The invention relates to a magnetic-tape cassette for use with a magnetic-tape cassette apparatus comprising tape-extraction means which, when a cassette is in position on the apparatus, are operable to draw a loop of tape from the cassette for cooperating with a magnetic head or heads on the apparatus; and more particularly to such a cassette comprising a housing having two parallel major walls and two side walls and a rear wall which extends between the major walls at the peripheries thereof, two reel hubs which are rotatable in the housing about axes perpendicular to the major walls of the housing, and a magnetic tape carrier on the hubs, the tape being secured at its ends to the hubs and being unwound from one hub and wound onto the other hub in the operation of the cassette apparatus.
The cassette has two apertures in the front of the housing through which the tape leaves and re-enters the housing while travelling from one reel hub to the other. Two tape supports each define a part of the boundary of an associated one of the front apertures and, when the cassette is not in use, support a portion of the tape that extends across the front of the housing externally between the apertures. The tape inside the housing extends directly between each tape support and an associated one of the reel hubs. A recess formed in the front of the housing between the apertures permits the tape-extraction means of the cassette apparatus, when the cassette is in position on the apparatus, to engage behind the portion of the tape that extends across the front of the housing. The recess is formed by a recess of recesses in the front edge or edges of one or both of the major walls of the housing and is bounded by a wall which extends between the major walls and which has two side wall portions and an intermediate portion extending between the side portions. Each of these side wall portions and the adjacent side wall of the housing bounds a passage in the housing through which the tape passes and which terminates in a respective one of said apertures.
Such a magnetic-tape cassette is known from U.S. Pat. No. 4,235,395 and is widely used in video cassette equipment of the V2000 system. Such magnetic-tape cassette equipment comprises tape-extraction means, for example, in the form of pins or rollers, which when the cassette has been inserted are situated in the recess in the front of the cassette housing, behind the portion of the tape that extends across the front of the housing.
For a more universal use of the cassette and, in particular, a satisfactory operation in the case of a compact construction it is desirable to make the recess in the cassette housing as wide as possible, within the constructional specifications of the cassette. This provides a greater freedom of construction and/or movement, regardless of the dimensions of the housing, for the tape-extraction means with which the apparatus is equipped and by means of which the magnetic tape is drawn from the cassette housing to allow it to cooperate with the magnetic heads of the apparatus, especially when the heads are arranged in a head drum at some distance from the cassette.
When drawn from the cassette housing the magnetic tape in the known cassette cannot become disengaged from the two tape supports at the front of the housing during operation. In the known cassette these tape supports are arranged at the location of the comparatively narrow apertures in the front of the housing, which are disposed at some distance from the side walls of the housing. Because of this arrangement, during operation of the cassette apparatus as the tape as enters and leaves the cassette housing it is always guided by the tape supports of the cassette regardless of the diameters of the rolls of tape on the reel hubs and/or the location of the tape-extraction means relative to the aperture. As a result of this the tape supports have to be manufactured very accurately. Such accuracy can only be achieved at high cost by means of the injection-molding techniques with which the cassette housing is manufactured. Moreover, as a result of the abrasive action of the magnetic tape, the tape supports are generally provided with a hard-metal surface. This surface is also a cost-raising factor.
Even if the two tape supports in the known cassette could be dispensed with, the magnetic tape would still be in contact with wall portions as a result of the arrangement of the side and intermediate portions of the wall of the recess in the front of the cassette housing relative to each other and the position of the apertures in the front of the cassette housing relative to the side walls of the housing, so that these wall portions would influence the tape transport.