HIGH STORAGE CAPACITY COMPACT CARTRIDGE FOR USE WITH A PRECISION MAGNETIC TAPE RECORDER

Abstract: A compact cartridge (10) for storing approximately 720 feet of 0.25'' wide magnetic tape (20) comprises a two section plastic enclosure (12, 14) containing two reel spools and associated hubs (16, 18). The tape (20) is reeled on the cartridge spools with the recording surface of the tape (20) facing inward towards the cartridge (10) interior. The cartridge (10) is axially loadable into a recorder, and an aperture (28) in the bottom of the cartridge (10) allows entry of the recorder heads (50) and guides (52) for contacting the tape's recording surface. Leaf spring tight winders (40, 42) are provided to squeegee entrained air from between the turns of the tape (20) as the tape (20) is reeled from one hub (16, 18) to the other. Until the cartridge (10) is seated in the recorder, tape lifters (22, 24) keep the tape (20) clear of the aperture (28) to allow unimpeded positioning of the heads (50) for contact with the tape (20) in the cartridge (10). After the cartridge (10) is seated, the tape lifters (22, 24) release the tape (20), allowing it to wrap the heads (50) and guides (52) of the recorder, and simultaneously the locks (36, 38) on the cartridge hubs (16, 18) are released.

Description: HIGH STORAGE CAPACITY COMPACT CARTRIDGE FOR USE WITH A PRECISION MAGNETIC TAPE RECORDER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a magnetic tape cartridge, and in particular to a low cost, high storage capacity, compact cartridge. 2. Description Relative to the Prior Art Magnetic storage devices, such as magnetic tape drives and magnetic disk units, are indispensable components of modern computers and data processing systems. Tape drives are used for archival storage of data and programs, while disk units serve as quick access storage means for operating systems and programs, data storage of computational results and word processing outputs. With continuing trends toward higher speed and higher capacity digital processors, the need for higher transfer rate and increased storage capacity magnetic storage devices is also rising. Much of the current growth is directed towards small office systems, computer work stations and personal computing systems for home use. Magnetic storage devices suitable for use in these areas must not only meet increasing processor speed and storage demands, but must also be reliable, inexpensive, and spatially compact. Advances directed towards meeting the above goals are ongoing in the art. Inexpensive, non-precision cartridges which serve primarily as tape containers that shift the precision guiding of the tape to elements located on the transport itself have been described in U.S.Patent 4,410,419 in the name of Armstrong, and U.S.Patent 4,757,399 in the names of Peterson et al. A simplified precision, low flutter transport that incorporates a microcomputer controlling the transport reeling system to maintain constant tape speed without the use of a capstan is described in U.S. Patent 4,256,996 in the names of Brooks et al. Increased storage capacity in a miniature cartridge accomplished by use of 0.25" wide tape in a mini-cartridge configuration is available in the 3M Company, St. Paul, Minn., DC 2000 cartridge. Further improvements are needed to meet the requirements of an advanced, cartridge loaded, miniature magnetic tape storage system having a transfer rate of 3 megabytes per second and capable of storing 2 gigabytes on about 720 feet of 0.25" wide magnetic tape. This advanced magnetic tape storage system is packaged as a "half-height" unit which mounts in a standard computer rack, and occupies a mere 1.63" x 5.75" of panel space. The stringent system performance requirements, coupled with small size and economic constraints, demands significant advances in system components over those known in the prior art. The present invention of a compact tape cartridge has the goal of meeting the system tape container requirements. SUMMARY OF THE INVENTION A compact cartridge for storing approximately 720 feet of 0.25" wide magnetic tape comprises a two section plastic shell containing two reel spools and associated hubs adapted for mating with turntables driven by the reeling motors mounted on a precision plate of an associated tape transport. The tape is wound on the cartridge spools with the recording surface of the tape facing inward towards the cartridge. The tape is transportable from reel to reel for operation in either a forward or reverse direction, with a span of tape extending between the reels for contacting the heads and guides mounted on the recorder. The cartridge is manually inserted into an opening in the front face of the recorder, and upon the closing of the door of the transport, the cartridge is axially lowered onto the reel motor turntables. A firm, solid connection with no play between the reel motor turntables and the cartridge hubs is required to prevent induced flutter in the tape. This is denoted as a "zero clearance" fit between the reel turntables and cartridge hubs which maintains flutter free tape motion by control of wobble and eccentricity at the mating connection. The zero clearance fit is required as tape speed is totally under control of the transport reeling system: there is no conventional capstan in the transport for metering tape speed. As stated above, the cartridge stores 2 gigabytes of data on about 720 feet of tape. The linear packing density is 80 kilobits per inch. Because of the extremely high packing density, intimate contact between the tape and heads is an essential requirement. To insure this intimate contact, the recording surface of the tape is very smooth; an asperity can lift the tape away from the gap of the head with attendant signal loss. This tape smoothness, however, may result in air entrapment between turns of the tape particularly during high speed rewind or fast forwarding operations. "Tight winders", which are spring assemblies mounted in the cartridge, ride against the outermost surface of the tape pack and squeeze out any entrained air as the pack increases in radius. Additionally, the tight winders prevent any tendency of the outer layers of the tape pack to unravel when the cartridge is out of the recorder. Because the recording surface of the tape in the cartridge faces inward, contact between the recording surface and the heads must be accomplished by slipping the cartridge over the heads and guides as it is being lowered into position for mating with the recorder. An aperture is provided in the cartridge bottom surface through which the heads and fixed tape guides located on the precision plate of the transport are inserted as the cartridge drops into position. No guides are located in the cartridge, the guides are exclusively mounted on the transport, simplifying cartridge construction as well as reducing cartridge cost. The cross-section of the cartridge enclosure is hexagonal, readily identifying the front end of the cartridge for easy insertion into the recorder. As the cartridge is being lowered into position in the transport, it is necessary to hold the tape away from the heads and guides until the cartridge is fully seated. A pair of "tape lifters" in the cartridge accomplish this by engaging the tape and holding it clear of the heads and guides during insertion. When the cartridge is in position and its hubs mated with the turntables of the reeling motors, the tape lifters are retracted, and the tape wraps the heads and guides in preparation of operation. When the cartridge is out of the recorder, it is in a "parked" configuration where a spring loaded door covers the aperture in the cartridge bottom providing a totally enclosed environment for the tape. The reel hubs are locked, and the tape lifters position the tape clear of the aperture. The tape hub locks, which consist of teeth on the same assembly as the tape lifters, engage rachet like teeth located on the hubs, securing the tape reels. As the cartridge is lowered into the transport, it is taken out of the parked configuration, and placed into the operated configuration. A tab, fixed in the recorder, releases the protective door over the cartridge aperture, the tape lifters are retracted after the heads and guides are in position and the hub locks are released. The reeling system is energized, tensioning the tape as the tape wraps the heads and guides. With the cartridge in place, the system is ready for operation. DESCRIPTION OF THE INVENTION The invention will be described with respect to the figures, of which: Fig. 1 is a perspective view showing the cartridge of the invention in the parked configuration, Fig. 2 is a perspective view showing the cartridge of the invention in the operate configuration, Fig. 3 is a plan view of the underside of the cartridge of the invention, and Fig. 4 shows plan and elevation views of the hub of the cartridge of the invention. Referring to Fig. 1, a cartridge 10 is shown in its parked configuration. The cartridge 10 is assembled from a lower section 12 and an upper section 14, both fabricated of plastic. A magnetic tape 20, 0.25" wide, is wound on flangeless reel hubs 16, 18, and the path of the tape span 21 between the hubs 16,18 in the parked configuration is determined by the tape lifters 22, 24. The tape lifters 22,24 are mounted on a plate 30 which is urged forward by a leaf spring 32. In the parked position, the spring 32 is extended, positioning the plate 30 towards the front of the cartridge, and the tape lifters 22,24 force the tape 20 forward in the cartridge. The tape lifters 22,24 thereby position the span 21 of the tape 20 clear of an aperture 28 in the bottom of the shell 12. The plate 30 also has teeth 36 which, in the parked configuration, engage rachet like teeth 38 of the hub 16. The teeth 38 are sharply pointed to provide steep sloping sides to insure that the teeth 36 of the plate 30 drop into the depressions between the rachet like teeth 38 of the hub 16 when the parked configuration is initiated. The locking of the hub 18 follows the identical process described above for the hub 16, except that the rachet like teeth of the hub 18 are the mirror images of the teeth on the hub 1_£ . In addition to the above described locking of the hubs 16,18, "tight winders" 40,42 which are leaf springs are fixed in the cartridge, and bear on the outermost layers of the tape packs of the hubs 16,18 at the points 44,46 where the tape 20 contacts the tape packs. The pressure exerted by the tight winders 40,42 on the tape pack helps maintain the rigidity of the packs in the parked configuration and also keeps the outermost tape layers from any tendency to unravel. It will be noted that the recording surface of the tape 20 faces inward, and, therefore, the tight winders 40,42 contact the base side of the tape 20 and not the recording surface side. The tight winders 40,42 play a further role when the cartridge is in its operating position in the recorder, which is described below. Referring to Fig. 2, the cartridge 10 is shown in its operating configuration where the bar 30 has been retracted by means of an actuator in the recorder which engages a hole in a boss 48 (See Fig. 3) located on the bar 30. On insertion of the cartridge into the recorder, the door 17, Fig.3, is tripped open. Just prior to the bar 30 being retracted but with the cartridge seated in the recorder, the heads 50 and guides 52 project into the cartridge through the aperture 28 and are facing the tape span 21, which is still being held off by the tape lifters 22,24. With movement of the bar 30 the tape lifters 22,24 move rearward in the cartridge and the tape span 21 contacts the surface of the heads 50 and the guides 52 mounted on the recorder precision plate. At the same time, the teeth 36 on the bar 30 disengage the rachet teeth 38 on the hub 16 unlocking the hub, and the splines of the hub 16 engage the appropriate reeling motor turntable. Similarly, the hub 18 is unlocked and engages its reeling motor turntable. Excitation to the reeling motors then provides torque which tensions the tape, resulting in intimate contact between the heads and the guides and the tape. Because of the high polish and smoothness of the recording side of the tape 20, air adherent to the surface of the tape tends to become entrained between turns of the tape 20 winding onto the hubs 16,18 as the tape shuttles from one hub to the other. Under operating conditions, and particularly during high speed fast forwarding and rewinding of the tape 20, the tight winders 40,42 squeegee the entrained air out from between turns of the tape 20 as it winds onto the hub acting as the take-up hub, ensuring a firm and rigid tape pack. Referring to Fig.3, the bottom view of the cartridge 10 shows the underview of the hubs 16,18 which mate with the turntables mounted on the spindles of the reeling motors of the transport. The hubs 16,18 are substantially hollow cylinders with splined interior surfaces consisting of lands 55 and grooves 54. In Fig.4, again considering the hub 16 as typical of both hubs 16,18, the teeth 38 which engage with the bar 30 for locking as previously described, are shown on the periphery of the lower rim 61 of the hub 16. The lower portions of the lands 55 of the splined interior of the hub 16 are chamfered 56 to effect concentric mating of the hub 16 and the turntable of the transport. An outer cylindrical surface 62 of the hub serves as the spool on which the tape is reeled. A cap 58, which has no voids in its surface but which is corrugated to provide compliance in the axial direction, forms the top of the hub 16 and is provided with a wear button 60 which bears against the inner surface of the upper section 12 of the cartridge. It will be appreciated that the cap 58 provides a seal which, when the cartridge is in the parked configuration, keeps dust from entering the cartridge via the splined portion of the hub. Additionally, when the driving turntable is mated with the hub 16, the turntable pressing against the rim of the hub 16 forces the wear button 60 against the interior surface of the upper section 12 slightly compressing the compliant cap 58 to provide an axial reaction force that ensures firm mating between the hub 16 and the turntable.

Claims: What is claimed is: 1. An improved cartridge (10) adapted for axial loading in a cooperating transport, said cartridge (10) comprising: a. an upper section (14) and a lower section (12) adapted to form an enclosure, b. first and second hubs (16,18) having cylindrical surfaces (62) thereon, said first and second hubs (16,18) being rotatably mounted in said enclosure, c. first and second cylindrical toothed rims (36,38) axially located on said first and second hubs (16,18), d. a magnetic tape (20) wound onto said first and said second cylindrical hub (16,18) surfaces to provide first and second reels of tape having a transportable segment (21) of said tape (20) which extends between said first reel and said second reel, the recording surface of said segment (21) being oriented to face towards the interior of said enclosure, e. an aperture (28) in the bottom surface of said lower section (12) to provide access to said recording surface of said tape segment (21) for magnetic recording or playback thereon, f. means for positioning (22,24) said tape segment (21) away from or proximate to said aperture (28), g. means for locking and unlocking (30) said hubs (16,18), conjoined for operation with said means for positioning (22,24) said tape segment (21), h. first and second compliant caps (58) located at the ends of said first and second hubs (16,18) opposite to the ends of said first and second hubs (16,18) mounted in said lower section (12), said caps (58) having wear buttons (60) extending from their upper surfaces for bearing against the inside surface of said upper section (14), wherein the overall lengths of said first and second hubs (16,18) are slightly greater than the distance from the inside top surface of said enclosure to the inside lower surface of said enclosure, wherein said first and second caps (58) are slightly compressed when said first and second hubs(16,18) are axially positioned inside said enclosure, whereby said compliantly compressed caps (58) provide axial forces directed along the axes of said first and second hubs (16,18). 2. The cartridge (10) of Claim 1 further comprising first and second spring assembly tight winders (40,42) tangentially contacting the outside layer of said first and said second reels whereby entrained air is squeegeed from said first and second reels.

Inventors: FAVROU JOHN MILTON, FAVROU, JOHN, MILTON
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1990
Main classification: G11B23
IPC codes: G11B23