Backlight assembly and method of assembling the same

A backlight assembly comprises an optical plate that has a fixing portion and a receiving member that has a combination portion combined with the fixing portion. The fixing portion comprises a protrusion that is extended from the optical plate and a connecting portion that is bent with respect to and extended from the protrusion.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2007-0092660, filed on Sep. 12, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference in its entirety herein.

BACKGROUND OF THE DISCLOSURE

1. Technical Field

This disclosure relates to a backlight assembly and a method of assembling the backlight assembly.

2. Discussion of Related Art

A cathode ray tube (CRT) device had been widely used as an information processing apparatus due to its capabilities and price. However, the CRT device is large in size and not very portable.

Liquid crystal display (LCD) devices have small and compact sizes and reduced power consumption and have been used as an alternative to the CRT device. The LCD device displays an image using electrical and optical characteristics of liquid crystal molecules.

The LCD device includes an LCD panel, a driver for driving the LCD panel, a backlight assembly for providing light to the LCD panel, and a top chassis and a bottom chassis for receiving and fixing the LCD panel, the driver, and the backlight assembly.

The backlight assembly includes a light source for emitting light, an optical plate for guiding the light from the light source to the LCD panel, a mold frame for protecting the optical plate and light source, and a reflective sheet and an optical sheet for increasing light efficiency.

In a conventional LCD device, double-sided adhesive tape has been used to prevent the optical plate from moving while the optical plate and the mold frame are combined with each other. Attaching the adhesive is time-consuming because it needs to be manually performed.

Thus, there is a need for a backlight assembly and a method of assembling the backlight assembly, which can prevent its optical plate from moving without requiring the adhesive tape.

SUMMARY OF THE INVENTION

According to an exemplary embodiment of the present invention, a backlight assembly comprises an optical plate on which light is incident from a light source, and a receiving member in which the light source and the optical plate are received. The optical plate includes a fixing portion and the receiving member includes a combination portion combined with the fixing portion. The fixing portion comprises a protrusion that is extended from the optical plate and a connecting portion that is bent with respect to and extended from the protrusion.

The combination portion may have a combination groove. The combination groove contacts at least one surface of the fixing portion and is combined with the fixing portion.

The combination portion may comprise a separation preventing portion and a supporting portion. The separation preventing portion may cover at least one outer surface of the protrusion and be combined with the protrusion to prevent the optical plate from being separated from the receiving member. The supporting portion may be bent with respect to and extended from a surface of the separation preventing portion and cover at least one outer surface of the connecting portion.

A top surface of the protrusion may face a bottom surface of the separation preventing portion and be spaced by a predetermined interval from the bottom surface of the separation preventing portion.

The connecting portion may have the same thickness as that of the supporting portion.

The connecting portion may comprise a vertical surface bent with respect to and extended from the protrusion, a bottom surface extended from the vertical surface and being substantially parallel to the extension direction of the protrusion, and an inclined surface inclined with respect to the bottom surface and extended from the bottom surface to a side surface of the protrusion.

The combination portion may comprise a separation preventing portion covering at least one outer surface of the connecting portion and being in contact with the connecting portion to prevent the optical plate from being separated from the receiving member, and a supporting portion bent with respect to and extended from the separation preventing portion and covering at least one outer surface of the connecting portion.

The optical plate may comprise an incident surface on which light is incident from the light source, an opposite surface that faces and is positioned opposite the incident surface, first and second connecting surfaces that are connected to the incident surface and the opposite surface, an emitting surface through which the light is emitted from the incident surface, and a bottom surface that faces and is positioned opposite the emitting surface.

The fixing portion may be formed on at least one of the opposite surface, the first connecting surface, and the second connecting surface.

The optical plate may comprise a plurality of the fixing portions.

The fixing portion may comprise first and second fixing portions. The first fixing portion faces the second fixing portion.

The combination portion may comprise a combination groove that contacts at least one surface of the fixing portion and a locking portion that is engaged with the connecting portion. The fixing portion may be inserted into the combination groove.

The fixing portion may cover at least one outer surface of the locking portion.

The backlight assembly may comprise a plurality of the light sources and the receiving member may include a receiving portion that receives and fixes the light sources.

The incident surface of the optical plate may be spaced from an inner surface of the receiving member by a predetermined interval.

An adhesive material may be applied on a region where the bottom surface of the optical plate contacts a lower surface of the receiving member.

According to an exemplary embodiment of the present invention, a method of assembling a backlight assembly comprises preparing a receiving member, an optical plate, and a light source, receiving the light source in a receiving portion of the receiving member, and fixing the optical plate to the receiving member, wherein the receiving member includes a combination portion and the optical plate includes at least one fixing portion.

Fixing may comprise combining the fixing portion of the optical plate with the combination portion of the receiving member, and seating the optical plate in the receiving portion of the receiving member so that an incident surface of the optical plate faces the light source.

The fixing portion may comprise a protrusion projected from the optical plate, and a connecting portion bent with respect tot and extended from the protrusion.

The combination portion may comprise a separation preventing portion covering at least one outer surface of the protrusion and being combined with the protrusion to prevent the optical plate from being separated from the receiving member, and a supporting portion bent with respect to and extended from the separation preventing portion and covering at least one outer surface of the connecting portion.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numbers may be used throughout the drawings to refer to the same or like parts.

FIG. 1is an exploded perspective view showing an LCD device according to an exemplary embodiment.

Referring toFIG. 1, the LCD device200includes a top chassis10, an LCD panel20, a driving circuit portion, a backlight assembly, and a bottom chassis150.

The top chassis10is arranged on the LCD panel20to protect the LCD panel20and the backlight assembly. The top chassis10has an opening formed in its center, which exposes a display region of the LCD panel20.

The LCD panel20includes a color filter substrate21, a thin film transistor (TFT) substrate23, and a liquid crystal layer.

The color filter substrate21includes an upper substrate, a black matrix, and a color filter. The upper substrate is made of glass or plastic. The black matrix is formed on the upper substrate to block light. The color filter includes a red color filter, a green color filter, and a blue color filter and is provided on a region that is defined by the black matrix. The red color filter, the green color filter, and the blue color filter are used for implementing red color, green color, and blue color, respectively. The color filter substrate21further includes a common electrode to apply a common voltage to the liquid crystal layer and an upper alignment layer coated on the common electrode to align liquid crystal molecules.

The TFT substrate23includes a lower substrate, gate lines, data lines, and TFTs. The lower substrate is made of glass or plastic. The gate lines and the data lines intersect each other on the lower substrate, with a gate insulating layer interposed between the gate lines and the data lines. The TFTs are connected to the gate lines and the data lines. The TFT substrate23further includes pixel electrodes to apply pixel voltages to the liquid crystal layer and a lower alignment layer coated on the pixel electrodes to align liquid crystal molecules. A TFT includes a gate electrode connected to the gate line, a source electrode connected to the data line, and a drain electrode connected to the pixel electrode. The drain electrode is positioned to face the source electrode.

The driving circuit portion includes a gate driver integrated circuit (IC)43for driving the gate line and a data driver IC53for driving the data line. The driving circuit portion further includes a timing controller, a power supply, and other circuit elements, and generates various signals necessary to implement an image. Signal circuits such as the timing controller, the power supply, and other circuit elements are mounted on a gate printed circuit board (PCB)45and a data PCB55.

The signal circuits mounted on the gate PCB45and the data PCB55are connected through a gate tape carrier package (TCP)41and a data TCP51to the gate line and the data line.

The backlight assembly includes an optical sheet60, a light source71, a lamp housing73, an optical plate80, a receiving member, and a reflective sheet140. The receiving member will be described hereinbelow as a mold frame110, but the embodiments of the present invention are not limited thereto.

The optical sheet60is arranged on the optical plate80to direct light from the optical plate80to the LCD panel20. The optical sheet60includes a diffusion sheet61for diffusing the light incident from the optical plate80and a prism sheet63for vertically directing the light from the diffusion sheet61. The optical sheet60also includes a protective sheet65that is arranged on the diffusion sheet61and the prism sheet63.

The light source71emits light. The light source71may include a cold cathode fluorescent lamp (CCFL) and an external electrode fluorescent lamp (EEFL). The light source71is arranged parallel with the LCD panel20and abuts the incident surface of the optical plate80.

The lamp housing73is arranged to wrap around an outer surface of the light source71except for a part of the outer surface which faces the optical plate80. The lamp housing73is spaced from the light source71by a predetermined interval. The lamp housing73has a reflective film coated on its inside surface.

The optical plate80changes line light to surface light and directs the surface light to the LCD panel20. The optical plate80may be formed of a transparent synthetic resin. The optical plate80includes a fixing portion90.

The mold frame110receives the optical plate80and the light source71. The mold frame110includes a combination portion120. The combination portion120is combined with the fixing portion90.

The reflective sheet140is arranged on a lower side of the optical plate80. The reflective sheet140is made of a highly reflective material. The reflective sheet140reflects the light incident thereon from the optical plate80to reduce light loss.

The bottom chassis150receives the backlight assembly while covering the edge region of the backlight assembly. The bottom chassis150also receives the mold frame110and the LCD panel20. The bottom chassis150is combined with the top chassis10to protect the LCD panel20, the driving circuit portion, and the backlight assembly from external impacts.

FIG. 2Ais a perspective view showing an exemplary optical plate of the LCD device shown inFIG. 1, andFIG. 2Bis an enlarged perspective view of a region ‘A’ of the optical plate shown inFIG. 2B.

Referring toFIG. 2A, the optical plate80includes an incident surface81on which light is incident from a light source71, an emitting surface82through which light is emitted, and an opposite surface83which faces the incident surface81. The opposite surface83includes a fixing portion90. The optical plate80may become thinner in a direction from the incident surface81to the opposite surface83.

The fixing portion90may be formed of the same material as that of the optical plate80. Referring toFIG. 2B, the fixing portion90includes a protrusion93and a connecting portion95. The protrusion93is extended from a part of the opposite surface83. The connecting portion95projects perpendicular from the protrusion93. The connecting portion95protrudes downward from the protrusion away from the emitting surface82.

FIG. 3is an enlarged perspective view of a combination portion of an exemplary mold frame of the LCD device shown inFIG. 1.

Referring toFIG. 3, the mold frame110includes a combination portion120. The combination portion120includes a separation preventing portion121, a supporting portion123, and a combination groove125. The separation preventing portion121is formed on an upper side of the mold frame110. The separation preventing portion121includes three surfaces so formed to create an empty space in the side of the mold frame110. The supporting portion123is formed on a lower side of the mold frame110. The supporting portion123extends from sides of the separation preventing portion121while being spaced from a top surface of the separation preventing portion121by a predetermined interval. The combination groove125is formed by interval between the separation preventing portion121and the supporting portion123. The combination groove125may be shaped as a rectangle.

FIG. 4Ais a cross sectional view illustrating a combination of the optical plate shown inFIG. 2Aand the mold frame shown inFIG. 3, andFIG. 4BandFIG. 4Care enlarged perspective views showing a region ‘B’ where the fixing portion and the combination portion shown inFIG. 4Aare combined with each other.

Referring toFIGS. 4A and 4B, the optical plate80is received inside the mold frame110and its fixing portion90is inserted into the combination groove125. The separation preventing portion121includes three surfaces so formed to create the empty space in the mold frame110to form the combination portion120, and wraps around the outer surface of the fixing portion90, so that the optical plate80can be fixed to the mold frame110. More specifically, since the protrusion93contacts the separation preventing portion121, the optical plate80is fixed by the separation preventing portion121, and the separation preventing portion121may prevent the optical plate80from moving in the Z-axis direction.

The connecting portion95is engaged with the supporting portion123to prevent the optical plate80from moving in the X-axis direction. The supporting portion123is recessed toward the inside of the mold frame110by a width of the connecting portion95. Therefore, the connecting portion95can be firmly supported by the supporting portion123.

The combination of the optical plate80and the mold frame110by the fixing portion90and the combination portion120can prevent the deformation of the optical plate80. The bottom surface of the separation preventing portion121that faces the top surface of the protrusion93may be spaced by a predetermined interval from the top surface of the protrusion93, so that the protrusion93may be easily combined with the combination portion120. A height d2of the connecting portion95may be equal to a height d1of the supporting portion123.

FIG. 4DandFIG. 4Eare enlarged perspective views showing a region ‘C’ where the optical plate and a receiving portion of the mold plate shown inFIG. 4Aare combined with each other.

Referring toFIG. 4D, the incident surface81is seated in a receiving portion115. The receiving portion115includes an inner surface111that faces the incident surface81and a lower surface113that is bent with respect to and extended from the inner surface111. The incident surface81is spaced by a predetermined interval from the inner surface111, so that the light source71can be arranged between the incident surface81and the inner surface111.

Referring toFIG. 4E, an adhesive material117may be applied in a region where a bottom surface86of the optical plate80contacts the lower surface113of the receiving portion115in order to prevent the optical plate80from moving.

FIG. 5AandFIG. 5Bare perspective views illustrating a process of combining the optical plate and the mold frame shown inFIG. 4A.

Referring toFIG. 5A, the light source71and the lamp housing73are mounted in the mold frame110and then the optical plate80is received in the mold frame110. The fixing portion90of the optical plate80is combined with the combination portion120of the mold frame110. The separation preventing portion121of the fixing portion90wraps around the protrusion93of the fixing portion90. The supporting portion123of the combination portion120is engaged with the connecting portion95of the fixing portion90.

Referring toFIG. 5B, the incident surface81of the optical plate80is seated in the receiving portion115of the mold frame110. The incident surface81is spaced by a predetermined interval from the inner surface111, so that the light source71can be arranged between the incident surface81and the inner surface111. An adhesive material may be applied in a region where the bottom surface86contacts the lower surface113.

FIG. 6is an enlarged perspective view of a fixing portion of an exemplary optical plate of the LCD device shown inFIG. 1, andFIG. 7is a cross sectional view illustrating a combination of the optical plate shown inFIG. 6and a mold frame.

Referring toFIG. 6, the optical plate80includes the opposite surface83from which the fixing portion90is projected. The fixing portion90includes the protrusion93that is extended from the opposite surface83and the connecting portion95that is extended perpendicular to the protrusion93.

The connecting portion95includes a vertical surface951, a bottom surface952, and an inclined surface953. The vertical surface951is extended to be substantially perpendicular to the protrusion93. The bottom surface952is extended from the vertical surface951to be substantially parallel with the protrusion93. The bottom surface952is substantially perpendicular to the vertical surface951. The inclined surface953is extended from the bottom surface952to be upwardly inclined by a predetermined angle.

Referring toFIG. 7, the fixing portion90of the optical plate80is combined with the combination portion120of the mold frame110. The protrusion93contacts the separation preventing portion121and the vertical surface951of the connecting portion95contacts the supporting portion123. The fixing portion90can be easily combined with the combination portion120due to the inclined surface953formed to be inclined by a predetermined angle.

Although the inclined surface953has been described to be inclined by a predetermined angle, the embodiments of the present invention are not limited thereto. For example, the inclined surface953may be shaped as a curved surface.

FIG. 8is an enlarged perspective view of a fixing portion of an exemplary optical plate of the LCD device shown inFIG. 1

Referring toFIG. 8, the optical plate80includes the fixing portion90that protrudes from the opposite surface83. The fixing portion90includes the protrusion93and the connecting portion95. The protrusion93is extended from a part of the opposite surface83. The connecting portion95protrudes upward from the protrusion93away from the emitting surface82of the optical plate80.

FIG. 9is an enlarged perspective view of a combination portion of an exemplary mold frame of the LCD device shown inFIG. 1.

Referring toFIG. 9, the mold frame110includes the combination portion120. The combination portion120includes the separation preventing portion121, the supporting portion123, and the combination groove125. The separation preventing portion121is formed on an upper side of the mold frame110. The supporting portion123is located on a lower side of the mold frame110. The combination groove125is formed by the space between the separation preventing portion121and the supporting portion123.

FIG. 10is a cross sectional view illustrating a combination of the optical plate shown inFIG. 8and the mold frame shown inFIG. 9.

Referring toFIG. 10, the protrusion93contacts the supporting portion123. The connecting portion95contacts the separation preventing portion121. The separation preventing portion121includes a seating surface121aon which the optical sheet (not shown) is seated, and a contact surface121bthat is perpendicular to the seating surface121a. When the optical plate80moves in the direction of X axis, the connecting portion95is engaged with the contact surface121b. This can prevent the optical plate80from moving in the X-axis direction. When the optical plate80moves in the direction of Y axis, the protrusion93is held in place by the separation preventing portion121and the supporting portion123. This can prevent the optical plate80from moving in the Y-axis direction.

Although the optical plate80has been described to have a single fixing portion, the embodiments of the present invention are not limited thereto. For example, at least one fixing portion may be further provided on other surfaces of the optical plate80.

FIG. 11is an exploded perspective view showing an LCD device according to an exemplary embodiment of the present invention.

Referring toFIG. 11, the LCD device200includes a top chassis10, an LCD panel20, a driving circuit portion, a backlight assembly, and a bottom chassis150.

The backlight assembly includes an optical sheet60, a light source71, a lamp housing73, an optical plate80, a mold frame110, and a reflective sheet140.

The light source71is arranged in a side of the optical plate80to emit light.

The optical plate80directs the light from the light source71to the LCD panel20. The optical plate80includes a first fixing portion91and a second fixing portion97.

The mold frame110receives the optical plate80. The mold frame110includes a first combination portion127and a second combination portion129through which the optical plate80can be combined.

The optical sheet60is arranged on the optical plate80to direct light from the optical plate80to the LCD panel20.

The reflective sheet140is arranged on a lower side of the optical plate80. The reflective sheet140reflects the light incident thereon from the optical plate80to reduce light loss.

The bottom chassis150and the top chassis10receive the LCD panel20, the driving circuit portion, and the backlight assembly, and protect them from external impacts.

FIG. 12AandFIG. 12Bare perspective views of an exemplary optical plate of the LCD device shown inFIG. 11.

Referring toFIG. 12A, the optical plate80includes an incident surface81, an opposite surface83, a first connecting surface87, a second connecting surface89, an emitting surface82, and a bottom surface86. The emissive light is directed from the incident surface81through the emitting surface82to the LCD panel20. The bottom surface86faces the emitting surface82. The first and second connecting surfaces87and89are symmetrical to each other and connected to the incident surface81and the opposite surface83. The fixing portions91and97protrude from the first and second connecting surfaces87and89, respectively.

Referring toFIG. 12B, the first fixing portion91includes a first protrusion94and a first connecting portion96, and the second fixing portion97includes a second protrusion98and a second connecting portion99. The first and second protrusions94and98may be thinner in thickness than the first and second connecting portions96and99, respectively. The first and second connecting portions96and99are bent with respect to the first and second protrusions94and98and extended from the first and second protrusions94and98, respectively.

FIG. 13AandFIG. 13Bare perspective views of an exemplary mold frame of the LCD device shown inFIG. 11.

Referring toFIGS. 13A and 13B, the mold frame110includes first and second combination portions127and129. The first and second combination portions127and129face the first and second fixing portions91and97, respectively. The first combination portion127includes a first locking portion122and a first combination groove124, and the second combination portion129includes a second locking portion126and a second combination groove128. The first and second locking portions122and126can be lower in height than the top surface of the mold frame110. The first and second grooves124and128are depressed to be lower in height than the first and second locking portions122and126, respectively.

FIG. 14A,FIG. 14B, andFIG. 14Care cross sectional views of combinations of the optical plate and the mold frame shown inFIG. 12A,FIG. 12B, andFIG. 13AandFIG. 13Band processes of combining the optical plate and the mold frame.

Referring toFIG. 14A, the mold frame110includes the first and second combination portions127and129, and the optical plate80includes the first and second fixing portions91and97.

Referring toFIGS. 14A and 14B, the optical plate80is arranged over the mold frame110, so that the first and second fixing portions91and97face the first and second combination portions127and129, respectively. Then, the first and second fixing portions91and97are combined with the first and second combination portions127and129, respectively, by press-fitting the optical plate80into the mold frame110.

More specifically, the first and second connecting portions96and99are inserted into the first and second grooves124and128, respectively. The first and second connecting portions96and99are brought in tight contact with the first and second locking portions122and126, respectively, so that the mold frame110can be firmly combined with the optical plate80. Referring toFIG. 14C, the optical plate80can be firmly combined with the mold frame110without leaving any space between the locking portions122and126, and the connecting surfaces87and89.

FIG. 15is an exploded perspective view showing an LCD device according to an exemplary embodiment of the present invention.

Referring toFIG. 15, the LCD device200includes a top chassis10, an LCD panel20, a driving circuit portion, a backlight assembly, and a bottom chassis150.

The backlight assembly includes an optical sheet60, a light source71, an optical plate80, a mold frame110, and a reflective sheet140.

As an alternative to a CCFL or EEFL, the light source71may be light emitting diodes (LEDs). The light source71is mounted on a substrate (not shown) and arranged adjacent to the incident surface81. The light source71is fed with electric power from an external power source (not shown) to generate light.

The optical plate80changes line light to surface light and directs the surface light to the LCD panel20. The optical plate80may be shaped as a slim and flat plate. The optical plate80includes an incident surface81and an opposite surface83that faces the incident surface81. A fixing portion90protrudes from the opposite surface83. The fixing portion90of the optical plate80is combined with the combination portion120of the mold frame110and prevents the optical plate80from moving.

The mold frame60receives the optical plate80and the light source71. The mold frame110includes a combination portion120. The combination portion120is prepared in a part of the mold frame110, which corresponds to the fixing portion90.

FIG. 16is an exploded perspective view showing an LCD device according to an exemplary embodiment of the present invention.

Referring toFIG. 16, the LCD device200includes a top chassis10, an LCD panel20, a driving circuit portion, a backlight assembly, and a bottom chassis150.

The backlight assembly includes an optical plate80, a light source71, and a mold frame110.

The optical plate80is arranged below the LCD panel20. The optical plate80directs the light from the light source71to the LCD panel20. The optical plate80may include a diffusion sheet, a prism sheet, and a protective sheet. The optical plate80includes a first fixing portion91and a second fixing portion97. The first fixing portion91is positioned opposite to the second fixing portion97. The second fixing portion97has the same structure as that of the first fixing portion91. The first fixing portion91includes a first protrusion94and a first connecting portion96. The first and second fixing portions91and97are combined with the first and second combination portion127and129to prevent the optical plate80from moving.

The light source71emits light. A plurality of light sources71are provided below the optical plate80and arranged in parallel with the LCD panel20, so that the light emitted from the light source71can be directly incident to the LCD panel.

The reflective sheet140is arranged below the light source71and reflects the light incident thereon to the LCD panel20to reduce light loss.

The mold frame110includes a first combination portion127and a second combination portion129. The first combination portion127faces and is combined with the first fixing portion91. The second combination portion129faces and is combined with the second fixing portion97. The second combination portion129has the same structure as that of the first combination portion127. The first combination portion127includes a first locking portion and a first combination groove. The first connecting portion96is inserted into the first combination groove. The mold frame110further includes a bottom surface119on which the light source71is seated.

The above exemplary embodiments have been described with respect to a case where a mold frame is employed as a receiving member, but the embodiments of the present invention are not limited thereto. For example, any receiving members that fix the optical plate could be used.

As described above, the exemplary embodiments of the present invention can prevent an optical plate from moving through the combination of a fixing portion of the optical plate and a combination portion of a receiving member.