JP4676974B2 - Method for adjusting mutual inductance and transformer adjusted by the method - Google Patents

Description

  The present invention relates to a method for adjusting mutual inductance, and more particularly, to a method for increasing or decreasing mutual inductance between adjacent windings wound around a main core of a transformer.

  In many liquid crystal display devices, a cold cathode fluorescent lamp (CCFL) is used as a main light source. The cold cathode fluorescent tube is driven at a high voltage, and an inverter circuit is used for lighting. Conventionally, a lighting circuit for lighting one discharge tube by one inverter transformer is used as a boosting element. A large number of discharge tubes are used for large surface light sources such as liquid crystal displays. Conventionally, when lighting them, the number of transformers and driving circuits that turn on one discharge tube for each step-up transformer is increased. Since it was used in proportion, the inverter circuit was complicated. In recent years, backlights for liquid crystal displays have further increased in size, and as a result, more discharge tubes have been used for one backlight. In recent years, however, the number of step-up transformers for inverter circuits for surface light sources has been reduced. Therefore, there has been a demand for a step-up transformer that is compact and capable of outputting a large amount of power.

  FIG. 13 is a perspective view showing an example of a conventional step-up transformer for lighting multiple lamps. The transformer 300 is configured by combining two E-shaped cores 31, 31 and an I-shaped core 32. The I-shaped core 32 is inserted into the hollow hole of the bobbin 30 around which the primary winding 301 and the secondary winding 302 are wound, and the E-shaped cores 31 and 31 are opposed to both ends of the bobbin 30 in the axial direction. Attached. FIG. 14 is a circuit diagram using this step-up transformer. A discharge tube is connected to one end of each of the secondary windings 302 and 302 and the other end is grounded. When a voltage is applied to the primary winding 301, a magnetic flux is generated, and the secondary windings 302 and 302 are connected to each other. A high voltage is generated to light the discharge tube. When the coupling coefficient K between the primary winding 301 and the secondary winding 302 is high, FIG. 14 is represented by the equivalent circuit of FIG. FIG. 16 is a circuit diagram for explaining how the current flows in the discharge tube in the circuit of FIG. As shown, the output current I is the sum of load currents I1 and I2 that are shunted to the discharge tube. Due to the presence of the negative resistance characteristics of the discharge tube, a large amount of current flows through one of the secondary windings coupled with the mutual inductance, and when the discharge tube current on that side increases, the voltage of the discharge tube decreases and the mutual inductance Since the voltage is lowered to the voltage of the other discharge tube coupled, the secondary winding 302 coupled by mutual inductance and the tube current flowing through the individual discharge tubes of the secondary winding 302 are unbalanced. For this reason, the currents of the plurality of discharge tubes become non-uniform, and the plurality of discharge tubes may not be lit evenly.

  FIG. 17 is a cross-sectional view showing an example of another conventional transformer. In this transformer 400, two U-shaped cores 41 and 41 are inserted into the hollow holes of the bobbin 40 in which a primary winding 401 and a secondary winding 402, which are connected in parallel in the vertical direction, are wound, and the respective legs are inserted. Thus, it is configured to be magnetically coupled. FIG. 18 is a circuit diagram using this step-up transformer. When a discharge tube is connected to both ends of each of the secondary windings 402 and 402 and a voltage is applied to the primary winding 401, a magnetic flux is generated, and a high voltage is generated in the secondary windings 402 and 402 to light the discharge tube. Let At this time, when the coupling coefficient K between the primary winding 401 and the secondary winding 402 is high, FIG. 18 is also represented by the equivalent circuits of FIGS. 19 to 20. FIG. 20 is a circuit diagram for explaining how the current flows in the discharge tube in the circuit of FIG. The transformer 400 has substantially the same action as that in which the discharge tube is connected in parallel to one winding, and when the current of one discharge tube increases as in the conventional example, the other discharge tube As a result, the current of the discharge tubes is unbalanced, and the currents of the individual discharge tubes become unbalanced. As a result, the currents of the plurality of discharge tubes become non-uniform, and the discharge tubes cannot be evenly lit.

  According to the above prior art, when the coupling coefficient K between the plurality of secondary windings is high, the output of the secondary windings is equivalent to or close to the parallel connection, and the currents flowing through the secondary windings are mutually connected. Seesaw phenomenon that changes so as not to be equal, and does not become equal. On the other hand, if the coupling coefficient K is lowered with this structure, the coupling coefficient between the primary winding and the secondary winding also decreases, and the leakage inductance of the secondary winding increases, so the power factor seen from the primary winding side. Can not be raised. This means that the copper loss of the primary winding is increased to reduce the conversion efficiency of the transformer, and the power that can be output from the transformer cannot be increased.

FIG. 21 is a perspective view showing an example of another conventional transformer. The transformer 500 uses a core in which the center core 51 and the side cores 52 and 52 are independently combined. The primary winding 501 is wound around the center core 51, and the secondary winding 502 and the secondary winding 502 are wound. The secondary windings 502 and 502 are wound around the side cores 52 and 52 so that the phase difference between the output voltages of the first and second output voltages becomes 180 degrees. The coupling coefficient of the transformer 500 is not very good, and when a resonance circuit is incorporated on the output side of the secondary windings 502 and 502, if the resonance frequency of the resonance circuit shifts, the secondary winding 502 , 502 has a problem that currents flowing through 502 are not equal. Further, each of the secondary windings 502 and 502 receives the magnetic flux generated by the primary winding 501, but each of the secondary windings 502 and 502 has a large number of turns and the self-resonant frequency becomes the drive frequency of the inverter circuit. Since the secondary winding forms a distributed constant delay circuit, the traveling waves P ₁ and P ₂ running in opposite directions collide with each other and the induced magnetic flux is canceled out. There is also a problem that it cannot be done. In order to avoid the above problem, the self-resonant frequency of the secondary winding 502 must be increased so as not to be affected by the relatively reflected magnetic flux of the secondary windings 502 and 502. In order to increase the self-resonant frequency of the secondary winding 502, it is necessary to increase the number of divisions of the section winding, thereby causing a problem of decreasing the coupling coefficient.

  FIG. 22 is a perspective view showing an example of another conventional transformer. This transformer 600 includes two U-shaped cores 61, 61 extending from two abdominal ends disposed on both sides and an I-shaped core 62 disposed in the center, and the U-shaped core 61, Each of the two legs of 61 is inserted into the corresponding bobbin, and the primary windings 601 and 601 are wound around the two opposite bobbins, and the secondary windings 602 and 602 are wound around the other two bobbins. Is wound. According to the configuration of the transformer 600, it is possible to prevent the problem that the two secondary windings 602 and 602 are closed, and the secondary windings of the above form are coupled to each other. The cross-sectional area of the core 62 and the cross-sectional area of the abdominal part of the U-shaped cores 61 and 61 are substantially the same, and the cross-sectional area of the core 62 is actually a U-shaped core, although not shown in detail in this figure. In this configuration, the core cross-sectional area cannot be adjusted to increase the coupling coefficient K, and the leakage inductance cannot be reduced to increase the output. The negative effects of traveling wave collisions cannot be excluded.

  FIG. 23 is a plan view showing an example of another conventional transformer. The transformer 700 is formed in a closed shape by a U-shaped core 71 and an I-shaped core 72, and a primary winding and a secondary winding are adjacent to each other on a bobbin 70 into which the I-shaped core 72 is inserted, and Since they are juxtaposed in close proximity, the secondary winding is configured by winding a primary winding 701 and a secondary winding 702 that are in a tightly coupled / loosely coupled configuration with respect to the primary winding. The magnitude of the traveling wave on one end side (tightly coupled end) close to the primary winding 701 of the secondary winding 702 is on the other end side (loosely coupled end) far from the primary winding 701 of the secondary winding 702. Since the magnitude of the traveling wave is larger than that of the traveling wave and is not easily affected by the collision of the traveling wave, the number of turns of the secondary winding 702 can be adjusted to obtain a desirable coupled state. In this transformer 700, the Q value of the resonance circuit on the secondary winding 702 side is increased, and resonance occurs between the parasitic capacitance and the auxiliary capacitance between the secondary winding 702 and the discharge tube (not shown). By doing so, the exciting current on the primary winding side can be reduced, and as a result, the number of turns of the primary winding 701 can be reduced and the copper loss can be reduced. Therefore, an inverter circuit that can be miniaturized and has high efficiency can be configured. However, in the structure of this conventional example, the distance between the primary winding and the secondary winding is physically separated. Therefore, on the secondary winding, a portion that is tightly coupled to the primary winding and a loose coupling are provided. It was difficult to form a part.

Also, when a large number of discharge tubes are lit, such as a liquid crystal television surface light source, if the Q value of the secondary winding side resonance circuit is increased unnecessarily, the resonance frequency on the secondary winding side of each step-up transformer is small. This may cause a problem that the tube currents of the discharge tubes are not equal. Therefore, the Q value of the secondary side resonance circuit must be lowered and compromised in a state where the power factor is poor, and the efficiency must be deteriorated to cope with it. Therefore, many current step-up transformers are set to low Q values, at the expense of efficiency.
JP-A-2005-223125

  The present invention is intended to solve the above problems, effectively adjust the mutual inductance between adjacent windings, uniformize and stabilize the current flowing through the induction winding, and An object of the present invention is to provide a mutual inductance adjusting method capable of increasing the output and increasing the conversion efficiency.

  In order to achieve the above object, the present invention is a method used in a transformer having a plurality of primary windings and a plurality of windings, wherein (A) the primary windings and the secondary windings are provided on a main core. Winding the wires adjacent to each other; (B) preparing a sub-core having a smaller cross-sectional area than the main core; and (C) winding the sub-core adjacent to the main core. Between the primary windings and the secondary windings, and (D) between the primary windings wound next to each other and between the secondary windings. The relative position between the sub-core and the main core is adjusted so that only the main magnetic flux constituting the generated mutual inductance is split and the self-resonant frequencies of the plurality of secondary windings do not become too low. And the primary windings And reducing the mutual inductance between the secondary windings, the primary windings wound next to the main core, and the mutual inductance between the secondary windings. Provide a way to adjust.

  In the step (B), it is further preferable to prepare the sub-core in which the cross-sectional area of the sub-core is equal to or less than the effective cross-sectional area of the main core.

  In the step (A), it is further preferable that the winding is performed so that the cross-sectional area of the main core at a portion away from the sub-core is equal to or larger than the effective cross-sectional area of the main core.

  In the step (A), the primary windings wound next to each other are preferably connected in series via an external circuit, for example.

  In the step (A), a plurality of primary windings are wound in an adjacent relationship as adjacent windings on one side of the main core, and a plurality of secondary windings are wound on the other side. In the step (C), the sub-core can be provided across the main core so as to be disposed between the plurality of primary windings.

  In the step (A), a plurality of the primary windings are wound in an adjacent relationship on one side of the main core, and a plurality of the secondary windings are wound in an adjacent relationship on the other side. In the step (C), the sub-core may be provided across the main core so as to be disposed between the secondary windings.

  In the step (D), adjusting a relative position between the main core and the sub-core is performed so as to adjust a contact area between the main core and the sub-core.

  In the step (D), the relative position between the main core and the sub core may be adjusted so as to adjust the gap between the main core and the sub core.

  Further, in the step (D), adjusting a relative position between the main core and the sub core may be performed by setting a gap between the sub core and the main core when the sub core is on the main core. It can also be done to adjust.

  Further, in the step (B), the sub-core is prepared so that two sub-cores are arranged in a straight line with a gap, and in the step (D), the relative positions of the main core and the sub-core are determined. Adjusting can also be done to adjust the gap between the two sub-cores.

  According to another aspect, the present invention can provide a step-up transformer adjusted by any one of the above methods.

  According to the method of the present invention, by using the main core and the sub-core having a cross-sectional area smaller than the cross-sectional area of the main core, the primary inductance among the mutual inductances generated between the plurality of windings wound around the main core. Maintains the main magnetic flux that passes through the winding and secondary winding, reduces the main magnetic flux that passes between primary windings or between secondary windings, and the self-resonant frequency of the secondary winding becomes too low By adjusting the relative position between the sub-core and the main core so as to reduce the mutual inductance between adjacent windings wound around the main core, the secondary winding The self-inductance can be adjusted so that the self-inductance does not become too large, that is, the self-resonance frequency does not become too low.

  Also, by adjusting the mutual inductance between multiple windings, shortening one effective magnetic path and lengthening the other, reducing the excitation current on the primary winding side and making the other effective magnetic path longer, A configuration with loose and tight coupling can be obtained. Further, by connecting the primary windings in series, the current flowing through the plurality of windings can be made uniform and stabilized.

  Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, about the component which has the same structure and function, the same number is attached | subjected and the description is abbreviate | omitted.

  FIG. 1 is a plan view showing a transformer of a first example using the method according to the first embodiment of the present invention. FIG. 2 is a front sectional view of FIG.

  In addition, although this invention is mainly invention regarding a method, when mass production is performed about the transformer adjusted using this method, it may be replaced with the thing which fixed the adjustment method from the convenience of cost and mass production. .

  First, the transformer 100 includes a main core 11 in which two U-shaped cores 110 and 110 each having two legs extended at right angles from both ends in the X direction of the abdomen are combined in a closed-circular shape. Yes. The two leg portions of each of the two U-shaped cores 110, 110 are cut out from one side to be thin, and each one leg portion is wound with, for example, primary windings 111, 111 as a plurality of windings 10. The other leg portions of the bobbins 13 and 13 are inserted into the hollow holes of the bobbins 14 and 14 around which the secondary windings 112 and 112 are wound. The two U-shaped cores 110 and 110 are provided to face each other so that the primary windings 111 and 111 and the secondary windings 112 and 112 wound around the two U-shaped cores 110 are connected in series. The rod-shaped sub-core 12 is disposed across the two leg portions of the two U-shaped cores 110, and the mouth-shaped main core 11 and the rod-shaped sub-core 12 are combined in a substantially “day” shape. The sub-core 12 is formed so that the cross-sectional area 121 is smaller than the cross-sectional area of the main core 11. Here, the axis of the sub-core 12 is the X direction.

  In the transformer 100, the cross-sectional area 121 of the sub-core 12 is preferably less than or equal to the effective cross-sectional area 113 of the main core 11, for example, less than or equal to one half of the effective cross-sectional area 113 of the main core 11. Further, it is preferable that the cross-sectional area 114 of the main core separated from the sub-core 12 is equal to or larger than the effective cross-sectional area 113 of the main core 11.

  As described above, the sub-core 12 is disposed close to the main core 11 and between the secondary windings 112 and 112 of the main core 11. In this example, the sub-core 12 is disposed so as to contact the main core 11 at a position where the legs of the U-shaped cores 110 and 110 face each other. Next, the sub-core 12 is moved with respect to the main core 11 along the X direction to separate the magnetic flux due to the mutual inductance of the secondary windings 112 and 112, and the main magnetic flux between the adjacent windings 10 and 10 is reduced. The relative position between the main core 11 and the sub-core 12 is adjusted so as to be sufficiently divided. However, if a completely closed magnetic circuit is constructed, the self-inductance of the secondary winding increases too much and the self-resonance frequency decreases, so in this case, the sub-core is placed in the main core so that the self-resonance frequency is increased to some extent. Move away from.

  In this way, the facing area 122 between the main core 11 and the sub-core 12 is changed so that the mutual inductance between adjacent windings is reduced as much as possible.

  Next, the sub-core 12 is fixed on the main core 11 with an adhesive or the like.

It can be estimated by Equation 1 how much the shape of the sub-core 12 disposed between the adjacent windings 10 and 10 can sufficiently reduce the mutual inductance between the adjacent windings. As a result, it can be seen that it may be considerably thin.
Magnetic circuit length = physical distance of magnetic flux / cross-sectional area of core (Equation 1)
By increasing the length (magnetic path length) of one effective magnetic circuit of adjacent windings 10 and 10 and shortening the other magnetic path length, the magnetic circuit of the transformer 100 is loosely coupled and tightly coupled. A configuration can also be provided.

  In the present invention, since the cross-sectional area 114 of the main core 11 away from the sub-core 12 is equal to or larger than the effective cross-sectional area 113 of the main core 11, the secondary windings 112, 112 near the primary windings 111, 111 are dense. The secondary windings 112 and 112 near the sub-core 12 are loosely coupled. As a result, a traveling wave entering from a distant portion, that is, a loosely coupled portion when viewed as a magnetic path is reduced, and a standing wave can be prevented from being formed. In addition, the fact that the coupling coefficient can be increased means that the excitation current as seen from the primary winding side is reduced when resonating between the leakage inductance on the secondary side and the parasitic capacitance of the discharge tube (not shown). As a result, the heat generation of the transformer can be reduced.

  3 and 4 are a perspective view and a front sectional view showing a transformer of a second example using the method according to the first embodiment of the present invention. The configuration of this transformer is almost the same as the configuration of the first embodiment, but the sub-core 12 is not brought into contact with the main core 11 and a gap 123 is formed in parallel with the abdominal portions of the U-shaped cores 110 and 110. The windings 10, 10 adjacent to each other are configured to extend over the two leg portions of the main core 11, and are the primary windings 111, 111. According to this configuration, it is possible to adjust the mutual inductance between adjacent windings as in the above example.

  5 and 6 are perspective views showing a transformer of a third example using the method according to the first embodiment of the present invention. The configuration of this transformer is almost the same as the configuration of the above embodiment, but the sub-core 12 is moved in the X direction with a gap 123 without contacting the main core 11, and the sub-core 12 is positioned on the main core 11. The opposing area 124 is adjusted and provided so as to straddle the two legs of the main core 11 in parallel with the abdominal parts of the U-shaped cores 110 and 110. By moving the sub-core 12 back and forth in the X direction to change the gap 123 between the sub-core 12 and the main core 11, that is, by changing the facing area 124 of the sub-core 12 to the main core 11, mutual inductance between adjacent windings can be reduced. It can be adjusted to reduce as much as possible. Accordingly, as in the previous embodiment, a loosely and tightly coupled configuration can be provided, so that the discharge tube (not shown) is changed by changing the gap 123 and the facing area 124 so as to eliminate the influence of the mutual inductance of the secondary winding. The current flowing in the circuit can be stabilized equally.

  The adjacent windings 10 and 10 are connected in series via the external circuit 20, for example. This connection has the effect of balancing the output voltages of the two secondary windings to be equal, which contributes to stabilizing the output current equally. The plurality of windings 10 and 10 may be directly connected within the bobbin of the transformer without passing through an external circuit.

  FIG. 7 is a plan view showing a transformer of a fourth example using the method according to the first embodiment of the present invention. In this transformer, two rod-like sub-cores 12a and 12b are arranged in a straight line with a gap D in plan view, and arranged across a closed main core 11 formed into a rectangle by two U-shaped cores. Is substantially the same as the configuration of the above embodiment. This transformer can be adjusted to reduce the mutual inductance between adjacent windings as much as possible by adjusting the gap D between the two sub-cores 12a and 12b. Therefore, the same effect as in the above embodiment can be obtained.

  FIG. 8 is a plan view showing a transformer of a fifth example using the method according to the first embodiment of the present invention. In this transformer, the rod-shaped sub-core 12 is disposed across a closed main core 11 formed in a rectangular shape by two U-shaped cores in plan view. A primary winding 111 and a secondary winding 112 are wound around both sides of the main core 11 with the rod-shaped sub-core 12 as an axis. Here, the primary windings 111 and 111 are formed by winding one coil. The secondary winding 112 is adjacent to the winding 10. Since this transformer can be provided with a loose coupling and a tight coupling by moving the sub-core 12 relative to the main core 11 and adjusting the position thereof, it is possible to achieve a high efficiency similarly to the transformer of the above embodiment. It is high power and can stabilize the current equally.

  FIG. 9 is a plan view showing a transformer of a sixth example using the method according to the first embodiment of the present invention. This transformer has a rectangular main core 11 formed by combining a U-shaped core and a rod-shaped core, and the secondary windings 112 and 112 are wound next to each other on both sides around the sub-core 12 so as to be close to the sub-core 12. It is formed by winding the primary windings 111 and 111 by one coil apart from the coil. This transformer can be provided after adjusting the position by moving the sub-core 12 provided over the main core 11 along the X direction with respect to the main core 11, and can be configured to have loose coupling and tight coupling. Therefore, like the transformer of the above embodiment, it is possible to achieve high efficiency and high power and to stabilize the current equally.

  FIG. 10 is a plan view showing a transformer of a seventh example using the method according to the first embodiment of the present invention. Unlike the example of FIG. 8, the transformer is configured such that the primary windings 111, 111 are wound adjacent to each other on the both sides of the main core 11 with the sub-core 12 as an axis, adjacent to the sub-core 12, and adjacent to the sub-core 12. The secondary windings 112 and 112 are connected to both ends of the coil and are wound apart from each other. This transformer is provided after adjusting the position by moving the sub-core 12 provided over the main core 11 with respect to the main core 11, thereby extending the magnetic circuit of the adjacent winding 10 and increasing the magnetic resistance. In addition, since it can be a loosely coupled configuration and a configuration having a loosely coupled and a tightly coupled configuration, by adjusting the mutual inductance between the windings, high efficiency and high power can be achieved in the same manner as the transformer of the above embodiment. And the current can be stabilized equally.

  The present invention can provide a method according to still another second embodiment.

The method according to the second embodiment is almost the same as the method according to the first embodiment, except that the main core has a loosely coupled end having a large magnetic resistance and a distance from the loosely coupled end. A main core having two tightly coupled ends with low magnetic resistance is prepared. Next, windings are wound next to each other between each of the two tightly coupled ends and the loosely coupled end. Then, the cross-sectional area of the tightly coupled end is changed so that the mutual inductance due to the inductance of the adjacent windings becomes small, and the cross-sectional area of the tightly coupled end is made larger than the effective cross-sectional area of the loosely coupled end. As described above, the mutual inductance between adjacent windings such as the primary winding and the secondary winding can be adjusted.

  The Example using this method is shown concretely.

  FIG. 11 is a cross-sectional view showing a transformer of an example using the method according to the second embodiment of the present invention.

  In this transformer, the core portion of the tightly coupled end and the core portion of the loosely coupled end are combined by different cores so that the mutual inductance of the tightly coupled end is larger than the mutual inductance of the loosely coupled end. That is, as shown in the figure, the flaky sub-cores 12 are provided at the tightly coupled ends 116 on both sides of the main core 11 so that the cross-sectional area 114 of the tightly coupled end 116 is greatly changed. In this way, the magnetic resistance of the tightly coupled end 116 can be reduced and a tightly coupled configuration can be achieved, and the loosely coupled end 115 can be configured in a loosely coupled configuration with respect to the tightly coupled configuration of the tightly coupled end 116. The mutual inductance between the adjacent windings 10 and 10 can be reduced, and a standing wave can be prevented from being formed.

  The cross-sectional area 114 of the tightly coupled end 116 is preferably greater than or equal to the effective cross-sectional area 113 of the loosely coupled end 115. According to experiments, the above-described effect can be obtained if the cross-sectional area 114 of the tightly coupled end 116 is larger than 1.2 times the effective cross-sectional area 113 of the loosely coupled end 115.

  Needless to say, as shown in FIG. 12, the sub-core 12 may be provided so as to be integrally formed with the two tightly coupled ends 116. In short, it is only necessary that the cross-sectional area 114 of the tightly coupled end 116 can be made larger than the effective cross-sectional area 113 of the loosely coupled end 115.

  For example, a core having two tightly coupled ends 116 having a large cross-sectional area is prepared. The cross-sectional area 114 of the tightly coupled end 116 is equal to or larger than the effective cross-sectional area 113 of the loosely coupled end 115, and the tightly coupled end is ground and cut so that the mutual inductance between the adjacent windings 10 and 10 is reduced. The area 114 can also be adjusted.

  As described above, the sub-core 12 is moved in the X direction with respect to the main core 11, or the cross-sectional area 114 of the tightly coupled end 116 of the main core 11 is changed, so that the mutual inductance due to adjacent windings is made as relatively as possible. A reduced configuration can be achieved. Therefore, the current flowing through the discharge tube can be stabilized equally.

  The method for adjusting mutual inductance according to the present invention can reduce the mutual inductance of adjacent windings as much as possible, has the effect of stabilizing the current flowing in the discharge tube equally, and is useful in various electrical devices. is there.

It is a top view which shows the transformer of the 1st Example using the 1st method of the present invention. It is sectional drawing of FIG. It is a perspective view of the transformer of the 2nd example. FIG. 4 is a cross-sectional view of FIG. 3. It is a perspective view of the transformer of the 3rd example. FIG. 6 is a perspective view of the transformer of FIG. 5. It is a top view which shows the trans | transformer of a 4th Example. It is a top view showing the transformer of the 5th example. It is a top view showing the transformer of the 6th example. It is a top view which shows the trans | transformer of a 7th Example. It is sectional drawing which shows the trans | transformer of the Example using the 2nd method of this invention. It is sectional drawing which shows the trans | transformer of another Example using the 2nd method of this invention. It is a disassembled perspective view which shows an example of the conventional transformer. FIG. 14 is a circuit diagram using the step-up transformer of FIG. 13. It is the equivalent circuit of FIG. FIG. 16 is a circuit diagram illustrating how a current flows in the discharge tube in the circuit of FIG. 15. It is sectional drawing which shows an example of the other conventional transformer. FIG. 18 is a circuit diagram using the step-up transformer of FIG. 17. It is the equivalent circuit of FIG. FIG. 20 is a circuit diagram illustrating how current flows in the discharge tube in the circuit of FIG. 19. It is a perspective view which shows an example of the other conventional transformer. It is a perspective view which shows an example of the other conventional transformer. It is a top view which shows an example of the other conventional transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Transformer 11, 110 ... Main core 111 ... Primary winding 112 ... Secondary winding 113, 114, 121, 122, 124 ... Area 115 ... Loose coupling end 116 ... Tight coupling end 12 ... Sub core 123 ... Gap 13, 14 ... bobbin

Claims (12)

A method used for a transformer having a plurality of primary windings and a plurality of secondary windings,
(A) winding the primary windings around the main core and the secondary windings next to each other;
(B) providing a sub-core having a cross-sectional area smaller than that of the main core;
(C) arranging the sub-core between the primary windings wound adjacent to and adjacent to the main core, and between the secondary windings;
(D) splitting only the main magnetic flux constituting the mutual inductance generated between the primary windings wound next to each other and between the secondary windings, and a plurality of the secondary windings Adjusting the relative position between the sub-core and the main core so that the self-resonant frequency does not become too low, thereby reducing mutual inductance between the primary windings and between the secondary windings. Including,
A method of adjusting a mutual inductance between the primary windings wound next to each other on the main core and between the secondary windings.   2. The method according to claim 1, wherein in the step (B), the sub-core having a cross-sectional area of the sub-core that is equal to or smaller than an effective cross-sectional area of the main core is further prepared.   2. The method according to claim 1, wherein in the step (A), the winding is performed so that a cross-sectional area of the main core in a portion away from the sub-core is equal to or larger than an effective cross-sectional area of the main core.   The method according to claim 1, wherein in the step (A), the primary windings wound side by side are connected in series with each other.   The method according to claim 1, wherein in the step (A), the primary windings wound side by side are connected in series via an external circuit. In the step (A), the primary winding is wound as an adjacent winding on one side of the main core in an adjacent relationship, and the secondary winding is wound as an adjacent winding on the other side. Wound in a side-by-side relationship
The method according to claim 1, wherein in the step (C), the sub-core is provided across the main core so as to be disposed between the plurality of primary windings. In the step (A), a plurality of the primary windings are wound in an adjacent relationship on one side of the main core, and a plurality of the secondary windings are wound in an adjacent relationship on the other side,
The method according to claim 1, wherein in the step (C), the sub-core is provided across the main core so as to be disposed between the secondary windings.   The step (D) is characterized in that adjusting the relative position between the main core and the sub-core is performed so as to adjust a contact area between the main core and the sub-core. The method described in 1.   The step (D) is characterized in that the relative position between the main core and the sub-core is adjusted so as to adjust a gap between the main core and the sub-core. The method according to 1.   In the step (D), adjusting a relative position between the main core and the sub core adjusts a gap between the sub core and the main core when the sub core is on the main core. The method of claim 1, wherein the method is performed as follows. In the step (B), the sub-core is prepared so that the two sub-cores are arranged in a straight line with a gap between them,
2. The step (D) according to claim 1, wherein adjusting a relative position between the main core and the sub-core is performed so as to adjust a gap between the two sub-cores. the method of. Step-up transformer comprising been adjusted by the method according to any one of claims 1 to 11.

Images