JP3120612B2 - Power transmission switching mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a power used for switching a driving force at the time of loading / unloading a cassette holder (hereinafter referred to as "cassette loading") in a tape cassette filling apparatus of a video tape recorder (VTR). The present invention relates to a transmission switching mechanism.

[0002]

2. Description of the Related Art For example, in a tape cassette filling device having no drive source for a video tape recorder, cassette loading of a cassette holder for holding a tape cassette is also performed by using a capstan motor or a cam motor. In this case, a power transmission switching mechanism for switching the driving force of the motor after cassette loading is required,
There is a mechanism for switching power by moving an arm having gears and engaging another gear.

[0003]

However, in the power transmission switching mechanism in which the power is switched by moving the arm having the above-mentioned conventional gear and meshing with another gear, the tooth tips of the gears interfere with each other. Or the mechanism may be damaged. As a countermeasure, a limiter mechanism for dividing the arm into two parts and connecting them with a spring or the like is required, and there is a disadvantage that the number of parts increases and the cost increases.

Accordingly, the present invention is to provide a power transmission switching mechanism that can operate without being damaged even if the tooth tips of the gears interfere with each other.

[0005]

SUMMARY OF THE INVENTION A drive gear, a switching arm rotatably supporting a transmission gear and a switching gear meshing with the transmission gear, and a switching gear of the switching arm meshing with and separating from the driving gear. And a switching arm of the switching arm, which rotatably supports the switching gear, is elastically deformable in a direction away from the driving gear.

[0006]

When the tooth of each gear interferes with the tooth of the gear when the gear and the drive gear mesh with each other, the part of the arm which supports the gear of the gear is elastically deformed, and the tooth of each gear is elastically deformed. No excessive load is applied. As a result, when the drive gear rotates, the tooth tips of each gear slip and come into a normal meshing state, and each gear and the entire mechanism are not damaged.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In FIGS. 1 to 3, reference numeral 1 denotes a power transmission switching mechanism, which is used for cassette loading of a tape cassette filling device of a video tape recorder (VTR). The power transmission switching mechanism 1 includes a drive gear 10 rotatably supported on a chassis (not shown) via a shaft 2.
The transmission gear 12 is rotatably supported on the shaft 3 having the central portion 11a swingably supported on the chassis via the shaft 3, and the switching gear 13 meshing with the transmission gear 12 is connected to the front end portion 11b. A switching arm 11 rotatably supported via a support shaft 14, and a switching gear 13 of the switching arm 11.
A slide plate (operating member) 15 that meshes with and detaches from the drive gear 10, a stopper 11 c formed at the base of the switching arm 11, and the support shaft 4 erected on the chassis. Of the switching arm 11
And a tension coil spring (elastic member) 16 that constantly urges the side in a direction in which it contacts one side surface 15a of the slide plate 15.

The drive gear 10 is formed of a synthetic resin, and has a pulley 10b integrally formed on the lower surface thereof. The pulley 10b is connected via a timing belt 9 to a capstan motor as a power drive source (not shown). As a result, the drive gear 10 rotates using the capstan motor as a drive source.

The switching arm 11 is formed by molding a synthetic resin.
U-shaped cutout groove 1 obliquely from the 5 side to the center portion 11a
1d is formed. The tip 11 of the switching arm 11
The slide plate 15 side becomes the engaging portion 11e with the notch groove 11d on the b side as a boundary, and the tip protrudes in an arc shape. As a result, the distal end 11b of the switching arm 11 is elastically deformable toward the engaging portion 11e around the concave portion at the back of the notch groove 11d, and the engaging portion 11e is also formed at the concave portion at the back of the notch groove 11d. , And is elastically deformable toward the tip 11b.

The transmission gear 12 is formed of a synthetic resin, and is rotatably supported by the shaft 3 that rotatably supports the switching arm 11. The transmission gear 12 is connected to a gear (not shown) of a loading mechanism of the tape cassette filling device. The switching gear 13 is also made of a synthetic resin.

The slide plate 15 is formed of a synthetic resin into a substantially rectangular plate shape, and has at least a pair of long groove holes 15b, 15b (only one is shown in the figure) so as to be parallel to one side surface 15a. It is formed. Each slot 15
A support shaft 5 erected on the chassis is loosely fitted in b.
Thus, the slide plate 15 is reciprocally slid in the left and right directions by a driving source such as a cam motor (not shown) at the time of VTR mode transition. A part of one side surface 15a of the slide plate 15 is integrally formed with a quadrangular projection (locking portion) 15c.

According to the power transmission switching mechanism 1 used for cassette loading of the tape cassette filling device of the VTR according to the embodiment, as shown in FIG. 1, the switching arm 11 is engaged in a mode other than the cassette loading mode. The portion 11e is separated from the projection 15c of the slide plate 15,
The switching arm 11 receives a moment in a counterclockwise direction in the figure by a tension coil spring 16. Therefore, the switching gear 13 is completely separated from the driving gear 10, and no driving force is transmitted to the tape cassette filling device.

FIG. 2 shows the state of the power transmission switching mechanism 1 in the cassette loading mode.
The projection 15c of the slide plate 15 is in contact with e. Therefore, the switching arm 11 rotates clockwise in the figure around the shaft 3 against the urging force of the tension coil spring 16, and the switching gear 13 meshes with the drive gear 10. Since the drive gear 10 is directly connected to a capstan motor as a power source via the timing belt 9, its power is transmitted to the switching gear 13, and further transmitted from the switching gear 13 to the transmission gear 12. Since this transmission gear 12 is connected to the gear of the loading mechanism of the tape cassette filling device,
With the power of the transmission gear 12, the cassette holder of the tape cassette filling device is loaded or unloaded.

At the moment when the engaging portion 11e of the switching arm 11 hits the projection 15c of the slide plate 15, the switching gear 13
In some cases, the tooth tips of the tooth portion 13a and the tooth portion 10a of the drive gear 10 may interfere with each other. At this time, as shown in FIG. The tip portion 11b which rotatably supports the switching gear 13 via the support shaft 14 via the notch groove 11d formed at the front end is elastically deformed in the counterclockwise direction in the drawing around the concave portion at the back of the notch groove 11d. As a result, an excessive load applied to the tip 11b is released. For this reason, a load that causes breakage is not applied to each tooth tip of the tooth portion 13a of the switching gear 13 and the tooth portion 10a of the drive gear 10, and if the drive gear 10 continues to rotate, each tooth portion 10a
All of the tooth tips a and 13a mesh with each other at the tooth tip and the tooth bottom, and a normal meshing state as shown in FIG. 2 is obtained.

When each of the gears 10 and 13 is engaged with each other, the stopper 11c of the switching arm 11 comes into contact with a stopper (not shown) on the chassis, and
A suitable backlash of 0,13 is created to prevent bite of the tooth tip. In a mode other than the cassette loading mode (the state shown in FIG. 1), the switching arm 11
Although the engaging portion 11e is in contact with one side surface 15a of the slide plate 15 by the tensile force of the tension coil spring 16, no excessive load is applied, and there is no adverse effect on the slide of the slide plate 15.

As described above, the notch groove 11 is formed in the switching arm 11.
Since the structure is simple enough to form d and the number of parts does not increase, damage to the teeth 10a, 13a of the gears 10, 13 and the entire mechanism 1 can be reliably prevented at low cost.

According to the above-described embodiment, the projection as the locking portion is formed on the slide plate so as to press the engaging portion of the switching arm toward the drive gear. May be formed. In this case, the tension coil spring is provided on the distal end side of the switching arm, and when the base of the switching arm enters the concave portion of the slide plate, the switching gear and the drive gear mesh with the urging force of the tension coil spring. Further, the operation member is not limited to the slide plate, and may be configured by a gear having a cam groove as a locking portion. In this case, the engagement portion of the switching arm is formed in a boss shape so as to fit into the cam groove of the gear. Further, although the power transmission switching mechanism is used for cassette loading of the tape cassette filling device of the VTR, it is needless to say that the power transmission switching mechanism can be applied to other power transmission switching.

[0019]

As described above, according to the power transmission switching mechanism of the present invention, the portion of the switching arm that rotatably supports the switching gear that meshes with and separates from the drive gear is elastically moved in the direction away from the drive gear. Since the switching gear is formed so as to be freely deformable, even when the tooth tips of the gears interfere with each other when the switching gear meshes with the driving gear, the portion of the switching arm that rotatably supports the switching gear is elastically deformed, and No excessive load is applied to the gear tips. As a result, when the drive gear rotates, the tooth tips of the gears slip and come into a normal meshing state, so that damage to each gear and the entire mechanism can be reliably prevented. Further, the switching arm may be formed of an elastically deformable synthetic resin, or a notch groove may be formed between respective portions of the switching arm that rotatably support the transmission gear and the switching gear, so that the switching gear is Since the rotatably supported part is formed so as to be elastically deformable, it is possible to reliably prevent damage to the teeth of each gear and the entire mechanism without increasing the number of parts.

[Brief description of the drawings]

FIG. 1 is a plan view of a power transmission switching mechanism according to an embodiment of the present invention.

FIG. 2 is a plan view of the power transmission switching mechanism.

FIG. 3 is a plan view of the power transmission switching mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power transmission switching mechanism 10 ... Drive gear 11 ... Switching arm 11a ... Central part 11b ... Tip part 11d ... Notch groove 11e ... Engagement part 12 ... Transmission gear 13 ... Switching gear 15 ... Slide plate (operation member) 15c ... Projection (Locking part) 16 ... Tension coil spring (elastic member)

Claims (4)

(57) [Claims] 1. A drive gear, a switching arm rotatably supporting a transmission gear and a switching gear meshing with the transmission gear, and an operating member for engaging the switching gear of the switching arm with the driving gear and detaching the switching gear. A power transmission switching mechanism, wherein a portion of the switching arm, which rotatably supports the switching gear, is formed to be elastically deformable in a direction away from the driving gear. 2. The power transmission switching mechanism according to claim 1, wherein said switching arm is formed by molding a synthetic resin. 3. The power transmission switch according to claim 1, wherein a notch groove is formed between a portion of the switching arm rotatably supporting the transmission gear and a portion rotatably supporting the switching gear. mechanism. 4. A switching gear is rotatably supported at a central portion of the switching arm, and a switching gear is rotatably supported at a distal end thereof. When the engaging portion is provided with an engaging portion which comes into contact with or separates from the engaging portion, the notch groove is formed diagonally at the center of the engaging portion, and the switching arm is engaged with the base of the switching arm. 4. The power transmission switching mechanism according to claim 3, wherein an elastic member is provided for urging the portion in a direction in which the portion comes into contact with the locking portion of the operation member.