JPH09305945A - Multi-magnetic head and front surface polishing and bonding method for magnetic head - Google Patents

Abstract

(57) Abstract: A multi-magnetic head having three or more heads mounted on a head base and a man-hour for polishing and adhering the heads are simplified to secure required performance. SOLUTION: Magnetic heads 1 and 2 are recording combination heads,
The magnetic heads 3 and 4 are erasing combination heads and are bonded to the same multi-head base 7. To attach the multi-head base 7 to the polishing drum 16, the recording head 1,
In polishing No. 2, the front surface is projected from the outer peripheral surface 17, and the front surfaces of the erasing heads 3 and 4 are positioned so as not to project from the outer peripheral surface 17. By utilizing the diameter difference between the rotary cylinder 9 and the polishing drum 16, polishing is performed for each of the magnetic heads 1 to 4 in combination.
Since the adhesion of the magnetic heads 1 to 4 to the multi-head base 7 has a mounting error in the protruding direction, the erasing head 3,
4 is projected a lot. After the recording heads 1 and 2 are polished, the erasing heads 3 and 4 are polished so that the difference in the protrusion amount becomes zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a multi-magnetic head used in a magnetic recording / reproducing apparatus and a method for polishing and adhering the front surface of the magnetic head.

[0002]

2. Description of the Related Art In order to manufacture a magnetic recording / reproducing apparatus (for example, a VTR) having stable characteristics and functions, first, a recording / reproducing output from a magnetic head for recording / reproducing and a magnetic tape is stably outputted. It is important that the magnetic head is positioned with respect to the rotary cylinder with high accuracy. In particular, it is necessary to make the contact state between the magnetic head and the magnetic tape uniform.

Conventional helical scanning method V
As a typical publicly known example of a front surface polishing method for a magnetic head attached to a TR, for example, a VHS system VTR,
There are some processing methods as follows. That is, first, the block in which the gap is formed is cut, the separated head chip is adhered to the head base with a predetermined size, and then it is attached to the jig of the polishing drum of the head front surface polishing device and rotated, and this rotation is performed. By polishing with a polishing tape wound around a polishing drum, the front surface is finished in a predetermined shape. In addition, in a VHS system VTR that supports long time and noiseless, 2 head
There is a so-called combi head in which individual head chips are adhered, and in this case as well, processing and polishing are performed by a method similar to that described above.

By the way, in the case of a commercial digital VTR that handles a large amount of information or a high-definition VTR, in general,
A method of dividing the amount of information and recording with a plurality of heads is adopted. When the number of head chips is increased in order to realize this method, that is, when the number of magnetic heads is increased, there is no space for arranging the head bases corresponding to the individual head chips. It has been necessary to form a so-called multi-magnetic head in which more than one head chip is bonded.

However, when the above-mentioned polishing method is applied to such a multi-magnetic head, it is difficult to properly manage the gap depth and uniformly polish the head front surface shape. Therefore, in manufacturing such a multi-magnetic head, the head chip is removed from the head base after the head front surface is polished by the head chip alone. Next, a plurality of head chips are bonded to the same head base so that the gap position of the head chip and the apex of the front surface of the head chip are substantially aligned on the outer circumference of the rotary cylinder, and the head base is screwed to the rotary cylinder. Was attached to.

[0006]

However, in the multi-magnetic head having such a structure and the method for polishing and adhering the front surface of the magnetic head, a great number of man-hours are required to manufacture the multi-magnetic head, and eventually, the multi-magnetic head is manufactured. There is a problem that the head becomes expensive.

The present invention is directed to solving the above-mentioned problems of the prior art, and provides a multi-magnetic head capable of simplifying the man-hours and ensuring the required performance, and a front surface polishing and bonding method for the magnetic head. The purpose is to do.

[0008]

In order to achieve this object, the multi-magnetic head according to the present invention has a first magnetic head and a second magnetic head.
And a second combination head composed of the third and fourth magnetic heads are bonded on the same head base, and the first combination head is for recording / reproduction. And the second combination head is an erasing magnetic head.

Further, a first combination head composed of first and second magnetic heads and a single head composed of a third magnetic head are bonded on the same head base,
The first combination head is a recording / reproducing magnetic head, and the single head is an erasing magnetic head.

Further, the gap position gap between the second magnetic head and the third magnetic head is made larger than the gap position gap between the first magnetic head and the second magnetic head, and the head base is mounted. The diameter of the polishing drum is made larger than the diameter of the rotating cylinder, and the first combination head and the second combination head arranged on the same head base perform front surface polishing for each combination head. To be able to.

Further, by attaching to the head base so that the protruding amount of the second erasing second combination head is larger than that of the first recording / reproducing first combination head, the mounting error of the magnetic head is absorbed by the gap depth. To be able to.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a rotary cylinder on which a multi-magnetic head according to Embodiment 1 of the present invention is mounted, viewed from the back side.

In FIG. 1, reference numerals 1a, 2a and 1b, 2b respectively denote a pair of recording heads, and each of these pairs constitutes a recording combination head. 3a, 4a and 3
Reference numerals b and 4b respectively denote a pair of erasing heads, each of which constitutes an erasing combination head. Reference numerals 5a, 6a and 5b, 6b respectively denote a pair of reproducing heads, and each of these pairs constitutes a reproducing combination head. 7a and 7b are multi-head bases, which are recording heads 1a,
Recording combination head including 2a and erasing heads 3a and 4a
Erasing combination head including, and recording head 1b,
The recording combination head including 2b and the erasing head 3b,
The erasing combination heads including 4b are adhered to each other. Further, 8a and 8b are combination head bases, which are reproduction combination heads including reproduction heads 5a and 6a,
The reproducing combination heads including the reproducing heads 5b and 6b are adhered to each other. Reference numeral 9 is a rotary cylinder on which the multi-head bases 7a and 7b and combination head bases 8a and 8b are mounted, 10 is a screw, and arrow A is a rotary cylinder 9.
Is the direction of rotation.

Further, in each of the following drawings, constituent members having the same function and effect are designated by the same reference numerals, and the duplicated description thereof will be omitted. The subscripts “a” and “b” of the reference numerals attached to the respective members in the drawing are given for distinguishing the similar members provided to face the rotary cylinder 9 or the polishing drum described later by about 180 degrees. For convenience, some of them are not shown.

FIG. 2 is a perspective view showing a main part of the rotary cylinder according to the first embodiment. In FIG. 2, 11 is a fixed cylinder that rotatably supports a rotating cylinder 9 having a lead portion that guides the magnetic tape 12, and 13 is a head for recording heads 1 and 2 to project from the outer peripheral surface of the rotating cylinder 9. A head window, 14 is a head window through which the erasing heads 3 and 4 project, 15 is a head window through which the reproducing heads 5 and 6 project, and arrow B indicates the running direction of the magnetic tape 12 and the polishing tape described later. Is.

FIG. 3 is an enlarged view of the multi-head base portion to which the recording head and the erasing head in the first embodiment are bonded. In FIG. 3, I _{1 to} I ₄ are I-shaped cores constituting the magnetic heads 1 to 4, and C _{1 to} C ₄ are the magnetic heads 1 to ₄ .
C-shaped core which constitutes the 4, g ₁ to g ₄ is a gap of the magnetic head 1 to 4, S ₁ to S ₅ are slit grooves provided to allow adjusting the relative height of the magnetic head 1 to 4, D ₁₂ ,
D _23, D ₃₄ is the gap distance between the magnetic head 1-4.

4 (a) and 4 (b) show the first embodiment.
4A shows a state in which the multi-head base is attached to the polishing drum, and FIG. 4A is a plan view showing the relationship between the diameter of the polishing drum and the diameter of the rotating cylinder.
FIG. 3 is a partially enlarged view of a recording head and an erasing head attached to a polishing drum. In FIGS. 4 (a) and 4 (b), 16 is a polishing drum to which the multi-head base 7 is attached, 17 is an outer peripheral surface of the polishing drum 16, and 18a and 18b are for wrapping a polishing tape to be described later around a combination head for polishing. Suction groove of the polishing tape, O is the center of rotation of the polishing drum 16, Oa '
Is the center of rotation of the rotary cylinder 9, T is the amount of protrusion of the combination head mounted on the polishing drum from the outer peripheral surface of the polishing drum, and L ₁ and L ₂ are the center of rotation Oa ′ of the rotary cylinder 9 and the distance between each combination head. It is the center line connecting the central parts.

In the multi-magnetic head shown in FIGS. 1 and 2 in the first embodiment, the multi-head base 7 and the combination head base 8 are mounted on the rotary cylinder 9 having a diameter of about 21.7 mm, and each magnetic head is 1 to 6 (1a, 1b to 6a, 6
In b), about 10 to 30 μm is projected from the outer peripheral surface 17 of the rotating cylinder 9.

Further, as shown in FIG. 3, the magnetic head 1,
2 is an I-shaped core I _1, I ₂ and C-shaped core C _1, C _2, has a gap g _1, g _2, the gap g ₁ and the gap distance D ₁₂ of the gap g ₂ is about 6 degrees Form a combi head (about 1.2 mm). The magnetic heads 3 and 4 are also composed of I-type cores I ₃ and I ₄ and C-type cores C ₃ and C ₄ , and the gap distance D ₃₄ between the gaps g ₃ and g ₄ is about 1.
It forms a 2mm combination head.

The magnetic heads 1 and 2 are recording heads,
The magnetic heads 3 and 4 are erasing heads, and the combination heads of the reproducing heads 5 and 6 are similarly configured (see FIG. 1).
Furthermore, an approximately 22-degree gap distance D ₂₃ of the gap g ₂ and the gap g ₃ of the magnetic head 2 and the magnetic head 3 (about 4.1 mm), Combi head gap distance D ₁₂ of the aforementioned,
It is more than 3 times as large as D ₃₄ (about 1.2 mm). The multi-head base 7 to which the magnetic heads 1 and 2 for recording and the magnetic heads 3 and 4 for erasing are adhered is provided with a slit groove S so that the relative height of each magnetic head 1 to 4 can be adjusted. _{1 to} S ₅ are provided.

The diameter of the polishing drum 16 for polishing is shown in FIG.
It is slightly larger than the diameter of the rotary cylinder 9 shown by the two-dot chain line in (a). The diameter of the polishing drum 16 is preferably 1.1 to 1.5 that of the rotary cylinder 9. Therefore,
The position of the rotation center O of the polishing drum 16 and the position of the rotation center Oa 'of the rotary cylinder 9 indicated by the chain double-dashed line are displaced.

In other words, the posture in which the multi-head base 7 is attached to the polishing drum 16 is such that when the recording heads 1 and 2 are polished, the center line L ₁ of the recording heads 1 and 2 is the polishing drum 1.
The head front surface is mounted so as to be aligned with a line passing through the rotation center O of 6 and protruding from the outer peripheral surface 17 of the polishing drum 16 by a predetermined amount (in the first embodiment, the protruding amount T (see FIG. )) Is 100 to 300 microns). At this time, the tips of the gaps g ₃ and g _{4 on} the front faces of the erasing heads 3 and 4 which are not polished are the outer peripheral surface 17 of the polishing drum 16.
It is positioned within the diameter of the polishing drum 16 so as not to project further.

As described above, in order to polish the multi-magnetic heads (magnetic heads 1 to 4) for each combination head by utilizing the diameter difference between the rotary cylinder 9 and the polishing drum 16, the gap distance D It is necessary to make the gap distance D ₂₃ larger than ₁₂ (see FIG. 3). For this reason, a multi-magnetic head is constructed by using a combination head of two magnetic heads, each of which has an I-shaped core with a narrow width and a C-shaped core with a wide width having a winding groove. This can be easily realized.

Further, the larger the diameter of the polishing drum 16, the outer peripheral surface of the polishing drum 16 of the combination head on the non-polishing side.
It becomes easy to surely prevent the head from protruding from 17. However, if the diameter of the polishing drum 16 is too large, the radius of curvature of the front surface of the magnetic head becomes large and the contact with the magnetic tape 12 near the gap deteriorates. Is preferred.

On the other hand, when the erasing heads 3 and 4 are polished, the erasing heads 3 and 4 are polished in the same manner as the recording heads 1 and 2.
The center line L ₂ of the polishing drum 16 is aligned with the line passing through the rotation center O of the polishing drum 16, and the polishing drum 16 is attached by protruding from the outer peripheral surface 17 by a predetermined amount. At this time, the tips of the recording heads 1 and 2 may be positioned so as not to project from the outer peripheral surface 17 of the polishing drum 16.

Next, FIG. 5 is an explanatory diagram of the mounting error when the magnetic head is bonded in the first embodiment. In FIG. 5, 19 is a mounting reference disk for bonding the magnetic head to the multi-head base 7, and 20 is a mounting reference disk.
A virtual circle when the gap tips of the magnetic heads 1 and 2 are viewed from the rotation center Op of 19, and a virtual circle 21 when the gap tips of the magnetic heads 3 and 4 are viewed from the rotation center Op of the mounting reference disk 19. , Δp are mounting errors in the protruding direction of the magnetic head.

The magnetic heads 1 to 4 are attached to the multi-head base 7.
The state in which is adhered will be described with reference to FIG. The adhesion of the magnetic head to the head base is performed without adjustment with the mechanical accuracy of an adhesion device (not shown) only in order to improve productivity. Therefore, due to machine and head shape errors, the mounting error δ in the protruding direction as shown in FIG.
will have p. The mounting reference disk 19 has a diameter equal to the diameter of the rotating cylinder 9 of 21.7 mm, and the mounting error δp is the radius difference between the virtual circles 20 and 21.

Actually, in addition to the mounting error δp, there are attitude errors and the like of the magnetic head, but since it is easier to ensure accuracy as compared with the mounting error δp in the protruding direction, here, the mounting error δp in the protruding direction is used. The effectiveness of the front surface polishing, the bonding method, and the effectiveness of the multi-magnetic head of the present invention will be described.

FIG. 6 is a plan view showing a polishing state of the magnetic head attached to the polishing drum in the first embodiment, and 22 is a polishing tape. FIG. 7 is a sectional view of the polishing drum shown in FIG. 6 taken along the line X-Ob'-Y. Further, FIG. 8 is an enlarged plan view showing a portion of the polishing drum and the magnetic head to be polished, and FIG. 9 is an enlarged sectional view showing the portion of the polishing drum and the magnetic head to be polished.

On the side of the multi-head base 7a shown in FIG. 6, the recording heads 1a and 2a are polished by the multi-head base 7a.
On the b side, the erasing heads 3b and 4b are polished.
The polishing tape 22 is made of CrO ₂ and is equivalent to No. 10000, and is run in the direction of arrow B. Also polishing drum
Reference numeral 16 is rotated in the direction of arrow A, and the front surfaces of the recording heads 1a and 2a and the erasing heads 3b and 4b and the polishing tape 22 are brought into contact with each other for polishing.

Further, as shown in FIG. 8, the recording head 1
The polishing tape 22 is wound around the suction grooves 18a around the a and 2a, and the recording heads 1a and 2a are polished into a predetermined shape. Polishing of the recording heads 1a and 2a is performed so that a predetermined gap depth is obtained. Further, since the erasing heads 3a and 4a do not project from the outer peripheral surface 17 of the polishing drum 16 and the suction groove 18a of the polishing tape 22 is not provided, the polishing tape 22 and the erasing head 3a are not provided. ，
Almost no contact with 4a occurs and it is not polished.

On the other hand, the erasing heads 3b and 4b on the side of the multi-head base 7b opposite to the polishing drum 16 are also polished by the polishing tape 22 into a predetermined shape, like the recording heads 1a and 2a. On the other hand, the recording heads 1b and 2b are not polished. On the contrary, the polishing of the erasing heads 3a and 4a and the recording heads 1b and 2b need only be performed by replacing the multi-head base 7a and the multi-head base 7b, and therefore the description thereof will be omitted (see FIG. 6).

Next, FIG. 10 is an explanatory view of the polishing conditions for absorbing the head mounting error in the first embodiment, and 23 is the tip of the recording heads 1 and 2 after polishing from the rotation center O '. The virtual circle, δp ', is the error between the virtual circle 21 and the virtual circle 23. As described above, the adhesion of the magnetic heads 1 to 4 to the multi-head base 7 has a mounting error δp in the protruding direction. The adhesion and polishing conditions of the magnetic heads 1 to 4 with respect to the mounting error .delta.p will be described with reference to FIG.

First, at the time of adhering to the multi-head base 7, the erasing heads 3 and 4 are offset so that they protrude more than the recording heads 1 and 2 protrude.
It is preferable that this offset amount is set as a rough attachment error Δp. Next, the recording heads 1 and 2 are polished to have a predetermined gap depth. At this time, the tips of the recording heads 1 and 2 after polishing form a virtual circle 23. next,
When the erasing heads 3 and 4 are polished, the error δp 'becomes 0, that is, the imaginary circle 23 at the tips of the recording heads 1 and 2 and the imaginary circle 21 at the tips of the erasing heads 3 and 4. The erasing heads 3 and 4 are polished a lot so that they coincide with each other. At this time, the gap depths of the erasing heads 3 and 4 are longer than the gap depths of the recording magnetic heads 1 and 4 in order to prevent the gap depths of the erasing heads 3 and 4 from becoming too small and shortening the head life. Alternatively, the head life of the erasing heads 3 and 4 can be made equal to that of the recording heads 1 and 2 by increasing the head thickness.

Although the gap depth of the erase heads 3 and 4 after polishing may become long depending on the direction of the mounting error δp, the electromagnetic conversion characteristics of the erase heads 3 and 4 are different from those of the recording heads 1 and 2. In comparison, it is not a problem because it is not needed so much.

The value of the mounting error δp in the protruding direction may be measured at the time of mounting the magnetic heads 1 to 4, or may be measured at the time of polishing.

As described above, the recording combination head composed of the recording heads 1 and 2 and the erasing combination head composed of the erasing heads 3 and 4 are adhered to the multi-head base 7, whereby the combination composed of two magnetic heads is combined. Polishing for each head becomes easy.

Further, by forming a multi-magnetic head with the recording heads 1 and 2 which are required to have high electromagnetic conversion characteristics and the erasing heads 3 and 4 having relatively low specifications, the head manufacturing yield is lowered. It is possible to manufacture a multi-magnetic head without having to do so. Further, by dividing the recording heads 1 and 2 and the erasing heads 3 and 4 for each combination head, the mounting error of the magnetic heads is adjusted by the gap depth of the erasing heads 3 and 4, and a highly accurate multi-magnetic head is compared. It becomes possible to manufacture easily.

Next, FIG. 11 is a plan view seen from the back side showing the rotary cylinder in which the multi-magnetic head according to the second embodiment of the present invention is mounted. In FIG. 11, 24 is an erasing head having a single head and the outer shape is substantially symmetrical, 25 is a multi-head base in which the recording heads 1 and 2 and the erasing head 24 are bonded, and D ₂₃ ′ is It is the gap distance between the recording head 2 and the erasing head 24. Also,
FIG. 12 is a plan view showing a polishing state of the magnetic head on the polishing drum 16.

The second embodiment will be described with reference to FIGS. 11 and 12. First, since the erasing head 24 is a single head, the gap distance D ₂₃ ′ is about 4 times as large as the gap distance D ₁₂ of the recording heads 1 and 2 shown in FIG. Therefore, the first embodiment described above
Similarly, the front polishing of the recording heads 1 and 2 and the front polishing of the erasing head 24 can be individually performed.

Recording heads 1a, 2a and erasing head 24b
Is contacted with the polishing tape 22 and slid to be polished. on the other hand,
The recording heads 1b and 2b and the erasing head 24a are not projected from the polishing drum 16 and are not polished.

Hereinafter, the conditions for bonding and polishing the head are the same as those in the first embodiment, and the description thereof will be omitted. further,
Since the reproducing heads 5 and 6 and the combination head base 8 are not directly related to the present invention, the description thereof will be omitted.

In the examples of the first and second embodiments, the two multi-head bases 7a and 7b are polished at the same time. However, in order to perform the polishing control more accurately, each multi-head base 7a, 7b is polished. It may be polished. Further, although the multi-magnetic head is the recording head and the erasing head, it is clear that there is no difference between the reproducing head and the erasing head.

[0044]

As described above, according to the present invention,
By using a recording / reproducing combination head and a multi-magnetic head composed of an erasing combination head or a single head, it is possible to separately polish recording / reproducing and erasing combination heads. Conventional VHS V
Similar to the polishing of the combi head used in TR or the like, the front face shape of the head can be polished accurately and easily, and the multi-magnetic head can be provided without lowering the production yield.

Further, by forming a multi-magnetic head with an erasing head whose magnetic head is not so strict in specifications and a recording / reproducing head whose specifications are strict, it is possible to improve the yield due to multi-heading.

Further, the head base is provided with a combination head of a recording or reproducing head and a combination head of an erasing head separately, and the gap depth of the erasing head is larger than the gap depth of the recording or reproducing head. By doing so, it is possible to secure the life of the erasing head and to realize a highly accurate multi-magnetic head capable of absorbing the mounting error of the magnetic head.

[Brief description of drawings]

FIG. 1 is a plan view of a rotary cylinder on which a multi-magnetic head according to a first embodiment of the present invention is mounted, viewed from the back side.

FIG. 2 is a perspective view showing a main part of a rotary cylinder according to the first embodiment of the present invention.

FIG. 3 is an enlarged view of a multi-head base portion to which a recording head and an erasing head according to Embodiment 1 of the present invention are bonded.

FIG. 4 shows a state in which the multi-head base according to Embodiment 1 of the present invention is attached to a polishing drum,
(a) is a plan view showing the relationship between the diameter of the polishing drum and the diameter of the rotary cylinder, and (b) is a partially enlarged view of a recording head and an erasing head attached to the polishing drum.

FIG. 5 is an explanatory diagram of a mounting error when the multi-magnetic head is bonded in the first embodiment of the present invention.

FIG. 6 is a plan view showing a polishing state of a magnetic head attached to the polishing drum according to the first embodiment of the present invention.

FIG. 7 is an X-Ob′-Y sectional view of the polishing drum shown in FIG. 6 in the first embodiment of the present invention.

FIG. 8 is an enlarged plan view showing a portion of a polishing drum and a magnetic head to be polished according to the first embodiment of the present invention.

FIG. 9 is an enlarged cross-sectional view showing a portion of a polishing drum and a magnetic head to be polished according to the first embodiment of the present invention.

FIG. 10 is an explanatory diagram of polishing conditions for absorbing a head mounting error according to the first embodiment of the present invention.

FIG. 11 is a plan view showing a rotary cylinder on which a multi-magnetic head according to Embodiment 2 of the invention is mounted, as seen from the back side.

FIG. 12 is a polishing drum according to a second embodiment of the present invention.
FIG. 6 is a plan view showing a polished state of the magnetic head at 16.

[Explanation of symbols]

1, 1a, 1b, 2, 2a, 2b ... Recording head, 3, 3
a, 3b, 4, 4a, 4b, 24a, 24b ... erasing head, 5
a, 5b, 6a, 6b ... reproducing head, 7, 7a, 7b, 25
a, 25b ... Multi-head base, 8a, 8b ... Combination head base, 9 ... Rotating cylinder, 10 ... Screw, 11 ... Fixed cylinder, 12 ... Magnetic tape, 13, 13a, 13b, 14,
14a, 14b, 15, 15a, 15b ... head window, 16 ... polishing drum, 17 ... outer peripheral surface, 18, 18a, 18b ... suction groove, 19
… Mounting reference disk, 20, 21, 23… Virtual circle, 22
… Polishing tape.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruo Ota 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (9)

[Claims] 1. A first combination head comprising a first magnetic head and a second magnetic head arranged in proximity to the first magnetic head, a third magnetic head and the third magnetic head. It is characterized by comprising a second combination head composed of a fourth magnetic head arranged in close proximity, and a single head base to which the first combination head and the second combination head are bonded. Multi magnetic head. 2. The first and second magnetic heads are magnetic heads for recording or reproducing, or recording and reproducing, and the third and fourth magnetic heads are magnetic heads for erasing. The multi magnetic head according to claim 1. 3. A first combination head composed of a first magnetic head and a second magnetic head arranged close to the first magnetic head, a single head composed of a third magnetic head, and the first magnetic head. 1. A multi-magnetic head comprising a combination head of No. 1 and a single head base to which the single head is bonded. 4. The first and second magnetic heads are magnetic heads for recording or reproducing, or recording and reproducing, and the third magnetic head is an erasing magnetic head. Item 3. The multi-magnetic head according to Item 3. 5. A first magnetic head and a second magnetic head which are arranged close to each other.
4. The multi-magnetic head according to claim 1, wherein a gap position gap between the second magnetic head and the third magnetic head is larger than a gap position gap between the magnetic head and the second magnetic head. 6. A first combination head composed of two closely arranged magnetic heads as one magnetic head, and a second combination head different from the first combination head or one as the other magnetic head. A single head composed of the magnetic heads is adhered onto the same head base, the magnetic head is integrally rotated by a polishing drum on which the head base is mounted, and the magnetic head is wound around the outer peripheral surface of the polishing drum. A polishing method for polishing the front surface of the magnetic head by contacting a polishing tape and the magnetic head, wherein only one front surface of the magnetic head is the outer peripheral surface of the polishing drum. A predetermined amount from the outer peripheral surface of at least the vicinity of the gap of the other magnetic head,
The front surface of the other magnetic head is also polished by causing only the front surface of the other magnetic head to protrude from the outer peripheral surface by a predetermined amount and not protruding the vicinity of the gap of the one magnetic head from the outer peripheral surface. Polishing method. 7. The polishing drum, which is attached to the polishing drum, causes the gap depth direction of the polishing magnetic head to substantially coincide with the center of rotation of the polishing drum, and near the gap of the magnetic head which is not polishing the polishing drum. The diameter of the polishing drum is set to be larger than the diameter of a rotary cylinder on which the multi-magnetic head is mounted for recording / reproducing on / from a magnetic tape so as not to protrude from the outer peripheral surface of the magnetic tape. 7. The front surface polishing method for a magnetic head according to item 6. 8. A first combination head comprising a first magnetic head and a second magnetic head arranged in proximity to the first magnetic head, a third magnetic head and the third magnetic head. A second combination head composed of a fourth magnetic head arranged in close proximity, and a single head base to which the first combination head and the second combination head are bonded, The second magnetic head is a recording or reproducing magnetic head, or a recording and reproducing magnetic head.
The third and fourth magnetic heads are erasing magnetic heads, and when the first, second, third and fourth magnetic heads are adhered to the head base, the erasing magnetic head protrudes. A method of adhering a magnetic head, wherein the amount is made larger than the protruding amount of the recording or reproducing magnetic head. 9. The multi-magnetic head according to claim 2, wherein the gap depth of the erasing magnetic head is larger than the gap depth of the recording and reproducing magnetic heads.