JP2866795B2 - 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 in 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 relates to a pulse transformer for ISDN configured by arranging two pipe-shaped magnetic cores made of a material of μe = 30000 or more in parallel and applying a winding passing through two through holes centering on opposing side surfaces. is there. The preferred dimensions of the magnetic core are 4 mm or less in outer diameter and 30 mm or less in length, and more preferably 2.4 to 2.0 mm in outer diameter, 1.3 to 1.7 mm in inner diameter, and 10 to 30 mm in length. . The magnetic core is preferably coated with a thickness of 150 μm or less or sealed in a case of 0.15 mm or less to achieve insulation. In the present invention, μe = 300
The material having a high magnetic permeability of at least 00 is used.
Co-based amorphous, Fe-based microcrystalline soft magnetic alloy, Permalloy, 6.5% Si silicon steel, and the like.

[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 material of μe = 30000 or more, 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.

[0006]

【Example】

Example 1 Using a ribbon of Fe-based ultrafine crystal material (FT-3 material manufactured by Hitachi Metals, Ltd.) (thickness: 15 μm, width: 15 mm), an outer diameter of 2.2 mm, an inner diameter of 1.5 mm, and a length of 15 mm were used. A wound core was prepared and heat-treated at 570 ° C. for 1 hour in a nitrogen atmosphere. When the characteristics of this pipe-shaped magnetic core were measured, μe
= 30000, AL value 34 μH / N ＾ 2. This core is coated with a 80μm thick parylene coating,
Using a 0.06φ wire, six parallel wires were wound 9 turns to form a primary 18 turn, secondary 36 turn pulse transformer. FIG. 1 shows a perspective view of this embodiment. In FIG. 1, 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 (12 μm thick) was used.
m, width 15 mm) using an outer diameter of 2.2 mm and an inner diameter of 1.
A wound core having a length of 5 mm and a length of 15 mm was prepared and heat-treated at 570 ° C. for 1 hour in a nitrogen atmosphere. When the characteristics of this pipe-shaped core were measured, μe = 45000, AL value 5
1.1 μH / N ＾ 2. The thickness of this core is 80μm
Is applied, and 6 parallel wires are wound by 8 turns using a wire of 0.06φ, and the primary 16 turns, 2 turns
A pulse transformer of the next 32 turns was used. 2 of this embodiment
When the inductance at 0 kHz was measured,
A sufficient inductance of 6.2 mH was obtained.

Example 3 In the same manner as in Example 1, a ribbon of Co-based amorphous material (ACO-4 manufactured by Hitachi Metals, Ltd.) (thickness 15 μm, width 1)
5 mm) using an outer diameter of 2.2 mm, an inner diameter of 1.5 mm,
A wound core having a length of 15 mm was prepared and heat-treated at 450 ° C. for 1 hour in a nitrogen atmosphere. When the characteristics of this pipe-shaped magnetic core were measured, μe = 40000 and the AL value was 45.4 μm.
H / N ＾ 2. An 80 μm thick parylene coating was applied to the magnetic core, and six parallel wires were wound by eight turns using a 0.06φ wire to form a primary 16 turn and a secondary 32 turn pulse transformer. 20 kHz of this embodiment
Measured the inductance at 23.2 m
H and a sufficient inductance were 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 12 into which the pipe-shaped magnetic core 1 (shown by a broken line in the figure) is inserted.
A plurality of wiring terminals 13 are provided on the side surface parallel to the axis of the through hole 12 so as to protrude from the recess 15.
A wiring groove 14 for passing a lead wire is formed between the portion where the through hole 12 is provided and the portion where the wiring terminal is provided. The through-hole 12 is formed in a shape in which two pipe-shaped magnetic cores 1 can be inserted adjacent to each other, and two such holes 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 this embodiment, the winding state and the case are described separately for the sake of explanation. In this embodiment, the pipe-shaped core 1 is inserted into the case 11, and then the winding is performed. The above-mentioned pulse transformer is configured by connecting the lead wires of the wires to the wiring terminals 13 of the case 11. In addition, the parallel connection of the parallel wires was performed using the wiring terminals 13 to form a winding having a predetermined number of turns. 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 1
2.8 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, 2
3 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 1 shows the height, inductance and number of coil turns of the comparative example.
Shown in

[0011]

[Table 1]

From Table 1, 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] The present invention is characterized in that two pipe-shaped magnetic cores made of a material having μe = 30000 or more are arranged in parallel, and winding is performed through two through holes centering on opposing side surfaces. Pulse transformer for ISDN. 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.