Patent Application
20060131461
1. Field of the Invention The present invention is directed to a reel for winding tape-like material thereon, and in particular to a reel for winding magnetic recording tape thereon.
2. Description of the Prior Art For many applications, it is necessary to wind ribbon-like or tape-like material onto a reel. The ribbon-like or tape-like material may be of any type, such as cloth, plastic, paper or thin metal. The tape-like material is wound onto a central hub of a reel, and forms a ribbon pack or tape pack around the hub, between the flanges of the reel.
Particularly when the material is wound onto the hub at a high rotational speed of the reel, air becomes entrained between the successive winding layers in the pack, thereby adding volume to the pack and reducing the packing density. This is particularly a problem in the case of winding of magnetic recording tape, wherein such tape is wound (and unwound) at extremely high speeds. Since most tape cartridges must have a specified form factor (i.e., predetermined standardized dimensions) in order to be used in standardized tape drives, the size of the take-up reel cannot be arbitrarily enlarged to accommodate a larger tape pack. A tape pack that is wound with a smaller packing density, due to the presence of air entrained between the successive wound layers of tape, reduces the total length of tape that can be wound on the reel. This, in turn, reduces the total available tape area for data recording. In general, therefore, it is desirable to have as high a packing density as possible for the tape wound on the reel.
Moreover, in the case of high speed magnetic tape drives, there is also a desire to continually increase the winding speed, because the access time for data recorded at any location along the tape length is dependent on the amount of time required to unwind the tape from the supply reel and wind the tape onto the take-up reel to bring the desired location on the tape past the read head. Therefore, as tape drives operating at increasingly higher speeds are developed, the packing density problem will be even more exacerbated.
An object of the present invention is to provide a reel for winding any type of ribbon-like or tape-like material thereon at high speeds, wherein the amount of air entrainment is reduced, and thus the packing density is increased.
This object is achieved in accordance with the present invention in a reel for windable ribbon-like or tape-like material having first and second flanges mounted on a hub generally parallel to and spaced from each other. One of the flanges has an air evacuator built into it. This built-in air evacuator is formed by an air passage proceeding through this flange communicating an interior space between the flanges with an exterior of the flange having the air evacuator. The air evacuator also includes a low pressure generator that interacts with air at the exterior of the flange having the air evacuator as that flange rotates, for producing, via the air passage, air pressure at the exterior of that flange that is lower than air pressure at the interior region. As the ribbon-like or tape-like material is wound onto the hub as the reel rotates, air flows from the interior region to the exterior, due to the aforementioned lower pressure at the exterior, and therefore less air is entrained between successive wound layers of the material.
In the preferred embodiment, the flange having the air evacuator built into it is partially covered by a flat, circular plate. This avoids air from being drawn by the air evacuator in the opposite direction from the intended direction, which would tend to equalize the pressures at the exterior of the flange and at the interior region, thereby reducing the efficiency of promoting air flow from the interior region to the exterior.
In one embodiment, the air evacuator is formed by a number of curved ribs disposed at the exterior side of the flange, proceeding radially along respective curved paths from a central region to a periphery of the flange. An annular channel is formed at the exterior side of this flange between the central region and a raised edge of the periphery, and the curved ribs connect the central region to this raised edge. As the reel is rotated, each rib has a leading face that interacts with the ambient air in the manner of a turbine blade. Behind each rib, at a trailing side thereof, a number of openings are disposed, collectively forming the aforementioned air passage. The interaction of each curved blade with the air as the reel is rotated produces a low pressure at the trailing side of each rib, thereby producing an air flow through the holes from the interior region of the reel between the flanges.
The aforementioned cover plate has a diameter that is slightly less than the diameter of the flange, so that an annular opening is present at the periphery of the flange, thereby allowing an “escape path” for the air that has been evacuated from the interior region of the reel.
In the further embodiment, the air evacuator is formed by a number of aerofoils disposed in the flange between the central region and a raised peripheral edge of the flange. Each aerofoil has a profile similar to that of an airplane wing, so that a low pressure region is formed at the trailing edge or side of each aerofoil. Again, a number of holes are disposed in the flange at this trailing edge, so that air is evacuated from the interior region of the reel to the exterior of this flange as the reel rotates. Again, a cover plate is provided , having a diameter that is slightly less than the diameter of the flange, thereby producing an annular opening for the evacuated air to escape.
Although the orientation of a tape cartridge containing the two reels on which the tape is wound in a magnetic recording system is arbitrary, the flange that is generally regarded as the “top flange” preferably has the aforementioned air evacuator built into it.
Although the tape reel with the air evacuator as described above can be used to particular advantage in the case of data storage using magnetic recording tapes, the reel with the air evacuator according to the invention can be used in any context wherein windable ribbon-like or tape-like material must be wound at a high speed onto a reel. Therefore, in the following discussion, the generic term “tape-like material” will be used to indicate any type of windable material in a form similar to a tape, ribbon or strip. Such material is not limited to magnetic recording tape, but can be any type of material such as cloth, plastic, metal, paper, etc.
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In the context of magnetic recording tape cartridges, the actual spatial orientation assumed by the cartridge in the drive is arbitrary, since the drive can be essentially arbitrarily oriented, with a few restrictions. Nevertheless, a tape cartridge generally has a side or a surface that is called the “top surface,” and the flange 1 or 1a having the air evacuator built into it preferably is disposed next to this top surface of the cartridge, and thus can be regarded as the “top” flange of the reel 8. Under appropriate circumstances, however, there is no reason why the air evacuator could not be built into the bottom flange 10.
Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.
