JPH0411247Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a driving force transmitting device, and more particularly to a driving force transmitting device in a tape pull-out mechanism of a video tape recorder or the like.

BACKGROUND ART FIG. 5 is a typical prior art top view.
The base 1 is equipped with a planar grooved cam 2. This planar grooved cam 2 is rotatable around the axis of a shaft 3. A gear 4 is formed on the outer periphery of the planar grooved cam 2. Further, the planar groove cam 2 has a spiral cam groove 5, into which a follower 6 is fitted.
This follower 6 is fixed to a sector-shaped partial gear 7. This partial gear 7 is pivotally supported on the base 1 by a shaft 8. Therefore, this partial gear 7 has a shaft 8
can be angularly displaced around the axis of A partially toothed gear 9 meshes with the partial gear 7. A partially-toothed gear 11 having a larger diameter than the partially-toothed gear 9 is fixed coaxially to the rotating shaft 10 of the partially-toothed gear 9.

The cam 2 is rotated by a driving force that is decelerated by a transmission mechanism from a driving source such as a motor (not shown). As a result, the follower 6 moves along the cam groove 5, and the partial gear 7 is angularly displaced around the axis of the shaft 8. This causes the partially toothed gear 9 to rotate, and thereby the partially partially toothed gear 11 to rotate. The driving force thus applied to the cam 2 is transmitted to the partially toothed gear 11. The driving force from the partially toothed gear 11 is transmitted to a subsequent cam mechanism (not shown), thereby loading the videotape at a predetermined position.

Problems to be Solved by the Invention In the above prior art, the partially toothed gears 9 and 11 must be disposed near the cam 2, and when downsizing the video tape recorder, the partially toothed gears 9,
11 or other locations where the cam 2 can be installed, the installation positions of the partially toothed gears 9, 11 and the cam 2 are restricted, and therefore, they cannot be installed freely. This has become a problem in trying to make video tapes smaller.

The purpose of this invention is to solve the above technical problems,
A drive system that does not restrict the positional relationship between the cam and the gear to which the driving force is transmitted by the cam, allows the cam and the gear to be freely arranged, and that also enables reliable transmission of the driving force. An object of the present invention is to provide a force transmission device.

Means for Solving the Problems The present invention includes a base 21 and a cam groove 26 that is rotatably provided on the base 21 around the first shaft 25 and is formed substantially spirally around the axis of rotation. a rotating body 24 having: means 22 and 23 for rotationally driving the rotating pair 24; and a lever 27 pivotally supported on the base 21 so as to be angularly displaceable around a second shaft 29;
The lever 27 is provided with a follower 28 that fits into the cam groove 26, and has one end pin-coupled by a pin 60 on the opposite side of the second shaft 29 with respect to the follower 28 of the lever 27. It is a longitudinal link 30, and a rack 31 is formed along the longitudinal direction at the other end of the link 30, and a longitudinal guide portion 35 extending along the longitudinal direction is formed between the one end and the other end. The longitudinal guide portion 35 includes a link 30 formed, a protrusion 39 provided on the base 21 and fitted into the longitudinal guide portion 35, and a gear 32 provided on the base 21 and meshed with the rack 31. This driving force transmission device is characterized in that the link 30 is guided so that the pitch line of the rack 31 and the pitch circle of the gear 32 are always in contact with each other.

Effect According to the present invention, the rotating body 24 is rotationally driven by the rotational drive means 22 and 23, and thereby the follower 28 is provided which fits into the cam groove 26 formed in the rotating body 24. A lever 27 is angularly displaced, and a link 30 pin-coupled by a pin 60 on the side opposite to the second shaft 29 with respect to the follower 28 of the lever 27 is provided with a longitudinal guide portion extending along the longitudinal direction of the link 30. A protrusion 39 is fitted into the longitudinal guide portion 35, and as the link 30 is displaced, a gear 32, which is a pinion that meshes with a rack 31 formed at the other end of the link 30, is angularly displaced. is the pitch line of rack 31 and gear 3
Link 30 so that the pitch circle of 2 is always in contact with
Since the gear 32 is shaped to be guided, the gear 32 is reliably rotationally driven and the power from the rotation driving means 32 is reliably transmitted to the gear 32. In such a configuration, the link 30 is not configured to move linearly, so the arrangement of the rotating body 24, the lever 27, and the link 30 can be set freely, and the lever 27 and the link 30 are connected to each other by a pin. 60, which can reduce frictional force.

Embodiment FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a sectional view thereof. A geared motor 22 is attached to the base 21. A gear 23 is fixed to the output shaft of the geared motor 22 at the same time. This gear 23 is a cam gear 24 which is a rotating body.
It meshes with a gear 24a carved on the outer periphery of. The cam gear 24 is rotatable around the axis of a shaft 25 erected on the base 21 . A substantially spiral cam groove 26 is formed on the upper surface 24b of the cam gear 24, which is perpendicular to the shaft 25. A follower 28 fixed to the lever 27 is loosely fitted into the cam groove 26 . The lever 27 is pivoted by a shaft 29 so that it can be angularly displaced about the axis of the shaft 29.

Here, the distance between the cam follower 28 and the shaft 25, that is, the cam radius, is S, and the follower 28 of the cam groove 26
The movement start position of the cam gear 2 is defined as Q1, the movement end position of the follower 28 of the cam groove 26 is defined as Q2, and the cam gear 2
Let the rotation angle of 4 be α. At this time, the relationship between the cam radius S and the rotation angle α is shown in FIG. That is, when the cam gear 24 rotates 100 degrees from the movement start position Q1, the cam radius S is maintained at a constant value as indicated by reference numeral m1. Then, when the cam gear 24 is angularly displaced from the rotation angle of 100 degrees to 200 degrees, the cam gear S gradually decreases at an inclination angle β as indicated by reference numeral m2.
When the cam radius S is angularly displaced from 200 degrees to 250 degrees, the cam radius S gradually decreases with the inclination angle γ, as indicated by reference numeral m3. Note that this inclination angle γ is selected to be larger than the inclination angle β. and cam gear 2
When 4 rotates from an angle of 250 degrees to 360 degrees,
The cam radius S remains constant, as indicated by reference m4.

The other end of the lever 27 is attached to the link 30 with a pin 60.
pin-coupled by. A rack 31 is formed at one end of this link 30 (diagonally downward in FIG. 1). This rack 31 meshes with a partially toothed gear 32. Another partially toothed gear 34 is coaxially fixed to the shaft 33 of this partially toothed gear 32 . The partially toothed gear 34 is selected to have a larger diameter than the partially partially toothed gear 32. A guide slot 35 is formed in the link 30 to guide the link 30 so that the pitch line of the rack 31 and the pitch circle of the partially toothed gear 32 are always in contact with each other. A protrusion 39 formed on a substrate 36 disposed above the link 30 is loosely fitted into the guide hole 35 . One end of the link 30 is located on the opposite side of the second shaft 29 (the first
(on the left side of the figure) by a pin 60 as described above. A rack 31 is formed at the other end of the link 30 along its longitudinal direction. Between the one end and the other end of the link 30, a guide elongated hole 35, which is a longitudinal guide portion extending in the longitudinal direction, is formed. As is clear from FIG. 2, the substrate 36 is fixed to the base 21, and therefore the protrusion 39 is fixed to the base 21.

The shape of the guide slot 35 is determined based on the following calculation formula. That is, referring to FIG. 4, let the coordinates of the axis 29 be C ₀ (0, 0) and the coordinates of the axis 33 be C ₁ (x ₀ , y ₀ ). Also, the shaft 29 of the lever 27
The length of the link 30 and the pin 60 is l ₁ , and the coordinates of the point P _x located at a distance l ₂ from the pin 60 of the link 30 are P _x (x,
y), the width of the link 30 is b, and the partially toothed gear 3
Let R be the pitch circle radius of 2. At this time, P _x (x,
y) is expressed by the first and second equations using the angle θ between the positive direction of the X-axis and the lever 27 as a parameter.

x=l ₁ cosθ−l ₂ sin(θ _a −θ _b ) …(1) y=l ₁ sinθ−l ₂ cos(θ _a −θ _b )……(2) Here, θ _a and θ _b are Shown below.

In this way, the point P _x (x,
The shape of the guide slot 35 is determined so that y) can draw the trajectory shown by the first equation.

One end of the link 37 restrained by the partially toothed gear 34 is connected to a support plate 40 with a pin. A guide groove 41 is provided upright on the support plate 40 . This guide shaft 41 is movable along the guide groove 42. This guide shaft 41 is used to pull out the tape from inside the tape cassette and load the tape onto the rotating head when loading the video cassette. That is, when the partially toothed gear 34 rotates in the direction of the arrow, the guide shaft 41 reaches the movement end position G of the guide groove 42 along the guide groove 42 . This causes the tape in the cassette to come into contact with the outer peripheral surface of the rotary head. By rotating the rotary head, the tape is reproduced or recorded.

Next, the operation of the driving force transmission device having the above configuration will be explained. Geared motor 22
When energized with power, the cam gear 24 is rotationally driven in the direction of the arrow via the gear 23. As a result, the lever 27 is moved to the shaft 29 via the follower 28.
is angularly displaced about the axis of link 3, thereby causing link 3
0 is displaced in the direction of the arrow, the partially toothed gear 32 is rotationally driven via the rack 31, and the partially toothed gear 34 is also rotationally driven in the direction of the arrow. Therefore, the guide shaft 41 moves along the guide groove 42 via the link 37.

When the tape recording or playback operation is completed, the geared motor 22 is driven to rotate in the opposite direction to that in the above case, thereby causing the link 30 to move in the opposite direction to the direction of the arrow, so that the link 37 Then, the guide shaft 41 moves along the guide groove 42 and returns to its original state. This ensures that the drawn tape is in its original position within the cassette.

By using the link 30 in this manner, the positional relationship between the cam gear 24 and the partially toothed gears 32 and 34 can be freely arranged without being restricted. Therefore, free design is possible. Moreover, for this reason, it is possible to effectively utilize the areas that are wasted when downsizing the video tape recorder.

Although the above embodiments have been described with respect to video tape recorders, the invention is not limited thereto, and the present invention can be suitably implemented in a wide range of other technical fields.

Effects As described above, according to the present invention, the positional relationship between the cam and the gear to which driving force is transmitted by the cam is not restricted, and the cam and the gear can be freely arranged. It becomes possible to reliably transmit driving force. Therefore, it becomes possible to downsize video disc recorders and the like.

Further, according to the present invention, the follower 28 of the lever 27
is connected to one end of the link 30 by a pin 60 on the opposite side to the second shaft 29,
The protrusion 39 provided on the base 21 is connected to the link 3
This link 3 is fitted into a longitudinal guide portion 35 extending along the longitudinal direction between the one end and the other end of the
A rack 31 is formed along the longitudinal direction at the other end of the lever 27, so that the excellent effect of freely setting the arrangement of the lever 27, link 30, gear 32, etc. is achieved. . Further, the lever 27 and the link 30 are connected by a pin 60, and the longitudinal guide portion 35 of the link 30
In addition, since the protrusion 39 provided on the base 21 fits in and the link 30 is displaced, the frictional force can be made as small as possible. In addition, the number of parts is small and the structure is simple.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is a cam diagram of the cam gear 24, and FIG. 4 is a basis for determining the shape of the guide slot 35. FIG. 5 is a typical prior art top view. 21...Base, 24...Cam gear, 26...Cam groove, 27...Lever, 28...Follower, 30...
... Link, 31 ... Rack, 32, 34 ... Missing tooth gear, 35 ... Guide slot, 37 ... Link, 39
... protrusion, 41 ... guide shaft, 42 ... guide groove,
S...Cam radius, α...Rotation angle of the cam gear 24.

Claims (1)

[Claims for Utility Model Registration] A rotating body having a base 21 and a cam groove 26 that is rotatably provided on the base 21 around a first shaft 25 and is formed in a substantially spiral shape around the axis of rotation. 24, means 22 and 23 for rotationally driving the rotating body 24, and a lever 27 pivotably supported on the base 21 so as to be angularly displaceable around a second shaft 29, the lever 27
The lever 27 is provided with a follower 28 that fits into the cam groove 26, and has one end pin-coupled by a pin 60 on the opposite side of the second shaft 29 with respect to the follower 28 of the lever 27. It is a longitudinal link 30, and a rack 31 is formed along the longitudinal direction at the other end of the link 30, and a longitudinal guide portion 35 extending along the longitudinal direction is formed between the one end and the other end. The longitudinal guide portion 35 includes a link 30 formed, a protrusion 39 provided on the base 21 and fitted into the longitudinal guide portion 35, and a gear 32 provided on the base 21 and meshed with the rack 31. A driving force transmission device characterized in that the link 30 is guided so that the pitch line of the rack 31 and the pitch circle of the gear 32 are always in contact with each other.