LCD Backlight unit and LCD having the same

• US 7,221,416 B2
• Filed: 11/29/2004
• Issued: 05/22/2007
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Park, Young Sam, Ahn, Ho Sik, Kim, Hyung Suk, Jeong, Young June, Hahm, Hun Joo, Park, Jung Kyu
• Primary Examiner(s): Dudek; James A.
• Application Number:
  US10/997,895
• Publication Number:
  US 20060055843A1
• Time in Patent Office: 904 Days
• Field of Search: 349/65, 349/69, 362612-613
• US Class Current: 349/65
• CPC Class Codes: G02B 5/021 the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
• CPC Class Codes: G02B 5/0284 used in reflection
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]

Abstract

An LCD backlight apparatus includes a light guide plate placed under an LCD panel of the LCD to guide light to the LCD panel. The light guide plate has an even upper surface and a scattering pattern formed in a bottom surface. A plurality of monochromatic light sources are placed in line at a side of the light guide plate to radiate light along the plane direction of the light guide plate between the upper and bottom surfaces of the light guide plate. The light sources are adapted to radiate light beams at a predetermined beam angle so that the light beams reach the scattering pattern only after having propagated a predetermined reference length necessary for forming white light when mixed together. The LCD backlight apparatus can reduce the Bezel width without increasing the thickness of the LCD.

Claims

1. A Liquid Crystal Display (LCD) backlight apparatus for an LCD, said backlight apparatus comprising:

a light guide plate adapted to be placed under an LCD panel of the LCD to guide light to the LCD panel, the light guide plate having an even upper surface and a scattering pattern formed on a bottom surface thereof; and

a plurality of monochromatic light sources placed in line at a side of the light guide plate to radiate light along the plane direction of the light guide plate between the upper and bottom surfaces of the light guide plate;

wherein

the light sources are adapted to radiate light beams at a predetermined beam angle so that the light beams reach the scattering pattern only after having propagated a predetermined reference length necessary for forming white light when the light beams are mixed together; and

each of the monochromatic light sources includes a Light Emitting Diode (LED) chip and an LED lens for directing light emitted from the LED chip at predetermined upward and downward beam angles into the light guide plate.

2. The LCD backlight apparatus according to claim 1, wherein the monochromatic light sources are placed at one side of the light guide plate.

3. The LCD backlight apparatus according to claim 1, wherein the monochromatic light sources are placed at both sides of the light guide plate.

4. The LCD backlight apparatus according to claim 1, wherein the upward and downward beam angles are the same.

5. The LCD backlight apparatus according to claim 1, wherein the downward beam angle is smaller than the upward beam angle.

6. The LCD backlight apparatus according to claim 1, wherein the scattering pattern is divided into a first area extended from an edge of the light guide plate to a point in which the light beams from the monochromatic light sources are mixed together and a second area extended from the first area, and wherein the scattering pattern is denser in the first area than in the second area.

7. The LCD backlight apparatus according to claim 1, wherein the light guide plate comprises a plurality of light guide plates.

8. The LCD backlight apparatus according to claim 1, wherein the reference length l and the upward and downward beam angles β

are determined by Equations 1 and 2 below;

l=k×

P/tan(θ

/2) 

 

Equation 1, and

β

=sin<sup>−

1</sup>(h/l) 

 

Equation 2,

wherein k is coefficient of correlation, θ

is a planar beam angle of the light sources, P is a pitch of the light sources, and h is a height from the bottom surface of the light guide plate to the light sources.

9. A Liquid Crystal Display (LCD), comprising:

an LCD panel for displaying images in response to input electric signals;

a circuit board for applying the input electric signals to the LCD panel;

a backlight apparatus placed under the LCD panel to provide backlight to the LCD panel, wherein the backlight apparatus includes;

a light guide plate placed under the LCD panel of the LCD to guide light to the LCD panel, the light guide plate having an even upper surface and a scattering pattern formed on a bottom surface thereof; and

a plurality of monochromatic light sources placed in line at a side of the light guide plate to radiate light along the plane direction of the light guide plate between the upper and bottom surfaces of the light guide plate; and

a housing for housing the LCD panel, the circuit board and the backlight apparatus;

wherein

the light sources are adapted to radiate light beams at a predetermined beam angle so that the light beams reach the scattering pattern only after having propagated a predetermined reference length necessary for forming white light when the light beams are mixed together; and

each of the monochromatic light sources includes a Light Emitting Diode (LED) chip and an LED lens for directing light emitted from the LED chip at predetermined upward and downward beam angles into the light guide plate.

10. The LCD according to claim 9, wherein the monochromatic light sources are placed at both sides of the light guide plate.

11. The LCD according to claim 9, wherein the monochromatic light sources are placed at one side of the light guide plate.

12. The LCD according to claim 9, wherein the upward and downward beam angles are the same.

13. The LCD according to claim 9, wherein the downward beam angle is smaller than the upward beam angle.

14. The LCD according to claim 9, wherein the scattering pattern is divided into a first area extended from an edge of the light guide plate to a point in which the light beams from the monochromatic light sources a mixed together and a second area extended from the first area, and wherein the scattering pattern is denser in the first are than in the second area.

15. The LCD according to claim 9, wherein the light guide plate comprises a plurality of light guide plates.

16. The LCD according to claim 9, wherein the reference length l and the upward and downward beam angles β

are determined by Equations 1 and 2 below;

l=k×

P/tan(θ

/2) 

 

Equation 1, and

β

=sin<sup>−

1</sup>(h/l) 

 

Equation 2,

wherein k is coefficient of correlation, θ

is a planar beam angle of the light sources, P is a pitch of the light sources, and h is a height from the bottom surface of the light guide plate to the light sources.