TAPE DRIVE MECHANISM

Abstract: A tape drive mechanism for a video tape recorder and an audio tape recorder. The tape drive mechanism automatically corrects the position in the direction of width of the running tape without mechanically restricting the edge of tape. Sensors (8) and (8) on a tape path detect change of position from a reference running position that may develop in the direction of width of the tape (7), a tape guide post (1) for attracting the tape (7) is moved in the direction of width of the tape, or inclination of a tape guide post (41) is changed to move the tape (7) in the direction of width being driven by actuators (2), (42) and (62) that give corresponding displacement based on the values detected by the sensors (8) and (8), or the reel plate (57) is moved in the direction of width of tape to move the tape (7) together with the reel (24). The tape (7) having a small thickness is suppressed from moving up and down on the tape path and is permitted to run stably without being damaged on the edges.

Description: Technical Field The present invention relates to tape drive mechanism, and, more particularly, to a tape drive mechanism for a magnetic recording/reproducing apparatus such as a video tape recorder and an audio tape recorder which drives a magnetic tape to record or reproduce data. Background Art Video tape recorders or audio recorders perform a tape drive operation by means of a tape drive mechanism provided therein, but are basically prone to such trouble that, if the tape, while being driven by that drive mechanism, is dislocated in its width-wise direction, the track of the tape results in deviation, making thus inactive the recording/reproducing functions of those recorders. As disclosed in FR-A-7518147 to avoid the trouble, the arrangement of hitherto, conventional tape drive mechanism has been such that the tape guide posts, which allows sliding of a tape upon each of their surfaces, are equipped with a flange in order for the upper end of the tape or the lower end of same to come in contact with the flange, or in the mechanism of the type having a rotary drum, a lead is formed on the outer surface of the drum, whereby the tape is mechanically limited its running in the width-wise direction and thus the running position of the tape is adjustingly retained within a given normal point. Further, in the past, no particular tape drive mechanism has been proposed, which has a function for positively eliminating a non-neatly or non-uniformly wound state of the tape around a tape reel. This poor tape winding has been forcibly caused into a normal winding state by use of the flange of tape guide post or lead on the rotary drum. However, such prior-art arrangement is based on the forcible way to cause the edges of tape (both side edges of tape as viewed width-wise) to coincide with the flanges of the tape guide post or the lead of the rotary drum, so as to mechanically restrict the running path of the tape within the width-wise direction. Consequently, if the tape is badly non-neatly wound upon a cassette reel, if the tape guide post is not disposed exactly in a perpendicular relation with the tape, or if the tape is run out of a normal path excessively in its width-wise direction due to an excessive large tension exerted on the tape, then the tape being run is at its edges subject to a non-rectilinear friction from the foregoing tape guide post flanges or lead of rotary drum, and the tape per se is not run along stably, which creates a jitters, and may give a damage to the tape in a worst case. Those unfavorable aspects will be more serious, if the tape is of a more thin thickness, and possibly the tape may be prevented from running in a worst situation. For the reasons, it has been difficult to reduce the thickness of the tape as well as to increase a memory capacity of the tape. Disclosure of the Invention An object of the present invention is to provide a tape drive mechanism for causing a stable run of a tape having a reduced thickness, without damaging the edge of the tape. More particularly, an object of the present invention is to provide a tape drive mechanism capable of automatically correcting the position of a tape in the direction of the height of the tape, that is, in the direction of the width of the tape without performing a mechanical restriction of the tape edges. An object of the present invention is to realize a reliable stable run of a tape and to reduce the thickness of the tape for the purpose of enlarging the memory or store capacity of the tape and preventing generation of jitters. According to an aspect of the present invention there is provided a tape drive mechanism comprising: a sensor for detecting an amount of dislocation of a tape from a reference running position in a width-wise direction of said tape and an actuator for moving the tape in said width-wise direction in response to a detection signal being supplied from said sensor, characterised in that: said actuator moves either or both of a supply reel base and a winding reel base in the width-wise direction of said tape in accordance with the amount of tape dislocation supplied from said sensor. Consequently, the sensor detects to what degree the tape is dislocated from the reference running position in its width-wise direction, when rewinding the tape or driving it for reproducing/recording purpose. the actuator disposed on the reel base is feedback-controlled responsive to such degree of tape dislocation, so as to return the tape to a normal height or the reference running position. Thus, even if non-uniform winding of the tape is generated due to the positional change in the direction of the width of the tape on the tape path, the tape can be rewound to the supply reel base with the change corrected. Furthermore, if there is non-uniform winding which could not be eliminated at the time of the running of the tape, it can be restored to the normal state. Therefore, according to the present invention, the change of the position of a tape taken place due to the non-uniform winding of the reel, change in the rotation and change in the tape tension can be restricted. In particular, in a case where a thin type tape having poor rigidity is used, the restricting force acting between the lead of the rotational drum or the like and the tape edges can be reduced. As a result, the tape can be reliably and stably run on a predetermined tape path without the damage of the tape edges. Brief Description of the Drawings Figs. 1,2 and 3, 4 illustrate an embodiment of the tape drive mechanism according to the present invention, wherein Fig. 1 is a front elevational view which illustrates a state in which the present invention is applied to a supply reel base, Fig. 2 is a broken-away central longitudinally sectional view which illustrates an example of specific structure of a reel base device, and Figures 3 and 4 are front elevational views which, excluding Fig. 3, respectively illustrate another embodiment of the actuator for moving the reel base. Figure 5 is a plan view of a VHS video tape recorder. Referring to Figure 5, a tape 7 is drawn out from a supply reel 25 of a cassette 24, then introduced along by a limiter post 26, an impedance roller 27 and a vertical post 28, which are all at the side of inlet of the drive system, and brought into contact with the circumferential surface of the rotary drum 17 in a properly inclined state relative thereto within a given limit of inclination angle. The tape 7 is then run along through another vertical post 29, impedance roller 30 and pinch roller 32, all of them being at the outlet side of the drive system, and wound around a winding reel 33 of the same cassette 24. Best Mode for Carrying Out the Invention The structure of the present invention will now be described with reference to an embodiment of the present invention. Figs. 1 to 4 illustrate an embodiment of the present invention, which suggests displacing a reel in the width-wise direction of a tape 7 in order to limit the position of the tape 7 in the direction of the width of the tape 7. Fig. 1 shows an embodiment in which a voice coil motor is employed as an actuator for moving a reel base vertically. According to this embodiment, a reel base 57 for supporting a reel, namely, the supply reel 25 and a reel base operating motor 58 for rotating the reel base 57 are supported via a coil guide portion 59, on a base member or the like of a VTR or the like in such a manner that they can be moved in the direction of the width of the tape 7. A voice coil 61, which formes the voice coil motor 62 together with a magnet 60 secured to the base member or the like, is fastened to the lower surface of the reel base operating motor 58. In this connection, if sensors 8 detect the dislocation of the edges of the tape 7, electric signals are imparted therefrom to the voice coil 61, thereby generating a repulsive force between the coil 61 and magnet 60, which force causes the movement of the reel base 57 in the width-wise direction of the tape 7. More specifically, as shown in Fig. 2, the reel base device according to this embodiment comprises the reel base 57 having a reel base boss 57a, a reel shaft 63 rotatably supporting the reel base 57, a stator board 65 supported on the reel shaft 63, the coil guide portion 59 for supporting the reel shaft 63 via a linear slider 64 in such a manner that the reel shaft 63 can be moved in the axial direction, a reel base motor coil 66 and the voice coil motor 61 secured to the stator board 65, the voice coil magnet 60 which constitutes the voice coil motor 62 in association with the voice coil 61 of the stator board 65, a yoke 73 for supporting and securing the voice coil motor 62 to the base or the like and the reel base motor magnet 67 secured to the lower portion of the reel base 57 and constituting the reel base operating motor 58 in association with the coil 66 of the stator board 65. The stator board 65 and the coil guide portion 59 are arranged such as to permit them to be movable in the axial direction and prevent their rotation by means of a rotation stopping pin 68. With the above-mentioned structure, supplying an electricity to the reel motor coil 66 causes the rotation of the reel base 57, and in the event of the sensors 8 detecting a width-wise dislocation of the tape edges, output signals are imparted therefrom so as to energize the voice coil 61, thereby generating a repulsive force between the coil 61 and voice magnet 60, which then causes a vertical movement of the reel base 57 as well as the stator board 65. Thus, it is seen that the reel base 57 is rotated and moved in a vertical direction (i.e. in the width-wise direction of the tape 7). In the drawings, reference numeral 69 represents a flange for fastening the magnet 67 to the reel base 57, 70 represents a ball bearing and 71 represents a collar. Generally, an ordinary video tape cassette accommodates a reel therein, allowing a slight movement of the reel in the width-wise direction of the tape 7. For example, as shown in Fig. 1, the VTR cassette 24 is of such structure that a leaf spring 72 is provided at the upper side of the cassette 24, and has an end portion adapted for resiliently keeping the displacement of the supply reel 25 and a winding reel (not shown) towards the reel base when the cassette 24 is loaded in a recorder. The cassette 24, therefore, permits a slight movements of the supply reel 25 and reel base 25 to be executed by the voice coil motor 62 in the width-wise direction of the tape, insofar as the movements occur within the vertical stroke limit of the leaf spring 72, wherein, of course, the upward movement of them overcomes the force of the leaf spring 72. As the sensors 8, 8 for detecting the dislocation of the tape edges, an optical sensor or other sensors may be employed. The sensors are usually disposed along the tape path between the reel base 57 and the tape guide post, for instance. From the construction above, it is to be understood that, when rewinding the tape 7 around the supply reel 25, the optical sensors 8, 8 detect whether or not the upper and lower edges of the tape 7 are maintained within a predetermined reference height, and if the tape 7 is dislocated out of the reference position, the amount of the tape dislocation or deviation is imparted through the sensors 8, 8 and fed back to the coil 61 of the voice coil motor 62, thereby generating a proper repulsive force between the voice magnet 60 and voice coil so as to cause a desired vertical movement of the reel base 57, the repulsive force being varied in proportion to an mount of power supplied, whereby the tape 7 is so controlled to keep running at a height level within a predetermined normal height limit. This prevents an undesired non-uniform winding of the tape 7 around the reel 25. Hence, in driving the tape for a reproducing or recording purpose, the sensors 8, 8 may detect a non-uniform winding state of the tape 7 which has not yet been corrected during the rewinding, or the width-wise deviation of the tape 7 which occurs due to an uneven rotation of the reel, and then a detected amount of those phenomena is fed back to the voice coil motor 62 which causes a proper vertical movement of the reel base 57 and supply reel 25, to thereby correct the height of the tape, thus attaining a long reliable tape drive system. According to the above-described embodiments, the voice coil motor is employed as the actuator for vertically moving the reel base 57. However, the actuator 62 is not limited to the above-described structure. Any actuator may be employed if it displays excellent responsibility to the feedback control such as a piezoelectric actuator served by the piezoelectric device 73 as shown in Fig. 3 or an air cylinder as shown in Fig. 4. While the reel case operating motor 58 is mounted on the reel base 57 in accordance with the above-described embodiments, the reel base 57 may be, via an idler or the like, connected to another separate reel operating motor. If a further precise tape running operation is desired, the actuator 62 may be provided on the winding reel in addition to the supply reel. Industrial Applicability The tape drive mechanism according to the present invention can be suitably employed in a video tape recorder, a digital audio tape recorder or the like which uses a tape for broadcasting or a tape having a relatively reduced thickness and in which the running of the tape must be stably controlled. The tape drive mechanism according to the present invention can be used as the tape drive mechanism for a usual analog audio tape recorder as well as the tape drive mechanism for the above-described helical scan type tape recorder.

Claims: A tape drive mechanism comprising: a sensor (8) for detecting an amount of dislocation of a tape (7) from a reference running position in a width-wise direction of said tape (7) and an actuator (62) for moving the tape in said width-wise direction in response to a detection signal being supplied from said sensor, characterised in that: said actuator (62) moves either or both of a supply reel base (25, 57) and a winding reel base (33, 57) in the width-wise direction of said tape in accordance with the amount of tape dislocation supplied from said sensor (8). The tape drive mechanism according to claim 1, wherein either or both of said supply reel base (25, 57) and winding reel base (33, 57) can be rotated and moved simultaneously in the width-wise direction of said tape so as to cause either or both said reel bases (57) to be moved in the width-wise direction of said tape (7) by an output from said sensor (8) and said tape (7) is thereby maintained at a predetermined position. The tape drive mechanism according to claim 2, wherein said supply reel base includes a motor (58) for rotating said reel base (57) and an actuator (62) for vertically moving said reel base (57).

Inventors: ABE K NIPP HOSO KYOKAI HOSO GI, GOTOH MASAKI K K SANKYO SEIKI, HASHIZUME T K K KAISHA SANKYO, KATOU D NIP HOSO KYOKAI HOSO G, MITSUYASU T NIPP HOSO KYOKAI H, MIYASHITA MITSUTAKA K K SANKYO, OKINA T K K SANKYO SEIKI SEISA, SEKIGUCHI T NIPP HOSO KYOKAI H, YANAGISAWA H N HOSO KYOKAI HOS, ABE, K. NIPP. HOSO KYOKAI HOSO GIJUTSU KENKYUSHO, GOTOH, MASAKI K.K. SANKYO SEIKI SEISAKUSHO, HASHIZUME, T. K.K. KAISHA SANKYO SEIKISEISAKUSHO, KATOU, D. NIP. HOSO KYOKAI HOSO GIJUTSU KENKYUSHO, MITSUYASU, T. NIPP. HOSO KYOKAI HOSO GIJUTSUKEN., MIYASHITA, MITSUTAKA K.K. SANKYO SEIKISEISAKUSHO, OKINA, T. K.K. SANKYO SEIKI SEISAKUSHO KOMAGANE, SEKIGUCHI, T. NIPP. HOSO KYOKAI HOSO GIJUTSU KEN., YANAGISAWA, H. N. HOSO KYOKAI HOSO GIJUTSU KEN.
Applicants: JAPAN BROADCASTING CORP, SANKYO SEIKI SEISAKUSHO KK, KABUSHIKI KAISHA SANKYO SEIKI SEISAKUSHO, NIPPON HOSO KYOKAI
Application year: 1989
Main classification: G11B15
IPC codes: G11B15