Abstract:
The present invention relates to a light pipe configuration having a light transmitting portion with an inlet and outlet. An arm portion connected to the light transmitting portion that has a tab portion that functions to lock the light pipe in place during operation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/819,989, filed Jul. 11, 2006. 
     
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a light pipe configuration. 
       BACKGROUND OF THE INVENTION 
       [0003]    The use of light pipes in connection with a light emitting diode (LED) light source for providing various visual displays are becoming more common. The arrangement and design of the various light pipes present several obstacles. For example, the materials used, the shape of the light pipe, and ways of holding the light pipe in relation to the light source are all factors that can influence the performance of the design of a light pipe system. Furthermore, the design considerations must also account for variables related to the kinds of materials being used; for example, thermal expansion can occur with the light pipe materials which make it necessary to consider this effect when designing a light pipe for an LED. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention relates to a light pipe configuration having a light transmitting portion with an inlet and outlet. An arm portion connected to the light transmitting portion that has a tab portion that functions to position the light pipe during operation. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0006]      FIG. 1  depicts a plan side view of a light pipe and carrier module; and 
           [0007]      FIG. 2  is a plan side view of a self compensating light pipe and carrier module. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0008]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0009]    Referring now to  FIG. 1 , a light pipe  10  is generally shown. The light pipe  10  has a light transmitting portion  12  having an inlet  14  and outlet  16 . An alignment portion  18  is connected to the light transmitting portion  12 . The alignment portion  18  has an arm  20  that extends away from the light transmitting portion  12  and has a tab  22  that extends downward from the arm portion  20 . The alignment portion  18  is configured to mate with a carrier module  24 . The carrier module  24  has a ledge  26  formed on its surface for receiving the alignment portion  18  of the light pipe  10 . The carrier module  24  has a retainer portion  28  or tang that extends over the tab  22  and applies downward force to hold the alignment portion  18  to the ledge  26 . 
         [0010]    The inlet  14  of the light transmitting portion  12  is spaced apart from a light source  30 . The light source  30  can be a light emitting diode (LED) light source that receives light which is then transmitted through the outlet  16 . When the light pipe  10  changes in temperature thermal expansion can occur and eliminate the gap between the inlet  14  and light source  30 , thus the spacing of the light pipe and light source  30  must be within certain tolerances to optimize light transmission and account for thermal expansion. The gap is preferably 0.1 mm; however, a greater or lesser gap can be incorporated depending upon the needs of a particular application. Such factors as material and spatial requirements will affect the amount of gap between the inlet  14  and light source  30 . 
         [0011]    In order to maintain the same amount of gap before thermal expansion and after thermal expansion the light pipe  10  and carrier module  24  can be made of the same material, or a material having a substantially identical thermal expansion coefficient. Because the coefficient of thermal expansion is the same, when the light pipe  10  and carrier module  24  expand they will expand at the same rate in opposite directions canceling the effect of thermal expansion, and maintain the gap between the inlet  14  and light source  30 . 
         [0012]      FIG. 2  depicts a self compensating light pipe  32 . The self compensating light pipe  32  can be used for applications where thermal expansion cannot be compensated for by making the light pipe and carrier module out of the same material or a material with substantially identical thermal expansion characteristics. 
         [0013]    The self compensating light pipe  32  has a light transmitting portion  34  having an inlet  36  and outlet  38 . A light source  40 , which can be a light emitting diode (LED) or some other suitable light source spaced apart from the inlet  36  to create a gap. The gap is preferably 0.1 mm; however, it is possible for greater or smaller gaps to be used depending on the design of a particular application. The light pipe  32  has an attachment portion  41  that has a leg  42  extending generally parallel to the light transmitting portion  34 . The leg  42  extends parallel for a portion of the length of the light transmitting portion  34 . A carrier module  44  has a ledge  46  that receives the leg  42 . The carrier module  44  also has a lock  47  for applying pressure downward on the attachment portion  41  to hold the leg  42  within the ledge  46 . The leg  42  and light transmitting portion  34  are made of the same material. When the light transmitting portion expands because of thermal expansion the leg  42  will also expand. Thus thermal expansion is compensated for by the leg  42  and light transmitting portion  34  expanding at the same rate. Therefore, it is not necessary for the carrier module  44  to be made of the same material or have the same thermal expansion properties. 
         [0014]    In both embodiments of the invention several light pipes  10 ,  32  can be fastened to the carrier module  24 ,  44 . The present invention provides a way of compensating for thermal expansion as well as securing the light pipes at a set distance from the light source. 
         [0015]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.