Backlight assembly and liquid crystal display apparatus

Disclosed is a backlight assembly and an LCD apparatus having uniform brightness and low power consumption. The backlight assembly has a plurality of lamps for providing light to the LCD panel. Each of the plurality of lamps has two or more sub-lamps connected to each other in series. The backlight assembly has a brightness control unit disposed between the sub-lamps to reduce a brightness difference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a backlight assembly and an LCD (Liquid Crystal Display) apparatus, and more particularly to a backlight assembly and LCD apparatus having uniform brightness and low power consumption.

2. Description of the Related Art

An LCD apparatus displays images using electric signals generated from a device processing image information. In order to display images, an LCD apparatus is generally provided with a liquid crystal control device and a light supply device. The liquid crystal control device controls the liquid crystal in response to the electric signals from the image information processing device, and the light supply device supplies light to the liquid crystal control device.

The light supply device may be an one-dimensional light source for generating one-dimensional light such as point light or linear light, or a two-dimensional light source for generating two-dimensional light such as surface light. The LCD apparatus employs the one-dimensional light source such as a CCFL (Cold Cathode Fluorescent Lamp) generating one-dimensional light.

However, the length of a CCFL becomes longer as the display size of an LCD apparatus becomes larger. Where the length of a CCFL becomes longer, a voltage for driving the CCFL, heat emitted from the CCFL and power consumption in the CCFL increase. Also, since the weight of a CCFL increases in accordance with increase in its length, the CCFL may be bent, thereby deteriorating display quality of the LCD apparatus.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a backlight assembly having uniform brightness and requiring low power consumption.

The present invention also provides an LCD apparatus having uniform brightness and requiring low power consumption. In one aspect of the invention, there is provided a backlight assembly comprising:

a receiving container having a bottom surface and a sidewall extended from the bottom surface; a plurality of lamps disposed on the bottom surface, each of the lamps having two or more sub-lamps connected to each other in series, the two or more sub-lamps being disposed in a first direction, for generating light; a lamp holder disposed on the bottom surface in a second direction perpendicular to the first direction, for receiving a connection portion where the sub-lamps are connected to each other; and a diffusing plate disposed on the receiving container, for diffusing the light emitted from the lamps.

In another aspect, there is provided an LCD apparatus comprising:

a receiving container having a bottom surface and a sidewall extended from the bottom surface; a plurality of lamps disposed on the bottom surface, each of the lamps having two or more sub-lamps connected to each other in series and disposed in a first direction, wherein the sub-lamps generate light having first brightness at an area proximate the sub-lamps and light having second brightness at an area proximate a connection portion where the sub-lamps are connected to each other; a lamp holder disposed on the bottom surface, for receiving the connection portion; a brightness control unit for reflecting a portion of the light emitted from the lamps to reduce a brightness difference between the first brightness and the second brightness, the brightness control unit being disposed on the lamp holder; a diffusing plate disposed on the receiving container, for diffusing the light emitted from the lamps; and an LCD panel disposed on the diffusing plate, for receiving the light from the diffusing plate and displaying an image.

According to the present invention, a backlight assembly has the plurality of lamps for providing light to an LCD panel. Each of the lamps has two or more sub-lamps connected to each other in series. Also, a backlight assembly has a brightness control unit disposed between the sub-lamps to reduce the brightness difference between the sub-lamps. Thus, the backlight assembly may reduce consumption power of the lamps having the two or more sub-lamps and provide the light having uniform brightness to the LCD panel.

DETAILED DESCRIPTION OF THE INVENTION

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

Referring toFIG. 1, the backlight assembly700includes a receiving container100, a reflecting plate115, lamps200, a lamp holder300, a brightness control unit400and a diffusing plate500. A lamp200may have, for example, two or more sub-lamps210and the backlight assembly700may have the lamps200each having two or more sub lamps210.

The receiving container100includes a bottom surface110and sidewalls120each extended from an edge portion of the bottom surface110. The bottom surface110, for example, has a rectangular shape. InFIG. 1, a first direction is the longitudinal direction of the bottom surface110and a second direction is the widthwise direction perpendicular to the first direction. The lamps200are disposed on the bottom surface110of the receiving container100. Each of the sub-lamps210includes a lamp tube211, a first electrode220, and a second electrode230.

FIG. 2is an enlarged view of portion A in FIG.1. Referring toFIG. 2, the lamp tube211includes a tube body212, a fluorescent material214and a discharge gas216. The tube body212has a tube shape sealed at opposite end portions thereof. The fluorescent material214is deposited on an inner surface of the tube body212and the discharge gas216is injected into the tube body212.

The first and second electrodes220and230are disposed inside the opposite end portions of the tube body212and connected to a lead line, respectively. The first and second electrodes220and230receive a discharge voltage having a potential difference appropriate to ionize the discharge gas216in the lamp tube211, so that light is emitted from the lamp tube211.

The lamp200having the two sub-lamps210is disposed on the bottom surface110of the receiving container100in the first and second directions. The two sub-lamps210of the lamp200are electrically connected in series through the first electrodes220thereof. Where the backlight assembly700has two or more lamps having a structure such as the lamp200having the two sub-lamps210, the lamps are connected to each other in parallel.

FIG. 3is a perspective view showing the lamp holder300shown in FIG.1. Referring toFIG. 3, the lamp holder300includes a lamp holder body310and lamp receiving grooves320disposed on the lamp holder body310. The lamp holder body310is disposed on the bottom surface110in the second direction and has a bar shape, as a whole, with a bottom surface wider than its top surface.

The lamp receiving grooves320are formed on the lamp holder body310, and the number of the lamp receiving grooves320is corresponding to the number of the lamps200employed in the backlight assembly700. Each of the lamp receiving grooves320has a depth and a width suitable to receive the sub-lamp210. The lamp receiving grooves320are each provided with a protrusion portion325for preventing the sub-lamps210from being movable because the sub-lamps210received into the lamp receiving grooves320may move in the first direction. The protrusion portions325are protruded from sidewalls, respectively, of the lamp receiving groove320and are disposed between the sub-lamps210of the lamp200.

FIG. 4is a schematic view showing an assembled structure between a lamp holder and a receiving container according to an exemplary embodiment of the present invention. Referring toFIG. 4, the lamp holder body310may be adhered to the bottom surface110using adhesive, for example, double-sided tape330.

FIG. 5is a schematic view showing an assembled structure between a lamp holder and a receiving container according to another embodiment of the present invention.

Referring toFIG. 5, the lamp holder body310is provided with engaging protrusions340and the bottom surface110is provided with engaging openings112corresponding to the engaging protrusions340, respectively. The lamp holder body310and bottom surface110are engaged to each other by engaging the engaging protrusions340into the engaging openings112, respectively.

FIG. 6is a schematic view showing a connection structure of the two sub-lamps210according to an exemplary embodiment of the present invention. Referring toFIG. 6, the lead lines each connected to the corresponding first electrode220of the respective sub-lamps210are soldered to each other by a solder225.

FIG. 7is a schematic view showing a connection structure of the two sub-lamps according to another embodiment of the present invention.

Referring toFIG. 7, the lead lines each connected to the corresponding first electrode220of the respective sub-lamps210are electrically connected to each other by a conductive connection member260having, for example, a cylindrical shape. In this embodiment, the two sub-lamps210are connected to each other using the conductive connection member260such that a sub-lamp210may be easily replaced with a new sub-lamp when the sub-lamp210is in trouble.

Referring toFIG. 1again, the second electrodes230of the sub-lamps210are connected to a first power supply unit600and a second power supply unit650on which power is externally applied.

The first power supply unit600is disposed on one end portion of the bottom surface110in the second direction. The first power supply unit600includes a first metal plate610having a band shape and a first gripping clip620for gripping one lead line of the second electrodes230of the two sub-lamps210. The first gripping clip620provides the external power to the corresponding sub-lamp210. As shown inFIG. 1, the first power supply unit600may have multiple first gripping clips620each for providing the external power to the corresponding sub-lamp210.

The second power supply unit650is disposed on the other end portion of the bottom surface110in the second direction. In other words, the first and second power supply units600and650are disposed at the opposite end portions of the bottom surface110. The second power supply unit650includes a second metal plate660having a band shape and a second gripping clip670for gripping one lead line of the second electrodes230of the two sub-lamps210. The second gripping clip670provides the external power to the corresponding sub-lamp210. The second supply unit650may also have multiple second gripping clips670each for providing the external power to the corresponding sub-lamp210.

The first and second power supply units600and650receive the discharge voltage to make a predetermined potential difference between the first and second electrodes220and230. The first electrodes220of the two sub-lamps210connected to each other may be connected to a separate power supply line. The power supply line may be grounded or receive an alternating current. The second electrodes230receive an alternating current from the first and second power supply units600and650as the discharge voltage.

On the other hand, the two sub-lamps210may receive the alternating current having a phase difference of 180 degrees through the second electrodes230from the first and second power supply units600and650. In this case, the first electrodes220of the two sub-lamps210are electrically connected to each other using the solder or conductive connection member260without the separate power supply line.

FIG. 8is a schematic view showing a structure of the brightness control unit400shown in FIG.1andFIGS. 9 and 10are cross-sectional views of the brightness control unit400shown in FIG.8.

Referring toFIGS. 8 and 9, the brightness control unit400includes a first light diffusing surface410, a second light diffusing surface420, a third light diffusing surface430and a fourth light diffusing surface440.

The first and second light diffusing surfaces410and420are inclined with respect to an imaginary line “I” at a first angle “α” and the first and second light diffusing surfaces410and420are symmetrical to each other. The third and fourth light diffusing surfaces430and440are inclined with respect to the first and second light diffusing surfaces410and420at a second angle “β”, respectively. The third and fourth diffusing surfaces430and440are symmetrical to each other. The imaginary line “I” is perpendicular to the bottom surface110of the receiving container100. The brightness control unit400diffuses the light from the lamps200and may be formed by an injection-molding manner of resin.

Referring toFIG. 10, the brightness control unit400includes a metal plate460bent to have the first to fourth light diffusion surfaces410-440, a light diffusing layer470, an adhesive480and an insulating layer490.

The light diffusing layer470is disposed on an outer surface of the metal plate460by coating light diffusing material or adhering a light diffusing sheet thereto. The insulating layer490is disposed on an inner surface of the metal plate460so as to reduce a parasitic capacitance caused by disposing the light diffusing layer470on the metal plate460.

Referring toFIGS. 8 and 9, the third and fourth light diffusing surfaces430and440are provided with lamp receiving openings450disposed at edge portions thereof. The lamp receiving openings450respectively receive the lamps200when combining to the lamp holder300. In order to combine the brightness control unit400to the lamp holder300, the adhesive480is partially disposed on an inner surface of the third and fourth light diffusing surfaces430and440.

FIG. 11is a schematic view for illustrating an operation of the brightness control unit400shown in FIG.10.

Referring toFIG. 11, when turning on the lamps200, the light emitting region may be divided into a first area having first brightness and a second area having second brightness darker than the first brightness. The second area is about an area between the two sub-lamps210. A user may realize that the second area is darker than the first area due to the brightness difference between the first and second areas. The brightness control unit400reflects the light provided from the first area to the first and second light diffusing surfaces410and420on which the light is diffused toward the second area to reduce the brightness difference between the first and second areas. Then, the diffusing plate500(referring toFIG. 1) diffuses the light emitted from the lamps200and the light reflected from the brightness control unit400to provide light having uniform brightness. The diffusing plate500is disposed on the receiving container100.

FIG. 12is a perspective view showing a structure of an LCD apparatus according to the present invention.

Referring toFIG. 12, the LCD apparatus1000includes a backlight assembly700, an LCD panel assembly800and a chassis900.

The LCD panel assembly800includes a TFT (Thin Film Transistor) substrate810, a color filter substrate820, and liquid crystal (not shown) interposed between the TFT substrate810and color filter substrate820. The TFT substrate810comprises TFTs disposed on a transparent glass substrate in a matrix configuration and pixel electrodes for receiving a power voltage from the TFTs. The color filter substrate820is disposed facing the TFT substrate810. The color filter substrate820includes a color filter disposed on a glass substrate facing the pixel electrode and a common electrode disposed over the glass substrate to cover the color filter. The LCD panel assembly800is disposed on the receiving container100of the backlight assembly700.

The chassis900is combined to the receiving container100to prevent the LCD panel assembly800from being deviated from the receiving container100.

According to the exemplary embodiments of the present invention, the backlight assembly has the plurality of lamps for providing light to the LCD panel. Each of the lamps has two or more sub-lamps connected to each other in series. Also, the backlight assembly has the brightness control unit disposed between the sub-lamps to reduce the brightness difference between the sub-lamps. Thus, the backlight assembly may reduce consumption power of the lamps and provide the light having uniform brightness. Further, an LCD apparatus according to the present invention may use sub-lamps each having a length shorter than that of a display area thereof.