JP2000182209A - Multi-track magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively provide a magnetic head which does not deteriorate in reproduction characteristics even abrasion advances and has long life by reducing partial abrasion of the magnetic head. SOLUTION: The magnetic head 1 comprises head elements 3, 4, 5, 6, and 7 and spacers 8, 9, 10, 11, 12, and 13. The head elements are formed of magnetic bodies and the spacers are also formed of the same material with the head elements. Then a thin layer of a nonmagnetic body is provided between the head elements and spacers. Then the head elements and spacers of the magnetic head have nearly the same abrasion characteristics. As the head elements and spacers wear equally, the life of the magnetic head is prolonged eventually.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-track magnetic head including a plurality of head elements in one magnetic head for simultaneously reading signals of a plurality of tracks recorded in a longitudinal direction of a magnetic tape, and a method of manufacturing the same. It is about the method.

[0002]

2. Description of the Related Art Recording information on a magnetic tape can be broadly classified into a method of providing recording tracks in the width direction of the tape and a method of providing recording tracks in the longitudinal direction of the tape. The method of providing the recording tracks in the width direction of the tape can be used for a video tape recorder and the like because the recording capacity of information per unit area of the magnetic tape can be relatively easily increased. On the other hand, the method of providing the recording tracks in the longitudinal direction of the tape has an advantage that the mechanism of the tape traveling is simple, so that the reliability of the tape traveling system can be increased, and it is widely used for a data backup device of a computer. Have been.

In the method of providing recording tracks in the longitudinal direction of the tape, it is usual to provide a large number of tracks along the longitudinal direction of the tape in order to increase the recording capacity per unit area of the magnetic tape. Particularly in the case of a large-capacity recording format, an information track for recording and reproducing hundreds of information is provided on a tape having a width of 1/2 inch. In the case of such a multi-track format, as in the past,
It is impossible to record and reproduce data with a simple fixed head. Therefore, apart from the information tracks for recording and reproducing information, about five servo tracks are provided on the tape. And the recording / reproducing head that traces the information track,
The servo track is used as a reference for positioning on the tape, and the position is actively controlled so that the recording / reproducing head accurately traces the information track.

In this case, the most important thing is how to accurately form the servo track magnetization pattern on the tape. The magnetization pattern of the servo track is a reference for the position of writing data to the tape,
In addition, it is a reference for the reading position of the data recorded on the magnetic tape. The formation of the servo track is performed in a completely independent step from the recording and reproduction of data on the information track. The step of forming a servo track is called a servo track recording step. In the servo track recording step, first, a servo signal is recorded on a servo track of a tape by a servo recording head, and then the servo signal of the recorded servo track is reproduced by a servo reproducing head.
It is designed to verify the accuracy of the servo track.

[0005] Assurance of whether the magnetization pattern of the servo track formed on the tape is accurate is performed by verifying the magnetization pattern of the recorded servo track. That is, a servo track previously recorded on a tape is reproduced by a reference verification device. If the servo track can be reproduced as predetermined, it is considered that the magnetization pattern of the servo track is recorded with predetermined accuracy. Any writing device or writing means may be used as long as the verification can be passed by the reference verification device.

The read head plays an important role in the servo track verification process. The read head used in the servo track verification process is not only abrasion resistant like a normal read head, but it does not have enough wear resistance. Needs to be That is, the reproducing head used in the servo track verification process needs to have a sufficiently smooth surface that comes into contact with the tape even if the wear progresses to some extent.

For reproducing the servo tracks, a multi-track head for reproducing all the tracks at the same time is used. A multi-track head is one in which several (e.g., five) head elements are incorporated in one head assembly, and a typical structure is shown in JP-B-61-41043. The head shown in JP-B-61-41043 has 5 heads.
This is a head in which three head elements are integrated. The five head elements are arranged at a fixed distance from each other, and the space between the head element and the other head elements is filled with a spacer material.

[0008] As another prior art, Japanese Patent Publication No. Sho 61
No. 43767, the multi-track head shown here addresses the problem of wear which is a detriment to the durability of the multi-track head. That is, it is shown that the abrasion resistance of the head can be improved by sufficiently examining the material of the spacer between the adjacent head elements.

On the other hand, Japanese Patent Publication No. 61-8489 discloses a technique for improving the assembling accuracy of a multi-track head, which is another important problem of the multi-track head. This document discloses a multi-track head in which a spacer material is firstly processed with high precision to align head elements with high precision, and the head element is incorporated between them.

In each of the above-described conventional magnetic heads, the material of the head element and the material of the spacer are different. Generally, the head element is made of a magnetic material such as ferrite. The spacer portion is made of a non-magnetic material such as silicon oxide or glass. The reason for using a non-magnetic material for the spacer is that if a magnetic material is used for the spacer, the magnetic flux induced in the head element when reproducing the magnetic tape also passes through the spacer, and no effective reproduction sensitivity can be obtained. It is.

It is assumed that the magnetic head is worn during use. Therefore, the materials for the head element and the spacer are selected from various materials so as to be worn as uniformly as possible. If the magnetic head is not worn evenly and is partially worn, the head element does not come into good contact with the magnetic tape, and the reproduction of signals is hindered. However, actually, the magnetic material and the non-magnetic material originally have completely different physical properties, and also have different wear characteristics. The wear properties of the material are influenced by complex parameters such as the composition of the surface of the magnetic tape, the tension of the magnetic tape, the typical running speed of the magnetic tape, temperature, humidity and atmosphere. No matter which parameter changes,
A combination of a magnetic material and a non-magnetic material having the same wear characteristics and suitable for constituting a magnetic head cannot be easily obtained.

[0012]

With respect to the conventional multi-track magnetic head, a technique has been proposed which exhibits excellent durability characteristics with respect to abrasion resistance when traveling in contact with a tape. However, the conventional multi-track magnetic head has a problem that partial wear occurs on the contact surface of the magnetic head with the tape. When partial wear occurs on the surface of the magnetic head, a level difference occurs between a portion where the wear has progressed and a portion where the wear has not progressed, and the contact surface of the magnetic head with the tape becomes non-uniform. As a result, in order to obtain stable reproduction characteristics, it is necessary to replace the magnetic head with a new one in use time (for example, 1000 hours) which is considerably shorter than the expected life time (for example, 2000 hours). The cause of the partial wear is that the contact surface of the head with the tape is made of various materials having different physical properties related to wear characteristics.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic head in which the wear of the magnetic head is made as uniform as possible on the contact surface with the tape, so that a smooth contact surface can be maintained for a long time. I do.

[0014]

FIG. 1 is an overall front view showing the appearance of a multi-track magnetic head embodying the present invention. 1
Is a magnetic head. 2 is a tape. 3, 4,
5, 6, and 7 are head elements. 8, 9, 10,
11, 12, and 13 are spacers. The head elements 3, 4, 5, 6, 7 are provided with spacers 8, 9, 10, 11,
It is sandwiched between 12 and 13.

FIG. 2 is an enlarged view of the head element 3 and is a cross-sectional view taken from A shown in FIG. The head element 3 includes a first core 14, a second core 15, a third core 17, and a winding 16. Core 14,
Reference numerals 15 and 17 are made of a material having a high magnetic permeability such as ferrite, and constitute a magnetic circuit passing through the winding 16. A void 18 is provided at the leading edge of the cores 14 and 15. The space 18 is a part that comes into contact with the tape 2.

FIG. 3 is a partially enlarged view of the magnetic head 1 shown in FIG. As shown in FIG.
Between the head element 4 and the head element 4, a spacer 9 is provided. Adhesive layers 19, 2 on both sides of the head element 3
0 on both sides of the head element 4
There are 1,22. The bonding layers 19, 20, 21, and 22 are for bonding each head element and each spacer.
The space 18 shown in FIGS. 2 and 3 is a part where the head element 3 actually contacts the magnetic tape 2 and is called a head front. The spacer 9 has a portion having the same height as that of the gap 18 shown in FIG. 2, and this portion is in contact with the magnetic tape 2 like the gap 18 and is called a spacer front.

FIG. 4 is a side view of the magnetic head 1 shown in FIG. The magnetic head 1 is roughly divided into a front core assembly 23 and a rear core assembly 24.
Consists of three parts. Front core assembly 2
3 and the rear core assembly 24 are assembled separately and glued in a final step via an adhesive surface 25.

FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG.
11 and 12 illustrate a manufacturing process of the front core assembly 23, FIG. 13 illustrates a manufacturing process of the rear core assembly 24, and FIG. 14 illustrates a bonding process of the front core assembly 23 and the rear core assembly 24. Is explained.

The front core assembly 2 shown in FIG.
3 is a head element 3,4,5. , 6, 7 and spacers 8, 9, 10, 11, 12, 13. The head element and the spacer are processed separately,
Finally assembled.

FIG. 5 shows a material for forming portions corresponding to the cores 14 and 15 shown in FIG. (A)
It is a top view of core materials 26 and 27, and (b) is a front view. The core material 26 is the material of the core 14 shown in FIG. 3, and the core material 27 is the material of the core 15. Core material 2
6, 27 are made of a magnetic material such as ferrite, for example. The mating surfaces 28 and 29 of the core materials 26 and 27 become portions of the gap 18. This gap 18 needs to maintain a predetermined controlled distance as in the conventional magnetic head. Therefore, a gap material 30 that is the distance of the gap 18 is formed in the material 26 in advance. The material of the void material 30 is the core material 2
There is a close relationship with the physical properties of the materials 6 and 27, and the core material 2
When ferrites 6 and 27 are ferrite, a nonmagnetic material such as silicon dioxide is preferable. Further, the method of forming the gap material 30 can be formed by vapor deposition if the material is silicon dioxide. FIGS. 5C and 5D show a process of bonding the core materials 26 and 27 together. Material 26, 2
7 is accurately abutted, and cylindrical glass rods 31 and 32 over the entire length of the core materials 26 and 27 are inserted.

FIGS. 6A and 6B show processing steps of the core materials 26 and 27 following FIG. 5, wherein FIGS. 6A and 6B are a plan view and a front view, respectively, and FIGS. It is the top view and front view following the process of a) and (b). In (a) and (b), when the core materials 26 and 27 are heated while being abutted, the glass rods 31 and 32 are melted and become adhesives 33 and 34. After cooling, the core materials 26 and 27 are fixed in a state where the core materials 26 and 27 are butted by the adhesives 33 and 34. Next, the upper part of the core material 2 from the line 35 of (a) and (b) is
6 and 27 are cut along the longitudinal direction to obtain the states shown in (c) and (d).

FIG. 7 shows a step subsequent to FIGS. 6C and 6D. (A) is an explanatory view of a slicing step of the core materials 26 and 27, and (b) is a core material 2 shown in FIGS.
6 and 27, (c) is a perspective view of a core material after slicing, and (d) is a core material 2 after slicing shown in (c).
It is a front view of 6 and 27. In the process shown in FIG.
The core materials 26 and 27 from which the unnecessary portions have been cut are changed according to the inclination of the gap 18 (for example, +6 degrees) as shown in FIG.
It is tilted and sliced at equal intervals as shown by line 36. (B) shows the core materials 26 and 27 immediately before slicing.
It is a perspective view of. When the core materials 26 and 27 are sliced, as shown in (c) a perspective view and (d) a front view, a thin core material 4 combining thin core materials 26 and 27 is obtained.
4 can be obtained. Core material 2 shown in FIG.
A large number of thin core materials 44 shown in (c) and (d) can be made from 6, 27.

FIG. 8 shows a process of manufacturing the spacer 9 shown in FIG. FIG. 8A is a plan view of the spacer material 37, and FIG. 8B is a front view of the spacer material 37. The spacer material 37 is made of a material having wear characteristics similar to the core materials 26 and 27 shown in FIG. 5, and is desirably the same material as the core materials 26 and 27. Spacer material 37
Is first sliced at regular intervals, as shown by the line 38.

FIG. 9 shows the spacer material 3 after slicing.
7A is a perspective view, and FIG. 7B is a partially enlarged view thereof. Immediately after slicing, the spacer material 37 is a cube.
2, 43 are provided. Then, the spacer material 37 becomes
The portion 41 is thicker and the portion 40 is narrower across the steps 42 and 43. (B) is an enlarged view of the portion of the step 42 indicated by c in (a). The size of the step 42 is the size of the adhesive layers 19, 20, 21, and 22 shown in FIG.

FIG. 10 shows a process of assembling the thin core material 44 shown in FIG. 7D and the sliced spacer material 37 shown in FIG. 9A. FIG.
(A) shows five thin core materials 44 and a spacer material 37.
Is a plan view of a state where six are alternately combined. FIG.
(B9 is a front view thereof. The position of the step 42 from the bottom surface shown in FIG. 9A is indicated by a broken line 45. (c) is
It is an enlarged view of the portion indicated by d in FIG. It can be seen that a gap is formed between the spacer material 37 and the thin core material 44 by the distance of the step 42. In FIG. 10A, an assembly in which the spacer material 37 and the thin core material 44 are combined is indicated by 46.

FIG. 11 shows a process of bonding the spacer material 37 and the thin core material 44. FIG. 11 (a)
Is a plan view of the first step of bonding, and (b) is a front view. First, the glass rod 47 is placed on the assembly 46. Heat in that state. Then, the glass rod 47
Melts. (C) shows the glass rod 4 on the assembly 46.
FIG. 7D is a plan view of a molten state, and FIG. The molten glass rod 47 in FIG.
It permeates into the gap formed between the spacer material 37 and the core material 44 shown in (c). Next, as shown in FIG. 11D, the assembly 46 is cut along the lines 48 and 49. The position of the line 49 is closer to the surface 40 than the step 42 shown in FIG. That is, the portion below the step 42 is
Cut off completely.

FIG. 12 shows the front core assembly 23.
Shows the final step. As shown in (a) plan view and (b) front view in FIG. 12, when the cutting process along lines 48 and 49 shown in FIG. 11 (d) is completed, a thin assembly 46 is completed.
Next, both sides of the assembly 46 are cut along the lines 50 and 51. Then, like (c) plan view (d) front view,
An elongated front core assembly 23 is obtained. further,
The hatched portion 51 shown in FIG. 12D is ground while the shape is adjusted by polishing. Finally, as shown in the front view (e), the front core assembly 23 is completed.
The front core assembly 23 shown in FIG.
In the sectional view of the magnetic head 1 shown in FIG.
5 corresponds to the part.

FIG. 13 shows the processing steps of the rear core assembly 24 shown in FIG. FIG. 13 (a)
Is a side view of the rear core 52, (b) is a plan view, and (c) is a front view. The rear core 52 is a prism at first, and only the outer shape is processed. The material of the rear core 52 is a magnetic material such as ferrite, for example. First, the rear core 52
A vertical groove 53 is provided over the entire length. This dimension is shown in FIG.
As shown in the vertical groove 53, the width is equal to the cores 14 and 15, and the depth is such that the winding 16 can be accommodated. next,
Lateral grooves 54, 55, 56, 57, 58, 59, 60, 6
1, 62 and 63 are provided. Then, a pair of projections 64, 65, 66, 67, 6
8 are formed. The projection attaches the winding 16 shown in FIG.

FIG. 14 shows the final assembly process. FIG.
(A) is a side view of an assembly process, (b) is a top view.
As shown in (a), first, the front core assembly 2
3 is aligned with the rear core 52. Next, as shown in (b), the front core assembly 23 is
Paste to. At this time, although not shown in FIGS. 14A and 14B, the windings 16 shown in FIG. 2 are inserted into the projections 64, 65, 66, 67, and 68, respectively. Thus, the magnetic head 1 shown in FIG. 1 is completed.

Next, the dimensions of the step 42 shown in FIG. 9 will be described. Focusing on the head element 3 shown in FIG. 3, the size of the step 42 is the thickness N of the adhesive layers 19 and 20.
To form The adhesive layers 19 and 20 are made of a non-magnetic material such as glass and magnetically insulate the cores 14 and 15 of the head element 3 from the spacers 8 and 9. If the adhesive layers 19, 2
When the thickness dimension N of zero is zero and the cores 14, 15 are in close contact with the spacers 8, 9, the magnetic flux of the signal reproduced in the gap 18 passes through the core 17 shown in FIG. Before being converted into a signal, it passes through spacers 8,9. That is,
Short circuit of magnetic flux occurs. If a magnetic flux is completely short-circuited, the magnetic head does not play its role. However, if the thickness dimension N is gradually increased, the magnetic flux of the signal reproduced in the gap 18 will be divided into a portion passing through the short circuit of the spacers 8 and 9 and a portion passing through the core 17. Core 17
, Induces a voltage in the winding 16, and this voltage becomes an effective reproduction signal.

On the other hand, according to the experiment, the size of the adhesive layer was smaller than the recording wavelength of 0.000 compared with the recording wavelength of the magnetic tape.
It was found that if the distance was between 5 and 0.005 mm, a practical reproduction output could be obtained with the dimensions of the adhesive layers 19 and 20 being about 10 times the recording wavelength. Also, the adhesive layer 19,
It has been found that if the size of 20 can be made about 100 times the recording wavelength, an extremely good reproduction output can be obtained. The larger the dimensions of the adhesive layers 19 and 20, the better the reproduction output can be obtained. However, if the dimensions of the adhesive layers 19 and 20 are too large, partial wear of the magnetic head proceeds, and the life of the magnetic head is shortened.

FIG. 15 schematically shows the waveform of a reproduced signal reproduced by the winding 16 shown in FIG. 2, in which the vertical axis indicates the voltage L of the reproduced signal, and the horizontal axis indicates the time T. Is shown. When the traveling speed of the magnetic tape 2 traveling relatively to the gap 18 shown in FIG. 2 is constant, the interval of the time T indicated on the horizontal axis should correspond to the wavelength of the signal recorded on the magnetic tape 2. Can be. In FIG. 15, the recording wavelength on the magnetic tape 2 is Mmm. If the recording waveform on the magnetic tape is a square wave,
Positive voltage waveforms p1, p2 and negative voltage waveforms n1, n2 appear alternately. The voltage Lr is a reproduction limit voltage. That is, for the positive voltage waveforms p1 and p2, if the voltage L of the reproduction signal is smaller than Lr, the voltage waveforms p1 and p2 are buried in the noise signal and reproduction becomes difficult, and if the voltage L is larger than Lr, it is practical. It is a reproduction voltage.

FIG. 16 shows the recording wavelength M = 0.000 on the horizontal axis.
5 is a graph showing the ratio L of the thickness N of the adhesive layer and the recording wavelength M at 5 mm, and the vertical axis represents the voltage L of the reproduced signal. FIG. 17 is a similar graph when the recording wavelength M is 0.005 mm. As shown in FIGS. 16 and 17, when K = N / M is 10 or more, the reproduction limit voltage L
It can be seen that a reproduction output higher than r can be obtained. on the other hand,
If K is increased, the reproduction voltage L becomes larger than Lr and a good reproduction output is obtained. However, the dimension N of the thickness of the adhesive layer is increased and partial wear is apt to progress.

FIG. 18 is a schematic diagram relating to partial wear of the magnetic head. (A) shows the case where the dimension N of the thickness of the adhesive layer is large, and (b) shows the case where the dimension N of the thickness of the adhesive layer is small. The adhesive layers 190a and 2a shown in FIG.
00a, 210a and 220a are the adhesive layers 1 shown in FIG.
The dimensions of the spacer 90a shown in FIG. 10A are larger than those of the spacers 90b shown in FIG. When the material of the head elements 3 and 4 is made of the same or similar material as the spacers 90a and 90b, the effect of the partial wear is smaller in (b) than in (a). Therefore, even if the magnetic head 1 is worn, after the wear, the magnetic head shown in FIG. As shown in (a), when the unevenness of the magnetic head 1 becomes severe, the reproduction output fluctuates, and the reproduction output becomes unstable.

FIG. 19 shows the life of the magnetic head 1 in time when the thickness N of the adhesive layers 19 and 20 shown in FIG. 3 is variously changed. In this case, the life of the magnetic head 1 is set not by the signal reproduction level but by the dropout occurrence rate at a preset time interval. In FIG. 19, the ordinate indicates the thickness dimension N in mm, and the abscissa indicates the measured life. As shown in FIG. 19, if the dimension N of the thickness of the adhesive layers 19 and 20 is N> 1 mm,
There is not much difference from the life of the conventional magnetic head. N <0.5mm
In this case, it can be seen that the life of the magnetic head is greatly affected, and the life can be greatly extended.

From FIGS. 16, 17 and 19, the materials of the cores 14, 15 of the head element 3 and the spacer 9 shown in FIG.
It can be seen that the life of the magnetic head 1 is greatly extended by reducing the value of. This corresponds to the cores 14, 1 shown in FIG.
If the materials of the magnetic tape 5 and the spacer 9 are made the same, the composition of the surface of the magnetic tape, the tension of the magnetic tape, the typical running speed of the magnetic tape, the temperature,
This is probably because complicated parameters such as humidity and atmosphere act in the same way. Further, it can be concluded that the thickness dimension N should be as small as possible in order to minimize the partial wear. In the above description, the case where the thickness dimension N of the adhesive layer present on both sides of each head element is the same on both sides of all head elements is shown, but the thickness dimension N is not necessarily the same. It is not necessary, and a slight variation is allowed for each head element. That is, the thickness dimension N is determined by the steps 42 and 43 shown in FIG. 9, and the steps 42 and 43 need not necessarily be the same.

[0037]

As described above, in the multi-track magnetic head embodying the present invention, the head element and the spacer for determining the distance between the head elements can be made of the same material. The gap can be narrowed. As a result, the wear characteristics of the head element and the spacer can be made the same or very similar, so that even if the wear of the magnetic head progresses, partial wear hardly occurs and a multi-track head with a long life can be obtained. .

[Brief description of the drawings]

FIG. 1 is an overall view of a magnetic head embodying the present invention;

FIG. 2 is a sectional view of a magnetic head.

FIG. 3 is a partially enlarged view of a magnetic head.

FIG. 4 is a side view of a magnetic head.

FIG. 5 is an assembly process diagram of the front core assembly of the magnetic head.

FIG. 6 is an assembly process diagram of the front core assembly of the magnetic head.

FIG. 7 is an assembly process diagram of a front core assembly of the magnetic head.

FIG. 8 is a process diagram of processing a spacer of a magnetic head.

FIG. 9 is a process diagram of processing a spacer of a magnetic head.

FIG. 10 is an assembly process diagram of a front core assembly of a magnetic head.

FIG. 11 is an assembly process diagram of the front core assembly of the magnetic head.

FIG. 12 is an assembly process diagram of a front core assembly of a magnetic head.

FIG. 13 is an assembly process diagram of a rear core assembly of the magnetic head.

FIG. 14 is an assembly process diagram of the magnetic head.

FIG. 15 is an explanatory diagram of a reproduction signal of a magnetic head.

FIG. 16 is a reproduction characteristic diagram of a magnetic head.

FIG. 17 is a reproduction characteristic diagram of a magnetic head.

FIG. 18 is a schematic diagram of wear of a magnetic head.

FIG. 19 is a diagram illustrating the life of a magnetic head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic head 2 Magnetic tape 3, 4, 5, 6, 7 Head element 8, 9, 10, 11, 12, 13 Spacer 19, 20, 21, 22 Adhesive layer 16 Winding 18 Air gap 23 Front core assembly 24 Rear core ·assembly

Claims (4)

[Claims] 1. A multi-track magnetic head for simultaneously reading information on a plurality of tracks recorded in a longitudinal direction of a magnetic tape, a plurality of head elements corresponding to the plurality of tracks, and the head element and another head A spacer that determines the distance between the elements, and a head front that is a part of the head element that contacts the magnetic tape and a spacer front that is a part of the spacer that contacts the magnetic tape are made of a magnetic material of the same material. Multi-track magnetic head characterized by the following: 2. The multi-track magnetic head according to claim 1, wherein an adhesive layer made of a non-magnetic material is provided between said head element and said spacer. 3. When the recording wavelength of a signal recorded on the magnetic tape is M and the thickness dimension of the adhesive layer is N, the value of K when K = N / M is greater than 10 and 1
3. The multi-track magnetic head according to claim 2, wherein the value is smaller than 00. 4. The multi-track magnetic head according to claim 3, wherein the recording wavelength M is 0.0005 mm to 0.005 mm.