Luminaire module having a light guide with a redirecting end-face

Abstract

A solid-state luminaire module includes one or more light-emitting elements (LEEs) arranged to provide light; and a light guide including a receiving end arranged to receive the light provided by the LEEs and an opposing end, a pair of opposing side surfaces extending along a length of the light guide to guide the received light in a forward direction to the opposing end, and a redirecting end-face located at the opposing end and configured to reflect the guided light—that reaches the opposing end—back into the light guide as return light, such that substantially all the return light impinges on the pair of opposing side surfaces at incident angles larger than a critical incidence angle and transmits through the pair of opposing side surfaces into the ambient as output light of the luminaire module, the output light to propagate in backward directions.

1 . A luminaire module comprising:
 one or more light-emitting elements (LEEs) arranged to provide light; and   a light guide comprising
 a receiving end and an opposing end, the receiving end arranged to receive the light provided by the LEEs, 
 a pair of opposing side surfaces extending along a length of the light guide between the receiving end and the opposing end, the light guide configured to guide the received light in a forward direction, along the length of the light guide to the opposing end of the light guide, and 
 a redirecting end-face located at the opposing end and configured to reflect the guided light—that reaches the opposing end—back into the light guide as return light, such that substantially all the return light impinges on the pair of opposing side surfaces at incident angles larger than a critical incidence angle and transmits through the pair of opposing side surfaces into the ambient as output light of the luminaire module, the output light to propagate in backward directions. 
   
     
     
         2 . The luminaire module of  claim 1 , wherein substantially all the return light is transmitted through the pair of opposing side surfaces during multiple bounces at the pair of opposing side surfaces. 
     
     
         3 . The luminaire module of  claim 1 , wherein the light guide is configured to guide the received light in a forward direction through total internal reflection (TIR) off the opposing side surfaces. 
     
     
         4 . The luminaire module of  claim 1 , wherein
 the light provided by the LEEs is in a first angular range, and   a numerical aperture of the light guide is such that the light received from the LEEs in the first angular range can be guided by the light guide through TIR off the pair of opposing side surfaces.   
     
     
         5 . The luminaire module of  claim 1  further comprising one or more optical couplers, wherein
 the light provided by the LEEs is in a first angular range, 
 the optical couplers are arranged to receive the light provided by the LEEs and redirect it to the receiving end of the light guide in a second angular range, and 
 a numerical aperture of the light guide is such that the light received from the optical couplers in the second angular range can be guided by the light guide through TIR off the pair of opposing side surfaces. 
 
     
     
         6 . The luminaire module of  claim 1 , wherein
 the guided light that reaches the opposing end of the light guide is in a third angular range, and   a configuration of the redirecting end-face is such that return light generated by the redirecting end-face is in a first return angular range, and   the first return angular range has substantially no overlap with the third angular range.   
     
     
         7 . The luminaire module of  claim 6 , wherein the return light in the first return angular range transmits through each of the pair of opposing side surfaces as output light in a first output angular range with a propagation direction having a component anti-parallel to the forward direction. 
     
     
         8 . The luminaire module of  claim 6 , wherein the redirecting end-face comprises one or more sawtooth-shaped sections. 
     
     
         9 . The luminaire module of  claim 6 , wherein
 the configuration of the redirecting end-face is such that return light generated by the redirecting end-face is also in a second return angular range, and   the second return angular range has substantially no overlap with the third angular range.   
     
     
         10 . The luminaire module of  claim 9 , wherein the return light in the second return angular range transmits through each of the pair of opposing side surfaces as output light in a second output angular range with a propagation direction having a component anti-parallel to the forward direction. 
     
     
         11 . The luminaire module of  claim 8 , wherein the sawtooth-shaped sections are symmetrical. 
     
     
         12 . The luminaire module of  claim 1 , wherein the redirecting end-face is coated with reflecting material. 
     
     
         13 . The luminaire module of  claim 12 , wherein the reflecting material has voids that allow light to transmit through the end face. 
     
     
         14 . The luminaire module of  claim 1 , wherein the pair of opposing side surfaces are planar and parallel.