JPH07220331A - Magnetic recording / reproducing device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a high-performance magnetic recording / reproducing apparatus that eliminates or reduces natural vibration generated in the magnetic recording / reproducing apparatus and stabilizes the magnetic tape running speed. [Structure] A shaft portion 11c (12c) for engaging a tape reel wound with a magnetic tape, and the shaft portion 11c (1
2c) a rotary disk 11a (1
2a) and a rotating body 11 (12) and a turntable 11a
The rotating disk 11a (12a) is engaged with the convergent portion of (12a).
And a drive motor 17 for rotating the rotating body 11 (1
2) and a dynamic vibration absorbing device (1, 2) for dynamically absorbing the natural vibration generated in the rotating body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a structure of a magnetic recording / reproducing apparatus for reducing speed fluctuation of a magnetic tape.

[0002]

2. Description of the Related Art Conventionally, a magnetic tape running system used in a magnetic recording / reproducing apparatus or the like is run while a magnetic tape is sandwiched between rotating bodies called capstans and pinch rollers. This method, in order to achieve the purpose of the magnetic tape running system of running the magnetic tape at a constant speed,
This is a method with a very simple structure and high performance in that the rotation speed of the capstan should be kept constant. Therefore, at present, most magnetic recording / reproducing apparatuses adopt this method.

However, a magnetic recording / reproducing apparatus using this method inevitably requires members such as a capstan and a pinch roller. Further, a mechanism for holding and releasing the magnetic tape is required. The operation of sandwiching and releasing the magnetic tape is repeated when the magnetic tape is running and when it is stopped.

Further, when performing fast forward and rewind operations of the magnetic tape, the gear arrangement is set so that the tape reel wound with the magnetic tape is rotated at a high speed. Further, during normal running, gears are arranged so as to rotate the tape reel via a slip mechanism. in this way,
The slip mechanism is provided because the tape reel on the take-up side gradually increases the winding diameter of the magnetic tape as the magnetic tape travels, so even if the magnetic tape running speed is constant,
This is because the rotation speed of the tape reel on the take-up side gradually decreases, and this difference between the magnetic tape running speed and the rotation speed of the tape reel is absorbed. Therefore, the magnetic recording / reproducing apparatus having the above structure has a problem that the structure becomes very complicated.

In order to solve such a problem, Japanese Patent Application No. 4-128604 discloses a magnetic recording / reproducing apparatus having a running system capable of directly driving a tape reel and controlling it even when the magnetic tape speed is low. ing. According to the magnetic recording / reproducing apparatus using the method of directly driving the magnetic tape with the tape reel, since the capstan, the pinch roller, etc. are not required, the structure of the magnetic recording / reproducing apparatus can be made very simple.

The structure of this magnetic recording / reproducing apparatus will be briefly described below with reference to FIGS. 26 and 27. First, referring to FIG. 26, while the magnetic tape 220 wound on the supply-side tape reel 216 is being transferred to the winding-side tape reel 215, information (voice, image data, numerical values) is obtained by the magnetic head 221. Record or play (text information, etc.). The transfer of the magnetic tape 220 is performed by engaging the output shaft 217a of the drive motor 217 with the peripheral portion of the rotary disk 211a of the rotary body 211 which is a drive rotary body configured to rotate together with the tape reel 215 on the winding side. It is done by.

Next, referring to FIG. 27, the drive motor 21
7 and the turntable 211a (212a) will be described. The output shaft 217a of the drive motor 217 is connected to the rotary table 2
It contacts rubber 211b provided on the peripheral portion of 11a, transmits the rotational drive force of output shaft 217a by friction, and rotationally drives turntable 211a. Thereby, the rotating body 21
The tape reel 215 on the take-up side is rotationally driven via the shaft portion 211c provided on the No. 1 unit.

However, in this magnetic recording / reproducing apparatus, natural vibration (resonance) may occur during its operation. This natural vibration is caused by the output shaft 217a and the turntable 211.
contact part 218 with rubber 211b provided on the peripheral edge of a
Is defined as the spring constant (based on the rigidity of the rubber 211b), the moment of inertia of the drive motor 217, the rotational body 211
And the resonance based on the moment of inertia of the tape reel 215. Due to the presence of this natural vibration, the control characteristics of the magnetic tape running speed control are deteriorated, and the speed stability is impaired.

Here, as a conventional method for suppressing natural vibration, for example, JP-A-58-58
As disclosed in Japanese Patent Laid-Open No. 196647, there is a tape reel stand device of a tape recorder. According to this tape reel stand device, rubber is used as a cushioning material in order to prevent vibration of the drive system or the like transmitted to the tape reel stand,
It is configured to damp vibrations during the transmission of power for rotating the tape reel.

[0010]

However, when the vibration suppression shown in the above-mentioned Japanese Patent Laid-Open No. 58-196647 is applied to the above-mentioned prior art, an elastic material is used as a cushioning material in order to prevent the vibration of the drive system. Is used to reduce the rigidity of the drive system. Therefore, in the drive system in the prior art, there is a problem that the control performance of the magnetic tape running speed control is deteriorated. That is, since the rigidity of the drive system becomes low, a phase delay occurs when the driving force is transmitted, the control performance of the magnetic tape running speed control deteriorates, and the magnetic tape running speed control cannot be performed well.

Further, the above-mentioned natural vibration causes phase delay when the frequency is in the vicinity of the servo band and affects the servo characteristics, and when the level of the natural vibration becomes large, this natural vibration causes magnetic recording and reproduction. This becomes a factor that hinders the stability of the magnetic tape running speed of the device, and significantly deteriorates the performance of the magnetic recording / reproducing device.

The present invention has been made to solve the above problems, and is a high-performance magnetic recording / reproducing apparatus for eliminating or reducing the natural vibration generated in the magnetic recording / reproducing apparatus to stabilize the magnetic tape running speed. The purpose is to provide.

It is another object of the present invention to provide a high performance magnetic recording / reproducing apparatus for stabilizing the running of the magnetic tape due to vibration from the outside of the magnetic recording / reproducing apparatus.

It is another object of the present invention to provide a high performance simple magnetic recording / reproducing apparatus and an inexpensive magnetic recording / reproducing apparatus.

[0015]

A magnetic recording / reproducing apparatus according to a first aspect of the present invention includes first and second rotating bodies, a driving device, and a dynamic vibration absorbing device. The first and second rotating bodies include a shaft portion for engaging a tape reel around which a magnetic tape is wound, and a turntable provided on one end side of the shaft portion so as to be coaxial with the shaft portion. have.

The drive device engages with the peripheral portion of the rotary disk to rotate at least one of the first and second rotary bodies. The dynamic vibration absorbing device is the first or second
Is engaged with at least one of the first and second rotating bodies in order to dynamically absorb and absorb the natural vibration generated in the rotating body.

A magnetic recording / reproducing apparatus according to a second aspect of the present invention is the magnetic recording / reproducing apparatus according to the first aspect, wherein the dynamic vibration absorbing device is coaxial with the rotary disk. It has a disc provided, and this disc is attached to the rotating disc with a viscoelastic member interposed.

Next, a magnetic recording / reproducing apparatus according to a third aspect of the present invention is the magnetic recording / reproducing apparatus according to the second aspect, wherein the disc is provided inside the rotary disk. Has been.

Next, a magnetic recording / reproducing apparatus according to a fourth aspect of the present invention is the magnetic recording / reproducing apparatus according to the third aspect, wherein the viscoelastic member is a rubber member or a metal spring. And viscous fluid or viscoelastic resin member.

Next, a magnetic recording / reproducing apparatus according to a fifth aspect of the present invention is the magnetic recording / reproducing apparatus according to the first aspect, wherein the dynamic vibration absorbing device is the peripheral edge of the turntable. The portion has a rotating member which is provided so as to be engaged via a viscoelastic member and which rotates in accordance with the rotation of the rotating disk.

Next, a magnetic recording / reproducing apparatus according to a sixth aspect of the present invention is the magnetic recording / reproducing apparatus according to the fifth aspect, wherein the viscoelastic member is a rubber member or a viscoelastic resin. It is a member.

Next, in a magnetic recording / reproducing apparatus according to a seventh aspect of the present invention, which is the magnetic recording / reproducing apparatus according to the fifth aspect, the driving device and the dynamic vibration absorbing device are: The drive device and the rotating member are engaged with the peripheral portion of the turntable of the first or second rotating body by being installed on the same base substrate and moving the substrate.

Next, a magnetic recording / reproducing apparatus according to an eighth aspect of the present invention is the magnetic recording / reproducing apparatus according to the seventh aspect, wherein the base substrate is the first and the second. It is provided rotatably around a fulcrum provided between the rotating bodies.

[0024]

According to the inventions of claims 1 to 8 based on the present invention, at least one of the first and second rotating bodies is engaged with the first or second rotating body, and is generated. A dynamic vibration absorbing device for dynamically absorbing natural vibration is provided.
As a result, the natural vibration generated in the magnetic tape drive system in the magnetic recording / reproducing apparatus is absorbed by the dynamic vibration absorbing device, and the natural vibration in the magnetic tape drive system is significantly reduced. Further, since the dynamic vibration absorbing device can be installed while keeping the rigidity of the driving force transmission system high, it is possible to absorb the vibration without deteriorating the rigidity unlike the conventional vibration suppressing means, and to control the running of the magnetic tape. Can be realized with high performance.

As a result, fluctuations in the magnetic tape running speed caused by natural vibration are reduced, and the magnetic tape running speed is stabilized. Further, since the resonance peak level of the natural vibration in the control characteristic is reduced, the phase delay amount is reduced, the control characteristic is improved, and as a result, the magnetic tape running speed is stabilized.

According to the invention described in claims 2 to 4 based on the present invention, the dynamic vibration absorbing device has a disk provided concentrically with the rotary disk, and the disk is viscoelastic to the rotary disk. It is attached with a member interposed. As described above, the dynamic vibration absorbing device can be realized by mounting the inertial body made of a disk and the disk on the rotating disk with the viscoelastic member including the elastic element and the damping element interposed.

According to the invention described in claim 3 based on the present invention, the disc is provided inside the turntable. As a result, it is possible to reduce the size of the magnetic recording / reproducing device.

Next, according to the invention of claim 4 based on this invention, a rubber member or a metal spring and a viscous fluid or a viscoelastic resin member are used as the viscoelastic member. This makes it possible to realize a viscoelastic member including an elastic element and a damping element.

Next, according to the invention described in claims 5 to 8, the dynamic vibration absorbing device is provided so as to be engaged with the peripheral portion of the rotary disk with a viscoelastic member interposed therebetween. A rotating member that rotates following the rotation of the turntable is used.

As a result, the rotary member rotates following the rotation of the rotary disk, but at this time, the rotary member rotates in the direction opposite to the rotation of the rotary disk. Therefore, when rotational vibration is applied to the magnetic recording / reproducing apparatus from the outside, the rotational moment due to the rotational vibration generated on the rotating disk and the rotational moment due to the rotational vibration generated on the rotating member act in opposite directions. Therefore, the respective rotation moments cancel each other out, and it is possible to suppress the amount of change in the magnetic recording tape running speed due to the rotational vibration from the outside. As a result, the magnetic tape running speed can be further stabilized.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described below with reference to the drawings. The structure of the magnetic recording / reproducing apparatus in the first embodiment has the same structure of the tape reel, the magnetic head, and the magnetic tape shown in the magnetic recording / reproducing apparatus in the prior art described in FIG.
The description here is omitted, and only the configuration around the rotating body 11 (12), which is a characteristic part of the present embodiment, will be referred to. FIG. 1 shows a rotor 1 of a magnetic recording / reproducing apparatus according to this embodiment.
It is a longitudinal cross-sectional view showing the structure of 1 (12). Rotating body 11
(12) has a turntable 11a (12a) and a shaft portion 11c (12c) as in the conventional case. Drive motor 17
Are pressed against the rotating body 11 (12). The driving force of the drive motor 17 is applied from the output shaft 17a to the rotary disk 11a (12
It is transmitted by frictional force to the rubber 11b (12b) provided on the peripheral portion of a) and is decelerated to drive the tape reel on the winding side to run the magnetic tape.

The rigidity of the contact portion 18 between the output shaft 17a and the rubber 11b (12b) (based on the rigidity of the rubber 11b (12b)) is taken as the spring constant, and the equivalent mass of the drive motor 17 and the equivalent of the rotating body 11 (12). A natural vibration having a natural angular frequency of ω _n occurs in a vibration system (hereinafter, referred to as a main vibration system) constituted by an equivalent mass based on the mass (including the moment of inertia of the magnetic tape 20) (hereinafter, This is called the main vibration). This natural angular frequency is the natural angular frequency in the magnetic recording / reproducing apparatus.

Here, the equivalent mass is an equivalent mass of the moment of inertia when a force is applied to an object having the moment of inertia (J) at a radius R, and (J / It is represented by R ² ). In this embodiment, the equivalent mass of the drive motor 17 is the moment of inertia of the rotor of the drive motor 17 divided by the square of the radius of the output shaft 17a. The equivalent mass of the rotating body 11 (12) is
The sum of the moments of inertia of both (12) and the magnetic tape wound on the tape reel 15 (16) is calculated by the rubber 11b (12
It is divided by the square of the radius from the center of rotation in b).
The natural vibration constituted by the equivalent mass represented by the harmonic mean of these two equivalent masses and the spring constant is the main vibration.

In order to reduce the level of the main vibration of the natural angular frequency (ω _n ), the vibration damping effect (dynamic vibration absorbing effect) of the dynamic vibration absorbing device is applied, which is constructed as follows.

With respect to the rotating body 11 (12), a spring system constituted by the inertia moment disk 1 which is an inertia body having an inertia moment and the rubber 2, that is, the dynamic vibration absorbing device is also a vibration system, so natural vibration is caused. However, the natural angular frequency (designated as ω ₂ ) and the viscous damping coefficient (designated as c) are set for the natural angular frequency of the main vibration based on the following method. Therefore, the main vibration is suppressed and the vibration level is reduced.

FIG. 3 shows a model of the above system. The linear motion system is modeled and expressed from the correspondence between the rotary system and the linear motion system, but no inconvenience occurs. m ₁ is the equivalent mass of the main vibration system composed of the tape reel 15 (16) (including the wound magnetic tape) and the rotating body 11 (12), m ₂ is the equivalent mass of the moment of inertia disk 1, k ₁ is a drive motor 17 and a rotating body 11
Power transmission section between (12), that is, rubber 11b (12
b) The spring constant, k ₂ is the spring constant of the rubber 2 between the rotor 11 and the moment of inertia disc 1, and c is the viscous damping coefficient of the rubber 2 between the rotor 11 and the moment of inertia disc 1. ing.

Here, the natural angular frequency (ω _n ) of the main vibration system
Note that changes with the transfer of magnetic tape. That is, as described above, m ₁ also includes the moment of inertia of the magnetic tape itself wound on the tape reel. Therefore, as the magnetic tape is transported and the winding diameter of the tape reel on the winding side increases, the value of m ₁ increases and the natural angular frequency (ω _n ) of the main vibration system decreases. here,
In the entire region to end of winding from the winding start of the magnetic tape, natural angular frequency most effective natural angular frequency for (omega _n) to changing range (omega _n), the dynamic vibration effects as shown below To give.

The most effective natural angular frequency (ω _n ) may be, for example, the median of the change range of the natural angular frequency (ω _n ) from the beginning to the end of winding of the magnetic tape. In general, the lower the natural angular frequency (ω _n ) becomes, the higher the vibration level becomes. Therefore, in that case, within the change range of the natural angular frequency ω _n , the lower natural angular frequency side It may be configured to give a dynamic vibration absorbing effect to the point due to.

Natural frequency of the main vibration system of interest
(Ω_n) Is set, and this natural angular frequency (ω _n) Against
The parameter settings to give the dynamic vibration absorption effect are as follows.
You can do it this way. If the angular frequency of the external force is p,
The vibration amplitude of the main vibration system is shown in FIG. In addition, in FIG.
Is the vibration amplitude of the main vibration system,
And these are based on the amount of static displacement due to external force.
Expressed as a ratio. The horizontal axis is the natural angular frequency of the external force.
Natural frequency of main vibration system (ω_n) On the basis of these
It is expressed as a ratio. Curve L₁Is the moment of inertia disk 1
(M₂) Indicates the vibration amplitude of the main vibration system.
It

In this case, p / ω _n = 1. Where the natural angular frequency (ω _n ) of the main vibration system and the angular frequency p of the external force match.
Resonance occurs at the point of 0, and the vibration amplitude of the main vibration system becomes infinite. With the moment of inertia disk 1, m ₁ and m ₂
(M ₂ / m ₂ = β), the natural angular frequency (ω ₂ ) of the dynamic vibration absorber formed by the moment of inertia disk 1 and the rubber 2, and the natural angular frequency of the main vibration system (ω _n ) And (ω
₂ / ω _n = δ) and the damping ratio of the dynamic vibration absorber (μ: μ = c
The curve changes depending on the value of / 2m ₂ ω _n ), but it can be seen that the level of natural angular frequency decreases by setting the damping ratio (μ) to an appropriate value. Here, the natural angular frequency of the main vibration system is ω _n = √ (k ₁ / m ₁ ), and the natural angular frequency of the dynamic vibration absorber is ω ₂ = √ (k ₂ / m ₂ ).

The frequency ratio (δ) and the damping ratio (μ), which have the highest dynamic vibration absorption effect, may be set according to the following equation according to the theory of dynamic vibration absorption. δ = 1 / (1 + β) μ = √ (3β / (8 (1 + β) ³ )) The characteristic at this time is as shown in FIG. 5, and the level of vibration is reduced. Stabilization is achieved.

As described above, the maximum effect can be obtained by setting each parameter, but when it is difficult to set each parameter independently (for example, when the range of changing the physical properties of rubber is small). Even if the value of) is not necessarily set to the above value, for example, even in the case shown in FIG. 4, the natural vibration level can be reduced, so that the intended effect can be obtained.

As described above, by supporting the moment of inertia disk 1 with the rubber 2 which also functions as an elastic element and a damping element for the main vibration system which causes the rotor 11 (12) to vibrate, a dynamic vibration absorption effect is obtained. To reduce the natural vibration level of the rotating body 11 (12), stabilize the rotation speed fluctuation of the rotating body 11 (12), and at the same time shift the transfer delay position of the servo system to the high frequency side, It is possible to improve the servo characteristics and further stabilize the magnetic tape running speed.

In this embodiment, the elastic element and the damping element are used as the rubber 2 which is one member, but the present invention is not limited to this, and another element such as a metal spring and a viscous fluid may be used. Alternatively, a resin material having viscoelasticity can be used to obtain the same effect. Further, when the traveling direction of the magnetic tape is reversed, in the above description, the drive motor 17 is shown to be in contact with the rotating body 11, but the drive motor 17 is moved so as to be in contact with the rotating body 12. By doing so, it is possible to obtain the same effect as that of the above-described embodiment.

In this embodiment, the moment of inertia disc 1 is provided inside the rotary disk 11a to save space. However, when space saving is not a problem, If it is concentric with the turntable, the same action and effect can be obtained without providing it inside the turntable.

Next, a second embodiment based on the present invention will be described. In the above-described first embodiment, the moment of inertia disk and the rubber are used as the dynamic vibration absorbing device, but in the present embodiment, the rotary disk 11a (12a) is used.
The rubber is engaged with the peripheral portion of the rotary disc 11a (1a (1
An inertia moment rotating member 19 is provided which rotates following the rotation of 2a).

Referring to FIGS. 6 and 7, the drive motor 17, which is a power generation means, has a rotating body 11 for transmitting power.
While being in contact with the outer circumference of the rotary disk 11a, it is configured to be in contact with the outer peripheral rubber 11b of the rotary disk 11a and rotate. That is, the rubber 11b provided on the outer periphery of the rotary disk 11a becomes a part of the power transmission mechanism and is a transmission member for generating friction.
b is a viscoelastic member having elasticity and viscosity (damping property). At this time, the spring constant (k ₂ ) is
The spring constant and the viscous damping coefficient c due to the configuration of the contact portion 4 with respect to the inertia moment rotating member 19 represent the viscous damping coefficient of the rubber 11b, and the other parameters are the same as those in the first embodiment.

Also in this embodiment, the vibration level can be reduced by selecting each parameter as in the first embodiment. When setting the parameters,
A method of adjusting the radius (R ₁ ) of the contact point 4 with the rubber 11b for adjusting the spring constant (k ₂ ) and setting the natural angular frequency (ω ₂ ) is also possible. That is, the natural angular frequency (ω
_This is because the equivalent mass of the inertia moment rotating member 19, which is a parameter that determines ₂ ), is inversely proportional to the square of the radius (R ₁ ) of the contact portion 4, which is the point of action of force, as described above.

Next, FIG. 8 shows the frequency characteristic of the fluctuation level of the magnetic tape running speed in the magnetic tape running system of the conventional magnetic recording / reproducing apparatus shown in FIG. 26 when the dynamic vibration absorbing device is not used. . The horizontal axis represents frequency, and the vertical axis represents the amount called wow and flutter, which represents the amount by which the running speed of the magnetic tape fluctuates. That is, it is shown that the higher the level on the vertical axis of the graph, the greater the fluctuation of the magnetic tape running speed, and the higher the level on the vertical axis, the worse the performance. Therefore, it is desirable that the level on the vertical axis be low over the widest possible frequency range on the horizontal axis.

This example shows the characteristics of a magnetic tape running system using an audio compact cassette tape. Rubber 11 provided on the outer circumference of the turntable 11a
b is NBR rubber having a rubber hardness of 80 ° and has a spring constant of about 9 N / m. The equivalent mass of the main vibrating body composed of the tape reel 15 and the rotating body 11 is 0.005 g at the beginning of winding the magnetic tape and 0.019 g at the end of winding the magnetic tape.

The portion indicated by arrow P in FIG.
It is a mountain with a peak at Hz, and it can be seen that there is natural vibration at this point. This natural vibration is caused by the above-mentioned turntable 1
It is a natural vibration composed of a spring constant determined by the elastic coefficient of the rubber 11b provided on the outer periphery of 1a and the above equivalent mass. FIG. 8 shows the characteristics at the end of winding of the magnetic tape, and it can be seen that the characteristics of the magnetic tape running system are most deteriorated at this position.

Next, FIG. 9 shows the frequency characteristic of the running speed fluctuation level of the magnetic tape in the second embodiment. The inertia moment rotating member 19 has an inertia moment of 0.003 gf. cm. It is composed of a brass member of s ² and has an equivalent mass of 0.045 g. The equivalent mass ratio (β) is about 2.3, and the natural angular frequency ratio δ is about 0.7.

Comparing the parameters for optimum dynamic vibration absorption, there is some deviation due to the limit in the range in which parameters such as the elastic coefficient of rubber can be set.
As described in the embodiment of FIG.
It can be seen from FIG. 9 that the vibration level at point P seen in FIG. 8 is greatly reduced by the effect of the dynamic vibration absorbing device constituted by the elastic element and the damping element of 9 and the rubber 11b. According to the theory of dynamic vibration absorption, the vibration level is slightly increased at the Q and R points, but the effect of reducing the vibration level at the p point is large, and therefore the magnetic tape running speed fluctuation is comprehensively compared with that in FIG. The level is reduced by about 25% or more, and it can be seen that the magnetic recording apparatus of the present embodiment has a smaller fluctuation in the running speed of the magnetic tape than the magnetic recording / reproducing apparatus of the conventional example and the performance is high.

Further, the second embodiment has the following effects. That is, since the rotating direction of the rotating body 11 and the rotating direction of the inertia moment rotating member 19 are opposite to each other, it is possible to suppress the fluctuation of the magnetic tape rotation speed due to the disturbance in the rotating direction induced by the external force. Has become.

In more detail, considering the case where the mechanism of this embodiment has a portable structure and is held and shaken in the hand, the rotary body 1 having the structure of this embodiment is considered.
1 and each of the rotating elements of the inertia moment rotating member 19 generate a rotation moment due to the disturbance inertial force in the rotation direction. When such a rotation moment occurs, the rotation speed fluctuates and the magnetic tape running speed changes. Although it is possible to control this by the magnetic tape running speed control circuit, in the case of this embodiment, since the rotational moment can be suppressed by the mechanical structure, speed control with higher performance can be achieved. It will be possible.

That is, referring again to FIG. 7, when disturbance rotation is applied to the entire magnetic recording / reproducing apparatus in the direction of arrow A, an inertial force is generated in the direction opposite to the disturbance rotation due to the disturbance rotation, and rotation is performed. A rotational moment due to an inertial force is generated in the body 11 in the arrow B direction and also in the inertia moment rotating member 19 in the arrow B direction. At this time, if the rotating body 11 is rotating in the direction of the arrow B, the disturbance rotation moment is
However, since the inertia moment rotating member 19 is rotating in the direction of arrow C, the disturbance rotation moment acts in a direction of decreasing the rotation speed of the inertia moment rotating member 19.

Therefore, the changes in the rotational speed of the two cancel each other out, and the fluctuation in the running speed of the magnetic tape becomes smaller. Similarly, when the disturbance rotation moment is applied in the direction opposite to the arrow A direction, the disturbance rotation moment causes speed changes in opposite directions with respect to the rotating body 11 and the inertia moment rotating member 19, thereby changing the magnetic tape running speed. Fluctuations will be smaller.

Further, in the second embodiment, the moment of inertia rotating member 19A is in contact with the rotating body 12 of the tape reel on the supply side to rotate, but as shown below, the magnetic tape runs. While rotating in the reverse direction, it functions like the moment of inertia rotating member 19, but when engaged with the tape reel on the supply side, it also acts as a load torque element for the tape reel 16 on the supply side, and the magnetic tape running speed. Can be used as one element of the adjustment.
Further, since it also acts as an equivalent moment of inertia element of the supply-side tape reel, it can be used for adjusting dynamic response characteristics of the magnetic tape reel system.

As described above, in this embodiment, the inertia moment rotating member 19 for providing the dynamic vibration absorbing effect is configured to be in contact with the rubber 11b of the rotating body 11, so that the natural angle of the dynamic vibration absorbing device is increased. Since the rubber 11b also serves as the elastic element and the damping element for giving vibration, the elastic element and the damping element are not required newly. Also,
Even for the rotation moment due to the disturbance inertia moment,
Good magnetic tape running speed stability with little rotation fluctuation can be achieved.

As in the case of the first embodiment, when the traveling direction of the magnetic tape is reversed, the drive motor 17 is moved so as to be in contact with the turntable 12a. Can be obtained.

Next, a third embodiment based on the present invention will be described with reference to the drawings. The configuration of the third embodiment is almost the same as the configuration of the second embodiment described above. First, referring to FIG. 10, the drive motor 17 and
The inertial moment rotating member 19 which is an inertial body having an inertial moment is arranged on the rotary moving board 5 which is an operation mode switching means. The drive motor 17 and the inertia moment rotating member 19 are pressed against the turntable 11a and act in the same manner as in the above-described second embodiment to improve the dynamic vibration absorption effect and the stability of the magnetic tape running speed against the disturbance rotation moment. It is exerting.

In this embodiment, when the running direction of the magnetic tape is reversed, the rotary moving platen 5 rotates about the shaft 6 provided between the rotating body 11 and the rotating body 12 to rotate the rotating plate 12a. Further, the drive motor 17 and the inertia moment rotating member 19 are configured to be in contact with each other. At this time, the turntable 12a acts similarly to the turntable 11a.

In this embodiment, since only one moment of inertia rotating member 19 is required, the cost of the moment of inertia rotating member can be reduced. Further, since the inertia moment rotating member is not in contact with the rotating body on the supply side, when the load resistance of the rotating body on the supply side of the magnetic tape described in the second embodiment is reduced. It works particularly effectively. It should be noted that the above-described embodiments are not limited to the above-mentioned configurations, and similar effects can be obtained by combining them.

Next, a fourth embodiment based on the present invention will be described with reference to the drawings. First, referring to FIG. 11, the configuration of the magnetic recording / reproducing apparatus in the present embodiment is such that a shaft portion 101 (102) for rotating a tape reel for winding a magnetic tape 110, and this shaft portion 101 ( 1
02) and a turntable 103 (104) for rotating the same. An output shaft 108 for transmitting the rotational force of the drive motor 107 to the rotary disc 103 (104) is attached so as to be in pressure contact with the rubber 105 (106) provided on the peripheral edge of the rotary disc 103. The magnetic tape 110 is provided with a magnetic head for recording and reproducing information on the magnetic tape 110, and a pressure pad 112 at a position facing the magnetic head 109. Further, inside the magnetic tape cassette (not shown) in which the magnetic tape 110 is housed, rotating rollers 11a and 11b for restricting the running of the magnetic tape 110 are arranged at predetermined positions.

Further, a tape speed detection sensor 113 for detecting the running speed of the magnetic tape 110 is provided near the magnetic head 109. The information obtained from the tape speed detection sensor 113 is input to the control circuit 114 for controlling the rotation speed of the drive motor 107, and further the information is input from the control circuit 114 to the drive circuit 115.

The output shaft 108 of the drive motor 107 is a rubber 105 (1) provided on the periphery of the rotary disk 103 (104).
06) is in a position where it can be selectively pressed, and is selectively pressed against the rubber 105 (106) with a constant force by a switching mechanism (not shown). A rotatable roller is attached to the tape speed detection sensor 113, and the roller is in contact with or wound around the magnetic tape 110 by a certain amount. This roller rotates without slipping as the magnetic tape 110 moves, and has a rotation speed proportional to the running speed of the magnetic tape 110. This roller is equipped with a so-called FG (Frequency Generator),
A signal having a frequency proportional to the rotation speed of the roller is output, and the running speed information of the magnetic tape is obtained from the output signal.

Next, the operation when the magnetic tape 110 runs at a constant speed in the direction of arrow A during recording / reproduction of the magnetic tape will be described. When the magnetic tape 110 travels in the direction of arrow A, the output shaft 108 of the drive motor 107
Is pressed against the rubber 105 of the rotary disk 103 mounted coaxially with the shaft 101 on the magnetic tape winding side by a constant force by a switching mechanism (not shown). The driving force of the drive motor 107 is transmitted to the turntable 103 without sliding due to friction, and the shaft portion 101 on the magnetic tape winding side is rotated to wind the magnetic tape 110.

Next, the movement of the magnetic tape 110 causes the tape speed detection sensor 113 to output magnetic tape speed information. The obtained speed information is compared and calculated with a predetermined magnetic tape speed by the control circuit 114, and a control signal is output so that the speed becomes the predetermined magnetic tape speed. The output control signal is input to the drive motor 107 via the drive circuit 115, and the rotational speed of the drive motor 107 is controlled, so that the magnetic tape 110 can be fed at a predetermined tape speed.

Similarly, an operation when the magnetic tape 110 runs at a constant speed in the direction opposite to the arrow A at the time of recording / reproducing will be described with reference to FIG. Magnetic tape 110
When traveling in the direction of the arrow B, the rotating body 108 of the drive motor 107 is provided with a rubber 106 provided on the peripheral portion of a rotary disc 104 mounted coaxially with the shaft portion 102 on the magnetic tape winding side by a switching mechanism (not shown). Is pressed by a constant force to rotate the drive motor 107 in the direction opposite to the case of FIG.

The driving force of the drive motor 107 is transmitted to the rotating disk 104 without slipping due to friction, and the shaft portion 102 on the magnetic tape winding side is rotated to wind the magnetic tape 110. By moving the magnetic tape 110, the tape speed detection sensor 1
Magnetic tape speed information is output from 13. The obtained magnetic tape speed information is compared and calculated with a predetermined magnetic tape running speed by the control circuit 114, and a control signal is output so as to obtain a predetermined tape speed. The output control signal is output to the drive motor 107 via the drive circuit 115.
By controlling the rotation speed of the drive motor 107, it is possible to feed the magnetic tape 110 at a predetermined tape speed.

Further, the fast-forwarding of the magnetic tape 110 can be realized by pressing the output shaft 108 of the drive motor 107 against the turntable on the winding side of the magnetic tape and rotating the drive motor 107 at a high speed. The return can be realized by bringing the output shaft 108 into pressure contact with the rotating plate on the magnetic tape supply side and rotating the drive motor 107 at a high speed in the opposite direction.

Next, FIGS. 13 and 14 show ideal open loop transfer characteristics of the magnetic tape speed control system of the magnetic recording / reproducing apparatus using the above-mentioned drive mechanism. 13 and 14, the magnetic tape speed control system described above has a phase delay element due to a mechanism and a phase delay element in the circuit. Therefore, as the frequency increases, the phase delays and exceeds a certain frequency. The phase is delayed by 180 ° or more.
In order to improve the servo characteristics of the control system, it is basically desirable to secure the stability of the control system such as gain margin and phase margin and increase the gain as much as possible, as shown in FIGS. 13 and 14. .

However, in reality, the tape reel drive mechanism as described above is used as the tape reel drive means, the magnetic tape speed is detected, and the magnetic tape is wound based on the magnetic tape speed information. In a magnetic recording / reproducing apparatus that realizes constant speed running of a magnetic tape by controlling the number of rotations of a motor that drives a reel, the spring constant of the contact portion between the rotary disk 103 and the output shaft 108 and the total of the shaft portion 101 are reduced. Equivalent moment of inertia and output shaft 10
There are vibrations due to the total equivalent moment of inertia with respect to 8.

The frequency of this vibration is determined by the spring constant of the contact portion between the turntable 103 and the output shaft 108, the total equivalent moment of inertia of the rotor around the rotor 101A on the magnetic tape winding side, and the output shaft 108 around the output shaft. This is the natural frequency of the system composed of all equivalent moments of inertia. The moment of inertia of the tape reel on the magnetic tape take-up side is (J ₁ ), and the moment of inertia of the magnetic tape 110 wound on the tape reel on the magnetic tape take-up side is (J ₂ ) of the tape reel on the tape take-up side. If the moment of inertia of the rotating disk 103 is (J ₃ ), the total equivalent moment of inertia (Ja) around the rotating body on the magnetic tape winding side can be expressed by Ja = J ₁ + J ₂ + J ₃ .

The total equivalent moment of inertia (Jb) around the output shaft 108 of the drive motor 107, the radius of the rotary disc 103 (Ra), the radius of the output shaft 108 (Rb), the rotary disc 10
Assuming that the spring constant of the outer peripheral material of 3 and the contact portion of the output shaft 108 is K, the vibration frequency (F) is

[0076]

[Equation 1]

It can be expressed as Since the vibration frequency (F) is also related to the moment of inertia of the magnetic tape 110 wound on the tape reel on the magnetic tape winding side, the vibration frequency (F) of the magnetic tape 110 wound on the tape reel on the magnetic tape winding side is related. The vibration frequency changes as the winding radius changes. That is, the magnetic tape 110 is wound around the tape reel on the tape winding side, and the moment of inertia of the tape reel on the magnetic tape winding side increases as the winding radius increases, and the vibration frequency gradually shifts to a lower frequency.

Next, with reference to FIG. 15 and FIG. 16, an example of the open loop transmission characteristic of the actual magnetic tape running speed control system near the end of the magnetic tape winding is shown. C shown in FIG.
Are resonances due to the spring constant based on the outer peripheral material of the rotating disk 103, the total equivalent inertia moment of the magnetic tape winding side shaft portion 101, and the total equivalent inertia moment of the output shaft 108. This resonance moves to a lower frequency as the magnetic tape 110 is wound on the winding reel, and the resonance delays the phase. In FIG. 16, the phase is 1
Since the frequency delayed by 80 °, so-called phase intersection point D, is lower than the frequency of resonance C, in order to secure the stability of the control system, that is, the gain margin and the phase margin,
It is necessary to reduce the gain of the control system, and the servo characteristic becomes worse than the ideal open loop transfer characteristic (FIGS. 13 and 14). Therefore, it is not possible to obtain a sufficient constant speed feeding performance of the magnetic tape, so-called wow and flutter. 17 and 18, another example of the open loop transfer characteristic of the actual magnetic tape speed control system near the winding end of the magnetic tape 110 will be shown. C shown in FIG.
Is the spring constant based on the outer peripheral material of the turntable 103, the total equivalent moment of inertia about the rotating body 101A, and the output shaft 108.
Is the resonance due to the total equivalent moment of inertia of.
This resonance moves to a lower frequency as the magnetic tape 110 is wound on the winding-side tape reel, and the phase is delayed due to this resonance. In FIG. 18, the frequency at which the phase is delayed by 180 °, that is, the so-called phase intersection point D is higher than the frequency of the resonance C, and therefore has no great influence on the servo characteristics of the control system. Therefore, the stability of the control system, that is, the gain margin and the phase margin are secured, and the ideal open-loop transfer characteristic (see FIG. 13) is obtained.
And since the same servo characteristics as Fig. 14) can be maintained,
Sufficient constant speed tape feed performance, so-called wow and flutter, can be obtained.

From the above, in order to obtain good constant speed tape feeding performance of the magnetic tape, that is, wow and flutter, from the time when the magnetic tape is wound on the tape reel on the winding side to the time when it is wound. The resonance frequency may be always higher than the phase intersection frequency in the open loop transfer characteristic of the tape speed control system. That is, the total equivalent moment of inertia about the tape reel, the turntable, and the shaft of the magnetic tape wound around the tape reel (Ja), the radius of the turntable (Ra), and the total about the output shaft of the drive motor. The equivalent moment of inertia (Jb), the radius of the drive motor shaft (Rb), the spring constant of the contact portion between the outer peripheral material of the rotary disk and the output shaft K, and the phase intersection point in the open loop transfer characteristic of the tape speed control system. When the frequency is set to F, during recording / playback, from the time when the magnetic tape is wound on the tape reel on the magnetic tape take-up side to the time when it is wound,

[0080]

[Equation 2]

In order to satisfy the above, each parameter constituting the moment of inertia between the rotary body and the rotary disk, the radius of the rotary disk, the inertia moment of the drive motor, the radius of the output shaft, and the spring constant based on the outer peripheral material of the rotary disk is determined. By doing so, the deterioration of wow and flutter can be suppressed to a small level, and good wow and flutter performance can be obtained.

Next explained is the fifth embodiment according to the invention. The fifth embodiment is a magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic tape as an analog signal by using the same driving mechanism as that of the third embodiment.
A compact cassette tape is actually used as the magnetic tape, and NBR rubber (hardness 70 °) is used as the outer peripheral material of the rotating disk.
When is used, the setting of each parameter of the drive mechanism will be described.

In this embodiment, each parameter is the radius of the rotating disk Ra = 2 cm, the radius of the output shaft Rb = 0.075 cm, the total equivalent moment of inertia Jb about the output shaft Jb = 0.008 gf · cm · s ² . In addition, since the moment of inertia J ₂ of the magnetic tape wound around the tape reel changes according to the change in the diameter of the magnetic tape winding, in this embodiment, the total equivalent moment of inertia around the rotating body on the magnetic tape winding side ( Ja) changes from the beginning to the end of winding of the magnetic tape, and Ja = 0.10 to 0.063 gf · cm · s ² . The spring constant K of the contact portion between the outer peripheral material of the rotating disk and the output shaft is E, the longitudinal elastic modulus, H is the width of the rotating body in the direction, and M is the radial thickness, and the contact width of the output shaft in the main direction is If it is B,

[0084]

[Equation 3]

In the present embodiment, the spring constant based on the outer peripheral material of the rotating disk K = 4200
It is gf / cm.

In a magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic tape as an analog signal, it is internationally decided to measure through a circuit having an auditory sense correction characteristic shown in FIG. 19 when evaluating wow and flutter. , 0.2 Hz
The frequency fluctuation component of wow and flutter of about 200 Hz becomes a problem in hearing.

In this embodiment, the spring constant based on the outer peripheral member of the rotating disk, the frequency of vibration caused by the total equivalent moment of inertia of the rotating body on the tape winding side and the total equivalent moment of inertia of the output shaft, and the winding of the magnetic tape. FIG. 20 shows the relationship of the magnetic tape winding rate of the take-up side rotating body. This Figure 2
At 0, the vibration frequency changes from about 210 Hz to 180 Hz as the tape winding rate of the rotating body on the magnetic tape winding side changes from 0% to 100%.

The wow and flutter frequency components at E and F in FIG. 20 are shown in FIGS. 21 and 22, respectively. The G region shown in FIGS. 21 and 22 is the frequency component of the vibration and is a factor that obviously makes wow and flutter worse, but the frequency of vibration is lower in FIG. 22 than in FIG. Therefore, the amplitude of vibration is large and the adverse effect on wow and flutter is large.

FIG. 23 shows the relationship between the tape winding ratio of the rotating body on the winding side of the magnetic tape and the wow and flutter. In FIG. 23, the value of wow and flutter gradually deteriorates as the tape winding rate of the rotating body on the magnetic tape winding side increases. This is mainly because the frequency component of the vibration exists in the wow and flutter frequency band (0.2 to 200 Hz) and moves to the lower range, and the tape winding of the rotating body on the winding side of the magnetic tape is performed. Wow and flutter with a wear rate of 75% or more, that is, a frequency of the vibration of 100 Hz or less, deteriorates rapidly.

Next, the radial thickness L of the outer peripheral material of the rotating disk
FIG. 24 shows the relationship between the tape winding rate of the rotating body on the magnetic tape winding side and the vibration frequency when the ratio is changed to about 80%.
Shown in. The spring constant K based on the outer peripheral material of the turntable at this time is 8200 gf / cm. From FIG. 24, the above vibration frequency is about 290 Hz as the tape winding rate of the rotating body on the magnetic tape winding side changes from 0% to 100%.
Changes to about 120 Hz and does not fall below 100 Hz.

FIG. 25 shows the relationship between the tape winding ratio of the rotating body on the magnetic tape winding side and wow and flutter. Figure 25
In FIG. 23, wow and flutter worsen as the tape winding rate of the rotating body on the magnetic tape winding side changes from 0% to 100%. The wow and flutter is considerably improved when the tape winding rate of the above is 75% or more. This is because the frequency component of the vibration is the wow and flutter frequency band (0.2 to 200
This is because the frequency of the above vibration does not become 100 Hz or less by suppressing the movement to the low frequency range at 100 Hz). That is, good wow and flutter performance can be obtained by always setting the vibration frequency to 100 Hz or higher.

From the above, in order to obtain the good constant speed tape feeding performance of the magnetic tape, that is, so-called wow and flutter, the magnetic tape is always above the time from the winding start to the winding end. Resonance frequency is 100
It suffices to determine the parameters that configure the drive mechanism so as to be equal to or higher than Hz. That is, the total equivalent moment of inertia of the magnetic tape wound around the rotor is (J
a), the radius of the turntable (Ra), the total equivalent moment of inertia about the output shaft of the drive motor (Jb), the radius of the output shaft of the drive motor (Rb), the outer peripheral material of the turntable and the output shaft When the spring constant of the contact portion is K, during recording / reproduction, from the time when the magnetic tape is wound around the tape winding side rotary member to the time when it is wound.

[0093]

[Equation 4]

If the inertial moments of the rotor and the rotary disk, the radius of the rotary disk, the drive motor inertial moment, the output shaft radius, and the spring constant based on the outer peripheral material of the rotary disk are determined so that The deterioration of wow and flutter can be suppressed to a small level, and good wow and flutter performance can be obtained.

In this embodiment, when a compact cassette tape is used as the magnetic tape and NBR rubber (hardness 70 °) is used as the outer peripheral material of the reel drive wheel, information is recorded and reproduced as an analog signal. However, the present embodiment is not limited to this, and good wow and flutter performance can be obtained by determining each parameter configured so that the above-mentioned formula (4) holds. it can.

[0096]

According to the first to eighth aspects of the present invention, at least one of the first and second rotating bodies is engaged with the first or second rotating body. A dynamic vibration absorbing device for dynamically absorbing the generated natural vibration is provided. As a result, the natural vibration generated in the magnetic tape drive system in the magnetic recording / reproducing apparatus is absorbed by the dynamic vibration absorbing device, and the natural vibration in the magnetic tape drive system is significantly reduced. Further, since the dynamic vibration absorbing device can be attached while keeping the rigidity of the driving force transmission system high, it is possible to absorb the vibration without deteriorating the rigidity unlike the conventional vibration suppressing means, and the magnetic tape. High-performance driving control can be realized.

As a result, the fluctuation of the magnetic tape running speed generated by the natural vibration is reduced, and the magnetic tape running speed is stabilized. Further, since the resonance peak level in the control characteristic is reduced, the phase delay amount is reduced and the control characteristic is improved. As a result, it is possible to provide a high performance magnetic recording / reproducing apparatus.

Next, according to the inventions of claims 2 to 4 based on the present invention, the dynamic vibration absorbing device is a disk provided coaxially with the rotating disk. It is attached to the turntable with a viscoelastic member interposed.

As described above, the dynamic vibration absorbing device can be realized by mounting the inertial body made of a disk and the disk on the rotary disk with the viscoelastic member including the elastic element and the damping element interposed. .

According to a third aspect of the magnetic recording / reproducing apparatus of the present invention, the disc is provided inside the rotary disk. As a result, the space of the magnetic recording / reproducing apparatus can be saved, and the size of the magnetic recording / reproducing apparatus can be reduced.

Next, according to the magnetic recording / reproducing apparatus of the fourth aspect of the present invention, a rubber member or a metal spring and a viscous fluid or a viscoelastic resin member are used as the viscoelastic member. This makes it possible to realize a viscoelastic member including an elastic element and a damping element.

Next, according to the magnetic recording / reproducing apparatus of the fifth to eighth aspects of the present invention, the vibrating member is engaged with the dynamic vibration absorbing device at the peripheral portion of the rotary disk. The rotating member is provided so as to rotate in accordance with the rotation of the turntable.

As a result, the rotary member rotates following the rotation of the rotary disk. At this time, the rotary member rotates in the opposite direction to the rotation of the rotary disk.

Therefore, when rotational vibration is externally applied to the magnetic recording / reproducing apparatus, the rotational moment due to the rotational vibration generated on the rotating disk and the rotational moment due to the rotational vibration generated on the rotating member act in opposite directions. for that reason,
The respective rotation moments cancel each other out, and it is possible to suppress the amount of change in the magnetic tape running speed due to rotational vibration from the outside, and as a result, it is possible to further stabilize the magnetic tape running speed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a rotary disk of a magnetic recording / reproducing apparatus in a first embodiment.

FIG. 2 is a plan view showing the structure of a rotary disk of the magnetic recording / reproducing apparatus in the first embodiment.

FIG. 3 is a schematic diagram for explaining a dynamic vibration absorbing effect of the magnetic recording / reproducing apparatus in the first embodiment.

FIG. 4 is a first diagram showing characteristics of a dynamic vibration absorbing effect of the magnetic recording / reproducing apparatus in the first embodiment.

FIG. 5 is a second diagram showing the characteristics of the dynamic vibration absorption effect of the magnetic recording / reproducing apparatus in the first embodiment.

FIG. 6 is a schematic diagram showing a configuration of a magnetic recording / reproducing apparatus according to a second embodiment.

FIG. 7 is a plan structural view of a magnetic recording / reproducing apparatus in a second embodiment.

FIG. 8 is a characteristic diagram showing speed fluctuations in a conventional magnetic recording / reproducing apparatus.

FIG. 9 is a characteristic diagram showing speed fluctuations of the magnetic recording / reproducing apparatus in the second embodiment.

FIG. 10 is a plan view showing the configuration of a magnetic recording / reproducing apparatus according to a third embodiment.

FIG. 11 is a plan view showing a first state of the magnetic recording / reproducing apparatus according to the fourth embodiment.

FIG. 12 is a plan view showing a second state of the magnetic recording / reproducing apparatus according to the fourth embodiment.

FIG. 13 is a first diagram showing a transfer characteristic of a circuit section of a magnetic recording / reproducing apparatus in a fourth example.

FIG. 14 is a second diagram showing the transfer characteristic of the circuit section of the magnetic recording / reproducing apparatus in the fourth example.

FIG. 15 is a third diagram showing the transfer characteristic of the circuit portion of the magnetic recording / reproducing apparatus in the fourth embodiment.

FIG. 16 is a fourth diagram showing the transfer characteristic of the circuit unit of the magnetic recording / reproducing apparatus in the fourth embodiment.

FIG. 17 is a fifth diagram showing the transfer characteristic of the circuit section of the magnetic recording / reproducing apparatus in the fourth example.

FIG. 18 is a sixth diagram showing the transfer characteristic of the circuit unit of the magnetic recording / reproducing apparatus in the fourth embodiment.

FIG. 19 is a wah / flutter audibility correction characteristic diagram.

FIG. 20 is a diagram showing a relationship between a tape winding rate and a vibration frequency of a take-up side tape reel of a magnetic recording / reproducing apparatus in a fifth example.

21 is a diagram showing a relationship between wow and flutter level and frequency in a region indicated by F in FIG.

22 is a diagram showing a relationship between wow and flutter level and frequency in a region indicated by E in FIG.

FIG. 23 is a first diagram showing the relationship between the tape winding rate and the wow / flutter of the tape reel on the winding side of the magnetic recording / reproducing apparatus in the fifth embodiment.

FIG. 24 is a diagram showing the relationship between the tape winding rate and the vibration frequency of the tape reel on the winding side of the magnetic recording / reproducing apparatus in the fifth example.

FIG. 25 is a second diagram showing the relationship between the tape winding rate and wow and flutter of the tape reel on the winding side of the magnetic recording / reproducing apparatus in the fifth embodiment.

FIG. 26 is a perspective view showing a structure of a magnetic recording / reproducing apparatus in the related art.

FIG. 27 is a plan view showing the structure of a magnetic recording / reproducing apparatus in the related art.

[Explanation of symbols]

 1 Inertia moment disk 2 Rubber 11,12 Rotating body 11a, 12a Rotating disk 11c, 12c Shaft part 11b, 12b Rubber 15,16 Tape reel 17 Drive motor 17a Output shaft 19 Inertia moment rotating member Indicates the same or corresponding part.

Claims (8)

[Claims] 1. A first and a first shaft having a shaft portion for engaging with a tape reel for winding a magnetic tape, and a turntable provided coaxially with the shaft portion at one end of the shaft portion. No. 2 rotating body, a drive device that engages with a peripheral portion of the rotating disk and rotates at least one of the first or second rotating body, and at least one of the first or second rotating body. And a dynamic vibration absorbing device for dynamically absorbing the natural vibration generated in the first or second rotating body. 2. The dynamic vibration absorbing device has a disk provided coaxially with the rotary disk, and the disk is attached to the rotary disk via a viscoelastic member. Magnetic recording and reproducing device. 3. The magnetic recording / reproducing apparatus according to claim 2, wherein the disc is provided inside the rotary disk. 4. The magnetic recording / reproducing apparatus according to claim 3, wherein the viscoelastic member is a rubber member, a member made of a metal spring and a viscous fluid, or a viscoelastic resin member. 5. The dynamic vibration absorbing device has a rotating member which is provided so as to be engaged with the peripheral edge portion of the rotary disc with a viscoelastic member interposed, and which rotates following the rotation of the rotary disc. The magnetic recording / reproducing apparatus according to claim 1. 6. The magnetic recording / reproducing apparatus according to claim 5, wherein the viscoelastic member is a rubber member or a viscoelastic resin member. 7. The drive device and the dynamic vibration absorbing device are installed on the same base substrate, and by moving the substrate, the peripheral portion of the turntable of the first or second rotating body. The magnetic recording / reproducing apparatus according to claim 5, wherein the drive device and the rotating member are engaged with each other. 8. The magnetic recording / reproducing according to claim 7, wherein the base substrate is rotatably provided around a fulcrum provided between the first rotating body and the second rotating body. apparatus.