Tape recording and/or reproducing apparatus

Abstract: Tape recording and/or reproducing apparatus has a guide drum (14) with rotary heads to record or reproduce signals in slant tracks scanned on a longitudinally transported tape (13) wrapped helically about a circumferential surface of the drum (14) between a tape-entry position (15 a ) and a tape-exit position (15 b ). A tape-guiding assembly, which may be part of a tape loading device, includes ultrasonically vibrated tape guides (25 a , 25 b ) engageable by the tape (13) adjacent the tape-entry (15 a ) and tape-exit (15 b ) positions, respectively, auxiliary guide elements (26 a , 26 b ) angled relative to the vibrated tape guides (25 a , 25 b ), respectively, and each being disposed for engagement by the tape (13) between the respective vibrated tape guide (25 a , 25 b ) and the tape-entry (15 a ) or tape-exit (15 b ) position, respectively, with the auxiliary guide elements (26 a , 26 b ) having respective surface projections (71 a , 71 b ) extending therefrom at positions therealong corresponding to widthwise portions of the tape at which the rotary heads scan the tape (13) adjacent the tape-entry (15 a ) and tape-exit (15 b ) positions respectively, so that the surface projections (71 a , 71 b ) on the auxiliary guide elements (26 a , 26 b ) relatively increase tension in the tape (13) at the respective widthwise portions to minimise errors that may arise in the signals recorded or reproduced in the tracks adjacent the tape-entry and tape-exit positions due to vibrations transmitted along the tape from the vibrated tape guides (25 a , 25 b ).

Description: This invention relates generally to a tape guiding assembly for recording and/or reproducing apparatus, such as, a video tape recorder (VTR). Published Japanese Specification No. 04-311856 provides a tape guiding assembly for a VTR which includes ultrasonically vibrated tape guides engageable by the tape adjacent the tape-entry and tape-exit positions, respectively, and auxiliary guide elements angled relative to the vibrated tape guides, respectively, and each disposed for engagement by the tape between the respective vibrated tape guide and the tape-entry or tape-exit position, respectively. When such tape guiding assembly is included in a tape loading and unloading apparatus, the vibrated tape guides and the respective auxiliary guide elements are mounted on respective sliders which are movable between unloaded positions, in which the vibrated tape guides and auxiliary guide elements are engageable with the tape in a cassette, and loaded positions, in which the vibrated tape guides and respective auxiliary guide elements are disposed adjacent the tape-entry and tape-exit positions, respectively. When the sliders are moved from their unloaded positions to the respective loaded positions, the vibrated tape guides and auxiliary guide elements withdraw the tape from the cassette and wrap the tape about the circumferential surface of the guide drum between the tape-entry and tape-exit positions. When the vibrated tape guides are operated, ultrasonic vibrations are generated to reduce the frictional resistance to movement of the tape. Generally, the ultrasonically vibrated tape guides vibrate at frequencies between about 100 and 150 kHz with an amplitude of about 1 µm. In existing tape guiding assemblies employing ultrasonically vibrated tape guides, as aforesaid, the vibrations generated thereby are propagated past the adjacent relatively angled auxiliary guide elements to at least those portions of the tape wrapped about the guide drum which are adjacent the tape-entry and tape-exit positions. In the case of digital VTRs, the foregoing vibrations cause the error rate of the digital video signal to deteriorate to within a range of from 1 x 10 -5 to 3 x 10 -4 during recording or reproducing operations. By reason of such deterioration of the error rate of the video signal during recording or reproducing operations, it is a disadvantage of existing tape guiding assemblies including ultrasonically vibrated tape guiding assemblies including ultrasonically vibrated tape guides that the vibrated tape guides are usually energized or operated only in the fast-forward or rewind mode. In other words, the ultrasonically vibrated tape guides are usually not vibrated in the recording or reproducing mode so that the reduction in the frictional resistance to movement of the tape is not then realized. Further, in known tape guiding assemblies included in tape loading and unloading apparatus, there is the danger that the tape, tape guides and the like will be damaged if the tape tension becomes excessive, for example, when the tape reaches one of the ends thereof in either the fast-forward mode or rewind mode without a sufficient deceleration theretofore. Moreover, in previously proposed tape guiding assemblies included in tape loading and unloading apparatus and employing ultrasonically vibrated tape guides, tape guides are mounted on respective sliders which, at the loaded positions, are located by respective stoppers disposed thereat. Contacts provided on each slider and on the respective stopper are mutually engaged with each other when the slider attains the loaded position so that power for energizing the respective vibrated tape guide can be supplied through the mutually engaged contacts. However, such contacts are engaged and disengaged at each loading and unloading operation and are either subject to relatively rapid wear or corrosion, or to the accumulation of foreign matter therebetween which undesirably increase contact resistance such that unreliable transmission of power is experienced. It is also to be noted that, in a previously proposed tape guiding assembly employing ultrasonically vibrated tape guides, each of the tape guides comprises a support shaft, a cylindrical metal bushing, usually of brass, slidable on the support shaft and having a plurality of annular bearing projections as integral parts of the bushing and being spaced apart in the axial direction on the outer surface of the bushing, a tubular tape guide, for example, of ceramic, diametrically dimensioned to extend telescopically over the bushing and be supported, at the inner surface of the tubular tape guide, by the annular projections on the bushing, and an ultrasonic vibration generator fixed to the tubular tape guide at one side thereof and operative to generate an ultrasonic standing wave oscillation in the tubular tape guide with nodes thereof substantially at the annular projections. However, if the annular projections are not precisely located at vibration nodes, the tubular tape guide will move at its areas of contact with the annular projections and, by reason of the relatively hard material of such annular projections, will generate undesirable noise. Published Japanese Specification No. 1119950 discloses a magnetic recording and reproducing device which utilises a surface wave motor to move tape drawing members along stators. The stators incorporate vibration bodies and piezoelectric elements which, when energised, cause travelling surface waves to be generated on the surfaces of the vibration bodies. Published European Specification No. 0 386 712 discloses a variety of tape guiding devices. One of these devices comprises a support shaft over which is fitted a cylindrical bushing that is vibratable by an ultrasonic vibrator. The cylindrical bushing is insulated from the support shaft by rubber O-rings. The ultrasonic vibrator is fixed on two sides to the bushing. US-A-3 494 525 discloses a multitrade tape recorder that employs a plurality of u-shaped tape guide shutes. Each shute is provided with a control roller that has a raised central portion to reduce the area of frictional engagement between the roller and the tape. According to one aspect of the invention there is provided tape recording and/or reproducing apparatus comprising: a guide drum with rotary head means thereon to move in a planar orbit coinciding with a circumferential surface of the drum to record or reproduce signals in slant tracks scanned on a longitudinally transported tape wrapped helically about the circumferential surface of the guide drum between a tape-entry position and a tape-exit position; a tape-guiding assembly including first and second tape guides engageable by the tape adjacent the tape-entry and tape-exit positions, respectively, first and second auxiliary guide elements disposed for engagement by the tape between the first tape guide and the tape-entry position and between the second tape guide and the tape-exit position, respectively, and means to tension the tape; characterised in that said first and second tape guides are ultrasonically vibrated, said first and second auxillary guide elements are angled relative to the first and second tape guides, respectively, and the first and second auxiliary guide elements have respective surface projections extending therefrom at positions therealong corresponding to widthwise portions of the tape at which the rotary head means scan the tape adjacent the tape-entry and tape-exit positions, respectively, so that the surface projections on the auxiliary guide elements relatively increase tension in the tape at the widthwise portions to minimise errors that may arise in the signals recorded or reproduced in the tracks adjacent the tape-entry and tape-exit positions due to vibrations transmitted along the tape from the vibrated tape guides. According to a further aspect of the invention there is provided an ultrasonic tape guiding apparatus comprising: a support shaft, a cylindrical bushing slidable on the support shaft and having a plurality of bearing rings spaced apart in the axial direction on the outer surface of the bushing, with at least the bearing rings being of a shock-absorbing material, a tubular tape guide diametrically dimensioned to extend telescopically over the bushing and be supported, at the inner surface of the tubular tape guide, by the bearing rings, and ultrasonic vibration generating means operative to generate an ultrasonic standing wave oscillation in the tubular tape guide with nodes thereof substantially at the bearing rings; characterised in that the ultrasonic vibration generating means is fixed on one side to the tubular tape guide. In such a tape guiding assembly employing ultrasonically vibrated tape guides, propagation of vibrations along the tape to either the tape-entry position or tape-exit position on the surface of a rotary head drum can be substantially prevented so as to avoid deterioration of the error rate. In tape recording and/or reproducing apparatus with a tape loading device including ultrasonically vibrated tape guides mounted on respective sliders moveable from unloaded to loaded positions, contacts on the sliders and on stoppers provided to locate the sliders in their loaded positions can be engaged with each other to supply energizing power to the vibrated tape guides, without excessive wear or corrosion of contacts. In a tape guiding assembly particularly suited for use in a tape loading and unloading device of a VTR, the occurrence of excessive tensions in the tape, for example, when the tape runs out while running at a high speed in either the fast-forward or rewind mode, can be avoided. An ultrasonically vibrated tape guide in accordance with an embodiment of the invention can be substantially noise-free in operation and can be relatively simply disassembled and reassembled, as when replacement of parts therein is required. Preferably, the support shaft of the ultrasonic tape guiding apparatus extends upwardly from a base and has a threaded upper end portion, upper and lower flanges extend around the support shaft at opposite ends of the bushing and project beyond the outer surface of the tubular tape guide, a spring is provided about the support shaft between the base and the lower flange, and a nut is engaged with the threaded upper end portion of the support shaft and is adjustable along the support shaft to displace the flanges, bushing and tubular tape guide, as a unit, along the support shaft against the yieldable resistance of the spring. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Figure 1 is a schematic plan view showing a video tape recorder (VTR) having a tape loading apparatus which includes a tape guiding assembly in accordance with an embodiment of the invention; Figure 2 is a plan view showing drive rings and guide rails of a main loading section of the tape loading apparatus schematically represented in Figure 1 to effect movements of tape guiding devices between loaded and unloaded positions; Figure 3 is a plan view showing an auxiliary loading and tape tension limiting mechanism included in the tape loading apparatus; Figures 4A and 4B are enlarged, fragmentary plan views of a portion of the auxiliary loading and tape tension limiting mechanism shown in two different positions, and to which reference will be made in explaining the operation of such mechanism; Figures 5A and 5B are a plan view and a front elevational view showing details of the tape guiding devices in the main loading section of the tape loading apparatus in accordance with an embodiment of the invention; Figures 6A and 6B are enlarged side elevational views of respective auxiliary guide elements associated with ultrasonically vibrated tape guides in the tape guiding devices of Figures 5A and 5B; Figures 7 and 8 are longitudinal sectional views illustrating how a tubular tape guide which is ultrasonically vibrated in each tape guiding device is supported in accordance with two embodiments of the present invention; Figure 9 is a detailed plan view of one of the tape guiding devices in which an ultrasonically vibrated tape guide is mounted along with an associated auxiliary guide element on a common base or slider in accordance with an embodiment of the invention; Figure 10 is an enlarged sectional view of the ultrasonically vibrated tape guide as viewed on line X - X in Figure 9; Figure 11 is an exploded perspective view of the elements included in the ultrasonically vibrated tape guide of Figures 9 and 10; Figure 12 is a plan view similar to that of Figure 9, but showing the slider disposed on a guide rail at its loaded position determined by a stopper, and further showing an arrangement of mutually engageable contacts on the slider and stopper to supply energizing power to the vibrated tape guide in the loaded position; Figure 13 is a side elevational view of the structure shown in Figure 12; Figure 14 is a sectional view taken on line XIV - XIV in Figure 12; and Figure 15 is a diagrammatic side view to which reference will be made in explaining how a wiping action is achieved between the mutually engageable contacts to supply energizing power to the respective vibrated tape guide in accordance with the invention. Referring to the drawings in detail, and initially to Figure 1 thereof, it will be appreciated that the invention may be applied to various types of tape recording and/or reproducing apparatus, such as, VTRs employing any one of the D-2 digital, Veta VHS or 8mm formats, and is shown applied to a video cassette recorder (VCR) 10, that is, a VTR intended for use with a tape cassette 11. The illustrated VCR 10 is shown to include a base 12 on which the conventional tape cassette 11 is suitably positioned. The cassette 11 has a casing 11 a , a supply reel 11 b and a take-up reel 11 c rotatably disposed within the casing 11 a and on which a tape 13 is wound, and guides 11 d within the casing 11 a at opposite ends of a recess 11 a provided in a front portion of the cassette casing 11 a and by which the tape between the reels 11 b and 11 c is guided to extend across the open front of the recess 11 e when the cassette 11 is not in use. The tape loading apparatus provided in the VCR 10 may employ a so-called "M-loading" operation to withdraw the tape 13 from within the cassette casing 11 a operatively positioned on the base 12 and helically wrap the withdrawn tape about the circumferential surface of a tilted rotary head drum 14 mounted on the base 12, as shown in full lines in Figure 1. The head drum 14 conventionally has rotary heads (not shown) moving in a planar orbit coinciding with the circumferential surface of the drum to record or reproduce video or other information signals in slant tracks scanned by the rotary heads on the tape wrapped about the drum 14 between a tape-entry position 15 a and a tape-exit position 15 b . Also mounted on the base 12 are supply and take-up reel bases 12 a , 12 b for the reels 11 b , 11 c respectively, suitably positioned fixed tape guides 16 a , 16 b , 16 c , 16 d and 16 e , an erasing head 17, a fixed head assembly 18 used, for example, to record and reproduce an audio signal and a control or CTL signal in longitudinal tracks on the tape, and a capstan 19. The tape loading operation is effected, in part, by a main loading section including tape guiding devices 20 a and 20 b mounted on sliders 21 a and 21 b (Figure 2) which are suitably guided, as hereinafter further described, for movements indicated by the arrows a in Figure 1 between initial or unloaded positions, shown in broken lines in Figure 1, where the tape guiding devices 20 a and 20 b extend upwardly into the recess 11 e of the operatively positioned cassette 11 behind the run of the tape then extending across such recess, as indicated at 13 a , and operative or loaded positions, included in full lines in Figure 1, and at which the tape guiding devices 20 a and 20 b respectively guide the withdrawn tape 13 to and from the surface of the rotary head drum 14, adjacent the tape-entry and tape-exit positions 15 a and 15 b , respectively. The VCR 10 is further shown to include a pinch roller 24 and auxiliary loading guide elements 22 a and 22 b which are included in an auxiliary loading and tape tension limiting mechanism and are mounted, as hereinafter described in detail, for movement between initial or unloaded positions, shown in broken lines in Figure 1, where the pinch roller 24 and the auxiliary loading guide elements 22 a and 22 b also extend upwardly into the recess 11 e of the operatively positioned tape cassette 11, and operative or loaded positions, indicated in full lines in Figure 1, and at which the pinch roller 24 is positioned adjacent the capstan 19 and the auxiliary loading guide elements 22 a and 22 b form respective bights 23 a and 23 b directed laterally away from the drum 14 in the withdrawn tape between the cassette 11 and the drum 14. It will be apparent that the movements of the auxiliary loading guide elements 22 a and 22 b to their loaded positions are effective to bring the withdrawn tape into contact with the fixed erasing head 17 and the fixed head 18 for recording and reproducing audio and CTL or control signals. After the tape 13 has been loaded, as generally described above, the pinch roller 24 is conventionally further moved against the capstan 19 with the tape therebetween longitudinally to advance the tape along the described path, while the tape is unwound from the supply reel 11 b and rewound on the take-up reel 11 c . During such movement of the tape, the rotary heads associated with the drum 14 and the fixed heads 17 and 18 can record or reproduce signals on the tape. The tape guiding device 20 a includes on the slider 21 a an ultrasonically vibrated tape guide 25 a and a relatively angled auxiliary guide element 26 a which is disposed for engagement by the tape between the vibrated tape guide 25 a and the tape entry position 15 a when the tape guiding device 20 a is in its loaded position shown in Figures 5A and 5B. The tape guiding device 20 b similarly includes on the slider 21 b an ultrasonically vibrated tape guide 25 b and a relatively angled auxiliary guide element 26 b disposed for engagement by the tape between the vibrated tape guide 25 b and the tape-exit position 15 b when the tape guiding device 20 b is in its loaded position. As shown particularly in Figure 5B, the auxiliary guide elements 26 a and 26 b are oppositely angled in respect to the related vibrated tape guides 25 a and 25 b to control the winding and spiralling angles of the tape 13 as it is helically wrapped around the rotary head drum 14 with a wrap angle of around 180°. As shown particularly in Figure 2, the main loading section further includes a pair of horizontally disposed, oppositely curving guide rails 27 a and 27 b extending from the unloaded positions to the loaded positions of the tape guiding devices 20 a and 20 b , respectively, and on which the tape guiding devices 20 a and 20 b are slidably mounted. The guide rails 27 a and 27 b have respective curving slots 28 a and 28 b extending therealong, and connecting pins 29 a and 29 b extend downwardly through the slots 28 a and 28 b from the sliders 21 a and 21 b slidable on upper surfaces 30 a and 30 b of the guide rails. Drive links 31 a and 31 b are pivotally connected, at one end, to the connecting pins 29 a and 29 b , while the opposite ends of the links 31 a and 31 b are pivotally connected, as at 32 a and 32 b (Figure 2), to superposed counter-rotatable drive rings 33 a and 33 b , respectively, which extend around the guide drum 14. The upper drive ring 33 b has an arcuate slot 34 therein to permit the pivotal connection 32 a to extend therethrough from the lower drive ring 33 a to the drive link 31 a . When a suitable motor-driven drive mechanism (not shown) turns the drive rings 33 a and 33 b in the opposite directions indicated by the arrows b in Figure 2, the links 31 a and 31 b are effective to drive the sliders 21 a and 21 b , and hence the tape guiding devices 20 a and 20 b , in the directions of the arrows a from their unloaded positions shown in broken lines toward their loaded positions. It is to be noted that, in the herein disclosed auxiliary loading and tape tension limiting mechanism embodying the invention, the auxiliary loading guide element 22 a acts to load tape 13 b at the tape supply side, that is, between the supply reel 11 b and the drum 14, and also as a tension regulator for the tape supply side, in addition to avoiding excessive tension in the tape at the tape supply side. On the other hand, the other auxiliary loading guide element 22 b only acts to load tape 13 c at the tape take-up side and to prevent the occurrence of excessive tension in the tape 13 c at the tape take-up side. Thus, tension control of the tape 13 c at the take-up side is provided by a suitable tension regulator which forms no part of the invention and which has a tension sensing guide pin 35 against which the tape in the bright 23 b is made to engage in response to movement of the auxiliary loading guide element 22 b to its loaded position. As shown in Figure 3, horizontal support arms 36 a and 36 b are mounted, at one end, on shafts 37 a and 37 b for pivotal movements about such shafts in the direction of the arrows c and d , and the auxiliary loading guide elements 22 a and 22 b are mounted on the support arms 36 a and 36 b , respectively, adjacent the free ends thereof. More specifically, the guide element 22 a is rotatably mounted on one end of a support link 38 a which, at its other end, is pivotally mounted on a pin 39 a at the free end of the support arm 36 a . A suitable tape tension detector 40 which forms no part of the invention is coaxially mounted on the shaft 37 a to detect the tension in the tape 13 b at the tape supply side. The other auxiliary loading guide element 22 b is rotatable on a shaft 39 b carried by the free end portion of the support arm 36 b , and a pinch roller support arm 38 b is pivotally mounted, at one end, on the shaft 39 b and, at its other end, carries a shaft 41 on which the pinch roller 24 is rotatable. A driving shaft 42 is rotatably mounted so as to extend horizontally between the support arms 36 a and 36 b , and a peripheral gear 43 on the drive ring 33 a drives a gear train 44 which meshes with a pinion 45 on the shaft 42 to drive the shaft 42. Worm gears 46 a and 46 b are mounted on opposite end portions of the shaft 42, and are rotatably coupled with the shaft 42 through torque limiter springs 47 a and 47 b . The worm gears 46 a and 46 b mesh with worm wheels 48 a and 48 b , respectively, which are rotatable about fixed vertically extending shafts 49 a and 49 b . Driving arms 50 a and 50 b are rotatably coupled with the worm wheels 48 a and 48 b , respectively, so as to turn therewith about the shafts 49 a and 49 b . Limiting mechanisms are employed to connect the drive arms 50 a and 50 b with the respective support arms 36 a and 36 b . For example, as shown in Figure 4A, the limiting mechanism connecting the drive arm 50 a with the support arm 36 a includes links 51 a and 52 a having their adjacent ends pivotally connected, as at 53 a , while the other end of the link 51 a is pivotally connected to the free end of the driving arm 50 a by a pin 54 a , and the end of the link 52 a remote from the link 51 a is pivotally connected, as at 55 a , to an intermediate portion of the support arm 36 a . A tension spring 56 a extends between a spring anchor tab 57 a on the driving arm 50 a and an anchor tab 58 a on the link 51 a to urge the links 51 a about the pin 54 a in the clockwise direction relative to the driving arm 50 a , as viewed in Figure 4A. Such spring-urged movement of the link 51 a relative to the driving arm 50 a is limited, to the position shown in Figure 4A, by a tap 59 a directed laterally from the link 51 a and engageable with a lug 60 a extending from the driving arm 50 a . Further, as shown in Figure 4A, the links 51 a and 52 a are dimensioned and the tape 59 a and the lug 60 a are disposed so that, with the auxiliary loading guide element 22 a in the loaded position, lines extending from the axis of the pivot pin 53 a to the axes of the pivot pins 54 a and 55 a , respectively, include an obtuse angle α open in the direction in which the spring 56 a urges the link 51 a to turn relative to the driving arm 50 a . The spring 56 a is shown as a tension spring and is designed to be stronger than the torque limiter springs 47 a by which rotation of the driving shaft 42 is transmitted to the worm gear 46 a . As is apparent in Figure 3, the limiting mechanism connecting the drive arm 50 b with the support arm 36 b similarly includes links 51 b and 52 b pivotally connected to each other, as at 53 b , and also pivotally connected to the driving arm 50 b , as at 54 b , and to the support arm 36 b , as at 55 b . Further, a tension spring 56 b extends between anchor tabs on the drive arm 50 b and on the link 51 b to urge the link 51 b in the counter-clockwise direction, as viewed in Figure 3, relative to the drive arm 50 b . Such spring-urged movement of the link 51 b relative to the driving arm 50 b is limited in a manner similar to that described above with reference to Figure 4A. The operation of the auxiliary loading and tape tension limiting mechanism described above is as follows. In its unloading state, the support arms 36 a and 36 b are turned in the directions of the arrows d to their respective unloaded positions shown in broken lines in Figure 3, and at which the arms 36 a and 36 b engage respective stops 61 a and 61 b . Thereafter, when the drive rings 33 a and 33 b are rotated in the directions of the arrows b , the tape guiding devices 20 a and 20 b are moved, as previously described, from their unloaded positions in the directions of the arrows a in Figure 2, to their loaded positions. At the same time, the peripheral gear 43 on the drive ring 33 a , the gear train 44 and the pinion 45 on the shaft 42 cause rotation of the shaft 42 in a forward direction. Such rotation of the driving shaft 42 is transmitted through the torque limiting springs 47 a and 47 b , the worm gears 46 a and 46 b , and the worm wheels 48 a and 48 b so as to cause turning of the driving arms 50 a and 50 b in the directions of the arrows e in Figure 3. During such turning of the driving arms 50 a and 50 b , the springs 56 a and 56 b are effective to cause the links 51 a and 51 b in the direction of the arrows e . Turning of the links 51 a and 51 b together with the respective driving arms 50 a and 50 b causes the links 52 a and 52 b to drive the support arms 36 a and 36 b in the directions of the arrows c from their unloaded positions to their loaded positions shown in full lines in Figure 3, and at which the arms 36 a and 36 b engage respective stops 62 a and 62 b , respectively. During the movement of the support arms 36 a and 36 b toward their loaded positions, the auxiliary loading guide elements 22 a and 22 b on the support arms 36 a and 36 b pull the tape 13 b at the tape supply side and the tape 13 c at the tape take-up side out of the tape cassette 11 in the directions indicated by the arrows f on Figure 1. When the tape 13 loaded as shown in Figure 1, the tape may be run at a high speed in the fast-forward or rewind mode. In such cases, if the tape 13 runs unchecked due to an error or defect in a tape drive servo system, in a tape reel diameter sensing device or in a tape end sensor, an abnormal or excessive tension develops in the tape at the guide elements 22 a and 22 b with the result that a large force F 1 acts laterally inward on the free end of each of the support arms 36 a and 36 b . The moment the excessive tension occurs in the tape 13 b at the tape supply side, the resulting force F 1 acting on the arm 36 a at its free end causes an even larger force to be transmitted from the pivot 55 a on the arm 36 a through the link 52 a to the pivot 53 a . Such transmitted force acts in the longitudinal direction of the link 52 a and, by reason of the angle α, the line of force is offset from the pivot 54 a connecting the link 51 a to the driving arm 50 a , as shown in Figure 4A. Accordingly, a turning moment acts on the link 51 a in the direction of the arrow g which overcomes the force of the spring 56 a and thereby turns the link 51 a relative to the driving arm 50 a to the position shown in Figure 4B. Thus, the links 51 a and 52 a are turned relative to each other from their relatively extended condition of Figure 4A to the contracted or V-shaped condition shown in Figure 4B. It will be appreciated that, when the links 51 a and 52 a assume the V-shaped or contracted condition shown in Figure 4B, the respective support arm 36 a and the auxiliary loading guide element 22 a mounted thereon are free to move through a large stroke β to the position shown in Figure 4B at which the excessive tension acting on the tape is immediately released to avoid the various problems that might otherwise be triggered by the excessive tension, such as, breakage of the tape, or damage to the guide element 22 a or the described mechanism for actuating its support arm 36 a . The links 51 b and 52 b connecting the support arm 36 b with the respective driving arm 50 b will similarly respond to an excessive tension acting on the tape take-up side 13 c engaged by the guide element 22 b . It will be appreciated that the length ratios of the links 51 a and 52 a connecting the support arm 36 a to the driving arm 50 a , and of the links 51 b and 52 b connecting the support arm 36 b to the driving arm 50 b may be varied, as also may be the strength of the limiter springs 56 a and 56 b which are employed to urge the links 51 a and 52 a , and the links 51 a and 51 b to their respective extended conditions. Such dimensional changes or adjustments may be made to select a desired size of the escape strokes β for the support arms 36 a and 36 b , and also to select a desired value of the abnormal or excessive tension at which the arms 36 a and 36 b are made to move through such escape strokes. After completion of the loading operation, that is, when the tape guiding devices 20 a and 20 b are in their loaded positions so that the tape 13 is wrapped helically about the circumferential surface of the drum 14 from the tape-entry position 15 a to the tape-exit position 15 b , as in Figures 5A and 5B, the ultrasonically vibrated tape guides 25 a and 25 b may be operated, for example, at frequencies of 100 to 150 kHz with an amplitude of about 1 µm. The purpose of such vibration is to reduce the frictional resistance to movement of the tape 13 past the engaged surfaces of the vibrated tape guides 25 a and 26 b and the adjacent auxiliary guide elements 26 a and 26 b , respectively. When the vibrated tape guides 25 a and 25 b are operated, a standing wave vibration is generated, as indicated in broken lines at W in Figure 5B, with the standing wave having a pair of nodes J spaced apart in the axial direction of each of the vibrated tape guides 25 a and 25 b . As a result of the forgoing, vibrations are propagated along the tape, particularly, along edge portions of the tape. If such vibrations propagated along the tape by the ultrasonically vibrated tape guides 25 a and 25 b are allowed to travel past the relatively angled auxiliary guide elements 26 a and 26 b to the portion of the tape wrapped about the drum 14, the error rate in digitally recorded video or other signals is known to increase substantially, particularly in the signals recorded or reproduced at shaded regions 70 a and 70 b shown adjacent the tape-entry position 15 a and the tape-exit position 15 b in Figures 5A and 5B. conventionally, the incidence of such errors is known to reach error rates of 1 x 10 -5 to 3 x 10 -4 . Due to the helical wrap of the tape 13 about the drum 14, errors occur at different heights measured in the widthwise direction of the tape 13 in the region 70 a adjacent the tape-entry position 15 a , and in the region 70 b adjacent the tape-exit position 15 b . for a tape 13 having a width W 1 of 19mm, errors occurring at the region 70 a adjacent the tape-entry position 15 a will be at a height H 1 of about 14mm measured from the lower tape edge 13', while errors appearing at the region 70 b adjacent the tape-exit position 15 b will be at a height H 2 of about 9mm measured from the lower tape edge 13'. In other words, errors due to the propagated vibration are concentrated on the tape 13 in longitudinal bands respectively corresponding to the widthwise positions on the tape where the rotary heads enter into contact with, and leave the tape wrapped about the drum 14. Referring now to Figures 5B, 6A and 6B, it will be seen that the above described problem is avoided by providing the auxiliary guide elements 26 a and 26 b with respective surface projections 71 a and 71 b extending therefrom at positions along the auxiliary guide elements 16 a and 26 b corresponding to the widthwise portions of the tape 13 at which the rotary head or heads associated with the drum 14 scan the tape adjacent the tape-entry and tape-exit positions 15 a and 15 b , respectively. More specifically, in the illustrated embodiment, the surface projections 71 a and 71 b are in the form of annular, diametrically enlarged portions of the cylindrical surfaces of the respective guide elements 26 a and 26 b . The projection 71 a on the guide element 26 a is located at an axial distance H' 1 along the guide element 26 a measured from the lower edge 13' of the tape, as engaged with the guide element 26 a , which is equivalent to the height H 1 of the region 70 a in which errors would occur near the tape-entry position 15 a . similarly, the projection 71 b on the guide element 26 b is located at an axial position H' 2 along the guide element 26 b measured from the position at which the lower edge 13' of the tape runs over the guide element 26 b and which is equivalent to the height H 2 of the region 70 b from the lower edge of the tape. Specifically each of the annular raised projections 71 a and 71 b can have an axial width W 2 of about 2 to 3mm and protrude radially beyond the remaining cylindrical surface 26' of the guide element 26 a and 26 b a distance t of about 20 to 40 µm. When the angled auxiliary guide elements 26 a and 26 b are provided with the projections 71 a and 71 b , respectively, as described above, the deterioration of the video signal error rate attributable to vibrations generated by the ultrasonically vibrated tape guides 25 a and 25 b is prevented, as follows: During a recording or reproducing operation, the tape is conventionally under tension, for example, as regulated in response to the tape tension detector 40 associated with the support arm 36 a and/or the tension regulator which includes the tension sensing guide pin 35. By reason of such tape tension, the tape 13 wrapped about the rotary head drum 14 is held taut between the ultrasonically vibrated tape guides 25 a and 25 b near the tape-entry position 15 a and the tape-exist 15 b , respectively. As the tape 13 is longitudinally advanced by the capstan 19 and the pinch roller 24, the projections 71 a and 71 b on the angled auxiliary guide elements 26 a and 26 b relatively increase the tape tension in the widthwise portions of the tape located at the heights H 1 and H 2 from the lower edge 13' of the tape near the tape-entry position 15 a and the tape-exist position 15 b . The increased tension is, in each instance, produced over a width W 2 at widthwise positions on the tape which correspond to the error-prone regions 70 a and 70 b . When the ultrasonically vibrated tape guides 25 a and 25 b are made to vibrate at frequencies of 100 to 150 kHz with an amplitude of about 1 µm, the partial increase in the tension considered across the tape 13 resulting from the projections 71 a and 71 b on the angled auxiliary guide elements 26 a and 26 b , respectively, and the resulting relatively high-pressure contact of the tape with these projections 71 a and 71 b , serve to damp out at the guide elements 26 a and 26 b most of the tape vibrations resulting from the ultrasonically vibrated tape guides 25 a and 25 b . Thus, the vibrations are not propagated further along the tape onto the drum 14 at the tape-entry and tape-exist positions 15 a and 15 b . As a result of the foregoing, with both of the ultrasonically vibrated tape guides 25 a and 25 b allowed to vibrate during recording or reproducing operations, the VCT can achieve an improved video signal error rate of about 1 x 10 -5 , as compared with the video signal error rate of about 3 x 10 -4 if the ultrasonically vibrated tape guides are operated during a recording or reproducing operation and the projections 71 a and 71 b are not provided. Accordingly, the ultrasonically vibrated tape guides 25 a and 25 b are operated in the recording and reproducing modes, as well as in the fast-forward and rewind modes, thereby to minimize the frictional resistance to movement of the tape during all operations to economize on power consumption. Referring now to Figures 10 and 11, each of the ultrasonically vibrated tape guides 25 a and 25 b is shown to include an upstanding support shaft 81 having its lower end portion suitably fixed in the respective slider 21 a and 21 b . A concave-convex disc spring 82 extends around the shaft 81 immediately above the slider 21 a and 21 b , and a vibrator holder 83 moulded or otherwise formed of an insulating material, such as, an acrylic resin, has a base portion 83 a with a suitably dimension hole 83 b slidably to receive the shaft 81. An elongate locating pin 84 also extends upwardly from the slider 21 a and 21 b and is slidably received in a bore 83 c in the base portion 83 a of the holder 83 when the holder 83 is installed on the shaft 81 above the spring 82. A lower flange 85 of a wear-resisting material, such as, a ceramic, is in the form of a ring which is movable on the shaft 81 above the base portion 83 a of the holder 83. A cylindrical bushing 86 is dimensioned to be slidable on the support shaft 81 so as to rest, at its lower edge, on the lower flange 85, with the bushing 86 having bearing rings 87 spaced apart in the axial direction on the outer surface of the bushing 86. A tubular tape guide 88 which has an ultrasonic vibration generator 89 bonded or otherwise suitably fixed to a side of the guide 88 midway between the ends thereof, is diametrically dimensioned to extend telescopically over the bushing 86 and is supported, at its inner surface 88 a , by the bearing rings 87 on the bushing. When the tubular tape guide 88 is thus installed, the vibration generator 89 thereon is received in, and embraced by the sides of a recess 90 formed in the holder 83. Thus, the holder 83 which is positioned about the axis of the support shaft 81 by the engagement of the locating pin 84 in the hole 83 c of the holder, is effective similarly to position the tubular tape guide 88 and the vibration generator 89 thereon by the engagement of the vibration generator 89 in the recess 90. The support shaft 81 has a reduced diameter, threaded upper end potion 81 a which, as shown on Figure 10, may barely extend upwardly out of the bushing 86. An upper flange 91 which is also in the form of a ring of wear-resistant material, such as a ceramic, extends, with substantial radial clearance, about the upper end portion 81 a of the shaft 81, and rests on the upper end edge of the bushing 86. A spacer 92 for canting or inclining the upper flange 91 is interposed between the upper flange 91 and a head 93 of a nut 94 which further includes an internally threaded cylindrical body 95 depending from the head 93. More specifically, the body 95 is dimensioned to be screwed onto the threaded upper end portion 81 a of the support shaft 81, an is externally dimensioned to extend loosely through central openings 92 a and 91 a in the spacer 92 and the upper flange 91, respectively, and then to be slidably received within the upper end portion of the bushing 86. The spacer 92 is shown in Figure 11 to have an ear 92 b extending therefrom and formed with a hole 92 c spaced from the hole 92 a slidably to receive a locating pin 96 extending upwardly from the holder 83. Such engagement of the pin 96 in the hole 92 c serves rotationally to position the spacer 92 about the axis of the shaft 81. As shown in Figure 10, the underside of the head 93 of the nut 94 has a circular rib 97 depending therefrom, while the spacer 92 is shown in Figure 11 to be formed with a part-circular arcuate slot 92 d having a radius equivalent to that of the circular rib 97. Thus, when the nut 94 is screwed down onto the upper end portion 81 a of the shaft 81, only a portion of the rib 97 extends through the arcuate slot 92 d into contact with the upper surface of the flange 91, while the remainder of the rib 97 bears against the upper surface of the spacer 92. By reason of the foregoing, the upper flange 91 is inclined or canted by an angle  relative to a plane perpendicular to the axis of the shaft 81. Such canting of the upper flange 91 has been found to avoid curling of the upper edge of the guided tape. As shown in Figure 10, the axial length of the bushing 86 is slightly greater than that of the tubular tape guide 88 so as to leave a total axial gap G 1 of about 20 to 30 µm between the tubular tape guide 81 and the flange 85 and 91. As shown in Figure 9, a relatively larger gap G 2 of 0.1 to 0.2 mm is also desirably provided between the sides of the ultrasonic frequency generator 89 and the inside surfaces of the recess 90 provided in the holder 83 to receive the generator. The vibration generator 89 may be conventionally formed of a stack 89 a of piezo-electric ceramic plates with positive and negative electrodes alternately interposed between the successive ceramic plates, and bonding or dummy layers 89 b bonded to the opposite sides of the stack 89 a and securing the same to be tubular tape guide 88. Rotation of the nut 94 on the threaded end portion 81 a of the shaft 81 causes movement thereof in the direction of the axis of the shaft to adjust the height of the holder 83, the lower and upper flanges 85 and 91, the bushing 86 and the tubular tape guide 88, as a unit, between the head 93 of the nut 94 and the spring 82. Such height adjustment of the vibrated tape guide 25 a and 25 b leaves the gap G 1 and G 2 unaffected. When the adjustment of the height is completed, a set screw 98 is screwed into the nut 94 to bear against the upper end of the shaft 81 and thereby lock the nut 94 in its adjusted position on the threaded end portion 81 a . In order to assemble one of the ultrasonically vibrated tape guides 20 a and 20 b , it is only necessary successively to install from above, on the shaft 81, the spring 82, the holder 83, the lower flange 85, the bushing 86, the tubular tape guide 88, the upper flange 91, and the spacer 92, whereupon the nut 94 is screwed onto the threaded upper end portion 81 a of the shaft 81. The foregoing simple assembly procedure makes it easy to replace the tubular tape guide 88 if necessary. As earlier noted, the holder 83 is readily moulded from an insulating material, such as, an acrylic resin, and the pin 84 determines the rotary direction of the holder 83 while permitting axial adjustments thereof on the shaft 81. The bushing 86 is effective precisely to locate the tubular tape guide 88 so as to be coaxial with the shaft 81. Simply inserting the vibration generator 89 into the recess 90 of the holder 83 establishes the gap G 2 with sufficient precision. Because the nut 94 and the spring 82 press the upper and lower flanges 91 and 85 against the adjacent ends of the bushing 86, the precise dimensioning or machining of the bushing 86, the precise dimensioning or machining of the bushing 86 and of the tubular tape guide 88 ensures that the gap G 1 is precisely maintained to permit the tubular tape guide 88 to vibrate efficiently in both axial and circumferential directions. Since the holder 83 is formed of an insulating material, the gap G 2 can be substantial so as to facilitate the assembly procedure when replacement of the tubular tape guide 88 is required. Further, with the upper and lower flanges 91 and 85 formed of a wear-resistant material, such as, a ceramic, the durability of the assembly is enhanced. The bearing rings 87 are intended to be located at nodes of the ultrasonic standing wave oscillation generated in the tubular tape guide 88. However, if the wave is lightly distorted there will be movements of the guide 88 relative to the bearing rings 87 so that, if such bearing rings are formed integral with the bushing 86 made of brass, noisy operation will result. Therefore, as shown in Figure 7, at least the bearing rings 87' which support the tubular tape guide 88 on the bushing 86' are formed of a shock-absorbing material, such as, a polycarbonate resin or rubber. In the case where the bushing 86' is otherwise formed of a metal, such as, brass, each bearing ring 87' is separately formed and fixedly mounted, as by bonding or the like, against a respective shoulder 86' a suitably positioned on the external surface of the bushing 86'. The bearing rings 87' of shock-absorbing material reduce the friction between the vibrated tubular tape guide 88 and the rings 87' on the bushing 86'. This prevents the occurrence of high-frequency resonance between the tubular tape guide 88 and the bushing 86', when both of these elements are formed of metal. Furthermore, reduction in the frictional resistance to vibration of the guide 88 permits the guide 88 to vibrate more efficiently. Figure 8 illustrates a modification of the preferred arrangement for supporting the vibrated tubular tape guide 88, and in which the bushing 86" and the bearing rings 87" formed integrally therewith are made of a shock-absorbing material, such as, a polycarbonate resin, to achieve the same results as described with reference to Figure 7. The manner in which energizing power is supplied to the ultrasonically vibrated tape guide 25 b of the tape guiding device 20 b when such device attains its loaded position will now be described with reference to Figures 12 to 15, and it will be understood that a similar arrangement is provided to supply energizing power to the vibrated tape guide 25 a of the tape guiding device 20 a in the loaded position thereof. As shown particularly in Figures 12 and 14, the curving slot 28 b extending through the guide rail 27 b is disposed at one side of the longitudinal median line of the guide rail and the guide rail, at the other side of such median line, is formed with a shallow upwardly opening guide groove extending along the upper surface 30 b of the guide rail parallel with the guide slot 28 b . A relatively short guide pin 100 depends from the undersurface 101 of the slider 21 b and engages in the shallow guide groove 99. A step 101 a (Figure 13) extends laterally in the undersurface of the slider 21 b so that the slider may be rocked on such step, as hereinbefore described. The pin 29 b connected to the drive link 31 b and the pin 100 cooperate with the slot 28 b and the groove 99, respectively, to guide slider 21 b along the top surface 30 b of the guide rail between the unloaded position and the loaded position. An end portion 102 of the slider 21 b , which is at the front of the slider 21 b as the slider moves in the direction of the arrow a in Figure 12 toward the loaded position, carries a substantially laterally centered upstanding locater pin 102 a . Further, a ball 103 is embedded in the upper surface of the front end portion 102 of the slider ahead of the locater pin 102 a . The end surface 104 of the front end portion 102 of the slider extends laterally substantially at right angles to the direction of movement of the slider 21 b toward the loaded position, as indicated by the arrow a in Figure 12. Further, the front end surface 104, as viewed from the side in Figure 13, is inclined upwardly and forwardly at the angle  3 of about 10° relative to a perpendicular to the bottom surface 101 of the slider 21 b . In other words, the front end surface 104 of the slider has a sloping overhang. A connector board 105 is secured by a screw 106 (Figure 12) to the front end surface 104 of the slider. A pair of contacts 107 of a contact set 108 are provided at the front of the side portion of the connector board 105 which extends away from the drum 14 in the loaded position of the tape guiding device 20 b . In other words, the contacts 107 on the connector board 105 are offset laterally by a distance l 1 (Figure 12) from the locater pin 102 a in the direction way from the rotary head drum 14. The contacts 107 are connected through harnesses 109 to a repeater board 110 secured to the holder 83. The repeater board 110 is, in turn, connected through harnesses 111 with electrodes at the opposite ends of the stack 89 a of piezo-electric plates constituting the vibration generator 89. A stopper device 112 for accurately locating the tape guiding device 20 b at its loaded position is shown to include a fixed block 113 with a positioning plate 114 secured on the top surface thereof. The positioning plate 114 has an extending portion or shelf-like projection 115 which extends over the front end portion 102 of the slider 21 b as the slider 21 b nears its loaded position. The shelf-like projection 115 has a notch 116 in its end edge for receiving the locater pin 102 a when the slider 21 b attains its loaded position, as shown in Figure 12. At such time, the ball 103 embedded in the upper surface of the front end portion 102 of the slider is disposed under the shelf-like projection 115 and engageable against the underside of the projection 115 to limit upward movement of the front end portion 102 of the slider away from the respective guide rail 27 b . As shown in Figure 12, the shelf-like projection 115 is substantially laterally centered with respect to the block 113 and, at the side of the projection 115 facing away from the drum, a connector board 117 is secured, as by a screw 118, to a surface 119 of the block 113 which is inclined from a perpendicular to the surface 30 b of the guide rail 27 b at the same angle  3 as the front end surface 104 on the slider. Mounted on the connector board 117 are a pair of contacts 120 which, with the pair of contacts 107 on the connector board 105 complete the contact set 108. The contacts 120 are inclined similarly to the connector board 117 and are constituted by contact pins spring urged to project or protrude from respective housings 121. A harness 122 is connected to the connector board 117 to supplying power to the contacts 120. The above described arrangement for precisely locating the tape guiding device 20 b at its loaded position and there supplying power to its vibrated tape guide 25 b operates as follows: As the driving link 31 b moves the slider 21 b along the guide rail 30 b toward the loaded position of the tape guiding device 20 b in response to the turning of the respective drive ring 33 b in the direction of the arrow b in Figure 2, the forward end portion 102 of the slider moves under the shelf-like projection 115 of the positioning plate 114, and the ball 103 engages the underside of the shelf-like projection 115 while the locater pin 102 a enters the notch or cutout 116. From the point where the locater pin 102 a first enters the notch 116 to the point where the pin 102 a engages the surface of the notch 116, as in Figure 12, the slider 21 b travels the distance l 2 (Figure 15) in the direction of the arrow a . The contacts 107 on the connector board 105 first engage the extended, spring-urged contacts 120 on the connector board 117 as the locater pin 102 a enters the notch 116 so that, during the further movement of the slider 21 b through the distance L 2 to the loaded position, the contacts 120 are depressed in the inclined direction of the arrows k in Figures 13 and 15 which is at the angle  3 relative to the direction a of movement of the slider. As is shown particularly in Figure 15, by reason of the angle  3 between the direction of movement of the slider, indicated by the arrow a , and the direction in which the contacts 120 are depressed, as indicated by the arrow k , during the final movement of the slider through the distance L 2 to its loaded position, the point of engagement of each contact 107 with the respective contact 120 moves from the point P 1 to the point P 2 . In other words, the point of engagement between the depressible contact 120 and the respective contact 107 moves downwardly on the contact 107 through the small distance Δ L determined by the equation: ΔL = L 2  3 . The relative sliding movements of the contacts 107 and 120 effect automatic cleaning thereof to remove any corrosion or foreign matter that may have collected therebetween and that could otherwise cause faulty contact or increased contact resistance. Thus, with the described arrangement, the engagement of the contacts 107 and 120 is such as to ensure that the ultrasonically vibrated tape guides 25 a and 25 b will be reliably supplied with power when in their loaded positions. When the slider 21 b has been moved to its loaded position and the contacts 107 and 120 are engaged, as described above, the continued exertion of a driving force F 1 (Figure 13) by way of the link 31 b on the pin 29 b causes angular moments M 1 (Figure 12) and M 2 (Figure 13) to act on the slider. The angular moment M 1 acts horizontally about the locater pin 102 a , and the angular moment M 2 acts vertically about the step 101 a in the bottom surface 101 of the slider 21 b . As a result of the moment M 2 , the ball 103 is firmly pushed against an underlying surface 115 a of the shelf-like projection 115 in the direction indicated by the arrow Y (Figure 13). Further, by reason of the moment M 1 , the relatively short guide pin 100 depending from the bottom of the slider 21 b is pressed, in the direction of the arrow X (Figure 12) against one side 99 a of the respective guide groove 99. Moreover, reaction forces F 2 and F 3 are generated at the driving pin 29 b and at the engagement of the contacts 107 and 120 and act in the same directions as the moments M 1 and M 2 with the result that the slider 21 b can be smoothly and precisely disposed in its loaded position. Since the contacts 107 and 120 have a very short relative sliding or wiping distance Δ L when they are put into engagement with each other, faulty contact or increased contact resistance is avoided while minimizing the wear of the contacts 107 and 120. As a result, the durability-of the contacts 107 and 120 is enhanced significantly. The angle  3 at which the connector boards 105 and 117, and hence the contacts 107 and 120 are inclined can be varied, if desired, from the angle of 10° given above by way of example. The reaction forces F 2 and F 3 resulting from the mutual engagement of the contacts 107 and 120 are in no way opposed to the positioning force- of the locater pin 102 a moving in the approximately V-shaped notch 116. Thus, the slider 21 b is placed into its loading position with high precision, both in the horizontal and vertical directions, by use of the driving force F 1 , the reaction forces F 2 and F 3 and the angular moments M 1 and M 2 . Since the contacts 107 and 120 are situated at the side portions of the end surfaces 104 and 119 which extend away from the drum 14 when the respective slider 21 b is at its loaded position, the connector boards carrying the contacts are at the side of the shelf-like projection 115 and the locater pin 102 a facing away from the drum 14 with the result that the switch contacts 107 and 120 and their respective connector boards can be easily replaced when necessary. While the structure and operation of the tape guiding device 20 b and the arrangements provided for supplying power to its vibrated tape guide 25 b and for precisely locating the slider 21 b in the loaded position have been described in detail above with reference to Figures 12 to 15, it will be appreciated that the tape guiding device 20 a is similarly constructed and operates in the same manner.

Claims: Tape recording and/or reproducing apparatus comprising: a guide drum (14) with rotary head means thereon to move in a planar orbit coinciding with a circumferential surface of the drum (14) to record or reproduce signals in slant tracks scanned on a longitudinally transported tape (13) wrapped helically about the circumferential surface of the guide drum (14) between a tape-entry position (15 a ) and a tape-exit position (15 b ); a tape-guiding assembly including first and second tape guides (25 a , 25 b ) engageable by the tape adjacent the tape-entry (15 a ) and tape-exit (15 b ) positions, respectively, first and second auxiliary guide elements (26 a , 26 b ) disposed for engagement by the tape (13) between the first tape guide (25 a ) and the tape-entry position (15 b ) and between the second tape guide (25 b ) and the tape-exit position (15 b ), respectively, and means (22 a , 22 b ) to tension the tape; characterised in that said first and second tape guides (25 a , 25 b ) are ultrasonically vibrated, said first and second auxillary guide elements (26 a , 26 b ) are angled relative to the first and second tape guides (25 a , 25 b ), respectively, and the first and second auxiliary guide elements (26 a , 26 b ) have respective surface projections (71 a , 71 b ) extending therefrom at positions therealong corresponding to widthwise portions of the tape (13) at which the rotary head means scan the tape (13) adjacent the tape-entry and tape-exit positions, respectively, so that the surface projections (71 a , 71 b ) on the auxiliary guide elements (26 a , 26 b ) relatively increase tension in the tape (13) at the widthwise portions to minimise errors that may arise in the signals recorded or reproduced in the tracks adjacent the tape-entry and tape-exit positions due to vibrations transmitted along the tape from the vibrated tape guides (25 a , 25 b ). Tape recording and/or reproducing apparatus according to claim 1; in which the auxiliary guide elements (26 a , 26 b ) have elongate cylindrical surfaces with the surface projections (71 a , 71 b ) constituted by enlarged diameter portions thereof. Tape recording and/or reproducing apparatus according to claim 1 or claim 2; in which the vibrated tape guides (25 a , 25 b ) and the auxiliary guide elements (26 a , 26 b ) have respective longitudinal axes extending perpendicular to the longitudinal direction of the tape and perpendicular to the plane of the planar orbit of the rotary head means, respectively. Tape recording and/or reproducing apparatus according to claim 3; further comprising supply and take-up reel bases (12 a , 12 b ) rotatable about axes parallel to the longitudinal axes of the vibrated tape guides to support supply and take-up reels (11 b , 11 c ), respectively, at the same level, and from which the tape (13) is withdrawn to be wrapped about the guide drum (14); and in which the guide drum (14) has a tilted central axis to which the longitudinal axes of the auxiliary guide elements (26 a , 26 b ) are parallel. Tape recording and/or reproducing apparatus according to claim 1; in which each of the vibrated tape guides (25 a , 25 b ) includes a support shaft (81), a cylindrical bushing (86) slidable on the support shaft (81) and having a plurality of bearing rings (87) spaced apart in the axial direction on the outer surface of the bushing (86), with at least the bearing rings (87) being of a shock-absorbing material, a tubular tape guide (88) diametrically dimensioned to extend telescopically over the bushing (86) and be supported, at the inner surface (88a) of the tubular tape guide, by the bearing rings (87), and ultrasonic vibration generating means (89) fixed to the tubular tape guide (88) at a side thereof and operative to generate an ultrasonic standing wave oscillation in the tubular tape guide (88) with nodes thereof (N) substantially at the bearing rings. Tape recording and/or reproducing apparatus according to claim 5; in which the shock-absorbing material is a polycarbonate resin. Tape recording and/or reproducing apparatus according to claim 5 or claim 6; in which the bearing rings (87) and the bushing (86) are formed integrally of the shock-absorbing material. Tape recording and/or reproducing apparatus according to any of claims 5 to 7; in which each of the vibrated tape guides (25 a , 25 b ) further includes a base (21 a , 21 b ) from which the support shaft (81) extends upwardly, a threaded upper end portion (81a) on the support shaft (81), upper and lower flanges (91, 85) extending around the support shaft (81) at opposite ends of the bushing (86) and projecting beyond the outer surface of the tubular tape guide (88), spring means (82) about the support shaft (81) between the base (21 a ) and the lower flange (85), and a nut (94) engaged with the threaded upper end portion (81 a ) of the support shaft (81) and adjustable to displace the flanges (91, 85), the bushing (86) and the tubular tape guide (88), as a unit along the support shaft (81) against the yieldable resistance of the spring means (82). Tape recording and/or reproducing apparatus according to claim 8; in which each of the vibrated tape guides further includes a head (93) on the nut (94) and a spacer (92) between the head (93) and the upper flange (91), the head (93) having a circular rib (97) depending from a lower face thereof, and the spacer (92) having a part-circular arcuate slot (92 d ) receiving a portion of the circular rib (97) so that the upper flange (91) is canted relative to the axis of the shaft (81). Tape recording and/or reproducing apparatus according to any preceding claim; in which the tape (13) extends between supply (11 b ) and take-up (11 c ) reels in a cassette (11), the first vibrated tape guide (25 a ) and the first auxiliary guide element (26 a ) are mounted on a first slider (21 a ) and the second vibrated tape guide (25 b ) and the second auxiliary guide element (26 b ) are mounted on a second slider (21 b ) and the first and second sliders are mounted for movement between unloaded positions, in which the vibrated tape guides (25 a , 25 b ) and the auxiliary guide elements (26 a , 26 b ) are engageable with the tape (13) in the cassette (11), and loaded positions in which the first vibrated tape guide and the auxiliary guide element and the second vibrated tape guide and the auxiliary guide element are disposed adjacent the tape-entry (15 a ) and tape-exit (15 b ) positions, respectively; and further comprising main loading means (33 a , 33 b ) for moving the sliders (21 a , 21 b ) from the unloaded positions to the loaded positions so that the vibrated tape guides and auxiliary guide elements withdraw the tape from the cassette and wrap the tape about the circumferential surface of the guide drum (14) between the tape-entry (15a) and tape-exit (15 b ) positions. Tape recording and/or reproducing apparatus according to claim 10; in which the means to tension the tape includes at least one auxiliary loading guide element (22 a , 22 b ); and further comprising a support arm (36 a , 36 b ) carrying the auxiliary loading guide element (22 a , 22 b ) adjacent one end of the support arm and mounted for angular movements about a pivot axis (37 a , 37 b ) adjacent the other end of the support arm between an unloaded position in which the auxiliary loading guide element (22 a , 22 b ) is engageable with the tape (13) in the cassette (11) and a loaded position in which the auxiliary loading guide element also withdraws tape from the cassette and forms, in the withdrawn tape, a bight (23 a , 23 b ) directed laterally away from the guide drum (14) between the cassette (11) and the loaded position of the first vibrated tape guide (25 a ), a driving arm (50 a ) connected with the main loading means (33 a , 33 b ) to be driven thereby, a pair of pivotally connected links (51 a , 52 a ) extending between the driving arm (50 a ) and the support arm (36 a ) and being relatively angularly movable between an extended condition and a contracted condition, and limiter spring means (56 a , 56 b ) urging the links to the extended condition to move the support arm to the loaded position thereof when the main loading means move the sliders (21 a , 21 b ) to the loaded positions of the sliders, the links being moved to the contracted condition against the force of the limiter spring means when the tape tension in the bight exceeds a predetermined value, whereupon, the support arm (36 a ) is free to move substantially toward the unloaded position thereof to relieve the excess tension in the tape. Tape recording and/or reproducing apparatus according to claim 11; in which the main loading means includes counter-rotatable first and second drive rings (33 a , 33 b ) extending around the guide drum (14), first and second guide rails (27 a , 27 b ) along which the first and second sliders (21 a , 21 b ) are movable between the unloaded and loaded positions thereof, and drive links (51 a , 52 a ) pivotally connected between the first and second drive rings and the first and second sliders, respectively; and gear transmission means (44) angularly to turn the driving arm (50a) in response to turning of one of the drive rings (33 a , 33 b ) and having torque limiting means (47 a , 47 b ) interposed therein. Tape recording and/or reproducing apparatus according to claim 11 or claim 12; in which the links are pivotally connected to each other at a first axis (53 a , 53 b ) adjacent one end of the links and the other ends of the links are pivotally connected to the support arm (36 a , 36 b ) and the driving arm (50 a , 50 b ) respectively, at second and third axes, respectively, the limiter spring means (56 a , 56 b ) is connected between the driving arm (50 a , 50 b ) and the one (51 a , 51 b ) of the links connected thereto to urge said one link to turn in a first direction relative to the driving arm, and cooperative stop means (59 a , 59 b ) on the drive arm and the one link limit the turning of the one link in the first direction to a position in which lines extending from the first axis to the second and third axes, with the auxiliary loading guide element in the loaded position, include an obtuse angle a open in the first direction in which the limiter spring means urges the said one link to turn relative to the driving arm. Tape recording and/or reproducing apparatus according to any of claims 10 to 13; in which the main loading means includes guide rails (27 a , 27 b ) having surfaces on which the first and second sliders (21 a , 21 b ) are respectively slidable between the unloaded and loaded positions, and stopper means (112) fixed at each of the loaded positions to determine the position of the respective slider in the loaded position; and further comprising mutually engageable contact means (108) on each of the sliders and on the respective one of the stopper means (112) to supply energising power to the vibrated tape guide on the respective slider when the respective slider is disposed at the loaded position thereof, the mutually engageable contact means (107, 120) being disposed at an end surface (104) of the respective slider (21 a , 21 b ) and a surface of the respective stopper means (112) which comes into abutting relation therewith in response to movement of the respective slider to the loaded position thereof and which are inclined upwardly and forwardly, in the direction of the movement, from a perpendicular to the surface of the respective guide rail (27 a , 27 b ). Tape recording and/or reproducing apparatus according to claim 14; in which the contact means on each of the stopper means includes contact pins (120) projecting at right angles from the surface of the stopper means (112) and being depressed during a final increment of movement of the respective slider to the loaded position thereof so as to provide a wiping action of the mutually engageable contact means on each other. Tape recording and/or reproducing apparatus according to claim 14 or 15; in which each of the stopper means includes a shelf-like projection (115) extending over a portion of the respective slider (21 a , 21 b ) adjacent said end thereof. and each of the sliders has a ball (103) embedded in an upwardly facing surface of said portion thereof to bear against the shelf-like projection (115) and thereby limit the urging of said end of the slider (21 a , 21 b ) away from the guide rail surface (27 a , 27 b ), Tape recording and/or reproducing apparatus according to claim 16; in which the shelf-like projection (115) of each stopper means has a notch (116) in an edge thereof, each of the sliders has a laterally centered locater pin (102a) directed upwardly from said portion thereof and engaging in the notch (116) as the respective slider nears the loaded position thereof, each of the guide rails (27a, 27b) has a guide slot (28a, 28b) extending therethrough for passage of a drive pin (29 a , 29 b ) which depends from the respective slider (21 a , 21 b ) and, below the respective slider, is acted upon by the main loading means to move the respective slider, and each of the guide rails further has a guide groove (99) slidably receiving a guide pin (100) depending from the respective slider, the drive pin (29 a , 29 b ) and the guide pin (100) being spaced apart laterally at opposite sides of a central portion of the respective slider and being spaced from the locater pin (102 a ) in the direction away from said end surface of the respective slider. Tape recording and/or reproducing apparatus according to claim 16 or claim 17; in which each of the sliders has an undercut lower surface portion (101) adjacent an end of the respective slider remote from said end surface (104) to define a step (101 a ) about which the respective slider can be rocked to move the embedded ball (103) against the shelf-like projection (115). Tape recording and/or reproducing apparatus according to any of claims 16 to 18; in which the contact means (107) on each of the first and second sliders is at an end portion of the said end surface (104) which is laterally away from the guide drum, and the contact means (120) on each of the stopper means (112) is at a side of the respective shelf-like projection (115) facing away from the guide drum (14). An ultrasonic tape guiding apparatus comprising: a support shaft (81), a cylindrical bushing (86) slidable on the support shaft and having a plurality of bearing rings (87) spaced apart in the axial direction on the outer surface of the bushing, with at least the bearing rings being of a shock-absorbing material, a tubular tape guide (88) diametrically dimensioned to extend telescopically over the bushing and be supported, at the inner surface (88 a ) of the tubular tape guide, by the bearing rings (87), and ultrasonic vibration generating means (89) operative to generate an ultrasonic standing wave oscillation in the tubular tape guide with nodes thereof substantially at the bearing rings (87); characterised in that the ultrasonic vibration generating means is fixed on one side to the tubular tape guide. An ultrasonic tape guiding apparatus according to claim 20; in which the shock-absorbing material is a polycarbonate resin. An ultrasonic tape guiding apparatus according to claim 21 or claim 22; in which the bearing rings (87) and the bushing (86) are formed integrally of the shock-absorbing material. An ultrasonic tape guiding apparatus according to any of claims 20 to 22; further comprising a base (21a, 21b) from which the support shaft (81) extends upwardly, a threaded upper end portion (81 a ) on the support shaft, upper and lower flanges (91, 85) extending around the support shaft at opposite ends of the bushing and projecting beyond the outer surface of the tubular tape guide, spring means (82) about the support shaft between the base (21 a , 21 b ) and the lower flange (85), and a nut (94) engaged with the threaded upper end portion (81 a ) of the support shaft (81) and adjustable to displace the flanges, bushing and tubular tape guide, as a unit along the support shaft (81) against the yieldable resistance of the spring means (82). An ultrasonic tape guiding apparatus according to claim 23; further comprising a head (93) on the nut (94) and a spacer (92) between the head (93) and the upper flange (91) the head (93) having a circular rib (97) depending from a lower face thereof, and the spacer (92) having a part-circular arcuate slot (92d) receiving a portion of the circular rib (92) so that the upper flange (91) is canted relative to the axis of the shaft (81).

Inventors: KIRIYAMA HIROSHI, MASUDA SHIGERU, SHIMIZU OSAMU, TANIMURA KAZUNARI, KIRIYAMA, HIROSHI, MASUDA, SHIGERU, SHIMIZU, OSAMU, TANIMURA, KAZUNARI, KIRIYAMA, HIROSHI, C/O PATENTS DIVISION, Masuda, Shigeru, c/o Patents Division, Shimizu, Osamu, c/o Patents Division, Tanimura, Kazunari, c/o Patents Division
Applicants: SONY CORP, SONY CORPORATION
Application year: 1992
Main classification: G11B15
IPC codes: G11B15