Illumination System

• US 20080062686A1
• Filed: 08/18/2005
• Published: 03/13/2008
• Est. Priority Date: 09/24/2004
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Ansems, Johannes, Hoelen, Christoph
• Application Number:
  US11/575,517
• Publication Number:
  US 20080062686A1
• Time in Patent Office: Days
• US Class Current: 362/240
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/002 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

An illumination system has a plurality of light emitters (R, G, B), at least one light-collimating section (12, 12′, 12″) for collimating the light emitted by the light emitters arranged along a longitudinal axis (25) of the illumination system. The at least one lightcollimating sections merge into a light-mixing section (3) at a side facing away from the light emitters. The light-mixing section has a plurality of side-faces parallel to the longitudinal axis. A surface of the light-mixing section facing away from the light emitters is provided with a light-shaping diffuser (17). Preferably, the light-shaping diffuser is a holographic diffuser. Preferably, the illumination system comprises a plurality of light-collimating sections each of the light-collimating sections being associated with at least one light emitter. The illumination system provides improved spatial and spatio-angular mixing of the light emitted by the light emitters.

Claims

1. An illumination system comprising:

a plurality of light emitters (R, G, B),

at least one light-collimating section (12, 12′

, 12″

) for collimating the light emitted by the light emitters (R, G, B),

the at least one light-collimating section (12, 12′

, 12″

) being arranged along a longitudinal axis (25) of the illumination system,

the at least one light-collimating section (12, 12′

, 12″

) merging into a light-mixing section (3) at a side facing away from the light emitters (R, G, B),

the light-mixing section (3) having a plurality of side-faces parallel to the longitudinal axis (25),

a surface of the light-mixing section (3) facing away from the light emitters (R, G, B) being provided with a light-shaping diffuser (17).

2. An illumination system as claimed in claim 1, wherein the illumination system comprises a plurality of light-collimating sections (12, 12′

, 12″

) arranged substantially parallel to each other along the longitudinal axis (25) of the illumination system, each of the light-collimating sections (12, 12′

, 12″

) being associated with at least one light emitter (R, G, B).

3. An illumination system as claimed in claim 2, wherein light propagation in the light-collimating sections (12, 12′

, 12″

) is based on total internal reflection or on reflection on reflective surfaces (22) of the light-collimating sections (12, 12′

, 12″

).

4. An illumination system as claimed in claim 1, wherein the at least one light-collimating section (12, 12′

, 12″

) comprises a non-gaseous dielectric or non-gaseous dielectric-filled light-collimating section (12, 12′

, 12″

) and wherein the ratio of a length l of the at least one light-collimating section (12, 12′

, 12″

) parallel to the longitudinal axis and a diameter d_c of the light-collimating section (12, 12′

, 12″

) is in the range;

$0.35\le <br><br>\frac{l_c}{d_c}\le <br><br>2.$

5. An illumination system as claimed in claim 1, wherein light propagation in the light-mixing section (3) is based on total internal reflection or on reflection on reflective surfaces (33, 33′

) of the light-mixing section (3).

6. An illumination system as claimed in claim 2, wherein the light-collimating sections (12, 12′

, 12″

) and the light-mixing section (3) form one integral part (1).

7. An illumination system as claimed in claim 6, wherein the light-collimating sections (12, 12′

, 12″

) and the light-mixing section (3) are made from a dielectric material with a refractive index larger than or equal to 1.3.

8. An illumination system as claimed in claim 1, wherein the light-mixing section (3) comprises a non-gaseous dielectric or non-gaseous dielectric-filled light-mixing section (3) and wherein the ratio of a length l_ms of the light-mixing section (3) parallel to the longitudinal axis (25) and a diameter d_ms of the light-mixing section (3) is in the range:

$3.5\le <br><br>\frac{l_{m<br><br>\text{\hspace{1em}<br><br>}<br><br>s}}{d_{m<br><br>\text{\hspace{1em}<br><br>}<br><br>s}}\le <br><br>10.$

9. An illumination system as claimed in claim 1, wherein the light-mixing section (3) comprises an air-filled light-mixing section (3) and wherein the ratio of a length l_ms of the light-mixing section (3) parallel to the longitudinal axis (25) and a diameter d_ms of the light-mixing section (3) is in the range:

$2\le <br><br>\frac{l_{m<br><br>\text{\hspace{1em}<br><br>}<br><br>s}}{d_{m<br><br>\text{\hspace{1em}<br><br>}<br><br>s}}\le <br><br>7.$

10. An illumination system as claimed in claim 1, wherein the light-mixing section (3) is provided with four or six side-faces.

11. An illumination system as claimed in claim 1, wherein the light-shaping diffuser (17) is a holographic diffuser.

12. An illumination system as claimed in claim 1, wherein the light-mixing section (3) at a side facing away from the light emitters (R, G, B) is provided with a further light-collimating section (15).

13. An illumination system as claimed in claim 12, wherein the further light-collimating section (15) is substantially shaped according to a compound parabolic concentrator.

14. An illumination system as claimed in claim 1, wherein the light emitters comprise at least a first light-emitting diode (R) of a first primary color, at least a second light-emitting diode (G) of a second primary color, and at least a third light-emitting diode (B) of a third primary color, the three primary colors being distinct from each other.

15. An illumination system as claimed in claim 14, wherein each of the light-emitting diodes (R, G, B) has a radiant power output of at least 25 mW when driven at nominal power and with the light-generating junction of the light emitting diodes (R, G, B) at room temperature.