whole sliding door5is ready for being inserted into the lower guide channel24, the sliding door5is dropped to insert into the lower guide channel24(seeFIG. 5).

And as shown inFIG. 5andFIG. 6, the rib81, which projects from the first guide wall24aof the lower guide channel24, and the groove55carved on the inner side surface54aof the sliding door5are engaged. Once the rib81and the groove55are engaged, the sliding door55will not lift from the lower guide channel24even if the spring member6imposes the force on the sliding door5in the closing direction, since the sliding door5is restrained from displacing vertically. When the lower half section and the upper half section are mated this way, the sliding door5is mated properly with the lower guide channel24of the lower half section2.

Second Embodiment

Next the second embodiment of the invention will be described. In the description hereinafter, the detail explanations will be omitted for the items, which are the same as those of the first embodiment, bearing the same symbols.FIG. 7is a view illustrating the section taken along the line VII—VII inFIG. 5, which shows the magnetic tape cartridge according to the second embodiment of the present invention.

As shown inFIG. 7a rib56projects from the inner side surface54aof the sliding door5against the first guide wall24aof the lower guide channel24. The rib56is laid out from the front end5ato the rear end5b(seeFIG. 2). A groove82, which is to engage with the rib56projecting from the inner side surface54aof the sliding door5, is carved on the first guide wall24aof the lower guide channel24facing the rib56.

When the sliding door5is inserted into the lower guide channel24, the vertical displacement of the sliding door5is restricted, since the rib56projecting from the inner side surface54aof the sliding door5engages with the groove82carved on the first guide wall24aof the lower guide channel24. Thus the sliding door5will not lift from the lower guide channel24even if the spring member6imposes the force on the sliding door5in the closing direction. The groove82carved on the first guide wall24aguides the sliding door5, which is inserted into the lower guide channel24, in the lower guide channel24freely. The rib56can project from the outer side surface54binstead of the inner side surface54aof the sliding door5(not shown). In this case the rib56will engage with the groove carved on the second guide wall24b.

Third Embodiment

Next the third embodiment of the invention will be described. In the description hereinafter, the detail explanations will be omitted for the items, which are the same as those of the first or second embodiment, bearing the same symbols.FIG. 8is a view illustrating the section taken along the line VIII—VIII inFIG. 5, which shows the magnetic tape cartridge according to the third embodiment of the present invention.

As shown inFIG. 8, a rib83projects from the inner surface of the side wall21aof the lower half section2. A groove57, which is to engage with the rib83, is carved on the outer side surface54bof the sliding door5facing the rib83. The groove57is laid out from the front end5ato the rear end5bof the sliding door5(seeFIG. 2).

When the sliding door5is inserted into the lower guide channel24, the vertical displacement of the sliding door5is restricted, since the rib83projecting from the inner surface of the side wall21aengages with the groove57carved on the outer side surface54bof the sliding door5. Thus the sliding door5will not lift from the lower guide channel24even if the spring member6imposes the force on the sliding door5in the closing direction. The groove57carved on the outer side surface54bof the sliding door5guides the sliding door5, which is inserted into the lower guide channel24, in the lower guide channel24freely. The rib83can project from the outer side surface54bof the sliding door5instead of the inner surface of the side wall21a(not shown). In this case the rib83will engage with the groove carved on the inner surface of the side wall21a.

Fourth Embodiment

Next the fourth embodiment of the invention will be described.FIG. 9is an exploded perspective view of the magnetic tape cartridge, andFIG. 10is an enlarged view illustrating the vicinity of the sliding door shown inFIG. 9.FIG. 11is another enlarged view showing the vicinity of the sliding door, which is inserted in the lower guide channel.FIG. 12is a section view taken along the line XII—XII inFIG. 11.FIG. 13is a section view taken along the line XIII—XIII inFIG. 11.

As shown inFIG. 9, the magnetic tape cartridge according to the fourth embodiment is so arranged that the reel4wound by the magnetic tape41, the sliding door, the spring member6, the inadvertent erasing protection claw71, the IC chip72and the compression coil spring73are housed in the lower half section2and the upper half section3, which form the cartridge case1.

The opening11, which lies across the lower half section2and the upper half section3, for extracting the magnetic tape41is provided near the corner of the side wall21aof the cartridge case1. The opening11is opened or closed by the sliding door5, which slides along the side wall21aof the lower half section2and the side wall31of the upper half section3. The spring member6, which is a torsion coil spring with two coils, imposes the force on the sliding door5in the closing direction continuously.

The leader pin42is clamped at the leading end of the magnetic tape41with the clip43. The leader pin42will be held by the tape loading mechanism of a record playback unit, when the record playback unit retracts the magnetic tape41through the opening11.

The cartridge case1is formed by mating the two parts, the lower half section2and the upper half section3, which include half section of the cartridge case respectively. Reinforcing ribs22a,22band22care provided on the base28of the lower half section2. The space between the reinforcing ribs22a,22band22cand the side walls21a,21b,21cand21dis so arranged that the supporting and mounting of parts can be performed.

As shown inFIG. 10, the lower guide channel24, referred to as the guide according to the appended claim, is carved on the base28so that the sliding door5can slide smoothly. The lower guide channel24is shallow and guides the sliding door5freely along with the upper guide channel34of the upper half section3to be described later (seeFIG. 9).

A restricting rib8stands along the lower guide channel24on the base28in a given height, which refers to the restriction device according to the appended claims. The restricting rib8is placed facing the side wall21aof the lower half section2, between which the lower guide channel24lies, to restrain the sliding door5from falling in the direction normal to its plane along with the side wall21a, when the sliding door5is inserted into the lower guide channel24. The height of the restricting rib8is so arranged that it may support to prevent the sliding door5from falling.

The spring holder23, which holds the fixing spring arm62of the rear end of the spring member6, is a vertical slit, which is cut on the reinforcing rib22athat stands inside the side wall21aacross the lower guide channel24. The holder25, which holds the leader pin42(seeFIG. 1) attached on the leading end of the magnetic tape41, is provided in the corner inside the lower half section2. When a record playback unit opens the sliding door5, the arm of the tape loading mechanism of the record playback unit needs to press the front end5aof the sliding door5(right direction inFIG. 10). The cutout27for introducing the arm, about upper two thirds of the side wall21b, is provided for the side wall21bwith which the front end5aof the sliding door5interferes. And under the cutout27is provided the contact member26, to which the front end5aof the sliding door5contacts when the sliding door is closed.

The inner surface of the upper half section3(not shown) is formed approximately symmetrical with that of the lower half section2. The upper guide channel34, which guides the top of sliding door5, is carved inside the opening along the side wall31in parallel with the opposite lower guide channel24(seeFIG. 9).

The spring member6is a torsion coil spring having two coils61. When the spring member6is mounted on the lower half section-2, the fixing spring arm62of the rear end is held by the spring holder23of the reinforcing rib22aand the acting spring arm63is placed in the lower guide channel24. The acting spring arm63placed in the lower guide channel24, to be described in detail later, is held by the spring holder51provided in the rear end5bof the sliding door5(left direction inFIG. 10). Though the coil spring has been used for the spring member6in the explanation of the embodiment, any types of springs such as a compression coil spring, extension coil spring, torsion coil spring, laminated spring, torsion bar, spiral spring, coned disk spring and flat spring may be employed. Their materials are not limited to metals but resins may be used instead.

The sliding door5is a thin rectangular plate, in the rear end5bof which the spring holder51for holding the acting spring arm63is formed in a U-shape cutout. The lower portion of the spring holder51has the wedge52so that the acting spring arm63of the spring member6lying in the lower guide channel24may be lifted and guided to the spring holder51, when the sliding door5is mounted on the lower half section2. The projection53, which protrudes toward the rear end5bof the sliding door5and the upper portion of which is cut out, is prepared for the spring holder51so that the coils61of the spring member6may not interfere with the sliding door5, when the sliding door5is opened.

When the magnetic tape cartridge described above is assembled, the fixing spring arm62of the spring member6is held by the spring holder23and the acting spring arm63is set in the lower guide channel24. Next, the sliding door5is inserted into the lower guide channel24tilted with the wedge52downward and the sliding door5is carried to the acting spring arm63. After the wedge52hits the acting spring arm63, the wedge52is continued to slide in the lower guide channel24, bending the spring member6. Then when the load of the spring member6reaches a given value, the acting spring arm63is lifted by the wedge52and held by the spring holder51. When the spring member6is compressed till the whole sliding door5is ready for being inserted into the lower guide channel24, the sliding door5is dropped to insert into the tower guide channel24(seeFIG. 11).

The restricting rib8prevents the sliding door5inserted in the lower guide channel24from falling inward of the sliding door5(right direction inFIG. 12, upper direction inFIG. 13), in contact with the inner side surface54aof the sliding door5shown inFIG. 12andFIG. 13. Also, the sliding door5will not fall outward of the sliding door5(left direction inFIG. 12or lower direction inFIG. 13), since the outer side surface54bof the sliding door5is in contact with the side wall21aof the lower half section2. Thus the sliding door5is prevented from falling in the direction normal to its plane by the restricting rib8and the side wall21a, thereby inserted into the lower guide channel24of the lower half section2properly. Therefore, if the lower half section and the upper half section are mated under the conditions described above, it will be performed easily.

Fifth Embodiment

Next the fifth embodiment of the invention will be described. In the description hereinafter, the detail explanations will be omitted for the items, which are the same as those of the fourth embodiment, bearing the same symbols.FIG. 14is a view illustrating the section taken along the line XIV—XIV inFIG. 11showing the fifth embodiment.

As shown inFIG. 14, the restricting rib8according to the fifth embodiment of the invention is divided into a plurality of restricting ribs8a,8band8c. The restricting ribs8a,8band8cprevent the sliding door5, which is inserted in the lower guide channel24, from falling inward (upper direction inFIG. 14) by keeping in contact with the inner side surface54aof the sliding door5. The number of division of the restricting rib8and the spacing of individual restricting ribs may be arranged as required.

Sixth Embodiment

Next the sixth embodiment of the invention will be described. In the description hereinafter, the detail explanations will be omitted for the items, which are the same as those of the fourth embodiment, bearing the same symbols.FIG. 15is a view illustrating the section taken along the line XV—XV inFIG. 11showing the sixth embodiment.

As shown inFIG. 15, the reinforcing rib22aaccording to the sixth embodiment of the invention stands along the lower guide channel24. The restriction device according to appended claims can be attained by standing the reinforcing rib22aalong the lower guide channel24. The reinforcing rib22aprevents the sliding door5from falling inward of the sliding door5(upper direction inFIG. 15), by keeping in contact with the inner side surface54aof the sliding door5, which is inserted in the lower guide channel24.

Seventh Embodiment

Next the seventh embodiment of the invention will be described. In the description hereinafter, the detail explanations will be omitted for the items, which are the same as those of the fourth embodiment, bearing the same symbols.FIG. 16is a view illustrating the section taken along the line XVI—XVI inFIG. 11showing the seventh embodiment.

As shown inFIG. 16, pins9a,9band9caccording to the seventh embodiment of the invention stand along the lower guide channel24. The restriction device according to appended claims can be attained by standing the pins9a,9band9calong the lower guide channel24. The pins9a,9band9cprevent the sliding door5from falling inward of the sliding door5(upper direction inFIG. 16), by keeping in contact with the inner side surface54aof the sliding door5, which is inserted in the lower guide channel24. The number of pins9and the spacing of individual pins may be arranged as required.

Eighth Embodiment

The eighth embodiment of the present invention will be described with the reference to the accompanying drawings.FIG. 17is an exploded perspective view of the magnetic tape cartridge andFIG. 18is an enlarged view showing the vicinity of the sliding door.

As shown inFIG. 17, the magnetic tape cartridge according to the eighth embodiment is so arranged that the reel4wound by the magnetic tape41, the sliding door5, the spring member6, the inadvertent erasing protection claw71, the IC chip72and the compression coil spring73are housed in the lower half section2and the upper half section3, which form the cartridge case1.

The opening11, which lies across the lower half section2and the upper half section3, for extracting the magnetic tape41is provided near the corner of the side wall21aof the cartridge case1. The opening11is opened or closed by the sliding door5, which slides along the side wall21aof the lower half section2and the side wall31of the upper half section3. The sliding door5is continuously pressed in the closing direction by the spring member6, which is a torsion coil spring with two coils.

The leader pin42is clamped at the leading end of the magnetic tape41with the clip43. The leader pin42will be held by the tape loading mechanism of a record playback unit, when the record playback unit retracts the magnetic tape41.

The cartridge case1is formed by mating the two parts, the lower half section2and the upper half section3, which include half section of the cartridge case respectively. Reinforcing ribs22are positioned so that they may not interfere with the reel4on the base of the lower half section2. The cartridge case is so arranged that the supporting and mounting of parts can be performed with the reinforcing ribs22.

As shown inFIG. 18, the lower guide channel24, referred to as the guide according to the appended claims, is carved on the base28so that the sliding door5can slide smoothly. The lower guide channel24is shallow and guides the sliding door5freely along with the upper guide channel34of the upper half section3to be described later (seeFIG. 17). The spring holder23, which holds the fixing spring arm62of the rear end of the spring member6, is a vertical slit, which is cut on one of the reinforcing ribs22that stands inside the side wall21aacross the lower guide channel24. The holder25, which holds the leader pin42when it is in the cartridge case, is provided in the corner inside the lower half section2. The cutout27for introducing the arm, about upper two thirds of the side wall21b, is provided for the side wall21bwith which the front end of the sliding door5(right direction inFIG. 18) interferes, since the arm of a record playback unit needs to press the front end of the sliding door5when the record playback unit opens the sliding door5. The contact member26, with which the front end of the sliding door is in contact when it is closed, is elevated from the base28of the lower half section2.

The inner surface of the upper half section3(not shown) is formed approximately symmetrical with that of the lower half section2. The upper guide channel34, which guides the top of sliding door5, is carved inside the opening along the side wall31in parallel with the opposite lower guide channel24(seeFIG. 17).

The spring member6is a torsion coil spring having two coils61. When the spring member6is mounted on the lower half section2, the fixing spring arm62of the rear end is held by the spring holder23and the acting spring arm63of the front end is placed in the lower guide channel24. Subsequently, the sliding door5is inserted into the lower guide channel24, while the acting spring arm63is bent by the rear end of the sliding door5(left direction inFIG. 18)

The sliding door5is a thin rectangular plate, in the rear end of which the spring holder51for holding the acting spring arm63is formed in a U-shape cutout. The lower portion of the spring holder51has the wedge52so that the acting spring arm63of the spring member6may be lifted, when the sliding door5is mounted on the lower half section2by bending the spring member6. The projection53is prepared, which protrudes toward the rear end of the sliding door5and the upper portion of which is cut out so that the coils61of the spring member6may not interfere with the sliding door5when it is opened. The top of the projection53is slightly higher than the side wall21a, thereby exceeding the height of the side wall21a, when the sliding door5is inserted into the lower guide channel24.

The process of assembling the magnetic tape cartridge descried above will next be explained. Any type of assembly can be applied to the magnetic tape cartridge such as the assembly by a man, the assembly with dedicated assembly equipment, or the assembly with an all-purpose robot.

FIG. 19(a) andFIG. 19(b) are for explaining the assembly process of the magnetic tape cartridge shown inFIG. 17. When the magnetic tape cartridge described above is assembled, the fixing spring arm62of the spring member6is held by the spring holder23and the acting spring arm63is set in the lower guide channel24. Next, the sliding door5is inserted inside the side wall21atilted with the wedge52downward, and the sliding door5is carried to the acting spring arm63sliding the wedge52in the lower guide channel24. After the wedge52hits the acting spring arm63, the wedge52is continued to slide in the lower guide channel24, bending the spring member6. Then when the load of the spring member6reaches a given value, the acting spring arm63is lifted by the wedge52and held by the spring holder51. When the spring member6is compressed till the whole sliding door5is ready for being inserted into the lower guide channel24, the sliding door5is dropped to insert into the lower guide channel24. The sliding door5will stand still if no external force acts, since the sliding door5is pressed to the contact member26by the force imposed by the spring member6. However, the sliding door5may possibly be lifted and off the lower guide channel24by small force such as vibration, since the spring member6and the sliding door5are unstable due to the fact that the force acting on the sliding door5by the spring member6is supported only by the small contact member26standing on the base28of the lower half section2. Also the sliding door5is liable to fall inward the lower half section2, for the sliding door5is supported only by the side wall21aand the shallow lower guide channel24in the direction normal to its plane (thickness direction).

So as shown inFIG. 19for example, an L-shape stick7, which is an assembly support device having a right-angle bent end, a holding point7a, is introduced to press the spring member6toward the base28. The L-shape stick7is brought from the outside of the lower half section2over the spring member6with the holding point7adownward (see the two-dot chain line inFIG. 19(a)), and dropped to press the spring member6toward the base28of the lower half section2(see the solid line inFIG. 19(a)). Thus the spring member6is prevented from lifting. Further, since the acting spring arm63is held on the spring holder51, the spring member6imposes the force on the sliding door5, thereby preventing the sliding door5from lifting. It would be preferable to draw the spring member6to the side wall21awith the L-shape stick7in parallel with pressing the spring member6toward the base28. This will allow standing the spring member6normal to the base28, since the spring member6is pressed to the side wall21a. When the spring member6is pressed to the side wall21a, the sliding door5is pressed to the side wall21aby the acting spring arm63, since the sliding door5is interposed between the acting spring arm63and the side wall21a. Therefore, the sliding door5can also stand normal to the base28.

The lifting and falling of the sliding door5and the spring member6will be prevented under the conditions that the spring member6is pressed as described above, when the upper half section3is mated with the lower half section2. Therefore, the sliding door5is not off the lower guide channel24, thus enabling the sliding door5to be inserted into the upper guide channel34easily (seeFIG. 17), which is carved on the upper half section3.

Pressing of the spring member6by the L-shape stick7should be released just before the completion of mating the upper half section3with the lower half section2, since the L-shape stick7will be an obstacle for finalizing the mating. As shown inFIG. 19(b), in which the upper half section is omitted, when the upper half section3has been mated just over the L-shape stick7, the L-shape stick7is turned 90 deg clockwise inFIG. 19(b) (see the two-dot chain line) and pulled out of the lower half section2(see the solid line). Subsequently, the upper half section3is mated with the lower half section2completely. Thus the mating of the lower half section2and the upper half section3can be performed easily.

Next, the application of the method for assembling the magnetic tape cartridge according to the present invention to another type of magnetic tape cartridges will be described. In the following the detailed description would be omitted for the items which are the same as those according to the eighth embodiment, bearing the same symbols.

Ninth Embodiment

FIG. 20is an enlarged view showing the vicinity of the sliding door of the magnetic cartridge according to the ninth embodiment. The sliding door5shown inFIG. 20is approximately rectangle and has a spring hook hole51a, which is for holding the bent tip of the acting spring arm63aof a spring member6aand positioned at the upper portion of the rear end of the sliding door5(left direction inFIG. 20). Under the spring hook hole51ais provided a cutout54of U-shape, which is cut from the rear end for pressing the sliding door5toward the base28of the lower half section2. The cutout54is provided so that the L-shape stick7can press the slide door5at the possible lowest position, which at the same time should be higher than the side wall21a. Thus the L-shape stick7will be of no interference when the upper half section3(seeFIG. 17) is mated with the lower half section2.

The spring member6is a torsion coil spring having two coils61a. A fixing spring arm62aof the rear end side (left direction inFIG. 20) descends and an acting spring arm63aof the front end side (right direction inFIG. 20) ascends. The fixing spring arm62ais held by the spring holder23and the acting spring arm63ais held by the spring hook hole51a.

The magnetic tape cartridge having the sliding door5and the spring member6encounters the difficulty that the rear end of the sliding door5is liable to be lifted in mating the lower half section2with the upper half section3, since the spring member6aimposes the force on the sliding door6so as to lift the sliding door5upward.

After the L-shape stick7is inserted into the cutout54, the sliding door5is drawn to the side wall21awith the holding point7aas well as pressed toward the base28of the lower half section2. Thus the lifting and falling of the spring member6aand the sliding door5will be prevented. Therefore, if the lower half section2and the upper half section3is mated this way (seeFIG. 20), it will be performed easily.

Tenth Embodiment

The tenth embodiment will be described.FIG. 21is an enlarged perspective view showing the vicinity of the sliding door of the magnetic tape cartridge according to the tenth embodiment.

As shown inFIG. 21, according to the tenth embodiment, a spring supporting rod51, around which a compression coil spring6bis installed, projects from the middle of the rear end of the sliding door5(left direction inFIG. 21). A spring holder23bfor holding the end of the compression coil spring6bstands on the base28of the lower half section2in the rear of the lower guide channel24(left direction inFIG. 21).

When the magnetic tape cartridge of this type is assembled, the compression coil spring6bis compressed while the spring supporting rod51bis slanted and the end of the compression coil spring6bis held by the spring holder23b, and the sliding door5is gradually dropped to insert into the lower guide channel24. Under these conditions, if the compression spring6bis pressed downward, namely toward the base28of the lower half section2with the L-shape stick7, and also drawn to the side wall21awith the holding point7ahooked on the compression coil spring6b, the lifting and falling of the sliding door5can be prevented. Therefore, if the lower half section2and the upper half section3is mated this way, it will be performed easily.

Eleventh Embodiment

The eleventh embodiment will be described.FIG. 22is an enlarged perspective view showing the vicinity of the sliding door of the magnetic tape cartridge according to the eleventh embodiment. As shown inFIG. 22according to the eleventh embodiment, a leaf spring6cbent like waves is employed. The sliding door5is so arranged that a spring holder51cof a plate, the height of which is lower than a door portion5n, is integrated with the door portion5nof a thin rectangular plate. The front end of the leaf spring6c(right direction inFIG. 22) is housed between the spring holder51cand the side wall21aof the lower half section2. And the rear end of the leaf spring6cis held by a spring holder23cstanding at the rear end of the lower guide channel24, in which the sliding door5slides.

When the magnetic tape cartridge of this type is assembled, the rear end of the leaf spring6cis held by the spring holder23cand then the sliding door5is inserted into the lower guide channel24by compressing the leaf spring6cwith the sliding door5. With the L-shape stick7, the top of the spring holder51cis pressed downward, namely toward the base28of the lower half section2, and the spring holder51cis simultaneously drawn to the side wall21aof the lower half section2. Thus the lifting and falling inward of the sliding door5and the leaf spring6ccan be prevented, since the leaf spring6clies between the side wall21aand the spring holder51c. Therefore, when the upper half section3is mated with the lower half section2with the L-shape stick7pressing the spring holder51c, the magnetic tape cartridge will be assembled easily and securely.

It will now be appreciated from the foregoing description that the present invention is not limited to the particularly illustrated embodiments 8 through 11 discussed above and may be carried out in various modified forms. For example, the position of the spring member or the sliding door, on which the L-shape stick imposes the force, can be selected according to the shapes of the parts.

Twelfth Embodiment

The twelfth embodiment of the invention will now be described in detail.FIG. 23is an exploded perspective view of the magnetic tape cartridge,FIG. 24(a) is a top view of the sliding door and the supporting arm andFIG. 24(b) is a perspective view of the sliding door and the supporting arm.

As shown inFIG. 23, the magnetic tape cartridge according to the present embodiment is so arranged that the reel4wound by the magnetic tape41, the sliding door5, the spring member6, the inadvertent erasing protection claw71, the IC chip72and the compression coil spring73are housed in the lower half section2and the upper half section3, which form the cartridge case1.

The opening11, which lies across the lower half section2and the upper half section3, for extracting the magnetic tape41is provided near the corner of the side wall21aof the cartridge case1. The opening11is opened or closed by the sliding door5, which slides along the side wall21aof the lower half section2and the side wall31of the upper half section3. The sliding door5is continuously pressed by the spring member6, which is a torsion coil spring with two coils.

The leader pin42is clamped at the leading end of the magnetic tape41with the clip43. The leader pin42will be held by the tape loading mechanism of a record playback unit, when the record playback unit retracts the magnetic tape41.

The cartridge case1is formed by mating the two parts, the lower half section2and the upper half section3, which include half section of the cartridge case respectively. Reinforcing ribs22are so positioned that they may not interfere with the reel4on the base28of the lower half section2. The cartridge case is so arranged that the supporting and mounting of parts can be performed with the reinforcing ribs22.

The lower guide channel24, referred to as the guide according to the appended claims, is carved on the base28so that the sliding door5can slide smoothly. The lower guide channel24is shallow and guides the sliding door5freely along with the upper guide channel34of the upper half section3to be described later (seeFIG. 23). The spring holder23, which holds the fixing spring arm62of the spring member6, is a vertical slit, which is cut on one of the reinforcing ribs22that stands inside the side wall21aacross the lower guide channel24. A holder25, which holds the leader pin42, is provided in the corner inside the lower half section2. The cutout27for introducing the arm, about upper two thirds of the side wall21b, is provided for the side wall21bwith which the front end5aof the sliding door5interferes, since the arm of a record playback unit needs to press the front end5aof the sliding door5when the record playback unit opens the sliding door5. The contact member26, with which the front end5aof the sliding door5is in contact when it is closed, is elevated from the base28of the lower half section2.

The inner surface of the upper half section3(not shown) is formed approximately symmetrical with that of the lower half section2. The upper guide channel34, which guides the top of sliding door5, is carved inside the opening11along the side wall31in parallel with the opposite lower guide channel24(seeFIG. 23).

As shown inFIG. 23andFIG. 25, the spring member6is a torsion coil spring having two coils61. When the spring member6is mounted on the lower half section2, the fixing spring arm62of the rear end is held by the spring holder23and the acting spring arm63is placed in the lower guide channel24. Subsequently, the sliding door5is inserted into the lower guide channel24, while the acting spring arm63is bent by the rear end of the sliding door5.

The sliding door5is a thin rectangular plate, in the rear end of which the spring holder51for holding the acting spring arm63is formed in a U-shape cutout. The lower portion of the spring holder51has the wedge52so that the acting spring arm63of the spring member6may be lifted, when the sliding door5is mounted on the lower half section2by bending the spring member6. The projection53, which protrudes in the opening direction of the sliding door and upper portion of which is cut out so that the coils61of the spring member6may not interfere with the sliding door5when it is opened. The top of the projection53is slightly higher than the side wall21a, thereby exceeding the height of the side21a, when the sliding door5is inserted in the lower guide channel24.

The magnetic tape cartridge of this type is assembled as follows. The sliding door5is inserted into the lower guide channel24of the lower half section2so that the spring member6may impose the force on the sliding door5. The lower half section2and the upper half section3are mated while the front end5aof the sliding door5is supported by a supporting arm90, which belongs to assembly apparatus (not shown). The supporting arm90shown inFIG. 24, which comes in contact with approximately half of the front end5aof the sliding door5in the middle and has a V-shape groove91facing the front end5a. The V-shape groove91, which is positioned in front of the front end5a, approaches the front end5aof the sliding door5, presses the front end5aand leaves it, when the supporting arm90is driven by a one-axis driving means (not shown). Only the portion that comes in contact with the V-shape groove91is chamfered with the same slope as that of the V-shape groove91to form a chamfered portion58on the corners, where the front end5aof the sliding door5and the inner or outer surface of the sliding door5meet.

The assembly of the magnetic tape cartridge of this type with the supporting arm90will be described now. Any type of assembly can be applied to the magnetic tape cartridge such as the assembly by a man, the assembly with dedicated assembly equipment, or the assembly with an all purpose robot.

FIG. 25andFIG. 26are for explaining the assembly process of the magnetic tape cartridge according to this embodiment. As described before, the fixing spring arm62of the spring member6is held by the spring holder23and the acting spring arm63is set in the lower guide channel24. Next, the sliding door5is placed inside the side wall21atilted with the wedge52downward and the sliding door53is carried to the acting spring arm63. After the wedge52hits the acting spring arm63, the wedge52is continued to slide in the lower guide channel24, bending the spring member6. Then when the load of the spring member6reaches a given value, the acting spring arm63is lifted by the wedge52and held by the spring holder51. When the spring member6is compressed till the whole sliding door5is ready for being inserted into the lower guide channel24, the sliding door5is dropped to insert into the lower guide channel24. The sliding door5will stand still if no external force acts, since the sliding door5is pressed to the contact member26by the force imposed by the spring member6(seeFIG. 25(a)). However, the sliding door5may possibly be lifted and off the lower guide channel24by small force such as vibration, since the spring member6and the sliding door5are unstable due to the fact that the force acting on the sliding door5by the spring member6is supported only by the small contact member26standing on the base28of the lower half section2. Also the sliding door5is liable to fall inward the lower half section2, for the sliding door5is supported only by the side wall21aand the shallow lower guide channel24in the direction normal to the plane of the sliding door5(thickness direction).

In order to solve the problem mentioned above, the supporting arm90is brought closer in a parallel movement in front of the sliding door5and the V-shape91of the supporting arm90is in contact with the chamfered portion58. Moving the supporting arm90further in the opening direction of the sliding door, the sliding door5is opened. When the sliding door5is opened by one third approximately, the supporting arm90is stopped.

Thus the sliding door5is pressed against the V-shape groove91with the force imposed by the spring member6. The sliding door5will be supported to stand normal to the base28of the lower half section2securely, since the chamfered portion58of the sliding door5is inserted into the V-shape groove91deeply.

The upper half section3is mated with the lower half section2while the front end5aof the sliding door5is supported by the supporting arm90(seeFIG. 26(a)). The sliding door5will be inserted into the upper guide channel34of the upper half section3securely, since the front end5aof the sliding door5is supported by the supporting arm90as described above. Subsequently, the supporting arm90is moved in the closing direction of the sliding door5in a parallel movement and detached from the front end5a, which will complete the mating of the lower half section2and the upper half section3(seeFIG. 26(b)).

In this manner, the magnetic tape cartridge can be assembled easily and securely by mating the upper half section3with the lower half section2supporting the sliding door5by the V-shape groove91.

Next, the application of the method for assembling the magnetic tape cartridge according to the present invention to another type of magnetic tape cartridges will be described. In the following the detailed description would be omitted for the items, which are the same as those according to the twelfth embodiment, bearing the same symbols.

Thirteenth Embodiment

FIG. 27is an enlarged perspective view showing the sliding door and the supporting arm according to the thirteenth embodiment. As shown inFIG. 27, the sliding door5has the chamfered portion58only in the vicinity of the top of the front end5a. The chamfered portion58has the sharp edge, as the chamfering is performed up to the center of the thickness of the sliding door5leaving no flat area at the end. There formed a step59between the chamfered portion58and its lower neighboring portion without chamfering. A supporting arm90ahas a V-shape groove91a, which faces the chamfered portion58. The V-shape groove91ais formed by fixing two slope parts92aof trapezoidal cross section spaced on the front end of an arm95a. A groove91ais formed in the bottom of the V-shape.

The supporting arm90awill prevent the sliding door5from falling in the direction normal to its plane by supporting the front end5aof the sliding door5, thus enabling an easy and secure mating of the lower half section2and the upper half section3. According to this embodiment, the lifting of the sliding door5is prevented since the vertical displacement of the sliding door5is restricted in such a way that the step59hits the slope parts92a, while the sliding door5is supported by the supporting arm90a. Therefore, the lower half section2and the upper half section3can be mated more securely, since the sliding door5is prevented from being off the lower guide channel24during the mating.

Fourteenth Embodiment

The fourteenth embodiment of the present invention will now be described.

FIG. 28is an enlarged view showing major parts of the sliding door5and a supporting arm90baccording to the fourteenth embodiment of the invention:FIG. 28(a) is a top view andFIG. 28(b) is a perspective view.

As shown inFIG. 28(a) andFIG. 28(b), the sliding door5has a knob59a, which is the rib placed in the middle of the front end5aprojecting outward from the cartridge case1. This fourteenth embodiment doesn't have the chamfered portion58different from the twelfth and thirteenth embodiments. A V-shape groove91b, the width of which is larger than the combined thickness of the sliding door5and the knob59a, is formed on the supporting arm90bfacing the front end5a.

A combination of the sliding door5and the supporting arm90benables an easy mating of the lower half section2and the upper half section3, since the front end5aof the sliding door5is supported by the supporting arm90bso that the sliding door5stands stably inserted in the V-shape groove91awhile the spring member6imposes the force on the sliding door5. In this embodiment, the sliding door5cannot be opened by moving the supporting arm90bstraight to the sliding door5from its front because the width of the V-shape groove91bis wider than that of the sliding door5. So it is necessary to move the supporting arm90bdiagonally or in an arc from the outside of the cartridge case1so as to position the V-shape groove91bin front of the front end5a, while the sliding door5is opened by another assembly support equipment.

It will now be appreciated from the foregoing description that the present invention is not limited to the particularly illustrated embodiments 12 through 14 discussed above and may be carried out in various modified forms For example, the shapes of the spring member and the sliding door are not limited to what have been exemplified. Any type will be applicable so long as it has the mechanism that the spring member imposes force on the sliding door in the closing direction.