Tape cassette

Abstract: In a tape cassette having a tape guide member in which a rotating member is freely rotatably mounted around a fixing member, steps are formed at the peripheral portions of bosses formed on the inner flat surfaces of the upper and lower half members between a first portion confronting the end surface of the fixing member and a second portion confronting the end surface of the rotating member so that the first portion is projected more inwardly of the frame body than said second portion.

Description: This invention relates to a tape cassette e.g. for a magnetic tape recorder (VTR), etc, and more particularly to a tape cassette having a tape guide which is rotatable in accordance with the running of a tape, and in which a sliding or slipping motion of the tape to the tape guide can be suppressed to the minimum. In Figure 6 of the accompanying drawings is shown an example of a VTR tape cassette 20 of VHS type which is so designed that a magnetic tape T fed out from the side of a supply reel 21 runs along the front face of the tape cassette 20 so as to be slidably contacted with a tape guide member 22 and a guide roller 23, and then wound up by a wind-up reel 24. The tape guide member 22 with which the magnetic tape T is slidably contacted so that its tape running position (passageway) is guided, is designed in a cylindrical form as shown in a cross-sectional view of Figure 7(a). Bosses 25 and 26 are respectively formed at fixing positions of the tape guide member 22 on an upper half 20a and a lower half 20b which constitute a frame body of the tape cassette 20. One of the bosses, for example, the boss 26 is particularly formed with a predetermined number of press-fitting ribs 26a on the peripheral surface thereof. The tape guide member 22 is secured to the tape cassette 20 by engagedly inserting the bosses 25 and 26 into a cylindrical hole 22h of the tape guide member 22 from the upper and lower sides thereof as shown in Fig. 7(c) when the upper half 20a and the lower half 20b are fabricated with each other. The tape guide member 22 is surely fixedly secured to the tape cassette 20, particularly by breaking the press fitting ribs 26a on the peripheral surface of the boss 26 when the boss 26 is inserted into the cylindrical hole 22h of the tape guide member. There may be used another fixing manner for the tape guide member 22 as shown in Figs. 8(a) to 8(c) in which no rib is provided to the bosses 25 and 26, and the bosses 25 and 26 are used merely as a positioning member for the tape guide member 22. In this case, at the time when the upper and lower halves 20a and 20b are fixedly engaged with each other through vis fixation, the bosses 25 and 26 are engagedly inserted into the hole 22h, and the tape guide member 22 is fixedly sandwiched in a direction as indicated by an arrow A by the upper and lower halves 20a and 20b. However, in comparison with the fixing manner of the tape guide member 22 as described above in which the tape guide member 22 is fixedly secured in the frame body and the magnetic tape T is slidably contacted with the fixed tape guide member 22 so that the tape running position is guided. the following manner is more preferable in improvement of durability of the magnetic tape T and the tape guide member. That is, the tape guide member 22 is so designed as to be freely rotatable and thus a sliding or slipping motion is suppressed between the magnetic tape T and the tape guide member 22. In view of the above, there has been proposed a tape guide member 22 as shown in a cross sectional view of Fig. 9. The tape guide member 22 comprises an inner cylindrical fixing member 22a and an outer cylindrical rotatable member 22b which is freely rotatably mounted around the inner cylindrical fixing member 22a, and the tape guide member 22 is fixed in a space between the upper and lower halves by engagedly inserting the bosses 25 and 26 into the hole 22h of the inner cylindrical fixing member 22a. The rotating member 22b is provided with a projection 22b 1 on the inner peripheral surface thereof so as to extend in the peripheral direction thereof, and the fixing member 22a is provided with a groove 22a 1 on the outer peripheral surface thereof so as to extend in the peripheral direction thereof. The rotating member 22b1 is mounted around the fixing member 22a in a state where the projection 22b 1 is engaged with the groove 22a 1 , so that the rotating member 22b is prevented from falling off upwardly and downwardly from the fixing member 22a. Further, as shown in Fig. 9. the dimension L 1 of the frame body of the fixing member 22a in its thickness direction is set to be slightly longer than the dimension L 2 of the frame body of the rotating member 22b in its thickness direction, whereby the rotating member 22b is prevented from being slidably contacted with the inner flat surfaces of the upper and lower halves 20a and 20b at its rotation time to thereby prevent an excellent rotating operation of the rotating member 22b from being disturbed. However, the rotating member 22b is unintentionally moved in some degree in the thickness direction (as indicated by the arrow A) of the frame body because some degree of clearance or dimensional error occurring in a molding process exists at the setting portion of the fixing member 22b and the rotating member 22a, that is, between the projection 22b 1 and the groove 22a 1 . Due to such ricketiness of the rotating member 22b, the upper and lower end surfaces 22b 2 of the rotating member 22b is relatively easily contacted with the inner flat wall of the upper half 20a or lower half 20b, so that the smoothly rotating operation of the rotating member 22b is disturbed. In addition, the upper and lower halves 20a and 20b are frequently warped in some degree. In this case, as shown in Fig. 10, for example when the lower half 20b is warped in the inward direction of the frame body, the end surface 22b 2 of the rotating member 22b is more easily contacted with the lower half 20b, and thus the rotating operation of the rotating member 22b is disturbed. Further, there are some cases where recessed portions 20a 1 and 20b 1 having small steps are unintentionally formed on the periphery of the bosses 25 and 26 in accordance with the state of an insert die of a mold (Fig. 11). In this case, portions 20a 2 and 20b 2 which are located nearer to the inside of the frame body by one step than the recessed portions 20a 1 and 20b 1 are completely contacted with the end surface 22b 2 of the rotating member 22b, so that the rotating member is fixedly sandwiched by the portions 20a 2 and 20b 2 in a state where the rotation thereof is impossible. An object of this invention is to provide a tape cassette in which a sliding or slipping motion of a tape to a tape guide is suppressed to the minimum. In order to attain the above object, a tape cassette according to this invention is defined in claim 1. According to the tape cassette of this invention, on the upper and lower halves, the portion confronting the fixing member is so designed as to be projected to a position nearer to the inside of the frame body than the portion confronting the rotating member, and thus a surplus space is formed between the upper and lower end surfaces of the rotating member and the upper and lower halves, so that the rotating member is hardly contacted with the half members even when the rotating member mounted on the fixing member is moved in the thickness direction of the frame body or the half members are warped in some degree. The invention will be further described by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a cross-sectional view of the fixing state of the tape guide member for a tape cassette of an embodiment according to this invention; Figure 2 is an exploded perspective view of a tape guide member and a boss of this embodiment; Figure 3 is a perspective view of a frame body and a tape guide member of the tape cassette of this embodiment; Figure 4 is an exploded perspective view of a tape guide member and a boss of a modification of this embodiment; Fig. 5 is a cross-sectional view of the fixing state of a tape guide member of a tape cassette of another embodiment according to this invention; Fig. 6 is an explanatory diagram of a conventional tape cassette; Fig. 7 is an explanatory diagram of a conventional tape guide member; Fig. 8 is an explanatory diagram of another conventional tape guide member; Fig. 9 is an explanatory diagram of a conventional rotating type of tape guide member; Fig. 10 is an explanatory diagram of the conventional rotating type of tape guide member when the guide member is contacted with a lower half; and Fig. 11 is another explanatory diagram of the conventional rotating type of tape guide member when the guide member is contacted with halves thereof. A first embodiment of this invention will be hereunder described with reference to figs. 1 to 3. Fig. 3 is a perspective view of upper and lower halves and a tape guide member of a VTR tape cassette of VHS mode. A reference numeral 1 represents an upper half, a reference numeral 2 represents a lower half, a reference numeral 3 represents a tape guide member, and reference numerals 4 and 5 represent bosses which are projectingly provided at predetermined positions of the upper and lower halves 1 and 2, respectively. A reference numeral 6 represents a guide roller mechanism which is provided adjacent to the tape guide member 3. The tape cassette accommodates a magnetic tape in a frame body constructed by the upper and lower halves 1 and 2 (as not shown) in a state where the magnetic tape is wound up by a supply reel and a wind-up reel. The tape cassette is so designed that the magnetic tape drawn out of the supply reel is guided to the front face side of the frame body, then guided along its running position by the tape guide member 3 and the guide roller mechanism 6 , and then is fed to the wind-up reel side. Particularly in this embodiment, the tape guide member 3 comprises an inner cylindrical fixing member 3a, and an outer cylindrical rotating member 3b. The outer cylindrical rotating member 3b which will be contacted with the magnetic tape is freely rotatably disposed around the inner cylindrical fixing member 3a, to thereby promote the suppression of the sliding or slipping motion between the tape guide member 3 and the magnetic tape, and enable the magnetic tape and the tape guide member to be used for long time. Fig. 2 is an enlarged exploded perspective view of the mechanism of the tape guide member 3 of this embodiment. The fixing state of the tape guide member 3 by the bosses 4 and 5 is shown in a cross-sectional view of Fig. 1. As is apparent from these figures, the rotating member 3b is formed with a projection 3b 1 on the inner peripheral surface thereof in a peripheral direction thereof, and the fixing member 3b is formed with a groove 3a 1 on the peripheral surface thereof in peripheral direction thereof. When the fixing member 3a is inserted into a hole 3b n of the rotating member 3b, the projection 3b 1 is engaged with the groove 3a 1 to allow the rotating member 3b to be mounted on the fixing member 3a in such a manner that the rotating member 3b is rotatable relative to the fixing member 3a and is prevented from falling off from the fixing member 3a upwardly and downwardly. Further, the fixing member 3a is fixed between the upper and lower halves 2 and 3 by engaging the bosses 4 and 5 projected from the inner flat surfaces of the upper and lower halves 1 and 2 with the hole 3a n . In addition, the dimension L 1 of the fixing member 3a in the thickness direction of the frame body is set to be longer than the dimension L 2 of the rotating member 3b in the thickness direction of the frame body, so that the contact between the rotating member 3b and the inner flat surfaces of the upper and lower halves 1 and 2 is intentionally avoided. Still further, the peripheral portion of each of the bosses 4 and 5 is formed in a convex shape projecting in the inward direction of the frame body (these portions is hereinafter referred to as "convex portions" 6 and 7). As is apparent from Fig. 1, the convex portions 6 and 7 are formed on only those areas which confront the upper and lower end surfaces 3a 2 of the fixing member 3a, that is, the convex portions 6 and 7 are formed on the inner flat surfaces of the upper and lower halves 1 and 2 in such a manner that flat portions 6a and 7a of the convex portions 6 and 7 are confronted to the upper and lower end surfaces 3a 2 of the fixing member 3a, but not to the upper and lower end surfaces 3b 2 of the rotating member 3b. Therefore, the upper and lower end surfaces 3b 2 of the rotating member 3b are confronted to those portions on the inner flat surfaces of the upper and lower halves 1 and 2, which are adjacent to the flat portions 6a and 7a of the convex portions 6 and 7 and located at lower positions than the flat portions 6a and 7a by one step. With the construction as described above, a space between the end surfaces 3b 2 of the rotating member 3b and the upper and lower halves 1 and 2 is provided with sufficient gap interval, so that the rotating member 3b is hardly moved in the thickness direction of the frame body relatively to the fixing member 3a, and the end surfaces 3a 2 of the rotating member 3b is hardly contacted with the inner flat surface of the upper or lower half 1 or 2 even when the upper and lower halves 1 and 2 are warped. Therefore, the rotating member 3b can be smoothly rotated at all times. Fig. 4 shows a modification of this embodiment. In this case, each of the convex portions 6 and 7 to be formed on the peripheral portion of each of the bosses 4 and 5 is not continuously formed over the whole periphery of each of the bosses 4 and 5, but plural convex portions are intermittently or partially formed on the peripheral portion of each of the bosses 4 and 5 with three convex portions being grouped as an unit. In this modification, a group of convex portions 6 1 , 6 2 and 6 3 and a group of convex portions 7 1 , 7 2 and 7 3 are formed on the peripheral portions of the bosses 4 and 5, respectively. In this case, the flat surface portions 6a 1 , 6a 2 and 6a 3 of the convex portions 6 1 , 6 2 and 6 3 and the flat surface portions 7a 1 , 7a 2 and 7a 3 of the convex portions 7 1 , 7 2 and 7 3 are also designed as to be confronted to the upper and lower end surfaces 3a 2 of the fixing member 3a, but not to be confronted to the end surfaces 3b 2 of the rotating member 3b, so that the same effect as described above is obtainable in this modification. Of course, the number of the convex portions constituting a group (unit) which are formed on the periphery of each boss is not limited to three. Fig. 5 shows another embodiment of this invention. In this embodiment, those portions 8 and 9 which are confronted to the end surfaces 3b 2 of the rotating member 3b on the upper and lower halves 1 and 2 are designed in such a concave shape that they are recessed downwardly from the inner flat surfaces of the upper and lower halves 1 and 2, and those portions which are confronted to the end surfaces 3a 2 of the fixing member 3a serve as convex portions 6 and 7 which project in the inward direction of the frame body upon viewing from the concave portions 8 and 9. In this case, for example the flat surface portions 6a and 7a of the convex portions 6 and 7 may be designed so as to be located at the same height as the inner surface surfaces of the upper and lower halves 1 and 2 excluding the portions 8 and 9. In this embodiment, a sufficient gap interval is also provided between the end surfaces 3b 2 of the rotating member 3b and the upper and lower halves 1 and 2, and thus the contact between the end surfaces 3b 2 of the rotating member 3b and the inner surfaces of the upper and lower halves 1 and 2 is effectively prevented, so that the rotational motion of the rotating member 3b can be smoothly carried out. Further, in this embodiment, the height dimension L 2 ' of the rotating member 3b can be set to be longer than that in the first embodiment as shown in Fig. 1 (L 2 ' > L 2 ), no trouble would occur even if the running position of the magnetic tape is deviated in some degree in the thickness direction of the frame body. This invention is applicable to all tape guide members with which the magnetic tape is slidably contacted so that its running position is guided. Further, this invention may be applicable to any type of tape cassette such as an audio type, a video type, a data storage type or the like. As described above, according to the tape cassette having the tape guide in which the rotating member is freely rotatably mounted around the fixing member, a step portion is provided between the first portion confronting the end surface of the fixing member and the second portion confronting the end surface of the rotating member so that the first portion is more projected in the inward direction of the frame body than the second portion, so that a sufficient gap interval is provided between the rotating member and the upper half member and between the rotating member and the lower half member. Therefore, the rotational motion of the rotating member can be smoothly performed, and the stability of the tape running can be realized.

Claims: A tape cassette in which a tape-like recording medium is accommodated wound on a pair of reels in a frame body comprising upper and lower half members (1,2), the cassette comprising: tape guide means (3) for guiding the running position of the tape-like recording medium, said tape guide means (3) having a substantially-cylindrical fixing member (3a) and a substantially-cylindrical rotating member (3b), wherein said fixing member (3a) is fixed in said frame body by engagedly inserting bosses (4,5) projecting from inner surfaces of said upper and lower half members (1,2) into a hole formed in end surfaces of said fixing member (3a) and said rotating member (3b) is freely rotatably mounted on the outer peripheral surface of said fixing member (3a), wherein around the peripheral portions of said bosses (4,5) each of said upper and lower half members comprise a first portion (6,7) confronting a respective one of said end surfaces of said fixing member (3a) and comprise a second portion (8,9) confronting a respective end surface of said rotating member (3b), characterised in that said first portions (6,7) project more inwardly of said frame body than said second portions (8,9). The tape cassette as claimed in claim 1, wherein said rotating member (3b) is formed with a projection (3b1) on the inner peripheral surface thereof in a radial direction thereof, and said fixing member (3a) is formed with a groove (3a1) on the outer peripheral surface thereof in a radial direction thereof, said projection (3b1) being engageable with said groove (3a1) to allow said rotating member (3b) to be freely rotatably mounted on said fixing member (3a). The tape cassette as claimed in claim 1 or 2, wherein said second portions (8,9) are located in the same plane as the inner flat surfaces of said upper and lower half members (1,2) surrounding them. The tape cassette as claimed in claim 1 or 2, wherein said second portions (8,9) are recessed towards the outside of said frame body from the inner flat surfaces of said upper and lower half members (1,2) surrounding them. The tape cassette as claimed in claim 1, 2, 3 or 4, wherein said first portions (6, 7) are formed so as to have a flat surface which is continuously formed around the whole periphery of the respective bosses. The tape cassette as claimed in claim 1, 2, 3 or 4, wherein said first portions (6,7) are formed so as to have a flat surface (6a 1 , 6a 2 , 6a 3 , 7a 1 , 7a 2 , 7a 3 ) which is only intermittently formed around the periphery of the respective bosses.

Inventors: KONNO TOSHIKAZU, KONNO, TOSHIKAZU, Konno, Toshikazu, c/o Sony Corporation
Applicants: SONY CORP, SONY CORPORATION
Application year: 1993
Main classification: G11B23
IPC codes: G11B23