KR101502368B1 - Backlight unit and liquid cristal display device usimg the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display device capable of increasing light-incident efficiency of a light guide plate and improving production efficiency.

The backlight unit of the present invention includes at least one light source; A light guide plate including a light-incident portion through which light emitted from the light source is incident, and changing the light incident through the light-incident portion into a plane light; A reflector disposed on a back surface of the light guide plate to surround the light source and reflect light to the light guide plate; And a bottom cover surrounding the outer circumferential surface of the reflector, wherein the reflector in a region corresponding to the region between the light source and the light incident portion of the light guide plate has an inclined portion, and the light incident portion of the light guide plate is inclined in a direction opposite to the inclined portion of the reflector Structure.

According to the present invention, by integrating the support main, the light source housing, the reflector, and the light source housing, the manufacturing cost can be reduced by reducing the design cost and the assembling process. In addition, by forming the light guide plate having a sloped surface so as to have an inclined surface to increase the light incident surface area, the light incident efficiency for receiving light from the light source can be increased to provide a high brightness to the liquid crystal panel.

Light guide plate, reflector, light source housing, support main, inclination, curved surface

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of increasing light-incident efficiency of a light guide plate and improving production efficiency.

2. Description of the Related Art In recent years, various flat panel display devices that can reduce weight and volume, which are disadvantages of cathode ray tubes (CRTs), are emerging. Examples of such flat panel display devices include a liquid crystal display, a field emission display, a plasma display panel, and a light emitting device.

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 device includes a liquid crystal panel having a liquid crystal cell, a backlight unit for emitting light to the liquid crystal panel, and a driving circuit for driving the liquid crystal cell.

At this time, since the liquid crystal panel of the liquid crystal display device is a light-receiving device that displays an image by adjusting the amount of the light source coming from the outside, a backlight unit which is a separate light source for irradiating light to the liquid crystal panel is required. Such a backlight unit is classified into an edge type and a direct type according to the installed position.

First, the direct-type liquid crystal display device has begun to be developed as the size of the liquid crystal display device becomes larger than 20 inches, and a plurality of lamps are arranged in a row on the lower surface of the diffusion plate to direct light directly to the front surface of the LCD panel will be.

This direct-down scheme is mainly used for a large-screen liquid crystal display device which requires a high luminance because the utilization efficiency of light is higher than that of the edge scheme.

In the edge system, a lamp unit is installed on a side surface of a light guide plate for guiding light. The lamp unit includes a lamp that emits light, a lamp holder inserted in both ends of the lamp to protect the lamp, And a lamp reflector that is fitted to the side surface of the light guide plate and reflects the light emitted from the lamp toward the light guide plate.

The edge method in which the lamp unit is installed on the side surface of the light guide plate is applied to a liquid crystal display device having a comparatively small size such as a monitor of a laptop type computer and a desktop type computer and has a good uniformity of light, Which is advantageous for reducing the thickness of the liquid crystal display device.

1 is a view showing a conventional liquid crystal display device in an edge mode.

1, a conventional liquid crystal display comprises a bottom cover 12, a lamp 18 for supplying light from one side of the bottom cover 12, and a lamp 18 for protecting the lamp 18 A light guide plate 20 provided below the liquid crystal panel 10 for guiding the light of the lamp 18 to the liquid crystal panel 10 and a light guide plate 20 disposed below the light guide plate 10, A reflective sheet 14 for reflecting the light back to the front surface of the light guide plate 30, an optical sheet 22 laminated on the light guide plate 20 and supplying uniform light to the liquid crystal panel 10, A top cover 26 and a top cover 26 for covering the non-display area of the liquid crystal panel 10 and the side surface of the butter cover 12; And a support main 24 for supporting the top cover 26 while maintaining a gap generated by the provision of the liquid crystal panel 10 between the bottom cover 24.

In the edge type liquid crystal display device having such a configuration, the thickness of the light guide plate 20 provided inside the liquid crystal display device is reduced in order to produce a lightweight and thin liquid crystal display device. This reduces the area of light entering the light incident portion 28 of the light guide plate 20 through which the light of the lamp 18 arrives and decreases the light efficiency and thereby reduces the amount of light supplied to the liquid crystal panel 10 A problem occurs.

Further, since the support main, the reflection sheet, and the lamp housing constituting the backlight unit are separately designed and assembled, the design cost and the assembling process are increased, resulting in defective assembly.

In order to solve the above problems, the present invention provides a liquid crystal display device capable of increasing the light incident efficiency of the light incident portion of a light guide plate installed in a liquid crystal display have.

A backlight unit according to an embodiment of the present invention includes at least one light source; A light guide plate for converting the light of the light source into a plane light; A reflector for surrounding the light source and reflecting light to the light guide plate; And a bottom cover surrounding the outer circumferential surface of the reflector.

According to another aspect of the present invention, there is provided a backlight unit comprising: at least one light source; A light guide plate for converting the light of the light source into a plane light; A curved surface support main body having a curved surface for protecting the light source; And a bottom cover that houses the light source, the light guide plate, and the curved surface support main, and has an inclined surface between the light source and the support main.

The backlight unit and the liquid crystal display device using the same according to the present invention integrate the support main, the reflector, and the light source housing, which are conventionally separately configured, with the support main, the light source housing, the reflector, and the light source housing, The manufacturing cost can be reduced.

In addition, by forming the light guide plate having a sloped surface so as to have an inclined surface to increase the light incident surface area, the light incident efficiency for receiving light from the light source can be increased to provide a high brightness to the liquid crystal panel.

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

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

2, the backlight unit 150 according to the first embodiment of the present invention includes at least one light source 118, a light guide plate 120 that converts the light of the light source 118 into plane light, a light source 118 And a bottom cover 112 that surrounds the outer circumferential surface of the reflector 114. The bottom cover 112 includes a light guide plate 120,

The at least one light source 118 is disposed at one side edge portion of the bottom cover 112 so as to face the light entrance portion 140 of the light guide plate 120. Here, the light source 118 generates a light by receiving a light source voltage from an inverter (not shown), and irradiates the generated light to the light-incident portion 140 of the light guide plate 120. At least one light source 118 may be a fluorescent lamp. The fluorescent lamp may include a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode (LED) As shown in FIG. The light emitting diode (LED) may be formed of red (R), green (G), and blue (B) light emitting diodes (LEDs) emitting light of red (R), green have.

The light guide plate 120 is disposed on the plane reflecting portion 130 of the reflector 114. [ Here, the light guide plate 120 is formed to have a thin thickness of the light guide plate 120 due to the lightweight and thin object of the backlight unit. Therefore, in order to secure an area of the light-incident portion 140 of the reduced light guide plate 120, the light-incident portion 140 is formed to have an inclined surface. The light guide plate 120 scatters the light emitted from the light source 118 and emits the light to the front surface of the light guide plate 120 without reducing the light collection efficiency of the light received from the light source 118 in the light incident portion 140. That is, the light guide plate 120 converts the incident light incident from the light source 118 into plane light and irradiates the plurality of optical sheets 122. At this time, the light guide plate 120 may be formed of a plastic material such as PMA (poly methylmethacrylate) or a plastic material or a heat resistant glass material in a flat type or a wedge type.

On the other hand, the light guide plate 120 may be a prism light guide plate having a tilted back surface and a prism-type exit surface having an obtuse and a convex shape formed in a linear or circular shape. That is, a plurality of prism patterns having hills and valleys may be formed on the exit surface of the light guide plate 120.

3, the reflector 114 includes a light source housing part 132 for protecting the light source 118 and totally reflecting the light from the light source 118 to the light guide plate 120, A planar reflector 130 for reflecting the light emitted to the backside of the light guide plate 120 to the front and an inclined portion 134 having a slope between the light source housing 132 and the planar reflector 130, . The reflector 114 is coated with silver to cover the base material such as SUS, brass, aluminum, PET or the like in order to increase the reflectance, and is coated with titanium to prevent deformation due to heat generated in the light source 118 .

The light source housing part 132 is formed to surround the light source 118. The light source housing part 132 protects the light source 118 and totally reflects light emitted from the light source 118 and guides the light to the light entrance part 140 of the light guide plate 120.

The planar reflector 130 is formed so that the light guide plate 120 is seated. The planar reflector 130 reflects the light that is emitted from the light source 118 and directed to the back surface of the light guide plate 120 to the front surface of the light guide plate 120 among the light incident on the light entrance portion 140 of the light guide plate 120. [ .

The inclined portion 134 is formed to have an inclined surface between the light source housing portion 132 and the planar reflection portion 130. The inclined portion 134 is formed to have a sloped surface between the light source housing portion 132 and the planar reflection portion 130 by forming the light guide plate 120 to be thin and lightweight and thin in the liquid crystal display device. This inclined surface can concentrate the light irradiated from the light source 118 on the light-incident portion 140 of the light guide plate 120. [

The bottom cover 112 is formed to surround the outer circumferential surface of the reflector 114. Here, the bottom cover 112 may be formed of a material having a high thermal conductivity so that heat generated from the backlight unit 150 may be emitted to the outside.

The plurality of optical sheets 122 improve the brightness and uniformity of the outgoing light emitted from the light guide plate 120 and irradiate the unshown liquid crystal panel. To this end, the plurality of optical sheets 122 include at least one diffusion sheet for diffusing the outgoing light of the light guide plate 120 to the entire area, and at least one prism sheet for condensing the light diffused by the diffusion sheet do. Here, the laminated structure of each of the at least one diffusion sheet and the prism sheet may be sequential, non-sequential or alternating for the purpose of improving brightness and uniformity of light.

Such a backlight unit can reduce manufacturing cost by reducing the design cost and the assembling process by integrating the reflector plate and the light source housing which are conventionally separately formed. By forming an inclined sloped surface at the light-incoming portion of the light guide plate, the light receiving efficiency can be increased by increasing the area for receiving light from the light source.

4 is a view illustrating a backlight unit according to a second embodiment of the present invention.

4, the backlight unit 250 according to the second embodiment of the present invention includes a light source 218, a light guide plate 220 for converting the light of the light source 218 into a plane light, a light source 218, A curved surface support main body 224 having a curved surface for protecting the curved surface of the light guide plate 220 and a curved surface support main body 228 for accommodating the light source and the light guide plate and curved surface support main bodies 218, 220 and 224, And a bottom cover 212 having a bottom cover 212.

The bottom cover 212 is formed to accommodate the backlight unit 250. Here, the bottom cover 212 is formed with an inclined surface between the light source 218 and the light-incoming portion 240 of the light guide plate 220 for lightweight and thin shape of the liquid crystal display device. At this time, the bottom cover 212 may be formed of a material having a high thermal conductivity so that heat generated from the backlight unit 250 may be emitted to the outside.

The at least one light source 218 is disposed at one side edge portion of the bottom cover 212 so as to face the light-incident portion 240 of the light guide plate 220. Here, at least one light source 218 generates light by receiving a light source voltage from the outside, and irradiates the generated light to the light-incident portion 240 of the light guide plate 220. At this time, the at least one light source 218 may be a fluorescent lamp. The fluorescent lamp may be a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode As shown in FIG. The dual LED may be formed of red (R), green (G), and blue (B) light emitting diodes (LEDs) emitting red (R), green (G) .

The light guide plate 220 is disposed on the flat surface of the bottom cover 212 on which the reflection sheet 214 is installed. Here, the light guide plate 220 is formed to have a small thickness for the light weight and thinness of the liquid crystal display device. Accordingly, the light incident portion 240 of the reduced light guide plate 220 is formed with an inclined surface to secure an area. The light guide plate 220 scatters the light emitted from the light source 218 and outputs the light to the front surface of the light guide plate 220 without reducing the light collection efficiency of the light received from the light source 218 in the light incident portion 240. That is, the light guide plate 220 converts incident light incident from the light source 218 into plane light and irradiates the plurality of optical sheets 222. At this time, the light guide plate 220 may be formed of a plastic material such as PMA (poly methylmethacrylate) or a resin material or a heat resistant glass material in a flat type or a wedge type

On the other hand, the light guide plate 220 may be a prism light guide plate having a tilted rear surface and a prism-shaped exit surface having an obtuse and a convex shape formed in a linear or circular shape. That is, a plurality of prism patterns having hills and valleys may be formed on the exit surface of the light guide plate 220.

The reflective sheet 214 is provided on the back surface of the bottom cover 212. Here, the reflective sheet 214 reflects the light emitted to the back surface 220 of the light guide plate 220 to the front surface. In order to increase the reflectivity, the reflective sheet 214 is coated with silver on the base materials such as SUS, brass, aluminum, and PET, and a titanium coating is applied to prevent deformation due to heat generated in the light source 218. [ can do.

The curved surface support main 224 is accommodated in one side of the bottom cover 212. 5, the curved surface support main portion 224 includes a light source housing portion 206 for protecting the light source 218 and for totally reflecting the light from the light source 218, and a liquid crystal panel (not shown) And a line hole 234 in which a signal line 228 for supplying an electrical signal to the light source 218 is installed.

The light source housing part 206 is formed to surround the light source 218. The light source housing part 206 protects the light source 218 and totally reflects the light emitted from the light source 218 and guides the light to the light incident part 240 of the light guide plate 220. At this time, the light source housing part 206 is formed into a curved surface so that the light is condensed in the light source 208 and guided to the light-incident part 240 of the light guide plate 220.

Further, a reflective material may be plated or coated on the curved surface of the light source housing part 206, and the reflective material may be formed of any one of Cr, Ag, and Br, or may be formed by mixing them.

The panel supporting portion 230 is formed so that a liquid crystal panel (not shown) can be seated. Here, the panel supporting portion 23 is formed in a rectangular frame shape to edge the edge of the liquid crystal panel.

The line hole 234 is formed in the upper portion of the curved surface support main 234. Here, the line hole 234 is formed so that a signal line 228 through which an electrical signal can be transmitted to the light source 218 can be installed.

The plurality of optical sheets 222 improve the brightness and uniformity of the outgoing light emitted from the light guide plate 220 and irradiate the liquid crystal panel not shown. To this end, the plurality of optical sheets 222 include at least one diffusion sheet for diffusing the outgoing light of the light guide plate 220 to the entire area, and at least one prism sheet for condensing the light diffused by the diffusion sheet do. Here, the laminated structure of each of the at least one diffusion sheet and the prism sheet may be sequential, non-sequential or alternating for the purpose of improving brightness and uniformity of light.

Such a backlight unit integrates the support main and the light source housing, which have conventionally been separately constructed, so that the manufacturing cost can be reduced by reducing the design cost and the assembling process. By forming an inclined sloped surface at the light-incoming portion of the light guide plate, the light receiving efficiency can be increased by increasing the area for receiving light from the light source.

FIG. 6 is a view illustrating a liquid crystal display device according to an embodiment of the present invention, and FIG. 7 is a sectional view of I-I 'of a liquid crystal display device according to an embodiment of the present invention.

6 and 7, the liquid crystal display device 100 includes a liquid crystal panel 100 for displaying an image by adjusting the transmittance of light and a backlight unit 150 for irradiating the liquid crystal panel 100 with light.

The liquid crystal panel 100 includes a lower substrate 102 and an upper substrate 104 which are bonded together to face each other. At this time, a spacer (not shown) and a liquid crystal layer (not shown) are provided between the lower substrate 102 and the upper substrate 104 to keep the gap therebetween constant.

The upper substrate 104 includes at least three color filters including red, green, and blue, a separation matrix of each color filter, a black matrix defining a pixel cell, and a common electrode to which a common voltage is supplied. Here, the common electrode may be formed on the lower substrate 102 in accordance with the mode of the liquid crystal.

The lower substrate 102 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 (TFT) formed in each pixel cell region defined by intersecting data lines and gate lines And a pixel electrode connected to the TFT. The thin film transistor TFT supplies an image signal from the data line to the liquid crystal cell in response to a gate pulse from the gate line.

Since the liquid crystal cell (not shown) is composed of a common electrode facing the liquid crystal layer and a pixel electrode connected to the thin film transistor (TFT), it can be equivalently expressed by a liquid crystal capacitor. The liquid crystal cell also includes a storage capacitor for holding the image signal charged in the liquid crystal capacitor until the next image signal is charged.

A lower polarizing film 136 facing the plurality of optical sheets 122 is attached to the back surface of the lower substrate 102. The lower polarizing film 136 polarizes the light emitted from the plurality of optical sheets 122. At this time, the transmission axis of the lower polarizing film 136 is arranged at a predetermined angle so as to coincide with the alignment direction of the liquid crystal layer.

An upper polarizing film 138 is attached to the upper portion of the upper substrate 104. The upper polarizing film 138 polarizes the light transmitted through the liquid crystal layer and the color filter array substrate. At this time, the transmission axis of the upper polarizing film 138 is arranged to be perpendicular to the transmission axis of the lower polarizing film 136.

The top cover 126 covers the front edges of the liquid crystal panel 100 disposed on the backlight unit 150 and the sides of the support main 124 and the bottom cover 112. The top cover 126 is provided with a flat portion that covers the non-display area, i.e., the edge except the display area of the liquid crystal panel 100, and a flat portion that is bent perpendicularly from the flat portion, And a side surface surrounding the side surface.

The support main 124 is provided at the upper end of the bottom cover 212 surrounding the outer circumferential surface of the reflector 114. The support main 124 is provided at a rectangular rim of the liquid crystal panel 100 and includes a signal line 128 for supplying an electrical signal to the light source 118 through a line hole formed in the upper portion of the support main 124 Respectively.

The bottom cover 112 is formed to surround the outer circumferential surface of the reflector 114. Here, the bottom cover 112 may be formed of a material having a high thermal conductivity so that heat generated from the backlight unit 150 may be emitted to the outside.

The backlight unit according to the first and second embodiments and the liquid crystal display using the same according to the first and second embodiments integrate the support main, the reflector, and the light source housing, which are conventionally separately configured, with the support main body, the light source housing, , The manufacturing cost can be reduced by reducing the design cost and assembly process.

In addition, by forming the light guide plate having a sloped surface so as to have an inclined surface to increase the light incident surface area, the light incident efficiency for receiving light from the light source can be increased to provide a high brightness to the liquid crystal panel.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Will be clear to those who have knowledge of.

1 is a view showing a conventional liquid crystal display device.

2 is a view illustrating a backlight unit according to a first embodiment of the present invention.

3 is a view showing a reflector of a backlight unit according to the first embodiment of the present invention.

4 illustrates a backlight unit according to a second embodiment of the present invention.

5 is a diagram showing a curved surface support main of a backlight unit according to a second embodiment of the present invention.

6 is a view illustrating a liquid crystal display device according to an embodiment of the present invention.

7 is a cross-sectional view showing I-I 'in a liquid crystal display device according to an embodiment of the present invention.

Description of the Related Art

112: bottom cover 114: reflector

118 at least one light source 120: light guide plate

122: a plurality of optical sheets 130:

132: light source housing part 134: inclined part

140:

Claims (10)

At least one light source; A light guide plate including a light-incident portion through which light emitted from the light source is incident, and changing the light incident through the light-incident portion into a plane light; A reflector disposed on a back surface of the light guide plate to surround the light source and reflect light to the light guide plate; And a bottom cover surrounding an outer circumferential surface of the reflector, The reflector in a region corresponding to a portion between the light source and the light-incoming portion of the light guide plate has an inclined portion, Wherein the light incident portion of the light guide plate is inclined in a direction opposite to the inclined portion of the reflector, The reflector has a light source housing part for protecting the light source and totally reflecting the light of the light source to the light guide plate, Wherein a distance between a side surface of the light source housing portion facing the light incident portion of the light guide plate and a light incident portion of the light guide plate is further away from an upper surface of the light source housing portion toward an inclined portion of the reflector. The method according to claim 1, The reflector Further comprising a planar reflector for reflecting the light emitted from the backlight of the light guide plate to the front surface of the light guide plate. The method according to claim 1, Wherein the light source comprises any one of a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED). 3. The method of claim 2, Wherein the inclined portion is formed between a lower surface of the light source housing portion and the planar reflection portion. delete At least one light source; A light guide plate including a light-incident portion through which light emitted from the light source is incident, and changing the light incident through the light-incident portion into a plane light; A curved surface support main body having a curved surface for protecting the light source; A reflective sheet provided on a back surface of the light guide plate to reflect light to the light guide plate; And a bottom cover for accommodating the light source, the light guide plate, the reflection sheet, and the curved surface support main, Wherein the reflective sheet in the region corresponding to the space between the light source and the light incident portion of the light guide plate has an inclined portion, The bottom cover in an area corresponding to the space between the light source and the light incident portion of the light guide plate is formed along the inclined portion of the reflective sheet, Wherein the light incident portion of the light guide plate is inclined in a direction opposite to the inclined portion of the reflective sheet, Wherein the curved surface support main has a curved surface portion for protecting the light source and for totally reflecting light of the light source, Wherein a distance between a side surface of the curved surface supporting main body facing the light entrance portion of the light guide plate and a light entrance portion of the light guide plate is further away from the curved portion toward the inclined portion of the reflection sheet. The method according to claim 6, Wherein the light source comprises any one of a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED). The method according to claim 6, The curved surface support main body Wherein the backlight unit further comprises a panel support for supporting the liquid crystal panel. delete A liquid crystal panel for displaying an image by adjusting a transmittance of liquid crystal; And a backlight unit according to any one of claims 1 to 4 and 6 to 8 for radiating light to the liquid crystal panel.

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