JP2007208228A - Compound winding transformer and lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a compound winding transformer with easy circuit design and a lamp lighting device with a small variation in luminance by avoiding a heat concentration on a plurality of the winding transformers and specific transformers and facilitating the matching of characteristics caused by a magnetic flux distribution. <P>SOLUTION: There is provided a compound winding transformer 7 characterized by being provided with a plurality of winding transformers 7a and 7b and a covering member 13 integrating the plurality of winding transformers 7a and 7b, which have cores 8, primary windings 9 and secondary windings 10 formed in the cores 8, and terminal electrodes 11 electrically connected with the primary windings 9 and the secondary windings 10. There is also provided a lamp lighting device mounted with the same. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a winding transformer used in a backlight drive circuit of a liquid crystal television and a lamp lighting device using the transformer.

  In recent years, an apparatus using a liquid crystal panel as a display device such as a personal computer, a mobile phone, and a liquid crystal television has been increasing. Since the liquid crystal panel itself does not emit light, a backlight is required. In order to drive the backlight of the liquid crystal panel, a lamp lighting device having an inverter circuit is used.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2003-309023, a lamp lighting device used for driving a backlight switches a voltage applied to a primary winding of a transformer by a switching element, and uses a secondary winding of the transformer. The voltage is boosted, and the boosted voltage is applied to the cold cathode tube to light up. In such a lamp lighting device, usually one transformer is provided for each switching circuit. However, if there is a demand for high power, such as a liquid crystal television, one switching circuit 3 is used as shown in FIG. In some cases, small transformers 5 and 6 are used in combination to reduce the load per unit. The circuit of FIG. 1 is called a full bridge type, and is a type in which a larger voltage is generated when the two inverter circuits 1 and 2 generate voltages having phases opposite to each other.

JP 2003-309023 A

  When multiple transformers are used together as described above, it becomes difficult to achieve thermal balance of each transformer, such as due to variations in characteristics such as coupling coefficient of each transformer and heat concentration on a specific transformer depending on the mounting position on the board. There was a problem. Further, since the magnetic flux distribution is different due to variations in the mounting positions of the transformers, it is difficult to match the characteristics of the transformers, and there is a problem in that the brightness of the lamps to be lit varies.

  The present invention solves such problems and proposes a winding transformer with easy circuit design and a lamp lighting device with little variation in luminance.

  The present invention is electrically connected to a core, a bobbin into which the core is inserted, a primary winding and a secondary winding wound around the bobbin, and the primary winding and the secondary winding. A composite winding transformer comprising a plurality of winding transformers having a terminal electrode and a plurality of winding transformers integrated with a covering member is proposed.

  According to the present invention, since the heat generated from each transformer is transmitted through the covering member and the entire heat distribution becomes uniform, the heat concentration on the specific transformer is eliminated, and it is easy to achieve the thermal balance of each transformer. . In addition, since the mounting position of each transformer is fixed, characteristic imbalance due to magnetic flux distribution is eliminated. Such an effect is that the winding axis direction is parallel to the mounting surface, the primary winding and the secondary winding are surrounded by the outer frame formed by the core in the lateral direction, and the terminal electrode is the winding axis. This is particularly effective in a winding transformer having a structure arranged in the direction end.

  Examples of the covering member used in the present invention include a case and a resin mold. In addition to the resin case, for example, a metal case using a nonmagnetic metal such as aluminum can be used as the case. Cases such as resin cases and metal cases have good thermal conductivity and a high heat dissipation effect. Since the resin mold seals the winding portion, the dielectric strength between the lines can be improved.

  Moreover, the shielding effect which suppresses the leakage magnetic flux from a trans | transformer can be acquired by disperse | distributing a magnetic body to resin which forms a resin case, or resin for molding. In the case of a resin case and a metal case, a magnetic material may be coated on the case. In the case of a resin mold, in order not to affect the magnetic characteristics of the transformer, at least the winding part is coated with a resin that does not contain a magnetic material, and then a resin in which the magnetic material is dispersed is coated thereon. Also good. As the magnetic material, a ferrite material such as Ni—Zn or Ni—Zn—Cu can be used.

  In addition, the present invention proposes a lamp lighting device in which the above composite winding transformer is mounted. In this case, the integrated composite winding transformer may be mounted such that each secondary winding is connected in parallel to the same lamp.

  According to the present invention, heat concentration can be reduced and characteristic imbalance due to magnetic flux distribution can be eliminated. Therefore, a winding transformer with easy circuit design and a lamp lighting device with little variation in luminance can be obtained.

  An embodiment of a composite winding transformer and a lamp lighting device according to the present invention will be described with reference to the following drawings.

  A first embodiment of a composite winding transformer according to the present invention will be described with reference to FIG. First, as shown in FIG. 2A, a plurality (two in this case) of winding transformers 7a and 7b are prepared. In the winding transformers 7a and 7b, the middle leg of the EE type core 8 is inserted into the bobbin 12, and the primary winding 9 and the secondary winding 10 are formed on the bobbin 12 in different regions of the bobbin 12, respectively. It is electrically connected to the terminal electrode 11 (not shown) provided in the opposing surface of the terminal electrode 11 and the terminal electrode 11 which arranged the end part of the line | wire so that it might protrude in the end part of the winding axis direction, Is a thin winding transformer having a structure in which the core is parallel to the mounting surface, the core forms the outer frame of the winding, and there is no core in the vertical direction and the lateral direction is surrounded by the core. Here, one end of the primary winding and the secondary winding is connected to the terminal electrode 11, and the winding end that becomes the high voltage of the secondary winding is connected to the terminal on the opposite surface of the terminal electrode 11. Connected. Subsequently, as shown in FIG. 2B, the winding transformers 7a and 7b are arranged side by side so that the side surfaces in the direction orthogonal to the winding direction, that is, the surfaces where the terminal electrodes 11 are not formed are directed toward each other. Although the winding transformers are in close contact with each other in the drawing, they may be arranged at a predetermined interval. Next, as shown in FIG. 2C, the winding transformers 7 a and 7 b are covered with a resin mold 13 and integrated to form the composite winding transformer 7. Examples of the resin to be molded include epoxy resins. Since the composite winding transformer 7 obtained in this way can propagate heat from each transformer through the resin mold and make the heat distribution uniform, it is easy to achieve thermal equilibrium.

  A second embodiment of the composite winding transformer according to the present invention will be described with reference to FIGS. In this embodiment, in FIG. 2C, a resin mold 13 mixed with a magnetic material such as ferrite powder is used. In this case, as shown in FIG. 3, it is preferable that the winding portion 15 is covered with a resin 16 that does not include a magnetic material, and is covered with a resin 17 that includes a magnetic material including the core 14 from above. As a result, the insulation between the wires of the winding portion is improved, and a magnetic shield can be applied without affecting the magnetic characteristics of the transformer.

  Next, a third embodiment of the composite winding transformer according to the present invention will be described with reference to FIGS. In FIG. 4, two winding transformers are covered with a case 18. In this case, the case 18 may be directly covered with a transformer, or may be covered with a resin mold. As the case, for example, an epoxy resin, a polyimide resin, a diallyl phthalate resin, a phenol resin, an aramid resin, or the like formed into a case shape can be used for a resin case. Can be used. Further, it is possible to provide a magnetic shield by using a resin case formed of a resin containing a magnetic body, a resin case coated with a magnetic body, or a metal case.

  FIG. 5 shows a case in which a window is formed in a part of the case to improve heat dissipation. In FIG. 5, a window is formed in a portion related to the primary winding 9, but the size, position, etc. of the window can be set as appropriate.

  In the first to third embodiments of the composite winding transformer according to the present invention, an example using an EE type core has been described. However, a UU type or UI type core as shown in FIG. Even if it is used, it is possible to form the composite winding transformer 7 ′ by applying the embodiment of the present invention as in the case of the EE type core as shown in FIG. 6B.

  Next, an embodiment of a lamp lighting device according to the present invention will be described with reference to FIG. The lamp lighting device is formed by mounting other electronic components such as the composite winding transformer 7 and the switching circuit 3. The primary winding of the composite winding transformer is connected to the switching circuit 3 side, and the secondary winding is connected to the lamp 4 side.

  In the present embodiment, since the composite winding transformer 7 in which a plurality of winding transformers are integrated is mounted, it is easy to achieve thermal balance and consistency of characteristics, so that the driving voltage is stable and there is little variation in luminance. A lamp lighting device can be obtained. In the case of integrating a plurality of winding transformers, as shown in FIG. 7, the secondary windings are mounted in parallel (the primary windings may be in series or in parallel) and individual winding transformers are mounted. It can also be connected in parallel to the same lamp.

It is a circuit diagram which shows a lamp lighting device and a lamp. It is a figure which shows 1st embodiment of the composite winding transformer which concerns on this invention, (a) is the figure which prepared two winding transformers, (b) is the figure which made two winding transformers adjoin. (C) is the figure which integrated two coil | winding transformers with the resin mold. It is sectional drawing which shows an example of 2nd embodiment of the composite coil | winding transformer which concerns on this invention. It is a figure which shows 3rd embodiment of the composite coil | winding transformer which concerns on this invention. It is a figure which shows the modification of 3rd embodiment of the composite coil | winding transformer which concerns on this invention. It is a figure which shows the modification of 1st thru | or 3rd embodiment of the composite coil | winding transformer which concerns on this invention. It is a circuit diagram showing an embodiment of a lamp lighting device according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Inverter circuit 3 Switching circuit 4 Lamp 5, 6 Transformer 7, 7 'Compound winding transformer 7a, 7b, 7c, 7d Winding transformer 8 EE type core 9 Primary winding 10 Secondary winding 11 Terminal electrode 12 Bobbin 13 Resin mold 14 Core 15 Winding portion 16 Resin not including magnetic material 17 Resin including magnetic material 18 Case 19 Window 20 UU type core

Claims (10)

A core, a bobbin into which the core is inserted, a primary winding and a secondary winding wound around the bobbin, and a terminal electrode electrically connected to the primary winding and the secondary winding. A plurality of winding transformers having
A composite winding transformer comprising a plurality of winding transformers integrated with a covering member.   The composite winding transformer according to claim 1, wherein the covering member is a case of resin or nonmagnetic metal.   The composite winding transformer according to claim 2, wherein the case is coated with a magnetic material.   The composite winding transformer according to claim 2, wherein the case is made of a resin in which a magnetic material is dispersed.   The composite winding transformer according to claim 1, wherein the covering member is formed of a resin mold.   The composite winding transformer according to claim 4, wherein the resin mold uses a resin in which a magnetic material is dispersed.   7. The composite winding transformer according to claim 6, wherein at least a winding portion of the winding transformer is coated with a resin that does not disperse the magnetic material, and further coated with a resin that disperses the magnetic material.   The winding transformer has a winding axis direction parallel to the mounting surface, the primary winding and the secondary winding are surrounded by an outer frame formed by the core in the lateral direction, and the terminal electrode is a winding axis The composite winding transformer according to claim 1, wherein the composite winding transformer is arranged at a direction end. In a lamp lighting device having a plurality of winding transformers,
The plurality of winding transformers are integrated by a covering member, the primary winding is connected to the switching circuit side, and the secondary winding is connected to the lamp side. The lamp lighting device according to claim 9, wherein each of the plurality of transformers has a secondary winding connected to the same lamp.

Images