Illumination system and display device

• US 20020135997A1
• Filed: 10/25/2001
• Published: 09/26/2002
• Est. Priority Date: 10/25/2000
• Status: Active Grant

• Current Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Lammers, Liane
• Granted Patent: US 6,672,734 B2
• Time in Patent Office: Days
• US Class Current: 362/31
• 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 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

A backlight system comprises a light-emitting panel (1) having a front wall (2) and, opposite thereto, a rear wall (3), and opposite first and second light-transmitting edge surfaces (4; 5) associated with a plurality of first and second light sources (6; 7). Light originating from the light sources (6; 7) is diffused in the panel (1). Parts of the surface areas (8; 9) of the rear wall (3) are provided with extraction means (18, 18′, . . . ; 19, 19′, . . . ) for extracting light from the panel (1). First extraction means (18, 18′, . . . ) extract light from, preferably, the first light source (6), and vice versa In operation, said parts of the surface areas (8; 9) project light on a (LCD) display device panel (34) with an associated color filter (35). In the vicinity of the second edge area (5), the concentration of the first extraction means (18, 18′, . . . ) is higher than that of the second extraction means (19, 19′, . . . ), and vice versa. Preferably, the extraction means (18, 18′, . . . , 19, 19′, . . . ) are wedge-shaped, a side surface of the first extraction means (18, 18′, . . . ) directed towards the second light source (7) extending parallel to the second edge surface (5), and vice versa. Preferably, the light sources (6; 7) comprise a plurality of blue, green, (amber) and red LEDs, each preferably having a luminous flux of at least 5 lumen.

Claims

1. An illumination system for illuminating a display device, which illumination system is provided with a light-emitting panel (1) comprising

a front wall (2) and, opposite thereto, a rear wall (3) as well as a first and a second light-transmitting edge surface (4, 5) which are situated between the front wall (2) and the rear wall (3),

at least one first light source (6) being associated with the first edge surface (4) and at least one second light source (7) being associated with the second edge surface (5), and

in operation, light originating from the first light source (6) being incident on the first light-transmitting edge surface (4), and light originating from the second light source (7) being incident on the second light-transmitting edge surface (5), said light spreading in the light-emitting panel (1), characterized in that,

a first sub-surface (8) of the front wall (2) or of the rear wall (3) of the light-emitting panel (1) is provided with first coupling-out members (18, 18′

, . . . ) for coupling light out of the panel (1), which light predominantly originates from the first light source (6), and

in that a second sub-surface (9) of the front wall (2) or of the rear wall (3) of the light-emitting panel (1) is provided with second coupling-out members (19, 19′

, . . . ) for coupling light out of the panel (1), which light predominantly originates from the second light source (7),

the concentration of the first coupling-out members (18, 18′

, . . . ) near the second edge surface (5) being higher than the concentration of the second coupling-out members (19, 19′

, . . . ), and

the concentration of the second coupling-out members (19, 19′

, . . . ) near the first edge surface (4) being higher than the concentration of the first coupling-out members (18, 18′

, . . . ).

2. An illumination system as claimed in claim 1, characterized in that the first and second coupling-out members (18, 18′

, . . . ;

19, 19′

, . . . ) are wedge-shaped,

a side face of the first coupling-out members (18, 18′

, . . . ) facing the second light source (7) extending at least substantially parallel to the second edge surface (5), and

a side face of the second coupling-out members (19, 19′

, . . . ) facing the first light source (6) extending at least substantially parallel to the first edge surface (4).

3. An illumination system as claimed in claim 1 or 2, characterized in that each of the sub-surfaces (8, 9) comprises a single surface which covers approximately half the front wall (2) or rear wall (3) of the light-emitting panel (1),

the coupling-out members (18, 18′

, . . . ;

19, 19′

, . . . ) being provided such that the degree to which light is coupled out by the sub-surfaces (8, 9) is at least substantially constant.

4. An illumination system as claimed in claim 1 or 2, characterized in that the sub-surfaces (108, 109;

208, 209) overlap each other partly.

5. An illumination system as claimed in claim 4, characterized in that the sub-surfaces (108, 109;

208, 209) extend over a substantial part of the front wall (102;

202) or the rear wall (103;

203) of the light-emitting panel (101;

201),

the coupling-out members (118, 119;

218, 219) being provided such that the amount of light coupled out changes as a function of the distance to the light-transmitting edge surface (104, 105;

204, 205).

6. An illumination system as claimed in claim 1 or 2, characterized in that the first and the second light source (6, 6′

, 6″

, . . . ;

7, 7′

, 7″

, . . . ) comprise at least a light-emitting diode having a luminous flux of at least 5 lm.

7. An illumination system as claimed in claim 6, characterized in that the light-emitting diode is mounted on a printed circuit board.

8. An illumination system as claimed in claim 1 or 2, characterized in that the light source comprises at least two light-emitting diodes with different light emission wavelengths.

9. An illumination system as claimed in claim 1 or 2, characterized in that the illumination system comprises control electronics for changing the luminous flux of the light source (6, 6′

, 6″

, . . . ;

7, 7′

, 7″

, . . . ).

10. A display device comprising an illumination system as claimed in claim 1 or 2.