JP2002050014A - Dummy head and rotary magnetic head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the abrasion of each magnetic head loaded on a rotary drum. SOLUTION: The sliding surface of a dummy head 4 is divided into plural parts by providing a groove portion 24 formed in a direction parallel to a sliding direction with respect to a magnetic tape. Thus, the contact width of the dummy head 4 to the magnetic surface of the magnetic tape is narrowed as one sliding surface even though as the whole sliding surface totaling sliding surfaces 22 and 23 is widened. Therefore, a surface pressure reduction or a contact failure in the dummy head 4 is prevented, and the concavity and convexity of the magnetic surface of the magnetic tape are adequately smoothened. Thus, since the magnetic surface of the magnetic tape is smooth, the abrasion of each magnetic head is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic head mounted on a rotary drum of a rotary magnetic head device for recording and reproducing a magnetic signal on a magnetic tape by a helical scan system, together with the magnetic head, and prior to the magnetic head. The present invention relates to a dummy head that slides on a tape. Further, the present invention relates to a rotary magnetic head device for recording and reproducing magnetic signals on a magnetic tape by a helical scan method.

[0002]

2. Description of the Related Art A recording / reproducing apparatus, such as a video recorder, a data recorder, and a tape streamer, for recording and / or reproducing magnetic signals on a magnetic tape by a helical scan method (hereinafter referred to as recording / reproducing) is a rotating drum. A rotating magnetic head device equipped with a plurality of magnetic heads for recording, reproducing, erasing, and the like is provided thereon.
This rotary magnetic head device records and reproduces magnetic signals by sliding a plurality of magnetic heads against the magnetic surface of the magnetic tape while running the magnetic tape wound helically around the outer periphery of the rotary drum. I have.

The magnetic surface of a magnetic tape that is slid by a magnetic head has fine irregularities due to magnetic powder. In the helical scan method, when the magnetic head slides relatively to the magnetic surface of the magnetic tape, the magnetic surface of the magnetic tape and the plurality of magnetic heads are mutually worn. In the helical scan method, of the plurality of magnetic heads mounted on the rotating drum, the magnetic head that slides first against the magnetic tape comes into contact with the above-described irregularities first, so that the amount of wear thereof is reduced. Tend to be the largest.

Since the magnetic tape is a consumable item, it can be easily replaced when it is worn. However, when the magnetic head is worn, it is difficult to replace it, and the maintenance cost is extremely high. For this reason, in the helical scan method, extending the life of the magnetic head is an important issue.

[0005] In order to prolong the life of the magnetic head, attempts have been made to reduce the wear of the magnetic head by mounting a dummy head on a rotating drum.
The dummy head is mounted on the rotating drum so as to slide with respect to the magnetic surface of the magnetic tape before the plurality of magnetic heads described above. Sliding on the magnetic surface for smoothing.

Each magnetic head other than the dummy head is
As described above, the amount of wear is reduced by sliding on the magnetic surface of the magnetic tape smoothed by the dummy head. This achieves a longer life of the magnetic head.

[0007]

By the way, in most of the dummy heads currently used, the contact width of the sliding surface with respect to the magnetic surface is determined by the recording magnetic head and the reproducing magnetic head mounted on the rotary drum. In each of the other magnetic heads, the sliding surface is set to be wider than the contact width with respect to the magnetic surface. When the contact width of the dummy head is set wider than the contact width of each of the other magnetic heads, the number of times the dummy head slides on the same area of the magnetic surface of the magnetic tape increases, so that the magnetic surface of the magnetic tape becomes smooth. .

However, if the contact width of the sliding surface of the magnetic tape in the dummy head is set too wide, the pressure (hereinafter referred to as surface pressure) applied from the sliding surface of the dummy head to the magnetic surface of the magnetic tape is set. The sliding surface of the dummy head and the magnetic surface of the magnetic tape do not sufficiently come into contact with each other due to the reduction or spacing, so-called contact failure occurs. For this reason, if the contact width of the dummy head is too wide, the effect of the dummy head sufficiently smoothing the magnetic surface of the magnetic tape is reduced, and the magnetic heads other than the dummy head mounted on the rotating drum are adversely affected. The effect of reducing the wear rate is reduced.

As a method for securing the contact width of the sliding surface of the dummy head while suppressing the decrease in the surface pressure, a dummy having a contact width equivalent to that of each of the other magnetic heads such as a recording magnetic head is provided on a rotating drum. A method of reducing the wear rate by mounting a plurality of heads is considered.

However, when this method is adopted, there is a problem that the cost increases because the number of parts increases. In addition, the positioning of the dummy head becomes complicated.

The present invention has been proposed in view of such a conventional situation, and an erasing magnetic head, a recording magnetic head, and a reproducing magnetic head mounted on a rotating drum without causing a significant increase in cost. It is an object of the present invention to provide a dummy head which can effectively reduce wear of a magnetic head for use.

[0012]

A dummy head according to the present invention is mounted together with a magnetic head on a rotary drum of a rotary magnetic head device for recording and / or reproducing magnetic signals on a magnetic tape by a helical scan method. A dummy head that slides on the magnetic tape prior to the magnetic head, wherein a sliding surface that slides on the magnetic tape is formed in a direction parallel to a sliding direction with respect to the magnetic tape. It is characterized by being divided into a plurality of regions by at least one groove.

[0013] The dummy head according to the present invention has a sliding surface,
At least one groove formed in a direction parallel to the sliding direction with respect to the magnetic tape is provided, and the sliding surface is divided into a plurality of regions. Therefore, the contact width of the sliding surface of the dummy head with respect to the magnetic surface of the magnetic tape becomes wider as a whole sliding surface, but becomes narrower as one sliding surface. For this reason, a decrease in surface pressure and a poor contact hardly occur.

Therefore, the dummy head according to the present invention slides on the magnetic surface while sufficiently contacting with the magnetic surface of the magnetic tape, since there is little decrease in surface pressure and poor contact.
The magnetic surface of the magnetic tape can be made sufficiently smooth. This makes it possible to reduce the possibility that the other plurality of magnetic heads mounted on the rotating drum will wear due to contact with the unevenness existing on the magnetic surface of the magnetic tape.

Further, a rotary magnetic head device according to the present invention is a rotary magnetic head device for recording and / or reproducing magnetic signals on a magnetic tape by a helical scan method, comprising: a rotary drum; And a dummy head mounted on the rotating drum together with the magnetic head and sliding on the magnetic tape prior to the magnetic head. In the dummy head, a sliding surface sliding on the magnetic tape is divided into a plurality of regions by at least one groove formed in a direction parallel to a sliding direction with respect to the magnetic tape. It is characterized by.

The rotary magnetic head device according to the present invention has at least one groove formed on the sliding surface in a direction parallel to the sliding direction with respect to the magnetic tape, and the sliding surface is divided into a plurality of regions. With a dummy head. That is, in the dummy head provided in this rotary magnetic head device, the contact width with respect to the magnetic surface of the magnetic tape is:
Although the entire sliding surface becomes wider, it becomes narrower as one sliding surface. Then, in this dummy head, a decrease in surface pressure and a poor contact hardly occur.

Therefore, in the rotary magnetic head device according to the present invention, the magnetic surface of the magnetic tape can be made sufficiently smooth by the dummy head, so that the other magnetic head provided in the rotary magnetic head can be used. Wear is suppressed.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The rotating magnetic head device is provided on a rotating drum,
Each magnetic head such as an erasing magnetic head, a reproducing magnetic head, and a recording magnetic head is mounted. The rotating magnetic head device records and reproduces a magnetic signal by sliding a plurality of magnetic heads against a magnetic surface of the magnetic tape while running while helically winding a magnetic tape around an outer periphery of a rotating drum. I have.

At this time, since each magnetic head mounted on the rotating drum slides the magnetic tape at a high speed, each magnetic head is easily worn.

Therefore, in order to prevent such wear of each magnetic head, a dummy magnetic head is mounted on the rotary magnetic head device. The dummy head is mounted on the rotating drum so as to slide on the magnetic surface of the magnetic tape before each magnetic head, and slides on the magnetic surface of the magnetic tape before each of the other magnetic heads. Move and smooth. Each magnetic head other than the dummy head slides on the magnetic surface of the magnetic tape smoothed by the dummy head, thereby reducing the wear amount.

In the present invention, by optimizing the dummy head, the magnetic surface of the magnetic tape is smoothed appropriately and effectively.

Rotating magnetic head device 1 to which the present invention is applied
As shown in FIG. 1, a dummy head 4 to which the present invention is applied, an erasing magnetic head 11, and two recording magnetic heads 12, 13 are provided on an upper drum 3 of a rotary drum 2.
And two reproducing magnetic heads 14 and 15 are mounted.

The erasing magnetic head 11 includes a magnetic tape 16
The magnetic signal recorded on the magnetic surface 16a is erased.

The recording magnetic heads 12 and 13 record a magnetic signal on the magnetic surface 16a of the magnetic tape 16. The two recording magnetic heads 12, 13 simultaneously record magnetic signals on adjacent tracks, respectively. The two recording magnetic heads 12 and 13 have different azimuths.

The reproducing magnetic heads 14 and 15 reproduce signals recorded on the magnetic surface 16a of the magnetic tape 16. 2
The two reproducing magnetic heads 14 and 15 reproduce magnetic signals recorded on adjacent tracks, respectively. In addition, 2
The two reproducing magnetic heads 14 and 15 have different azimuths.

As shown in FIG. 2, each of the erasing magnetic head 11, the recording magnetic heads 12, 13 and the reproducing magnetic heads 14, 15 has a head core 17 made of a ferromagnetic material such as ferrite. The head chip has a structure in which the coil 18 is wound. These head chips are mounted on the rotating drum 2 in a state where the head chips are provided on a head base.

The rotary drum 2 is composed of a rotatable upper drum 3 and a lower drum (not shown) fixed to a recording / reproducing device (not shown).
6 is configured to run while being wound helically. Here, the rotation direction of the upper drum 3 indicated by an arrow A and the running direction of the magnetic tape 16 indicated by an arrow B are configured to be forward directions.

As shown in FIG. 3, the upper drum 3 is provided with a dummy head 4, an erasing magnetic head 11, recording magnetic heads 12, 13, and reproducing magnetic heads 14, 15 in this order. The rotating drum 2 slides on the surface 16a.
Are mounted at intervals and heights determined by the format along a reference head height position P2 perpendicular to the rotation center line P1.

More specifically, the dummy head 4 is mounted at the highest position based on the reference head height position P2 so as to slide on the magnetic surface 16a first before other magnetic heads. . Then, the erasing magnetic head 11
It is mounted between the dummy head 4 and the reference head height position P2. The recording magnetic heads 12, 13 and the reproducing magnetic heads 14, 15 are respectively mounted near the reference magnetic head height position P2.

When each magnetic head is mounted on the rotating drum 2 in the above arrangement, the rotating drum 2 rotates in the direction indicated by arrow A and the magnetic tape 16 moves in the direction indicated by arrow B. First, the dummy head 4 slides on the magnetic surface 16a, then the erasing magnetic head 11 slides, then the recording magnetic heads 12 and 13 slide, and finally the reproducing magnetic head slides. Slide.

The rotating drum 2 moves the above-described magnetic heads obliquely at a high speed with respect to the magnetic tape 16 by rotating the upper drum 3 while running the magnetic tape 16 wound helically around the outer circumference. Then, a magnetic signal is recorded on a recording track formed obliquely on the magnetic tape 16, and a magnetic signal recorded on the recording track is reproduced.

As shown in FIG. 4, the dummy head 4 has a first member 20 made of, for example, ferrite.
And the second member 21 are joined. By joining the first member 20 and the second member 21,
Erasing magnetic head 11, recording magnetic heads 12, 13,
Core 1 in reproducing and reproducing magnetic heads 14 and 15
A portion corresponding to 7 is formed. The dummy head 4 has sliding surfaces 22 and 23 and a groove 24. As shown in FIG. 5, the dummy head 4 has a groove 24 formed in a direction indicated by an arrow C which is parallel to the sliding direction with respect to the magnetic tape 16 so that the sliding surface is divided into two. have. Note that the arrow C and the arrow A shown in FIGS. 1 and 3 indicate directions in which they coincide with each other.

The dummy head 4 thus configured is
As described above, the magnetic head 16 is mounted at a position that slides on the magnetic surface 16a before the other magnetic head mounted on the rotating drum 2. Then, the magnetic surface 16a is slid before the other magnetic heads, and is smoothed.

As described above, the dummy head 4 includes the groove 24 formed in a direction parallel to the sliding direction with respect to the magnetic tape 16 so that the two sliding surfaces 22 and 2 are provided.
3 has a structure in which the dummy head 4 is formed.
The contact width of the sliding surface with respect to the magnetic surface 16a becomes wider as a total of the sliding surfaces 22 and 23, but becomes narrower as one of the sliding surfaces 22 and 23 alone.

As a result, the dummy head 4 reduces the pressure (hereinafter referred to as surface pressure) from the sliding surfaces 22 and 23 to the magnetic surface 16a, and the sliding surface 22 and 23 due to spacing.
The contact between the magnetic surface 16a and the magnetic surface 16a becomes insufficient, so-called poor contact hardly occurs, and the unevenness of the magnetic surface 16a can be made sufficiently smooth. The erasing magnetic head 11, the recording magnetic heads 12 and 13, and the reproducing magnetic heads 14 and 15 sliding on the magnetic surface 16a after the dummy head 4 have the magnetic surface smoothed by the dummy head 4. Since it slides on 16a, it becomes hard to wear.

More specifically, as shown in FIG.
As the dummy head 4 slides on the magnetic surface 16a, the unevenness 16b becomes smooth, and a smooth surface 16c is formed.
Therefore, the erasing magnetic head 11, the recording magnetic head 1
The magnetic heads 2 and 13 and the reproducing magnetic heads 14 and 15 are less likely to be in contact with the irregularities 16b existing on the surface of the magnetic surface 16a, and are less likely to be worn.

Here, the dummy head 4 is mounted on the magnetic tape 1.
6, the sliding surface 22, which slides on the magnetic surface 16a,
The contact width H of 23 will be described. The sliding surface 2
The contact widths H of 2, 23 are substantially equal to each other.

Sliding surfaces 22, 23 of dummy head 4
The appropriate value of the contact width H has a large relationship with the groove width R of the groove 24 and the thickness, tension, and the like of the magnetic tape 16.
And stiffness.

Here, regarding the appropriate value of the contact width H of the sliding surfaces 22 and 23 in the dummy head 4, as shown in FIG. 7, the track pitch of the two recording magnetic heads 12 and 13 and the two reproducing Assuming that the track pitch of the magnetic heads 14 and 15 is Tp and the contact width of the erasing magnetic head 11 is W1, two recording magnetic heads 12 and 13 are provided.
The contact width is W2 and the two reproducing magnetic heads 1
The contact width of 4, 15 will be described as W3.

The dummy head 4 needs to slide over the entire surface of the magnetic surface 16a in order to smooth the unevenness 16b of the magnetic surface 16a of the magnetic tape 16. In the present embodiment, the magnetic tape 1 is rotated while the upper drum 3 makes one rotation.
The recording / reproduction for two tracks is performed for No. 6. For this reason,
If the contact width H of the sliding surfaces 22 and 23 does not correspond to at least two tracks, trace remaining will be left, and an unsmoothed portion will be generated on the magnetic surface 16a.

The dummy head 4 is a recording magnetic head 1.
The magnetic heads 2 and 13 and the reproducing magnetic heads 14 and 15 are mounted on the same rotary drum 2, and slide with respect to the magnetic surface 16 a in the same motion as the recording magnetic heads 12 and 13. For this reason, for example, the dummy head 4 in which the width of the groove 24 is 4 Tp and the contact width H of the sliding surfaces 22 and 23 is 2 Tp, respectively, is first shown in the first rotation of the rotating drum 2. As shown in FIG. 8 (A), the magnetic surface 1 is slid over the places corresponding to the tracks T1 and T2 and the tracks T7 and T8.
6a is smoothed. Next, at the second rotation of the rotating drum 2,
As shown in FIG. 8 (B), the magnetic surface 16 is slid over the places corresponding to the tracks T3 and T4 and the tracks T9 and T10.
a is smoothed. Then, at the third rotation of the rotating drum 2,
As shown in FIG. 8 (C), the magnetic surface 1 is slid over the places corresponding to the tracks T5 and T6 and the tracks T11 and T12.
6a is smoothed. Furthermore, at the fourth rotation of the rotating drum 2,
As shown in FIG. 8 (D), the magnetic surface 1 is slid over the places corresponding to the tracks T7 and T8 and the tracks T13 and T14.
6a is smoothed. By repeating such an operation, the entire surface of the magnetic surface 16a is smoothed.

For this reason, the contact width H of the sliding surfaces 22 and 23
Is less than 2 Tp, a portion that does not slide on the magnetic surface 16a appears, and the entire surface of the magnetic surface 16a cannot be smoothed. For example, when the track pitch is 20 μm, the sum of the two track pitches is 40 μm.
The contact width H of the sliding surfaces 22 and 23 needs to be 40 μm or more. Here, the hit width H is, for example, 30
μm, the non-sliding part is 1 for every 2 tracks.
It will occur with a width of 0 μm.

After the magnetic surface 16a is smoothed as described above, the erasing magnetic head 11, the recording magnetic head 1
The magnetic heads 2 and 13 and the reproducing magnetic heads 14 and 15 slide on the magnetic surface 16a. Each of these magnetic heads first
At the first rotation of the rotating drum 2, the track T1 and the track T2 slide as shown in FIG. Next, at the second rotation of the rotating drum 2, the track T3 and the track T4 slide as shown in FIG. Further, at the time of the third sliding, the track T5 and the track T6 are slid as shown in FIG. Then, such an operation is repeated to slide on the entire surface of the magnetic surface 16a.

As described above, when the number of the dummy heads 4 mounted on the rotary drum 2 is one, the hit width H is at least the recording magnetic head 12 formed during one rotation of the rotary drum 2. , 13 and the reproducing magnetic heads 14, 15 must have a width corresponding to twice the track pitch Tp. From this, the sliding surface 2
The contact width H of 2,23 needs to satisfy the following expression 1.

2Tp ≦ H (Equation 1) On the other hand, as the dimension of the contact width H increases, the surface pressure decreases. The decrease in the surface pressure affects the tension applied to the magnetic tape 16, the surface properties of the magnetic surface 16 a, the stiffness of the magnetic tape 16, and the tent shape of the magnetic tape 16 which changes depending on the rotation speed of the rotary drum 2.
This means that a is not sufficiently smoothed. That is, when the contact width H of the sliding surfaces 22 and 23 becomes a certain width or more, the magnetic surface 16a cannot be sufficiently smoothed.

Therefore, the contact width H is determined by the sliding surface 22,
It is desirable that the surface pressure from 23 and the surface pressure from the sliding surface of the magnetic head other than the dummy head 4 be at least equal. In other words, the contact width H is equal to the contact width W1 of the erasing head 11 and the recording magnetic head 1
2, 13 and the reproducing magnetic head 14,
Of the 15 hit widths W3, it is preferable that the hit width to the magnetic tape 16 be the narrowest. For this reason, the contact width H of the sliding surfaces 22 and 23 needs to satisfy the following expression (2).

H ≦ W Equation 2 From Equations 1 and 2, the contact width H of the sliding surfaces 22 and 23 is
It is desirable to satisfy Expression 3 shown below.

2Tp ≦ H ≦ W (Equation 3) That is, the contact width H of the sliding surfaces 22 and 23 is equal to or more than the track pitch slid by each magnetic head during one rotation of the upper drum 3. In addition, it is desirable that, of the above-described magnetic heads, the contact width with respect to the magnetic surface 16a be equal to or smaller than the contact width of the narrowest object.

By setting the contact width H of the sliding surfaces 22 and 23 to a value that satisfies the formula 3, it is possible to slide the entire surface of the magnetic surface 16a without generating a contact failure at an optimum contact pressure.

In the magnetic recording heads 12 and 13 and the reproducing magnetic heads 14 and 15, the track pitch is often extremely narrow with respect to the hit width. For example, the hit width is 77 μm, and the track pitch is 10 μm.
m.

The most desirable contact width H of the sliding surfaces 22 and 23 is substantially the same as the contact width of each of the other magnetic heads mounted on the rotary drum 2. When the lifespan of the erasing magnetic head 11, the recording magnetic heads 12, 13 and the reproducing magnetic heads 14, 15 and the dummy head 4 are compared, the contact width H of the sliding surfaces 22, 23 is different from that of the other magnetic heads. If the pressure is extremely narrow as compared with the above, the pressure applied from the sliding surfaces 22 and 23 becomes larger than the pressure applied from other magnetic heads. For this reason, only the dummy head 4 is worn and the magnetic surface 1
Since the irregularities 16b of 6a are not smooth, the other magnetic heads are liable to wear due to contact with the irregularities 16b.

As described above, in consideration of the overall wear during a certain period, the contact width H of the sliding surfaces 22 and 23 should be approximately the same as the contact width of the other mounted magnetic heads. Is desirable.

Next, the width R of the groove 24 will be described. The width R of the groove 24 is set so that the surface pressure applied from the sliding surfaces 22 and 23 is substantially equal to the surface pressure applied from the sliding surfaces of the other magnetic heads mounted on the rotating drum 2. Is set.

For example, when the contact width H of each of the sliding surfaces 22 and 23 is substantially the same as the contact width of the other magnetic heads, the contact pressure applied from the sliding surfaces 22 and 23 is reduced, or the contact pressure is poor. The groove 24 needs to have a width equal to or greater than a predetermined value so as to prevent the occurrence of the above. On the other hand, for example, when the contact width H of the sliding surfaces 22 and 23 is set to half of that of each of the other magnetic heads, if the groove portion 24 is made wider than necessary, the surface pressure applied from the sliding surfaces 22 and 23 increases. As a result, the wear speed of the sliding surfaces 22, 23 becomes extremely high, and the magnetic surface 16a cannot be sufficiently smoothed. As a result, the wear speed of each of the other magnetic heads mounted on the rotating drum 2 also increases, so that it is not desirable to form the width of the groove 24 larger than the predetermined width.

As is apparent from the above description, the dummy head 4 is provided with the groove 24 formed in parallel with the sliding direction with respect to the magnetic tape 16 so that the sliding surface is divided into two. . As a result, the contact width of the sliding surface of the dummy head 4 with respect to the magnetic surface 16a becomes wider as a whole of the sliding surfaces 22 and 23, but becomes narrower as one of the sliding surfaces 22 and 23 alone. . For this reason, the surface pressure on the sliding surfaces 22 and 23 of the dummy head 4 and the hitting failure are less likely to occur, and the dummy head 4 is designed to make the unevenness 16b of the magnetic surface 16a of the magnetic tape 16 sufficiently smooth. It is possible to do.

The smoothness of the unevenness 16b reduces contact between the unevenness 16b and the sliding surface of each of the other magnetic heads mounted on the rotary drum 2. Therefore, the dummy head 4 can reduce wear of each of the other magnetic heads mounted on the rotary drum 2.

The contact width H of the sliding surfaces 22 and 23 is set so that the dummy head 4 has an optimum surface pressure. For this reason, the dummy head 4 is less likely to be worn, and its life is prolonged.

Although the dummy head has one groove and two sliding surfaces, the dummy head may have a plurality of grooves and sliding surfaces. Again,
The width of each sliding surface is equal to or greater than the track pitch slid by each magnetic head during one rotation of the upper drum 3, and the width of the magnetic surface 16 in each magnetic head described above.
It is desirable that the contact width with respect to a be equal to or less than the contact width of the narrowest object.

The rotating magnetic head device 1 has the above-described dummy head 4 mounted on the rotating drum 2. That is, in the dummy head 4 provided in the rotary magnetic head device 1, the contact width H with respect to the magnetic surface 16 a increases as the sliding surfaces 22 and 23 as a whole, but the sliding surface 2
Since the dummy heads 2 and 23 become narrower, the dummy head 4 does not suffer from a decrease in surface pressure or a poor hit. And
In the rotary magnetic head device 1, before each of the other magnetic heads slides on the magnetic surface 16a, the dummy head 4 slides on the magnetic surface 16a a plurality of times while applying an optimum surface pressure.

In the rotating magnetic head device 1, after the magnetic surface 16a is sufficiently smoothed by the dummy head 4 sliding on the magnetic surface 16a a plurality of times as described above, each magnetic head other than the dummy head 4 Is the magnetic surface 16a
Slide. As a result, the rotating magnetic head device 1
Reduces the wear of each magnetic head other than the dummy head 4 and prolongs the life of each magnetic head.

The rotating magnetic head device 1 can smooth the magnetic surface 16a without the provision of the plurality of dummy heads 4, so that the number of components does not increase significantly. Since the number of parts does not increase significantly, positioning does not become complicated, and there is no significant increase in man-hours. Therefore, it is possible to smooth the magnetic surface 16a while suppressing a significant increase in cost.

Here, the number of the dummy heads 4 mounted on the rotary drum 2 is set to one. However, in order to further reduce the wear of the other magnetic heads, the number of the dummy heads 4 mounted on the rotary drum 2 is reduced. The number may be plural. However, when the number of the dummy heads 4 mounted on the rotary drum 2 is plural, the number of components increases, so that the cost may increase significantly.

Also, here, an example is described in which the dummy head 4 is mounted on the rotating drum 2 which is constituted by the upper drum 3 and the lower drum and on which the upper drum 3 rotates.
The dummy head 4 may be mounted on a rotating drum including an upper drum, a middle drum, and a lower drum. In this case, the middle drum rotates, and the erasing magnetic head, the reproducing magnetic head, and the recording magnetic head are mounted on the middle drum. Then, the dummy head 4 is also mounted on the middle drum. At this time, the dummy head 4 is mounted at a position that slides on the magnetic surface 16a before each magnetic head.

[0065]

The dummy head according to the present invention is less likely to cause a decrease in surface pressure and a poor contact, and can make the unevenness of the magnetic surface of the magnetic tape sufficiently smooth. By making the unevenness of the magnetic surface sufficiently smooth, the contact between the unevenness of the magnetic surface and the sliding surface of each of the other magnetic heads mounted on the rotating drum is reduced, and the wear of each of the other magnetic heads is reduced. Can be reduced.

The rotary magnetic head device according to the present invention has at least one groove formed in a direction parallel to the sliding direction with respect to the magnetic tape, so that the dummy head having the sliding surface divided into a plurality of parts can be provided. It is installed. That is, in the dummy head provided in the rotary magnetic head device according to the present invention, the contact width of the magnetic tape with respect to the magnetic surface is wide as a whole sliding surface, but narrow as one sliding surface. The dummy head does not suffer from a decrease in surface pressure or a poor hit.

In the rotating magnetic head device according to the present invention, as described above, after the dummy head slides on the magnetic surface of the magnetic tape a plurality of times, the magnetic surface is sufficiently smoothed, and then each of the components other than the dummy head is moved. The magnetic head slides on the magnetic surface. Thus, the rotating magnetic head device according to the present invention reduces the wear of each magnetic head other than the dummy head, and extends the life of each magnetic head.

[Brief description of the drawings]

FIG. 1 is a plan view showing a rotating drum to which the present invention is applied.

FIG. 2 is a schematic perspective view showing each magnetic head other than a dummy head mounted on the rotating drum.

FIG. 3 is a schematic diagram showing a positional relationship between each magnetic head mounted on the rotating drum and a magnetic tape.

FIG. 4 is a schematic perspective view of a dummy head to which the present invention is applied.

FIG. 5 is a plan view showing a sliding surface of the dummy head.

FIG. 6 is a schematic diagram showing a state where the dummy head smoothes irregularities on a magnetic surface.

FIG. 7 is a schematic diagram illustrating a relationship between a contact width of a sliding surface of the dummy head and a track pitch and a contact width of another magnetic head.

FIG. 8 is a diagram for explaining a relationship between a contact width of a sliding surface of a dummy head to which the present invention is applied and a track pitch, and shows how the dummy head slides on a magnetic surface to smooth it. It is a schematic diagram.

FIG. 9 is a schematic diagram showing tracks formed on a magnetic tape.

[Explanation of symbols]

4 Dummy head, 20 first member, 21 second member, 22, 23 sliding surface, 24 groove

Claims (4)

[Claims] 1. A magnetic head mounted on a rotating drum of a rotating magnetic head device for recording and / or reproducing magnetic signals on a magnetic tape by a helical scan method,
A dummy head that slides on the magnetic tape prior to the magnetic head, wherein a sliding surface that slides on the magnetic tape is formed in a direction parallel to a sliding direction with respect to the magnetic tape. A dummy head, which is divided into a plurality of regions by at least one groove. 2. A contact width of the plurality of divided areas with respect to the magnetic tape is equal to or larger than a signal recording width formed by the magnetic head during one rotation of the rotating drum, and 2. The dummy head according to claim 1, wherein the width of the dummy head is equal to or less than the width of contact with the magnetic tape. 3. A rotary magnetic head device for recording and / or reproducing magnetic signals on a magnetic tape by a helical scan method, comprising: a rotary drum; a magnetic head mounted on the rotary drum; A dummy head mounted on the rotating drum together with the head, and sliding on the magnetic tape ahead of the magnetic head, wherein the dummy head has a sliding surface sliding on the magnetic tape, A rotary magnetic head device, which is divided into a plurality of regions by at least one groove formed in a direction parallel to a sliding direction with respect to a magnetic tape. 4. A width of the plurality of divided areas of the dummy head against the magnetic tape which is equal to or larger than a signal recording width formed by the magnetic head during one rotation of the rotary drum, and 4. The rotary magnetic head device according to claim 3, wherein the width of the magnetic head relative to the magnetic tape is equal to or less than the width.