Light unit with an extended light emission surface

Patent metadata

Field	Value
Publication number	US-10371879-B2
Application number	US-201514980456-A
Country	US
Kind code	B2
Filing date	Dec 28, 2015
Priority date	Jan 2, 2015
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

A light unit with an extended light emission surface includes a light source, and a flat light distribution body having a first principal surface and a second principal surface disposed on opposite sides of the flat light distribution body, wherein the light source is positioned outside of the flat light distribution body, with light emitted by the light source being coupled into the flat light distribution body and being propagated within the flat light distribution body via total internal reflection at the first and second principal surfaces.

First claim

The invention claimed is:

1. A light unit with an extended light emission surface, comprising
a light source, and
a flat light distribution body having a first principal surface and a second principal surface disposed on opposite sides of the flat light distribution body,
wherein the light source is positioned outside of the flat light distribution body, with light emitted by the light source being coupled into the flat light distribution body and being propagated within the flat light distribution body via total internal reflection at the first and second principal surfaces,
wherein the flat light distribution body has a substantially cuboid shape and wherein the light source is arranged in a corner region of the flat light distribution body, with light from the light source being coupled into the flat light distribution body via a light entry surface,
wherein the light entry surface has a concave shape, when seen from the light source, in a cross-sectional plane parallel to the first principal surface and wherein the light entry surface has a convex shape, when seen from the light source, in a cross-sectional plane orthogonal to the first principal surface,
wherein the first principal surface has a plurality of surface irregularities, wherein light arriving at a surface irregularity at an angle of incidence is reflected at an angle of reflection that is different from the angle of incidence with respect to the first principal surface, with the angle of reflection allowing for the light to be coupled out of the flat light distribution body,
wherein a total irregularity ratio of the first principal surface is defined as a combined area of the plurality of surface irregularities on the first principal surface divided by a total area of the first principal surface and wherein a regional irregularity ratio is defined as a combined area of a subset of the plurality of surface irregularities in a sub-region of the first principal surface divided by a total area of said sub-region of the first principal surface, wherein the first principal surface has at least one square sub-region whose area is 10% of the total area of the first principal surface and whose regional irregularity ratio is at least 50% higher than the total irregularity ratio, and
wherein the first principal surface is the extended light emission surface and wherein the light unit comprises an extended reflector arranged outside of the flat light distribution body alongside the second principal surface, with the light being coupled out of the flat light distribution body at the first principal surface after being reflected at the plurality of surface irregularities on the first principal surface, travelling through the flat light distribution body, leaving the flat light distribution body at the second principal surface, being reflected at the extended reflector, entering the flat light distribution body via the second principal surface, and travelling through the flat light distribution body.

2. The light unit according to claim 1 , wherein the extended reflector is a diffuse reflector, in particular a white diffuse reflector.

3. The light unit according to claim 1 , wherein the second principal surface has a plurality of second surface irregularities, wherein light arriving at a second surface irregularity at an angle of incidence is reflected at an angle of reflection that is different from the angle of incidence with respect to the second principal surface, with the angle of reflection allowing for the light to be coupled out of the flat light distribution body.

4. The light unit according to claim 3 ,
wherein light is being coupled out of the flat light distribution body at the first principal surface after being reflected at the plurality of second surface irregularities on the second principal surface.

5. The light unit according to claim 1 , wherein the light source is an LED light source.

6. The light unit according to claim 1 , wherein a distribution of the plurality of surface irregularities is such that an output light intensity distribution across the extended light emission surface has a ratio between its maximum light intensity and its minimum light intensity of at most 3.

7. The light unit according to claim 1 , wherein the plurality of surface irregularities comprises holes in the first principal surface and/or wherein the plurality of surface irregularities comprises dots attached to the outside of the first principal surface.

8. The light unit according to claim 1 , wherein the light unit is an interior aircraft light unit.

9. A method of designing a light unit with an extended light emission surface, comprising the steps of:
(a) defining a geometry of a flat light distribution body, having a first principal surface, a second principal surface, and a light entry surface, wherein the flat light distribution body has a substantially cuboid shape,
(b) defining a position and a light intensity distribution of a light source, facing the light entry surface, wherein the light source is arranged in a corner region of the flat light distribution body, with light from the light source being coupled into the flat light distribution body via a light entry surface, wherein the light entry surface has a concave shape, when seen from the light source, in a cross-sectional plane parallel to the first principal surface and wherein the light entry surface has a convex shape, when seen from the light source, in a cross-sectional plane orthogonal to the first principal surface,
(c) defining a starting pattern of a plurality of surface irregularities on the first principal surface,
(c′) arranging an extended reflector outside of the flat light distribution body alongside the second principal surface, with light being coupled out of the flat light distribution body at the first principal surface after being reflected at the plurality of surface irregularities on the first principal surface, travelling through the flat light distribution body, leaving the flat light distribution body at the second principal surface, being reflected at the extended reflector, entering the flat light distribution body via the second principal surface, and travelling through the flat light distribution body, the first principal surface being the extended light emission surface,
(d) simulating an operation of the light unit and analysing an output light intensity distribution across the extended light emission surface,
(e) determining a maximum light intensity and a minimum light intensity of the output light intensity distribution and determining a ratio between the maximum light intensity and the minimum light intensity,
(f) if the ratio between the maximum light intensity and the minimum light intensity is above a predetermined threshold, increasing the number and/or the size of the surface irregularities in regions with low output light intensity values.

10. The method according to claim 9 , wherein steps (d) to (f) are performed iteratively, until the ratio between the maximum light intensity and the minimum light intensity is below the predetermined threshold.

11. The light unit according to claim 1 , wherein the extended reflector is a white diffuse reflector.

12. The light unit according to claim 1 , wherein the light source is an LED light source consisting of exactly one LED.

13. The light unit according to claim 1 , wherein the light unit is an interior aircraft exit light or an aircraft wash room signal light unit.

Assignees

• Goodrich Lighting Systems Gmbh

Inventors

• Srinivasamurthy Ramesh
• Schoen Christian
• Hessling-Von Heimendahl Andre
• Jha Anil Kumar

Classifications

• G02B6/0061

  to provide homogeneous light output intensity · CPC title

• G02B6/0058

  varying in density, size, shape or depth along the light guide · CPC title

• G02B6/0043 Primary

  provided on the surface of the light guide · CPC title

• G02B6/0021

  for housing at least a part of the light source, e.g. by forming holes or recesses · CPC title

• G02B6/0055 Primary

  Reflecting element, sheet or layer · CPC title