JPH09330509A - Rotating magnetic head device - Google Patents

Abstract

(57) An object of the present invention is to provide a rotary magnetic head device capable of extending the life of a magnetic head while maintaining a good contact state of the magnetic head with a magnetic recording medium. To do. SOLUTION: A rotary drum 5 has at least a window portion vicinity 5a.
The wear speed of the magnetic recording medium T is higher than that of the other parts of the rotary drum 5 by the magnetic recording medium T. The wear speed of the magnetic recording medium T near the window 5a of the rotary drum 5 is the same as that of the material forming the magnetic head 1. Therefore, the rotary drum 5 is adjusted according to the wear rate of the magnetic head 1.
The vicinity of the window is also worn, and the protrusion amount h becomes long and constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary magnetic head device in which a window for projecting a magnetic head is formed on a surface of a rotary drum around which a magnetic recording medium is wound.

[0002]

2. Description of the Related Art For example, a video tape recorder (VT)
In a recording / reproducing apparatus such as R), there is provided a rotary magnetic head apparatus in which a pair of magnetic core halves around which a coil is wound is butt-joined and integrated, and a magnetic head having a magnetic gap between the butt surfaces is mounted. It is distributed.

In this rotary magnetic head device, a window portion for protruding the magnetic head is formed on the surface of a rotary drum around which a magnetic recording medium is wound. The magnetic head projects from the surface of the rotary drum by a certain amount.

The amount of protrusion of the magnetic head from the surface of the rotary drum is set so that the time for maintaining a good contact state with the magnetic recording medium is maximized in consideration of the balance with the life of the magnetic head.

[0005]

By the way, ferrite, sendust, amorphous or the like is used as the magnetic core material of the magnetic head, while the rotary drum is wear-resistant,
Since an aluminum alloy is usually used from the viewpoint of corrosion resistance, the wear rate of the magnetic recording medium is higher in the magnetic head. Therefore, there is a problem that the protrusion amount of the magnetic head from the surface of the rotating drum is reduced, and the defective contact with the magnetic recording medium is the life of the magnetic head.

In order to solve this problem, it is conceivable to increase the protrusion amount of the magnetic head in advance. However, if the protrusion amount is increased, so-called head knocking (impact error) occurs and accurate recording / reproduction is performed. Cannot be done. Therefore, the protrusion amount of the magnetic head can be set only to a certain extent or less, and as described above, the defective contact of the magnetic head with the magnetic recording medium is the life of the magnetic head.

Therefore, depending on the type of the rotary magnetic head device, the rotary drum surface may be devised so as to maintain the contact state for a long time, but a sufficient one has not been developed yet. .

Therefore, the present invention can extend the life of the magnetic head while keeping the magnetic head in good contact with the magnetic recording medium, and can be used until the maximum gap depth is eliminated. An object is to provide a rotary magnetic head device.

[0009]

In order to solve the above-mentioned problems, the rotary magnetic head device of the present invention has a rotary magnetic head in which a window for projecting the magnetic head is formed on the surface of a rotary drum around which a magnetic recording medium is wound. In the apparatus, the wear speed of the magnetic recording medium at least near the window of the rotary drum is higher than the wear speed of the magnetic recording medium in other portions of the rotary drum.

The wear rate of the magnetic recording medium near the window of the rotary drum is the same as the wear rate of the material forming the magnetic head.

The rotary magnetic head device of the present invention is made of a material in which the wear speed of the magnetic recording medium in the vicinity of the window of the rotary drum is higher than the wear speed of the magnetic recording medium in other portions of the rotary drum. In addition, in the initial contact state of the magnetic recording medium with the rotating drum, it is not necessary to previously increase the protrusion amount of the magnetic head in consideration of the wear rate of the magnetic head as in the conventional case.

After that, when the magnetic head is contacted with the magnetic recording medium for several hundreds to several thousand hours, the magnetic head is worn and the protrusion amount is reduced. A good contact state in which the amount of protrusion of the head from the surface of the rotating drum does not change is maintained.

When the window portion of the rotary drum becomes large due to wear near the window portion of the rotary drum, and the suction amount of the magnetic recording medium also gradually increases, the optimum value of the magnetic head and the magnetic recording medium is further obtained. The contact state will be maintained.

The rotary magnetic head device having such a structure is
Since a good contact state can be maintained due to the relationship between the magnetic head and the magnetic recording medium, it is advisable to further devise the surface shape of the rotary drum, centering on the relationship between these two.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings.

In the rotary magnetic head device, generally, the magnetic head is a so-called "upper drum type" in which the upper drum rotates integrally, and the magnetic head is fixed to a thin drum rotating between the upper and lower drums. There is a so-called "medium drum type". And
The characteristics of the life of the magnetic head are different between the upper drum type and the middle drum type. Hereinafter, embodiments of both of these will be described.

First Embodiment First, as shown in FIGS. 1 and 2, an upper drum type rotary magnetic head device is provided on a lower fixed drum 6, an upper rotary drum 5, and the rotary drum 5. Magnetic head 1
It is composed of The upper drum type is widely used in so-called VHS system and 8 mm video.

In the rotary magnetic head device 11, a window 7 is formed on the outer peripheral surface of the rotary drum 5. This window 7
Is formed to protrude the magnetic head 1.
It is formed in a substantially concave shape so as to be continuous with the gap between the fixed drum 6 and the rotating drum 5.

The magnetic head 1 mounted on the rotary magnetic head device 11 is fixed to the rotary drum 5 via a base plate (not shown) or the like, and rotates together with the rotary drum 5. Then, the magnetic head 1 comes into contact with the magnetic recording medium T traveling at a certain angle along the surface of the rotary drum 5, traces the track of the magnetic recording medium T, and picks up a magnetic flux.
Get playback output.

In the magnetic head 1, as shown in FIG. 4, a pair of magnetic core halves 4a and 4b having a winding groove 3 around which a coil 2 is wound are butted and joined together by a joining means such as glass fusion. And a magnetic gap g is formed between the abutting surfaces.

Here, in the magnetic head 1, the depth of the magnetic gap is referred to as a gap depth d. When the gap depth d is lost due to wear of the magnetic recording medium T, the term "magnetic head originally" is used in this specification. The life of the ".

In the upper drum type, the magnetic head 1 rotates integrally with the rotating drum 5 which is the upper drum.
Since the rotating surface is large, when the magnetic recording medium T enters, an air film (air layer) is formed between the magnetic recording medium T and the rotating drum 5, which is formed by air. Normally, this air film is used for the magnetic recording medium T.
Ideally, the magnetic recording medium T should only come into contact with the magnetic head 1 while avoiding the contact state between the rotary drum 5 and the rotary drum 5.

Therefore, this upper drum type is good for avoiding damage to the rotary drum 5 and the magnetic recording medium T and sticking of both, but on the other hand, the magnetic head 1
If the amount of protrusion from the rotating drum 5 is reduced due to abrasion, the air film causes the contact state with the magnetic recording medium T to be unstable (defective contact), and sufficient recording and reproduction cannot be performed.

In the present embodiment, as shown in FIG. 5, the vicinity 5 of the concave window portion for protruding the magnetic head 1 of the rotary drum 5 is provided.
The material of a is composed of a material having a higher wear rate by the magnetic recording medium T than the other parts of the rotary drum 5.

Here, the material forming the rotary drum 5 is
Usually it is an aluminum alloy. Therefore, as the material of the window portion vicinity 5a of the rotary drum 5 which projects the magnetic head 1, a material which is more easily worn than the aluminum alloy is used.

However, the material forming the rotary drum 5 is
It is also preferable to consider the relationship with the wear rate of the magnetic head 1. That is, it is preferable that the material in the vicinity of the window portion 5a of the rotary drum 5 is made of the material forming the magnetic head 1 and the material having the same wear rate by the magnetic recording medium T.

Normally, in the VHS or β system, the magnetic head 1
The magnetic core material is ferrite, and a material having a higher saturation magnetic flux density, called sendust or amorphous, is used in 8 mm or the like where a metal tape is used.

Therefore, in the vicinity of the window portion 5a of the rotary drum 5.
The material of is determined in relation to the type and material of the magnetic head 1. In the present embodiment, the magnetic core material of the magnetic head 1 is made of ferrite, and the material in the vicinity of the window portion 5a of the rotary drum 5 is an aluminum alloy having the same wear rate as the ferrite. On the other hand, the other part of the rotary drum 5 is an aluminum alloy different from this aluminum alloy. These aluminum alloys can be easily obtained only by changing the constituent materials such as impurities contained therein. Thus, in the present embodiment, the material of the vicinity 5a of the window of the rotary drum 5 is made of a material having a higher wear rate by the magnetic recording medium T than the material of the other parts of the rotary drum 5. .

In the manufacture of the rotary drum 5 of the rotary magnetic head device 11 as described above, even if the metal is heated and punched with a hammer or the like to give a desired shape and toughness, the material in the vicinity of the window portion 5a is used. Instead of being integrated with the rotary drum 5, a component having a similar shape may be attached later to the window portion vicinity 5a by, for example, bonding or press fitting.

For example, the material forming the rotary drum 5 in recent years is also manufactured by repeating the forging on the center side and the surface side of the rotary drum 5. That is, for example, powder aluminum is integrated into the forged aluminum alloy on the center side by forging. Therefore, if at least the window portion 5a of the rotary drum 5 is made of a material having a higher wear rate by the magnetic recording medium T than the other parts of the rotary drum 5, it is manufactured by repeating such forging. You may.

Further, it may be a so-called clad material, which is a composite metal plate formed by joining two or more kinds of metals in order to make the best use of their respective characteristics.

For example, as the clad material, a laminated plate of corrosion-resistant aluminum and a strong aluminum alloy is prepared by a method such as rolling, welding or pressure bonding. Then, for example, a material that is more easily worn than the aluminum alloy, that is, another aluminum alloy that is more easily worn is put in the vicinity of the window portion 5a of the plate on the front surface side and integrated by forging. In addition, an engineer plastic-based material or a carbon-based material may be put in the vicinity 5a of the window.

In this embodiment, since the rotary magnetic head device 11 is configured in this way, in the initial contact state where the magnetic head 1 contacts the magnetic recording medium T, as shown in FIG. A sufficient protrusion amount h is secured for
Along with the suction of the magnetic head 1, a good contact state with the magnetic recording medium T is maintained. Therefore, in this initial contact state, it is not necessary to previously increase the protrusion amount h of the magnetic head 1 in consideration of the wear rate of the magnetic head as in the conventional case.

Thereafter, as a result of contact with the magnetic recording medium T for hundreds to thousands of hours, the magnetic head 1 is worn and the protrusion amount h is reduced.
The vicinity 5a of the window also wears.

In this respect, according to the conventional rotary magnetic head device, as shown in FIG. 9, the magnetic recording medium T has a higher wear rate than the surface of the rotating drum, so that the magnetic recording medium T has a higher wear rate. The contact state between the and magnetic head was unstable (bad contact). For this reason, measures such as increasing the amount of protrusion in the initial contact state have been made.
Further, since the rotating drum is made of an aluminum alloy from the viewpoint of wear resistance and the like, it is impossible that the vicinity of the window portion of the rotating drum becomes large (in FIG. 9,
The symbol R is used. ).

On the other hand, in the rotary magnetic head device 11 of the present embodiment, the window portion 5a of the rotary drum 5 is made of a material having a higher wear rate than the other portions of the rotary drum 5, and the rotary magnetic head device 11 is The wear speed of the magnetic recording medium near the window 5a of the drum 5 is the same as that of the magnetic head 1.

Therefore, as shown in FIGS.
The vicinity of the window 5a of the rotary drum 5 is also worn according to the wear speed of the magnetic head 1 by the magnetic recording medium T, but when the protrusion amount h of the magnetic head 1 from the surface of the rotary drum 5 is worn, it is almost the same. The window portion 5a of the rotary drum 5 is also worn by the same amount (indicated by reference numeral h2 in FIG. 6; h≈h).
2). Therefore, during this period, the protrusion amount h of the magnetic head 1 from the surface of the rotary drum 5 is kept constant, so that accurate recording / reproduction can be performed for a long time.

Then, the magnetic head 1 is abraded in the same manner until the depth d of the magnetic gap is eliminated, and is abraded to the maximum "the original life of the head" (h, h2≤d). Therefore, the life of the magnetic head 1 of the rotary magnetic head device 11 of the present embodiment can be extended.

Here, the relationship between the wear speeds of the magnetic head 1 and the window portion 5a of the rotary drum 5 is that the magnetic recording medium T needs to be in contact with the magnetic head 1 at all times. The same or slightly 5a near the window of the rotating drum 5
Is preferably faster.

Then, as shown in FIG. 8, the window portion 7 of the rotary drum 5 becomes large due to the abrasion of the window portion 5a of the rotary drum 5 (indicated by symbol r in FIG. 8; R <r). As the suction amount of the magnetic recording medium T gradually increases, the optimum contact state between the magnetic head 1 and the magnetic recording medium T can be maintained.

Here, in the present embodiment, it is not necessary to wear the window portion vicinity 5a from the initial state,
The rotating drum 5 may start to wear when the magnetic head wears and the distance between the magnetic recording medium T near the window 5a and the rotating drum 5 becomes shorter. By doing so, there is an effect that abrasion powder is not generated more than necessary.

Since it is sufficient that the periphery of the magnetic head 1 is gradually worn until the depth d of the magnetic gap of the magnetic head 1 disappears due to friction with the magnetic recording medium, it is made of a material having a wide area and a high wear rate. No need.

In the upper drum type, the contact between the magnetic head 1 and the magnetic recording medium T becomes soft due to the large amount of air film, and the friction of the magnetic recording medium T with the rotating drum 5 also becomes small. However, when the damaged magnetic recording medium T is applied or the air film is lost due to strong tension, tape damage may occur. Therefore, as shown in FIG. 1, the rotating drum 5 is parallel to the rotating direction. In many cases, several grooves 9 are formed to prevent tape adsorption.

Therefore, in the present embodiment, the magnetic recording medium T is devised in the surface shape of the rotating drum 5 such as adjusting the number and depth of the grooves 9 centering on the relationship with the magnetic head 1. It is good to do so. However, according to the present embodiment, the contact state is obtained centering on the relationship between the magnetic recording medium T and the magnetic head 1, and it is secondary or auxiliary to devise the surface shape of the rotating drum. Therefore, an ideal contact state is realized.

Second Embodiment Next, as shown in FIG. 3, in the rotary magnetic head device of the medium drum type, the magnetic head 1 is attached to a thin head drum 25 which rotates from between the upper and lower fixed drums 22 and 23. It is fixed. The medium drum type is often used in early home video and so-called β system.

The rotary magnetic head device 11 of this type also has the rotary drum 25 as in the first embodiment.
The window portion 27 is formed in the.

In this middle drum type rotary magnetic head device 21, since the upper and lower drums 22 and 23 do not move, the lower end of the magnetic recording medium T is read (a step serving as a reference for the vertical alignment of the magnetic recording medium T). 8 is relatively easy to follow and is excellent in the regulation force in the width direction of the magnetic recording medium T. The medium drum type has the advantage that the load on the motor is small and the traveling is stable because the magnetic head 1 is attached to the lightweight head disk.

It should be noted that when the surface of the magnetic recording medium T becomes high in density and the surface becomes smooth, friction increases, but at this time, the surface of the fixed drum is roughened to reduce the tape tension. A device is made.

The medium drum type has a small amount of air film because the rotating surface is small. In this respect, it is symmetrical with the drum type.

Therefore, the fixed upper and lower drums 22, 23
And the magnetic recording medium T are in contact with each other, and the contact pressure between the magnetic head 1 and the magnetic recording medium T is high at the same time. Even if the protrusion amount h of the magnetic head 1 is small due to the high contact pressure, a good contact state is maintained. On the other hand, the wear of the magnetic head 1 is faster than that of the upper drum type, and the magnetic gap of the magnetic head 1 disappears to reach the end of its life.

Therefore, also in this embodiment, as in the first embodiment, the material of the window portion 25a of the rotary drum 25 near the magnetic head 1 is larger than that of the other portions of the rotary drum 25 in comparison with the material of the magnetic recording medium T. It is composed of a material that has a high wear rate. The wear rate of the magnetic recording medium near the window 25a of the rotary drum 25 is the same as that of the magnetic head 1.

Therefore, in the present embodiment, even if the protrusion amount h of the magnetic head 1 in the initial contact state from the surface of the rotating drum 25 is small, the vicinity 25 of the window portion of the rotating drum 25 is obtained.
Since a wears out, a good contact state can be obtained.

In this respect, in the conventional medium drum type rotary magnetic head device, it is necessary to increase the protrusion amount of the magnetic head in advance in consideration of the wear rate of the magnetic head.

In particular, in the medium drum type, the surface of the magnetic recording medium T has a high density, and when the surface is smooth, friction increases, but in the present embodiment, the rotary drum 2 is used.
Since the vicinity of the window portion 25a of No. 5 is abraded, there is a great effect that the protrusion amount h of the magnetic head 1 in the initial state can be suppressed to be small.

After that, as a result of contact with the magnetic recording medium T for hundreds to thousands of hours, the magnetic head 1 wears and the protrusion amount h decreases. However, as in the first embodiment, While the protrusion amount h from the surface of the rotary drum 25 is kept constant, the same wear occurs until the depth d of the magnetic gap of the magnetic head 1 is reduced to the maximum (see FIGS. 6 to 8).

[0056]

The rotary magnetic head device of the present invention is made of a material in which the wear speed of the magnetic recording medium in the vicinity of the window of the rotary drum is faster than the wear speed of the magnetic recording medium in other portions of the rotary drum. Therefore, the good contact state in which the protrusion amount of the magnetic head from the surface of the rotary drum does not change can be maintained for a long time.

Therefore, the life of the magnetic head can be extended, and accurate recording / reproduction can be performed for a long time until the gap depth of the magnetic head is eliminated to the maximum.

Further, since the wear rate of the magnetic recording medium in the vicinity of the window portion of the rotating drum is made of the same material as that of the magnetic head, the conventional method is used in the initial contact state of the magnetic recording medium with the rotating drum. As described above, it is not necessary to increase the protrusion amount of the magnetic head in advance in consideration of the wear rate of the magnetic head.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of the rotary magnetic head device.

FIG. 3 is a perspective view showing a rotary magnetic head device according to another embodiment of the present invention.

FIG. 4 is a schematic view showing a configuration of a magnetic head of the rotary magnetic head device.

FIG. 5 is an enlarged side view showing the vicinity of a window of a rotary drum of the rotary magnetic head device.

FIG. 6 is a schematic view showing a worn state of a magnetic head and the vicinity of a window of a rotary drum of the rotary magnetic head device.

FIG. 7 is a schematic view showing a worn state of a magnetic head and the vicinity of a window of a rotary drum of the rotary magnetic head device.

FIG. 8 is a schematic diagram showing a wear relationship between a magnetic head and the vicinity of a window of a rotary drum of the rotary magnetic head device.

FIG. 9 is a schematic view showing the relationship between the magnetic head and the vicinity of the window of the rotary drum of the conventional rotary magnetic head device.

[Explanation of symbols]

1 magnetic head, 5,25 rotating drum, 6 fixed drum, 5a, 25a near window part of rotating drum, 7, 27
Windows 11, 21, rotary magnetic head device, d gap depth, g magnetic gap of magnetic head, h magnetic protrusion of magnetic head

Claims (2)

[Claims] 1. A rotary magnetic head device in which a window for projecting a magnetic head is formed on the surface of a rotary drum around which a magnetic recording medium is wound. In the rotary drum, the wear speed of the magnetic recording medium at least near the window of the rotary drum is high. A rotary magnetic head device, characterized in that it is made of a material that is faster than the wear speed of the other part of the magnetic recording medium. 2. The rotary magnetic head according to claim 1, wherein the wear rate of the magnetic recording medium near the window of the rotary drum is the same as the wear rate of the material forming the magnetic head. apparatus.