JPH0652599B2 - Cam mechanism of magnetic recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving mechanism of a tape guide member of a magnetic recording / reproducing apparatus, and particularly to decelerating a driving force from a motor and transmitting the driving force via a cam. Cam mechanism.

[Conventional technology]

In the conventional mechanism, power from a motor is transmitted to a cam gear through a belt pulley and a speed reduction mechanism by a gear to operate a driven arm having a pin that engages with a cam groove, and a pinch roller engaged with the driven arm. The tape guide member was operated. In the case of the cam mechanism, a load is applied to the engagement pin, so that the cam gear receives a force of a moment and a tilting force of the cam gear, and the rigidity of the cam gear and the length of the engagement pin are sufficiently structured. As an example of using the cam mechanism, there is JP-A-61-9863.

[Problems to be solved by the invention]

In the case of the prior art, when it is adopted in a small and thin mechanism corresponding to the recent VTR integrated type mechanism, the cam gear becomes thin,
When the engagement length between the cam groove and the pin becomes shorter and the bearing length becomes shorter, the rigidity of the cam gear itself becomes insufficient, and
Since the backlash increases, the engaging pin is easily disengaged, and when an abnormal load is reached, the engaging pin may disengage, which may cause a serious problem.

It is an object of the present invention to provide a cam mechanism of a magnetic recording / reproducing apparatus which is compatible with a small and thin mechanism without the drawbacks of the conventional technology.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention provides a loading gear with a cam cut off and a structure of a link that is rotatable coaxially and is mounted in parallel.
By projecting the protrusion from the link and positioning it so that it faces the flat surface of the surface opposite to the cam groove of the loading gear, and setting the gap between the cam gear and the protrusion of the link so that they will contact when the cam gear flexes under load. To be achieved.

On the contrary, it is also achieved by projecting the projection from the cam gear and setting it so as to contact the link or the chassis.

[Action]

Since the above-mentioned cam gear and the link are positioned parallel to each other and rotate on the same axis, the distance between the projection from the link and the flat surface of the cam gear is maintained unless the cam gear tilts. When a load is applied to the cam groove of the cam gear by the driven arm, a rotational moment force is applied to the cam gear.Therefore, the cam gear tries to bend, but the deflection caused by contact with the protrusion from the link prevents the driven gear from bending. The pin is prevented from coming off.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a schematic diagram of a tape running system of the magnetic recording / reproducing apparatus according to the present invention.

In the figure, the magnetic tape is pulled out from the supply reel 2 in the cassette 1, wound around the outer periphery of the cylinder 3 by a predetermined angle, and then wound around the take-up reel. 4 is a motor which is a power source of the mechanism, and the force of the motor 4 is via the belt 5 the worm gear 6 and the loading gear 7,
8 is transmitted. These loading gears 7 and 8 include
The tape guide body 9 on the input side and the tape guide body 10 on the output side are connected to each other via articulated links. In the unloading state, the tape guide bodies 9 and 10 are located in the cassette 1 as shown by the broken line in the figure, and when the driving forces from the motor 4 rotate the loading gears 7 and 8 in opposite directions, Each of the articulated links extends in the direction of the arrow along a guide hole (not shown).

FIG. 1 is a plan view of the loading mechanism, and FIG. 2 is a cross-sectional view thereof. In FIG. 1, a bearing 13 is provided at the center position of the loading gear 8, and the bearing 13 is fixed to a link 12 and mutually Links 15 and 16 are rotatably connected. The loading gear 8 is provided with a cam groove 8c,
Further, a pair of stoppers 8a, 8b are provided so as to be spaced apart from each other at a predetermined interval, and the protrusion 12b of the link 12 has these stoppers 8a, 8b.
By making contact with 8b, the range of rotation is restricted. The torsion spring 11 is wound coaxially with the bearing 13,
One end is attached to the loading gear 8 and the other end is hooked on the protrusion 12a of the link 12 to urge the link 12. Pin 1
Numeral 4 is fixed to the link 12 and is provided so as to project at a position of a gap d with a flat surface portion 8d opposite to the cam groove 8c of the loading gear 8. The driven arm 17 is attached so that the pin 17a engages with the cam groove. Link not shown
A tape guide body 10 is engaged with the tip of 16.

FIG. 4 is a rear view of the driven arm 17 shown in the sectional view of FIG. 2 in which the pin 17a is engaged with the cam groove of the loading gear 8 and the fulcrum shaft 19 provided on the chassis 20 is centered. It is rotatably attached. The driven arm 17 operates by engaging a pin 18 of a second driven arm (not shown) which moves the audio control head 21 shown in FIG. 3 to a predetermined position.

FIG. 5 shows a sectional view of the loading mechanism when the operation load of the driven arm 17 becomes large. When the loading gear 8 receives a momentum due to the reaction force F from the driven arm 17,
It tilts by the amount of 13 and bends. However, link 12
Since the loading gear 8 comes into contact with the link pin 14 which is fixed to and protruded by the gap δ, the deflection is prevented there, so that the pin 17a of the driven arm 17 does not come off.

FIG. 6 shows a sectional view of the loading mechanism when the operation load of the driven arm 17 becomes large when the conventional link 12 is not provided with a protrusion. The loading gear 8 is deflected by the reaction force from the driven arm 17, and the pin 17a of the driven arm 17 is disengaged by the amount of deflection δ. Therefore, the pin comes off and becomes inoperable.

FIG. 7 shows an example of the case where the loading gear 8 is provided with a protrusion. In this case, when the loading gear 8 is bent by the reaction force of the driven arm 17, the cam gear protrusion
8e contacts the link 12 to prevent the loading gear 8 from bending and prevent the pin 17a of the driven arm 17 from coming off. If the cam gear protrusion 8e is provided in an appropriate position within the rotation range of the link 12 in the shape of a half ring, the cam gear protrusion 8e can have a function of preventing deflection even if the position of the load is slightly displaced.

Regardless of whether the protrusion is projected from the link or the cam gear, the number of parts is not increased, and the engagement pin can be prevented from coming off the cam groove with almost no increase in cost.

〔The invention's effect〕

According to the present invention, by providing the simple protrusion, it is possible to prevent the pin that engages with the cam groove of the driven arm from coming off. Therefore, it is necessary to make the cam gear thin and to use a material with high rigidity such as die casting. However, since a material such as plastic having a low rigidity itself can be used, there is an effect that the entire set can be made thin and lightweight. Further, there is an effect that a serious defect such as detachment of a pin can be prevented and a reliable and stable operation can be performed.

[Brief description of drawings]

FIG. 1 is a plan view of a loading mechanism according to an embodiment of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is a schematic view of a tape running system, FIG. 4 is a rear view of the mechanism, and FIG. FIG. 6 is a cross-sectional view of the loading mechanism when the cam gear of the invention is flexed, FIG. 6 is a cross-sectional view of the conventional cam gear that is flexed, and the engagement pin is disengaged. It is sectional drawing which shows the case where it was taken out. 8 …… loading gear, 8c …… cam groove, 12 …… link, 14 …… link pin (projection), 17 …… driven arm, 17a …… driven arm pin, 8e …… cam gear projection, 13 …… bearing, 11 ...... Torsion spring.

Claims (2)

[Claims] 1. A cam gear for transmitting power of a motor through a speed reduction mechanism, a link parallel to the cam gear and rotatably biased by a spring coaxially with the cam gear, and a cam groove of the cam gear. In a magnetic recording / reproducing apparatus having a driven arm having a pin and a transmission mechanism which engages with the driven arm and operates a tape guide body, a flat surface having no unevenness is provided on a surface opposite to the cam groove of the cam gear, and the flat surface is provided. When the cam gear bends due to the excessive load of the driven arm and the engaging pin of the driven arm is about to come off, the projection comes out of the link so as to prevent the engaging pin from coming off. Cam mechanism of magnetic recording / reproducing device. 2. A protrusion is provided on a surface of the cam gear opposite to the cam groove, and the protrusion is opposed to the protrusion when the cam gear is bent by an excessive load of the driven arm and the engaging pin of the driven arm is about to be disengaged. The cam mechanism of the magnetic recording / reproducing apparatus according to claim 1, wherein the flat portion is provided on the link or the chassis.