Lighting arrangement with light guide
A lighting arrangement and a method of coupling light into a light guide are described. A light source is embedded within a light guide. The light guide includes first and second outer surfaces arranged on opposite sides. A forward direction extends from the light source parallel to the first outer surface. A collimator is embedded within the light guide. The collimator comprises a first reflector surface facing towards the second outer surface and a second reflector surface facing towards the first outer surface. The light source is arranged to emit light between the first and second reflector surfaces. The first reflector surface is arranged at least substantially parallel to the forward direction. At least a portion of the second reflector surface is arranged under an angle to the forward direction.
1. A lighting apparatus, comprising:
a light guide formed as a transparent solid body, the transparent solid body extending between a first outer surface and a second outer surface that opposes the first outer surface;
a light source embedded in the light guide and configured to emit light into the light guide, the light guide and the light source defining a forward direction that extends from the light source parallel to the first outer surface;
a first reflector surface embedded in the light guide and facing towards the second outer surface, the first reflector surface being substantially parallel to the forward direction; and
a second reflector surface embedded in the light guide and facing towards the first outer surface,
the light source being arranged to emit the light between the first reflector surface and the second reflector surface,
the second reflector surface being disposed on a second reflector member,
at least a portion of the second reflector surface being substantially planar and angled with respect to the forward direction and terminating at an end of the second reflector member.
2. The lighting apparatus of claim 1 , wherein:
the first reflector surface extends into the forward direction for a first reflector length measured from the light source;
the second reflector surface extends into the forward direction for a second reflector length measured from the light source; and
the second reflector length is greater than the first reflector length.
3. The lighting apparatus of claim 2 , wherein the second reflector length is at least 20% greater than the first reflector length.
4. The lighting apparatus of claim 1 , wherein
the portion of the second reflector surface and the forward direction are angled by an angle; and
the angle, the first reflector length, and the second reflector length are selected such that light emitted from the light source is directed along the light guide into directions such that an angle of incidence at the first outer surface or the second outer surface is above a critical angle and is reflected via total internal reflection at the first outer surface or the second outer surface.
5. The lighting apparatus of claim 1 , wherein the second reflector surface is angled between 2.5 degrees and 25 degrees, with respect to the forward direction.
6. The lighting apparatus of claim 1 , wherein the second reflector surface is angled between 7 degrees and 20 degrees, with respect to the forward direction.
7. The lighting apparatus of claim 1 , wherein the first reflector surface is disposed on a first reflector member.
8. The lighting apparatus of claim 1 , wherein the second reflector surface includes at least a first portion that is substantially parallel to the forward direction and a second portion that is angled with respect to the forward direction.
9. The lighting apparatus of claim 1 , wherein the light guide is generally flat and the light source is arranged at an edge of the light guide.
10. The lighting apparatus of claim 1 , wherein the second reflector surface includes a first portion located proximate the light source, the first portion being substantially planar and substantially parallel to the first reflector and extending to the end of the second reflector.
11. The lighting apparatus of claim 10 , wherein the second reflector surface further includes a second portion that adjoins the first portion such that the first portion is located between the second portion and the light source, the second portion being substantially planar and angled with respect to the first reflector and extending to the end of the second reflector.