JPH087543Y2 - Cam transmission mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a cam transmission mechanism used when a head chassis or the like in a tape recorder is moved to a predetermined position at a predetermined timing using a motor, In particular, the present invention relates to a cam transmission mechanism capable of accurately stopping a cam plate at a predetermined position without being affected by overrun by the motor.

(Prior Art) Conventionally, when moving a head chassis in a tape recorder according to an operation mode of the tape recorder, a cam transmission mechanism having a cam plate rotated or moved by a motor has been used.

Then, such a cam transmission mechanism changes the position of the cam groove provided on the cam plate by the motor that is rotationally driven according to the operation mode, and moves the position of the cam groove to appropriately move the position of the head chassis or the like. It is designed to be moved.

(Problems to be solved by the invention) In the conventional cam transmission mechanism as described above, the movement of the cam plate is stopped by detecting that the cam groove of the cam plate has reached a predetermined position and stopping the motor. By doing so, the head chassis and the like are stopped at a predetermined position.

However, even if the motor is stopped by detecting that the cam groove has reached a predetermined position, the motor does not immediately stop due to inertia and overruns. Pass by and stop.

Therefore, conventionally, a special motor drive circuit is required to return the cam groove of the cam plate to a predetermined position, and even when the cam plate is returned, the motor slightly overruns, which causes chattering.

Furthermore, since the amount of overrun of the motor as described above varies depending on the rotation period of the motor and the operation of forward rotation, reverse rotation, etc., it is difficult to accurately return the cam groove that has passed the predetermined stop position to the predetermined position. It was

(Means for Solving the Problem) The present invention has been made in view of the above-mentioned circumstances, and a cam transmission mechanism capable of accurately stopping the cam plate at a predetermined position without being affected by the overrun of the motor. The purpose is to provide.

In order to achieve this object, the present invention has a disk-shaped cam having a cam groove for guiding a position regulating pin connected to the movable body so as to move the movable body to a position according to the operation mode. A cam transmission mechanism including a plate, an intermediate gear that transmits the rotational driving force of the motor, and a drive transmission gear that transmits the rotational driving force of the motor to the cam plate via the intermediate gear to rotate the cam plate. The tooth portions of the cam plate are provided in parallel on the outer periphery of the cam plate in the circumferential direction at predetermined intervals, and the tooth portions of the cam plate are provided on the outer periphery of the drive transmission gear over a predetermined angle range. A tooth portion that meshes with a step portion that fits into the recess of the cam plate in a state where the rotation of the drive transmission gear is not hindered is provided in parallel over an angular range where the tooth portion is not provided, and Above the entire circumference of the transmission gear A tooth portion that meshes with the intermediate gear is provided, and when the movable body is guided by the cam groove and reaches a position corresponding to a predetermined operation mode, the concave portion of the cam plate and the step portion of the drive transmission gear are fitted. Provided is a cam transmission mechanism characterized in that the position of the movable body is regulated by stopping the motor so as to match.

(Embodiment) A preferred embodiment of the cam transmission mechanism according to the present invention will be described in detail below with reference to FIGS. 1 to 9.

Note that FIG. 2, FIG. 5, and FIG.
FIG. 6 is a plan view showing a relationship between a cam groove and a position regulating pin in a stop mode and a music selection mode.

In this embodiment, the present invention is applied to a cam transmission mechanism for moving a head chassis in a tape recorder according to an operation mode.

First, in the mechanical chassis 1, the reel 2 having the gear 2a provided on the outer periphery is rotatably arranged by the shaft 3, and similarly, the reel 4 having the gear 4a provided on the outer periphery is also rotatable by the shaft 5. Are arranged on these reels 2,
The motor 4 is appropriately rotated by a motor 6 disposed in the middle. That is, a gear 8 is attached to the output shaft 7 of the motor 6, and the gear 8 meshes with a gear 10 pivotally supported by a shaft 11 at the tip of an arm 9 pivotally supported by the output shaft 7. There is.

The gear 10 selectively meshes with the gears 2a, 4a of the reels 2, 4 by swinging the arm 9 according to the rotation direction of the motor 6.

Therefore, depending on the rotation direction of the motor 6, either one of the reels 2 or 4 is rotated.
Note that FIG. 1 shows the case where the motor 6 is rotationally driven in the counterclockwise direction, and in this case, the reel 2 is rotationally driven.

The mechanical chassis 1 also has a recording / playback head.
A head chassis, which is a movable body in the present embodiment, in which an erasing head 12 and an erasing head 13 are attached via a head holder 14.
15 are arranged, and the head chassis 15 is the first with respect to the mechanical chassis 1 by the cam transmission mechanism according to the present invention.
It is designed to slide vertically in the figure.

In FIG. 1, the head chassis 15 moves forward (moves upward in the drawing) so that the heads 12 and 13 are moved to the compact cassette C.
It shows the state of sliding contact with the magnetic tape stored in.

Reference numeral 17 in the drawing denotes a pinch roller arm, and a pinch roller 18 pivotally supported by a shaft 19 is attached to the tip of the pinch roller arm 17 and its base end is a shaft.
It is pivotally supported by the mechanical chassis 1 by 20. Similarly, reference numeral 21 in the drawing is also a pinch roller arm. A pinch roller 22 is attached to the tip of this pinch roller arm 21 by a shaft 23, and its base end is pivotally supported by the mechanical chassis 1 by a shaft 24. There is.

Each of the pinch rollers 18 and 22 is rotated by the pinch roller arms 17 and 21 in accordance with the movement of the head chassis 15 so that either of the pinch rollers 18 or
22 selectively contacts the capstans 25 and 26 via the magnetic tape, and the rotation of the capstans 25 and 26 stabilizes the running state of the magnetic tape.

On the other hand, a torsion spring 27 is attached to the head chassis 15, one end of the torsion spring 27 is fixed to the head chassis 15, and the other end is a bent portion 28a formed upright at the tip of the rotating arm 28. It is elastically engaged.

The rotating arm 28 is rotatably attached to the mechanical chassis 1 by a shaft 29, and a position regulating pin 30 is planted on the tip side thereof.

The tip of the position regulating pin 30 has a cam plate 32 arranged on the front surface side of the mechanical chassis 1 as shown in FIG.
The cam groove 32a is engaged with the cam groove 32a, and the cam groove 32a is moved by the rotation of the cam plate 32. As a result, the rotating arm 28
Is rotated about a shaft 29, and a head chassis 15 connected to a bent portion 28a at the tip of the rotating arm 28 via a torsion spring 27 is moved vertically in the drawing.

Further, the cam plate 32 is provided with a shaft as shown in FIGS.
The cam plate 32 is axially supported by the mechanical chassis 1 at 33, and the cam plate 32 is meshed with a gear 42 attached to an output shaft 44 of a motor 43 via a drive transmission gear 34 and intermediate gears 36, 38, 40. There is.

Therefore, the rotational driving force of the motor 43 is transmitted to the cam plate 32 via the gears, and the cam plate 32 is appropriately rotated by the motor 43 in a predetermined direction by a predetermined amount.

The intermediate gear 38 is rotatably supported by a shaft 39, and its small-diameter tooth portion 38a is meshed with the intermediate gear 36 rotatably supported by a shaft 37.

The large-diameter tooth portion 38b of the intermediate gear 38 meshes with the small-diameter tooth portion 40a of the intermediate gear 40 pivotally supported by the shaft 41, and the large-diameter tooth portion 40b of the intermediate gear 40 has the large-diameter tooth portion 40b. Output shaft of 44
Meshes with a gear 42 attached to the. Therefore, the rotation of the motor 43 causes the cam plate 32 to rotate at a reduced speed.

On the other hand, in the present embodiment, the cam plate 32 has the annular cam groove 32a formed on the surface thereof as shown in FIG. 4, and the cam groove 32a is formed in the reproduction position restricting portion 32b and the stop position restricting portion 32c. The music selection position restricting portions 32d and 32e are continuously formed.

As a result, the cam plate 32 is rotated to appropriately change the relative position between the cam groove 32a and the position regulating pin 30 as shown in FIG. 2, FIG. 5 or FIG. By moving the position, the head chassis 15 can be moved according to each operation mode such as reproduction, stop, and music selection as described above.

The position of the head chassis 15 is most advanced in the reproduction mode, most retracted in the stop mode, and is an intermediate position between them in the music selection mode, so that the position regulating portions 32a, 32c of the cam groove 32a are arranged. , 32d, 32e, the cam surface of the reproduction position restricting portion 32b is closest to the rotation center of the cam plate 32, and the cam surface of the stop position restricting portion 32c is farthest from the rotation center.

Furthermore, the distance from the rotation center of each cam surface of the music selection position restricting portions 32d and 32e is about the middle of the above restricting portions 32b and 32c.

Here, in the present embodiment, the music selection position restriction unit 32
By providing d and 32e between the reproduction position restricting portion 32b and the stop position restricting portion 32c, respectively, the cam surface of the cam groove 32a can be formed gently, whereby the position restricting pin 30 can be formed in the cam groove 32a. It is designed to be able to move smoothly inside.

Further, as shown in FIGS. 1 and 5 on the outer circumference of the cam plate 32 as described above.
As shown in the figure, there are provided tooth portions 32f and arcuate concave portions 32g dispersedly arranged at predetermined intervals in the circumferential direction.

The tooth 32f and the recess 32g are formed in two layers as shown in FIG. 5, and are located in parallel with each other.

Further, in the present embodiment, tooth portions 34a are provided on the outer periphery of the upper portion of the drive transmission gear 34 in the axial direction, as shown in FIGS.
These tooth portions 34a are tooth portions 3 formed on the outer periphery of the cam plate 32.
It is designed to mesh with 2f.

Further, another tooth portion 34c is formed over the entire circumference of the axially intermediate portion of the drive transmission gear 34. The tooth portion 34c is a tooth portion of the intermediate gear 36 as shown in FIG. It meshes with 36a.

Further, an arcuate step portion 34b is provided on the outer periphery of the lower portion of the drive transmission gear 34 in the axial direction, and the step portion 34b is adapted to be fitted into the recess 32g of the cam plate 32.

Further, the stepped portion 34b is provided at an angular range position where the tooth portion 34a is not provided, and when the tooth portion 34a and the tooth portion 32f of the cam plate 32 are disengaged from each other, the recessed portion 3b is formed.
The positional relationship is such that it fits into 2g.

The plan shape of the stepped portion 34b is the same as that of the drive transmission gear 3
It is formed in an arc shape so as to form a part concentric with 4, and the recess 32g of the cam plate 32 is also formed to have substantially the same planar shape.

Therefore, when the step portion 34b of the drive transmission gear 34 and the concave portion 32g of the cam plate 32 are fitted to each other, the drive transmission gear 34
However, the rotation of the cam plate 32 is restricted.

The state in which the step portion 34b and the recess 32g are fitted to each other continues while the drive transmission gear 34 rotates by approximately 90 °, and during this time, the rotation of the cam plate 32 is restricted by the step portion 34b.

Furthermore, the relationship between the position where the stepped portion 34b and the recess 32g are fitted and the respective positions of the position restricting portions 32b, 32c, 32d, 32e is that the position restricting pin 30 is one of the position restricting portions. The stepped portion 34b is adapted to fit into the concave portion 32g corresponding to each operation mode when it is located in the portion.

Further, in the present embodiment, the motor 43 is located in any position regulating portion corresponding to the operation mode in which the position regulating pin 30 is set by a switch mechanism (not shown) provided on the lower surface of the cam plate 32, And the recess 32g of the cam plate 32
The drive is controlled so that it is stopped when the step portion 34b of the drive transmission gear 34 and the step portion 34b are fitted together.

In the cam transmission mechanism having the above configuration, the motor
The rotational driving force of 43 is transmitted to the gear 42 and each of the intermediate gears 36, 38, 40, and further by the meshing of the tooth portion 36a of the intermediate gear 36 and the tooth portion 34c provided at the axially intermediate portion of the drive transmission gear 34. This is transmitted to the drive transmission gear 34.

By the rotation of the drive transmission gear 34 that accompanies the rotational drive of the motor 43, the tooth portion 34a provided on the axial upper side of the gear 34 and the cam plate 32 at every 1/4 rotation of the gear 34. Meshes with the tooth portion 32f of.

Therefore, the cam plate 32 is 1/4 of the drive transmission gear 34.
Rotation and stop are alternately repeated for each rotation, and the rotation is intermittently driven.

In addition, as described above, the tooth portion 34a of the drive transmission gear 34 has the cam plate 3
When not engaged with the tooth 32f of the second gear, this drive transmission gear
The step portion 34b of 34 is fitted in the concave portion 32g of the cam plate 32, whereby the rotation of the cam plate 32 is surely restricted.

Then, even when the step portion 34b of the drive transmission gear 34 and the recess portion 32g of the cam plate 32 are fitted to each other as described above, the step portion 34b and the recess portion 32g can be fitted relative to each other as described above. Since the step portion 34b is formed in an arc shape and forms a part of a circle concentric with the drive transmission gear 34, the rotation of the drive transmission gear 34 is not hindered.

Therefore, the position regulating pin 30 is provided on one of the position regulating portions 32 of the cam groove 32a corresponding to the set operation mode.
b, 32c, 32d, 32e is reached, and it is detected that the predetermined recess 32g corresponding to the operation mode of the cam plate 32 and the step portion 34b of the drive transmission gear 34 are fitted, and the motor 43 is stopped. The cam plate 32 is regulated by the relative fitting of the concave portion 32g and the stepped portion 34b to be reliably stopped, and even if the motor 43 overruns, as long as the drive transmission gear 34 does not rotate 90 ° or more, this overrun The rotational driving force is not transmitted to the cam plate 32, and the cam plate 32 does not rotate.

Thus, according to the cam transmission mechanism of the present embodiment,
Since the drive transmission gear 34 idles when the motor 43 is stopped, the cam plate 32 can be reliably stopped at a predetermined position without being affected by the overrun of the motor 43, and the cam plate 32 By the relative fitting between the recess 32g and the step portion 34b of the drive transmission carrier 34, the stopped state of the cam plate 32 can be reliably regulated.

Therefore, according to the present embodiment, it is possible to reliably perform the position regulation of the head chassis 15 that is the movable body by using the cam transmission mechanism having the above-described configuration.

(Effect of the Invention) As is apparent from the above description, according to the cam transmission mechanism of the present invention, when the cam plate is stopped, the rotation of the drive transmission gear interferes with the concave portion of the cam plate and the step portion of the drive transmission gear. The cam plate can be reliably stopped at a predetermined position without being affected by the overrun of the motor by fitting the cam plate in a state where the cam plate is not engaged.

Moreover, when the cam plate is stopped, the rotation of the cam plate is restricted by the relative fitting between the recess and the step portion, so that the stopped state of the cam plate at the predetermined position can be made more reliable.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a cam transmission mechanism according to the present invention, FIG. 2 is a plan view showing a positional relationship between a cam groove and a position regulating pin in the reproducing mode, and FIG. 3 is a view showing an embodiment. FIG. 4 is a side view showing a main part, FIG. 4 is a partially cutaway plan view showing a cam plate, and FIG. 5 is a plan view showing a positional relationship between a cam groove and a position regulating pin in a stop mode of this embodiment. Is a plan view showing the positional relationship between the cam groove and the position regulating pin in the music selection mode, FIG. 7 is a partial side view of the cam plate,
FIG. 8 is a plan view showing the drive transmission gear, and FIG. 9 is a side view showing the drive transmission gear. 15 …… Head chassis (movable body), 30 …… Position control pin, 32 …… Cam plate, 32a …… Cam groove, 32f …… Teeth, 32g
...... Concave part, 34 ...... Drive transmission gear, 34a ...... Tooth part, 34b ......
Step, 34c, teeth, 36, 38, 40, intermediate gear, 42, gear, 43, motor.

Claims (1)

[Scope of utility model registration request] 1. A disc-shaped cam plate having a cam groove for guiding a position regulating pin connected to the movable body for moving the movable body to a position according to an operation mode, and a rotational driving force of a motor. And a drive transmission gear for transmitting the rotational driving force of the motor to the cam plate via the intermediate gear to rotate the cam plate. A tooth portion and concave portions dispersed in the circumferential direction at predetermined intervals are provided in parallel on the outer circumference, and a tooth portion that meshes with the tooth portion of the cam plate over a predetermined angle range on the outer circumference of the drive transmission gear, and the tooth portion. A step portion that fits into the concave portion of the cam plate is provided in parallel in a state where the rotation of the drive transmission gear is not obstructed over an angular range where no portion is provided, and the entire circumference of the drive transmission gear is provided. Providing teeth that mesh with the intermediate gear When the driven body is guided by the cam groove and reaches a position corresponding to a predetermined operation mode, the concave portion of the cam plate and the step portion of the drive transmission gear are fitted to each other to stop the motor. A cam transmission mechanism characterized in that the position of the movable body is regulated by doing so.