JPH0726977U - Magnetic tape cassette - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the mounting accuracy of the hub locking projections and at the same time prevent the rotation preventing inner teeth of the reel hub from being scraped by the engagement of the hub locking projections. A shutter 41 made of a thin plate member that is slidably attached to the cassette body 1 and opens and closes the hub hole 8 of the cassette body 1, the magnetic head insertion window 19, the pinch roller entry pockets 20 and 21, and the like, Hub rotation preventing means 59, in which a hub locking projection 68 that engages with the rotation preventing inner teeth 39 of the reel hub 6 when the shutter is closed is formed of synthetic resin separately from the thin plate member of the shutter 41.
Structure having.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention employs a thin plate-shaped shutter that is slidably attached to the cassette body, such as a magnetic head insertion window, a pinch roller entry pocket, and a hub hole of the cassette body, which has a box shape with a pair of upper and lower cassette halves. The present invention relates to a magnetic tape cassette that can be opened and closed.

[0002]

[Prior art]

 In recent years, a magnetic tape cassette is used for recording information such as music and images by digital signals, and is generally called a digital compact cassette (DCC). This magnetic tape cassette has a structure as shown in FIGS. 13 to 15, for example. As shown in the figure, this magnetic tape cassette includes a cassette main body 1 in which a magnetic tape or the like is housed, a shutter 2 slidably attached to the cassette main body 1, and an interposing between the cassette main body 1 and the shutter 2. It is composed of a spring member (slider spring) 3 for urging the shutter 2 mounted and attached to the cassette body 1 in a fixed direction.

As is well known, the cassette body 1 has a substantially box-shaped appearance by a pair of upper and lower cassette halves 4 and 5 formed by injection molding of synthetic resin, and a magnetic tape (shown in the figure) A pair of reel hubs 6 around which (abbreviation) is wound and a guide roller and other parts for allowing stable running of the magnetic tape wound around the reel hub 6 are housed. The bottom wall portion 7 of the lower cassette half 4, which is the bottom surface of the cassette, has a hub hole 8 for inserting a tape drive shaft (hub drive shaft) in a digital recording / reproducing apparatus or the like into the reel hub 6, and the spring. A spring mounting recess 9 for accommodating the member 3, a bottom guide groove 10 extending in the left-right direction of the cassette (direction of arrow A in FIG. 13) for restricting the sliding direction of the shutter 2, and on the bottom guide groove 10. A bottom engaging piece 11 and the like that are provided so as to project and that engage the edge of the shutter 2 inserted into the bottom guide groove 10 are formed.

On the other hand, as shown in FIG. 15, on the upper wall portion 14 (lower side in the figure) of the upper cassette half 5 which is the upper surface of the cassette, as in the case of the bottom guide groove 10, the cassette extends in the left-right direction. There is formed an upper guide groove 15 which restricts the sliding direction of the shutter 2. Although not shown, a transparent resin window for visually recognizing the amount of the magnetic tape wound around each reel hub 6 inside the cassette body 1 is provided on the upper wall portion 14 of the upper cassette half 5. It is provided.

Further, as shown in FIG. 13, the cassette front surface 17 provided by the front wall portions of the lower cassette half 4 and the upper cassette half 5 is housed in the cassette body 1 for reading and writing information. A magnetic head insertion window 19 into which a magnetic head such as a digital recording / reproducing device is inserted, or a pinch roller such as a digital recording / reproducing device is inserted into the front surface 17 of the cassette in a portion where the magnetic tape 18 runs. Pockets 20 and 21 for entering the pinch rollers are formed. Further, the range in which the shutter 2 of the lower cassette half 4 and the upper cassette half 5 slides has a step corresponding to the plate thickness of the shutter 2 so that the cassette surface including the shutter 2 becomes flat. Has been granted.

The shutter 2 prevents dust and the like from entering the cassette body 1 through the opening of the cassette body 1 at the time of storage, and the magnetic head insertion window 19 and the shutter 2 are handled at the time of handling. This is for preventing the magnetic tape 18 exposed in the pocket 20 for entering the pinch roller from being inadvertently touched by a finger or the like, so that the magnetic tape 18 is soiled. As shown in FIG. A bottom wall portion 24 for covering the hub hole 8 on the bottom surface of the cassette, and a front wall portion 25 and an upper wall portion 26 for covering the magnetic head insertion window 19 and the pinch roller entry pockets 20, 21 on the front surface of the cassette are provided. With the configuration provided, it is an integrated structure made by bending a thin metal plate.

As shown in FIG. 15, a rear end of the bottom wall portion 24 extends horizontally along the surface of the bottom wall portion 7 between the bottom guide groove 10 and the bottom engaging piece 11. A horizontal flange portion 27 that is inserted into the upper guide groove 15 is provided at a rear end of the upper wall portion 26 and extends in a vertical direction perpendicular to the surface of the upper wall portion 14 and is inserted into the upper guide groove 15. A changer section 28 is provided. Further, the bottom wall portion 24 has a shaft insertion opening 29 corresponding to the hub hole 8, a spring engaging piece 30 for receiving a biasing force from the spring member 3, and a shutter closing for closing the hub hole 8. A hub rotation preventing means 31 for preventing rotation of the reel hub 6 in the cassette body 1 when in the state is provided, and a head insertion opening 33 corresponding to the magnetic head insertion window 19 is provided on the front wall portion 25 side. And a pinch roller opening 34 corresponding to the pinch roller entry pocket 21.

The shutter 2 is mounted on the cassette body 1 by elastically deforming a part of the bottom wall portion 24, the upper wall portion 26, etc., and the horizontal flange portion 27 and the vertical flange portion 28 are fixed to the predetermined one. The engagement with the grooves 10 and 15 prevents the cassette body 1 from falling off.

FIG. 14 shows a state in which the shutter 2 is attached to the cassette body 1. As shown in the figure, when one end of the spring member 3 is engaged with the spring engaging piece 30 and is not attached to a digital recording / reproducing apparatus, the spring member 3 is urged in the direction of arrow D. The shutter 2 is in a closed state in which the opening on the cassette body 1 is closed. A digital recording / playback device is equipped with a shutter opening device for moving the shutter 2 of the attached magnetic tape cassette in the direction of arrow E against the urging force of the spring member 3. When the shutter 2 is mounted on a reproducing device or the like, the shutter 2 is moved so that the shaft insertion opening 29 of the shutter 2 is aligned with the hub hole 8 of the cassette body 1, and the magnetic force on the cassette body 1 is changed. The shutter is opened with the head insertion window 19 and the pinch roller entry pockets 20 and 21 opened.

As shown in FIG. 16, the hub rotation preventing means 31 includes a pillar piece 35 that is bent perpendicularly to the bottom wall portion 24 of the shutter 2 and projects into the hub hole 8, and the pillar piece 35. A pair of hub locking projections 36 is provided at the front end portion of the reference numeral 35, which are vertically bent and project in the sliding direction, and are integrally formed with the bottom wall portion 24. On the other hand, as shown in FIG. 17, the reel hub 6 is provided with a hub pawl 37 protruding from an inner peripheral portion 38 for engaging a tape drive shaft of a digital recording / playback apparatus or the like. A gear portion 40 having inner teeth 39 for preventing rotation is formed concentrically with the inner peripheral portion 38 at a position having a difference from the portion where the gear is formed. When the shutter 2 comes to the position of the shutter open state shown by the symbol F in the figure, the hub locking projection 36 is located between the rotation preventing inner teeth 39 and the hub pawl 37. When the reel hub 6 is retracted, the reel hub 6 is maintained in a rotatable state. It rushes into the space 39 to prevent the reel hub 6 from rotating.

[0011]

[Problems to be solved by the device]

 By the way, when an article having a predetermined three-dimensional structure is manufactured by a series of sheet metal working such as punching and bending of a plate material such as the shutter 2, it becomes difficult to maintain the dimensional accuracy as the number of bending times increases, and The number of steps is increased, and the production cost is high.

In the case of the above-mentioned conventional example, the hub rotation preventing means 31 is accurately engaged with the rotation preventing inner teeth 39 of the reel hub 6 held in the cassette body 1 with a certain amount of play. Since they must be joined together, a considerable dimensional accuracy is required, but it is necessary to bend the pillar piece 35 and the hub locking projection 36 twice with respect to the bottom wall portion 24, and the dimension is required. Since it is also small, it becomes extremely difficult to secure the required accuracy, resulting in inconveniences such as a decrease in product yield or a decrease in the rotation preventing function of the reel hub 6, or an increase in production cost. There was a problem of inviting.

Further, the reel hub 6 is made of synthetic resin, and the hub engaging protrusion 36 that engages with the rotation preventing internal teeth 39 is formed integrally with the bottom wall portion 24 by a thin metal plate. In the related art, the rotation preventing inner teeth 39 may be scraped when the hub locking projection 36 is engaged, and the scraps may cause the magnetic tape 18 to be soiled.

Therefore, an object of the present invention is to solve the above-mentioned problems, and to equip the shutter with high accuracy, a hub locking projection that engages with the inner teeth of the reel hub to prevent rotation of the reel hub. In addition, it is possible to reduce the number of bends required to mold the shutter, and thus prevent inconveniences such as a decrease in product yield and a decrease in the rotation prevention function of the reel hub due to a decrease in dimensional accuracy. A magnetic tape that can reduce the cost and that prevents the rotation-preventing internal teeth from being scraped when the hub locking projection is engaged, thus avoiding contamination of the magnetic tape or the like due to scraps. It is to provide a cassette.

[0015]

[Means for Solving the Problems]

 The above object of the present invention is to accommodate a pair of reel hubs for winding a magnetic tape inside a cassette body by a pair of upper and lower cassette halves, and to prevent the magnetic tape wound on the reel hub from running on the front surface of the cassette. It is equipped with a head insertion window and a pinch roller entry pocket, and is attached slidably to the cassette body and has a shutter made of a thin plate member that opens and closes the hub hole of the cassette body and the opening part on the front surface of the cassette. In the tape cassette, when the shutter is closed to close the hub hole, the shutter is prevented from rotating by a hub locking protrusion that engages with inner teeth for rotation prevention formed on the inner peripheral side of the reel hub. A hub rotation prevention means is installed so as to project inside the cassette. The preventive means is a magnetic tape cassette characterized in that at least the hub engaging projection that engages with the anti-rotation internal teeth is formed of a synthetic resin separate from the other parts of the shutter. To be achieved.

[0016]

Embodiment

 Hereinafter, one embodiment of the present invention will be described in detail. 1 to 4 show an embodiment of a magnetic tape cassette according to the present invention. The magnetic tape cassette of the present embodiment is a digital compact cassette (DCC) that records information such as music and images as digital signals, and as shown in the drawing, a cassette body 1 containing a magnetic tape or the like, A shutter 41 slidably attached to the cassette body 1 and a spring member (slider) interposed between the cassette body 1 and the shutter 41 and biasing the shutter 41 attached to the cassette body 1 in a certain direction. Spring) 3 and the like.

The cassette body 1 and the spring member 3 are the same as the conventional one shown in FIG. That is, the cassette body 1 has a substantially box-shaped appearance by a pair of upper and lower cassette halves 4 and 5 formed by injection molding of synthetic resin, and a pair of upper and lower cassette halves around which the magnetic tape 18 is wound. The reel hub 6 and the magnetic tape 18 wound around the reel hub 6 are accommodated therein with guide rollers and other parts for enabling stable running. The bottom wall portion 7 of the lower cassette half 4 serving as the bottom surface of the cassette has a hub hole 8 for inserting a tape drive shaft (hub drive shaft) in a digital recording / reproducing apparatus into the reel hub 6, and A spring mounting recess 9 for accommodating the spring member 3, a bottom guide groove 10 extending in the left-right direction of the cassette (direction of arrow J in FIG. 1) to restrict the sliding direction of the shutter 41, and on the bottom guide groove 10. A bottom engaging piece 11 and the like is provided which protrudes from the bottom of the shutter 41 and engages the edge of the shutter 41 inserted into the bottom guide groove 10.

On the other hand, as shown in FIGS. 3 and 4, on the upper wall portion 14 of the upper cassette half 5 which is the upper surface of the cassette, as in the case of the bottom guide groove 10, it extends in the left-right direction of the cassette. An upper guide groove 15 that restricts the sliding direction of the shutter 41 is formed. Further, as shown in FIG. 4, on the upper wall portion 14 of the upper cassette half 5, a transparent resin window 42 through which the amount of the magnetic tape wound around each reel hub 6 inside the cassette body 1 can be visually recognized. Is provided.

Further, as shown in FIGS. 1 and 4, the cassette front surface 17 provided by the front wall portions of the lower cassette half 4 and the upper cassette half 5 has a cassette body for reading and writing information. A magnetic head insertion window 19 into which a magnetic head 44 such as a digital recording / reproducing device is inserted, and a digital recording / reproducing device are provided on the front surface 17 of the cassette where the magnetic tape 18 accommodated in the cassette 1 runs. Pinch roller entrance pockets 20 and 21 into which pinch rollers 45 and 46 and capstans 48 and 49 are inserted are formed. Further, the range in which the shutter 41 of the lower cassette half 4 and the upper cassette half 5 slides is appropriate to the plate thickness of the shutter 41 so that the cassette surface including the shutter 41 becomes flat. There is a step (dent).

The shutter 41 prevents dust and the like from entering the cassette body 1 through the opening of the cassette body 1 at the time of storage, and the magnetic head insertion window 19 and the magnetic head insertion window 19 at the time of handling. This is for preventing the magnetic tape 18 exposed in the pinch roller entry pocket 20 from being inadvertently touched by a finger or the like, so that the magnetic tape 18 is not damaged. As shown in FIG. A bottom wall portion 50 for covering the hub hole 8 on the bottom surface of the cassette, and a front wall portion 51 and an upper wall portion 52 for covering the magnetic head insertion window 19 and the pinch roller entry pockets 20 and 21 on the front surface of the cassette. With the configuration, it is an integrated structure made by bending a thin metal plate.

As shown in FIG. 3, at the rear end of the bottom wall portion 50, the bottom guide groove 10 and the bottom engaging piece 11 are extended in the horizontal direction along the surface of the bottom wall portion 7. A horizontal flange portion 54 is provided between the upper wall portion 52 and a rear end of the upper wall portion 52. The horizontal flange portion 54 extends in a vertical direction perpendicular to the surface of the upper wall portion 14 and is inserted into the upper guide groove 15. A vertical flange portion 55 is provided. Further, in the bottom wall portion 50, a shaft insertion opening 57 corresponding to the hub hole 8, a spring engaging piece 58 for receiving a biasing force from the spring member 3, and a shutter closing for closing the hub hole 8. Hub rotation preventing means 59 for preventing rotation of the reel hub 6 in the cassette body 1 when in the state is provided, and a head insertion opening 61 corresponding to the magnetic head insertion window 19 is provided on the front wall portion 51 side. And a pinch roller opening 62 corresponding to the pinch roller entry pocket 21.

The shutter 41 is mounted on the cassette body 1 by elastically deforming a part of the bottom wall portion 50, the upper wall portion 52 and the like, and the shutter 41 includes the horizontal flange portion 54 and the vertical flange portion 55. The engagement with the predetermined grooves 10 and 15 prevents the cassette body 1 from falling off.

FIG. 2 is a bottom view of the magnetic tape cassette with the shutter 41 attached to the cassette body 1. As shown in the figure, when one end of the spring member 3 is engaged with the spring engaging piece 58 and is not attached to a digital recording / playback device or the like, it is urged in the direction of arrow K by the urging force of the spring member 3. The shutter 41 is in a shutter closed state in which the opening on the cassette body 1 is closed. The digital recording / playback apparatus or the like is equipped with a shutter opening device for moving the mounted shutter 41 in the direction of the arrow L against the urging force of the spring member 3, and is used as a digital recording / playback apparatus or the like. When the shutter 41 is mounted, the shutter 41 is moved so that the shaft insertion opening 57 of the shutter 41 is aligned with the hub hole 8 of the cassette body 1, and the magnetic head insertion window 19 on the cassette body 1 and the like. The shutters are opened with the pinch roller advancing pockets 20 and 21 opened. FIG. 4 is a top view of the magnetic tape cassette showing the position of the back shutter 41 when the shutter is open.

The hub rotation preventing means 59 is an integrally molded product made of synthetic resin, and as shown in FIG. 5, it is perpendicular to the substrate portion 63 that abuts against the back surface of the bottom wall portion 50 of the shutter 41. A main body block 65 having a side portion having a pillar portion 64 that stands up and projects into the hub hole 8 and which can be said to be substantially L-shaped, and a rotation prevention of the bottom wall portion 50 that is erected vertically to the substrate portion 63. A rod-shaped portion 67 that is inserted into the means mounting hole 66, and a pair of hub locking protrusions 68 that project from the tip of the pillar portion 64 in the direction orthogonal to the pillar portion 64 (the slide direction of the shutter 41). It is equipped with it. The rod-shaped portion 67 is in the shape of, for example, a quadrangular prism whose cross section is square, and the tip end thereof is sharpened in a chevron shape.

As shown in FIG. 6A, the hub rotation preventing means 59 fits the rod-shaped portion 67 into the rotation preventing means mounting hole 66 of the bottom wall portion 50, and the upper surface of the bottom wall portion 50. As shown in FIG. 6B, the tip of the rod-shaped portion 67 protruding to the front is melted by the ultrasonic welding machine 70, and is welded to the shutter 41. The quadrangular cross-sectional shape of the rod-shaped portion 67 serves to prevent rotation of the hub rotation prevention means 59 fitted in the rotation-prevention means mounting hole 66, and the sharpening of the tip of the rod-shaped portion 67 is performed by ultrasonic waves. Useful for facilitating the welding process.

On the other hand, on the reel hub 6, as shown in FIG. 7, a rotation stopper is provided on an inner peripheral portion 38 on which a hub pawl 37 that engages with a tape drive shaft of a digital recording / reproducing apparatus or the like is projected. A gear portion 40 having internal teeth 39 is provided concentrically with the inner peripheral portion 38. Then, when the shutter 41 is in the position of the shutter open state shown by the symbol N in the drawing, the hub locking projection 68 is located in the region between the rotation preventing inner tooth 39 and the hub pawl 37. When the reel hub 6 is retracted and held in a rotatable state, the hub locking protrusion 68 causes the hub locking protrusion 68 to rotate when the shutter is in the shutter closed position indicated by the symbol P. It rushes in between 39 to prevent the reel hub 6 from rotating. As described above, the hub rotation preventing means 59 is integrally formed of synthetic resin as a separate body from the shutter 41 formed by subjecting a thin metal plate to a series of sheet metal working such as punching and bending. When formed by, the mounting accuracy of the hub locking projection 68 depends on the punching accuracy of the rotation preventing means mounting hole 66 on the shutter 41 and the molding accuracy of the hub rotation preventing means 59 by injection molding or the like. Although it depends on each of them, it is relatively easy to improve the accuracy.

Therefore, the hub locking protrusion 68 can be mounted on the shutter 41 with high accuracy, and the number of bends required for molding the shutter 41 can be reduced. It is possible to prevent inconveniences such as a decrease in product yield due to a decrease in dimensional accuracy and a decrease in the rotation blocking function of the reel hub 6, and at the same time, a reduction in production cost.

Further, unlike the case where the hub locking protrusion 68 made of synthetic resin is formed by bending a thin plate, the width of the protrusion protruding between the adjacent detent internal teeth 39 of the reel hub 6 Since the dimensions, the protrusion height, etc. can be freely set, the reel hub 6 can be positioned and fixed more accurately, and the reel hub 6 can be prevented from rattling when the shutter is closed. Become. Further, since the hub locking projection 68 is made of a resin having the same hardness as the anti-rotation internal teeth 39, it is possible to prevent the anti-rotation internal teeth 39 from being scraped when the hub locking projection 68 is engaged. Therefore, it is possible to prevent the magnetic tape and the like from being damaged by shavings.

In the above-described embodiment, the hub rotation preventing means 59 has an integrated structure made of synthetic resin. However, it is possible to improve accuracy by reducing the number of bending of a thin plate made of metal or prevent the generation of shavings. This can also be achieved by making only the hub locking protrusion that engages with the rotation preventing inner teeth 39 from synthetic resin. 8 to 12 show the configuration of the hub rotation preventing means in another embodiment of the present invention, which is improved from this point of view.

In the example shown in FIG. 8, the hub rotation preventing means 72 for preventing the rotation of the reel hub is provided with a pair of support pieces 73 standing on the bottom wall portion 50 of the shutter 41 and the support pieces 73. And a main body block 74 which is an integrally molded product of synthetic resin. Since the above-mentioned strut piece 73 is formed by bending a part of the bottom wall portion 50 of the shutter 41, the tip end portion of the strut piece 73 has the main body block as shown in FIG. 9A. The height is larger than 74. Further, the main body block 74 has a pair of groove portions 76 into which the pair of column pieces 73 are fitted, and a pair of hub locking protrusions 77 protruding in a slide direction orthogonal to the column pieces 73. Has been done.

As shown in FIG. 9A, the main body block 74 is positioned on the bottom wall portion 50 by inserting the support column piece 73 into the groove portion 76, and then, in FIG. 9B. As shown in FIG. 5, the tip end portion of the pillar piece 73 protruding from the groove portion 76 is fixed to the bottom wall portion 50 by caulking using an appropriate processing means such as bending or crushing. Even with such a configuration, although the pillar piece 73 is bent and processed with respect to the bottom wall portion 50, since the hub locking projection 77 is not formed by bending, it is fine. It is possible to obtain the same effect as that of the above-described embodiment without requiring a special bending process.

In the example shown in FIGS. 10 to 12, the hub rotation preventing means 82 for preventing the rotation of the reel hub includes a piece of support piece 83 standing on the bottom wall portion 50 of the shutter 41 and the support piece. It is composed of a pair of hub locking projections 84 mounted on 83. The pillar piece 83 is obtained by bending a pillar piece portion 85, which is punched out continuously from a part of the bottom wall portion 50 of the shutter 41 as shown in FIG. 11, as shown in FIG. A pair of projection mounting holes 86 for mounting the hub locking projections 84 are provided.

On the other hand, the hub locking projection 84 is a synthetic resin molded product, and as shown in FIG. 12, a wedge-shaped locking portion 88 for engaging with the rotation preventing inner teeth 39 of the reel hub 6, It is configured to include an insertion shaft portion 89 protruding from the base end side of the locking portion 88 and inserted into the protrusion mounting hole 86. The insertion shaft portion 89 has a cross-sectional shape of a square shape together with the above-mentioned projection mounting hole 86, and the tip end thereof is sharpened in a chevron shape. The hub locking protrusions 84 are formed by inserting the insertion shaft portion 89 into the protrusion mounting hole 86, and then ultrasonically welding the tip end portion of the insertion shaft portion 89 protruding to the back surface side of the pillar piece 83. It is fixed to the column piece 83.

Even with such a configuration, the pillar pieces 83 can be obtained by bending the bottom wall portion 50 once, and the number of bending times is reduced as compared with the conventional structure shown in FIG. Therefore, the same effect as that of the above-described embodiment can be obtained. The shape and the number of equipments of the hub locking projections protrudingly provided on the shutter 41 are not limited to the above-described embodiment. In the above-described embodiment, the hub locking protrusions are provided as a pair of equipments, but it is naturally possible to provide one or three or more equipments.

[0035]

[Effect of device]

 As described above, according to the magnetic tape cassette of the present invention, the hub locking protrusion that engages with the rotation preventing inner teeth of the reel hub is formed by performing a series of sheet metal working such as punching and bending on a thin metal plate. Since the shutter is formed separately from the shutter by molding, it is formed by integral molding of synthetic resin.Therefore, the mounting accuracy of the hub locking protrusions depends on the punching accuracy of the mounting holes punched on the shutter and the injection accuracy. Although it depends on the molding accuracy of the hub locking projection by molding or the like, it is relatively easy to improve the accuracy of all of these. Therefore, it is possible to equip the shutter with the hub locking projection with high precision and reduce the number of bends required for molding the shutter, and therefore decrease the product yield due to the decrease in dimensional accuracy. It is possible to prevent inconveniences such as deterioration of the rotation preventing function of the reel hub and at the same time reduce production costs. In addition, unlike the case of forming a thin plate by bending, the hub locking protrusion made of synthetic resin allows you to freely set the width dimension of the protrusion protruding between the adjacent detent internal teeth of the reel hub. It is also possible to more accurately position and fix the reel hub, and to prevent rattling of the reel hub when the shutter is closed. Further, since the hub locking protrusion is made of resin having the same hardness as that of the rotation preventing inner teeth, the rotation preventing inner teeth are prevented from being scraped when the hub locking protrusion is engaged, and the It also becomes possible to avoid stains such as tapes.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention viewed from the bottom side.

FIG. 2 is a bottom view of one embodiment of the present invention.

3 is a cross-sectional view taken along the line I-I of FIG.

FIG. 4 is a top view of an embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a main part of a shutter according to an embodiment of the present invention.

FIG. 6 is an explanatory view of a mounting structure of a hub rotation preventing means according to an embodiment of the present invention.

FIG. 7 is an operation explanatory view of the hub rotation preventing means according to the embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of a main part of a shutter according to another embodiment of the present invention.

FIG. 9 is an explanatory view of a mounting structure of a hub rotation preventing means according to another embodiment of the present invention.

FIG. 10 is a structural explanatory view of a main part of a shutter according to still another embodiment of the present invention.

FIG. 11 is a plan view illustrating a main part of a shutter according to another embodiment of the present invention.

FIG. 12 is an explanatory view of a mounting structure of a main part of a shutter of another embodiment of the present invention.

FIG. 13 is a perspective view of a conventional magnetic tape cassette.

FIG. 14 is a bottom view of the magnetic tape cassette of FIG.

15 is a cross-sectional view taken along the line BB of FIG.

16 is an enlarged view of a C portion of FIG.

FIG. 17 is an operation explanatory view of a hub rotation preventing means of a conventional magnetic tape cassette.

[Explanation of symbols]

 1 Cassette Main Body 3 Spring Member 4 Lower Cassette Half 5 Upper Cassette Half 6 Reel Hub 8 Hub Hole 18 Magnetic Tape 19 Magnetic Head Insertion Window 20, 21 Pinch Roller Entry Pocket 39 Locking Inner Teeth 40 Gear Part 41 Shutter 50 Bottom Wall Part 51 front wall part 54 horizontal flange part 55 vertical flange part 57 shaft insertion opening 59, 72, 82 hub rotation preventing means 68, 77, 84 hub locking protrusion

Claims (1)

[Scope of utility model registration request] 1. A pair of upper and lower cassette halves accommodate a pair of reel hubs around which a magnetic tape is wound inside a cassette body, and a magnetic head is inserted into the front surface of the cassette on which the magnetic tape wound around the reel hub runs. A magnetic tape cassette provided with a window and a pocket for entering a pinch roller, slidably attached to the cassette body, and provided with a shutter made of a thin plate member for opening and closing a hub hole of the cassette body and an opening portion of the front surface of the cassette. In the shutter, the hub rotation for preventing rotation of the reel hub by a hub locking protrusion that engages with internal rotation preventing teeth formed on the inner peripheral side of the reel hub when the shutter is closed to close the hub hole. The prevention means is provided so as to project inward of the cassette, and the hub rotation prevention means is
A magnetic tape cassette characterized in that at least the hub engaging projection that engages with the rotation preventing inner teeth is formed of a synthetic resin separate from other portions of the shutter.