A MAGNETIC TAPE CASSETTE

Abstract: A magnetic tape cassette comprises a cassette case (2), a pair of reels (3, 4), a reel lock member (10), first stopper parts (20, 21; 44, 45) and second stopper parts (17a, 18a). The reel lock member (10) is engageable with the flanges (5, 6) of the reels and includes a slide shell part (11), a pair of securing arms (14, 15; 42, 43) projected from the slide shell part and provided with leading ends (14a, 15a; 42a, 43a), and a spring member (24) urging the slide shell part to engage the securing with the flanges. The securing arms include hinge portions (12, 13; 40, 41) between the leading ends and the slide shell part. The first stopper parts (20, 21; 44, 45) restrict an amount of inward swing motion of the leading ends. The second stopper parts (17a, 18a) restrict an amount of the outward swing motion of the leading ends.

Description: SPECIFICATION A MAGNETIC TAPE CASSETTE [Technical Field] The present invention relates a magnetic tape cassette suitable for use as a video tape- cassette and, in more particular, a magnetic tape cassette improved in a reel lock member which can be engaged with the respective flanges of a pair of reels with a magnetic tape wound therearound so as to thereby prevent the rotation of the reels. [Background Art] Conventionally, there have been known various types of magnetic tape cassettes. For example, in a video tape cassette 60 having such an internal structure as shown in Fig. 9, a pair of reels 62 and 63 are rotatably disposed within a lower cassette half 61 (in Fig. 9, there is shown a state of the video tape cassette 60 with an upper cassette half thereof removed therefrom) , while a magnetic tape 65 is wound around the two reels 62 and 63. The magnetic tape 65 is guided by two left and right tape guides 66 and 67 respectively disposed in the front portion of the video tape cassette 60 (in Fig. 9, on the upper side thereof) and is allowed to pass through an opening 68 formed on the front surface side of the lower cassette half 61. On the respective peripheral edges of the lower flanges 70 and 71 of the two reels 62 and 63, there are formed engaging teeth 70a and 71a in such a manner that they respectively extend along the whole areas of the peripheral edges. On the other hand, in order to prevent the magnetic tape 65 from being loosened when the video tape cassette 60 is not loaded into a video deck (not shown) , that is, when the video tape cassette 60 is kept or carried, there is " disposed a reel lock member 75. The reel lock member 75 is used to prevent the rotation of the two reels 62 and 63 in a substantially triangular-shaped space 73 which is formed in the rear portion of the video tape cassette 60 and between the two reels 62 and 63. Between the rear plate portion 6,1a of the lower cassette half 61 and the reels 62, 63, there are provided two partition walls 76 and 77 each of which has a substantially triangular shape. The straight line portions 76a and 77a of these two partition walls 76 and 77 are disposed opposed to each other, while the reel lock member 75 is slidably inserted between the two straight line portions 76a and 77a. The reel lock member 75 is energized forwardly due to the energizing force of a coiled torsion spring 81 supported properly by a support shaft 80 which is provided on and projected from the bottom wall surface of the lower cassette half 61. The coiled torsion spring 81 is structured such that a coiled portion thereof allows the support shaft 80 to extend therethrough. One end of the coiled torsion spring 81 can be engaged with a portion of the partition wall 76 and the other end thereof can be engaged with the rear surface of the reel lock member 75. In the bottom wall surface of the reel lock member 75, an insertion hole 82 is formed, and into the insertion hole 82, a lock removal pin (not shown) provided in the video deck can be inserted. Then, in the bottom wall of the lower cassette half 61, an opening (not shown) is formed and corresponds to the insertion hole 82 of the reel lock member 75. The reel lock member 75 includes a rectangular slide shell portion 83 which is formed of resin having proper elasticity. The rectangular slide shell portion 83 has a relatively wide bottom surface area so as to allow the same to slide in a well stabilized manner. On the front end face of the slide shell portion 83, there are provided integrally therewith two securing arms 84 and 85 which can be respectively engaged with the engaging teeth 70a and 71a formed in the lower flanges 70 and 71. However, in the above-mentioned magnetic tape cassette 60, for example, when it is dropped down, it is possible that the two reels 62 and 63 are moved due to the impact of such drop so as to thereby press against the pair of securing arms 84 and 85. Then, such pressing force or pressure is transmitted to the slide shell portion 83, and. By the transmitted pressing force or pressure, the slide shell portion 83 is moved up to a lock removing position against the energizing force of the coiled torsion spring 81, so that the securing arms 84 and 85 can be removed or separated from the engaging teeth 70a and 71a of the reels 62 and 63. As a result of this, the two reels 62 and 63 can be rotated to thereby loosen the magnetic tape 65 wound around these reels 62 and 63. [Disclosure of the Invention] The present invention aims at eliminating the above- mentioned drawbacks found in the conventional magnetic tape cassette. Accordingly, it is an object of the invention to provide a magnetic tape cassette which can prevent a magnetic tape from being loosened when it is dropped down. The above object, according to the invention, can be attained by a magnetic tape cassette comprising: a cassette case; a pair of reels each having a flange and rotatably mounted within the cassette case with a magnetic tape wound around; a reel lock member engageable with the flanges of the reels so as to prevent the reels from rotating, wherein the reel lock member includes a slide shell part slidably disposed between the pair of reels, a pair of securing arms respectively projected from the slide shell part and provided with leading ends being engageable with the flanges, and a spring member urging the slide shell part in a direction where the securing arms are engaged with the flanges, and wherein the pair of securing arms respectively include hinge portions between the respective leading ends and the slide shell part; first stopper parts for restricting an amount of inward swing motion of the leading ends and for keeping the engagement between the leading ends with the flanges; and second stopper parts for restricting an amount of the outward swing motion of the leading ends and for keeping the engagement between the leading ends with the flanges. In the above-mentioned magnetic tape cassette, it is preferable that the first stopper parts are respectively provided at positions capable of contacting with a portion of the securing arm between the leading ends and the hinge portions . In the above-mentioned magnetic tape cassette, it is preferable that each of the first stopper parts comprises a pin which is erected from a bottom surface of the cassette case. In the above-mentioned magnetic tape cassette, it is preferable that each of the first stopper parts comprises a rib portion projected from the slide shell part. In the above-mentioned magnetic tape cassette, it is preferable that each of the first stopper parts comprises an expansion portion which is projectingly provided between the leading end and the hinge portion and is provided at a position capable of contacting with the slide shell part. In the above-mentioned magnetic tape cassette, it is preferable that the second stopper parts are respectively provided at positions capable of contacting with a portion of the securing arm between the leading ends and the hinge portions . In the above-mentioned magnetic tape cassette, it is preferable that each of the second stopper parts comprises a corner portion of arc-shaped partition wall which restricts movement of the reel in a radial direction thereof. In the above-mentioned magnetic tape cassette, it is preferable that each of the second stopper parts comprises a pin which is erected from a bottom surface of the cassette case. In the above-mentioned magnetic tape cassette, it is preferable that each of the second stopper parts comprises an expansion portion which is projectingly provided between the leading ends and hinge portions respectively and is provided at a position capable of contacting with a part of the cassette case. [Brief Description of Drawings] Fig. 1 is a plan view of the main portions of a first embodiment of a video tape cassette according to the invention; Fig. 2 is an explanatory view of a state in which the video tape cassette shown in Fig. 1 is dropped down in a parallel manner; Fig. 3 is an explanatory view of a state in which the video tape cassette shown in Fig. 1 is dropped down in an oblique manner; Fig. 4 is an explanatory view of a state of use of the video tape cassette shown in Fig. 1; Fig. 5 is a plan view of a modification of a reel lock member with respect to first stoppers; Fig. 6 is an enlarged perspective view of the main portions of a video tape cassette including a reel lock member according to another embodiment of the invention; Fig. 7 is a plan view of another modification of a reel lock member with respect to second stoppers; Fig. 8 is a plan view of further modification of a reel lock member with respect to second stoppers; and Fig. 9 is a schematic structure view of a conventional video tape cassette. [Best Mode for Carrying Out the Present Invention] The detail of an embodiment of a video tape cassette according to the present invention will be described below with reference to the accompanying drawings. As shown in Fig. 1, a video tape cassette 1 according to the present invention is structured such that, within a lower cassette half 2 forming a cassette case (Fig. 1 shows a state thereof in which an upper cassette half thereof is removed) , there are rotatably provided a pair of reels 3 and 4, while a magnetic tape (not shown) is wound around the reels 3 and 4. In the peripheral edges of lower flanges 5 and 6 which are respectively provided in the above two reels 3 and 4, there are formed engaging teeth 5a and 6a in such a manner that they extend over the whole periphery thereof. On the other hand, in order to prevent the magnetic tape from being loosened when the video tape cassette 1 is not loaded in a video deck (not shown) , in a substantially triangular-shaped space 8 formed between the two reels 3 and 4, there is disposed a reel lock member 10 which can be engaged with the engaging teeth 5a and 6a of the lower flanges 5 and 6 to thereby prevent the reels 3 and 4 being rotated. The operations of the other remaining parts than the reel lock member 10 are the same as in the conventional video tape cassette 50 which has been previously described and thus the description thereof is omitted here. The reel lock member 10, which is formed of synthetic resin or the like, includes a slide shell part 11 slidably interposed between the pair of reels 3 and 4. The reel lock member 10 also includes a pair of securing arms 14 and 15 which are respectively provided on and projected from the slide shell part 11 in such a manner that they can be engaged with the engaging teeth 5a and 6a of the lower flanges 5 and 6, while the slide shell part 11 is energized by a coiled compression spring 24 used as a spring member to allow the securing arms 14 and 15 to slide in a direction where they can be engaged with the lower flanges 5 and 6 respectively. In the lower surface of the slide shell part 11, there is formed a removing pin insertion portion 11a, and in the rear of the removing pin insertion portion 11a, there is formed a guide portion lib. As will be discussed later, when the video tape cassette 1 is loaded into the video deck, the slide shell part 11 is pushed by a lock removing pin (not shown) provided in the video deck and is thus moved backward, thereby being able to remove the locked conditions of the two reels 3 and 4. The slide shell part 11 is slidably fitted into guide members 27 and 28 which are respectively provided in the lower cassette half 2. Then, the lower end face of the guide portion lib is slidably fitted into guide rails 29 and 30 which is provided in the lower cassette half 2, whereby the slide shell part 11 is allowed to slide linearly. In the securing arms 14 and 15, which are respectively provided on and projected from the two side surfaces of the slide shell part 11, there are formed thin hinge portions 12 and 13. The thin hinge portions 12 and 13 are used to connect the leading end engaging portions 14a and 15a thereof to the slide shell part 11 in a slidable manner. That is, if the securing arms 14 and 15 receives a pressure of a given level or higher from the respective reels 3 and 4 through the leading end engaging portions 14a and 15a thereof, then they can be swung outwardly (in a direction of an arrow A in Fig. 1) or inwardly (in a direction of an arrow B in Fig. 1) around the hinge portions 12 and 13 respectively. In addition, in order that the leading end engaging portions 14a and 15a thereof can be surely engaged with the engaging teeth 5a and 6a of the reels 3 and 4, the securing arms 14 and 15 are respectively curved toward the center directions of the reels 3 and 4 at a proper angle. On the bottom wall surface of the lower half cassette 2, there are projectingly provided arc-shaped partition walls 17 and 18 for restricting the movements of the reels 3 and 4 in the radial directions thereof. The partition walls 17 and 18 respectively include corner portions 17a and 18a which are situated near the outside portions of the securing arms 14 and 15. The corner portions 17a and 18a are structured such that, if they are respectively contacted with the securing arms 14 and 15 between the leading end engaging portions 14a, 15a thereof and hinge portions 12, 13 thereof, then they can restrict the amounts of the swing motions of the leading end engaging portions 14a and 15a in the outward direction (namely, in the direction of the arrow A in Fig. 1) . That is,' the corner portions 17a and 18a of the partition walls 17 and 18 are respectively used as second stopper parts. On the portions of the bottom wall surface of the lower half cassette 2 that are situated near the inside portions of the securing arms 14 and 15, there are projectingly provided two stopper pins .20 and 21. In particular, the stopper pins 20 and 21 are structured such that, if they are respectively contacted with the securing arms 14 and 15 between the leading end engaging portions 14a, 15a and the hinge portions 12, 13, then they can restrict the amounts of the swing motions of the leading end engaging portions 14a and 15a in the inward direction (namely, in the direction of the arrow B in Fig. 1) . That is, the stopper pins 20 and 21 are respectively used as first stopper parts. According to the present embodiment, the second stopper parts, which restrict the amounts of the swing motions of the leading end engaging portions 14a and 15a in the outward direction (that is, in the direction of the arrow A in Fig. 1), is structured by extending the corner portions 17a and 18a of the partition walls 17 and 18 up to the neighboring portions of the outside portions of the securing arms 14 and 15. However, this is not limitative but, instead of this, as shown in Fig. 7, stopper pins or ribs independent of the partition walls 17 and 18 may be provided in the lower cassette half 2, as in the stopper pins 20 and 21. In the lower cassette half 2, there is provided a substantially triangular-shaped stopper 32 which is used to restrict the amount of advancement of the slide shell part 11. In particular, if the slide shell part 11 is contacted with the stopper 32, then the securing arms 14 and 15 are positively engaged with the securing teeth 5a and 6a of the reels 3 and 4 to thereby be sure to prevent the reels 3 and 4 against rotation. In the lower cassette half 2, in more particular, in the rear of the stopper 32, there is formed a pin insertion hole 2a which is so situated as to correspond to the removing pin insertion portion 11a of the slide shell part 11 and also into which the lock removing pin of the video deck can be inserted. Next, description will be given below of the operation of the reel lock member 10 of the video tape cassette 1 according to the invention with reference to Figs. 1 to 4. Fig. 1 shows a state in which the video tape cassette 1 is not loaded in the video deck. If the reel lock member 10 is energized by the coiled compression spring 24 in the direction where it can be engaged with the lower flanges 5 and 6, then the leading end engaging portions 14a and 15a of the securing arms 14 and 15 are respectively engaged with the engaging teeth 5a and 6a of the reels 3 and 4 to thereby prevent rotation of the reels 3 and 4. In this operation, the leading end engaging portions 14a and 15a are respectively kept from swinging around the hinge portions 12 and 13, so that they can be positively engaged with the engaging teeth 5a and 6a of the reels 3 and 4. Now, Fig. 2 shows a state in which the video tape cassette 1 is dropped down in a parallel manner. If the reels 3 and 4 are moved in a direction of an arrow C shown in Fig. 2 within the cassette case due to the impact of such drop, then a pressure of a certain level or higher is applied from the reels 3 and 4 onto the securing arms 14 and 15. Owing to the pressure, not only the slide shell part 11 is slid slightly and instantaneously in a lock removing direction (that is, in a direction of an arrow D in Fig. 2) but also the leading end engaging portions 14a and 15a of the securing arms 14 and 15 are respectively swung around the hinge portions 12 and 13 outwardly (that is, in a direction of an arrow A in Fig. 2) . If the leading end engaging portions 14a and 15a of the securing arms 14 and 15 are respectively swung by a certain amount while they are in engagement with the engaging teeth 5a and 6a of the reels 3 and 4, then the securing arms 14 and 15 are respectively contacted with the corner portions 17a and 18a of the partition walls 17 and 18, which serve as the second stopper parts provided in the lower cassette half 2. As a result, the swing motions of the securing arms 14 and 15 can be restricted. That is, the corner portions 17a and 18a are able to receive the pressures on the reels 3 and 4 applied to the leading end engaging portions 14a and 15a of the securing arms 14 and 15. Therefore, the corner portions 17a and 18a are able to prevent the pressures on the reels 3 and 4 from being transmitted directly to the slide shell part 11. Owing to this, the reel lock member 10 can control or minimize the amount of the sliding motion of the slide shell part 11 when the slide shell part 11 slides in the lock removing direction against the energizing force of the coiled compression spring 24, thereby being able to keep the engagement of the pair of arms 14 and 15 with their associated engaging teeth 5a and 6a. Next, Fig. 3 shows a state in which the video tape cassette 1 is dropped down in an oblique manner. For example, if the impact of such drop moves the reel 4 within the cassette case in a direction which the reel 4 is opposed to the securing arm 15 (in Fig. 3, in a direction of an arrow E) , then a pressure of a certain level or higher is applied from the reel 4 onto the securing arm 15. As a result, not only the slide shell part 11 is caused to slide in the lock removing direction (in Fig. 3, in a direction of an arrow D) instantaneously and slightly, but also the leading end engaging portion 15a of the securing arm 15 is swung inwardly (in Fig. 3, in a direction of an arrow B) with the hinge portion 13 as a fulcrum thereof. If the leading end engaging portion 15a of the securing arm 15 is swung by a certain amount while it is in engagement with the securing teeth 6a of the reel 4, then the securing arm 15 is contacted with the stopper pin 21 which serves as the first stopper part provided in the 2. Therefore, the swing motion of the securing arm 15 can be restricted. That is, the stopper pin 21 is able to receive the pressure on the reel 4 applied through the leading end engaging portion 15a of the securing arm 15. The stopper pin 21 is thereby be able to prevent the pressure on the reel 4 from being transmitted directly to the slide shell part 11. Owing to this, the reel lock member 10 can prevent the amount of the sliding motion of the slide shell part 11 in the minimum level when the slide shell part 11 is slid in the lock removing direction against the energizing force of the coiled compression spring 24. Therefore, the reel lock member 10 keeps the engagement of the pair of securing arms 14 and 15 with their associated engaging teeth 5a and 6a. In addition, when the reel 3 is moved within the cassette case in a direction where the reel 3 is opposed to the securing arm 14 due to the impact of the above-mentioned drop of the video tape cassette 1, the swing motion of the securing arm 14 is restricted by the stopper pin 20, which, similarly to the above-mentioned case, makes it possible to prevent the pressure on the reel 3 from being transmitted directly to the slide shell part 11. Therefore, with use of the above-mentioned video tape cassette 1, even when it is dropped down, the engagement between the securing arms 14, 15 and the engaging teeth 5a, 6a of the reels 3 and 4 can be surely kept on, thereby being able to prevent the loosened winding of the, agnetic tape. After the impact caused by the drop of the video tape cassette 1 is removed, the reel lock member 10 is allowed to return to the state shown in Fig. 1 due to the elastically restitutive forces of the hinge portions 12 and 13. Now, Fig. 4 shows a state of use in which the video tape cassette 1 is mounted into the video deck. As shown in Fig. 4, if the slide shell part 11 is pushed by the lock removing pin (not shown) of the video deck and is thereby retreated in a direction of an arrow D in Fig. 4, then the reel lock member 10 is slid up to the lock removing position. During the above-described slide, the securing arms 14 and 15 are not contacted with the corner portions 17a and 18a, thereby being able to remove the securing arms 14 and 15 from the engaging teeth 5a, 6a of the reels 3 and 4 respectively. As a result of this, the reels 3 and 4 are free to rotate, so they can be driven and rotated by a rotation drive shaft (not shown) provided in the video deck. In the above embodiment, the corner portions 17a and 18a of the partition walls 17 and 18 as well as the stopper pins 20 and 21 are respectively disposed near the inside and outside portions of the securing arms 14 and 15, thereby forming the first and second stopper parts for restricting the amounts of the swing motions of the leading end engaging portions 14a and 15a of the securing arms 14 and 15. The embodiments of the present invention is not limited to the above embodiment, and another embodiment is shown in Fig. 5. As shown in Fig. 5, a reel lock member 50 has hinge portions 40 and 41, securing arms 42 and 43, leading end engaging portions 42a, 43a and expansion portions 44 and 45. In the reel lock member 50, the expansion portions 44 and 45 are projectingly provided between the leading end engaging portions 42a, 43a of the inside surfaces of .securing arms 42, 43 and the hinge portions 40, 41 thereof The expansion portions 44 and 45 is used as first stopper parts, that is, they may be respectively contacted with the lower cassette half or slide shell part so as to be able to restrict the amounts of the swing motions of the leading end engaging portions 42a and 43a in the inward direction thereof. As shown in Fig. 8, when expansion portions as the expansion portions 144 and 145 are projectingly provided on the outside surfaces of the securing arms as second stopper parts, similarly to the above case, the amounts of the swing motions of the leading end engaging portions in the outward direction thereof can be restricted. That is, if the shapes of the expansion portions to be provided on and projected from the inside and outside surfaces of the securing arms are set properly, a magnetic tape cassette according to the present invention can be structured simply by replacing only the reel lock member. This is because the first and second stopper parts need not be separately provided and formed in the form of stopper pins in the lower cassette half and the design of the partition walls needs not be changed. In addition, the expansion portions 44 and 45 respectively formed in the inside portions of the securing arms 14 and 15, as restrict projections, restrict the amounts of the inward falling motion of the securing arms 14 and 15, thereby being able to prevent the hinge portions 40 and 41 from being curved inwardly to an excessive extent. Owing to this, when the reel lock member 50 is molded or the components of the magnetic tape cassette are collected together, even if an excessive inward pressure is applied onto the securing arms 14 and 15, there is no possibility that the hinge portions 40 and 41 can be curved excessively and can be thereby deformed permanently. Now, Fig. 6 is an enlarged perspective view of the main portions of another embodiment of a video tape cassette including a reel lock member 51 according to the present invention. In this embodiment, the components except a pair of restrict ribs 52 provided in the reel lock member 51 are similar in structure to the components of the previously described video tape cassette 1 shown in Fig. 1. Therefore, they are given the same designations and the detailed description thereof is omitted here. The reel lock member 51, as shown in Fig. 6, includes a slide shell part 11 slidably interposed between a pair of reels 3 and 4 (not shown in Fig. 6) , and a pair of securing arms 14 and 15 which are projectingly provided on the slide shell part 11 in such a manner that they can be engaged with engaging teeth 5a and 6a formed in the respective lower flanges 5 and 6 of the pair of reels 3 and 4. Further, on the two side surfaces of the slide shell part 11, there are projectingly provided a pair of restrict ribs 52 serving as restrict projections which are able to restrict the amounts of the inward falling motions of the securing arms 14 and 15 when they are contacted respectively with the securing arms 14 and 15 between the leading end engaging portions 14a, 15a and hinge portions 12, 13. The restrict ribs 52 are set to have such a proper projecting height that, within a range where the securing arms 14 and 15 are used in their normal states, allows the securing arms 14 and 15 to swing normally so that the securing arms 14 and 15 can be contacted with the stopper pins 20 and 21 smoothly. In order to prevent the restrict ribs 52 from interfering with the stopper pins 20 and 21 when the slide shell part 11 is pushed by the lock removing pin (not shown) of the video deck and is thereby moved back to the lock removing position, the restrict ribs 52 are provided at and projected from a position having a clearance X in the cassette case thickness direction with respect to the leading end portions of the stopper pins 20 and 21. That is, the restrict ribs 52, which are respectively provided on the two side surfaces of the slide shell part 11, restrict the amounts of the inward falling motions of the securing arms 14 and 15 to thereby be able to prevent the hinge portions 12 and 13 from being curved inwardly to an excessive extent. Owing to this, when the reel lock member 51 is molded or the components of the magnetic tape cassette are collected together, even if an excessive inward pressure is applied onto the securing arms 14 and 15, there is no possibility that the hinge portions 12 and 13 can be curved excessively and can be thereby deformed permanently. As an alternative, the restrict ribs 52 may be used as first stopper parts, that is, they may be contacted with the securing arms 14 and 15 to thereby be able to prevent the amounts of the inward swing motions of the leading end engaging portions 14a and 15a. In this case, the stopper pins 20 and 21, which are provided on and projected from the bottom wall surface of the lower half cassette 2, can be omitted. Further, the magnetic tape cassette according to the present invention is not limited to the structures of the reel rock member and stopper parts employed in the above- mentioned embodiments but, of course, there can be employed other various structures. For example, the shapes of the slide shell part and securing arms, the shapes of the hinge portions and the shapes of the stopper parts can be changed or modified properly according to the kinds of magnetic tape cassettes used without departing from the subject matter of the invention. [Industrial Applicability] As has been described heretofore, according to the magnetic tape cassette of the present invention, when the magnetic tape cassette is dropped down, if the reels are respectively moved within the cassette case due to the impact of such drop and the securing arms of the reel lock member are respectively pushed in the lock removing direction, then the leading end engaging portions of the securing arms are caused to swing outwardly or inwardly due to such pressure. If the leading end engaging portions of the securing arms are swung by a certain amount, then the securing arms are respectively contacted with the first or second stopper parts which are provided in the cassette half. That is, the first and second stopper parts are able to receive the pressures of the respective reels applied through the leading end engaging portions of the securing arms and thus they are able to prevent the pressures of the respective reels from being transmitted directly to the slide shell part. Owing to this, the reel lock member not only can restrict or minimize the sliding amount of the slide shell part in the lock removing direction against the energizing force of the spring member, but also can keep the engagement of the pair of securing arms with their respective flanges. Therefore, according to the video tape cassettes by the present invention, even if they are dropped down, the engagement between the securing arms and the engaging teeth of the reels can be kept positively, which in turn can prevent the magnetic tape from being loosened. The present invention is based on Japanese Patent Application No. Hei . 9-310600 and 10-36168, which is incorporated herein by reference. While only certain embodiments of the invention have been specifically describe herein, it will be apparent that numerous modification may be made thereto without departing from the spirit and scope of the invention.

Claims: CLAIMS 1. A magnetic tape cassette comprising: a cassette case (2); a pair of reels (3, 4) each having a flange (5,6) and rotatably mounted within said cassette case with a magnetic tape wound around; a reel lock member (10) engageable with said flanges of said reels so as to prevent said reels from rotating, wherein said reel lock member includes a slide shell part (11) slidably disposed between said pair of reels, a pair of securing arms (14,15; 42,43) respectively projected from said slide shell part and provided with leading ends (14a, 15a; 42a, 43a) being engageable with said flanges, and a spring member (24) urging said slide shell part in a direction where said securing arms are engaged with said flanges, and wherein said pair of securing arms respectively include hinge portions (12,13; 40,41) between the respective leading ends and said slide shell part; first stopper parts (20,21; 44,45) for restricting an amount of inward swing motion of said leading ends and for keeping the engagement between said leading ends with said flanges; and second stopper parts (17a, 18a) for restricting an amount of the outward swing motion of said leading ends and for keeping the engagement between said leading ends with said flanges. 2. The magnetic tape cassette according to claim 1, wherein said first stopper parts are respectively provided at positions capable of contacting with a portion of said securing arm between said leading ends and said hinge portions . 3. The magnetic tape cassette according to claim 2, wherein each of said first stopper parts comprises a pin (20, 21) which is erected from a bottom surface of said cassette case. 4. The magnetic tape cassette according to claim 2, wherein each of said first stopper parts comprises a rib portion (52) projected from said slide shell part (11) . 5. The magnetic tape cassette according to claim 1, wherein each of said first stopper parts comprises an expansion portion (44, 45) which is projectingly provided between said leading end (42a, 43a) and said hinge portion (40, 41) and is provided at a position capable of contacting with said slide shell part (150) . 6. The magnetic tape cassette according to claim 1, wherein said second stopper parts are respectively provided at positions capable of contacting with a portion of said securing arm between said leading ends and said hinge portions . 7. The magnetic tape cassette according to claim 6, wherein each of said second stopper parts comprises a corner portion (17a, 18a) of arc-shaped partition wall (17, 18) which restricts movement of said reel in a radial direction thereof . 8. The magnetic tape cassette according to claim 6, wherein each of said second stopper parts comprises a pin (244, 245) which is erected from a bottom surface of said cassette case. 9. The magnetic tape cassette according to claim 5, wherein each of said second stopper parts comprises an expansion portion (144,145) which is projectingly provided between the leading ends (142a, 143a) and hinge portions (140,141) respectively and is provided at a position capable of contacting with a part (76, 77) of said cassette case (2) .

Inventors: ASHIKAWA TERUO, ASHIKAWA, TERUO
Applicants: ASHIKAWA TERUO, FUJI PHOTO FILM CO LTD, ASHIKAWA, TERUO, FUJI PHOTO FILM CO., LTD.
Application year: 1998
Main classification: G11B23
IPC codes: G11B23