JP2866794B2 - Pulse transformer for ISDN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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 ferrite core of a pot type, an EI type, an EE type, or the like is combined with a bobbin with a winding. Alternatively, the ring-shaped ferrite core is formed by winding. Alternatively, a winding core is formed by attaching an insulating case or an epoxy coating to a wound core formed by winding a Co-based amorphous.

[0003]

In recent years, a pulse transformer for ISDN has a minimum height of 5 mm or less, and actually has a height of 3.6 mm or 2.8 mm in order to be housed in an IC card.
Ultra-thin dimensions such as the following are required. Also, the card size is limited to 54 × 85.6 mm, and it is necessary to mount two transformers for drive and receive within this area. When an attempt is made to construct a pulse transformer for ISDN that can be accommodated in this IC card, a conventional ferrite core such as a pot type, EI type, or EE type has a magnetic permeability of at most 8000 to 10000, and a high inductance with a required size. In order to obtain the required number of turns, an enormous number of turns is required, resulting in an increase in leakage inductance or an increase in capacity. Therefore, it is extremely difficult and unrealistic to satisfy required characteristics. When a ring-shaped ferrite core is used, a magnetic permeability of about 15000 can be obtained at the maximum, but a large number of turns is still required. Assuming a trial calculation, μi = 15000 and O
When a ring-shaped ferrite core of R11-3-4H is used, at least 49 turns are required with a 0.05 mm wire, which is not a realistic specification. This calculation shows that μi = 15000MI
N. It is a stricter specification in consideration of the variation in characteristics, temperature characteristics, and the like. Further, an increase in the number of turns in the ring-shaped ferrite core causes the following problem. 1) Difficulty of work, increased cost. 2) The occurrence rate of interlayer insulation failure increases. 3) If the number of windings is one, the effect on the coil height is small. However, if the number of windings is two or three, the effect on the coil height is large and the production variation is large. 4) Increase in winding capacity. 5) Increase in leakage inductance. On the other hand, a Co-based amorphous core has a permeability of 10,000.
A very high value such as 0 can be obtained, but has the following disadvantages. 1) A general thin ring-shaped wound core has a core height of 3 mm.
It is difficult to manufacture a ribbon having a smaller width than this, and it is difficult to manufacture the ribbon and to wind up the core, which leads to an increase in cost. 2) When winding a ribbon having a width of 3 mm, the ribbon core is shifted, so that the magnetic core height varies up to a maximum of about 3.5 mm. Further, when the winding is performed on the ring-shaped magnetic core with one layer, an unnecessary space is formed at the center of the winding frame, which hinders miniaturization of the coil. Therefore, it has been extremely difficult to satisfy the required characteristics and required dimensions even with a conventional Co-based amorphous wound core. The above-described problems occur, and it has been practically impossible to satisfy both the height dimension and the required characteristics in the past. The present invention, in view of the above,
ISD that satisfies both height dimensions and required characteristics and is easy to produce
An object is to provide a pulse transformer for N.

[0004]

As a result of conducting research to solve the above-mentioned problems, it has been found that both the height and the required characteristics can be satisfied with the following configuration. The present invention is configured by arranging two pipe-shaped cores made of an Fe-based ultra-microcrystalline soft magnetic alloy having a maximum thickness of 15 μm or less in parallel and applying a winding passing through two through holes centering on opposing side surfaces. Is a pulse transformer for ISDN. Further, the preferred size of the magnetic core is 4 mm or less in outer diameter,
The length is 30 mm or less, and more preferably, the outer diameter is 2.4.
~ 2.0mm, inner diameter 1.3 ~ 1.7mm, length 10 ~ 3
0 mm. The magnetic core has a thickness of 150 μm.
It is preferable to enclose in the following coating or a case having a thickness of 0.15 mm or less for insulation. In the present invention, it is preferable to use a material having μe = 30000 or more.

[0005]

According to the invention, a pipe-shaped magnetic core is provided.
With this pipe-shaped core, a high AL value can be obtained without increasing the outer diameter of the core, and the number of turns can be reduced. In addition, since the windings are formed by applying windings passing through the two through holes around the opposite side surfaces of the two pipe-shaped cores, the windings do not appear on the outer diameter of the cores, and the winding thickness is reduced. Height dimensions can be reduced. The outer diameter of the core is 4
If the length is 30 mm or less and the length is 30 mm or less, a coil that satisfies the characteristics sufficiently and can be mounted can be obtained. More preferably, when the outer diameter of the magnetic core 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, the height of the pulse transformer is 2.8 mm. And a pulse transformer with sufficient characteristics can be obtained. The above dimensions are for the case of using a Fe-based ultrafine crystal material, and it is difficult to satisfy the characteristics and dimensions using a conventional ferrite core. The reason is that, with ferrite, only μ = 15,000 can be obtained, the number of turns is required to be about 1.4 times that of the present invention, and the characteristics are not satisfied unless the magnetic core is increased. Needless to say, coating and enclosing the case are for insulation and protection of the magnetic core and insulation with the coil. The reason why the thickness of the ribbon of the Fe-based ultrafine crystal material is limited to the maximum thickness of 15 μm or less is to take into consideration the workability and the yield when manufacturing the wound core.
That is, a typical amorphous ribbon has a thickness of 17 to
Although it is 25 μm, it is difficult to wind up the inner diameter of the magnetic core as much as the thickness of the ribbon is large. The biggest problem that makes the winding difficult is breakage of the ribbon. Table 1 shows the experimental results of ribbon thickness and ribbon breakage. The ribbon thickness in Table 1 is the minimum thickness and the maximum thickness of each ribbon.
Is the number of breaks when wound 100 times. As can be seen from Table 1, when the maximum thickness is 15 μm or less, breakage is small, workability and yield are good.

[0006]

[Table 1]

[0007]

【Example】

Example 1 An outer diameter of 2.2 mm, an inner diameter of 1.5 mm, and a length of 15 mm were obtained using a ribbon (maximum thickness: 15 μm, width: 15 mm) of an Fe-based ultrafine crystal material (FT-3 manufactured by Hitachi Metals, Ltd.). And heat-treated in a nitrogen atmosphere at 570 ° C. for 1 hour. When the characteristics of this pipe-shaped core were measured, μe =
30,000, AL value was 34 μH / N ＾ 2. An 80 μm thick parylene coating is applied to the magnetic core.
Using a 06φ wire, six parallel wires are wound 9 turns, and 1
A pulse transformer of the next 18 turns and the secondary 36 turns was used. FIG. 1 shows a perspective view of this embodiment. In FIG.
1 is a magnetic core, 2 is a winding, and 3 is a wire. When the inductance at 20 kHz of this example was measured, a sufficient inductance of 22.1 mH was obtained.

Example 2 As in Example 1, a ribbon of FT-3 material (maximum thickness 12
μm, 15 mm in width) to make a wound core having an outer diameter of 2.2 mm, an inner diameter of 1.5 mm, and a length of 15 mm.
Heat treatment was performed for 1 hour in a nitrogen atmosphere. When the characteristics of this pipe-shaped core were measured, μe = 45000 and the AL value was 51.1 μH / N ＾ 2. The thickness of this magnetic core is 80μ.
m parylene coating, using 6 wires of 0.06φ, winding 6 parallel wires for 8 turns, primary 16 turns,
A secondary 32 turn pulse transformer was used. When the inductance at 20 kHz of this example was measured,
A sufficient inductance of 26.2 mH was obtained. Using these embodiments, a description will be given of a case where an ISDN pulse transformer in which two transformers for driving and receiving are mounted is configured. FIG. 2 shows a front view of the case used for this, and FIG. 3 shows a back view thereof. The case 11 has a through hole 1 into which a pipe-shaped magnetic core 1 (shown by a broken line in the figure) is inserted.
2 on the side parallel to the axis of the through hole 12,
A plurality of wiring terminals 13 are provided so as to protrude from the inside of the recess 15, and a lead wire for passing a lead wire is provided between a portion where the through hole 12 is provided and a portion where the wiring terminal is provided. A wiring groove 14 is formed. This through hole 1
Reference numeral 2 denotes a shape in which two pipe-shaped magnetic cores 1 can be inserted adjacent to each other, and two a and b are formed. The pulse transformer having the structure as shown in FIG. 1 was constructed for each of a and b, and a pulse transformer for ISDN was constructed with a used for driving and b used for receiving.
In the present embodiment, the winding state and the case are separately described for the sake of explanation. In this embodiment, the pipe-shaped core 1 is inserted into the case 11, and then the winding is applied.
The above-described pulse transformer is configured by connecting the lead wire of the winding to the wiring terminal 13 of the case 11. In addition, the parallel connection of the parallel lines is performed using the wiring terminals 13,
A winding having a predetermined number of turns was constructed. The mounting area of this ISDN pulse transformer was 316.2 mm ＾ 2, which was a sufficiently small area.

Comparative Example 1 Ribbon of Fe-based ultrafine crystal material FT-3 (having a thickness of 17 μm)
m, width 1.5mm), outer diameter 10mm, inner diameter 4m
m and a height of 1.5 mm were prepared and heat-treated at 570 ° C. for 1 hour in a nitrogen atmosphere. When the characteristics of this ring-shaped magnetic core were measured, μe = 50000, AL value
8 μH / N ＾ 2. This magnetic core was housed in a predetermined case, and six parallel wires were wound using a 0.06φ wire for 21 turns to form a 42-turn primary and 84-turn pulse transformer. FIG. 4 shows a perspective view of this comparative example. In FIG. 4, 21 is a magnetic core, 22 is a winding, and 23 is a wire. When the inductance at 20 kHz of this comparative example was measured, a sufficient inductance of 22.7 mH was obtained.

Comparative Example 2 Mn-Zn high permeability material (GP manufactured by Hitachi Ferrite Co., Ltd.)
-11)), outer diameter 2.2mm, inner diameter 1.5m
A pipe-shaped magnetic core having a length of m and a length of 15 mm was prepared. When the characteristics of this magnetic core were measured, μe = 10000, AL value 1
1.4 μH / N ＾ 2. The thickness of this core is 80μm
Was coated with parylene, and 6 parallel wires were wound as much as possible using a 0.06φ wire.
It was a turn. This was used as a transformer with 20 turns of primary and 40 turns of secondary. When the inductance of this transformer at 20 kHz was measured, only an insufficient inductance of 9.1 mH was obtained. The above embodiment,
Table 2 shows the height, inductance, and number of coil turns of the comparative example.
Shown in

[0011]

[Table 2]

From Table 2, it can be seen that in the example, the height did not exceed 2.8 mm, the inductance was satisfied, and the number of turns was small, but in Comparative Example 1, the height was 2.8 mm or less and the inductance was satisfied. However, the number of turns is remarkably large at 42 turns: 84 turns compared to 18 turns: 36 turns of the first embodiment, and it is clear that workability is poor. In Comparative Example 2 using ferrite, required characteristics could not be obtained. In the above embodiment, the coating is applied to the insulation of the pipe-shaped magnetic core. However, the coating thickness is desirably 150 μm or less in order to achieve a reduction in thickness. The insulating means is not limited to the coating, and a case may be used. In this case, it is desirable that the thickness of the case be 0.15 mm or less.

[0013]

As described above, according to the present invention, the ISDN
Therefore, the characteristics of the pulse transformer for use can be satisfied and the thickness can be reduced, and it is effective for simplifying the manufacturing method.

[Brief description of the drawings]

FIG. 1 is a perspective view of one 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 rear view of the case according to the embodiment of the present invention.

FIG. 4 is a perspective view of a comparative example according to the present invention.

[Explanation of symbols]

 1 magnetic core 2 winding 3 wire

Claims (5)

(57) [Claims] 1. A pipe-shaped core made of an Fe-based ultra-microcrystalline soft magnetic alloy having a maximum thickness of 15 μm or less is arranged in parallel, and a winding is made through two through holes centering on opposing side surfaces. A pulse transformer for ISDN, comprising: 2. The magnetic core according to claim 1, wherein the magnetic core has an outer diameter of 4 m.
m or less and a length of 30 mm or less
Pulse transformer for DN. 3. The magnetic core according to claim 1, wherein the magnetic core has an outer diameter of 2.
4-2.0 mm, inner diameter 1.3-1.7 mm, length 10
A pulse transformer for ISDN, which is 30 mm. 4. The pulse transformer for ISDN according to claim 1, wherein the magnetic core is coated with a coating having a thickness of 150 μm or less. 5. The magnetic recording medium according to claim 1, wherein the magnetic core has a thickness of 0.1 mm.
IS enclosed in a case of 15 mm or less
Pulse transformer for DN.