JP4737229B2 - Inverter transformer - Google Patents

Description

  The present invention relates to an inverter transformer configured by mounting a low-pressure bobbin and a high-pressure bobbin on a core.

  For example, in an inverter circuit for turning on a backlight of a liquid crystal panel, an inverter transformer (for example, see Patent Documents 1 to 5) that outputs a high voltage is used. In such a high-voltage inverter transformer, it is necessary to ensure a spatial distance and a creepage distance between the high-voltage side terminal and the low-voltage side terminal that are exposed to the outside from the inverter transformer. The necessary creepage distance is determined according to, for example, the output voltage or the intended use. For example, when the output voltage becomes a high voltage of about 1200 volts, for example, it is necessary to secure, for example, 24 mm or more as the predetermined creepage distance. FIG. 4 shows an example of an I-type inverter transformer 81 having a rod-shaped core 82. The inverter transformer 81 is configured by, for example, press-fitting bobbins 83 and 84 each having a through hole and wound with coils 85 and 86 into a rod-shaped core 82. Terminals 85a and 86a connected to the coils 85 and 86 are exposed from the bobbins 83 and 84, respectively.

  By the way, in the calculation of the creepage distance in such an inverter transformer 81, the core 82 which is a conduction part is regarded as a so-called floating metal part, and therefore the surface of the core 82 is not included in the creepage distance. Therefore, for example, in the inverter transformer 81, when the core 82 is not insulated, the creeping distance between the terminal 85a and the terminal 86a is as follows. That is, as indicated by a two-dot chain line in the figure, the shortest path on the surface of the bobbin 83 that connects the terminal 85a and the vicinity of the end 82a of the core 82 protruding from the bobbin 83, and the terminal 86a and the bobbin 84 protrude. The creeping distance is obtained by adding the distance to the shortest path on the surface of the bobbin 84 connecting the portion near the other end 82b of the core 82. Further, for example, in the transformer disclosed in Patent Document 1, the end portion of the core does not protrude from the bobbin, but the core is exposed to the outside as viewed from the transformer side portion. The distance of the shortest path on the surface of the transformer from the core to the core. In the inverter transformer 81 in which the core 82 is not insulated in this way, in order to ensure the creepage distance, the bobbins 83 and 84 are enlarged, the surface of the core 82 is covered with an insulating film, or the bobbins 83 and 84 are It is necessary to inject an insulating filler into the inside of the core 82 so that the end portions 82a and 82b of the core 82 are not exposed from the bobbins 83 and 84.

However, when an insulating film or the like is provided on the surface of the core 82 or a filler or the like is used as described above, the assembly process of the inverter transformer 81 is complicated and the number of parts and the like is increased, resulting in an increase in manufacturing cost. There is a problem. In addition, since the inverter transformer 81 is enlarged, the bobbins 83 and 84 may not be enlarged to ensure the creepage distance. For example, Patent Documents 2 to 5 disclose a transformer having a structure in which a core is exposed from a bobbin, but does not disclose an effective structure or the like for such a problem concerning a creepage distance.
JP 2007-317757 A Japanese Patent Laid-Open No. 2007-142088 JP 2002-25836 A JP 2002-25835 A JP 2000-21659 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an inverter transformer that can ensure a long creepage distance and that has a small number of parts and a low manufacturing cost.

In order to achieve the above object, the invention of claim 1 includes a rod-shaped core formed using a ferromagnetic material and a cylindrical portion, and the core is positioned so that the core is positioned in the cylindrical portion. A low pressure bobbin and a high pressure bobbin mounted on the low pressure bobbin, a low pressure coil wound around the low pressure bobbin, a high pressure coil wound around the high pressure bobbin and magnetically coupled to the low pressure coil, the low pressure bobbin and the high pressure bobbin Each having a low voltage terminal and a high voltage terminal connected to the high voltage coil, wherein the low voltage bobbin and the high voltage bobbin are separate from each other and are made of resin. are molded by an integral molding using each of the cylindrical portion of the low pressure bobbin and the high pressure bobbin is not open to the opening and the other end serving as a pressure inlet of said core at one end Has a sealing portion which is sealed in at both ends of the rod-shaped core, respectively, the low pressure bobbin and is pressed from the opening of the cylindrical portion of the high pressure bobbin, both end portions of said core and said low pressure bobbin The high-pressure bobbin is prevented from being exposed to the outside by the closed end of the cylindrical portion.

According to a second aspect of the present invention, in the first aspect of the invention, a portion of the rod-shaped core where the low-pressure bobbin and the high-pressure bobbin are not press-fitted is exposed .

  According to a third aspect of the present invention, in the first or second aspect of the present invention, at least one of the low-pressure bobbin and the high-pressure bobbin is a separator that protrudes in a bowl shape from the portion around which the low-voltage coil or the high-voltage coil is wound. It is what has.

  According to the first aspect of the present invention, since the high-pressure bobbin and the low-pressure bobbin having a cylindrical portion whose one end is closed at both ends of the core are disposed, both ends of the core are provided with the high-pressure bobbin. And from the closed end of each low pressure bobbin is not exposed to the outside. That is, even when each terminal is provided in a portion close to the end side where each bobbin is blocked, a long creepage distance between the high voltage terminal and the low voltage terminal can be secured. There is no need to cover the surface of the core with an insulating film or the like to ensure the creepage distance or to prevent the core from being exposed by using an insulating material, etc., reducing the number of parts of the inverter transformer and reducing the manufacturing cost. can do.

  According to the invention of claim 2, since the high-pressure bobbin and the low-pressure bobbin can be attached to the core only by press-fitting into the core, the inverter transformer can be easily assembled, and the manufacturing cost of the inverter transformer can be further reduced. Can do.

  According to the invention of claim 3, by providing the separator on the high-pressure bobbin and the low-pressure bobbin whose one end of the cylindrical portion is closed, the creepage distance includes a path on the surface of the separator, and the creepage distance becomes long. Accordingly, the creepage distance can be more effectively secured while maintaining the size of the bobbin, and the inverter transformer can be further downsized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show an example of a so-called I-type inverter transformer (hereinafter referred to as a transformer) according to the present embodiment. The transformer 1 includes a low pressure bobbin 3 around which a low voltage coil 5 is wound and a high pressure bobbin 4 around which a high voltage coil 6 is wound around a core 2 that is a rod-shaped iron core formed using a ferromagnetic material. The high voltage coil 6 is magnetically coupled to the low voltage coil 5. From the low voltage bobbin 3 and the high voltage bobbin 4, a low voltage terminal 5a connected to the low voltage coil 5 and a high voltage terminal 6a connected to the high voltage coil 6 are exposed. The low-pressure bobbin 3 and the high-pressure bobbin 4 are each formed by integral molding using, for example, a resin.

  As shown in FIG. 2, a cylindrical portion 31 is formed on the low pressure bobbin 3. The cylindrical part 31 is formed in the size which can lightly press-fit the core 2, for example. The cylindrical portion 31 has an opening 32 provided at one end that serves as a pressure inlet of the core 2 and a sealing portion 33 that is blocked from opening at the other end of the cylindrical portion 31. Yes. In other words, one end portion of the cylindrical portion 31 of the low-pressure bobbin 3 is closed by providing the sealing portion 33, and the low-pressure bobbin 3 is formed in a bottomed cylindrical cap shape. At both ends of the low-pressure bobbin 3, flanges 34 are formed so as to project in a hook shape so that the low-voltage coil 5 is wound in a portion between them. As shown in FIG. 1, the low-voltage terminal 5 a is held by the flange 34 on the side where the sealing portion 33 is provided, of the two flanges 34.

  The structure of the high pressure bobbin 4 is substantially the same as that of the low pressure bobbin 3. That is, the high-pressure bobbin 4 is formed with a cylindrical portion 41 that is sized so that the core 2 can be lightly press-fitted. The cylindrical portion 41 has an opening 42 at one end and the other end. A sealing portion 43 that closes the tubular portion 41 is provided. The high pressure bobbin 4 is formed with two flange portions 44 formed in the same manner as the flange portion 34 of the low pressure bobbin 3, and a plurality of (for example, five) separators are provided between the two flange portions 44. 45 is formed. In the present embodiment, the separator 45 is formed so as to protrude like a bowl from a portion around which the high voltage coil 6 of the high voltage bobbin 4 is wound, like the flange 44. As shown in the figure, the high-voltage coil 6 has a predetermined number of turns at a portion of the high-pressure bobbin 4 between the separator 45 and the separator 45 adjacent thereto, or a portion between the flange portion 44 and the separator 45 adjacent thereto. It is wound. In the present embodiment, the high-voltage terminal 6a is provided at two locations, for example, the flange portion 44 on the side where the sealing portion 43 is provided and the separator 45 located at the center of the high-pressure bobbin 4, and the transformer 1 is configured to be able to output two-stage voltages having different heights.

  FIG. 3 shows a case where the low pressure bobbin 3 and the high pressure bobbin 4 are press-fitted into the transformer 1. The low-pressure bobbin 3 is press-fitted into the one end portion 2 a of the core 2 from the opening 32 and attached to the core 2. Further, the high-pressure bobbin 4 is press-fitted into the other end 2 b of the core 2 from the opening 42 and attached to the core 2. Since the cylindrical portions 31 and 41 are formed in a size that allows light press-fitting of the ends 2 a and 2 b of the core 2, the low-pressure bobbin 3 and the high-pressure bobbin 4 can be easily press-fitted into the core 2. Yes, without being detached from the core 2, it is reliably maintained in a state of being press-fitted into the core 2.

  In this transformer 1, since the low-pressure bobbin 3 and the high-pressure bobbin 4 are formed in a bottomed cylindrical cap shape, when the low-pressure bobbin 3 and the high-pressure bobbin 4 are respectively press-fitted into both ends 2a and 2b of the core 2, Both end portions 2 a and 2 b of the core 2 are not exposed to the outside of the transformer 1. Accordingly, since the core 2 has a conductive portion exposed and is regarded as a so-called floating metal portion, the creeping distance in the transformer 1 is from the low voltage terminal 5a to the high voltage terminal 6a closer to the low voltage terminal 5a. In the shortest path along the surface, the distance from the low voltage terminal 5a to the core 2 (the part indicated by the two-dot chain line X in FIG. 1) and the part from the core 2 to the high voltage terminal 6a (the two-dot chain line in FIG. 1). (The portion indicated by Y). Thereby, in this transformer 1, the creeping distance between the low voltage terminal 5a and the high voltage terminal 6a is longer than that of the transformer having a structure in which both end portions 2a and 2b of the core are exposed to the outside.

  Thus, in this embodiment, even when the low-voltage terminal 5a and the high-voltage terminal 6a are provided in portions close to the sealing portion 33 of the low-pressure bobbin 3 and the sealing portion 43 of the high-pressure bobbin 4, respectively. A long creepage distance can be secured. Since it is not necessary to cover the surface of the core 2 or to expose the core 2 by using an insulating material or the like in order to secure a creepage distance, the number of parts of the transformer 1 can be reduced, thereby reducing the manufacturing cost. be able to. Further, since the low-pressure bobbin 3 and the high-pressure bobbin 4 can be press-fitted into the core 2 and easily attached to the core 2, the transformer 1 can be easily assembled, and the manufacturing cost can be further reduced. Furthermore, the high-pressure bobbin 4 has a large number of separators 45, and the creepage distance is calculated by the length of a long path including the path on the surface of the separator 45. Thus, a long creepage distance can be secured more effectively, and the transformer 1 can be further downsized.

  In addition, this invention is not limited to the structure of the said embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. For example, the core is not limited to a rod-shaped core and may have a curved portion such as an L shape. Further, the number of separators may be more or less than the above, and may be provided on the low-pressure bobbin or on both bobbins. Furthermore, the inverter transformer may be used with a member that is provided near the core and that forms a closed magnetic circuit together with the core.

The top view which shows an example of the inverter transformer which concerns on one Embodiment of this invention. AA line sectional view in Drawing 1 of the above-mentioned inverter transformer. The figure which shows the time of the assembly of the said inverter transformer. The top view which shows an example of this conventional inverter transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter transformer 2 Core 2a, 2b (Core) edge 3 Low voltage bobbin 4 High voltage bobbin 5 Low voltage coil 5a Low voltage terminal 6 High voltage coil 6a High voltage terminal 31, 41 Cylindrical part 32, 42 Opening 33, 43 Sealing part (blocking) Stripped edge)
45 separator

Claims (3)

A rod-shaped core formed using a ferromagnetic material;
A low-pressure bobbin and a high-pressure bobbin that have a cylindrical part and are attached to the core so that the core is positioned in the cylindrical part;
A low pressure coil wound around the low pressure bobbin;
A high voltage coil wound around the high voltage bobbin and magnetically coupled to the low voltage coil;
An inverter transformer provided on each of the low-voltage bobbin and the high-voltage bobbin, each having a low-voltage terminal and a high-voltage terminal connected to the low-voltage coil and the high-voltage coil,
The low-pressure bobbin and the high-pressure bobbin are separate from each other and are molded by integral molding using a resin ,
Each of the cylindrical portions of the low-pressure bobbin and the high-pressure bobbin has an opening serving as a pressure inlet of the core at one end and a sealing portion closed so as not to open at the other end.
The both ends of the rod-shaped core are press-fitted from the openings of the cylindrical portions of the low-pressure bobbin and the high-pressure bobbin, respectively, and the both ends of the core are blocked by the cylindrical portions of the low-pressure bobbin and the high-pressure bobbin. An inverter transformer characterized in that it is not exposed to the outside by an end portion. 2. The inverter transformer according to claim 1, wherein a portion of the rod-shaped core where the low-pressure bobbin and the high-pressure bobbin are not press-fitted is exposed .   3. The inverter according to claim 1, wherein at least one of the low-pressure bobbin and the high-pressure bobbin includes a separator protruding in a bowl shape from the portion where the low-voltage coil or the high-voltage coil is wound. Trance.

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