JPH0668857B2 - Output torque switching mechanism of reel stand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The output torque switching mechanism of the reel stand of the present invention will be described in the following order.

A. Industrial fields of use B. Outline of the invention C. Prior art a. Conventional example 1 (Fig. 5) b. Conventional example 2 (Fig. 6) D. Problems to be solved by the invention E. Problems Means for Solving the Problems F. Action G. Embodiment [Figs. 1 to 4] a. Overall outline [Fig. 1] b. Input gear [Figs. 1 to 3] c. Output disc [Figs. 1 to 3] d. Transmission disk [Figs. 1 to 3] e. Torque switching means [Figs. 1 and 4] f. Reel stand [Figs. 1 to 3] g. Operation [FIGS. 2 to 4] H. Effects of the invention (A. Field of industrial application) The present invention supports a tape reel in an output torque switching mechanism of a reel stand, particularly in a video tape recorder and the like. The output torque of the reel stand that allows you to change the output torque of the reel stand that causes the tape to be wound on the tape reel by rotating the It relates to click switching mechanism.

(B. SUMMARY OF THE INVENTION) The present invention is a reel base output torque switching mechanism for switching the output torque of a reel base supporting a tape reel inside a video tape recorder, an audio tape recorder, etc. A disk, an annular output disk that receives drive torque from the input disk via frictional torque transmission means, and is connected to the output shaft of the reel stand, and the input circle arranged on the lower end side of the reel stand. A transmission disc that has a transmission piece that engages with an engagement hole formed in the plate and the output disc and that is capable of reciprocating in the direction of the rotation axis, is arranged so that their axes coincide with each other, and the transmission circle is formed by the torque switching means. The plate has a first position where the transmission piece engages with the engagement holes of both the output disc and the input disc, and a second position where the transmission piece has disengaged at least one of the engagement holes. To and from When the transmission disc is in the first position, transmission of the drive torque from the input disc to the output disc is performed by the transmission piece of the transmission disc, and in the second position. Is performed via frictional torque transmission means so that the torque output can be switched, and the main part of the output torque switching mechanism can be provided inside the reel stand. The present invention aims to downsize a recorder or an audio tape recorder, and further simplify the structure of the output torque switching mechanism.

(C. Prior Art) A video tape recorder is generally provided with a reel stand. This reel stand supports a tape reel engaged with an engaging shaft portion provided on the reel stand from below, and rotates the tape reel to wind or unwind the tape. .

By the way, the output torque of the reel stand, that is, the force for rotating the tape reel by the output shaft of the reel stand needs to be switched according to the running state of the tape. That is, when the tape is run in a video tape recorder or the like, the tape is pressed against the pinch roller by the capstan, and the running speed is controlled by the pinch roller, and the tape is not pressed against the pinch roller, and the tape is not pressed onto the reel stand There is a state where the tape reel is wound from the other tape reel on the other reel stand. In the former case, if the output of the reel stand is large, there is a fear that a large tension will be applied to the tape, whereas in the latter case, In that case there is no such fear. That is,
In playback mode, double speed playback mode, reverse playback mode, etc., the tape runs under the control of the pinch roller while being pressed against the pinch roller by the capstan, but it is strong against the tape reel that winds the tape in such a case. When the torque is applied, the tape receives a strong tension between the portion pressed against the pinch roller and the tape reel, and may be extended or broken. Therefore, it is necessary to prevent the output torque of the reel stand from exceeding a certain level in such a traveling state. On the other hand, in the rewinding mode, the fast-forward mode, etc., the tape is run by being wound around the tape reel on one reel stand without being pressed against the pinch roller, and the tape is driven even if the output torque of the reel stand is large. There is no fear that a great amount of tension will be added to. Therefore,
In such a running state, it is not necessary to reduce the output torque of the reel stand, and if the output torque is reduced, the tape cannot be rewound or fed at high speed, which is not preferable.

Therefore, the output torque of the reel stand must be switchable according to the running state of the tape.

(A. Conventional Example 1) By the way, FIG. 5 shows an example of a conventional output torque switching mechanism for a reel stand.

The switching mechanism a includes an annular friction plate f made of felt or the like between a direct coupling gear d coupled to an output shaft c of a reel base b and a limiting gear e rotatable with respect to the output shaft c. The drive gear g for direct connection mode and the drive gear h for limiting mode are provided in addition.

Then, the direct connection mode drive gear g is meshed with the direct connection gear d, and a drive torque is applied from the drive gear g, so that the input torque received from the drive gear g is directly transmitted to the output shaft c. It is supposed to do. Further, the limiting drive gear h is meshed with the limiting gear e, and a drive torque is applied to the drive gear h, so that the torque is transmitted from the limiting gear e to the direct coupling gear d via the friction plate f. Transmitted,
Further, the limiting mode is transmitted to the output shaft c. In the limiting mode, a drive torque exceeding the frictional force between the friction plate f and, for example, the direct coupling gear d (the friction plate f is fixed to the limiting gear e side) is input. In that case, slippage occurs between them, and as a result, unlike the direct connection mode, torque above a certain level is not transmitted. Therefore, it is possible to prevent a large tension exceeding the allowable limit from being applied to the tape.

Assuming that the switching mechanism a is slightly modified, the two drive gears g and h are combined into one, and the one drive gear is meshed with the direct coupling gear d or meshed with the limiting gear e. There are things I tried to do.

(B. Conventional example 2) Another example of a conventional output torque switching mechanism for a reel stand is shown in FIG.

The switching mechanism i is provided only with the direct coupling gear d that is connected to the output shaft c, but is not provided with the equivalent to the limiting gear e of the switching mechanism a. The drive gear g for the direct connection mode is engaged in the direct connection mode, the drive gear j for the limiting gear is engaged with the direct connection gear d in the limiting gear, and the drive gear in the limiting mode is used. The driving torque for j is applied through the frictional torque transmitting means k.

In such a switching mechanism i, in the direct coupling mode, the input torque is directly transmitted from the drive gear g to the output shaft c via the direct coupling gear d, and the input torque and the output torque become equal. On the other hand, in the limiting mode, the input torque is transmitted to the limiting mode drive gear j via the frictional torque transmitting means k, and the torque is transmitted from the mobile gear j to the output shaft c via the direct coupling gear d. The frictional torque transmission means j is interposed in the torque transmission path. Therefore, the frictional torque transmission means j defines the upper limit of the output torque, and torque exceeding the upper limit is not output from the output shaft c.

(D. Problems to be Solved by the Invention) According to the switching mechanism a as shown in FIG. 5, the drive gears g and h are meshed with the direct coupling gear d and the limiting gear e, or the gear d, Since it has to be separated from e, its drive gears g and h are
must be provided outside e. Therefore, the drive gears g and h must be provided outside the reel base b, and there is a problem that the area occupied by the switching mechanism a becomes very large. Further, even in a switching device in which one drive gear is engaged with the direct coupling gear d or with the limiting gear e, the driving gear is moved to engage it with the direct coupling gear d. , Limiting gear e
The number of drive gears is one, but the drive gears must be provided outside the reel base b. Therefore, the occupying area of the switching mechanism a becomes large, and the structure of the switching means becomes complicated, so that the apparatus having the switching mechanism such as a video tape recorder becomes large in size.
This leads to higher prices.

Also, in the switching mechanism i as shown in FIG. 6, the drive gears g and j must be provided outside the direct coupling gear d, that is, outside the reel base b, so that the area occupied by the switching mechanism i becomes large. Also, the structure of the switching means becomes complicated, and the problem that the video tape recorder and the like are increased in size and price is inevitable.

Therefore, the present invention has been made to solve such a problem, and an output torque switching mechanism can be provided in the reel stand so that the occupied area of the mechanism is reduced and a video provided with the mechanism is provided. An object of the present invention is to miniaturize a device such as a tape recorder and to simplify the structure of a switching mechanism.

(E. Means for Solving the Problems) In order to achieve the above object, the output torque switching mechanism of the reel stand of the present invention includes an input disk that receives a driving torque and a frictional torque transmission means from the input disk. Engages with an annular output disc that receives driving torque via the output shaft of the reel stand and engagement holes formed in the input disc and the output disc located on the lower end side of the reel stand. And a transmission disc that has a transmission piece that is movable in the direction of the rotation axis and are arranged so that their axes coincide with each other, and the transmission disc is formed by the torque switching means so that the transmission piece has both the output disc and the input disc. The first position for engaging with the engaging hole and the second position for disengaging the transmission piece from at least one of the engaging holes can be reciprocated. .

(F. Action) According to the output torque switching mechanism of the reel stand of the present invention, the torque switching means moves the transmission disc located on the lower end side of the reel stand to the first position, whereby the peripheral edge of the transmission disc. The transmission piece erected at a predetermined position can be brought into a state of being engaged with the engagement holes of both the input disc and the output disc.
Therefore, the drive torque input to the input disc can be directly transmitted to the output disc via the transmission piece. Further, by moving the transmission disc to the second position by the torque switching means, the transmission piece is now disengaged from at least one of the engagement holes of the input disc and the output disc. can do. Therefore, the drive torque is transmitted from the input disc to the output disc not through the transmission piece but through the frictional torque transmission means formed annularly outside the portion where the engagement hole is formed. The output torque can be prevented from exceeding a certain level. Therefore, the output torque can be switched by reciprocating the transmission disc in the axial direction by the torque switching means.

Since the input disc, the output disc and the transmission disc that constitute the output torque switching mechanism are arranged so that their axes coincide with each other, these can be provided in the reel stand. Therefore, it is not necessary to occupy the limited area of the device such as the video tape recorder only for the output torque switching mechanism, and the device can be downsized.

Since the output torque of the reel base can be switched by a simple means of reciprocating the transmission disc in the axial direction, there is an advantage that a complicated mechanism is not required for the torque switching.

(G. Embodiment) Hereinafter, the output torque switching mechanism of the reel mount of the present invention will be described in detail according to an embodiment shown in the accompanying drawings.

1 to 4 show an embodiment in which the present invention is applied as an output torque switching mechanism of a reel stand in a video tape recorder.

(A. Overview of the whole) [FIG. 1] The output torque switching mechanism of the reel base has an input gear 1 that receives a driving torque from the outside, and a friction plate 2 from the input gear 1.
Reel support part 4 of reel stand 3 that receives drive torque via
The output disc 5 connected to the output disc 5 and the output disc 5 arranged on the lower end side of the reel stand 3 from the input gear 1 to the output disc 5 in the direct connection mode described later.
It comprises a transmission disc 6 for transmitting torque to and a torque switching means 7 for reciprocating the transmission disc 6 in its axial direction.

The input gear 1, the output disc 5, and the transmission disc 6 are supported so as to be rotatable about a support shaft 8 that supports the reel base 3 at its upper end. Reference numeral 9 denotes a boss fixed to the chassis 10, and the support shaft 8 is erected on the chassis 10 by the boss 9.

(B. Input gear) [FIGS. 1 to 3] The input gear 1 has a hole 11 formed in the center thereof through which the support shaft 8 is pushed, and is formed on a circle centered on the rotation axis. Four arc-shaped engagement holes 12, 12, 12, 12 are formed at equal intervals. The lower surface of the input gear 1 has engagement holes 12, 12, 12, 12
An annular friction plate 2 made of, for example, felt is fixed to the outside of the portion in which is formed.

(C. Output Disc) [FIGS. 1 to 3] The output disc 5 is rotatably fitted onto the support shaft 8 through a center hole 13, and is supported by a thrust receiver 14 provided on the support shaft 8. It is supported so that its axial position is kept constant.

Reference numeral 15 denotes a tubular portion that is formed so as to project upward from the central portion of the output disc 5, and the tubular portion 15 is rotatably pushed through the central hole 11 of the input gear 1. Is positioned above the output disc 5 via the friction plate 2.

Reference numerals 16, 16, 16 and 16 denote four arc-shaped engagement holes formed on one circle concentric with the center hole 13 of the output disk 5. The shape, size and distance from the rotation axis are input. Engagement hole 12 of gear 1,
It is made the same as those of 12, 12, 12.

(D. Transmission disc) [Figs. 1 to 3] The transmission disc 6 has a hole 17 formed at the center and an annular engagement groove 18 on the peripheral surface. Is rotatably supported by the support shaft 8.

Reference numerals 19 and 19 denote a pair of transmission pieces projectingly formed on the upper surface of the transmission disc 6, which are on a circle centered on the rotation center and have a center hole.
They are formed at positions opposite to each other across 17 and the distance between the transmission pieces 19 and 19 from the rotation axis is the input gear 1.
, And the engaging holes 12, 12, ... And 16, 16, ... Formed in the output disk 5, respectively. The transmission piece 19, 19
Has a cross-sectional shape of the engaging holes 12, 12, ..., 16, 16 ...
Is substantially the same as, but is made smaller than that so that it can be loosely fitted in the engaging holes 12, 12 ,.

The transmission pieces 19, 19 of the transmission disc 6 are always engaged with the engaging hole 1 of the output disc 5.
6 and 16 are engaged with each other, depending on the position of the transmission disc 6 in the axial direction, also engaged with the engagement holes 12, 12 of the input gear 1, that is, the direct connection mode, or the engagement holes. The state in which the engagement with 12, 12 is released, that is, the limiting mode is entered. The position of the transmission disc 6 in the direct connection mode is called the first position, and the position in the limiting mode is called the second position.

(E. Torque switching means) [FIGS. 1 and 4] The torque switching means 7 is a transmission disk drive fork 20 for reciprocating the transmission disk 6 in the axial direction, and a fork drive portion 21 for driving the fork 20. Consists of.

The transmission disc drive fork 20 is formed by forming a pair of arms 23, 23 at both ends of a cylindrical portion 22 that extend substantially at right angles to and parallel to each other, and the cross-sectional shape is formed on the facing surfaces of the tips of the arms 23, 23. Circular engagement protrusions 24, 24 are formed. An engaging piece 25 extending downward in a direction substantially perpendicular to the arms 23 is formed in the substantially central portion of the cylindrical portion 22.

The transmission disc drive fork 20 is rotatably supported on the chassis by a horizontal support shaft 26 that is loosely fitted in the cylindrical portion 22, and the arm 2
The engaging projections 24, 24 of 3, 23 are engaged with the engaging groove 18 of the transmission disc 6.

The fork drive unit 21 includes a driven plate 27 and a drive piece 28 for driving the driven plate 27.
Consists of.

The driven plate 27 is rotatably supported by the vertical support shaft 30 by a support piece 29 provided at one corner of the support shaft 8 side that supports the reel base, and is provided at another corner of the same side surface. A connecting piece 31
Has an engaging hole 32 for engaging with the engaging piece 25 of the transmission disc drive fork 20. The engaging piece 25 of the transmission disc drive fork 20 is engaged with the engaging hole 32.

33 is a coil spring for urging the driven plate 27 to rotate in the counterclockwise direction in FIG.
It is stretched between a support piece 29 of the driven plate 27 and a locking hole 36 of a spring locking piece 35 provided at a diagonal corner. Then, when the driven force is applied to the driven plate 27 to rotate in the counterclockwise direction by the spring 33, the transmission disc drive fork 20 having the engagement piece 25 engaged with the engagement hole 32 is moved to the first position. Figure 2,
It is biased so as to rotate in the clockwise direction in FIG. 3, and as a result, the transmission disc 6 receives a force in the upward moving direction. The transmission pieces 19, 19 of the transmission disc 6 which are constantly engaged with the engagement holes 16, 16 of the output disc 5 are engaged with the engagement holes 12, 12 of the input gear 1 rotated by a driving force from the outside. Is a transmission piece 1
When it reaches the position aligned with 9, 19, it engages with the engagement holes 12, 12.

One end of the drive piece 28 is rotatably supported by the vertical support shaft 30 that rotatably supports the driven plate 27, and is placed on the driven plate 27.

Reference numeral 37 denotes a spring locking pin that is provided on the upper surface of the driving piece 28 so as to project, and is provided at a position closer to the center of the shaft than the tip. 38 is a coil spring whose one end is locked to the spring locking pin 37 of the drive piece 28, and the other end is locked to a spring locking pin 39 which is provided on the upper surface of the driven plate 27 so as to project.
The spring 38 serves to rotate the driven plate 27 in the clockwise direction when the drive piece 28 rotates in the clockwise direction in FIG. Reference numeral 40 denotes a stopper piece formed on the upper surface of the driven plate 27, which is formed on the spring locking pin 39 side of the drive piece 28, and the position of the drive piece 28 that is stopped by the stopper piece 40 is the drive piece 28. It is a rotation limit point on the counterclockwise direction side with respect to the driven piece 27.

Reference numeral 41 is a drive lever, and a hooking piece 42 bent downward is formed at the tip end thereof, and the hooking piece 42 is engaged with the tip end of the edge of the driving piece 28 on the stopper piece 40 side from above. .
The drive lever 41 is connected to a pinch plunger (not shown) via a link (not shown) and reciprocates in the directions shown by the arrows in FIGS. 1 and 4. Specifically, when the video tape recorder expands between the capstan and the pinch roller and the video tape is not pressure-bonded, the video tape recorder moves to the A side and allows the drive piece 28 to rotate in the counterclockwise direction. On the contrary, when the video tape recorder presses the video tape by the capstan and the pinch roller, the video tape recorder moves to the B side to rotate the drive piece 28 in the clockwise direction by a certain amount.

Then, when the drive lever 41 is located closest to the A side, the drive piece 28 is pulled by the spring 38 and the stopper piece 40
It is kept rotated to the position where it engages with.

When the drive lever 41 is moved to the B side by the pinch plunger, the drive piece 28 is rotated in the clockwise direction accordingly. Then, the driven plate 27 receives its driving force via the spring 38 and is rotated in the clockwise direction in FIG. 4 against the tensile force of the spring 33. Then, the transmission disc drive fork 20 having the engagement piece 25 engaged with the engagement hole 32 of the driven plate 27 rotates counterclockwise in FIGS. 2 and 3 to move the transmission disc 6 to the first position. Move from position 1 to position 2. Then, the transmission pieces 19, 19 of the transmission disc 6 are engaged with the engagement holes 16, 1 of the output disc 5 and the input gear 1.
From the state of engaging with 6, 12 and 12 (direct coupling mode), engaging with only the engaging holes 16 of the output disc 5 and the engaging hole of the input gear 1.
12 and 12 are not engaged (limiting mode).

When the drive disc 41 is in the second position and the drive lever 41 moves to the A side, the drive piece 28 is allowed to rotate in the counterclockwise direction in FIG. By this, it is rotated counterclockwise to a position where it engages with the stopper piece 40. Then, the driven plate accordingly
27 is also rotated in the counterclockwise direction by the tensile force of the spring 33, and accordingly, the transmission disk drive fork 20 is about to be rotated in the clockwise direction in FIGS. 2 and 3. As a result, as described above, the transmission disc 6 is pressed upward by the fork 20, and the engagement holes 12, 12 of the input gear 1 that rotate by receiving the driving torque from the outside are the transmission pieces 19, 19 of the transmission disc 6. When the tip of the transmission piece 19, 19 is engaged with the engaging hole 12, 12, when the state of being aligned with 19,
That is, the direct connection mode is set.

(F. Reel base) [FIGS. 1 to 3] The reel base 3 whose output torque can be switched includes the reel support portion 4, the engagement shaft portion 43, and the cap 44.

The reel supporting portion 4 is a combination of a disk-shaped substrate 45, an annular protrusion 46 connected to the peripheral edge of the substrate 45, and a tubular portion 47 protruding upward from the center of the substrate 45. It is integrally formed of resin. An upper surface 48 of the annular protrusion 46 serves as a reel support surface, and an annular groove 49 that opens downward is formed in the lower portion thereof. The outer shape of the cylindrical portion 47 is formed into a regular hexagonal column shape, and a cylindrical cap mounting portion 50 having an outer diameter that is appropriately smaller than the diameter of the circle inscribed in the hexagonal columnar portion is formed at the tip end portion thereof. . Reference numeral 51 denotes a stepped portion formed between the cap mounting portion 50 of the tubular portion 6 and a portion below the cap mounting portion 50. The cap mounting portion 50 of the tubular portion 47 has a through hole 52 penetrating its center.

The upper half of the tubular portion 15 of the output disc 5 is press-fitted into the tubular portion 47 from below. The support shaft 8 pushed through the center holes 17 and 13 of the transmission disc 6 and the output disc 5 is loosely fitted in the through hole 52 of the cap mounting portion 50. And
By the press-fitting, the output disc 5 and the reel supporting portion 4 are coupled to each other, so that the driving torque can be transmitted from the output disc 5 to the reel supporting portion 4. A compression coil spring 53 is inserted between the groove 49 of the reel support portion 4 and the input gear 1. Then, the elastic force of the coil spring 53 causes the friction plate 2 fixed to the lower surface of the input gear 1 to be pressed against the upper surface of the output disc 5 to the output disc 5 of the drive torque input to the input gear 1. The frictional transmission of is made possible.

The engaging shaft portion 43 has a regular hexagonal engaging hole 54 in the central portion, and engaging protrusions 55, 55, 55 for engaging with an engaging hole of a tape reel (not shown) are arranged at equal intervals on the outer peripheral surface. Has been done. The engagement hole 54 is a tubular portion of the reel support portion 4 having a regular hexagonal column shape.
47 has such a size that it is slidably fitted and engaged with it in the rotational direction.

The engagement shaft portion 43 is slidably fitted on the tubular portion 47 of the reel support portion 4.

The cap 44 has a central hole 56 through which the support shaft 8 is inserted, and the lower half portion of the central hole 56 is the cap mounting portion 50 of the reel supporting portion 4.
Has a large diameter so that they can be fitted together. Further, the cap 44 has a flange portion 57 at the lower end portion that abuts on the stepped portion 51 of the reel support portion 4 and the upper surface of the engagement shaft portion 43. The cap mounting portion 50 is fitted into the large diameter portion of the center hole 56 of the cap 44. An E-ring 58 is attached to the upper end of the support shaft 8, and the E-ring 58 allows the cap 44 to be attached.
Is prevented from slipping upward. Further, the flange portion 57 of the cap 44 prevents the engagement shaft portion 43 from coming off to the upper side, and the engagement shaft portion 43 and the substrate of the reel support portion 4 are prevented.
A coil spring 59 is compressed between the upper surface of the coil 45 and the upper surface.

(G. Operation) [FIGS. 2 to 4] In the output torque switching mechanism of the reel stand as described above, the drive lever 41 operates when the tape is not fastened to the capstan by the pinch roller such as fast forward or rewind. The transmission disc 6 is kept at the position closest to the A side, and the transmission disc 6 is kept at the first position by the torque switching means 7 as described above. Therefore, as shown in FIG. 2, the transmission pieces 19, 19 are engaged with the engagement holes 16, 16, 12, 12 of both the output disk 5 and the input gear 1 (one transmission piece 19 and the engagement hole). The engagement with 16 and 12 can be maintained at (not shown in the drawing). In such a state, the torque that the input gear 1 receives from the outside is directly transmitted to the output disk 5 by the transmission pieces 19 and 19, and the transmitted torque is transmitted to the reel support portion 4 and the engagement shaft portion 43. Be transmitted to. Therefore, at this time, the input gear 1
Is a state in which the input torque received from the outside is equal to the output torque output from the engaging shaft portion 43 to the tape reel, that is,
The direct connection mode is set.

Then, when the tape is pressed against the capstan by the pinch roller for reproduction, double speed reproduction, reverse rotation reproduction, etc., the drive lever 41 connected to the pinch plunger via the link is moved in the direction of arrow B shown in FIG. Moved to the side. Then, the drive lever 41 causes the drive piece 28 to rotate in the clockwise direction in FIG. 4, and the rotational force is transmitted to the driven plate 27 via the spring 38, and the driven plate 27 resists the tensile force of the spring 33. It is turned clockwise. As a result, the transmission disc drive fork 20 having the engagement piece 25 engaged with the engagement hole 32 of the driven plate 27 is rotated in the counterclockwise direction in FIGS. 2 and 3, and accordingly. Engagement protrusion of the transmission disk drive fork 20
The transmission disc 6, which is engaged with 24, 24 in the engagement groove 18, is moved downward by the fork 20. Then, as shown in FIG. 3, the transmission pieces 19, 19 of the transmission disc 6 which were engaged with the engagement holes 12, 12 of the input gear 1 slip out of the engagement holes 12, 12, and the transmission pieces 19, 12. The engagement between 19 and the engagement holes 12 and 12 is released. As a result, the drive torque is transmitted from the input gear 1 to the output disc 5 not through the transmission pieces 19 and 19, but through the friction plate 2, and the transmission is frictional. Therefore, even if the driving torque input to the input gear 1 becomes large, the torque transmitted to the output disc 5 can be prevented from exceeding a certain level. That is, when the driving torque input to the input gear 1 is larger than the frictional force between the friction plate 2 and the output disc 5, slippage occurs between the friction plate 2 and the output disc 5, and the torque is attenuated. Be punished. Therefore, it is possible to prevent the tape from being subjected to a large tension exceeding the allowable limit between the portion wound on the tape reel and the portion pressed by the capstan and the pinch roller.

Further, according to the output torque switching mechanism of the reel base shown in the figure, even when the rotation of the reel base 3 is stopped, it is possible to apply the brake torque having the strength corresponding to the running state of the video tape. That is, when fast-forwarding and rewinding, the tape reel is rotating fast, so a strong brake torque must be applied to stop it quickly, whereas normal playback, double-speed playback, reverse playback, etc. At this time, since the tape reel is rotating at a relatively slow speed, the stopped state can be quickly achieved even when the braking torque applied is weak. Therefore, it is necessary to increase the brake torque during fast forward, rewind, etc., and decrease the brake torque during normal reproduction, double speed reproduction, reverse rotation reproduction, and the like. Therefore, in order to switch the brake torque according to the tape running state, a special mechanism has been conventionally required. However, according to the output torque switching mechanism of the reel base shown in the figure, the transmission pieces 19, 19 of the transmission disc 6 are engaged with the engagement holes of both the input gear 1 and the output disc 5 at the time of fast-forwarding, rewinding, etc.
Since it is in the direct connection mode in which the driving torque is directly transmitted from the input gear 1 to the output disc 5 by engaging with 12, 12, 16, and 16, if the input gear 1 is braked, the brake torque is output. It can be directly transmitted to the plate 5.
Therefore, the tape reel rotating at a high speed can be quickly stopped by the strong brake torque. Further, during normal reproduction, double-speed reproduction, reverse rotation reproduction, etc., the torque of the input gear 1 is in a state of being transmitted to the output disc 5 via the friction plate 2, so that when the brake is applied to the input gear 1 as well, the brake torque is reduced. It is transmitted to the output disc 5 via the friction plate 2. Therefore, the brake torque applied to the tape reel can be kept below a certain level, and the tape can be stopped by a small torque suitable for the running speed. As described above, according to the reel base output torque switching mechanism described above, the brake torque of the engagement shaft portion 43 of the reel base can be switched according to the running state of the tape. Therefore, it is not necessary to provide a special device for switching the brake torque.

According to the torque switching means 7 described above, the driving force of the drive lever 41 that moves to switch the state of the switching mechanism is not transmitted to the transmission disc 6 as it is, but is transmitted via the spring 38 or 33. The position of the transmission disk 6 can be smoothly reciprocated between the first position and the second position, and the state can be switched smoothly. That is, when the state shown in FIG. 3 is changed to the state shown in FIG. 2, the transmission pieces 19, 19 move upward to move the input gear 1
When the engaging holes 12, 12 of the input gear 1 that are in contact with the lower surface of the input gear 1 and rotate by receiving a driving torque from the outside are aligned with the transmitting pieces 19, 19, the transmitting pieces 19, 19 are engaged with each other. Aperture 1
The operation of engaging 2 and 12 is performed. Therefore, if the transmission disk 6 is driven by a strong force at that time, the transmission piece
19 and 19 are pressed against the input gear 1 with a strong force, and the transmission piece 1
There is a possibility that the input gear 1 may be broken or the engagement holes 12, 12 of the input gear 1 may be chipped, so that it is necessary to prevent this. However, in the torque switching means 7, when the transmission disc 6 is moved from the second position to the first position, the drive lever 41 is moved in the direction A to rotate the drive piece 28 in the counterclockwise direction. Just allow it. Then,
As described above, the driven plate 27 is rotated counterclockwise by the tensile force of the coil spring 33, and the rotational force is transmitted to the transmission disc 6. Therefore, when the transmission disc 6 moves to the position where the transmission pieces 19, 19 of the transmission disc 6 come into contact with the lower surface of the input gear 1 due to the rotational force, the engagement holes 12, 12, 12, 12 of the input gear 1 happen to occur. Even when the driven plate 27 is in a position not aligned with the transmission pieces 19, 19, when the driven plate 27 is rotated in the counterclockwise direction, the coil spring 33 is pulled from the driven plate 27 so that all the pulling force stored therein is lost. It waits for the engagement holes 12, 12 to be aligned with the transmission pieces 19, 19 in a slightly extended state with a partial pulling force stored therein, instead of discharging. Then, when the engaging holes 12, 12 are aligned with the transmission pieces 19, 19, the coil spring 33 moves the transmission disc 6 to the first position by the remaining tensile force, and the transmission pieces 19, 19 move to the input gear 1's position. The state of being engaged with the engaging holes 12, 12, that is, the direct connection mode is set. Therefore, the movement of the transmission disc 6 from the second position to the first position is extremely smoothly performed, and an unreasonable force is applied to the transmission pieces 19, 19, the engagement holes 12, 12 and the peripheral edges during the movement. There is no

Also, when the transmission disc 6 is moved from the first position to the second position, the driving force of the drive lever 41 is transmitted to the driven plate 27 via the coil spring 38 and further transmitted to the transmission disc 6. . Therefore, when the drive lever 41 moves to the B side and the drive piece 28 rotates in the clockwise direction in FIG. 4, the transmission pieces 19, 19 of the transmission disk 6 happen to be temporarily stopped for some reason. Even if the coil spring 38 is caught in the engaging holes 12 and cannot be removed from the engaging holes 12 and 12, the coil spring 38 does not forcibly contract and the driven plates 27 remain until the transmission pieces 19 and 19 come out of the engaging holes 12 and 12. And the spring locking pins 39 and 37 of the drive piece 28 keep the tensioned state. Then, when the above-mentioned situation disappears, the coil spring 38 contracts to move the transmission disc 6 to the second position, and the transmission pieces 19, 19 come out of the engagement holes 12, 12. Therefore, it is possible to smoothly move the transmission disc 6 from the first position to the second position.

In the above embodiment, the torque is transmitted from the input gear 1 to the output disc 5 in the limiting mode by the friction plate 2 made of felt or the like, that is, by friction transmission. However, the transmission of the torque does not necessarily have to be performed by frictional transmission, but may be performed by frictional transmission using a magnet or the like.

(H. Effect of the Invention) As described above, according to the output torque switching mechanism of the reel stand of the present invention, the transmission disc disposed on the lower end side of the reel stand by the torque switching means is set to the first position. By moving, it is possible to bring the transmission piece, which is erected at a predetermined position on the peripheral edge of the transmission disc, into engagement with the engagement holes of both the input disc and the output disc. Therefore, the drive torque input to the input disc can be directly transmitted to the output disc via the transmission piece. Further, by moving the transmission disc to the second position by the torque switching means,
The transmission piece can be brought into a state of being disengaged from at least one of the engagement holes of the input disc and the output disc. Therefore, the drive torque is transmitted from the input disc to the output disc not through the transmission piece but through the frictional torque transmission means formed annularly outside the portion where the engagement hole is formed. The output torque can be prevented from exceeding a certain level. Therefore, the output torque can be switched by reciprocating the transmission disc in the axial direction by the torque switching means.

Since the input disc, the output disc and the transmission disc that constitute the output torque switching mechanism are arranged so that their axes coincide with each other, these can be provided in the reel stand. Therefore, it is not necessary to occupy the limited area of the device such as the video tape recorder only for the output torque switching mechanism, and the device can be downsized.

Since the output torque of the reel base can be switched by a simple means of reciprocating the transmission disc in the axial direction, there is an advantage that a complicated mechanism is not required for the torque switching.

[Brief description of drawings]

1 to 4 show an example of an embodiment of the output torque switching mechanism of the reel stand according to the present invention. FIG. 1 is an exploded perspective view of the entire mechanism, and FIG. 2 is a transmission disc at the first position. FIG. 3 is a partially cutaway front view showing the state when there is a certain state, FIG. 3 is a partially cutaway front view showing the state when the transmission disc is at the second position, and FIG. 4 is a plan view showing the torque switching means. 5 and 6 are partially cutaway front views showing another conventional example of the output torque switching mechanism of the reel stand. DESCRIPTION OF SYMBOLS 1 ... Input disc, 2 ... Friction torque transmitting means, 3 ... Reel stand, 4,43 ... Output shaft, 5 ... Output disc, 6 ... Transmission disc, 7 ... Torque switching means, 12 ... engaging hole, 16 ... engaging hole, 19 ... transmission piece

Claims (1)

[Claims] 1. An input disc having an engagement hole at a position appropriately separated from a rotation axis and receiving a driving torque from the outside, and a distance from the rotation axis to a rotation axis of the input disc and the engagement hole. The friction holes are formed annularly on the outside of the portion where the engaging holes are formed, which have engaging holes at positions that are equidistant from each other and are arranged so that their axes coincide with the input disc. The output disk connected to the output shaft of the reel stand and receiving the driving torque through the torque transmitting means, the input disk and the output disk have the same axis line, and are reciprocally movable in the axial direction. A transmission disc that is disposed on the lower end side of the transmission disc and that engages with the engagement holes of the output disc and the input disc and is erected at a predetermined position on the peripheral edge; and the transmission disc in the axial direction thereof. And a torque switching means for reciprocating the torque switching means. A first position where the transmission disc engages with the engagement holes of both the output disc and the input disc, and a first position where the transmission disc is disengaged from at least one of the engagement holes. The output torque switching mechanism of the reel stand, which is capable of reciprocating between the two positions.