JPH06224053A - Printed coil type transformer - Google Patents

Abstract

PURPOSE:To provide a printed coil type transformer of a structure, wherein the primary side printed coil-secondary side printed coil common mode noise current of the transformer is little and an equivalent normal capacity is small. CONSTITUTION:A printed coil type transformer has a primary side printed coil 10 formed with foil-shaped conductor patterns, which are spirally formed and to which a pulsed current or an alternate current is applied, and a secondary side printed coil 20 formed with spiral foil-shaped conductor patterns, which are magnetically coupled with the conductor patterns of this coil 10. In the arrangement of conductor pattern surfaces S1 to S16 of the coil 10 and conductor pattern surfaces S21 to S26 of the coil 20, the absolute quantity of a change in a voltage, which is generated in order by an applying current from the opposed surfaces S11 and S21 of the coils 10 and 20 to the directions of the outer frame surfaces S16 and S26 of the coils 10 and 20 is increased in the conductor pattern surfaces S12 to S15 and S22 to S25, which are respectively positioned between the opposed surfaces and between the outer frame surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer used in electronic equipment and power supplies, and more particularly to improvement of noise reduction in a high frequency band.

[0002]

2. Description of the Related Art A printed coil transformer uses a copper foil having a thickness of about 30 to 70 .mu.m as a conductor, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-73911 proposed by the present applicant. In such a printed coil, since the copper foil is generally formed into a spiral conductor pattern by etching, the conductor cross section is flat. Therefore,
When the printed coils are laminated, the stray capacitance of the conductor patterns facing each other has a property of becoming larger than that of the wire winding transformer having the same cross-sectional area.

[0003]

By the way, the stray capacitance formed in the portion where the primary pattern and the secondary pattern are close to each other is a high frequency due to the stray capacitance when the transformer is incorporated into an operating circuit. There is a problem that common mode noise increases due to the flow of current. Further, since the high-frequency current flowing due to the stray capacitance formed between the primary patterns and between the secondary patterns becomes the normal capacitance of this transformer, it is desirable that the normal capacitance is small when driving the transformer. Further, widening the interval between the primary pattern and the secondary pattern is effective for reducing the stray capacitance, but there is a problem that the magnetic coupling state between the primary and secondary deteriorates and the leakage inductance increases. .

The present invention has solved the above-mentioned problems and is a printed coil type in which the magnetic coupling state between the primary and secondary sides of a transformer is kept good, the high frequency current flowing through the stray capacitance is small, and the normal capacitance is small. Intended to provide a transformer.

[0005]

According to the present invention which achieves such an object, a primary side printed coil in which a foil-shaped conductor pattern is formed in a spiral shape and a pulsating current or an alternating current is applied to this conductor pattern ( 10) and a secondary side print coil (20) on which a spiral foil-like conductor pattern magnetically coupled to the conductor pattern of the primary side print coil is formed, and each print coil has a conductor of two or more layers. A printed coil type transformer in which patterns are laminated has the following configuration.

That is, the conductor pattern surfaces (S _{11 to} S ₁₆ ) of the primary side print coil and the conductor pattern surfaces (S _{21 to} S ₂₆ ) of the secondary side print coil are arranged so as to face each other. Is the conductor pattern surface (S ₁₁ , S ₂₁ ) having the smallest absolute amount of voltage change caused by the applied current, and the conductor pattern surface (S ₁₆ , S ₂₆ ) located at the outermost position from the facing surface of both print coils is It is assumed that the absolute amount of the voltage change caused by the applied current is the largest, and the opposing surface is the conductor pattern surface (S _{12 to} S ₁₅ , S _{22 to} S ₂₅ ) located between the opposing surface and the outer surface of each print coil. Is characterized in that the absolute amount of voltage change caused by the applied current is sequentially increased in the direction from the outer surface to the outer surface.

[0007]

[Function] The voltage difference between the conductor pattern surfaces of the primary-side printed coil and the secondary-side printed coil facing each other is reduced, and the high-frequency current resulting from the stray capacitance of both is reduced.
Common mode noise is reduced. Further, by substantially reducing the potential difference between the conductor pattern surfaces adjacent to each other inside each print coil, the equivalent normal mode noise is reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram showing an embodiment of the present invention. In the figure,
The primary side printed coil 10 has a conductor pattern surface S ₁₁ of 6 layers.
Those consisting to S _16, the primary side common 145 is connected to the primary side ground GND1, pulsed current source E is connected to the primary-side current terminal 146. The secondary side print coil 20 is composed of six layers of conductor pattern surfaces S _{21 to} S ₂₆ , and the secondary side common 245 is the secondary side ground GND.
2, and a load is connected to the secondary side output terminal 246. The core 30 is an EE type core and forms a magnetic circuit for each conductor pattern surface of the print coil.

FIG. 2 is a development view of the primary side print coil 10, where (A) shows the front surface 10a and (B) shows the back surface 10b. Here, the case where three conductor pattern surfaces S _{11 to} S ₁₆ are provided on both surfaces of the flexible substrate is shown. Secondary-side print coil facing surface S of the primary-side print coil 10
A round hole 131 for the core 30 is formed in the center of the ₁₁ , and a 1.5-turn spiral winding that connects the primary side common 145 and the relay end 115a is formed. The surface 10a of the primary-side printed coil 10, the intermediate surface S _14, S ₁₅ subsequent to the facing surface S ₁₁ is provided. On the intermediate surface S ₁₄ ,
A conductor pattern for connecting the primary-side current terminal 146 and the relay end 112a is formed, and the connection pattern 148 is also formed.
A two-turn spiral winding is formed to connect the relay end 114a and the relay end 114a. The intermediate surface S _15, spiral winding of two turns to contact relay terminal 113a and the connecting pattern 148 is formed. In addition, round holes 132 and 133 for the core 30 are formed at the centers of the respective intermediate surfaces S ₁₄ and S ₁₅ .

Next, the back surface 10 of the primary side print coil 10
In b, an intermediate surface S ₁₂ located opposite to the facing surface S ₁₁ is provided, and an intermediate surface S ₁₃ and an outer surface S ₁₆ are provided adjacent to the intermediate surface S ₁₂ . The intermediate surface S ₁₂ is provided with a relay end 115b connected to the relay end 115a via a through hole, and a two-turn spiral winding connecting the connection pattern 149 is formed. The intermediate surface S ₁₃ is provided with a relay end 112 b that is connected to the relay end 112 a via a through hole and is connected to the connection pattern 147. Further, a relay end 114b connected to the relay end 114a through a through hole is also provided, and is connected to the connection pattern 149 by a spiral winding of 1.5 turns. The outer surface S ₁₆ is provided with a relay end 113b connected to the relay end 113a through a through hole, and a two-turn spiral winding connecting the connection pattern 147 is formed.

Such a printed coil is folded along folding lines 102 and 103 as shown in FIG. 1, and the conductor pattern surfaces are superposed in the order of the facing surface S ₁₁ , the intermediate surfaces S _{12 to} S _{15 and the} outer surface S _16. It is designed to be used. The secondary side print coil 20 also has the same conductor pattern surface S as in FIG.
_{21 to} S ₂₆ are formed, and the number of turns is appropriately adjusted.

The operation of the apparatus thus configured will be described. 3A and 3B are waveform diagrams for explaining the temporal change of the average potential of each conductor pattern surface. FIG. 3A shows the primary side print coil 10 and FIG. 3B shows the secondary side print coil 20. In the drawing, in the primary side print coil 10,
₁₄₅ is the primary side ground GND1 potential, V _S11 is the facing surface S
_{11 is} the average potential, V _{S12 to} V _S15 are the average potentials of the intermediate surfaces S _{12 to} S ₁₅ , and V ₁₄₆ is the potential of the primary side current terminal 146, which is substantially the average potential of the outer surface S ₁₆ . In the primary side print coil 10, the average potential V _S11 of the facing surface S ₁₁ is the smallest absolute amount of voltage change caused by the pulsed current source E. The absolute amount of voltage change caused by the pulsed current source E increases in the order of the average potentials V _{S1 2 to} V _S15 of the intermediate surfaces S _{12 to} S ₁₅ , and V ₁₄₆ representing the potential of the outer surface S _16. Is the largest, and V ₁₄₆ is E + G
It is ND1.

Similarly, in the secondary side print coil 20, V ₂₄₅ is the secondary side ground GND2 potential, V _S21 is the average potential of the facing surface S ₂₁ , and V _{S22 to} V _S25 are the intermediate surfaces S _{22 to} S _25.
, The average potential of V ₂₄₆ is the potential of the secondary output terminal 246,
Substantially the average potential of the outer surface S ₂₆ is represented. In the secondary side print coil 20, the average potential V _S21 of the facing surface S ₂₁ is
It has the smallest absolute amount of voltage change caused by the pulsed current source E sent through the transformer. The absolute amount of voltage change caused by the pulsed current source E increases in the order of the average potentials V _{S22 to} V _S25 of the intermediate surfaces S _{22 to} S ₂₅ , and V ₂₄₆ representing the potential of the outer surface S ₂₆ is It has become the largest, V ₂₄₆ is in the E + GND2.

In this way, the facing surface S ₁₁ and the facing surface S
_{At 21} , since the average potential is the same during circuit operation,
Even if there is stray capacitance between the primary and secondary sides, high frequency current does not flow and common mode noise is reduced. In addition, the potential difference between the adjacent conductor patterns inside the primary side print coil 10 is small, and even if there is stray capacitance between the primary windings, a small amount of high frequency current flows. Similarly, in the secondary-side printed coil 20, the potential difference between the conductor patterns adjacent to each other inside is also small, and even if there is stray capacitance between the primary windings, a small amount of high-frequency current flows.

FIG. 4 is a block diagram of a comparative example. The secondary side print coil 20 has the same folding method as in FIG.
The primary side print coil 10 is the reverse of FIG.
Therefore, in this example, since the intermediate surface S ₁₅ and the facing surface S ₂₁ face each other, the potential difference between them becomes larger than that in the case of FIG. 1, and the high frequency current flows due to the stray capacitance between the primary and secondary sides.
Common mode noise increases. Further, the potential difference between the adjacent conductor patterns is large even inside the primary side print coil 10. For example, the facing surface S ₁₁ and the intermediate surface S ₁₄ are adjacent to each other, and the outer surface S ₁₆ and the intermediate surface S ₁₃ are adjacent to each other. The high-frequency current flowing due to the stray capacitance existing in the area is large. Therefore, as compared with FIG. 1, the transformer has a large amount of noise, which is not preferable.

FIG. 5 is a block diagram showing another embodiment of the present invention. Here, the number of coils is one on each of the primary side and the secondary side, but a transformer with a center tap is used for both the primary side and the secondary side, and this is used in push-pull. In such a case, the stray capacitance can be reduced by providing a mirror-symmetrical primary print coil 10 'and a secondary print coil 20' with respect to the primary print coil 10 and the secondary print coil 20 in FIG. Even if it exists, it is possible to obtain a transformer with a small high-frequency current flowing through it.

Although an example in which a flexible printed board is bent as a print coil is shown here, the present invention is not limited to this, and a rigid printed board,
A multilayer board, a double-sided board, or a single-sided board may be used. A jumper wire may be used to connect the conductor pattern surfaces, and in short, the stacking order may be sequentially arranged based on the absolute amount of voltage change caused by the pulsed current source E.

[0018]

As described above, according to the present invention, the conductor pattern surface is selected so that the potential difference between the opposing surfaces of the primary side and secondary side print coils is substantially reduced. It requires less noise. In addition, since the order of the conductor patterns to be laminated is sequentially arranged inside each print coil on the basis of the absolute amount of the voltage change caused by the applied current source E, the normal capacitance is equivalently reduced and the normal mode noise is reduced. There is an effect. Therefore, the magnetic coupling state between the primary side and secondary side print coils can be kept high, and the performance as a transformer is also improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a development view of a primary side print coil 10.

FIG. 3 is a waveform diagram illustrating a temporal change in average potential of each conductor pattern surface.

FIG. 4 is a configuration diagram showing a comparative example.

FIG. 5 is a configuration diagram showing another embodiment of the present invention.

[Explanation of symbols]

 10 primary side printed coil 20 secondary side printed coil 30 core

Claims (1)

[Claims] 1. A primary side printed coil (10) in which a foil-shaped conductor pattern is formed in a spiral shape and a pulsed current or an alternating current is applied to this conductor pattern, and magnetic coupling with the conductor pattern of this primary side printed coil. And a secondary-side printed coil (20) having a spiral foil-shaped conductor pattern formed thereon, each of which is provided with two or more layers of conductive patterns. Each conductor pattern surface (S ₁₁ ~
S ₁₆ ) and each conductor pattern surface (S
₂₁ to S ₂₆ the arrangement of) the absolute amount of the smallest conductor pattern surface of the voltage change caused by the applied current in the opposing surfaces of both printed coil (S _11, S _21), the most from the facing surfaces of both printed coil In the conductor pattern surfaces (S ₁₆ , S ₂₆ ) located on the outer surface, the absolute amount of voltage change caused by the applied current is the largest, and the conductor pattern surface (between the opposing surface of each print coil and the outer surface) ( S ₁₂
~S _15, S ₂₂ ~S ₂₅₎ The print coil type transformer absolute amount of voltage change caused by sequentially the applied current to the outer surface direction from the opposing surface, characterized in that to increase.