JPH08320035A - Rotational braking device - Google Patents

Abstract

PURPOSE: To provide a rotational braking device which prevents inclination of a rotary shaft by braking the rotary shaft provided with a high inertial rotational body under high speed rotation with a little force and for a short time. CONSTITUTION: A braking strip member 60 is wound around a rotary shaft 90 by one time or more, having fixed one end. Ant energizing means 70 holds the braking strip member 60 in the state of being separated from the rotary shaft 90. A driving means 80 is driven for pulling the other end of the strip member 60 and winding the strip member 60 around the rotary shaft 90 against the energizing means 70. Thus a rotational braking device is composed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optimum rotation braking device for use in a tape recording device such as a video tape recorder (VTR) or a digital audio tape recorder (DAT).

[0002]

2. Description of the Related Art A tape recording device, for example, a video tape recorder is equipped with a cassette shell. The cassette shell has a tape supply reel (supply reel) and a take-up reel (winding reel). Supply reel and take-up reel
Each of them is adapted to be rotated by a rotating shaft of a motor.

For example, the rotation shaft of the take-up reel may stop from high-speed rotation such as fast-forwarding and rewinding of the tape.
In this case, the driving force of the motor of the rotating shaft 1 rotating at high speed shown in FIG. 4 is turned off, and the solenoid plunger 2 is turned on. Thereby, the arm 3 of the brake 3
Since a rotates around the fulcrum 3b against the force of the spring 4, the brake 3 is pressed against the peripheral surface of the rotating shaft 1 by the force W by the force of the plunger 2. Then, the brake 3 decelerates the rotating shaft 1 by frictional force and stops it. The frictional force F = μW (μ; friction coefficient between the rotating shaft 1 and the brake 3; W: force pressed by the plunger) at this time is insufficient for instantaneously stopping the rotating shaft 1 rotating at high speed. Is. Especially, a rotating body with a large inertia,
For example, it takes a considerable amount of time to completely stop the rotation shaft 1 to which the reel fully wound with the tape is attached from the high speed rotation. Therefore, considering the case where the belt-shaped member 5 is applied to the circumferential surface of the rotary shaft 1 by an angle of 90 °, the role of the brake 3 in FIG. 4 is to pull the belt-shaped member 5 by applying a slight force w. Fulfill.

[0004]

However, the brake 3 of FIG. 4 exerts a large force W against the rotary shaft 1 as shown by an arrow P, so that the brake 3 exerts a large force against it. In this case, it is possible that the rotary shaft 1 falls in the direction of the arrow P. Further, in the method of pressing the belt-shaped member 5 against the rotary shaft 1 by an angle of 90 ° (a quarter rotation) as shown in FIG. 5, the rotary shaft 1 may still fall. Therefore, for example, a method in which the brakes 3 are arranged on both sides of the rotary shaft 1 and the rotation of the rotary shaft 1 is stopped by the brakes 3 from both sides can be considered, but the structure is complicated and cost reduction and space saving are impossible. Is.

Therefore, the present invention has been made to solve the above problems, and a rotating shaft equipped with a rotating body having a high inertia and rotating at a high speed can be braked with a small force in a short time, so that the rotating shaft can be rotated. It is an object of the present invention to provide a rotation braking device that can prevent the shaft from falling.

[0006]

In order to achieve the above object, in the invention of claim 1, in a rotary braking device for braking a rotary shaft having a load attached, it is possible to wind the rotary shaft more than once. A braking belt-shaped member, one end side of which is fixed, a braking belt-shaped member, a biasing means for holding the braking belt-shaped member in a state of being separated from the rotation shaft, and the other end of the belt-shaped member. And a drive means for pulling the side to wind the braking band around the rotary shaft against the force of the biasing means.

According to the second aspect of the invention, preferably, the braking belt-shaped member is a thin plate having a spring property.
Further, in the invention of claim 3, preferably, the belt-like member for braking is wound around the rotation shaft by an integral number of turns. Further, according to the invention of claim 4, the housing is preferably arranged around the rotating shaft, the inner diameter of the housing is larger than the diameter of the rotating shaft, and is larger than the outer diameter of the belt member for braking when released. Is also small. Further, in the invention of claim 5, preferably, the load of the rotating shaft is a reel for winding the information recording tape.

[0008]

According to the first aspect of the invention, the strip-shaped member is wound around the rotating shaft for one rotation or more and is fixed at one end side thereof. The biasing means holds the strip-shaped member in a state of being separated from the rotation shaft. The drive means pulls the other end of the strip-shaped member to wind the braking strip-shaped member around the rotating shaft against the force of the biasing means. By the operation of the driving means, the belt-shaped member is wound around the rotating shaft for one rotation or more, and the rotating shaft rotating at a high speed is subjected to sudden braking. According to the second aspect of the invention, when the strip-shaped member is a thin plate having a spring property, it is lightweight and the rotation braking device can be made compact. According to the invention of claim 3, when the strip-shaped member is wound around the rotary shaft by an integral number of times, the phenomenon of shaft tilt of the rotary shaft does not occur. According to the invention of claim 4, since the inner diameter of the housing is larger than the diameter of the rotating shaft and smaller than the outer diameter of the strip-shaped member when released,
The belt-shaped member can be securely held on the inner peripheral surface of the housing when the rotating shaft is not braked, and the belt-shaped member does not come into contact with the rotating shaft that is rotating at a high speed when the rotating shaft is not braking.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The examples described below are
Since it is a preferred specific example of the present invention, various technically preferable limitations are attached, but the scope of the present invention is, unless otherwise stated to limit the present invention, in the following description.
It is not limited to these modes.

FIG. 1 shows a tape path system of a video tape recorder to which the rotary braking device 10 of the present invention is applied. In FIG. 1, the video tape path system of the video tape recorder has the following structure. In this video tape path system, the tape cassette shell C can be removably attached. The cassette shell C has a supply reel (supply reel) 22 and a take-up reel (take-up reel) 24. The supply reel 22
It is rotated by the motor M0. The take-up reel 24 is rotated by the motor M1. The cassette shell C can be attached to and detached from the base 11 of the tape traveling system 30. Base 1
A tape running system 30 and a rotary head device (rotary head drum) 40 are arranged on the upper part 1. Tape running system 30
Has a guide roller 32, a fixed guide 34, a fixed guide 36, a capstan shaft 38, a pinch roller 40, a guide roller 42, and the like. The guide roller 32 and the fixed guide 34 are arranged on the tape inflow end side of the rotary head device 40. The fixed guide 36, the capstan shaft 38, the pinch roller 40, and the guide roller 42 are arranged on the tape outflow end side of the rotary head device 40.
The tape T on the supply reel 22 is the guide roller 3
2, through the peripheral surface of the fixed guide 34, the drum of the rotary head device 40, between the fixed guide 36, the capstan shaft 38 and the pinch roller 40, and the guide roller 42 so that the take-up reel 24 can be wound up. It has become. The capstan shaft 38 is rotatable by a capstan motor M. The pinch roller 40 and the capstan shaft 38 can feed the tape T with a predetermined tension by a frictional force by the operation of the capstan motor M. The rotary head device 40 has, for example, a rotary drum and a fixed drum, and a magnetic head of the rotary drum records signals on the tape T by a helical scan method. At the time of reproducing the recorded signal, the reproducing head of the rotary drum reproduces the recorded signal. The take-up reel 24 is shown in FIG.
The rotation braking device 10 is set as shown in FIG. This rotation braking device 10 has a structure as shown in FIG. The rotation braking device 10 includes a thin plate-shaped member 60, a spring 70 that is a biasing unit, and a solenoid plunger 80 that is a driving unit.

The rotary shaft 90 of FIG. 2 is a rotary shaft for mounting and rotating the take-up reel 24 as a load, and is the output shaft of the motor M1 of FIG. Rotating shaft 90
The belt member 60 acting as a brake allows its rotation to be stopped suddenly. This belt-shaped member 60 is
As shown in FIG. 3, it is wound around the rotary shaft 90 at least once more than an integral number of times. When the belt-shaped member 60 is wound at an angle of 450 ° with respect to the rotation axis 90,
The force W for pulling the strip-shaped member 60 cannot rotate the rotary shaft 90 unless it is a considerably large force. This pulling force W is considerably larger than the pulling force w shown in FIG. Considering this conversely, considering that the integer-number band member 60 is wound around the rotating rotary shaft 90 at least one rotation or more, the band-shaped member 60 of FIG. 3 is compared with the band-shaped member 5 of FIG. Therefore, a larger braking force of the rotating shaft 90 can be obtained.

Therefore, the belt-shaped member 60 is, for example, a VT.
It is possible to employ a thin plate (for example, phosphor bronze for springs) of a material that is stronger than R tape and rich in elasticity. More preferably, if necessary, inside the strip-shaped member 60,
By sticking a material having a higher friction coefficient (μ), the belt-shaped member 60 can exert a stable braking force even during long-term use. One end 61 of the belt-shaped member 60 of FIG. 2 is fixed to the fixing portion 77. On the other hand, the other end of the belt-shaped member 60 is fixed to one end 81 of the operation member 83 of the solenoid plunger 80. The other end 82 of the operation member 83 of the solenoid plunger 80 is
It is connected to one end of the spring 70. The other end 77 of the spring 70
a is connected to the fixed portion 77. The spring 70 is a biasing means for holding the belt-shaped member 60 in a state of being separated from the rotating shaft 90 when the rotating shaft 90 is rotating.
On the other hand, the solenoid plunger 80 is designed to wind the braking belt-shaped member 60 around the rotating shaft 90 against the force of the spring 70 when the rotating shaft 90 rotating at high speed is to be braked rapidly.

In FIG. 2, a housing 100 is provided around the rotary shaft 90. This housing 100
Has a circular hollow portion 100a. The inner peripheral surface 100b of the housing 100 is shown by a broken line, and the inner diameter D of the inner peripheral surface 100b of the housing 100 is larger than the diameter d of the rotating shaft 90 and larger than the outer diameter of the belt-shaped member 60 when it is released. It is set small.

Next, the operation of the tape path system of the rotary braking device 10 and the video tape recorder described above will be described. In FIG. 1, the tape T is a tape up reel 24.
The case where the film is wound on the side at a high speed will be described. In the case of this high-speed winding, the rotary shaft 90 is rotated by the arrow R in FIG.
It rotates at high speed in one direction. At the time of this high speed rotation, the spring 70 exerts a tensile force between the fixed portion 77 and the other end portion 82 of the solenoid plunger 80, so that the belt-shaped member 60.
Is in a released state and is in a state of being separated from the periphery of the rotating shaft 90. Moreover, the strip-shaped member 60 is preferably pressed against the inner peripheral surface 100b of the housing 100. In this state, the tensile force of the spring 70 and the strip member 60
The belt-shaped member 60 is moved to the housing 100 by its own spring force.
It is pressed against the inner peripheral surface 100b. Therefore, since the belt-shaped member 60 is stably held on the inner peripheral surface 100b, the belt-shaped member 60 does not come into contact with the rotating shaft 90 that rotates at high speed, and the rotating shaft 90 rotates freely.

Next, a case where the rotating shaft 90 is suddenly braked will be described. In this case, the solenoid plunger 80 is operated to move the operation member 83 of the solenoid plunger in the arrow X direction. As a result, the operation member 83 pulls the belt-shaped member 60 in the arrow X direction against the pulling force of the spring 70 and the force of the belt-shaped member 60 itself. As a result, the belt-shaped member 60 is wound around the rotating shaft 90 rotating at a high speed for one rotation or more to be tightened. The rotating shaft 90 is suddenly braked by the strong frictional force of the belt-shaped member 60 and can stop the take-up reel 24 having high inertia (high inertia) in a short time. In particular, even when the take-up reel 24 is already considerably wound with tape, the rotary shaft 90 can be rapidly braked by the force of the solenoid plunger 80.

In this case, as already explained in FIG.
Since the belt-shaped member 60 is wound around the rotary shaft 90 at least one rotation or more or an integral number of times,
Since the resultant force of the tensile forces acting on the rotary shaft 90 is canceled, the phenomenon of shaft tilt of the rotary shaft 90 does not occur. This makes it possible to apply the braking force of the rotating shaft 90 with high accuracy. Next, in order to release the braking again, the pulling force of the spring 70 is generated by turning off the solenoid plunger 80.
Can be released from the rotating shaft 90. In this case, the band-shaped member 60 is moved to the inner peripheral surface 100b of the housing 100 by the spring force of the band-shaped member 60 and the force of the spring 70.
Is held stable against. As a result, the rotary shaft 90
Since unnecessary braking force does not act on the rotating shaft 90 during rotation of the rotating shaft 90, the rotating shaft 90 can freely rotate. In the example,
The rotary braking device 10 of the present invention is applied to the rotary shaft 90 of the take-up reel 24 in the VTR tape path system. However, the rotation shaft in the tape path system of FIG. 1 is not limited to this, and can be applied to the capstan shaft 38 of the capstan motor M, the rotation shaft 68 of the supply reel 22, and the like.

Not limited to video tape recorders, DAT
High-speed rotation (for example, fast-forwarding, fast-winding, etc.) in tape winding of tape storage devices such as audio, reel rotating system, and rotating system of capstan motor for tape feeding
It is of course possible to apply the rotary braking device of the present invention in order to shorten the time from rewinding, high-speed search, etc.) to stopping.

[0018]

As described above, the rotating shaft equipped with the rotating body of high inertia rotating at a high speed can be braked with a small force in a short time, and the falling of the rotating shaft can be prevented. .

[Brief description of drawings]

FIG. 1 is a diagram showing a tape path system of a video tape recorder having a rotation braking device of the present invention.

2 is a diagram showing a preferred embodiment of the rotary braking device of FIG. 1. FIG.

FIG. 3 is a view showing an example of a belt-shaped member and a rotation shaft of FIG.

FIG. 4 is a diagram showing a conventional braking device.

FIG. 5 is a diagram showing an example of a conventional braking device.

[Explanation of symbols]

24 Take-up reel (winding reel means, load) 60 Belt-shaped member 70 Spring (biasing means) 80 Solenoid plunger (driving means) 90 Rotating shaft 100 Housing 100b Inner peripheral surface of housing M Capstan motor M1 Take-up reel motor

Front page continuation (72) Inventor Tomohiro Ikegami 6-35 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (5)

[Claims] 1. A rotary braking device for braking a rotating shaft to which a load is attached, which is a braking belt-shaped member for winding one or more revolutions around the rotating shaft, one end side of which is fixed. The belt-shaped member, a biasing means for holding the braking belt-shaped member in a state of being separated from the rotating shaft, and a belt-shaped member for braking against the force of the biasing means by pulling the other end of the belt-shaped member. And a drive means for winding the member around the rotary shaft. 2. The rotary braking device according to claim 1, wherein the braking belt-shaped member is a thin plate having a spring property. 3. The rotary braking device according to claim 1, wherein the braking belt-shaped member is wound around the rotary shaft by an integral number of turns. 4. The housing according to claim 1, wherein the housing is arranged around the rotary shaft, and the inner diameter of the housing is larger than the diameter of the rotary shaft and smaller than the outer diameter of the braking belt-shaped member when it is released. Rotational braking device. 5. The rotary braking device according to claim 1, wherein the load on the rotary shaft is a reel for winding the information recording tape.