KR101361074B1 - Current sensing transformer, method for manufacturing the same, lamp power supply and liquid crystal display having the same - Google Patents

Abstract

The present invention relates to a current sensing transformer, a method of manufacturing the same, a lamp power supply and a liquid crystal display device having the same, in a predetermined form on one surface of a printed circuit board including an insulating base plate and an insulating base plate of the printed circuit board. Provided are a current sensing transformer including a first winding pattern formed and a second winding pattern formed on a second surface of an insulating base plate of a printed circuit board, a method of manufacturing the same, and a lamp power supply and a liquid crystal display device having the same. .

LCD, Inverter, Transformer, Current Sense Transformer, Printed Circuit Board

Description

Current sensing transformer, method for manufacturing same, lamp power supply and liquid crystal display having same {Current sensing transformer, method for manufacturing the same, lamp power supply and liquid crystal display having the same}

The present invention relates to a current sensing transformer, a method for manufacturing the same, a lamp power supply and a liquid crystal display device having the same, and more particularly, a coreless current sensing transformer manufactured using a printed circuit board and a method for manufacturing the same. It relates to a lamp power supply and a liquid crystal display.

The liquid crystal display device displays a desired image on a screen by adjusting the amount of light transmitted according to image signals applied to a plurality of control switches arranged in a matrix form, and applies light to the liquid crystal display panel and the liquid crystal display panel which display an image directly. And a backlight unit for illuminating. Since the liquid crystal display does not emit light by itself, a light source such as a backlight unit is required, and various fluorescent lamps and light emitting diodes are used as the light source, and among these, a cold cathode fluorescent lamp (CCFL) is used. Lamp) is mainly used. Recently, liquid crystal displays are required to be continuously enlarged and high in brightness through various applications such as LCD TVs and monitors. Accordingly, the number of lamps used as light sources is increasing. Since the increase in the number of lamps is accompanied by the increase in the size and the price of the lamp power supply required for driving the lamp, a cost reduction technology has been proposed.

Meanwhile, referring to a lamp power supply device, that is, a lamp driving inverter unit according to the related art, in order to provide a high voltage AC power to a lamp, in addition to a transformer for converting the level of AC power, the level of power applied to the lamp is sensed. A separate current sensing transformer was needed to do this. As a result, the number of parts of the lamp power supply increases, there is a problem that the production cost increases, and as the lamp power supply increases, there is a problem that also takes up a lot of mounting space in the liquid crystal display. Therefore, the research to reduce the number of parts of the lamp power supply required to drive the lamp, simplify the manufacturing process, reduce the production cost of the liquid crystal display device, and downsize the size of the lamp power supply.

The present invention is to overcome the above-described problems, the technical problem to be achieved by the present invention is to reduce the number of parts of the lamp power supply, to simplify the manufacturing process, coreless manufactured using a printed circuit board A current sensing transformer, a method of manufacturing the same, and a lamp power supply and a liquid crystal display device having the same.

According to an aspect of the present invention for achieving the object of the present invention, a printed circuit board including an insulating base plate; A first winding pattern formed in a predetermined shape on one surface of the insulating base plate of the printed circuit board; And a second winding pattern formed on the other surface of the insulating base plate of the printed circuit board in a predetermined shape.

The first winding pattern and the second winding pattern are disposed to face each other.

The first winding pattern and the second winding pattern are made of a conductive material.

The first winding pattern and the second winding pattern include copper.

The first winding pattern and the second winding pattern are formed in any one of a polygon, a circle, and an oval.

A first leakage magnetic flux prevention layer disposed on one surface of the insulating base plate of the printed circuit board and the inside of the first winding pattern; And a second leakage magnetic flux prevention layer disposed on the other surface of the insulating base plate of the printed circuit board and the second winding pattern.

The first leakage flux prevention layer and the second leakage flux prevention layer are made of a ferrite polymer composite.

The first leakage magnetic flux prevention layer and the second leakage magnetic flux prevention layer are formed to correspond to the shape of the first winding pattern and the second winding pattern.

The printed circuit board may be a double-sided printed circuit board or a multilayer printed circuit board.

According to another aspect of the present invention for achieving the object of the present invention, preparing a printed circuit board; Forming a first winding pattern and a second winding pattern of predetermined shapes on one side and the other side of the printed circuit board; And forming a first leakage magnetic flux prevention layer and a second leakage magnetic flux prevention layer, respectively, in the first winding pattern and the second winding pattern.

The preparing of the printed circuit board may include preparing a copper foil laminate having copper foil layers formed on one surface and the other surface of the insulating base plate.

The forming of the first winding pattern and the second winding pattern may include forming a photoresist pattern having a predetermined shape on each of the copper foil layers; Etching each of the copper foil layers; And removing the photoresist pattern.

The first leakage flux prevention layer and the second leakage flux prevention layer are made of a ferrite polymer composite.

According to another aspect of the present invention for achieving the object of the present invention, the DC / AC conversion unit for converting the DC power supplied from the outside into AC power; A transformer for converting a level of an AC power output from the DC / AC converter; A power detector for detecting a level of AC power applied to the lamp; A comparator for comparing a power level sensed by the power detector and a reference power level to determine a power change; And a controller for controlling the operation of the DC / AC converter according to the signal output from the comparator, wherein the power detector includes a printed circuit board including an insulating base plate; A first winding pattern formed in a predetermined shape on one surface of the insulating base plate of the printed circuit board; And a current sensing transformer including a second winding pattern formed in a predetermined shape on the other surface of the insulating base plate of the printed circuit board.

The power detection unit may include a first leakage magnetic flux prevention layer disposed on one surface of the insulating base plate of the printed circuit board and the inside of the first winding pattern; And a second leakage magnetic flux prevention layer disposed on the other surface of the insulating base plate of the printed circuit board and the second winding pattern.

The DC / AC converter, transformer, comparator and controller are mounted on the printed circuit board.

The power detector is connected to the input terminal or output terminal of the transformer.

It is connected to the input terminal of the DC / AC converter, and further comprises a switching unit for controlling the output of the DC power supplied from the outside.

According to another aspect of the present invention for achieving the object of the present invention, at least one lamp and a DC / AC converter for converting a DC power supplied from the outside into an AC power source; A transformer for converting a level of an AC power output from the DC / AC converter; A power detector for detecting AC power applied to the lamp; A comparison unit comparing the power sensed by the power detection unit with a reference power to determine a change in power; And a lamp power supply comprising a control unit for controlling an operation of the DC / AC converter according to the signal output from the comparison unit. And a liquid crystal display panel disposed on the backlight unit to display an image, wherein the power sensing unit includes a printed circuit board including an insulating base plate; A first winding pattern formed in a predetermined shape on one surface of the insulating base plate of the printed circuit board; And a current sensing transformer including a second winding pattern formed in a predetermined shape on the other surface of the insulating base plate of the printed circuit board.

According to the present invention, a coreless current sensing transformer is manufactured by using a printed circuit board on which various components of a lamp power supply are mounted, without using a separate current sensing transformer, thereby reducing the number of parts and improving the manufacturing process. It can be simplified.

As a result, it is possible to reduce the production cost of the lamp power supply and the liquid crystal display.

1A to 1C are a perspective view, a plan view, and a sectional view of a current sensing transformer according to a first embodiment of the present invention.

1A to 1C, the current sensing transformer 540 includes an insulating base plate 541, a first winding pattern 542, and a second winding pattern 543 of a printed circuit board.

The first winding pattern 542 is formed on one surface, that is, the upper surface, of the insulating base plate 541 of the printed circuit board, and the second winding pattern 543 is formed on the other surface, that is, the lower surface of the insulating base plate 541. Is formed.

In general, a printed circuit board (PCB) is a conductive pattern formed of a conductive material on the surface or surface of an insulating base board and the inside thereof and is fixed to it. It serves as a support and connects the signals of each part to each other. Such PCBs include single-sided PCBs in which circuits are formed only on one side, double-sided PCBs in which circuits are formed on both upper and lower sides, and multilayer PCBs in which circuits are additionally formed inside. In the present embodiment, a double-sided PCB is described as an example, but is not limited thereto, and a multilayer PCB may be used.

The first winding pattern 542 and the second winding pattern 543 are each formed in a rectangular shape and are disposed to face each other. In addition, the first winding pattern 542 and the second winding pattern 543 are made of a conductive material. Preferably, it is generally made of copper, which is used as a conductive material in printed circuit boards.

In the present embodiment, the first winding pattern 542 and the second winding pattern 543 are each formed in a wound form, but the present invention is limited thereto. The number of windings of the first winding pattern and the second winding pattern may be variously modified. Can be. In this case, when the number of windings of the first winding pattern and the second winding pattern is at least two or more times, the first winding pattern and the second winding pattern are formed in a spiral shape as a whole.

The current sensing transformer according to the prior art is formed by winding a core, the first winding and the second winding around this core. The first winding and the second winding wound on the core are electrically separated, but are magnetically coupled. When an alternating current flows through the first winding, the magnetic flux passing through the core changes, resulting from the electromagnetic induction action. Induced electromotive force is generated in the second winding, and this principle is used to sense the current.

The current sensing transformer according to the present invention having the first winding pattern and the second winding pattern corresponding to the first winding and the second winding of the current sensing transformer according to the prior art is provided with an alternating current applied to the first winding pattern. The induced electromotive force is generated in the second winding pattern by the induction action to sense the current.

2A and 2B are perspective views illustrating a modification of the current sensing transformer according to the first embodiment of the present invention.

2A and 2B, a first winding pattern 542 is formed on one surface, that is, the upper surface, of the insulating base plate 541 of the printed circuit board, and the other surface of the insulating base plate 541, that is, the lower portion thereof. The second winding pattern 543 is formed on the surface. In this case, each of the first winding pattern 542 and the second winding pattern 543 may be circular as shown in FIG. 2A or elliptical as shown in FIG. 2B and disposed to face each other. However, the shape of the first winding pattern and the second winding pattern is not limited thereto, and may be variously modified.

3A to 3C are a perspective view, a plan view, and a cross-sectional view of a current sensing transformer according to a second embodiment of the present invention.

3A to 3C, the current sensing transformer 540 may include an insulating base plate 541, a first winding pattern 542, a second winding pattern 543, and a first leakage of a printed circuit board. The magnetic flux prevention layer 544 and the second leakage magnetic flux prevention layer 545 are included.

The first winding pattern 542 is formed on one surface, that is, the upper surface, of the insulating base plate 541 of the printed circuit board, and the second winding pattern 543 is formed on the other surface, that is, the lower surface of the insulating base plate 541. Is formed.

The first winding pattern 542 and the second winding pattern 543 are each formed in a rectangular shape and are disposed to face each other. In addition, the first winding pattern 542 and the second winding pattern 543 are made of a conductive material. Preferably, it is generally made of copper, which is used as a conductive material in printed circuit boards.

Meanwhile, in the present exemplary embodiment, the first winding pattern 542 and the second winding pattern 543 are formed to be wound once, respectively, but the number of windings of the first winding pattern and the second winding pattern may vary. It can be modified. In addition, the shape of the first winding pattern and the second winding pattern is not limited to the rectangular shape, and as described above, it may be formed in various shapes such as circular or elliptical.

The first leakage magnetic flux prevention layer 544 is formed on one surface of the insulating base plate 541 of the printed circuit board, that is, the upper surface thereof, and is preferably disposed inside the first winding pattern 542 and the second leakage magnetic flux. The prevention layer 545 is formed on the other surface of the insulating base plate 541 of the printed circuit board, that is, the bottom surface, and is preferably disposed inside the second winding pattern. The first leakage magnetic flux prevention layer 544 and the second leakage magnetic flux prevention layer 545 prevent leakage of the magnetic flux generated between the first winding pattern and the second winding pattern.

In this case, the first leakage flux prevention layer 544 and the second leakage flux prevention layer 545 are formed corresponding to the shapes of the first winding pattern 542 and the second winding pattern 543. That is, the first leakage magnetic flux prevention layer 544 and the second leakage magnetic flux prevention layer 545 are formed in a quadrangular shape.

The first leakage magnetic flux prevention layer 544 and the second leakage magnetic flux prevention layer 545 are disposed to be spaced apart from the first winding pattern 542 and the second winding pattern 543 by a predetermined interval. That is, the first winding pattern 542 and the second winding pattern 543 are formed along the circumferences of the first leakage flux prevention layer 544 and the second leakage flux prevention layer 545, respectively.

In addition, the first leakage flux prevention layer 544 and the second leakage flux prevention layer 545 are preferably made of a ferrite polymer composite. The ferrite composite material is a composite of ferrite powder and plastic, and has a stable magnetic property and can be manufactured in the form of a flexible film, which is suitable for application as the leakage flux prevention layer of this embodiment.

4A to 4E are cross-sectional views of a manufacturing process of the current sensing transformer according to the present invention.

Referring to FIG. 4A, a printed circuit board is first prepared. In this case, the printed circuit board prepares a copper foil laminated plate in which copper foil layers 542 and 543 are formed on the upper and lower surfaces of the insulating base plate 541, respectively. In this embodiment, a copper foil laminate for double-sided PCB is used, but is not limited thereto, and a copper foil laminate for multilayer PCB may be used.

Referring to FIG. 4B, photoresist patterns 546 and 547 having a predetermined form are formed on the copper foil layers, respectively. A photoresist is formed over the entire copper foil layer, and then a predetermined shape photoresist pattern is formed through an exposure and development process using a mask (not shown) on which a predetermined pattern is formed.

4C and 4D, after the copper foil layer is etched using the photoresist patterns 546 and 547 as an etching mask, the photoresist pattern is removed to form a first winding pattern 542 and a second winding of a predetermined shape. Pattern 543 is formed.

Referring to FIG. 4E, a first leakage flux prevention layer 544 and a second leakage flux prevention layer 545 are formed in the first winding pattern 542 and the second winding pattern 543, respectively. In this case, the first leakage flux prevention layer 544 and the second leakage flux prevention layer 545 are formed by attaching a film made of a ferrite polymer composite. Alternatively, the thin film may be formed through a photolithography and etching process without attaching the leakage flux prevention layer in the form of a film. However, the present invention is not limited thereto, and the materials, shapes, and manufacturing processes of the first and second leakage magnetic flux prevention layers may be variously modified. In addition, in the above, after the winding pattern is formed, a leakage flux prevention layer is formed therein. On the contrary, after the leakage flux prevention layer is formed, a winding pattern surrounding the leakage flux layer may be formed.

5A is a schematic block diagram of a lamp power supply including a current sensing transformer according to the present invention, FIG. 5B is a schematic circuit diagram of a power sensing unit, and FIG. 5C is a schematic perspective view of the current sensing transformer of FIG. 5B. 6 is a schematic configuration diagram of the DC / AC converter shown in FIG. 5A.

5A to 6, the lamp power supply 500 includes a switching unit 510, a DC / AC converter 520, a power detector 530, a transformer 550, a comparator 560, and The control unit 570 is included.

The switching unit 510 controls the output of the DC power supplied from the outside. The DC / AC converter 520 connected to the output terminal of the switching unit 510 converts the DC power supplied through the switching unit 510 into AC power.

The DC / AC converter 520 includes an inductor L, a capacitor C, first and second switches 521 and 522, and a switch controller 5250. Capacitor C is connected in parallel with transformer 550 where a first node of capacitor C is connected to first switch 521 and a second node of capacitor C is connected to second switch 522. Connected.

The transformer 550 is connected to the output terminal of the DC / AC converter 520, converts the level of the AC power output from the DC / AC converter 520, and provides it to the lamp 410 shown in the figure, Drive the lamp. The primary winding 551 of the transformer 550 is connected to the output terminal of the DC / AC converter 520, the secondary winding 552 is connected to both electrodes of the lamp 410.

The power detector 530 detects the level of the AC power applied to the lamp. In the present embodiment, the power detector 530 includes a current sensing transformer 540 and a current change detector 580 using the above-described printed circuit board. In addition, the power detection unit 530 composed of the current-sensing transformer 540 may be connected to the primary winding 551 of the transformer to sense the current applied to the lamp as in the present embodiment. It may be connected to the secondary winding 552 to sense a current applied to the lamp.

The comparator 560 determines whether the change level of the current detected by the current change detector 580 of the power detector 530 is abnormal, and the controller 570 according to the signal output from the comparator 560. By controlling the on / off of the switching unit 510, the operation of the DC / AC converter 520 is controlled.

5B and 5C, the circuit configuration and operation of the power detector 530 and the comparator 560 will be described. The power detector 530 includes a current sensing transformer 540 and a current change detector 580.

The current sensing transformer 540 includes an insulating base plate 541 of the printed circuit board, a first winding pattern 542 formed on one surface of the insulating base plate 541, and the other of the insulating base plate 541. A second winding pattern 543 formed on a surface thereof, and first connection terminals 542a and 542b are formed at both ends of the first winding pattern 542 and second ends of the second winding pattern 543. Connection terminals 543a and 543b are formed.

The first winding pattern 542 of the current sensing transformer 540 is connected between the primary winding 551 of the transformer 550 and the DC / AC converter 520. That is, one of the first connection terminals 542a of the first winding pattern 542 is connected to the primary winding 551, and the other of the first connection terminals 542b is connected to the DC / AC converter 520. do. In addition, the second winding pattern 543 is connected to the current change detector 580. That is, the second connection terminals 543a and 543b of the second winding pattern 543 are connected to the detection terminals 581 and 582 of the current change detector 580.

The current sensing transformer 540 is a detection conductor that detects a change in current through a magnetic flux change Δφ occurring in the first winding pattern 542 connected to the primary winding 551 of the transformer 550. Winding pattern 543 is formed.

The detection terminals 581 and 582 of the current change detector 580 are connected to the second connection terminals 543a and 543b of the second winding pattern 543 to extract the voltage generated due to the action of the magnetic flux change Δφ. . The detection voltage obtained at the detection terminals 581 and 582 is applied to a circuit for detecting a change in current. This circuit includes a diode 583, a capacitor 584 and a resistor 585. The diode 583 is connected to the detection terminal 581, and a capacitor 584 and a resistor 585 are connected as a filter circuit between the cathode side of the diode 583 and the detection terminal 4452. By such a configuration The current change detection unit 580 is configured as a current / voltage conversion unit for converting a change in current into a change in direct current voltage, and the capacitor 584 and the resistor 585 obtain a direct current voltage corresponding to the change in current. This voltage level represents a change in current.

The detection signal of the current change detector 580 is applied to the comparator 560. The comparator 560 constitutes an amplifying part of the detection signal, and performs a function of determining whether the operation is abnormal from the level of change of the current. Accordingly, by controlling the on / off of the switching unit 510, the operation of the DC / AC converter 520 is controlled.

Referring to the operation of the lamp power supply, when the switching unit 510 is turned on, DC power is applied to the DC / AC converter 520, and an AC voltage, for example, a sine wave voltage, appears across the load or the lamp. Current flows through the inductor L to the center tap of the transformer 550. The switch controller 525 controls the on or off of the first switch and the second switch 521, 522, and the first and second switches are alternately opened and closed so that the AC across the secondary winding of the transformer 550 can be used. Generate a waveform. At this time, the operating frequencies of the first switch and the second switch can be fixed, but are normally synchronized with the resonant frequency of the reactive component of the circuit (ie, the capacitor C). When the first and second switches are synchronized with the resonant frequencies of the reactive components of the circuit, a sine wave is output.

When the switching unit 510 is turned off, the DC power supplied to the lamp power supply is cut off, and the switching unit 510 controls the output of the DC power by the output of the controller 570 to control the power applied to the lamp. To control.

A power detector 530 is connected to the primary winding or the secondary winding of the transformer 550. Through the current sensed by the power detector 530, it is possible to determine whether the current is normally supplied to the lamp. do.

At this time, the power detector 530, as described above, the insulating base plate 541, the first winding pattern (542), the second winding pattern (543), the first leakage magnetic flux of the printed circuit board The current sensing transformer 540 includes a barrier layer 544 and a second leakage flux barrier layer 545. On the printed circuit board on which the current-sensing transformer 540 is formed, in addition to the current-sensing transformer, the switching unit 510, the DC / AC converter 520, and the transformer 550, which are the components of the lamp power supply described above, are compared. The unit 560, the controller 570, and the like are mounted.

As a result, the present invention forms a current-sensing transformer on a printed circuit board commonly used in liquid crystal display devices, eliminating the need for a separate current-sensing transformer, reducing the number of parts of the lamp power supply, and improving the manufacturing process. Simplification can reduce the production cost of the lamp power supply.

7 is an exploded perspective view of a liquid crystal display including a lamp power supply according to the present invention.

Referring to FIG. 7, the liquid crystal display includes a top chassis 300, an LCD panel 100, driving circuits 220 and 240, a lamp unit 400, a lamp power supply 500, and a plurality of optical sheets. 710, diffusion plate 720, mold frame 800, and bottom chassis 900.

The driving circuits 220 and 240 are connected to the LCD panel 100, include a gate side printed circuit board 224 for mounting a control IC and applying a predetermined gate signal to a gate line of the TFT substrate 120, and a control. A data side printed circuit board 244 for mounting an integrated circuit (IC) and applying a predetermined data signal to a data line of the TFT substrate 120, between the TFT substrate 120 and the gate side printed circuit board 224. And a gate side flexible printed circuit board 222 for connecting the TFTs, and a data side flexible printed circuit board 242 for connecting between the TFT substrate 120 and the data side printed circuit board 244.

The top chassis 300 is formed in the shape of a rectangular frame having a flat portion and a sidewall portion that are bent at right angles to prevent the LCD panel 100 and the driving circuit parts 220 and 240 from being separated from each other and to protect from the impact applied from the outside.

The lamp unit 400 includes a lamp 410 and a lamp socket 430 for mounting the lamp.

The lamp power supply 500 serves to generate power applied to the lamp to drive the lamp 410. In this case, as described above, the lamp power supply 500 includes a switching unit, a DC / AC converter, a transformer, a comparator and a controller, which are components of the lamp power supply, mounted on a printed circuit board. Likewise, by forming a current sensing transformer on a printed circuit board to mount various components of the lamp power supply, it is not necessary to use a separate current sensing transformer.

A plurality of optical sheets 710, a diffusion plate 720, a lamp unit 400, and a reflecting plate 600 are sequentially stacked from the base surface of the storage space formed under the mold frame 800, and are combined with the mold frame 800. Thus, a bottom chassis 900 for supporting the components is disposed under the mold frame.

What has been described above is only an exemplary embodiment of a current sensing transformer according to the present invention, a method of manufacturing the same, a lamp power supply device and a liquid crystal display device having the same, and the present invention is not limited to the above-described embodiment. As claimed in the claims, any person of ordinary skill in the art without departing from the gist of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

1A to 1C are a perspective view, a plan view, and a sectional view of a current sensing transformer according to a first embodiment of the present invention.

2A and 2B are perspective views illustrating a modification of the current sensing transformer according to the first embodiment of the present invention.

3A to 3C are a perspective view, a plan view, and a cross-sectional view of a current sensing transformer according to a second embodiment of the present invention.

4A to 4E are cross-sectional views of a manufacturing process of the current sensing transformer according to the present invention.

5A is a schematic block diagram of a lamp power supply including a current sensing transformer according to the present invention, FIG. 5B is a schematic circuit diagram of a power sensing unit, and FIG. 5C is a schematic perspective view of the current sensing transformer of FIG. 5B. to be.

FIG. 6 is a schematic configuration diagram of the DC / AC converter shown in FIG. 5A.

7 is an exploded perspective view of a liquid crystal display including a lamp power supply according to the present invention.

Description of the Related Art [0002]

510; A switching unit 520; DC / AC converter

530; A power detector 540; Current Sense Transformers

541; Insulating base plate 542; First winding pattern

543; Second winding pattern 544; First leakage magnetic flux prevention layer

545; The second leakage magnetic flux prevention layer 550; Transformer

560; Comparator 570; The control unit

Claims (19)

A printed circuit board including an insulating base board; A first winding pattern formed on one surface of the insulating base plate of the printed circuit board; A second winding pattern formed on the other surface of the insulating base plate of the printed circuit board; A first leakage magnetic flux prevention layer disposed on one surface of the insulating base plate of the printed circuit board and the first winding pattern; And And a second leakage flux prevention layer disposed on the other surface of the insulating base plate of the printed circuit board and the second winding pattern. The method of claim 1, And the first winding pattern and the second winding pattern are disposed to face each other. The method of claim 1, And the first winding pattern and the second winding pattern are made of a conductive material. The method of claim 3, The first winding pattern and the second winding pattern current sensing transformer, characterized in that the copper (copper). The method of claim 1, The first winding pattern and the second winding pattern is a current-sensing transformer, characterized in that formed in any one of a polygonal, circular and elliptical form. delete The method of claim 1, The first leakage flux prevention layer and the second leakage flux prevention layer is a current sensing transformer, characterized in that made of a ferrite polymer composite (ferrite polymer composite). The method of claim 1, The first leakage flux prevention layer and the second leakage flux prevention layer is formed in accordance with the shape of the first winding pattern and the second winding pattern current transformer. The method of claim 1, The printed circuit board is a current sensing transformer, characterized in that the double-sided printed circuit board or a multilayer printed circuit board. Preparing a printed circuit board; Forming a first winding pattern and a second winding pattern on one side and the other side of the printed circuit board, respectively; And And forming a first leakage flux prevention layer and a second leakage flux prevention layer, respectively, in the first winding pattern and the second winding pattern, respectively. The method of claim 10, Preparing the printed circuit board, A method of manufacturing a current-sense transformer, comprising the step of providing a copper foil laminated plate formed with a copper foil layer on one surface and the other surface of the insulating base plate. 12. The method of claim 11, Forming the first winding pattern and the second winding pattern, Forming a photoresist pattern of a predetermined type on each copper foil layer; Etching each of the copper foil layers; And And removing the photoresist pattern. The method of claim 10, The first leakage flux prevention layer and the second leakage flux prevention layer is a method of manufacturing a current-sense transformer, characterized in that made of a ferrite polymer composite (ferrite polymer composite). A DC / AC converter converting DC power supplied from the outside into AC power; A transformer for converting a level of an AC power output from the DC / AC converter; A power detector for detecting a level of AC power applied to the lamp; A comparator for comparing a power level sensed by the power detector and a reference power level to determine a power change; And A control unit for controlling an operation of the DC / AC converter according to the signal output from the comparator, wherein the power detector includes: A printed circuit board including an insulating base board; A first winding pattern formed on one surface of the insulating base plate of the printed circuit board; A second winding pattern formed on the other surface of the insulating base plate of the printed circuit board; A first leakage magnetic flux prevention layer disposed on one surface of the insulating base plate of the printed circuit board and the first winding pattern; And a current sensing transformer including a second leakage magnetic flux prevention layer disposed on the other surface of the insulating base plate of the printed circuit board and the second winding pattern. The method of claim 14, The power detection unit may include a first leakage flux prevention layer disposed on one surface of the insulating base plate of the printed circuit board and the first winding pattern; and the other surface of the insulating base plate of the printed circuit board and the second winding pattern. Lamp power supply further comprises a second leakage flux prevention layer disposed inside the. The method of claim 14, And a DC / AC converter, a transformer, a comparator, and a controller are mounted on the printed circuit board. The method of claim 14, The transformer includes a first winding and a second winding, And the power detector is connected to the first winding or the second winding of the transformer. The method of claim 14, And a switching unit connected to an input terminal of the DC / AC converter and controlling an output of the DC power supplied from the outside. At least one lamp, A DC / AC converter converting DC power supplied from the outside into AC power; A transformer for converting a level of an AC power output from the DC / AC converter; A power detector for detecting a level of AC power applied to the lamp; A comparator for comparing a power level sensed by the power detector and a reference power level to determine a power change; And a lamp power supply comprising a control unit for controlling an operation of the DC / AC converter according to the signal output from the comparison unit. And A liquid crystal display panel disposed on the backlight unit and configured to display an image; A printed circuit board including an insulating base board; A first winding pattern formed on one surface of the insulating base plate of the printed circuit board; A second winding pattern formed on the other surface of the insulating base plate of the printed circuit board; A first leakage magnetic flux prevention layer disposed on one surface of the insulating base plate of the printed circuit board and the first winding pattern; And a current sensing transformer including a second leakage magnetic flux prevention layer disposed on the other surface of the insulating base plate of the printed circuit board and the second winding pattern.

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