JPH05326277A - Rotating transformer molded in two colors - Google Patents

Abstract

PURPOSE:To obtain a rotary transformer molded in two colors, which can improve crosstalk without widening the interval between adjacent channels. CONSTITUTION:This is a rotating transformer molded in two colors in which an Ni-Zn ferrite 1 is arranged in the channel formation part and an Mn-Zn ferrite 2 is arranged on the boundary with a channel and which is sintered under the condition of raising the permeability of this Ni-Zn ferrite 1 and lowering the permeability of this Mn-Zn ferrite 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-color molding rotary transformer suitable for application to a rotary magnetic head device such as a video tape recorder or a digital audio tape recorder.

[0002]

2. Description of the Related Art Conventionally, a rotary transformer is used for transmitting a signal obtained by a rotary magnetic head provided on a rotary side in a rotary magnetic head device such as a video tape recorder or a digital audio tape recorder to a fixed side circuit. It was widely used as a connection means.

Generally, this rotary transformer is composed of a rotor provided on the rotating side and a stator provided on the fixed side, and the rotor and the stator are arranged on one side surface of a substantially disk-shaped magnetic core according to the number of channels. It is manufactured by winding a concentric coil. Then, the rotor and the stator are arranged so as to face each other with a minute gap, and by electromagnetic coupling between the coils of the rotor and the stator, for example, a rotating magnetic head connected to the rotor and a reproducing circuit connected to the stator are connected, It is designed to transmit video signals and digital audio signals.

By the way, in order to manufacture the rotor or the stator of this rotary transformer, magnetic powder such as ferrite is pressed by a die and then sintered at a high temperature to obtain a magnetic material having concentric grooves and holes. The method of making the core has been adopted.

On the other hand, as one of the methods for improving the crosstalk between the adjacent channels of the rotary transformer, a method of increasing the distance between the adjacent channels has been adopted.

[0006]

However, with the recent miniaturization, the conventional rotary transformer described above has a problem that it is difficult to secure a sufficient distance.

The present invention has been made in view of the above problems, and an object thereof is to obtain a two-color molding rotary transformer capable of improving crosstalk without increasing the distance between adjacent channels.

[0008]

In the two-color molding rotary transformer of the present invention, one of Ni--Zn ferrite 1 and Mn--Zn ferrite 2 is arranged in the channel forming portion, and a channel boundary is provided. The remaining one of the two ferrites 1 or 2 is placed in the section, and the other ferrite is placed under a condition of increasing the magnetic permeability of the other ferrite and lowering the magnetic permeability of the other ferrite. To do.

[0009]

According to the two-color molding rotary transformer of the present invention, the Ni-Zn system ferrite 1 is provided in the channel forming portion.
Alternatively, one of the Mn-Zn-based ferrites 2 is arranged, and the other of the two ferrites 1 or 2 is arranged at the channel boundary, and the magnetic permeability of the one ferrite is Even if the distance between adjacent channels is not widened by increasing the temperature and sintering under the condition that the magnetic permeability of the other ferrite is decreased.
Since the generation of leakage magnetic flux to the adjacent channel is suppressed,
Crosstalk can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the two-color molding rotary transformer of the present invention will be described below with reference to FIGS. Figure 1
Is a Ni-Zn system ferrite 1 in the channel forming portion.
And a Mn—Zn-based ferrite 2 is disposed at the channel boundary to increase the magnetic permeability of the Ni—Zn-based ferrite 1 and reduce the magnetic permeability of the Mn—Zn-based ferrite 2. It shows a two-color molding rotary transformer which is sintered in.

In this example, the channel boundary portion becomes a low-permeability material by using the two-color molding method and by sintering under an unsuitable condition for the material arranged at the channel boundary portion. .

First, an outline of a method of manufacturing the rotary transformer of this example will be described. In order to manufacture a rotor or a stator of a rotary transformer, first, an appropriate amount of a binder (mainly 15 to 20% of a thermoplastic resin such as polypropylene or low molecular weight acrylic resin is added to a mold of an injection molding machine having a structure similar to that of ordinary plastic molding. Mixing) and injecting the kneaded ferrite powder to prepare a disk-shaped magnetic core. The resulting molded product (magnetic core) has less residual stress because the ferrite powder is uniformly pressed in all directions in the mold. In addition to the above binder, additives such as a plasticizer, a dispersant, and a lubricant may be added if necessary.

Here, the specific contents of the method for manufacturing the rotary transformer of this embodiment will be described in the order of steps. The manufacturing method of this example is called two-color molding because it is composed of two kinds of ferrite materials having different compositions.

An example of the composition of the ferrite used in this example is as follows. Ni-Zn-based _{Fe 2 O 3: 50mol% ZnO} : 30mol% NiO: 10mol% CuO: 10mol% Mn-Zn -based _{Fe 2 O 3: 52mol% MnCO} 3: 30mol% ZnO: 18mol%

FIG. 2 shows an example of the structure of a mold for injection molding the flat facing rotary transformer of this embodiment. First, as shown in FIG. 2A, a mold A, a mold B,
Then, the mold C is installed, and Ni—Zn ferrite (kneaded with the binder) is molded. Next, as shown in FIG. 2B, Mn—Zn-based ferrite (kneaded with a binder) is molded into a space (cavity) formed by retracting the mold C upwards, thereby making The rotary transformer is completed. .. In other embodiments, which will be described later,
The mold shown in FIG. 2 can be used as it is, and various rotary transformers can be manufactured by setting the mold C.

Next, the magnetic core is heated at a predetermined temperature to remove the organic components such as the binder contained therein (so-called degreasing), and the temperature is further raised to be fired. By this degreasing and firing, the volume of the magnetic core contracts, but the shape is maintained.

The sintering conditions of the two-color molding rotary transformer of this example are as shown in FIG. The optimum sintering atmosphere for the Ni-Zn ferrite is air. That is, O
The condition is ₂ : 20% and N ₂ : 80%. Under these conditions, it is an unsuitable condition for the magnetic permeability of Mn-Zn ferrite. For example, when Mn—Zn ferrite is sintered in air, the magnetic permeability becomes 100 or less.
That is, the magnetic properties of Mn-Zn ferrite are significantly reduced.

FIG. 4 is a case opposite to the above example, that is, the sintering conditions in the case where Mn-Zn type ferrite is used for the channel forming portion are illustrated. Mn-Zn
The optimum sintering atmosphere of the system ferrite is an atmosphere containing N2 as a main component. That is, O ₂ : 5 to 10%, N ₂ :
90 to 95%. Under this condition, the magnetic permeability of the Ni—Zn system ferrite forming the channel boundary portion is lowered.

Next, another embodiment of the two-color molding rotary transformer of the present invention will be described with reference to FIGS. As another embodiment of the flat facing type two-color molding rotary transformer in this example, as shown in FIG. 5, the channel boundary is partially cut off to increase the mechanical strength of the rotary transformer. 6, which has a recess on the facing surface side, and a short ring or metal paste (Cu, Ag) in the recess as shown in FIG.
Etc.) to improve the crosstalk. In the embodiment shown in FIG. 7, the counter electromotive force is generated by the eddy current to improve the crosstalk prevention effect.

From the above, according to this example, the Ni-Zn system ferrite 1 or Mn- is formed in the channel forming portion.
One of the Zn-based ferrites 2 is arranged, and the other of the two ferrites 1 or 2 is arranged at the channel boundary, and the permeability of this one ferrite is increased, Moreover, by sintering the other ferrite under the condition of lowering the magnetic permeability, crosstalk can be improved without widening the distance between adjacent channels.

The present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0022]

As described above, according to the present invention,
Crosstalk can be improved without increasing the distance between adjacent channels.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a two-color molding rotary transformer of the present invention.

FIG. 2 is a configuration diagram showing an example of a molding method of the two-color molding rotary transformer of the present invention.

FIG. 3 is a diagram showing sintering conditions of the two-color molding rotary transformer of the present invention.

FIG. 4 is a diagram showing sintering conditions of the two-color molding rotary transformer of the present invention.

FIG. 5 is a configuration diagram showing another embodiment of the two-color molding rotary transformer of the present invention.

FIG. 6 is a configuration diagram showing another embodiment of the two-color molding rotary transformer of the present invention.

FIG. 7 is a configuration diagram showing another embodiment of the two-color molding rotary transformer of the present invention.

[Explanation of symbols]

 1 Ni-Zn system ferrite 2 Mn-Zn system ferrite

Claims (1)

[Claims] 1. The channel forming portion is provided with either one of Ni-Zn type ferrite and Mn-Zn type ferrite, and the channel boundary portion has the other remaining ferrite of the two ferrites. A two-color molding rotary transformer, characterized in that the above-mentioned one ferrite is sintered under the conditions of increasing the magnetic permeability of the one ferrite and decreasing the magnetic permeability of the other ferrite.