JP2010003855A - Inverter transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct a displacement in leakage inductance occurring because of a fluctuation in dimension and in assembling of a magnetic core of an inverter transformer. <P>SOLUTION: The inverter transformer comprises: a primary winding 11, a secondary winding 12, a bobbin 13 having a winding axis with the primary and the secondary winding separately wound; and a pair of cores provided to the bobbin to form a closed magnetic circuit, magnetically coupling the primary and the secondary winding. Bases 13b, 13b of the both ends of the bobbin are formed wider than the winding axis and are the outer circumference of the winding axis, and a third magnetic core 18 is arranged in the region sandwiched by the base of the both ends. Consequently, even when the displacement occurs between the value of the leakage inductance after the primary magnetic core 15a and the secondary magnetic core 15b are mounted and the value of the leakage inductance of other inverter transformer, a part of a flux generated by the primary winding 11 has an influence on the secondary winding 12 through the third magnetic core 18 to modify the value of the leakage inductance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an inverter transformer, and more specifically to an inverter transformer that drives an inverter of a backlight of a display panel of an electronic device such as a liquid crystal TV or a car navigation device.

Electronic devices such as liquid crystal TVs and car navigation devices include a backlight device using a cold cathode fluorescent tube or other discharge lamp. In order to light these discharge lamps, an inverter circuit is used to obtain a high voltage from a low-voltage DC power source.

As a transformer for driving the inverter circuit, for example, as shown in FIG. 7, Patent Document 1 discloses a transformer 110 using a magnetic core 115 made of a ferrite core. The transformer 110 includes an I-type core 115a and a C core. The I-type core 115a is attached to a magnetic core insertion hole (not shown) formed on the winding shaft 113a of the bobbin 113 to which the primary side winding 111 and the secondary side winding 112 are applied. The C-type core 115b is located above the bobbin 113 in the direction perpendicular to the winding axis, and the C-type core 115b is opposed to the I-type core 115a outside the magnetic core insertion hole of the bobbin 113. A backlight transformer 110 has been proposed.

Further, in Patent Document 2, for example, as shown in FIG. 8, a bobbin 201 provided with at least a primary winding and a secondary winding (not shown), and freely movable to an inner cavity portion of the bobbin 201 are disclosed. The first magnetic core 230 is inserted, and the second magnetic core 240 is attached to the bobbin so as to cover at least one surface of the winding. The first magnetic core 230 and the second magnetic core 240 have a shape that changes the leakage inductance as the relative positional relationship changes, and the bobbin 201 is used to lock one end of the first magnetic core 230. Leakage inductance in which an elastic member 250 is provided on one end side 207 and adjusting means 260 for moving the first magnetic core 230 by pressing from the other end of the first magnetic core 230 is provided on the other end side 206 of the bobbin. A variable adjustment inverter transformer 210 has been proposed.
JP-A-9-186024 Japanese Patent Laid-Open No. 2007-142088

As described in the background art above, in the backlight transformer 110 in which at least one of the cores 115 is inserted into the magnetic core insertion hole of the winding shaft 113a of the bobbin 113, the dimensions and shape of the core to be used Due to variations and assembly conditions, leakage inductance may deviate from the other backlight transformers by, for example, about ± 10%, and in devices that use a plurality of backlight transformers, there may be variations in lighting characteristics and beat noise. There was a problem of becoming a factor. In the inverter transformer 210 having a structure in which the leakage inductance is changed as the relative positional relationship between the first magnetic core 230 and the second magnetic core 240 changes as described in the latter background art. Therefore, it is necessary to increase the size of the magnetic cores 230 and 240 and the bobbin 201 by the amount of adjustment.

The present inventors have found that the leakage inductance can be corrected by disposing the third magnetic core on the outer periphery of the winding shaft around which the bobbin winding is wound, and have reached the present invention.

It is an object of the present invention to provide an inverter transformer that can be corrected to a desired leakage inductance even when the leakage inductance is deviated due to variations in dimensions and assembly state of magnetic cores to be used. .

In order to achieve the above object, the present invention provides (1) a bobbin having a winding shaft in which a magnetic core insertion hole penetrating in the axial direction is formed, and bases respectively provided at both ends in the axial direction of the winding shaft; A primary winding and a secondary winding wound in different regions among a plurality of regions formed by dividing the bobbin winding axis, and a first magnetic core inserted in the magnetic core insertion hole And a second magnetic core attached to the bobbin so as to cover at least one surface of the winding shaft around which the winding is wound, wherein the bases at both ends are formed wider than the winding shaft. The third magnetic core is disposed in a region on the outer periphery of the winding shaft and sandwiched between the bases at both ends. (... hereinafter referred to as first problem solving means)

In addition to the first problem solving means, one of the main forms of the inverter transformer is (2) the third magnetic core on the surface facing the winding shaft of the second magnetic core. The magnetic core is bonded. (... hereinafter referred to as second problem solving means)

In addition to the first problem solving means, one of the other main embodiments of the inverter transformer further includes: (3) an insulating layer on the outer periphery of the winding shaft so as to cover the secondary winding. The third magnetic core is bonded to the surface of the insulating layer. (... hereinafter referred to as third problem solving means)

The operation of the first problem solving means is as follows. That is, a bobbin having a winding shaft in which a magnetic core insertion hole penetrating in the axial direction is formed, and bases respectively provided at both ends in the axial direction of the winding shaft, and a winding shaft of the bobbin are divided. A primary winding and a secondary winding wound in different regions of the plurality of regions, a first magnetic core inserted in the magnetic core insertion hole, and a winding shaft on which at least the winding is wound An inverter transformer having a second magnetic core attached to the bobbin so as to cover one side of
The bases at both ends are formed wider than the winding shaft,
A third magnetic core is disposed in a region between the outer periphery of the winding shaft and sandwiched between the bases at both ends. For this reason, the third magnetic core is prevented from protruding from the external dimensions of the inverter transformer, and can be mounted in the same space as before, and after the first magnetic core and the second magnetic core are mounted. Even when the leakage inductance value differs from the leakage inductance of another inverter transformer, a part of the magnetic flux generated in the primary winding affects the secondary winding via the third magnetic core. The leakage inductance value is corrected.

The operation of the second problem solving means is as follows. That is, the third magnetic core is bonded to the surface of the second magnetic core facing the winding shaft. For this reason, generation | occurrence | production of the sound by a 2nd magnetic core and a 3rd magnetic core colliding with the vibration generate | occur | produced by a magnetostriction or the vibration provided from an external environment can be suppressed. In addition, since the second magnetic core has high mechanical strength, the third magnetic core can be held more stably by bonding the third magnetic core to the second magnetic core. .

The operation of the third problem solving means is as follows. That is, an insulating layer is provided on the outer periphery of the winding shaft so as to cover the secondary winding, and the third magnetic core is bonded to the surface of the insulating layer. For this reason, a wide contact area can be obtained, and the movement of the third magnetic core due to vibrations generated by magnetostriction or vibrations applied from the external environment can be suppressed.

According to the present invention, it is possible to provide an inverter transformer that can be corrected to a desired leakage inductance even when a deviation occurs in the leakage inductance due to dimensional variation of the magnetic core to be used or an assembled state.
The above object and other objects, structural features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.

Hereinafter, a first embodiment of an inverter transformer of the present invention will be described with reference to FIGS. FIG. 1 is an external perspective view showing the overall structure of the inverter transformer 10 according to the first embodiment of the present invention. FIG. 2 is a longitudinal sectional view taken along line AA of FIG. 1 showing the internal structure of the inverter transformer 10 of the present embodiment. FIG. 3 is an exploded perspective view for explaining the internal structure of the inverter transformer 10 of the present embodiment.

As shown in FIGS. 1 to 3, the inverter transformer 10 of the present embodiment includes a primary winding 11, a secondary winding 12, and the primary winding 11 and the secondary winding 12 that are divided and wound. And a pair of magnetic cores 15 that are attached to the bobbin 13 to form a closed magnetic circuit and magnetically couple the primary winding 11 and the secondary winding 12 to each other. Specifically, the bobbin 13 includes a winding shaft 13a in which a magnetic core insertion hole 13c penetrating in the axial direction is formed, and bases 13b and 13b respectively provided at both ends in the axial direction of the winding shaft 13a. Have The winding shaft 13a of the bobbin 13 has the primary winding 11 and the secondary winding 12 in different regions among a plurality of winding winding regions formed by dividing the winding shaft 13a by an intermediate rod 13d. Is wound. A plurality of terminals 14 and 14 are respectively implanted on the bases 13b and 13b at both ends. The primary winding 11 is wound around a partial region of the winding shaft 13a, and each of the end portions 11a thereof is a connection terminal different from each other of at least one base 13b of the bases at both ends of the bobbin 13. 14. The secondary winding 12 is wound around a region different from the above of the winding shaft 13a, and each of its ends (not shown) is a base different from the above among the bases at both ends of the bobbin 13. 13b are connected to different connection terminals 14. The set of magnetic cores 15 is formed on the bobbin 13 so as to cover the first magnetic core 15a inserted into the magnetic core insertion hole 13c and one surface of the winding shaft 13a around which the winding is wound. The second magnetic core 15b is attached. The first magnetic core 15a and the second magnetic core 15b are bonded and fixed to the base 13b with an adhesive 16, respectively. The bases 13b, 13b at both ends are formed wider than the winding shaft 13a, and the third magnetic core 18 is disposed in an outer periphery of the winding shaft 13a and sandwiched between the bases 13b, 13b at both ends. Is arranged. In the inverter transformer 10 of the present embodiment, the third magnetic core 18 is bonded to the surface of the second magnetic core 15b facing the winding shaft 13a with an adhesive 16. Further, in the inverter transformer 10 of the present embodiment, the primary winding 11 and the secondary winding 12 are respectively provided on the winding shaft 13a of the bobbin 13 around which the primary winding 11 and the secondary winding 12 are wound. Insulating layers 17 and 17 are provided so as to cover them. The third magnetic core 18 is bonded to the surface of the insulating layer 17 covering the secondary winding 12 using an adhesive 16.

As described above, the magnetic flux generated in the primary winding 11 due to the third magnetic core 18 being disposed in the outer periphery of the winding shaft 13a and the region sandwiched between the bases 13b and 13b at both ends. Part of the current affects the secondary winding 12 via the third magnetic core 18, and the leakage inductance is corrected.

Next, the inverter transformer 10 of this embodiment will be described more specifically. As shown in FIG. 3, the bobbin 13 has a winding shaft 13a and bases 13b and 13b provided at one and the other end of the winding shaft 13a, respectively, and the center of the winding shaft 13a. A magnetic core insertion hole 13c is formed so as to penetrate. The winding shaft 13a is formed by dividing an area around which the primary winding 11 is wound and an area around which the secondary winding 12 is wound by an intermediate rod 13d, and the secondary winding 12 is wound around the winding axis 13a. Similarly, the region to be rotated is further divided into a plurality of regions by the intermediate rod 13d.

Each of the bases 13b and 13b is provided with a plurality of connection terminals 14 and 14 having, for example, a substantially E shape or a substantially U shape in plan view. The plurality of connection terminals 14 and 14 are connected to the terminal portion 14a on one end side, the connection piece 14c on the other end side, the terminal portion 14a and the connection piece 14c, and embedded in the base 13b. It is comprised with the implantation part which abbreviate | omitted illustration. In the case of the connection terminal 14 having a substantially E shape in plan view, for example, the two terminal portions 14a are connected to one connection piece 14c by an implantation portion (not shown). The terminal portions 14a are bent in a so-called gull wing shape so as to protrude horizontally from the end surface of the base 13b and then to protrude downward from the bottom surface of the base 13b. The connection piece 14c protrudes in the horizontal direction from the end surface of the base 13b. In the case of the connection terminal 14 having a substantially U shape in plan view, for example, one terminal portion 14a is connected to one connection piece 14c by an implantation portion (not shown). The other configuration is the same as that of the substantially E-shape.

The primary winding 11 is formed of, for example, a so-called litz wire formed by twisting a plurality of magnet wires, and is wound around a region for winding the primary winding 11 on one end side of the winding shaft 13a of the bobbin 13. It has been turned. The end portions 11a and 11a of the primary winding 11 are pulled out to the distal end side of the base 13b through a drawing groove (not shown) formed in the lower portion of one base 13b of the bobbin 13. The connection piece 14c of the connection terminal 14 planted on the base 13b is peeled off in a state where the insulating coating is peeled off, and is soldered by immersion in molten solder or the like to be electrically connected to the connection terminal 14. ing.

The secondary winding 12 uses an insulation-coated conductive wire having a thinner wire diameter than the primary winding 11, and is used for winding the secondary winding 12 out of the winding shaft 13 a of the bobbin 13. The plurality of divided regions are wound sequentially from one end side toward the center flange of the bobbin 13 and the end portions 12a and 12a thereof are formed below the other base 13b of the bobbin 13. It is pulled out to the distal end side of the base 13b through a drawing groove omitted in the drawing, and is tangled in a state where the insulating coating is peeled off from the connection piece 14c of the connection terminal 14 implanted in the base 13b. The connection terminal 14 is conductively connected by solder or the like. A consumer of the inverter transformer 10 of the present embodiment mounts the inverter transformer 10 on the circuit board of the power supply unit in the casing of the electronic device including a liquid crystal display panel, for example, The terminal portion 14a is used by being connected by a conductive bonding material such as solder.

Each of the pair of magnetic cores 15 is made of a magnetic material such as Mn—Zn ferrite. As shown in FIG. 3, the first magnetic core (I-type core) 15a of the set of magnetic cores 15a is inserted into the magnetic core insertion hole 13c of the bobbin 13 from one end side, and the magnetic core The both ends of the first magnetic core (I-type core) 15a protrude from the magnetic core insertion hole 13c by being abutted against the convex portion of one base 13b of the bobbin 13 on one end side of the core insertion hole 13c. And is positioned so as to be exposed on the base 13b.

As shown in FIG. 3, the tips of the leg portions 15c of the second magnetic core (C-type core) 15b are abutted against the upper surface of the first magnetic core (I-type core) 15a from above. Yes.

Further, as shown in FIG. 1, the pair of cores 15 are bonded and fixed to the base 13 b with, for example, an epoxy adhesive 16 at the lengthwise ends of the magnetic core insertion holes 13 c of the bobbins 13. ing. In addition, as described above, the pair of magnetic cores 15 has one end of the leg portion 15c of the second magnetic core (C-type core) 15b and one end of the first magnetic core (I-type core) 15a. The primary winding 11 and the secondary winding 12 are configured to be magnetically coupled by forming a closed magnetic circuit by being fixed in a state of being abutted against the main surface.

In the present embodiment, the inverter transformer is a normal form in which the primary winding 11 and the secondary winding 12 are wound around the set of magnetic cores 15 via the bobbin 13. It is not limited to. Although not shown, for example, an inverter transformer having a so-called twin structure in which two sets of primary windings and secondary windings are wound around a set of magnetic cores forming a closed magnetic circuit may be used. Specifically, for example, the first secondary winding, the first primary winding, the second primary winding, and the second secondary winding are arranged in a plurality of sections of the bobbin winding shaft from one end side. May be wound in this order. As another example, for example, the first secondary winding, the common primary winding, and the second secondary winding are wound in order from one end to a plurality of sections of the bobbin winding shaft. Also good.

A preferred embodiment of the primary winding 11 is as follows. That is, the primary winding 11 is wound around the winding shaft 13a of the bobbin 13, and is preferably an insulation-coated conductor, such as a polyurethane resin-coated conductor, a polyester resin-coated conductor, an enamel resin-coated conductor, or the like. Is more preferable. Further, the metal wire of the primary winding 11 is not limited to a single wire, and may be a stranded wire such as a so-called litz wire. Further, the metal wire of the primary winding 11 is not limited to a circular cross-sectional shape, and a rectangular wire having a rectangular cross-sectional shape, a square wire having a square cross-sectional shape, or the like may be used. Moreover, you may use the self-bonding wire which coat | covered the outer periphery of the said insulation coating conducting wire with resin of low melting | fusing point. Each of the end portions 11a, 11a of the primary winding 11 has different connection terminals implanted in at least one base 13b among a plurality of bases provided at least at both ends of the winding shaft of the bobbin 13. It is preferable that each of the 14 connection pieces 14c is peeled off in a state where the insulating coating is peeled off, and is electrically connected to the connection terminal 14 by solder or the like.

A preferred embodiment of the secondary winding 12 is as follows. That is, it is preferable that the secondary winding 12 is divided and wound into a plurality of regions partitioned around the winding shaft 13 a of the bobbin 13. Moreover, like the said primary winding 11, an insulation coating conducting wire is preferable and a polyurethane resin coating conducting wire, a polyester resin coating conducting wire, an enamel resin coating conducting wire, etc. are more preferable. Further, the metal wire of the secondary winding 12 is not limited to a single wire, and may be a stranded wire. The metal wire of the secondary winding 12 is not limited to a circular cross-sectional shape, and a rectangular wire having a rectangular cross-sectional shape, a square wire having a square cross-sectional shape, or the like may be used. Moreover, you may use the self-bonding wire which coat | covered the outer periphery of the said insulation coating conducting wire with resin of low melting | fusing point. Since it is necessary to increase the number of turns of the secondary winding 12 in order to generate a high voltage, it is generally preferable that the wire diameter of the secondary winding 12 is smaller than the wire diameter of the primary winding 11. . Further, each of the end portions 12 a and 12 a of the secondary winding 12 is formed of a plurality of bases provided at least at both ends of the winding shaft 13 a of the bobbin 13, similarly to the end portion 11 a of the primary winding 11. Of the plurality of connection terminals 14 and 14 planted on the base 13b different from the above, the connection pieces 14c of the connection terminals 14 different from each other are entangled in a state where the insulating coating is peeled off, solder, etc. It is preferable that the connection terminal 14 is conductively connected.

A preferred embodiment of the bobbin 13 is as follows. That is, as the material of the bobbin 13, an insulating resin is preferable, and an insulating resin such as a phenol resin, a polyester resin, or a liquid crystal polymer that has heat resistance and can be injection-molded with the plurality of connection terminals 14 and 14 is used. More preferred. The bobbin 13 preferably includes at least a winding shaft 13a and a base 13b provided at one end and the other end of the winding shaft 13a, but is not limited thereto. For example, a plurality of discharge tubes In what has a so-called twin structure including a plurality of secondary windings for turning on the lamp, a base may be further provided in an intermediate region of the winding shaft 13a, and a connection terminal may be planted on the base. . The winding shaft 13a of the bobbin 13 is preferably formed by dividing an area around which the primary winding 11 is wound and an area around which the secondary winding 12 is wound by an intermediate rod 13d. Moreover, it is preferable that the area | region where the said secondary winding 12 is wound is further divided into plurality by the intermediate rod 13d. The intermediate rod 13d that divides the region around which the secondary winding 12 is wound is preferably provided with a transition groove for winding the secondary winding 12 sequentially between adjacent regions. The base 13b of the bobbin 13 is preferably provided with connection terminals 14 and 14 to which the end portion 11a of the primary winding 11 or the end portion 12a of the secondary winding 12 is fixed. As the connection terminals 14 and 14 to be planted on the base 13b, a so-called Galwin type is preferable when surface mounting is performed on a substrate on which an inverter circuit is formed and reflow soldering is performed. When the connection terminal is inserted into the through hole and is soldered by flow, a pin type that is implanted vertically on the base 13b is preferable. The core insertion hole 13c of the bobbin 13 is preferably formed so as to penetrate the center of the winding shaft 13a. Further, the internal dimension of the magnetic core insertion hole 13c of the winding shaft 13a in the region where the secondary winding 12 is wound is such that the first magnetic core (I-type core) 15a is inserted. It is preferable that the size is slightly larger than the outer shape of one magnetic core 15a.

Next, a preferred embodiment of the connection terminal 14 is as follows. That is, it is preferable that the connection terminal 14 includes a planting portion embedded in the base 13b, a terminal portion 14a protruding from the base 13b, and a connection piece 14c.

Next, a preferred embodiment of the set of magnetic cores 15 (the first magnetic core 15a and the second magnetic core 15b) is as follows. That is, as the material of the set of magnetic cores 15, various magnetic materials such as Mn—Zn ferrite, Ni—Zn ferrite, dust core, laminated metal plate, and the like can be used. The structure of the set of magnetic cores 15 is preferably such that at least one is inserted into the magnetic core insertion hole 13c of the bobbin 13 and forms a magnetic path in a combined state. As the external shape of the set of magnetic cores 15, for example, a C-C type, a C-I type, or the like is preferable in order to be accommodated along a frame part such as a liquid crystal display panel. Further, the present invention is not limited to this, and for example, in order to obtain a thin inverter transformer, it may be an EE type, an EI type, a low I type, or the like.

Next, a preferred embodiment of the adhesive 16 is as follows. That is, the adhesive 16 preferably has an insulating resin as a main component, and may contain an inorganic filler or the like as necessary. It can be selected and used from an epoxy resin adhesive having a high heat resistance, a silicone resin adhesive, and the like, but outside the first magnetic core 15a and the magnetic core insertion hole 13c in the magnetic core insertion hole 13c. In order to mutually regulate vibration generated by magnetostriction of the second magnetic core 15b and vibration applied from the external environment, an epoxy resin adhesive is more preferable.

Next, a preferred embodiment of the insulating layer 17 is as follows. That is, the insulating layer 17 is preferably provided so as to cover the secondary winding 12 on the outer periphery of the winding shaft 13a around which the secondary winding 12 of the bobbin 13 is wound. As the material of the insulating layer 17, polyester, polyimide, and the like are preferable, and polyimide is more preferable from the viewpoint of insulating performance. The insulating layer 17 is preferably one having an adhesive layer or a fusion layer on one main surface, or one having heat shrinkability.

Next, a preferred embodiment of the third magnetic core 18 is as follows. That is, the third magnetic core is preferably a sheet or plate. The material of the third magnetic core 18 is preferably selected from those exemplified as the material of the set of magnetic cores 15. Moreover, it is more preferable that it is a Mn-Zn type ferrite from a viewpoint of the high correction capability of leakage inductance. The size of the magnetic core is not particularly limited, but is preferably disposed in a region sandwiched between the bases at both ends. Further, when the third magnetic core 18 is disposed, it is preferable that the third magnetic core 18 is bonded to the surface of the second magnetic core 15b facing the winding shaft 13a. For this reason, it is preferable to provide an adhesive layer in advance on the surface of the third magnetic core 18 to be bonded to the second magnetic core 15b in order to facilitate bonding. Further, in disposing the third magnetic core 18, it is preferable that the third magnetic core 18 is bonded to the surface of the insulating layer 17 covering the secondary winding 12. For this reason, it is preferable to provide an adhesive layer in advance on the surface of the third magnetic core 18 to be bonded to the surface of the insulating layer 17 in order to facilitate bonding. Further, in order to facilitate fixing the winding shaft around which the secondary winding is wound, for example, L having a plane along each of a plurality of sides of the outer shape of the intermediate rod provided on the winding shaft. You may adhere | attach the said 3rd magnetic core through the guide which consists of insulating thin plates, such as letter shape and U shape.

Next, a second embodiment of the inverter transformer of the present invention will be described with reference to FIGS. FIG. 4 is a longitudinal sectional view corresponding to FIG. 2 in the first embodiment showing the internal structure of the inverter transformer 20 of the present embodiment. FIG. 5 is an exploded perspective view for explaining the internal structure of the inverter transformer 20 of the present embodiment.

As shown in FIGS. 4 and 5, the inverter transformer 20 of the present embodiment is similar to the inverter transformer 10 of the previous embodiment, and includes a primary winding 21, a secondary winding 22, and the primary winding 21. A bobbin 23 in which the secondary winding 22 is divided and wound, and a set of magnets that are attached to the bobbin 23 to form a closed magnetic circuit and magnetically couple the primary winding 21 and the secondary winding 22. And a core 25.

Specifically, the bobbin 23 includes a winding shaft 23a in which a magnetic core insertion hole 23c penetrating in the axial direction is formed, and bases 23b and 23b provided at both ends in the axial direction of the winding shaft 23a, Have The winding shaft 23a of the bobbin 23 has the primary winding 21 and the secondary winding 22 in different regions among a plurality of winding winding regions formed by dividing the winding shaft 23a by an intermediate rod 23d. Is wound. A plurality of terminals 24 and 24 are respectively implanted on the bases 23b and 23b at both ends. Further, the primary winding 21 is wound around a part of the winding shaft 23 a, and each of the end portions 21 a is a different connection terminal of at least one base 23 b of the bases at both ends of the bobbin 23. 24. The secondary winding 22 is wound around a different area of the winding shaft 23a, and each of its ends (not shown) is a base different from the above among the bases at both ends of the bobbin 23. 23b are connected to different connection terminals 24. The set of magnetic cores 25 is formed on the bobbin 23 so as to cover the first magnetic core 25a inserted into the magnetic core insertion hole 23c and one surface of the winding shaft 23a around which the winding is wound. The second magnetic core 25b is attached. The first magnetic core 25a and the second magnetic core 25b are bonded and fixed to the base 23b with an adhesive 26, respectively. The bases 23b, 23b at both ends are formed wider than the winding shaft 23a, and a pair of third bases are formed on the outer periphery of the winding shaft 23a and sandwiched between the bases 23b, 23b at both ends. Magnetic cores 28 are provided. In the inverter transformer 20 of the present embodiment, the pair of third magnetic cores 28 and 28 are bonded to the surface of the second magnetic core 25b facing the winding shaft 23a by an adhesive 26. . Further, in the inverter transformer 20 of the present embodiment, the primary winding 21 and the secondary winding 22 are respectively provided on the winding shaft 23a of the bobbin 23 around which the primary winding 21 and the secondary winding 22 are wound. Insulating layers 27 are provided so as to cover them. The pair of third magnetic cores 28 and 28 are bonded to the surface of the insulating layer 27 covering the secondary winding 22 via a U-shaped guide 29. Adhesion between the U-shaped guide 29 and the third magnetic cores 28 and 28 and adhering between the insulating layer 27 and the U-shaped guide 29 are performed by an adhesive 26, respectively. As described above, the third magnetic cores 28 and 28 are disposed in the outer periphery of the winding shaft 23a around which the winding 22 is wound and in the region sandwiched between the bases 23b and 23b at both ends. A part of the magnetic flux generated in the primary winding 21 influences the secondary winding 22 through the third magnetic cores 28 and 28, and the leakage inductance is corrected.

The first difference between the inverter transformer 20 of the present embodiment and the inverter transformer 10 of the previous embodiment is the change in the number and arrangement of the third magnetic cores 28. Specifically, the pair of third magnetic cores 28 and 28 are respectively disposed on the outer periphery of the winding shaft 23a and in regions sandwiched between the bases 23b and 23b at both ends. As a result, the leakage inductance can be significantly corrected.

The second difference of the inverter transformer 20 of the present embodiment from the inverter transformer 10 of the previous embodiment is that the pair of third magnetic cores 28, 28 is provided with the insulating layer 27 via a U-shaped guide 29. It is glued to the surface. Thereby, in determining the adhesion position of the third magnetic cores 28, 28 on the outer periphery of the winding shaft 23a, the third magnetic core can be easily moved and positioned. Other configurations and operational effects are the same as those of the first embodiment, and thus description thereof is omitted.

Next, an embodiment of the inverter transformer of the present invention will be described. (Embodiment 1) The inverter transformer 10 of the first embodiment of the present invention has the configuration as described in the first embodiment. As shown in FIGS. 1 to 3, the inverter transformer 10 of the present embodiment includes a primary winding 11, a secondary winding 12, and the primary winding 11 and the secondary winding 12 are divided and wound. A bobbin 13 made of liquid crystal polymer, and a pair of magnetic cores 15 (first magnetic cores) made of Mn—Zn ferrite that is attached to the bobbin 13 and magnetically couples the primary winding 11 and the secondary winding 12. A core 15a and a second magnetic core 15b). Specifically, the bobbin 13 includes a winding shaft 13a in which a magnetic core insertion hole 13c penetrating in the axial direction is formed, and bases 13b and 13b provided at both ends in the axial direction of the winding shaft 13, respectively. Have The winding shaft 13a of the bobbin 13 has the primary winding 11 and the secondary winding 12 in different regions among a plurality of winding winding regions formed by dividing the winding shaft 13a by an intermediate rod 13d. Is wound. A plurality of connection terminals 14, 14 are respectively implanted on the bases 13b, 13b at both ends. The primary winding 11 is wound around a part of the winding shaft 13a, and its end 11a is connected to the connection terminal 14 of one base 13b of the bases at both ends of the bobbin 13. Yes. The secondary winding 12 is wound around a region different from the above of the winding shaft 13a, and each of its ends (not shown) is a base different from the above among the bases at both ends of the bobbin 13. 13b are connected to different connection terminals 14. The set of magnetic cores 15 includes a first magnetic core 15a inserted into the magnetic core insertion hole 13c, and one surface of a winding shaft 13a around which the primary winding 11 and the secondary winding 12 are wound. And a second magnetic core 15b attached to the bobbin 13 so as to cover it. The first magnetic core 15a and the second magnetic core 15b are bonded and fixed to the base 13b using an epoxy resin adhesive 16, respectively. In the inverter transformer 10 of this embodiment, the primary winding 11 and the secondary winding 12 are wound around the winding axis 13a of the bobbin 13 and the region where the primary winding 11 is wound. Insulating layers 17 and 17 made of polyimide and having a thickness of 0.05 mm are formed so as to cover the region where the next winding 12 is wound. In this state, the connection terminals 14 and 14 connected to the end portions 11a and 11a of the primary winding 11 and the connection terminals 14 and 14 connected to the end portions 12a and 12a of the secondary winding 12 are not shown. An inductance measurement circuit is connected to measure an initial leakage inductance value. In the inverter transformer 10 of the present embodiment, the bases 13b and 13b at both ends are formed wider than the winding shaft 13a, and are the outer periphery of the winding shaft 13a and the bases 13b at both ends. In a region sandwiched by 13b, Mn-- having a length of 20 mm, a width of 7 mm, and a thickness of 1.3 mm
A third magnetic core 18 made of Zn-based ferrite is disposed. The third magnetic core 18 is bonded to the surface of the second magnetic core 15b facing the winding shaft 13a by an epoxy resin adhesive 16. The third magnetic core 18 is also adhered to the surface of the insulating layer 17 covering the region around which the secondary winding 12 is wound by the adhesive 16 as described above. FIG. 6 shows the result of measuring the relationship between the arrangement position of the third magnetic core 18 (distance from the secondary side base 13b) and the leakage inductance. As is clear from FIG. 6, as the disposition position of the third magnetic core 18 moves away from the secondary base, in other words, as the disposition position of the third magnetic core 18 approaches the primary winding 11. It was confirmed that the value of leakage inductance [mH] increases. Thereby, it can correct | amend to a desired leakage inductance by selecting the arrangement | positioning position of the 3rd magnetic core 18. FIG.

The present invention is suitable as an inverter transformer for various electronic devices having a backlight, such as a liquid crystal TV.

1 is an external perspective view showing an overall structure of a first embodiment of an inverter transformer of the present invention. It is a longitudinal cross-sectional view in the AA line of the said FIG. 1 which shows the internal structure of the inverter transformer of the said embodiment. It is a disassembled perspective view for demonstrating the internal structure of the inverter transformer of the said embodiment. It is a longitudinal cross-sectional view for demonstrating the internal structure of 2nd Embodiment of the inverter transformer of this invention. It is a disassembled perspective view for demonstrating the internal structure of the inverter transformer of the said embodiment. It is a figure which shows the measurement result of the change of the leakage inductance in the arrangement | positioning position (distance from a secondary side base) of the 3rd magnetic core of the inverter transformer of the Example of this invention. It is an external appearance perspective view which shows an example of background art. It is a top view which shows the other example of background art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20: Inverter transformer 11, 21: Primary winding 11a, 21a: End part 12, 22: Secondary winding 13, 23: Bobbin 13a, 23a: Winding shaft 13b, 23b: Base 13c, 23c: Magnetic core Insertion holes 13d, 23d: intermediate rods 14, 24: connection terminals 14a, 24a: terminal portions 14c, 24c: connection pieces 15, 25: a set of magnetic cores 15a, 25a: first magnetic core (I-type core) 15b , 25b: second magnetic core (C-type core) 15c, 25c: magnetic legs 16, 26: adhesive 17, 27: insulating layer 18, 28: third magnetic core 29: guide

Claims (3)

A bobbin having a winding shaft in which a magnetic core insertion hole penetrating in the axial direction is formed, and bases respectively provided at both ends in the axial direction of the winding shaft, and a plurality of the bobbin winding shafts formed by dividing the bobbin winding shaft A primary winding and a secondary winding wound in different regions of the region, a first magnetic core inserted in the magnetic core insertion hole, and at least one surface of a winding shaft on which the winding is wound An inverter transformer having a second magnetic core attached to the bobbin so as to cover
The bases at both ends are formed wider than the winding shaft,
An inverter transformer, wherein a third magnetic core is disposed in a region on the outer periphery of the winding shaft and sandwiched between the bases at both ends. The inverter transformer according to claim 1, wherein the third magnetic core is bonded to a surface of the second magnetic core facing the winding shaft. The insulating layer is provided on the outer periphery of the winding shaft so as to cover the secondary winding, and the third magnetic core is bonded to the surface of the insulating layer. Inverter transformer.

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