JPH09153241A - Magnetic recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a tape beating sound by a simple constitution SOLUTION: This device provided on a rotary drum device 1 includes a curved surface nearly similar to the curved surface of the rotary drum device 1 on which a magnetic tape 7 is wound and a stranding preventing member 8 for preventing the magnetic tape 7 from being stranded on the rotary drum device 1 caused by the winding operation of the magnetic tape 7 performed by a leading guide base 3. In the stranding preventing member 8, a magnetic tape vibration regulating part 8b positioned in the vicinity of the detaching part of the wound magnetic tape 7 from a magnetic head 2 caused by its traveling is integrally formed.

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 for performing recording / reproduction by winding a magnetic tape around a rotary drum device at a predetermined angle when a traveling magnetic tape is separated from a magnetic head provided in the rotary drum device. The present invention relates to a technique for reducing the generated tapping sound (tape vibration).

[0002]

2. Description of the Related Art In a home-use digital VTR that converts a video signal into a digital signal and performs recording / reproduction, the rotation speed of a rotary drum device provided with a magnetic head is 9000 rpm, which is higher than the conventional home-use analog VTR of 1800 rpm. It's fast.

On the other hand, the noise generated by the rotation of the rotary drum device includes a motor electromagnetic noise, a bearing noise, and a wind noise. Further, the above-mentioned tape tapping noise is superposed when the magnetic tape runs during recording / reproduction, and these noises are generated. Since noise increases in proportion to the number of rotations of the rotary drum device, the home digital VTR is louder than the home analog VTR.

Among these noises, the tape hitting sound is a leading guide for winding the magnetic tape obliquely at a predetermined angle from the position where the magnetic head separates from the magnetic tape as the wound magnetic tape runs. The noise is generated by the vibration of the magnetic tape up to the guide post provided on the base. Therefore, if the vibration of the magnetic tape is eliminated, the tapping sound can be eliminated, and the noise during recording and reproduction can be reduced.

In a certain experiment, in the home digital VTR, the noise near the rotary drum device during recording and reproduction was about 54d when the audibility correction (JIS / A filter) was applied.
Although it is BA, it is about 50dBA when the magnetic tape is removed from the rotating drum device and the tapping sound is removed, and it is about 4d.
The improvement of BA was confirmed.

The tape tapping sound will be described in more detail. FIG. 5 is a cross-sectional view of the rotary drum device when the magnetic tape is running, viewed from above. The rotary drum device 21 rotates in the direction of arrow A, and the magnetic tape 22 runs in the direction of arrow B. Incidentally, 23 and 23 are magnetic heads.

Magnetic tape 2 in the rotary drum device 21
The air film amount of the portion b where the magnetic head 23 is detached from the magnetic tape 22 is smaller than that of the portion a on the inlet side of 2. As a result, the amount by which the magnetic head 23 bites into the magnetic tape 22 increases as it progresses from part a to part b.

FIG. 6 shows a magnetic head 23 and a magnetic tape 22.
Is a graph showing how the contact force changes from the portion a on the inlet side to the portion b on the release side. The horizontal axis indicates the position of the magnetic head 23, and the vertical axis indicates the relative value of the contact force. The contact force is almost proportional to the amount of the magnetic head 23 biting into the magnetic tape 22.
The contact force is maximized at the portion b where is separated. And b
In the portion, since the magnetic head 23 is suddenly separated from the magnetic tape 22, the contact force of the magnetic head 23 applied to the magnetic tape 22 is suddenly removed, and the portion b is moved to the next guide post, that is, the leading guide base. The magnetic tape 22 vibrates up to the guide post provided at the position, and a tapping sound is generated.

FIG. 7 is a three-dimensional graph showing the measurement results of the vibration of the magnetic tape 22 after the magnetic head 23 is detached, measured by a magnetic recording / reproducing apparatus. The horizontal direction is time and the depth direction is magnetic. The width and height directions of the tape 22 indicate the magnitude of vibration. As is clear from the graph, the peak of vibration occurs twice per one rotation of the rotary drum device 21. This is because the rotary drum device 21 is provided with two magnetic heads 23. Also, the magnetic tape 22
Vibration is greatest on the upper end side of the magnetic tape 22 from which the magnetic head 23 is detached, and is almost nonexistent on the lower end side of the magnetic tape 22 in contact with the lower drum fixed in the rotary drum device 21. This is because the magnetic tape 22 is obliquely wound around the rotary drum device 21, so that the magnetic head 23 is detached from the magnetic tape 22 at the upper end side of the magnetic tape 22. Therefore, the magnetic tape 2
By suppressing the vibration on the upper end side of 2, the tapping sound is drastically reduced.

In order to reduce the hitting sound of the tape described above, measures have been conventionally taken such as providing a bulge (projection) at the magnetic tape detaching portion of the lower drum or disposing an impedance roller.

The bulge is a projection of 50 to 60 μm provided on the magnetic tape running surface at the position where the magnetic head is detached at the upper end of the lower drum, and reduces the contact force between the magnetic tape and the magnetic head. Vibration of magnetic tape is reduced.

Further, the impedance roller is a roller having a large inertia, which is arranged between the detaching side of the rotary drum device and the next guide post, and is magnetic by contacting with a magnetic tape and rotating. Vibration of the tape is reduced.

[0013]

However, in the above-mentioned bulge, the process for partially providing the protrusion (bulge) on the lower drum is complicated and the cost is increased. further,
The position where the bulge is provided and the amount of protrusion are limited in processing, and the tape tapping noise cannot be sufficiently reduced.

Needless to say, providing the above-mentioned impedance roller increases the cost, and in a small mechanism used for a home digital VTR or the like, the impedance roller is provided between the rotary drum device and the next guide post. It is difficult to secure a space for arranging.

It is an object of the present invention to reduce the tape hitting noise with a simple structure in magnetic recording / reproducing using a rotary drum device.

[0016]

In order to solve the above-mentioned problems, the present invention provides a rotary drum device for rotating a magnetic head, a leading guide base for winding a magnetic tape on the rotary drum device obliquely at a predetermined angle, and The magnetic tape is provided on the rotary drum device and has a curved surface that is substantially the same as the curved surface of the rotary drum device on which the magnetic tape is wound, and the magnetic tape is wound on the rotary drum device by the winding operation of the magnetic tape by the leading guide base. A ride-up prevention member for preventing the rider from riding on the upper part of the magnetic head, and the ride-on prevention member is further provided with a magnetic field located near a detaching portion that is detached from the magnetic head when the wound magnetic tape runs. The tape vibration suppressing part is integrally formed.

Further, the magnetic tape vibration suppressing portion has a protruding portion on the magnetic surface side of the magnetic tape and at a position where the vibration of the magnetic tape caused by the detachment of the magnetic head is maximum. Further, the amount of protrusion of the protrusion protruding from and contacting the magnetic tape is set according to the amplitude of vibration of the magnetic tape. Furthermore, the said protrusion part is provided with two or more.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing a main part of a magnetic recording / reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the main part. In FIG. 1, reference numeral 1 is a rotary drum device, which is composed of an upper drum 1a for rotating a magnetic head 2 and a fixed lower drum 1b. Two magnetic heads 2 are provided facing the upper drum 1a by 180 degrees, but one of them is omitted in the drawing. And, 3 is an outlet side leading guide base, which has an inclined guide 4 and a guide roller 5 similarly to an inlet side leading guide base (not shown),
A cassette (not shown) is moved by a loading motor (not shown) along a groove 6 provided on the chassis.
The magnetic tape 7 is pulled out from the inside and wound around the rotary drum device 1 at a strong angle of 180 degrees and obliquely.

On the other hand, 8 is a riding prevention member made of a resin material, which is provided on the upper part of the rotary drum device 1,
The rotary drum device 1 has a curved surface 8a that is substantially the same as the curved surface on which the magnetic tape 7 is wound.

As shown in the cross-sectional view of the main part of FIG. 2, the ride-on preventing member 8 holds the printed circuit board 9a having the stator coil pattern forming the drum motor 9, and the boss 10 holds the printed circuit board 9a.
It is fixed to. Further, since the boss 10 is fixed to the shaft 11 fixed to the lower drum 1b, the riding prevention member 8 does not rotate. When the winding operation of the magnetic tape 7 by the leading guide base 3 is performed, the magnetic tape 7 is attempted to be obliquely wound around the rotary drum device 1, so that the magnetic tape 7 rides on the upper portion of the upper drum 1a. However, since the curved surface 8a provided on the ride-up preventing member 8 receives the magnetic tape 7, the magnetic tape 7 is wound around the upper edge 1a 'of the upper drum 1a without being damaged.

In FIG. 2, 9b is a rotary coil which constitutes the drum motor 9, and is fixed to the bearing 12 together with the upper drum 1a on which the magnetic head 2 is provided. Reference numeral 13 is a rotary transformer that transmits and receives signals between the magnetic head 2 and a signal processing circuit (not shown). The rotor transformer 13a is fixed to the bearing 12 and rotates together with the magnetic head 2, and the lower drum 1b. It is composed of a stator side 13b fixed to the.

The riding prevention member 8 has a structure shown in FIG.
As shown in FIG. 2, a magnetic tape vibration suppressing portion 8b is integrally formed in the vicinity of the detaching portion D which is detached from the magnetic head 2 when the wound magnetic tape 7 travels. Further, the magnetic tape vibration suppressing portion 8b has a projecting portion 8c on the magnetic surface side of the magnetic tape 7 and at one position 7a where the vibration of the magnetic tape caused by the detachment of the magnetic head 2 is maximized. .

On the other hand, FIG. 3 is a drawing seen from the upper side of the rotary cylinder device 1, and is an explanatory view schematically showing the positional relationship among the magnetic head 2, the magnetic tape 7, and the magnetic tape vibration suppressing portion 8b. The protruding portion 8c is provided on the magnetic surface side of the magnetic tape 7 and at a position where the vibration of the magnetic tape 2 caused by the detachment of the magnetic head 2 is maximized, and is in contact with the upper end side of the magnetic tape 7. The vibration of the magnetic tape 7 here occurs when the contact force of the magnetic head 2 applied to the magnetic tape 7 is suddenly removed.
That is, vibration is generated in the cycle in which the magnetic head 2 is detached from the magnetic tape 7. In addition, the position where the vibration of the magnetic tape is maximum when a certain magnetic head is detached means that the traveling speed of the magnetic tape from the detaching portion 7a where the magnetic head is detached by the traveling of the wound magnetic tape ( mm / sec) is the rotation speed (r
The position is an integer multiple of the value divided by pm).

Therefore, the amplitude is maximized by the number of magnetic heads provided in the rotating drum device between the positions where the running speed of the magnetic tape from the detaching portion 7a is divided by the number of rotations of the rotating drum device. . The magnitude of the amplitude depends on the amount of protrusion of each magnetic head from the rotary drum device. In addition, the amount of protrusion of the protrusion 8c that contacts the magnetic tape 7 is set to be approximately the same as the amplitude of vibration of the magnetic tape in order to maximize the effect of reducing vibration. The magnitude of the amplitude is about 50 to 60 μm in a general household analog VTR.

Further, as described above, at the position where the maximum amplitude is reached, the running speed of the magnetic tape is divided by the number of revolutions of the rotary drum device from the detaching portion where the wound magnetic tape is detached from the magnetic head as it travels. The position is an integer multiple of the value, and there are multiple. There are a plurality of magnetic heads depending on the number of magnetic heads. Therefore, as shown in FIG. 4, a plurality of protrusions, for example, 8
By providing d, 8e, and 8f, the effect of reducing the vibration of the magnetic tape can be further enhanced.

[0026]

According to the present invention, the vibration of the magnetic tape generated between the magnetic tape detaching portion and the guide post in the rotary drum device can be reduced, and the tape tapping noise due to the magnetic tape drive can be reduced at low cost and efficiently. be able to.

Further, like a small mechanism used in a camera-integrated VTR or the like, the magnetic tape vibration suppressing member can be provided in a narrow space between the rotary drum device and the guide post, and its effect is great.

The magnetic tape vibration suppressing portion can be formed of a resin material, and the degree of freedom regarding the shape and dimensions is extremely large.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an essential part of an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a main part of an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a main part of another embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a mechanism in which a tape tapping sound is generated.

FIG. 6 is a graph illustrating a mechanism of producing a tape tapping sound.

FIG. 7 is a graph showing a measurement result of vibration of a magnetic tape.

[Explanation of symbols]

 1 Rotating Drum Device 2 Magnetic Head 3 Exit Side Leading Guide Base 4 Inclined Guide 7 Magnetic Tape 8 Ride Prevention Member 8b Magnetic Tape Vibration Suppressing Parts 8c, 8d, 8e, 8f Projecting Part

Claims (4)

[Claims] 1. A rotary drum device for rotating a magnetic head, a leading guide base for winding a magnetic tape obliquely around the rotary drum device at a predetermined angle, and a magnetic drum in the rotary drum device which is provided above the rotary drum device. A run-up prevention member that has a curved surface substantially the same as the curved surface around which the tape is wound, and that prevents the magnetic tape from running on the upper portion of the rotary drum device by the winding operation of the magnetic tape by the leading guide base. Further, the ride-on prevention member is integrally formed with a magnetic tape vibration suppressing portion located in the vicinity of a detaching portion that is detached from the magnetic head when the wound magnetic tape travels. Magnetic recording / reproducing device. 2. The magnetic tape vibration suppressor has a protrusion on the magnetic surface side of the magnetic tape and at a position where the vibration of the magnetic tape caused by the detachment of the magnetic head is maximized. The magnetic recording / reproducing apparatus according to claim 1. 3. The magnetic recording / reproducing apparatus according to claim 2, wherein the amount of protrusion of the protrusion protruding from and contacting the magnetic tape is set according to the amplitude of vibration of the magnetic tape. 4. The magnetic recording / reproducing apparatus according to claim 2, wherein a plurality of the protrusions are provided.