Backlight unit and liquid crystal display device having the same

1. A backlight unit, comprising:

a light-guiding plate having a plurality of grooves, wherein an opening portion of the grooves is formed on the upper portion of the light-guiding plate and a width of the grooves is formed to be gradually narrower as it goes from a central portion of the grooves to the opening portion of the grooves;

a plurality of light-emitting lamps in the respective grooves of the light-guiding plate, wherein each of the lamps includes an external electrode fluorescent lamp having first and second external electrodes at both external ends of a tube;

lamp holders affixing the first and second external electrodes provided at the both external ends of the tube, wherein an entire circumference of the first and second external electrodes is enclosed by the lamp holders and each of the first and second external electrodes corresponds one-on-one with a lamp holder; and

a light-diffusion sheet above the light-guiding plate and the lamps.

2. The backlight unit of claim 1 , wherein the light-guiding plate includes acrylic resin.

3. The backlight unit of claim 1 , further comprising a reflective sheet under the light-guiding plate.

4. The backlight unit of claim 1 , wherein the light-diffusion sheet is composed of one sheet.

5. A liquid crystal display device, comprising:

an LCD panel including upper and lower substrates, and a liquid crystal layer between the upper and lower substrates; and

a backlight unit including a light-guiding plate with a plurality of grooves, a plurality of light-emitting lamps in the grooves of the light-guiding plate and including an external electrode fluorescent lamp having first and second external electrodes at both external ends of a tube, lamp holders affixing the first and second external electrodes provided at the both external ends of the tube, and a light-diffusion sheet above the light-guiding plate and the lamps;

wherein an opening portion of the grooves is formed on the upper portion of the light- guiding plate and a width of the grooves is formed to be gradually narrower as it goes from a central portion of the grooves to the opening portion of the grooves; and

wherein an entire circumference of the first and second external electrodes is enclosed by the lamp holders and each of the first and second external electrodes corresponds one-on-one with a lamp holder.

6. The device of claim 5 , wherein the light-guiding plate includes acrylic resin.

7. The device of claim 5 , further comprising a reflective sheet under the light-guiding plate.

8. The device of claim 5 , wherein the light-diffusion sheet is composed of one sheet.