JP2006049460A - Inverter transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain improvement in insulating performance and increase in high-voltage performance with respect to the structure of an inverter transformer used in order to turn on a cold cathode fluorescence pipe for the backlight of a liquid crystal display. <P>SOLUTION: In a bobbin 10, a primary winding section 11 and a secondary winding section 12 are formed in the ends side, respectively, and a leakage 13 is arranged in the medium of those sections. If two or more slits constitute the secondary winding section of a bobbin by a flange, it can improve the breakdown voltage between lines. an I type core 14 is inserted into the hollow section of the bobbin 10, and an E type core 15 is arranged at an upside. The leg of the ends of an I type core 15 and the ends of E type core are connected so as to form a magnetic loop. The middle leg of an E type core 16 is extended to the direction of a leakage 13 which is the magnetic flux leakage section of the I type core, and it is arranged so that it may counter with the I type core 15 with a predetermined gap. In order to control this gap, it is preferable to arrange a spacer between the leg of the ends of the E type core and the I type core. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of an inverter transformer used for lighting a cold cathode fluorescent tube for a backlight of a liquid crystal display device, and relates to a so-called horizontal transformer structure.

  An inverter transformer is used to obtain a boosted voltage for lighting a cold cathode fluorescent tube or the like. A general inverter transformer has a horizontal winding structure. As shown in FIG. 3, a primary winding and a secondary winding are wound around a bobbin, and a core inserted in a hollow portion of the bobbin and a core disposed around the core are magnetized. The circuit is configured to be a high coupling type.

  The problem with this transformer is that an overcurrent flows during a rare short. In addition, since the coupling is high, the output voltage is determined in proportion to the input voltage. Therefore, it is necessary to control the voltage when the lamp is opened and when the lamp is lit using a ballast capacitor or a voltage control circuit.

In addition, a structure called vertical winding as shown in FIG. 4 is adopted, and a leakage magnetic flux control gap is provided between the primary side and secondary side windings to reduce current during a short circuit. It is planned. In addition, voltage control when the lamp is opened and when the lamp is lit can be performed using the leakage flux of the transformer. However, because of the structure, in order to increase the output of high voltage, it is necessary to improve the withstand voltage, and it is necessary to increase the bottom area.
JP-A-10-5592 Japanese Patent Laid-Open No. 11-3298 JP 2000-3818 JP 2003-68540 A

  In order to cope with the increase in the screen size of liquid crystal display devices, the number of lamps has increased and the mounting density of components has also increased. In addition, high voltage inverter transformers are required for large panels, and it is necessary to develop inverter transformers that meet the requirements for improved insulation, higher voltage, and smaller size. An object of the present invention is mainly to improve insulation and increase the voltage.

  The present invention adopts a horizontal winding structure that facilitates the use of slit winding in order to improve insulation, and controls leakage magnetic flux between the primary side winding and the secondary side winding performed in the vertical winding. By adopting a structure in which a gap is arranged, leakage inductance is generated and stability is improved, thereby solving the above-described problem.

  That is, in an inverter transformer having a primary winding on one end of the bobbin, a secondary winding on the other end, an I-type core in the hollow part of the bobbin, and an E-type core that forms a magnetic circuit with the I-type core. The both ends of the I-type core and the legs of the E-type core are close to each other to form a magnetic circuit, and face the middle leg of the E-type core between the primary and secondary windings. It is characterized by having a magnetic flux leakage part.

The present invention not only solves the main problems described above, but also has the following effects.
(1) Since the secondary high voltage portion can be divided, a sufficient line-to-line breakdown voltage can be obtained.
(2) Increasing the number of slits (number of divisions) facilitates high voltage handling
(3) Since there is a gap for controlling leakage magnetic flux, it can be used for both self-excited and separately excited circuits.
(4) Since it has an elongated structure and a wide transformer interval can be obtained in the case of multiple lamps, it is advantageous in terms of inter-transformer interference, insulation distance, and heat dissipation.
(5) A minimum mounting area can be realized if the E-type core is arranged on the upper surface, and a low profile can be realized if it is arranged on the side surface.
(6) When the output is multi, reverse phase output is also possible by changing the winding direction of the secondary winding.

The basic configuration of the inverter transformer according to the present invention is as follows.
(1) Bobbin: The secondary side may be divided into a plurality of slits.
(2) Primary winding (3) Secondary winding (4) Magnetic flux leakage part (gap): Part where no winding exists between primary winding and secondary winding (5) I-type core (6) E-type core: The middle leg part faces the magnetic flux leakage part.

    Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an embodiment of the present invention. The winding portion is omitted. In the bobbin 10, a primary winding portion 11 and a secondary winding portion 12 are formed on both ends, respectively, and a leakage portion 13 is disposed between them. In this example, the leakage portion 13 has a structure in which a part of the bobbin is removed. In this example, the secondary winding portion of the bobbin has five slits formed by flanges, and the secondary winding is divided to improve the line withstand voltage.

  An I-type core 15 is inserted into the hollow portion of the bobbin 10, and an E-type core 16 is disposed on the upper side. Both ends of the I-type core 15 and the leg portions at both ends of the E-type core are connected to form a magnetic loop. An intermediate leg portion of the E-type core 16 extends in the direction of the leakage portion 13 which is a magnetic flux leakage portion of the I-type core, and is disposed so as to face the I-type core 15 with a predetermined interval. In order to control this distance, it is desirable to arrange spacers between the leg portions at both ends of the E-type core and the I-type core. If it does so, a space | interval can be made into a desired value with a spacer. By generating the leakage magnetic flux by the leakage portion 13, not only the voltage but also a self-excited oscillation circuit can be realized.

  The position of the E-type core may be the upper surface or the side surface, and if it is the upper surface, the mounting area can be reduced, and if it is the side surface, a low-profile structure is possible. Further, the bobbin of the leakage portion does not need to be provided with an opening for exposing the core, and may be a bobbin having no winding. Of course, it is necessary to avoid the direct contact between the E-type core and the I-type core at the leakage portion.

  FIG. 2 is a plan view and a front view showing an example of a so-called multi-structure. In the bobbins 20 and 30, a primary winding portion and a secondary winding portion are formed on both ends, respectively, and a leakage portion is disposed between them. In this example, the leakage portion has a structure in which a part of the bobbin is removed. In this example, the secondary winding portion of the bobbin has five slits formed by flanges, and the secondary winding is divided to improve the line withstand voltage. Each bobbin and core are the same as in FIG. The E-type core is arranged on the upper surface. In this multi-structure, a reverse phase output can be obtained by reversing the winding direction of the primary winding and the secondary winding.

  The present invention can be used for an inverter transformer or the like for lighting a cold cathode fluorescent tube used for a backlight of a liquid crystal display device.

Front view showing an embodiment of the present invention Plan view and front view showing another embodiment of the present invention A perspective view showing a conventional inverter transformer Front sectional view showing another conventional inverter transformer

Explanation of symbols

10: Bobbin
11: Primary winding
12: Secondary winding part
13: Leakage section
15: Type I core
16: E type core

Claims (5)

In an inverter transformer with a primary winding on one end of the bobbin and a secondary winding on the other end,
An inverter transformer comprising a magnetic flux leakage portion between a primary winding and a secondary winding. In an inverter transformer comprising a primary winding on one end of the bobbin, a secondary winding on the other end, an I-type core in the hollow part of the bobbin, and an E-type core that forms a magnetic circuit with the I-type core.
Magnetic flux that forms the magnetic circuit with both ends of the I-type core and both ends of the E-type core in close proximity, and faces the middle leg of the E-type core between the primary and secondary windings An inverter transformer characterized by having a leaking portion.   The inverter transformer according to claim 2, wherein spacers are disposed between both leg portions of the E-type core and both end portions of the I-type core.   The inverter transformer according to claim 2, wherein an opening is formed in a bobbin of the magnetic flux leakage portion. Each bobbin arranged in parallel has a primary winding on one end, a secondary winding on the other end, and an I-type core in the hollow part of each bobbin, and constitutes a magnetic circuit together with the I-type core. In inverter transformers with E-type cores,
The both ends of each I-type core and the legs of both ends of the E-type core are close to each other to form a magnetic circuit, and the middle leg of the E-type core is between each primary and secondary winding. An inverter transformer characterized by comprising a magnetic flux leakage part opposite to.

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