Illumination system, light mixing chamber and display device

• US 6,536,914 B2
• Filed: 05/01/2001
• Issued: 03/25/2003
• Est. Priority Date: 05/04/2000
• Status: Expired due to Term

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Hoelen, Christoph Gerard August, Harbers, Gerard
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): CRANSON JR, JAMES W
• Application Number:
  US09/846,421
• Publication Number:
  US 20010046131A1
• Time in Patent Office: 693 Days
• Field of Search: 362/231, 362/31, 362/230, 362/246, 362/545, 362/558, 362/800, 362/27, 349/68, 349/69
• US Class Current: 362/231
• CPC Class Codes: F21V 23/0442 activated by means of a sensor, e.g. motion or photodetectors
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0033 Means for improving the coupling-out of light from the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An illumination system for illuminating a display device (3) comprises a light-emitting panel (1) having a light-emission window (2) and at least one edge surface (4) for coupling light into the light-emitting panel (1). The illumination system further comprises a light mixing chamber (5) provided with a light source (6). The light mixing chamber (5) is associated with the edge surface (4). According to the invention, the light source (6) comprises a plurality of clusters of light-emitting diodes (LEDs) having different light-emission wavelengths, the clusters being arranged at a pitch P with respect to each other. The ratio of the height H of the light mixing chamber (5) to the pitch P of the clusters meets the relation 0.1≦H/P≦10, preferably 0.2≦H/P≦2. Preferably, each cluster comprises one blue, one green and one red LED, or one blue, two green and one red LEDs. Preferably, each LED has a luminous flux of at least 5 lumen. The illumination system according to the invention has a very uniform light distribution, so that the display device is uniformly illuminated.

Claims

1. An illumination system for illuminating a display device (3), comprising

a light-emitting panel (1) having a light-emission window (2) and at least one light-coupling edge area (4) for coupling light into the light-emitting panel (1), and

a light mixing chamber (5) with a longitudinal direction (15) which extends parallel to the light-coupling edge area (4), which light mixing chamber is provided with a light source (6;

6′

), the light mixing chamber (5) being associated with the light-coupling edge area (4), characterized in that

the light source (6, 6′

) comprises a plurality of clusters of light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) having different light-emission wavelengths, said clusters being arranged at a pitch (P) with respect to each other, and

the ratio between a height (H) of the light mixing chamber (5) and the pitch (P) of the clusters of the light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) meets the relation;

2. An illumination system as claimed in claim 1, characterized in that the ratio between the height (H) of the light mixing chamber (5) and the pitch (P) of the clusters of the light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) meets the relation;

3. An illumination system as claimed in claim 1 or 2, characterized in that the ratio between the height (H) of the light mixing chamber (5) and the pitch (P) of the clusters of the light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R 26G′

, . . . ) meets the relation;

$\frac{1}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\beta <br><br>}}_{\max }}\le <br><br>\frac{H}{P}\le <br><br>\frac{2}{\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\beta <br><br>}}_{\max }},$

where β

is the light emission angle of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) in a plane parallel to the longitudinal direction (15) of the light mixing chamber (5) and measured with respect to a longitudinal axis (21) of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G 26R, 26G′

, . . . ),and

where β

_max is the maximum value of β

at which the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

262, 26G, 26R, 26G′

, . . . ) emits, in operation, 90% of its energy for values of β

at which |β

|≦

β

_max.

4. An illumination system as claimed in claim 3, characterized in that the value of the angle β

_max lies in the range from 60≦

β

_max≦

80°

.

5. An illumination system as claimed in claim 1 or 2, characterized in that the ratio between the height (H) and a width (D) of the light mixing chamber (5) meets the relation:

$\frac{1}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_{\max }}\le <br><br>\frac{H}{D}\le <br><br>\frac{3}{\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_{\max }},$

where D is the width of the light mixing chamber (5) measured at right angles to the longitudinal direction (15) of the light mixing chamber (5),

where α

is the light emission angle of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) in a plane transverse to the longitudinal direction (15) of the light mixing chamber (5) and measured with respect to a longitudinal axis (21;

21′

) of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26R, 26G′

, . . . ), and

where α

_max is the maximum value of α

at which the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) emits, in operation, 90% of its energy for values of α

at which |α

|≦

α

_max.

6. An illumination system as claimed in claim 5, characterized in that

the value of the angle α

_max lies in the range from 20≦

α

_max≦

50°

if the light-emitting diodes (6) are provided in a wall of the light mixing chamber (5) which is remote from the light-coupling edge area (4) and which extends parallel to said light-coupling edge area (4), or

the value of the angle α

_max lies in the range from 60°

≦

α

_max≦

80°

if the light-emitting diodes (6′

) are provided in a wall of the light mixing chamber (5) transversely to the light-coupling edge area (4).

7. An illumination system as claimed in claim 1 or 2, characterized in that the width (D) of the light mixing chamber (5), measured transversely to the longitudinal direction (15) of the light mixing chamber (5), lies in the range from 3≦

D≦

15 mm.

8. An illumination system as claimed in claim 7, characterized in that the width (D) lies in the range from 3≦

D≦

5 mm.

9. An illumination system as claimed in claim 1 or 2, characterized in that each of the clusters of light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) having different light emission wavelengths is selected from the group formed by

one blue (6B), one green (6G) and one red (6R) light-emitting diode,

one blue (16B;

26B), two green (16G, 16G′

;

26G, 26G′

) and one red (16R;

26R) light-emitting diodes,

one blue, one green, one amber and one red light-emitting diode, and

one blue, two green, one amber and one red light-emitting diodes.

10. An illumination system as claimed in claim 1 or 2, characterized in that a diffuser (7) is present between the light mixing chamber (5) and the light-coupling edge area (4).

11. An illumination system as claimed in claim 1 or 2, characterized in that the panel comprises two light-coupling edge areas (4) which are situated at opposite sides of the light-emitting panel (1).

12. An illumination system as claimed in claim 1 or 2, characterized in that each of the light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) comprises a luminous flux of at least 5 lm.

13. 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-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26R, 26G′

, . . . ).

14. An illumination system for illuminating a display device (3), comprising

a light-emitting panel (1) having a light-emission window (2) and at least one light-coupling edge area (4) for coupling light into the light-emitting panel (1);

a light mixing chamber (5) with a longitudinal direction (15) which extends parallel to the light-coupling edge area (4), which light mixing chamber is provided with a light source (6;

6′

), the light mixing chamber (5) being associated with the light-coupling edge area (4) and a height H of the light mixing chamber (5) being measured at right angles to the light-coupling edge area (4),

wherein said light source (6, 6′

) includes a plurality of clusters of 26B, 26G, 26R, 26G′

, . . . ) having different light-emission wavelengths, said clusters being arranged at a pitch (P) with respect to each other, and

wherein a ratio between the height (H) of the light mixing chamber (5) and the pitch (P) of the clusters of the light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) meets the relation;

$\frac{1}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\beta <br><br>}}_{\max }}\le <br><br>\frac{H}{P}\le <br><br>\frac{2}{\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\beta <br><br>}}_{\max }},$

where β

is the light emission angle of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) in a plane parallel to the longitudinal direction (15) of the light mixing chamber (5) and measured with respect to a longitudinal axis (21) of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ),and

where β

_max is the maximum value of β

at which the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

262, 26G, 26R, 26G′

, . . . ) emits, in operation 90% of its energy for values of β

at which |β

|≦

β

_max.

15. An illumination system for illuminating a display device (3), comprising

a light-emitting panel (1) having a light-emission window (2) and at least one light-coupling edge area (4) for coupling light into the light-emitting panel (1);

a light mixing chamber (5) with a longitudinal direction (15) which extends parallel to the light-coupling edge area (4), which light mixing chamber is provided with a light source (6;

6′

), the light mixing chamber (5) being associated with the light-coupling edge area (4) and a height H of the light mixing chamber (5) being measured at right angles to the light-coupling edge area (4),

wherein said light source (6, 6′

) includes a plurality of clusters of light-emitting diodes (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) having different light-emission wavelengths, said clusters being arranged at a pitch (P) with respect to each other, and

wherein a ratio between the height (H) and a width (D) of the light mixing chamber (5) meets the relation;

$\frac{1}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_{\max }}\le <br><br>\frac{H}{D}\le <br><br>\frac{3}{\tan <br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_{\max }},$

where D is the width of the light mixing chamber (5) measured at right angles to the longitudinal direction (15) of the light mixing chamber (5),

where α

is the light emission angle of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ) in a plane transverse to the longitudinal direction (15) of the light mixing chamber (5) and measured with respect to a longitudinal axis (21;

21′

) of the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . . ), and

where α

_max is the maximum value of α

at which the light-emitting diode (6B, 6G, 6R, . . . ;

16B, 16G, 16R, 16G′

, . . . ;

26B, 26G, 26R, 26G′

, . . .) emits, in operation 90% of its energy for values of α

at which |α

|≦

α

_max.