KR20100134431A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to improve the assembly of a backlight unit by excluding an aluminum plate for electromagnetic shielding. CONSTITUTION: A liquid crystal display panel is arranged in matrix format, and a backlight unit is placed at a lower portion of the liquid crystal display panel. The backlight unit includes at least one lamp which irradiates light onto a liquid crystal display panel, and a cover shield(155) encloses a printed circuit board(170) and a trans(176) to protect the board and the trans.

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

The present invention relates to a liquid crystal display device, and more particularly, to an inverter circuit for supplying power to a backlight and a liquid crystal display device including the same.

In today's information society, display is more important as a visual information transmission medium, and in order to gain a major position in the future, it is necessary to satisfy requirements such as low power consumption, thinness, light weight, and high definition.

The display itself emits light such as a cathode ray tube (CRT), an electroluminescent (EL), a light emitting diode (LED), a vacuum fluorescent display (VFD), a field emission display (FED), and a plasma display panel (PDP). And it can be divided into a non-light-emitting type, such as a liquid crystal display that does not emit light itself.

Liquid crystal display is a device that displays images by using optical anisotropy of liquid crystal. Since it is better than CRT and has a small average heat dissipation compared to CRT of the same screen size, it generates less heat than PDP. It is in the spotlight as an apparatus.

The liquid crystal used in the liquid crystal display device is not a light emitting material that emits light itself, but a light source that modulates the amount of light coming from the outside to display on the screen, so that a separate light source for irradiating light to the liquid crystal display panel In other words, it requires a backlight unit.

Hereinafter, the liquid crystal display device will be described in detail.

Unless otherwise specified, the portion where the lamp is located in the completed liquid crystal display device is referred to as a relatively lower portion, and the portion where the liquid crystal display panel is located is referred to as an upper portion.

A liquid crystal display device is a liquid crystal display panel which largely injects liquid crystal between an array substrate and a color filter substrate to output an image, and is installed at a lower portion of the liquid crystal display panel to emit light over the entire surface of the liquid crystal display panel. The backlight unit includes a plurality of case parts for fixing and coupling the liquid crystal display panel and the backlight unit to each other.

The function of the backlight unit is to make plane light with uniform brightness from a lamp used as a light source, and the backlight unit is largely divided into an edge type and a direct type according to the position of the light source with respect to the display surface. Are distinguished. Among these, the direct type backlight unit is widely used in large liquid crystal display devices because of its high light utilization efficiency, simple handling, and no limitation on the size of the display surface.

In this case, the direct type backlight unit includes a plurality of lamps, a cover bottom for accommodating the lamps, a reflective sheet installed inside the cover bottom, and an inverter printed circuit board disposed outside the cover bottom. ; PCB). A diffuser plate is attached to the cover bottom accommodating the lamps, and a plurality of optical sheets are stacked on the diffuser plate.

In this case, the inverter printed circuit board is disposed on the rear surface of the cover bottom, and an inverter circuit including a transformer for driving lamps is mounted on the inverter printed circuit board.

In the general liquid crystal display device configured as described above, the leakage magnetic flux generated from the transformer causes an eddy current to be generated in the cover bottom, which is a magnetic material, and thus heat is locally generated in the cover bottom to increase the temperature. As a result, the power consumption of the backlight unit increases.

FIG. 1 is a cross-sectional view schematically illustrating a phenomenon in which an eddy current is induced in a cover bottom in a general liquid crystal display, and FIG. 2 is a cross-sectional view schematically showing a leakage magnetic flux blocked by an aluminum plate.

1 and 2 illustrate a state in which the liquid crystal display is turned upside down so that the cover bottom is located below and the cover shield is located above.

As shown in FIG. 1, a backlight unit of a general liquid crystal display device includes a lamp (not shown), a cover bottom 50 for accommodating the lamp, an inverter including a printed circuit board 70 and a transformer 76, and the A cover shield 55 is provided to surround and protect the printed circuit board 70 and the transformer 76.

In this case, the inverter including the printed circuit board 70 and the transformer 76 is disposed on the opposite side of the position where the liquid crystal display panel is located on the cover bottom 50, and the transformer 76 is the printed circuit board 70. The DC voltage is input from the circuit to generate an AC voltage, which is a power source for driving the lamp.

At this time, as described above, the magnetic flux is leaked from the transformer 76, and thus, an eddy current is induced in the cover bottom 50 by an interlinking component with the cover bottom 50, which is a magnetic material, thereby causing a power loss. do.

In order to prevent this, as shown in FIG. 2, the aluminum plate 80 for electromagnetic shielding is attached to the rear surface of the cover bottom 50 between the printed circuit board 70 and the cover bottom 50.

In this case, the aluminum plate 80 prevents the magnetic flux leaking from the transformer 76 from being bridged with the cover bottom 50. That is, the magnetic flux leaking from the transformer 76 is attached to the rear surface of the cover bottom 50. It is blocked by the aluminum plate 80 so that no eddy current is induced in the cover bottom 50.

However, since the aluminum plate 80 must be attached to the cover bottom 50 where the transformer 76 of the inverter is located by using double-sided tape, the assemblability of the backlight unit is disadvantageous and the tact time increases. There will be a cost for adding parts and a cost for adding processes.

In addition, when the LCD is driven in a high temperature and high humidity environment for a long time, the aluminum plate 80 attached by the double-sided tape may be separated from the cover bottom 50.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display device which improves the assemblability of a backlight unit and reduces power consumption of the backlight unit.

Other objects and features of the present invention will be described in the configuration and claims of the invention which will be described later.

In order to achieve the above object, the liquid crystal display device of the present invention comprises a liquid crystal display panel in which the pixels are arranged in a matrix form; A backlight unit disposed under the liquid crystal display panel and including at least one lamp irradiating light to the liquid crystal display panel; An inverter including a printed circuit board and a transformer for driving the lamp; A cover bottom disposed on a rear surface of the lamp to accommodate the lamp; And an electromagnetic shielding layer formed inside the printed circuit board to prevent magnetic flux leaking from the transformer from being bridged with the cover bottom.

As described above, the liquid crystal display device of the present invention forms an electromagnetic shielding layer inside the inverter printed circuit board to shield the magnetic field generated by the transformer, thereby reducing the power consumption of the backlight unit by about 11.9 W (6.4%). to provide.

In addition, the liquid crystal display of the present invention improves the assemblability of the backlight unit by eliminating the aluminum plate for electromagnetic shielding, and provides an effect of reducing the cost.

Hereinafter, exemplary embodiments of a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a cross-sectional view schematically illustrating that leakage magnetic flux is blocked in the liquid crystal display according to the exemplary embodiment of the present invention. For convenience of description, the liquid crystal display is inverted so that the cover bottom is located at the bottom and the cover shield is at the top. It is shown.

As shown in the figure, the backlight unit of the liquid crystal display according to the exemplary embodiment of the present invention includes a lamp (not shown), a cover bottom 150 for accommodating the lamp, a printed circuit board 170, and a transformer 176. A cover shield 155 is provided to cover and protect the inverter and the printed circuit board 170 and the transformer 176.

In this case, the inverter including the printed circuit board 170 and the transformer 176 is disposed on the opposite side of the position where the liquid crystal display panel is located on the cover bottom 150, the transformer 176 is a printed circuit board 170 The DC voltage is input from the circuit to generate an AC voltage, which is a power source for driving the lamp.

At this time, the electromagnetic shielding layer 175 made of a metal such as aluminum or copper is formed in the printed circuit board 170 according to the embodiment of the present invention so that the magnetic flux leaking from the transformer 176 is connected to the cover bottom 150. That is, the magnetic flux leaking from the transformer 176 is blocked by the electromagnetic shielding layer 175 formed inside the printed circuit board 170 so that no eddy current is induced in the cover bottom 150. .

In particular, the liquid crystal display according to the exemplary embodiment of the present invention applies a printed circuit board 170 having an electromagnetic shielding layer 175 therein instead of attaching an aluminum plate for electromagnetic shielding to the cover bottom 150. In addition to improving the assemblability of the backlight unit, it is possible to reduce the cost. In addition, even if it is not attached to the cover bottom 150, even if the drive for a long time does not cause a problem that the electromagnetic shielding layer 175 falls by the external environment such as high temperature or high humidity.

In addition, by blocking the magnetic flux leaking from the transformer 176 as described above, it provides an effect of reducing the power consumption of the backlight unit, which will be described in detail with reference to the drawings.

4 is a table showing the results of testing the power consumption of the backlight unit in the liquid crystal display according to an embodiment of the present invention, comparing the liquid crystal display device shielding the electromagnetic using a general liquid crystal display device and an aluminum plate together It is shown.

As shown in the figure, in the case of a general liquid crystal display device (Comparative Example 1) without electromagnetic shielding, the power consumption is 184.8W, whereas the liquid crystal display device (Comparative Example 2) using an aluminum plate and the embodiment of the present invention are used. In the case of the liquid crystal display according to the present invention, the power consumption is measured to be 172.8W and 172.9W, respectively.

In particular, it can be seen that the liquid crystal display according to the embodiment of the present invention is reduced by about 11.9 W (6.4%) compared to the general liquid crystal display (Comparative Example 1) without electromagnetic shielding.

Hereinafter, a liquid crystal display according to an exemplary embodiment of the present invention including an inverter printed circuit board having such a feature will be described in detail with reference to the accompanying drawings.

5 is an exploded perspective view schematically illustrating a structure of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in the figure, the liquid crystal display device according to an embodiment of the present invention, the liquid crystal display panel 110 in which the pixels are arranged in a matrix form, the liquid crystal display panel 110 is disposed below the liquid crystal display panel 110 It includes a backlight unit including at least one lamp 130 for irradiating the light and various case components such as the top case 160 and the cover bottom 150.

At this time, although not shown in detail in the drawing, the liquid crystal display panel 110 is largely the liquid crystal layer (110) formed between the color filter substrate 110a and the array substrate 110b and between the color filter substrate 110a and the array substrate 110b. liquid crystal layer).

The color filter substrate 110a is formed between a color filter composed of a plurality of sub-color filters for implementing red (R), green (G), and blue (B) colors and the sub-color filter. And a black matrix for blocking light passing through the liquid crystal layer, and a transparent common electrode for applying a voltage to the liquid crystal layer.

In addition, the array substrate 110b is formed on the pixel region and the thin film transistor, which is a switching element formed in a cross region of the gate line and the data line, the plurality of gate lines and data lines, which are arranged in a vertical direction. It consists of a pixel electrode.

As such, a common electrode and a pixel electrode are formed on the liquid crystal display panel 110 to which the color filter substrate 110a and the array substrate 110b are bonded, respectively, between the color filter substrate 110a and the array substrate 110b. An electric field is applied to the formed liquid crystal layer.

Therefore, when the voltage of the data signal applied to the pixel electrode is controlled while the voltage is applied to the common electrode, the liquid crystal of the liquid crystal layer rotates by dielectric anisotropy according to the electric field between the common electrode and the pixel electrode. For example, characters or images are displayed by transmitting or blocking light for each pixel.

In this case, the backlight units are arranged side by side to the plurality of lamps 130 for irradiating light to the liquid crystal display panel 110, the plurality of lamps 130 are disposed on the back of the plurality of lamps 130 The cover bottom 150 accommodates the reflection sheet 141 attached to the inner surface of the cover bottom 150 to reflect light generated from the plurality of lamps 130 toward the liquid crystal display panel 110, and the cover bottom. An inverter printed circuit board 170 disposed on an outer bottom surface of the 150, a diffusion plate 143 for diffusing light incident from the plurality of lamps 130, and irradiating the liquid crystal display panel 110 with the light. A plurality of optical sheets 144 stacked on the diffuser plate 143.

In this case, the liquid crystal display according to the embodiment of the present invention is a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a hot cathode fluorescent lamp (Hot Cathode Fluorescent Lamp) as a light source. Various light sources such as HCFL and Light Emitting Diode (LED) can be used, and when a direct type is applied, they are arranged side by side in the cover bottom 150 and both sides are supported by a support side (not shown). Supported.

In addition, the reflective sheet 141 reflects the light generated from the lamps 130 to be irradiated toward the liquid crystal display panel 110, thereby improving light efficiency, and the diffusion plate 143 includes a plurality of lamps ( The light incident from the 130 is diffused to prevent the luminance difference from appearing at the position of the lamps 130 and the position between the lamps 130.

In addition, the optical sheets 144 convert the propagation path of the light incident from the diffuser plate 143 to be perpendicular to the liquid crystal display panel 110 and diffuse the light so that the efficiency of the light irradiated onto the liquid crystal display panel 110 is increased. Improves the light uniformity. For this purpose, the optical sheets 144 include one or more prism sheets and diffusion sheets.

The liquid crystal display panel 110 and the backlight unit configured as described above are surrounded by a guide panel (not shown), and the wrapped liquid crystal display panel 110 and the backlight unit are disposed on the inner step of the main support 140. They will be stacked one by one.

The top edge of the liquid crystal display panel 110 is compressed by the top case 160, and the top case 160 is coupled to the guide panel 140.

The top case 160 is formed in the shape of a rectangular band having a flat portion and a side portion bent at right angles, and the top case 160 forms a top edge of the liquid crystal display panel 110 and a side surface of the cover bottom 150. Wrap it around and fix it. In addition, the cover shield 155 is fastened to the back surface of the cover bottom 150 to protect the printed circuit board 170 and the transformer (not shown).

The structure of the backlight unit in the liquid crystal display according to the exemplary embodiment of the present invention configured as described above will be described in detail with reference to the accompanying drawings.

FIG. 6 is a cross-sectional view schematically illustrating one side of a backlight unit in the liquid crystal display shown in FIG. 5. For convenience of description, the liquid crystal display is turned upside down such that a cover bottom is positioned below and a cover shield is positioned above. have.

7 is a plan view illustrating an inverter printed circuit board according to an exemplary embodiment of the present invention.

As shown in the figure, the backlight unit accommodates a plurality of lamps 130, a reflector plate 141, and the plurality of lamps 130 to increase the efficiency of light emitted from the plurality of lamps 130. The cover bottom 150 includes an inverter including a printed circuit board 170 and a transformer 176, and a cover shield 155 that surrounds and protects the printed circuit board 170 and the transformer 176.

In this case, the inverter including the printed circuit board 170 and the transformer 176 is disposed on the opposite side of the position where the liquid crystal display panel is located on the cover bottom 150, the transformer 176 is a printed circuit board 170 The DC voltage is input from the circuit to generate an AC voltage, which is a power source for driving the lamp.

For reference, the inverter circuit receives a DC power from an external power source to switch to an AC signal, a transformer for boosting the AC signal generated from the switching unit and supplying the boosted AC signal to the lamps, lamps And a control unit for detecting a current supplied to the field and controlling the switching unit. There are two methods of driving lamps through the inverter circuit: an individual driving method for driving one lamp and one transformer in one-to-one correspondence, and a parallel driving method for driving a plurality of lamps and one transformer in many-to-one correspondence. .

In case of individual driving method, one transformer is used to drive one lamp, so it is possible to drive with a transformer of small capacity. On the contrary, in the case of the parallel driving method, a single transformer is used to drive a plurality of lamps, so the transformer used must be of high power.

In addition, a first connector 132 is disposed on the printed circuit board 170 to be connected to the second connector 134 coupled to the end of the wire 135, and a lamp driving voltage is applied to the lamps 130.

Although not shown in detail, the transformer 176 is a core that guides the magnetic flux, a bobbin in which the primary coil and the secondary coil are wound, and both sides of the bobbin are located in the primary. The first and second pins 131a and 131b, which are terminals connected to the coil and the secondary coil, respectively, are configured.

At this time, as described above, the electromagnetic shielding layer 175 is formed inside the printed circuit board 170 according to the embodiment of the present invention to prevent the magnetic flux leaking from the transformer 176 from being bridged with the cover bottom 150. That is, the magnetic flux leaking from the transformer 176 is blocked by the electromagnetic shielding layer 175 formed inside the printed circuit board 170 so that no eddy current is induced in the cover bottom 150.

Here, the electromagnetic shielding layer 175 may be made of a metal such as aluminum or copper having a low permeability to increase the shielding effect of the magnetic flux. Referring to FIG. 7, the electromagnetic shielding layer 175 according to an embodiment of the present invention. The silver may be inserted only into the printed circuit board 170 at the position where the transformer 176 is attached. However, the present invention is not limited thereto, and the electromagnetic shielding layer 175 according to the embodiment of the present invention may be inserted into the front surface of the printed circuit board 170.

In particular, the liquid crystal display according to the exemplary embodiment of the present invention applies a printed circuit board 170 having an electromagnetic shielding layer 175 therein instead of attaching an aluminum plate for electromagnetic shielding to the cover bottom 150. In addition to improving the assemblability of the backlight unit, it is possible to reduce the cost. In addition, even if it is not attached to the cover bottom 150, even if the drive for a long time does not cause a problem that the electromagnetic shielding layer 175 falls by the external environment such as high temperature or high humidity.

In addition, as described above, blocking the magnetic flux leaking from the transformer 176 provides an effect of reducing power consumption of the backlight unit.

8 is a view schematically showing a cross-sectional structure of an inverter printed circuit board according to an embodiment of the present invention.

As shown in the figure, the printed circuit board includes conductive films 171a and 171b on a plate that is an insulator, and resins 172a and 172b are formed by forming a circuit pattern on the conductive films 171a and 171b. After the glass fiber matrix 173 was pressed in, the conductive films 171a and 171b were formed on the surface of the cured resins 172a and 172b by firing, and then a circuit pattern was produced by an etching process. do.

That is, the printed circuit board according to the embodiment of the present invention includes at least one layer of matrix member 173 made of fiber, resin materials 172a and 172b for supporting the matrix member 173 and at least one layer of conductive film. 171a, 171b.

In this case, the matrix member 173 may be a fiber, glass fiber, and the glass fiber is preferably formed in a woven form. However, the present invention is not limited thereto, and any matrix member that can be employed in a printed circuit board can be used.

The matrix member 173 may be press-fitted by the resin materials 172a and 172b to be buried in the resin materials 172a and 172b.

The conductive films 171a and 171b are coated on the surfaces of the resin materials 172a and 172b by a conductive metal such as copper.

In the printed circuit board according to the exemplary embodiment of the present invention having the above structure, an electromagnetic shielding layer 175 formed of a metal such as aluminum or copper is formed in the matrix member 173 so that the magnetic flux leaking from the transformer may bridge with the cover bottom. It can be prevented.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

1 is a cross-sectional view schematically illustrating a phenomenon in which an eddy current is induced in a cover bottom in a general liquid crystal display device.

2 is a cross-sectional view schematically illustrating that a leakage magnetic flux is blocked by an aluminum plate in a general liquid crystal display device.

3 is a cross-sectional view schematically illustrating that leakage magnetic flux is blocked in the liquid crystal display according to the exemplary embodiment of the present invention.

4 is a table illustrating a result of testing power consumption of a backlight unit in a liquid crystal display according to an exemplary embodiment of the present invention.

5 is an exploded perspective view schematically illustrating a structure of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 6 is a cross-sectional view schematically illustrating one side of a backlight unit in the liquid crystal display shown in FIG. 5.

7 is a plan view illustrating an inverter printed circuit board according to an exemplary embodiment of the present invention.

8 is a schematic cross-sectional view of an inverter printed circuit board according to an exemplary embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

110: liquid crystal display panel 130: lamp

150: cover bottom 155: cover shield

170: inverter printed circuit board 171a, 171b: conductive film

172a and 172b: Resin Material 173: Matrix Member

175: electromagnetic shielding layer 176: transformer

Claims (7)

A liquid crystal display panel in which pixels are arranged in a matrix form; A backlight unit disposed under the liquid crystal display panel and including at least one lamp irradiating light to the liquid crystal display panel; An inverter including a printed circuit board and a transformer for driving the lamp; A cover bottom disposed on a rear surface of the lamp to accommodate the lamp; And And an electromagnetic shielding layer formed inside the printed circuit board to prevent magnetic flux leaking from the transformer from being bridged with a cover bottom. The method of claim 1, wherein the backlight unit A plurality of lamps for irradiating light onto the liquid crystal display panel; A cover bottom disposed at the rear of the plurality of lamps to accommodate the plurality of lamps; A reflection sheet attached to an inner surface of the cover bottom to reflect light generated from a plurality of lamps toward a liquid crystal display panel; An inverter printed circuit board disposed on an outer bottom surface of the cover bottom; A diffuser plate for diffusing light incident from the plurality of lamps to irradiate the liquid crystal display panel; And And a plurality of optical sheets stacked on the diffusion plate. The liquid crystal display device of claim 1, further comprising a cover shield that surrounds and protects the printed circuit board and the transformer. The liquid crystal display device of claim 1, wherein the electromagnetic shielding layer is made of a metal such as aluminum or copper having a low permeability to increase a shielding effect of magnetic flux. The liquid crystal display of claim 1, wherein the electromagnetic shielding layer is formed in a printed circuit board at a position where the transformer is attached. The liquid crystal display of claim 1, wherein the electromagnetic shielding layer is formed on an entire surface of the printed circuit board. The method of claim 1, wherein the printed circuit board At least one layer of matrix member comprised of fibre; A resin material for supporting the matrix member; And And at least one conductive film, wherein the electromagnetic shielding layer is formed in the matrix member.

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