Tape loading apparatus for drawing magnetic tapes

Abstract: A tape loading apparatus in which a rotation of a motor is transmitted to a loading ring (4) using a planetary gear arrangement (3), a loading mechanism is operated as the loading ring is moved to a tape loading position and the loading ring (4) is locked at the tape loading position by a locking mechanism (5). When the motor is reversely rotated, the lock mechanism (5) releases the loading ring. When the loading ring is released, the gear change action of the planetary gear unit causes, in turn, the rotation of the motor to be transmitted to the loading ring. Thus, the loading ring can be rotated in the unloading direction.

Description: BACKGROUND OF THE INVENTION : (1) Field of the invention : The present invention relates to a VTR (Video Tape Recorder) and relates particularly to a tape loading apparatus which can perform a loading and unloading of magnetic tapes utilizing a loading ring. (2) Background art : A tape loading apparatus using a loading ring generally includes a motor by means of which a tape loading ring is rotated by means of a rotational transmission mechanism to carry out a tape loading and unloading. Generally such apparatus engages an epicyclic gear to effect tape loading. A conventional rotational transmission mechanism generally includes: a rubber belt one end of which is suspended on a rotational axis of a motor; the other end of the rubber belt engages a worm gear; the worm gear meshes with a worm wheel; a pinion gear mounted on the worm wheel meshes with a gear surface provided on an outer circumferential surface of the loading ring. When a rotational axle of the motor is rotated in one direction, the loading ring is rotated in a loading ring direction (arrow marked direction) via the rubber belt, worm gear, worm wheel, pinion, and gear surface. When the loading ring is rotated until a tape loading end position, a stopper pin installed on a lower surface of the loading ring is contacted with a positioning pin installed on a chassis side and the rotation of a loading ring is stopped to finish the tape loading. (Refer to a Japanese Patent Utility Model Registration Second Publication No. Showa58-50516 published on November 17, 1983). In the above-described tape loading apparatus, a rubber belt is used so that when the stopper pin is contacted with the positioning pin at the chassis side, the belt slips, serving as a so-called limiter. In addition, the worm and worm gear are used as a loading ring mechanism so that the stopper pin is maintained in a state where the stopper pin is pressed against the positioning pin. The following problem arises in the previously proposed tape loading apparatus; (1) Since both worm and worm wheel are used, transmission of rotational force from the motor is less efficient. (2) When utilizing worm and worm wheel locking of the loading ring is not secure, and a relatively large force must be applied to the loading ring to reverse loading ring direction. (3) The rubber belt lacks durability, and must be replaced regularly so maintenance becomes troublesome. According to the preamble of claim 1 from US 4,056,833 a turntable assembly for video cassette recorder/reproducer is already known. This assembly comprises a loading ring on which a first boss is mounted so that loading ring is stopped thereby at the first loading position. Furthermore there is provided a motor, transmitting means for transmitting rotation of said motor to said loading ring, and locking means having a first lever and a second lever for locking said first boss at a position where said first boss is engaged by the first lever and by the second lever. In US 4,357,639 a similar assembly is described. A loading ring is there provided with a notch. When the loading ring is at a final loading position a positioning roller, mounted on a lever, is urged within that notch in order to prevent the rotation of the loading ring. Further, when the tape has reached its final position the positioning roller is no longer urged within the notch of the loading ring. It should therefore be appreciated that the loading ring is no longer restrained from rotating about the guide drum. A similar assembly is described in AT 384 686 B which is provided with a loading ring having a first boss by means of which the loading ring is stopped at a loading position. Said first boss abuts against a stopper which is fixed at the chassis of the assembly. Furthermore from US 4,884,153 a similar assembly is known, which is provided with a loading ring. As the tape loading operation is completed a projection provided on the ring makes contact with the stopper and interrupst the rotating of the loading ring. Finally from DE 34 12 527 A1 it is known to provide detecting means for monitoring and controlling the rotation position of the loading ring. In this assembly the rotation of the loading ring is not stopped at the final loading position. It is therefore an object of the present invention to provide a tape loading apparatus according to the preamble of claim 1 which provides a reliable operation. This object is solved by the advantageous feature of claim 1. BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is a perspective view of a tape loading apparatus of a preferred embodiment according to the present invention. Fig. 2 is an exploded perspective view of the tape loading apparatus shown in Fig. 1. Fig. 3 is a cross sectional view of the tape loading apparatus. Fig. 4 is an plan view of the tape loading apparatus before a loading ring is locked. Fig. 5 is a plan view in which the loading ring is locked. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT: Reference will hereinafter be made to the drawings in order to facilitate a better understanding of the present invention. Figs. 1 through 5 show a tape loading apparatus in a preferred embodiment according to the present invention. In Figs. 1 and 2, the numeral 1 generally denotes a tape loading apparatus. The tape loading apparatus 1 rotates the loading ring via a rotational transmission mechanism 3. When the loading ring 4 rotates until a tape loading position, a lock mechanism 5 causes the loading ring 4 to lock. The locking mechanism 5 includes: a) a trigger lever 7 which is pressed by a stopper pin installed on a lower surface of the loading ring 4 when the loading ring 4 is rotated to a vicinity of a loading end position; and b) a lock lever 9 for positioning the loading ring 4 at a tape loading position with the stopper pin pressed against a positioning pin 8 installed on a chassis. The trigger lever 7 is pivotally supported on a tape loading mechanism frame 11. In addition, rotational force in a counterclockwise direction (as viewed from Fig. 1) is applied thereto by means of a coil spring 12 engaged with one end of the trigger lever 7. A pin contacting portion 13 is installed on the other end of the trigger lever 7. The stopper pin 6 installed on the loading ring 4 is contacted with the pin contacting portion 13. A roller 14 is installed between the pin contacting portion 13 and an axle 10. The roller 14 is fitted into a roller fitting bore 15 installed on the lock lever 9. The lock lever 9 has one end provided with a bearing hole 16. The lock lever 9 is pivoted with a main axle 18 of a planetary gear unit 17 as a center. The lock lever 9 has the other end engaged with a coil spring 19. The lock lever 9, thereby, receives pivoting force in the counterclockwise direction by means of the spring force of the coil spring 19. In addition, the roller fitting bore 15 is formed substantially arc shaped with the main axle 18 as the center. One end of its internal circumferential surface is formed with a step portion 20 for engaging the roller 14. The step portion 20 is engaged with the roller 14 so as to block the pivoting of the lock lever 9 toward the counterclockwise direction. As shown in Fig. 2, an internal tooth wheel engaging pin 21 is installed between the lock fitting bore 15 of the lock lever 9 and bearing hole 16 so as to be inserted into an elongated hole 24 installed on a bottom surface 23 of the internal tooth wheel 22 of the planetary gear unit 17. The structure of the lock mechanism 5 in the preferred embodiment is as described above. When the loading ring 4 is rotated in the vicinity of an loading end position, the stopper pin 6 installed on a lower surface of the loading ring 4 is contacted with the pin contacting portion 13 of the trigger lever 7. When the trigger lever 7 is pivoted in the clockwise direction, the roller 14 installed on the trigger lever 7 is disengaged from the step portion 20 installed on the internal circumferential surface of the roller fitting hole 15. The lock lever 9 is pivoted in the counterclockwise direction by means of the spring force of the coil spring 19. A stopper pin pressing surface 25 located on one side portion of the lock lever 9, causes the pin contacting portion 13 to press against the positioning pin 8 with the stopper pin 6 grasped by the pin contacting portion 13 of the trigger lever 7 so that the loading ring 4 is positioned and fixed at the loading position. Next, a structure of a rotational transmission mechanism 3 which transmits the rotational force of the motor 2 to the loading ring 4 will be described below. The rotational transmission mechanism 3 includes a pinion 27 installed on a rotational axis 26 of the motor 2, double gears 29 having large and small diameters for deceleration in which a large diameter gear portion thereof is meshed with the pinion 27, a reduction gear group 32 having a spur gear 31 meshed with the smaller diameter gear portion 30 of the double gear 29, and the planetary gear unit 17 which is rotationally operated via the reduction gear group 32. The planetary gear unit 17 includes an internal tooth gear 22 rotatably mounted on the main axle 18, as shown in fig. 2, and external tooth gear 33 rotatably mounted on the main axle 18, overlapped with the upper end surface of the internal tooth gear 22. A lower surface of the outer gear wheel 33 is provided with a pair of planetary gears 35, 36 rotatably mounted thereon and placed symmetrically with the bearing bore 34 as the center. Outward facing surface portions of the planetary gears 35, 36 are meshed with the internal gear 37 mounted on the inner circumferential surface of the inner tooth gear 22. On the other hand, since the inner facing surfaces of the planetary gears 35, 36 are meshed with the gear 38 fixed on the upper end of the main axle. The outer gear 39 installed on an outer circumferential surface of the outer tooth gear is meshed with a gear surface 40 installed on an outer circumferential surface of the loading ring 4. Then, after the lower end of the main axle 18 is inserted into the bearing bore 16 of the lock lever 9, the lower end thereof is inserted into the bearing hole 41 of the spur 31 so as to rotate with the spur 31. An operation of the rotational transmission mechanism and planetary gear unit 17 will be described with reference to Figs. 4 and 5. Fig. 4 shows a state in which the stopper 6 installed on a lower surface of the loading ring 4 has been moved to the vicinity of the pin contacting portion 13 of the trigger lever 7 with the loading ring 4 rotated in the direction of the tape loading direction. That is to say, when, with the loading ring 4 placed at the tape unloading position, the motor 2 is rotated in the clockwise direction the double gear 29 is rotated in the counterclockwise direction. Thus, the spur 31, meshed with the double gear 29, is rotated in the clockwise direction. Then, the main axle 18 inserted under pressure in the bearing bore 41 and gear 38 fixed on the upper end of the main axle 18 are rotated in the clockwise direction. Then, planetary gears 35, 36 meshed with the inner tooth gear 37 are rotated in the counterclockwise direction. The inner tooth gear 37 receives the rotational force from the planetary gears 35, 36. However, since the inner tooth gear engaging pin 21 installed on the lock lever 9 is inserted in the elongated hole 24 installed on the inner tooth gear 22, the lock lever 9 is locked so as not to rotate in the counterclockwise direction since the step portion 20 is engaged with the roller 14 installed on the trigger lever 7. Hence, since the inner tooth gear 22 is not rotated, the planetary gears 35, 36 are pivoted in the clockwise direction with the main axle 18 as a center, rotating in the clockwise direction. The outer tooth gear 33 on which the planetary gear is mounted is rotated in the clockwise direction so that the outer tooth gear 33 causes the loading ring 4 to rotate in the counterclockwise direction. When the loading ring 4 is further rotated in the counterclockwise direction from a state as shown in Fig. 4, the stopper pin 6 is brought in contact with the pin contacting portion 13 of the trigger lever 7. Furthermore, when the loading ring 4 is rotated in the counterclockwise direction, the stopper pin 6 causes the pin contacting portion 13 to be pressed under pressure. The trigger lever 7 is pivoted in the clockwise direction against the biasing force of the coil spring 12. When the pin contacting portion 13 is pivoted toward a position at which it is contacted with the positioning pin 8 installed on the chassis side, the roller 14 installed on the trigger lever 7 is disengaged from the roller engaging step portion 20 of the roller fitting hole 15. When the lock lever 9 is pivoted in the counterclockwise direction by means of a spring force of the coil spring 19, the stopper pin 6 and pin contacting portion 13 are pressed on the positioning pin 8 by means of a stopper pin pressing surface 25, on a side surface of the lock lever 9, as shown in Fig. 5. The pin 6 and contacting portion 13 correspond to a tape loading position of the loading ring 4. It is noted that an elongated hole is installed on the inner tooth gear 22 provides, the hole acts as the limiter so as to prevent breakage of the gear and so on. When the motor 2 is reversely rotated (in the counterclockwise direction) with the loading ring 4 in a locked state as shown in Fig. 5, the main axle 18 and the gear 38 fixed to the main axle 18 are rotated in the counterclockwise direction via the reduction gear group 32. Then, the planetary gears 35, 36 meshed with the gear 38 are rotated in the clockwise direction. Since the loading ring 4 is locked, the outer tooth gear 33 meshed with the loading ring 4 does not rotate. Hence, the inner tooth gear 22 meshed with the planetary gears 35, 36 are rotated in the clockwise direction. The lock lever 9 installed on the inner tooth gear engaging pin 21 to be engaged with the elongated hole 24 installed in the inner tooth gear 22 is pivoted in the clockwise direction. Then, when the lock lever 9 is rotated through a predetermined angle in the clockwise direction, the step portion 20 of the roller fitting hole 15 installed on the lock lever 9 becomes in the vicinity to the position of the roller 14. At this time, pressure on the stopper pin 6 by means of the stopper pin pressing surface 25 is released. Therefore, since locking of the loading ring 4 by means of the lock lever 9 is released, the lock of the outer tooth gear 33 locked via the loading ring 4 is necessarily released. The outer tooth gear 33 is enabled to be rotated. Counterclockwise rotation of the motor 2 is transmitted to the main axle 32 and gear 38 fixed to the main axle 32, the gear 38 being rotated in the counterclockwise direction. The planetary gears 35, 36 meshed with the gear 38 are rotated in the clockwise direction. Then, since the pivoting of the lock lever 9 in the counterclockwise direction is limited by means of the roller fitting hole 15 installed on the lock lever 9 and the roller 14 fitted thereinto, the lock lever 9 is fixed if it is pivoted through the predetermined angle. Hence, the planetary gears 35, 36 are rotated in the counterclockwise direction with the main axle 18 as a center since the inner tooth gear 22 does not rotate as well. The outer tooth gear 33 on which the planetary gears 35, 36 are rotated in the counterclockwise direction and thereby the loading ring 4 is rotated in the clockwise direction, that is to say, in the unloading direction. It is noted that numeral 42 shown in Fig. 2 denotes a manual crank and the manual crank 42 is mounted on an upper end of the main axle 18. When the main axle 18 is rotated, the tape loading mechanism according to the present invention can be manually operated. Therefore, if a failure occurs in an electric system or the motor 2, the tape can be extracted. The structure of the tape loading mechanism in the preferred embodiment is described above. When the motor 2 is rotated in one direction, the loading ring 4 is moved in the loading direction. When the loading ring 4 is brought into the position at which the tape loading is ended, the loading ring 4 is automatically locked by means of the lock mechanism 5. After the end of record and playback of a tape, the motor 2 is reversely rotated. The lock mechanism 5 is operated upon the action of the planetary gears 17. The lock of the loading ring 4 by means of the loading ring 4 is released. When the lock of the loading ring 4 is released, the gear change action of the gear assembly 17 causes the loading ring 4 to rotate in the unloading direction. Thus, the unloading of the tape is, thus, carried out. The structure of the lock mechanism is not limited to that in the preferred embodiment although the tape loading mechanism is constituted by the lock mechanism 5, trigger lever 7, and lock lever 9. The following effects are provided according to the structure of the tape loading mechanism described hereinabove. (1) Since neither worm gear nor worm wheel is used, the transmission efficiency of the rotating force of the motor can be enhanced, therefore the motor can be miniaturized and the power consumption can be reduced. (2) Since a rubber belt is not used, durability is increased and easy maintenance can be achieved. (3) Since the lock mechanism is used, the locking effect can be secured compared with constructions in which the locking function is effected by using a worm and worm wheel. In addition, rotation of the motor is switched by means of the operating force of the lock mechanism and rotating force of the loading ring. After the force of the motor is used to release the lock of the loading ring, the force of the motor can continuously rotate the loading ring in the unloading direction. It will be fully appreciated by those skilled in the art that the foregoing description has been made in terms of the preferred embodiment and various changes and modifications may be made without departing from the scope of the present invention which is to be defined by the appended claims.

Claims: A tape loading apparatus for drawing magnetic tape around a circumferential surface of a tape guide drum comprising: a loading ring (4) on which a first boss (6) is mounted so that said loading ring (4) is mounted so that said loading ring (4) is stopped thereby at a first loading position, a motor (2), transmitting means (3) for transmitting rotation of said motor (2) to said loading ring, and locking means having a first lever (9) and a second lever (7) for locking said first boss at a position where said first boss (6) is engaged by one of the first lever (9) and second lever (7) characterized in that a second boss (8) is provided for stopping a rotation of said loading ring (4) at a second position at which a loading operation is completed, whereby one of said first and second lever (7, 9) contacts said second boss (8) at said second position said first boss (6) is engaged by the first lever (9) and by the second lever (7), said transmitting means (3) comprise an epicyclic train (12) and in that said first lever (9) has a third boss (21) which is engaged to said epicyclic train (17) so that a rotation of said epicyclic train is limited thereby. The tape loading apparatus according to claim 1, in which said first lever has a roller, and said second lever is energized to rotate a predetermined direction and has an L-shaped hole. The tape loading apparatus according to claim 2, in which said epicyclic train comprises a first gear having a wall on which gear teeth are formed, and a second gear on which at least one planet gear is rotatably mounted, said second gear and said planet gear being engaged to said loading ring and said gear teeth of said first gear respectively, and a main shaft having gear teeth for engaging said first and second gears so as to drive same in response to rotation of said motor.

Inventors: TANAKA SEIKI, TANAKA, SEIKI
Applicants: SONY CORP, SONY CORPORATION
Application year: 1990
Main classification: G11B15
IPC codes: G11B15