JP2000182297A - Magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording and reproducing device which does not use a complicated tape tension mechanism, but has a tape tension control mechanism which is suitable for a small-sized portable appliance, saves the space, and has a small number of parts. SOLUTION: A tension control guide 5a is arranged between a payoff reel 3 and a guide drum 10 in a tape cassette 2 and guides a magnetic tape 1. The guide 5a varies a coefficient of friction with the winding angle of the magnetic tape 1 which travels along this guide 5a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape tension control device of a magnetic recording / reproducing device used for video equipment such as a video camera and a VTR.

[0002]

2. Description of the Related Art Video equipment such as video cameras and VTRs that use a magnetic tape are often used. In these video devices, in particular, in a helical VTR adopting an oblique scanning method, a contact portion between a guide drum and a magnetic tape is long, and the magnetic tape runs in contact with many guide posts and fixed heads. Therefore, it is necessary to control the tape tension so that the running magnetic tape does not slack. Further, in this type of magnetic recording / reproducing apparatus, there is a problem that the tape tension varies depending on the reel diameter, and in order to solve this, for example, a tape tension control mechanism disclosed in Japanese Utility Model Publication No. 1-15066 is used. I have. Hereinafter, the specific control mechanism will be described with reference to FIG.

FIG. 7 is an explanatory view showing an example of a conventional tape tension control mechanism. In this tape tension control mechanism 20, a magnetic tape 21 (hereinafter referred to as a tape 21) is wound around a reel 22 and is It is rotatable on the disk 23. Further, the tape 21 is pulled out from the reel 22 and guided by the tape guide 24,
Further, the vehicle travels along a predetermined traveling path while being in contact with the tension pole 26 implanted at the tip of the tension arm 25.

[0004] The tension arm 25 has a support shaft 27.
, And is supported by a spring 28 so as to be rotatable counterclockwise, and one end of a brake band 29 is connected to the tension arm 25.
The other end of 9 is fixed to the chassis. A friction member 30 is attached to the brake band 29,
The friction member 30 is in contact with the peripheral surface of the reel disk 23. Then, as is well known, when the tension of the running tape 21 exceeds the set value, the tension pole 26 attached to the tape 21 is pushed and the tension arm 25 is moved to the support shaft 2.
7 rotates clockwise against the urging force of the spring 28, thereby loosening the brake band 29 and damping the reel disc 23, thereby reducing the tension of the tape 21 so as to approach the set value. When the tension of the tape 21 falls below the set value, the tension arm 25 is urged by the spring 28 to rotate in the opposite direction to the above, and the brake band 29
The reel disk 23 is braked and the tape 2
The tension of the tape 21 is controlled by increasing the tension of No. 1 so as to approach the set value.

In other words, the tension pole 26 is always arranged at a position where the rotational force given by the spring 28 and the tape tension are kept in an equilibrium state. It is possible to suppress the slack of the tape 21 and the sudden change of the tension at the time of stop.

[0006]

According to the above-described conventional tape tension control mechanism, since the number of components is large and a movable range is required to some extent, the size and weight of a portable device such as a video camera can be reduced. There were limitations. Therefore, the emergence of a tape tension control mechanism which is suitable for small portable equipment and which has a small number of parts and a small space has been awaited.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points. As a first invention, a magnetic tape disposed between a supply reel 3 in a tape cassette 2 and a guide drum 10 is provided. A tension control guide 5a for guiding the magnetic tape 1 that changes the coefficient of friction according to the winding angle of the magnetic tape 1 running along the guide; According to the present invention, a tension control guide 5b that is disposed between the take-up reel 4 and the guide drum 10 in the tape cassette 2 and guides the magnetic tape 1 is provided.
As a third invention, a magnetic recording / reproducing apparatus configured to change a friction coefficient according to a winding angle of the magnetic tape 1 running along the guide is provided by using the guides 5a and 5b as a third invention.
The magnetic recording / reproducing apparatus provided in the tape cassette 2 is provided.

[0008]

FIG. 1 is a schematic plan view of a first embodiment of a magnetic recording / reproducing apparatus according to the present invention, and FIG. 2 is an explanatory view showing a relationship between a supply-side reel winding diameter and a tape reel. 3 is
FIG. 4 is an explanatory diagram showing a tape winding angle around the tension control guide, FIG. 4 is an explanatory diagram showing a relationship between the winding angle around the tension control guide and the outlet side tape tension, and FIG. FIG. 6 is a schematic plan view of a second embodiment of the apparatus, and FIG. 6 is a plan view showing the relationship between the tape winding angle and the surface roughness of the outlet-side tension control guide. Less than,
A first embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a magnetic tape.
Reference numeral 2 denotes a tape cassette for storing the magnetic tape 1, and includes a supply reel 3 and a take-up reel 4 in which the magnetic tape 1 is wound. Reference numeral 5a denotes a tension control guide which is a main part of the present invention, and is disposed between the supply reel 3 in the tape cassette 2 and a rotating drum 10 described later. Reference numeral 5b denotes a tension control guide which is a main part of the present invention, and is disposed between the take-up reel 4 in the tape cassette 2 and a rotating drum 10 described later. 6a, 6b
Is a tape guide roller for pulling out and storing the magnetic tape 1 from the tape cassette 2, and 7a and 7b are
This is an inclined post for correcting the twist of the tape guide roller, and moves integrally with the tape guide rollers 6a and 6b.

Reference numeral 8 denotes a pinch roller. Reference numeral 9 denotes a capstan that rotates the magnetic tape 1 while sandwiching the magnetic tape 1 between the pinch roller 8 and causes the magnetic tape 1 to run.
Reference numeral 10 denotes a rotating drum having a head (not shown) for recording and reproducing information on and from the magnetic tape 1. The operation of the magnetic recording / reproducing apparatus configured as described above will be described below.

After the tape cassette 2 is mounted in the magnetic recording / reproducing apparatus, the tape guide rollers 6a, 6b and the inclined posts 7a, 7b are moved from the inside of the tape cassette 2 to the positions shown in FIG. Of course, the tension control guides 5a and 5b, the pinch roller 8, the capstan 9 and the like, which are obstacles to this movement, are out of the movement path. Thereafter, the members such as the tension control guides 5a and 5b are brought to the position shown in FIG. 1 by means (not shown), and the magnetic tape 1 travels on a predetermined traveling path to perform recording and reproduction.

In the present invention, as in the case of a normal VTR, the tape tension on the rotating drum 10 needs to be constant. Therefore, a brake torque Q is applied to the supply reel 3 in order to apply the tape tension. It is. By the way, since the brake torque is usually constant in the case of the mechanical type, for example, when the magnetic tape 1 runs and the reel diameter r on the supply side decreases during recording and reproduction, the tape tension T increases. This relationship is T = Q / r, and the state is as shown in FIG.

On the other hand, as shown in FIG. 3, in the entrance side tension control guide 5a disposed between the supply reel 3 and the rotating drum 10, the tension control guide 5a is provided.
The tape tension between a and the magnetic tape 1 has an increase in the tape tension before and after the tape running due to friction when the tape runs, which is expressed by the following equation.
The result is as shown in FIG. T2 = T1 × eμθ (where, T1: entry side tape tension, T2: exit side tape tension, μ: coefficient of friction, θ: winding angle)

As described above, the tape tension T, the entrance-side tape tension T1, and the exit-side tape tension T2 are:
In the first invention, the tension control guide 5a whose winding angle changes according to the winding diameter of the supply reel 3 in FIG. The tension control guide 5a is disposed between the reel 3 and the rotating drum 10.
It is a feature of the present invention that the friction coefficient increases as the winding angle increases. That is, the supply reel 3
, The change in the tape tension caused by the winding diameter is offset by the change in the winding angle θ and the friction coefficient μ in the above equation.

According to the structure of the present invention, at the beginning of the tape winding of the cassette, the diameter of the reel on the supply side is large and the tape tension T1 on the entrance side is low, but the winding angle of the tension control guide 5a is large. Increases, and the outlet-side tape tension T2 increases. At the end of the tape winding of the cassette, the supply-side reel winding diameter is small and the entrance-side tape tension T1 is high, but the winding angle of the tension control guide 5a is small, so that the tension is reduced and the exit-side tape tension T2 is It is kept low. Therefore, the fluctuation of the tape tension can be kept constant.

When the running of the tape is reversed, the tension control guide 5b is connected to the tape cassette 2 as shown in FIG.
A similar effect can be obtained by arranging the take-up reel 4 and the rotary drum 10 outside.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a schematic plan view of a second embodiment of the magnetic recording / reproducing apparatus according to the present invention. In the first embodiment, a tension control guide 5 which is an essential part of the present invention is shown.
a and 5b are arranged outside the tape cassette 2. However, the closer to the reel, the greater the change in the winding angle and the higher the effect of stabilizing the tape tension. Therefore, the tension control guides 5a and 5b are It is arranged near the tape outlet of the cassette. With this configuration, the same effects as in the first embodiment can be obtained.

Next, a specific embodiment for changing the coefficient of friction on the tension control guides 5a and 5b according to the winding angle will be described with reference to FIG. (A) is a state diagram using a tension control guide that changes the surface roughness according to the winding angle and obtains a desired coefficient of friction.
Is a state diagram using a tension control guide that coated a high friction coefficient material such as rubber on the surface of the tension control guide, and changed the coating thickness according to the winding angle to obtain a desired friction coefficient. (C) is a state diagram using a tension control guide that changes the tape contact area according to the winding angle to obtain a desired friction coefficient.

[0019]

As described above in detail, according to the magnetic recording / reproducing apparatus of the present invention, the number of components is greatly reduced and the size and weight of the apparatus are reduced without using a conventional complicated tape tension controller. It can be easily achieved.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a first embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a supply-side reel winding diameter and a tape reel.

FIG. 3 is an explanatory diagram illustrating a tape winding angle around a tension control guide.

FIG. 4 is an explanatory diagram showing a relationship between a winding angle around a tension control guide and an outlet-side tape tension.

FIG. 5 is a schematic plan view of a second embodiment of the magnetic recording / reproducing apparatus according to the present invention.

FIG. 6 is a plan view illustrating a relationship between a tape winding angle and a surface roughness of an outlet-side tension control guide.

FIG. 7 is an explanatory diagram showing an example of a conventional tape tension control mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic tape 2 Tape cassette 3 Supply reel 4 Take-up reel 5a, 5b Tension control guide 6a, 6b Tape guide roller 7a, 7b Inclined post 8 Pinch roller 9 Capstan 10 Rotary drum

Claims (3)

[Claims] 1. A tension control guide disposed between a supply reel and a guide drum in a tape cassette for guiding a magnetic tape, wherein the tension control guide is provided at a winding angle of the magnetic tape running along the guide. A magnetic recording / reproducing apparatus characterized in that a friction coefficient is changed in accordance with the magnetic recording / reproducing apparatus. 2. A tension control guide which is disposed between a take-up reel and a guide drum in a tape cassette and guides a magnetic tape, wherein the guide comprises a winding angle of the magnetic tape running along the guide. A magnetic recording / reproducing apparatus characterized in that the friction coefficient is changed according to the following. 3. A magnetic recording / reproducing apparatus according to claim 1, wherein said guide is disposed in a tape cassette.