JPH04341962A - Rotary head drum - Google Patents

Abstract

PURPOSE:To attain the improvement of a recording/reproducing characteristic and the reduction of the damage of a tape by inserting a fixed cylinder over the outer circumference of a rotary drum so as to be aligned with the same axis as the rotary drum and forming a tape lead on the upper end surface so as to form an air film between the circumferential surface of the drum and the tape. CONSTITUTION:Plural rotary heads 3 are fitted at the outer circumference of the upper end side 14a of a rotary drum 14 and a cylindrical fixed cylinder 15 is inserted over the outer circumference of a lower end side 14b so as to be aligned with the same axis and a tape lead 4 of a helical angle alpha is formed at its upper end surface, and recording/reproduction is performed by a helical scanning system. Thus, the whole surface of the magnetic tape 5 can be faced to the drum 14 exending over a whole area from a drum entrance 12 to an exit 13. Then, an air flow due to the rotation of the drum 14 acts to the whole width of the tape 5, and in addition, to the whole area between the entrance 12 and the exit 13. Then, the air film 18 of thickness T2 uniform extending over the whole area is formed. Accordingly, the part of the head 3 excessively protruding against the tape 5 can be eliminated, and the damage of the tape can be reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head drum suitable for application to helical scan type magnetic recording and reproducing devices such as VTRs (video tape recorders) and DATs (digital audio tape recorders).

0002

2. Description of the Related Art Hitherto, in helical scan type magnetic recording and reproducing apparatuses such as VTRs and DATs, a rotary head drum of an upper drum rotation type has been most commonly used. The rotary head drum of this upper drum rotation method is shown in (A) in Figure 2.
As shown in (B), a rotating drum 1 and a fixed drum 2 having the same diameter are arranged on the same axis. A plurality of rotating heads 3, which are magnetic heads, are attached to the outer periphery of the rotating drum 1, and a helical tape lead 4 is formed on the outer periphery of the fixed drum 2. And magnetic tape 5
The magnetic tape 5 is guided by an entrance guide 6 and an exit guide 7 and wound helically around the outer periphery of the rotary drum 1 and the fixed drum 2, spanning both of them, and the magnetic tape 5 is run at a constant speed along the tape lead 4. Then, the rotating drum 1 is driven to rotate at high speed, for example, in the direction of the arrow a, by the spindle 9 of the spindle motor 8 attached to the fixed drum 2, and the magnetic tape 5 is recorded and/or reproduced by a helical scan method using the plurality of rotating heads 3. It is configured to do so.

[0003] In this upper drum rotation type rotary head drum, due to the high speed rotation of the rotary drum 1, an air film 10 is formed between the drum circumferential surface and the magnetic tape 5, as shown by diagonal lines in FIG. 2(B). This has the feature that the frictional resistance of the magnetic tape 5 against the drum circumferential surface can be reduced.

0004

[Problems to be Solved by the Invention] However, in the conventional upper drum rotation type rotary head drum, as shown by diagonal lines in FIG.
Since the width W1 of the air film 10 gradually decreases from the drum inlet 12 to the drum outlet 13 in a triangular shape, the thickness T1 of the air film 10 also gradually decreases from the drum inlet 12 to the drum outlet 13. It is changing to

For this reason, the amount of protrusion of the rotary head 3 relative to the magnetic tape 5 is not constant, and on the side of the drum entrance 12 where the air film 10 is thickest, the rotary head 3 protrudes insufficiently relative to the magnetic tape 5, and the air film On the drum exit 13 side, where 10 is the thinnest, the rotary head 3 protrudes too much from the magnetic tape 5. Therefore, it is not possible to make the contact (contact state) of the rotary head 3 against the magnetic tape 5 uniform over the entire area from the drum entrance 12 to the drum exit 13, thereby improving recording and/or reproducing characteristics and reducing tape damage. There was a problem that it was difficult to achieve both.

The present invention has been made to solve the above problem, and is to create a thick and uniform air film between the drum peripheral surface and the magnetic tape in the entire area from the drum entrance to the drum exit. The object of the present invention is to provide a rotary head drum that can form a rotary head drum.

[0007]

[Means for Solving the Problems] A rotary head drum of the present invention for achieving the above object includes a rotary drum having a rotary head provided on the outer periphery, and a rotary head inserted coaxially into the outer periphery of the rotary drum. , and a fixed cylinder having a tape lead formed on its upper end surface.

[0008]

[Function] The rotating head drum of the present invention configured as described above can ensure that the width of the facing surfaces of the rotating drum and the magnetic tape is constant over the entire area from the drum entrance to the drum exit. A thick and uniform air film can be formed between the drum circumferential surface and the magnetic tape over the entire area.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary head drum to which the present invention is applied will be described below with reference to FIGS. 1A and 1B. Note that the same reference numerals are given to the same structural parts as in FIGS. 2A and 2B, and redundant explanation will be omitted.

This rotating head drum has a plurality of rotating heads 3 attached to the outer periphery of the upper end side 14a of a rotating drum 14 having a long shaft length L, and a cylindrical fixed cylinder 15 attached to the outer periphery of the lower end side 14b of the rotating drum 14. They are inserted coaxially, and a tape lead 4 having a helical angle α is formed on the upper end surface of this fixed cylinder 15. Note that the rotating drum 14 is connected to the fixed cylinder 1.
The rotary drum 14 is rotatably held in a fixed cylinder 15 by a bearing 16 such as a fluid bearing or a ball bearing.
It is configured to be rotationally driven in the direction of arrow a by a spindle 9 of a spindle motor 8 attached to the lower end of.

[0011] This rotary head drum guides the magnetic tape 5 by an inlet guide 6 and an outlet guide 7 and wraps it helically around the outer periphery of the rotary drum 14 only.
While the magnetic tape 5 is running at a constant speed along the tape lead 4, the spindle 9 of the spindle motor 8 drives the rotary drum 14 to rotate at high speed in the direction of arrow a, and the magnetic tape 5 is helically driven by the plurality of rotary heads 3. Recording and/or reproduction is performed using a scanning method.

Therefore, according to this rotating head drum,
As shown by diagonal lines in (A) of FIG. 1, the width W2 of the facing surface 17 between the rotating drum 14 and the magnetic tape 5 can be maintained constant (same as the tape width) over the entire area from the drum entrance 12 to the drum exit 13. . In other words, the entire surface of the magnetic tape 5 can be opposed to the rotating drum 14 over the entire area from the drum entrance 12 to the drum exit 13.

As a result, the arrow a on the circumferential surface of the rotating drum 14
Since the air flow in the direction can be applied to the entire width of the magnetic tape 5 in the entire area from the drum inlet 12 to the drum outlet 13, as shown by diagonal lines in FIG. In the entire area up to the drum exit 13, a uniform air film 18 with a thick thickness T2 (ie, T2>T1) can be formed between the circumferential surface of the rotating drum 14 and the magnetic tape 5. Since the thickness T2 of the air film 18 is thick and uniform, the contact of the rotary head 3 against the magnetic tape 5 can be made uniform over the entire area from the drum entrance 12 to the drum exit 13, and the magnetic An optimal spacing of 0.05 μm or less between the tape 5 and the rotary head 3 can be stably ensured over the above range. Furthermore, since the excessive protrusion of the rotary head 3 relative to the magnetic tape 5 can be eliminated, damage to the tape can be reduced.

Although one embodiment of the present invention has been described above,
The present invention is not limited to the above embodiments, and various modifications can be made based on the technical idea of the present invention.

[0015]

[Effects of the Invention] Since the rotary head drum of the present invention is constructed as described above, it has the following effects.

[0016] The width of the facing surfaces of the rotating drum and the magnetic tape can be maintained constant over the entire area from the drum entrance to the drum exit, and the width between the drum peripheral surface and the magnetic tape can be maintained constant over the entire area from the drum entrance to the drum exit. thickly,
Furthermore, since a uniform air film can be formed, the contact of the rotating head against the magnetic tape can be made uniform over the entire area from the drum entrance to the drum exit. Therefore, it is possible to stably secure an optimum spacing between the magnetic tape and the rotary head, thereby achieving both improved recording and/or reproducing characteristics and reduced tape damage.

[Brief explanation of the drawing]

FIG. 1 is a side view and a plan view of a rotary head drum according to an embodiment of the present invention.

FIG. 2 is a side view and a plan view of a conventional rotary head drum.

[Explanation of symbols]

3 Rotating head 4 Tape lead 5 Magnetic tape 12 Drum inlet 13 Drum outlet 14 Rotating drum 15 Fixed cylinder 17 Opposing surface 18 between the rotating drum and magnetic tape
air film

Claims (1)

[Claims] 1. A rotary head drum comprising: a rotary drum having a rotary head disposed on its outer periphery; and a fixed cylinder inserted coaxially into the outer periphery of the rotary drum and having a tape lead formed on its upper end surface.