Patent Document

FIELD OF THE INVENTION 
     The present invention relates generally to lens assemblies for automotive light assemblies, and more particularly relates to lens assemblies structured for use with a LED light source. 
     BACKGROUND OF THE INVENTION 
     Light emitting diodes (LED&#39;s) are fast becoming the preferable light source for automotive lighting applications, as they consume less power but provide light output which is becoming acceptable for such applications. Near field lenses (NFL&#39;s) are used to collect as well as to collimate the light from a LED source. Additional optic power may be added to the NFL to create a certain desired beam pattern. Existing NFL&#39;s have very high light collection efficiency (typically 70-90%) regardless of their size, but the output beam size for a given source depends on the size of the lens. The larger the lens size (i.e. the larger the starting focal length of the lens), the smaller of the output beam size and the higher the peak intensity. However, manufacturing larger lenses poses complex molding issues and takes higher molding cycle time, thus requiring expensive molding tools and processes. 
     Accordingly, there exists a need to provide a lighting assembly having a lens that provides the output beam size and peak intensity for automotive applications, while reducing the time, cost and complexity of manufacture. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a light assembly having a lens assembly that overcomes the drawbacks noted above by splitting the function of a near field lens into two components. The first component is an inner lens, while the second component may be a reflector or a second lens. 
     One embodiment of the present invention provides a light assembly directing light along a longitudinal axis. The light assembly comprises a LED light source, a first lens member and a second member. The first lens member has a recess receiving the LED light source. The first lens member includes a radial portion and an axial portion. The second member has an interior space receiving the first lens member. The second member defines a reflecting surface. The reflecting surface of the second member receives light passing through the radial portion of the first lens member and directs the light downstream along the longitudinal axis. 
     According to more detailed aspects, the axial portion of the first lens member includes beam focusing optics. Preferably, the axial portion defines an inner axial surface, wherein the inner axial surface is structured as a Fresnel lens (which reduces thickness), a conical surface, or a free-form surface. The axial portion defines an outer axial surface as well, and one of the inner and outer axial surfaces may be curved to focus the light. The axial portion of the first lens member may also include beam spreading optics such as a plurality of pillows on the outer axial surface. The radial portion defines an inner radial surface and an outer radial surface, and the inner radial surface is preferably flat. The inner radial surface is positioned to reflect light passing therethrough. The outer radial surface is preferably curved in a manner to permit light to pass directly through the outer radial surface with minimal refraction. Alternatively, the inner and outer radial surfaces may both be curved. 
     According to further detailed aspects, the second member may be a reflector or a lens. When the second member is a lens, the second lens member defines an interior passageway extending through the second lens member which receives the first lens member. The interior passageway defines an interior surface which is structured to refract light from the first lens member. Preferably the interior surface is flat in the axial direction. Alternatively the area interior surface may be structured to match an exterior radial surface of the radial portion of the first lens member, thereby permitting light to pass directly through the interior surface with minimal refraction. The second lens member has an outer surface forming the reflecting surface which uses the principle of total internal reflection. When the second member is a reflector, the reflector preferably has a bowl shape defining an interior surface forming the reflecting surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is a cross-sectional view of a light assembly and lens assembly constructed in accordance with the teachings of the present invention; 
         FIG. 2  is a cross-sectional view of a first lens member of the lens assembly; 
         FIG. 3  is a cross-sectional view of an alternate embodiment of the first lens member depicted in  FIGS. 1 and 2 ; 
         FIG. 4  is a cross-sectional view of an alternate embodiment of the light assembly and lens assembly depicted in  FIG. 1 ; and 
         FIG. 5  is an alternate embodiment of the light assembly with the inner lens of  FIG. 2  and  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the figures,  FIG. 1  depicts a cross-sectional view of a light assembly  20  having a lens assembly  30  for an automotive lighting application. The light assembly  20  generally includes a LED light source  22  having a cover lens  23  and generating light from a source point  24  downstream along a longitudinal axis  26 . The lens assembly  30  collects and collimates the light from the LED light source  22  for generating a desired beam pattern for the particular automotive lighting application. Unnumbered lined arrows have been used throughout the application to depict the path of traveling light. 
     The lens assembly  30  generally includes a first lens member  32  and a second lens member  34 . The second lens member  34  includes an interior passageway  36  defined by a conically shaped interior surface  38 . As will be discussed in more detail below, the first lens member  32  directs a portion of the light straight through the internal passageway  36  without entering the second lens member  34 . A second portion of the light passes through the interior surface  38 , and due to the shape of the outer surface  40  of the second lens member  34  the light is reflected via total internal reflection and redirected longitudinally downstream and through the axial end surface  42  of the second lens member  34 . 
     It will also be recognized by those skilled in the art that the outer surface  40  of the second lens member  34  may include a reflective coating formed thereon (i.e. such as an aluminum coating) to further assist with the reflection of the light or to permit a different curvature or structure to be given to the outer surface  40  of the second lens member  34 . 
     Additional details of the first lens member  32  will now be described will reference to  FIG. 2 . As shown, the first lens member  32  defines a recess  44  receiving the LED light source  22 . The first lens member  32  thus comprises a radial portion  45  connected to an axial portion  47 . The radial portion  45  is generally defined by an inner radial surface  46  and an outer radial surface  50 . Similarly, the axial portion  47  is generally defined by an inner axial surface  48  and an outer axial surface  52 . Accordingly, the recess  44  is generally defined by the inner radial surface  46  and the inner axial surface  48 . 
     As light emanates from the light source origin  24 , a portion of the light will pass through the axial portion  47 . In this embodiment, the axial portion  47  has been formed as a Fresnel lens, the structure of which is well known in the art. Briefly stated, the inner axial surface  48  is comprised of a series of arcuate channels  54 , while the outer axial surface  47  is flat and planar, and generally perpendicular to the longitudinal axis  26 . As used herein, the term generally perpendicular means line or surface that is within about 3 degrees of true perpendicularity. 
     Another portion of the light emanating from origin point  24  will pass through the radial portion  45  of the first lens member  32 . As shown in  FIG. 2 , the inner radial surface  46  is generally flat, and more particularly is conical or tapered as it extends longitudinally downstream. As such, light passing through the inner radial surface  46  will be refracted as shown by the arrows indicating the light path. The outer radial surface  50  has been structured in a free form curvature (i.e. numerically generated) such that the light passing through the radial portion  45 , as refracted by the radial inner surface  46 , is permitted to pass directly through the outer radial surface  50  with zero refraction for a point source and minimal refraction for a finite source. As used herein, the term minimal refraction refers to a range of refraction between 0 and 3 degrees. 
     Referring back to  FIG. 1 , it can therefore be seen that the axial portion  47  of the first lens member  32  serves as a focusing lens to direct the light longitudinally downstream and through the interior passageway  36  of the second lens member  34 . This light can assist in forming a “hot spot” in the resulting beam pattern. Additionally, light passing through the radial portion  45  is redirected towards the second lens member  34 , and in particular the interior surface  38 . The radial portion  45  of the first lens member  32  and the second lens member  34  are structured and positioned relative to one another to collect a substantial portion of the light, collimate the light, and redirect the light longitudinally downstream via total internal reflection. Here, the flat and conical interior surface  38  refracts the light, which is then reflected by the outer surface  40  and directed downstream. 
     Turning now to  FIG. 3 , an alternate embodiment of the first lens member  132  is depicted. As in the prior embodiment, the first lens member  132  generally includes a radial portion  145  and an axial portion  147 . However, in this embodiment the radial portion  145  includes a curved inner radial surface  146 . The curvature of the inner and outer radial surfaces  146 ,  150  may be structured so that the light passing therethrough is only minimally refracted, or may be structured to refract the light in a manner acceptable for use by the second lens member, which is structured according to the principles described in the embodiment of  FIGS. 1-2 . 
     It can also be seen in the embodiment of  FIG. 3  that the axial portion  147  includes an inner axial surface  148  that is curved to form a lens for collimating the light. However, it will be recognized by those skilled in the art that the inner axial surface  148  could be flat, as shown by dotted line  148   a  while the outer axial surface  152  includes a curvature for focusing the light rays. 
     It will also be recognized that while the axial portion  147  has been shown as generally including beam focusing optics such as the Fresnel lens of  FIG. 2 , or the lens  148  of  FIG. 3 , the axial portion may also include beam spreading optics. As one example, the outer axial surface  152  has been shown as including plurality of pillows  156 . As is known in the art, such pillows or flutes serve to spread the light passing through the axial portion  147 , and generally create a beam pattern which is ideal for applications such as brake lights, tail lights and the like. While the beam spreading optics  156  have been shown used in conjunction with a beam focusing optics  148  in  FIG. 3 , it will be recognized that the beam spreading optics  156  can be used alone (i.e. in conjunction with a flat axial inner surface  148   a ). 
     Yet another alternate embodiment of the light assembly  220  and lens assembly  230  is depicted in  FIG. 4 . In this embodiment, the LED light source  220  generates light from a point or origin  224  which is collected and directed by first lens member  232  in a substantially similar fashion as the prior embodiments. However, in this embodiment the second lens member  234  includes an interior passageway  236  defined by an interior surface  238  that is structured to match the outer surface  250  of the first lens member  232 . That is, the interior surface  238  may be structured such that all light it receives from the first lens member  232  passes directly through the interior surface  238  with minimal refraction. In the embodiment depicted, the interior surface  238  has been divided into an upstream portion  238   a  and a downstream portion  238   b . The upstream portion  238   a  is given a curvature which matches the curvature of the outer radial surface  250  of the first lens member  232 . The downstream portion  238   b  may then be made simply cylindrical, or alternatively could be conical as in the prior embodiment. Furthermore, it will be recognized by those skilled in the art that depending upon the structure of the radial portion of the first lens member  232 , the entire interior surface  238  may be given a curvature, typically a free-form curvature, which is structured to correspond to the path of light passing through the radial portion of the first lens member  232 , resulting in minimal refraction of the light through the interior surface  238 . As with the prior embodiments, the second lens member  234  includes an outer surface  240  which serves to reflect and collimate the light longitudinally downstream along the longitudinal axis  226 . 
     A final embodiment has been depicted in  FIG. 5 . In this embodiment, the light assembly  320  and lens assembly  330  include an LED light source  322  generating light from origin  324  through a first lens member  332 , all of which may be constructed in accordance with the teachings of the present invention and the prior embodiments. However, in this embodiment the second lens member has been replaced with a reflector  334 . The reflector  334  has a general bowl shape and includes an interior surface  335  defining an interior chamber  336  which receives the first lens member  332 . Preferably, the interior surface  335  is structured to include a plurality of facets which result in a redirection of the light emitted from the first lens member  332  with some predetermined beam spread characteristics, such as is shown by the lined arrows of  FIG. 5 . It will be recognized by those skilled in the art that a number of types of reflectors  334  may be used to generate the desired beam pattern for the particular automotive application. 
     By way of the present invention, an automotive light assembly is provided having a lens assembly that overcomes the drawbacks of forming a single NFL of a relatively large size (i.e. a larger focal length) by splitting the function of the lens into a first lens member and a second member. In this manner, the lenses may be formed by conventional techniques and conventional tools. Further, with members, more flexibility and opportunity to adjust or impact the beam spread characteristics is possible. Thus, the present invention provides smaller output beam size and higher peak intensity, as well as increased flexibility, without the complex molding issues and expensive tools and processes. 
     The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Technology Category: f