JPH0945563A - Rotary transformer and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary transformer having superior characteristics and productivity to be used for video tape recorders, etc. SOLUTION: On a part of one main face of a magnetic layer 12 and that of a magnetic layer 13 conductive patterns 7, 9 and 37, 39 are formed, respectively and magnetic pattern 6, 39 are formed thereon. Nonmagnetic insulator layers or antiwarp insulator layers 8 and 38 are formed on the conductive patterns 7, 9, 37, 39 with leaving spaces 14 between them, and antiwarp layers 5 and 35 are formed on the opposite face to the one main face. This ensures the production of cores with minimum warp at a batch firing. Accordingly a rotary transformer having a very high electric signal transfer efficiency and superior productivity is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary transformer used in video tape recorders, digital audio tape recorders, digital video tape recorders and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, in a rotary transformer, a rotor core on the rotating side (head side) and a stator core on the fixed side (electronic circuit side), in which coils are formed concentrically with the rotating shaft of a rotating cylinder, are provided on these coil surfaces ( It has a structure in which a main surface) faces each other with an interval of about 20 to 80 μm, and the signal is transmitted between the head and the electronic circuit by this structure.

Conventionally, as a flat plate rotary transformer,
One in which a flat spiral coil formed by winding a conductor around the annular groove of a flat plate-shaped sintered ferrite core having an annular groove is arranged (Japanese Utility Model Publication No. 62-18013), and a film on which a conductor layer pattern is formed is used as a mold. Set on the flat surface of sintered ferrite by degreasing and sintering the green molded body with a conductor layer pattern after injection molding a mixture of ferrite powder and binder (Japanese Patent Laid-Open No. 3-248510). One in which a conductor coil film pattern and a ferromagnetic film are formed (JP-A-2-251106), and one in which an annular groove or a conductor coil pattern is formed by printing on one main surface of a ferrite core (JP-A-1-209708). Japanese Patent Laid-Open No. 3-157906), which is composed of an alternating laminated body of magnetic layers and non-magnetic layers and conductor layers.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The flat spiral coil formed by winding a conductor around a flat plate-shaped sintered ferrite core having an annular groove formed therein, which is described in Japanese Patent No. 013), has an annular groove and an opposing surface of the core due to dimensional variation during ferrite sintering. Since complicated post-processing is required and it is necessary to attach a coil to each channel, the manufacturing cost is very high.

Further, in order to stably insert the winding coil into the annular groove, it is necessary to preliminarily process the annular groove to a depth of about 100 μm and a large size. Therefore, normally, when the stator core and the rotor core are combined with each other. However, there is a problem that the gap of the coil surface becomes large, the magnetic resistance becomes high, the coupling coefficient becomes low, and the transmission efficiency of electric signals decreases.

Further, as shown in JP-A-3-248510, a core obtained by degreasing and firing a molded body prepared by injection molding a mixture of ferrite and a binder on a film on which a conductor layer pattern is formed is a conductor formed by injection molding. The mixture of ferrite powder and binder also enters between the individual conductors in the layer pattern to form a magnetic substance between the conductors, resulting in an increase in leakage flux between the conductors in the conductor layer pattern. There is a problem that the magnetic transmission efficiency with the rotor core is reduced.

On the other hand, Japanese Patent Laid-Open No. 25110/1990 shown in FIG.
No. 6, the conductor coil film patterns 105 and 115 and the ferromagnetic film 1 are formed on the flat surfaces of the stator core 101 and the rotor core 111 made of sintered ferrite.
02 and 112 are formed by the stator core 10
1 and the rotor core 111 and the ferromagnetic films 102 and 1
Since the adhesiveness with 12 is poor, the adhesive films 104 and 114 are required, and the conductor coil film patterns 105 and 115 are thicker than the ferromagnetic films 102 and 112. Therefore, the stator core 101 and the rotor core 111
Although the gap between the upper conductor coil film patterns 105 and 115 becomes smaller, on the contrary, the gap between the stator core 101 and the rotor core 111 becomes larger and the leakage of the magnetic flux becomes larger, so that the coupling coefficient becomes smaller and the electrical conductivity between the adjacent channels becomes smaller. The signal becomes easier to crosstalk,
There was a problem that the loss became large.

Further, Japanese Patent Laid-Open No. 1-20970 shown in FIG.
In the conventional configuration described in Japanese Patent No. 8 publication, the ferrite core 101
Since the annular grooves formed by the conductor coil film patterns 105 and 115 and the ferromagnetic film 102 and 112 are formed by printing only on one main surface of the ferromagnetic films 10 and 111, the ferromagnetic film 10 can be baked.
There is a problem that the ferrite cores 101 and 111 are warped or cracked due to firing shrinkage of 2 and 112. Further, in the case where a plurality of layers are fired, if there is a conductor pattern on the opposite surface, the conductor pattern comes into contact with the main surface of the ferrite core, and there is a problem that the reaction occurs during firing.

Further, in the conventional structure described in Japanese Patent Laid-Open No. 3-157906, since the conductive layers are composed of the alternating laminated layers with the non-magnetic layers, the effective magnetic flux area formed on the facing surface of the core is reduced. Since it is smaller, it is not possible to secure a sufficient coupling coefficient, and since the conductor layer is not formed directly on the magnetic layer, the magnetic transfer efficiency deteriorates, and there is a problem in securing performance such as the coupling coefficient. In order to achieve the thickness, the number of printings of the magnetic layer and the like is increased, so that the problem remains in reducing the number of steps.

It is an object of the present invention to solve the above-mentioned conventional problems and to provide a rotary transformer having high electric signal transmission efficiency and magnetic transmission efficiency and excellent productivity.

[0011]

According to the present invention, in order to solve the above-mentioned problems, a rotor core and a stator core are provided with a conductor pattern, a magnetic pattern and a plurality of concentric circular portions on a part of one main surface of the magnetic layer. A warp prevention insulator layer made of a non-magnetic material is arranged on the conductor pattern, and the warp prevention layer is formed on the opposite surface of the magnetic material layer. Are attached to the rotary shaft so as to face each other.

[0012]

As described above, the warp composed of the conductor pattern, the magnetic pattern, and the non-magnetic material formed on the conductor pattern arranged in a plurality of concentric portions on one main surface of the magnetic layer as described above. By co-firing the anti-insulation layer and the warp-prevention layer formed on the opposite surface of the magnetic layer, the magnetic layer and the conductor pattern are firmly adhered to each other, and the adhesive layer is unnecessary. Further, since the conductor pattern is covered with the non-magnetic warp-preventing insulator layer, it has excellent magnetic efficiency and reliability.
In addition, since the warp prevention insulator layer and the warp prevention layer are provided on the main surface and the opposite surface of the magnetic layer, it is possible to control the warp of the entire core at the time of co-firing, and the magnetic layer Since the take-out conductor pattern formed on the opposite surface or the side surface does not react with the surface on which the core is stacked even during stack firing, it is possible to provide a rotary transformer having excellent productivity.

[0013]

1 is a sectional view of an embodiment of a rotary transformer of the present invention, showing a partially cutaway plan view taken along the line AB of FIG. 3 to 5 are schematic views of partial cross sections of the core showing one embodiment of the present invention.

1 and 2, a rotary transformer according to the present invention has a fixed-side stator core 1 and a rotating-side rotor core 11, which are placed at right angles to a rotating shaft 30, and has a parallelism of 10 μm. The surfaces 3 and 33 are arranged with a space of about 20 to 80 μm so as to face each other, and thereby signal transmission between the head and the electronic circuit is performed. In the stator core 1 on the fixed side, a shaft hole 2 for mounting the rotating shaft 30 and a conductor pattern, that is, a plurality of conductor patterns formed in a plurality of portions corresponding to the number of channels on one main surface 3 of the core. The warp prevention insulator layer 8 made of a non-magnetic material formed on the coil pattern 7 and the short ring 9, and the magnetic field forming the magnetic path on one main surface of the core on which the conductor pattern is not formed. A body pattern 6 is formed, and a warp prevention layer 5 is formed on the opposite surface 4.
The coil pattern 7 is connected to the conductor pattern 20 for extraction by the through hole 10 and electrically connected through the terminal pin 50 and the like, and the terminal block 60 is coupled to the warp prevention layer 5 side. It is configured.

Similarly, in the rotor core 11 on the rotating side,
A shaft hole 32 for mounting the rotating shaft 30 and a main surface 33 of the core
In addition, a part of the one main surface is formed in a plurality of concentric circles corresponding to the number of channels, that is, a conductor pattern, that is, a plurality of coil patterns 37 and a warping prevention insulation formed of a non-magnetic material on the short ring 39. A magnetic layer 36 forming a magnetic path is formed on the body layer 38 and one main surface of the core on which the conductor pattern is not formed, and a warp prevention layer 35 is formed on the opposite surface 34. The pattern 37 is connected to the conductor pattern 22 for taking out by a through hole 40, electrically connected through a terminal pin 55 and the like, and a terminal block 66 is coupled to the warp prevention layer 35 side.

Coil patterns 7, 37 or short rings 9, 39 (both patterns are collectively referred to as a conductor pattern) are formed on one main surface of the magnetic layers 12, 13 serving as the bases of the stator core 1 and the rotor core 11. Then, after forming the warp prevention insulating layer 8 or 38 on them, the magnetic layer 12 or 13 and the conductor pattern 7, 37 or 9, 39 are firmly adhered by degreasing and firing them integrally. However, as a result, the adhesive layer becomes unnecessary.

On the other hand, when the conductor patterns 7, 37 or 9, 39 and the magnetic patterns 6, 36 are formed only on one main surface of the magnetic layers 12, 13, the magnetic layers 12, 13 and the conductor pattern 7 are formed. , 37, 9, 39 and the magnetic material patterns 6, 36 are integrally fired at the same time, warping or cracking may occur due to a difference in density between them or a difference in firing shrinkage behavior between different materials. .

Therefore, according to the present invention, the conductor patterns 7 and 3 are formed.
7 and 9 and 39, the warp prevention insulating layer 8 or 38 and the warp prevention layer 5 or 35 on the opposite surface of the magnetic layers 12 and 13.
By providing the above, the contraction behavior during firing is balanced between the one main surface side and the opposite surface side of the magnetic layers 12 and 13, and the warpage is reduced. In this case, the warp prevention layer 5 or 35 may be formed on the opposite surface entirely or partially.
This may be a warp prevention layer formed by forming a concave portion on the opposite surface of the ferrite molded body by a mold or the like so as to provide a molding density difference on the opposite surface.

The thickness of the magnetic layer 12 or 13 may be the minimum thickness capable of ensuring the performance of the rotary transformer, and may be at least 200 μm or more. Further, as the partial shape of the warp prevention layer 5 or 35, a concentric shape, a non-circular shape,
A rib shape, a spiral shape, a radial shape, a linear shape, a polygonal shape, a dot shape, or a combination pattern thereof can be considered, but all are effective, and the thickness of the warp prevention layer 5 or 35 is
It is also possible to control the warp by changing the material composition.

The warp prevention layer 5 or 35 on the opposite surface does not have to be a magnetic material such as a ferrite material in terms of a magnetic circuit, and a nonmagnetic material, a dielectric material, an insulating material or the like may be used. The warp prevention insulator layer 8 or 38 is preferably made of a non-magnetic material in order to improve the magnetic transfer efficiency because the leakage flux between the conductors in the coil patterns 7 and 37 becomes large.

Further, the height of the coil pattern 7 or 37 in one main surface of the magnetic material layers 12 and 13 is determined by the height of the magnetic material patterns 6 and 6.
If it is higher than the same main surface of 36, the coil patterns 7, 37
The magnetic flux generated from the structure cannot effectively use the portion constituting the magnetic path on the one main surface of the magnetic layers 12 and 13 structurally,
As a result, the magnetic flux leakage increases and the coupling coefficient of the rotary transformer decreases. Further, in the case of repeated firing, the conductor patterns 7, 37, 9, 39 and the surface on which the cores are superposed react with each other, and therefore it is necessary to perform firing separately, which poses a problem in productivity. Therefore, it is preferable that the height of the conductor patterns 7, 37 or 9, 39 be less than or equal to the main surface of the magnetic patterns 6, 36. In addition, the lead-out conductor patterns 7, 37, 9, 3 formed on the opposite surfaces of the magnetic layers 12, 13
Similarly, in order to prevent 9 from reacting to repeated firing,
It is preferably formed on the surface between the magnetic layers 12 and 13 and the warp prevention layer 5 or 35.

The materials contained in the magnetic layers 12 and 13 are ferrite powder or at least one or more of the ferrite powder and the elements constituting the ferrite are metal powders and the balance is an oxide, and a binder, a plasticizer, What added the organic binder, such as a lubricant and a defoaming agent, can be used. Here, the metal powder is for preventing shrinkage during sintering of ferrite. For example, the metal powder such as iron powder, zinc powder, nickel powder, and copper powder is oxidatively expanded to shrink during sintering. Since the shrinkage rate can be suppressed and the shrinkage rate of the ferrite sintered body can be made almost zero, the warpage at the time of firing can be made almost zero.

A ceramic material is excellent as a material for forming the warp prevention insulator layer 8 or 38 and the warp prevention layer 5 or 35, and metal powder for suppressing and controlling firing shrinkage is appropriately selected as described above. It can be added and used.
The difference between the firing shrinkage of the magnetic layers 12 and 13 and the firing shrinkage of the warp prevention insulator layers 8 and 38 and the warp prevention layers 5 and 35 is preferably within 1%.

Conductor pattern 7, 37 or 9, 39
Is silver, which can be fired at a low temperature of 800 ° C. to 1200 ° C.
Palladium, silver-platinum, or copper is preferred. The magnetic path forming portion, that is, the magnetic material pattern 6 or 36 is made of a ferrite material, and it is possible to use the same ferrite material as the magnetic material layers 12 and 13, and a ferrite material having a different composition from the magnetic material layers 12 and 13 or the above-mentioned metal powder is used. It is possible to include it.

With respect to the shapes of the magnetic material patterns 6 and 36, by making the portion exposed on one main surface of the core larger than the internal area, it is possible to secure a large opposing area between the cores, that is, the magnetic path area, which is excellent in magnetic efficiency. It is possible to realize a high-performance rotary transformer with low loss. The conductor pattern 7,
37, 9, 39 and the magnetic material patterns 6, 36 are directly formed on the magnetic material layers 12, 13 by a printing method or a plating method, or a conductor pattern 7, 37, 37, This shape can be created by printing and forming 9, 39 and the magnetic material patterns 6, 36 and transferring and forming them on the predetermined positions of the magnetic material layers 12, 13.

In particular, the magnetic patterns 6, 36 are formed by the above transfer method.
In the case of forming the magnetic pattern 6, as shown in FIG.
Since the shape of 36 can be formed in an inverted trapezoidal shape, the portion exposed on one main surface of the core is larger than the internal area, so that the facing area between cores, that is, the magnetic path area can be secured large, and good characteristics can be realized. Of.

The thickness of the conductor pattern 7, 37 or 9, 39 and the magnetic pattern 6 or 36 is several μm to several tens.
μm, and the difference in thickness between the conductor patterns 7, 37, 9, 39 and the magnetic patterns 6, 36 is 0 to several tens.
μm is preferable in terms of lowering the resistance of the conductor and increasing the density of the magnetic flux. Conductor patterns 7 and 3 to achieve a desired thickness
The formation of 7, 9, 39 and the magnetic material patterns 6, 36 may be overprinted a plurality of times.

The thickness of the magnetic patterns 6, 36, the magnetic patterns 6, 36 and the conductive patterns 7, 37,
In order to obtain the difference in thickness from the magnetic layers 9, 39, the magnetic layers 12, 13
One of the main surfaces may be machined to grind the magnetic material patterns 6 and 36 to realize desired dimensions. Further, the height of the warp prevention insulating layers 8 and 38 is set to the magnetic material patterns 6 and 36.
By lowering the height of the one main surface, the load of the grinding process can be reduced and the productivity can be improved.

The ferrite material is preferably a Ni-Zn-Cu type ferrite which can be fired at a low temperature of 850 ° C to 1200 ° C, but it goes without saying that other ferrite materials are also effective.

When the laminate is punched with a mold before firing,
Magnetic material patterns 6 and 36 formed on one main surface of the laminated body
Of the magnetic material patterns 6, 36 formed near the outer peripheral portion
Since stress concentrates on the end face of the outermost peripheral portion of the laminate during punching, it is preferable to form the laminate at least 0.1 mm or more from the outermost periphery.

Specific examples will be described below. (Embodiment 1) FIG. 3 shows a partial cross-sectional schematic view of a core which is a manufacturing process of an embodiment according to the present invention.

First, the main composition of ferrite powder is Fe ₂ O ₃
49 mol%, ZnO 27 mol%, NiO 13 mol%,
CuO 13 mol% was added to the raw material powder 7
After calcining at 00 ° C. for 3 hours, a calcined powder of Ni—Zn—Cu ferrite was crushed to have an average particle size of 1 μm, and a butyral resin as a binder, a plasticizer, a lubricant, and a quenching agent were prepared. A ferrite slurry was prepared by appropriately adjusting the slurry concentration while adding a foaming agent.

Next, a green sheet having a thickness of 200 μm was prepared from this slurry by using a doctor blade method.
A laminate of a plurality of these green sheets was hot pressed at 80 ° C. to prepare one magnetic green sheet having a thickness of 0.9 mm shown in FIG. After cutting this into a predetermined size, a through hole 10 having a diameter of 0.3 mm was provided at a desired position of the magnetic layer 12 as shown in FIG. Further, as shown in FIG. 3C, a silver paste was screen-printed in order to simultaneously form the take-out conductor pattern 20 and the conductor in the through hole 10.

Next, as shown in FIG. 3D, a spiral coil pattern 7 (pattern width: 100 μm, thickness: 40) is formed on the opposite surface of the magnetic layer 12 as a conductor pattern.
μm) and short ring 9 (pattern width: 200 μm,
(Thickness: 40 μm) was simultaneously screen-printed with a silver paste. In this case, the coil pattern 7 and the through hole 10 are electrically connected.

Further, a magnetic material pattern 6 (pattern width: 200 μm, thickness: 5) of a portion forming a magnetic path on the same surface.
0 μm), a ferrite paste made of ferrite powder having the same composition as the magnetic layer 12 and an average particle diameter of 1.5 μm is provided between the coil pattern 7 and the short ring 9 and between the coil pattern 7 and the inner and outer peripheral surface sides. Also formed an annular pattern by screen printing.

Next, as shown in FIG. 3 (e), a non-magnetic material prepared as a warp prevention insulator layer 8 by mixing a non-magnetic material containing Zn ferrite having an average particle diameter of 1 μm as a main component with a binder having the same composition as described above. The paste was screen-printed on the conductor patterns 7 and 9.

Further, as shown in FIG. 3 (f), FIG.
As the warp prevention layer 5 on the surface opposite to the main surface of the magnetic layer 12 obtained in 1., the same composition as the magnetic layer 12 and an average particle diameter of 2 μm are used.
A ferrite paste prepared from the above ferrite powder was screen-printed on almost the entire surface (thickness: 50 μm) to prepare a molded body A.

Then, as a comparative example, the same method as above is used.
A molded body B having no warp prevention insulator layer 8 and no warp prevention layer 5 was prepared, and each of the molded bodies A and B was cut into a disk shape with an outer diameter of 25 mm and an inner diameter of 4.5 mm by pressing.
After degreasing the formed bodies A and B thus prepared, they are collectively fired in air at 900 ° C. for 3 hours to obtain samples A and B, respectively.
And

The electromagnetic conversion characteristics are evaluated at a measurement frequency of 1 MHz.
In the case where the gap between the stator core and the rotor core was 25 μm. As a result, the warpage of the core of sample A is 5 μm
In contrast to the coupling coefficient of 0.98, in Sample B, the warp of the core reached 300 μm, so that the coupling coefficient could not be measured.

As can be seen from the above, when the warp prevention insulator layer 8 and the warp prevention layer 5 were not present, the amount of warpage during firing was very large, and the measurement and evaluation of electromagnetic conversion characteristics were also impossible. By providing the warp prevention insulator layer 8 and the warp prevention layer 5, it is possible to obtain a sintered core with a minimum of warpage and to obtain a rotary transformer having high electric signal conversion efficiency and excellent performance.

The magnetic layer 12 shown in Example 1 is used.
The warp prevention insulator layer 8 and the warp prevention layer 5 are not limited to those in this embodiment, and these production conditions, that is, the material composition of the powder, the calcination temperature, the particle size and density, the thickness, etc. are appropriately combined with each other. As a result, the warp amount of the fired core can be controlled to almost zero. Further, it has been confirmed that the thickness of the magnetic layer 12 should be at least 200 μm or more, and good performance can be obtained. Although the warp prevention layer 5 is formed by screen printing in this embodiment,
It is also possible to prepare a green sheet by the same method as described above and stack it on the magnetic layer 12.

In this embodiment, since the silver paste is used as the material for forming the conductor patterns 7 and 9, the firing temperature is limited, and a relatively low temperature treatment of about 900 ° C. is premised, so that the magnetic layer 12 and the warp are prevented. The materials for the insulator layer 8 and the warp prevention layer 5 were also made to be compatible with this, but materials other than silver that can be processed up to a relatively high temperature of 900 ° C. or higher, that is, silver-
Needless to say, if a paste of palladium, silver-platinum, or copper is used, the range of material composition selection and design is widened, not limited to this embodiment.

Further, the difference in thickness between the magnetic material pattern 6 and the conductor pattern, that is, the coil pattern 7 and the short ring 9 and the overall thickness of the sintered core are set to a desired dimension, the magnetic material pattern 6 or the warp prevention insulating layer 8. In order to secure sufficient surface properties, the warp prevention layer 5 on the main surface side or the opposite surface of the sintered core may be subjected to post-processing by grinding, respectively or simultaneously.

Further, in this case, the thickness of the warp prevention insulating layer 8 is made thinner than the thickness of the magnetic material pattern 6 in advance to reduce cracks and strains due to processing stress applied during grinding, thereby improving rotary productivity. A transformer can be provided.

(Embodiment 2) FIG. 4 is a partial sectional schematic view of a core showing a manufacturing process of an embodiment according to the present invention.

First, as shown in FIG. 4A, the non-magnetic paste and the magnetic paste prepared in the same manner as in Example 1 were screen-printed in a desired pattern on a substrate such as a PET film 70 and warped. The preventive insulating layer 8 and the magnetic pattern 6 were formed.

Next, as shown in FIG. 4B, the coil pattern 7, the short ring 9, the through hole 10, and the lead-out conductor pattern 20 prepared in the same manner as in Example 1 are formed.
The magnetic layer 12 provided with the warp prevention layer 5 is prepared.

Next, the pattern-printed PET film 70 shown in FIG. 4A is laminated on the magnetic layer 12 by using a heat press or the like as shown in FIG.
As shown in (d), the PET film 70 was peeled off, and the warp prevention insulator layer 8 and the magnetic material pattern 6 were transferred and formed on the corresponding surface of the magnetic material layer 12 to prepare a molded body shown in FIG. 4 (e).

Next, this molded body is pressed to have an outer diameter of 25 m.
After cutting into a disk shape having an m of 4.5 mm and an inner diameter of 4.5 mm and degreasing, it was co-fired in air at 900 ° C. for 3 hours to prepare a magnetic core.

The electromagnetic conversion characteristics were evaluated in the same manner as in Example 1 when the measurement frequency was 1 MHz and the gap between the stator core and the rotor core was 25 μm. However, by providing the warp prevention insulator layer 8 and the warp prevention layer 5, As a result, a sintered core was obtained that has a very small number of sintered cores and high electrical signal conversion efficiency and excellent performance.

The magnetic layer 12 shown in the second embodiment is used.
The warp prevention insulating layer 8 and the warp prevention layer 5 are not limited to those in this embodiment, and these production conditions, that is, the material composition of the powder, the calcination temperature, the particle size and density, the thickness, etc. are appropriately combined with each other. As a result, the warp amount of the sintered core can be controlled to almost zero. Further, it has been confirmed that the thickness of the magnetic layer 12 should be at least 200 μm or more, and good performance can be obtained. In addition, the warp prevention layer 5
In the present embodiment, the film was formed by screen printing, but it is also possible to form a green sheet by the same method as described above and laminate the green sheet on the magnetic layer 12.

Further, as in the first embodiment, the magnetic material pattern 6 is formed.
In order to make the difference in thickness between the coil pattern 7 and the short ring 9 and the overall thickness of the sintered core into a desired dimension, and to sufficiently secure the surface property of the magnetic pattern 6 or the warp prevention insulating layer 8, The warp prevention layer 5 on the main surface 3 side or the opposite surface 4 of the binding core may be subjected to post-processing by grinding, respectively or simultaneously.

Further, in this case, by forming the thickness of the warp prevention insulator layer 8 thinner than the thickness of the magnetic material pattern 6 in advance, cracks and strains due to processing stress applied during grinding can be reduced, and a rotary transformer having excellent productivity can be obtained. Can be provided.

In the second embodiment, the warp prevention insulator layer 8 and the magnetic pattern 6 are formed on the same PET film 70. However, the present invention is not limited to this example, and the warp prevention insulator layer 8 is previously formed on the magnetic layer 12 side. It may be formed by printing.

In this embodiment, since the silver paste is used as the material for forming the conductor patterns 7 and 9, the firing temperature is limited, and a relatively low temperature treatment of about 900 ° C. is a prerequisite, so the magnetic layer 12 and the warp prevention The materials for the insulator layer 8 and the warp prevention layer 5 were also made to be compatible with these, but materials other than silver that can be processed up to a relatively high temperature of 900 ° C. or higher, that is,
Needless to say, if a paste of silver-palladium, silver-platinum, copper or the like is used, the range of material composition selection and design is expanded without being limited to this embodiment.

As shown in FIG. 4C, the feature of the present invention is that since the magnetic material pattern 6 is transferred and formed on the magnetic material layer 12, the magnetic material pattern 6 can have an inverted trapezoidal shape. Since the portion exposed on one main surface is larger than the internal area, the facing area between the rotor core and the stator core, that is, the magnetic path area can be secured large, and good characteristics can be realized.

(Embodiment 3) FIG. 5 is a schematic partial cross-sectional view of a core showing a manufacturing process of an embodiment according to the present invention.

First, the main composition of the ferrite powder is Fe ₂ O ₃
49 mol%, ZnO 27 mol%, NiO 13 mol%,
CuO 13 mol% was added to the raw material powder 7
After calcination at 00 ° C. for 3 hours, pulverized Ni—Zn—Cu-based ferrite calcined powder so that the average particle diameter is 1 μm is prepared.
Metal Fe 65.8 mol%, ZnO 18.
1 mol%, NiO 8.7 mol%, CuO 7.4 mol%
30 parts by weight of the raw material powder mixture was added, and a slurry concentration was adjusted appropriately while adding a butyral resin as a binder, a plasticizer, a lubricant, and a defoaming agent to the ferrite slurry to prepare a ferrite slurry.

Next, a green sheet having a thickness of 200 μm was prepared from this slurry by using a doctor blade method.
A laminate of a plurality of these green sheets was hot pressed at 80 ° C. to form one magnetic layer 12 having a thickness of 0.6 mm.

The main composition of the ferrite powder is Fe ₂ O ₃
50 mol% of ZnO and 50 mol% of ZnO
After calcining at 00 ° C. for 3 hours, pulverized non-magnetic Zn ferrite calcined powder having an average particle size of 1 μm was prepared, and 100 parts by weight of this Zn ferrite calcined powder were mixed with metallic Fe.
Add 30 parts by weight of a mixture of raw material powders of 65.8 mol% and ZnO 18.1 mol%, and add a butyral resin as a binder, a plasticizer, a lubricant, and an antifoaming agent to the slurry concentration while appropriately adjusting the slurry concentration. A slurry was created.

Next, using a doctor blade method, this slurry was subjected to hot pressing at 80 ° C. with a green sheet 48 for forming a non-magnetic warp-preventing insulator layer having a thickness of 100 μm, and further a plurality of the green sheets laminated. Then, one green sheet 4 for forming a warp prevention layer having a thickness of 1.2 mm
It was set to 5.

First, a non-magnetic warp-preventing insulator layer forming green sheet 48 formed as shown in FIG. 5A is used as a base, and a magnetic paste is screen-printed in a desired pattern on the green sheet 48 to form a magnetic material. Pattern 6 was formed.

Next, as shown in FIG. 5B, the magnetic layer 12 having the coil pattern 7, the short ring 9, the through hole 10 and the lead-out conductor pattern 20 prepared in the same manner as in Example 1 was formed. prepare.

Next, as shown in FIG. 5C, a warp-preventing insulator layer-forming green sheet 48 having a printed pattern is formed from above the magnetic layer 12 and from the opposite surface thereof, the warp-preventing green sheet 45. After laminating using a hot press etc. so as to sandwich it, PE as shown in FIG.
The T film 70 was peeled off, and the warp prevention insulator layer 8 and the magnetic material pattern 6 were laminated on the corresponding surface of the magnetic material layer 12 to prepare a molded body shown in FIG. At this time, the warp prevention insulating layer 8 was sufficiently filled up to above the conductor patterns 7 and 9. If the warpage prevention insulator layer 8 is not sufficiently filled here, FIG.
The warp prevention insulating layer 8 may be formed by printing between the magnetic patterns 6 in (a), or may be formed on the coil pattern 7 in FIG. 5 (b).

Next, this molded body is pressed to have an outer diameter of 25 m.
After cutting into a disk shape having an m and an inner diameter of 4.5 mm and degreasing, it was co-fired in air at 900 ° C. for 3 hours to prepare a sintered core.

Next, the warp prevention insulator layer 8 on the main surface side of the sintered core thus obtained is processed by grinding until the magnetic material pattern 6 is exposed as shown in FIG. A core for a rotary transformer was prepared by grinding so that the entire thickness was obtained to a desired size.

The electromagnetic conversion characteristics were evaluated in the same manner as in Example 1 when the measurement frequency was 1 MHz and the gap between the stator core and the rotor core was 25 μm. However, by providing the warp prevention insulator layer 8 and the warp prevention layer 5, As a result, a sintered core was obtained that has a very small number of sintered cores and high electrical signal conversion efficiency and excellent performance.

The magnetic layer 12 shown in Example 3 was used.
The warp prevention insulator layer 8 and the warp prevention layer 5 are not limited to those in this embodiment, and these production conditions, that is, the material composition of the powder, the calcination temperature, the particle size and density, the thickness, etc. are appropriately combined with each other. As a result, the warp amount of the fired core can be controlled to almost zero. Further, it has been confirmed that the thickness of the magnetic layer 12 should be at least 200 μm or more, and good performance can be obtained.

Further, as in the first embodiment, the magnetic material pattern 6 is used.
In order to secure the desired difference in thickness between the coil pattern 7 and the short ring 9 and the overall thickness of the sintered core and sufficient surface properties of the magnetic material pattern 6 or the warp prevention insulating layer 8, the sintered core The warp prevention layer 5 on the main surface side or the opposite surface may be subjected to post-processing by grinding or simultaneously.

Further, in this case, by forming the thickness of the warp prevention insulating layer 8 thinner than the thickness of the magnetic material pattern 6 in advance, cracks and strains due to processing stress applied during grinding can be reduced, and a rotary transformer having excellent productivity can be obtained. Can be provided.

Further, although the magnetic material pattern 6 is formed on the substrate of the non-magnetic warpage preventing insulation layer green sheet 48 in the third embodiment, the present invention is not limited to this example and a sufficient warpage prevention insulation layer 8 is formed. Therefore, it may be directly printed on the conductor patterns 7 and 9 or between the magnetic patterns 6.

In this embodiment, since the silver paste is used as the material for forming the conductor patterns 7 and 9, the firing temperature is limited, and a relatively low temperature treatment of about 900 ° C. is premised, so that the magnetic layer 12 and the warp are prevented. The materials for the insulator layer 8 and the warp prevention layer 5 were also made to be compatible with this, but materials other than silver that can be processed up to a relatively high temperature of 900 ° C. or higher, that is, silver-
Needless to say, if a paste of palladium, silver-platinum, or copper is used, the range of material composition selection and design is widened, not limited to this embodiment.

As shown in FIG. 5F, the feature of the present invention is that since the magnetic material pattern 6 is transferred and formed on the magnetic material layer 12, the magnetic material pattern 6 can have an inverted trapezoidal shape. The portion exposed on one main surface of the core is larger than the internal area, and the facing area between the rotor core and the stator core, that is, the magnetic path area can be secured large, and good characteristics can be realized.

In the rotary transformer of the present invention and the method for manufacturing the same, various materials (composition, density, thickness of magnetic material layer, warp-preventing insulating layer, warp-preventing layer, conductor material), forming method (printing) Method, transfer method, green sheet lamination method), firing conditions (temperature, time, atmosphere, etc.), core shape (outer diameter, inner diameter, gap, conductor pattern, magnetic pattern, through hole shape and size) etc. It is not limited to the examples.

[0075]

As described above, according to the rotary transformer and the method for manufacturing the same of the present invention, the conductor pattern, the magnetic pattern and the warpage preventing insulating layer are formed on a part of the main surface of the magnetic layer. By forming a warp prevention layer on the surface opposite to this one main surface, it is possible to obtain a core with a minimum warp during co-firing, and therefore the electrical signal transmission efficiency is extremely high and the productivity is improved. Is an excellent rotary transformer.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a rotary transformer of the present invention.

FIG. 2 is a partially cutaway plan view of FIG.

3A to 3F are partial cross-sectional schematic views showing a manufacturing process of a stator core according to an embodiment of the present invention.

4 (a) to (e) are schematic partial cross-sectional views showing a manufacturing process of a stator core according to another embodiment of the present invention.

5 (a) to 5 (f) are partial cross-sectional schematic views showing a manufacturing process of a stator core of another embodiment of the present invention.

FIG. 6 is a sectional view showing a conventional rotary transformer.

FIG. 7 is a cross-sectional view showing another conventional rotary transformer.

[Explanation of symbols]

 1 Stator Core 11 Rotor Core 2,32 Shaft Hole 3,33 Main Surface of Core 4,34 Opposite Surface of Magnetic Layer 5,35 Warp Prevention Layer 6,36 Magnetic Pattern 7,37 Coil Pattern 8,38 Warp Insulation Layer 9,39 Short ring 10,40 Through hole 12,13 Magnetic layer 20,22 Extraction conductor pattern 30 Rotation axis 45 Warpage prevention green sheet 48 Warpage prevention insulator layer green sheet 50,55 Terminal pin 60,66 Terminal Stand 70 PET film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Mido 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Akira Hashimoto, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (12)

[Claims] 1. A rotor core and a stator core, each of which has a conductor pattern, a magnetic pattern, and a non-magnetic warp-preventing insulator formed on a plurality of concentric circles on one main surface of the magnetic layer. A rotary body mounted on a rotary shaft such that the main surfaces of the rotor core and the stator core are opposed to each other. Trance. 2. The rotor core and the stator core are formed of a plurality of concentric circles on a part of one main surface of a magnetic layer in which at least one kind of ferrite powder and elements constituting the ferrite is metal powder and the balance is oxide. The laminate includes a conductor pattern, a magnetic pattern, and a warp prevention insulator layer made of a non-magnetic material disposed on the conductor pattern, and a warp prevention layer formed on the opposite surface of the magnetic layer. ,
A rotary transformer mounted on a rotating shaft such that main surfaces of the rotor core and the stator core face each other. 3. The rotary transformer according to claim 1, wherein the magnetic material pattern is made of a magnetic material forming a magnetic path. 4. The area of a portion exposed on the main surface side of each of the rotor core and the stator core facing each other as a magnetic material pattern forming a magnetic path is wider than the internal portion. Rotary transformer. 5. The rotary transformer according to claim 1, wherein the height of the warp prevention insulating layer on the conductor pattern is not more than the height of the protruding surface of the magnetic pattern. 6. The rotary transformer according to claim 1, wherein the magnetic layer has a thickness of 200 μm or more. 7. The warp prevention insulating layer and the warp prevention insulating layer are formed of ceramic powder or ceramic powder and at least one kind of metal powder, and the balance comprising oxides forming ceramics. The rotary transformer according to claim 1 or 2, wherein the body layer is made of a non-magnetic material. 8. The rotary transformer according to claim 1 or 2, wherein the area of the warp prevention layer is equal to or smaller than the area of the magnetic layer, and is formed almost entirely or partially on the magnetic layer. 9. A conductor pattern for extraction is formed on the upper surface of the warp prevention layer on the side opposite to the main surface of the magnetic layer, the surface opposite to the main surface of the magnetic layer and the warp prevention layer, or these conductor patterns are formed. A structure in which the conductive pattern for extraction and the conductive pattern on the one main surface of the magnetic layer are electrically connected to each other by a conductive body through a through hole. The rotary transformer according to claim 1 or 2. 10. A conductor pattern and a magnetic material are provided in a plurality of concentric circular portions on a part of one main surface of a magnetic layer made of ferrite powder and at least one kind of elements constituting the ferrite, and the balance being oxide. A warp prevention insulating layer, a magnetic body, and a warp prevention insulating layer are formed on the body pattern and the warp prevention insulating layer on the conductor pattern, and a warpage preventing layer is formed on the opposite surface of the magnetic body layer. After patterning at least one of the pattern or the warp-preventing layer directly on the magnetic layer or on a plurality of portions on another substrate by a means such as printing,
A method of manufacturing a rotary transformer, which comprises transferring and forming on a corresponding surface of the magnetic layer and firing. 11. A magnetic layer consisting of ferrite alone or a mixture of ferrite powder and at least one kind of elements constituting the ferrite and a balance of the metal and the balance is a concentric circle on a part of one main surface of the magnetic layer. Among the laminates in which a conductor pattern, a magnetic pattern, and a warp-preventing insulator layer are arranged on the conductor pattern on a plurality of portions, and a warp-preventing layer is formed on the opposite surface of the magnetic layer, the warp A concentric magnetic material pattern is formed by printing on a substrate on which an anti-insulation layer is formed, and this is laminated at a predetermined position sandwiching the conductor pattern on the magnetic material layer on which the conductor pattern is formed and baked. After that, a method for manufacturing a rotary transformer in which the warp prevention insulating layer is ground until the magnetic pattern is exposed. 12. The rotary according to claim 10, wherein the difference between the firing shrinkage of the magnetic layer and the firing shrinkage of the warp prevention layer and the warpage preventing insulator layer on the opposite surface of the magnetic layer is within 1%. Method of manufacturing transformer.