JPH09306065A - Rotary magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary magnetic recording device in which the contact of a magnetic tape to the fixed lower drum or the rotary upper drum is completely excluded and thereby no demagnetization occurs. SOLUTION: This device includes a fixed lower drum 11 having a cylindrical outer peripheral surface, a rotary upper drum 12 which is supported rotatally against this fixed lower drum 11 and has a cylindrical outer peripheral surface matching the outer peripheral surface of the fixed lower drum 11, a plurality of magnetic heads 13a, 13b which are fixed to the peripheral edge of this rotary upper drum 12 on the side of the fixed lower drum 11 and different in height, and a rotating means which drives and rotates the rotary upper drum 12. In this case, the above rotary upper drum 12 is made to have a comparatively large gap 14 in its lower edge so as not to form a window part about the magnetic head 13a at a low position and at the same time to have a comparatively small window part 12a in correspondence with the magnetic head 13b at a high position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary magnetic recording apparatus used in a helical scan type magnetic recording / reproducing apparatus such as a VTR and a DAT.

[0002]

2. Description of the Related Art Conventionally, a rotary magnetic recording device is shown in FIG.
It is configured as shown in FIG. That is, in FIG. 4, the rotary magnetic recording apparatus 1 is composed of a fixed lower drum 2 and a rotating upper drum 3 each having a cylindrical outer peripheral surface aligned with each other. The magnetic head 4 can be attached.

The fixed lower drum 2 is fixedly arranged, and a tape lead 2a extending obliquely in a helical shape is formed on the outer peripheral surface thereof. This tape lead 2a
The magnetic tape (not shown) is guided by the side edges of the magnetic tape. The rotating upper drum 3 is rotatably supported by the fixed lower drum 2 around a central axis, and is rotationally driven at high speed by a motor (not shown). Further, the rotary upper drum 3 is provided with a notch in a part of its outer peripheral surface so as to have a so-called window 3a in the region of the magnetic head 4 as shown in FIG.

According to the rotary magnetic recording apparatus 1 having such a structure, the rotary upper drum 3 is rotationally driven at a high speed, and
The magnetic tape runs along the tape lead 2a of the fixed lower drum 2. As a result, the magnetic head 4 provided on the rotating drum 3 moves obliquely with respect to the magnetic tape to perform recording or reproduction.

At this time, since the rotary upper drum 3 is rotating at a high speed, an air flow is drawn between the rotary upper drum 3 and the magnetic tape, and the outer peripheral surface of the rotary upper drum 3 and the magnetic tape are separated from each other. In between, a thin air layer called an air film will be formed. Therefore, in the above-mentioned cross section in the circumferential direction of the window 3a, as shown in FIG. 6, the airflow will flow so as to be sucked into the window 3a,
The air film becomes thin. As a result, the magnetic tape T is urged in a direction closer to the magnetic head 4 projecting from the window portion 3a to the outer side in the radial direction of the rotary drum 3, and thus the magnetic head 4 of the magnetic tape T. Will be contacted more reliably.

By the way, in the rotary magnetic recording apparatus 1 having such a structure, if the window 3a is large, the magnetic tape T
The magnetic tape T may come into contact with the side edge of the rear window portion 3a in the traveling direction A of the rotating upper drum 3 as shown in the drawing. In this case, there is a possibility that the data recorded on the magnetic tape T may be lost, that is, there is a possibility of so-called demagnetization, which is a serious problem in terms of reliability of magnetic recording. Therefore, the above-mentioned demagnetization is reduced by performing an additional process called so-called buffing on the rear side edge of the window 3a. Here, the buffing means that a disc-shaped felt is spun with an abrasive and is rotated, and a portion to be buffed is brought into contact with the felt, whereby the rear side edge of the window 3a is rounded.
It is to process it into a shape.

However, since such additional work of buffing is almost manually performed, a relatively large variation occurs in the finish, and there is a problem that it is difficult to obtain a certain quality. It was On the other hand, it is conceivable to make the window portion 3a as small as possible, but if the window portion 3a is made small, it becomes necessary to increase the mounting accuracy of the magnetic head 4 on the rotary drum 3. Therefore, the workability of mounting the magnetic head is deteriorated, and the magnetic head 4 is frequently damaged during the work, resulting in an increase in cost. However, there is a problem that the buffing process described above cannot be omitted in order to reliably prevent demagnetization of the tape.

Therefore, as shown in FIG. 7, there is also known a rotary magnetic recording apparatus having no window portion 3a as described above. In FIG. 7, in the rotary magnetic recording device 5, the lower edge of the rotary upper drum 3 is fixed to the fixed lower drum 3 so that all the magnetic heads 4 do not come into contact with the rotary upper drum 3 instead of providing the above-mentioned window 3a. A gap 6 having a predetermined distance d is provided with respect to the upper edge of 2. According to the rotary magnetic recording apparatus 5 having such a configuration, in the axial cross section near the magnetic head 4, as shown in FIG. 9, the air film is sucked into the gap. As a result, the magnetic tape T approaches the magnetic head 4 and can sufficiently contact the magnetic head 4. In this case, demagnetization due to the contact of the magnetic tape T with the side edge of the window 3a unlike the case of the rotary magnetic recording apparatus 1 having the window 3a does not occur, so that the buffing process is unnecessary and the cost is reduced. Will be reduced.

[0009]

However, if the gap 6 is large, the magnetic tape T is largely drawn into the gap 6, and the distance from the fixed lower drum 2 is lost, as shown in FIG. In addition, there is a possibility that the magnetic tape T may come into contact with the fixed lower drum 2, which may cause the above-described demagnetization.

In view of the above points, the present invention provides a rotary magnetic recording apparatus in which the contact of a magnetic tape with a fixed lower drum or a rotating upper drum is reliably eliminated and demagnetization does not occur. Has an aim.

[0011]

According to the present invention, the above object is to provide a fixed lower drum having a cylindrical outer peripheral surface and an outer periphery of the fixed lower drum which is rotatably supported with respect to the fixed lower drum. A rotating upper drum having a cylindrical outer peripheral surface aligned with the surface, and a plurality of magnetic heads having different heights attached to the peripheral edge of the rotating upper drum on the fixed lower drum side,
And a rotating means for rotating the rotating upper drum.
The rotating upper drum and the rotating lower drum have a gap with respect to a region where the magnetic head at the lower position is provided, and are small enough to correspond to the magnetic head at the higher position so that the running tape does not hit the side wall. This is achieved by a rotating magnetic recording device having a window.

According to the above construction, the upper rotating drum is arranged so as to have a gap so as to include the magnetic head at a lower position with respect to the lower fixed drum. For this reason,
No window is defined for this lower magnetic head. Therefore, the side edge on the rear side of the window portion does not come into contact with the magnetic tape as the rotary drum is driven to rotate, and the occurrence of demagnetization is eliminated. Further, regarding the magnetic head at a high position, a window is formed in addition to the above-mentioned gap. However, since this window is relatively small, the window behind the window is rotated as the upper rotary drum is driven. The side edges do not come into contact with the magnetic tape and the occurrence of demagnetization is eliminated. As a result, it is not necessary to perform buffing on the side edge of the window as in the conventional case, and the cost is reduced.

If the gap between the lower edge of the rotating upper drum and the upper edge of the fixed lower drum is selected so that optimum contact between the magnetic tape and the magnetic head is obtained,
The magnetic tape does not come into contact with the upper edge of the fixed lower drum, and demagnetization due to contact with the fixed lower drum is also eliminated.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
The embodiments described below are preferable specific examples of the present invention, and therefore, various technically preferable limitations are given,
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 shows an embodiment of a rotary magnetic recording apparatus according to the present invention. In FIG. 1, the rotary magnetic recording device 10 is composed of a fixed lower drum 11 and a rotating upper drum 12, and a plurality of magnetic heads 13 having different heights are provided on the periphery of the rotating upper drum 12 (see FIG. 2). Can be attached.

The fixed lower drum 11 is fixedly arranged, and a tape lead 11a extending obliquely in a helical shape is formed on a cylindrical outer peripheral surface thereof, and the tape lead 11a forms a magnetic tape (see FIG. It is designed to run while guiding the side edge of (not shown).

The rotating upper drum 12 has a cylindrical outer peripheral surface so as to be aligned with the outer peripheral surface of the fixed lower drum 11, and rotates about the central axis with respect to the fixed lower drum 11. It is supported so that it can be rotationally driven at high speed by a motor (not shown). Further, the rotating upper drum 12 is arranged so that its lower edge defines a gap 14 of a predetermined distance D with respect to the upper edge of the fixed lower drum 11. The gap D is selected so that the gap D is optimal for the amount of air film formed between the magnetic tape and the rotating upper drum 12 and the fixed lower drum 11.

The rotating upper drum 12 has a fixed lower drum 11 so that the amount of the air film between the drums 11 and 12 and the magnetic tape falls within the range of, for example, several microns to 20,30 microns. Will be assembled against. Here, as shown in FIG. 2, the gap 14 is designed such that the magnetic head 13a is completely within the gap 14 for the magnetic head 13a at the lower position, but is not for the magnetic head 13b at the higher position. Since the magnetic head 13b interferes with the lower edge of the rotating upper drum 12, a cutout is provided in the lower edge of the rotating upper drum 12 at this interfering portion, so that the relatively small window 12a is formed.
Is formed.

The rotary magnetic recording apparatus 10 according to the present embodiment.
Is configured as described above, the rotating upper drum 12 is rotationally driven at a high speed, and the magnetic tape runs along the tape lead 11a of the fixed lower drum 11. As a result, the magnetic head 13 (13a, 13b) provided on the rotating drum 12 moves obliquely with respect to the magnetic tape to perform recording or reproduction.

At this time, since the rotary upper drum 12 is rotating at a high speed, an air flow is drawn between the rotary upper drum 12 and the magnetic tape, and the outer peripheral surface of the rotary upper drum 12 and the magnetic tape are separated from each other. In between, a thin air layer called an air film will be formed.

Therefore, with respect to the magnetic head 13b at the high position, the air flow will flow so as to be sucked into the window portion 12a, and the air film becomes thin. As a result, the magnetic tape T is urged in a direction closer to the magnetic head 13b protruding from the window portion 12a to the outer side in the radial direction of the rotary drum 12, and thus the magnetic head 4 of the magnetic tape T. Will be contacted more reliably. At this time, the window portion 12a is formed small unlike the window portion 3a in the conventional rotary magnetic recording apparatus 1, so that the magnetic tape does not come into contact with the rear side edge of the window portion 12a. Therefore, the occurrence of demagnetization is eliminated. Therefore, with respect to the side edge of the window 12a,
Buffing is not required, and the cost is reduced.

With respect to the magnetic head 13a at the lower position, the air flow flows so as to be sucked into the gap 14. At this time, the gap D between the gap 14 and the magnetic tape T is as shown in FIG. Since the amount of air film between each drum 11 and 12 is selected to be optimum, the magnetic tape T does not come into contact with the upper edge of the fixed lower drum 11 and therefore the demagnetization is prevented. Occurrence will be eliminated.

In the above-described embodiment, the rotary magnetic recording apparatus 10 provided with the two magnetic heads 13a and 13b has been described, but the present invention is not limited to this, and a plurality of magnetic heads having different heights are provided. It is obvious that the present invention can be applied to the rotating magnetic recording device.

[0024]

As described above, according to the present invention, the contact of the magnetic tape with the fixed lower drum or the rotating upper drum is surely eliminated, and the demagnetization is prevented from occurring. Can be provided.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a main part of an embodiment of a rotary magnetic recording apparatus according to the present invention.

FIG. 2 is an enlarged front view of a magnetic head portion of the rotary magnetic recording apparatus of FIG.

3 is a schematic vertical sectional view showing a contact state between a magnetic tape and each drum in the rotary magnetic recording apparatus of FIG.

FIG. 4 is a schematic perspective view showing a main part of an example of a conventional rotary magnetic recording device with a window.

5 is an enlarged front view of a magnetic head portion of the rotary magnetic recording apparatus of FIG.

6 is a schematic cross-sectional view showing a contact state between a magnetic tape and a magnetic head in the rotary magnetic recording apparatus of FIG.

FIG. 7 is a schematic perspective view showing a main part of an example of a conventional rotary magnetic recording apparatus without a window.

8 is an enlarged front view of a magnetic head portion of the rotary magnetic recording apparatus of FIG.

9 is a schematic vertical sectional view showing a contact state between a magnetic tape and each drum in the rotary magnetic recording apparatus of FIG.

[Explanation of symbols]

10 ... Rotating magnetic recording device, 11 ... Fixed lower drum, 12 ... Rotating upper drum, 12a ... Window part, 13
... magnetic head, 13a ... low magnetic head, 13b ... high magnetic head, 14 ... gap.

Claims (2)

[Claims] 1. A fixed lower drum having a cylindrical outer peripheral surface, and a rotating upper drum having a cylindrical outer peripheral surface rotatably supported with respect to the fixed lower drum and aligned with the outer peripheral surface of the fixed lower drum. A plurality of magnetic heads of different heights attached to the peripheral edge of the rotating upper drum on the fixed lower drum side, and rotating means for rotatingly driving the rotating upper drum. The lower drum has a gap with respect to a region where the magnetic head at the lower position is provided, and has a window portion corresponding to the magnetic head at the higher position so that the running tape does not hit the side wall. Characteristic rotary magnetic recording device. 2. The gap between the lower edge of the rotating upper drum and the upper edge of the fixed lower drum is selected so as to obtain an optimum contact state between the magnetic tape and the magnetic head. The rotating magnetic recording apparatus according to claim 1, wherein the rotating magnetic recording apparatus is a magnetic recording apparatus.