JPH07201612A - Rotary transformer and its manufacture - Google Patents

Abstract

PURPOSE:To enhance the transmission efficiency while reducing noise by a structure wherein the conductor wirings for coupling a transformer are filled tightly in winding slots in flush with the opposing faces of cores while being connected, at the end parts with connection lands formed on the surface on the opposite side. CONSTITUTION:A thin copper film 36 is cut to form insulating grooves 41, 42 around through holes 43, 44. Consequently, connection lands 39, 40 are formed in the insulating grooves 41, 42 formed circularly. Winding slots 64, 65 are filled tightly with windings 62, 63 of thin copper film having surfaces in flush with those of the cores 67, 68. Since reactive flux passing through the winding slots 64, 65 is not generated, the transmission efficiency is enhanced significantly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary transformer having a high transmission efficiency for use in a rotary head type magnetic recording / reproducing apparatus such as a VTR or R-DAT, and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 10 is a plan view and a cross section of a stationary member of a conventional flat plate rotary transformer. In the figure,
Reference numeral 1 is a stationary side member, 2 is a flat plate-shaped stationary side core formed of a high magnetic permeability material such as ferrite, and 3 is a concentric stationary side winding groove formed on one circular surface of the core 1. ,
Reference numeral 4 denotes a stationary side winding lead-out groove formed from a part of the stationary side winding groove 3 toward the outer side in the radial direction of the stationary side core 2, and 5 is formed concentrically by using a conductor such as a conductive wire. The stationary winding 5, 6 is the end of the stationary winding 5, and OO ′ is the central axis. In the stationary-side member 1, the stationary-side winding 5 is embedded in the stationary-side winding groove 3 with an adhesive so as not to protrude to the surface of the stationary-side core 2. The end 6 is drawn to the outside of the stationary core through the stationary winding drawing groove 4. A portion of the end portion 6 that passes through the stationary side winding lead-out groove 4 is buried inside the stationary side winding groove 4 with an adhesive so as not to protrude to the surface of the stationary side core 2.

Next, the rotating member will be described. Figure 1
1 shows a plan view and a cross-sectional view of the rotary member. In the figure, 7 is a rotary member, 8 is a flat circular rotary core made of a high magnetic permeability material such as ferrite, and 9 is a concentric rotary core formed on one circular surface of the core 1. The winding groove 10 is a rotation-side winding lead-out groove formed from a part of the rotation-side winding groove 9 toward the outer side in the radial direction of the rotation-side core 8,
Reference numeral 11 denotes a rotating side winding formed concentrically using a conductor such as a conductive wire, 12 denotes an end portion of the rotating side winding 11, O-
O'is the central axis. In the rotation side member 7, the rotation side winding 11 is embedded in the rotation side winding groove 9 using an adhesive so as not to protrude to the surface of the rotation side core 8. The end portion 12 is drawn out to the outside of the rotation side core through the rotation side winding drawing groove 10. A portion of the end portion 12 that passes through the rotation-side winding lead-out groove 10 is embedded in the rotation-side winding groove 10 with an adhesive so as not to protrude to the surface of the rotation-side core 8.

FIG. 12 is a diagram showing a positional relationship when the stationary member and the rotating member shown in FIGS. 10 and 11 are used as a rotary transformer. In the figure, the stationary side member 1 and the rotating side member 7 are arranged so as to share the central axis OO ′ so that the stationary side winding 5 and the rotating side winding 11 are close to each other. With this arrangement, transformer coupling can be obtained even when the rotating member 7 is rotating. A portion A surrounded by a dotted line shows a portion where the stationary winding 5 and the rotating winding 11 are close to each other. Although not shown, for example, when used for rotary magnetic recording / reproduction of VHS VTR, R-DAT, etc., the rotary transformer is built in the rotary cylinder, and the stationary side winding end 6 is connected to the recording / reproducing amplifier to rotate the rotary side winding. The wire end 12 is connected to the magnetic head.

[0005]

FIG. 13 is an enlarged view of a winding facing portion of a conventional rotary transformer, and shows a portion A surrounded by a dotted line in FIG. In the figure, 1 is a stationary member, 2 is a stationary core, 3 is a stationary winding groove, 5 is a stationary winding, 5'is a conductor portion of the stationary winding 5, 5 "is a stationary winding 5 Insulation film, 7 is a rotating member, 8 is a rotating core, 9
Is a winding groove on the rotating side, 11 is a winding on the rotating side, 11 'is a conductor portion of the winding on the rotating side 11, 11 "is an insulating film on the winding on the rotating side 11, 15 is an adhesive, Φ1 is an effective magnetic flux, Φ2, Φ3 is an ineffective magnetic flux Since the rotary transformer rotates and uses the rotating side member 7, the stationary side winding 5 and the rotating side winding 11 are surely the stationary side winding groove 3 and the rotating side winding groove 9 respectively. Therefore, the stationary side winding groove 3 must be securely embedded in the inside.
The depth of the winding groove 9 on the rotating side and the thickness of the adhesive material 15 in the groove depth direction of the winding 5 on the stationary side and the winding 11 on the rotating side are added with the floating and peeling margins of the winding. It was decided.

For this reason, for example, when a signal is transmitted from the stationary side to the rotating side of the rotary transformer, if a current is passed through the stationary side winding 5 upward in the drawing, it is roughly divided into Φ 1, Φ.
2 and Φ3 magnetic flux lines are generated. Among them, only the Φ1 which links the rotating side winding 11 plays a role of transmitting a signal to the rotating side by electromagnetic induction.
Φ2 passing through the stationary winding groove 3 without interlinking with Φ3 passing through the rotating winding groove 9 is an ineffective magnetic flux. Here, in the conventional rotary transformer, the winding groove is formed deep in consideration of the thickness of the winding film, the thickness of the adhesive material 15, the peeling margin of the winding, and the like. The path becomes longer, the magnetic resistance to the effective magnetic flux Φ1 increases,
There is a problem in that the ratio of the reactive magnetic fluxes Φ2 and Φ3 to the effective magnetic flux Φ1 becomes large and the transmission efficiency is significantly reduced.

Furthermore, since the stationary side winding lead-out groove 4 and the rotating side winding leading-out groove 10 are formed in the stationary side core 2 and the rotating side core 8, respectively, the winding grooves do not face each other. At this time, since the combined inductance of the transformers is different, when the rotating member 7 is rotated at a constant cycle, the transmission efficiency changes at every constant cycle, which becomes spike noise of a constant cycle and adversely affects the transmission signal. There was also a problem.

In order to solve this problem, for example, as disclosed in Japanese Patent Publication No. 3-55961, a resist pattern is formed on a thin aluminum plate at a position other than the circuit portion, and the circuit on the substrate is formed. After forming a conductor by plating on the portion, an insulating layer is formed on the conductor, then the aluminum thin plate is removed by etching, and a conductor is formed by plating on the surface of the obtained conductor which is in contact with the aluminum thin plate. The obtained printed winding is buried in a concentric circular groove of a plate-shaped circular ferrite provided with a plurality of concentric circular grooves and a plurality of radial grooves of the circle, and a take-out circuit portion is provided with a radius of the circular core. A remedy is known in which the rotary transformer is formed by being buried in a groove in the direction.

FIG. 1 is an enlarged view of a portion where the stationary side winding and the rotating side winding are close to each other, as in FIG.
4 will be used for the explanation. In the figure, 1 is a stationary member,
2 is a stationary side core, 3 is a stationary side winding groove, 16 is a stationary side printed winding formed by plating, 17 is a conductor portion of the stationary side printed winding 16, 18 is a rotating side printed winding formed by plating, Reference numeral 19 is a conductor portion of the rotary side printed winding wire 2,
0 is insulator, 21 is adhesive, Φ1 is effective magnetic flux, Φ2, Φ3
Is the ineffective magnetic flux.

In this method, since the conductor portion 17 of the stationary side print winding 16 and the conductor portion 19 of the rotating side print winding 18 are not covered with the insulating film, the winding groove 3, 9 can be made slightly shallower. As a result, the magnetic path length of the effective magnetic flux is shortened, the magnetic resistance to the effective magnetic flux φ1 is reduced, and the transmission efficiency can be improved. However, there is still a process of embedding the printed winding in the winding groove using an adhesive material, so a peeling margin of the printed winding is required, and there is space in the groove even though the winding groove becomes shallow. Therefore, the invalid magnetic fluxes Φ 2 and Φ 3 existed even though they became smaller.

Although not shown, a winding lead-out groove for pulling out the terminal portion of the printed winding is required in the above-mentioned improvement measure as in the case of the conventional example.
However, the problem that the transmission efficiency changes every fixed cycle and this becomes spike noise of a fixed cycle and adversely affects the transmission signal has not been solved.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a rotary transformer and a manufacturing method thereof in which transmission efficiency is improved and noise countermeasures are taken.

[0013]

In the rotary transformer according to the invention of claim 1, the conductor winding used for transformer coupling is not covered with an insulating film, and the winding surface does not protrude from the facing surface of the core. The conductor winding is filled in the winding groove with no gaps, exactly matching the surface facing the core, and the end of the conductor winding is on the opposite side to the surface provided with the winding through the electrically conductive through hole. Is connected to the connection land formed on the surface of the.

A method of manufacturing a rotary transformer according to a second aspect of the present invention is such that a concentric circular groove is formed in advance, and at least one through hole is formed in the groove. A conductor is formed on the entire surface, and after the film is formed, the surface of the surface on which the concentric groove is formed is polished to fill the groove and the through hole with the conductor. In this rotary transformer, the winding groove is filled with a conductor to form a winding, and the outer peripheral surface of the core and the surface opposite to the surface having the winding are covered with a non-magnetic conductor. There is something.

According to a third aspect of the present invention, the rotary transformer according to the second aspect irradiates the rotary transformer with a laser to form a coil-shaped insulating groove.

A rotary transformer according to a fourth aspect of the present invention uses the method of the second aspect to form a conductor short-circuit ring.

According to a fifth aspect of the present invention, a rotary transformer according to the second aspect is formed by irradiating the rotary transformer with a laser to form connection lands to form the rotary transformer of the first aspect.

According to a sixth aspect of the present invention, in the rotary transformer, the resonance frequency fr required for the transmission system from the head to the recording / reproducing amplifier via the rotary transformer, the combined inductance LT of the head and the rotary transformer, and the coupling of the rotary transformer. The winding groove width L is determined by the following formula from the coupling capacity CAP of the recording / reproducing amplifier other than the capacity, the winding section thickness x, the winding groove diameter R, the number of windings n, and the dielectric constant ε in the winding groove. To do.

[0019]

[Equation 2]

[0020]

In the rotary transformer according to the first aspect of the present invention, since the winding lead-out groove does not exist in the core facing surface, the combined inductance does not change even when the rotary member rotates in the used state.

In the rotary transformer according to the second aspect of the present invention, the outer peripheral surface of the core and the surface on the side opposite to the surface provided with the winding are covered with the non-magnetic conductor, so that they serve as an electromagnetic shield against external noise.

In the rotary transformer according to the second and third aspects of the present invention, since the winding groove is filled with a conductor without a gap, it is possible to eliminate the reactive flux passing through the winding groove that has been conventionally generated. it can.

The rotary transformer according to the invention of claim 4 is excellent in productivity because the conductor winding can be formed and at the same time the conductor short-circuiting ring for the crosstalk of the adjacent channel can be formed.

The rotary transformer according to the invention of claim 5 can have the advantages of both the rotary transformers of claims 2 and 1.

The rotary transformer according to the invention of claim 6 can easily design a rotary transformer having excellent transmission efficiency by using a specific formula.

[0026]

【Example】

Example 1. A method of manufacturing a rotary transformer according to an embodiment of the present invention will be described with reference to FIGS. First, as described in claim 2, the concentric groove is formed,
A flat plate circular core made of a ferromagnetic material having at least one through hole formed in the groove is prepared. FIG. 1 is a diagram showing a core shape of a rotary transformer according to the present invention before winding processing, and the front surface (winding forming surface), cross section, and back surface (winding forming surface) of a flat plate circular core prepared in this embodiment. (The opposite side of) is shown. In the figure, 31 is a core made by sintering a high-permeability material such as ferrite into a flat plate circular shape using a mold, and 32 is a concentric circular winding groove formed on one circular surface of the core 31. , 33 and 34 are through holes, 35 is an insulating film, a
Is the depth of the winding groove 32, b is the width of the winding groove 32, and OO ′ is the central axis.

First, the depth a is 100 [μm] and the width b is 17
The winding groove 32 is formed on the front surface of the core 31 by grinding using a diamond wheel or the like so as to have a thickness of 0 [μm].
The winding groove 32 may be formed by irradiating a YAG laser or an excimer laser, for example. Further, if the mold used for sintering the core 31 is formed in advance so that the depth a is 100 [μm] and the width b is 170 [μm], the grinding process can be omitted.

The through hole 33 has a diameter of 50 μm, and is inscribed in the outer circumference of the winding groove 32, for example, a YAG laser,
It is formed by irradiating an excimer laser or the like. The through hole 34 also has a diameter of 50 μm and is formed by irradiating the inner circumference of the winding groove 32 with, for example, a YAG laser or an excimer laser.

Since the inner peripheral portion of the core 31 is necessary for positioning when it is attached to the rotary cylinder, the insulating film 35 is formed before plating so that the surface accuracy of this portion does not deteriorate due to plating. . The insulating film 35 may be formed, for example, by applying a polymer material or the like that can be easily removed with an organic solvent. Hereinafter, the same numbers refer to the same parts.

FIG. 2 is a diagram showing a front surface, a cross section, and a back surface immediately after copper is plated on the core in FIG. In the figure, 31 is a core, 32 is a winding groove, 33 and 34 are through holes,
35 is an insulating film, 36 is a copper thin film formed by plating,
OO 'is the central axis. The copper plating may be about 100 [μm], as long as the winding groove 32 is filled with copper. Copper plating also fills the through-holes 33 and 34 with copper to form electrically-conductive through-holes (through-holes) 43 and 44, respectively.

After copper plating, an insulating film 35 is formed by using an organic solvent.
To remove. After that, the surface on which the winding groove 32 is formed is polished using a rotary polishing machine or the like until the depth of the winding groove 32 reaches 50 [μm]. In this way, the excess copper thin film and the core surface portion are removed from the front surface of the core 31 so that the inside of the winding groove 32 is filled with the copper thin film with a thickness of 50 [μm]. FIG. 3 shows a front view, a sectional view, and a rear view of the core 31 in this state. In the figure, 37 is a copper thin film with which the winding groove 32 is filled.

Next, a method of processing the front copper thin film 37 into a winding will be described. The processing is performed using a laser as described in claim 3. FIG. 4 is an enlarged view of the copper thin film in FIG. In the figure, 30 is a copper thin film winding, 38 is an insulating groove, 50 is a laser irradiation locus, α is a laser irradiation start position, β is a laser irradiation end position, w1, w2 and w3 are the pitches of the laser irradiation locus and w1 is 55 [μm], w2
Is 60 [μm] and w3 is 55 [μm]. For example, YA
Irradiation of G laser or excimer laser is performed from the irradiation start position α in the direction of the arrow shown in the trajectory 50, and ends at the end position β, so that the copper thin film 37 is cut and the insulating groove 38 having a width of 10 μm. To form. As to the method of forming the insulating groove 38 as described above, the laser may be moved, but the laser may be fixed and the core may be moved. By this processing, the copper thin film 37 has a concentric circular shape with the through holes 43 and 44 as end portions, and has a cross-sectional width of 50 [μm],
The copper thin film winding 30 has a sectional thickness of 50 [μm] and a winding number of 3 [turn]. Here, the winding of a generally used rotary transformer has a diameter of about 80 [μm] including an insulating film, and the copper wire portion has a diameter of about 50 [μm]. Compared with this, since the cross-sectional area of the copper thin film winding is wider, the electrical resistance of the winding is lower and the thermal noise can be reduced.

Next, a method of processing the copper thin film 36 on the back surface to form connection lands for connecting the ends of the copper thin film windings 30 will be described. The processing is performed by using a laser as described in claim 5. FIG. 5 is an enlarged view of the back surface of the core 31. In the figure, 36 is a copper thin film, 39 and 40 are connection lands, 41 and 42 are insulating grooves, and 51 and 52 are laser irradiation loci. For example, irradiation with a YAG laser or an excimer laser is performed according to the directions of the arrows shown in the loci 51, 52 to cut the copper thin film 36, and the through holes 43, 4 are formed.
By forming the insulating grooves 41 and 42 around 4 respectively, the connection lands 39 and 40 described in claim 1 are formed inside the insulating grooves 41 and 42 formed in a circular shape.

FIG. 6 shows a front view, a sectional view, and a rear view of the constituent members of the rotary transformer according to the first embodiment of the present invention manufactured by the above process. The constituent member shown in FIG. 6 can be used as either a stationary member or a rotating member. In the figure, 30 is a copper thin film winding, 31 is a core, 3
2 is a winding groove, 36 is a copper thin film, 39 and 40 are connection lands,
43 and 44 are through holes, and OO ′ is a central axis.
FIG. 7 is a sectional view when a rotary transformer is configured by using two constituent members of the rotary transformer shown in FIG. In the figure, 36 is a copper thin film, 60 is a stationary side member, 61 is a rotating side member, 62 is a stationary side winding, 63 is a rotating side winding, 64 is a stationary side winding groove, and 65 is a rotating side winding groove. 67 is the stationary core,
Reference numeral 68 is a rotation side core, and O-O 'is a central axis of the stationary side member 60 and the rotation side member 61, and is also a rotation axis of the rotation side member 61. A region B surrounded by a dotted line is a winding facing portion.

FIG. 8 is an enlarged view of the winding facing portion B surrounded by a dotted line in FIG. In the figure, 36 is a copper thin film, 31
Is a core, 60 is a stationary side member, 61 is a rotating side member, 62 is a stationary side winding, 63 is a rotating side winding, 64 is a stationary side winding groove,
Reference numeral 65 is a rotating side winding groove, 66 is an insulating groove, 67 is a stationary side core, 68 is a rotating side core, a is a winding groove depth, b is a winding groove width, and c is one winding groove. , L is the width of the insulating groove 66, Φ
1 is an effective magnetic flux passing through the core 31. The depth a of the winding groove is 50 [μm], the width b is 170 [μm], the width c of one winding is 50 [μm], and the width L of the insulating groove 66 is 10 [μm]. Thus, the winding grooves 64 and 65 are filled with the copper thin film windings 62 and 63, respectively, without any gaps, and the surfaces of the copper thin film windings 62 and 63 are aligned with the surfaces of the cores 67 and 68. Therefore, the ineffective magnetic flux passing through the winding grooves 64 and 65 is not generated, and the transmission efficiency is remarkably improved. Further, since the circular outer peripheral portions and the back surfaces of the cores 67 and 68 are covered with a copper thin film which is a non-magnetic conductive material, there is an electromagnetic shield effect against external noise.

Example 2. In Example 1, plating was performed with copper. However, if a non-magnetic conductive material having a higher conductivity than copper, such as gold, platinum, platinum palladium, and silver, is used, the resistance of the thin film winding is further reduced. The transmission efficiency and the shield effect are further improved.

Example 3. In Example 1, the cross-sectional area is 50 [μ
m] and the cross-sectional thickness of 50 [μm] was explained, but since the conductivity required for the winding depends on the modulation method of the signal to be transmitted, the detection method, etc. The cross-sectional thickness is not limited to this as long as it satisfies the necessary conditions for the transmission signal used. Also, the number of turns is 3 for both the rotating side and the stationary side.
Although [turn] is set, if the band of the transmitted signal is satisfied,
The number of windings is not limited to 3 [turn], and the number of stationary windings may be larger than the number of rotating windings.

Example 4. In Example 1, the conductive thin film winding was formed by laser processing. For example, “Journal of Microe
lectromechanical Systems ", VOL2, NO.2, JUNE, 1993, IEE
As shown in E PUBLICATIONS DEPARTMENT, P87-94, a resist is formed with photosensitive polyimide in the winding groove and plating is performed, and then the resist of the photosensitive polyimide is removed to form a thin film winding. Is also good. If a resist is formed around the through hole before plating by the same method, the connection land can be easily formed.

Example 5. Although the rotary transformer has one transmission channel in the first embodiment, the same effect as that of the first embodiment can be obtained even if the rotary transformer has a plurality of transmission channels as long as the number of winding grooves is increased. Also,
When a plurality of transmission channels are used at the same time, in order to reduce crosstalk between the channels, the method of claim 4
As described above, by forming the groove for the short-circuit ring in the core before plating in advance, the short-circuit ring can be easily formed by polishing the surface after plating. FIG. 9 is a diagram showing another embodiment of the rotary transformer of the present invention,
The core before plating is shown. In the figure, 101 is a core, 102 is a channel 1 winding groove, 103 is a channel 2 winding groove, 104 is a groove for a short circuit ring, and OO ′ is a central axis. It should be noted that the short-circuit ring exhibits a sufficient effect even if it is formed on only one core, but if it is formed on both cores, the effect is further increased.

Example 6. Although Example 1 was an example relating to a flat plate type rotary transformer, when a similar method is applied to a cylindrical type rotary transformer configured by combining cylindrical cores, the same effect is obtained. I was able to.

Example 7. In Example 1, the conductive thin film was irradiated with a laser to form an insulating groove having a width of 10 [μm]. The insulating groove width is one of the factors that determine the coupling capacitance between adjacent windings. Here, if the cross-sectional thickness of the winding is x, the diameter of the winding groove is R, the insulating groove width is L, the number of windings is n, and the dielectric constant in the winding groove is ε, the coupling capacitance CRT of the rotary transformer is Can be approximated by the following equation (1).

[0042]

[Equation 3]

Here, considering the case of actually using the rotary head type magnetic recording / reproducing apparatus, the transmission band of the transmission system including the head, the rotary transformer and the recording / reproducing amplifier is determined by the resonance frequency fr of this transmission system. The resonance frequency fr of the transmission system is LT, the combined inductance of the head and the rotary transformer, and C is the total coupling capacitance of the recording / reproducing amplifier.
If P is set, it can be calculated by the following equation (2).

[0044]

[Equation 4]

Since the coupling capacitance CRT of the rotary transformer is included in CP, if the coupling capacitance of the recording / reproducing amplifier other than CRT is set to CAP, then CRT can be expressed by the following equation (3) using equation (2). it can.

[0046]

[Equation 5]

From equations (1) and (3), the insulating groove width L can be expressed by the following equation (4).

[0048]

[Equation 6]

That is, the resonance frequency fr of the transmission system, the head, the combined inductance LT of the rotary transformer, the coupling capacitance CAP of the recording / reproducing amplifier other than the coupling capacitance of the rotary transformer,
If the cross-sectional thickness x of the winding, the diameter R of the winding groove, and the number of windings n are determined, the value of the winding groove width L may be determined using equation (4).
In addition, since it may be considered that the transmission band is actually set sufficiently wide, the winding groove width L may be set according to the following expression (5) as described in claim 6.

[0050]

[Equation 7]

[0051]

As described above, according to the rotary transformers of the first to eighth embodiments of the present invention, since the conductor winding is filled in the winding groove without any gap, it passes through the winding groove which has been conventionally generated. It is possible to eliminate all the ineffective magnetic flux that occurs, and the transmission efficiency is significantly improved.

Furthermore, since there is no winding lead-out groove on the surface facing the core, there is no change in the combined inductance even when the rotating member is rotating.
It is possible to completely eliminate the problem that spike-like noise with a constant period adversely affects the transmission signal.

Further, since the outer peripheral surface of the core and the surface on the side opposite to the surface provided with the winding are covered with the non-magnetic conductor, this portion serves as an electromagnetic shield and interference due to external noise can be eliminated.

Since the rotary transformer according to the fifth embodiment of the present invention has the short circuit ring between the transmission channels, the crosstalk can be sufficiently reduced even when two adjacent channels sandwiching the short circuit ring are used at the same time. Furthermore, since the short-circuit ring can be formed at the same time as the winding formation, it is very efficient.

Good transmission characteristics can be obtained by defining the groove width of the rotary transformer according to the present invention.

[Brief description of drawings]

FIG. 1 is a diagram showing a core shape before winding processing of a rotary transformer according to the present invention.

FIG. 2 is a view showing a front surface, a cross section, and a back surface immediately after copper is plated on the core in FIG.

FIG. 3 is a view showing a front surface, a cross section, and a back surface of a core whose surface is polished after copper plating.

FIG. 4 is an enlarged view of the copper thin film in FIG.

FIG. 5 is an enlarged view of the back surface of the core.

FIG. 6 is a diagram showing constituent members of a rotary transformer according to the present invention.

7 is a cross-sectional view when a rotary transformer is configured by using two constituent members of the rotary transformer shown in FIG.

8 is an enlarged view of a winding facing portion B surrounded by a dotted line in FIG.

FIG. 9 is a diagram showing another embodiment of the rotary transformer of the present invention.

FIG. 10 is a view showing a plane and a cross section of a stationary side member of a conventional flat plate type rotary transformer.

FIG. 11 is a diagram showing a plan view and a cross section of a rotary member of a conventional flat plate type rotary transformer.

FIG. 12 is a diagram showing a positional relationship when the stationary member and the rotating member shown in FIGS. 9 and 10 of the related art are used as a rotating transformer.

FIG. 13 is an enlarged view of a winding facing portion of a conventional rotary transformer.

FIG. 14 is an enlarged view of a winding facing portion of another conventional rotary transformer.

[Explanation of symbols]

 30 Copper thin film winding 31 Core 32 Winding groove 36 Copper thin film 39, 40 Connection land 43, 44 Through hole O-O 'Central axis

Claims (6)

[Claims] 1. A pair of flat-plate circular cores made of a ferromagnetic material, each core having one or more concentric circular grooves formed on one circular surface, and the grooves made of a conductor. The windings of each core are arranged, and the surfaces of the windings of the respective cores are made to face each other with a constant gap, thereby causing a transformer coupling,
In a flat plate type rotary transformer used as a transformer having a single or a plurality of transmission channels in a state where at least one core is stationary or rotating, the conductor winding is not covered with an insulating film and the winding surface is a core. Does not protrude from the facing surface of the conductor, is almost coincident with the facing surface of the core, and is filled in the winding groove without any gap except for the minute gap between the conductor windings. A rotary transformer characterized in that it is connected to a connection land formed on the surface opposite to the surface provided with the winding through a through hole that is conducted to. 2. A concentric circular groove is formed in advance, and at least one through hole is formed in the groove. A flat plate circular core made of a ferromagnetic material is formed on the entire core with a conductor to form a film. After the film formation, the surface of the surface on which the concentric groove is formed is polished to fill the inside of the groove and the inside of the through hole with a conductor. 3. The method according to claim 2, wherein the conductor thin film filled in the concentric groove formed on the core facing surface is irradiated with a laser to form a coiled insulating groove. The rotary transformer according to claim 1, wherein a conductor winding is formed. 4. The rotary transformer according to claim 1, wherein a conductor short-circuit ring is formed between the windings corresponding to the adjacent transmission channels by using the method according to claim 2. 5. The method according to claim 2, wherein a laser beam is irradiated around the through hole on the surface on which the conductive thin film is applied on the side opposite to the surface on which the winding is provided, The rotary transformer according to claim 1, wherein a connection land is formed inside the insulating groove by forming a frame of the insulating groove so that the vicinity thereof is electrically insulated from other conductive thin films. 6. When actually used in a rotary head type magnetic recording / reproducing apparatus, a resonance frequency fr required for a transmission system from a head to a recording / reproducing amplifier via a rotary transformer, a combined inductance LT of the head and the rotary transformer, Coupling capacitance CA of recording / reproducing amplifier other than coupling capacitance of rotary transformer
4. The winding groove width L is determined by the following equation from P, the cross-sectional thickness x of the winding, the diameter R of the winding groove, the number of windings n, and the dielectric constant ε in the winding groove. Rotating transformer described. [Equation 1]