This application claims the benefit of priority of Czech Republic Patent Application No PV. 2010-789 filed on Nov. 1, 2010 hereby incorporated herein by reference in its entirety.
This invention relates to the construction of interior and exterior signal lighting in vehicles and more particularly to a light guide module with adjustable lighting of a contour surface including light sources and a light guide.
The uniformity of lighting of dashboards or other interior parts is usually a critical parameter in the area of interior signal lighting. Because front and rear contour lights, directional indicator lights, and daytime running lights are used to accentuate the exterior style features of a vehicle, requirements for homogeneity are also becoming essential for exterior signal lighting. For these purposes, light guide components with light-emitting diodes (LEDs) are commonly used as a light source.
Light guide components, constructed according to the required appearance, can have a linear base or a planar base.
A linear light guide component can be added to one side or both sides in the direction of the light guide axis, i.e., usually perpendicular to the lighting direction. The drawback to this approach is that it cannot be used on a complicated contour shape with relatively small diameters.
A planar light guide component is ordinarily provided with several LEDs and an axis that coincides with the lighting direction. In order to attain the required homogeneity of the emerging beam, it is possible to use collimating optical elements on the input surface or properly constructed optical elements on the exit surface. The drawback of this approach is the large number of LEDs arranged along the entire input surface.
It would be desirable to have a light guide module that can achieve a required lighting using totally uniform lighting of the contour surface.
Consonant with the present invention, a light guide module that can achieve a required lighting using totally uniform lighting of the contour surface, has surprisingly been discovered.
In an embodiment of the invention, the light guide module with adjustable lighting of the contour surface is composed of light sources and a light guide. The light guide is composed of a primary part, a Y-shaped branch, and a secondary part with contour surface. The supporting surface of the Y-shaped branch of the light guide is composed of a system of directional optical elements, is of prismatic shape, conical shape, or a combination of these, and has its vertex on the optical axis of the primary part of the light guide.
The light sources are light-emitting diodes (LEDs) placed behind the primary part of the light guide. The light-emitting diodes (LEDS) behind the primary part that terminates in a conically configured Y-shaped branching have a higher luminous flux than the light-emitting diodes (LEDs) behind the primary part that terminates in a prismatically configured Y-shaped branching.
The first edge of the light guide is provided with a collimating component.
The directional optical elements are formed by planar surfaces, cylindrical surfaces, or non-uniform rational base splines surfaces (NURBS), whose shape is defined by the shape of the entry region S and the incoming illumination F [lx] onto S, and the shape of the exit region T and the required outgoing illumination G [lx] onto T.
As is illustrated in
where Sε(s), Tε(t) are areas in S, T around φ(s), γ(t) with thickness s and width W. For the Y-shaped branching in t in the shape of a prism, the relationship f(s)=F(φ(s))W, g(t)=G(γ(t))W is obtained.
According to this notation, the region Si, defined by the interval of parameters [si, si+1] of curve φ, corresponds to the region Ti, concerning the parameters [ti, ti+1], ti=t(si), ti+1=t(si+1) of curve γ and
where β is the absorption constant in the material, and x(s, t) is the distance between points φ(s), γ(t(s)).
Let
be defined as the coefficient of energy saturation. If B=1, as much energy as is needed is available from region S to region T. If B>1, there is a surplus of luminous energy in region T. If B<1, there is a deficit of luminous energy in region T. In such cases, one can work with a modified formula ĝ(t)=B g(t). It must be noted that B is a function of absorption in the material, since this is the function t(s). It is assumed hereinafter that B=1.
By rearranging (Q1), an equation is obtained for the desired function t=t(s)
f(s)e−βx(s,t)=g(t)t′ (Q2)
A general solution for (Q2), in the case of constant losses in the material, e−βx(s,t)=ω(s) can be written in the form,
∫g(t)dt=∫f(s)ω(s)ds+C (Q3)
where the constant C is established by the choice of the starting point of the curve γ. Equations (Q2), (Q3), as well as the most general case, when B≠1, are usually solved for the unknown function t=t(s) by numerical and iterative methods.
The structure of the panels Si, forming the Y-shaped branch of the light guide, which reflect only into the region Ti in the contour region T, has a high sensitivity to fabrication inaccuracies and tolerances. To reduce this sensitivity, the faces Si are constructed as planar surfaces, cylindrical surfaces, or NURBS surfaces, which reflect the beams incident upon a region in region T containing the region Ti.
The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description when considered in the light of the accompanying drawings, in which:
The following detailed description and appended drawings describe and illustrate an exemplary embodiment of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner.
The light guide module shown in
The light guide 2 is composed of a primary part 3, a Y-shaped branch 4, and a secondary part 5 having a contour surface T. The supporting surface of the Y-shaped branch 4 of the light guide 2, which is made up of a system of directional optical elements Si, is of prismatic shape, conical shape, or a combination thereof (see
The light sources 1 are light-emitting diodes (LEDs) located behind the primary part 3 of the light guide 2. The light-emitting diodes (LEDS) located behind the primary part 3 that terminates in a conically configured Y-shaped branching have a higher luminous flux than the light-emitting diodes (LEDs) located behind the primary part that terminates in a prismatically configured Y-shaped branching.
The first edge 31 of the light guide 2 is provided with a collimating component 32. The component 32 can be constructed as an optical collimator or a Fresnel lens, in order to create a collimated beam of light for loss-free propagation of the light in the light guide 2.
The directional optical elements Si are formed by planar surfaces, cylindrical surfaces, or NURBS surfaces.
In
The contour surface T of the secondary part 5 can be oriented in any manner with respect to the optical axis of the primary part 3.
Another application of the light guide module is an optical system where the contour surface T serves as a light source for another part of a more complex optical system.
The advantage of the light guide module is high efficiency, since LEDs are used as the light sources 1 and the light propagates in the light guide 2 without losses. The light guide module, moreover, has minimal space requirements, and, because it has only a small rigid board with printed circuits, it reduces costs.
From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.
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