JPH07201587A - Pulse transformer for isdn - Google Patents

Abstract

PURPOSE:To provide a pulse transformer which satisfies the height requirement and the requested characteristics and which can be manufactured easily by locating parallelly two pipe-like magnetic cores which are made by winding a Co-base amorphous ribbon in the specific thickness or below and by applying a winding which passes through two through holes around the facing side faces of the magnetic cores. CONSTITUTION:Using a Co-base amorphous ribbon (thinner than 15mum), magnetic cores are manufactured. Then, the magnetic cores 1 are heat-treated in a nitrogen atmosphere. Six parallel wires are wound (2) eight turns using a wire rod 3 and a pulse transformer of 16 turns at the primary side and 32 turns at the secondary side is manufactured. Out of the six parallel wires, two wires are connected in series to make a 16-turn winding and four wires are connected in series to make a 32-turn winding. A pulse transformer for ISDN is manufactured by installing the pipe-like magnetic cores in through holes 12 of a case 11. For preliminary preparations, a wire rod 3 which constitutes the primary coil is colored. By this method, a pulse transformer which satisfies the characteristics of a pulse transformer for ISDN and which can be made thin and can be manufactured easily can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ISDN pulse transformer.

[0002]

2. Description of the Related Art A pulse transformer for ISDN is 20 kHz.
It is necessary to guarantee a high inductance of 20 mH or more in z, and to realize a low capacitance and a low leakage inductance. Conventionally, a bobbin with a winding is combined with a pot type, EI type, EE type, or the like ferrite core. Alternatively, the ring-shaped ferrite magnetic core is provided with windings. Alternatively, the winding core is formed by attaching an insulating case or epoxy coating to a winding magnetic core formed by winding a Co-based amorphous material.

[0003]

Since the recent ISDN pulse transformer is housed in an IC card, the minimum height is 5 mm or less, and in reality, the height is 3.6 mm or 2.8 mm.
The following ultra-thin dimensions are required. The card size is also limited to 54 × 85.6 mm, and it is necessary to mount two transformers for drive and receive within this area. When an ISDN pulse transformer that can be housed in this IC card is to be constructed, the conventional pot type, EI type, and EE type ferrite cores have a magnetic permeability of at most 8000 to 10000, and a high inductance at the required size. To achieve this, a huge number of turns is required, resulting in an increase in leakage inductance or an increase in capacity, so that it is very difficult and unrealistic to satisfy the required characteristics. Further, when a ring-shaped ferrite magnetic core is used, a maximum magnetic permeability of about 15,000 can be obtained, but still a large number of turns is required. Assuming a trial calculation, μi = 15,000
When a ring-shaped ferrite magnetic core of R11-3-4H is used, the minimum diameter is 49 turns with a 0.05φ wire rod, which is not a realistic specification. This estimation is μi = 15000 MI
N. However, the specifications will be more strict when considering variations in characteristics and temperature characteristics. Further, the increase in the number of turns in the ring-shaped ferrite magnetic core causes the following problems. 1) Difficult work and cost increase. 2) The occurrence rate of interlayer insulation failure increases. 3) If the number of windings is only one layer, the effect on the coil height is small. 4) Increase in winding capacity. 5) Increased leakage inductance. On the other hand, the Co-based amorphous winding magnetic core has a magnetic permeability of 10,000.
Although a very high value such as 0 can be obtained, there are the following drawbacks. 1) A typical thin ring-shaped winding magnetic core has a magnetic core height of 3 mm.
However, it is difficult to manufacture a ribbon having a width narrower than that of the ribbon manufacturing and winding of the core, resulting in an increase in cost. 2) When winding a ribbon having a width of 3 mm, the height of the magnetic core varies up to about 3.5 mm because the ribbon is displaced. Furthermore, when the winding is performed in one layer on the ring-shaped magnetic core, an unnecessary space is formed in the center of the winding frame, which hinders downsizing of the coil. Therefore, it has been extremely difficult to satisfy the required characteristics and required dimensions even with the conventional Co-based amorphous winding magnetic core. Further, in recent years, there is a limit to the reduction of the leakage inductance, and a circuit for preventing the leakage inductance has been devised, which makes the required characteristics complicated. This circuit determines the operation of the circuit by detecting the undershoot of the transmission pulse, and does not operate normally when the leakage inductance is small. Therefore, when using this circuit, it is required to increase the leakage inductance to some extent contrary to the original requirement. In general, the leakage inductance of a transformer can be increased by roughly winding the windings and separating the primary and secondary windings. However, if the coil is roughly wound, the value of the leakage inductance cannot be controlled and the quality is deteriorated. On the other hand, if the primary winding and the secondary winding are separated, the winding needs to be divided into two, which leads to an increase in cost. The problems as described above occur, and it has been practically impossible in the past to satisfy both the height dimension and the required characteristics. In view of the above, it is an object of the present invention to provide a pulse transformer for ISDN that satisfies both the height dimension and required characteristics and is easy to produce.

[0004]

As a result of research to solve the above-mentioned problems, it was found that both the height dimension and the required characteristics can be satisfied with the following constitution. The present invention is configured by arranging two pipe-shaped magnetic cores formed by winding a Co-based amorphous material having a maximum thickness of 15 μm or less in parallel and providing bifilar windings passing through two through holes with opposite side faces as a center. It is a pulse transformer for ISDN. Further, the bifilar winding uses at least three parallel wires, and at least two of them are connected to form a coil by connecting the winding start end and the winding end end to form a transformer having a winding ratio of 1: 2. To do. In addition, at least one of the bifilar windings is colored.
The number of turns of the primary coil and the secondary coil of the bifilar winding is set to an integral number to reduce the leakage inductance. Further, the number of turns of at least one coil of the bifilar winding is set to an integral number of +0.5, and the leakage inductance is increased to be used together with the leakage inductance countermeasure circuit. Further, in the present invention, μe = 3
It is desirable to use a material of 0000 or more. This Co
In the case of the basic amorphous magnetic core material, it is preferable to perform coating or case encapsulation because it is necessary to perform protection and insulation treatment. Moreover, the leakage inductance is reduced by setting the number of turns to an integral number. Further, assuming a circuit for preventing leakage inductance, the leakage inductance is increased by setting the number of turns of at least one coil to an integral number +0.5.

[0005]

According to the present invention, a pipe-shaped magnetic core is provided,
With this pipe-shaped magnetic core, a high AL value can be obtained and the number of turns can be reduced without increasing the outer diameter of the magnetic core. In addition, since bifilar windings that pass through the two through holes centering on the opposite side surfaces of the two magnetic cores are provided,
The winding does not appear on the outer diameter of the core, and the height dimension corresponding to the winding thickness can be reduced. As the magnetic core size, the outer diameter is 4 mm or less,
The core length is preferably 30 mm or less, whereby a pulse transformer that sufficiently satisfies the characteristics and can be mounted can be obtained. More preferably, the outer diameter is 2.4 to 2.0 mm, the inner diameter is 1.3 to 1.7 mm, and the length is 10 to 30 mm, and the height is 2.8 mm MAX. And a pulse transformer with sufficient characteristics is obtained, which is optimal. The above dimensions are C
This is the case where an o-based amorphous material is used, and it is difficult to satisfy the characteristics and dimensions by using a ferrite core.
The reason is that with ferrite, only about μ = 15,000 can be obtained, and the number of turns is required to be about 1.4 times that of the present invention, and the characteristics cannot be satisfied unless the core is enlarged. Needless to say, coating and enclosing the case is to insulate and protect the core and insulate the coil from coil to coil. Setting the number of turns of the coil to an integral number for reducing the leakage inductance is intended to obtain the following effects. Setting the number of turns of the coil to an integral number for reducing the leakage inductance is intended to obtain the following effects.
According to the configuration of the present invention, two pipe-shaped magnetic cores are arranged and the bifilar winding is provided around the opposite side faces. The bifilar winding is a configuration for reducing the leakage inductance. However, in the configuration in which the winding start end and the winding end end of the coil are both ends in the longitudinal direction of the magnetic core, 0.
There are 5 turns, which creates an air-core coil and increases leakage inductance. Therefore, since the winding start end and the winding end end of the coil are concentrated at one end in order to make the number of turns an integer number, and the air-core coil is not formed, the leakage inductance can be reduced. On the other hand, assuming a specific circuit, it is necessary to increase the leakage inductance as described above. In such a case, the requirement can be met by adopting an integer number of turns + 0.5 turns. Also Co
The reason why the thickness of the base amorphous ribbon is limited to 15 μm or less is that workability and yield in manufacturing the wound magnetic core are taken into consideration. That is, a general amorphous ribbon has a thickness of 17 to 25 μm, but the thicker the ribbon, the more difficult it is to wind the inner diameter of the magnetic core so small. The biggest problem that makes this winding difficult is breakage of the ribbon. Table 1 shows the experimental results of this ribbon thickness and ribbon breakage. The ribbon thickness in Table 1 is
It is the minimum thickness and the maximum thickness of each ribbon, and the number of breaks is the number of breaks when 100 turns are wound around an inner diameter of 1.5 mm.
As can be seen from Table 1, when the maximum thickness is 15 μm or less, breakage is small and workability and yield are good.

[0006]

[Table 1]

[0007]

【Example】

Example 1 Co-based amorphous (ACO-4 material manufactured by Hitachi Metals, Ltd.)
Using the ribbon (maximum thickness 15 μm, width 15 mm)
A wound magnetic core having an outer diameter of 2.2 mm, an inner diameter of 1.5 mm and a length of 15 mm was prepared and heat-treated in a nitrogen atmosphere at 450 ° C. for 1 hour. When the characteristics of this pipe-shaped magnetic core were measured,
= 40000, and the AL value was 45.4 μH / N ^ 2.
A 80 μm-thick parylene coating was applied to this magnetic core, and 6 parallel wires were wound 8 turns using a 0.06φ wire rod to obtain a primary 16-turn and secondary 32-turn pulse transformer. At this time, of the six parallel lines, two were connected in series for 16 turns, and four were connected in series for 32 turns. A perspective view of this embodiment is shown in FIG. In FIG. 1, 1 is a magnetic core, 2 is a winding wire, and 3 is a wire rod. A front view of the case in which the magnetic core is arranged is shown in FIG.
The back view is shown in FIG. The case 11 has a through hole 12 into which the pipe-shaped magnetic core 1 (shown by a broken line in the figure) is inserted, and a plurality of wiring terminals 13 are recessed on the side surface side parallel to the axis of the through hole 12. A groove 14 for wiring for passing a lead wire is formed between the portion provided with the through hole 12 and the portion provided with the wiring terminal. There is. The pipe-shaped magnetic core 1 is arranged in the through hole 12 of the case 11 to provide the ISDN.
A pulse transformer was constructed. This characteristic is as described above. In the present embodiment, the winding state and the case are described separately for convenience of description, but in the present embodiment, the case 11 is used.
Then, the pipe-shaped magnetic core 1 is inserted into the above, and then the above-mentioned winding is applied, and the lead wire (the above-mentioned wire 3) of the winding is attached to the case 11
The pulse transformer is configured by connecting to the wiring terminal 13. In addition, the wiring terminals 13 were used to connect parallel lines in series. When the inductance at 20 kHz of this example was measured, it was 23.2 mH.
And a sufficient inductance was obtained.

Example 2 The same ring-shaped magnetic core as in Example 1 was used. FIG. 4 is a front view of a case that forms a pulse transformer in combination with this magnetic core.
A back view is shown in FIG. The case 21 has a through hole 22 into which the pipe-shaped magnetic core 26 (shown by a broken line in the figure) is inserted, and a plurality of wiring terminals 23 are recessed on the side surface side parallel to the axis thereof. A wiring groove 24 for passing a lead wire is formed between the portion provided with the through hole 22 and the portion provided with the wiring terminal 23 so as to project from the inside. There is. This through hole 22
Is formed into a shape in which two pipe-shaped magnetic cores 26 can be inserted adjacent to each other, and two magnetic cores 26 a and b are formed. The pulse transformer having the structure shown in FIG. 1 is formed in each of a and b, and the ISDN pulse transformer is formed by using a for driving and b for receiving.
In the present embodiment, the winding state and the case are described separately for convenience of description, but in the present embodiment, the pipe-shaped magnetic core 26 is inserted into the case 21, and then the winding is applied and the winding is performed. The lead wire of the wire is connected to the wiring terminal 23 of the case 21 to form the pulse transformer.

Comparative Example 1 Mn-Zn high permeability material (GP manufactured by Hitachi Ferrite Co., Ltd.)
-11 material), outer diameter 2.2 mm, inner diameter 1.5 m
A pipe-shaped magnetic core having a length of m and a length of 15 mm was prepared. When the characteristics of this core were measured, μe = 10000, AL value 1
It was 1.4 μH / N ^ 2. 80 μm thick on this magnetic core
After applying the parylene coating of No. 1 and inserting it into a predetermined bobbin, 6 parallel wires were wound as much as possible using a wire of 0.06φ, and it was 10 turns. This was used as a transformer with primary 20 turns and secondary 40 turns. When the inductance of this transformer at 20 kHz was measured, an insufficient inductance of 9.1 mH was obtained. Table 2 shows the height dimension, the inductance, and the number of coil turns of the above Examples and Comparative Examples.

[0010]

[Table 2]

From Table 2, it can be seen that in the embodiment, the height is not more than 2.8 mm, the inductance is satisfied, and the number of turns is small. Comparative example 1 using ferrite
Then, the required characteristics were not obtained. Table 3 shows the leakage inductance when the core of Example 1 was used and the number of turns of the primary coil was 18 turns and 18.5 turns. About 18.5 turns, one wire rod was extended by half a turn, and was drawn out from the other end face facing the wire rod. It can be seen from Table 3 that this method is effective for controlling the leakage inductance.

[0012]

[Table 3]

Further, in the above-mentioned embodiment, the wire material constituting the primary coil is colored in advance so that the discrimination and the work can be facilitated in the winding work and the terminal tying work. Further, in the above embodiment, the insulation of the pipe-shaped magnetic core is coated, but it is desirable that the coating thickness is 150 μm or less in order to achieve thinning. Also, the insulating means is not limited to coating,
You may use a case. In this case, the thickness of the case is
It is desirable that the thickness is 0.15 mm or less.

[0014]

As described above, according to the present invention, ISDN is used.
It is possible to satisfy the characteristics of the pulse transformer for use and achieve thinning, and it is also effective for simplifying the manufacturing method.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment according to the present invention.

FIG. 2 is a front view of a case according to an embodiment of the present invention.

FIG. 3 is a back view of the case of the embodiment according to the present invention.

FIG. 4 is a front view of a case according to another embodiment of the present invention.

FIG. 5 is a back view of a case according to another embodiment of the present invention.

[Explanation of symbols]

 1, 26 Magnetic core 2 Winding 3 Wire rod 11, 21 Case 12, 22 Through hole 13, 23 Wiring terminal 14, 24 Wiring groove 15, 25 Recess

Claims (5)

[Claims] 1. A pipe-shaped magnetic core formed by winding a Co-based amorphous material having a maximum thickness of 15 μm or less is arranged in parallel, and a bifilar winding passing through two through-holes around opposite sides is provided. IS characterized by being
Pulse transformer for DN. 2. The bifilar winding according to claim 1, wherein at least three parallel wires are used, and at least two of them are connected to form a coil by connecting a winding start end and a winding end end.
A pulse transformer for ISDN, characterized in that it constitutes a transformer having a turns ratio of 1: 2. 3. The ISD according to claim 1, wherein at least one of the bifilar windings is colored.
Pulse transformer for N. 4. The ISD according to claim 1, wherein the number of turns of the primary coil and the secondary coil of the bifilar winding is an integral number to reduce leakage inductance.
Pulse transformer for N. 5. The method according to claim 1, wherein at least one coil of the bifilar winding has an integral number of turns +0.5 times to increase a leakage inductance and is used together with a leakage inductance countermeasure circuit. ISDN
Pulse transformer for.