JP4586249B2 - Step-up transformer and electric apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a step-up transformer and an electric device using the step-up transformer, for example, a step-up transformer used in an inverter for lighting a discharge lamp for a backlight of a liquid crystal display, and an electric device using the step-up transformer.
[0002]
[Prior art]
With the spread of liquid crystal displays in recent years, the thinning of displays is accelerating, and there is an increasing demand for thinning an inverter for lighting a discharge lamp for a backlight and a step-up transformer used therefor.
[0003]
FIG. 7 shows an exploded perspective view of a conventional thin step-up transformer. The basic structure of the step-up transformer shown in FIG. 7 is disclosed in Japanese Patent Laid-Open No. 8-153634.
[0004]
In FIG. 7, the step-up transformer 1 includes a bobbin 2 and core members 10, 11, and 12. First, the bobbin 2 has a cylindrical portion 3, extension portions 4, 5 provided on the mounting surface side (downward in FIG. 7) of the cylindrical portion 3 and extending on both sides in the longitudinal direction, and the extension portion 4. 5 and the pin bases 6 and 7 provided so that the mounting surface side is flush with the extensions 4 and 5 respectively, and the pin terminals 8 and 9 respectively planted on the pin bases 6 and 7. ing. Here, the pin bases 6 and 7 are formed so that the thickness from the mounting surface side is thicker than that of the extension portions 4 and 5 so that the pin terminals 8 and 9 can be implanted. Although not shown, at least a primary winding and a secondary winding are wound around the cylindrical portion 3 of the bobbin 2, and the end of the primary winding is connected to the pin terminal 8 and the end of the secondary winding. Are connected to pin terminals 9, respectively.
[0005]
Then, the core member 10 is inserted into the hole 3 a of the cylindrical portion 3 of the bobbin 2 from the side where the extension portion 5 and the pin base 7 are provided. Furthermore, the two core members 11 and 12 are arrange | positioned so that the cylindrical part 3 and the core member 10 inserted there from both sides of the cylindrical part 3 may be pinched | interposed. As a result, a magnetic path is formed by the three core members 10, 11, and 12.
[0006]
In the step-up transformer 1 configured as described above, the thickness of the pin bases 6 and 7 from the mounting surface side is formed to be thicker than the extension portions 4 and 5, so that the pin base has a thickness on the mounting surface side and the bobbin. Therefore, the step-up transformer can be made thinner.
[0007]
[Problems to be solved by the invention]
However, the step-up transformer 1 shown in FIG. 7 requires three or at least two types of core members for the three core members 11, 12, and 13, which increases the number of parts and hinders cost reduction. There is a problem of becoming. In addition, when the number of parts is large, it takes time to assemble, and there is a problem that it also hinders the reduction of manufacturing costs.
[0008]
The present invention aims to solve the above-described problems, and provides a step-up transformer capable of reducing the number of parts and manufacturing cost as well as reducing the thickness and an electric device using the step-up transformer.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a step-up transformer according to the present invention has first, second, and third magnetic legs arranged in parallel in order, and one end of each of the first, second, and third magnetic legs. The first and second core members are connected to each other via a connecting portion, and the other end of one magnetic leg is directed to the other connecting portion with the first and second core members facing in opposite directions. And a primary winding and a secondary winding are wound around the core, and the second magnetic legs of the first and second core members are both disposed so as to pass therethrough. A bobbin having a cylindrical portion, and the bobbin extends in the longitudinal direction on the mounting surface side of the cylindrical portion, and the mounting surface side extends continuously from the extension portion. A pin pedestal provided to be flush with the portion, and the thickness of the pin pedestal is extended. It is formed to be thicker and thinner than the thickness obtained by adding the second magnetic leg and the extension of the core member disposed on the mounting surface side of the first and second core members, and further, the extension of the bobbin A groove through which the lead wire of the secondary winding passes is provided on the mounting surface side of the portion, and the groove through which the lead wire at the end of the secondary coil that has a high voltage passes is the extension portion. The first or second core member disposed in contact with the first or second core member is formed at a position facing a gap between the first or third magnetic leg and the second magnetic leg. To do.
[0010]
The step-up transformer according to the present invention is characterized in that a spacer is provided between the first and second core members.
[0011]
The step-up transformer according to the present invention is characterized in that the first and third magnetic legs are thicker than the second magnetic legs.
[0014]
In addition, an electrical device of the present invention is characterized by using any of the step-up transformers described above.
[0015]
With this configuration, the step-up transformer of the present invention can be reduced in thickness, size, and cost.
[0016]
In addition, the electric device of the present invention can be reduced in thickness, size, and cost.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a perspective view of an embodiment of the step-up transformer of the present invention. FIG. 2 shows an exploded perspective view thereof. 1 and 2, the step-up transformer 20 includes a bobbin 21, a first core member 29 and a second core member 30 having the same shape. First, the bobbin 21 has a cylindrical portion 22, extension portions 23 and 24 provided on the mounting surface side (downward in FIG. 1) of the cylindrical portion 22 on both sides in the longitudinal direction, and the extension portion 23. , 24 and the pin bases 25, 26 provided on the mounting surface side flush with the extension portions 23, 24, and pin terminals 27, 28 respectively planted on the pin bases 25, 26. ing. Here, the pin pedestals 25 and 26 are formed so that the thickness from the mounting surface side is thicker than that of the extension portions 23 and 24 so that the pin terminals 27 and 28 can be implanted. Although not shown, at least a primary winding and a secondary winding are wound around the cylindrical portion 22 of the bobbin 21, and the end of the primary winding is connected to the pin terminal 27 and the end of the secondary winding. Are connected to pin terminals 28, respectively.
[0018]
Next, in the first core member 29, the first magnetic leg 29a, the second magnetic leg 29b, and the third magnetic leg 29c are arranged in parallel in order, and one end of the first core leg 29 is connected via the connecting portion 29d. They are connected to each other. Here, the first magnetic leg 29a and the third magnetic leg 29c are narrower and slightly thicker than the second magnetic leg 29b, and the first magnetic leg 29a and the third magnetic leg 29c The sum of the cross-sectional areas substantially matches the cross-sectional area of the second magnetic leg 29b. Similarly, in the second core member 30, the first magnetic leg 30a, the second magnetic leg 30b, and the third magnetic leg 30c are arranged in parallel in order, and one end of the second core member 30 is connected to the connecting part 30d. Are connected to each other. The width, thickness, and cross-sectional area of each magnetic leg of the second core member 30 are also formed in the same manner as the first core member 29.
[0019]
Next, how to assemble the step-up transformer 20 will be described. First, the first core member 29 is positioned on the extension portions 23 and 24 after the second magnetic leg 29b is inserted through the hole 22a of the cylindrical portion 22 of the bobbin 21 from the pin terminal 27 side and penetrated. To do. Next, the second core member 30 is inserted through the hole 22a of the cylindrical portion 22 of the bobbin 21 from the pin terminal 28 side, and then passed through the second core member 30. Position to. As a result, the first core member 20 and the second core member 30 are opposite to each other and overlap so that the other end of one magnetic leg is adjacent to the other connecting portion. A core is configured. Finally, the step-up transformer shown in FIG. 1 is formed by fixing the first core member 29 and the second core member 30 to the bobbin 21 with an adhesive or the like.
[0020]
By configuring in this way, the number of core members in the step-up transformer 20 can be two, and the two core members can have the same shape. As a result, the assembly work is facilitated and the manufacturing cost can be reduced. Moreover, since the number of parts can be reduced, cost reduction can be achieved.
[0021]
In addition, since the first magnetic leg and the third magnetic leg of the first and second core members are thicker than the second magnetic leg, the width of the first magnetic leg and the third magnetic leg is increased. Can be made shorter than the width of the second magnetic leg. As a result, the width of the step-up transformer itself can be prevented from being increased by preventing the width of the first magnetic leg or the second magnetic leg from being too large and the width of the step-up transformer itself from increasing.
[0022]
Here, FIG. 3 shows a side view of the step-up transformer 20. In FIG. 3, the primary winding 31 and the secondary winding 32 which are omitted in FIGS. 1 and 2 are shown. Here, the thickness of the extension parts 23 and 24 of the bobbin 21 is a, the thickness of the pin bases 25 and 26 is b, and the thickness of the second magnetic legs 29b and 30b of the first and second core members 29 and 30 is c. It is said.
[0023]
As shown in FIG. 3, the pin bases 25 and 26 are formed flush with the extensions 23 and 24 on the mounting surface side, and do not protrude from the surfaces of the extensions 23 and 24. And the thickness b from the mounting surface side of the pin bases 25 and 26 is thicker than the thickness a of the extension parts 23 and 24, and the 1st core member 29 arrange | positioned at the thickness a of the extension parts 23 and 24 and the mounting surface side. The thickness of the second magnetic leg 29b is less than the thickness obtained by adding the thickness c. For this reason, first, the thickness of the step-up transformer does not increase due to the thickness of the pin base, and the step-up transformer can be made thinner. Further, the pin bases 25 and 26 do not hinder the insertion of the first and second first and second core members 29 and 30 into the holes 22a of the cylindrical portion 22 of the bobbin 21. That is, when the second magnetic leg 29b is inserted into the hole 22a, the height of the opening viewed from the pin terminal 27 side of the hole 22a is the height of two of the second magnetic legs 29b of the original core member. With respect to (c + c), the pin pedestals 25 and 26 are reduced by the amount (ba) protruding from the extension portions 23 and 24, but still remain because of the relationship c> ba. The height (c + c− (ba)) is larger than c, and the second magnetic leg 29b of the first core member 29 can be smoothly inserted into the hole 22a. Even after the first core member 29 is positioned at a predetermined position, the hole 22a has a gap for inserting the second magnetic leg 30b of the second core member 30 when viewed from the pin terminal 28 side. Thus, the second core member 30 can also be smoothly inserted and positioned.
[0024]
Note that if the thickness of the second magnetic leg of the core member is selected so as to have such a relationship, the thickness of the second magnetic leg of the first core member and the second core member does not necessarily match. It does not matter.
[0025]
FIG. 4 is a bottom view of the step-up transformer 20. FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4 also shows the primary winding 31 and the secondary winding 32 that are omitted in FIGS. 1 and 2.
[0026]
As shown in FIG. 4, a primary winding 31 is wound around the tubular terminal 22 of the bobbin 21 on the pin terminal 27 side, and a secondary winding 32 is wound on the pin terminal 28 side. Since a large current with a low voltage flows through the primary winding 31, a thick wire is used although the number of windings is small. A small current with a high voltage flows through the secondary winding 32, so there are many windings. Thin wire rod is used. Grooves 23a and 24a for passing the lead wires of the primary winding 31 and the secondary winding 32 are provided on the mounting surface side of the extensions 23 and 24 of the bobbin 21, respectively. The two end portions 31a of the primary winding 31 are drawn out through the groove 23a and connected to the pin terminal 27, and the one end portion 32a of the secondary winding 32 is drawn out through the groove 24a to be the pin terminal. 28, and the other end 32 b is pulled out through the groove 23 a and connected to the pin terminal 27.
[0027]
The bobbin 21 is wound with a feedback winding 33 through which a relatively small current flows in addition to the primary winding 31 and the secondary winding 32, and its end 33 a is connected to the pin terminal 27. Since it is not the main part of this invention, description is abbreviate | omitted.
[0028]
Next, the relationship between the end 32a of the secondary winding 32 and the first and second core members 29 and 30 will be described with reference to FIG. In FIG. 5, only the cut surface is shown, and other parts are omitted. Further, the size of the end portion 32a of the secondary winding 32 passing through the groove 24a is exaggerated for easy understanding.
[0029]
As shown in FIG. 5, a groove 24a is provided on the mounting surface side of the extension 24, and the end 32a of the secondary winding 32 passes through the groove 24a. Near the end of the first magnetic leg 29a, the second magnetic leg 29b, and the third magnetic leg 29c of the first core member 29 are in contact with the side of the extension 24 opposite to the mounting surface side. Yes. There is a gap 29g between the first magnetic leg 29a and the second magnetic leg 29b, and between the second magnetic leg 29b and the third magnetic leg 29c. For this reason, the groove 24 a is formed at a position facing the gap 29 g of the first core member 29. The first core member 29 is adjacent to the connecting portion 30 d of the second core member 30.
[0030]
By making the positional relationship between the groove 24a of the extension part 24 and the first core member 29 and the second core member 30 in this way, among the parts constituting the first and second core members 29, 30, The portion closest to the groove 24 a becomes the gap 29 g of the first core member 29. This is because, for example, compared with the case where the groove 24a is formed at a position facing one of the magnetic legs of the core member 29, one end 32a of the secondary winding 32 passing through the groove 24a and the first core This means that the distance between the member 29 and the second core member 30 is increased.
[0031]
Since the secondary winding 32 starts to be wound from the other end portion 32b, the other end portion 32b becomes substantially the ground voltage, and the one end portion 32a becomes the high voltage. That is, the highest voltage in the secondary winding 32 is generated at one end portion 32a, and the first core member 29 and the second core member 30 are substantially at ground potential. However, when the relationship between the end 32a of the secondary winding 32 and the first and second core members 29 and 30 is configured in this manner, the distance between the two is widened and the generation of corona discharge occurs. Can be prevented. In order to prevent corona discharge, the thickness of the extension portion is increased, or another insulating material is provided between the extension portion and the end of the secondary winding to make the secondary winding 32 the first winding. Since there is no need to separate (increase the insulation distance) from the core member 29, the step-up transformer can be reduced in thickness and cost.
[0032]
In the step-up transformer 20 shown in FIG. 1 to FIG. 5, the first core member 29 and the second core member 30 are directly overlapped to form a core. A spacer made of an insulator such as resin or paper may be provided between the legs, and the same effect as that of the step-up transformer 20 can be achieved. In addition, the inductance value of the core can be adjusted by providing a spacer between the two core members and further changing the material and thickness thereof. Of course, in that case, it is necessary to increase the height of the bobbin hole by the thickness of the spacer, and as a result, the thickness of the pin base can be increased by the thickness of the spacer.
[0033]
In the above embodiment, the thickness of the first and third magnetic legs of the core member is larger than the thickness of the second magnetic leg. However, the thickness of all the magnetic legs may be equal. In that case, the thickness of the second magnetic leg of the core member is the thickness of the core member.
[0034]
FIG. 6 shows a partially transparent perspective view of one embodiment of the electric apparatus of the present invention. In FIG. 6, a liquid crystal display 40 that is an electric device includes a housing 41, a liquid crystal display unit 42 disposed on the front surface of the housing 41, a stand 43 that supports the housing 41, and a backlight of the liquid crystal display unit 42. A discharge tube 44 serving as a light source and an inverter 45 that generates an AC voltage for driving the discharge tube 44 are provided. The inverter 45 uses the step-up transformer 20 of the present invention.
[0035]
In the liquid crystal display 40 configured as described above, the inverter 45 can be reduced in thickness, size, and cost by using the step-up transformer 20 of the present invention. As a result, the liquid crystal display 40 itself can be reduced in thickness, size, and cost.
[0036]
In FIG. 6, a liquid crystal display is shown as an electric device. However, the present invention is not limited to this, and another electric device such as a notebook computer with a liquid crystal display may be used. The electric device used in the above may be the same and has the same effect.
[0037]
【The invention's effect】
According to the step-up transformer of the present invention, the first, second, and third magnetic legs are arranged in parallel in order, and the first and second cores are connected to each other through the connecting portion. The core is formed by stacking the members in opposite directions so that the other end of one magnetic leg is adjacent to the other connecting portion, and the primary winding and the secondary winding are wound. By providing a bobbin having a cylindrical portion through which the second magnetic legs of the first and second core members are disposed, the thickness is reduced and the cost is reduced by reducing the number of parts. Can do.
[0038]
Further, by providing a spacer between the first and second core members, the inductance value of the core can be changed.
[0039]
Further, by making the first and third magnetic legs thicker than the second magnetic legs, the width of the core member can be narrowed and the step-up transformer can be downsized.
[0040]
Also, the step-up transformer can be made thinner by forming the pin pedestal from the mounting surface side thicker than the extension, and thinner than the total thickness of the extension and the core member disposed on the mounting surface. .
[0041]
Also, a groove through which the lead wire of the secondary winding passes is provided on the mounting surface side of the bobbin extension, and the groove is connected to the first or third magnetic leg of the core member arranged in contact with the extension. By forming it at a position facing the gap between the two magnetic legs, corona discharge can be prevented and the step-up transformer can be made thinner.
[0042]
According to the electric device of the present invention, it is possible to reduce the thickness, size and cost by using the step-up transformer of the present invention.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a step-up transformer according to the present invention.
FIG. 2 is an exploded perspective view showing the step-up transformer of FIG.
3 is a side view showing the step-up transformer of FIG. 1. FIG.
4 is a bottom view showing the step-up transformer of FIG. 1. FIG.
5 is a cross-sectional view taken along line AA in FIG.
FIG. 6 is a perspective view showing an embodiment of the electric apparatus according to the present invention.
FIG. 7 is an exploded perspective view showing a conventional step-up transformer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Boost transformer 21 ... Bobbin 22 ... Cylindrical part 22a ... Hole 23, 24 ... Extension part 23a, 24a ... Groove 25, 26 ... Pin base 27, 28 ... Pin terminal 29 ... 1st core member 30 ... 2nd Core member 29a, 30a ... 1st magnetic leg 29b, 30b ... 2nd magnetic leg 29c, 30c ... 3rd magnetic leg 29d, 30d ... Connection part 29g ... Air gap 31 ... Primary winding 32 ... Secondary winding 33 ... Tertiary winding 31a, 32a, 33a ... End 40 ... Liquid crystal display

Claims (4)

The first, second, and third magnetic legs are arranged in parallel in order, and the first, second, and third magnetic legs are connected to each other via a connecting portion. A core composed of two core members, the first and second core members facing each other in opposite directions, and the other end of one magnetic leg being adjacent to the other coupling portion;
A bobbin having a cylindrical portion in which a primary winding and a secondary winding are wound, and the second magnetic legs of the first and second core members are both disposed therethrough ,
The bobbin includes an extension portion provided in the longitudinal direction on the mounting surface side of the cylindrical portion, and a pin base provided on the mounting surface side flush with the extension portion continuously from the extension portion. Have
The pin base is formed thicker than the extension, and thinner than the thickness of the first magnetic core and the second magnetic leg of the core member arranged on the mounting surface side of the first and second core members. And
Furthermore, the mounting surface side of the extension part of the bobbin is provided with a groove for passing the lead wire of the secondary winding,
Of the grooves, the groove through which the lead wire at the end of the secondary winding that is at a high voltage passes is the first or second core member disposed in contact with the extension. A step-up transformer, which is formed at a position facing a gap between the third magnetic leg and the second magnetic leg .   The step-up transformer according to claim 1, wherein a spacer is provided between the first and second core members.   3. The step-up transformer according to claim 1, wherein the first and third magnetic legs are thicker than the second magnetic legs. An electric device using the step-up transformer according to any one of claims 1 to 3.

Images