JPH01145464A - Drive selecting mechanism - Google Patents

Abstract

PURPOSE:To alternately actuate two driven members using a single drive source by providing a wheel having a circular arc-shaped groove part and a linear groove part and a moving member having a stopper moving along both the groove parts. CONSTITUTION:A worm 10 is provided to be slidably arranged in the axial direction of a rotary shaft 12, while a turning effect is transmitted from the rotary shaft 12. A cam wheel 20 has a circular arc-shaped groove part 25 and a linear groove part 26. A stopper 32, which moves along the groove parts 25, 26, is fixedly provided to be arranged in the upper surface of a moving plate 30. When the stopper 32 is placed in the first groove part 25, the wheel 20 is able to rotate. When the stopper 32 is placed in the second groove part 26, the wheel 20 is unable to rotate, and the moving plate 30 moves. In this way, two driven members can be alternately actuated by using a single drive source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive switching mechanism, and more particularly to a drive switching mechanism that can alternately operate two driven members by one drive source.

[Conventional technology]

Generally, when operating two independent driven members alternately, a dedicated drive source is provided for each driven member,
When the operation of one driven member is completed, each drive source is switched and controlled so that the other driven member is operated. However, in the above case, a plurality of drive sources are required, and the control means for controlling each drive source also becomes complicated.

Therefore, it is common practice to extract two driving forces for alternately operating two driven members from one driving source via a drive switching mechanism. For example, in this type of drive switching mechanism, two cams having different cam curves are operated by one drive source, and these two cams alternately operate two independent driven members. There is.

[Problem that the invention seeks to solve]

However, in the case of the drive switching mechanism described above, since it uses a cam, it is not possible to obtain a sufficient stroke or rotation amount to operate the driven member, and if you try to obtain a sufficient stroke or rotation amount, the cam The problem arises of increasing the size.

The present invention has been made in view of the above circumstances, and allows two driven members to be operated alternately using one drive source, as well as a large stroke for operating each member with a small mechanism. It is an object of the present invention to provide a power switching mechanism that can obtain rotation amount, etc.

[Means for solving problems]

In order to solve the above object, the present invention includes a worm to which rotational force is transmitted from a rotational shaft and is slidably disposed in the axial direction of the rotational shaft; a wheel having a first groove portion and a linear second groove portion continuous with the first groove portion; a moving member that engages with one end and has a stopper that moves along the first and second grooves, and the wheel is rotatable when the stopper is in the first groove. So, the second
When the worm is in the groove, the wheel becomes unrotatable, and the moving member moves in accordance with the movement of the rotating shaft of the worm in the axial direction.

[Effect]

According to the present invention, when the rotation of the wheel rotated by the worm is prevented, a thrust force is applied to the worm in the direction of its rotation axis, and the rotation of the wheel and the movement of the worm in the axial direction are It is possible to switch between two types of power. That is, the movable member is provided with a stopper so as to prevent the wheel from rotating once it has rotated by a certain amount, and when a rotational force is applied to the worm after the rotation of the wheel is prevented, the stopper is arranged to be slidable in the direction of the rotation axis of the worm. The provided worm moves as the worm rotates, and the moving member that engages with the worm also moves. At this time, in order to allow the moving member to move, the wheel is formed with a linear groove that is prevented from rotating by the stopper but allows the stopper to move.

〔Example〕

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

1 and 2 are plan views showing the loading mechanism of a VTR to which the power switching mechanism according to the present invention is applied, respectively. FIG. 1 shows the state before loading starts, and FIG. 2 shows the state after loading is completed. ing. This power switching mechanism is
It mainly consists of a worm lO, a cam wheel 20, and a moving chassis 30.

The worm 10 is disposed to be slidable in the axial direction of the rotating shaft 12, and engages with the D-cut portion 12A of the rotating shaft 12 so that rotational force is transmitted from the rotating shaft 12. . Further, a gear 14 is fixedly arranged on the rotating shaft 12,
A worm 16A disposed on the drive shaft of a loading motor 16 meshes with this gear 14.

The cam wheel 20 is rotatably disposed on a shaft 21 installed on the main chassis 40 (A-A in FIG. 3(B)).
(See FIG. 5, which is a cross-sectional view taken along the line), a cam groove 2OA is formed on the upper surface and a pin 22 is implanted therein, and two semicircular members 23 and 24 are provided on the lower surface as shown in FIG.
Accordingly, an arcuate groove portion 25 and a linear groove portion 26 are provided. Also, a gear 2 is provided around the cam wheel 20.
0B is formed. An intermediate gear 27 is disposed between the cam wheel 20 and the worm lO,
The rotational force of the worm 10 is transmitted to the cam wheel 20 via an intermediate gear 27.

Moreover, the moving plate 30 has three long holes 30A130A.
A guide hole 30B into which the shaft 21 of the cam wheel 20 is inserted is formed substantially in the middle of the main chassis 40, and a rack 31 is formed at the upper end. . Further, on the upper surface of the moving plate 30, a groove portion 25 provided on the lower surface of the cam wheel 20 is provided.
．． A stopper 32 that moves along the line 26 is fixedly disposed,
An engaging piece 33 that engages with one end of the worm 10 is bent at the lower end of the moving plate 30 (see FIG. 5).

Next, the loading mechanism of a VTR to which the drive switching mechanism of the above configuration is applied and its operation will be briefly described.

This loading mechanism has a mechanism for pulling out the tape in the video cassette and winding the tape around the rotating head drum 42. A loading ring 43 is disposed around the rotating head drum 42, and A guide roller and a tilted post (not shown) are arranged in the . Further, a gear group 44 for driving the loading ring is disposed between the loading ring 43 and the rack 31 of the movable plate 30.

Therefore, as will be described later, when the movable blade 30 moves and the loading ring 43 rotates via the gear group 44, the tape is pulled out from the cassette by the guide rollers, inclined posts, etc. on the loading ring 43 and wound around the rotating head drum 42. It will be done.

On the other hand, this loading mechanism is based on the rotating head drum 42.
A movable chassis 45 is disposed so as to be movable forward and backward in the direction, and the video cassette is configured to be mounted on this movable chassis 45. This movable chassis 45 is formed with a guide hole 45A that engages with the bin 22 planted on the top surface of the cam wheel 20, and a hook that engages with the bin 34, 34 that is planted on the movable plate 30. Shape guide holes 45B, 45B are formed.

Therefore, when the cam wheel 20 rotates as will be described later, the movable chassis 45 moves to the bin 22 on the cam wheel 20.
Move forward and backward. The reason why the cassette is moved forward and backward relative to the rotary head drum 42 by the movable chassis 45 is to downsize the VTR. Further, the movable chassis 45 needs to move toward the rotary head drum 42 after tape loading is performed by the loading ring 43 and the like so that the cassette and the guide rollers of the loading ring 43 and the like do not interfere with each other.

Furthermore, an arm 46 is disposed on the main chassis 40 so as to be rotatable about a fulcrum 46A, and the arm 46 is inserted into a cam groove 2OA formed on the upper surface of the cam wheel 20 at a substantially central portion of the arm 46. A cam follower 46B is provided. Therefore, when the cam wheel 20 rotates, the arm 46
swings around the fulcrum 46A. This operation of the arm 46 releases a cassette brake (not shown), moves a guide near the tape entrance/exit of the cassette, and presses the pinch roller against the capstan.

Next, a substitute for the drive switching mechanism according to the present invention will be explained.

3(A) to 3(D) are diagrams showing each operating state of the drive switching mechanism, and FIGS. 3(A) and 3(D) are diagrams showing before the start of loading in FIG. 1 and during loading in FIG. 2, respectively. Corresponds to the operating state after completion.

First, when the loading motor 16 is driven from the state shown in FIG. 3 (A) and the worm 10 rotates in the loading direction, this rotational force is transmitted to the cam wheel 20 via the intermediate gear 27.

At this time, the stopper 32 on the moving plate 30 is located in the arcuate groove 25 on the lower surface of the cam wheel 20, so the cam wheel 20 is rotatable.

Therefore, the cam wheel 20 rotates about the shaft 21 in a counterclockwise direction (<CCW direction). Note that the moving plate 30 cannot be moved in the left-right direction because the right end of the guide hole 30B is in contact with the shaft 21 and the stopper 32 is in sliding contact with the circumferential surface of the semicircular member 24.
The worm 10 with which the engaging piece 33 engages is also immovable in the axial direction.

The cam wheel 20 is rotated CCW from the position shown in FIG. 3(A).
When the cam wheel 20 is rotated approximately 70 degrees in the CCW direction, the stopper 32 comes into contact with the linear surface of the semicircular member 23, thereby preventing the cam wheel 20 from rotating in the CCW direction. Also, due to the rotation of the cam wheel 20 during this period, the arm 46 is moved into the cam groove 2 of the cam wheel 20.
It is rotated in the CCW direction by the OA, and as described above, the cassette brake is released and the guide near the tape entrance/exit of the cassette is moved. On the other hand, since the pin 22 on the cam wheel 20 moves along the arc portion of the guide hole 45 of the movable chassis 45 (see FIG. 1), the movable chassis 45 does not move.

In the state shown in FIG. 3(B), when the worm 10 rotates in the loading direction, the cam wheel 20 and the intermediate gear 27 are prevented from rotating.
0 in the axial direction of the rotating shaft 12, that is, the third
Start moving to the right on the diagram ('B) and move plate 3.
0 moves in the same direction as the ohm 10 moves. Note that the stopper 32 on the moving plate 30 is connected to the cam wheel 2.
0 along the linear groove 26 on the lower surface.

Due to the movement of the moving plate 30, the moving plate 30
The loading ring 43 is rotated via the rack 31 and the four gear groups, and a required tape loading operation is performed. When the moving plate 30 reaches the position shown in FIG. 3(C), the guide groove 30B of the moving plate 30 prevents the moving plate 30 from moving in the right direction, and the cam wheel 20 is again allowed to rotate in the CCW direction. Become.

In FIG. 3(C), when the worm 10 further rotates in the loading direction, this rotational force is transmitted to the cam wheel 20 via the intermediate gear 27.
Rotate in the CCW direction.

This rotation of the cam wheel 20 causes the cam wheel 20 to
The movable chassis 45, whose pin 22 is engaged with the guide hole 45A, starts moving in the direction of the rotary head drum 42, and when the cam wheel 20 reaches the position shown in FIG. 3(D), , the movable chassis 45 moves to the forward end (see FIG. 2).

In addition, by reversing the loading motor 16,
It is also possible to perform an operation opposite to that described above, ie an unloading operation.

As described above, this drive switching mechanism alternately extracts the driving force for moving the moving plate 30 and the driving force for rotating the cam wheel 20 from the driving force of one loading motor 16, and The loading mechanism can be caused to perform a predetermined operation.

Although this embodiment describes a case in which the drive switching mechanism is applied to the loading mechanism of a VTR, this drive switching mechanism is not limited to this and can be applied to other devices that require alternate operation of two driven members. Mechanisms are applicable.

〔Effect of the invention〕

As explained above, according to the drive switching mechanism according to the present invention, it is possible to alternately operate two independent driven members using one drive source, and the mechanism uses a cam or the like. It is possible to obtain a large drive stroke or rotation amount with a smaller and lighter mechanism compared to the previous model.

[Brief explanation of the drawing]

1 and 2 are plan views showing a loading mechanism of a VTR to which the drive switching mechanism according to the present invention is applied, respectively;
Figures 3 (Δ) to (D) are diagrams showing each operating state of the drive switching mechanism, Figure 4 is a perspective view of the cam wheel in the drive switching mechanism seen from the back side, and Figure 5 is the figure 3. It is a sectional view along line A- of (B). 10... Worm, 12... Rotating shaft, 20
...Cam wheel, 23.24...Semicircular member, 25.26...Groove portion, 30...Moving plate, 31...Rack, 32...Stopper.

Claims (1)

[Scope of Claims] A worm to which rotational force is transmitted from a rotational shaft and slidably arranged in the axial direction of the rotational shaft; and a first arc-shaped groove to which rotational force is transmitted from the worm. and a linear second groove continuous to the first groove, the wheel being disposed so as to be movable in substantially the same direction as the axial direction of the rotating shaft and engaging with one end of the worm. a moving member having a stopper that moves along the first and second grooves; when the stopper is in the first groove, the wheel is rotatable; The drive switching mechanism is characterized in that when the wheel is in the groove, the wheel is unable to rotate, and the moving member moves as the worm moves in the axial direction of the rotating shaft of the worm.