JP2008004780A - Transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and highly reliable transformer. <P>SOLUTION: A high-voltage transformer 100 includes: a core 5 having a pair of external magnetic legs 5a arranged to be mutually in parallel, and an internal magnetic leg 5b held between the pair of external magnetic legs 5a and arranged to be in parallel with the external magnetic legs 5a; a first bobbin with a first winding wire formed therein, which is mounted to cover one of the external magnetic legs; and a second bobbin with a second winding wire formed therein, which is mounted to cover the other external magnetic leg. The dimensions of the internal and external magnetic legs and the first and second bobbins are adjusted so as to allow the maximum height of the first and second bobbins to be substantially the same as that of the inner magnetic leg. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transformer including a plurality of output windings.

  A high voltage transformer is used in a lighting device for the backlight. In recent years, a double transformer type high-voltage transformer in which two transformer parts are integrated is proposed (for example, Patent Document 1).

JP-A-2005-311227

  In a double transformer type high voltage transformer in which two transformer parts are integrated, for example, a Japanese-shaped core having three magnetic legs (iron cores) arranged in parallel to each other is used. A bobbin with windings is arranged on the magnetic legs (referred to as outer magnetic legs) at both ends of the day-shaped core, and the magnetic flux passing through the outer magnetic legs is arranged between the two outer magnetic legs. It has a structure shared by magnetic legs (called inner magnetic legs). In such a transformer, since the cross-sectional area of the inner magnetic leg needs to be larger than the cross-sectional area of the outer magnetic leg, the outer dimension of the transformer becomes large. Therefore, there is a problem that the area and volume occupied by the high-voltage transformer on the substrate are limited.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a small and highly reliable transformer.

  In order to solve the above problems, the present invention provides a transformer including a plurality of output windings described below.

  A transformer according to the present invention includes a core having a pair of outer magnetic legs arranged in parallel to each other, and an inner magnetic leg arranged in parallel to the outer magnetic legs so as to be sandwiched between the pair of outer magnetic legs. A first bobbin that is formed so as to cover one of the pair of outer magnetic legs, and a second bobbin that is formed so as to cover the other of the pair of outer magnetic legs. And a second bobbin to be operated. The maximum height of the first and second bobbins and the height of the inner magnetic leg are configured to be substantially equal.

  According to the present invention, a compact and highly reliable transformer can be obtained.

  Embodiments of a high-voltage transformer and a discharge lamp lighting device using the same according to the present invention will be described below with reference to the drawings.

  1 is a schematic perspective view of a high-voltage transformer according to the present invention, FIG. 2 is a schematic exploded perspective view of the high-voltage transformer shown in FIG. 1, and FIG. 3 is a schematic cross-sectional view of the high-voltage transformer.

  The high-voltage transformer 100 is used for an inverter power source for simultaneously lighting two lamps (for example, a cold cathode tube and a hot cathode tube). For an input voltage of 10 [V] to 20 [V], A voltage of 1000 [V] to 2000 [V] can be output. As shown in the drawing, the high-voltage transformer 100 includes two bobbins 1 and two E-shaped cores 5. The bobbin 1 has a cylindrical hollow portion having a rectangular cross-sectional shape perpendicular to the longitudinal direction. A coil is formed by winding the low voltage winding 3 and the high voltage winding 4 around the outer periphery of the hollow portion. A plurality of terminals 2 are provided at the ends of the plate-like portions located at both ends of the bobbin 1. The start end and the end of each of the low voltage winding 3 and the high voltage winding 4 are connected to one of the plurality of terminals 2.

  As shown in FIG. 1, the E-shaped core 5 has three prismatic magnetic legs (iron cores) and has an E-shaped planar structure. In the present invention, the magnetic leg located at the center of the E-shaped core 5 is referred to as an inner magnetic leg 5B, and the two magnetic legs located outside thereof are referred to as outer magnetic legs 5A. The E-shaped core 5 has an inner magnetic leg 5B disposed between two outer magnetic legs 5A. The two outer magnetic legs 5A and the inner magnetic legs 5B are arranged in parallel with each other with a predetermined distance (insulation distance) therebetween.

  The E-shaped core 5 can be formed using a material such as ferrite, permalloy, sendust, or iron carbonyl, for example. Two outer magnetic legs 5A of the E-shaped core 5, an inner magnetic leg 5B, and a connecting portion for connecting them are integrally formed. However, in the present invention, the two outer magnetic legs 5A, the inner magnetic legs 5B, and the connecting portions connecting them may be configured as separate and independent components. For example, the two outer magnetic legs 5A are integrated. The inner magnetic leg 5B can be configured as a separate part.

  In the example shown in FIGS. 1 and 2, two E-shaped cores 5 are used as a set, and the end of the outer magnetic leg 5A of one core 5 and the end of the outer magnetic leg 5A of the other core 5 are bobbins. They are combined so as to face each other inside the hollow portion. That is, two E-shaped cores 5 are inserted from both ends of the hollow portion of the bobbin 1 so as to face each other. Here, two E-shaped cores 5 are combined to form an EE core, but an E-shaped core 5 and an I-shaped core may be combined to be used as an EI core. In this case, the length of the three magnetic legs (5A and 5B) of the E-shaped core 5 is formed so as to be at least longer than the length of the hollow portion where the winding portion of the bobbin 1 is formed. What is necessary is just to comprise so that a leg may penetrate a hollow part.

  As shown in FIG. 3, the E-shaped core 5 is configured such that the thickness of the outer magnetic leg 5A and the thickness (height) of the inner magnetic leg 5B are different from each other. However, it is thicker than the outer magnetic leg 5A. Thus, by making the thickness of the inner magnetic leg 5B thicker than that of the outer magnetic leg 5A, the lateral width of the E-shaped core 5 (the width of the entire core in the direction in which the three magnetic legs are arranged) Since the thickness of 5A and the inner magnetic leg 5B can be made narrower than the case where it is the same, a high voltage transformer can be made smaller than before.

  In the example shown in FIG. 3, the cross-sectional area of the inner magnetic leg 5B of the core 5 is almost twice the cross-sectional area of the outer magnetic leg 5A. The cross-sectional area of the inner magnetic leg 5B is preferably in the range of 1.7 times to 2.4 times the cross-sectional area of the outer magnetic leg 5A. In the present invention, the thickness (height) of the inner magnetic leg 5B is maintained while maintaining the cross-sectional area of the inner magnetic leg 5B within the range of 1.7 times to 2.4 times the cross-sectional area of the outer magnetic leg 5A. The outer magnetic leg 5A and the inner magnetic leg 5B are preferably configured to be substantially equal to or less than the maximum thickness (height) of the bobbin 1. Thereby, the overall height or width of the high-voltage transformer can be minimized.

  Further, in a conventional high-voltage transformer in which the inner magnetic leg 5B and the outer magnetic leg 5A of the core have the same height, it is conceivable to reduce the bobbin as a method for realizing miniaturization, but if the bobbin is reduced in size, There was a risk of a decrease in dielectric strength and a decrease in bobbin strength. In the present invention, since the dimensions of the inner magnetic leg 5B and the outer magnetic leg 5A of the core are adjusted, it is possible to reduce the size of the high-voltage transformer while ensuring the same dielectric strength without changing the size of the bobbin. it can.

  In the example shown in FIG. 3, the cross-sectional shape of the inner magnetic leg 5B of the E-shaped core 5 is formed in a substantially square shape, and the cross-sectional shape of the outer magnetic leg 5A is formed in a rectangular shape. Are configured to be thicker than the thickness of the outer magnetic leg 5A, the cross-sectional shapes of the outer magnetic leg 5A and the inner magnetic leg 5B are not limited. The cross-sectional shape of the magnetic leg 5A may be substantially square. Further, the cross-sectional shapes of the outer magnetic leg 5A and the inner magnetic leg 5B may be formed in a shape such as a circle or an ellipse.

  Further, as shown in the high-voltage transformer 101 in FIG. 4, the inner magnetic legs 5B and the outer magnetic legs 5A of the core 5 can be formed so that the cross-sectional shapes thereof are rectangles that are long in the height direction. In this case, the thickness (height) of the inner magnetic leg 5B is maintained while maintaining the cross-sectional area of the inner magnetic leg 5B within the range of 1.7 times to 2.4 times the cross-sectional area of the outer magnetic leg 5A. It is set to be approximately equal to or less than the maximum value of the thickness (height) of the bobbin 1. As a result, a small high-voltage transformer with a narrow width can be obtained.

  Further, if the inner magnetic leg 5B and the outer magnetic leg 5A are formed so that the cross-sectional shape is a rectangle that is long in the width direction, a thin and small high-voltage transformer can be obtained. In the present invention, the cross-sectional shape and dimensions of the core can be appropriately set in accordance with the use of the high-voltage transformer and the required substrate occupation area or substrate occupation volume of the high-voltage transformer.

  1-4, the low-voltage windings of the bobbin 1 inserted in the two outer magnetic legs 5A so that the directions of the magnetic fluxes inside the two outer magnetic legs 5A of the core 5 are the same. The line 3 is wound in the same direction. A voltage is applied to the low-voltage winding 3 in parallel with each other, and two lamps are simultaneously discharged and lit by the output from the high-voltage winding 4.

  In the high-voltage transformer according to the present embodiment, when the high-voltage windings 4 formed on the two bobbins are connected in parallel to drive the two lamps independently of each other, the high-voltage windings of the two bobbins respectively. It is preferable to make the winding directions of the same. In addition, the end of the high-voltage winding of one bobbin is connected to one end of a U-shaped cold cathode tube driven at high voltage, and the other bobbin is connected to the other end of the U-shaped cold cathode tube. When the terminations of the high voltage windings are connected so that the terminations are in opposite phases, the winding directions of the high voltage windings of the respective bobbins may be reversed.

  As described above, a small high-voltage transformer can be realized by adjusting the dimensions of the inner magnetic leg, the outer magnetic leg, and the bobbin so that the maximum bobbin height and the inner magnetic leg height are substantially equal. Can do.

  The high voltage transformer according to the present invention has been described in detail above. Such a high voltage transformer of the present invention is used for an inverter power source of a liquid crystal display device, for example. 5 and 6 are a block diagram of an inverter power source 500 using a high-voltage transformer and a block diagram of a liquid crystal display device 600 including the inverter power source 500, respectively.

  As shown in FIG. 5, an inverter power source 500 is a power source for lighting a cold cathode tube of a backlight unit, and includes a transformer 100 according to the present invention, a drive circuit 510 for driving the transformer 100, and a drive thereof. And a control circuit 520 for controlling the circuit 510. The control circuit 520 can detect the output of the high voltage transformer 100 and control the drive circuit 510.

  As shown in FIG. 6, the liquid crystal display device 600 includes a signal circuit 610, a liquid crystal panel 620, a backlight unit 630, an inverter power supply 500, and a control circuit 640. The video signal input to the signal circuit 610 is subjected to signal processing in the signal circuit 610 and then output to the liquid crystal panel 620. The inverter power source 500 is connected to the backlight unit 630, and an input voltage or the like is controlled by the control circuit 640 to light the cold cathode tube of the backlight unit 630.

  The embodiments of the high-voltage transformer according to the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various improvements and modifications are made without departing from the gist of the present invention. be able to.

  In the above embodiment, the high voltage transformer with the input voltage of 10 [V] to 20 [V] and the output voltage of 1000 [V] to 2000 [V] has been described as an example. However, the present invention is not limited to this, It can be applied to various input voltage and output voltage transformers.

1 is a schematic perspective view of a high-voltage transformer according to the present invention. 1 is a schematic exploded perspective view of a high-voltage transformer according to the present invention. It is a schematic sectional drawing of the high voltage | pressure transformer according to this invention. It is a schematic sectional drawing of the modification of the high voltage | pressure transformer according to this invention. It is a block diagram of the inverter power supply using the high voltage | pressure transformer according to this invention. It is a block diagram of a liquid crystal display device provided with the inverter power supply shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bobbin, 2 ... Terminal, 3 ... Low voltage winding, 4 ... High voltage winding, 5 ... E-shaped core, 5A ... Outer magnetic leg, 5B ... Inner magnetic leg, 100 ... High voltage transformer, 101 ... High voltage transformer, 500 ... Inverter power supply, 510 ... drive circuit, 520 ... control circuit, 600 ... liquid crystal display device, 610 ... signal circuit, 620 ... liquid crystal panel, 630 ... backlight unit, 640 ... control circuit

Claims (3)

A transformer comprising a plurality of output windings,
A core having a pair of outer magnetic legs arranged in parallel to each other and an inner magnetic leg arranged in parallel to the outer magnetic legs so as to be sandwiched between the pair of outer magnetic legs;
A first bobbin formed with a first winding and mounted to cover one of the pair of outer magnetic legs;
A second winding is formed, and has a second bobbin mounted to cover the other of the pair of outer magnetic legs,
A transformer in which the maximum height of the first and second bobbins is substantially equal to the height of the inner magnetic leg. The transformer according to claim 1, wherein a cross-sectional area of the inner magnetic leg is in a range of 1.7 times to 2.4 times a cross-sectional area of the outer magnetic leg. The transformer according to claim 1 or 2, wherein the core includes two E-shaped cores.

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