JPH0276146A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To suppress the fluctuation of braking force to occur at braking time by composing the title device so that the friction coefficient of a brake shoe at a side where the cross angle between a radius and a brake arm at the brake point of a reel base becomes an actuate angle can be smaller than the friction coefficient or the brake shoe at another side where the above-mentioned angle becomes an obtuse angle. CONSTITUTION:In the magnetic recording and reproducing device having a braking brake arm 1, to which a brake shoe 3 is fitted at its tip, a brake shoe 3a at the side where the cross angle between the radius and the brake arm 1 at a brake point (a) of a reel base 2 becomes an obtuse angle alpha is composed of a felt shaped member having the large friction coefficient. Accompanying this, a brake shoe 3b at the side where the cross angle between the radius and the brake arm 1 at the brake point (a) becomes an acute angle beta is composed of another felt shaped member having the small friction coefficient. As this result, when braking is executed while the reel base rotates from the side of the acute angle beta to the side of the obtuse angle alpha, the biting in of the brake shoe 3 occurs. However, since the friction coefficient of the brake shoe 3b at this part is small, the braking force does not increase excessively. Thus, the fluctuation of the braking force can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus such as a video tape recorder for home and business use, and particularly to a braking mechanism thereof.

2. Description of the Related Art A conventional example is a video tape recorder (hereinafter simply referred to as VTR).
) will be explained based on the drawings. As shown in FIGS. 4 and 5, two reel stands, namely a supply side reel stand 12 (12A) and a take-up side reel stand 12 (12B), are arranged on the motor base 11 of the VTR. A control mechanism 13 is provided to stop the rotation of both reel stands 12A and 12B. Note that usually
In consideration of the inertial force of the tape and reel stand 12, the braking mechanism 13 is provided in addition to the electromagnetic brake of the motor that drives the reel stand 12. By the way, the braking mechanism 13 is connected to both reel stands 12A of the motor base 11.
, 128, respectively, via support bins 14 in the same plane as the reel stands 12A, 12B, and each of these swing arms 15.
A brake shoe 16 for braking the reel stand is attached to one end, and a tension spring 17 is attached to the other end of both swing arms 15 to press the brake shoe 16 against each reel stand. , is arranged on the motor base 11 between the other ends of both swing arms 15, and connects these other ends to one another.
It is composed of an electromagnetic solenoid 18 that is operated for one hour.

Further, the brake shoes 16 are made of felt made of chemical 4I fiber having a large coefficient of friction. In addition, since the electromagnetic solenoid 18 has its operating rod 18a protruding only in one direction, an engagement piece 19 is provided for interlocking the swinging of one swinging arm 15B with the other swinging arm 15A.
A, 193 are provided respectively. Further, as shown in FIG. 6, the swing arm 15 is slightly inclined at a predetermined angle θ with respect to the pressing position of the reel stand 12, that is, the tangent at the braking point a. This is because when the tape stops running, the stopping time of both reel stands is slightly shifted to give an appropriate tension to the tape in the stopped state.

In the above configuration, when the tape runs, the operating rod 18a of the electromagnetic solenoid 18 is projected and the brake shoes 16 of both swing arms 15 are separated from the reel stand 12, as shown in FIG. Also, when the tape stops running,
As shown in FIG. 4, the operating rod 18a is retracted and each swing arm 15 is moved from the reel stand 1 by the urging force of the tension spring 11.
2 side, each brake shoe 16 is biased toward each reel stand 1.
2.

Problems to be Solved by the Invention According to the above-mentioned conventional structure, since the brake shoe uses felt made of chemical 4I fiber with a high coefficient of friction, when the temperature rises, 1. T! As the friction coefficient increases, for example, as shown in Fig. 6, when rotating in the direction of the arrow,
Although the braking force does not increase much, during nine rotations in the eight directions of the arrows, the felt is rolled up and the braking force increases. This occurs because the swing arm 15 is slightly inclined with respect to the tangent line. Therefore, as the temperature rises, the brake torque increases as shown in the curve in Figure 7 and goes out of its optimum range (indicated by diagonal lines), and a large braking force is applied to the reel stand, causing the tape to
There was a problem.

Therefore, it is an object of the present invention to provide a magnetic recording/reproducing device capable of solving the above-mentioned problems.

Means for Solving the Problems In order to solve the above problems, the magnetic recording and reproducing apparatus of the present invention comprises:
A magnetic recording/reproducing device having a brake arm for braking with a brake shoe attached to its tip, and the brake arm being inclined with respect to a tangent at a braking point of a reel stand, The brake shoe on the side where the intersection angle between the radius and the brake arm at the point is an obtuse angle is made of a felt-like member with a large friction coefficient, and the brake on the side where the intersection angle between the radius and the brake arm at the braking point is an acute angle. The shoe is made of a felt-like member with a small coefficient of friction.

Effect In the above configuration, when braking is applied while the reel stand is rotating from an acute angle side to an acute angle side, the brake shoes do not bite, and therefore the felt-like member with a large friction coefficient provides a predetermined braking force. This occurs, and conversely, when braking is applied while the reel stand is rotating from an acute angle side to an obtuse angle side, the brake shoe bites, but since the friction coefficient of the brake shoe in this area is small, 1hlJ
! The lJ force does not increase much, and therefore the braking force does not change much.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

Since the gist of the present invention lies in the configuration of the brake shoe attached to the tip of the brake arm for braking the reel stand, this part will be highlighted and explained, and the other configurations are the same as the conventional configuration. Therefore, its explanation will be omitted.

In FIG. 1, reference numeral 1 denotes a brake arm for braking the reel stand 2, which is slightly inclined at an angle θ with respect to a tangent to the reel stand 2 at a braking point a. The brake shoe 3 attached to the tip of the brake arm 1 is made of two types of materials. That is, the brake shoe 3a (hereinafter referred to as the first shoe) on the side where the intersection angle α between the radius C at the braking point a of the reel stand 2 and the brake arm 1 is an obtuse angle is made of a felt-like member with a large friction coefficient (for example, a chemical Felt made of 11N)
The brake shoe 3b (hereinafter referred to as the second shoe) on the side where the intersection angle β between the radius C and the brake arm 1 at the braking point a is an acute angle is made of a felt-like member with a small friction coefficient (for example, a natural It is composed of felt (made of fibers). In addition, the second
The relationship between the temperature and brake torque at the brake shoe 3b is shown. From this, the change in frictional force with temperature is small, but [JIJ! It can be seen that since the coefficient is small, the frictional force is small.

In the above configuration, when braking is applied while the reel stand 2 is rotating from the first shoe 38 to the second shoe 3b side (indicated by arrow A 1>), since the brake arm 1 is inclined, the first shoe 3b Even if the shoe 3a becomes soft due to temperature rise, it does not bite and generates a predetermined braking force.In addition, the reel stand 2 is rotating from the second shoe 3b to the first shoe 3a side (indicated by arrow B). When braking is applied, the second shoe 3b tries to bite into the outer periphery of the reel stand 2, but the softness of the second shoe 3b does not change even when the temperature rises, so this biting occurs to a large extent. Therefore, the brake torque of the brake shoe 3 as a whole forms a curve as shown in Fig. 3, and is within the optimum range (indicated by diagonal lines) from low to high temperatures. In other words, natural 1liIIIt
It takes advantage of the constancy of m-oscillatory force against temperature changes, which is an advantage of
This is supplemented by chemical fibers that have a coefficient of friction 1.5 times that of natural 41 miscellaneous.

Effects of the Invention According to the configuration of the present invention described above, it is possible to suppress variations in the braking force that occur during braking regardless of which direction the reel stand is rotating, thereby preventing damage to the tape. Can be done.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
The figure is a plan view of the main part of the brake 1jII structure, Figures 2 and 3.
The figure is a graph showing the relationship between the temperature and brake torque in the brake shoe. Figures 4 to 7 show conventional examples. Figures 4 and 5 are a plan view of the 6
The figure is a plan view of the main part, and FIG. 7 is a graph showing the relationship between temperature and brake torque in the brake shoe. 1...brake arm, 2...reel stand, 3...
Brake shoe, 3a...1st shoe, 3b...2nd shoe 〇Representative Yoshi Morimoto Arc part 4 Figure 5 (--N-t ~

Claims (1)

[Claims] 1. A magnetic recording and reproducing device having a braking brake arm having a brake shoe attached to its tip, and the brake arm being inclined with respect to a tangent at the braking point of the reel stand, wherein the reel stand The brake shoe on the side where the intersection angle between the radius and the brake arm at the braking point is an obtuse angle is made of a felt-like member with a large friction coefficient, and the intersection angle between the radius and the brake arm at the braking point is an acute angle. A magnetic recording/reproducing device in which the side brake shoes are made of a felt-like material with a small coefficient of friction.