JPH0793704A - Magnetic head - Google Patents

Abstract

PURPOSE:To work the case of the magnetic head with high accuracy, to position a core, etc., with high accuracy and to decrease the number of constituting parts. CONSTITUTION:The case 15 is molded of a nonmagnetic material. A partition 16 to segment two magnetic head parts H1 and H2 is formed in the case 15. The core 21 is guided and inserted to positioning ribs 19a formed on the inside surfaces of the case. The positioning surface 21c of the core 21 and the positioning surface 18a of the case come into direct contact with each other and the core 21 is positioned. The core 21 is, therefore, positioned with high accuracy in the case. An elastic piece 16b is formed at the partition 16. The core pieces 21a and 21b are pressurized in a magnetic gap G1 by this elastic piece 16b, by which adequate impedance is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulk type magnetic head for voice / control or audio of a VTR device, in particular, improving the workability of the case and reducing the number of internal parts. Regarding magnetic heads.

[0002]

2. Description of the Related Art FIG. 10 is a front view showing a voice / control magnetic head of a conventional VTR device, and FIG.
12 is a plan sectional view of the magnetic head shown in FIG. 0, FIG. 12 (A) is a front view showing the core and the coil housed in the case, and FIG.
2B is a bottom view of FIG. This magnetic head has a shield case 1 formed of a magnetic material such as permalloy. A front side plate 4 made of stainless steel, which is a non-magnetic material having excellent wear resistance and a low friction coefficient, is attached to the center of the front surface of the shield case 1, and the square holes 1a and 1b are provided above and below the front side plate 4, respectively. Are formed.

A core 2 for recording and reproducing voice and a core 3 for recording and reproducing control signals are housed in the shield case 1. FIG. 11 shows a portion in which the audio core 2 is stored. The core 2 is composed of core pieces 2a and 2b made of ferrite or the like, and a magnetic gap G1 is formed at the joint portion.
A bobbin 5 is mounted on the rear connecting portion of both core pieces 2a and 2b, and a coil 6 is wound around the bobbin 5. The terminals 7, 7 that are electrically connected to the coil 6 project from the rear surface of the shield case 1. The core 2 is positioned and fixed by a holder 10 made of a non-magnetic material provided on the inner surface of the side wall of the shield case 1. And the magnetic gap G1 of the core 2
The portion where is formed is exposed from the square hole 1a at the upper front surface of the shield case 1.

As shown in FIGS. 12 (A) and 12 (B), leaf springs 8 are mounted on the outer sides of both core pieces 2a and 2b so that both core pieces 2a and 2b form a magnetic gap G1. Pressurized towards. By applying this pressing force F, the impedance of the magnetic circuit becomes a predetermined value or more, and desired characteristics can be obtained. The structure of the control signal core 3 is almost the same as the structure of the audio core 2 described above, a magnetic gap G2 is formed at the joint between the core pieces 3a and 3b, and the core pieces 3a and 3b are formed by the leaf spring 8. Pressurized. The portion of the core 3 where the magnetic gap G2 is formed is
It is exposed from the square hole 1b at the lower front surface of the shield case 1. As shown in FIG. 11, the inside of the shield case 1 is filled with resin 9 and the cores 2 and 3 are fixed.

[0005]

However, the above conventional magnetic head has the following problems. (1) The conventional shield case 1 has been drawn by press working. In this press working operation, there is a restriction on the shape that can be worked from the structure of the mold, and the shield case 1 cannot be made into a complicated shape. Further, the size of the entire case is not stable due to springback after pressing, and the thickness of the case varies. Further, since a hard material cannot be drawn, the usable materials are limited to permalloy and the like.

(2) As described above, the shield case 1 is
It will be formed of a soft material such as permalloy that is easy to draw, but a material that is easy to draw will have inferior wear resistance, and permalloy has a friction coefficient It will be expensive. Therefore, as shown in FIG. 10, the front plate 4 such as stainless steel must be separately attached to the portion of the front surface of the shield case 1 where the magnetic tape slides, resulting in a large number of parts and assembling work of the case. Is also getting complicated.

(3) Since the shield case 1 formed by drawing has a simple shape, it is necessary to position the cores 2 and 3 inside or to form a structure for applying a pressing force to the cores. I can't. In addition to this, conventionally, since the shield case 1 is made of a magnetic material such as permalloy, it is impossible to directly contact the cores 2 and 3 with the shield case. Therefore, a holder 10 made of a non-magnetic material is separately provided in the shield case 1,
Positioning each core 2 and 3 and front plate 4 of non-magnetic material
Therefore, it was necessary to position the cores 2 and 3 in the vertical direction of FIG. Further, as shown in FIG. 11, the square hole 1a
In the portions 1 and 1b, it was necessary to provide a gap δ for magnetically blocking the cores 2 and 3 from the shield case 1. For this reason, it is necessary to provide the shield case 1 with parts such as the front plate 4, the holder 10, and the plate springs 8, which results in a large number of components and high cost. Further, since there are many parts for positioning the cores 2 and 3, it is difficult to increase the positioning accuracy of the cores 2 and 3 due to the cumulative tolerance. Particularly in this type of magnetic head, the cores 2 and 3 are fixed in the shield case 1 and then the front surface of the shield case is ground together with the front surfaces of the cores 2 and 3, but the cores 2 and 3 are not accurately positioned. Then, this polishing operation causes variations in the gap depth d shown in FIG. 11, resulting in large variations in the characteristics of the magnetic head. In addition, the gap δ shown in FIG.
Therefore, the positioning work of the cores 2 and 3 is complicated. In addition, the gap δ is apt to be clogged with magnetic powder and dust separated from the magnetic tape, and the sliding reliability of the magnetic tape is reduced.

(4) Conventionally, the inside of the shield case 1 becomes one space, and the resin 9 is filled in the entire area of this one space, so that the volume of the resin 9 is large. Since the stress when the resin material is cured is proportional to the volume, when one space in the shield case 1 is filled with a large volume of resin 9, the curing stress distorts the core and the shield case 1. It is easy to give. Further, stress also acts on the cores 2 and 3 and the coil, and this stress greatly affects the characteristics of the magnetic head. Further, since the amount of the resin 9 injected into the shield case 1 is large, the heat energy at the time of filling the resin is large, which easily deteriorates the characteristics of the magnetic circuit formed by the cores 2 and 3 and the coil.

(5) The voice / control magnetic head shown in FIG. 10 is usually aligned with the erasing head and joined together. Also, some magnetic heads must be combined in the same manner as various types of magnetic heads, or it is necessary to align and bond with parts other than the magnetic head. Also, in the case of a magnetic head for voice / control or a magnetic head for audio, it is necessary to position and fix it on the magnetic head mounting plate. However, since the shield case drawn by pressing has a simple shape, it is impossible to form an uneven portion and an emboss for mutual positioning with the magnetic head and other parts. Therefore, conventionally, when fixing the magnetic head and the magnetic head or the magnetic head and other parts, and further fixing the magnetic head and the mounting plate, the mutual positioning is determined by a jig, and then work such as screwing or welding is performed. It becomes necessary to carry out the process, and the assembling process of the magnetic head becomes very complicated.

The present invention is to solve the above-mentioned conventional problems. By molding the case with a non-magnetic material, various structures can be added to the case, and the core is brought into direct contact with the case. It becomes possible to position and fix each component easily and with high accuracy, and it is an object of the present invention to provide a magnetic head capable of reducing the component cost and the assembly cost.

[0011]

The present invention provides a magnetic head in which a core and a coil wound around the core are housed in a case, and a magnetic gap forming portion of the core is exposed from a hole of the case. The case is formed by molding a non-magnetic material, and the core is positioned by contacting a positioning portion formed in the case.

Further, in the above description, an elastic piece for pressing the cores facing each other in the magnetic gap is formed on the wall portion of the case, or the case is integrally formed with a partition for partitioning the resin filled therein. Is possible.

Further, in the above means, it is preferable that a magnetic plate around which a noise canceling coil is wound is attached to the outside of the case, and the magnetic plate covers the outer surface of the case where the coil is housed.

[0014]

In the above means, since the case is made of a non-magnetic material, it is possible to position the core by directly contacting the case, which eliminates the need for conventional positioning parts. The positioning accuracy is also high. Further, since it is not necessary to provide a gap (δ in FIG. 11) between the core and the periphery of the hole on the magnetic tape sliding surface, magnetic powder, dust, etc. will not adhere to this gap. Further, since the case is molded with a non-magnetic material, it is possible to use a material having excellent wear resistance and a low friction coefficient as the material of the case, and thus it is not necessary to separately provide a conventional front side plate or the like. Further, since the case is molded, the internal structure can be made complicated, so that the structure for positioning the core and other structures can be integrally provided in the case.

Further, since the core can be brought into contact with the case and the case can be formed of a material having a high elastic coefficient, an elastic piece for pressing the cores facing each other in the magnetic gap is integrally formed on the wall portion of the case. However, the elastic force of this elastic piece makes it possible to press the cores with each other in the magnetic gap portion with an optimum force.

Further, by integrally forming a partition for partitioning the resin in the case, the curing stress of the resin can be reduced and the thermal energy of the resin can be reduced, so that the stress on the core and the coil and the influence of heat can be reduced. Therefore, it is possible to prevent deterioration of the characteristics of the magnetic head.

Further, although the case is made of a non-magnetic material and the case itself cannot exert the shielding effect,
The influence of noise can be reduced by providing the noise canceling coil. In particular, by attaching a magnetic plate around which a noise coil is wound to the outside of the case and covering the outer surface of the case where the coil is housed by the magnetic plate, the influence of noise on the internal coil and core can be made extremely small. become.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 is an exploded perspective view of a magnetic head according to a first embodiment of the present invention, FIG. 2 is a front view of the magnetic head shown in FIG. 1 as seen from the tape sliding surface side, and FIG. 3 is a plan view of the magnetic head shown in FIG. FIG. The magnetic head of the first embodiment is for a VTR device, and has a voice / control magnetic head portion H1 and an erasing magnetic head portion H2 integrally formed.
Reference numeral 15 is a case of the magnetic head. In FIG. 1, this case 15 is shown as a perspective view. This case 15
Is a non-magnetic material, such as a stainless steel material, which is molded. As a concrete method of this molding, for example, a so-called metal-metal which is prepared by kneading a metal powder of a non-magnetic material together with a binder, injecting this into a mold to remove the binder with a solvent or heat, and then sintering. Injection molding method can be adopted.

The case 15 formed by molding can have a complicated structure depending on the shape of the mold, unlike drawing by pressing. Therefore, in the case 15, a partition wall 16 extending vertically is formed integrally at almost the center of the inside, and the partition wall 16 allows the head portion H for voice / control to be formed.
A space A forming 1 and a space B forming the erasing head H2 are divided. When stainless steel is used as the material of the case 15, the wear resistance is excellent and the friction coefficient is low, so that the running characteristics of the magnetic tape sliding on the case front surface 15a can be stabilized, and the magnetic tape The front surface 15a of the case is less likely to wear due to sliding. Therefore, the front side plate 4 as shown in the conventional example of FIG. 10 is unnecessary. The metal material forming the case 15 is not limited to stainless steel, and any non-magnetic material having excellent wear resistance and a low friction coefficient can be used.

On the front surface 15a of the case corresponding to the space A,
The square hole 17a is opened in the upper part and the square hole 17b is opened in the lower part.
Further, in the case front surface 15a corresponding to the space B, a square hole 17c is opened at the upper part. A positioning surface 18a is formed in a portion adjacent to the rectangular hole 17a, and similarly, positioning surfaces 18b and 18c are formed in a portion adjacent to the rectangular holes 17b and 17c.
Are formed. Although the positioning surface 18a is shown in FIG. 3, as shown in FIG.
Is a horizontal surface in the left-right direction. On one side wall 15b of the case 1, a positioning rib 19a extending in parallel with the positioning surface 18a is integrally formed on the inner surface of the side wall 15b. Similarly, the positioning surface 18 is formed on the inner surface of the side wall 15b.
Positioning ribs 19b extending in parallel with b sandwiched are integrally formed. On the inner surface of the other side wall 15c of the case 15, positioning ribs 19c extending in parallel with each other with the positioning surface 18c interposed therebetween are formed.

Above the space A, a core 21 for recording and reproducing sound is inserted from the rear. The core 21 is a combination of core pieces 21a and 21b made of ferrite or the like, and a magnetic gap G1 is formed at the joint between the core pieces 21a and 21b. A bobbin 22 is externally inserted in the connecting portion at the rear ends of both core pieces 21a and 21b, and a coil 23 is wound around the bobbin 22. Also bobbin 2
From the terminal 2, terminals 24, 24 extend rearward. The positioning surface 21c is formed on the front edge of one core piece 21b.
Are formed. When the assembly of the core 21, the bobbin 22, and the coil 23 is inserted into the space A, the upper and lower edges (a) of the side surface of the one core piece 21b are aligned with the side wall 15.
It is sandwiched between the positioning ribs 19a on the inner surface of b. When the core 21 is inserted by being guided by the positioning rib 19a, the positioning surface 21c at the front end of the core piece 21b contacts the positioning surface 18a on the case 15 side, and the insertion position of the core 21 in the case front direction (Y direction) is changed. It is decided (see FIG. 3).

Since the case 15 is a non-magnetic material, the core 2
It is possible to bring 1 into direct contact with the case 15. Therefore, as described above, the positioning surface 18a and the positioning surface 2
1c can be brought into contact with each other to be positioned with respect to each other, and the opening dimension of the square hole 17a and the outer dimension of the tip of the core 21 are made to substantially coincide with each other to form a gap G1 of the core 21 as shown in FIG. It is possible to fit the formed portion into the square hole 17a without a gap or with a minimum gap. Also, as described above, the positioning surfaces 18a and 21c
By abutting with each other, the positioning accuracy of the core 21 and the case 15 in the Y direction shown in FIG. 3 can be increased. Therefore, when the front surface 15a of the case 15 is polished together with the tip of the core 21, the depth (gap depth) d of the magnetic gap G1 is prevented from varying, and it is possible to finish with high accuracy. Also, the tip of the core 21 and the square hole 17
Since a gap (δ shown in FIG. 11) is hardly formed between the magnetic tape and a, magnetic particles and dust of the magnetic tape do not adhere to the gap portion, so that the running stability of the magnetic tape can be obtained.

As shown in FIG. 1, an elastic piece 16b separated by a notch 16a is formed in a partition wall 16 at the center of the case 15.
Are formed. When the material of the case 15 is stainless steel or the like, the elastic piece 16b is highly elastic. Therefore, as shown in FIG. 3, when the core 21 is inserted, the side surface 21d of the core piece 21a hits the elastic piece 16b, and the elastic piece 16b presses the core pieces 21a and 21b against each other at the magnetic gap G1. . The pressing force F at this time affects the impedance of the magnetic circuit and further affects the characteristics of the magnetic head, but the pressing force F is 1.3 (k).
g) is appropriate. A control signal core 31 is inserted in the lower portion of the space A. The shape of this core 31 is almost the same as that of the voice core 21, and the core piece 31
A magnetic gap G2 is formed at the junction between a and 31b. A coil 33 is wound around the bobbin 32, and terminals 34, 34 project from the bobbin 32. Core 31
Is guided by being sandwiched between the positioning ribs 19b in the case 15 and into the case 15, and the positioning surface 18b and the positioning surface 31
By hitting c, the case 15 and the core 31 are positioned relative to each other. Further, the tip of the core 31 is fitted into the square hole 17b without any gap. Further, the core pieces 31a and 31b are separated from each other by the notch 16c in the lower portion of the partition wall 16 and the elastic piece 1 is formed.
Pressurized by 6d.

On the other hand, in the space B of the erasing head portion H2,
The erasing core 41 is inserted. The core 41 is composed of core pieces 41a and 41b, and an erasing magnetic gap G3 is formed at the joint portion. A bobbin 42 around which a coil 43 is wound is mounted on the core 41, and terminals 44, 44 project from the bobbin 42. This core 4
1 is also a positioning rib 1 on the inner surface of the side wall 15c of the case 15.
9c is guided and inserted, and the positioning surface 41c formed on the core piece 41b hits the positioning surface 18c of the case and is positioned. In the erasing core 41, it is not necessary to set the pressing force of the core pieces 41a and 41b with high accuracy. Therefore, the elastic piece 16b formed on the partition wall 16 sets the pressure applied to the voice core 21, and the erase core 41 is used.
Does not exert the function of pressurizing. When it is necessary to apply pressure to both the voice core 21 and the erasing core 41, an elastic piece for pressing the erasing core 41 may be provided on the side wall 15c side. Alternatively, the elastic pieces for pressing the cores 21 and 41 may be separately provided on the partition wall 16.

In the embodiment of FIG. 1, the positioning rib 19 is provided only on one side surface of each core 21, 31, 41.
Although the cores are positioned by being guided by a, 19b, and 19c, both side portions of each core may be guided by the positioning ribs. In the process of assembling the magnetic head, the cores 21, 31, and 41 are inserted and positioned in the spaces A and B, respectively, as described above.
After filling the space A and the space B with resin to fix the cores and the coils, the front surface 15a of the case 15 is attached to the cores 2
Polish with the front side of 1, 31, 41. Although the depth d of the magnetic gap is set by this polishing as described above, since the cores are accurately positioned in the Y direction, the gap depth d after polishing is finished with high accuracy.

Next, FIG. 4 shows a second magnetic head according to the present invention.
An example is shown. In this embodiment, the voice / control magnetic head portion H1 and the erasing head portion H2 are separately formed. Case 51 of magnetic head H1
And the case 52 of the magnetic head portion H2 are both formed of a non-magnetic material such as stainless steel by a metal injection molding method. Fitting grooves 51a and 51a are formed above and below the side surface of the case 51, and fitting protrusions 52a and 52a are formed on the side surface of the case 52. The cases 51 and 52 are connected by sliding and fitting the fitting protrusions 52a and 52a and the fitting grooves 51a and 51a, both of which have a V-shaped cross section. Since the fitting grooves 51a, 51a and the fitting protrusions 52a, 52a are both formed with high precision by molding, the cases 51 and 52, that is, the magnetic head portions H1 and H2 are highly precise and simple. It will be connected by work.

A square hole 51d is formed in the upper part of the front surface of the case 51. Also, both side walls 51b and 51 of the case 51 are
Positioning ribs 51e and 51f are formed on both inner surfaces of c. The voice core 21 is inserted into the space A with its both side edges being guided by the positioning ribs 51e and 51f. Further, similarly to the embodiment shown in FIG. 1, the positioning of the core 21 and the case 51 in the Y direction can be performed by the positioning surface formed on at least one of the core pieces 21a and 21b and the positioning surface formed on the inner surface of the case 51. Done. The case 51 is not formed with the elastic piece as shown in FIG. 1, but is provided with a separate leaf spring member 53 for pressing the core pieces 21a and 21b. Supporting pieces 53 a are formed on both sides of the leaf spring member 53. The support piece 53a is adapted to fit on the upper and lower edges of the positioning ribs 51e and 51f. And both the oppression pieces 53 formed between the support pieces 53a.
The core pieces 21a and 21b are pressed by a predetermined pressing force F by b and 53b. Further, the portion of the core 21 where the magnetic gap G1 is formed passes through the notch 53c formed in the leaf spring member 53 and is fitted into the square hole 51d without any gap. Although the mounting structure of the control signal core 31 and the erasing core 41 is not shown in FIG. 4, the mounting structure of the cores 31 and 41 in the cases 51 and 52 is the same as that of the audio core 21. Is the same.

FIG. 5 is a longitudinal sectional view of a magnetic head according to the third embodiment of the present invention. FIG. 5 shows a magnetic head unit H1 for voice / control. The case 55 is manufactured by molding such as metal injection molding as in the above-described embodiments, and the partition plates 55a and 55a are integrally formed inside the case 55. The internal space of the case 55 is partitioned by the partition plates 55a and 55a to be divided into A1, A2, and A3. A voice core 21, a bobbin 22, etc. are inserted in the uppermost partition space A1, and a control signal core 31, a bobbin 32, etc. are inserted in the lowermost partition space A3. The respective cores 21 and 31 are positioned by the same positioning ribs and positioning surfaces as those shown in the above-mentioned respective embodiments.

The partition spaces A1 and A3 are filled with a resin 56 for fixing the cores 21, 31, etc.,
The resin 56 is also filled in the central partition space A2. In this embodiment, the volume of the resin 56 filled in each of the partition spaces A1, A2, A3 is divided to be small. The internal stress at the time of curing the resin 56 is proportional to the volume, but since the resin in the partition spaces A1, A2 and A3 has a small volume, the curing stress is higher than that of the conventional example and the examples shown in FIGS. 1 and 4. Becomes very small. Therefore, the influence of the curing stress of the resin on the core and the coil portion is reduced.
Further, since the resin 56 is dispersed, the heat energy radiated at the time of resin filling and curing is smaller than that in the case of the integrated space A, and the core and the coil are less likely to be affected by heat. Therefore, the characteristics of the magnetic circuit are less likely to deteriorate due to stress or heat. Further, in FIG. 5, resin may be filled only in the partition spaces A1 and A3, and the central partition space A2 may be left without being filled with resin.

FIG. 6 is a perspective view showing a magnetic head according to the fourth embodiment of the present invention. In this embodiment, the case where the magnetic head portion H1 for voice / control is constituted by a single body is shown. The case 58 of the magnetic head portion H1 is molded in the same manner as described above, and in this molding step, a plurality of mounting projections 58a are integrally formed on the lower surface of the case 58 by projection molding. On the other hand, a plurality of mounting holes 59a are formed in the mounting plate 59 to which the magnetic head portion H1 is mounted. The case 58 and the mounting plate 59 are positioned relative to each other by inserting the protrusion 58a into the mounting hole 59a. It The case 58 and the mounting plate 59 can be fixed by a simple operation, for example, by caulking the projection 58a on the lower surface of the mounting plate 59, or by welding the projection 58a and the mounting plate 59.

It should be noted that the case 58 can be formed with projections or recesses of various structures for attachment, for example, an emboss or the like for electric resistance welding can also be formed. Alternatively, it is possible to provide a plurality of hook-shaped protrusions elastically fitted in the holes of the mounting plate 59 on the bottom of the case 58. In each of the above embodiments, the case is molded with a non-magnetic material such as stainless steel. Therefore, the case itself does not have a shield function, and it is preferable to separately take measures against external noise.

FIG. 7 shows a structure in which a noise canceling coil is installed outside the case as a countermeasure against noise. In FIG. 7, a case 15 having the same structure as that shown in FIG. 1 is shown. Engagement protrusions 15f, 15f are integrally formed on the upper edge portions of the outer surfaces of both side walls 15b and 15c of the case 15. A noise canceling coil assembly 60 is attached to the top of the case 15. The assembly 60 is provided with a U-shaped metal plate 61 that serves as a coil core, and both side plates 61 of the metal plate 61 are provided.
Fitting holes 61b and 61b are formed in a and 61a.
A bobbin 62 is attached to the center of the metal plate 61, and a cancel coil 63 is wound around the bobbin 62. Further, terminals 64, 64 project from the bobbin 62.

By the elastic force of both side plates 61a, 61a, the fitting holes 61b, 61b and the engaging projections 15f, 15f are fitted, so that the assembly 60 is fixed to the upper part of the case 15. In this assembly 60, the external noise causes the metal plate 6
By being guided to 1, the density of noise magnetic flux passing through the cancel coil 63 is increased. Then, an electromotive force opposite to that of the coil 23 wound around the audio core 21 is generated in the cancel coil 63, and the electromotive force due to noise in the cancel coil 63 and the coil 23 is canceled. Particularly in the embodiment of FIG. 7, the metal plate 6
1 has a structure in which the voice core 21 and the coil 23 are covered on the three sides above and on both sides.
The external noise that tries to enter the coil 23 and the metal plate 6
It can lead to 1, and effective noise removal can be performed. Further, the magnetic head has a specific directivity with respect to external noise, and has a characteristic that it is weak against external noise from a certain direction and strong against external noise from other directions. Therefore, the areas of the side plates 61a and 61a on both sides of the metal plate 61 are made different from each other, and the side plates 6 positioned in a direction weak against external noise due to the directivity.
By increasing the area of 1a, it is possible to cope with the directivity to noise peculiar to the magnetic head.

FIG. 8 shows an assembly process of the noise canceling coil assembly 60. The central portion 61c of the U-shaped metal plate 61 has a narrow width. Further, the bobbin 62 is formed with a split groove 62a that divides the bobbin at the upper limit. The central portion 6 of the metal plate 61 is placed in the split groove 62a.
By sandwiching 1c, the metal plate 61 and the bobbin 62 are combined. After this combination is performed, the cancel coil 63 is wound around the bobbin 62, and the assembly 60 is completed.

FIG. 9 shows another structure of the assembly 60. In this case, the cancel coil 63 is wound around the bobbin 62 in advance. Further, the bobbin 62 is formed with a square hole 62b penetrating in the axial direction thereof. The metal plate 61 is divided into two parts, and each metal plate is integrally formed with a side plate 61a and an elastic piece 61d having an engaging claw 61e. The assembly of the assembly 60 is completed by inserting both elastic pieces 61d from both ends of the square hole 62b and engaging the engaging claws 61e with the openings of the square hole 62b. The cancel coil may be provided inside the case instead of being provided outside the case. The magnetic head of the present invention is
It is not limited to voice / control, but may be for audio or other purposes.

[0036]

According to the first aspect of the present invention, since the case is made of a non-magnetic material, the core can be brought into direct contact with the case for positioning, and a positioning component as in the prior art. Is unnecessary, the number of parts can be reduced, and the positioning accuracy of the core is improved. Also, since there is no need to provide a gap between the core and the periphery of the hole in the case,
Magnetic particles and dust do not adhere to this gap. Further, since the case is molded with a non-magnetic material, it is possible to use a material having excellent wear resistance and a low friction coefficient as the material of the case, and thus it is not necessary to separately provide a conventional front side plate or the like. Further, since the case is molded, the internal structure can be made complicated, so that the structure for positioning the core and other structures can be integrally provided in the case.

According to the second aspect of the present invention, since the core is pressed by the elastic piece formed integrally with the case, a leaf spring for pressing the core as in the conventional case is unnecessary.

According to the third aspect of the present invention, since the partition for partitioning the resin is integrally formed in the case, the curing stress of the resin can be reduced and the thermal energy of the resin can be reduced, so that the stress and heat applied to the core and the coil can be reduced. To eliminate the effect of
It is possible to prevent the deterioration of the characteristics of the magnetic head.

According to the fourth aspect of the present invention, the influence of noise can be reduced by providing the noise canceling coil. In particular, by attaching a magnetic plate around which a noise coil is wound to the outside of the case and covering the outer surface of the case where the coil is housed by the magnetic plate, the effect of noise on the internal coil and core can be minimized. .

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of a magnetic head according to the present invention,

FIG. 2 is a front view of the magnetic head of the first embodiment,

FIG. 3 is a plan sectional view of the magnetic head of the first embodiment,

FIG. 4 is an exploded perspective view showing a second embodiment of the magnetic head according to the present invention,

FIG. 5 is a vertical sectional view showing a third embodiment of the magnetic head of the present invention,

FIG. 6 is a perspective view showing a fourth embodiment of the magnetic head of the present invention,

FIG. 7 is an exploded perspective view showing a state in which a noise canceling coil is installed outside the case of the magnetic head of the first embodiment,

FIG. 8 is a perspective view showing an example of a structure of a noise canceling coil assembly;

FIG. 9 is a perspective view showing another example of the structure of the assembly of the noise canceling coil,

FIG. 10 is a front view of a conventional magnetic head,

FIG. 11 is a plan sectional view of a conventional magnetic head,

12A is a front view showing a core pressure structure of a conventional magnetic head, FIG. 12B is a bottom view thereof, FIG.

[Explanation of symbols]

 H1 voice / control magnetic head portion H2 erasing magnetic head portion A magnetic head portion H1 space B magnetic head portion H2 space 15 case 15a case front surface 15b, 15c case side wall 16 partition wall 16b, 16d elastic piece 17a, 17b , 17c Square hole 18a, 18b, 18c Positioning surface 19a, 19b, 19c Positioning rib 21 Voice core 21c Positioning surface 22 Bobbin 23 Coil 31 Control signal core 31c Positioning surface 32 Bobbin 33 Coil 41 Erasing core 41c Positioning Surface 42 Bobbin 43 Coil G1, G2, G3 Magnetic gap 51, 52 Case 51a Fitting groove 52a Fitting protrusion 55 Case 55a Partition plate 58 Case 58a Mounting protrusion 60 Noise canceling coil assembly 61 Metal plate 62 Down 63 cancel coil

Claims (4)

[Claims] 1. A magnetic head in which a core and a coil wound around the core are housed in a case, and a magnetic gap forming portion of the core is exposed from a hole of the case, wherein the case is made of a non-magnetic material. A molded magnetic head, wherein the core is positioned in contact with a positioning portion formed in the case. 2. The magnetic head according to claim 1, wherein an elastic piece for pressing the cores facing each other in the magnetic gap is formed on a wall portion of the case. 3. The magnetic head according to claim 1, wherein the case is integrally formed with a partition for partitioning the resin with which the case is filled. 4. The magnetic head according to claim 1, wherein a magnetic plate around which a noise canceling coil is wound is attached to the outside of the case, and the outer surface of the case where the coil is housed is covered by the magnetic plate.