JPH03227002A - Manufacture of rotary transformer - Google Patents

Abstract

PURPOSE:To accomplish both cost reduction and production yield improvement through automation by a method wherein conductive ink is jetted out from a jetting nozzle on the surface of the core for a rotary transformer, the core and the jetting nozzle are relatively shifted, and a coil pattern and a short-ring pattern are formed on the surface of the core by the ink. CONSTITUTION:While conductive ink 3 is jetted out from a jetting nozzle 2 on the surface of a rotary transformer core 1 consisting of disc-shaped ferrite, the rotary transformer core 1 is rotated in the specific direction, and at the same time, the jetting nozzle 2 is shifted in the prescribed direction. A helical coil pattern is made on the surface of the rotary transformer core 1 by the relative movement of the core and the nozzle. When a short-ring pattern is made, the rotary transformer core 1 only is rotated in the prescribed direction, and the jetting nozzle 2 is fixed. After the desired coil pattern and the short-ring pattern have been drawn, the whole core is put in a high-temperature atmosphere, the resin ingredient contained in the conductive ink 3 is removed, conductivity is obtained, and a coil and a short ring are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a rotary transformer used for transmitting and receiving signals to and from a rotating magnetic head of a video tape recorder 1, digital audio tape recorder, etc.

Conventional rotary transformers include a disk type in which a groove is provided in a disk-shaped ferrite core and a coil made of coated copper wire is inserted into the groove, and a disk type in which a groove is similarly provided in a cylindrical ferrite core and a coil made of coated copper wire is inserted into the groove. There are two types: a cylindrical type (generally called a coaxial type) in which a coil made of copper wire is inserted.

FIG. 3 is a top view of the disk type rotary transformer, and FIG. 4 is a cross-sectional view taken along line A-A' in FIG.

In FIGS. 3 and 4, 1) is a ferrite core, and a coil 12 is formed with a coated copper wire in a groove provided on the surface of the ferrite core.
．． 14 was inserted. A short ring 13 prevents coupling between the coils, and a ring-shaped conductor is inserted into a groove provided in the ferrite core 1).

For video tape recorders and digital audio recorders, two rotary transformers having this configuration are used as a set, with the surfaces provided with the coils 12, 14 and the short ring 13 facing each other.

FIG. 5 is a sectional view showing the configuration of a coaxial type rotary transformer.

Reference numeral 15 denotes a ferrite core called an outer core that is attached to the rotor portion of the rotating head, and coils 16 and 17 formed of coated copper wire are inserted into grooves provided on the inner peripheral surface of the ferrite core. 18 is a ferrite core called an inner core attached to the stator part of the rotating head, and coils 19 and 2 formed of coated copper wire in grooves provided on the outer peripheral surface of the ferrite core
1 and the short ring 20 are inserted.

Note that most common disc type rotary transformers have a 5-channel configuration with 5 coils, and coaxial type rotary transformers often have a 5-9 channel configuration, but for the sake of ease of explanation here. It is shown in a two-channel configuration.

The conventional method for manufacturing a disc-type rotary transformer with the above configuration is to insert a ring made of an air-core coil and a conductor wound with coated copper wire the required number of times into a groove provided in the ferrite core 1, and then Fix it with coil 1
2.14 and short ring 13 are formed.

In addition, in the conventional manufacturing method of a coaxial type rotary transformer, a part of the inner coil 19 is wound by directly winding a coated copper wire and a conductor a necessary number of times in a groove provided on the outer periphery of the inner core 18.
．． 21 and a ring 20 are formed.

For the outer part, an air-core coil with coated copper wire wound the required number of times is inserted into a groove provided on the inner periphery of the outer core 15 and fixed with adhesive to form a coil 16.17, similar to a disk-type rotary transformer. form.

Problems to be Solved by the Invention In such a conventional rotary transformer manufacturing method, apart from a part of the coaxial type inner, an air core coil and a short ring are made in advance and fixed with adhesive. Rotary transformers become expensive as they cannot be automated. In addition, when inserting an air-core coil into the coaxial type outer core 15, the circular air-core coil is deformed into a heart shape in advance, and the deformed air-core coil is inserted into the groove provided on the inner periphery of the outer core 15. However, since a jig is used to return the shape to the original shape, mistakes are often made during the transformation into the heart shape and when the shape is returned to the shape of the heart, resulting in poor yield.

SUMMARY OF THE INVENTION In view of the problems of the conventional manufacturing method described above, an object of the present invention is to provide a method for manufacturing a rotary transformer that can be automated and has a high yield.

Means for Solving the Problem In order to solve this problem, the present invention jets conductive ink from a jet nozzle onto the surface of a core for a rotary transformer, and moves the core for a rotary transformer and the jet nozzle relatively. and forming a coil pattern and a short ring pattern using the conductive ink on the surface of the rotary transformer core, and then curing the conductive ink by heating to develop conductivity to form a coil and a short ring. This is what I did.

Effects By having the above structure, the present invention can form coils and short rings directly on the disc-shaped and cylindrical rotary transformer cores, and can reduce costs through automation and improve yield.

Example Hereinafter, the present invention will be explained in detail based on examples.

FIG. 1 is a perspective view showing one embodiment of the present invention. Reference numeral 1 denotes a rotary transformer core made of disk-shaped ferrite, and conductive ink 3 is jetted onto the surface of the rotary transformer core 1 from a jetting nozzle 2. While rotating, the rotary transformer core 1 is rotated in a fixed direction, and at the same time, the injection nozzle 2 is moved in a fixed direction. Due to this relative movement between the two, a spiral coil pattern is provided on the surface of the rotary transformer core 1. When providing a short ring pattern, only the rotary transformer core 1 is rotated in a fixed direction, and the injection nozzle 2 is fixed.

After drawing the desired coil pattern and short ring pattern, the whole is placed in a high-temperature atmosphere to remove the resin component contained in the conductive ink 3 and develop conductivity.
Form a coil and short ring.

Both ends of each coil are led out to the opposite surface of the rotary transformer core 1 through through holes (not shown) provided in the rotary transformer core 1 in advance and connected to external terminals (not shown).

The injection nozzle can be driven by compressed air. Further, like the inkjet head of a printer, which is an OA terminal, it can also be driven by a piezoelectric element.

FIG. 2 is a sectional view showing another embodiment of the present invention.

In the figure, 5 is a rotary transformer core made of cylindrical ferrite, and an injection nozzle 6 is provided on the inner peripheral surface of the rotary transformer core.
The rotary transformer core 5 is rotated in a fixed direction while the conductive ink 7 is jetted from the rotary transformer core 5, and at the same time, the jet nozzle 6 is moved in a fixed direction. Due to this relative movement between the two, a spiral coil pattern is provided on the inner peripheral surface of the rotary transformer core 5. When providing a short ring pattern, only the rotary transformer core 5 is rotated in a fixed direction, and the injection nozzle 6 is fixed.

After drawing the desired coil pattern and short ring pattern, the entire body is placed in a high-temperature atmosphere in the same manner as in the previous embodiment, the resin component contained in the conductive ink 6 is removed to develop conductivity, and the coil and short ring patterns are drawn. form a ring.

Both ends of each coil are led out to the outer peripheral surface of the rotary transformer core 5 through through holes (not shown) provided in the rotary transformer core 5 and connected to external terminals (not shown) as in the previous embodiment. .

According to this embodiment, it is possible to form a short ring even in a part of the outer part, which has been extremely difficult in the past, and crosstalk between channels can be significantly improved.

Note that the formation of the coil and short ring on a part of the inner is omitted because the only difference is that the surfaces on which these are formed are the inner and outer surfaces of the cylindrical core.

In addition, a recess is provided in advance in the part where the coil will be formed,
If a coil is formed in the recess and a short ring is formed on a normal surface, the efficiency of blocking the magnetic flux of the short ring can be improved and crosstalk between channels can be significantly improved.

This effect is the same for both disk and cylindrical image shapes.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, an air-core coil is created and inserted by spraying conductive ink directly onto the surface of a core for a rotary transformer using a spray nozzle to form a coil and a short ring.

There is no need for adhesives, a large degree of automation can be achieved, and an inexpensive rotary transformer can be provided.

In addition, a short ring can be formed even in a part of the outer layer, which has been extremely difficult in the past, and crosstalk between channels can be significantly improved.

Further, by forming the coil in a recess provided in the rotary transformer core, crosstalk between channels can be further improved.

[Brief explanation of drawings]

1 and 2 are a perspective view and a sectional view showing an embodiment of the present invention, FIGS. 3 and 4 are a top view and a sectional view showing a conventional example, and FIG. 5 is a top view and a sectional view showing a conventional example. FIG. 1.5...Core for rotary transformer, 2.6
...Ejection nozzle, 3,7... Conductive ink.

Claims (4)

[Claims] (1) Spray conductive ink from a jet nozzle onto the surface of the rotary transformer core, move the rotary transformer core and the jet nozzle relatively, and form a coil pattern and a short ring on the surface of the rotary transformer core. A method for manufacturing a rotary transformer, which comprises forming a pattern and then heating and curing the conductive ink to make it conductive, thereby forming a coil and a short ring. (2) The method for manufacturing a rotary transformer according to claim 1, wherein the rotary transformer core is disc-shaped. (3) The method for manufacturing a rotary transformer according to claim 1, wherein the rotary transformer core has a cylindrical shape. (4) The method for manufacturing a rotary transformer according to claim 1, wherein a recessed portion deeper than at least the thickness of the heat-cured conductive ink is provided in a portion of the surface of the rotary transformer core where a coil pattern is to be formed.