JP2008140804A - High voltage transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high voltage transformer which can produce a good high voltage detection waveform. <P>SOLUTION: The high voltage transformer comprises a bobbin, a primary winding wound around the drum section of the bobbin, a secondary winding wound around the drum section of the bobbin in parallel with the primary winding, and a tertiary winding wound to be covered with the secondary winding on the inside thereof in order to detect the voltage of the secondary winding. The tertiary winding is constituted to have a winding width narrower than that of the secondary winding, and arranged such that the end of the tertiary winding on the primary winding side is located farther from the primary winding than the end of the secondary winding on the primary winding side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transformer having a detection winding.

  A high-voltage transformer is used as an inverter power supply for the backlight. As a high-voltage transformer, there is known a structure in which a primary winding and a secondary winding are wound side by side in the axial direction of a bobbin body around a body of a bobbin into which a core is inserted.

  A high-voltage transformer having such a structure is known that includes a high-voltage detection winding (tertiary winding) in order to detect a voltage output from a secondary winding (high-voltage winding).

  In a high-voltage transformer having a high-voltage detection winding, the output of the high-voltage detection winding is a low voltage of about 15V. The high-voltage detection winding is disposed inside the secondary winding so that the position of the end of the secondary winding coincides with the end of the primary winding.

  However, in a high-voltage transformer having such a high-voltage detection winding, a phenomenon may occur in which an output waveform is distorted by superimposing a high-frequency component on the output of the high-voltage detection winding. Such distortion of the high voltage detection waveform may cause a malfunction of the high voltage protection circuit.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a high voltage transformer capable of obtaining a good high voltage detection waveform.

  The above problems are solved by, for example, the invention described in the claims.

  According to the high voltage transformer of the present invention, a good high voltage detection waveform can be obtained.

  Hereinafter, embodiments of a high-voltage transformer according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic diagram of a high-voltage transformer. The high voltage transformer 1 includes a bobbin 11, a primary winding (low voltage winding) 12, a secondary winding (high voltage winding) 14, and a high voltage detection winding (not shown).

  FIG. 2 schematically shows a state where the high-voltage detection winding (tertiary winding) is wound around the bobbin 11.

  The bobbin 11 is made of resin, and a plurality of groove portions (winding grooves) 1 to 8 for winding the primary winding and the secondary winding are formed in the body portion. In the present embodiment, the number of groove portions is eight. The diameter of the groove parts 1-8 is comprised so that it may become large as it goes to a high voltage | pressure side from a low voltage | pressure side. Terminals 19 a to 19 j are provided at both ends of the bobbin 11.

  In the high voltage transformer 1 shown in FIG. 1, the primary winding 12 is wound around the groove portion 1 of the bobbin 11, and the secondary winding is wound around the groove portions 3 to 8. The high-voltage detection winding 16 is wound around the groove portion 5 positioned substantially at the center of the secondary winding 14, and the secondary winding 14 is wound in an overlapping manner so as to cover the high-voltage detection winding 16. Here, the high voltage detection winding 16 is overlapped so as to be in contact with the secondary winding, but an insulator or the like may be interposed between the high voltage detection winding 16 and the secondary winding.

  In the present embodiment, the diameters of the groove portions 1 to 8 are configured to increase from the low pressure side to the high pressure side, but the groove portion 5 in which the high voltage detection winding 16 is formed is larger than the other groove portions. The diameter may be large or small. In addition, the groove around which the secondary winding is wound may have a constant diameter, and only a part of the grooves may be formed larger or smaller. Further, the high-voltage detection winding 16 may be wound around two or more groove portions.

  In the present embodiment, the number of groove portions formed in the body portion is eight. However, in the present invention, the number of groove portions is not limited to eight. Further, the depth and width of the groove are not particularly limited.

  The number of windings and the material of the high-voltage detection winding are also not particularly limited, and can be appropriately set according to the ratio between the primary winding and the secondary winding, the operating voltage, and the like.

  Next, the relationship between the position where the high voltage detection winding 16 is formed and the detection waveform of the high voltage detection winding 16 was examined. 2 to 8 show the position of the high-voltage detection winding with respect to the secondary winding 14 and the detection waveform detected from the high-voltage detection winding formed at that position. 2 to 8, the position of the high voltage detection winding is shown on the upper side of the drawing, and the output waveform of the secondary winding and the graph of the detection waveform of the high voltage detection winding are shown on the lower side of the drawing.

  As shown in FIG. 2, the high voltage detection winding 16 is formed in the groove 2, and the primary winding and the secondary winding are not wound on the high voltage detection winding 16 without overlapping the secondary winding. In the transformer in which the high-voltage detection winding is formed between them, it can be seen that the voltage waveform from the high-voltage detection winding 16 is distorted by superimposing high-frequency components.

  Further, as shown in FIG. 3, when the high voltage detection winding is provided in the groove 3 closest to the primary winding, similarly, a high frequency component is superimposed on the voltage waveform from the high voltage detection winding and distorted. You can see that

  On the other hand, as shown in FIG. 4 to FIG. 8, by forming the high-voltage detection winding 16 in the groove portions 4 to 8 that are arranged farther away from the primary winding 12 than the groove portion 3, It can be seen that the distortion of the voltage waveform of the high voltage detection winding 16 is reduced. In particular, when the high voltage detection winding 16 is formed substantially at the center of the secondary winding 14, the distortion of the detection waveform from the high voltage detection winding 16 is most reduced.

  FIG. 9 shows a graph of the leakage inductance of the high voltage detection winding with respect to the position of the high voltage detection winding in the high voltage transformer having the structure shown in FIG.

  Among the plurality of groove portions 2 to 8 (winding groove Nos. 2 to 8) formed in the bobbin 11, the high voltage detection winding 16 is provided in the groove portion 5 located at the approximate center in the length direction of the secondary winding portion 14. It can be seen that the leakage inductance is the lowest and the coupling between the high voltage detection winding 16 and the secondary winding 14 is the strongest.

  The present invention is applicable to both an open magnetic circuit type high voltage transformer and a closed magnetic circuit type high voltage transformer.

  As described above, the waveform of the high voltage detection voltage can be improved by devising the winding method of the high voltage detection coil. Thereby, the operation of the high voltage protection circuit can be stabilized.

  Such a high voltage transformer of the present invention is used for an inverter power source of a liquid crystal display device, for example. 10 and 11 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. 10, 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. 11, 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.

  For example, in the above example, the present invention is applied to a high-voltage transformer used for an inverter power supply, but is not limited to this and can be applied to various transformers.

FIG. 1A is a schematic diagram of a high-voltage transformer according to the present invention, and FIG. 1B is a diagram showing a position where a high-voltage detection winding is formed. FIG. 2 shows a position of the high voltage detection winding with respect to the secondary winding and a detection waveform detected from the high voltage detection winding formed at that position. FIG. 3 shows the position of the high voltage detection winding with respect to the secondary winding and the detection waveform detected from the high voltage detection winding formed at that position. FIG. 4 shows the position of the high voltage detection winding with respect to the secondary winding and the detection waveform detected from the high voltage detection winding formed at that position. FIG. 5 shows a position of the high-voltage detection winding with respect to the secondary winding and a detection waveform detected from the high-voltage detection winding formed at that position. FIG. 6 is a detection waveform detected from the position of the high voltage detection winding with respect to the secondary winding and the high voltage detection winding formed at that position. FIG. 7 shows the position of the high-voltage detection winding with respect to the secondary winding and the detection waveform detected from the high-voltage detection winding formed at that position. FIG. 8 is a detection waveform detected from the position of the high-voltage detection winding with respect to the secondary winding and the high-voltage detection winding formed at that position. 2 is a graph of leakage inductance of the high voltage detection winding with respect to the position of the high voltage detection winding of the high voltage transformer shown in FIG. 1. 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 1-8 ... Winding groove, 10 ... High voltage transformer, 11 ... Bobbin, 12 ... Primary winding, 14 ... Secondary winding, 16 ... High voltage detection winding, 19a-j ... Terminal, 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 (2)

A high voltage transformer,
With bobbin,
A primary winding wound around the body of the bobbin;
A secondary winding wound around the bobbin body in parallel with the primary winding;
A tertiary winding wound inside the secondary winding so as to be covered by the secondary winding in order to detect the voltage of the secondary winding;
The tertiary winding is configured to be narrower than the secondary winding,
The primary winding side end of the tertiary winding is positioned at a position farther from the primary winding than the primary winding side end of the secondary winding. A high-voltage transformer with a tertiary winding. The high-voltage transformer according to claim 1,
The tertiary winding is a high-voltage transformer provided at a substantially central position of the secondary winding in the axial direction of the bobbin.

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