JPH048501Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a limiter mechanism for a rotating body used in a recording/reproducing device, and is particularly suitable for application to a limiter mechanism for a tape pull-out arm in a cassette-type video tape recorder. It is something.

[Background technology and its problems]

For example, in a cassette type video tape recorder, the drive mechanism for the tape pull-out arm is as shown in FIGS. The rotation of the worm wheel 3 is transmitted to the base 5 of the tape pull-out arm 4 provided concentrically with the wheel 3, and the tape pull-out arm 4 is rotated. In the limiter mechanism, the base 5 is rotatably fitted onto the shaft 7 of the worm wheel 3, and a stopper 8 protruding from the base 5 comes into contact with one spring locking portion 9 provided on the worm wheel 3. A spring 11 is stretched between this spring locking portion 9 and the other spring locking portion 10 provided on the base 5, so that the torque of the worm wheel 3 is transmitted to the base 5 via the spring 11. ing.

During the rotation of the tape pull-out arm 4, the spring 11 does not expand due to the above-mentioned torque.
The configuration is such that no relative angular displacement occurs between the tape pull-out arm 4 and the worm wheel 3.

Thus, if the spring constant of the spring 11 is appropriately selected, and the worm wheel 3 is set so that it continues to rotate for a while and then stops even after the tape pull-out arm 4 contacts the positioning stopper 14, When the tape pull-out arm 4 comes into contact with the positioning stopper 14, the torque increases and the spring 11 stretches, so that the stopper 8 separates from the spring locking part 9.

Therefore, the tape pull-out arm 4 is elastically pressed against the positioning stopper 14, and the tape pull-out arm 4 is accurately positioned.

If the tape 16 wound around the tape guide pin 15 at the tip of the tape pull-out arm 4 receives an overload under this condition, the tape pull-out arm 4 will rotate in the direction away from the positioning stopper 14 against the tension of the spring 11. Since the tape 16 moves, the above-mentioned overload is absorbed and damage to the tape 16 is prevented.

When the overload is removed, the tape pull-out arm 4 returns to the position where it contacts the positioning stopper 14 due to the tension of the spring 11.

Note that the reference numeral 17 in FIG. 1 is a tape cassette, and the reference numeral 18 is a tape reel.
Tape cassette 17 as shown by the dashed line in the figure.
Since the tape pull-out arm 4 is accommodated in the recess 21 of the tape pull-out arm 4, it does not get in the way.

Also, when the tape drawer arm 4 starts rotating,
The tape 16 is guided by the tape guide pin 15 and pulled out from the position shown by the dashed line in the figure to the position shown by the solid line.

By the way, in the above mechanism, the spring constant of the spring 11 is selected in consideration of the product of the tape tension acting on the tape guide pin 15 and the arm length of the tape pull-out arm 4, and this spring constant is Since it tends to become large, the work of hanging the spring 11 when assembling the limiter mechanism becomes an extremely difficult work, partly because the work is done in a narrow space.

Therefore, the spring 1 is placed near the tape guide pin 15.
1 may be tensioned to reduce the spring constant, but in this case, the spring locking portion 9 would need to protrude from the worm wheel 3, which would increase the moment of inertia of the movable part. , or the mechanism becomes complicated.

[Purpose of invention]

The present invention aims to provide a limiter mechanism for a recording/reproducing apparatus that can solve the above-mentioned defects all at once.

[Summary of the idea]

It has a power transmission mechanism configured such that the worm rotated by the drive shaft is biased against the worm wheel in the axial direction of the drive shaft, and the power transmission mechanism moves a rotating body such as a tape drawer arm to its first position. In a limiter mechanism for a recording/reproducing device, the limiter mechanism rotates from a first position to a second position and positions the rotating body by elastically abutting a positioning stopper provided at the second position, The worm, to which rotational force is to be transmitted from the drive shaft, is disposed on the outer periphery of the drive shaft so as to be in sliding contact with the drive shaft and movable in the axial direction of the drive shaft, and the worm is attached to the drive shaft. The worm is rotated by the rotation of the drive shaft, and when the worm rotates the worm wheel, the rotating body is moved against the positioning stopper. When the worm wheel stops rotating due to contact,
A limiter mechanism for a recording/reproducing device configured to move the worm on the drive shaft against the urging means and release the worm by a screw feeding action at a meshing portion between the worm wheel and the worm. be.

Therefore, according to the limiter mechanism of the recording/reproducing apparatus according to the present invention, assembly is extremely easy, and work efficiency is significantly improved.

〔Example〕

An embodiment in which the present invention is applied to a tape pull-out arm drive mechanism of a cassette-type video tape recorder will be described below with reference to FIGS. 3 to 10.

Note that the same parts as those shown in FIGS. 1 and 2 are designated by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 3, the tape pull-out arm 4 has a tape guide pin 15 at its distal end on which a tape 16 can be wound, and its base 5 is fixed to a shaft 7 protruding from the worm wheel 3.

The worm wheel 3 meshes with the worm 2 driven by the motor 1, and can freely rotate in either the forward or reverse direction according to the forward or reverse rotation of the motor 1.

Furthermore, the tape pull-out arm 4, which rotates together with the worm wheel 3, is in the first position accommodated in the recess 21 of the tape cassette 17, as already described with reference to FIG. When the drive button is operated from this position, rotation begins, and rotation continues while pulling out the tape 16.
At the second position shown by the solid line in the figure, it comes into contact with the positioning stopper 14 and stops rotating.

Incidentally, a worm drive body 23 is fixed to the drive shaft 22 of the motor 1, and the worm 2 is driven by the worm drive body 23 via an engaging portion 24, the detailed structure of which is shown in FIG. - shown in FIG.

That is, the worm 2 is provided with a center hole 25, and the drive shaft 22 is inserted through the center hole 25, so that the worm 2 is configured to be slidable on the drive shaft 22.

Further, the worm drive body 23 has a hollow cylindrical shape,
After inserting the drive shaft 22 into the center hole, it is fixed at a predetermined position on the drive shaft 22 using a screw 28.

An engaging piece 29 in the shape of a hollow cylinder divided in half is provided at one end of the worm drive body 23, and a flange-shaped seat 32 for a spring 31, which will be described later, is provided protruding near the other end.

The above-mentioned engagement piece 29 is an engagement piece 30 provided at one end of the worm 2 and having the same shape as this engagement piece 29.
, they are placed opposite to each other so that the drive shaft 22 is sandwiched therebetween.

Further, each end face 3 in the axial direction of the engaging pieces 29, 30
5 and 36 are end faces 3 of the worm 2 and the worm drive body 23 facing each other as shown in FIG.
A hollow cylindrical collar 39 is placed on the drive shaft 22 as shown in the figure so that the worm 2 is not displaced to the right beyond this distance in the figure. It is fitted in and fixed with screws 42.

The spring 31 in a compressed state is fitted between the catch seat 32 and a catch seat 33 of the same shape as the catch seat 32 provided near the base of the engagement piece 30, and the collar 3
9. Press the worm 2 onto the worm.

Next, to describe the function of the engaging portion 24, the torque of the motor 1 is transmitted from the engaging piece 29 of the worm driver 23 fixed to the drive shaft 22 to the engaging piece 30 of the worm 2 disposed opposite thereto. As a result, the worm 2 is rotated at the same speed as the drive shaft 22. Also, the rotation of this worm 2 is caused by the rotation of the worm wheel 3.
and rotates the tape pull-out arm 4.

By the way, if the inclination angle α of the worm 2 is determined as shown in FIG. 4, when the drive shaft 22 rotates in the direction of arrow A in the figure, the worm wheel 3 rotates in the direction of arrow B in the figure.

During this time, the torque transmitted from the worm 2 to the worm wheel 3 is relatively small, so the worm 2 remains pressed against the collar 39 by the spring 31, and no sliding occurs in the axial direction. .

Next, when the tape pull-out arm 4 comes into contact with the positioning stopper 14 and stops rotating, the worm wheel 3 continues to rotate for a while as described above, so the worm 2 moves to the worm wheel 3.
At the meshing part 43 that meshes with the spring 31, the worm 2 rotates while being guided by the teeth 44 of the worm wheel 3 which is in a stationary state, and receives a screw feeding action in the direction of arrow C shown in FIG. It slides on the drive shaft 22 in the direction of arrow C as shown by the dashed line in FIG. 7 while resisting the force of.

Therefore, the tape pull-out arm 4 is elastically pressed against the positioning stopper 14 due to the repulsive force of the spring 31.
The positioning will be extremely accurate.

In this case, the intervals between the end faces 35 and 38 and between the end faces 36 and 37 will naturally be smaller than the initial interval S, but if the intervals are set in advance so that a predetermined interval still remains, the tape 16 Even if an overload is applied to the tape pull-out arm 4 and the tape pull-out arm 4 is displaced in a direction away from the positioning stopper 14, the spring 31 is compressed and can follow this displacement. Damage to the tape 16 is therefore prevented.

When the overload applied to the tape 16 is removed, the tape pull-out arm 4 immediately returns to its normal position in contact with the positioning stopper 14 by the force of the spring 31.

Next, FIG. 9 shows a modification of the above embodiment, in which the engaging portion 24 is provided on the right side of the worm 2 as shown in the figure, and the tape pull-out arm 4
During the rotation, the respective end surfaces 3 of the engaging pieces 29 and 30
5 and 36 are in contact with the end surface 38 of the worm 2 and the end surface 37 of the worm driver 23, respectively.

Further, the spring 45 is placed on the left side of the worm 2,
As in the above embodiment, this spring 45
9 and 30 are not arranged so as to be wound.

By the way, with such a limiter mechanism, the drive shaft 2
2 in the direction of arrow A in the figure, the worm wheel 3 rotates in the direction of arrow B, and the tape pull-out arm 4 moves from the position indicated by the dashed line in the tape cassette 17 to the positioning position indicated by the solid line. It rotates toward the position where it comes into contact with the stopper 14.

In this case, if the spring constant of the spring 45 is appropriately selected, the end surfaces 35 and 38 and the end surfaces 36 and 37 will be in contact while the torque received by the tape pull-out arm 4 is small, that is, while the tape pull-out arm 4 is rotating. tape drawer arm 4.
rotates smoothly.

Further, when the tape pull-out arm 4 comes into contact with the positioning stopper 14 and the torque increases, the spring 45 is compressed and the worm 2 moves to the left in FIG. It will be elastically crimped.

Furthermore, in the above state where the tape pull-out arm 4 is in contact with the positioning stopper 14, if the tape pull-out arm 4 is displaced in the direction away from the positioning stopper 14 due to the overload applied to the tape 16,
The spring 45 is further compressed to absorb this overload, and the overload is removed, and the action of the spring 45 returns the tape pull-out arm 4 to the position in which it abuts the positioning stop 14 again. This point is similar to the case of the previous embodiment.

Next, in order to be able to position the tape drawer arm 4 at both ends of its rotation range, two
A tenth limiter mechanism using two positioning stoppers 52 and 53 will be described below.

In the figure, the worm 2 is loosely fitted to the drive shaft 22.
is provided with locking pieces 30 at both ends, and these locking pieces 3
0 and the locking pieces 29 of the two worm drive bodies 23 fixed to the drive shaft 22 are arranged facing each other so as to sandwich the drive shaft 22, respectively.

Thus, the engaging portion 4 similar to that in the above embodiment
8 and 49 are formed on the left and right sides of the worm 2, respectively, as shown in FIG.
8 and 49 are wound with springs 50 and 51, respectively.

In the mechanism configured in this way, arrow A in the figure
When the drive shaft 22 is rotated in the direction shown in FIG. Drawer arm 4
comes into contact with the positioning stopper 52 and stops.

In this case, the spring 50 on the left side of the figure is compressed, and the spring 51 on the right side is extended, so the tape drawer arm 4
is elastically pressed against the positioning stopper 52.

Next, when the drive shaft 22 rotates in the direction of the arrow A' in the figure, the worm wheel 3 and the tape pull-out arm 4 rotate in the direction of the arrow B' in the figure, and the tape pull-out arm 4 eventually moves to the positioning stopper 53. It stops when it comes into contact with. In this case, the spring 51 is compressed and the spring 50 is extended, so that the tape pull-out arm 4 is elastically pressed against the positioning stopper 53.

Therefore, in this case, the tape pull-out arm 4 can be elastically brought into contact with the positioning stopper 52 or 53 at both ends of its rotation range, and can be accurately positioned.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various effective modifications can be made based on the technical idea of the present invention.

For example, since the springs 31, 45, 50, and 51 are employed as one of the biasing means, they can naturally be replaced with rubber or other elastic bodies.

Further, the cross-sectional shape of the engaging pieces 29 and 30 is not necessarily limited to the shape obtained by dividing a hollow cylinder in half. That is, the worm driving body 23 and the worm 2
Since it is sufficient that torque can be transmitted between
8,49 may be configured.

In addition, for example, the worm 2 and the drive shaft 22 are connected so that the worm 2 is slidable with respect to the drive shaft 22.
It is also possible to spline-couple them so that the torque of the drive shaft 22 is directly transmitted to the worm 2, and omit the worm drive body 23.

[Application example]

The limiter mechanism of the present invention is not limited to the rotation mechanism of the tape pull-out arm 4, but can be applied to a wide range of rotation mechanisms used in recording and reproducing devices.

[Effect of idea]

As described above, in the present invention, since the rotating body such as the tape pull-out arm can be elastically pressed against the positioning stopper, the rotating body can be accurately positioned.

Further, the worm is configured to be slidably fitted to the drive shaft and driven by the drive shaft, and a biasing means is interposed between the worm and the drive shaft to form a limiter mechanism. Because of the structure, the limiter mechanism can be preassembled outside the recording/reproducing apparatus and then incorporated into the recording/reproducing apparatus as a single component, making assembly extremely easy and significantly improving work efficiency. I can do it.

[Brief explanation of the drawing]

Figures 1A to 2 show the limiter mechanism of the tape drawer arm, which is the basic structure in devising the present invention, Figures 1A and 1B are plan views of the above mechanism, and Figure 2 is the same as above. A perspective view of the mechanism, FIGS. 3 to 10 show an embodiment in which the present invention is applied to a tape pull-out arm drive mechanism of a cassette-type video tape recorder, and FIG. 3 is a perspective view of the same mechanism, and FIG.
5 is a sectional view taken along the line V-V in FIG. 4, FIG. 6 is a sectional view taken along the - line in FIG. 4, and FIG. 7 is a longitudinal sectional view of FIG. 4. FIG. 8 is an exploded perspective view of essential parts of the same mechanism, FIG. 9 is a plan view showing a modification of the above embodiment, and FIG. 10 is a plan view of a tape drawer arm mechanism equipped with a pair of limiter mechanisms. In addition, in the symbols used in the drawings, 2... Worm, 3... Worm wheel, 4... Tape drawer arm, 7... (of the worm wheel)
Shaft, 14... Positioning stopper, 22... Drive shaft, 31... Spring, 39... Collar, 43... Engaging portion, 45... Spring, 50... Spring, 51... Spring, 52... Positioning 53 is a positioning stopper.

Claims (1)

[Claims for Utility Model Registration] It has a power transmission mechanism configured such that a worm rotated by a drive shaft is urged against a worm wheel in the axial direction of the drive shaft, and includes a rotating body such as a tape drawer arm. is rotated from a first position to a second position by this power transmission mechanism, and this rotating body is positioned by elastically abutting against a positioning stopper provided at the second position. In a limiter mechanism of a recording/reproducing device, the worm to which rotational force is to be transmitted from the drive shaft is arranged on the outer periphery of the drive shaft so as to be slidable on the drive shaft and movable in the axial direction of the drive shaft. In addition, a biasing means for biasing the worm to move in the axial direction on the drive shaft is provided, and when the worm is rotated by the rotation of the drive shaft and the worm wheel is rotationally driven by the worm, the worm wheel is rotated by the worm. When the rotating body comes into contact with the positioning stopper and the rotation of the worm wheel is stopped, the worm is moved against the urging means by a screw feeding action at the meshing portion between the worm wheel and the worm. A limiter mechanism for a recording/reproducing device configured to move on the drive shaft and release the limiter.