Backlight assembly and liquid crystal display apparatus having the same

A backlight assembly includes a lamp assembly generating light, a light guide plate changing a path of light incident from the lamp assembly, a receiving container having a bottom part and a side part vertically extending from the bottom part and forming a receiving space, and an adhesive member fixing the light guide plate to the receiving container. The light guide plate includes a prism pattern on a surface, and the adhesive member is attached to a light-adjusting portion opposite to the lamp assembly. Therefore, the light guide plate may be affixed to the receiving container without additional structure and the appearance of the backlight assembly may be improved by preventing modification of the prism pattern.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a backlight assembly and a liquid crystal display apparatus having the same, more particularly, to a backlight assembly having a light guide plate having a prism pattern formed on a top and/or bottom surface thereof for providing high illumination.

2. Description of the Related Art

Generally, a liquid crystal display device includes a liquid crystal panel including a Thin Film Transistor (TFT) substrate, a color filter (CF) substrate opposite to the TFT substrate, and a liquid crystal disposed between the TFT and CF substrates. The liquid crystal display device further includes a backlight assembly for supplying light.

The backlight, assembly includes at least one lamp, a light guide plate (LGP) for guiding the light from the at least one lamp toward the liquid crystal panel, a reflecting sheet positioned beneath the LGP for reflecting leakage light, optical sheets for improving the optical characteristics of the light from the LGP, and a receiving container for receiving these components.

Recently, a Prism LGP providing high illumination at a low cost has been developed. The Prism LGP has a fine pitch of prism patterns on a bottom surface, and thus provides high illumination without additional optical sheets. However, since the Prism LGP has the prism pattern on the bottom surface, it does not have a good appearance. For example, in securing the Prism LGP in the receiving container, some problems are experienced. Due to the nature of the attachment of the Prism LGP to the receiving container, dark portions are generated around part of the Prism LGP. Further, a shape of the prism pattern on the Prism LGP is transformed by the receiving container.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a backlight assembly capable of improving the appearance by securing the Prism LGP. The backlight assembly comprises a lamp assembly configured to include a lamp and a lamp reflecting plate, a light guide plate configured to change a path of light from the lamp assembly; a receiving container configured to include a bottom part, and a side part extending from the bottom part to receive the lamp assembly and the light guide plate; and an adhesive member configured to affix the light guide plate to the receiving container.

Anther embodiment of the present invention provides a liquid crystal display device having the backlight assembly. The liquid crystal display device comprises a backlight assembly configured to include a lamp assembly having a lamp and a lamp reflecting plate, a light guide plate changing a path of light from the lamp assembly, a receiving container having a bottom part and a side part extending from the bottom part to receive the lamp assembly and the light guide plate, and an adhesive member fixing the light guide plate to the receiving container; a display unit configured to display images by using light from the backlight assembly; and a top chassis configured to fix the backlight assembly to the display unit.

This application relies for priority upon Korean Patent Application No. 2004-10584 filed on Feb. 18, 2003, the contents of which are herein incorporated by reference in its entirety.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a cut out perspective view showing a backlight assembly according to an embodiment of the present invention. Referring toFIG. 1, the backlight assembly1000includes a lamp assembly100, a Light Guide Plate (LGP)200, a receiving container300, and an adhesive member400. The lamp assembly100includes at least one lamp110emitting light, and a lamp reflecting plate120that protects the lamp110and reflects the light toward the LGP200. The lamp assembly100is received at one side of the receiving container300.

The lamp110includes a Cold Cathode Fluorescent Lamp (CCFL) with a stripe shape. The lamp reflecting plate120is made of high reflectance material. Alternately, the reflecting plate may be implemented by a reflective coating on a surface of the lamp110. According to this configuration, the lamp reflecting plate120improves light efficiency by reflecting the light from the lamp110toward the LGP200.

The LGP200is received in an inner space of the receiving container300. The LGP200receives light from the lamp assembly100and vertically outputs the light. The LGP200may be wedge-shaped tapering in thickness away from lamp110. A first prism pattern is formed on the bottom surface of the LGP200for redirecting the light heading towards the bottom surface of the LGP200towards the top surface of the LGP200.

The receiving container300includes a bottom portion310, and a side portion320vertically extending from the bottom portion310forming a receiving space, that receives the lamp assembly100and the LGP200. The adhesive member400is mounted at one side of the LGP200and fixes the LGP200to the receiving container300.

The backlight assembly1000further includes a reflecting sheet500positioned at the bottom surface of the LGP200and an optical sheet600positioned at the top surface of the LGP200. The reflecting sheet500reflects leakage light from the LGP200back towards the LGP200. The reflecting sheet500is made of a reflecting material. The reflecting sheet500is formed, for example, by coating a base film with the reflecting material. The optical sheet600is positioned at the top surface of the LGP200for improving the illumination characteristics from the LGP200.

The optical sheet600includes a reverse prism sheet for improving the front illumination from the LGP200. On the bottom of the optical sheet600facing the top of the LGP200, a second prism pattern is formed. The optical sheet600may further include at least one diffusion sheet. The diffusion sheet may be positioned at the top or bottom of the optical sheet600and diffuses the light from the LGP200or the optical sheet600to improve uniformity of illumination. Further, it should be noted that the diffusion sheet or a separate prism sheet may be added or omitted based on the desired illumination characteristics. Alternately, instead of an optical sheet600, the top surface of the LGP200may be patterned with prisms or other structure to improve the illumination characteristics (e.g. intensity, diffusion) from the LGP200.

The backlight assembly1000further includes a back cover700for conducting heat generated by the lamp assembly100away from the backlight assembly1000. The back cover700is connected with the receiving container300to cover the sides and the bottom of the lamp reflecting plate120

FIG. 2is a perspective view showing the bottom surface of the LGP and an optical sheet600shown inFIG. 1.FIG. 3is an enlarged view of region “A” shown inFIG. 2.

Referring toFIGS. 2 and 3, the LGP200is wedge-shaped having a first prism pattern210that is formed on its bottom surface facing the bottom part310of the receiving container300. The first prism pattern210includes a plurality of first prisms220each having a triangular shape. Each first prism220has a longitudinal axis perpendicular to the longitudinal axis of the lamp assembly100. Each first prism220includes a first inclined surface222and a second inclined surface224, and forms a peak220aand a valley220bin contact with the first and second inclined surfaces222and224together. The inside angel between the first and second inclined surfaces222and224is approximately 120° and the distance (PW) between the adjacent peaks220aor between the adjacent valleys220bis approximately 50um˜60um. However, the first prism pattern210may have various modifications in view of desired illumination characteristics. Therefore, the LGP200may improve illumination by forming the first prism pattern210on the bottom surface of the LGP200.

The optical sheet600is positioned on the top of the LGP200. A second prism pattern610is formed on the bottom surface of the optical sheet600facing the top surface of the LGP200. The second prism pattern610has a plurality of parallel second prisms (not shown) each having a triangular shape. Each second prism has a longitudinal axis parallel to the longitudinal axis of the lamp assembly100.

Therefore, the embodiments of the present invention may improve illumination without a separate optical sheet by forming the first and second prisms210and610on the bottom surfaces of the LGP200and the optical sheet600, respectively.

The optical sheet600further includes a first sheet fixing part620being formed corresponding one of the sides of the optical sheet600. The first sheet fixing part620extends from the corresponding side of the optical sheet600and is fixed to the corresponding one of sides of the receiving container300. A fixing hole622is formed on the center of the first sheet fixing part620for connecting with the receiving container300.

FIG. 4is a perspective view showing the receiving container and the adhesive member shown inFIG. 1, andFIG. 5is a cross-sectional view showing a light adjusting portion of the backlight assembly shown inFIG. 1.

Referring toFIGS. 4 and 5, the receiving container300includes the bottom part310, and the side part320vertically extending from the edge of the bottom part310. The bottom part310includes a plurality of ribs312and an aperture314formed between the plurality of ribs312. The side part320includes a first sidewall320a,a second sidewall320bfacing the first sidewall320a,a third sidewall320cvertically extending from one side of the first sidewall320a,and a fourth sidewall320dconnected with the second sidewall320bto face the third sidewall320c.On the upper surface of the third and fourth sidewalls320cand320d,a fixing protrusion322is provided for securing the optical sheet600to the receiving container300. The optical sheet600is affixed to the receiving container300by inserting the fixing hole622of the first sheet fixing part620into the fixing protrusion part322.

The adhesive member400is attached to the bottom part310adjacent to the second sidewall320b.The adhesive member400affixes the LGP200to the receiving container300by being disposed between the bottom part310and the LGP200. An adhesive material is formed on the upper and lower surfaces of the adhesive member400for affixing the LGP200to the receiving container300. For example, the adhesive member400may be a base film containing Poly Ethylene Terphthalate (PET) or a double-sided tape with an adhesive layer formed on the upper and lower surfaces of the base film. Therefore, the upper surface of the adhesive member400is attached to the LGP200and the lower surface of the adhesive member400is attached to the bottom part310. The reflecting sheet500is positioned so as not to overlap the adhesive member400. Further, the adhesive member400may be colored black for preventing a leakage light from the light adjusting part of the LGP200opposite the lamp110.

FIG. 6is a perspective view showing the underside of region “B” shown inFIG. 4, andFIG. 7is a cross-sectional view showing a light receiving portion of the backlight assembly shownFIG. 1.

Referring toFIGS. 6 and 7, the first sidewall320aincludes an upper surface330and a side surface340. The upper surface330covers the upper part of the lamp assembly100and the side surface340covers the side part of the lamp assembly100. The upper surface330further includes a first protrusion332protruding at a predetermined height toward the bottom part310. As shown inFIG. 6, the first protrusion332is formed adjacent to a first edge contacting the first and fourth sidewalls320aand320d.Further, it should be noted that the first protrusion332is formed adjacent to a second edge contacting the first and third sidewalls320aand320c.The first protrusion332prevents the LGP200from moving toward the lamp assembly100. A guide hole334is formed on the upper surface330of the first sidewall320afor affixing a lamp wire112. The lamp wire112is connected to both sides of a lamp110for applying a driving voltage.

The receiving container300may further include a second protrusion324formed at the third and fourth sidewalls320cand320d.The second protrusion part324protrudes a predetermined height from the inner surface of the LGP200. As shown inFIG. 6, the second protrusion324is formed adjacent to a first edge contacting the first and fourth sidewalls320aand320d.It should be noted that the second protrusion324is formed adjacent to a second edge contacting the first and third sidewalls320aand320c.Further, the second protrusion324may be connected to the first protrusion332. The second protrusion324guides the LGP so that the LGP200is separated by a certain distance from the third and fourth sidewalls320cand320d.According to this configuration, when the LGP200expands due to heat from the lamp110, the space between the LGP200and the third sidewall320c,and between the LGP200and the fourth sidewall320dprevents modification of the LGP200.

The lamp assembly100and the back cover700are mounted on the first sidewall320aat the bottom part of the receiving container300. The bottom surface of the lamp reflecting plate120is exposed through the aperture314. The back cover700is connected with the receiving container300to cover the first sidewall320aand some area of the bottom part310. The back cover700contacts the lamp reflecting plate120exposed through the aperture314. According to this configuration, the back cover700prevents the lamp assembly100mounted in the receiving container300from being separated from the receiving container300. In addition, the back cover700emits heat from the lamp assembly100to the surrounding area. Therefore, the back cover700may be made from a metal material having a high thermal conductivity. A first connecting hole326is formed on the third and fourth sidewalls320cand320dfor connecting the lamp reflecting plate120and the back cover700by fasteners (e.g. screws).

FIG. 8is a perspective view showing the lamp reflecting plate and the back cover shown inFIG. 1. Referring toFIG. 8, the lamp reflecting plate120includes a connecting part122extended from its one side corresponding to the third and fourth sidewalls320cand320d.The connecting part122has a first hole124corresponding to the first connecting hole326formed at the third or fourth sidewalls320cand320d.The lamp reflecting plate120is affixed to the first sidewall320avia a fastener (e.g. a screw) extending through the first hole124and the first connecting hole326.

The back cover700has a second hole720corresponding to the first connecting hole326formed the third and fourth sidewalls320cand320d.The back cover700is fixed to the receiving container300via a fastener (e.g. a screw) extending through by the second hole720and the first connecting hole326. The lamp reflecting plate120further includes a hook126protruding from its bottom surface, and the back cover700further includes a connecting hole730formed to meet the hook126. The lamp reflecting plate120is affixed to the receiving container300through the connecting part122formed at one side or both sides of is the lamp reflecting plate210. Further, the hook126of the lamp reflecting plate120is connected with the connecting hole730. This configuration prevents the lamp reflecting part120from sliding toward the LGP200.

FIG. 9is a plan view showing the receiving container shown inFIG. 4, andFIG. 10is a perspective view showing a third edge part that meets the second and fourth sidewalls320band320d.

Referring toFIGS. 9 and 10, the second protrusion324is formed on the third and fourth sidewalls320cand320dcorresponding to the light receiving portion. The LGP200is mounted so that the second protrusion324distances the LGP200from the third and fourth sidewalls320cand320dby a predetermined distance. A recess328may also be formed on the third and fourth sidewalls320cand320dto accommodate the light adjusting portion. The recess328has a predetermined depth from the inner surface of the third and fourth sidewalls320cand320d.Further, the recess328is formed to meet the light adjusting part, and thus may prevent the LGP200from being bent and prevent an edge part of the LGP200from being broken.

As shown inFIGS. 9 and 10, a protrusion329is formed on the upper surface of the first, second, third and fourth sidewalls320a,320b,320cand320dfor guiding the receiving location of the optical sheet600mounted on the upper part of the LGP200. The fixing protrusion322is formed on the upper surface of the third and fourth sidewalls320cand320dfor securing the optical sheet600.

The receiving container300further includes a guiding part350that is formed around a first edge contacting the first and fourth sidewalls320aand320d,a second edge contacting the first and third sidewalls320aand320c,a third edge contacting the second and third sidewalls320band320c,and a fourth edge contacting the second and fourth sidewalls320band320d,respectively. The guiding part350is formed to be higher than the upper surface of the first, second, third and fourth sidewalls320a,320b,320cand320d.The guiding part350guides the connecting location of a liquid crystal display device (not shown).

FIG. 11is a perspective view showing the reflecting sheet shown inFIG. 1, andFIG. 12is an enlarged view of region “C” shown inFIG. 4.

Referring toFIGS. 11 and 12, the reflecting sheet500is positioned on the bottom part310of the receiving container300. The reflecting sheet500is made of, for example, a PET material or Poly Carbonate (PC) material, etc. A reflecting layer is formed on the upper surface of the reflecting sheet500for reflecting light. A second sheet fixing part510is formed on both sides of the reflecting sheet500for affixing the reflecting sheet500to the receiving container300, respectively.

As shown inFIG. 12, an insert hole327is formed on the third and fourth sidewalls320cand320dto receive the second sheet fixing part510. The insert hole327is a hole formed in the inner surface of the third and fourth sidewalls320cand320dthat receives the second sheet fixing part510. The reflecting sheet500is affixed to the receiving container300by inserting the second sheet fixing part510into the insert hole327. This configuration eliminates an additional adhesive unit for attaching the reflecting sheet500to the receiving container300.

FIG. 13is an enlarged view of region “D” shown inFIG. 4. Referring toFIG. 13, the bottom part310of the receiving container300includes a plurality of ribs312partially connected to each other, and aperture314disposed between the ribs312. The ribs312support the reflecting sheet500, the LGP200, and the optical sheet600that are mounted on the receiving container300. The ribs312may be formed using minimal area of the bottom part310for reducing weight.

The inner surface of the ribs312facing the reflecting plate500and the LGP200is tapered from the center of the ribs312to an edge adjacent to the aperture314. This configuration prevents the first prism pattern of the LGP200from being modified by reducing contact between the first prism pattern and the ribs312.

FIG. 14is a perspective view showing a liquid crystal display device according to an embodiment of the present invention. In this embodiment, since the backlight assembly1000has the same structure as that described with reference toFIGS. 1 to 13, the detailed description of the backlight assembly1000will be omitted, and the same reference numerals used for corresponding elements.

Referring toFIG. 14, the liquid crystal display device2000includes the backlight assembly1000, a display unit800for displaying images, and a top chassis900for fixing the display unit800to the backlight assembly1000. The display unit800includes a liquid crystal panel810, a source Printed Circuit Substrate (PCB)820, a Tape Carrier Package (TCP)830, and a gate TCP840. The liquid crystal panel810includes a Thin Film Transistor (TFT) substrate812, a color filter (CF) substrate814and a liquid crystal (not shown) disposed between the TFT and CF substrates812and814.

The TFT substrate812is a transparent glass substrate having TFTs (not shown) formed in a matrix. The source terminal of the TFT is connected to a data line, the gate terminal of the TFT is connected to a gate line, and the drain terminal of the TFT is connected to a pixel electrode being made of a transparent conductive material. The CF substrate814is a substrate that RGB filters are formed. A common electrode is formed on the whole surface of the CF substrate814.

The source PCB substrate820is connected to one side of the TFT substrate812through the data TCP830. The source PCB substrate820generates data driving signals and gate driving signals, and outputs them to the liquid crystal panel810. The data driving signals are signals for controlling the data line formed on the TFT substrate812, and are applied to the data line through the data TCP830. The gate driving signals are signals for controlling the gate line formed on the TFT substrate812, and are applied to the gate line through the data TCP820and the gate TCP830. Therefore, a conductive wiring (not shown) is formed on the TFT substrate812for connecting the data TCP820and the gate TCP830.

The display unit800is mounted on the upper surface of the backlight assembly1000. The liquid crystal panel810is located on the upper surface of the receiving container300and the mounted location is guided by the guide part350formed around four edges of the receiving container300. The source PCB substrate820is fixed to the rear of the receiving container300by bending the data TCP820.

The top chassis900is connected to the receiving container300to cover the edge part of the liquid crystal panel810. The top chassis900prevents the liquid crystal panel810from escaping from the backlight assembly1000and prevents the liquid panel810from be damaged by external impact.

The prevent invention may retain the LGP without an additional process, and may prevent poor appearance by affixing the LGP with the prism pattern by an adhesive member and supported by a plurality of tapered ribs.

Having described the embodiments of the present invention and its advantages, it should be noted that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by appended claims.