Magnetic tape cassette

Abstract: A magnetic tape cassette having tape reels on which a magnetic tape is wound, includes magnetic tape regulating members one end portions of which are securely fixed on the magnetic tape cassette, other portions thereof being in contact with edge portions of the magnetic tape so as to regulate side edge alignment of the magnetic tape in the magnetic tape cassette. Thus, it is possible to prevent tape damages such as tape edge folding caused by side edge misalignment of the tape in the cassette.

Description: BACKGROUND OF THE INVENTION The invention relates to a magnetic tape cassette according to the precharacterizing part of claim 1. Conventionally, in order to reduce the size of a magnetic tape cassette, flanges of tape reels are eliminated, and a supply reel and a take-up reel are located in such a manner that their maximum winding diameters overlap each other, thereby decreasing a pitch between the reels. Thus, it is possible to decrease the plane area and the height of the magnetic tape cassette. In this type of cassette, sheet-like members are inserted between a casing and the magnetic tape so as to prevent side edge misalignment of the magnetic tape which is caused by absence of flanges. As a magnetic type cassette of such a structure, one example is disclosed in Japanese Patent Unexamined Publication No. 60-154375. EP-A-0 394 780 is used for the delimitation of claim 1 and discloses a magnetic tape cassette of a similar kind with flangeless reels having tape regulating members which are mounted between the tape edge and the inside of the casing so as to prevent misalignment of the tape. These regulating members are sheet-like slide plates which resiliently press against the magnetic tape and which resiliently abut the inner sides of the cassette halves. A tape cassette of the structure in which no flanges are formed on tape reels involves problems in relation to side edge alignment of a magnetic tape. That is to say, levels of side edges of the magnetic tape wound on the reel become irregular, and levels of side edges of the magnetic tape with respect to a tape moving system of the apparatus are not constant. In order to solve these problems, the above-mentioned method of inserting sheet-like members is employed. In this method, however, the sheet-like members and the magnetic tape always slide on each other so that edges of the magnetic tape are likely to be damaged. Moreover, the sheet-like members are located in such a manner that gaps of predetermined distances are defined between the sheet-like members and the casing of the tape cassette, and consequently, levels of side edges of the magnetic tape with respect to the tape cassette can not be precisely determined. If a deviation is caused between the level of the magnetic tape and the level of the tape moving system of the apparatus, movement of the magnetic tape becomes unstable, so that reliable track tracing can not be conducted, and that the tape will be easily damaged by flanges of tape guides or the like, thereby deteriorating the quality of reproduced images. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a small-sized tape cassette in which contact between edges of a magnetic tape and components of the tape cassette can be decreased, and levels of side edges of the magnetic tape in the tape cassette can be precisely determined. In order to achieve this object, according to the invention, a magnetic tape cassette is provided having the features as mentioned in the characterizing part of claim 1. Further advantageous developments of the inventive cassette are mentioned in claims 2 and 3. Each pair of the magnetic tape pressing members has one ends secured on the tape cassette, and portions of the pressing members at a predetermined distance from the secured ends are positioned to be predetermined distances away from edge portions of the magnetic tape by means of a stopper provided on the tape cassette. Consequently, the magnetic tape pressing members can be positioned with respect to the tape cassette, and also, they can produce predetermined forces. By aligning the side edge levels of the magnetic tape wound on a supply reel and a take-up reel with the levels defined by the magnetic tape pressing members, the side edge levels of the magnetic tape wound on each reel can be maintained accurately with respect to the tape cassette, and even if a disturbance to change the side edge levels of the magnetic tape is caused, it is possible to maintain the magnetic tape at a predetermined position and to effect the side edge alignment by the forces of the pressing members. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view showing one embodiment of a magnetic tape cassette according to the present invention; Fig. 2 is a cross-sectional view taken along the line A-A of Fig. 1; and Fig. 3 is an enlarged cross-sectional view showing the portion B of Fig. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of the present invention will be hereinafter described with reference to the attached drawings. Fig. 1 is a plan view showing one embodiment of the invention. In this figure, a magnetic tape 1 is wound on the outer peripheries of a supply reel hub 3 and a takeup reel hub 4 provided in a cassette 2, the tape being at a predetermined level to be spaced from walls of the cassette at a predetermined distance. The magnetic tape 1 is extended out of the cassette 2 through a supply side opening 2a and a take-up side opening 2b of the cassette 2. As shown in the figure, the cassette 2 is provided with pressing members 5 having a cylindrical shape in cross section. The pressing members are mounted at their one ends on the cassette, extending from a portion of the side wall adjacent to the supply side opening 2a toward the supply reel hub 3. The one end portions or proximal ends of the pressing members 5 are press-fitted and retained on a predetermined position of a cassette casing side wall 2c, and the other end portions of the pressing members 5 serve to regulate side edge alignment of the magnetic tape 1. Also, on the take-up side of the cassette 2, additional pressing members 6 are provided on a predetermined position of a cassette casing side wall 2d in substantially the same manner as on the supply side. Further, stoppers or positioning members 2e and 2f for the pressing members 5 and 6 are integrally formed on the cassette casing side walls 2c and 2d, respectively. Fig. 2 is a cross-sectional view taken along the line A-A of Fig. 1. In this embodiment, each pair of the pressing members 5 or 6 is located in spaced relation to clamp the magnetic tape 1 therebetween, thereby maintaining the magnetic tape 1 at a predetermined position and effecting the side edge alignment. Fig. 3 is an enlarged cross-sectional view showing the portion B of Fig. 2. In this figure, the pressing members 5 of the magnetic tape 1 comprise a pressing member 5a for regulating the upper edge alignment of the tape and a pressing member 5b for regulating the lower edge alignment of the tape. The pressing members 5a and 5b are attached to the cassette casing so as to be elastically deformable in directions for restricting the width of the magnetic tape 1, as indicated by dashed lines in the figure. In this case, the positioning member 2e serves to maintain the gap between the pressing members 5a and 5b at substantially the same distance as the tape width, thus preventing the magnetic tape from being restricted by an excessive force. According to this embodiment, as described above, the side edge alignment of the magnetic tape can be maintained constantly even in the case of the reels having no flanges, so that edges of the tape can be prevented from being damaged due to side edge misalignment. As clearly understood from the above description, the magnetic tape cassette of the present invention has effect on prevention of tape damages such as tape edge folding caused by side edge misalignment of the tape in the cassette. This embodiment, which is a mere example of the present invention in every aspect, should not be interpreted in a limited manner. The scope of the invention is determined by the appended claims.

Claims: A magnetic tape cassette for loading on a magnetic recording/reproducing apparatus, the cassette includes a cassette body casing (2), two hub members (3, 4) mounted in the cassette body casing (2) for rotation about respective axes perpendicular to a bottom surface of the cassette body casing (2), a magnetic tape (1) wound on the respective hub members (3, 4) to form tape reels thereon with each tape reel having a top edge surface and a bottom edge surface, and tape regulating means in contact with the respective tape reels for regulating the top and bottom edge surfaces thereof, and the hub members (3, 4) are adapted to, when the magnetic tape cassette is loaded on the magnetic recording/reproducing apparatus, be driven by tape take-up shafts of the apparatus to wind the magnetic tape (1) from one of the tape reels (3, 4) to the other for recording of signals on the magnetic tape (1) or reproducing of signals from the magnetic tape (1), characterized in that said tape regulating means includes two pairs of top and bottom elongated rod members (5a, 5b, 6a, 6b), and each rod member (5a, 5b , 6a or 6b) is securly attached at an end thereof to said cassette body casing (2) and extends radially across an adjacent one of the tape reels in line contact with the top or bottom edge surface of the adjacent tape reel so that said top and bottom edge surfaces of the respective tape reels are maintained at substantially constant levels in said magnetic tape cassette to minimize deviations of turns of the tape (1) from said top edge surface and said bottom edge surface. A magnetic tape cassette according to claim 1, characterized in that said tape regulating means further includes stopper members (2e, 2f) securly fixed on said cassette body casing (2), each stopper member (2e or 2f) contacts the top and bottom rod members (5a, 5b or 6a, 6b) of each pair of said tape regulating means to restrict said top and bottom rod members (5a, 5b or 6a, 6b) from movement toward said top and bottom edge surfaces of said magnetic tape reels, while allowing said top and bottom rod members (5a, 5b or 6a, 6b) to be in line contact with said top and bottom edge surfaces of said magnetic tape, respectively, to regulate the alignment of said magnetic tape (1) in said magnetic tape cassette. A magnetic tape cassette according to claim 1 or 2, characterized in that each of said elongated rod members (5a, 5b, 6a, 6b) is elastically deformable.

Inventors: KAKU NOBUYUKI, OGIRO KENJI, TAKEDA HIDEKAZU, KAKU, NOBUYUKI, OGIRO, KENJI, TAKEDA, HIDEKAZU
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1993
Main classification: G11B23
IPC codes: G11B23