Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system
Reexamination Certificate
2000-09-12
2001-08-28
Nguyen, John Q. (Department: 3653)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
Cartridge system
C242S356000, C360S085000, C360S093000
Reexamination Certificate
active
06279845
ABSTRACT:
TECHNICAL FIELD
The present invention relates to driving reels upon which magnetic tape is wound.
BACKGROUND ART
Magnetic tape is commonly used to store voice and data information due to its reliability, cost efficiency, and ease of use. Magnetic tape may be made more useful and cost-effective by increasing the density of information stored and decreasing the time required to access this information. Tape may be made wider and data tracks written on the tape narrower to increase the areal density of information stored on the magnetic tape. Tape may be made thinner to increase the volume of information stored on a reel of tape. Tape may be moved past the tape head faster to increase the rate of information transfer. Tape paths may be shortened to decrease access time, decrease costs, and decrease the size and complexity of tape access systems. These factors generally necessitate increased accuracy in positioning magnetic tape relative to tape access components.
Tape is typically wound on one or two reels in a protective housing, such as a cassette or cartridge. The path of magnetic tape leaving its containment housing depends on the positioning of the reel relative to the tape player. Typically, this position is established at the interface of the tape reel and the tape player drive coupling used to spin the tape reel. Current coupling designs locate the reel by mating drive teeth on the coupling with drive teeth on the reel. Fixturing the reel to the coupling using this relatively complex geometry is prone to many types of misalignment errors. These errors, representing the accuracy of tape reel location, can be expressed using a variety of geometric criteria. First, axial difference between the tape centerline of the reel and the tape path centerline of the drive represents a positioning offset in the plane of tape travel. Second, perpendicularity of the tape reel axis relative to the tape path centerline of the drive indicates the angular error of the tape path leaving the reel. Third, run out of the tape reel, typically measured at the outside edge of the reel flange, produces a time-varying error in the tape path. Runout is expressed as two components, the axial variation of the reel flange and the radial variation of the reel flange.
If mating drive teeth on the coupling and reel flange are used to position the tape reel, the drive tooth pattern must be very precisely manufactured. Additionally, if the drive teeth become deformed due to mishandling, wear, debris, or the like, the alignment of the reel could be impacted. Typically, the drive teeth on the reel are made of plastic. These teeth wear, break, and deform differently on different cartridges. Hence, misalignment errors may vary greatly between cartridges.
What is needed is to couple tape drives to tape reels in a manner that does not rely on the geometry of drive teeth. In particular, correct axial positioning is needed to minimize tape path errors. Such a coupling should be implemented within cost and space constraints imposed by commercial tape players and cartridges.
DISCLOSURE OF INVENTION
It is an object of the present invention to couple tape reels to tape drives without relying on drive teeth as the principal means for establishing position.
Another object of the present invention is to more accurately position tape reels.
Still another object of the present invention is to position tape reels onto drive couplings in a mainer that is less susceptible to manufacturing tolerances.
Yet another object of the present invention is to couple tape reels to tape drives in a manner that is less susceptible to mechanical damage.
In carrying out the above objects and other objects and features of the present invention, a coupling for driving a magnetic tape reel is provided. The coupling includes drive teeth located a fixed radial distance from a drive shaft. The drive teeth drive a tape reel by engaging mating teeth on the tape reel. An annular surface is also located about the shaft. The annular surface contacts datum pads on the tape reel to axially position the tape reel relative to the drive shaft.
In an embodiment of the present invention, three datum pads on the tape reel define a tape reel axial location plane.
In another embodiment of the present invention, the drive teeth are located on a drive ring. The coupling also includes a flexure assembly permitting the drive ring to float in the axial direction.
In still another embodiment of the present invention, the coupling includes a magnet attracting a magnetically sensitive surface of the tape reel to engage the drive teeth with mating teeth on the tape reel.
In a further embodiment of the present invention, the annular surface is located on a datum ring and the drive teeth are located on a drive ring.
A system for accessing magnetic tape is also provided. The system includes tape cartridges having at least one reel upon which magnetic tape is wound and unwound. The reel has a reel surface accessible through an opening in the tape cartridge. The reel surface defines reel teeth and a plurality of datum pads. The system also includes a tape unit. The tape unit has at least one recording head for accessing information on the magnetic tape. The tape unit also has a drive ring with drive teeth located a fixed distance about a drive shaft. The drive teeth engage the reel teeth to drive the tape reel when the drive ring is spun by a motor. The tape unit also includes a datum ring defining an annular surface radially located about the drive shaft. The annular surface contacts the datum pads to axially position the tape reel relative to the drive shaft.
A method for coupling a drive shaft to a magnetic tape reel is also provided. The tape reel is located relative to a drive axis by contacting an annular surface rotating about the drive axis with datum pads on the tape reel flange. Drive teeth rotating about the drive axis engage with mating reel teeth to spin the tape reel flange.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
REFERENCES:
patent: 3857531 (1974-12-01), Jantzen
patent: 4654740 (1987-03-01), Katoku
patent: 4775115 (1988-10-01), Gelardi
patent: 5366173 (1994-11-01), Lammers et al.
patent: 5564647 (1996-10-01), Bay et al.
patent: 5992782 (1999-11-01), Goodknight
patent: 0 284 687 (1988-10-01), None
patent: 2236092 (1991-03-01), None
Bendson Steven A.
Falace Joseph P.
Graves David C.
Hemzacek Wayne R.
Hoge David T.
Brooks & Kushman P.C.
Nguyen John Q.
Storage Technology Corporation
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