LINER SHEET FOR MAGNETIC TAPE CASSETTES

Abstract: The cassette liner comprises a sheet-like element (2) having formed therein a pair of holes positionable at the hubs (15) of a magnetic tape cassette. The holes have perimetral portions adapted to engage folded edges (10) of openings (11) defined by each half-shell (12,13) of the cassette at the hubs (15). The perimetral portions are adapted to assume a curved form with concavity directed towards the hubs (15) of the magnetic tape cassette upon said liner mask being coupled with one of said half-shells (12,13).

Description: The present invention relates to a sheet liner, hereinafter referred to as mask structure, for cassettes of magnetic tape with means for locking with respect to the box-like shell. As is known, cassettes of magnetic tape are constituted by a box-like shell produced by means of two mutually associable half-shells, which define in their interior the region of accommodation of the hubs on which the magnetic tape winds and unwinds. In order to correctly locate the hubs inside the box-like shell, masks are conventionally used which are constituted by sheet-like elements possibly shaped and covered with portions of material with low friction coefficient, which are interposed between the axial ends of the reel of magnetic tape and the inner wall of the box-like shell. In order to position the masks with respect to the half-shells, so as to prevent said masks from moving during the step of coupling of the two half-shells, one or more holes were provided, generally located in the peripheral regions of the mask, with which studs engaged which, slightly forcing into said holes, created a force for the retention of the mask with respect to the half-shells, so as to prevent the displacement of the mask during the step of overturning the half-shells for their mutual coupling. This solution has been abandoned in the course of time, since it is scarcely practical from a functional point of view and poorly accepted from an aesthetical point of view, since said stud was clearly visible from outside. In order to solve the problem using automatic packaging machines, the method was subsequently introduced of slightly wetting or dampening the surface of the mask in contact with the half-shell, so as to have an at least temporary adhesion, required to maintain the coupling between the mask and the half-shell during the assembly step. Even this solution, however, is not free from disadvantages, since it is not infrequent that the unstable adhesion, determined by the wetting of the sheet-like element or by other methods or experiences currently in use, lead to an uncoupling of the sheet-like element from the half-shell; moreover, the wetting of the sheet-like element unavoidably creates residual humidity in the cassette. Also known from FR-A-2,498,363 is a mask for magnetic tape cassettes as defined in the precharacterizing part of claim 1. However, the mask known from FR-A-2,498,363 cannot be locked to the half-shells of the box-like cassette structure, whereby to prevent displacement of said mask upon overturning the cassette half-shells during assembly of the magnetic tape cassette. The aim proposed by the invention is indeed to solve the above described problem, by providing a mask structure which is easily connectable to the related half-shell, without having to provide modifications in the half-shell, such as the presence of studs, pins or the like. Within the scope of the above described aim, a particular object of the invention is to provide a mask which, besides solving the problem of its connection to the half-shell during the step of overturning for the manufacture of the box-like shell, is capable of positioning itself perfectly with respect to said half-shell in a substantially stable manner, thus keeping this positioning even during the phases of use of the cassette. Still another object of the present invention is to provide a mask structure which, though having considerably improved functional characteristics, does not thereby have constructive complications or additional costs. Not least object of the present invention is to provide a mask structure which can have any surface configuration deemed suitable, and which furthermore is easily applicable to any type of box-like shell of a cassette for magnetic tapes. The above described aim, as well as the objects mentioned and others which will become apparent hereinafter, are achieved by a sheet liner as defined in appended claim 1. Further characteristics and advantages of the invention will become apparent from the detailed description of a mask structure for cassettes of magnetic tape with means for locking with respect to the box-like shell, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a view of a mask with holes having mutually parallel diametral portions; Figure 2 is a view of a mask with ovalized holes; Figure 3 is a view of a mask with substantially hexagonal holes; Figure 4 is a view of a mask with holes having counterposed tabs; and Figure 5 is a cross section view of a mask applied to a cassette of magnetic tape. With reference to the above described figures, the mask structure for magnetic tape cassette with means for locking with respect to the box-like shell, according to the invention, generally indicated by the reference numeral 1, has a sheet-like element 2 which can have any configuration deemed suitable. The peculiarity of the invention resides in the fact that the sheet-like element 2 defines a pair of through holes which have perimetral portions which are capable of engaging with the folded edges 10 of the openings 11 which are defined by the half-shells 12 and 13 of the cassette for magnetic tape, respectively at the hubs 15 on which the magnetic tape 16 winds. According to what is illustrated in figure 1, a hole 20 is provided, having a substantially circular configuration, which has two counterposed perimetral portions constituted by rectilinear portions 21 interfering with the circular configuration. In this manner the rectilinear portions 21, which have a mutual distance which is smaller than the outer diameter of the folded edges 10, elastically engage with said folded edges, creating a fold during the application step which produces an elastic force which retains said mask in contact with the half-shell, even in the steps of overturning of the half-shell for mutual coupling. The same functional effect can be obtained by means of ovalized holes 25 wherein the engagement portions are constituted by the portions of the smaller axis which have a smaller distance with respect to the outer diameter of the folded edges 10. A similar effect is also obtainable with holes 30 with a polygonal configuration, in which at least two substantially counterposed sides have a mutual distance which is smaller than the outer diameter of the folded edges 10. In figure 4, the mask 1 has holes 35 which are provided with two radial tabs 36, which may be arranged in a counterposed diametral position, in the case of two tabs, or possibly also variously distributed, in the case of a plurality of tabs, and which have such a mutual distance as to engage by elastic contact with the outer surface of the folded edges 10, obtaining the same effect described above. To the above one must furthermore add that by applying the mask on the half-shell a curvature is created in the perimetral portions, engaging with the folded edge 10, which has its concavity facing towards the reel of the cassette, so that the edges which delimit the holes provided on the sheet-like element constituting the mask tend to "jam" with respect to the folded edge 10, impeding uncoupling of the mask from said folded hole. From the above it can thus be seen that the invention achieves the intended aim and objects, and in particular the fact is stressed that a mask is provided which is capable of elastically anchoring to the related half-shell, without having to provide structural modifications in the half-shells constituting the cassette or without having to resort to expedients such as the wetting or the like of the surface of the mask to make it at least temporarily adherent to the half-shell. Furthermore, the coupling obtained by virtue of the perimetral portions interfering with the folded edge has the function of better positioning said mask inside the cassette. In practice, the materials employed, so long as compatible with the specific use, as well as the dimensions and the contingent shapes, may be any according to the requirements. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: A sheet liner (2) contained in a conventional magnetic tape cassette of the type having half shells (12, 13) with openings defining folded edges (10) at cassette hubs, said sheet liner comprising a pair of holes (20, 25, 30, 35) formed in the sheet liner (2) and being positionable at the hubs (15) of a conventional magnetic tape cassette, and perimetral portions (21, 26, 31, 36) defined by the edges of said holes (20, 25, 30, 35) and being positionable at the folded edges (10) of openings defined at the hubs (15) of each conventional half shell (12, 13) of the box-like shell of a conventional cassette, characterized in that said holes have perimetral portions (21, 26, 31, 36) adapted to lock said sheet liner (2) to the folded edges (10) of a cassette, whereby to prevent displacement of said sheet liner upon overturning the cassette half-shells (12, 13). A sheet liner contained in a conventional cassette according to claim 1, characterized in that said means (21, 26, 31, 36) elastically lock said sheet liner (2) to the folded edges (10) and comprise at least two locking portions peripherally spaced apart by at least two intermediate portions. A sheet liner contained in a conventional cassette according to claims 1 or 2, characterized in that said means (21) for locking the sheet liner (2) comprise at least two rectilinear portions (21) defined by said hole (20). A sheet liner contained in a conventional cassette according to claims 1 or 2 and 3, characterized in that said rectilinear portions (21) of said hole (20) extend substantially parallel and diametrically opposite to each other. A sheet liner contained in a conventional cassette according to claim 3 or 4, characterized in that said rectilinear portions (21) extend substantially parallel to the edge of said sheet liner (2). A sheet liner contained in a conventional cassette according to claim 1 or 2, characterized in that said means (21, 26, 31, 36) for locking said sheet liner (2) to the folded edges (10) comprises an oval configuration defined by said holes (25), said means for locking (26) being spaced apart by the minor axis of said oval configuration. A sheet liner contained in a conventional cassette according to claims 1, 2 and 6, characterized in that said means for locking (26) are radiused to said intermediate portions. A sheet liner contained in a conventional cassette according to claim 1, characterized in that said holes (30) have a polygonal configuration, said means for locking (31) being defined by counterposed sides (31) of said polygonal configuration. A sheet liner contained in a conventional cassette according to claims 1 and 8, characterized in that at least two of said counterposed sides (31) extend parallel to each other and parallel to the longitudinal edges of said sheet liner (2). A sheet liner contained in a conventional cassette according to claim 1, characterized in that said means (36) for locking the sheet liner (2) comprise at least two tabs (36) protruding radially towards the centre of each hole (20). A sheet liner contained in a conventional cassette according to claim 9 or 10, characterized in that said tabs (36) extend towards each other in a transverse direction with respect to the longitudinal extension of said sheet liner (2).

Inventors: BORDIGNON, ABRAMO
Applicants: A.T.B. S.P.A.
Application year: 1987
Main classification: G11B23
IPC codes: G11B23