WO1998018127A1

WO1998018127A1 - Belt-driven tape cartridge with improved belt for reducing slippage at tape interface

Info

Publication number: WO1998018127A1
Application number: PCT/US1997/003139
Authority: WO
Inventors: James A. Eggebeen
Original assignee: Gigatek Memory Systems
Current assignee: Gigatek Memory Systems
Priority date: 1996-10-18
Filing date: 1997-02-28
Publication date: 1998-04-30
Anticipated expiration: 1999-04-18
Also published as: AU2059797A

Abstract

A belt-driven tape cartridge having a surface texture of visible raised plateaus in a predetermined pattern that contacts the tape to be driven. The texture prevents the belt from slipping relative to the tape, especially at high tape speeds. The belt texture pattern may be formed by a pattern forming roller.

Description

BELT-DRIVEN TAPE CARTRIDGE WITH IMPROVED BELT FOR REDUCING SLIPPAGE AT TAPE INTERFACE

BACKGROUND OF THE INVENTION 1 . Field of the Invention

The present invention relates generally to magnetic tape data storage media for computer systems and, more specifically, to an improved belt for a belt-driven tape cartridge and a method of making the belt. 2. Description of the Related Art The belt-driven tape cartridge described in U.S. Patent No. 3,692,255, issued to von Behren, is used in conjunction with a tape drive unit to store and retrieve data in a computer system. The cartridge includes a base plate and a housing. Two spools are rotatably mounted in the housing on pins perpendicular to the base plate. Like the spools of other tape recording systems, the spools of the von Behren cartridge comprise a cylindrical hub with two flanges having diameters greater than that of the hub. The tape is wound around the hub between the flanges. The hubs are aligned on an axis parallel to the front wall of the housing in which the tape drive and tape read/write openings are located. The tape is driven between the hubs by means of a flexible elastic drive belt that extends around a drive roller at the front of the housing and contacts the tape on the two hubs before extending around a pair of corner rollers. The drive belt moves in response to rotation of the drive roller. When the front of the cartridge is inserted through the drive door, a capstan in the drive engages the drive roller and a read/write head in the drive engages the tape. In operation, the drive roller rotates in response to rotation of the capstan, and the tape moves past the head in response to rotation of the drive roller.

In a von Behren cartridge, the tape is magnetically encoded on one side only. The magnetic side is referred to as the front of the tape. The belt contacts the front side of the tape when it drives the tape hubs. It has been recognized that when the hub spins at high speeds, the belt tends to slip on the tape surface. One culprit apparently is air driven under the belt by the spinning hubs. The air pressure pushes on the belt causing variance in tape tension as the belt slips. This is undesirable because tape speed cannot be controlled without constant tension. In an attempt to solve this problem, U.S. Patents 4,466,564, and 4, 581 , 1 89 each to Smith et al., disclose an apparatus and a method for making such an apparatus, respectively, to promote the release of air from between the belt and the underlying tape in a von Behren type cartridge to minimize variations in tape tension and tape speed. Demand for tape cartridges capable of maintaining high tape speed has increased in view of requirements for faster data storage and retrieval. In particular, there is a growing demand for cartridges having a small form factor of about 31 inches that can maintain high tape speeds. These cartridges are known as mini-cartridges. Typical prior art mini-cartridges have operated at about 90 inches per second (ips), but there is a growing demand for mini-cartridges able to maintain tape speeds of about 1 20 ips. Unfortunately, belts made in accordance with the teachings of Smith demonstrate slippage at high tape speeds of 1 20 ips. Another disadvantage of belts made in accordance with the above- referenced Smith patents is the requirement that a microscopically small rough surface be applied. The rough belt surface of the Smith patents is disclosed as having discontinuities ranging in size from between 0.2 to 40 micrometers peak to peak, such that these discontinuities are not visible to the naked eye. The reference teaches that the disclosed polyetherurethane belt will probably damage the tape if surface roughness exceeds the disclosed microscopic range. Unfortunately, it is difficult to maintain quality control with Smith type belts because the surface cannot be inspected visually without expensive microscopes or other optical equipment. Another solution for releasing air in a tape cartridge is disclosed by

Newell in U.S. Pat. No. 4,342,809. Newell is directed to a different type of tape cartridge than the von Behren cartridge. The Newell type cartridge includes two belts, a drive belt as in the von Behren cartridge and a tensioning belt stretched over the outer peripheries of the drive roller and the belt guide rollers. Thus, the belt tension of the driving belt is directly influenced by the tension belt so that slipping can be addressed by tightening the tension belt. The Newell patent discloses either coating a metal or plastic tape with a thin elastomeric film or wounding filaments having a high modulus of elasticity within a matrix of a low modulus of elasticity. Over the years, the Newell disclosed technique has not been applied to a von Behren type cartridge, probably because the solution would be inadequate to address belt-tape slippage where no tensioning belt is available to provide additional tension.

There is clearly a long felt need in the art for a drive belt for a von Behren type cartridge that prevents slipping at the belt and tape interface at high tape speeds and which does not require microscopically small roughened surfaces.

SUMMARY OF THE INVENTION

To overcome the limitations of the prior art discussed above, and in view of other limitations which will become apparent upon reading the detailed description below, this invention provides a belt-driven tape cartridge having a belt with a visible surface texture of raised plateaus in a predetermined pattern for preventing belt slippage between the belt and the tape surface. A preferred method for forming the belt includes forming a pattern on a sheet of extruded material, cutting the sheet into rings, and stretching each ring to form the belts with the visible surface texture formed thereon.

One preferred pattern for the rings is that of visible cylindrical protrusions which results in three-dimensional rounded protrusions having elliptical faces disposed on the belt that is formed by stretching the ring. The faces are offset at non-straight angles from each other and of different sizes. The faces form the raised plateaus. An alternative pattern is that of three-dimensional rounded protrusions with elliptical faces which results in visible three-dimensional almost cylindrical protrusions on the belt formed by stretching the ring. The faces are elliptical, offset in substantially straight angles from each other and the sizes are substantially equal to each other. Still another alternative pattern is that of a cell, such as a honeycomb type structure, wherein the walls of the cell form the raised plateau texture.

Preferably, the belt is formed of at least one polyetherurethane material. Nevertheless, the belt may be made of other materials, rather than polyetherurethane. Two polyetherurethane materials may be blended into a homogenous mixture by melting both materials and mixing the molten material and forming the belt from the resulting polymeric mixture with the visible pattern disposed thereon. Optionally, a single polyetherurethane polymer may be used as the material comprising the belt if that single material has the requisite properties of flexibility and durability. BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference is now made to the following detailed description of the embodiments illustrated in the accompanying drawings in which identical numbers in various views represent the same or similar elements, and wherein:

Fig. 1 is a plan view of a tape cartridge including the belt of the present invention in a prior art compatible tape drive ;

Fig . 2 is a plan view of a drum roller used to form a visible surface texture of raised plateaus on the belt of the cartridge of the present invention shown in Fig. 1 ;

Fig. 3 is an enlarged view of the pattern on the roller of Fig. 2 that is used to create the visible surface texture of raised plateaus on the belt of the cartridge of Fig. 1 ;

Fig. 4 is a plan view of a sheet of material made by the process shown in Fig. 1 2 and having a surface texture formed by the roller of Fig. 2 and used to create the belt of the cartridge of Fig. 1 ;

Fig. 4a is an enlarged view of the surface texture of the sheet of Fig. 4;

Fig. 5 is a plan view of a ring cut from the sheet of Fig. 4; Fig. 6 is a plan view of a belt created by stretching the ring of Fig. 5 that may be used as the belt in the cartridge of Fig.1 ;

Fig. 7 is an enlarged view of the surface texture on one embodiment of the belt of Figs. 1 and 6;

Fig. 7a is a sectional view of the belt of Fig. 7 taken along sectional lines la-la;

Fig. 8 is a plan view of a ring cut from material similar in construction to the segment of Fig. 4, but showing an alternative embodiment of a predetermined pattern for creating a visible surface texture of raised plateaus; Fig. 9 is a plan view of a ring cut from material similar in construction to the segment of Fig. 4, but showing an alternative embodiment of a pre- stretched pattern for cleating a visible surface texture of raised plateaus;

Fig . 9a is a sectional view of the ring of Fig. 9 taken along section lines 9a-9a; Fig. 10 is a plan view of a belt created by stretching the ring of Fig.

9 that may be used as the belt in the cartridge of Fig .1 ; Fig. 1 1 is an enlarged view of the surface texture of the belt of Figs. 1 and 1 0;

Fig. 1 2 is a flow diagram illustrating the steps of making the belt of Fig. 1 2; Fig. 1 3 is a schematic diagram illustrating a manufacturing arrangement for making the belt of Fig. 1 ; and

Fig . 1 4 is an enlarged view of the surface texture of another embodiment of the belt of Fig. 1 .

DESCRIPTION OF PREFERRED EMBODIMENTS

Figs. 1 shows a von Behren type cartridge 1 1 for reading and writing of recording tape 1 8 by tape head 24 that is part of the drive. Data cartridge 1 1 comprises a metal base plate 1 0, a transparent plastic cover 1 2, and a pair of tape spools 1 4. Together base plate 1 0 and cover 1 2 form cartridge housing 1 3. Spools 1 4 are rotatably supported on the base plate 1 0 by cylindrical spindles 1 6 that are fixed perpendicularly into base plate 10. A magnetic recording tape 1 8 is wound around spools 14 at opposite ends and extends between spools 1 4 along a predetermined path around various fitted tape guides 20. The path extends across a tape head opening 22 in the front wall of the cartridge to provide access for a tape head 24.

A belt driving roller 26 is mounted adjacent a drive opening 28 in the front wall of the cartridge. A drive belt 30 extends around belt driving roller

26 and around belt guide rollers 32, which are rotatably mounted on base plate 1 0. The belt 30 includes a surface texture of raised plateaus in a predetermined pattern (Figs. 6-8, and 1 0- 1 1 ) on the side in approximate contact with the tape. For example a contact point 50 exists at the interface of tape 1 8 and belt 30 and the texture is on the side of belt 30 making direct contact with the tape. Belt 30 is a primary source of tension for tape 1 8, since there is no other belt in the cartridge. Referring to Fig. 1 2, a method for making the belt 30 is shown. In step 1 202, two polyetherurethane materials of different molecular weight are blended. A suitable choice for the materials is disclosed in U.S. Pat. No. 5, 1 31 ,891 , and that patent is incorporated herein in its entirety by this reference. It is known in the prior art to use a belt composed of a polyester urethane material, such as the belt disclosed by the Smith patents referenced-above. Such a prior art belt exhibits the proper dynamic response between 60 to 90 Hz, at high belt tension, and low tape tension. But lowering the belt tension and increasing the tape tension with a Smith type belt has been shown to lower the dynamic response below 60 Hz. This inability to respond is unacceptable according to industry standards for data cartridges and drives administered by Quarter-Inch Cartridge (Q.I.C.) Drive Standards, Inc. of Santa Barbara, California. Inability to meet the specifications of Q.I.C. may make a tape cartridge unacceptable to the industry. However, lowering the belt tension may increase the life of the belt. Thus, there is a need to operate with lower belt tension, but at the same time it is critical that the tape tension be held consistently as the tape speed increases otherwise, slipping may occur. The texture of the new invented belt is able to satisfy these seemingly opposed criteria, and the composition of the belt may also provide advantages.

The belt of the present invention is preferably composed of a blended polyetherurethane material composed of high and low molecular weight resins blended together. One of the resins controls the high speed response while the other controls the gross effects of cartridge performance. Thus, the cartridge dynamic response in maintained even under cases of low belt tension . In a preferred embodiment, the high molecular weight (about 260,000 m.w.) resin is a polyetherurethane known as "Pelletane"^'" polyetherurethane No. 2103-90AEF from the Dow Chemical Company and the low molecular weight (about 1 60,000 m.w.) known as "Estane"™ compound 58887 from the B.F. Goodrich Chemical Co. The two polyetherurethane materials are blended into a homogenous mixture by melting both materials and mixing the molten material. The belt is formed from the resulting polymeric mixture. Optionally, a single polyetherurethane polymer may be used as the material comprising the belt if that single material has the requisite properties of flexibility and durability.

The polyetherurethane materials may be mixed together in the form of dry pellets in a drum that blends the dry materials by spinning them together in step 1 202. In step 1 204, the dry materials are melted at about 400 degrees Fahrenheit, in a contained screw auger device that moves the molten material and extrudes it out through a narrow slot onto a substrate carrier in step 1 206. In step 1 207, the carrier with the polymeric mixture is disposed on a substrate carrier and moved by a tractor pulley arrangement about two inches through two rollers disposed on either side of the carrier and mixture. In step 1 208, the mixture is formed with a pattern by the roller in direct contact with it. It is best to have the mixture enter the pattern forming area hot to form the pattern, but leave it cold after the pattern is formed. Therefore, in step 1 209, following the formation of the pattern, the mixture is cooled on the substrate by the rollers which are water chilled. The pattern forming roller is discussed in detail below with reference to Fig. 2.

Referring again to Fig. 1 2, after the material is rolled under the pattern forming roller it continues to be moved by the tractor pulley arrangement. It is sized into appropriate width sheet or sheets by knife blades disposed in the carrier's path, in step 1 21 0. In step 1 21 2, the carrier and solidified mixture are rolled onto a tube, such as cardboard. The roll is removed from the general area and is available for the next steps, which may be performed immediately or much later. In step 1 21 4, the sheet is unrolled and rings (Fig. 5, 8, and 9, discussed below) are punched out with a die, or other suitable cutting tool. The ring is cut while still disposed on the substrate carrier, but the carrier is not cut. The die only penetrates the solidified mixture and not the carrier. The advantage of this process is that the carrier aids the completion of steps 1 207-1 21 4, but afterwards the belt can easily be removed and retrieved automatically for the stretching and finishing operation of steps 1 21 6- 1 224, discussed below. Such rings for forming belts are known, but known prior art processes do not include the paper substrate which provides the advantage of support and acts as a medium for carrying the mixture during manufacturing. It also eliminates spillage and waste. Although other carriers will work, paper is preferred. In particular, a paper having a silicone coating is a good choice because that makes the mixture easy to remove. Such a paper is available from Tribex Corp. , of San Jose, California.

The cut ring is placed over opposing mandrels in step 1 21 6. In step 1 21 8, heat is applied by raising the temperature to about 80 degrees Celsius. The mandrels are rotated and the opposing pairs are slowly pulled apart at some predetermined stretch rate to achieve uniform stretching in step 1 220. In step 1 222, the belts are allowed to cool. Since the belts are very thin cooling does not take very long. The cooled belts are removed in step 1 224, and are ready for being stretched over the belt guide rollers and drive roller as shown in Fig. 1 . Such stretching of rings is known in the tape cartridge belt forming art, but has not been combined with belts formed in accordance with all the steps of this process, and in particular not with rings removed from paper substrates, and having a visible surface texture of raised plateaus formed thereon as in the present invention. Fig. 1 3 shows a simplified schematic of a manufacturing line 1 300 for making sheets. Steps 1 202 and 1 204 occur in extruder 1 302 which contains the roller and auger. Step 1 206 occurs at the throat 1 304. Step 1 207 — disposing the mixture on the substrate carrier occurs in region 1 306. The pattern is formed and the mixture is cooled in region 1 308 (steps 1 208 and 1 209) . The sheet is sized and rolled (steps 1 21 0-1 21 2) past region 1 308 (all of manufacturing line not shown for simplicity) .

The pattern forming drum and the visible surface texture is now discussed. Fig. 2 shows the pattern forming drum 200 useful in step 1 209 of the above-described process. Fig. 3 is an enlarged view of an exemplary pattern for forming a visible surface texture on belt 30. The roller has indented circular areas disposed thereon for forming a predetermined pattern onto the material mixture. An enlarged view in Fig. 3, shows an exemplary pattern of longitudinally aligned circular indentations 300 that create a pattern on the material mixture when it cools and dries. The indentations may be made by known machining processes, such as using an end mill. A preferred embodiment of the indentations on roller 200 comprises about 720 total holes, each about 0.007 inches deep and having a diameter of about 0.031 inches. However, one skilled in the art will appreciate that other visible surface texture patterns can also prevent slippage at the belt and tape interface, and some of these alternatives are discussed below with reference to Figs. 8, and 10. The pattern discussed with reference to Fig. 7, and produced by roller 200 has been tested by the inventor and compared to cartridges having prior art belts and the results are now discussed.

Various properties may be compared, and one relevant test involves measuring tape tension and tangential drive force applied to the capstan to drive the tape, at different numbers of passes of the tape. In the tape tension test, the standard range for acceptable performance is 1 .0-3.5 ounces (force) of tension. Cartridges are measured for maximum, average and minimum tape tension. A comparison of prior art belts with the invented belt was made by installing 25 of each kind in respective mini-cartridges and operating the mini-cartridges at a tape speed of about 1 20 ips. Fourteen of the 25 prior art belts failed catastrophically, while none of the invented belts failed. Thus, the invented belt is superior to prior art belts.

Fig. 4 shows a segment of the cooled mixture forming rectangular sheet 400 on paper substrate 402. The paper substrate may be simply peeled away, because it preferably has a silicone coating allowing for easy separation. Rectangular sheet 400 may be then cut into a desirable geometric shape for forming the belt, such as a ring.

Fig . 5 shows a ring 500 cut from the sheet 400 with the paper substrate removed. The ring is cut in accordance with step 1 21 4 discussed above. Preferably, the paper is removed before cutting. The pattern 41 0 formed by pattern forming roller 200 can easily be seen disposed on surface 504 of ring 500. The patterned ring is then placed on mandrels, heated, stretched, cooled and removed in accordance with respective steps 1 21 6- 1 224 (Fig. 1 2) . Pattern 41 0 of ring 500 is formed by closely spaced cylindrical protrusions 520, in other words the reciprocal of the indentations on roller 200. Fig. 6 shows endless belt 30a (an embodiment of belt 30 of Fig. 1 ) formed by the process shown in Fig. 1 2 and having pattern 602 disposed thereon. Fig. 7 shows an enlarged view of one embodiment of pattern 602. The belt surface texture pattern 602 (result of stretching pattern 410) is a series of visible three dimensional protrusions 690 having elliptical faces 61 0. The shape of the faces results from stretching corresponding cylindrical protrusions disposed on ring 500. Each elliptical face is disposed at non-straight angles to the other faces. Note that those near its inner diameter (d,) are stretched more along the resulting major axis of the elliptical face than those located closer to the outer diameter (d₀) of the ring so they are longer along the major axis. Following the stretching, the protrusions are visible to the human eye. According to the IES Lighting handbook, 1 981 , IESNA, New York, New York, visual acuity describes the visibility of fine details that can be discerned by the naked eye. Below 40 micrometers, details cannot be observed without a microscope. The protrusions of the belt of the present invention are clearly visible and therefore must exceed 40 micrometers in height. Referring to Figs 7 and 7A (sectional view taken along lines 7A - 7A of Fig. 7), the surface texture pattern 602 of the raised plateaus is shown. Preferably, each face 61 0 is smooth having very little surface roughness. Similarly, each valley region 620 between plateaus is also smooth. However, one or more of the faces may be rough, and one or more valley regions may also be rough. Thus, any belt surface that may contact the tape is smooth. It is surprising that a smooth surface would have the effect of preventing belt slippage at high tape speed and particularly when the overall surface texture is visible. This is contrary to the teachings of the prior art, especially those of the Smith patents that teach the necessity of a microscopically rough surface to prevent belt slippage while simultaneously avoiding tape damage. The present belt is not microscopically rough, rather it has a visible pattern of raised plateaus wherein the faces of the plateaus are smooth relative to the rest of the tape surface. The preferred height of the protrusions (h) (Fig. 7A) is less than or equal to .007 inches (about 1 77 micrometers) measured from the bottom of tape portion 620 in the valley region to the top of plateau 61 0. The tape portion 620 (valley floor) has a thickness (t) of about .002 inches. Therefore the additional height over the normal belt thickness is about .005 inches or (h-t). Preferably, the raised protrusions cover between about 20% to 80% of the surface area of the belt measured across the width of the tape W. For example, in the embodiment discussed with reference to Figs. 6 and 7, measurements and calculations were made with a sample specimen. The sample specimen fell in about the middle of the preferred range. In the sample, about 101 raised protrusions covered an exemplary rectangular area of belt, about 3/1 6" wide and about 1 " long. The raised plateau faces covered about 57% of the overall surface area. Before stretching there were about 1 45 protrusions over the same area, covering about 58% of the overall surface. This raised visible surface of elliptically faced raised plateaus has been empirically shown to prevent slippage at the belt tape interface even at high tape speeds. It provides advantages of reducing variance of tape tension and speed, even at high speeds. Moreover, high tape speeds and low belt tension can be achieved in cartridge 1 1 having belt embodiment 30a of invented belt 30 with pattern 602 disposed thereon. The inventor has discovered that the belt texture created in accordance with the preset invention yields unexpectedly superior results over the prior art. Possibly, lowering overall belt tension by using a polyetherurethane material is a significant contributor to the overall superiority by decreasing the chance of tape damage. Additionally, having a smooth plateau on the raised protrusion may contribute to lowering the risk of tape damage and provides superiority over a generally rough, even randomly dispersed texture pattern as in prior art belts. The visible surface texture provides a benefit of ease of manufacturing and particularly with regards to quality control.

Fig. 14 shows another embodiment of a visible surface texture pattern 1 400 of raised plateaus, wherein faces 1 41 0 are elliptically faced as in pattern 602, but there are no valleys between face 1 420 which runs continuously without valley regions interrupting the texture. Face 1420 is substantially at least two raised plateaus connected without valley regions in between.

Fig. 8 shows another embodiment of a visible surface texture pattern 800 that is a series of closely spaced cells 802 shaped as a polygon, each having a chamber 804, where air may collect. Preferably, polygon-shaped cell 802 has a honeycomb or hex geometry, but other cell shapes will suffice. In contrast to the teachings of prior art the inventor has made the critical recognition that it is not always necessary for air to be released between the tape and belt to prevent slippage. This discovery is also very surprising and counter to the beliefs of those skilled in the art. The inventor has recognized that as long as the cell is sized so that a volume of air may be carried in chamber 804 that is substantially greater than the volume of air that might be pulled in, the chamber will be at a lower pressure and will draw air into the chamber without creating a vacuum effect or expanding. The surfaces of the chamber walls 803 disposed to contact the tape serve as raised plateau faces for the belt to provide advantages similar to pattern 602.

Figs. 9, 9a, and 10 show an alternative visible surface texture pattern 900 and 922 formed on ring 902, and belt 30b (an embodiment of belt 30 of Fig. 1 ), respectively. Fig. 1 1 shows an enlarged view of the pattern formed on the belt. The pattern may be formed by a drum, similar to the drum of Fig. 2, by employing known numerical control methods to form a suitable pattern forming surface. The preferred geometry of pattern 900 is that of closely spaced rounded three-dimensional protrusions that start at the inner diameter d, of ring 902 (only a portion shown) with a first structure 904 having a circular face 906 of radius 908. As the diameter of the ring increases, moving toward outer diameter d₀ of ring 902, each three- dimensional protrusion's face becomes elliptically shaped. For example, face 91 0 of protrusion 91 2 is elliptically shaped having an minor axis 91 4 equivalent to radius 908. However, the major axis of elliptical face 91 0 is greater than radius 908. Additionally, each succeeding protrusion, such as protrusion 920, proceeding toward the outer diameter of ring 902, has an elliptical face with a minor axis equivalent to minor axis 91 4 but with a larger major axis than each preceding protrusion. Each protrusion is centered along a radial line, such as radial line 91 6, and each is located by polar (circular) coordinates rather than Cartesian (rectangular) components. This arrangement of the pattern is based on the inventor's critical recognition that protrusions disposed near the inner diameter (d,) of ring 902 (e.g. protrusion 91 2) will be stretched more along their major axis than will the major axes of protrusions such as protrusion 91 2 disposed nearer the outer diameter of ring 902 when the belt is formed in accordance with steps 1 21 6- 1 224.

Referring to Figs. 1 0 and 1 1 , the resulting pattern 922 (pattern 900 after stretching) is that of raised protrusions having substantially equal elliptical faces but aligned in straight columns. The ellipses are at straight angle offsets to each other's ellipse. In other words, the stretching aligns the radials disposed rounded pattern of combined circular faced and elliptical faced protrusions of ring 902 into columns in a reverse fashion that the raised cylindrical protrusions 520 on ring 500 are converted into three- dimensional elliptically faced protrusions disposed on an arcuate path. The surface texture provided by pattern 922 yields the same advantages of above-described pattern 602, because each protrusion face provides a smooth plateau. For any uniform area there is a predetermined area of protrusions dispersed across the width of the belt and preferably in approximately the same ratio (about 57% of the surface of the belt) . The difference between the height of the protrusion and the thickness of the tape is preferably equivalent to pattern 602. Additionally, the pattern 922 provides a similar ratio of area of protrusions to the total area of the belt over a uniform area as pattern 602 (Figs. 6 & 7) . Thus, the same unexpected superiority as with belt 30a will be possible with a belt having the surface texture of belt 30b.

With each of the above described patterns, the belt of Fig. 1 can be formed, offering superior performance regarding maintaining constant tape tension at high speed and without quality control methods requiring expensive optical equipment, such as is the case with prior art microscopically rough surfaces.

A belt with a visible surface texture of raised plateaus in a predetermined pattern for preventing belt slippage and maintaining constant tape tension and a method of making the same has been shown.

Modifications may occur to those skilled in the art in view of the teachings above. Therefore this invention is only to be limited by the claims appended below and their equivalents.

Claims

1 . A data storage tape cartridge positionable in a drive having drive means, the cartridge comprising: a cover having a front, back, top, and first and second sides; a base plate having a front and a back and a top surface, the base plate top surface having mounted to the cover to form a housing; a media access opening formed in the front of the housing; a drive opening formed in the front of the housing; two hubs rotatably mounted in the housing; tape media wrapped around the two hubs in the housing to form two tape packs, the tape media being accessible from the outside of the housing through the media access opening; a belt driving roller rotatably mounted in the housing and accessible to the drive means through the drive opening; a pair of belt guide rollers rotatably mounted in the housing; and an elastic belt wrapped around the belt driving roller, belt guide rollers, and the two tape packs for rotating the hubs in response to rotation of the belt driving roller by the drive means, the elastic belt having a first surface facing the tape of the two tape packs, and the first surface having a visible surface texture including raised plateaus in a predetermined pattern disposed thereon for preventing belt slippage at a contact interface of the belt and the tape.

2. The data cartridge of claim 1 , wherein each plateau of the belt has a smooth face.

3. The data cartridge of claim 1 , wherein the belt has a second surface facing away from the tape of the two tape packs and each plateau face is raised a substantially equal predetermined height measured from the second surface to the raised plateau portion of the first surface.

4. The data cartridge of claim 1 , wherein at least two of the raised plateaus are connected without a valley region disposed between the two connected plateaus.

5. The data cartridge of claim 4, wherein the height of each raised plateau is between about 0.005 inches and 0.01 0 inches.

6. The data cartridge of claim 3, wherein the visible surface texture includes a plurality of valley regions, and each valley region is disposed between each raised plateau and has a side disposed facing the tape.

7. The data cartridge of claim 6, wherein the side of the valley region disposed facing the tape is smooth.

8. The data cartridge of claim 6, wherein a distance from the second surface of the belt to the side of the valley region closest to the tape defines a thickness of the belt, and the difference between the height of each raised plateau and the belt thickness is greater than about 0.005 inches.

9. The data cartridge of claim 1 , wherein the predetermined pattern comprises a pattern of polygon-shaped cells and the raised plateaus are formed by walls surrounding the cells.

1 0. The data cartridge of claim 1 , wherein the belt has a width and a length, and the raised plateaus cover between 20 and 80% of an area on the first surface bounded by the width and any portion of the length.

1 1 . The data cartridge of claim 1 , wherein the predetermined pattern comprises raised three-dimensional protrusions, each protrusion having an elliptical face that forms the plateau surface.

1 2. The data cartridge of claim 1 1 , wherein the elliptical faces are of various sizes and each elliptical face is offset from each other elliptical face at non-straight angles.

1 3. The data cartridge of claim 1 1 , wherein the belt has a width, and each elliptical face is substantially equal in size to each other elliptical face, and each elliptical face is disposed in a respective columnar group of a plurality of columnar groups, each group having a plurality of elliptical faces aligned in a straight column across the width of the tape.

1 4. The data cartridge of claim 1 , wherein the elastic belt is comprised of at least one polyetherurethane material.

1 5. The data cartridge of claim 1 , wherein the elastic belt is comprised of a first polyetherurethane material and a second polyetherurethane material.

1 6. The data cartridge of claim 1 5, wherein the first polyetherurethane material has a lower molecular weight than the second polyetherurethane material.

1 7. The data cartridge of claim 1 6, wherein the first polyetherurethane material is estane and the second polyetherurethane material is Pelletane.

1 8. In a data storage tape cartridge having a cover having a front, back, top, and first and second sides, and a base plate having a front and a back and a top surface, the base plate top surface being mounted to the cover to form a housing with a media access opening formed in the front of the housing, and the housing having a drive opening formed in the front of the housing, and the housing further having two hubs rotatably mounted in the housing, and tape media wrapped around the two hubs in the housing to form two tape packs, and the tape media being accessible from the outside of the housing through the media access opening, and the housing also having a belt-driving roller rotatably mounted in the housing and accessible to the drive means through the drive opening, and the housing also having a pair of belt guide rollers rotatably mounted in the housing, an improved belt for driving the roller, the belt comprising: an elastic belt having a first surface facing the tape of the two tape packs, and the first surface having a visible surface texture of raised plateaus in a predetermined pattern disposed thereon for preventing belt slippage at an interface of the belt and the tape.

1 9. The belt of claim 1 8, wherein each plateau of the belt has a smooth face.

20. The belt of claim 1 8, wherein the belt has a second surface facing away from the tape of the two tape packs and each plateau face is raised a substantially equal predetermined height measured from the second surface to the raised plateau portion of the first surface.

21 . The belt of claim 20, wherein the height of each raised plateau is between about 0.005 inches and 0.01 0 inches.

22. The belt of claim 20, wherein the visible surface texture includes a plurality of valley regions, each valley region disposed between each raised plateau and having a side disposed facing the tape.

23. The belt of claim 22, wherein the side of the valley region disposed facing the tape is smooth.

24. The belt of claim 23, wherein a distance from the second surface of the belt to the side of the valley region closest to the tape defines a thickness of the belt, and the difference between the height of each raised plateau and the belt thickness is about 0.005 inches.

25. The belt of claim 1 8, wherein at least two of the raised plateaus are connected without a valley region disposed between the two connected plateaus.

26. The belt of claim 1 8, wherein the predetermined pattern comprises a pattern of polygon-shaped cells and the plateaus are formed by walls surrounding the cells.

27. The belt of claim 1 8, wherein the belt has a width and a length, and the raised plateaus cover between 20% and 80% of an area on the first surface bounded by the width and any portion of the length.

28. The belt of claim 1 8, wherein the predetermined pattern comprises raised three-dimensional protrusions, each protrusion having an elliptical face that forms the plateau surface.

29. The belt of claim 28, wherein the elliptical faces are of various sizes and each elliptical face is offset from each other elliptical face at non- straight angles.

30. The belt of claim 28, wherein the belt has a width, and each elliptical face is substantially equal in size to each other elliptical face, and each elliptical face is disposed in a respective columnar group of a plurality of columnar groups, each group having a plurality of elliptical faces aligned in a straight column across the width of the tape.

31 . The belt of claim 1 8, wherein the elastic belt is comprised of at least one polyetherurethane material.

32. The belt of claim 1 8, wherein the elastic belt is comprised of a first polyetherurethane material and a second polyetherurethane material.

33. The belt of claim 32, wherein the first polyetherurethane material has a lower molecular weight than the second polyetherurethane material.

34. The belt of claim 33, wherein the first polyetherurethane material is estane and the second polyetherurethane material is Pelletane.

35. A manufacturing roller assembly for forming a predetermined pattern on a sheet of material that is formed into an elastic belt for a belt- driven data cartridge, the roller assembly comprising: a substantially cylindrical drum having an outer surface; a plurality of visible indentations disposed on the outer surface in a predetermined pattern, each indentation forming a cavity on the outer surface, each cavity having a round opening at a first end disposed closest to the outer surface and being closed at a second end that is disposed distal to the first end for allowing a belt forming mixture to flow into the cavity at the opening for forming a belt surface texture of raised plateaus in accordance with the predetermined pattern that the plurality of visible indentations are disposed on the drum.

36. The manufacturing roller assembly of claim 35, wherein the round opening of each cavity is circular and each cavity is a substantially cylindrical bore.

37. The manufacturing roller assembly of claim 36, wherein each cavity, in relation to each other cavity, has a substantially equal height measured from the first end to the second end and a substantially equal diameter of the circular opening.

38. The manufacturing roller assembly of claim 35, wherein at least one of the round openings is elliptically shaped.

39. A method of making an elastic belt for a data storage tape cartridge positionable in a drive having drive means, wherein the cartridge has a housing with two hubs rotatably mounted in the housing, tape media wrapped around the two hubs in the housing to form two tape packs, a belt driving roller rotatably mounted in the housing and accessible to the drive means through a drive opening, a pair of belt guide rollers rotatably mounted in the housing, and wherein the elastic belt is wrapped around the belt driving roller, belt guide rollers, and the two tape packs for rotating the hubs in response to rotation of the belt driving roller by the drive means, the elastic belt having a first surface facing the tape of the tape of the two tape packs, the method comprising the steps of:

(a) placing at least one polyetherurethane material in a container;

(b) melting the at least one polyetherurethane material to form a melted mixture;

(c) extruding the melted mixture onto a substrate carrier;

(d) forming a visible surface texture on the melted mixture in a predetermined pattern;

(e) cooling the melted mixture on the substrate carrier to form a sheet having the visible surface texture in a predetermined pattern;

(f) cutting a ring from the sheet; and (g) stretching the ring to form a belt comprised of an endless loop having a visible surface of raised plateaus disposed thereon in a predetermined pattern for preventing belt slippage at a contact interface of the belt and the tape when installed in the cartridge.

40. The method of claim 39, wherein the step of forming a visible surface texture on the melted mixture is preceded by a step of providing a manufacturing roller assembly that is a substantially cylindrical drum having an outer surface with a plurality of visible indentations disposed on the outer surface in a predetermined pattern, each indentation forming a cavity on the outer surface having a round opening at a first end disposed closest to the outer surface and being closed at a second end disposed distal to the first end for allowing the melted mixture to flow into the cavity at the opening for forming the visible surface texture.

41 . The method of claim 40, wherein the round opening of each cavity of the provided manufacturing roller assembly is circular and each cavity is a substantially cylindrical bore extending from the first end to the second end and having a consistent diameter.

42. The method of claim 41 , wherein each cavity, in relation to each other cavity, has a substantially equal height measured from the first end to the second end and a substantially equal diameter of the circular opening.

43. The method of claim 42, wherein at least one of the round openings is elliptically shaped.

44. The method of claim 39, wherein the elastic belt is comprised of at least one polyetherurethane material.

45. The method of claim 39, wherein the elastic belt is comprised of a first polyetherurethane material and a second polyetherurethane material.

46. The method of claim 45, wherein the first polyetherurethane material has a lower molecular weight than the second polyetherurethane material.

47. The method of claim 46, wherein the first polyetherurethane material is estane and the second polyetherurethane material is Pelletane.

48. The method of claim 47, wherein the stretched predetermined pattern on the belt comprises raised three-dimensional protrusions, each protrusion having an elliptical face that forms the plateau surface.