KR20090084446A - Backlight unit and liquid cristal display device usimg the same - Google Patents

Abstract

A backlight unit and a liquid crystal display device using the same are provided to improve brightness by effectively supplying light to a liquid crystal panel. In a reflector light guide plate(108), a space in which light of a light source can be reflected is formed. Light refracted by gas is emitted toward an upper part of the reflector light guide plate. The reflector light guide plate has a light incident part(106) and holes(116). In the light incident part, a surface corresponding to the light source is opened. The opened surface receives the light. The plurality of holes has different sizes. A plurality of holes is formed on an upper part of the reflector light guide plate. Light of the light source is emitted through the plurality of holes.

Description

BACKLIGHT UNIT AND LIQUID CRISTAL DISPLAY DEVICE USIMG THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a backlight unit and a liquid crystal display using the same, which can reduce weight, material cost, and improve luminance.

Recently, various flat panel display devices that can reduce weight and volume, which are disadvantages of cathode ray tubes, have emerged. Such a flat panel display includes a liquid crystal display, a field emission display, a plasma display panel, a light emitting device, and the like.

The liquid crystal display device displays an image by adjusting the light transmittance of the liquid crystal using an electric field. To this end, the liquid crystal display includes a liquid crystal panel having a liquid crystal cell, a backlight unit for irradiating light to the liquid crystal panel, and a driving circuit for driving the liquid crystal cell.

In this case, the liquid crystal panel of the liquid crystal display device is a light-receiving element that displays an image by adjusting the amount of light source coming from the outside, so a backlight unit, which is a separate light source for irradiating light to the liquid crystal panel, is required. The backlight unit is divided into an edge method and a direct method according to the installation position.

First of all, the direct type method is mainly developed as the size of the liquid crystal display device is increased to 20 inches or more. A plurality of lamps are arranged in a row on the lower surface of the diffuser plate to direct light directly to the front of the LCD panel. will be.

The direct method is mainly used for a large screen liquid crystal display device requiring high luminance because the light utilization efficiency is higher than that of the edge method.

In addition, the edge method is that the lamp unit is installed on the side of the light guide plate for guiding the light, the lamp unit is inserted into both ends of the lamp to emit light, the lamp holder to protect the lamp and the outer circumferential surface of the lamp and one side It is provided with a lamp reflecting plate fitted to the side of the light guide plate to reflect the light emitted from the lamp toward the light guide plate.

The edge method in which the lamp unit is installed on the side of the light guide plate is applied to a relatively small liquid crystal display device such as a monitor of a laptop computer and a desktop computer, and has good uniformity of light and a long service life. It is advantageous to thin the liquid crystal display device.

1 is a view showing a conventional backlight unit.

Referring to FIG. 1, a conventional edge type backlight unit includes a lamp 10 for supplying light, a light guide plate 20 for guiding light from the lamp 10 upward, and a light guide plate 20 not shown on the light guide plate 20. It comprises a prism sheet 40 which is an optical sheet for supplying light to the liquid crystal panel.

In the backlight unit, the light emitted from the lamp 10 is reflected inside the light guide plate 20, and the light is emitted upward by the pattern 30 formed on upper and lower surfaces of the light guide plate. In this case, the light emitted from the light guide plate 20 is collected by the prism sheet 40, which is an optical sheet of the backlight unit, to provide an effect of increasing the luminance of the liquid crystal panel (not shown).

As such, the optimal light emitted through the light guide plate and the prism sheet to increase the brightness of the liquid crystal panel should be emitted at an angle of α (15 ° to 20 °) from the upper surface of the light guide plate based on a normal line. At the light surface of the light, light is incident at an angle of θ (25 ° to 30 °) and irradiated to the liquid crystal panel. However, light emitted from the upper surface of the light guide plate of the conventional backlight unit is mostly emitted at β (60 ° to 80 °) angle, as shown in FIGS. 2 and 3, and the light emitted is effectively emitted to the liquid crystal panel. Failure to supply these causes a decrease in the luminance of the liquid crystal display device.

In addition, the light guide plate constituting the conventional backlight unit mainly uses acrylic resin (Polymethyl-methacylate (PMMA)) or polycarbonate (Propylene Carbonate (PC)). As shown in Table 1, the acrylic resin or polycarbonate-based light guide plate has a specific gravity of about 1.2 g / cm 3, thereby increasing its weight and manufacturing cost when the liquid crystal display is enlarged.

Since the shrinkage ratio of the acrylic resin or polycarbonate light guide plate is about 0.4 to 0.08, and the light absorption is about 0.15, the thickness of the light guide plate is not uniform when the liquid crystal display is enlarged, and the luminance due to the light absorption is decreased. Becomes

In order to solve the above problems, the present invention is to provide a backlight unit and a liquid crystal display using the same to reduce the weight and material costs of the backlight unit and to effectively supply light to the liquid crystal panel to improve the brightness.

The backlight unit according to the present invention comprises at least one light source; The light guide plate may include a reflector light guide plate in which a space in which light from the light source may be reflected is formed so that light refracted by the gas is emitted upward.

The reflector LGP includes: a light incident part to which a surface corresponding to the at least one light source is opened so that the light is incident; An upper portion of the reflector LGP includes a plurality of holes having different sizes from which light of the light source is emitted.

Each surface of the reflector LGP may be formed with a plurality of patterns through which light of the light source may be refracted.

The reflector LGP is formed of any one of polyethylene terephthalate, polycarbonate, and MCPET.

The angle of the reflector LGP is characterized in that formed by plating, coating or painting any one of Cr, Ag and Br or a mixture thereof.

The upper portion of the reflector light guide plate is characterized in that it is formed transparent.

At least one partition is formed inside the reflector LGP.

The partition wall is characterized in that a plurality of patterns in which the light of the light source is refracted is formed.

The reflector LGP may be formed in a tunnel shape in which a surface corresponding to the light source has a curvature.

The backlight unit and the liquid crystal display using the same according to the present invention can reduce the material cost and the weight by forming the reflector LGP using a reflector having a low specific gravity in the form of a box formed of empty spaces.

In addition, the present invention forms a front surface of the reflector light guide plate with a reflective material without light loss, and forms a plurality of holes to improve the light collection efficiency in a plurality of optical sheets disposed on the reflector light guide plate, thereby providing uniform light to the liquid crystal. By supplying to the panel, the brightness of the liquid crystal display device can be improved.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

3 is a diagram illustrating a backlight unit according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the backlight unit 100 according to an embodiment of the present invention may reflect at least one light source 102, a light source housing 104 that protects the light source, and light from the light source 102. A space is formed and includes a reflector light guide plate 108 through which light refracted by a gas is emitted upward, and a plurality of optical sheets 118 diffuse and condense light emitted from the reflector light guide plate 108.

At least one light source 102 is disposed to face the light incident portion 106 of the reflector light guide plate 108. Here, the at least one light source 102 generates light by receiving a light source voltage from an inverter (not shown) and irradiates the light incident portion 106 of the reflector LGP 108. The at least one light source 102 may be a fluorescent lamp, wherein the fluorescent lamp includes a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED). ) Can be configured to any one. The light emitting diodes (LEDs) may be formed of red (R), green (G), and blue (B) light emitting diodes (LEDs) that emit light of red (R), green (G), and blue (B) light. have.

The light source housing 104 is formed to enclose at least one or more light sources 102. Here, the light source housing 104 protects the light source 102, and totally reflects the light emitted by the light source 102 to guide the light incident part 106 of the semiconductor light guide plate 108.

As illustrated in FIG. 4, the reflector LGP 108 is formed to have a space in which light of a light source may be reflected therein in the form of a box for manufacturing a lightweight and thin shape. In addition, the reflector LGP 108 is formed of a reflector having an upper surface, a lower surface, a rear surface, and a side surface having a reflectance of 98% or more. Here, the reflector LGP 108 does not reduce the amount of light irradiated from the at least one light source 102 to the light incident part 106, and is diffusely reflected or totally reflected by a refracting material and a reflecting material by the gas to reflect the reflector LGP 108. Outgoing to the top. In this case, the reflector LGP 108 is formed of any one of polyethylene terephthalate (PET), polycarbonate (PC), and micro-forming polyethylene terphthalate (MCPET), or any one of Cr, Ag, and Br or mixed thereof. One reflective material is plated, coated, or painted to form diffuse or total reflection of light. The reflector LGP 108 may be formed as a reflective polarizer capable of producing reflection and polarization components.

The reflector light guide plate 108 may have an opening corresponding to at least one light source 102 and the light incident portion 106 may receive light, and the light of the light source 102 may be emitted above the reflector light guide plate 108. It is configured to include a plurality of holes 116 having different sizes.

The light incident part 106 is formed by opening a corresponding surface of the reflector light guide plate corresponding to the at least one light source 102. Here, the light incident part 106 may allow light incident from the light source 102 to enter a space formed inside the semiconductor light guide plate 108.

The plurality of holes 116 are formed by piercing the upper surface of the reflector LGP 108. Here, the plurality of holes 116 allow the light supplied through the light incidence unit 106 to be reflected inside the reflector LGP 108 and emitted upward. In this case, the plurality of holes 116 are formed to have different sizes according to the light emitted so that the light reflected from the inside of the reflector LGP 108 may be uniformly supplied to the plurality of optical sheets 118.

The reflector LGP 108 formed as described above may include a plurality of refractive patterns having a triangular, elliptical, circular, or quadrangular shape that refracts the light of the light source 102. The upper surface of the reflector LGP 108 corresponding to the liquid crystal panel (not shown) may be formed to be transparent to allow light to pass therethrough. In addition, an upper surface of the reflector LGP 108 may be attached to an anisotropic film that can change the transmittance according to the incident angle.

The plurality of optical sheets 118 enhance the luminance and uniformity of the emitted light emitted from the reflector LGP 108 and irradiate the liquid crystal panel (not shown). To this end, the plurality of optical sheets 118 may include at least one diffusion sheet 110 for diffusing the light emitted from the reflector LGP 108 to the entire area, and at least one light condensing light diffused by the diffusion sheet 110. The prism sheets 112 and 114 are comprised. Here, the laminated structure of each of the at least one diffusion sheet 110 and the prism sheets 112 and 114 may be sequential, non-sequential or alternating to improve brightness and uniformity of the light.

As described above, in the backlight unit using the reflector LGP 108, the light distributions supplied to the plurality of optical sheets 118 disposed on the reflector LGP 108 are a plurality of optical sheets. The light converging efficiency of the prism sheet can be improved by being distributed in an area between 0 ° to 40 ° and 50 ° to 80 °, which can improve the condensing efficiency of the prism sheet. In this way, the light condensing efficiency is improved and the light passing through the prism sheet is supplied to the liquid crystal panel to improve the brightness of the liquid crystal display device.

Therefore, the backlight unit of the present invention can reduce the material cost and the weight by forming the reflector LGP with a reflector having a low specific gravity in the form of a box formed of empty space therein. In addition, the entire surface of the reflector light guide plate is formed of a reflective material with no light loss, and a plurality of holes are formed on the upper part of the reflector light guide plate to improve the light condensing efficiency of light supplied to the plurality of optical sheets. By supplying, the brightness of the liquid crystal display device can be improved.

6 is a view illustrating a reflector light guide plate according to a second embodiment of the present invention.

First, since the backlight unit according to the second embodiment of the present invention has the same configuration as the first embodiment of the present invention except for the reflector LGP, the description of the same configuration will be replaced with the above description.

Referring to FIG. 6, the reflector LGP 158 according to the second exemplary embodiment of the present invention is formed to have a space in which light of a light source may be reflected therein in the form of a box to manufacture a light weight and a thin film. do. In addition, the reflector LGP 158 is formed of a reflector having an upper surface, a lower surface, a rear surface, and a side surface having a reflectance of 98% or more. Here, the reflector LGP 158 does not reduce the amount of light irradiated from the at least one light source 102 to the light incident portion 156, and is diffusely reflected or totally reflected by a refracting material and a reflective material by the gas, thereby reducing the amount of light reflected from the reflector LGP 108. Outgoing to the top. In this case, the reflector LGP 158 is formed of any one of polyethylene terephthalate (PET), polycarbonate (PC), and micro-forming polyethyleneterphthalate (MCPET), or any one of Cr, Ag, and Br, or a mixture thereof. One reflective material is plated, coated, or painted to form diffuse or total reflection of light. The reflector LGP 158 may be formed of a reflective polarizer capable of producing reflection and polarization components.

The reflector LGP 158 has a light incident portion 156 through which a surface corresponding to the at least one light source 102 is opened and the light is incident, and the light of the light source 102 emits light on the reflector LGP 158. It includes a plurality of holes 116 having a different size and a plurality of partitions 158 formed inside the reflector LGP 158.

The light incident part 156 is formed by opening a corresponding surface of the reflector LGP corresponding to the at least one light source 102. Here, the light incident part 156 may allow the light incident from the light source 102 to enter the space formed inside the reflector LGP 158.

The plurality of holes 166 are formed by piercing the upper surface of the reflector LGP 158 that does not correspond to the plurality of partition walls 158. Here, the plurality of holes 166 allow the light supplied through the light incidence part 156 to be reflected inside the reflector LGP 158 and output upward. In this case, the plurality of holes 166 may be formed in different sizes according to the light emitted so that the light reflected from the inside of the reflector LGP 158 may be uniformly supplied to the plurality of optical sheets 118.

The partition walls 158 are formed inside the reflector light guide plate 158. Here, the plurality of partitions 158 improves the degree of condensing of light emitted through the plurality of holes 166. In addition, when the light source is a light emitting diode (LED) of red (R), green (G), and blue (B), the plurality of barrier ribs 158 are well mixed to provide uniform light to the liquid crystal panel. In this case, the plurality of partitions 158 include a plurality of refractive patterns through which light may be refracted.

The reflector LGP 158 formed as described above may include a plurality of refractive patterns having a triangular, elliptical, circular, or quadrangular shape that refracts the light of the light source 102. The upper surface of the reflector LGP 158 corresponding to the liquid crystal panel (not shown) may be formed to be transparent to allow light to pass therethrough. In addition, an upper surface of the reflector LGP 158 may be attached with an anisotropic film that can change the transmittance according to the incident angle.

7 is a view illustrating a reflector light guide plate according to a fourth embodiment of the present invention.

Referring to FIG. 7, in the backlight unit according to the third exemplary embodiment, the light guide plate 206 having a tunnel shape having a curved shape 204 is formed on the top surface of the backlight unit in order to improve the condensing degree of light incident through the light incident part 202. It can be formed as.

8 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 8, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel 306 for displaying an image by adjusting a transmittance of liquid crystal, and a backlight unit 100 for irradiating light to the liquid crystal panel. do.

First, the backlight unit 100 includes a backlight unit according to the first to third embodiments of the present invention described above.

The liquid crystal panel 306 is formed of a lower substrate 302 and an upper substrate 304 which are bonded to each other. In this case, the lower substrate 302 and the upper substrate 304 is configured to include a spacer (not shown) and a liquid crystal layer (not shown) to keep their gap constant.

The upper substrate 304 includes at least three color filters including red, green, and blue, a separation of each color filter, a black matrix defining a pixel cell, a common electrode supplied with a common voltage, and the like. The common electrode may be formed on the lower substrate 302 according to the mode of the liquid crystal.

The lower substrate 302 includes a plurality of data lines and a plurality of gate lines formed to cross each other, a thin film transistor (TFT), and a thin film transistor formed in each pixel cell region defined by crossing the data lines and the gate lines. And a pixel electrode connected to the TFT). The thin film transistor TFT supplies the image signal from the data line to the liquid crystal cell in response to the gate pulse from the gate line.

The liquid crystal cell (not shown) may be equivalently represented as a liquid crystal capacitor because the liquid crystal cell includes a common electrode facing each other with a liquid crystal layer interposed therebetween and a pixel electrode connected to the thin film transistor TFT. The liquid crystal cell also includes a storage capacitor for maintaining the image signal charged in the liquid crystal capacitor until the next image signal is charged.

As described above, the backlight unit and the liquid crystal display using the same according to the embodiment of the present invention can reduce the material cost and reduce the weight by forming the reflector LGP using a reflector having a small specific gravity in the form of a box formed of empty spaces. . In addition, the present invention forms a front surface of the reflector light guide plate with a reflective material without light loss, and forms a plurality of holes to improve the light collection efficiency in a plurality of optical sheets disposed on the reflector light guide plate, thereby providing uniform light to the liquid crystal. By supplying to the panel, the brightness of the liquid crystal display device can be improved.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

1 is a view showing a conventional backlight unit.

FIG. 2 is a view illustrating a light distribution diagram of light emitted through a light guide plate in a conventional backlight unit. FIG.

3 is a view illustrating a backlight unit according to an exemplary embodiment of the present invention.

4 is a view showing a reflector light guide plate according to a first embodiment of the present invention;

5 is a view showing a light distribution of the reflector LGP according to an embodiment of the present invention.

6 is a view showing a reflector light guide plate according to a second embodiment of the present invention;

7 is a view illustrating a reflector light guide plate according to a third embodiment of the present invention.

8 illustrates a liquid crystal display according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

106: light incident part 108: reflector light guide plate

116: multiple holes

Claims (10)

At least one light source; And a reflector light guide plate having a space in which the light of the light source is reflected to emit the light refracted by the gas. The method of claim 1, The reflector light guide plate, A light incident part to which a surface corresponding to the at least one light source is opened so that the light is incident; And a plurality of holes having different sizes at which light of the light source is emitted from the upper part of the reflector LGP. The method of claim 1, And a plurality of patterns on each surface of the reflector light guide plate through which light of the light source is refracted. The method of claim 1, The reflector light guide plate is formed of any one of polyethylene terephthalate, polycarbonate, MCPET backlight unit. The method of claim 1, The angle of the reflecting light guide plate is a backlight unit, characterized in that formed by plating, coating or painting any one of Cr, Ag and Br or mixed. The method of claim 1, The upper portion of the reflector light guide plate is characterized in that the transparent unit is formed. The method of claim 1, At least one partition wall is formed inside the reflector LGP. The method of claim 5, wherein The barrier unit is a backlight unit, characterized in that a plurality of patterns that can be refracted light of the light source is formed. The method of claim 1, The reflector light guide plate is a backlight unit, characterized in that the surface corresponding to the light source is formed in a tunnel shape having a curvature. A liquid crystal panel which displays an image by adjusting the transmittance of the liquid crystal; A liquid crystal display device comprising any one of the backlight units according to claim 1, wherein the liquid crystal panel is irradiated with light.

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