JP2006147688A - High voltage transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high voltage transformer in which the size is reduced, workability is enhanced during manufacture, and the primary and secondary windings are coupled tightly. <P>SOLUTION: The high voltage transformer comprises a primary winding 8 and a secondary winding 6 wound around the core portion 3 of a bobbin 1, and a core of magnetic material inserted into the hollow hole 12 of the bobbin 1 wherein the bobbin 1 is provided, at the opposite ends of the core portion 3, with terminal portions 2a and 2b having a plurality of terminals 5, a thin plate-like conductor forming the primary winding 8 is formed integrally in the core portion and the secondary winding 6 is formed on the outer circumference of the core portion 3 including the primary winding 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high voltage transformer, particularly a high voltage transformer for lighting a discharge tube that requires a high voltage, such as a liquid crystal display device.

  Conventionally, a discharge lamp such as a cold cathode lamp or a metal halide lamp has been used as a light source for a backlight device of a liquid crystal display device, a facsimile, a copying machine or the like. In order to light these lamps, a high voltage is required. When a cold cathode lamp is lit, the lamp is lit by boosting the output of the oscillation circuit to several kV using a high voltage transformer. In such a high-voltage transformer, for example, as shown in Patent Document 1, a core made of a ferrite is inserted into a hollow hole of a bobbin in which a core portion is axially coaxially divided into a plurality of sections by a flange, The primary winding and the secondary winding are wound using a linear conductive member.

  When the current flowing through the coil of the winding requires a large current capacity, a conductive member having a large wire diameter is used. When it is necessary to flow a large current capacity to the primary winding, a conductive member with a large wire diameter is used for the primary winding, but the coil diameter of the primary winding becomes large and the transformer becomes large. There is a problem.

  For this reason, as shown in Patent Document 2, a high-voltage transformer for lighting a discharge lamp has been proposed in which a primary winding is formed using a thin plate conductor, a large current capacity can flow, and the transformer can be miniaturized.

An exploded perspective view of the high-voltage transformer described in Patent Document 2 is shown in FIG. In FIG. 10, the high-voltage transformer has, for example, a U-shaped core 100 and a rod-shaped core 100a combined to form a closed magnetic circuit, and the primary windings 101 and 101a are formed in a U shape with thin plate conductors. Then, the primary winding 101 is inserted into the insertion holes 105a and 105b formed in the flange 104 of the bobbin 103, and the primary winding 101a is inserted into the insertion holes 105c and 105d formed in the bobbin flange 104a. In addition, each of the secondary windings 102 and 102a is arranged in a single layer and stacked in two stages to increase the electric capacity of the secondary winding, improve the insulation between adjacent lines, and improve the spacing between the lines. In this case, the short circuit caused by the potential difference between adjacent lines is reduced. In addition, the high-voltage transformer is miniaturized by making the magnetic circuit a closed magnetic circuit.
JP-A-8-153634 Japanese Patent Laid-Open No. 10-241972

  However, in the high-voltage transformer of Patent Document 2, a large current capacity can flow through the primary winding, but the primary winding and the secondary winding are arranged side by side in the axial direction. When a so-called close-coupled transformer is produced, in which the coupling between the wire and the secondary winding is poor and the coupling between the primary winding and the secondary winding is high, the performance as a transformer deteriorates. There is.

  In addition, after inserting the thin plate-like primary winding into the insertion hole formed in the flange, it is necessary to cover it with a thick resin in order to ensure insulation, and there is a problem that workability at the time of manufacture is not good.

  In view of the above problems, the present invention aims to reduce the size of the transformer, improve the workability during manufacturing, and provide a high-voltage transformer in which the primary winding and the secondary winding are closely connected. The purpose is to provide.

  In order to achieve the above object, the present invention provides a high-voltage transformer in which a primary winding and a secondary winding are wound around a bobbin core, and a core made of a magnetic material is inserted into the hollow hole of the bobbin. The bobbin has a terminal portion having a plurality of terminals at both ends of the core portion, and is integrally formed with a thin plate-like conductor that forms a primary winding in the core portion. A secondary winding is formed on the outer periphery of the core part including the wire.

  According to a preferred embodiment of the present invention, the primary winding is concentrically disposed on the inner periphery of the secondary winding on the low voltage side. Further, the secondary winding is divided into a plurality of sections, and the width between sections in the section where the primary winding is disposed is larger than the width between sections where the primary winding is not disposed. The diameter of the core part in the section where the primary winding is disposed is formed larger than the diameter of the core part in the section where the primary winding is not disposed. It is characterized by being.

Furthermore, according to another configuration of the present invention, the primary winding consists of one turn or two turns. In addition, a boss for positioning on the printed circuit board is provided on the bottom surface of the terminal portion.
Further, according to another embodiment, the secondary winding on the high voltage side is formed by oblique lap winding.

  In the high-voltage transformer of the present invention, the primary winding is made of a conductor on a thin plate, and the primary winding is embedded in the core part of the bobbin by integral molding by insert molding. It is possible to eliminate the rotating work and maintain the dimensional accuracy and improve the productivity.

  In addition, by maintaining the outer diameter of the winding portion of the secondary winding at the same level as that of the conventional high-voltage transformer and embedding the primary winding in the winding core, a small-sized and high-coupling property can be configured. .

  Furthermore, by disposing the primary winding concentrically and internally on the low voltage portion of the secondary winding, the voltage difference between the primary winding and the secondary winding is reduced, and the reliability of the transformer is improved.

Hereinafter, the high-voltage transformer of the present invention will be described with reference to the drawings.
1 to 4 show a high-voltage transformer according to the present invention. 1 is a plan view of a high-voltage transformer according to the present invention, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, FIG. 3 is a perspective view of a bobbin, and FIG. 4 is a combination of a core and a bobbin. It is a bottom view of the high voltage transformer showing the previous state.

  1 and 2, a bobbin 1 is formed of a resin such as liquid crystal polymer (LCP), and a primary winding 8 is insert-molded in the core part 3, and an outer peripheral part of the core part 3. Is divided into a plurality of sections a to h, and the secondary winding 6 is wound there.

  Terminal portions 2a and 2b provided at both ends of the bobbin 1 are provided with terminals 5a to 5k, respectively, and the core portion 3 is connected between the terminal portions 2a and 2b to form an integrated structure.

  As shown in FIG. 2, the core part 3 has two thin plate-like conductors 8a and 8b embedded in the core part by insert molding. The thin plate-like conductors 8a and 8b constitute the primary winding 8, and consist of one turn or two turns. The primary winding 8 is arranged on the left side of the figure, that is, on the low voltage side of the secondary winding 6.

  Further, the core part 3 is provided with flanges 4a to 4g for forming a plurality of sections a to h. In the example of FIGS. 1 and 2, the core part 3 is divided into 8 sections of a section to h section. ing. The section widths in the two sections of the b section and the c section are equal and are larger than the section widths in the d section to the h section, and the section widths in the five sections of the d section to the h section are respectively equal.

In addition, the outer diameter of the core portion in the three sections of the a section to the c section is formed larger than the outer diameter of the core portion 3b in the five sections of the d section to the h section, and is on the low voltage side of the secondary winding. The groove depth of the section on the high voltage side with respect to the section is shallow.
The secondary windings 6a to 6g are wound around 7 sections of b section to h section, respectively, so that the voltage in each section is substantially equal.

  In the illustrated example, terminals 5a, 5b, 5f, and 5g are terminals for primary winding, terminals 5h, 5i, 5j, and 5k are terminals for secondary winding, and terminal 5c is a terminal for GND. It has become.

  In this embodiment, no winding is wound around the a section, but a tertiary winding such as a feedback coil may be wound around the a section. When the tertiary winding is wound around the a section, the tertiary winding is drawn to the terminals 5d and 5e.

  As described above, the bobbin 1 in which the primary windings 8a and 8b are insert-molded in the core portion 3 has the outer shape shown in FIG. 3, has a through hole 12 in the center, and is formed at both ends. It has the surface 13 which raised one side of the terminal part 2a, 2b made one step, and makes insertion of the core 11 easy.

  The bobbin 1 is provided with seven flanges according to the outer diameter of the bobbin. Each of the flanges is formed with one slit groove 7 on the upper surface or the lower surface, and the secondary winding is divided. It is possible.

  In the bobbin 1, after the secondary windings 6a to 6g are wound corresponding to the plurality of sections of the core part 3, the central leg part 11a of the core 11 is the core part 3 as shown in FIG. The core 11 and the bobbin 1 are assembled so as to be inserted into the through hole 12.

  The core 11 is made of ferrite. In this embodiment, the central leg portion 11a of the E-type core 11 is inserted into the through hole 12 of the bobbin 1, but the core shape is not limited to the E-type core. Of course, an EI core, a U-type core, or the like may be used.

  For example, as shown in FIG. 8, two U-shaped cores are inserted from both ends of one or two bobbins, the ends of both cores are brought into contact with each other, and are connected to each other via an adhesive. The core 11 is attached to the bobbin 1.

  The bobbin 1 is assembled and fixed to a printed circuit board (not shown) such as a backlight inverter circuit in a state where the core 11 is combined, and the terminal of the bobbin 1 is soldered to the circuit board.

  In order to attach and fix the bobbin 1 to the printed circuit board, as shown in FIG. 4, a boss 9 is formed on the bottom surface of the terminal portion, and this boss 9 is formed in a hole provided in the printed circuit board (not shown). By inserting, the bobbin 1 can be easily attached to the correct position on the printed circuit board. Reference numerals 10a to 10e denote grooves for drawing out the lead wires of the windings.

  The primary winding 8 embedded in the winding core 3 as shown in FIG. 2 is formed of a conductive thin plate. In a preferred embodiment of the present invention, as shown in FIG. A two-turn coil is formed.

  FIG. 5 shows a primary winding 8 made of a thin plate-like conductor used in the present invention. This primary winding 8 is sequentially subjected to a punching process and a bending process by a multistage progressive press, and each of the frames along the lead frame 15 has two U-shaped primary windings 8a and 8b. Lead wires 16 extending in the direction and terminal portions 5a to 5h connected to the lead frames 15 formed on both edges are formed.

  These primary windings 8a and 8b are formed by connecting a coil portion and terminals 5b and 5f and 5a and 5g, respectively. Then, primary windings 8 a and 8 b formed by two U-shaped or U-shaped thin plates are insert-molded in the core portion 3. When the primary winding 8 is used as a one-turn coil, any one of the windings 8a and 8b may be used. When the primary winding 8 is used as a two-turn coil, for example, it is formed on a printed circuit board (not shown). The terminal 5b and the terminal 5g may be connected on the wiring pattern, and the winding 8a and the winding 8b may be configured in series.

  In the present invention, as shown in the figure, two coils 8a and 8b are used as primary windings, and when only one turn is used, the two coils are connected in parallel. When a two-turn coil is used, a common bobbin can be used in either case of one turn or two turns by connecting the two coils in series.

  In the present invention, the primary winding 8 is positioned in the mold by the lead frame 15 and insert-molded. As is apparent from the plan view of FIG. 6 a, the bobbin 1 that remains connected to the lead frame 15 is formed. And the connection part of the terminal parts 5a-5h and the lead frame 15 is cut | disconnected, and the bobbin 1 by which the primary windings 8a and 8b were insert-molded is produced.

  Thus, the primary winding 8 insert-molded on the bobbin 1 is formed on the lead frame 15 and has a height position as is apparent from the cross-sectional view of FIG. 6b as seen from the line AA of FIG. 6a. In addition, it has two U shapes with different left and right width dimensions. Each primary winding 8a, 8b has an L-shaped lead wire 16 bent outward from both ends thereof. Further, two terminals 5f and 5g for primary winding following the lead wire 16 extending from one end side of the primary winding 8 and other terminals 5a to 5e are terminals for primary winding, GND terminal and tertiary winding. Form. On the other hand, four terminals 5h, 5i, 5j, and 5k for secondary winding are formed on the terminal portion 2b on the other end side of the bobbin 1.

  Here, the primary winding, the lead wire, and the terminal are described as being integrally formed by press molding. However, if the thin plate-like conductor is insert-molded on the bobbin, the shape of the conductor is U-shaped, U Any shape such as a letter shape or a square shape may be used. Alternatively, the terminal of the primary winding may simply protrude from the side surface of the bobbin, or the terminal portion side terminal portion and the primary winding may be separated. As an example, FIG. 7 shows a cross-sectional shape of the primary winding.

  Furthermore, in a preferred embodiment of the present invention, as shown in FIG. 9a, a plurality of flanges are formed on the outer periphery of the core portion of the bobbin in order to wrap the secondary winding into a plurality of sections. However, it is also possible to use bobbins without these flanges, in which case the windings are diagonally stacked in order to maintain the breakdown voltage on the high voltage side of the secondary winding, as shown in FIG. 9b. It is also possible to wind the secondary winding in a manner in which the winding direction is reversed and the winding directions of the forward path and the double path are reversed. As a result, it is possible to form a larger number of bobbins and to reduce the cost of the winding process of the secondary winding.

  In the present invention, the section outer diameter on the low voltage side of the portion where the primary winding 8 is inserted is larger than the section outer diameter on the high voltage side. The section width of 6 is made wider than the section width on the high voltage side. This increases the degree of coupling of the high-voltage transformer and makes the overall height of the secondary winding 6 the same on the low voltage side and the high voltage side so that the outer shape of the low voltage side does not become unnecessarily thick. Yes. In other words, the secondary winding on the high voltage side increases the radial width of the winding, while the secondary winding on the low voltage side decreases the radial width of the winding to increase the secondary winding. The line height is the same as a whole, and the voltage in each section is equal.

  As described above, the high-voltage transformer of the present invention has a structure in which the primary winding 8 is made of a conductor on a thin plate, and the primary winding is embedded in the core portion 3 of the bobbin by integral molding by insert molding. The work process of winding the primary winding 8 can be eliminated, the work efficiency can be improved, and the bobbin productivity can be improved.

  In addition, the secondary winding wound around the bobbin winding core portion has the same height as the low-voltage side and high-voltage side windings, and the primary winding is formed in the winding core portion. In addition, it is possible to make a high-voltage transformer with improved connectivity.

  Further, since the positioning of the primary winding 8 is determined by the mold accuracy, the positional accuracy of the primary winding 8 in the bobbin can be maintained, and the primary winding 8 can be determined based on the design input voltage of the transformer. It is also possible to freely change the arrangement of the transformer and further arrange the transformer so that the coupling coefficient of the transformer is increased.

  Conventionally, a plurality of terminals 5 are insert-molded on the bobbin 1. However, since the primary winding 8 is also insert-molded together at the time of this insert molding, it is not necessary to increase the work cycle time transiently.

  Further, by disposing the primary winding 8 concentrically and inwardly with the low voltage portions 6a and 6b of the secondary winding 6, the voltage difference between the primary winding 8 and the secondary winding 6 is reduced, and the high voltage The reliability of the transformer is improved by reducing the short circuit due to the potential difference between the adjacent lines of the secondary winding on the side, the breakage of the bobbin due to the discharge, and the like.

It is a top view which shows the bobbin shape which shows the state which wound the secondary winding of the high voltage | pressure transformer which concerns on this invention. It is sectional drawing which shows the cross-sectional structure of the core part of FIG. It is a perspective view which shows the shape of the bobbin which concerns on this invention. It is the block diagram which showed the combination of the bobbin and core which concerns on this invention, and was seen from the bobbin bottom face side. It is a perspective view which shows the shape of the primary winding used for this invention. 6A is a schematic configuration diagram showing a state in which the bobbin and the primary winding of the present invention are integrally formed, and FIG. 6B is a cross-sectional view taken along line AA. It is sectional drawing which shows the shape of the other primary winding which concerns on this invention. FIG. 8a shows a core connected to one bobbin, and FIG. 8b is a schematic diagram showing a core connected to two bobbins. FIG. 9a shows a cross-sectional structure of the core part of the bobbin, and FIG. 9b is a cross-sectional view showing a cross-sectional structure of the core part according to another embodiment. It is a disassembled perspective view of the conventional high voltage transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bobbin 2a, 2b Terminal part 3 Core part 4a-4g Flange 5a-5h Terminal 7 Slit groove 6 Secondary winding 8 Secondary winding 9 Boss 11 Core 12 Through-hole 15 Lead frame 16 Lead wire

Claims (6)

A high-voltage transformer in which a primary winding and a secondary winding are wound around a bobbin core, and a core made of a magnetic material is inserted into a hollow hole of the bobbin,
The bobbin has a terminal portion having a plurality of terminals at both ends of the core portion, and is formed by integrally forming a thin plate-like conductor that forms a primary winding in the core portion, and includes the primary winding. A high voltage transformer, wherein a secondary winding is formed on an outer periphery of the winding core.   The high voltage transformer according to claim 1, wherein the primary winding is concentrically arranged on an inner periphery of the secondary winding on a low voltage side.   The secondary winding is divided into a plurality of sections, and the width between sections in the section in which the primary winding is disposed is larger than the width between sections in which the primary winding is not disposed. The diameter of the core part in the section where the primary winding is disposed is formed larger than the diameter of the core part in the section where the primary winding is not disposed. 3. The high voltage transformer according to claim 1, wherein the high voltage transformer is provided.   The high voltage transformer according to any one of claims 1 to 3, wherein the primary winding includes one turn or two turns.   5. The high-voltage transformer according to claim 1, wherein a boss for positioning on a printed circuit board is provided on a bottom surface of the terminal portion. 3. The high-voltage transformer according to claim 1, wherein the high voltage side of the secondary winding is obliquely wound.

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