JP2006332277A - Current balancing transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of components, a mounting area, and a cost by enabling to balance the currents in three or more loads by a transformer component of a unitary construction. <P>SOLUTION: The transformer consists of coils wound around individual winding frames of a bobbin and a magnetic core which are combined together using the bobbin 20 having a plurality of winding frames on the identical winding axis. The bobbin has two or more winding regions divided by at least one magnetic core assembling groove formed in the intermediate portion. The winding regions each have two winding frames. The two coils of the respective winding frames which are opposite from each other with the magnetic core assembling groove in-between are so wound as to be continuous with each other. Since the magnetic core is so arranged that the coil of each winding region may form a closed magnetic circuit, each winding region forms one balancer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multi-output transformer for balancing a load current. More specifically, the present invention has two or more winding regions each having two winding frames, and adjacent winding regions The coils of two winding frames facing each other are wound in a continuous manner, and a magnetic core is provided so that the coils in each winding region form a closed magnetic circuit, thereby forming one balancer in each winding region. The present invention relates to a current balance transformer. This current balance transformer is useful for lighting circuits such as many cold cathode fluorescent lamps and light emitting diode groups.

  In a liquid crystal panel of a notebook personal computer or a small liquid crystal monitor, usually one or two cold cathode tubes are used as a backlight. However, three or more cold-cathode tubes are used as backlights in large-sized liquid crystal televisions and liquid crystal monitors that have recently become popular. In the backlight, it is important to illuminate the entire panel as uniformly as possible. Therefore, it is necessary to supply current to each cold cathode tube as uniformly as possible.

  In the past, as many inverter circuits as the number of cold-cathode tubes were installed, and each cold-cathode tube was driven independently to control the current. However, this configuration is not a big problem when the number of cold cathode tubes is small like the liquid crystal panel of a small liquid crystal monitor, but when the number of cold cathode tubes is large like a large liquid crystal television or a liquid crystal monitor. In addition, a large number of inverter circuits are required, and it is difficult to reduce the size of the inverter circuit.

Therefore, as shown in FIG. 1, a load current balancing device has been developed in which a balancer 14 is connected between the inverter circuit 10 and the cold cathode tubes 12 to evenly distribute the currents flowing through the cold cathode tubes. In this case, in the prior art, two identical balancers 14 are used for three loads (cold cathode tubes 12). Each balancer 14 is a two-output current balance transformer having a structure in which a bobbin having two winding frames on the same winding axis is used and a coil wound around both winding frames of the bobbin and a magnetic core are combined. . One coil of the first balancer and one coil of the second balancer are connected in series on the substrate, and the current I ₁ flowing through the first cold cathode tube and the second cold cathode tube are connected by the first balancer. The flowing current I ₂ is balanced, and the current I ₂ flowing through the _second cold cathode tube and the current I ₃ flowing through the third cold cathode tube are balanced by the second balancer. Thereby, finally, the currents I _{1 to} I ₃ flowing through all the cold cathode tubes 12 can be equally distributed. Such a technique is disclosed in Patent Document 1.

Such a load current balancing apparatus has an advantage that the number of parts such as a control circuit and an inverter transformer can be greatly reduced because the number of inverter circuits can be reduced. However, the number of cold cathode tubes used for the backlight is increasing due to the increase in the size of the liquid crystal screen. Therefore, in the two-output balancer system as described above, (N−1) balancers are required for N cold cathode tubes. As a result, the circuit board design becomes more complicated as the liquid crystal panel becomes larger, and the mounting area and cost of the balancer cannot be ignored.
JP-A-6-269125

  The problem to be solved by the present invention is that it is possible to balance the currents flowing through three or more loads even though it is a single-structure transformer component, thereby reducing the number of components, the mounting area, and the cost. It is to plan.

  The present invention uses a bobbin having a plurality of winding frames on the same winding axis, and in a transformer in which a coil wound around each winding frame of the bobbin and a magnetic core are combined. There are two or more winding regions divided by the magnetic core incorporating groove, each winding region has two winding frames, and the coils of the two winding frames facing each other across the magnetic core incorporating groove are The current balancing transformer is characterized by being wound continuously and provided with a magnetic core so that the coils in each winding region form a closed magnetic circuit, and one balancer is formed in each winding region.

  Here, the simplest form of the bobbin is a structure having two winding regions divided by one magnetic core incorporating groove in the middle portion. In this case, for example, the magnetic core is formed of a combination of an E core and an I core, the I core passes through the bobbin winding shaft, and the inner leg of the E core is fitted into the magnetic core incorporation groove of the bobbin. . Alternatively, the magnetic core may be a combination of a U core and an I core, the I core may pass through the bobbin winding shaft, and one leg of both U cores may be accommodated in the bobbin magnetic core incorporating groove. The magnetic core is a combination of an I core and a Japanese character core. The I core passes through the bobbin winding shaft, and the intermediate bridge portion of the Japanese character core fits into the magnetic core incorporation groove of the bobbin. It may be a structure. In addition, the magnetic core is composed of a combination of an E core and an I core, the I core is fitted into the magnetic core incorporation groove of the bobbin, and the inner leg of the E core is inserted into the bobbin winding shaft. It may be a combination of a core and an I core, and the I core may be fitted into the magnetic core incorporation groove of the bobbin, and one leg of the U core may be inserted into the bobbin winding shaft. Each of these structures is a three-output type.

  In addition, the bobbin has a structure having three or more winding regions divided by two or more magnetic core incorporation grooves in the middle portion, and the magnetic core has two outer legs and two or more inner legs with respect to the back plate. Is a combination of two multi-leg cores with a structure projecting in the same direction and an I core, the I core penetrates the bobbin winding shaft, and the inner leg fits into the magnetic core built-in groove of the bobbin. You may make it. This structure can handle multiple outputs of 4 outputs or more.

  Alternatively, the bobbin has a structure having three winding regions divided by two magnetic core incorporation grooves in the middle portion, and the magnetic core is composed of a combination of an I core and an eye-shaped core, and the I core is a bobbin. The intermediate bridging portion of the eye-shaped core may be fitted into the magnetic core incorporation groove of the bobbin. This structure can cope with four outputs, and if the number of magnetic core built-in grooves and intermediate bridges is increased, it can also cope with more outputs.

  In the present invention, the load of the current balance transformer includes a cold cathode tube or a light emitting diode group. One or more current balancing transformers as described above are incorporated in the lighting circuit, the output of the inverter circuit is divided into three or more outputs, and each output is turned on as a cold cathode tube serving as a load or a number of light emitting diodes connected in series. .

  The current balancing transformer according to the present invention can balance the current flowing through many loads even though it is a single transformer component. By using such a current balance transformer, the circuit board design of the lighting circuit can be simplified, and the mounting area of components and the cost can be reduced. More specifically, for example, in order to balance currents with respect to three loads, the conventional technique requires two balancers, but in the present invention, only one balancer is required. It is. The material cost can be reduced because the number of bobbins and cores can be reduced, the time for installing the bobbin in the winding machine can be shortened, and the cost in the manufacturing process can be reduced.

  FIG. 2 is an explanatory view showing an embodiment of a current balancing transformer according to the present invention, in which A represents a plane and B represents a side surface. This current balancing transformer balances the current supplied to three loads (cold cathode tube etc.), and uses a bobbin 20 in which four winding frames are arranged in parallel on the same winding axis. In this structure, the coil 22 and the magnetic core 24 wound around each of the 20 winding frames are combined.

  3A and 3B are explanatory views of the coil. A shows a state where the coil is wound around the bobbin from the bottom side, and B shows the side surface of the bobbin. The bobbin 20 has two winding regions P and Q that are divided by one central magnetic core incorporating groove, and each of the winding regions P and Q includes two winding frames. One winding region is formed by three flanges 27 projecting outward from the winding shaft 26. In addition, two rectangular parallelepiped terminal blocks 28 are provided at both ends of the winding shaft 26, and a single rectangular parallelepiped terminal block 29 is provided between the two winding regions. Is formed with a winding through groove 29a. The winding shaft 26, the flange 27, and the terminal blocks 28 and 29 are integrally formed products. In addition, the gap where the flange faces above the central terminal block 29 is a magnetic core incorporation groove. One terminal 30 is provided at each end of each terminal block 28, 29. Although the bobbin is a surface mount type here, it goes without saying that it may be a pin type.

  Winding is applied to each of the four winding frames partitioned by the flange 27, and the terminals of the outer two coils p1 and q2 are tangled to terminals 30 located at both ends of the terminal block 28, respectively, and soldered. Connected by attaching. The inner two coils p2 and q1 are wound so as to be continuous through the winding through groove 29a of the central terminal block 29, and the terminals are connected to the terminals 30 located at both ends of the terminal block 29 by soldering or the like. Is done. A winding diagram is shown in FIG. For example, each coil p1, p2, q1, q2 is 410 turns. The number of turns is set as appropriate according to the required inductance and frequency characteristics.

  FIG. 5 shows a state where the magnetic core is incorporated in such a bobbin. The magnetic core is composed of a combination of one I core 32 and two E cores 34. The I core 32 is inserted through the winding shaft of the bobbin 20, and the E core 34 is combined from both sides. At this time, the inner legs of the E core 34 are fitted into the magnetic core incorporation grooves, and the legs are combined so that the front end surfaces of the legs abut the side faces of the I core 32. As a result, the coils of the winding regions P and Q each have a closed magnetic circuit, and a balancer is formed.

Such a current balance transformer is incorporated in the lighting device as shown in FIG. The output of the inverter circuit 10 is supplied to the current balance transformer 40 via the inverter transformer 11, and the three outputs drive the cold cathode tube 12, respectively. The inside of the dotted line represents the current balance transformer 40. The magnetic path at this time is shown in FIG. The two E cores 34 opposite to the I core 32 form a magnetic circuit that forms two closed magnetic paths surrounding the winding regions P and Q on both sides, as shown by the dotted lines in FIG. The current flowing through the coils p1 and p2 is balanced by the magnetic circuit passing through the coils p1 and p2 in the line region, and the current flowing through the coils q1 and q2 is balanced by the magnetic circuit passing through the coils q1 and q2 in the other winding region. As a result, the currents I _{1 to} I ₃ (see FIG. 6) flowing through the three cold cathode tubes connected to the current balance transformer of the present invention are uniform.

  A conventional lighting device shown in FIG. 1 in which two balancers with two outputs are arranged and a lighting device (FIG. 6) using a current balanced transformer with three outputs according to the present invention are prototyped. The current flowing through CFL 1 to 3) was measured. The measurement results are shown in Table 1. From Table 1, it was confirmed that the variation of the tube current was equivalent to the conventional configuration of the product of the present invention.

  FIG. 8 is an explanatory view showing another embodiment of the current balancing transformer according to the present invention. A is an example in which one winding frame is further divided into a plurality by the auxiliary flange 50. In addition to the structure shown in FIG. 3, the bobbin 20 has a structure in which one winding frame is further provided with an auxiliary flange 50, and the magnetic core is a combination of an I core 32 and an E core 34. By increasing the number of divisions in this way, the stray capacitance of each coil can be reduced and the self-resonant frequency of the current balanced transformer can be increased. B is a structure in which two rectangular parallelepiped cores 52 are connected as I cores 32 via a gap sheet 54, and is assembled so that the gap sheet 54 is positioned exactly in the magnetic core incorporation groove. The bobbin 20 may have the same structure as that shown in FIG. By arranging the gap sheet 54 in this way, the influence of the magnetic coupling between the coils p1-p2 and the coils q1-q2 can be reduced.

  FIG. 9 is an explanatory view showing still another embodiment of the current balancing transformer according to the present invention. In the example shown in A, the bobbin has the same structure as that shown in FIG. 3, and the magnetic core consists of a combination of the U core 56 and the I core 32. A represents the front. Then, the I core 32 passes through the winding axis of the bobbin 20, and one leg of both the U cores 56 is aligned and is assembled so as to be accommodated in the magnetic core incorporation groove of the bobbin 20. In the example shown in B, the bobbin has the same structure as the auxiliary flange 50 shown in A of FIG. 8, and the magnetic core consists of a combination of an I core 32 and a Japanese-shaped core 58. B represents a plane. Then, the I core 32 is assembled so that it passes through the bobbin winding shaft, and the intermediate bridging portion 58 a of the sun-shaped core 58 is fitted in the magnetic core incorporation groove of the bobbin 20.

  FIG. 10 is an explanatory view showing another embodiment of the current balance transformer according to the present invention. The bobbin 20 may have the same structure as that shown in FIG. A shows a plane, and B shows a state in which a magnetic core is incorporated in a bobbin. The magnetic core is composed of a combination of the E core 60 and the I core 62, but the combination is different from each of the embodiments described above. In this embodiment, the I core 62 is fitted into the magnetic core incorporation groove of the bobbin 20, and the inner leg of the E core 60 is assembled to be inserted into the winding shaft of the bobbin 20 from both sides. The front end surface of each leg of the E core 60 contacts the side surface of the I core 62.

  FIG. 11 is an explanatory view showing another embodiment of the current balance transformer according to the present invention. Each of the bobbins 20 may have the same structure as that shown in FIG. The example shown in A is a structure in which two plate-like cores 66 are bonded as I cores 64 via a gap sheet 68. Combined with the I core 64 is the same E core 60 as shown in FIG. A represents a plane. Also in this example, the I core 64 is fitted into the magnetic core incorporation groove of the bobbin 20, and the inner leg of the E core 60 is assembled to be inserted into the winding shaft of the bobbin 20. By arranging the gap sheet 68 in this way, it is possible to reduce the influence of magnetic coupling between the coil in one winding region and the coil in the other winding region. In the example shown in B, the magnetic core is composed of a combination of a U core 70 and an I core 72. The I core 72 is fitted into the magnetic core incorporation groove of the bobbin 20, and one leg of the U core 70 is inserted into the winding shaft of the bobbin 20 from both sides. B represents the front.

  FIG. 12 is an explanatory view showing another embodiment of the current balance transformer according to the present invention. Here, the bobbin 82 has a structure having three winding regions divided by two magnetic core incorporation grooves in the middle part. Each winding region has two winding frames, and coils p1, p2, q1, q2, r1, and r2 are wound on a total of six winding frames, respectively. A winding diagram is shown in FIG. Here, the coils p2 and q1 are continuous, and the coils q2 and r1 are continuous. In the example shown in A, the magnetic core is composed of a combination of two 4-leg cores 84 having a structure in which two outer legs and two inner legs protrude in the same direction with respect to the back plate, and an I core 86. The I core 86 passes through the winding shaft of the bobbin 82 and the inner leg of the quadruped core 84 is fitted in the magnetic core incorporation groove of the bobbin 82. In the example shown in B, the magnetic core is composed of a combination of an I core and an eye-shaped core 88. The I core penetrates the winding axis of the bobbin 82, and the intermediate bridge portion of the eye-shaped core 88 is fitted in the magnetic core incorporation groove of the bobbin. In such a configuration, it is possible to balance currents to four loads (such as cold cathode tubes) with one current balancing transformer.

FIG. 14 shows another example of the lighting device using the current balance transformer according to the present invention. In this example, six cold cathode tubes 12 are driven. The output of the inverter 10 is supplied to a two-output balancer 90 via an inverter transformer 11, and both outputs of the balancer 90 are supplied to two current balancing transformers 92 to drive a total of six cold cathode tubes 12. The current balancing transformer 92 balances the current flowing through the first cold cathode tube and the current flowing through the second cold cathode tube with the coil in one winding region, and the second winding region with the coil in the second winding region. The current flowing through the cold cathode tube and the current flowing through the third cold cathode tube are balanced. The same applies to the other current balancing transformer 92. As a result, the currents I _{1 to} I ₆ flowing through the six cold cathode tubes 12 are balanced.

  In the above embodiment, a cold cathode tube is shown as a load, but it is not limited thereto. The present invention can be applied to an LED lighting device of a light emitting diode group in which a number of light emitting diodes (LEDs) are connected in series.

  If the load current varies due to variations in the capacitance components of the entire liquid crystal panel, line drawing, or the like, it is possible to adjust the number of turns of individual windings so as to eliminate the variation.

Explanatory drawing of the lighting device using the conventional balancer. Explanatory drawing which shows one Example of the current balance transformer which concerns on this invention. Explanatory drawing of the coil. The winding diagram. Explanatory drawing of the state which incorporates a magnetic core in a bobbin. Explanatory drawing of the lighting device incorporating the current balance transformer of this invention. Explanatory drawing of the magnetic path in the current balance transformer of this invention. Explanatory drawing which shows the other Example of the current balance transformer which concerns on this invention. Explanatory drawing which shows the further another Example of the current balance transformer which concerns on this invention. Explanatory drawing which shows the other Example of the current balance transformer which concerns on this invention. Explanatory drawing which shows the other Example of the current balance transformer which concerns on this invention. Explanatory drawing which shows the further another Example of the current balance transformer which concerns on this invention. The winding diagram. Explanatory drawing which shows the other Example of the lighting device incorporating the current balance transformer.

Explanation of symbols

20 Bobbin 22 Coil 24 Magnetic core 26 Core 27 Flange 28, 29 Terminal block 30 Terminal 32 I core 34 E core P, Q Winding area

Claims (10)

In a transformer using a bobbin having a plurality of winding frames on the same winding axis and combining a coil and a magnetic core wound around each winding frame of the bobbin,
The bobbin has two or more winding regions divided by one or more magnetic core incorporation grooves in the middle portion, and each winding region has two winding frames, and is opposed to each other with the magnetic core incorporation groove interposed therebetween. The coils of the two winding frames are wound continuously so that a magnetic core is provided so that the coils of each winding region form a closed magnetic circuit, and one balancer is formed in each winding region. Characteristic current balance transformer.   The bobbin has a structure having two winding regions divided by a magnetic core incorporating groove in one intermediate portion, and the magnetic core is a combination of an E core and an I core, and the I core penetrates the bobbin winding axis. The current balance transformer according to claim 1, wherein an inner leg of the E core is fitted into a magnetic core built-in groove of the bobbin.   The bobbin has a structure having two winding regions divided by a magnetic core incorporating groove at one location in the middle, and the magnetic core is a combination of a U core and an I core, and the I core penetrates the bobbin winding axis. The current balancing transformer according to claim 1, wherein one leg of both U cores is accommodated in a magnetic core incorporation groove of the bobbin.   The bobbin has a structure having two winding regions divided by a magnetic core incorporating groove at one location in the middle part, and the magnetic core is composed of a combination of an I core and a Japanese character core, and the I core is a bobbin winding. 2. A current balancing transformer according to claim 1, wherein the current bridge transformer penetrates the shaft and the intermediate bridge portion of the sun-shaped core is fitted in the magnetic core incorporation groove of the bobbin.   The bobbin has a structure having two winding regions divided by one magnetic core incorporating groove in the middle portion. The magnetic core is a combination of an E core and an I core, and the I core is a core incorporating groove of the bobbin. The current balancing transformer according to claim 1, wherein the inner legs of the E core are inserted into a bobbin winding shaft.   The bobbin has a structure having two winding regions divided by one magnetic core incorporating groove in the middle portion, and the magnetic core is a combination of a U core and an I core, and the I core is a core incorporating groove of the bobbin. The current balancing transformer according to claim 1, wherein the current balance transformer is fitted and one leg of both U cores is inserted into a winding shaft of the bobbin.   The bobbin has a structure having three or more winding regions divided by two or more magnetic core incorporation grooves in the middle portion, and the magnetic core has two outer legs and two or more inner legs with respect to the back plate. It consists of a combination of two multi-leg cores with a structure projecting in the same direction and an I core. The I core penetrates the bobbin winding shaft, and the inner leg of the multi-leg core fits into the magnetic core built-in groove of the bobbin. The current balance transformer according to claim 1, wherein   The bobbin has a structure having three winding regions divided by two magnetic core built-in grooves in the middle portion, and the magnetic core is formed of a combination of an I core and an eye-shaped core, and the I core is a bobbin winding. 2. The current balancing transformer according to claim 1, wherein the intermediate bridge portion of the eye-shaped core is fitted into the magnetic core incorporation groove of the bobbin through the shaft.   A cold cathode tube comprising one or more current balancing transformers according to any one of claims 1 to 8, wherein the output of the inverter circuit is divided into three or more outputs, and a cold cathode tube serving as a load is lit at each output. Cathode tube lighting circuit. One or more current balancing transformers according to any one of claims 1 to 8 are incorporated, the output of the inverter circuit is divided into three or more outputs, and a number of light emitting diodes connected in series as loads are lit at each output. LED lighting circuit.

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