JP2009158573A - Transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transformer, capable of obtaining desired magnetic shielding with a compact and simple structure and securely that ensures the insulation distance required on a primary and a secondary side, even with respect to a higher voltage. <P>SOLUTION: The transformer is such that a first bobbin 1 in a flat square tube shape wound with a primary coil and a second bobbin 2, in a flat square tube shape wound with a second coil are disposed adjacently in an axial direction, and a closed magnetic path is formed of cores 12 and 13 made of magnetic materials disposed over the first and second bobbins; a magnetic shielding magnetic material core 14, which is formed into a flat plate shape to cover the first and second bobbins in the axial direction is disposed on the top and reverse surfaces of the first and second bobbins; and a range which is at an outer periphery of the magnetic cores and whose length in the axial direction is longer than an insulation distance of the safety standard adaptive to an operating voltage is covered with an insulating member 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transformer excellent in magnetic shielding effect, which is suitable for use in a device that generates a high voltage from a secondary coil such as an inverter transformer for lighting a cold cathode tube.

  A cold cathode tube discharge / lighting transformer incorporated as a light source of a liquid crystal display boosts the input voltage to the primary coil to a high voltage of 1000 to 2000 V in the secondary coil and outputs the boosted voltage to the cold cathode tube. Is.

By the way, in the above transformer, a leakage magnetic flux is generated during operation, which causes noise and the like, and therefore a magnetic shield is provided as a countermeasure.
For example, in Patent Document 1 below, a coil portion having at least a primary winding and a secondary winding, a magnetic core incorporated in the coil portion, and at least two sides of the outer peripheral surface abut on the magnetic core to cover the coil portion. Converter transformers composed of magnetic shield plates made of sintered ferrite, resin ferrite, or metal plates have been proposed.

On the other hand, the transformer adopts a structure that secures a predetermined insulation distance (creeping distance) between the primary coil and the secondary coil in accordance with safety standard requirements.
In particular, the transformer used for lighting the cold-cathode tube has a higher voltage specification than a general low-voltage transformer, and thus is longer between the primary coil and the secondary coil. It is required to secure an insulation distance and ensure insulation between each other.

However, when the magnetic shield plate is provided as a shield measure, even when the insulation between the primary coil and the secondary coil is secured, the magnetic shield disposed across the primary coil and the secondary coil. Since the plate is not an insulator, it is necessary to obtain a predetermined insulation performance for the magnetic shield plate. As a result, the structure of the transformer is complicated and increased in size. There was a problem of going backwards.
Japanese Patent Laid-Open No. 10-74634

  The present invention has been made in view of such circumstances. A desired magnetic shield can be obtained with a small and simple structure, and the primary side and the secondary side can be surely connected to a higher voltage. It is an object of the present invention to provide a transformer capable of ensuring the insulation distance required for the above.

  In order to solve the above-mentioned problem, the transformer according to claim 1 includes a flat rectangular tube-shaped first bobbin around which a primary coil is wound, and a flat rectangular tube-shaped first coil around which a secondary coil is wound. Two bobbins are disposed adjacent to each other in the axial direction, and a closed magnetic circuit is formed by a core made of a magnetic material disposed across the first and second bobbins, and A magnetic material core for magnetic shielding, which is formed in a flat plate shape and covers the first and second bobbins in the axial direction, is disposed on at least one of the upper and lower surfaces of the first and second bobbins. In addition, the outer circumference of the magnetic material core, the range in which the length in the axial direction is longer than the safety standard insulation distance adapted to the operating voltage is covered with an insulating member. It is.

  According to a second aspect of the present invention, in the first aspect of the present invention, the insulating member is an insulating tape wound around an outer periphery of the magnetic material core.

  On the other hand, the invention according to claim 3 is the invention according to claim 1, wherein the insulating member is formed in a rectangular tube shape and the magnetic material core is inserted therein. It is a feature.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the insulating member is formed in a rectangular tube shape into which the first and second bobbins are inserted, and the insulating member A rectangular cylindrical storage portion is integrally formed on at least one of the upper surface and the lower surface, and the magnetic material core is inserted into the storage portion. Here, it is preferable to form an insulating partition between the first and second bobbins inside the insulating member.

  Further, the invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the core is a first core located on the first bobbin side and the second bobbin side. And the other one of the first bobbin and the second bobbin includes the other primary coil and the first core or the secondary coil and the second bobbin. And an insulating covering portion including a partition wall interposed between the primary coil and the secondary coil and between the magnetic joints of the first and second cores is formed. It is characterized by this.

  According to the transformer according to any one of claims 1 to 5, at least one of the upper surface and the lower surface of the first bobbin and the second bobbin disposed adjacent to each other in the axial direction is formed as a flat magnetic plate. Since it is covered with the magnetic material core for shielding, a desired shielding effect can be obtained by the magnetic material core. In addition, the magnetic material core can also increase leakage, and therefore, when used in a device that uses a continuous discharge phenomenon such as a cold cathode tube, it can also stabilize the current. it can.

  In addition, when the outer circumference of the magnetic material core is covered with an insulating member so that its length in the axial direction is longer than the insulation distance of the safety standard adapted to the operating voltage, it becomes a high-voltage specification In this case, it is possible to ensure the insulation distance required by the safety standard between the primary side and the secondary side.

  As a result, a desired magnetic shield can be obtained with a small and simple structure, and an insulation distance required between the primary side and the secondary side can be ensured even for higher voltage. It becomes possible.

  Here, various forms can be adopted as a structure for covering the outer periphery of the magnetic material core with an insulating member. For example, as in the invention described in claim 2, a simple configuration in which an insulating tape is wound around the outer periphery of the magnetic material core can be adopted. Alternatively, as in a third aspect of the invention, the insulating member is formed in a rectangular tube shape to which a flat magnetic material core can be inserted, and the magnetic material core is inserted therein. Good.

  According to a fourth aspect of the present invention, the insulating member is formed in a rectangular tube shape into which the first and second bobbins are inserted, and a rectangular tube is formed on at least one of the upper surface and the lower surface of the insulating member. Since the magnetic material core is inserted into the storage part and the magnetic material core is inserted into the storage part, a desired shielding effect and leakage increasing effect can be obtained.

  According to a fourth aspect of the present invention, if an insulating partition is formed between the first and second bobbins inside the insulating member, the primary coil wound around the first bobbin And the secondary coil wound around the second bobbin can ensure an insulation distance corresponding to the axial length of the insulating member. For this reason, in addition to obtaining the shielding effect, the insulation distance required between the primary side and the secondary side can be ensured reliably even for higher voltage.

  Further, as in the invention described in claim 5, the core is divided into a first core on the first bobbin side and a second core on the second bobbin side, and the first bobbin and Either one of the second bobbins covers the outer periphery of the primary part composed of the other primary coil and the first core or the outer periphery of the secondary part composed of the secondary coil and the second core, and If the insulation coating part in which the partition part interposed between the primary part and the secondary part is integrally formed is formed, the insulation coating part is formed between the primary coil and the secondary coil. An insulation distance corresponding to the length dimension in the axial direction can be ensured. Therefore, even when a high voltage is input to the above-described primary coil, this can be accommodated by a simple structure.

(First embodiment)
1 and 2 show a first embodiment in which the transformer according to the present invention is applied to an inverter transformer for lighting a cold cathode tube as a backlight of an LCD, and FIG. 3 shows a modification thereof. It is.
In these inverter transformers, the bobbin is divided into a first bobbin 1 and a second bobbin 2.

  The first bobbin 1 has a flat rectangular tube-shaped first winding portion 3 around which a primary coil (not shown) formed at the central portion in the axial direction is wound, and the first winding. A first terminal mounting portion 5 having a substantially rectangular plate shape in which a terminal 4 formed on one end side in the axial direction of the portion 3 and connected to the end portion of the primary coil is implanted; The insulating coating 6 formed on the other axial end is integrally formed of a synthetic resin having electrical insulation.

  The insulation coating portion 6 is formed in a rectangular tube shape that is slightly larger in width and thickness than the first winding portion 3, and the insulation coating portion 6, the first winding portion 3, and the like. A partition wall 7 that blocks the internal space is integrally formed therebetween. Here, the thickness dimension in the axial direction of the partition wall portion 7 is a dimension capable of ensuring predetermined magnetic connection characteristics while achieving electrical insulation of first and second cores described later, for example, 1 It is set in the range of 0.0 to 0.4 mm.

  As a result, the first winding portion 3 has an inner space that opens to the first terminal mounting portion 5 side, and an inner wall surface 3 a that is flat and continuous with the surface 5 a of the first terminal mounting portion 5. Is formed. Further, the insulation coating portion 6 is formed such that the length dimension in the axial direction is the same as or slightly larger than the length dimension in the axial direction of a second winding portion 8 to be described later of the second bobbin 2.

  On the other hand, the second bobbin 2 has a square cylindrical second winding portion 8 around which a secondary coil (not shown) is wound, and one axial direction end side of the second winding portion 8. A flat plate-like second terminal mounting portion 10 in which terminals 9 to which the end portions of the secondary coils are connected is planted is integrally formed of a synthetic resin having an electrical insulating property. .

  In the second winding portion 8, a plurality of partition plates 11 for preventing creeping discharge in the high-voltage secondary coil are integrally formed on the outer peripheral portion at equal intervals in the axial direction. 11 is formed to be slightly smaller than the inner dimension of the insulating coating portion 6 in the first bobbin 1. Further, the second winding portion 8 is formed so that the inner space thereof opens to the second terminal mounting portion 10 side and the inner wall surface thereof is continuous with the surface 10 a of the second terminal mounting portion 12. ing.

  Further, the first and second bobbins 1 and 2 are provided with cores that form a closed magnetic path as a whole. This core is divided into a first core 12 located on the first bobbin 1 side and a second core 13 located on the second bobbin 2 side.

  The first core 12 and the second core 13 include a pair of outer cores 12a and 13a extending in the axial direction along the outer periphery of the first bobbin 1 or the second bobbin 2, and the outer cores 12a. , 13a is formed in an E shape having inner cores 12b, 13b located in the middle part.

  Here, the outer core 12 a and the inner core 12 b of the first core 12 are formed to have a length dimension substantially equal to the length dimension in the axial direction of the first winding portion 3, and the outer side of the second core 13. The core 13a and the inner core 13b are formed to have a length dimension substantially equal to the length dimension in the axial direction of the second winding portion 8 (or the insulation coating portion 6).

In the first core 12, the inner core 12b is inserted into the internal space of the first winding portion 3, and the outer cores 12a are arranged along the primary coil with a slight gap therebetween. Is attached to the first bobbin 1.
The second core 13 also has the inner core 13b inserted into the inner space of the second winding portion 8 and the outer cores 13a arranged at slight intervals along the secondary coil. Is attached to the second bobbin 2.

  And the 2nd bobbin 2 is inserted in the insulation coating | coated part 6 of the 1st bobbin 1 by the 2nd coil | winding part 8 and the 2nd core 13 in which the secondary coil was wound, The first bobbin 1 is integrally connected. Thereby, the flat-plate-shaped transformer main body is formed as a whole.

  Further, in this transformer, the insulating covering portion 6 formed in a flat plate shape and having the first bobbin 1 and the second bobbin 2 inserted in the upper and lower surfaces, which are the wide surfaces of the transformer body, is arranged in the axial direction. A magnetic material core 14 for covering the magnetic shield is disposed.

  An insulating tape (insulating member) 15 is wound around the outer periphery of the magnetic material core 14 and corresponding to the first bobbin 1. Here, the length L of the insulating tape 15 in the axial direction is set to a dimension that is longer than the safety-standard insulating distance adapted to the operating voltage of the transformer. The surface of the insulating tape 15 facing the first bobbin 1 is formed thick so that the magnetic material core 14 contacts the upper and lower surfaces of the insulating coating 6.

Further, in the modification shown in FIG. 3, the insulating tape (insulating member) 15 is disposed on the outer periphery of the magnetic material core 14 in the range of the length dimensions L ₁ and L ₂ from both ends toward the axial direction. It is wound. In this transformer, the total length dimension (L ₁ + L ₂ ) of the insulating tape 15 in the axial direction is set to a dimension that is longer than the insulation distance of the safety standard adapted to the operating voltage of the transformer. .

  According to the transformer having the above configuration, the upper and lower surfaces of the first bobbin 1 and the second bobbin 2 arranged adjacent to each other in the axial direction are covered with the magnetic material core 14 for a flat magnetic shield. Therefore, a desired shielding effect can be obtained by the magnetic material core 14. In addition, since the magnetic material core 14 can obtain an effect of increasing leakage, it is also possible to obtain an effect of stabilizing current in a continuous discharge phenomenon.

In addition, the outer circumference of the magnetic material core 14 is covered by the insulating member 15 so that the lengths L and L ₁ + L ₂ in the axial direction are longer than the safety standard insulation distance adapted to the operating voltage. Even in the case of high pressure specifications, it is possible to ensure the insulation distance required by the safety standards between the primary side and the secondary side.

  As a result, a desired magnetic shield can be obtained with a small and simple structure, and an insulation distance required between the primary side and the secondary side can be ensured even for higher voltage. it can.

(Second Embodiment)
4 and 5 show a second embodiment of a transformer according to the present invention. The same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals and the description thereof is simplified. To do.
This transformer differs from that shown in the first embodiment in that an insulating case 20 is used instead of the insulating tape 15 as an insulating member.

  The insulating case 20 is formed of a thin and flat rectangular tube shape with a synthetic resin having electrical insulation, and a hole portion 21 into which the flat magnetic material core 14 is inserted without any gap is formed. ing. The area of the wide surface of the insulating case 20 is set to a size that can cover the insulating covering portion 6 in which the first bobbin 1 and the second bobbin 2 are inserted in the axial direction.

  The insulating case 20 may have a configuration in which one end side of the hole 21 is closed. The insulating case 20 is integrated with the magnetic material core 14 inserted into the hole 21 and disposed on the upper and lower surfaces of the transformer body, which are the wide surfaces.

  The same effect as that of the first embodiment can be obtained by the transformer having the above configuration. In addition, in the transformer of the present embodiment, since the total length in the axial direction of the insulating case 20 is the insulation distance, it is possible to ensure a long insulation distance between the primary side and the secondary side without fail. In addition, since it is only necessary to insert the magnetic material core 14 into the insulating case 20 and dispose it on the upper and lower surfaces of the transformer body, the assembly is easy.

  In particular, a bottomed cylindrical mounting member into which the insulating case 20 can be inserted, a U-shaped guide portion that can sandwich both sides of the insulating case 20, or the insulating case 20 is provided on the insulating covering portion 6 side. If the concave and convex portions that are fitted to each other are provided on the insulating coating portion 6, the assembly is further facilitated.

(Third embodiment)
6 and 7 show a third embodiment of a transformer according to the present invention. Similarly, the same components as those shown in FIGS. Simplify.
This transformer is different from those shown in the first and second embodiments in that the insulating coating portion 6 is not formed on the first bobbin 1 and that the insulating tape 15 or the insulating case is used as an insulating member. Instead of 20, the outer periphery covering insulating case 30 is used.

  The outer periphery covering insulating case 30 is a flat rectangular tube-shaped member formed of a synthetic resin having electrical insulation properties, and its inner dimension is a primary consisting of the first bobbin 1 and the first core 12. The side part and the secondary part made up of the second bobbin 2 and the second core 13 are formed in a size that allows loose insertion.

In addition, the outer periphery covering insulating case 30 is formed to have a length dimension that allows at least the primary coil and the secondary coil to be continuously surrounded in the axial direction.
A partition wall portion that closes the central portion in the axial direction is integrally formed in the outer periphery covering insulating case 30. Incidentally, the partition wall portion is also set to a dimension in which the thickness dimension in the axial direction can achieve the electrical insulation of the first and second cores 12 and 13 and can also ensure a predetermined magnetic connection characteristic. Has been.

  Further, on the upper and lower surfaces, which are the wide surfaces of the outer covering case 30, storage portions 31 into which the flat magnetic material cores 14 are inserted with almost no gap are formed. The outer periphery covering case 30 may also be configured such that one end side of the storage portion 31 is closed.

  In this transformer, the primary part composed of the first bobbin 1 and the first core 12 is inserted from the one end opening side of the outer periphery covering case 30, and the second bobbin 2 and the second bobbin 2 from the other end opening side. The secondary part composed of the two cores 13 is inserted, and the magnetic material core 14 is inserted into the storage portion 31 for assembly.

  According to the transformer according to this embodiment, in addition to being able to obtain the same effects as those shown in the first and second embodiments, the number of parts as a whole is reduced. It becomes even easier. Also, since the assembly can be completed by inserting the primary part from the one end opening side of the outer peripheral covering insulating case 30 and inserting the secondary part from the other end opening side, Simplification can also be achieved.

  In the above embodiment, only the case where an E-type core in which the outer cores 12a and 13a and the inner cores 12b and 13b are integrated is used as the first and second cores 12 and 13 has been described. However, the present invention is not limited to this. For example, a C-type core having only a pair of outer cores or a core that becomes an E-type as a whole by disposing an I-type core between the central portions of the C-type core is used. Is also possible.

1 is a perspective view showing a first embodiment of a transformer according to the present invention. FIG. 2 is an exploded perspective view of FIG. 1. It is a disassembled perspective view which shows the modification of 1st Embodiment of FIG. It is a perspective view which shows 2nd Embodiment of the trans | transformer which concerns on this invention. FIG. 5 is an exploded perspective view of FIG. 4. It is a perspective view which shows 3rd Embodiment of the trans | transformer which concerns on this invention. FIG. 7 is an exploded perspective view of FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st bobbin 2 2nd bobbin 6 Insulation coating | cover part 7 Partition part 12 1st core 13 2nd core 12a, 13a Outer core 12b, 13b Inner core 14 Magnetic material core 15 Insulation tape (insulation member)
20 Insulating case (insulating material)
30 Case for outer periphery covering 31 Storage part

Claims (5)

A flat rectangular tube-shaped first bobbin around which the primary coil is wound and a flat rectangular tube-shaped second bobbin around which the secondary coil is wound are disposed adjacent to each other in the axial direction. A closed magnetic path is formed by a core made of a magnetic material disposed across the first and second bobbins.
In addition, a magnetic material core for magnetic shielding, which is formed in a flat plate shape and covers the first and second bobbins in the axial direction, is disposed on at least one of the upper and lower surfaces of the first and second bobbins. In addition, the outer circumference of the magnetic material core, the range in which the length in the axial direction is longer than the safety standard insulation distance adapted to the operating voltage is covered with an insulating member. Transformer.   The transformer according to claim 1, wherein the insulating member is an insulating tape wound around an outer periphery of the magnetic material core.   The transformer according to claim 1, wherein the insulating member is formed in a rectangular tube shape, and the magnetic material core is inserted therein.   The insulating member is formed in a rectangular tube shape into which the first and second bobbins are inserted, and a rectangular tube-shaped storage portion is integrally formed on at least one of the upper surface and the lower surface of the insulating member. The transformer according to claim 1, wherein the magnetic material core is inserted into the storage portion.   The core is divided into a first core located on the first bobbin side and a second core located on the second bobbin side, and the first bobbin and the second bobbin One of them covers the outer periphery of the other primary coil and the first core or the secondary coil and the second core, and between the primary coil and the secondary coil and between the first and second coils. The transformer according to any one of claims 1 to 4, wherein an insulating coating portion having a partition wall interposed between magnetic joint portions of the core is formed.

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