JP2004297862A - Two-output inverter transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer a two-output inverter transformer where a magnetic flux little leaks to the outside of a transformer and besides the mounting area can be made small. <P>SOLUTION: This two-output inverter transformer is equipped with bobbins 10 and 20 which have an upper groove and a lower groove each around a spindle and where terminals are attached to two flanks each, cores 30 and 40 which have a center projection, two axes, and two outer feet each and where the center projection is arranged each between the two axes, and primary winding 60 and secondary winding 70a and 70b. The axis of the core 30 and the axis of the core 40 are inserted severally into the holes of the bobbins 10 and 20 from reverse direction, and the axes of the cores 30 and 40 and the center projections are counterposed to each other via air gaps, and besides the outer feet of the cores 30 and 40 are butted with each other to form a closed magnetic path. The primary winding 60 is wound astride from the upper groove 14 of the bobbin 10 to the upper groove 24 of the bobbin 20, and also the secondary winding 70a is wound in the lower groove 15 of the bobbin 10, and the secondary winding 70b is wound in the lower groove 25 of the bobbin 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inverter transformer used for an inverter device for lighting a discharge lamp, and more particularly to a magnetic leakage type two-output inverter transformer capable of taking out two outputs by one.
[0002]
[Prior art]
As this type of magnetic leakage type two-output inverter transformer, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. H11-163,972. This inverter transformer is provided with two secondary windings 2a and 2b electromagnetically coupled to one primary winding 1 as shown in FIG. 15, and the same output voltage can be obtained from each of the secondary windings 2a and 2b. It is like that. The use of this transformer when there are a plurality of discharge lamps has the advantage that the mounting area can be reduced as compared with the case where two one-output type transformers are used.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-126937
[Problems to be solved by the invention]
However, since the primary winding 1 and the two secondary windings 2a and 2b are arranged on the same plane, it is difficult to further reduce the mounting area. Further, as shown in FIG. 16, there is a problem that a large amount of magnetic leakage occurs outside the transformer due to the structure in which the side surface is opened. Arrows in FIG. 16 indicate the flow of magnetic flux passing through the pair of cores 3 and 4. Leakage magnetic flux to the outside of the transformer indicated by a broken line may adversely affect circuits around the transformer. SUMMARY OF THE INVENTION An object of the present invention is to provide a two-output inverter transformer capable of reducing the magnetic flux leakage to the outside of the transformer and further reducing the mounting area.
[0005]
[Means for Solving the Problems]
The two-output inverter transformer according to the present invention has bobbins 10, 20 having upper and lower grooves around a winding shaft having a vertical hole penetrating therethrough, and a plurality of terminals attached to two opposing side surfaces, Cores 30 and 40 having a central projection and two shaft cores and two outer legs projecting in the same direction from the plane portion, and having the central projection disposed between the two shaft cores; a primary winding 60; The two cores of the core 30 and the two cores of the core 40 are inserted into the holes of the bobbins 10 and 20 from opposite directions, respectively. The projections are opposed to each other with an air gap therebetween, and the outer legs of the cores 30 and 40 abut each other to form a closed magnetic path. The primary winding 60 is wound from the upper groove of the bobbin 10 to the upper groove of the bobbin 20. , The secondary winding 70a is wound around the lower groove of the bobbin 10. , And wherein the configuration of the secondary winding 70b wound in the lower groove of the bobbin 20.
[0006]
【Example】
One embodiment of a two-output inverter transformer according to the present invention is shown in FIGS. Two bobbins 10 and 20 having the same dimensions and insulating properties are fixed to the upper surface of the lower core 40. As shown in FIGS. 5 and 6, the bobbin 10 has an upper groove 14 and a lower groove 15 separated by a flange 13 around a cylindrical winding shaft 12 through which a vertical hole 11 passes. Are provided with a plurality of terminals 16 and 17, respectively. A slit 18 is formed at a position between the two terminals 17.
[0007]
A lead wire of a secondary winding, which will be described later, is drawn out below the bobbin 10 through the slit 18 and is connected to a connecting portion 17a (FIG. 5) integrated with the terminal 17. 2 and 4, the other bobbin 20 also includes a cylindrical winding shaft 22 through which a hole 21 penetrates, and an upper groove 24 and a lower groove 25 separated by a flange 23. Are provided with a plurality of terminals 26 and 27, respectively.
[0008]
Reference numerals 30 and 40 denote a pair of cores made of a magnetic material. As shown in FIG. 7, the lower core 40 includes a central projection 42 (42a, 42b, 42c) protruding upward from the plane portion 41, two shaft cores 43, 44, and two outer legs 45, 46. . The outer legs 45 and 46 are located at both ends of the flat portion 41, respectively, and the central projection 42 is provided at a position intermediate between the two shaft cores 43 and 44. The distal end surfaces of the central projection 42, the shaft cores 43 and 44, and the outer legs 45 and 46 are on the same plane. The central projection 42 of this embodiment has a shape in which notches 51 and 52 are provided at two locations of the projection extending over the full width of the core 40, and is divided into three portions 42a, 42b and 42c. ing.
[0009]
Similarly to the lower core 40, the upper core 30 also has a central projection 32 (32a, 32b, 32c) protruding downward from the plane portion 31, two shaft cores 33, 34, and two outer legs 35, 36, respectively. In place. Therefore, the upper core 30 and the lower core 40 of this embodiment can be molded using the same mold. As shown in FIG. 4, the upper core 30 and the lower core 40 form a closed magnetic circuit by abutting the outer legs 35 and 36 and the outer legs 45 and 46 with each other.
[0010]
As shown in FIG. 7, cutouts 48 for passing lead wires of the secondary winding are formed at two places on one side surface of the lower core 40. The notch 48 extends from the side surface of the lower core 40 to the shaft cores 43 and 44. In this embodiment, a similar notch 38 is provided in the upper core 30, but the notch 38 in the upper core 30 is not necessarily provided. As shown in FIG. 9, the upper core 30 may have a square planar portion 31 so that the upper surface can be easily sucked when mounted on a printed circuit board.
[0011]
The upper core 30 has a shaft 33 inserted into the hole 11 of the bobbin 10 and a shaft 34 inserted into the hole 21 of the bobbin 20 from above. The lower core 40 has a shaft 43 inserted into the hole 11 of the bobbin 10 and a shaft 44 inserted into the hole 21 of the bobbin 20 from below. The shaft cores 33, 34 and the central projection 32 of the upper core 30 are slightly polished from the flat portions 31 by polishing, for example, so that the protrusions from the flat portions 31 are smaller than those of the outer legs 35, 36. For this reason, the center projection 32 and the center projection 42, and the shaft cores 33 and 34 and the shaft cores 43 and 44 are opposed to each other via a gap.
[0012]
As shown in FIG. 4, a secondary winding 70 a is wound around the lower groove 15 of the bobbin 10, and its lead wire is connected to a terminal 17. A secondary winding 70b is wound around the lower groove 25 of the bobbin 20, and its lead wire is connected to the terminal 27. Further, the primary winding 60 is wound over the upper groove 14 of the bobbin 10 from the upper groove 24 of the bobbin 20, and the lead wires at both ends thereof are connected to the terminals 16 and 26, respectively. The primary winding 60 is wound through notches 51 and 52 which are discontinuous portions of the central projection 42. FIG. 10 shows a simplified winding state of the primary winding 60 at this time. The primary winding 60 is wound along the outer periphery of the two winding shafts 12 and 22 and a common tangent.
[0013]
The flow of the magnetic flux is as shown by the arrow in FIG. 8, and a two-output inverter transformer with little leakage of the magnetic flux to the outside of the transformer is obtained. The central protrusion 42 is located between the two secondary windings 70a and 70b, and has an effect of weakening electromagnetic coupling between the primary winding 60 and the secondary windings 70a and 70b. The two secondary windings 70a and 70b have the same number of turns, and are electromagnetically coupled to the primary winding 60 with the same degree of coupling. The winding operation of the primary winding 60 may be performed in a state where the bobbins 10 and 20 around which the secondary windings 70 a and 70 b are wound are fixed to the lower core 40.
[0014]
When the primary winding 60 is wound across the upper groove 14 of the bobbin 10 from the upper groove 14 of the bobbin 20, as shown in FIG. 11, only around the winding shaft 12 of the bobbin 10 and only the winding shaft 22 of the bobbin 20. A part of the primary winding 60 may be wound around the same number of times. When a portion wound around only the winding shaft 12 and only around the winding shaft 22 is added to a part of the primary winding 60, the degree of coupling between the primary winding 60 and the secondary windings 70a and 70b increases. Therefore, the coupling degree can be finely adjusted by changing the number of turns.
[0015]
FIG. 12 shows another embodiment of the winding method of the primary winding 60, in which the primary winding 60 is divided into two windings, that is, a thin line 60a and a thick line 60b. The primary winding 60a starts winding from the terminal 16a of the bobbin 10 and ends at the terminal 26a of the bobbin 20. The other primary winding 60b starts winding from the terminal 16b of the bobbin 10 and ends at the terminal 26b of the bobbin 20. That is, both primary windings 60a, 60b start at terminal 16 of bobbin 10 and end at terminal 26 of bobbin 20.
[0016]
FIG. 18 shows an example of an inverter circuit for lighting two discharge lamps 7 and 8 using a two-output type inverter transformer T. In the transformer of the present invention, the feedback winding 9 in the figure is wound from the upper groove 14 of the bobbin 10 to the upper groove 24 of the bobbin 20, similarly to the primary winding 60. Q1 and Q2 are switching transistors, R is a bias resistor, CC is a resonance capacitor, and an intermediate tap 61 of the primary winding 60 is connected to an input power supply via a choke coil L.
[0017]
The terminals 16b and 26a in FIG. 12 are connected by the conductor pattern of the printed board when the transformer is mounted on the printed board. This conductor pattern is used, for example, as an intermediate tap 61 of the primary winding 60 in the inverter circuit of FIG. Thereby, even when the lower core 40 or the upper core 30 having the central projection 42 between the terminal 16 and the terminal 26 as shown in FIG. 1 is used, it is possible to easily take out the intermediate tap 61 of the primary winding 60. it can.
[0018]
In the conventional intermediate tap 61, two lead wires 62 are connected to one terminal 6b as shown in FIG. In this case, when each lead wire 62 is connected to the terminals 6a, 6b, 6c by solder dip, the lead wire 62 of the intermediate tap 61 is compared with the lead wire 62 of one connection in the other terminals 6a, 6c. The insulating coating is not easily peeled off. For this reason, when the conditions of the temperature and the immersion time at the time of solder dip are adjusted to the intermediate tap 61, the lead wires 62 of the other terminals 6a and 6c become thinner and easily broken, and if the conditions are adjusted to the lead wires other than the intermediate tap 61. There is a disadvantage that the connection of the intermediate tap 61 is likely to be defective. With the connection method shown in FIG. 12, a plurality of lead wires are not connected to one terminal, so that a uniform solder dipping process can be performed.
[0019]
The central projection 32 may not be divided into a plurality, but may be formed as one as shown in FIG. The central projection 32 has a shape in which notches 51 and 52 are provided at both ends of a projection extending to the full width of the upper core 30. The primary winding 60 is wound by passing through the notches 51 and 52. The central projection 42 of the lower core 40 facing the central projection 32 is formed in a similar shape.
[0020]
Further, one of the upper core 30 and the lower core 40 may be formed in a flat plate shape. FIG. 14 shows an example in which the upper core 30 is a flat core. The central projections 42 (42a, 42b, 42c), the shaft cores 43, 44, and the outer legs 45, 46 protruding from the flat portion 41 are formed only on the lower core 40 side. In this case, assembling is performed by winding the secondary windings 70a and 70b and the primary winding 60 on the bobbins 10 and 20 fixed to the jig, and combining the two bobbins 10 and 20 by the primary winding 60. May be fitted to the lower core 40.
[0021]
【The invention's effect】
According to the present invention, a two-output inverter transformer having a small mounting area and a small amount of magnetic leakage to the outside can be obtained. Since the bobbin for the secondary winding is also used for the primary winding, the number of parts can be reduced, and the pair of cores can be formed by the same mold. Further, the solder dipping time of the terminal to which the lead wire of the primary winding is connected can be reduced, and a stable soldering state can be obtained. There is also an advantage that the degree of coupling between the primary winding and the secondary winding can be easily fine-tuned depending on how the primary winding is wound.
[Brief description of the drawings]
FIG. 1 is a plan view of an embodiment of a transformer according to the present invention, from which an upper core is removed. FIG. 2 is a partially exploded perspective view of the transformer. FIG. 3 is a plan view of the transformer. FIG. 5 is a perspective view of a bobbin of the transformer. FIG. 6 is a side sectional view of the bobbin. FIG. 7 is an exploded perspective view of a pair of cores in the transformer. FIG. 8 is a flow of magnetic flux in the transformer. FIG. 9 is a perspective view showing a modification of the upper core. FIG. 10 is a plan view showing a simplified first winding example of the primary winding. FIG. 11 is a second drawing of the primary winding. FIG. 12 is a plan view showing a simplified winding example of a primary winding. FIG. 13 is a plan view showing a simplified winding example of a primary winding. FIG. 13 is a perspective view showing another embodiment of a core. FIG. 15 is an exploded perspective view showing another embodiment of the core of FIG. 15. FIG. 16 is a plan view of a conventional two-output inverter transformer. Circuit diagram showing an example of a plan view and FIG. 18 inverter circuit of the lead wire connecting portion in the cross section Figure 17 the transformer showing the flow of the magnetic flux [Description of symbols]
10, 20 Bobbin 14, 24 Upper groove 15, 25 Lower groove 30, 40 Core 32, 42 Center protrusion 33, 34 Shaft core 43, 44 Shaft core 60 Primary winding 70a Secondary winding 70b Secondary winding

Claims (7)

First and second bobbins having an upper groove and a lower groove around a winding shaft through which a vertical hole penetrates, and a plurality of terminals attached to two opposing side surfaces, respectively;
A first and a second core having a flat portion, a central protrusion protruding in the same direction from the flat portion, two shaft cores, two outer legs, and a center protrusion disposed between the two shaft cores;
One primary winding,
With two secondary windings,
The two cores of the first core and the two cores of the second core are inserted into the holes of the first and second bobbins from opposite directions, respectively. The central projections are opposed to each other with a gap therebetween, and the outer legs of the first and second cores abut each other to form a closed magnetic path,
The primary winding is wound around the upper groove of the first bobbin from the upper groove of the second bobbin, and one secondary winding is wound around the lower groove of the first bobbin, and the other secondary winding is wound. Is wound around the lower groove of the second bobbin. 2. The two-output inverter transformer according to claim 1, wherein the central projection is provided with cutouts formed at two places of the protrusion extending to the full width of the core, and the primary winding is wound through the cutout. . 2. The two-output inverter transformer according to claim 1, wherein a part of the primary winding is wound the same number of times around only the winding axis of the first bobbin and only around the winding axis of the second bobbin. 2. The two-output inverter transformer according to claim 1, wherein the primary winding is divided into two, and each of the two primary windings starts from a terminal of the first bobbin and ends at a terminal of the second bobbin. The axial center of the first core, the central projection, and the respective distal end surfaces of the outer legs are on the same plane, and the axial center and the central projection of the second core have a smaller amount of protrusion from the flat portion than the outer legs. The two-output inverter transformer according to claim 1. First and second bobbins having an upper groove and a lower groove around a winding shaft through which a vertical hole penetrates, and a plurality of terminals attached to two opposing side surfaces, respectively;
A pair of cores having two shaft cores, a central projection provided between the two shaft cores, and outer legs formed at both ends, and abutting the outer leg portions;
One primary winding,
With two secondary windings,
The two cores of one core are inserted into the holes of the first and second bobbins, respectively, and the central projections of the two cores and the core are respectively opposed to the other core via the gaps, and The first and second cores are butted together to form a closed magnetic path,
A primary winding is wound over an upper groove of the first bobbin from an upper groove of the second bobbin, one secondary winding is wound around a lower groove of the first bobbin, and the other secondary winding is wound. Is wound around the lower groove of the second bobbin. 7. The two-output inverter transformer according to claim 6, wherein the other core is a flat core.

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