JPH05342714A - Rotary head device - Google Patents

Abstract

PURPOSE:To provide a rotary head device wherein its small size 2 its light weight are realized by preventing that a wavy phenomenon is caused in a magnetic tape when an air current generated by the rotation of a cylindrical drum flows into a part between the cylindrical drum and the magnetic tape. CONSTITUTION:In the head device, a magnetic tape 5 is wound spirally at a prescribed lap angle thetaA on a cylindrical drum 1 which is provided with a rotary magnetic head 4, and a magnetic recording/playback operation is performed. In the head device, one part of an edge part 5a in the magnetic tape 5 which is wound spirally at the prescribed lap angle thetaA is constituted so as to travel in an unwound state in the axial direction of the cylindrical drum 1 over a prescribed angle thetaB (where thetaB/thetaA ca. 0.2 to 0.5) from the feed side within the range of the prescribed lap angle thetaA.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head suitable for use in, for example, a video tape recorder,
In particular, the present invention relates to a rotary head device most suitable for a portable home video camera or the like.

[0002]

2. Description of the Related Art A general rotary head device includes a cylindrical drum 1 shown in FIG. 6, which is a lower drum 2 connected to a chassis (not shown) of a video tape recorder, and a lower drum 2. It has the upper drum 3 which is provided on the upper part and rotates. This upper drum 3 is lower drum 2
It is provided rotatably with respect to a fixed shaft 10 which is erected at the center of the lower drum 2 and the lower drum 2 and the upper drum 3 are concentric with each other.

Further, a plurality of magnetic heads 4 are provided below the upper drum 3 so as to rotate together with the upper drum 3 about a fixed shaft 10. Further, a lead 6 with which the lower edge portion of the magnetic tape 5 abuts is formed on the outer peripheral surface of the lower drum 2 so as to guide the magnetic tape 5 to be wound around the cylindrical drum 1 in a spiral shape.

The magnetic tape 5 is the cylindrical drum 1.
On the other hand, it is wound by a predetermined wrap angle θ _A. The predetermined wrap angle θ _A is, for example, 221 °, and is wound around the cylindrical drum 1 by a tape guide (not shown).

In such a rotary head device 7, since the magnetic tape 5 is in close contact with the outer peripheral surface of the cylindrical drum 1 and runs along the leads 6, the magnetic tape 5 is accurately moved. Magnetic recording / reproduction can be performed.

However, when the cylindrical drum 1 rotates, an air flow as shown by a chain line S is generated, which sometimes causes a corrugation phenomenon on the magnetic tape 5. The waviness phenomenon of the magnetic tape 5 called tape tapping has a drawback that recording / reproducing / performance of the magnetic head 4 is deteriorated and a clear image cannot be obtained.

Therefore, a magnetic head device 7 shown in FIG. 7 as disclosed in Japanese Patent Laid-Open No. 56-127963 has been proposed. The magnetic head device 7 is provided with a rectifying block 8 for adjusting the air flow discharged in the direction along the outer peripheral surface of the cylindrical drum 1. By the block 8, the thickness of the air layer formed between the cylindrical drum 1 and the magnetic tape 5 is adjusted to prevent the above-mentioned waving phenomenon of the magnetic tape 5.

[0008]

Adjusting the air flow by adding the rectifying component in this way is effective for enhancing the quality of the image, but it increases the number of components and is small and lightweight. It is difficult to proceed with the development, and it is an undesired structure especially when it is adopted in a portable video camera or the like.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a rotary head device that realizes a reduction in size and weight while preventing the corrugation phenomenon of the magnetic tape.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a rotary head device for magnetic recording / reproducing by spirally winding a magnetic tape around a predetermined wrap angle on a cylindrical drum provided with a rotary magnetic head and running the magnetic tape. Yes, a part of the edge of the spirally wound magnetic tape is partially unwound in the axial direction of the cylindrical drum over a predetermined angle from the feeding side of the magnetic tape within the predetermined wrap angle range. It is in a rotating head device that is adapted to run.

Further, according to the present invention, a magnetic recording / recording is performed by providing a cylindrical drum, and winding the magnetic tape in a spiral shape over a predetermined wrap angle θ _A around the cylindrical drum having a rotary magnetic head and running the cylindrical drum. A rotary head device for reproducing, wherein a part of an edge of the magnetic tape wound in a spiral shape is formed on the cylinder from the feeding side of the magnetic tape within a range of the predetermined wrap angle θ _A to a predetermined angle θ _B. Part of the drum in the axial direction is unwound so that the vehicle travels, and the ratio between the predetermined wrap angle θ _A and the predetermined angle θ _B is

Θ _B / θ _A = 0.2 to 0.5

The rotary head device is set so as to substantially satisfy the above condition.

[0014]

According to the present invention, a part of the edge of the magnetic tape is
The magnetic tape in the range of the predetermined wrap angle is configured so that the magnetic tape can be run in the axial direction of the cylindrical drum over a predetermined angle from the feeding side, so that the edge of the magnetic tape corresponding to the predetermined angle has a cylindrical shape. The drum does not touch. Thereby, the airflow generated when the magnetic tape is fed can be made to flow out from between the edge of the magnetic tape corresponding to the predetermined angle and the cylindrical drum.

Further, according to the present invention, the predetermined wrap angle θ
By setting the ratio of _A to the predetermined angle θ _B so as to satisfy the condition of the above mathematical expression 2, the optimum air flow can be adjusted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.
Will be described. Rotary head device 7 shown in the figure
Has a lower drum 2 and a cylindrical drum 1 having an upper drum 3 provided above the lower drum 2. The lower drum 2 is coupled and fixed to a chassis (not shown) of, for example, a video tape recorder incorporated in a video camera.

A fixed shaft 10 (not shown) is erected at the center of the lower drum 2, and the upper drum 3 is rotatably provided on the fixed shaft 10. here,
Both the lower drum 2 and the upper drum 3 are arranged concentrically, and only the upper drum 3 is rotationally driven by a drive motor (not shown) provided inside the upper side of the upper drum 3.

Further, a plurality of rotary magnetic heads 4 are arranged at the lower edge of the upper drum 3 so as to rotate together with the upper drum 3. Further, leads 6 for guiding the running of the magnetic tape 5 are formed on the outer peripheral surface of the lower drum 2, and the magnetic tape 5 is provided with the leads 6.
The lower edge portion is brought into contact with the vehicle so that the vehicle can run.

The magnetic tape 5 has a moving mechanism (not shown) and is spirally wound at a predetermined wrap angle θ _A by a pair of roller guides 8 and 9 which move so as to sandwich the cylindrical drum 1 from the left and right in plan view. It is designed to be used. The magnetic tape 5 runs in the direction of arrow P, for example. At this time, the edge 5a on the upper side of the magnetic tape 5 runs off the upper side of the cylindrical drum 1 from the feeding side of the magnetic tape 5 having the predetermined wrap angle θ _A to the predetermined angle θ _B.

That is, the thickness dimension H of the upper drum 3 in the axial direction
Is shorter than that of the conventional structure, and the edge portion 5a of the magnetic tape 5 indicated by the diagonal lines is removed above the upper drum 3 over the predetermined angle θ _B.

With this configuration, the arrow S
As shown by, the airflow to be entrained with the rotation of the upper drum 3 flows out between the upper drum 3 and the edge portion 5a along the upper surface of the upper drum 3, so that the amount of entrainment of air is reduced. Further, it is possible to prevent the phenomenon of waviness of the magnetic tape 5 in the radial direction of the cylindrical drum 1, and to reduce the disturbance of images during recording / reproduction.

Specifically, when the predetermined wrap angle θ _A is, for example, 221 °, the predetermined angle θ _B is about 44 ° to 111 °.
By setting the angle in the range of °, it is possible to prevent the waving phenomenon of the magnetic tape 5 described above.

That is, the predetermined wrap angle θ _A and the predetermined angle θ
The ratio to _B is

Θ _B / θ _A = 0.2 to 0.5

By setting so that the condition (1) is almost satisfied, the corrugation phenomenon of the magnetic tape 5 can be prevented. Further, as described above, the edge portion 5a of the magnetic tape 5 is arranged above the upper drum 3 so as to be partially unwound in a protruding state. It can be made thinner than the structure. This makes it possible to reduce the size and weight of the rotary head device 7. Further, the rotary head device 7 can be particularly suitable for a portable home video camera or the like.

Next, a second embodiment of the present invention will be described with reference to FIG. The upper edge 3a of the upper drum 3 of the cylindrical drum 1 shown in the figure has, for example, 0.4 to 1.2 mm.
R-shaped chamfer is applied. By performing such chamfering, the magnetic tape 5 and the upper edge portion 3 of the upper drum 3 are
The high pressure contact with a can be prevented. By preventing the high-pressure contact of the magnetic tape 5 with the upper drum 3, damage to the magnetic tape 5 can be reduced and demagnetization can be prevented.

Next, a third embodiment of the present invention will be described with reference to FIGS. 4 and 5. Since the basic structure of the rotary head device 7 is the same as that of the first and second embodiments, it has the same structure. Detailed description of parts will be omitted, and different parts will be described in detail. A lower end (not shown) of the fixed shaft 10 is fixed to the lower drum 2 shown in the figure. The upper drum 3 is rotatably attached to the middle of the fixed shaft 10.

On the upper end side of the fixed shaft 10 located on the upper side of the upper drum 3, a stator base 11 paired with a rotor (not shown) provided inside the upper drum 3 is fixed. A stator (not shown) is fixed to the lower surface of the stator base 11, and a tape retainer 12 is provided at a position described later. The side surface of the tape retainer 12 that comes into contact with the edge 5a of the magnetic tape 5 is formed into an R shape having a radius of, for example, about 4 to 10 mm, and does not prevent the edge 5a of the magnetic tape 5 from sliding. ing. The stator base 11 has a connection terminal 13
Is provided.

The magnetic tape 5 has a structure in which the edge 5a on the feeding side is wound so as to come off above the upper drum 3 over a predetermined angle θ _B. That is, the tape retainer 12 is provided within the range of the predetermined wrap angle θ _A and the predetermined angle θ _B.

The tape holder 12 is positioned within the range of the predetermined wrap angle θ _A of the magnetic tape 5 as described above, and is further arranged at the holding position angle θ _C from the feeding direction of the magnetic tape 5. There is. This pressing position angle θ _C is a ratio with the predetermined lap angle θ _A ,

Θ _C / θ _A = 0.1-0.4

It is set so that the condition (1) is almost satisfied.

Further, the pressing force F applied to the magnetic tape 5 by the tape holder 12 is the ratio of the tensile force T received by the magnetic tape 5 during the reproducing / recording operation to that of a normal video tape recorder.

F / T = 0.03 to 0.2

The conditions are set so as to substantially satisfy the condition. Also, in the 8mm video tape recorder,

F = 0.005N to 0.03N

The conditions are set so as to substantially satisfy the condition. As described above, by providing the tape retainer 12, the envelope and the jitter can be reduced.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the upper drum 3
The magnetic head 4 and the magnetic head 4 are both rotationally driven, but the present invention is not limited to this. For example, the structure described above can be applied to a structure in which a rotary intermediate drum is provided between a fixed lower drum and a fixed upper drum. That is, regardless of the configuration of the cylindrical drum 1,
By providing a part of the feeding-side edge portion 5a of the magnetic tape 5 in the axial direction of the cylindrical drum 1, the air entrained in the axial direction of the cylindrical drum 1 can be discharged by the rotation of the cylindrical drum 1. You can

[0039]

As described above, according to the present invention,
The magnetic tape is spirally wound around the cylindrical drum with a part of the edge of the magnetic tape on the winding side removed in the axial direction of the cylindrical drum. The entrained airflow generated between the and can be discharged in the axial direction of the cylindrical drum.
As a result, the magnetic tape is brought into close contact with the peripheral surface of the cylindrical drum without waviness, so that accurate magnetic recording / reproduction can be performed. Further, since the magnetic tape wound in a spiral shape is configured such that a part of the edge portion thereof is displaced in the axial direction of the cylindrical drum, the axial dimension of the cylindrical drum can be shortened. As a result, it is possible to provide a rotary head device that can be reduced in size and weight.

The predetermined wrap angle θ of the magnetic tape
_A and a part of the edge of the magnetic tape so as to run in the axial direction of the cylindrical drum within the range of the predetermined wrap angle θ _A and over the predetermined angle θ _B from the feeding side of the magnetic tape. To the predetermined lap angle θ _A
By setting the ratio of the predetermined angle θ _B to the predetermined angle θ _B so as to substantially satisfy the condition of the above mathematical expression 2, the waviness phenomenon when the magnetic tape is wound around the cylindrical drum while sufficiently ensuring the magnetic recording / reproducing performance. Can be prevented. further,
Since the axial dimension of the cylindrical drum can be shortened, the size and weight can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a magnetic tape is wound around a rotary head device according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a state in which a magnetic tape is wound around the rotary head device of the first embodiment of the invention in a side view corresponding to a plan view.

FIG. 3 is a side view of a rotary head device according to a second embodiment of the invention.

FIG. 4 is a plan view of a rotary head device according to a third embodiment of the invention.

FIG. 5 is an explanatory view showing a state in which a magnetic tape is wound around the rotary head device of the third embodiment of the invention in a side view corresponding to a plan view.

FIG. 6 is a perspective view illustrating a state in which a winding airflow is generated and a corrugation phenomenon is generated on the magnetic tape in the conventional rotary head device.

FIG. 7 is a perspective view illustrating a conventional rotary head device including a rectifying component for a trapped air flow.

[Explanation of symbols]

1 Cylindrical Drum 4 Magnetic Head 5 Magnetic Tape 5a Edge θ _A Predetermined Lap Angle 7 Rotary Head Device θ _B Predetermined Angle

Claims (2)

[Claims] 1. A rotary head for spirally winding a magnetic tape around a predetermined wrap angle on a cylindrical drum equipped with a rotary magnetic head and running in the winding direction to perform magnetic recording / reproduction on the magnetic tape. In the apparatus, a part of the edge of the magnetic tape wound in a spiral shape is partially unwound in the axial direction of the cylindrical drum within a range of the predetermined wrap angle and over a predetermined angle from the feeding side of the magnetic tape. A rotary head device characterized in that the rotary head device is configured to travel. 2. Magnetic recording / reproduction is performed on this magnetic tape by spirally winding the magnetic tape around a predetermined wrap angle θ _A around a cylindrical drum having a rotary magnetic head and running in this winding direction. In the rotary head device, a part of the edge of the magnetic tape wound in a spiral shape is provided in the axial direction of the cylindrical drum within the range of the predetermined wrap angle θ _A and from the feeding side of the magnetic tape over the predetermined angle θ _B. The vehicle is constructed so as to be partially unwound while traveling, and the ratio of the predetermined wrap angle θ _A and the predetermined angle θ _B is set so that the condition of θ _B / θ _A = 0.2 to 0.5 is substantially satisfied. A rotary head device characterized by being set.