GB2279489A - A tape guide roller with fixed edge guides - Google Patents

Abstract

A tape drive machine having guide rollers 18, 20 with fixed lower flanges 46 to guide the lower edge of the tape; air bearings 14, 16 with upper tape edge guides which are supported by torsionally highly flexible cantilevers to permit the guides to adapt to their position to run flat on the upper edge of the tape; air bearings with relatively few air holes 76 joined by grooves 80; a lacing mechanism 82 - 98 with a part-circular arcuate path for a leader block pin 98; and a tape path which is a mirror-image symmetrical about the central axis 108 of the head 12. <IMAGE>

Description

TAPE DRIVE MACHINES This invention relates to tape drive machines and is particularly, but not exclusively, concerned with machines for use with single reel cartridges according to the IBM GS 32-0048-0, ECMA 120 or ANSI X385-87-037 specification, such as the IBM 3480 cartridge. The invention is however, applicable to other tape machines and for use with optical and other tapes in addition to magnetic tapes.

Tape guide rollers are sometimes used in tape drive machines where the direction of the tape path needs to be changed, and usually the roller has a cylindrical portion around which the tape runs, and a flange for guiding the lower edge of the tape. It has been noticed that, at the periphery of the flange, a vibration can sometimes occur due to the component of peripheral velocity of the flange in the direction parallel to the tape thickness. Such vibrations can ultimately cause damage to the tape or affect the quality of data recording or reproduction. A first aspect of the present invention is concerned with this problem.

In accordance with the first aspect of the invention, there is provided a tape drive machine comprising a baseplate, a head mounted on the baseplate and means defining a path for a tape from one reel to another reel past the head, the tape path defining means including at least guide roller mounted on the baseplate for rotation about an axis perpendicular to the baseplate and a respective guide surface adjacent the roller and parallel to the baseplate for guiding that edge of the tape nearer the baseplate. This aspect of the invention is characterised in that the guide surface is stationary relative to the baseplate. For example, the guide surface may be provided by a raised surface of the baseplate. Thus there is no relative velocity component between the tape and the guide surface is the thickness direction of the tape.

Especially in the case where there is a plurality of such guide rollers and respective guide surfaces, the guide surfaces are preferably prepared in a single manufacturing step so that the guide surfaces are coplanar. This helps to improve the total characteristics of the tape path. In contrast, in the case where the guide surfaces are provided by flanges on the rollers, it is necessary to try to line up all of the rollers so that their guide surfaces are coplanar.

A second aspect of the present invention is concerned with air bearings for tape drive machines, which have previously been placed in the tape path to either side of the head. Such air bearings enable the tape path direction to be changed with little frictional loss and with consistency in the drag applied to the tape. They have been combined with guides which control the position of the tape in its transverse direction, and in one known arrangement one edge of the tape runs against a first fixed guide surface, and the other edge of the tape is engaged by a second guide surface in the form of a ceramic button at one end of a cantilever which is biased towards the first guide surface. Because the cantilever is resilient, it can accommodate slight variations in the width of the tape, but if the delicate resilient cantilever is accidentally twisted or bent, it can produce different drag characteristics in dependence upon the direction of travel of the tape. The second aspect of the invention is concerned with this problem.

In accordance with the second aspect of the invention, there is provided an air bearing for a tape drive machine, comprising: a block having a bearing surface across which one side of a tape can pass, and a plurality of air outlets in the bearing surface through which air can be passed; a first guide surface at right angles to the bearing surface for guiding one edge of the tape; and a cantilever member having one end fixed, and the other end providing a second guide surface facing and biassed towards the first guide surface for guiding the other edge of the tape; characterised in that the width of the cantilever member between its two ends is narrower than the width thereof at said other end.

Thus, there is little torsional rigidity in the cantilever member and it can adapt itself so that it runs flat on said other edge of the tape.

Preferably, the cantilever member does not, or does not completely, provide the bias against said other edge of the tape, but is assisted by a second, resilient cantilever member having one end fixed and the other end bearing against said other end of the first mentioned cantilever member to bias the second guide surface towards the first guide surface.

As mentioned above, in the known arrangement a separate ceramic button is fixed to the end of the cantilever member. Preferably, in the second aspect of the invention, the second guide surface has a hard (eg diamond) coating, so as to simplify the manufacturing process.

For better guiding of said other edge of the tape, the first cantilever member may be one of a plurality of such cantilever members, said one ends thereof being joined together, and said other ends thereof being aligned for guiding said other edge of the tape.

In the previously mentioned method of manufacture of a tape drive machine where the guide surfaces for the rollers are prepared in the same manufacturing step, if the machine includes an air bearing according to the second aspect of the invention, said first guide surface of the air bearing is preferably prepared in the same manufacturing step as the guide surfaces for the guide rollers.

A third aspect of the present invention is also concerned with air bearings for tape drive machines. In a typical known air bearing1 perhaps 60 or 70 air outlets are provided. They use a considerable amount of air, requiring a relatively large pump, and manufacture is costly. The third aspect of the invention is concerned with these problems.

It has been found that feeding the air outlets into grooves in the bearing surface provides a sufficiently good air bearing effect, with reduced manufacturing costs, and the air consumption of the air bearing is reduced so that a smaller capacity pump can be used.

Accordingly, the third aspect of the invention provides an air bearing for a tape drive machine, comprising: a block having a bearing surface across which one side of a tape can be passed; and a plurality of air outlets in the bearing surface through which air can be passed to hold the tape off the bearing surface; characterised in that the bearing surface has a plurality of grooves therein extending in the same direction as the tape travel direction, at least one of the air outlets feeding into each groove.

Preferably, a plurality of the air outlets feed into each groove, for example two, three or four air outlets per groove. It has also been found that a very large number of grooves are not required, and preferably the air bearing has two, three or four such grooves.

A fourth aspect of the present invention is concerned with lacing and unlacing a tape drive machine, that is loading the tape into the tape path and unloading it back into the cartridge. There have been many previous proposals concerned with lacing and unlacing, with mechanisms employing many linkages, levers, gears, chains and cables.

The fourth aspect of the invention is concerned with providing a very simple and effective lacing arrangement.

In accordance with the fourth aspect of the invention, there is provided a tape drive machine comprising means to hold a tape cartridge, a head, a take-up reel, and a lacing means for moving a leader block of the tape cartridge between an unlaced position in the tape cartridge and a laced position in the take-up reel with the tape following a path from the cartridge. past the head to the take-up reel; characterised in that the lacing means moves the leader block in a part-circular arcuate path between the unlaced and laced positions. By using an arcuate path, the mechanism necessary to define that path can be relatively simple.

In one embodiment, the lacing means comprises a rotatable member, drive means for rotating the rotatable member and a leader block pin mounted on the rotatable member.

Preferably, the rotatable member is annular, so that, for example, wiring connections can pass through the middle of it, and in this case the annular member may be supported for rotation by a plurality of supports engaging an inner edge of the annular member, an outer edge of the annular member being toothed, and the drive means comprising a motor having a pinion which engages the toothed edge of the annular member.

Typically it requires a force of 12N to withdraw a leader block from an IBM 3480 cartridge, and with the earlier complicated arrangements with a leader block pin at the end of an arm, the motor torque required can be considerable. Preferably, with the fourth aspect of the invention the direction of movement of the leader block pin as the lacing means leaves the unlaced position is generally aligned with a direction in which least force is required to withdraw the leader block from the tape cartridge.

A fifth aspect of the invention is concerned with consistency of the tape flow. As the size of tape drive machines has been reduced and the lacing mechanisms have become more complicated, so too has the tape path become more complex. A relatively tight turn in the tape upstream of the head can cause complications for which compensation needs to be made elsewhere. However, when the tape is running in the opposite direction the complications differ, and different compensation may be required. The fifth aspect of the invention is concerned with this problem.

In accordance with the fifth aspect of the invention there is provided a tape drive machine comprising means for holding a tape cartridge, a take-up reel, and in a path for tape from the cartridge to the take-up reel: a first guide roller, a first air bearing, a head, a second air bearing, and a second guide roller in that order; characterised in that the tape path from the first guide roller to second guide roller is mirror-image symmetrical about a bisecting plane of the head. Thus, the tape flow characteristics at the head will be very similar irrespective of the direction of travel of the tape.

Although any variations in the tape path between the cartridge reel and the first guide roller, and between the second guide roller and the take-up reel, have only a secondary effect on the tape flow characteristics at the head, preferably when the take-up reel is half-full, the tape path from the reel in the cartridge to the take-up reel is generally mirror-image symmetrical about the bisecting plane of the head.

Although five differing aspects of the invention have been described above, it will be appreciated that any two or more of those aspects may be combined into a single machine.

A specific embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a plan view of a tape drive machine with a lacing wheel removed; Figure 2 is a sectional view of a guide roller, taken along the line 2-2 in Figure 1; Figure 3 is a sectional view of an air bearing taken along the line 3-3 in Figure 1; Figure 4 is a plan view of part of the air bearing; Figure 5 is a view of the air bearing as seen in the direction of 5 shown in Figure 3; Figure 6 is a plan view of the tape drive machine with lacing wheel; Figure 7 is a sectional view taken along the line 7-7 in Figure 6.

Referring to Figure 1, the tape drive machine comprises a baseplate 10, on which is mounted a head 12, a pair of air bearings 14,16, a pair of guide rollers 18,20 and a take-up reel 24.

The take-up reel 24 is driven by a motor mounted beneath the baseplate.

Also mounted on the baseplate 10 is a bay (not shown), for removably holding an IBM 3480 tape cartridge 26, and a drive hub for the tape cartridge 26 is mounted beneath the baseplate 10. In use, a tape 28 extends from a reel within the tape cartridge 26, past the first drive roller 18, past the first air bearing 14, past the head 12, past the second air bearing 16, past the guide roller 20 and onto the take-up reel 24, where a leader block 30 at the end of the tape 28 resides in a slot 32 in the take-up reel.

Figure 2 shows one of the guide rollers 18. The roller 18 has a first cylindrical portion 34, a second, smaller diameter cylindrical portion 36 which enters a hole 38 in the baseplate 10, and a third, smaller diameter cylindrical portion 40 which is fitted into a ball-bearing assembly 42 mounted in a recess 44 in the baseplate 10.

Around the hole 38, the baseplate has a raised portion 46 with a flat upper surface 48, and this surface 48 provides the guide surface for the lower edge 50 of the tape 28 as the tape passes around the roller 18.

Although only one ball-bearing assembly is shown in the drawing, it will be appreciated that two ball-bearing assemblies may be employed, if desired.

The other guide roller 20 is similarly formed, and during the manufacturing process for the baseplate 10, the upper surfaces 48 of the raised portions 46 for both guide rollers 18,20 are ground in the same grinding operation so as to ensure, as far as possible, that the guide surfaces are coplanar.

Figure 3 shows one of the air bearings 14. The air bearing 14 comprises a ceramic plate 52 secured to the baseplate 10 and a hollow block 54 secured on top of the ceramic plate. The block 54 has a slightly curved front surface 56 over which the tape 28 passes, with the lower edge 50 of the tape being guided by the upper surface 58 of a projecting portion of the ceramic plate 52. The upper edge 60 is guided by a device as shown in Figure 4 formed from sheet material.

The device of Figure 4 has a root portion 62 from which five parallel narrow fingers 64 project. The tips 66 of the fingers are wider, so that the series of five tips almost, but do not quite, touch each other. The tips 66 rest on the upper edge 60 of the tape, and to improve the wearing properties of the tips 66, they are coated with a hard material, for example of diamond. Mounted on the block 54 above the member of Figure 4 is a further member which is somewhat similar to that of Figure 4, except that the fingers 68 are wider and are bent gently upwardly for most of the length of the fingers before being bent sharpwardly downwardly so that the ends 70 of the fingers 68 bear down on the tips 66 of the fingers 64. The fingers 68 are resilient and are arranged so that they apply a downward biasing force on the tips 66 towards the lower guide surface 58 so as to control the lateral position of the tape 28. Because the fingers 64 are so narrow, they have little torsional rigidity, and therefore, the tips 66 can twist in the direction shown by the arrow 72 in Figure 5 so that they can adapt themselves to lie flat against the upper edge 60 of the tape 28.

It will be recalled in connection with the description of Figure 2, that the guide surfaces 48 are ground in a single operation.

Advantageously, the upper surfaces 58 of the ceramic plates 52 may also be ground as part of the same operation.

Referring to Figures 3 and 5, the block 54 has an inlet port 74 for the supply of air under pressure, and a three by three array of nine holes 76 are formed through the wall of the block 54 which provides the bearing surface 56. The bearing surface 56 is formed with three horizontal grooves 80, each groove 80 being aligned with three of the holes 76, so that the holes 76 feed the grooves 80 with pressurised air. Preferably, the ends of the grooves are closed, so that air cannot readily escape from the ends of the grooves. It has been found that, by providing the grooves 80 it is not necessary to provide as many holes 76 as are used in the earlier air bearing arrangement.

Also, it has been found that the number of grooves which it is necessary to provide are less than the number of holes which have been provided in the height direction in the earlier arrangements. Because, in this embodiment, only nine holes are provided the air consumption of the air bearing is smaller than the earlier devices. Whilst a three by three array has been shown in the drawings, it will be appreciated that different arrangements can be employed, for example, two, three or four grooves, each with two, three or four holes.

Referring back to Figure 1, a lacing motor 82 with a driving pinion 84 is mounted near one corner of the baseplate 10, and three support columns 86 are also provided. Referring to Figures 6 and 7, a bracket 87 and pulley 88 is mounted at the top of each column 86, and the three pulleys 88 between them hold an annular lacing wheel 90 by engaging the inner periphery 92 of the wheel 90. The brackets 87 are held on the columns 86 by screw 94, so that the brackets 87 and pulleys 88 can be removed1 and then the lacing wheel can be taken off for maintenance or to facilitate access to other parts of the machine. The outer periphery 96 of the lacing wheel is toothed and meshes with the pinion 84 of the lacing motor 82. A lacing pin 98 depends from the lacing wheel 90 and has an enlarged portion 100 at the lower end of the pin 98. As is well known, and as shown in Figure 7, the leader block 30 for an IBM 3480 tape cartridge has a stepped hole 102,104 and a slot 106 of generally the same width as the diameter of the smaller portion 102 of the hole.

In operation, in order to lace a tape from the cartridge 26, the wheel 90 is rotated clockwise (as seen in Figure 6) until the pin 98 enters the slot 106 in the leader block 30. The cartridge 26 is then lowered by a mechanism not shown, so that the enlarged portion 102 of the lacing pin 98 enters the larger portion 104 of the hole in the leader block. The wheel 90 is then rotated anti-clockwise by about 270 pulling with it the leader block 30 and the tape 28. Once the lacing wheel 90 has completed its travel, the leader block 30 is located in the slot 32 in the take-up reel 24 with the lacing pin 98 being coaxial with the axis of rotation of the take-up reel 24, so that the latter can be rotated to draw the tape from the cartridge 26 past the guide rollers 18,20 the air bearings 14,16 and the head 12.

In order to unlace the machine, the drive hub for the cartridge 26 is rotated until there is no tape left on the take-up reel 24, and the take-up reel is adjusted so that the slot 32 is tangential to the lacing wheel 90. The lacing wheel 90 is then rotated approximately 2700 clockwise, with the drive hub for the tape cartridge 26 also being rotated to take up the slack in the tape. The leader block 30 is thus returned to its position in the cartridge 26, and the cartridge can then be raised so that the enlarged portion 100 and the lacing pin 98 is clear of the leader block and the cartridge can then be removed.

Suitable sensors may be provided on the lacing wheel 90 to determine when it is in its two end positions. Suitable sensors may also be provided on the take-up reel 24 to determine when it is empty of tape and when the slot 32 is tangential to the lacing wheel 90.

It should be noted that, in the arrangement shown in Figure 6, the tape path is mirror-image symmetrical about the plane 108 which bisects the head 12. Therefore, the air bearings 14,16 are arranged as mirror-images of each other, and the guide rollers 18,20 are arranged as mirror-images of each other about that plane. Furthermore, the cartridge 26 and the take-up reel 24 may be arranged so that, when the take-up reel 24 is half full with tape, the tape passed between the cartridge 28 and the guide roller 18 is a mirror-image of the tape path between the take-up reel 24 and the guide roller 20.

Whilst one specific embodiment of the invention has been described, it will be appreciated that many modifications and developments may be made thereto without parting from the scope of the invention.

Claims (23)

1. A tape drive machine comprising a baseplate, a head mounted on the baseplate and means defining a path for a tape from one reel to another reel past the head, the tape path defining means including at least guide roller mounted on the baseplate for rotation about an axis perpendicular to the baseplate and a respective guide surface adjacent the roller and parallel to the baseplate for guiding that edge of the tape nearer the baseplate, characterised in that the guide surface is stationary relative to the baseplate.

2. A machine as claimed in Claim 1, wherein the guide surface is provided by a raised surface of the baseplate.

3. A machine as claimed in Claim 1 or 2, wherein a plurality of such guide rollers and respective guide surfaces are provided.

4. A method of manufacturing a machine as claimed in Claim 3, wherein the guide surfaces are prepared in a single manufacturing step so that the guide surfaces are coplanar.

5. An air bearing for a tape drive machine, comprising: a block having a bearing surface across which one side of a tape can pass, and a plurality of air outlets in the bearing surface through which air can be passed; a first guide surface at right angles to the bearing surface for guiding one edge of the tape; and a cantilever member having one end fixed, and the other end providing a second guide surface facing and biassed towards the first guide surface for guiding the other edge of the tape; characterised in that the width of the cantilever member between its two ends is narrower than the width thereof at said other end.

6. An air bearing as claimed in Claim 5, further comprising a second, resilient cantilever member having one end fixed and the other end bearing against said other end of the first mentioned cantilever member to bias the second guide surface towards the first guide surface.

7. An air bearing as claimed in Claim 5 or 6, wherein the second guide surface has a hard (eg diamond) coating.

8. An air bearing as claimed in any of Claims 5 to 7, wherein the first cantilever member is one of a plurality of such cantilever members, said one ends thereof being joined together, and said other ends thereof being aligned for guiding said other edge of the tape.

9. A method as claimed in Claim 4 for manufacturing a tape drive machine having an air bearing as claimed in any of Claims 5 to 8, wherein said first guide surface of the air bearing is prepared in the same manufacturing step as the guide surfaces for the guide rollers.

10. An air bearing for a tape drive machine, comprising: a block having a bearing surface across which one side of a tape can be passed; and a plurality of air outlets in the bearing surface through which air can be passed to hold the tape off the bearing surface; characterised in that the bearing surface has a plurality of grooves therein extending in the same direction as the tape travel direction, at least one of the air outlets feeding into each groove.

11. An air bearing as claimed in Claim 10, wherein the ends of each groove are closed.

12. An air bearing as claimed in Claim 10 or 11, wherein a plurality of the air outlets feed into each groove.

13. An air bearing as claimed in Claim 12, wherein two, three or four of the air outlets feed into each groove.

14. An air bearing as claimed in any of Claims 10 to 13, wherein there are two, three or four such grooves.

15. An air bearing as claimed in any of Claims 10 to 14, wherein all of the air outlets feed into the grooves.

16. A tape drive machine comprising means to hold a tape cartridge, a head, a take-up reel, and a lacing means for moving a leader block of the tape cartridge between an unlaced position in the tape cartridge and a laced position in the take-up reel with the tape following a path from the cartridge, past the head to the take-up reel; characterised in that the lacing means moves the leader block in a part-circular arcuate path between the unlaced and laced positions.

17. A machine as claimed in Claim 16, wherein the lacing means comprises a rotatable member, drive means for rotating the rotatable member and a leader block pin mounted on the rotatable member.

18. A machine as claimed in Claim 17, wherein the rotatable member is annular.

19. A machine as claimed in Claim 18, wherein the annular member is supported for rotation by a plurality of supports engaging an inner edge of the annular member, an outer edge of the annular member being toothed, and the drive means comprising a motor having a pinion which engages the toothed edge of the annular member.

20. A machine as claimed in any of Claims 16 to 19, wherein the direction of movement of the leader block pin as the lacing means leaves the unlaced position is generally aligned with a direction in which least force is required to withdraw the leader block from the tape cartridge.

21. A tape drive machine comprising means for holding a tape cartridge, a take-up reel, and in a path for tape from the cartridge to the take-up reel: a first guide roller, a first air bearing, a head, a second air bearing, and a second guide roller in that order; characterised in that the tape path from the first guide roller to second guide roller is mirror-image symmetrical about a bisecting plane of the head.

22. A machine as claimed in Claim 21, characterised in that when the take-up reel is half-full, the tape path from a reel in the cartridge to the take-up reel is generally mirror-image symmetrical about the bisecting plane of the head.

23. A tape drive machine, an air bearing therefor, or a method of manufacturing a tape drive machine, substantially as described with reference to the drawings.