JPH0845758A - Flat rotary transformer and its manufacture - Google Patents

Abstract

PURPOSE:To provide a flat rotary transformer excellent in characteristics which is used in a video tape recorder or the like. CONSTITUTION:A conductor pattern 7 (37) and a ferromagnetic protruding pattern 8 (38) composed of ferrite are formed on the main surface 3 (33) of a molded object 1 (31) composed of ferrite and additive. On the opposite surface, a warp protecting layer 5 (35) is formed. By degreasing and baking the molded objects as an unified body, a flat rotary transformer excellent in productivity wherein warp is little and the transmission efficiency of an electric signal is high can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat plate rotary transformer used in electronic equipment such as video tape recorders and digital tape recorders for supplying and extracting electric signals from a rotating body to an external stationary body and a method of manufacturing the same. .

[0002]

2. Description of the Related Art Generally, in a rotary transformer, a rotor core on a rotating side (head side) and a stator core on a fixed side (electronic circuit side), in which coils are formed concentrically with a drum shaft of a rotary head, are provided on their coil surfaces. The structure is such that the (main surface) faces each other with a space of about 20 to 80 μm, and the signal is transmitted between the head and the electronic circuit.

Conventionally, a flat plate rotary transformer has a flat ferrite core of a sintered body in which an annular groove is formed and a flat spiral coil formed by winding a conductor around the annular groove is arranged (Japanese Utility Model Publication No. 62-18013). A film on which a conductor pattern is formed is set in a mold of an injection molding machine, a mixture of sinterable ferrite and a binder is injection molded, and then degreased and fired (JP-A-3-248510) or fired. A structure in which a conductor coil film pattern and a ferromagnetic film are formed on a flat surface of a bound ferrite (JP-A-2-2
5106), an annular groove was formed by printing only on one surface of the ferrite core (JP-A-1-209708).

[0004]

An annular groove is formed in the flat ferrite core of the above sintered body, and a flat spiral coil formed by winding a conductive wire around this annular groove is arranged. Therefore, a complicated post-processing is required, and it is also necessary to mount a coil, so that the manufacturing cost is very high.

Further, since it is necessary to machine the annular groove to a depth of about 100 μm and a large size in advance so that the winding can be stably inserted into the annular groove, the gap between the coil surfaces of the stator core and the rotor core is usually large. The magnetic resistance becomes high, the coupling coefficient when the stator core and the rotor core are combined is about 0.95, the total inductance is about 4.5 μH, and the loss is about -3.6 dB, and the electrical signal transmission efficiency is There was a problem that it decreased.

A film on which a conductor pattern is formed is set in a mold of an injection molding machine, a mixture of sinterable ferrite and a binder is injection molded, and then degreased and sintered. The mixture of the sinterable ferrite and the binder enters between the individual conductors to form a ferromagnetic material between the conductors, and as a result, the magnetic flux density between the individual conductors of the conductor pattern in one core is reduced. There was a problem that the magnetic transfer efficiency between the rotor core and the rotor core was reduced.

On the other hand, in the conventional structure shown in FIG. 8, a stator core 101 and a rotor core 1 made of sintered ferrite.
Conductor coil patterns 105 and 115 on the flat surface of 11
And the ferromagnetic films 102 and 112 are not formed, the adhesion between the stator core 101 and the rotor core 111 and the ferromagnetic films 102 and 112 is poor, so that the adhesive film 104 is formed.
And 114 are required, and the conductor coil patterns 105 and 115 have ferromagnetic films 102 and 112.
The conductor coil patterns 105 and 115 are thicker than the ferromagnetic films 102 and 112. Therefore, although the gap between the conductor coil patterns 105 and 115 on the stator core 101 and the rotor core 111 becomes smaller, on the contrary, the gap between the stator core 101 and the rotor core 111 becomes larger and the leakage of magnetic flux becomes larger, so that the stator core 101 and the rotor core 111 are combined. The coupling coefficient at that time is as small as about 0.95, and electrical signals between adjacent channels are easily cross-talked, resulting in loss of about −.
There is a problem that it becomes as large as 3.98 dB.

In the conventional structure shown in FIG. 9, the ferromagnetic film 10 is formed only on one surface of the ferrite cores 101 and 111.
Since the annular grooves of 2 and 112 are formed, the protrusions of the ferromagnetic films 102 and 112 and the conductor coil patterns 105 and 115 and the ferrite cores 101 and 1 are formed during the integral firing.
There was a problem that the molded body was warped or cracked due to a difference in density of the molded body from the molded body of No. 11 or the like. Further, when a plurality of layers are fired, there is a problem that when the lead-out conductor pattern exists on the opposite surface, the lead-out conductor pattern on the opposite surface comes into contact with the main surface to cause a reaction during firing.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above conventional problems and provide a flat plate rotary transformer having high electric signal transmission efficiency and magnetic transmission efficiency and excellent productivity.

[0010]

In order to solve the above-mentioned problems, the present invention forms a conductor pattern and a ferromagnetic convex pattern made of ferrite on one main surface of a molded product made of ferrite and an additive. (EN) A flat plate rotary transformer in which a molded body having a warp prevention layer formed on the opposite surface is integrally degreased and sintered.

[0011]

[Function] As described above, a molded body in which a conductor pattern and a ferromagnetic convex pattern made of ferrite are formed on one main surface of a molded body made of ferrite and an additive, and a warpage prevention layer is formed on the opposite surface is integrally formed. By degreasing and sintering in step 1, the ferrite core and the conductor pattern and the ferromagnetic material pattern are firmly adhered to each other, and the adhesive layer is unnecessary. Also, by molding the conductor pattern and the ferromagnetic pattern to be lower than the conductor pattern or the recesses on the main surface of the molded body, the gap between the stator core and the rotor core is reduced, and the magnetic resistance is reduced. Crosstalk of signals is less likely to occur, loss is reduced, and transmission efficiency of electric signals can be improved and loss can be reduced.
Further, by providing the warp prevention layer on the opposite surface, it is possible to control the warp during integral firing, and when the take-out pattern is present on the opposite surface, the take-out conductor pattern on the opposite side is mainly used during repeated firing. Since there is no direct contact with the surface, no reaction occurs during firing, and repeated firing is possible.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially cutaway plan view of an embodiment of a flat plate rotary transformer of the present invention, FIG. 2 is a sectional view taken along line AB of FIG.
3 to 7 are schematic views showing other embodiments of the present invention.

1 and 2, in the flat plate rotary transformer of the present invention, a rotor core 31 on the rotating side (head side) and a stator core 1 on the fixed side (electronic circuit side) are parallel to each other concentrically with the drum shaft 20. Approximately 20 so that the main surfaces 3 and 33 finished to a degree of 10 μm face each other.
The signals are transmitted between the head and the electronic circuit by arranging them at intervals of about 80 μm. In the stator core 1 on the fixed side, a shaft hole 2 for mounting the drum shaft 20, a plurality of conductor patterns 7, a ferromagnetic material pattern 8 and a short ring 10 are formed on one main surface 3, and the opposite surface 4 is formed.
A warp prevention layer 5 is formed on the substrate, and the warp prevention layer 5 is electrically connected via a conductor pattern for extraction, a terminal pin, or the like.

Similarly, in the rotor core 31 on the rotating side,
A shaft hole 32 for mounting the drum shaft 20, a plurality of conductor patterns 37, a ferromagnetic material pattern 38, and a short ring 40 are formed on one main surface 33, and a warp prevention layer 35 is formed on the opposite surface 34. Is a conductor pattern for taking out,
It is configured to be electrically connected via a terminal pin or the like.

When the conductor pattern 7 or 37 is formed on one main surface of the molded body to be the stator core 1 or the rotor core 31, the conductor pattern 7 or 37 and the ferromagnetic pattern 8 or 38 are formed on one main surface of the molded body. In the case where a concave portion is formed on one main surface of the molded body and a conductor pattern is formed in this concave portion, the molded body and the conductor pattern 7 or 37
By integrally degreasing and sintering and, the ferrite core 1 or 31 and the conductor pattern 7 or 37 and the ferromagnetic material pattern 8 or 38 are firmly adhered to each other, and the adhesive layer becomes unnecessary.

When the conductor pattern and the ferromagnetic material pattern are formed only on one main surface of the molded body, the difference in the molding density between the ferrite molded body and the convex pattern or the shrinkage behavior of the firing of the conductor pattern and the ferrite molded body during firing. Due to the difference or the like, it may warp in one direction or crack may occur during firing. Therefore, the warp prevention layer 5 or 35 is provided on the opposite surface.
By providing, it is possible to reduce warpage by balancing on the surface opposite to the one main surface. Warp prevention layer 5 or 35
May form a pattern on the opposite surface entirely or partially.

Further, the warp prevention layer may be formed by forming a concave portion on the opposite surface with a mold or the like so as to give a difference in molding density to the opposite surface. As a partial pattern shape of the warp prevention layer 5 or 35, FIGS.
It is conceivable that, as shown in Fig. 7, only the extraction conductor pattern is formed in the recess, concentric circles, non-circles, ribs, spirals, radials, straight lines, polygons, points, etc. It is effective, and the warp can be controlled by changing the thickness of the warp prevention layer 5 or 35.

The warp prevention layer 5 or 35 on the opposite surface does not have to be a ferromagnetic material such as a ferrite material in terms of a magnetic circuit, and a nonmagnetic material, a dielectric material, a resistance material or the like may be used.

When the height of the conductor pattern 7 or 37 on the one main surface is higher than the depth of the recessed groove on the same surface, the magnetic flux generated from the conductor pattern easily leaks from the convex portion of the ferromagnetic material and the coupling coefficient becomes low. Further, the conductor pattern reacts during the repeated firing.
Therefore, it is preferable that the height of the conductor pattern 7 or 37 on one main surface is equal to or less than the depth of the recessed groove on the same surface. In addition, in order that the lead-out conductor pattern on the opposite surface also does not react during repeated firing, it is preferable that the conductor pattern is formed in the concave portion of the warp prevention layer 5 or 35 and the height of the conductor pattern is not more than the depth of the concave groove.

Additives for the molded product include organic binders such as binders, plasticizers, lubricants, and defoamers, or inorganic binders containing at least the same elements as the constituent elements of ferrite. Any thing can be used. Here, the inorganic binder is for preventing shrinkage during sintering of the ferrite, for example, iron powder, zinc powder, nickel powder, copper powder and the like metal oxide powder is oxidatively expanded to shrink during sintering. By canceling, the shrinkage rate of the sintered body can be made almost zero, and in the case of only the molded body having no pattern formed on both surfaces, the warpage during firing can be controlled to several μm or less.

The conductor pattern 7 or 37 is 850 to 1
Silver, silver-palladium, silver-capable of low temperature firing at 200 ° C
Platinum or copper is preferred. The ferromagnetic material pattern 8 or 38 is made of a ferrite material, and may be the same ferrite material as the molded body, or may be a ferrite material having a different composition from the molded body or a material containing the above-mentioned additive. The thickness of the conductor pattern 7 or 37 and the ferromagnetic material pattern 8 or 38 is several μm to several tens of μm, and the difference in thickness between the conductor pattern 7 or 37 and the ferromagnetic material pattern 8 or 38 is 0 to several 10 μm. It is preferable in terms of lower resistance of the conductor and higher density of magnetic flux.

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

When the molded body is punched out by a die or the like before firing, if a convex pattern portion is present on the outermost peripheral portion of one main surface, stress is concentrated on the end face of the outermost peripheral portion at the time of punching, so that the pattern is missing. Therefore, it is preferable to form the convex portion at least 0.1 mm or more from the outermost periphery.

Specific examples will be described below. (Example 1) NiZnCu-based ferrite calcined powder A was prepared by calcination of raw material powders blended so that the main composition was as follows, at 700 ° C for 3 hours, and then pulverized to have an average particle size of 1 µm. Then, the slurry concentration was adjusted while adding the additive A (binder, plasticizer, lubricant, defoaming agent) to prepare the slurry A. The compositions of the calcined ferrite powder A and the additive A are shown below.

Calcined ferrite powder A; Fe ₂ O ₃ 49 mol% ZnO 27 mol% NiO 13 mol% CuO 11 mol% …… 100 kg Additive A; ・ Binder butyral resin …… 140 liters ・ Plasticizer …… 1.5 kg ・ Lubricant ...... 4 kg ・ Antifoaming agent …… 1.5 liters This slurry A was applied to a thickness of 2 using a doctor blade method.
A green sheet of 00 μm was produced. A laminate of these green sheets was hot pressed at 120 ° C. to obtain a green sheet having a thickness of 0.95 mm. After cutting this green sheet into a predetermined size, a conductor pattern (pattern width 70 μm, thickness 36 μm) is formed on one main surface of the molded body.
As a spiral pattern with silver-palladium paste ink, short ring coil (pattern width 200μ
m, thickness 36 μm) by screen printing with a silver-palladium paste ink, and as a ferromagnetic pattern (pattern width 200 μm, thickness 36 μm) on the same surface, a ferrite ink of the same composition as the core is used to form an annular pattern of a conductor pattern. Screen printed in between.

Thereafter, a warp prevention layer was screen-printed with a ferrite ink having the same composition as the core on the entire opposite surface (thickness 15 μm), and the respective shapes shown in FIGS. Molded bodies B to F each having a concentric circle shape, a radial shape, a linear shape, a polygonal shape, and a dot shape screen-printed on the portion (thickness 25 μm), and a molded body G on which a warp prevention layer is not printed are prepared, and after printing, respectively. It was cut into a disk shape having an outer diameter of 25.56 mm and an inner diameter of 4.54 mm by pressing. After degreasing the molded bodies A to G produced in this manner, they were fired in air at 970 ° C. to obtain samples A to G, respectively.
And

The electromagnetic conversion characteristics were measured at a gap of 25 μm between the stator core and the rotor core, and the values at 1 MHz are shown.
The results are shown in (Table 1). In sample G having no warp prevention layer on the opposite surface, the amount of warpage during firing was large and the magnetic conversion characteristics could not be measured. It can be seen that by providing the warp prevention layer on the entire opposite surface or on a part thereof, a flat plate rotary transformer having a high degree of electric signal transmission efficiency with little warpage and excellent productivity can be obtained. Further, the partial pattern shape of the warp prevention layer is a non-circular shape other than the embodiment, a rib shape,
A spiral shape or a combination pattern thereof can be considered, but it goes without saying that they are all effective.

(Example 2) In the same manner as in Example 1, the slurry A was used in the doctor blade method to prepare a green sheet having a thickness of 200 µm. A stack of these green sheets is heat-pressed at 120 ° C. with an upper mold 51 having a concave portion 54 forming a convex pattern as shown in FIG. 5A to obtain a green sheet as shown in FIG. 5B. A green sheet having a thickness of 0.95 mm in which the convex pattern 38 was formed on one surface of the sheet 53 was obtained.

After cutting this green sheet into a predetermined size, a conductor pattern 37 (pattern width 70 μm, thickness 36) is formed in the concave portion of the main surface of the molded body as shown in FIG. 5C.
as a spiral pattern, and a short ring coil (pattern width 200 μm, thickness 36 μm) was screen-printed with silver paste ink. Also, FIG.
As shown in (d), a warp prevention layer 35 (thickness 20 μm) was screen-printed with a ferrite ink having the same composition as the core on the entire opposite surface. Pressed after printing, outer diameter is 25.56m
It was cut into a disk shape having an m and an inner diameter of 4.54 mm. After degreasing the molded body produced in this way, 900
Sample H was obtained by stacking and firing at ℃.

The electromagnetic conversion characteristics were measured at a gap of 25 μm between the stator core and the rotor core, and the values at 1 MHz are shown.
The results are shown in (Table 1). A flat plate rotary transformer that has a conductor pattern formed in the concave portion of one main surface of the molded body and a warp prevention layer formed on the opposite surface of the molded body has high productivity with high electric signal transmission efficiency with little warpage and excellent productivity. I understand.

(Example 3) In the same manner as in Example 1, the slurry A was used in the doctor blade method to prepare a green sheet having a thickness of 200 µm. The laminated green sheets were hot pressed at 120 ° C. to obtain a green sheet having a thickness of 0.95 mm. As shown in FIG. 3, the green sheet was cut into a predetermined size, and then through holes 12 and 42 having a diameter of 300 μm were formed by a punching machine.

The conductor patterns 7 and 37 are aligned with the through holes 12 and 42 of the green sheet and are formed on one main surface of the molded body.
(Pattern width 70 μm, thickness 36 μm), and short ring coil (pattern width 200 μm, thickness 36 μm
m) and the through holes 12, 42, the conductive members 6, 3
6 was formed by screen printing or embedding a silver paste ink, respectively.

On the opposite surface, the take-out conductor pattern 9,
39 (thickness: 15 μm) was screen-printed with silver paste ink, and the portion other than the conductor portion was taken out as shown in FIG.
As shown in (f), the warp prevention layers 5 and 35 (thickness 20 μm
m) was screen-printed with a ferrite ink having the same composition as the core. After printing, it was cut into a disk shape having an outer diameter of 25.56 mm and an inner diameter of 4.54 mm by pressing. The molded body thus produced was degreased and then repeatedly fired at 900 ° C. in air to obtain Sample I.

The electromagnetic conversion characteristics were measured at a gap of 25 μm between the stator core and the rotor core, and the values at 1 MHz are shown.
The results are shown in (Table 1). Even in a molded article in which a conductor pattern for extraction is formed on the opposite surface and the conductor pattern for extraction and the conductor pattern on the main surface are energized by a conductive member through a through hole, a warp prevention layer is provided on the opposite surface. From the above, it can be seen that the flat plate rotary transformer has high electric signal transmission efficiency with little warpage and is excellent in productivity.

(Example 4) A Zn ferrite calcined powder was obtained by calcination of raw material powders having the following main composition, which were calcined at 700 ° C for 3 hours, and then pulverized to have an average particle size of 1 µm. B and the additive A prepared in Example 1
Slurry B was prepared by adjusting the slurry concentration while adding (plasticizer, lubricant, defoaming agent). The composition of the calcined ferrite powder B is shown below.

Ferrite calcined powder B; Fe ₂ O ₃ 50 mol% ZnO 50 mol% ... 100 kg As in Example 1, the slurry B was used to prepare a 200 μm-thick green sheet using the doctor blade method.
The laminated green sheet is hot pressed at 120 ° C. to form a green sheet having a thickness of 0.95 mm,
It was cut into a predetermined size. As shown in FIG. 6A, the conductor pattern 37 (pattern width 70 μm, thickness 36 μm)
As a spiral pattern with silver-palladium paste ink, short ring coil (pattern width 200μ
m, thickness 36 μm), silver-palladium paste ink, and ferromagnetic pattern 38 (pattern width 200
Slurry A having the same composition as that of the core was formed on the PET film 55 as a substrate.

Next, as shown in FIG. 6B, the base 5
The pattern No. 5 was transferred to the one main surface 33 of the molded body 53 to form a pattern. As shown in FIG. 6C, a non-magnetic material slurry B is formed as a warp prevention layer 35 (thickness: 15 μm) on the PET film 55 as a base in advance, and the warp prevention layer 35 of the base 55 is formed. Molded body 53
By transferring to the opposite surface 34, the warp prevention layer 35 was formed on the entire opposite surface. Outer diameter 2 by press after printing
It was cut so as to have a disk shape of 5.56 mm and an inner diameter of 4.54 mm. The molded body thus produced was degreased and then repeatedly fired at 970 ° C. in the air to obtain a sample J.

The electromagnetic conversion characteristics were measured at a gap of 25 μm between the stator core and the rotor core, and the values at 1 MHz are shown.
The results are shown in (Table 1). The warp prevention layer on the opposite side is
It is understood that the magnetic circuit does not have to be a ferromagnetic material such as a ferrite material and may be a non-magnetic material. Needless to say, a dielectric material, a resistance material, or the like may be used as the warp prevention layer.

(Embodiment 5) NiZnC which was pulverized to have an average particle size of 1 μm after calcination of raw material powder blended so that the main composition became the following composition at 700 ° C. for 3 hours
U-based ferrite calcined powder A was prepared, and the slurry concentration was adjusted while adding the additive B (shrinkage inhibitor, binder, plasticizer, lubricant, defoaming agent) to prepare a slurry C. The composition of the calcined ferrite powder A and the additive B is shown below.

Calcined ferrite powder A; Fe ₂ O ₃ 49 mol% ZnO 27 mol% NiO 13 mol% CuO 11 mol% ...... 100 kg Additive B; ・ Shrinkage inhibitor Fe 65.8 mol% ZnO 18.1 mol% NiO 8.7 mol% CuO 7.4 mol% ...... 25 kg ・ Binder butyral resin …… 180 liters ・ Plasticizer …… 2 kg ・ Lubricant …… 6 kg ・ Defoamer …… 2 liters Slurry A containing no shrinkage inhibitor as in Example 1. To
A 200 μm thick green sheet was prepared using the doctor blade method. Similarly, a slurry C having the above composition containing a shrinkage inhibitor was prepared by a doctor blade method to form a green sheet having a thickness of 200 μm. The laminated green sheets were hot pressed at 120 ° C. to obtain green sheets having a thickness of 0.95 mm, which were cut into a predetermined size to obtain green sheets A and C, respectively. As shown in FIG. 7A, the ferromagnetic pattern 38 (pattern width 200 μm, thickness 36 μm)
As the base substrate / PET film 55 in which the recesses are pre-filled with the slurry A containing no shrinking agent inhibitor,
A ferromagnetic pattern was formed on the one main surface 33 of the molded body 53 by intaglio printing.

Next, as shown in FIG. 7B, a spiral pattern is formed as a conductor pattern 37 (pattern width 70 μm, thickness 36 μm) using silver-palladium paste ink, and a short ring coil (pattern width 200 μm, thickness 36 μm) is formed. A silver-palladium paste ink was formed by screen printing.

As shown in FIG. 7C, the warp prevention layer 35 (thickness: 15 μm) also uses a substrate / PET film 55 in which the recesses are filled with the slurry A in advance, and a molded body 5 is formed.
The warp prevention layer 35 is formed by partially intaglio printing the opposite surface 34
Was partially formed.

Molded articles starting from green sheet A (without shrinkage preventive agent), molded articles starting from green sheet C (containing shrinkage inhibiting agent), and molded articles not having a warp prevention layer for comparison. (No shrinkage inhibitor),
(Containing shrinkage inhibitor) is also prepared, and the outer diameter is 25.
It was cut into a disc shape having a diameter of 56 mm and an inner diameter of 4.54 mm. After degreasing each of the molded bodies produced in this way,
Samples K to N were obtained by repeatedly firing in air at 900 ° C.

The electromagnetic conversion characteristics were measured at a gap of 25 μm between the stator core and the rotor core, and the values at 1 MHz are shown.
The results are shown in (Table 1). It can be seen that the samples K and L having the warp prevention layer have a small amount of warp. Further, it can be seen that the sample M in which an inorganic shrinkage inhibitor is added as an additive and the warp prevention layer is present has very little warpage and high electrical signal transmission efficiency, and a flat plate rotary transformer excellent in productivity can be obtained. .

[0045]

[Table 1]

In the flat plate rotary transformer of the present invention and the manufacturing method thereof, various materials (ferrite powder,
Binder, conductor, ferromagnetic material, material composition such as shrinkage inhibitor, particle size distribution, etc., molding method (molding, green sheet molding, injection molding, green sheet single layer or laminated), firing conditions ( Temperature, time, pressure, atmosphere, etc.), conductor and ferromagnetic material molding method (printing, transfer, inkjet, etc.), rotary transformer shape (outer diameter, inner diameter, thickness, gap, conductor pattern, ferromagnetic material pattern, through hole, The dimensions of the short ring coil etc.) are not limited to those in this embodiment.

[0047]

As described above, according to the flat plate rotary transformer of the present invention and the manufacturing method thereof, a conductor pattern and a ferromagnetic convex pattern made of ferrite are formed on one main surface of a molded body made of ferrite and an additive. By integrally degreasing and sintering the molded body having the warp prevention layer formed on the opposite surface thereof, it is possible to obtain a flat plate rotary transformer having a high degree of electric signal transmission efficiency with little warpage and excellent productivity.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing an embodiment of a flat plate rotary transformer of the present invention.

FIG. 2 is a sectional view taken along the line AB of FIG.

FIG. 3 is an enlarged cross-sectional view of a main part of the other embodiment.

4A to 4F are bottom views of the other embodiments.

5 (a) to 5 (d) are cross-sectional views showing a manufacturing process of a stator core or a rotor core according to another embodiment of the present invention.

6A to 6C are cross-sectional views showing respective steps of manufacturing a stator core or a rotor core according to another embodiment of the present invention.

7A to 7C are cross-sectional views showing respective steps of manufacturing a stator core or a rotor core according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a conventional flat plate rotary transformer.

FIG. 9 is a sectional view showing another conventional flat plate rotary transformer.

[Explanation of symbols]

 1 Stator core 2,32 Shaft hole 3,33 Main surface 4,34 Opposite surface 5,35 Warp prevention layer 6,36 Conductive member 7,37 Conductor pattern 8,38 Ferromagnetic material pattern 9,39 Extraction conductor pattern 10,40 Short ring 11,41 Terminal pin 12,42 Through hole 20 Drum shaft 21 Terminal block 31 Rotor core 51 Upper mold 52 Lower mold 53 Molded body 54 Recessed portion 55 Base body

Front page continuation (72) Inventor Yuji Mido 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (12)

[Claims] 1. A molded body integrally formed with a conductor pattern and a ferromagnetic convex pattern made of ferrite formed on one main surface of a molded body made of ferrite and an additive, and a warp prevention layer formed on the opposite surface of the molded body.・ Sintered ferrite core,
A flat plate rotary transformer consisting of a terminal block provided with terminals for extracting electrical signals. 2. A ferrite core obtained by integrally degreasing and sintering a molded body comprising a conductor pattern formed in a concave portion of one main surface of the molded body made of ferrite and an additive, and a warp prevention layer formed on the opposite surface thereof. A flat plate rotary transformer consisting of a terminal block provided with terminals for extracting electrical signals. 3. The flat plate rotary transformer according to claim 1, wherein the warp prevention layer is formed on the entire opposite surface. 4. The flat plate rotary transformer according to claim 1, wherein the warp prevention layer is partially formed on the opposite surface. 5. The flat plate rotary transformer according to claim 1, wherein the warp prevention layer is made of the same material as the ferromagnetic pattern of the main surface. 6. The warpage prevention layer is made of a non-magnetic material.
Or the flat plate rotary transformer described in 2. 7. The flat plate rotary transformer according to claim 1 or 2, which is composed of an inorganic material containing at least the same element as an element constituting ferrite as an additive. 8. The structure according to claim 1 or 2, wherein a conductor pattern for extraction is formed on the opposite surface, and the conductor pattern for extraction and the conductor pattern on one main surface are energized by a conductive member through a through hole. Flat plate rotary transformer. 9. The flat plate rotary transformer according to claim 1, wherein the height of the conductor pattern on one main surface is not more than the depth of the recessed groove on the same surface or the height of the convex pattern of the ferromagnetic material. 10. The flat plate rotary transformer according to claim 8, wherein the lead-out conductor pattern on the opposite surface is formed in the recess of the warp prevention layer, and the height of the conductor pattern is not more than the depth of the recess. 11. A conductor pattern formed on one main surface of a molded body made of ferrite and an additive or a ferromagnetic convex pattern made of ferrite, and a warp prevention layer formed entirely or partially on the opposite surface. A method of manufacturing a flat plate rotary transformer, comprising printing at least one of the above or forming a pattern on a substrate, and then transferring and forming the pattern on a corresponding surface of a ferrite molded body. 12. The method for producing a flat plate rotary transformer according to claim 11, wherein the substrate has a concave portion, and after filling the concave portion with a paste, a pattern is formed on the corresponding surface of the ferrite molded body by intaglio printing.