JP3137948U - Trance - Google Patents

Abstract

An object of the present invention is to provide a transformer capable of efficiently adjusting a mutual inductance between windings to obtain an appropriate coupling coefficient k and equally stabilizing a current flowing in the windings.
A main core (11) in which a plurality of windings (10, 10) are wound side by side, and a cross-sectional area thereof is smaller than a cross-sectional area (113) of the main core (11), and adjacent windings. A sub-core (12) disposed between adjacent windings (10, 10) so as to be movable with respect to the main core (11) so as to change a mutual inductance generated between (10, 10). It is configured with.
[Selection] Figure 1

Description

  The present invention relates to a step-up transformer for lighting a discharge tube.

  In the backlights of many liquid crystal display devices, cold cathode fluorescent lamps (CCFLs) and EEFLs are the main light sources.

  Since a high voltage is required for lighting a discharge tube such as a cold cathode fluorescent tube, an inverter circuit is generally used. Conventionally, a single step-up transformer is used for lighting one of these discharge tubes.

  However, many discharge tubes are used for large surface light sources such as displays for liquid crystal televisions, and one step-up transformer and drive circuit are required for each discharge tube for lighting these discharge tubes. Therefore, the inverter circuit has become complicated.

  In recent years, however, backlights for liquid crystal displays have become larger and more discharge tubes have been used. Therefore, the inverter circuit for these surface light sources has been changed to one that turns on a plurality of discharge tubes simultaneously with one transformer.

  FIG. 17 is a sectional view showing an example of a conventional step-up transformer for four lighting. In this transformer 400, a core is used in which two U-shaped cores 41, 41 each having two leg portions extending at right angles from both end portions on the abdomen side are combined in a closed loop shape. One of the opposing leg portions is inserted into the hollow hole of the bobbin 40 around which the primary winding 401 is wound, and the other leg portion is inserted into the hollow hole of the bobbin 40 around which the secondary windings 402 and 402 are wound. Insert into. FIG. 18 is a circuit diagram showing a configuration in which this transformer is connected to a discharge tube. 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 generate a discharge tube. Lights up.

In the example of the transformer 400, when the coupling coefficient K between the two secondary windings 402 and 402 is high, the same effect as that when the cold cathode tubes are connected as in the parallel equivalent circuit of FIG. 19 and FIG. Occurs. As shown in FIG. 20, the output current I is the sum of the load currents I ₁ and I ₂ or I ₃ and I _{4 that} are shunted to the discharge tube, but each discharge tube has a negative impedance characteristic. When one of the tube currents increases, the other current tends to decrease.

  Such a phenomenon occurs because the coupling coefficient between the first secondary winding 402 and the second secondary winding 402 is high, that is, the main magnetic flux is shared.

  Thus, if the main magnetic flux is shared, the tube currents of the individual discharge tubes are unbalanced, and the individual discharge tubes cannot be lit stably at the same time.

  On the other hand, if the coupling coefficient K is lowered in order to solve this problem, the coupling between the primary winding 401 and the two secondary windings 402 and 402 is also lowered, and as a result, the inductive component viewed from the primary winding side is reduced. This increases the power factor viewed from the primary winding side, so that a large amount of reactive current flows through the primary winding, resulting in increased copper loss and heat generation. This lowers the conversion efficiency of the lighting circuit and leads to a reduction in the limit of power that can be supplied.

  Further, if the coupling coefficient between the primary winding and the secondary winding is too high, there arises a problem that the self-resonant frequency of the secondary winding becomes too low. When the self-resonance frequency is lower than the drive frequency of the inverter circuit, the balance of tube current is lost, and sufficient voltage boosting cannot be performed, and further heat is generated.

  An object of the present invention is to provide a transformer capable of efficiently obtaining a condition in which the balance of tube current is optimized by adjusting the mutual inductance between windings. To do.

  In order to achieve the above object, the present invention generates a main core in which a plurality of windings are wound next to each other, and a cross-sectional area thereof is smaller than a cross-sectional area of the main core, and is generated between the adjacent windings. Provided is a transformer comprising a combination of sub-cores arranged between adjacent windings so as to be movable with respect to the main core so as to change mutual inductance.

  Further, by making the cross-sectional area of one end of the main core away from the sub-core larger than the cross-sectional area of the other part of the main core, the primary winding and the secondary winding on the side away from the sub-core The coupling coefficient between them can be kept large.

  In addition, the transformer may be configured so that the sub-core is disposed across the main core so that a bottom surface of the sub-core is in contact with the main core, and the gap between the sub-core and the main core is changed. Are arranged to be movable.

  In the transformer, the sub-core may be covered with a cover having a U-shaped cross section.

  The transformer may be movable about the sub-core as an axis so that the bottom surface of the sub-core changes a gap between the main core without contacting the main core.

  Further, the two sub-cores can be arranged on a straight line with a gap between them so that the gap between the two sub-cores can be adjusted.

  The transformer may further include a frame member having a passage formed therein, and the sub-core may be inserted into the passage so as not to contact the main core.

  The frame member is, for example, a cylindrical case.

  The cylindrical case is divided into two parts, a first case member and a second case member, each of which has a plurality of localization portions that are brought into contact with each other and locked, and the first case member and the first case member are divided into two. The two case members may be arranged so that the central axes thereof coincide with each other so that the sub-core is inserted in communication with each other to form a coaxial passage.

  As another example, the frame member has two vertical end surfaces with the sub-core as an axis, each of the two vertical end surfaces has an axial hole as the passage, and the sub-core has a male screw. It is a rod having a shape and can be inserted into the two shaft holes.

  A guide member that guides the sub-core when the sub-core is moved along the passage in the passage may be formed on the two side walls in the passage of the frame member so as to protrude slightly in contact with the sub-core. .

  One end of the passage is provided with an elastic member that comes into contact with the sub-core and pushes and biases the sub-core, and the other end of the passage comes into contact with the sub-core and resists the urging force. A control member for stopping at a predetermined position can be provided.

  The control member is a screw having a shaft portion arranged perpendicularly to the main core, and a head portion of the screw is a flat head and is in contact with the sub-core, and is irregular. It can also be eccentric with respect to the shape or shaft.

  Further, a vertical gap may be provided between the tip of the sub-core and the main core.

  For example, the elevating member is a pad disposed under the sub-core.

  In another example, the elevating member is a roller having an eccentric shaft.

  As another example, the elevating member may include an elastic member that presses and fixes one end of the sub-core and a clamp with a screw rod that elevates and lowers the other end of the sub-core.

  The transformer includes primary windings wound around two one end portions of the main core located on both sides of one end portion of the sub core, and both sides of the other end portion of the sub core. Secondary windings wound around the two other end portions of the main core located on the main core can be provided as the plurality of windings.

  The transformer includes secondary windings on the two first end sides of the main core located on both sides of one end of the sub-core as a plurality of adjacent windings, and the main You may provide the primary winding wound by the two 2nd edge part side on the opposite side to two said 1st edge parts of a core.

  The transformer includes primary windings on the two first end sides of the main core located on both sides of one end of the sub-core as a plurality of adjacent windings, and the main You may provide the secondary winding wound by the two 2nd edge part side on the opposite side to two said 1st edge parts of a core.

  The primary winding is preferably wound around one conductive wire.

  The cross-sectional area of the sub-core is preferably less than or equal to one half of the effective cross-sectional area of the main core.

  Moreover, it is preferable that the cross-sectional area of the main core near the sub-core is equal to or less than the effective cross-sectional area of the main core.

  According to the method of the present invention, the main core and the sub-core having a cross-sectional area smaller than the cross-sectional area of the main core are used, the mutual inductance generated between the secondary windings is reduced, and the primary and secondary windings are reduced. By adjusting the relative position between the sub-core and the main core so that the self-resonant frequency of the secondary winding does not become too low. Conditions with good balance, moderately low leakage inductance, high output and low heat generation can be easily found.

  In addition, a transformer mass-produced based on the positional relationship established in the adjustment method naturally has a good balance of tube current, high output, low heat generation, and a small size.

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

  FIG. 1 is a cross-sectional view of a transformer according to an embodiment of the present invention. 2 is a partially exploded perspective view of the transformer of FIG.

  In the transformer 100, a main core 11 is used in which two U-shaped cores 110, 110 each having two leg portions extending at right angles from both ends on the abdomen side are combined in a mouth-shaped closed circuit shape. Two leg portions of each of the two U-shaped cores 110, 110 are cut out from one side surface to be thin, and bobbins 115, 115 each having one leg portion wound with, for example, primary windings 111, 111 are wound. Are inserted into the hollow holes of bobbins 116 and 116 in which secondary windings 112 and 112 as a plurality of windings 10 and 10 are wound next to each other. The two U-shaped cores 110, 110 face each other so that the primary windings 111, 111 wound around the two U-shaped cores 110 and the secondary windings 112, 112 are connected in series. The rod-shaped sub-cores 12 are provided so as to straddle the two leg portions of the two U-shaped cores 110 and are combined with the mouth-shaped main core 11 so as to form a substantially “day” shape. Here, the major axis direction of the rod-shaped sub-core 12 is defined as the X direction.

  In the transformer 100 of the present invention, the main core 11 combined in a square shape and the sub-core 12 whose effective cross-sectional area 121 is equal to or less than the effective cross-sectional area 113 of the leg of the U-shaped core 110 are used. In addition, a cross-sectional area means the area of the cross section orthogonal to the axis | shaft of a longitudinal direction.

  In this example, the effective cross-sectional area 121 (cross-sectional area perpendicular to the X direction) of the sub-core 12 is equal to or less than the effective cross-sectional area 113 (cross-sectional area perpendicular to the longitudinal direction of the leg) of the leg portion of the U-shaped core 110. A core having a half or less of the effective cross-sectional area 113 may be used as the sub-core 12. The effective cross-sectional area 113 near the sub-core 12 of the main core 11 is preferably equal to or less than the effective cross-sectional area 114 near the abdomen of the U-shaped core 110.

  Next, the sub-core 12 is disposed between the secondary windings 112 and 112 of the main core 11 in proximity to the main core 11. In this example, the sub-core 12 is covered with a cover-shaped square frame 13 on the portions of the leg portions of the U-shaped cores 110, 110 facing each other, so that a contact area 122 is formed in the square frame 13. In addition, it is movably disposed in contact with the main core 11. The sub core 12 is moved with respect to the main core 11 along the X direction so that the magnetic flux forming the mutual inductance of the secondary windings 112 and 112 is divided, and the magnetic flux of the windings 110 and 110 forms an effective divisional closed circuit. The relative position between the main core 11 and the sub-core 12 is adjusted.

  At this time, if the main core 11 and the sub-core 12 are completely in contact with each other, the self-resonance frequency of the secondary winding may decrease too much. Therefore, the self-resonance frequency of the secondary winding is measured, The position of the sub-core 12 is adjusted so as not to be at least 1.5 times the operating frequency of the inverter circuit.

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

In addition, it adjusts so that the mutual inductance between the adjacent windings 10 may be reduced so that Formula 1 may be satisfy | filled using the subcore 12, and the exciting magnetic flux by the mutual inductance between adjacent windings can be improved.
Magnetic circuit length = physical distance of magnetic flux / cross-sectional area of core (Equation 1)
As described above, the effect of mutual inductance can be reduced by adjusting the facing area of the main core 11 and the sub-core 12 (the area of the overlapping portion) and effectively shortening the magnetic circuit. If the length is made longer, the self-resonant frequency of the secondary winding can be increased. Therefore, by adjusting the facing area between the main core 11 and the sub-core 12, a transformer having an optimal magnetic flux configuration can be obtained. As a result, the currents flowing in the discharge tubes can be equalized and stabilized, and the leakage inductance can be reduced to provide a high output transformer.

  Furthermore, in the present invention, the cross-sectional area 114 of the main core 11 away from the sub-core 12 is set to be equal to or larger than the effective cross-sectional area 113 of the main core 11, so that each primary winding 111, 111 has this cross-sectional area 114. The length of the effective magnetic circuit in the portion of the secondary windings 112 and 112 adjacent to each other is reduced. As a result, the coupling on the side close to the cross-sectional area 114 of the secondary winding becomes a tight coupling relative to the coupling on the other end, that is, the sub-core side, and the secondary windings 112 and 112 near the sub-core 12 are relatively Since the coupling is reduced and becomes loosely coupled, the traveling wave entering the secondary winding from the sub-core side can be reduced and the standing wave can be reduced, resulting in a large output transformer with less heat generation. can do.

  The transformer is configured to form a sparse / tight coupling by bringing the sub-core 12 into contact with the main core 11 while approaching the main core 11. However, the sub-core 12 may not be in contact with the main core 11.

  That is, the sub-core 12 may be configured to be movable so as to change the gap between the main core 11 and the bottom surface of the sub-core 12 without contacting the main core 11. As an example of such a transformer, a cylindrical case member can be provided as a frame member having a passage formed therein, and the sub-core 12 can be inserted into the passage of the cylindrical case member so as not to contact the main core 11. .

  FIG. 3 is a perspective view showing a transformer according to an embodiment of the present invention. This transformer is different from the embodiment of FIGS. 1 and 2 in that the sub-core 12 is not provided in contact with the main core 11, but the sub-core 12 passes through the rectangular tube 33 and is provided with a gap 123 therebetween. It is a point. In this transformer, the sub-core 12 is arranged so as to straddle the two legs of the main core 11 in parallel with the abdomen of each of the U-shaped cores 110 and 110 without placing the gap 123 in contact with the main core 11. ing. Here, a plurality of adjacent windings 10 and 10 are connected in series via an external circuit 20 formed on a printed wiring board. 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, it is possible to adjust so as to reduce the mutual inductance between adjacent windings as much as possible. Accordingly, as in the embodiment of FIGS. 1 and 2, an optimum loose / tight coupling configuration can be easily found, so that a high-output and low-heat-generating transformer can be realized, and adjacent windings can be mutually connected. By changing the gap 123 so as to eliminate the influence of the inductance, the current flowing through the discharge tube can be equally stabilized.

  FIG. 4 is a perspective view showing a transformer according to an embodiment of the present invention. This transformer is different from the above embodiment in that the square tube 33 that penetrates the sub-core 12 so as to form the facing area 124 is further brought closer to the main core 11 and arranged between the adjacent windings 10 and 10. It is a point to do. Similar to the embodiment of FIGS. 3 to 3, a high output and low heat generating transformer can be realized, and the current can be equally stabilized.

  FIG. 5 is a plan view of a transformer according to an embodiment of the present invention. This transformer is different from the above embodiment in that the sub-core 12 is arranged on a straight line with the gap D between the two sub-cores 12a and 12b. By adjusting the gap D between the two sub-cores 12a and 12b, the relative positions of the main core 11 and the sub-core 12 can be adjusted.

  FIG. 6 is an exploded perspective view showing a transformer according to an embodiment of the present invention. FIG. 7 is a perspective view showing a state where the transformer of FIG. 6 is assembled. In this transformer, the cylindrical case 33 includes a first case member 331 and a second case in which a plurality of positioning portions 331a, 332a, 331b, 332b,... The first case member 331 and the second case member 332 that cover the bobbins 31 and 32 are respectively connected to the member 332 so that the sub-core 12 is inserted in communication with each other. Are aligned to form a coaxial passage 334.

  FIG. 8 is a perspective view showing a transformer according to an embodiment of the present invention. In the present embodiment, unlike the above embodiment, the frame member 33 has a groove shape having a predetermined height, and has two vertical end faces 33a and 33b with the sub-core 12 as an axis in the groove. Each of the two vertical end faces 33a and 33b has shaft holes 334a and 334b. The sub-core 12 is a male screw-shaped rod, and is inserted into the two shaft holes 334a and 334b to a predetermined position.

  FIG. 9 is a perspective view showing a transformer according to an embodiment of the present invention. In this embodiment, unlike the above embodiment, the sub-core 12 is moved back and forth along the passage 334 in the passage 334 to the two side walls 334c of the elongated groove-shaped passage 334 of the frame member 33 having a predetermined height. Guide members 161, 161,... That are sometimes guided to a fixed position are formed in a protruding shape and are in contact with the sub-core 12 at the tip.

  FIG. 10 is a perspective view showing a transformer according to an embodiment of the present invention. In the present embodiment, an elastic member 162 is provided on one end side of the groove-shaped passage 334 so as to come into contact with the sub-core 12 and push the sub-core 12 to urge it, and to contact the sub-core 12 on the other end side against the urging force. A control member 163 for stopping the sub-core 12 at different predetermined positions is provided. By doing so, the sub-core 12 can be moved along the X direction.

  In this example, the control member 163 is a screw arranged perpendicularly to the main core 11, is flat with the shaft portion 163 a, is located in contact with the sub-core 12, and has an irregular shape (circular shape). Unlike the shape, the distance from the center to the outer periphery is not constant) or a head 163b that is eccentric with respect to the male screw shaft 163a.

  In the above embodiment, the frame member 33 having a predetermined height is used to make the vertical height constant. However, the present invention is not limited to this, and as shown below, the tip of the sub-core 12 and the main core 11 can also be provided with an elevating member for adjusting these vertical gaps.

  FIG. 11 is a perspective view showing a transformer according to an embodiment of the present invention. In FIG. 11, the pad 14 is disposed in the frame member 33 so as to be positioned below the sub-core 12 as a lifting member that adjusts the height of the sub-core 12 relative to the main core 11.

  Moreover, as shown in FIG. 12, a roller 15 having an eccentric shaft can be used.

  Further, as shown in FIG. 13, an elevating member comprising a fixed elastic member 162 that presses one end of the sub-core 12 to fix the position and a clamp 163 with a screw rod that moves up and down across the other end of the sub-core 12 may be used. .

  Hereinafter, embodiments of the transformer to which the structure of the sub-core part is applied will be described.

  FIG. 14 is a plan view showing a transformer according to an embodiment of the present invention. In this transformer, one conductive wire is wound around each of the portions of the main core 11 that are close to one end (the lower side of FIG. 14) of the sub-core 12 at two opposing portions that face the sub-core 12. The primary windings 111 and 111 are formed, and windings 10 and 10 are formed by winding a plurality of conductive wires on portions close to the other end (upper side in FIG. 14) of the sub-core 12. The secondary windings 112 and 112 are provided.

  FIG. 15 is a plan view showing a transformer according to an embodiment of the present invention. Unlike the above embodiment, this transformer has secondary windings 112 and 112 formed as a plurality of windings 10 and 10 at the end of the main core 11 near the subcore 12 on both sides of the subcore 12. Provided, and primary windings 111 and 111 formed by winding one conductive wire at the end opposite to the end.

  FIG. 16 is a plan view showing a transformer according to an embodiment of the present invention. In this transformer, primary windings 111 and 111 formed by winding one conductive wire around the end of the main core 11 near the sub core 12 on both sides of the sub core 12 are arranged with the sub core interposed therebetween. A plurality of adjacent windings 10 and 10 and secondary windings 112 and 112 formed by winding a plurality of windings at the end of the main core 11 on the opposite side. ing.

  Winding the primary winding in this manner further improves the current balance of the discharge tube. In addition, since only one winding is electrically required, the winding may be once wound around an external terminal and then connected to the external circuit 20 in FIGS. 3 and 4 by external wiring. .

  In each of the above-described transformers, the sub-core 12 is moved with respect to the main core 11 to adjust the mutual inductance between the windings and the self-resonance frequency of the secondary winding, so A structure having coupling can be easily found, and at the same time, the current flowing in the discharge tube can be stabilized equally.

  As described above, by providing the sub-core 12 so as to move in the X direction with respect to the main core 11, it is possible to freely adjust the mutual inductance of adjacent windings. The current flowing in the discharge tube can be equally stabilized.

  Although the present invention has been described with reference to a specific example of the use of a liquid crystal backlight discharge tube as one of its embodiments, the mutual inductance adjustment method of the present invention can be applied to adjacent windings. Mutual inductance can be adjusted freely, and it has the effect of being able to stabilize the current flowing on the winding evenly with high output and low heat generation, so it is useful in various electrical devices that require this. It is.

It is sectional drawing which shows the trans | transformer of one Example of this invention. It is a perspective view which decomposes | disassembles and shows schematic structure of the transformer of FIG. It is a perspective view showing a transformer of one example of the present invention. It is a perspective view showing a transformer of one example of the present invention. It is a top view which shows the transformer of one Example of this invention. It is a perspective view which decomposes | disassembles and shows the transformer of one Example of this invention. FIG. 7 is a perspective view showing a state where the transformer of FIG. 6 is assembled. It is a perspective view showing a transformer of one example of the present invention. It is a perspective view showing a transformer of one example of the present invention. It is a perspective view showing a transformer of one example of the present invention. It is sectional drawing which shows the trans | transformer of one Example of this invention. It is sectional drawing which shows the trans | transformer of one Example of this invention. It is a perspective view showing a transformer of one example of the present invention. It is a top view which shows the transformer of one Example of this invention. It is a top view which shows the transformer of one Example of this invention. It is a top view which shows the transformer of one Example of this invention. It is a top view which shows an example of the conventional transformer. FIG. 18 is a circuit diagram using the transformer of FIG. 17. FIG. 19 is an equivalent circuit diagram of FIG. 18. FIG. 20 is a circuit diagram for explaining how a current flows in the discharge tube in the circuit of FIG. 19.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Transformer 10 ... Adjacent winding 11, 110 ... Main core 111 ... Primary winding 112 ... Secondary winding 113, 114, 121, 122, 124 ... Area 115, 116, 31, 32 ... Bobbin 12, 12a, 12b ... sub-core 123 ... gap 13 ... square frame 161 ... guide member 162 ... elastic member 163 ... control member 163a ... screw 163b ... head 20 ... external circuit 33 ... frame member (cylindrical case member)
33a, 33b ... end face 331a, 332a, 331b, 332b ... localization part 331, 332 ... case member 334 ... passage 334a, 334b ... shaft hole 334c ... side wall

Claims (23)

A main core in which a plurality of windings are wound side by side;
The cross-sectional area is smaller than the cross-sectional area of the main core and is movable with respect to the main core so as to change the mutual inductance generated between the adjacent windings. A transformer characterized by being configured by combining a sub-core arranged in The sub-core is disposed across the main core so that the bottom surface of the sub-core is in contact with the main core,
The transformer according to claim 1, wherein the sub-core is movably disposed so as to change a gap between the sub-core and the main core.   The transformer according to claim 2, wherein the sub-core is covered with a cover having a U-shaped cross section.   The sub-core is movably disposed so as to change a gap between the sub-core and the main core without contacting a bottom surface of the sub-core with the main core. The described transformer. It further comprises a frame member having a passage formed therein,
The transformer according to claim 4, wherein the sub-core is inserted into the passage so as not to contact the main core.   The transformer according to claim 5, wherein the frame member is a cylindrical case. The cylindrical case is divided into two, a first case member and a second case member, each of which is formed with a plurality of stereotaxic portions that are engaged with each other and locked together.
The first case member and the second case member are arranged so that their central axes coincide with each other so that the sub-core is inserted in communication with each other to form a coaxial passage. The transformer according to claim 6. The frame member has two vertical end faces perpendicular to the axis, with the sub-core as an axis,
Each of the two vertical end faces has a shaft hole as the passage,
The transformer according to claim 5, wherein the sub-core is a male screw-shaped rod, and is inserted into the two shaft holes.   Guide members for guiding the sub-core to move along the passage in the passage are formed on the two side walls in the passage of the frame member so as to protrude so as to contact the sub-core. The transformer according to claim 5, wherein An elastic member that presses and biases the sub-core in contact with the sub-core on one end side of the passage;
The transformer according to claim 5, further comprising a control member on the other end side of the passage that contacts the sub-core and stops the sub-core at a different predetermined position against the biasing force. The control member is a screw having a shaft portion arranged perpendicular to the main core,
11. The transformer according to claim 10, wherein a head portion of the screw is a flat head, is located in contact with the sub-core, and is eccentric with respect to an irregular shape or the shaft portion. The two sub-cores are arranged in a straight line with a gap between them;
The transformer according to claim 1, wherein a gap between the two sub-cores is adjustable.   The transformer according to claim 1, further comprising an elevating member for adjusting a vertical gap between a front end portion of the sub-core and the main core.   The transformer according to claim 13, wherein the elevating member is a pad disposed under the sub-core.   The transformer according to claim 13, wherein the elevating member is a roller having an eccentric shaft.   14. The transformer according to claim 13, wherein the elevating member includes an elastic member that presses and fixes one end of the sub-core and a clamp with a screw rod that elevates and lowers the other end of the sub-core. A primary winding wound around each of two end portions of the main core located on both sides of the one end portion of the sub-core;
The secondary winding wound around two other end portions of the main core located on both sides of the other end portion of the sub-core is provided as the plurality of windings. The transformer according to 1. A secondary winding is provided as a plurality of adjacent windings on the two first end sides of the main core located on both sides across one end of the sub-core,
The transformer according to claim 1, further comprising a primary winding wound around two second end portions opposite to the two first end portions of the main core. . A primary winding is provided as a plurality of adjacent windings on the two first end sides of the main core located on both sides across one end of the sub-core,
The transformer according to claim 1, further comprising a secondary winding wound around two second end portions opposite to the two first end portions of the main core. .   The transformer according to any one of claims 17 to 19, wherein the primary winding is electrically wound by a single winding across the sub-core.   The transformer according to claim 1, wherein a cross-sectional area of the sub-core is equal to or less than one half of an effective cross-sectional area of the main core.   The transformer according to claim 1, wherein a cross-sectional area of the main core near the sub-core is equal to or less than an effective cross-sectional area of the main core.   The transformer according to claim 1, wherein a cross-sectional area of a portion of the main core away from the sub-core is equal to or greater than an effective cross-sectional area of the main core.

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