GB2195488A - Tape lacing mechanism - Google Patents

Abstract

Tape lacing in a recorder with magnetic heads 40-46 fixedly mounted on a deck 12 between single capstan 52 and a (damped) idler 50 comprises moving (semicylindrical) tape guide 34 in recess 28 in cassette body 14 and moving idler rollers 36 and 38 in recess 32 in the cassette body to the loaded positions as shown, tape 20 being thus constrained to follow a looped path into the interior of which its front surface faces and within which are situated capstan 52, the magnetic heads and idler 50. Thereafter, pinch rollers 56 and 58 are moved vertically downward towards the surface of the deck 12 and then perpendicular to their axes so as to bring them into contact with the tape on the capstan surface (also (Figs. 3, 4)). They are advantageously fixedly mounted on a support (60) pivotable about an axis spaced from and parallel to their own axes so as to allow automatical equalisation of their pressures on capstan 52. Lacing may involve translation of the pinch rollers 56, 58 (Figs. 5, 6, 7), and the heads may be on opposite tape runs (Figs. 6, 7). <IMAGE>

Description

SPECIFICATION Tape lacing mechanism The invention relates to mechanisms for lacing tapes, that is, for receiving a tape and causing it to assume a required path for subsequent longitudinal movement. The tape may be a magnetic tape, for example, and in such a case the path may be a path extending past and immediately adjacent to a magnetic recording and/or reproducing head (or several such heads) which thus interact with the tape for recording onto it or reproducing from it.

Thus, such mechanisms may be used in tape recorders for example.

According to the invention, there is provided a tape lacing arrangement for translating longitudinally movable tape from a first, unlaced path into a second, laced path in which latter path the-tape is longitudinally movable with its surfaces in operative juxtaposition with tape processing transducing means, comprising means for defining the second path as a loopshaped path within the loop of which is situated the said transducing means, and lacing means for translating the tape into the second path and constraining it to move longitudinally therein.

-According to the invention, there is further provided a tape lacing arrangement for lacing magnetic tape held in a cassette which has an externally accessible face along which is positioned the tape when unlaced and which face is provided with- recess means comprising tape deck means for receiving the cassette in a predetermined position thereon, a capstan fixedly mounted on the deck means so as to be rotatable about an axis thereon, at least one magnetic tape head fixedly positioned on the deck means, and tape lacing means in the form of at least two tape guide means which are mounted on the deck means so as to be movable between a tape-unlaced position to a tape-laced position, the tape guide- means when in the tape-unlaced position being located within the recess means in the said face of the cassette so as to be adjacent the back surface of the tape running along the externally accessible face of the cassette, and including means for moving the tape guide means in directions perpendicular to the face of the tape from the tape-unlaced position to the tape-laced position, the tape guide means when in the tape-laced position restraining the tape to define a loop one run of which extends from one tape guide means and over part of the surface of the capstan and the other run of which extends over another part of the surface of the capstan and to the other tape guide means, the tape in the said loop having its front surface in contact with the magnetic tape head which is within the loop.

According to the invention, there is also provided a method of lacing a magnetic recording tape so as to move it into a laced position in contact with a capstan and with at least one magnetic head, including the step of applying a force to the back surface of the tape at two spaced-apart positions along its length so as to move the tape into the laced position in which it defines a loop with the front face of the tape facing inwardly thereof so that the capstan and the magnetic head are within the loop and in contact with the front face of the tape.

According to the invention, there is still further provided a tape driving arrangement for driving a tape longitudinally, including a capstan, means for rotating the capstan, and two pinch rollers having an operative position in which they press the tape against respective parts of the surface of the capstan, the two pinch rollers being mounted to be rotatable about respective axes which are parallel to each other and spaced apart in relation to each other by a fixed distance, the pinch rollers being mounted in common so as to have free movement as a unit in directions perpendicular to their axes whereby to equalise the pressures which they apply to the tape on the surface of the capstan.

Tape recorders incorporating tape lacing mechanisms embodying the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a diagrammatic plan view of part of one form of the mechanisms and illustrating it in the setting which it assumes before the tape is laced; Figure 2 corresponds to Figure 1 but shows the tape fully laced; Figure 3 is a more detailed plan view of the mechanism of Figure 1; Figure 4 is a diagrammatic perspective view of part of the mechanism; Figure 5 is a diagrammatic plan view showing part of another possible form of the mechanism; Figure 6 is a diagrammatic plan view showing part of a further possible form of the mechanism; and Figure 7 is a diagrammatic plan view of yet a further possible form of the mechanism.

The tape lacing mechanism now to be described is for use in a tape recorder designed to receive tape in a cassette. In the particular example to be described initially, the tape recorder is for recording data in several channels arranged side by side across the width of the tape, and the type of cassette used is a VHS ("Video Helical Scan") video-tape cassette (to BS 6482, 1984 and IEC 774, 1983).

However, and as will be explained in more detail, the mechanism to be described may be used with other forms of tape cassette and with tape not in a cassette; thus, for example, the mechanism may be used with reel-to-reel tape supply arrangements.

Figure 1 is essentially diagrammatic. It shows a VHS-type video cassette 10 in position in the mechanism and mounted on a deck 12 only partly shown. The cassette 10 is of standard VHS-type with a body 14 including the normal tape spools 16 and 18 (shown dotted). Figure 1 shows the cassette 10 in position on the deck 12 but with its tape not yet laced, that is, not yet fed into position in the desired operative path. Thus, the tape is shown at 20. As shown, the tape passes from the spool 16, around a guide 24, across the front face of the cassette, and then back to the spool 18 via a further guide 22.

The front face 26 of the cassette body 14 contains recesses 28,30 and 32. These are the normal or standard recesses and are provided in every VHS-type cassette body.

As iridicated in Figure 1, the lacing mechanism to be described in more detail includes a semicircular-shaped tape guide 34 within the recess 28 and two guides 36 and 38 within the recess 32. The guides 34,36 and 38 are mounted on movable arms (not shown in Figure 1) which are supported from the deck 12 and these arms position the guides in the positions shown when the mechanism is in the unlaced setting. Therefore, when the tape cassette 10 is loaded into the tape recorder, the guides 34,36 and 38 automatically become positioned within the recesses 28 and 32.

Clearly, the recorder has to have a cassette loading mechanism which ensures that the cassette 10 is moved into a predetermined loaded position; in addition, the loading mechanism has to be such that the cassette is moved into position with the recesses 28 and 32 substantially vertically above the guide 34 and the rollers 36 and 38 arid then moves vertically downwards, onto the deck 12, so that the guides 34,36 and 38 can enter the recesses 28 and 32, behind the tape 20.

The semi-cylindrical shape of the guide 34 is a refinement to fit within the limited space of the recess 28 and provides optimum strength in relation to the space available for it.

As shown in Figure 1, the tape recorder has four (in this example) magnetic heads 40,42,44 and 46 for recording and/or reproducing data on and from the tape 20 in use.

The heads are fixedly mounted with respect to the deck 12 by means not shown. A guide 48 may be mounted on the deck 12 and-positioned between the heads 42 and 44. An idler roller 50 is rotatably mounted on the deck 12 and rotatably driven by means not shown.

An erase head 54 is also fixedly mounted on the deck 12.

Also shown in Figure 1 are two pinch rollers 56 and 58 which are freely rotatably mounted on a plate 60. In a manner to be explained, the plate 60 is movable between an unloaded position and a loaded position. Figure 1 shows the plate in the unloaded position. In the unloaded position the plate 60 is raised with respect to the deck 12 so that the pinch rollers 56 and 58 are positioned above the plane of the tape.

Figure 2 corresponds to Figure 1 and corresponding items are similarly referenced. However, Figure 2 shows the mechanism after tape lacing has taken place. The tape lacing process involves predetermined movements of the guides 34,36 and 38, and the plate 60.

As shown in Figure 2, the guide 34 has been displaced along an arc indicated at 70.

and the guides 36 and 38 have been displaced along paths shown dotted at 72 and 74. Therefore, the tape 20 now passes from idler 24 around guides 38 and 36, then in contact with the capstan 52 and behind the heads 40 and 46, around idler 50, across heads 46 and 44, guide 48, and heads 42 and 40 to the surface of capstan 52 again.

Thence it passes around guide 36 and back to idler 22.

The idler 50 is suitably damped to minimise angular vibration which might otherwise result from the inertia of the idler and the stiffness of the tape. Such damping may be achieved with a rotary element resiliently coupled to the idler. The rotary element could be a ringshaped element positioned at one axial end of the idler and coupled to the idler by one or more resilient coupling members extending parallel to the axis. Instead the rotary element could be within the hollow interior of the idler and coupled to it by a resilient coaxial sleeve.

Other arrangements are possible.

In passing between the guides 36 and 38, the tape passes across the face of the erase head 54. When the idlers 36 and 38 move into the tape-laced position shown in Figure 2, a keeper 76 moves with them and into a predetermined position adjacent to the operative face of the erase head 54 but on the opposite side of the tape 20.

The lacing process is completed by movement of the plate 60 and consequent movement of the pinch rollers 56 and 58 into the positions shown in Figure 2. The movement of the plate 60 takes place in two directions sequentially, as will be explained in more detail below. First, the plate 60 moves vertically downwards, that is, towards the surface of the deck 12. It then moves in the direction of the arrow B, so that the pinch rollers 56 and 58 press the tape onto the surface of the capstan 52.

It will be appreciated that an alternative arrangement is possible in which the plate 60 is initially in a lowered position so that the pinch rollers 56 and 58 are below the capstan and is then raised #vertically.

The tape lacing mechanism illustrated has a number of significant advantages.

It will be noted that only a single capstan is used. Tape driving mechanisms embodying multiple capstans are subject to the likelihood of small differences in the surface velocities of the several capstans. In certain circumstances, particularly bi-directional operation, this can be disadvantageous, resulting in variations in tape tension and velocity. Moreover, multiple capstans tend to complicate the tape driving mechanism.

The arrangement of the pinch rollers 56 and 58 is also advantageous. Their rotatable axes are mutually fixed on plate 60. As explained, this plate moves the pinch rollers into the loaded position shown in Figure 2 (by moving in the direction of the arrow B). The fact that the plate 60 is rockable about its pivot 61 in the directions of the arrows A means that the two pinch rollers 56 and 58 automatically exert equal force on the tape and capstan. In this way, therefore, the capstan exerts equal contact force on the two portions of the tape, and the resultant force exerted on the capstan is small.

The actual lacing process (that is, the process involving the movement of the guides 34 36 and 38, and the plate 60) may take place manually or automatically.

The mechanism for moving the guides 34,36 and 38 from the positions shown in Figure 1 to the positions shown in Figure 2 will now be described with particular reference to Figures 3 and 4.

Figure 3 shows a plan view of the mechanism with the cassette and deck removed to aid clarity. This Figure shows the mechanism in the laced position.

The lacing mechanism comprises a disc crank 100 which can be turned via a drive belt 102 and a motor-driven spool 104 (the motor being omitted). The disc crank 100 has a connecting rod 106 privotally connected to it at 108. The other end of the connecting rod 106 is pivotally connected at 110 to a main lacing arm 116 which is pivotted to the deck about an axis 118.

A substantially L-shaped coupling rod 112 is pivotally connected at 114 to the main lacing arm 116. The other end of the coupling rod 112 is pivotally connected at 120 to an arm 122 which is rigid with a subsidiary lacing arm 124. The junction between the link 122 and the arm 124 is pivotted to the deck at 126.

The capstan 52 is driven by an electric motor incorporated in a module (not shown) with a tacho-generator for use in speed measurement and control.

The main lacing arm 116 carries the guides 36 and 38 (see Figures 1 and 2 also).

The subsidiary lacing arm 124 carries the tape guide 34 (see Figures 1 and 2).

The mechanism is shown in the loaded position in full line in Figure 3. As will be seen, the main lacing arm 116 has therefore placed the guides 36 and 38 in the correct positions relative to the capstan 52. Similarly, the subsidiary lacing arm 124 has positioned the guide 34 in the correct loaded position relative to the capstan 52.

In addition, the arm 116 has moved the keeper 76 into juxtaposition with the erase head 54 so that DC erasing of the tape can be carried out as required.

The mechanism is moved into the unloaded position (that is, with the tape unlaced) by anti-clockwise rotational movement of the disc crank 100. This movement, via rod 106, rotates the lacing arm 116 from the full to the dotted position. The movement of arm 116 is communicated to the subsidiary lacing arm 124 by rod 112 and link 122 so that the subsidiary arm likewise moves to the dotted position (for clarity only part of arm 124 is shown in the dotted position and the other connected members are not shown in equivalent dotted positions). The guides 34,36 and 38 thus move back into the unlaced position for the tape, that is, they move back within the recesses 28 and 32 of the tape cassette 10 (see Figs 1 and 2).

The design of the mechanism is such that the connecting rod 106, in moving the mechanism into either extreme position, becomes slightly deflected from its relaxed form. This helps to ensure that the main and subsidiary lacing arms 116 and 124 are firmly held in their final positions.

Completion of the lacing process also of course requires that the plate 60 and the pinch rollers 56 and 58 (see Figures 1 and 2) be moved into position. As explained, such movement takes place in two planes. First, movement in a vertically downward direction with respect to the top surface of the deck 12 is required, and secondly, the plate 60 has to move the pinch rollers towards the capstan 52.

The mechanism for moving the plate 60 is shown most clearly in the perspective view of Figure 4. As shown, the plate 60 is rigidly attached at 61 (see also Figure 1) to the upper end of a pillar 150 which is rotatable and slidable in a vertical direction in a block 152.

The block 152 has arms 154 and 156 which embrace the deck 12 and by means of which the block can pivot about an axis 157. A bellcrank 160 is pivotally mounted on one side of the block 152 and has an extending arm 162 which contacts a pin 163 working (with clearance) in a slot 164). The pin is attached to the pillar 150. Therefore, movement of the bell-crank 160 in the direction of the arrow C causes the pillar 150 to be lifted under action of a return spring 166, while movement in the opposite direction to the arrow C lowers the pillar 150.

Movement of the bell crank 160 is controlled by a rod 170. One end of this is attached to the bell crank by ball joint 171 and the other end is connected to a rocker arm 172 (see Fig. 3) by ball joint 173. The other end of the arm 172 engages an extension 174 on the disc crank 100.

During the tape-lacing operation, the disc 100 is moved in a clockwise direction (as viewed in Figure 3) as a#lready explained. The movement of the extension 174 therefore causes the rocker 172 to turn in the direction of the arrow D (Figure 3) and thus pushes on the rod 170. The bell crank 160 therefore turns in the direction opposite to that shown by arrow C (Fig. 4) and the pillar 150 and the plate 60 are lowered. This of course happens in sequence with the already-described movements of the main and subsidiary lacing arms 116 and 124, and the arrangement is such that the pinch rollers 56 and 58 are not lowered into position alongside the capstan 52 until the guides 34,36 and 38 have moved into their positions corresponding to final tape lacing.

The mechanism is arranged so that the pillar 150 becomes fully lowered within the block 152 before angular movement in the direction of the arrow D of the rocker arm 172 has been completed. Therefore, the rod 170 continues to move. Because the pillar 150 cannot be lowered any further, the result is to cause the block 152 to swing about the arms 154 and 156 in the direction of the arrow E in Fig.

4 corresponding to the direction of the arrow B in Figure 2. This swinging movement compresses a return spring 180 (Fig. 4) which is held in a recess (not shown) in the deck 12.

Such swinging movement of the block 152 moves the plate 60, and thus the pinch rollers 56 and 58, towards the capstan 52 and thus into the positions shown in Figure 2.

The above-described process for moving the pinch rollers into position against the tape on the capstan does not begin until the tape lacing process is complete. As already explained, the rod 106 is designed to bend slightly under its own resilience. Therefore, when the lacing arms- 116 and 124 have reached their tapelaced positions, continued clockwise movement of disk crank 100 can take place and it is during this continued movement that the extension 174 contacts the rocker 172 and moves it in the direction of the arrow D to carry out the loading movement for the pinch rollers.

Unloading of the pinch rollers is the reverse of the sequence just described. Thus, angular movement of the disc 100 in the anticlockwise direction causes the arm 172 to turn. in the direction opposite to arrow D (Figure 3) and the rod 170 is retracted. This allows the spring 180 to swing the block 152 in the direction opposite to that of arrow E (Fig. 4). The plate 60 and thus the pinch rollers 56 and 58 are retracted from the capstan 52. Continued retraction of the rod 170 allows spring 166 (Fig. 4) to raise the pillar 150 thus lifting the pinch rollers 56 and 58 above the tape path.

It will be seen from Figures 1 to 4 that plate 60 carries jaws 63 which embrace an upper extension of capstan 52. The purpose of these jaws 63 is to limit free movement in the directions B (see Figure 2) of plate 60 when pinch rollers 56 and 58 are disengaged.

Thus, when the pinch rollers 56 and 58 move vertically downwards, during the engagement process, the plate 60 is in such correct angular position that the descending rollers do not contact and thus disturb the tape. When the pinch rollers 56 and 58 subsequently undergo motion in the direction B (see Figure 2), produced by angular motion E (see Figure 4), they move into contact with the tape on the capstan. This contact holds the jaws clear of the capstan extension.

The mechanism illustrated in Figures 1 to 4 is well suited to the use of DC erasing because the guides 36 and 38 provide a subsidiary tape path, in the tape-laced position, adjacent one side of which the keeper 76 is moved by the arm 116. However, it is of course not at all necessary to use DC erasing and other erasing means can be used as desired (or of course no erasing means may be provided).

It will be understood that the mechanism illustrated with respect to Figures 1 to 4 is merely an example of many different possible mechanisms which can be used.

Figure 5 diagrammatically shows a possible modified system, and parts in Figure 5 corresponding to those in the preceding Figures are similarly referenced.

In the system shown in Figure 5, the lacing process is carried out by means of translational movement of the pinch rollers 56 and 58 themselves. When the cassette 10 is loaded into position in the tape recorder, the pinch roller 56 becomes located within the recess 30 as indicated at 56A and the pinch roller 58 together with an idler roller 200 become located within the recess 32, as indicated at 58A and 200A. The lacing process involves translational movement of the pinch rollers 56 and 58 and the idler roller 200 to the positions shown. The tape 20 is thus laced around the capstan 52, across the operational faces of the heads 40 to 46 and round the main idler 50. The pinch rollers 56 and 58 move into contact with the tape where it runs over the surface of the capstan 52. Various other possibilities exist, and it should also be noted that the heads 40-46 need not be positioned as illustrated. Figure 6 shows an alternative arrangement in which two of the heads 40 and 42 are in contact with one run of the captive loop of tape 20- while the heads 44 and 46 are in contact with the opposite run thereof. In this case, there are two main idler rollers 50A and SOB (both of which have their axes rigidly fixed with reference to the deck 12). An additional idler 204 is also provided.Lacing is again carried out by movement of the pinch rollers 56 and 58 which are initially located in the recesses 30 and 32 of the cassette 10, each being associated with a respective idler 206,208, the latter moving with the pinch rollers 56,58, (the pinch rollers 56 and 58 and the idlers 206 and 208 each being indicated with the suffix "A" in the unlaced positions). Such a modified head arrangement may of course be applied to the modified system shown in Figure 5.

Another possible modified system is shown in Figure 7. This is somewhat similar to that shown in Figures 5. and 6 in that the lacing process is carried out by translatfonal movement of the pinch rollers 56 and 58 which are initially located within the recesses 30 and 32 of the cassette body 14. Although the mechanisms so far described have been described with reference to lacing tape from a VHS video cassette, the mechanisms may be applied in many other circumstances. Thus, with suitable modification the mechanisms described could be used for lacing tape held in forms of cassette other than VHS video cassettes. It is of course necessary for the cassette to be designed to enable the members which actually carry out the lacing (that is, the guides 34,36 and 38 in the case of the mechanism shown in Figures 1 to 4)-have to have freedom of access, before lacing begins, to the reverse side of the tape. However, use of the mechanism is not restricted to the lacing of tapes held in cassettes. The lacing mechanism can be used for lacing the tape of a reel-toreel tape recorder for example.

In the arrangements illustrated, the pinch rol lers may advantageously be permitted a degree of self-alignment in their rotational axes to ensure that they adopt the correct position with respect to tape and capstan movement.

Claims (56)

1. A tape lacing arrangement for translating longitudinally movable tape from a first, unlaced path into a second, laced path in which latter path the tape is longitudinally movable with its surfaces in operative juxtaposition with tape processing transducing means, comprising means for defining the second path as a loop-shaped path within the loop of which is situated the said transducing means, and lacing means for translating the tape into the second path and constraining it to move longitudinally therein.

2. A tape lacing arrangement according to claim 1, in which the means for defining the second path includes the surface of a single rotatable capstan.

3. A tape lacing arrangement according to claim 2, in which the second path comprises, in order along its length, part of the surface of the capstan, the said head means, and another part of the surface of the capstan.

4. A tape lacing arrangement according to claim 3, in which the second path also includes at least one tape. guiding means in a position along the length of the path between the two said parts of the surface of the capstan.

5. A tape lacing arrangement according to any one of claims 1 to 3, in which the second path is defined by the said capstan and anidler roller which are positioned with their rotational axes parallel to each other spaced apart from each other and fixedly mounted in relation to each other and parallel to the plane of the tape when in the second path, and by the transducing means which is positioned between the capstan and the idler roller, the said path having two tape runs, one extending from one said part of the surface of the capstan to the idler roller and the other extending from the idler roller to the other said part of the surface of the capstan.

6. A tape lacing arrangement according to claim 5, in which the transducing means comprises a plurality of individual tape processing heads.

7. A tape lacing arrangement according to claim 6, in which the plurality of heads are all mounted in operative juxtaposition with one said run of the second path.

8. A tape lacing arrangement according to claim 6, in which some of the heads are mounted in operative juxtaposition with one said run of the second path and the remainder of the heads are mounted in operative juxtaposition with the other said run thereof.

9. A tape lacing arrangement according to any preceding claim, in which the lacing means comprises at least two spaced apart tape guide means which make contact with the opposite said surface of the tape when the tape is in the said first path, and including means for moving the tape guide means in a direction perpendicular to the said surface whereby to move the tape into the said second path.

10. A tape lacing arrangement according to any one of claims 5 to 8, in which the tape lacing means comprises at least two spaced.

apart tape guide means which make contact with the opposite said surface of the tape when the latter is in the said first path and including means for moving one said guide means in a direction perpendicular to the said surface so that it causes a portion of the said tape to move into one said run of the second path, and means for moving the other tape guide means in a direction perpendicular to the said tape surface so that it causes another portion of the tape to move into the other said run the second path.

11. A tape lacing arrangement according to claim 9 or 10, including third tape guide means mounted adjacent to one of the said tape guide means and movable therewith so as to define a subsidiary tape path when the tape is in the second path.

12. A tape lacing arrangement according to any one of claims 9 to 11, in which at least one said tape guide means is an idler roller.

13. A tape lacing arrangement according to claim 2 or to any one of claims 3 to 13 as dependent on claim 2, including at least one pinch roller which is positioned adjacent the surface of the capstan when the tape is in the second path for holding the tape in driving engagement with the said c#apstan surface.

14. A'tape lacing arrangement according to claim 13, in which there are two said pinch rollers, one having a first location adjacent to the said one pa#rt of the surface of the capstan when the tape is in the said second path and the other having a second location adjacent to the said other part of the surface of the capstan when the tape is in the said second path.

15. A tape lacing arrangement according to claim 14, in which the two pinch rollers are rollers mounted on a translatable member so as to have their rotational axes parallel to and fixed in relation to each other, the said translatable member being translatable into such position, after the tape has been moved into the said second path, as to move the pinch rollers into the said first and second locations respectively, the said translatable member being permitted freedom of movement in a direction transverse to the-directions of the axes of the pinch rollers whereby substantially to equalise the pressures which the pinch rollers exert on the tape in contact with the capstan.

16. A tape lacing arrangement according to any one of claims 13 to 15 in combination with any one of claims 9 to 12, in which at least one said tape guide means comprises a -said- pinch roller.

17. A tape lacing arrangement according to any preceding claim, in which the tape paths are paths extending between tape receiving reels.

18. A tape lacing arrangement according to any one of claims 1 to 7, in which the tape is held in a cassette across an externally accessible face of which the tape extends when in the first path.

19. A tape lacing arrangement according to any one of claims 9 to 12 and 16 in which the tape is held in a cassette across an externally accessible face of which the tape extends when in the said first path, the said externally accessible surface of the cassette having at least one recess for receiving the tape guide means so that the latter are adjacent to the said opposite surface of the tape.

20. A tape lacing arrangement according to claim 19, in which at least one tape guide means is a guide having a part cylindrical surface for receiving- the tape.

21. A tape lacing arrangement according to claim 18, 19 or 20, in which the cassette is a video cassette.

22. A tape lacing arrangement according to claim 21, in which the cassette is a VHS video cassette.

23. A tape lacing arrangement according to any preceding claim, in which the tape is magnetic tape and the tape processing transducing means comprises magnetic recording/reproducing head means.

24. A tape lacing arrangement according to claim 11 or to any one of claims 12 to 22 as dependent on claim 11, in which the tape is magnetic tape and the tape processing transducing means comprises magnetic recording/reproducing head means and including a magnetic erase head mounted in juxtaposition with the said subsidiary tape path for magnetically erasing the said tape therein.

25. A tape lacing arrangement according to claim 24, including a magnetic keeper mounted between the said further tape guide means and the said one of the first and second tape guide means so as to be movable therewith into a magnetic keeping position relative to the erase head when the tape is in the said subsidiary tape path.

26. A tape lacing arrangement for lacing magnetic tape held in a cassette which has an externally accessible face along which is positioned the tape when unlacqd and which face is provided with recess means comprising tape deck means for recefving the cassette in a predetermined position thereon, a capstan fixedly mounted on the deck means so as to be rotatable about an axis thereon, at least one magnetic tape head fixedly positioned on the deck means, and tape lacing means in the form of at least two tape guide means which are mounted on the deck means so as to be movable between a tape unlaced position to a tape laced position, the tape guide means when in the tape unlaced position being located within the recess means in the said face of the cassette so as to be adjacent the back surface of the tape running along the externally accessible face of the cassette, and including means for moving the tape guide means in directions perpendicular to the face of the tape from the tape-unlaced position to the tape-laced position, the tape guide means when in the tape-laced position restraining the tape to define a loop one run of which extends from one tape guide means and over part of the surface of the capstan and the other run of which extends over another part of the surface of the capstan# and to the other tape guide means, the tape in the said loop having its front surface in contact with the magnetic tape head and the magnetic tape head which is within the loop.

27. An arrangement according to claim 26, in which the recess means comprises two recesses spaced apart along the said face of the cassette and in which the tape guide means are respectively located in the recess means when in the tape unlaced position.

28. An arrangement according to claim 26 or 27, in which there are a plurality of magnetic tape heads all of which are positioned within the loop and in contact with the front surface of the tape when the tape guide means are in the tape-laced position.

29. A tape lacing arrangement according to claim 28, in which some of the magnetic heads are in contact with the tape in one said run and the remainder of the tape heads are in contact with the tape in the other said run.

30. A tape lacing arrangement according to any one of claims 26 to 29, including an idler roller around which the tape passes and which is positioned between the two runs of the loop.

31. A tape lacing arrangement according to any one of claims 26 to 30, including at least one pinch roller for pressing the tape into driving contact with the capstan when the tape guide means are in the said tape-laced position.

32. A tape lacing arrangement according to any one of claims 26 to 30, including two pinch rollers mounted on a pinch roller support member with their rotational axes parallel to each other and spaced apart by a fixed predetermined distance, and means for moving the said member in synchronism with movement of the tape guide means from the tapeunlaced position to the tape-laced position so that the pinch rollers are moved from a position clear of the said loop into a position in which they are respectively in contact with the back surface of the tape in the two positions thereof where the front surface is in contact with the capstan, whereby the pinch rollers press the tape into driving engagement with the capstan, the said member being freely movable in a direction which permits the pinch rollers to move perpendicularly to their axes whereby to enable them substantially to equalise the pressures which they apply to the tape on the surface of the capstan.

33. A tape lacing arrangement according to any one of claims 26 to 32 in which one of the tape guide means is of part cylindrical shape so as to be capable of being fully recessed in the recess means in the tape-unlaced position.

34. A tape lacing arrangement according to any one of claims 26 to 333 in which the cassette is a video cassette.

35. A tape lacing arrangement according to claim 34, in which the video cassette is a VHS cassette.

36. A method of lacing a magnetic recording tape so as to move it into a laced position in contact with a capstan and with at least one magnetic head, including the step of applying a force to the back surface of the tape at two spaced-apart positions along its length so as to move the tape into the laced position in which it defines a loop with the front face of the tape facing inwardly thereof so that the capstan and the magnetic head are within the loop and in contact with the front face of the tape.

37. A method according to claim 36, in which there are a plurality of magnetic heads extending between the capstan and an idler roller and in which the said step comprises the step of forming the said loop so that one run thereof extends from one part of the surface of the capstan to the idler roller and the other run thereof extends from the idler back to another part of the surface of the capstan, with the magnetic heads being in contact with the front face of the tape along at least one said run.

38. A method according to claim 37, in which some of the heads are in contact with the tape in one said run and the remainder are in contact with the tape in the other said run.

39. A tape driving arrangement for driving a tape longitudinally, including a capstan, means for rotating the capstan, and two pinch rollers having an operative position in which they press the tape against respective parts of the surface of the capstan, the two pinch rollers being mounted to be rotatable about respective axes which are parallel to each other and spaced apart in relation to each other by a fixed distance, the pinch rollers being mounted in common so as to have free movement as a unit in directions perpendicular to their axes whereby to equalise the pressures which they apply to the tape on the surface of the capstan.

40. An arrangement according to claim 39, in which the two pinch rollers are rotatably mounted on a support member which is pivotable about an axis parallel to but spaced from the axes of the pinch rollers so as to provide the said free movement of the pinch rollers.

41. An arrangement according to claim 40, in which the said member is movable between first and second positions so that in the said first position the pinch rollers are clear of -the capstan so as to permit the tape to move into and out of contact with the surface of the capstan in directions transverse to the face of its surface and in the said second position the pinch rollers are in their said operative position.

42. An arrangement according to claim 41, in which the movement of the said member between the first and second positions is made up of movement in two substantially perpendicular directions.

43. An arrangement according to claim 42, in which the said first position the member supports the pinch rollers vertically displaced from the capstan and in which the said movement comprises a first stage of movement which moves the pinch rollers in a direction parallel to the axis of the capstan to an intermediate position in which they are adjacent to the tape on the capstan and a second stage of movement which moves the pinch rollers in a direction perpendicular to the axis of the capstan and into the said second position.

44. An arrangement according to claim 43, including guiding means which limit the amount of movement of the pinch rollers in directions transverse to the axis of the capstan- when the member is in the first position and when it is moving to the intermediate position whereby to prevent contact of the pinch rollers with the edge of the tape on the capstan during the said first stage of movement.

45. An arrangement according to claim 44, in which the guiding means comprises a pair of jaws on the said members on the said member which partially embrace and make contact with the surface of an axially extend ing part of the capstan.

46. A tape lacing arrangement, substantially as described with reference to Figures 1 and 2 of the accompanying drawings.

47. A tape lacing arrangement, substantially as described with reference to Figures 1 to 4 of the accompanying drawings.

48. A tape lacing arrangement, substantially as described with reference to Figure 5 of the accompanying drawings.

49. A tape lacing arrangement, substantially as described with reference to Figure 6 of the accompanying drawings.

50. A tape lacing arrangement, substantially as described with reference to Figure 7 of the accompanying drawings.

51. A tape lacing method, substantially as described with reference to Figures 1 and 2 of the accompanying drawings.

52. A tape lacing method, substantially as described with reference to Figures 1 to 4 of the accompanying drawings.

53. A tape lacing method, substantially as described with reference to Figure 5 of the accompanying drawings.

54. A tape lacing method, substantially as described with reference to Figure 6 of the accompanying drawings.

55. A tape lacing method, substantially as described with reference to Figure 7 of the accompanying drawings.

56. A tape lacing arrangement according to claim 39 and substantially as described with reference to the accompanying drawings.