TAPE REEL CARTRIDGE BACKGROUND OF THE INVENTION
This invention relates generally to tape reels used in reel-to-reel magnetic tape transport mechanisms, and, more particularly, to devices for retaining tape on a tape reel when removed from a tape transport mechan¬ ism.
Tape transport mechanisms of various kinds have been used for many years in conjunction with digital computers, for both program storage and data storage. Typically, magnetic tape is supplied on a supply reel installable in and removable from a tape transport mech¬ anism. When the supply reel is placed in the mechanism, the tape is fed from the reel past a magnetic recording head and onto a take-up r-eei. The transport mechanism may include a capstan and pinch roll-er to draw the tape past the recording head at a constant speed, or a drive belt that bears on the surface of the packed tape on each reel. In many systems, the tape is provided with a leader of different material from the recording tape itself, usually to facilitate automatic or semi-automa¬ tic threading from the supply reel to the take-up reel. One practical difficulty that is common to all reel-to-reel tape transport mechanisms is that some
OMPI
means must be provided for protecting the tape once the supply reel is removed from the transport mechanism. Otherwise, the free end of the tape could unravel from the reel and the entire tape could be subjected to da - age due to the intrusion of dust or moisture. In the past, some magnetic tape reels have been stored in round, flat cans, in the same manner as movie film, or have been provided with a separate peripheral closure which is secured about and between the flanges of the reel. This prevents the tape from emerging from between the flanges, although does not totally preclude unrav¬ eling. Such a closure also provides a fairly effective seal against the intrusion of dust and moisture. How¬ ever, both these approaches require the provision of separate containers or closures, and introduce a signif¬ icant inconvenience in the operation of the tape trans¬ port mechanism.
Accordingly, attempts have been made to provide a sealable tape reel which has the qualities of a self- contained cartridge. One way to do this is to provide a leader of significantly greater width than the record¬ ing tape itself-, and to modify the flanges of the reel to include at ι?ast one annular groove on the inside face of t^ flange. In accordance with the tape reel disclosed by Hosono et al in U.S. Pat. No. 3,797,777, one reel fla.g« is provided with an annular groove or recess and the other flange includes a flexible retain¬ ing spring, which holds the tape leader in the groove. In accordance with another technique, a flexible annular disc is installed adjacent to and inside one of the flanges. The relatively wide leader strip flexes the outer periphery of the flexible disc, which may include a serrated surface, ;and the disc holds the leader in place. Such an arrangement is shown by Lewis in U.S. Patent No. 4,168,811.
There are, however, significant problems inher¬ ent to both these attempts to provide a self-contained reel cartridge. First, the contact surface between the
tape leader and a groove or a flexible disc does not provide a completely effective seal against the intru¬ sion of dust and humidity. Furthermore, the retaining forces applied to the leader are significantly dependent upon the radial distance from the center of the reel. In the case of the grooved flange, clearly the leader will not engage at any other position than in the groove. Similarly, the retaining force provided by a flexible disc is very sensitive to position. If too much tape is on the reel, engagement of the leader at the outer periphery of the disc may not result in a sufficiently high retaining force. On the other hand, if too little tape is on the reel, the leader may have to be forced into position and may be difficult to re- move when the tape is next used.
With the development of relatively inexpensive belt-driven tape transport mechanisms, for use with small computer systems, there has been an increased need for a tape reel cartridge which overcomes the disadvan- tages of the prior art and provides an effective seal against dust and humidity, regardless of the amount of tape that may be on the reel. The present invention is directed to this end, and provides what is believed tc be a novel solution to these problems.
SUMMARY 0? THE INVENTION
The present invention resides in a tape reel cartridge for storing magnetic recording tape for use in - a tape transport mechanism, and providing self-contained means for protecting the tape against unraveling, as. well as from the intrusion of dust and humidity. In accordance with the invention, each flange of the tape reel is provided with an annular layer of a resilient material, which is engaged and deformed by a leader tape of significantly greater width than the width of the recording tape. Since the layer of resilient mater¬ ial, which is preferably of natural or synthetic rubber,
extends over a significant radial distance, the sealing mechanism provided by engagement of the leader with the resilient layers is effective over a wide radius range. In accordance with a presently preferred embodi- ent of the invention, the resilient layers are secured in annular recesses in the flanges, the depth of the recesses becoming greater with increasing radius, such that the exposed faces of the resilient layers are par¬ allel with each other over much of the radial dimension of the layers, and slope outwardly further apart as the maximum radius is reached. With this configuration, re¬ moval of the leader from between the resilient layers is greatly facilitated.
It will be appreciated from the foregoing, that the present invention represents a significant advance in the field of tape reel cartridges. In particular, it provides a cartridge in which the tape can be effective¬ ly retained and stored by a self-contained reel closure, safe from the intrusion of dust and humidity. Moreover, the reel closure provided by the invention is effective over wide -ranges of tape radius, and is eytremely simple, convenient and reliable in operation. Other aspects and advantages of the invention will become ap¬ parent from the following more detailed description, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINCS
FIGURE 1 is a diagrammatic plan view of <*. Delt- driven tape transport mechanism in which the invention may be used; FIG. 2 is a fragmentary cross-sectional view of a tape reel cartridge embodying the present invention, taken substantially along the line 2-2 in FIG. 1;
FIG. 2a is a fragmentary cross-sectional view similar to FIG. 2, showing a preferred embodiment of the invention;
FIG. 3 is an elevational view of the tape reel
-BURE
OMPI
cartridge, shown partly in section and taken in a direc¬ tion parallel to the planes of the reel flanges;
FIG. 4 is a fragmentary view of a portion of magnetic tape attached to a leader strip; and FIG. 5 is a cross-sectional view of the. tape and leader strip taken substantially along line 5-5 of FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in the drawings for purposes of illus- tration, the present invention is principally concerned with a tape reel cartridge for a tape transport mecha¬ nism. Various attempts have been made to provide a tape reel cartridge for use in open reel tape transport sys¬ tems, and to provide in the cartridge self-contained means for sealing the tape, both to prevent unraveling and to keep out dust and moisture from the reel. Prior to this invention, devices available for this purpose have either required the use of additional separate components, or have not been completely effective in sealing the reel when the tape pack radius is different from some optimum value.
By way of background, FIG. 1 shows in diagram¬ matic form a tape transport mechanism in which the present invention would typically be employed. The mechanism includes a removable supply reel, indicated by reference numeral 10, from which recording tape 11 is supplied to the mechanism, a take-up reel 12, and a tape-drive belt 14 which circumferentially engages the packs of tape -on the two reels. The belt 14 also enga- ges a motor drive pulley 16 disposed between the reels 10 and 12, and two other pulleys 18 and 20 positioned to maintain the belt 14 stretched across the packed tape on the two reels. The tape is driven at a constant speed past a recording or play back head 22. The tape passes over other pulleys 24 and 26, or alternatively, through a continuous channel (not shown) extending from
the reel 10 to the reel 12 and past the head 22. Such a channel may be employed to facilitate automatic thread¬ ing of the tape from one reel to another.
As shown, in FIG. 3, the reel 10 includes a hub 30 and two flanges 32 and 34 rigidly attached to the hub. For ease of manufacture, the flange 34 is formed integrally with the hub 30, and the other flange 36 is formed separately and later attached to the hub. In accordance with the invention, the inner surface of each of the flanges 32 and 34 is provided with an annular resilient layer 36. Each of the resilient layers 36 is secured, as by an adhesive, in an annular recess in the flanges 32 and 34, such that the exposed surface of the layer 36 is continuous with the inner surface of the flange.
As shown in FIGS. 4 and 5, the tape 11 is secured to a leader strip 40, which is significantly wider than the tape. In the illustrative embodiment, the tape is one mil thick (2.54 x 10 meter) and one- half inch (12.7 mm) wide, while the leader 40 is made from a polyester film of 5 mil (12.7 x 10 meter) thickness and 0.6 inch (15.2 mm) width. As shown in FIG. 2, the leader 40 deforms the resilient layers 36 significantly when the leader is wrapped around the reel 10. However, the leader 40 is not itself deformed or buckled, as is the case in some prior art devices, and a good seal is provided between the leader and the resil¬ ient material 36.
As shown in FIG. 2a, the layer 36 is preferably installed in a recess of non-uniform depth in the flange 32 or 34. Thus, the exposed surface of_the resilient layer 36 is parallel with the plane of the flange over a portion of its radial dimension, indicated at 42, but as the outer radius of the layer is approached, the layer 36 slopes outwardly to conform with a deeper recess in the flange, as indicated at 44. In addition, each flange 32 or 34 is provided with an integral outer re¬ taining lip 46, which extends over the edge of the layer
"BU EA
OMPI
36 and serves to secure it more reliably to the flange. It will be noted that .the lip 46 is not as wide as the overall flange thickness, to allow for easy insertion of the leader between the two peripheral lips 46. Although specific materials and dimensions will depend on a variety of factors, including the size of the tape, in the illustrative embodiment of the inven¬ tion the resilient layers 36 are made from l/16th inch (1.6 mm) thick polyurethane rubber having a Shore hardness in the range of 40 to 60. Depending on the stiffness, width and hardness of the leader, a rubber hardness in the range from 30 to 80 will probably be usable in most cases. The use of polyurethane or silicone rubber renders the invention extremely reliable since the rubber does not take a set on compression, yet still retains the leader strip reliably. In contrast, grooves in a flexible flange are subject to wear, or will cause in wear of the leader strip itself.
It will be appreciated from the foregoing that the present invention represents a significant advance in the field of tape storage for tape transport mechan¬ isms. In particular, the invention provides a reliable closure for a tape reel without the need for additional components. Moreover, the closure is effective to seal the tape against environmental effects over a wide radius range for the packed tape. It will also be appreciated that, although a particular embodiment of the invention has been described in detail for purposes of illustation, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.