JPS6276606A - Rotary transformer and its manufacture - Google Patents

Abstract

PURPOSE:To make it possible to provide superior cross-talk characteristics between channels also in a high frequency band by arranging a ring-shaped magnetic core consisting of a higher magnetic permeation ratio and lower loss material on a ring- shaped substrate consisting of a lower magnetic permeation material in a coaxial shape with specified distance each other. CONSTITUTION:A gap formed with ring-shaped magnetic cores 22 and 23 is filled with a highly conductive material, for example, a thin plate made by adhering permal loy or permalloy and copper in a ring-shape so as to form a short ring with small width. In the case of a rotary transformer made of ferrite, higher magnetic permeation and lower loss ferrite and nonmagnetic ferrite which are adjusted so that sintering condition, contraction ratio, and heat expansion, etc. are the same are prepared as source materials and made into grains. After that, ring-shaped magnetic cores 22 and 23 consisting of higher magnetic ratio and lower loss ferrite are coaxially com pressed to be formed on a ring-shaped substrate 21 consisting of nonmagnetic ferrite as one body, with specified distance and are sintered, then whose flat plane, external circumference, and internal circumference are ground to be a specified dimension with accuracy, with the result that the cross-talk between channels is substantially reduced, realizing an application in a wide band magnetic recording and reproduction device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotary transformer used in a VTR (video tape recorder), etc., and a method for manufacturing the same.

[Technical background of the invention]

In conventional single-rotation head type magnetic recording and reproducing apparatuses, a rotary transformer is used for transmitting and receiving electrical signals between the rotating magnetic head and the signal processing circuit on the fixed part side.

FIG. 8 shows an example.

This example corresponds to the transmission and reception of two-channel signals, and as shown in the plan view of Figure 8), two concentric grooves are formed, and the ζ windings (11) and (lb) are connected here. The annular magnetic cores (2) are arranged so that the windings (la) and (lb) are opposed to each other with a slight gap f interposed therebetween, as shown in Figure (b). Note that (3) is a shield ring that is similarly placed in the groove for the purpose of reducing crosstalk between channels. Core (2
), (2) are opposite windings (1a
) and (la), (lb) and (1b) -c m f
i Coupling occurs and signals are exchanged. Here, general magnetic coupling will be explained. Core (4), (4)
When one of the cores rotates, the arrow (
Magnetic flux loops shown in 5) and (6) are generated, and each channel is magnetically coupled. However, the magnetic core (4)
, (4) have a continuous integral structure, so in reality, as shown in FIG. 9(b), the opposing windings (la), (
ill) produces a magnetic flux loop (6) and at the same time the winding (l
A magnetic flux loop (7) is generated in the magnetic path surrounding a), (ia), (tb), and (xb), which results in crosstalk. In addition, a magnetic flux loop as shown in (8) in FIG. 9(C) 1 occurs, which results in crosstalk.

Figure 10 shows an example of measures taken to reduce the above-mentioned crosstalk between channels, in which a short ring (3) is placed between the channels shown in Figure 8 ((a) in the same figure).
, just a groove (9) between the windings (la) and (lb) i
(11 is provided ((b) and (C) in the same figure).
1), (one force is a magnetic core). To briefly explain the function of the short ring (3) shown in FIG. 10(a), the two windings (la) and (la) generate a magnetic flux loop (6) and the winding (la).

(11), winding (3), magnetic flux loop surrounding (3) (13, winding (la), (la), winding (3),
Tring (3), (3).

A magnetic flux loop (14) surrounding the winding (lb), (lb)
). However, since the magnetic flux loop (19) gives a back electromotive force to the short rings (3), (3), a magnetic flux loop in the opposite direction to the magnetic flux loop (1~) is generated between the short rings (3), (3). Since this is a magnetic flux loop (I4 is also a magnetic flux loop in the opposite direction), the influence of crosstalk caused by the magnetic flux loops αJ and α is reduced.

The same thing can be said about the magnetic flux loop created by the first winding (lb) and (lb).

Therefore, the rotary transformer with crosstalk measures as described above can transmit and receive signals in the band up to approximately gQMHz, and the frequency band used by conventional magnetic recording and reproducing devices (1Q
QKHz~f3MHx).

[Problems with background technology]

However, in recent years, as the quality of magnetic recording and reproducing devices has increased and digital circuits have been improved, the maximum frequencies used have become wider, up to several IQMHz, and accordingly, the transmission characteristics of rotary transformers are also required to have wider bands. However, in the conventional rotor 1, 1 + transformer described above, crosstalk due to capacitive coupling between each channel increases rapidly in a band of about 20 MHz or higher.

There was a problem that it could not cope with the above-mentioned higher quality and digital circuits.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a rotary transformer and a method for manufacturing the same which have excellent inter-channel crosstalk characteristics even in high frequency bands.

[Summary of the invention]

The rotary transformer according to the present invention includes an annular magnetic core made of a high magnetic permeability low loss material on an annular substrate made of a low magnetic permeability material, and the annular magnetic core made of the same ferrite is spaced at a predetermined distance from each other on the annular substrate made of the same ferrite. The low magnetic permeability ferrite to be formed and the high magnetic permeability low loss ferrite to form the annular magnetic core are compression molded to form a composite magnetic core, which is fired and then pressed to a predetermined size.

A method of winding the wire was used.

[Embodiments of the invention]

First of all? An embodiment of the rotary transformer according to the present invention will now be described, and then an embodiment of the manufacturing method in which the material is ferrite will be described.

FIG. 1 is a diagram showing the above-mentioned embodiment, and FIG. 1(a) is a plan view of the I2-tally transformer on the fixed side (same as on the rotating side). FIG. 2B is a sectional view of the entire rotary transformer. eJ]) is a low magnetic permeability material (e.g.

It is an annular substrate made of Zn ferrite)* (B+
c:3) is an annular magnetic core made of a high permeability, low loss material (for example, Ni-Zn ferrite). And the annular magnetic core (:!'21.f23) has a winding (24), (
The interval W between the grooves where 2■ is arranged is 0.5f11 or more,
The distance f between the stationary rotary transformer (c) and the rotating rotary transformer (5) is several tens of μm to 106 μm.

This rotary transformer creates a magnetic flux loop (28a) between opposing windings by rotating the rotary transformer.
), (28b) occurs. In other words, magnetic coupling occurs, and the windings (goods) of the rotary transformer (c) on the fixed side,
The signal flowing to (c) is the rotating side rotary transformer (5)
winding (2), 25 flows into one transformer (2f; 1.
Signals are exchanged between @. In this case, since the distance W between the high magnetic permeability and low loss annular magnetic core (23 and The dielectric constant of (c) is the core (sha), the space (29a) between (c), (29
Since the dielectric constant is more than 10 times that of the air present in b), the electrostatic coupling between adjacent channels is greatly weakened, and electrostatic crosstalk is also reduced.

FIG. 2 shows another embodiment of the rotary transformer according to the present invention, and FIG. 2(a) shows a high-conductivity material (for example, permalloy or It is filled (in an annular shape) with a thin plate made of permalloy and copper bonded together, and by configuring it in this way, a wide sheet ring is formed. Figure Φ) is winding 01
) is wound Iζ between multiple turns of magnetic core Q 123, and by short-circuiting both ends of the first winding 01) and making the potential of the first winding the same as the circuit ground in an alternating current manner, the same figure (
It has the same effect as a).

Furthermore, in the same figure (C), a material with a large dielectric loss is arranged (in an annular shape) in the gap between the magnetic cores, and the permittivity of the S annular magnetic core (24, (c) and the material Ga is The windings (1) and (3) are magnetically and electrostatically separated by the difference in the windings.

Next, one embodiment of a method for manufacturing the rotary transformer shown in FIG. 1, in which the material is ferrite, will be described.

FIG. 3 is a flow chart showing an outline of the above embodiment. First, high magnetic permeability, low loss ferrite (2) and non-magnetic ferrite (b), which are adjusted to have the same firing conditions, contraction rate, thermal expansion coefficient, etc., are weighed and mixed (wet method).

Material production through the steps of dehydration, drying, roasting, pulverization (wet), dehydration, and drying (step 81.82) l,, / (mix ind and granulate (step s3.84) L, then non- integral compression molding using a mold or the like so that annular magnetic cores made of high magnetic permeability low loss ferrite are arranged concentrically at predetermined intervals on an annular substrate made of magnetic ferrite (step 85); The four-tally transformer material with a composite structure made of both ferrites is fired (step 86).Finally, the plane, outer circumference, and inner circumference are polished to a predetermined dimensional accuracy and the first winding etc. are finished (step S7). Thus, a rotary transformer is obtained.

Next, the compression molding process in the manufacturing process of a rotary transformer having a two-channel configuration, which is the minimum channel configuration, will be specifically explained based on FIG. 4.

First, as shown in the same figure (a), the protrusions (3 ridges, (g)) for forming the grooves for the 1st winding (goods) and (e), and the grooves for separating and making the two channels independent. After arranging a cylindrical partition wall OI concentrically corresponding to the protrusion part GV) for forming a powder-filled gap for each channel in the lower mold (to) having a protrusion part 07), a high magnetic permeability Granulated materials of low-loss ferrite, such as Ni-Zn ferrite (40, (41
) is filled to a thickness that is two to three times the thickness of the magnetic core of the molded product. After that, as shown in the same figure Φ), the upper punch ■,
(Slide A3 in the lower chamber (to) '4~f3 t/a
Pressure molding is performed at a high pressure of about rt".Then, the first and fourth
As shown in FIG. Fill to thickness. Next, as shown in Fig. 4(d), slide the upper punch (c) inside the lower mold (to) and
After that, the molded product is taken out from the lower mold and heated in a tunnel type electric furnace etc.
It is fired at a high temperature of about 1400°C. And plane, outer circumference,
Polish and finish using an internal grinder or the like to achieve a predetermined dimensional accuracy. As a result, the composite ferrite shown in Fig. 4(e) is completed, and finally the winding grooves m and ran are formed as shown in Fig. 4(e).
As shown in 0, windings (48) and (4G) are applied to complete the process.

Note that 60 is a groove that separates the channels.

FIG. 5 shows another compression molding method. First, the same figure (a)
As shown in the figure, a lower mold 61) having one cylindrical groove is filled with six granulated materials of non-magnetic ferrite, for example Zn ferrite, to a thickness that is 2 to 3 times the thickness of the non-magnetic substrate part of the molded product. do. Next, as shown in the figure Φ), a cylindrical upper punch 63) that can slide through the cylindrical groove of the lower mold 6υ is slid inside the lower mold 61), and a high pressure of 4 to 8 t/c is applied. Pressure mold. As shown in the same figure (C), a of the granulated material of high magnetic permeability and low loss ferrite is 2 times the thickness of the magnetic core after molding.
Fill to ~3 times the thickness.

After that, as shown in FIG. 5(d), a protrusion (59, (to)) for forming a winding groove, and a protrusion 6' for forming a groove for separating and making the two channels independent. 7) Slide the upper punch Q equipped with
Pressure molding is performed at a high pressure of A. Next, the molded product is placed in the lower mold l.
51) and heated in a tunnel electric furnace etc. for 1000~
It is fired at a temperature of about 1400°C. The following finishing work for the first winding is performed in the same manner as described in FIG.

FIG. 6 is a diagram showing further details of another compression molding process. First, as shown in Figure (a), a compression molding die f5cJ having a cylindrical through hole corresponding to the outer circumferential dimension of the molded product is fixed, and a die f5cJ is arranged concentrically with the die f5cJ and has a cylindrical through hole corresponding to the outer peripheral dimension of the molded product. 121. A lower punch υ that forms an opposing surface of the rotary transformer in a cylindrical space formed by a fixed lower punch ⑅ having a cylindrical shape corresponding to the dimensions. till, f6-
Lower punch (65), (U
GI and a lower punch (6η) to form a groove to make the two channels independent during separation are adjusted and installed to a predetermined step.Furthermore, in order to form a powder filling gap for each channel, a lower punch (6η) is installed. The upper punch (67) and the corresponding cylindrical partition wall are arranged concentrically.Then, the granulated material of high magnetic permeability and low loss ferrite, σ0, is the thickness of the magnetic core part of the molded product. Next, as shown in Fig. 6(b), the upper punch συ is inserted into the cylindrical space formed by the die 5'l and the lower punch. Pressure molding is carried out at a pressure of about 4 to 8 t/cm" by sliding. Furthermore, as shown in FIG. 6(C), one cylindrical partition wall is formed.
is removed, and a granulated material σJ of non-magnetic ferrite is filled to a thickness 2 to 3 times the thickness of the non-magnetic substrate portion of the molded product. After that, as shown in Fig. 6(d), the upper punch σ4 is slid in the space formed by the die (5ω) and the lower punch 1 (1), and the molding is performed under high pressure of 4 to F3 t/art. Then, the molded product was taken out from die 6I and fired in the same manner as described above.

Polish the first winding.

FIG. 7 is a diagram showing further details of another compression molding process. As shown in Figure (a), there is a die R51 that is fixed during compression molding and has a cylindrical through hole corresponding to the outer circumferential dimension of the molded product, and a die r51 that is arranged concentrically with this and has a cylindrical through hole that corresponds to the outer peripheral dimension of the molded product. The lower punch σe is installed at a predetermined position in the cylindrical space formed by the cylindrical fixed lower punch t61 corresponding to the dimensions. Then, a granulated material ση of non-magnetic ferrite (for example, Zn 7 elite) is filled to a thickness 2 to 3 times the thickness of the non-magnetic substrate portion of the molded product. Next, as shown in Fig. 7 Φ), slide the upper punch (7 mallets) within the cylindrical space formed by the die 51 and the lower punch, and press 4 to 8 t/cm''.
Pressure mold with moderate pressure. Furthermore, as shown in FIG. 7(c), high magnetic permeability low loss ferrite (for example, Ni-Zn
The granulated material σω of 7 Elite) is filled to a thickness that is 2 to 3 times the thickness of the magnetic core portion of the molded product. As shown in Fig. 7(d), the upper punches (B) and (C) form the facing surface of the rotary transformer, Q3υ, upper punch, and upper punch (C) form the first winding groove, and the two channels. An upper punch for forming a groove diagram (see FIG. 7(e)) for separating and making the two parts independent is adjusted to a predetermined level difference and arranged. Next, slide the upper punch in the cylindrical space formed by the die and lower punch to generate 4 to 8 t/cr.
Pressure mold with a pressure of about n''. At this time.

The upper punch (to) is made to pierce through the bonding surface between the six high magnetic permeability, low loss ferrites and the non-magnetic ferrite ση.

Thereafter, the molded product is taken out from the die 6) and subjected to firing and polishing as described above.

As the compression molding process, various methods other than those described above can be considered, and it is also easy to use modified versions of the above method.

According to the method for manufacturing a rotary transformer according to this embodiment, a rotary transformer can be manufactured using substantially the same manufacturing process as a conventional rotary transformer.

In addition, since each annular magnetic core is integrally compression-molded and then fired together with the non-magnetic annular substrate, there is no need to position and arrange the annular magnetic cores with high precision in consideration of concentric accuracy, and the annular magnetic cores and the non-magnetic substrate are There is no need to use non-magnetic adhesive or the like for bonding. Therefore, the characteristics of the annular magnetic core do not deteriorate over time.

〔Effect of the invention〕

As described above, according to the rotary transformer according to the present invention, crosstalk between channels can be significantly reduced compared to the conventional one.
It is also possible to use it in a wideband magnetic recording/reproducing device whose maximum frequency is several tens of MHz.

In addition, according to the method for manufacturing a rotary transformer according to the present invention, the rotary transformer described above using ferrite can be manufactured using substantially the same manufacturing process as the conventional method, thereby providing a rotary transformer with good performance at approximately the same cost. I can do it. Furthermore, there is no need to position and arrange a plurality of annular magnetic cores concentrically and with high precision on a non-magnetic substrate, and manufacturing is easy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of a four-tally transformer according to the present invention, and FIG. 2 is a diagram showing another embodiment. FIG. 3 is a flowchart showing an outline of the method for manufacturing the rotary transformer according to the present invention, and FIG. 4 is a diagram showing an embodiment of the method for manufacturing the rotary transformer shown in FIG. FIG. 5 to FIG. 7 are diagrams similarly showing other manufacturing methods. Fig. 8 is a diagram showing an example of a conventional rotary transformer, Fig. 9 is a diagram for explaining the magnetic coupling state and crosstalk state of the rotary transformer, and Fig. 10 is a diagram for explaining the magnetic coupling state and crosstalk state of the rotary transformer. Conventional low u, 25... winding,
26...Fixed side rotary transformer. I...Rotating side four-tally transformer. sl, S2...Material production process, S3. S4... Granulation process. S5... Compression molding process, S6... Phosphoric acid process. S7... Finishing process. Agent Patent Attorney Nori Ken Chika Yudo Hiroshi Uji 1 1 Portal Figure 2 Figure 4 Figure 5 Figure 8 Figure 9

Claims (2)

[Claims] (1) An annular substrate made of a low magnetic permeability material, a plurality of annular magnetic cores made of a high magnetic permeability, low loss material arranged concentrically at predetermined intervals on this annular substrate, and provided in this annular core. A rotary transformer in which core assemblies having windings disposed in grooves are arranged opposite each other with a predetermined gap in between so that the windings face each other. (2) A process for producing high magnetic permeability, low loss ferrite and non-magnetic ferrite materials, a granulation process to align the grains of these materials, and a high magnetic permeability, low loss ferrite material on an annular substrate made of non-magnetic ferrite. The granulated material of the non-magnetic ferrite and high magnetic permeability low loss ferrite is compression molded so that a plurality of annular magnetic cores each having a groove are arranged concentrically at a predetermined distance from each other. a step of firing a ferrite core with a composite structure obtained through this step, a step of processing the fired ferrite core to a predetermined dimensional accuracy, and arranging a winding wire in the groove of the annular magnetic core of the ferrite core. A method for manufacturing a rotary transformer, comprising the steps of: