Patent Application
20060209558
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.
Light emitting diodes (LED'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'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'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.
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.
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:
Turning now to the figures,
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
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
Referring back to
Turning now to
It can also be seen in the embodiment of
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
Yet another alternate embodiment of the light assembly 220 and lens assembly 230 is depicted in
A final embodiment has been depicted in
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.
