JPH0773551A - Rotary head device - Google Patents

Abstract

PURPOSE:To obtain the stability for tape running by uniformizing the floating hight of the magnetic tape against a rotary cylinder and increasing the control force of a tape running system. CONSTITUTION:In a specified central angle theta deg. of a fixed cylinder 2, the magnetic tape T is helically wound on the outside cylindrical surface and guided for running, then the rotary cylinder 1 is arranged coaxially with this fixed cylinder keeping a narrow gap 3 with the end surface thereof and rotated while winding the magnetic tape on the outside cylindrical surface common with the fixed cylinder, and a magnetic head 7 to record/reproduce for the magnetic tape is mounted on the outside cylindrical surface of the rotary cylinder. The rotary cylinder is formed to the tapered state so that the external size is gradually made smaller against the fixed cylinder, and plural V-shaped grooves are provided on the outside cylindrical surface of the rotary cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drum device used in a magnetic recording / reproducing apparatus such as a video tape recorder.

[0002]

2. Description of the Related Art A magnetic recording / reproducing apparatus such as a video tape recorder requires a rotary head device having a head for recording or reproducing directly on a magnetic tape.

FIG. 7 is a partially cutaway view of a conventional rotary head device. This rotary head device basically comprises a fixed cylinder A on the lower side and a rotary cylinder B on the upper side coaxially connected to each other.

In the fixed cylinder A, a tape running guide guide m is provided in a helical shape on the outer peripheral cylindrical surface, and an end edge of the magnetic tape T is engaged between a predetermined central angle of the guide guide to run the tape. invite.

The magnetic tape T is also wound around the outer peripheral cylindrical surface of the rotary cylinder B, which is common to the fixed cylinder A, and comes into sliding contact with the rotary cylinder with a relative speed difference. A magnetic head (not shown) is attached to the outer peripheral cylindrical surface of the rotary cylinder B, and recording / reproducing is performed on the magnetic tape T.

[0006]

By the way, in the rotary cylinder B, a plurality of V grooves d are formed along the outer peripheral surface thereof.
... are provided at predetermined intervals. Each V groove d controls the amount of air that is caught between the magnetic tape T and the rotating cylinder B in a state where the magnetic tape T is in contact with the magnetic tape T, so that the tape floats more reliably.

Due to the presence of the V groove d, theoretically, the magnetic tape T is levitated and guided by an even amount over the entire winding range of the rotary cylinder B. However, in reality, at the entrance portion where the magnetic tape T starts to come into contact with the device, the tape is inclined as shown in the figure.

This is proved from the actual measurement data shown in FIG. That is, the displacement from the surface is almost zero in the vicinity of the outlet where the tape winding angle is 150 ° with reference to the inlet where the magnetic tape T contacts the cylinders A and B. A large inclination occurs near the entrance which is 0 °. According to the data, the displacement from the surface is about 30 μm floating at the upper end of the rotary cylinder B, and about 10 μm is floating at the lower end.

As shown in FIG. 7 again, especially at the entrance portion, the magnetic tape T has a large floating amount at the upper end portion compared to the lower end portion and is in an inclined state, so that the regulation force of the tape running system becomes weak. Tape running becomes a cause of fluctuation.

In particular, the HD whose development has been accelerated in recent years
In (Hi-Vision: High Definition), in order to increase the recording density, measures such as increasing the cylinder diameter and increasing the cylinder rotation speed are taken, but in both cases, the tape and head (cylinder surface) The relative speed with Therefore, the flying height of the magnetic tape T at the entrance portion is generally increased, and the instability of the tape running may be expanded. Therefore, immediate countermeasures are desired to be adopted.

On the other hand, the rotating cylinder B is constantly rotating at a high speed, and the magnetic tape T is guided to the rotating cylinder B at a low peripheral speed by another driving mechanism. Due to the large speed difference between the cylinder B and the tape T and the presence of the V groove d, air is entrapped between them and the tape floats with an air layer interposed.

On the other hand, the fixed cylinder A is literally fixed, and there is no condition for entraining air with the magnetic tape T which is guided at a low speed. Since the air layer is not present unlike the rotating cylinder B, the friction with the tape is large.

The fixed cylinder A is provided with a tape running guide m in a helical shape, and the tape T is guided along this guide. That is, with reference to the width direction of the tape T, the width of contact with the fixed cylinder A is extremely small at the entrance portion where the tape travel guide guide m starts to contact, but the contact width gradually increases and the separation occurs. The outlet portion, which is the portion to be contacted, makes contact with the tape in the width direction.

As described above, at the outlet of the tape running guide m, the magnetic tape T contacts and rubs against the fixed cylinder A over the entire width direction. As a result, slipping of the tape T, frictional vibration, etc. are likely to occur, the tape running speed is not stable, and a screen flickering phenomenon called jitter occurs.

As a countermeasure against this, for example, Japanese Patent Laid-Open No. 4-25
As disclosed in Japanese Unexamined Patent Publication No. 2412, there is proposed one having a protrusion member having a protrusion in the radial direction of the fixed cylinder and a means for changing the protrusion amount. Alternatively, the surface roughness of the fixed cylinder is controlled to achieve tape running stability and low tape damage.

However, with the means using the projection and the projection member, the tape is floated only at the portion where these are provided, and the tape running stability is obtained only in an extremely narrow range.

Further, in the control of the surface roughness of the fixed cylinder, the contact state between the cylinder surface and the tape is slightly improved, and a remarkable effect cannot be expected. The present invention has been made in view of the above-mentioned circumstances, and a first object of the present invention is to make the flying height of the magnetic tape uniform with respect to the rotating cylinder to increase the restriction force of the tape traveling system, An object of the present invention is to provide a rotary head device that can obtain running stability.

A second object is to form a proper air layer between the fixed cylinder and the magnetic tape, thereby reducing the friction resistance to reduce the jitter and reduce the tape damage. Is to provide.

[0019]

In order to solve the above-mentioned problems, in the rotary head device of the first invention, a magnetic tape is helically wound between the fixed cylinder at predetermined center angles and on the outer peripheral cylindrical surface. The traveling cylinder is guided, and the rotary cylinder is coaxially arranged with a small gap from the fixed cylinder end face, and the magnetic tape is wound around the outer peripheral cylindrical surface common to the fixed cylinder to rotate the outer peripheral cylindrical surface of the rotary cylinder. To
Attach a magnetic head for recording and reproducing on a magnetic tape,
The rotary cylinder has an outer shape tapered so as to become gradually smaller than the fixed cylinder, and has a plurality of V-shapes.
The groove is provided in the circumferential direction.

The rotary head device of the second invention comprises a fixed cylinder, a rotary cylinder, and a magnetic head for recording / reproducing on a magnetic tape, and a tape running guide is helically provided on the outer peripheral cylindrical surface of the fixed cylinder. A plurality of openings with a gap between each other on the end surface of the fixed cylinder facing the gap with the rotary cylinder, and a plurality of air grooves, one end of which is the opening. It is characterized in that they are communicated with each other, and are provided on the outer peripheral cylindrical surface of the fixed cylinder in parallel with the tape running guide, and the positions of the other ends of the two are aligned along the same angle.

A rotary head device according to a third aspect of the present invention comprises a fixed cylinder, a rotary cylinder, and a magnetic head for recording / reproducing on / from a magnetic tape. The rotary cylinder has an outer diameter gradually increasing with respect to the fixed cylinder. It is formed in a taper shape so that it becomes smaller, and a plurality of V
A groove is provided, and a tape running guide is provided in a helical shape on the outer peripheral cylindrical surface of the fixed cylinder to guide running of the magnetic tape, and a gap is formed between the fixed cylinder end surface facing the gap with the rotating cylinder. A plurality of openings are provided, one end communicates with the opening, and a plurality of air grooves are provided parallel to the tape guide guide on the outer peripheral cylindrical surface of the fixed cylinder, and the positions of the other ends of the two are arranged. The feature is that they are aligned along the same corner.

[0022]

According to the rotary head device of the first aspect of the invention, air is guided to the plurality of V grooves provided on the outer peripheral cylindrical surface of the rotary cylinder to float the magnetic tape. As a result, the floating amount on the end side opposite to this becomes large, and the tape is in a tilted state.

However, since the rotating cylinder is formed in a taper shape so that its outer diameter becomes gradually smaller than that of the fixed cylinder, it has a cylindrical shape that follows the inclination of the tape, so that the flying height of the tape can be made uniform. obtain.

According to the rotary head device of the second invention, as the rotary cylinder rotates, the pressure in the gap between the rotary cylinder and the fixed cylinder increases, and air is guided to the opening of the end face of the fixed cylinder. It is guided to the air groove and an air layer is formed between the magnetic tape and the magnetic tape.

From aligning the air grooves along the same corner, all the air grooves are aligned near the tape outlet,
A uniform air layer is formed in the width direction of the tape. According to the rotary head device of the third aspect of the present invention, the rotary cylinder is formed in a taper shape along the inclination of the magnetic tape, and in particular, the flying height of the tape at the entrance portion is made uniform, and the fixed cylinder and the magnetic tape are combined. By interposing an air layer between them, the friction with the tape is reduced, and the tape is surely floated especially at the outlet.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, in the rotary head device, the rotary cylinder 1 is on the upper side and the fixed cylinder 2 is on the lower side, and the rotary head devices are continuously arranged coaxially with each other with a narrow gap 3 therebetween. It becomes.

The rotary cylinder 1 is mechanically connected to a drive source (not shown) and is rotationally driven at high speed. The fixed cylinder 2 is literally fixed, and a step portion is obliquely provided on the outer peripheral cylindrical surface to form a tape running guide 4.

The magnetic tape T is obliquely guided so as to face the tape running guide 4, and the lower edge of the magnetic tape T is engaged with the guide to guide the running. However, the magnetic tape T is guided to travel only between the predetermined central angles θ ° of the cylinders 1 and 2 and helically wound around the outer peripheral cylindrical surface.

To explain further, at the entrance portion 5 where the magnetic tape T starts to come into contact with the rotary head device, the magnetic tape T comes into contact with the rotary cylinder 1 and comes into contact with the fixed cylinder 2 over most of the width direction of the tape. There are very few parts.

Along the traveling direction of the magnetic tape T, the portion in contact with the rotary cylinder 1 gradually decreases, and conversely, the portion in contact with the fixed cylinder 2 increases. At a portion immediately before the magnetic tape T is separated from the device, that is, at the outlet portion 6, the magnetic tape T contacts the fixed cylinder 2 in the width direction of the tape,
There is almost no part that contacts the rotating cylinder 1.

At least two magnetic heads 7 for recording and reproducing (only one is shown) are attached to the outer peripheral cylindrical surface of the rotary cylinder 1 for recording / reproducing on / from the magnetic tape T.

Further, a plurality of V grooves 8 ... Are provided on the outer peripheral cylindrical surface of the rotary cylinder 1 at predetermined intervals in the axial direction. The rotary cylinder 1 is formed in a tapered shape with a taper angle α ° so that the outer diameter of the rotary cylinder 1 becomes gradually smaller than that of the fixed cylinder 2.

In practice, the taper size is set so that the upper outer diameter of the rotary cylinder 1 is larger than the lower outer diameter by about 20 μm. On the other hand, as shown in FIGS. 3 and 4, the fixed cylinder 2 is provided with a plurality of openings 9 ... at intervals on the upper side end surface which is the end surface facing the clearance with the rotary cylinder 1. .

The positions of these openings 9 ...
Based on the above, the tape winding angle may be set in the range of 90 ° to 180 °. One end of the air groove 10 is communicated with each opening 9. Each air groove 10 is provided on the outer peripheral surface of the fixed cylinder 2 in parallel with the tape running guide 4, and the positions of the other ends are aligned along the same angle θa °.

That is, the positions of one end of the air groove 10 are different from each other, but the positions of the other ends are all aligned on the same axis. Actually, the position of the other end of the air groove 10 is preferably located immediately before the outlet 6 where the magnetic tape T separates from the fixed cylinder 2.

Thus, the magnetic tape T guided by the traveling system is obliquely guided to the rotary head device.
In the device, the rotary cylinder 1 rotates at high speed,
The magnetic head 7 attached here moves at high speed.
The fixed cylinder 2 is naturally in a fixed state, and the lower end of the magnetic tape T engages with the tape running guide 4.

At the entrance portion 5 of the apparatus, most of the magnetic tape T contacts the rotating cylinder 1 over the width direction of the tape, and the contact portion with the fixed cylinder 2 is very small. Along the traveling direction of the magnetic tape T, the portion contacting the rotary cylinder 1 gradually decreases, and conversely, the portion contacting the fixed cylinder 2 increases.

At the outlet portion 6 which is a portion immediately before the magnetic tape T is separated from the apparatus, the tape is in contact with the fixed cylinder 2 in the width direction and there is almost no contact with the rotary cylinder 1.

Due to the high speed rotation of the rotary cylinder 1, air is guided to the plurality of V grooves 8 provided on the outer peripheral cylindrical surface, an air layer is formed between the air V and the magnetic tape T, and the tape is floated.

In other words, as long as the magnetic tape T is in sliding contact with the rotary cylinder 1, the V groove 8 forms an air layer between the tape and the cylinder, and the tape is floated. As shown in FIG. 5, in particular, at the entrance portion 5, the magnetic tape T follows the rotating cylinder 1 almost all over the width direction, but the force of pushing down the tape, so-called lead pressure becomes strong, and the lower end portion of the tape The floating amount on the upper end side is larger than that on the upper side, and it is inclined.

However, the rotary cylinder 1 is formed in a taper shape with a taper angle α °, the outer diameter of which is gradually smaller than that of the fixed cylinder 2. That is, the rotary cylinder 1 has a shape that follows the inclination of the magnetic tape T in advance, and the floating amount of the tape with respect to the cylinder is uniform.

FIG. 6 shows actual measurement data in an apparatus having the rotary cylinder 1 having such a structure. The tape wrap angle is 0 compared to the previously explained structure.
It can be seen that the amount of displacement from the surface decreases at the position of °. That is, a uniform flying height at the tape inlet portion 5 can be obtained.

In particular, the relative speed between the rotary cylinder and the magnetic head such as HD (high-definition) becomes high, which is effective for a rotary head device compatible with high density recording. on the other hand,
As the rotating cylinder 1 rotates at high speed, the pressure in the gap 3 between the rotating cylinder 1 and the fixed cylinder 2 increases, and air is guided to the plurality of openings 9 ... Provided on the end surface of the fixed cylinder 2.

The air is introduced into the air grooves 10 which communicate with the respective openings 9. These air grooves 10 ... The other end terminal portions are positions immediately before the outlet portion 6 where the magnetic tape T separates from the fixed cylinder 2, so that air is sealed in the grooves.

That is, an air layer is formed between the fixed cylinder 2 and the magnetic tape T wound around and guided by the cylinder. Since the magnetic tape T is guided to run obliquely, the tape sequentially faces each air groove 10, and the number of the facing grooves increases. All the air grooves 10 are aligned at the other end of the groove and are in sliding contact with the fixed cylinder 2 in the width direction of the tape, so that a uniform air layer is formed with the tape.

Due to the presence of this air layer, the frictional resistance of the magnetic tape T to the fixed cylinder 2 is significantly reduced,
The tape running property is stable. Therefore, the frictional force is reduced and the tape damage is reduced.

In the above embodiment, the rotary cylinder 1 having the V groove 8 and formed in a tapered shape,
The rotary head device provided with both the opening 9 on the end surface and the fixed cylinder 2 having the air groove 10 communicating with the opening on the outer peripheral surface has been described, but the present invention is not limited to this.

For example, the rotary head apparatus may be provided with the V-shaped groove 8 and the rotary cylinder 1 formed in a tapered shape, or the opening 9 and the air groove 10 may be provided.
It may be a rotary head device including a fixed cylinder 2 provided with. That is, various modifications can be made without departing from the scope of the present invention.

[0049]

As described above, the rotary head device of the first invention is formed in a taper shape so that its outer shape becomes gradually smaller than that of the fixed cylinder, and a plurality of V grooves are provided on the outer peripheral cylindrical surface. Since the rotating cylinder is provided, the floating amount of the magnetic tape with respect to the rotating cylinder is made uniform, the regulation force of the tape running system is strengthened, and the tape running stability is obtained.

In the rotary head device of the second invention, a tape running guide is provided on the outer peripheral cylindrical surface of the fixed cylinder, a plurality of openings are provided on the end surface of the cylinder, and a plurality of air grooves are provided on the outer peripheral surface. Since they are communicated and the positions of the other ends of the grooves are aligned at the same angle, an appropriate air layer can be formed between the fixed cylinder and the magnetic tape, and the frictional resistance can be reduced. As a result, the effects of reducing jitter and reducing tape damage can be obtained.

Further, since the rotary head device of the third invention comprises both the rotary cylinder having the features of the first invention and the fixed cylinder having the features of the second invention, The effect which synergized each effect is acquired.

[Brief description of drawings]

FIG. 1 is a front view of a rotary head device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the rotary head device according to the embodiment.

FIG. 3 is a perspective view of a fixed cylinder of the embodiment.

FIG. 4 is a partially developed view of the rotary head device according to the embodiment.

FIG. 5 is a vertical cross-sectional view of a tape entrance portion of the rotary head device according to the embodiment.

FIG. 6 is a diagram showing the floating characteristic of the magnetic tape with respect to the rotating cylinder in the embodiment.

FIG. 7 is a vertical sectional view of an inlet portion of a rotary head device, showing a conventional example of the present invention.

FIG. 8 is a diagram showing a floating characteristic of a magnetic tape with respect to a rotating cylinder in the conventional example.

[Explanation of symbols]

T ... magnetic tape, 1 ... rotary cylinder, 2 ... fixed cylinder, 7 ... magnetic head, 8 ... V groove, 4 ... tape guide guide, 9 ... opening, 8 ... air groove.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G11B 15/61 M

Claims (3)

[Claims] 1. A fixed cylinder for guiding a magnetic tape helically wound around an outer peripheral cylindrical surface between a predetermined central angle, and a fixed cylinder coaxially arranged with an end surface of the fixed cylinder with a narrow gap. A rotary head device comprising: a rotary cylinder that rotates by winding a magnetic tape around an outer peripheral cylindrical surface common to a fixed cylinder; and a magnetic head that is attached to the outer peripheral cylindrical surface of the rotary cylinder and that records and reproduces data on and from the magnetic tape. A rotary head device comprising: the rotary cylinder, which is formed in a tapered shape such that its outer shape is gradually smaller than that of the fixed cylinder, and in which a plurality of V grooves are provided in the circumferential direction. 2. A fixed cylinder which guides traveling by winding a magnetic tape helically around an outer peripheral cylindrical surface between a predetermined central angle and a fixed cylinder which is coaxially arranged with an end surface of the fixed cylinder with a narrow gap. A rotary head device comprising: a rotary cylinder that rotates by winding a magnetic tape around an outer peripheral cylindrical surface common to a fixed cylinder; and a magnetic head that is attached to the outer peripheral cylindrical surface of the rotary cylinder and that records and reproduces data on and from the magnetic tape. A tape running guide which is provided in a helical shape on the outer peripheral cylindrical surface of the fixed cylinder and which guides running by engaging with the end edge of the magnetic tape, and a fixed cylinder end surface facing the clearance between the rotary cylinder and a gap therebetween. And a plurality of openings provided in the fixed cylinder, one end of which is in communication with the above-mentioned openings, and the tape running guide and the flat guide on the outer peripheral cylindrical surface of the fixed cylinder. Provided, and the rotary head and wherein the position of each other of the other end portion is provided with a plurality of air grooves are aligned along the same corner. 3. A fixed cylinder, which is provided between a predetermined central angle and on which a magnetic tape is helically wound around an outer peripheral cylindrical surface to guide the running, and is arranged coaxially with the fixed cylinder end surface with a narrow gap. A rotary head device comprising: a rotary cylinder that rotates by winding a magnetic tape on an outer peripheral cylindrical surface common to a fixed cylinder; and a magnetic head that is attached to the outer peripheral cylindrical surface of the rotary cylinder and that records and reproduces on and from the magnetic tape, The rotary cylinder is formed in a taper shape so that its outer diameter is gradually reduced with respect to the fixed cylinder, a plurality of V grooves are provided on the outer peripheral cylindrical surface of the rotary cylinder, and a helical cylinder is formed on the outer peripheral cylindrical surface of the fixed cylinder. Fixed taper that protrudes in a circular shape and engages with the edge of the above-mentioned magnetic tape to guide the running of the magnetic tape, and the gap between the rotating cylinder and the tape running guide. In the Sunda end face,
A plurality of openings provided with a gap between each other, one end of which is communicated with the above-mentioned opening, which is provided on the outer peripheral cylindrical surface of the fixed cylinder in parallel with the tape guide guide and the positions of the other ends of each other. Is provided with a plurality of air grooves aligned along the same angle.