Sunlight-based large area light source and large area luminaire

Patent metadata

Field	Value
Publication number	US-10830405-B2
Application number	US-201716487678-A
Country	US
Kind code	B2
Filing date	Feb 28, 2017
Priority date	Feb 28, 2017
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

A light source (25) for emitting collimated light (29) in particular for a large area luminaire (21) comprises a light guide unit (43) for guiding light by total internal reflection. The light guide unit comprises a plurality of localized light source regions (57) at a main front face (55A) for having light pass there through. The light source (25) further comprises a plurality of light emitting units (41) for emitting light into the light guide strips (91) through respective portions of the at least one coupling face (47) of the light guide unit (43), and a collimation unit (45) extending along the main front face (55A) and comprising a plurality of collimating elements. At least one light emitting unit (41) is configured as a light input coupling assembly (250) to receive collected natural light from a fiber (249) and to provide the received natural light to the light guide unit (43). The light source (25) can be implemented in a sunlight-based illumination system (241) collecting and providing natural light to the light source (25).

First claim

The invention claimed is:

1. A light source for emitting collimated light, the light source comprising:
a light guide unit having a main front face, a main back face, and at least one lateral coupling face connecting the main front face and the main back face in a thickness direction (d T ), wherein
the light guide unit is configured to guide light received at the at least one lateral coupling face by total internal reflection between the main front face and the main back face, and
the main front face comprises a plurality of localized light source regions that are areas with a limited extent in two-dimensions for having light pass there through, wherein the light source regions are surrounded by a non-source region,

a plurality of light emitting units configured to emit light into the light guide unit through the at least one coupling face, wherein at least one light emitting unit of the plurality of light emitting units is configured as a light input coupling assembly to receive collected natural light from a fiber and to provide the received natural light to the light guide unit; and
a collimation unit extending along the main front face and comprising a plurality of collimating elements, wherein each collimating element comprises an input side and an output side, is optically associated to one of the plurality of light source regions, is configured to receive light emerging from the associated light source region at its input side, and to emit collimated light from a respective collimated light emitting region formed at its output side.

2. The light source of claim 1 , wherein the light source regions are provided in a substantially regular pattern over the non-source region in at least a section of the main front face, and/or
wherein the regular pattern has a regular grid structure that is based on one or more types of grid units, each type of grid unit having an essentially identical dimension and/or a shape of a grid unit comprising points at equal distances or being a triangular grid unit or a square grid unit.

3. The light source of claim 1 , wherein at least one of
at least one of the plurality of light emitting units comprises a light emitting device with a light emission over an angular range that results in an angular range within the light guide unit of below 40°,
the angular range is characterized by an input light central direction and the input light central direction is inclined with respect to the normal to the main front face or main back face of light guide unit, and
at least one of the plurality of light emitting units comprises a white light emission spectrum and/or a variation of emission spectra.

4. The light source of claim 1 , wherein the ratio of the area of the plurality of light source regions with respect to the area of the main front face and/or the area of the non-source region is less or equal to 16%.

5. The light source of claim 1 , wherein the light guide unit comprises two opposite lateral light coupling faces each being associated with a subgroup of light emitting units of the plurality of light emitting units to thereby couple counter-propagating light into the light guide unit.

6. The light source of claim 1 , wherein a light emitting face is formed by the collimated light emitting regions, and the light emitting face comprises non-emitting regions between collimated light emitting regions and the area ratio between the non-emitting regions and the collimated light emitting regions is essentially constant over the light emitting face of the light source.

7. The light source of claim 1 , wherein at least one of
the distance between neighboring light source regions defined as pitch distance in a light propagation direction is in the range from 0.5 mm to 50 mm,
the light source or the light guide unit is configured such that the flux of light emitted from the light source regions is at least 10 times as much as any leakage flux of light through the non-source regions, and
the light source regions are distributed within and substantially surrounded by the non-source region.

8. The light source of claim 1 , wherein the extension of the light guide unit in directions defined by the shape of the main front face is much larger than the thickness of the light guide unit in the thickness direction (d T ), and at least one of
the light guide unit is panel shaped having a thickness in the range from 1 mm to 5 mm and a lateral extension in the range from 0.05 m to 3 m, and
the main front face and the main back face are opposite and parallel to each other.

9. The light source of claim 1 , wherein the light guide unit comprises a plurality of optically separated light guide strips, wherein at least one of
each light guide strip comprises at least one lateral coupling face section optically coupled to at least one of the plurality of light emitting units, and a subgroup of the plurality of light source regions arranged linearly along the light guide strip at equal distances,
the light guide strip has a rectangular cross-section with a thickness in the range from 0.1 mm to 5 mm, a lateral width in the range from 0.1 mm to 5 mm, and a length in the range from 0.1 m to 2 m, and
the plurality of light guide strips is mounted to a substrate at the respective sides of the light guide strips that are associated with the main back face of the light guide unit.

10. The light source of claim 1 , wherein
the light source regions have a lateral extension in the range up to 2 mm, and/or
the collimated light emitting regions have a lateral extension in the range from 0.5 mm to 50 mm.

11. The light source of claim 1 , further comprising at least one of
a cross-talk reducing baffle structure extending between and/or along collimating elements, thereby reducing the amount of light from a light source region entering a collimating element associated with a neighboring collimating element,
a front leakage blocking structure extending between collimating elements along the main front face, and
a back leakage blocking structure extending along the main back face and configured as a heat sink.

12. The light source of claim 1 , further comprising a plurality of reflective structures respectively associated with a light source region and wherein at least one of
a reflective structure of the plurality of reflective structures is positioned and configured to reflect light to pass through the light source region,
a reflective structure of the plurality of reflective structures is positioned and configured to reflect light onto a respective down conversion element, and
a reflective structure of the plurality of reflective structures is configured as focusing reflector.

13. The light source of claim 1 , further comprising a plurality of reflective structures respectively associated with a light source region and wherein at least one of
a reflective structure of the plurality of reflective structures is positioned and configured to reflect light falling onto it from opposite directions to pass through the light source region in a similar extraction direction,
a reflective structure of the plurality of reflective structures is configured as a reflective prism formed on the main back side, and
a reflective structure of the plurality of reflective structures has a triangular cross section when looked at from the side and a round cross section when looked at from the respective collimating element, and having a planar reflecting side that is shaped as a half-ellipse or as a half-circle.

14. The light source of claim 1 , wherein at least one of the plurality of collimating elements is configured to provide at le

Assignees

• Coelux Srl

Inventors

• Di Trapani Paolo
• Magatti Davide
• Lotti Antonio
• Krames Michael Ragan
• Molteni Matteo

Classifications

• F21S11/007 Primary

  characterised by the means for transmitting light into the interior of a building · CPC title

• F21V14/003

  by interposition of elements with electrically controlled variable light transmissivity, e.g. liquid crystal elements or electrochromic devices · CPC title

• F21S11/002

  characterised by the means for collecting or concentrating the sunlight, e.g. parabolic reflectors or Fresnel lenses · CPC title

• G02B6/0073

  Light emitting diode [LED] · CPC title

• G02B6/0068

  Arrangements of plural sources, e.g. multi-colour light sources · CPC title