KR101234875B1 - Emi filter for power unit not including pfc and flat panel display device including the same - Google Patents

Abstract

The present invention relates to an EMI filter of a non-PFC power supply unit and a flat panel display device including the same. A low frequency circuit is installed on a circuit board and includes a coil wound in parallel with the circuit board when viewed from the side of the circuit board. Common mode choke coils; And one high frequency common mode choke coil installed on the circuit board. .

Description

EM FILTER FOR POWER UNIT NOT INCLUDING PFC AND FLAT PANEL DISPLAY DEVICE INCLUDING THE SAME}

The present invention relates to an EMI filter and a flat panel display device including the same.

Recently, in the flat panel display (FPD) market, such as a liquid crystal display (LCD), a plasma display panel (PDP), an organic light emitting diode (OLED), and the like, the demand for technology research to slim down the overall size of the product has been increasing. have.

In particular, there is a continuing need for slimming the thickness of products in order to enhance the quality of the display device.

On the other hand, power factor correction (PFC) is often not applied to flat panel display devices having a power supply of less than about 100W or a screen size of 32 inches or less.

FIG. 2 illustrates noise by frequency band when PFC is applied, and FIG. 3 illustrates noise by frequency band when PFC is not applied.

FIG. 2 illustrates common mode noise when PFC is applied and FIG. 3 illustrates common mode noise when PFC is not applied. As illustrated in FIGS. 2 and 3, when the PFC is not applied, a DC / DC converter Electro Magnetic Interference (EMI) is greatly generated by rapid current, voltage change and miniaturization and high speed of image board and semiconductor devices caused by SMPS at the stage, and various problems are caused by the occurrence of such electromagnetic interference. As illustrated in FIG. 1, the power quality unit is provided to reduce noise.

The power quality unit includes an electromagnetic magnetic interference (EMI) filter for reducing common mode and differential mode noise, using a choke coil to reduce common mode noise.

In FIG. 4, a configuration of a conventional EMI filter applied to a power supply unit without a PFC is illustrated. As shown in FIG. 4, one high frequency common mode choke coil and two low frequency common mode choke coils are generally used.

However, in the case of the EMI filter applied to the conventional PFC non-applied power supply unit, since two or more low frequency choke coils are required, there is a limit in miniaturization of the power supply unit.

In addition, the conventional low-frequency common mode choke coil is disposed so that the coil is wound in a direction perpendicular to the substrate when the common mode choke coil is installed on the substrate. As the distance gets closer, there is a problem that the magnetic flux generated outside of the coil directly affects the panel and the back cover and generates noise.

In addition, the conventional low-frequency common mode choke coil has a problem that the manufacturing efficiency is very low because the coil is wound by manual labor.

The present invention devised to solve the above problems, it is an object of the present invention to provide an EMI filter of the PFC non-applied power supply unit which can be miniaturized, suppresses the noise generated by the magnetic flux, and improved manufacturing efficiency.

In addition, another object of the present invention is to provide a flat panel display device including the EMI filter.

The PFC non-applied EMI filter according to an embodiment of the present invention, which is designed to achieve the above object, is included in a power supply unit of a display device including a display panel, a circuit board on which circuit components are mounted, and a cover to reduce noise. 1. A low frequency common mode choke coil installed in the circuit board and including a coil wound in parallel with the circuit board when viewed from the side of the circuit board; And a high frequency common mode choke coil installed on the circuit board.

In this case, the low frequency common mode choke coil may be implemented in an EE or EER type.

In addition, when the coil of the low frequency common mode choke coil is viewed in plan view, the coil is preferably wound in a clockwise or counterclockwise direction.

The low frequency common mode choke coil may include: a bobbin in which the coil is wound; And

A core coupled with the bobbin to provide a magnetic flux; As shown in FIG.

In this case, the coil is composed of a neutral coil and a live coil, the neutral coil and the live coil is preferably partitioned and wound by the partition wall formed on the bobbin.

On the other hand, the coil is composed of a neutral coil and a live coil, the neutral coil and live coil is formed on the bobbin, the base having a lead frame electrically connected to the neutral coil and live coil and connected to the circuit board It may be partitioned and wound by a plate.

In this case, the base plate is preferably disposed parallel to the circuit board.

In addition, the base plate may be configured to be seated in the opening of the circuit board.

In addition, one of the neutral coil and the live coil may be wound around the bobbin provided in the direction of the display panel in the circuit board, and the other may be wound in the bobbin provided in the back cover direction in the circuit board.

In addition, the partition wall portion and the base plate may be configured in parallel.

In addition, the coil may be formed of a neutral coil and a live coil, and the neutral coil and the live coil may be divided and wound by the base plate.

In addition, the core may be composed of an E-type or ER-type core in which the outer foot portion and the middle foot portion are formed in the core body.

On the other hand, the high frequency common mode choke coil is preferably made of a coil wound around the O-type core.

In addition, the high frequency common mode choke coil is preferably made of 10 to 15 turns.

Meanwhile, the flat panel display apparatus according to the present invention may be configured to include the above-described EMI filter of the PFC non-applied power supply unit.

The EMI filter of the PFC non-applied power supply unit according to the present invention configured as described above, unlike the conventional EMI filter, can achieve a sufficient noise reduction effect even if only one common mode choke coil for low frequency is provided, so that the power supply unit can be miniaturized and low frequency It provides a useful effect that noise can be suppressed by minimizing the influence of the magnetic flux of the common mode choke coil on the panel or the back cover.

In addition, the low frequency common mode choke coil applied to the EMI filter of the PFC non-applied power supply unit according to the present invention can improve the manufacturing efficiency because automatic winding and manufacturing are possible unlike the conventional low frequency common mode choke coil.

In addition, the flat panel display device including the EMI filter provides a useful effect that it can be further slimmer than the conventional without causing problems such as noise due to the magnetic flux.

1 is a block diagram showing a typical configuration of a power supply unit without a PFC.
2 is a diagram illustrating common mode noise when PFC is applied.
3 is a diagram illustrating common mode noise when no PFC is applied.
4 is a diagram illustrating a conventional EMI filter applied to a power supply unit without a PFC.
5 is a diagram illustrating an EMI filter of the PFC non-applied power supply unit according to an embodiment of the present invention.
6 is a schematic exploded perspective view of a flat panel display device according to an embodiment of the present invention.
FIG. 7 is a view illustrating a coupling state of a low frequency common mode choke coil and a circuit board included in an EMI filter of a PFC non-applied power supply unit according to an embodiment of the present invention.
8 is an exploded perspective view illustrating a low frequency common mode choke coil included in an EMI filter of a PFC non-applied power supply unit according to an embodiment of the present invention.
9 is a cross-sectional view illustrating a configuration of a low frequency common mode choke coil included in an EMI filter of an PFC non-applied power supply unit according to an embodiment of the present invention.
FIG. 10 is a view illustrating a coupling relationship between a low frequency common mode choke coil and a circuit board included in an EMI filter of a PFC non-applied power supply unit according to an embodiment of the present invention.
FIG. 11 is a view illustrating a coupling relationship between a low frequency common mode choke coil and a circuit board included in an EMI filter of a PFC non-applied power supply unit according to another embodiment of the present invention.
12 is a schematic diagram illustrating a flow of magnetic flux generated in a low frequency common mode choke coil of a flat panel display device according to an exemplary embodiment of the present invention.
FIG. 13 is a view illustrating impedance characteristics of a low frequency common mode choke coil included in an EMI filter of an PFC non-applied power supply unit according to an embodiment of the present invention.
14 is a diagram showing the impedance characteristics of the high frequency common mode choke coil included in the EMI filter of the PFC non-applied power supply unit according to an embodiment of the present invention.

The advantages and features of the present invention and the techniques for achieving them will be apparent from the following detailed description taken in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The present embodiments are provided so that the disclosure of the present invention is not only limited thereto, but also may enable others skilled in the art to fully understand the scope of the invention. Like reference numerals refer to like elements throughout the specification.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, 'comprise' and / or 'comprising' refers to a component, step, operation and / or element that is mentioned in the presence of one or more other components, steps, operations and / or elements. Or does not exclude additions.

Hereinafter, with reference to the accompanying drawings will be described in more detail the configuration and operation of the present invention.

5 is a diagram illustrating an EMI filter of the PFC non-applied power supply unit according to an embodiment of the present invention.

Referring to FIG. 5, the EMI filter of the PFC non-applied power supply unit according to an embodiment of the present invention includes a coil installed on a circuit board and a coil wound in parallel with the circuit board when the circuit board is viewed from the side. And low frequency common mode choke coils 20 and one high frequency common mode choke coil 30 installed on the circuit board.

Compared with the EMI filter of the conventional PFC non-applied power supply unit illustrated in FIG. 4, it can be seen that the low frequency common mode choke coil 20 is reduced to one.

Since the configuration and operation principle of other parts are similar to those of the EMI filter of the conventional PFC non-applied power supply unit, redundant description will be omitted.

6 is a schematic exploded perspective view of a flat panel display device according to an embodiment of the present invention.

Referring to FIG. 6, a flat panel display apparatus 10 according to an exemplary embodiment of the present invention may include a display panel 14, a circuit board 15, one low frequency common mode choke coil 20, and one high frequency common. The mode choke coil 30 (not shown in FIG. 6) and the cover 18 may be included.

According to FIG. 6, the cover 18 may be a back cover separated from the front case 12, and may form an inner space together with the front case 12.

The display panel 14 may be disposed in the internal space, and may employ a liquid crystal display (LCD), a plasma display panel (PDP), an organic light emitting diode (OLED), or the like.

The display panel 14 is electrically connected to a circuit board 15 on which circuit components for driving the display panel 14 are mounted.

The circuit board 15 and the display panel 14 may be fixed to the front case 12 or the back cover 18 by the chassis 16.

The low frequency common mode choke coil 20 includes a coil wound in parallel with the circuit board 15 when the circuit board 15 is viewed from the side (arrow ⓐ).

In addition, when the circuit board 15 is viewed in plan view (arrow ⓑ) of the circuit board 15, the coil may be wound in a clockwise or counterclockwise direction.

Hereinafter, the technical characteristics of the low frequency common mode choke coil 20 included in the EMI filter of the PFC non-applied power supply unit according to an embodiment of the present invention will be described in detail, and the flat panel display apparatus 10 will be described below. It may include all the technical features of the low-frequency common mode choke coil 20.

FIG. 7 is a view illustrating a low frequency common mode choke coil included in an EMI filter of a PFC non-applied power supply unit mounted on a circuit board according to an embodiment of the present invention, and FIG. 8 is a view illustrating an embodiment of the present invention. A schematic exploded perspective view of a low frequency common mode choke coil included in an EMI filter of a PFC non-applied power supply unit, and FIG. 9 is a cross-sectional view of a low frequency common mode choke coil included in an EMI filter of a PFC non-applied power supply unit according to an embodiment of the present invention. .

7 to 9, the low frequency common mode choke coil 20 included in the EMI filter of the PFC non-applied power supply unit according to an embodiment of the present invention has a bobbin 24 to which the coils 26 and 28 are wound. And a core 22 coupled with the bobbin 24 to provide magnetic flux.

The bobbin 24 may include a base plate 246 having a lead frame 247 electrically connected to the coils 26 and 28 and coupled to the circuit board 15 of the flat panel display apparatus 10. Can be. Here, the base plate 246 includes a lead frame 247 to define a plate coupled to the circuit board 15 as a base plate.

As illustrated in FIG. 8, the bobbin 24 includes a bobbin body 242 having a rectangular cross section, and the bobbin body 242 has a core insertion hole into which the midfoot portion 224 of the core 22 is inserted. 243 is formed, and coils 26 and 28 are wound around the outer circumferential surface of the bobbin body 242.

The core 22 of the present embodiment is an E type core in which the outer foot portion 222 and the middle foot portion 224 are formed in the core body 225, and the middle foot portion 224 of the two E type cores is the bobbin 24. It can be inserted into the core insertion hole 243 of the adhesive and fixed.

At this time, the middle foot portion 224 is illustrated only the E-shaped core having a quadrangular shape, the middle foot portion 224 may use an ER-shaped core having a circular shape.

Here, the coil is composed of a neutral coil 26 and a live coil 28, the neutral coil 26 and the live coil 28 is partitioned by a partition 244 formed in the bobbin 24 Can be wound. The neutral coil 26 and the live coil 28 are wound in the same direction to perform a noise filtering function.

In the varnish impregnation process after winding the neutral coil 26 and the live coil 28 to the bobbin 24, the partition 244 is cut to facilitate the inflow of the impregnation liquid into the wound coils 26 and 28. A portion 248 may be formed.

The neutral coil 26 and the live coil 28 may be wound in parallel with the circuit board 15 when viewed from the side of the circuit board 15 (arrow ⓐ direction).

Here, the base plate 246 is parallel to the partition 244, and the base plate 246 is parallel to the circuit board 15.

When the circuit board 15 or the base plate 246 is viewed in plan view (arrow ⓑ), the neutral coil 26 and the live coil 28 may be wound in a clockwise or counterclockwise direction.

FIG. 10 is a diagram illustrating a state in which a low frequency common mode choke coil included in an EMI filter of an PFC non-applied power supply unit is mounted on a circuit board having an opening. Referring to FIG.

Referring to FIG. 10, a configuration in which the low frequency common mode choke coil 20 illustrated in FIGS. 8 and 9 is mounted on the circuit board 15 may be confirmed.

In the low frequency common mode choke coil 20 illustrated in FIGS. 8 and 9, the base plate 246 constituting the bobbin 24 is formed on the lowermost layer, and the bobbin body 242 is formed on the base plate 246. Is formed.

The base plate 246 according to the present embodiment may be seated in the opening 155 of the circuit board 15. As described above, the opening 155 is formed in the circuit board 15 to install the low frequency common mode choke coil 20, thereby achieving the slimming of the entire flat panel display apparatus 10.

FIG. 11 is a schematic perspective view of a low frequency common mode choke coil included in an EMI filter of a non-PFC power supply unit mounted on a circuit board having an opening according to another embodiment of the present invention.

Referring to FIG. 11, a state in which the low frequency common mode choke coil 20 included in the EMI filter of the PFC non-applied power supply unit according to another embodiment of the present invention is mounted on the circuit board 15 may be confirmed.

The low frequency common mode choke coil 20 included in the EMI filter of the PFC non-applied power supply unit according to the present embodiment is a neutral coil 26 and a live coil 28 are formed on the bobbin 24, the neutral coil 26 ) And a base plate 246 having a lead frame 247 electrically connected to the live coil 28 and connected to the circuit board 15.

The bobbin 24 according to the present exemplary embodiment may include a partition wall portion 244 disposed in parallel with each other up and down with respect to the base plate 246.

The base plate 246 according to the present embodiment may be seated in the opening 155 of the circuit board 15. As the base plate 246 is seated in the opening 155 of the circuit board 15, one of the neutral coil 26 and the live coil 28 is connected to the display panel 14 on the circuit board 15. It is wound on the bobbin 24 in the () direction, and the other may be wound on the bobbin 24 in the direction of the back cover 18 on the circuit board 15.

In the case of using the circuit board 15 to which the low frequency common mode choke coil 20 included in the EMI filter of the PFC non-applied power supply unit according to the present embodiment is applied, the entire flat panel display 10 as compared to the embodiment illustrated in FIG. Can be made thinner.

12 is a schematic diagram illustrating a flow of magnetic flux generated in a low frequency common mode choke coil in a flat panel display device according to an exemplary embodiment of the present invention.

Referring to FIG. 12, the magnetic flux of the coil is different from the conventional case in which the neutral coil 26 and the live coil 28 are installed in parallel to the printed circuit board 15 so as to be wound in a direction perpendicular to the substrate 15. Is formed in the direction of the arrow.

That is, since the magnetic flux is formed in parallel with the display panel 14 and the back cover 18, the magnetic flux does not interfere with the display panel 14 and the back cover 18 of the flat display device 10. There is no effect.

In addition, the interference with the display panel 14 and the back cover 18 may be alleviated by playing a role of alleviating the leakage of magnetic flux in the above-described E-type or ER-type core.

According to the EMI filter of the flat panel display apparatus and the PFC non-applied power supply unit according to the present invention, the flat panel display apparatus 10 is slimmed so that the circuit board 15 is close to the display panel 14 and the back cover 18. Even though the coil of the low frequency common mode choke coil 20 is wound horizontally with the circuit board 15, the magnetic flux generated in the coil directly affects the display panel 14 or the back cover 18. It will not go crazy.

In this way, the magnetic flux affects the display panel 14 or the back cover 18, and the noise generated is significantly reduced.

Meanwhile, the high frequency common mode choke coil 30 included in the EMI filter of the PFC non-applied power supply unit according to an embodiment of the present invention may be formed by winding a coil around an O-type core, and in this case, 10 to 15 turns It can be configured to have.

FIG. 13 illustrates an impedance characteristic of a low frequency common mode choke coil 20 included in an EMI filter of an PFC non-applied power supply unit according to an embodiment of the present invention, and FIG. 14 illustrates a non-PFC application according to an embodiment of the present invention. An impedance characteristic of the high frequency common mode choke coil 30 included in the EMI filter of the power supply unit is illustrated.

As illustrated in FIG. 13, the low frequency common mode choke coil 20 included in the EMI filter of the PFC non-applied power supply unit according to the embodiment of the present invention has an impedance characteristic in which resonance points are formed in a region of less than 1 MHz. The common mode noise of the region can be reduced, and as illustrated in FIG. 14, the high frequency common mode choke coil 30 included in the EMI filter of the PFC non-applied power supply unit according to the embodiment of the present invention is located in a region exceeding 1 MHz. Since the resonance point has an impedance characteristic formed, common mode noise in the high frequency region can be reduced.

Therefore, the common mode noise of the high frequency region and the low frequency region can be effectively reduced by using a single high frequency common mode choke coil 20 and a low frequency common mode choke coil 30, respectively. Can be reduced.

The foregoing detailed description is illustrative of the present invention. In addition, the foregoing description merely shows and describes preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. That is, it is possible to make changes or modifications within the scope of the concept of the invention disclosed in this specification, the disclosure and the equivalents of the disclosure and / or the scope of the art or knowledge of the present invention. The above-described embodiments are for explaining the best state in carrying out the present invention, the use of other inventions such as the present invention in other states known in the art, and the specific fields of application and uses of the invention are required. Various changes are also possible. Accordingly, the detailed description of the invention is not intended to limit the invention to the disclosed embodiments. It is also to be understood that the appended claims are intended to cover such other embodiments.

10: flat panel display device
12: front case
14 display panel
15: circuit board
16: chassis
18: back cover
20: low frequency common mode choke coil
22: Core
24: bobbin
30: common mode choke coil for high frequency

Claims (15)

delete delete delete delete In order to reduce noise included in a power supply unit of a display device including a display panel, a circuit board on which circuit components are mounted, and a cover,
One low-frequency circuit, which is installed on the circuit board and includes a coil wound in parallel with the circuit board when viewed from the side, a bobbin wound around the coil, and a core coupled with the bobbin to provide magnetic flux. Common mode choke coil; And
Including; a high frequency common mode choke coil is installed on the circuit board;
The coil is composed of a neutral coil and a live coil, the neutral coil and live coil, characterized in that the partition is wound by the partition wall formed in the bobbin
EMI filter in PFC power supply.
In order to reduce noise included in a power supply unit of a display device including a display panel, a circuit board on which circuit components are mounted, and a cover,
One low-frequency circuit, which is installed on the circuit board and includes a coil wound in parallel with the circuit board when viewed from the side, a bobbin wound around the coil, and a core coupled with the bobbin to provide magnetic flux. Common mode choke coil; And
Including; a high frequency common mode choke coil is installed on the circuit board;
The neutral coil and the live coil have a lead frame electrically connected to the neutral coil and the live coil and connected to the circuit board, and are divided and wound by a base plate formed on the bobbin.
EMI filter in PFC power supply.
The method according to claim 6,
The base plate is disposed parallel to the circuit board
EMI filter in PFC power supply.
The method according to claim 6,
The base plate is seated in the opening of the circuit board
EMI filter in PFC power supply.
The method of claim 8,
One of the neutral coil and the live coil is wound around the bobbin provided in the display panel direction on the circuit board, and the other is wound around the bobbin provided in the back cover direction on the circuit board.
EMI filter in PFC power supply.
The method of claim 7, wherein
The bobbin further comprises a partition wall portion provided parallel to the base plate.
EMI filter in PFC power supply.
delete delete delete delete The flat panel display device including the EMI filter of the non-PFC power supply unit according to any one of claims 5 to 10.

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