Backlight assembly including a buffered lamp holder for impact absorption and display apparatus having the same

A backlight assembly includes a lamp, a light guide plate, a receiving container and a lamp holder. The lamp generates light. The light guide plate has a light incident face through which the light generated by the lamp enters the light guide plate. The light guide plate guides the light. The receiving container has a base plate and sidewalls protruding from the edge portions of the base plate to define a receiving space for receiving the lamp and the light guide plate. The lamp holder holds an end portion of the lamp and includes a buffer portion. When an impact is applied to the backlight assembly, the buffer portion absorbs the impact to prevent damages to the lamp and the light guide plate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application relies for priority upon Korean Patent Application No. 2004-67775 filed on Aug. 27, 2004, and Korean Patent Application No. 2005-49911 filed on Jun. 10, 2005, the contents of which are herein incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a backlight assembly and display apparatus having the backlight assembly. More particularly, the present invention relates to a backlight assembly having enhanced reliability and a display apparatus having the backlight assembly.

2. Description of the Related Art

A display apparatus converts an electric signal that is processed by an information processing apparatus into an image. Examples of display apparatus include a cathode ray tube (CRT) apparatus, a liquid crystal display (LCD) apparatus, an organic light emitting display (OLED) apparatus, etc.

Of the different types of display apparatuses, the LCD apparatus typically includes a display panel and a backlight assembly. The display panel displays an image by controlling the optical transmittance of liquid crystals through a pixel. The backlight assembly provides the display panel with light.

The backlight assembly includes a lamp unit and a light guide plate. The lamp unit includes a lamp that generates light and a lamp holder that supports the lamp. The light guide plate enhances the luminance uniformity of the light generated by the lamp and directs the light toward the display panel.

A receiving container receives the lamp unit and the light guide plate. When the distance between the lamp unit and the light guide plate increases, the thickness of the backlight assembly increases. When the distance between the lamp unit and the light guide plate is decreased in order to reduce the thickness of the backlight assembly, the lamp unit and the light guide plate are easily damaged by an impact applied to at least one of the lamp unit and the light guide plate. Thus, there is a conflict between compactness of the device and the reliability of the device.

A method of making the display device compact without compromising reliability is desired.

SUMMARY OF THE INVENTION

The present invention provides a backlight assembly capable of preventing the floating of a light guide plate in order to reduce an impact applied to a lamp unit and/or the light guide plate.

The present invention also provides a display apparatus having the above backlight assembly.

In an exemplary backlight assembly according to the present invention, the backlight assembly includes a lamp, a light guide plate, a receiving container and a lamp holder. The lamp generates light. The light guide plate has a light incident face through which the light generated by the lamp enters the light guide plate. The light guide plate guides the light. The receiving container has a base plate and sidewalls protruding from edge portions of the base plate to define a receiving space for receiving the lamp and the light guide plate. The lamp holder holds an end portion of the lamp. The lamp holder includes a buffer portion that moderates an impact due to a floating of the light guide plate.

The portion of the lamp holder that is adjacent to the light incident face of the light guide plate may protrude toward the light incident face of the light guide plate to form the buffer portion. The receiving container may also include a light guiding plate (LGP) fixing member protruding from the base plate to be disposed between the light incident face of the light guide plate and the buffer portion of the lamp holder.

Preferably, the lamp holder includes a first buffer opening for absorbing any impact applied to the light guide plate and the receiving container.

In another aspect, the present invention is a display apparatus that includes a backlight assembly and a display panel. The backlight assembly includes a lamp, a light guide plate, a receiving container and a lamp holder. The lamp generates light, and the light guide plate guides the light. The light guide plate has a light incident face through which the light generated by the lamp enters the light guide plate. The receiving container has a base plate and sidewalls protruding from edge portions of the base plate to define a receiving space for receiving the lamp and the light guide plate. The lamp holder holds an end portion of the lamp. The lamp holder includes a buffer portion that absorbs an impact due to the floating of the light guide plate. The display panel is disposed over the backlight assembly. The display panel converts the light generated by the lamp of the backlight assembly into an image.

According to the present invention, when an impact is applied to the backlight assembly or the display apparatus, the LGP fixing member fastens the light guide plate to the receiving container and the buffer portions absorb the impact to prevent damages to the lamp and the light guide plate.

DESCRIPTION OF THE EMBODIMENTS

It should be understood that the exemplary embodiments of the present invention described below may be modified in many different ways without departing from the inventive principles disclosed herein, and the scope of the present invention is therefore not limited to these particular flowing embodiments. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art by way of example and not of limitation.

FIG. 1is an exploded perspective view illustrating a backlight assembly according to a first exemplary embodiment of the present invention.

Referring toFIG. 1, a backlight assembly according to the present embodiment includes a light guide plate100, a receiving container200and a lamp unit300.

The light guide plate100is shaped like a rectangular plate. The light guide plate100includes, for example, an optically transparent acrylic resin. The light guide plate100includes a first side face111, a second side face112, a third side face113, a fourth side face114, a light exiting face120, and a light reflecting face130that is opposite the light exiting face120. The first, second, third and fourth side faces111,112,113and114connect the light exiting face120and the light reflecting face130.

The first side face111is substantially parallel to the second side face112, and the third side face113is substantially parallel to the fourth side face114. The first side face111is connected to the second and fourth side faces112and114, and the second side face112is also connected to the third and fourth side faces113and114. The first side face111is a light incident face. In other words, the lamp unit300is adjacent to the first side face111so that the light generated by the lamp unit300enters the light guide plate100through the first side face111.

The light guide plate100may be, for example, shaped like a rectangular plate and have a substantially uniform thickness. Alternatively, the light guide plate100may have a wedge-shape with its thickness decreasing from the first side face111to the second side face112.

The light exiting face120is opposite the light reflecting face130. Light that enters the light guide plate100through the first side face111exits the light guide plate100through the light reflecting face130. The light reflecting face130reflects a portion of the light that enters the light guide plate100through the first side face111toward the light exiting face120.

A plurality of prism patterns (not shown) may be formed on the light exiting face120or the light reflecting face130in order to alter the path of light that enters the light guide plate100through the first side face111. When protrusions or recesses are formed at the first, second, third and fourth side faces111,112,113and114, the luminance and the luminance uniformity are lowered. Therefore, it is preferable that there be no protrusions or recesses on the side faces111,112,113,114.

The receiving container200includes a base plate210, a first sidewall220, a second sidewall230, a third sidewall240and a fourth sidewall250. The first to fourth sidewalls220,230,240and250extend from edge portions of the base plate210. The receiving container200receives the light guide plate100and the lamp unit300.

The base plate210has a rectangular shape to receive the light guide plate100. The base plate210may have as many openings (not shown) as possible leaving an area supporting the light guide plate100without an opening, thereby reducing weight. The receiving container200further includes a light guiding plate (LGP)-fixing member211. The LGP-fixing member211protrudes from the base plate210. The LGP-fixing member211is disposed at a region where the first side face111meets an end portion of the lamp unit300. The LGP-fixing member211will be explained in detail with reference toFIG. 5.

The lamp unit300includes at least one lamp310generating light, and a lamp holder320. The lamp unit310is disposed between the first side face111of the light guide plate100and the first sidewall220of the receiving container200.

A cold cathode fluorescent lamp (CCFL) having a cylindrical shape may be employed as the lamp310. A hot electrode (not shown) for applying a relatively high voltage, and a cold electrode (not shown) for applying a relatively low voltage are disposed at first and second end portions of the lamp310, respectively. The lamp unit300may include more than one lamp310.

The lamp holder320receives an end portion of the lamp310to protect the lamp310and fastens the lamp310to the receiving container200. The lamp holder320includes a buffer portion330. The buffer portion330protrudes toward the first side face111of the light guide plate100. The buffer portion330absorbs any impact applied by the lamp holder320, which is caused by the floating of the light guide plate100, so that damages to the light guide plate100and the lamp310are prevented.

The lamp unit300may further include a lamp cover (not shown). The lamp cover protects the lamp310. The lamp cover includes a material having a relatively high optical reflectivity. In some embodiments, a material of high optical reflectivity may be coated on a surface of the lamp cover to reflect the light generated by the lamp310toward the first side face111of the light guide plate100. Therefore, light-using efficiency is enhanced.

FIG. 2is a perspective view illustrating a lamp holder ofFIG. 1, andFIG. 3is a cross-sectional view taken along a line I-I′ inFIG. 2.

Referring toFIGS. 2 and 3, the lamp holder320includes a body having a rectangular parallelepiped shape and the buffer portion330. The body has a first face321, a second face322, a third face323, a fourth face324, a fifth face325and a sixth face326. The buffer portion330is formed at the first face321.

The buffer portion330protrudes from the first face321toward the first side face111of the light guide plate100by a thickness t1. The buffer portion330absorbs the impact applied to the light guide plate100or the lamp holder320, reducing the damages to the light guide plate100and the lamp holder320.

The buffer portion330includes a buffer opening335. A portion of the buffer portion330is removed to form the buffer opening335. The buffer opening335has a width t2that is smaller than the thickness t1of the buffer portion330.

The buffering opening335provides the buffer portion330with a space for compression to absorb the impact applied to the lamp holder320.

The lamp holder320formed on the second face322further includes a first hole322aand a second hole322bfor receiving the lamp(s)310. The first hole322aand the second hole322bare formed on the second face322of the lamp holder320. The lamp holder320further includes a third hole323aand a fourth hole323bformed at the third face323facing the first face321. The third hole323aand the fourth hole323bare connected to the first hole322aand the second hole322b, respectively. Wires for applying a driving voltage to the lamp310are disposed in the third hole323aand the fourth hole323b.

FIG. 4is a plan view illustrating a portion of the receiving container combined with a lamp unit inFIG. 2, andFIG. 5is a cross-sectional view taken along a line II-II′ inFIG. 4.

Referring toFIGS. 4 and 5, the LPG-fixing member211protrudes from the base plate210of the receiving container200to be disposed between the first face111of the light guide plate100and the buffer portion330of the lamp holder320. The LPG-fixing member211makes contact with the buffer portion330. The LPG-fixing member211has a width of t3that is greater than the thickness t1of the buffer portion330.

Therefore, when the receiving container200receives the light guide plate100, the first face111of the light guide plate110makes contact with the LGP-fixing member211, and the first face111of the light guide plate110is spaced apart from the buffer portion330of the lamp holder320by a distance d. The distance d corresponds to a difference between the width t3of the LGP-fixing member211and the thickness t1of the buffer portion330. The distance d is, for example, in a range of about 0.05 mm to about 0.1 mm.

When impact is applied to the backlight assembly, the LGP-fixing member211fastens the light guide plate100to the receiving container200, and even when excessive impulse is applied to the backlight assembly, the buffer opening335absorbs the impact to reduce damages to the lamp unit300and the light guide plate100.

The third hole323aand the fourth hole323b, where the wirings for applying the driving voltage to the lamp100are disposed, absorb the impact applied by the first sidewall220of the receiving container200.

FIG. 6is a graph showing the relationship between impact time and an LGP floating distance of the backlight assembly inFIG. 1. “Impact time” is measured from the moment an impact is applied to the backlight assembly.

In order to measure the LGP floating distance, an LGP floating distance measuring device (not shown) was disposed at the first side face111of the light guide plate100.

Referring toFIG. 6, a graph (a) corresponds to an LGP floating distance of a light guide plate in a conventional backlight assembly, and a graph (b) corresponds to an LGP floating distance of the light guide plate in the backlight assembly ofFIGS. 1 through 5.

According to the graph (a), the maximum LGP floating distance of the conventional backlight assembly is about 2.14 mm, whereas, according to the graph (b), a maximum LGP floating distance of the backlight assembly according to the present embodiment is about 1.92 mm. As a result, the maximum LGP floating distance of the backlight assembly according to the present embodiment is reduced by about 10.3% with reference to the maximum LGP floating distance of the conventional backlight assembly.

FIG. 7is a graph showing a relationship between impact time and an LGP lamp stress of the backlight assembly inFIG. 1.

Referring toFIG. 7, a graph (c) corresponds to the lamp stress experienced by a light guide plate in the conventional backlight assembly, and a graph (d) corresponds to the lamp stress experienced by the light guide plate in the backlight assembly inFIGS. 1 through 5.

According to graph (c), the maximum lamp stress of the conventional backlight assembly in response to an impact is about 117 Mpa. In comparison, according to the graph (d), the maximum lamp stress of the backlight assembly according to the present embodiment is about 78 Mpa. These results indicate that the maximum lamp stress of the backlight assembly according to the present embodiment is reduced by about 33% relative to the maximum lamp stress of the conventional backlight assembly.

As shown inFIGS. 6 and 7, the backlight assembly according to the present embodiment has reduced LGP floating distance and lamp stress, so that damages to the lamp and the receiving container are reduced or even prevented.

FIG. 8is an exploded perspective view illustrating a backlight assembly according to a second exemplary embodiment of the present invention, andFIG. 9is a plan view illustrating a portion of the receiving container combined with a lamp unit inFIG. 8.

The backlight assembly as shown inFIG. 8is substantially the same as the backlight assembly as shown inFIGS. 1 to 5, except for a first receiving container400and a second receiving container450. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the first exemplary embodiment and any further explanation concerning the already-described elements will be omitted.

Referring toFIGS. 8 and 9, the backlight assembly according to the second exemplary embodiment includes a first receiving container400and a second receiving container450.

The first receiving container400includes a first base plate410and a first frame portion protruding from edge portions of the first base plate410. The first receiving container400receives the second receiving container450.

The first frame portion includes a first sidewall420a, a second sidewall420b, a third sidewall420cand a fourth sidewall420d. The first sidewall420amakes contact with the lamp unit300. The second sidewall420bis parallel to the first sidewall420a. The third sidewall420cconnects a first end portion of the first sidewall420aand a first end portion of the second sidewall420b. The fourth sidewall420dconnects a second end portion of the first sidewall420aand a second end portion of the second sidewall420b, and the fourth sidewall420dis parallel to the third sidewall420c. Two end portions of the lamp310make contact with the third and fourth sidewalls420cand420d, respectively.

The third and fourth sidewalls420cand420dinclude LGP fixing members425, respectively. Each of the LGP fixing members425has a thickness t3. The LGP fixing members425protrude from the third and fourth sidewalls420cand420dsuch that the LGP fixing members425extend parallel to the first and second sidewalls420aand420b.

The second receiving container450includes a second base plate451and a second frame portion protruding from edge portions of the second base plate451. The second receiving container450receives the light guide plate100and the lamp unit300. The second frame portion includes a fifth sidewall452a, a sixth sidewall452b, a seventh sidewall452cand an eighth sidewall452d. The fifth sidewall452acorresponds to the first sidewall420aof the first receiving container400. The sixth sidewall452bcorresponds to the second sidewall420bof the first receiving container400. The seventh sidewall452ccorresponds to the third sidewall420cof the first receiving container400, and the eighth sidewall452dcorresponds to the fourth sidewall420dof the first receiving container400.

The second receiving container450includes slits455. The LGP fixing members425of the first receiving container400are inserted into the slits455when the two receiving containers400,450are combined. When the first receiving container400receives the light guide plate100and the lamp unit300, two end portions of the first face111of the light guide plate100make contact with the LGP fixing members425, respectively.

The buffer portion330of the lamp holder320has a thickness of t1that is smaller than the third width t3of the LGP fixing member425, so that the first face111of the light guide plate100is spaced apart from the buffer portion330by a distance d.

Therefore, when impact is applied to the backlight assembly, the LGP fixing members425prevent the floating of the light guide plate100. Furthermore, the buffer portion330absorbs the impact. Additionally, the buffer opening335absorbs the impact.

According to the present embodiment, the second receiving container450includes, for example, metal in order to dissipate heat and block electromagnetic interference. Where it is desirable to reduce the device weight and thickness, the second receiving container450may be omitted from the backlight assembly.

FIG. 10is a perspective view illustrating a lamp holder according to a third exemplary embodiment of the present invention.FIG. 11is a cross-sectional view taken along a line III-III′ inFIG. 10, andFIG. 12is a cross-sectional view taken along a line IV-IV′ inFIG. 10.

The same reference numerals will be used to refer to the same or like parts as those described inFIG. 2, and any further explanation concerning the above elements will be omitted.

Referring toFIGS. 10 to 12, the lamp holder500includes a first buffer opening510, a second buffer opening520and a third buffer opening521. The first buffer opening510is formed at the buffer portion330. The first buffer opening510is substantially same as the buffer opening335inFIG. 2.

The second buffer opening520is adjacent to the fourth face324. The second buffer opening520extends between the first face321and the third face323.

The fourth face324makes contact with the third sidewall240of the receiving container200, and the sixth face326makes contact with the base plate210of the receiving container200. Therefore, the second buffer opening520absorbs any impact applied to the third sidewall240of the receiving container200, and the third buffer opening530absorbs any impact applied to the base plate210of the receiving container200.

The lamp holder500according to the present embodiment may further include a second buffer portion and a third buffer portion protruding from the fourth face324and the sixth face326, respectively, and the second buffer opening520and the third buffer opening521may be formed on the second and third buffer portions, respectively.

FIG. 13is a perspective view illustrating a lamp holder according to a fourth exemplary embodiment of the present invention.

The lamp holder as shown inFIG. 13is substantially the same as the lamp holder inFIG. 2, except for a buffer portion610. Thus, the same reference numerals will be used to refer to the same or like parts as those described inFIG. 2, and any further explanation concerning the above elements will be omitted.

Referring toFIG. 13, the lamp holder600includes a body having a rectangular parallelpiped shape and a buffer portion610. The body has a first face321, a second face322, a third face323, a fourth face324, a fifth face325and a sixth face326. The buffer portion610includes a plurality of protrusions protruding from the first face321by a thickness t1. The protrusions are spaced apart from each other. Each of the protrusions has a linear shape.

The buffer portion610absorbs any impact applied to the lamp holder600like a spring. Therefore, damages caused by the floating of the light guide plate100or impacts applied to the light guide plate are reduced or prevented.

FIG. 14is a perspective view illustrating a lamp holder according to a fifth exemplary embodiment of the present invention.

The lamp holder as shown inFIG. 14is substantially the same as the lamp holder as shown inFIG. 2, except a buffer portion610. Thus, the same reference numerals will be used to refer to the same or like parts as those described inFIG. 2, and any further explanation concerning the already-described elements will be omitted.

Referring toFIG. 14, a lamp holder700according to the fifth exemplary embodiment includes a buffer portion710formed at the first face321. The buffer portion710includes a plurality of protrusions715. The protrusions715are spaced apart from each other and protrude from the first face321. Each of the protrusions715has, for example, a cylindrical shape. However, the shape of the protrusions is not a limitation of the invention and each of the protrusions715may have any shape such as a truncated cone shape, truncated pyramid shape, etc.

The protrusions715of the buffer portion710absorb the impact applied by the lamp holder700like a spring. Therefore, damages caused by floating of the light guide plate100or impacts applied to the light guide plate100are reduced or prevented.

FIG. 15is a perspective view illustrating a lamp holder according to a sixth exemplary embodiment of the present invention.FIG. 16is a cross-sectional view taken along a line V-V′ inFIG. 15, andFIG. 17is a cross-sectional view taken along a line VI-VI′ inFIG. 15.

The same reference numerals will be used to refer to the same or like parts as those described inFIG. 2, and any further explanation concerning the above elements will be omitted.

Referring toFIGS. 15 to 17, a lamp holder800according to the sixth exemplary embodiment includes a first buffer opening810and a second buffer opening820. The first buffer opening810and second buffer opening820penetrate between the fifth face325and the sixth face326. The first buffer opening810is adjacent to the first face321, and the second buffer opening820is adjacent to the fourth face324.

The lamp holder800further includes a first hole830and a second hole840. The first hole830is formed on the second face322. The first hole830receives a lamp (not shown). The second hole840is formed on the sixth face326. The second hole840receives wires (not shown) for driving the lamp.

The first buffer opening810absorbs the impact applied to the first side face of the light guide plate (not shown), and the second buffer opening820absorbs the impact applied to the receiving container200.

FIG. 18is a perspective view illustrating a lamp holder900according to a seventh exemplary embodiment of the present invention, andFIG. 19is a cross-sectional view taken along a line VII-VII′ inFIG. 18.

The lamp holder900as shown inFIGS. 18 and 19is substantially the same as the lamp holder as shown inFIG. 13except for the number of holes for receiving the lamp and the number and position of wire holes. Thus, the same reference numerals will be used to refer to the same or like parts as those described inFIG. 13, and any further explanation concerning the already-described elements will be omitted.

Referring toFIGS. 18 and 19, the lamp holder900includes a buffer portion910formed at a first face321of the lamp holder900. The buffer portion910includes a plurality of grooves spaced apart from each other. The grooves have a rectangular shape. In other words, rectangular portions of the first face321are removed to form the buffer portion910. The removed rectangular portions may be spaced apart from each other at a regular interval.

The lamp holder900further includes a first hole920for receiving a lamp (not shown) and a second hole930for receiving the wires that apply the driving voltage to the lamp.

FIG. 20is an exploded perspective view illustrating a display apparatus according to an exemplary embodiment of the present invention.

Referring toFIG. 20, a display apparatus according to the present embodiment includes a backlight assembly1000and a display panel1100. The backlight assembly1000is substantially same as that ofFIG. 1. Thus, the same reference numerals will be used to refer to the same or like parts as those described inFIG. 1, and any further explanation concerning the already-explained elements will be omitted.

The display panel1100includes a thin film transistor (TFT) substrate1110, a color filter substrate1120, and a liquid crystal layer (not shown). The TFT substrate1110and the color filter substrate1120are substantially parallel to each other, and the liquid crystal layer is disposed between the TFT substrate1110and the color filter substrate1120. When electric fields are applied to the liquid crystal layer, the arrangement of liquid crystal molecules in the liquid crystal layer is altered to change the optical transmittance. This way, the display panel1100converts the light provided by the backlight assembly1000into an image.

The display apparatus may further include a top chassis (not shown) that is designed to fit with a receiving container200. The top chassis surrounds the edge portions of the display panel1100disposed on the backlight assembly1000to prevent the display panel1100from being separated from the backlight assembly1000. The top chassis also protects the display panel1100from being damaged by an external impact.

According to the backlight assembly and the display apparatus of the present invention, when impact is applied to thereto, the LGP fixing member211on the receiving container200and the buffer portion330on the lamp holder320absorb the impact to prevent the light guide plate100from floating toward the lamp unit300.

Additionally, the buffer opening further absorbs the impact.

According to the present invention, the LGP fixing member protrudes from the base plate of the receiving container and a portion of the lamp holder protrudes toward the light guide plate to form the buffer portion.

Therefore, the LGP fixing member prevents the light guide plate from floating, and the buffer portion absorbs the impact caused by any unprevented floating of the light guide plate. Furthermore, the buffer opening further absorbs the impact to relieve the damages. The overall effect of using the lamp holder of the invention is a significant reduction in the damages to the lamp unit and the light guide plate, and the resultant reliability enhancement for the device.

Having described the exemplary embodiments of the present invention and its advantages, it is 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.