JPH01182956A - Intermittent movement mechanism - Google Patents

Abstract

PURPOSE:To obtain an optimum mechanism for the tape loading of a VTR with a miniature and simple constitution by constituting by a driving member and a follower member and achieving many conditions required for a tape loading mechanism in the same mechanism. CONSTITUTION:When rotational pins 76 and 78 of a driving member and rotational channel parts 84 and 86 of the follower member are not engaging, a rotation stopping wall part 74 and a rotation stopping channel part 82 are abutted and the rotation of the follower member is obstructed, and when they are engaging, the abutment of the rotation stopping wall part 74 and the rotation stopping channel part 82 is released and the follower member is rotated. Then, at least when the rotational pins 76 and 78 are positioned on the line to link the two rotational spindle of the driving member and the follower member, the rotational pins 76 and 78 are constituted to be retracted against spring energizing force by the rotational channel parts 84 and 86. Thus, the intermittent movement mechanism of a miniature and simple constitution can be realized. Besides, on a loading start, impact force is not added to a tape, and also the positioning accuracy and so on of a mobile member on a loading end can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intermittent movement mechanism, and is particularly applicable to a tape loading mechanism in a VTR, etc., and is suitable for moving a certain moving member in a specific period of time. Regarding.

[Conventional technology]

A tape loading mechanism in a video tape recorder (VTR) pulls out a tape from a cassette and winds it around a rotating head drum to form a tape running system, and generally the tape loading operation is performed according to a predetermined order.

Taking the case of an 8mm VTR as an example, first move the two swing-out bins installed near the left and right tape entrances on the inside of the tape in the cassette mouth part from inside the cassette mouse to the outside, pull out the tape from inside the cassette, and then , the tape is separated from the wall inside the cassette, thereby making it possible to subsequently pull out the tape from inside the cassette without damaging the tape. Next, the tape loading guide pulls out more tape from the cassette and wraps it around the rotating head drum. In addition, a type of VTR in which the chassis on which the cassette is installed moves relative to the chassis on which the rotating head drum is arranged.
At the same time as the tape is wound around the rotary head drum, or after winding is completed, the chassis with the cassette mounted thereon is moved toward the rotary head drum.

By the way, in order to move the above-mentioned swinging pin, tape loading guide, etc. separately, a plurality of drive sources are required, and the control means for controlling each drive source also becomes complicated.

On the other hand, as a mechanism for moving a plurality of movable members at appropriate times using a single drive source, there is a groove cam mechanism having a plurality of groove cam curves, or a mechanism in which rotation is transmitted using a gear and rotation is stopped using a cam. Some devices utilize an intermittent movement mechanism in which a driven member to which rotational motion is intermittently transmitted from a driving member moves another moving member.

[Problem that the invention seeks to solve]

However, when using the above-mentioned grooved cam mechanism, it is not possible to obtain a sufficient stroke or rotation amount to operate the moving member, and in order to obtain a sufficient stroke or rotation amount, the cam becomes larger. arise. In addition, in order to apply the intermittent movement mechanism using gears to the tape loading mechanism of a VTR, the switching between rotation and stop is rapid, and as soon as rotation starts, the loader speed becomes steady, giving an impact to the tape, and when stopping, the steady speed is reduced. After loading, the tape suddenly stopped and the tape was prone to cracking. Furthermore, even if a large resistance force is generated due to some kind of accident when drawing out the tape, there is no effective means for detecting this and stopping the tape drawing without damaging the tape.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an intermittent motion mechanism suitable for a VTR0 loading mechanism that is small in size and simple in structure.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention forms an arcuate rotation stopper wall part on the upper or lower surface of a rotating drive member, the rotation axis of which is the center of electrical conductivity, and the rotation stopper wall part is formed. l or a plurality of rotating pins are disposed within a predetermined central angle range, are movable in the radial direction, and are always spring-biased in the outer circumferential direction. An arc-shaped rotation stopper groove is formed that contacts the stopper wall, and a rotation groove is formed that engages with the rotation pin and is cut in the radial direction of the rotation pin, so that the rotation pin of the drive member and the rotation groove of the driven member are non-contact. During the engagement, the rotation stopper wall and the rotation stopper groove come into contact to prevent the driven member from rotating, and during the engagement, the rotation stopper wall and the rotation stopper groove come out of contact and the driven member is prevented from rotating. When the member rotates and at least the rotating pin is located on a line connecting two rotational axes of the driving member and the driven member, the rotating pin is configured to be retracted by the rotating groove portion against the spring biasing force. It is characterized by

[Operation] According to the present invention, the driving member and the driven member constitute an intermittent motion mechanism, and when the rotation pin of the driving member is not engaged with the rotation groove of the driven member, the rotational power of the driving member is is not transmitted to the driven member, and the driven member is fixed unrotatably by the rotation stopper wall of the drive member and the rotation stopper groove of the driven member coming into contact with each other. Further, when the rotating pin of the driving member engages with the rotating groove of the driven member within a predetermined rotation angle range of the driving member, the rotation of the driving member is transmitted to the driven member via the rotating pin and the rotating groove member, and Within a predetermined rotation angle range, the contact between the rotation stopper wall and the rotation stopper groove is released, and the driven member rotates. Furthermore, at the beginning and end of the engagement between the rotation pin and the rotation groove, the rotation speed of the driven member is slow, and at the middle point of engagement where the rotation speed of the driven member is the highest, the rotation pin is retreated by the rotation groove, so that the rotation speed of the driven member is slow. The rotation speed near the point is suppressed and the speed is made uniform. Furthermore, if the rotating pin and the groove are duplicated, when a rotational load greater than the spring urging force in the outer circumferential direction on the rotating pin is applied to the driven member, the retracted rotating pin returns after the midpoint of engagement between the rotating pin and the groove. This makes it impossible to transmit the rotational power through the rotation pin and the groove, and it is possible to stop the transmission of power with less damage to the tape. As described above, according to the present invention, many conditions required for a tape loading mechanism are achieved within the same mechanism, and a VT
An optimal intermittent movement mechanism can be provided for the R tape loading mechanism.

〔Example〕

Preferred embodiments of the intermittent motion mechanism according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is a plan view showing an embodiment of the mechanical part of a tape recorder to which the intermittent motion mechanism according to the present invention is applied, and shows an apparatus using an 8 mm video cassette as the tape cassette. Incidentally, FIG. 2 shows a state in which the cassette 10 is installed in a predetermined position and tape loading is completed.

In FIG. 2, 20 is a fixed chassis and 22 is a movable chassis. A rotary head drum 26 and a loading ring 28 are disposed on the fixed chassis 20, and a pinch roller 36, a guide roller 38, 40, and an inclined post 42 are also disposed thereon, and a loading guide 30 is disposed on the loading ring 28. , guide roller 32
and inclined posts 34 are installed.

On the other hand, the movable chassis 22 includes a pair of left and right reel stands 50.
．． 52, capstan 54, and shaker bottle 56.5
8th grade is placed. FIG. 3 is a view seen from the direction of arrow A in FIG. 2. As shown in the figure, the movable chassis 22 is provided to be able to move forward and backward by a certain amount in the directions of arrows B and C with respect to the fixed chassis 20, and when the cassette 10 is attached or removed, it moves to the backward end of the arrow C, and when the tape loading is completed. Move in the direction of arrow B to the forward end.

The loading ring 28 on the fixed chassis 20 side rotates counterclockwise during loading, pulls out the tape from the cassette 10 by the tape loading guide 30, etc., and forms a tape bus on the exit side of the rotating head drum 26, - During unloading, the tape rotates clockwise, and the tape loading guide 30 and the like inside the tape move into the cassette mouth section. Further, the guide roller 38 moves to the left in FIG. 2 during loading, and the guide roller 40 and inclined post 42 move from the cassette mouth portion to the illustrated position in FIG. 2 during loading. Furthermore, the swinging pins 56 and 58 of the movable chassis 22 each move from the cassette mouth portion to the illustrated position in FIG. 2 at the start of loading.

FIG. 1 is a plan view showing a loading ring drive section on a fixed chassis. In the figure, a worm 62 is attached to the drive shaft of a loading motor 60, and this worm 62 meshes with a gear 64. Also, gear 6
A gear 66 disposed coaxially with the tape 4 meshes with a gear 70, which is rotated clockwise during tape loading.

The rotational force of the gear 80 is transmitted only within a predetermined rotation angle range of the gear 70. In addition, gears 70 and 8
The details of 0 will be described later.

When gear 80 rotates, its rotation is increased in speed by gear group 90 and transmitted to loading ring 28, which rotates counterclockwise during tape loading.

Next, the intermittent movement mechanism according to the present invention will be explained.

This intermittent movement mechanism is constituted by the gears 70 and 80 mentioned above. 4(A) and (B) are perspective views of gears 70 and 80, respectively, and FIG. 5(A) and (B) are perspective views of gears 70 and 80, respectively.
These are a plan view and a front view, respectively, of the gears 70 and 80 in an assembled state.

As shown in these drawings, the lower surface of the gear 70 has an arc-shaped rotation stopper wall 74 whose center of curvature is the rotation axis 72.
are formed, and two rotating bins 76.
78 are disposed so as to be movable in the radial direction.

That is, the rotating pin is connected to the rotating shaft 7 as shown in FIG. 5(A).
The slide plate 77 has two long holes 77A and 77B that engage with the guide pin 77C and the rear end of the slide plate 77 and the inside of the rotation stopper wall 74. A spring 79 is provided that biases the plate 77 in the direction of advancing (the direction in which the rotation pin moves away from the rotation shaft 72 of the gear 70). Therefore, the rotating pins 76, 78 are each movable in the radial direction of the gear 70, and are normally located at a predetermined forward end due to the biasing force of the spring 79, but the rotating pins 76, 78 exceed the spring biasing force. When a force is applied, the rotation pins 76,78 retract in the direction of the rotation axis 72.

On the other hand, the upper surface of the gear 80 is formed with an arc-shaped rotation stopper groove 82 that comes into contact with the rotation stopper wall 74 of the gear 70, and two rotation grooves 84 that mesh with the rotation pins 76 and 78 of the gear 70. .86 is formed.

With the above configuration, as shown in FIG. 5(A), the gear 70
does not transmit rotational power to the gear 80 when neither of its rotation pins 76, 78 are engaged with the rotation grooves 84, 86 of the gear 80, and the rotation stopper wall 74 of the gear 70
slides along the rotation stopper groove 82 of the gear 80. In this state, the gear 80 is fixed so that it cannot rotate because the rotation stop wall 74 and the rotation stop groove 82 are in contact with each other.

When the gear 70 reaches the rotational position shown in FIG. becomes rotatable.

Therefore, when the gear 70 rotates clockwise from the state shown in FIG. When the rotation pin 78 is removed from the rotation groove 84, the rotation pin 78 simultaneously begins to engage the rotation groove 86. When the rotation pin 78 is removed from the rotation groove 86, rotational power is no longer transmitted to the gear 80, and the rotation stopper wall 74 and the rotation stopper groove 82 fix the gear 80 so that it cannot rotate again.

That is, the gear 80 is rotated by the rotational power transmitted only when the gear 7o is within a predetermined rotation angle range, and is fixed so as not to rotate when the gear 7o is within a predetermined rotation angle range. Further, the rotation speed of the gear 80 increases as the rotation pin enters the rotation groove, and decreases as the rotation pin moves out of the rotation groove. Further, the length of the rotation groove is not long enough to allow the rotation pin to rotate while being located at the forward end, and therefore, when the rotation pin reaches the deep end of the rotation groove, the rotation pin (slide plate 77) is then rotated by the rotation of the gear 70. Slide towards the center. This causes the rotation pin to rotate between gears 70 and 8.
When the gear 80 is located on or near the line connecting the zero rotation centers, the rotation speed of the gear 80 is suppressed and the rotation speed can be averaged.

Further, by utilizing the fact that the rotating pins 76 and 78 move back and forth depending on the force applied to the rotating pins, it is possible to prevent excessive load torque from being applied to the gear 8°.

That is, as shown in FIG. 6, when a load torque is applied to the gear 8o and becomes stronger than the biasing force of the spring 79, the rotating pin 76 rotates without being fully extended.

If the rotating pin 76 does not fully extend and separates from the rotating groove 84,
The next rotating pin 78 does not mesh with the rotating groove 86 and hits the side surface, making the gear 70 unable to rotate. Therefore, no further overload torque is applied to the gear 80, so that the loading operation can be stopped before an abnormal tension is applied to the tape to the extent that the rotation of the loading motor stops. Note that by adjusting the biasing force of the spring 79, the maximum torque that can be transmitted to the gear 80 can be set.

On the other hand, the gear 70 can drive mechanical parts other than the loading ring 28 by providing a cam groove or the like on its upper surface.

7(A) to (C) show a cam groove 71 on the top surface of the gear 70.
An example of a case where a pin 73 is provided is shown.The cam groove 71 has a lever 7 rotatably disposed around a fulcrum 75A.
The cam follower 75B of No. 5 is fitted, and the pin 73
is fitted into a hole 22A formed in the movable chassis 22.

Therefore, when the gear 70 rotates from the position shown in FIG. 7(A) to the position shown in FIG. 7(B), the lever 75 is rotated clockwise as its cam follower 75B moves along the cam groove 71. The rotation of the lever 75 is used to move, for example, the left and right swinging pins 56 and 58. Note that at this time, since the pin 73 moves along the hole 22A, the movable chassis does not move.

Subsequently, when the gear 70 rotates from the position shown in FIG. 7(B) to the position shown in FIG. 7(C), the hole 22A is removed from the pin 73.
Power is transmitted to the movable chassis 22 via the movable chassis 22, and the movable chassis 22 moves to the forward end.

Next, the tape loading operation by the loading mechanism having the above configuration will be explained in detail with reference to FIGS. 8(A) to 8(D).

FIG. 8(A) shows a state in which the cassette 10 is installed in a predetermined position and before tape loading is started.

In this state, the movable chassis 22 is located at the backward position,
Furthermore, all the movable members that should be located inside the tape, including the tape loading guide on the loading ring 28, are located within the cassette set mouth section. Further, the gear 70 is in the position shown in FIG. 7(A).

From this state, the loading motor 60 rotates, and the gear 7
0 rotates from the position shown in FIG. 7(A) to the position shown in FIG. 7(B), the rotation of the lever 75 as described above causes the left and right swinging pins 56 to move as shown in FIG. and 58 respectively as shown by the arrows, and the cassette 10
A tape bus is formed at the tape inlet/outlet of the tape.

Next, when the gear 70 further rotates clockwise from the position shown in FIG. 7(A), that is, the position shown in FIG. 5(A),
The rotational power is transmitted to the gear 80, and the loading ring 28 starts rotating, and the movable chassis 22 also starts moving (FIG. 8(C)). In the initial stage of rotation of the loading ring 28, since the rotation speed is slow, no excessive force or impact force is applied to the tape, and no damage to the tape is caused.

When the gear 80 rotates until it is stopped again, the loading ring 28 reaches the position shown in FIG. 8(D), the tape in the cassette is pulled out by the tape loading guide 30, and the tape bus on the drum exit side is It is formed. Furthermore, the movable chassis 22 also moves to the forward end. Furthermore, the guide roller 20 and the inclined post 42 also move in the direction shown by the arrow to form a tape bus on the drum entrance side, and the guide roller 38 also moves in the direction of the arrow to complete tape loading.

In this embodiment, the intermittent movement mechanism consisting of gears 70 and 80 is applied to the tape loading mechanism of a VTR.
The present invention is not limited to this, and can be applied to other devices that require intermittent motion. Furthermore, the number of rotating pins and rotating grooves is not limited to this embodiment.

〔Effect of the invention〕

According to the intermittent motion mechanism according to the present invention, it is possible to realize an intermittent motion mechanism that is small and has a simple structure. Also, the speed is slow at the beginning and end of the intermittent motion, and the speed in the middle is not very fast and can be kept constant, so if this mechanism is applied to the loading mechanism of a VTR,
The loading operation can be performed smoothly, and in particular, there is an advantage that no impact force is applied to the tape at the start of loading, and the positioning accuracy of the moving member at the end of loading can also be improved. If a plurality of rotation pins are provided, if the driven member becomes overloaded, the driving force will not be mechanically transmitted to the driven member, and the means moved by the driven member can be protected.

[Brief explanation of the drawing]

Figure 1 shows a VTR to which the intermittent motion mechanism according to the present invention is applied.
A plan view showing an example of the loading drive part of the V
3 is a plan view showing the entire mechanism of the TR, FIG. 3 is a view taken in the direction of arrow A in FIG. 2, and FIGS. 4(A) and (B) are perspective views of the gears shown in FIG. 1, respectively. Figure 5 (A) and (B)
are a plan view and a front view of the combined gears shown in FIGS. 4(A) and (B), respectively, and FIG. 6 is a plan view and a front view of the gears shown in FIG.
) Figure 7 shows the gear shown in Fig. 7 under overload.
Figures (A) to (C) are diagrams showing respective operating states of other moving members moved by gears, and Figure 8 (A).
7A to 7D are plan views showing respective operating states of the loading mechanism. 10... Cassette, 20... Fixed chassis,
22... Moving chassis, 26... Rotating head drum, 28... Loading ring, 70.8
0... Gear, 74... Rotation stopper wall, 76.78
...Rotating pin, 77...Slide plate, 7
9... Spring, 82... Rotation stopper groove, 84.
86...Rotating groove section.

Claims (1)

[Claims] An arc-shaped rotation stopper wall with the rotation axis as the center of curvature is formed on the upper or lower surface of the rotating drive member, and a predetermined central angle where the rotation stop wall is not formed is formed on the upper or lower surface of the rotating drive member. One or more rotating pins located within the range, movable in the radial direction, and always spring-biased in the outer circumferential direction are arranged, and the driven member rotatably arranged abuts on the rotation stopper wall. An arc-shaped rotation stop groove is formed, and a rotation groove is formed that engages with the rotation pin and is cut in the radial direction of the rotation pin, and when the rotation pin of the driving member and the rotation groove of the driven member are not engaged, the rotation groove is formed. The rotation stop wall and the rotation stop groove come into contact to prevent the driven member from rotating, and during engagement, the rotation stop wall and the rotation stop groove come out of contact and the driven member rotates, and at least The rotating pin is a driving member and a driven member.
An intermittent movement mechanism characterized in that the rotation pin is configured to be moved backward by the rotation groove portion against a spring biasing force when the rotation pin is located on a line connecting two rotation axes.