Compact illumination system and display device
A compact backlighting system for illuminating a display device ( 12 ) comprises a light-emitting panel ( 1 ) having a front wall ( 2 ), an opposing rear wall ( 3 ) and edge areas ( 4 ). At least one of the edge areas ( 4 ) is capable of transmitting light. The backlighting system includes a light source ( 6 ) comprising at least one LED, and a light-mixing panel 5 for mixing the light originating from the light source ( 6 ). Light originating from the light source ( 6 ) is coupled into the light-mixing panel ( 5 ) via a light input surface ( 7 ), which light is mixed in the light-mixing panel ( 5 ) and coupled out via a light output surface ( 8 ). The light-mixing panel ( 5 ) and the light-emitting panel ( 1 ) are arranged so as to extend substantially parallel to each other. Between the light-mixing panel 5 and the light-emitting panel 1 , the backlighting system comprises a light transport chamber ( 9 ) for transporting the light from the light-mixing panel ( 5 ) to the light-emitting panel ( 1 ). Preferably, the light transport chamber ( 9 ) has elliptical, reflective inner wall ( 10 ).
1. An illumination system for illuminating a display device, which illumination system is provided with a light source ( 6 ) and a light-emitting panel ( 1 ), wherein
the light source ( 6 ) comprises at least one light-emitting diode,
the light-emitting panel ( 1 ) comprises a front wall ( 2 ), a rear wall ( 3 ) situated opposite said front wall, and at least one light-transmitting edge area ( 4 ),
and the light-transmitting edge area ( 4 ) is situated between the front wall ( 2 ) and the rear wall ( 3 ) of the light-emitting panel ( 1 ), characterized in that
the illumination system comprises a light-mixing panel ( 5 ) for mixing light originating from the light source ( 6 ),
the light-mixing panel ( 5 ) being provided with a light input edge area ( 7 ) for coupling light originating from the light source ( 6 ) into the light-mixing panel ( 5 ), and with a light output edge area ( 8 ) for coupling light out of the light-mixing panel ( 5 ),
in operation, light originating from the light source ( 6 ) being incident on the light input edge area ( 7 ) of the light-mixing panel ( 5 ) and spreading in the light-mixing panel ( 5 ),
a light-transport chamber ( 9 ) for transporting light from the light-mixing panel ( 5 ) to the light-emitting panel ( 1 ) being situated between the light-mixing panel ( 5 ) and the light-emitting panel ( 1 ), and
the light-mixing panel ( 5 ) and the light-emitting panel ( 1 ) being arranged so as to extend substantially parallel to each other.
2. An illumination system as claimed in claim 1 , characterized in that the light transport chamber ( 9 ) comprises an elliptically shaped, reflective inner wall ( 10 ).
3. An illumination system as claimed in claim 1 , characterized in that the light transport chamber ( 19 ) comprises two light-transmitting prisms ( 20 , 20 ′).
4. An illumination system as claimed in claim 1 , characterized in that the light-transport chamber ( 29 ) comprises a faceted, reflective inner wall ( 30 ).
5. An illumination system as claimed in claim 1 , characterized in that a light-collimating element for coupling light originating from the light source into the light-mixing panel ( 5 ) is situated between the light source ( 6 ) and the light-mixing panel ( 5 ).
6. An illumination system as claimed in claim 1 , characterized in that the light-mixing panel ( 5 ) narrows in a direction facing away from the light output edge area ( 8 ).
7. An illumination system as claimed in claim 1 , characterized in that the light source ( 6 ) comprises at least three light-emitting diodes ( 6 B, 6 G, 6 R) with a first, a second and a third light emission wavelength, which light emission wavelengths are different.
8. An illumination system as claimed in claim 7 , characterized in that the light source ( 6 ) associated with the light input edge area ( 7 ) of the light-mixing panel ( 5 ) comprises clusters of blue, green and red light-emitting diodes ( 6 B, 6 G, 6 R).
9. An illumination system as claimed in claim 1 , characterized in that the light-mixing panel ( 5 ) comprises a first and a second part ( 51 , 52 ), having a respective first and second light input edge area ( 71 , 72 ) and a first and second light output edge area ( 81 , 82 ) and in that a first and second light-transport chamber ( 91 , 92 ) for transporting light from the respective first and second light-mixing panel part ( 51 , 52 ) to the light-emitting panel ( 1 ) being situated between the respective first and second light-mixing panel part ( 51 ,_ 52 ) and the light-emitting panel ( 1 ).
10. An illumination system as claimed in claim 9 , characterized in that the light source ( 6 ) is common to the first and second light-mixing panel part.
11. An illumination system as claimed in claim 9 , characterized in that the light source ( 6 ) comprises a first and a second section ( 61 , 62 ) coupled to the respective first and second light input edge area ( 71 , 72 ).
12. A display device comprising an illumination system as claimed in claim 1 .
13. A display device as claimed in claim 12 , wherein the display device comprises a liquid crystal display ( 12 ).
14. An illumination system for illuminating a display device, which illumination system is provided with a light source ( 6 ) and a light-emitting panel ( 1 ), wherein
the light source ( 6 ) comprises at least one light-emitting diode,
the light-emitting panel ( 1 ) comprises a front wall ( 2 ), a rear wall ( 3 ) situated opposite said front wall, and at least one light-transmitting edge area ( 4 ),
and the light-transmitting edge area ( 4 ) is situated between the front wall ( 2 ) and the rear wall ( 3 ) of the light-emitting panel ( 1 ),
the illumination system comprises a light-mixing panel ( 5 ) for mixing light originating from the light source ( 6 ),
the light-mixing panel ( 5 ) being provided with a light input edge area ( 7 ) for coupling light originating from the light source ( 6 ) into the light-mixing panel ( 5 ), and with a light output edge area ( 8 ) for coupling light out of the light-mixing panel ( 5 ),
in operation, light originating from the light source ( 6 ) being incident on the light input edge area ( 7 ) of the light-mixing panel ( 5 ) and spreading in the light-mixing panel ( 5 ),
a light-transport chamber ( 9 ) for transporting light from the light-mixing panel ( 5 ) to the light-emitting panel ( 1 ) being situated between the light-mixing panel ( 5 ) and the light-emitting panel ( 1 ), and
the light-mixing panel ( 5 ) and the light-emitting panel ( 1 ) being arranged so as to extend substantially parallel to each other,
characterized in that the light transport chamber ( 9 ) comprises an elliptically shaped, reflective inner wall ( 10 ).
15. An illumination system as claimed in claim 14 , characterized in that
the first focus (f 1 ) of the ellipse is situated in or at least near the light output edge area ( 8 ) of the light-mixing panel ( 5 ), and
the second focus (f 2 ) of the ellipse is situated in or at least near the light-transmitting edge area ( 4 ) of the light-emitting panel ( 1 ).
16. An illumination system as claimed in claim 14 , characterized in that the ratio of half the length (a) of the short axis of the ellipse to half the length (b) of the long axis of the ellipse lies in the range from
0.4
≤
a
b
≤
1.
17. An illumination system as claimed in claim 16 , characterized in that the ratio of half the length (a) of the short axis of the ellipse to half the length (b) of the long axis of the ellipse lies in the range from
0.8
≤
a
b
≤
1.
18. An illumination system as claimed in claim 15 , characterized in that the inner wall ( 10 ) of the light transport chamber ( 9 ) is at least substantially circular in shape, the center of the circle being situated between the light output edge area ( 8 ) of the light-mixing panel ( 5 ) and the light transmitting edge area ( 4 ) of the light-emitting panel ( 1 ).