JP2006108390A - Transformer core and leakage transformer employing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize low profile, decrease the number of components, simplify the structure, and reduce the cost while enhancing the efficiency by one input multiple output system. <P>SOLUTION: The transformer core has a first core portion constituted of an outer circumference core 1 of rectangular frame shape and leakage cores 2 and 3 linking two opposing sides of the outer circumference core 1, and a second core portion (coil winding core 6) arranged to intersect the leakage cores 2 and 3 substantially perpendicularly and being secured to the bottom face of the outer circumference core 1 to oppose these leakage cores 2 and 3 through a predetermined interval (leakage gap g). A primary coil 8 is arranged in the center of the coil winding core 6 and secondary coils 10, 11, 13 and 14 are arranged on the opposite sides thereof. A plurality of leakage cores 2 and 3 are provided in correspondence with the position between the primary coil and the secondary coil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transformer core including a leakage core that constitutes a leakage magnetic path, and further relates to a leakage transformer using the same.

  As a liquid crystal TV inverter circuit system, a collector resonance type circuit system is generally used, but this collector resonance type circuit also has a resonance circuit on the primary side and causes interference with the resonance circuit on the secondary side. Has the disadvantage of being bad. In addition, when the waveform is asymmetrical, it is necessary to use a ballast capacitor in order to cut off a direct current component (cause of abnormal discharge) caused by the rectifying action of the cold cathode discharge lamp (CFL), which causes an increase in cost. .

  In recent years, with the increase in size of liquid crystal TVs and the like, a secondary side resonance type circuit system that stably turns on a cold cathode discharge lamp without using a ballast capacitor which causes a decrease in efficiency and an increase in cost has come to be adopted. ing. The secondary-side resonance type circuit (externally-excited resonance type circuit) uses a so-called leakage transformer, in which secondary side leakage inductance and parasitic capacitance, or an auxiliary resonance capacitor resonates. This is based on the fact that the power factor seen from the transformer primary side near the point is dramatically improved. The secondary side resonance type circuit does not require the ballast capacitor, and has an advantage of improving the power factor (efficiency improvement) of the transformer.

  By the way, with the increase in size of the liquid crystal TV, it is necessary to turn on a large number of cold cathode discharge lamps. Accordingly, the number of transformers used increases and the space occupancy of the transformer tends to increase. The case where the leakage transformer is used is not an exception. For this reason, various one-input / multi-output type leakage transformers having two or more secondary coils for one primary coil have been proposed (for example, (See Patent Document 1 and Patent Document 2).

  For example, in Patent Document 1, an inner core is wound with one primary coil connected to an inverter circuit and at least two secondary coils connected independently to a fluorescent lamp, and between the coils. A leakage transformer is disclosed in which an outer core having a magnetic leg constituting a leakage magnetic path is arranged so as to surround each coil. Patent Document 2 discloses an inverter transformer in which one primary winding and a plurality of secondary windings are provided and each secondary winding is electromagnetically coupled to the primary winding with the same degree of coupling. It is disclosed that each secondary winding of an inverter transformer is connected to a different discharge lamp. In the inverter transformer described in Patent Document 2, the projection serves as a leakage magnetic leg. Therefore, when this projection is provided, the inverter transformer operates as a leakage transformer.

In this way, if a single-input multiple-output type leakage transformer is used, it is not necessary to correspond the number of cold cathode discharge lamps to the number of transformers on a one-to-one basis, and the space occupancy can be reduced by reducing the number of transformers. it is conceivable that.
JP 59-40513 A JP 2001-126937 A

  However, when considering further reduction in the height of the leakage transformer and simplification of the structure, there are still many points to be improved in the inventions described in the patent documents. For example, the invention described in Patent Document 1 has a structure in which the outer core is abutted against the inner core from both sides, and the number of cores is three. If the number of cores is large, the structure becomes complicated and the assembly work is required.

  On the other hand, in the invention described in Patent Document 2, since the coil is sandwiched in the height direction from the board surface to be mounted, it is difficult to reduce the height of the transformer. Further, as the number of secondary coils increases, it is necessary to increase the number of second legs, which causes problems such as an increase in the area required for mounting and a complicated core shape.

  The present invention has been proposed in view of such a conventional situation. That is, the present invention can achieve high efficiency by increasing the number of inputs and outputs, and can further reduce the number of parts and simplify the structure, and is advantageous in reducing the height of the transformer core. The purpose is to provide a leakage transformer.

  In order to achieve the above-described object, the transformer core of the present invention includes a first core portion including a rectangular frame-shaped outer peripheral core and a leakage core connecting two opposing sides of the outer peripheral core. A second core portion that is disposed substantially orthogonal to the leakage core and is fixed to the bottom surface of the outer peripheral core so as to face the leakage core with a predetermined interval, and the leakage core Is provided in a plurality corresponding to the position between the primary coil and the secondary coil. The leakage transformer of the present invention includes the transformer core, and a primary coil is wound around a center position of the second core portion, and secondary coils are wound on both sides of the primary coil. The leakage core is disposed at a position between the secondary coils.

  In the transformer core of the present invention, the leakage core is provided for the purpose of forming a leakage magnetic flux path, and has a structure in which a leakage gap is formed between the leakage core and the second core portion. . This structure makes it possible to control the leakage magnetic flux.

  Further, in the leakage transformer of the present invention, the primary coil is disposed in the center of the second core portion, the leakage magnetic pole (leakage core) is disposed in the vicinity of both sides thereof, and the secondary coil is disposed on the outside thereof. It has become. Accordingly, the secondary coil is arranged symmetrically with respect to the primary coil, the primary coil and the secondary coil are separated by the leakage core, and a sufficiently large leakage inductance is secured by the leakage core. The voltage fluctuation between them is kept small.

  In the present invention, the transformer core is composed of two core parts, that is, a first core part including an outer peripheral core and a leakage core, and a second core part around which the primary coil and the secondary coil are wound. . Therefore, for example, as compared with the invention described in Patent Document 1, the number of necessary cores is reduced and the structure is simplified.

  In addition, the transformer core or leakage transformer of the present invention is basically arranged horizontally rather than having a structure in which the coil is sandwiched in the height direction as in the invention described in Patent Document 2, so that the height is reduced. Is advantageous.

  Furthermore, in the present invention, for example, it is not necessary to correspond the number of core portions around which the secondary coil is wound with the number of secondary coils, and only one second core portion is arranged. Therefore, an increase in mounting area and an increase in structure due to an increase in the number of outer legs as in the invention described in Patent Document 2 are avoided.

  In the leakage transformer of the present invention, it is also possible to arrange the soft magnetic thin plate so as to cover the upper surface when it is placed horizontally by utilizing its structural characteristics. In this case, in addition to the above-described configuration, a soft magnetic thin plate is disposed on the upper surface side when it is horizontally disposed. By placing a soft magnetic thin plate on the upper surface side, the primary and secondary coils are shielded, reducing magnetic flux leakage. For example, when mounted on a board, the influence of leakage magnetic flux to the surroundings is suppressed. Will be.

  According to the transformer core and the leakage transformer of the present invention, it is possible to achieve high efficiency by increasing the number of inputs and outputs, realizing a reduction in height, reducing the number of parts, simplifying the structure, and reducing costs. Is possible. Further, according to the present invention, it is possible to design so that the output is taken out from each secondary coil almost evenly.

  Hereinafter, a transformer core and a leakage transformer to which the present invention is applied will be described with reference to the drawings.

(First embodiment)
1 to 3 show the shape and structure of the transformer core of this embodiment. FIGS. 4 to 6 show the structure of a leakage transformer in which a primary coil and a secondary coil are mounted on the transformer core.

  The transformer core 1 of the present embodiment is composed of two core parts. First, as shown in FIG. 1, the first core part is a rectangular frame-shaped outer peripheral core 1 and the outer peripheral core. It is comprised from the leaking cores 2 and 3 provided so that one long side which mutually opposes may be connected. The leakage cores 2 and 3 are provided at a boundary position between a primary coil and a secondary coil, which will be described later. In the case of this embodiment, the secondary coils are arranged on both sides of the primary coil. 2 and 3 are provided.

  The outer peripheral core 1 has a height that can accommodate a primary coil and a secondary coil, which will be described later, and has a hollow casing-like appearance that is open at the top and bottom. Each of the leakage cores 2 and 3 is a rod-shaped (prism-shaped) core, but is not as thick as the outer core 1 (height dimension). As shown in FIG. 1 is formed integrally with the outer core 1 at a position close to the upper surface of 1. The leakage cores 2 and 3 are arranged in parallel with each other at a predetermined interval.

  Concave portions 4 and 5 for positioning and fixing the second core portion are formed on the bottom surface on the short side of the outer peripheral core 1, and the second core portion is fitted and disposed through a spacer gap. Thus, the first core portion and the second core portion are magnetically coupled. In the fitting arrangement, the spacer gap is necessary so that the effective magnetic permeability is adjusted so as not to be easily saturated.

  The second core portion is a single rod-shaped core, and is constituted by a coil winding core 6 around which a primary coil and a secondary coil are wound. As shown in FIG. 3, the coil winding core 6 is disposed on the bottom surface side of the outer core 1 and is fitted to the concave portions 4 and 5 so that both ends thereof are fitted to the outer core 1 and further for leakage. It is positioned and fixed with respect to the cores 2 and 3.

  Here, the positional relationship between the coil winding core 6 and the leakage cores 2 and 3 will be described. The coil winding core 6 and the leakage cores 2 and 3 are mutually connected when viewed in a plane. They are arranged orthogonally. On the other hand, in the height direction, as shown in FIG. 3, a predetermined gap, that is, a leakage gap g is formed between each of the leakage cores 2 and 3 and the coil winding core 6. The leakage gap g can be adjusted by, for example, the depth of the recesses 4 and 5 provided on the bottom surface of the outer core 1, and the leakage magnetic flux can be controlled by this structure.

  The cross-sectional shape of the coil winding core 6 may be a rectangular shape, for example. In this case, a rectangular shape with corners may be used, but when the primary coil or the secondary coil is directly wound, for example, the insulating film of the winding is prevented from being carelessly peeled off at the corners. In order to achieve this, it is preferable to form a rectangular shape whose corners are chamfered obliquely or in an arc shape. However, when the coil winding core 6 is fitted into the recesses 4 and 5 of the outer core 1, the effective permeability is adjusted by inserting the spacer gap as described above. The core 6 can be used more efficiently if the corners are left behind rather than being chamfered. Considering prevention of chipping of the coil winding core 6 and ease of insertion of the bobbin, a cross-sectional shape with a rounded corner is advantageous.

  In each core portion of the transformer core of the present embodiment, for example, the outer core 1, the leakage cores 2 and 3, and the coil winding core 6 are all formed of a ferrite material or the like, for example, a predetermined shape It is formed by forming and sintering. As the ferrite material, any ferrite material such as Mn-Zn ferrite can be used, but in order to improve performance, a ferrite material having a low iron loss and a high saturation magnetic flux density is used. It is preferable.

  In the transformer core, as shown in FIG. 4, a coil bobbin 7 in which a primary coil 8 is wound is inserted in the center of a coil winding core 6, and secondary coils 10 and 11 are wound on the outer sides thereof, respectively. By inserting the coil bobbin 9 and the coil bobbin 12 around which the secondary coils 13 and 14 are wound, and attaching the coil winding core 6 to the recesses 4 and 5 on the bottom surface of the outer core 1 as the first core portion. The leakage transformer shown in FIG. 5 is configured. The primary coil 8 and the secondary coils 10, 11, 13, and 14 are coil-wound while being wound around bobbins 7, 9, and 12 formed of an insulating material (for example, plastic) as described above. The winding core 6 is mounted, and each coil (the primary coil 8 and the secondary coils 10, 11, 13, and 14) has a winding length regulated by the flange portions 7a, 9a, and 12a of the bobbin.

  A terminal plate 15 to which the coil ends are connected is attached to the bottoms of the primary coil 8 and the secondary coils 10, 11, 13, and 14. Moreover, the terminal pin 16 is attached to this terminal board 15, For example, when it mounts in a board | substrate, the input to the primary coil 8 and the output from the secondary coils 10, 11, 13, and 14 are as follows. This is done through the terminal plate 15 and the terminal pin 16.

  In the leakage transformer of the present embodiment, four transformers are configured by the primary coil 8 and the four secondary coils (secondary coils 10, 11, 13, and 14), and therefore the leakage of the present embodiment. The transformer functions as an inverter transformer with one input and four outputs.

  In the leakage transformer configured as described above, the ratio between the number of turns of the primary coil 8 and the number of turns of each of the secondary coils 10, 11, 13, and 14 is appropriately set according to the required voltage. On the other hand, the number of turns of each secondary coil 10, 11, 13, 14 is the same as the number of turns when the output output from each secondary coil 10, 11, 13, 14 is constant.

  The leakage transformer having the above configuration is arranged and mounted so that the outer peripheral core 1, the leakage cores 2 and 3, and the coil winding core 6 are substantially parallel to the board surface of the mounting board. The That is, the mounting form of the leakage transformer of this embodiment is a so-called horizontal arrangement. Therefore, for example, the height can be reduced as compared with the structure in which the coil is sandwiched in the height direction.

  In the leakage transformer of the present embodiment, the transformer core is formed as a first core portion in which the outer peripheral core 1 and the leakage cores 2 and 3 are integrally formed, and a second coil winding core 6 is formed. It is composed of core parts, and the number of core parts is two. Therefore, the number of cores can be reduced and the structure can be simplified as compared with the leakage transformer described in Patent Document 1, for example. Further, as the coil winding core, one coil winding core 6 may be prepared. For example, unlike the invention described in Patent Document 2, it is not necessary to form the legs as many as the number of secondary coils. Therefore, the structure can be simplified also in this respect.

  In the leakage transformer 20 of the present embodiment, the leakage cores 2 and 3 are disposed between the primary coil 8 and the secondary coil 11 and between the primary coil 8 and the secondary coil 13. , 3 and the coil winding core 6 form a leakage gap, so that the primary winding (primary coil 8) and the secondary winding (secondary coils 10, 11, 13, 14) are separated. Further, the secondary coils 10 and 11 and the secondary coils 13 and 14 are arranged symmetrically with respect to the primary coil 8. Therefore, the voltage fluctuation on the secondary side can be reduced.

  Further, in the leakage transformer of the present embodiment, a sufficiently large leakage inductance can be secured between the leakage cores 2 and 3 and the coil winding core 6. For example, when used in a liquid crystal TV inverter circuit, a plurality of cooling transformers are used. Variations in the discharge operation of the cathode discharge lamp can be suppressed.

(Second Embodiment)
The leakage transformer of this embodiment is an example in which the number of secondary coils is further increased. The number of secondary coils is preferably an even number. In the first embodiment, four secondary coils are arranged. In this embodiment, four coils are provided on one side of the primary coil, for a total of eight. The secondary coil is arranged. The configuration of the leakage transformer of this embodiment is shown in FIG. Since the structure of the transformer core is the same as that of the first embodiment, the description thereof is omitted here.

  In the leakage transformer of the present embodiment, eight secondary coils 21, 22, 23, 24, 25, 26, 27, and 28 are attached to one primary coil 8, and therefore, an inverter having one input and eight outputs. Functions as a transformer. Four secondary coils are arranged on one side of the primary coil 8, and the leakage coil formed between the leakage cores 2 and 3 and the coil winding core 6 is the same as in the first embodiment. The primary winding (primary coil 8) and the secondary winding (secondary coils 21, 22, 23, 24, 25, 26, 27, 28) are separated, and the secondary coils 21, 22, 23, 24 The secondary coils 25, 26, 27, 28 are arranged symmetrically with respect to the primary coil 8. Therefore, as in the first embodiment, it is possible to extract outputs from the eight secondary coils 21, 22, 23, 24, 25, 26, 27, and 28 substantially evenly.

(Third embodiment)
The present embodiment is an example in which a shielding soft magnetic thin plate is attached to the upper surface of the outer peripheral core 1. As shown in FIGS. 8 and 9, a soft magnetic thin plate 30 for shielding is attached to the upper surface of the outer core 1. Therefore, the shield plate (soft magnetic thin plate 30) is arranged so as to cover the space in which the primary coil 8 and the secondary coils 10, 11, 13, and 14 are accommodated. Since other configurations are the same as those of the transformer core and the leakage transformer of the first embodiment, the same reference numerals are given to the same members, and descriptions thereof are omitted.

  By providing the soft magnetic thin plate 30, leakage magnetic flux from the primary coil 8 and the secondary coils 10, 11, 13, and 14 is shielded. The effect of leakage magnetic flux on is effectively suppressed.

It is a top view which shows the shape of the 1st core part in the trans | transformer core of 1st Embodiment. It is a side view which shows the shape of the 1st core part in the trans | transformer core of 1st Embodiment. It is a side view which shows the attachment state to the 1st core part of the 2nd core part in the trans | transformer core of 1st Embodiment. It is a disassembled perspective view which shows the mounting state of the primary coil and the secondary coil to the transformer core of 1st Embodiment. It is a top view of the leakage transformer of a 1st embodiment. It is a side view of the leakage transformer of a 1st embodiment. It is a bottom view of the leakage transformer of 2nd Embodiment. It is a top view of the leakage transformer of a 3rd embodiment. It is a side view of the leakage transformer of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer core, 2, 3 Leakage core, 4, 5 Recessed part, 6 Coil winding core, 7, 9, 12 Bobbin, 8 Primary coil 10, 11, 13, 14, 21, 22, 23, 24, 25, 26, 27, 28 Secondary coil, 15 terminal plate, 16 terminal pin, 30 soft magnetic thin plate

Claims (9)

A first core portion composed of a rectangular frame-shaped outer peripheral core and a leakage core connecting two opposing sides of the outer peripheral core;
A second core portion that is disposed substantially orthogonal to the leakage core, and is fixed to the bottom surface of the outer peripheral core so as to face the leakage core with a predetermined interval;
A plurality of leakage cores are provided corresponding to positions between the primary coil and the secondary coil.   The transformer core according to claim 1, wherein a concave portion into which the second core portion is fitted is formed on a bottom surface of the outer peripheral core.   The transformer core according to claim 1, wherein the second core portion is chamfered at a corner portion in an arc shape.   4. The device according to claim 1, wherein the outer peripheral core, the leakage core, and the second core portion are disposed horizontally so as to be substantially parallel to a substrate surface of the substrate on which the outer core is mounted. The transformer core according to item. A transformer core according to any one of claims 1 to 3,
The primary coil is wound around the center position of the second core part, and the secondary coils are wound on both sides thereof,
A leakage transformer, wherein the leakage core is disposed at a position between the primary coil and the secondary coil.   6. The leakage transformer according to claim 5, wherein a plurality of secondary coils are wound on both sides of the primary coil.   7. The transformer core according to claim 5, wherein the outer peripheral core, the leakage core, and the second core portion of the transformer core are disposed horizontally so as to be substantially parallel to the substrate surface of the substrate on which the transformer core is mounted. Leakage transformer.   The leakage transformer according to claim 7, wherein when mounted on a substrate, the height of the outer peripheral core is higher than the height of the primary coil and the secondary coil.   The leakage transformer according to claim 8, wherein a soft magnetic thin plate is disposed on the upper surface side of the outer peripheral core.

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