KR20080008743A - Backlight unit and liquid crystal display having the same - Google Patents

Abstract

A back light unit and an LCD(Liquid Crystal Display) including the same are provided to emit the heat generated at a spot light source rapidly, thereby enhancing the reliability of a product. A spot light source(110) is arranged along the side circumference of a light guide panel to transmit a light beam to the side of the light guide panel. The spot light source is mounted to a supporter(114) equipped to the light guide panel. The spot light source is a light emitting diode. The light emitting diode emits a white light beam. The supporter is made of the heat conduction materials to perform the heat exchange with the spot light source. The supporter is also curved and encompasses the rear of the spot light source and fixed to the edge of the light guide panel. The end of the supporter and the side edge of the light guide panel are fixed by the both-sided tape.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

1 is an exploded perspective view showing a first embodiment of a backlight unit according to the present invention.

FIG. 2 is a side cross-sectional view illustrating an installation state of the light guide plate and the point light source of FIG. 1.

3 is an exploded perspective view showing a second embodiment of the backlight unit according to the present invention.

4 is a side cross-sectional view illustrating an installation state of the light guide plate and the point light source of FIG. 3.

5 is a side view of the supporter according to the second embodiment.

6 is an exploded perspective view showing a liquid crystal display according to the present invention.

<Description of the names of the main parts of the drawings>

100: backlight unit 110: point light source

112: substrate 114: supporter

120: light guide plate 130: reflecting plate

140: diffusion plate 150: prism sheet

160: lower chassis 170: upper chassis

180: mold flame 190: liquid crystal display panel

The present invention relates to a backlight unit and a liquid crystal display including the same. More particularly, in implementing a large liquid crystal display, a point light source is used as a light source of the backlight unit and the thickness of the backlight unit is minimized. The present invention relates to a backlight unit and a liquid crystal display including the same, which can rapidly release heat and improve reliability of a product.

Recently, flat panel display devices such as liquid crystal displays (LCDs) and plasma display panels (PDPs) are rapidly developing in place of cathode ray tube (CRT) devices.

Among such flat panel display devices, the liquid crystal display device does not emit light, unlike a plasma display device, and thus requires a separate light source. Therefore, the liquid crystal display device may include various light sources according to the screen display method, and is generally classified into a direct type and an edge type according to the installation position of the light source, and in the case of a large screen such as a television, the direct type The edge type method is applied to a mobile device such as a mobile phone.

The direct type backlight unit includes a light source, a reflection plate disposed directly below the light source, a diffusion plate and a prism sheet disposed directly above the light source, and the reflection plate, a light source, a diffusion plate, and a prism sheet. By including the lower chassis, there is an advantage that can increase the brightness of the light irradiated to the liquid crystal display panel located on the upper portion of the backlight unit.

The edge type backlight unit includes a diffuser plate and a prism sheet having a light source disposed on one side of the light guide plate and disposed directly above the light guide plate, and a lower chassis to accommodate the light guide plate, the diffuser plate, and the prism sheet. As a result, there is an advantage that a backlight unit having a thickness thinner than that of the direct type backlight unit can be realized.

In particular, in the direct type, the luminance is excellent because the light source is provided directly below the diffusion plate, while the bright lines appear in the shape of the light source on the liquid crystal display panel. Therefore, in order to compensate for the uniformity of the brightness of the backlight unit, a diffuser plate that causes diffuse reflection must be spaced apart from the light source to some extent. However, since the thickness of the backlight unit is increased by the distance between the diffusion plate and the light source, it is difficult to maintain a thin structure, which is an advantage of the liquid crystal display.

In addition, as a light source of the direct type backlight unit, when a light emitting diode of a point light source is installed directly below a diffuser plate instead of a cold cathode fluorescent lamp having a line light source, light is emitted according to the area irradiated onto the liquid crystal display panel. There is a problem in that the number of installation of the diode increases and thus increases the production cost of the product.

The present invention is to solve the above problems, has a uniform brightness distribution so that it can be applied to a large screen such as a television with a minimum light source, it is possible to quickly release the heat generated from the point light source to improve the reliability of the product An object of the present invention is to provide an edge type backlight unit.

Another object of the present invention is to provide an LCD device having an ultra-thin type by applying an edge type backlight unit to a large liquid crystal display panel.

According to the technical idea of the present invention for achieving the above object, a light guide plate, a point light source disposed along the side circumference of the light guide plate for injecting light to the entire side surface of the light guide plate, and the point light source is mounted and It is achieved by a backlight unit comprising a supporter provided in the light guide plate.

Here, the point light source is preferably a light emitting diode.

In addition, the light emitting diode preferably emits white light.

The supporter is preferably formed of a thermally conductive material so as to exchange heat with the point light source.

In addition, the supporter is bent to surround the back of the point light source, one end is preferably fixed to the edge of the light guide plate.

In addition, one end of the supporter and the side edge of the light guide plate are preferably fixed by a double-sided tape.

The supporter may include a reflective surface formed to surround the rear of the point light source, a lower mounting surface and an upper mounting surface on which both ends of the reflective surface are bent to be fixed to an edge of the light guide plate, and on which the point light source is mounted. Do.

Here, the point light source is preferably arranged in two rows zigzag on the lower mounting surface and the upper mounting surface.

In addition, both ends of the lower mounting surface and the upper mounting surface preferably include a fastening surface bent inward to elastically press the edge of the light guide plate.

On the other hand, according to another technical idea of the present invention for achieving the above object, a light guide plate, a point light source disposed along the side circumference of the light guide plate to inject light to the entire side surface of the light guide plate, and the point light source is It is achieved by a liquid crystal display device comprising a backlight unit including a supporter mounted and fixed to the light guide plate, and a liquid crystal display panel for displaying an image using light supplied from the backlight unit.

Hereinafter, embodiments according to the present invention will be described in more detail with reference to the accompanying drawings.

First Example

1 is an exploded perspective view showing a first embodiment of a backlight unit according to the present invention, Figure 2 is a side cross-sectional view showing the installation state of the light guide plate and the point light source of FIG.

Referring to the drawings, the backlight unit 100 includes a point light source 110, a light guide plate 120 provided with the point light source 110 along a side circumference, and a lower portion of the light guide plate 120. And a reflector plate 130, a diffuser plate 140 and a prism sheet 150 disposed on the light guide plate 120, and the point light source 110, the light guide plate 120, and the reflector plate 130. The lower chassis 160 for accommodating the 140 and the prism sheet 150 may be further included.

The light guide plate 120 is formed of a transparent material having a substantially hexahedral shape of a flat plate and having a constant refractive index so that light emitted from the point light source 110 may be incident on the side surface of the light guide plate 120. The supporter 114 having the point light source 110 mounted on four side surfaces of the light guide plate 120 except for the top and bottom surfaces of the light guide plate 120 is installed.

Here, when the current flows through the pn junction structure of the semiconductor, the point light source 110 diffuses electrons of the n-type semiconductor into the p-type semiconductor region, holes of the p-type semiconductor into the n-type semiconductor region, and these electrons and holes are respectively It can be a light emitting diode that emits light when it is recombined with holes and electrons in the region of. In addition, the light emitting diode may be mounted on the supporter 114 in a state where the light emitting diode is mounted on one or both surfaces of the point light source circuit board 112 on which the circuit pattern is formed.

The point light source circuit board 112 is connected to a plurality of driving voltage generators (not shown) for generating a driving voltage and is electrically connected to the point light source 110.

Here, the light emitting diode mounted on the supporter 114 may be a light emitting diode that is continuously mounted along the longitudinal direction of the supporter 114 and emits white light toward the side of the light guide plate 120. The light emitting diodes emitting red, green, and blue light to the side of the light guide plate 120 may be continuously mounted to the light guide plate 120.

The heat generated by the point light source 110 requires rapid heat dissipation because the brightness of the point light source 110 is reduced and the life is shortened. Therefore, the supporter 114 is made of a thermally conductive material (for example, metal) so that the heat generated by the point light source 110 can be quickly discharged. While being formed to surround, the reflective surface may be formed to maximize the light utilization efficiency of the point light source (110).

That is, the supporter 114 includes a mounting surface 116 on which the point light source 110 is mounted and one end is fixed to an edge of the light guide plate 120, and a heat transfer area is wrapped around the rear of the point light source 110. It includes a reflective surface 118 bent vertically at the other end of the mounting surface 116 to maximize. Here, one end of the mounting surface 116 and one of the upper and lower edges of the light guide plate 120 may be fixed by a double-sided tape.

The reflective plate 130 reflects the light emitted from the point light source 110 to the upper surface of the light guide plate 120 to increase the light utilization efficiency, and when the light is emitted to the upper surface of the light guide plate 120, the entire upper surface is uniform. The light guide plate 120 may be positioned below the light guide plate 120 to have a luminance distribution.

The reflective plate 130 generally uses a polyester film, and has a structure in which a reflective layer and a packing layer are coated on both sides of the polyester film to prevent incident light from leaking out and to improve brightness characteristics with a high reflection layer structure having excellent concealability. The reflective plate 130 may be attached to the lower chassis 160 by an adhesive, a double-sided adhesive tape, or may be integrally formed with the lower chassis 160.

The diffusion plate 140 directs the light incident from the point light source 110 toward the front of the liquid crystal display panel provided above the backlight unit 100, and diffuses the light to have a uniform distribution in a wide range. To irradiate the liquid crystal display panel. As such a diffusion plate 140, it is preferable to use a film made of a transparent resin coated with a predetermined light diffusion member on both surfaces.

The prism sheet 150 serves to change the light incident at an oblique angle among the light incident on the prism sheet 150 through the diffusion plate 140 to be emitted vertically. This is because the light efficiency increases when the light incident on the liquid crystal display panel is perpendicular to the liquid crystal display panel. Therefore, at least one prism sheet 150 may be disposed between the diffuser plate 140 and the liquid crystal display panel to vertically convert the light emitted from the diffuser plate 140.

In addition, the lower chassis 160 has a rectangular parallelepiped having an upper surface open to cover and protect side and bottom surfaces of the point light source 110, the light guide plate 120, the reflector plate 130, the diffusion plate 140, and the prism sheet 150. The light source 110, the light guide plate 120, the reflecting plate 130, the diffusion plate 140, and the prism sheet 150 are sequentially arranged to be formed in a box shape. Here, a point light source 110, a light guide plate 120, a reflector plate 130, a diffusion plate 140, and a prism sheet 150 may be installed in a mold frame formed in a substantially rectangular frame shape instead of the lower chassis.

As described above, the supporter 114 including the point light source 110 is installed on four side surfaces of the light guide plate 120 except for the top and bottom surfaces thereof, so that the light guide plate 120 has a uniform luminance distribution. Accordingly, when the backlight unit of the present invention is applied to a large liquid crystal display panel such as a television, it is possible to implement a liquid crystal display device having a thinner thickness than the conventional direct type backlight unit.

In addition, the installation of the point light source can be minimized compared to the conventional direct type backlight unit using the point light source, thereby reducing the production cost.

In addition, since the supporter on which the point light source is mounted is made of a thermally conductive material, heat emission of the point light source irradiating light onto the light guide plate may be rapidly performed to improve the reliability of the product. In particular, when the supporter and the lower chassis are in direct contact, heat generated from the point light source is transferred to the lower chassis through the supporter. Therefore, when the contact area between the supporter and the lower chassis is increased, heat emission of the point light source is more quickly performed. Can be achieved.

2nd Example

3 is an exploded perspective view showing a second embodiment of the backlight unit according to the present invention, Figure 4 is a side cross-sectional view showing the installation state of the light guide plate and the point light source of Figure 3, Figure 5 is a supporter according to a second embodiment Side view. In the following description, a description overlapping with the above-described first embodiment will be omitted.

Referring to the drawings, the backlight unit 100 includes two points of light sources 210a and 210b installed along the side circumference of the light guide plate 120 and a reflector 130 disposed below the light guide plate 120. ) And a diffuser plate 140 and a prism sheet 150 disposed on the light guide plate 120, and in some cases, the point light source 110, the light guide plate 120, and the reflector plate 130. A lower chassis 160 for accommodating the 140 and the prism sheet 150 may be further included.

In particular, the point light sources 210a and 210b disposed on four sides of the light guide plate 120 are mounted in two rows, so that the brightness of the light guide plate 120 is improved, and the supporter 214 is formed to be thin and easy to install. To this end, the supporter 214 has a shape of approximately " 이루어진 " made of a thermally conductive material to quickly heat transfer the point light sources 210a and 210b.

That is, the supporter 214 includes a lower mounting surface 216a and an upper mounting surface 216b such that the point light sources 210a and 210b are arranged in two rows, and the point light sources 210a and 210b are point light circuit boards. Mounted on the lower mounting surface 216a and the upper mounting surface 216b in a state of being mounted on the 212a and 212b, respectively, the point light source 210a, the lower mounting surface 216a and the upper mounting surface 216b. 210b) is mounted to be symmetrical up and down. Here, the mounting positions of the point light sources 210a and 210b mounted on the lower mounting surface 216a and the upper mounting surface 216b are preferably arranged in a zigzag manner so as not to interfere with each other.

The lower mounting surface 216a and the upper mounting surface 216b are connected by the reflective surface 218, and the reflective surface 218 is connected to the half light source 210a or 210b to maximize the heat exchange area. The slope 218 is formed to surround the back of the point light sources 210a and 210b.

In addition, the supporter 214 is preferably made of a metal material having an elastic force so that the supporter 214 can be easily installed when the supporter 214 is installed on the light guide plate 120. In particular, one end of the lower mounting surface 216a and the upper mounting surface 216b is bent inward to form fastening surfaces 215a and 215b for pressing the edge of the light guide plate.

Accordingly, when the supporter 214 is installed on the light guide plate 120, the fastening surfaces 215a and 215b of the lower mounting surface 216a and the upper mounting surface 216b are opened, and the top and bottom edges of the light guide plate 120 are opened. Since it is fixed by holding, the supporter 214 mounted with the point light source (210a, 210b) is installed along the side circumference of the light guide plate 120 can be installed without a separate fixing member, the point light source is 2 Even if arranged along the lateral circumference of the light guide plate in a row, the supporter may have a small thickness increase and become thin.

3rd Example

6 is an exploded perspective view showing a liquid crystal display according to the present invention. In the following description, overlapping descriptions of the above-described first and second embodiments will be omitted. In the third embodiment, the supporter 114 equipped with the point light source 110 described in the first embodiment will be omitted. Explain by reference.

Referring to the drawings, the liquid crystal display device 300 includes a point light source 110 mounted on four sides of the light guide plate 120 except for the top and bottom surfaces of the light guide plate 120 so that light is incident on the entire side surface of the light guide plate 120. Wraps the backlight unit 100 provided with the supporter 114, the mold frame 180 for accommodating the backlight unit 100, the liquid crystal display panel 190, and a predetermined area and sides of the backlight unit 100. An upper chassis 195 for the purpose.

The liquid crystal display panel 190 includes a thin film transistor substrate 192, a data side and gate side tape carrier package (TCP) 194a and 194b connected to the thin film transistor substrate 192; A data side and gate side printed circuit board 196a and 196b connected to the data side and gate side tape carrier packages 194a and 194b, a color filter substrate 198 corresponding to the thin film transistor substrate 192, and a thin film And a liquid crystal layer (not shown) injected between the transistor substrate 192 and the color filter substrate 198. The display device may further include a polarizer (not shown) formed to correspond to the upper portion of the color filter substrate 198 and the lower portion of the thin film transistor substrate 192.

Here, the color filter substrate 198 is a substrate in which RGB pixels, which are color pixels in which a predetermined color is expressed while light passes, are formed by a thin film process. A common electrode (not shown) made of a transparent conductor such as indium tin oxide (ITO) or indium zinc oxide (IZO), which is a transparent conductive thin film, is formed on an entire surface of the color filter substrate 198. .

The thin film transistor substrate 192 is a transparent glass substrate in which thin film transistors (TFTs) and pixel electrodes are formed in a matrix form. The data line is connected to the source terminal of the thin film transistors, and the gate line is connected to the gate terminal. In addition, a pixel electrode (not shown) made of a transparent electrode made of a transparent conductive material is connected to the drain terminal. When an electrical signal is input to the data line and the gate line, each thin film transistor is turned on or turned off to apply an electrical signal necessary for pixel formation to a drain terminal.

That is, when power is applied to the gate terminal and the source terminal of the thin film transistor substrate 192 as described above and the thin film transistor is turned on, an electric field is formed between the pixel electrode and the common electrode of the color filter substrate 198. Due to this electric field, the arrangement of the liquid crystal injected between the thin film transistor substrate 192 and the color filter substrate 198 is changed, and the light transmittance is changed according to the changed arrangement to obtain a desired image.

The data side and gate side tape carrier packages 194a and 194b are respectively connected to data lines and gate lines of the thin film transistor substrate 192 to apply a data driving signal and a gate driving signal to the thin film transistor. In this case, an integrated circuit (IC) may be mounted in the data side and gate side tape carrier packages 194a and 194b. The data side and gate side printed circuit boards 196a and 196b are connected to the data side and gate side tape carrier packages 194a and 194b to apply external image signals and gate drive signals.

The backlight unit 100 may include a point light source 110 for generating light, a light guide plate 120 provided with the point light source 110 along a side circumference, and a reflector plate 130 disposed below the light guide plate 120. ), A diffuser plate 140 and a prism sheet 150 disposed on the light guide plate 120, a supporter 114 on which the point light source 110 is mounted, a light guide plate 120, a reflector plate 130, and a diffusion plate. Lower chassis 160 for receiving plate 140 and prism sheet 150 is included.

The mold frame 180 is formed in a rectangular frame shape and includes a flat portion 182 and sidewall portions 186 bent at right angles therefrom. A mounting portion 184 may be formed on the flat portion 182 to allow the liquid crystal display panel 190 to be mounted thereon. The seating portion 184 may use a fixing protrusion for contacting each of the edge side surfaces of the liquid crystal display panel 190 and aligning them, or may be formed using a predetermined stepped step surface. The light guide plate 120, the reflector plate 130, the diffusion plate 140, and the prism sheet 150 are installed between the mold frame 180 and the lower chassis 160.

The upper chassis 195 is configured in the form of a rectangular window frame having a flat portion and sidewall portions bent at right angles therefrom. The planar portion of the upper chassis 195 supports a portion of an edge of the liquid crystal display panel 190 at a lower portion thereof, and the sidewall portion is coupled to face the sidewalls of the lower chassis 160.

In particular, since the supporter 114 having the point light source 110 is mounted on four side surfaces of the light guide plate 120 except for the top and bottom surfaces of the light guide plate 120, the light guide plate has a uniform luminance distribution, and thus can be applied to a large liquid crystal display panel. Therefore, a thin liquid crystal display device can be realized. For example, while a conventional large liquid crystal display device has a backlight unit of several tens of mm (35 mm) thick, the present invention can implement a backlight unit of several mm (2 mm) thick, thereby significantly reducing the thickness of the liquid crystal display. It can be made thinner.

In addition, the installation of the point light source can be minimized compared to the conventional direct type backlight unit using the point light source, thereby reducing the production cost.

On the other hand, the present invention is not limited only to the above-described embodiment, but can be modified and modified within the scope not departing from the gist of the present invention, it should be seen that such modifications and variations are included in the technical idea of the present invention. do.

In the backlight unit and the liquid crystal display using the same according to the present invention, a direct supporter having the point light source is installed such that the point light source is disposed on four side surfaces of the light guide plate except for the top and bottom surfaces of the light guide plate. Since the installation of the point light source can be minimized as compared to the backlight unit of the present invention, the cost of production can be reduced, and heat is emitted from the point light source through the supporter, thereby improving the reliability of the product.

In addition, when the point light source is installed on four sides of the light guide plate, since the light guide plate has a uniform luminance distribution, a liquid crystal display device having a thinner thickness may be realized as compared with the conventional direct type backlight unit.

Claims (10)

The light guide plate, A point light source disposed along a side circumference of the light guide plate to inject light into the entire side surface of the light guide plate; And a supporter on which the point light source is mounted and provided in the light guide plate. The backlight unit of claim 1, wherein the point light source is a light emitting diode. The backlight unit of claim 2, wherein the light emitting diode emits white light. The backlight unit of claim 1, wherein the supporter is formed of a thermally conductive material so as to exchange heat with the point light source. The backlight unit of claim 1, wherein the supporter is bent to surround the back of the point light source, and one end is fixed to an edge of the light guide plate. The backlight unit of claim 5, wherein one end of the supporter and the side edge of the light guide plate are fixed by double-sided tape. The method of claim 1, wherein the supporter includes a reflective surface formed to surround the rear of the point light source, the lower mounting surface and the upper mounting surface on which both ends of the reflective surface is bent to be fixed to the edge of the light guide plate and the point light source is mounted Backlight unit, characterized in that. The backlight unit of claim 7, wherein the point light sources are arranged in two rows on the lower mounting surface and the upper mounting surface, and are mounted in a zigzag manner. The backlight unit of claim 7, wherein the point light source is mounted on the lower mounting surface and the upper mounting surface and is arranged in two rows. A backlight unit including a light guide plate, a point light source disposed along a side circumference of the light guide plate to inject light into the entire side surface of the light guide plate, and a supporter on which the point light source is mounted and fixed to the light guide plate; And a liquid crystal display panel which displays an image by using the light supplied from the backlight unit.

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