DE202007001829U1 - Low beam headlight for motor vehicle, has primary and secondary lenses, where Z-shape generation takes place by bundling primary and secondary lens segments that project edge segment with Z-shape from light bundle cross section of LED - Google Patents

Abstract

The headlight has a total internal reflection reflector (TIR), and a light module that has an LED with a condenser lens (CL). Two secondary lenses are arranged optically downstream to a primary lens. The primary and secondary lenses have three lens segments, where Z-shape generation takes place by bundling primary and secondary lens segments that project an edge segment with a distinct Z-shape from a light bundle cross section of the LED.

Description

Background of the invention:

White high-power LEDs (High-power LEDs) are on the rise in many areas of everyday life and sit opposite each other Halogen lamps or fluorescent tubes increasingly through. Thanks to typical advantages such as robustness, durability, Low-voltage power supply, increasing efficiency and color quality are LED headlights has become a particularly interesting topic in recent years. Involve without exception automotive suppliers with the development of LED headlamps (LED-SW) to mass production and cancel for 2007 to 2009 various products.

in the Comparison to other common light sources, feature LEDs over a lower luminance. activities for generating higher illuminance levels the illuminated road surface must be hit become. in principle this problem is solved by multiple superimposition of light distribution patterns, generated by individual "paler" sources become. This drives the number of required LEDs, the complexity of the arrangement and their manufacturing costs in the amount. Consequently, there is a central one Question of novel optical approaches in the raise the decoupling efficiency, thus counteracting the number of LEDs and the structural complexity can be. At the same time, however, one is also aiming for a more homogeneous one streak-free light distribution with pronounced hot spot and sufficient Width illumination, which keep up with the current state of the art and possibly exceed can. higher Efficiency and a lower number of LEDs per SW can be the SW-space requirements lower, bringing the vehicle design new degrees of freedom are offered.

Of the Current state of the art is provided by modern (bi) xenon headlights with shaped Z-shaped Light-off (Cut-off with Z-shape) marked. A Z-shape distribution according to ECE R98, in difference to a distribution with pronounced 15 ° -increase according to ECE R11 a higher one Range and better illumination of the right side of the road.

optical As seen, a modern xenon gas discharge lamp provides an advantageous light source with small outer dimensions, high Luminance and high luminous flux, e.g. 3000 [lm]. The high luminous flux makes energetically inefficient diaphragm-based approaches possible, for example: Bi-xenon headlights in low beam mode. In typical headlamp projection systems the object environment is reflected by reflectors, concentrators and accordingly formed shaped panels. Absorb and / or block the panels the light, so much of it of the generated light flux does not reach the roadway. typically, About 35% of the emitted light is used to illuminate the road used.

in the Case of LED headlamps would be Such a low efficiency unacceptable, since one is impractical high number of LEDs for a headlight available must be set, e.g. at least 30 LEDs with a luminous flux of each 100 [lm] per LED to reach the 3000 [lm] of a xenon source. Motor Vehicle Manufacturers That is why we are looking for more efficient solutions.

On the other side is also looking for ways that are relatively high ignition more common Xenon headlights in the vehicle to avoid and energy consumption, as well as reducing temperature exposure of the immediate environment. LEDs offer a serious alternative as a light source.

LED headlights are expected to be rated according to ECE R112, however, to face Xenon headlights To enforce, it applies, at least one comparably good light distribution realize, as already pointed out, significantly higher efficiency and homogeneity will play a crucial role.

One Walkthrough is over Parallel 2D projections by means of several modularly constructed beam paths possible. According to the superposition principle, the individual beam intensities are added up, so that the required illuminance values are achieved on the road. It is important, not the LED chip itself, but like from one Slide projection system known, an object environment suitable light intensity concentration and with shaped cut-off or Z-shape in the viewing plane (Roadway). As repeatedly emphasized, this is what it is often by absorbing or blocking diaphragms.

in the In contrast, the present invention describes an approach which defines a specially shaped object environment that the light not just stops, but over Redirection to different imaging optical elements, the required object environment adjusts and project onto the roadway. Thus, a larger proportion (over 55%) of the original LED light flux in compliance with the required light distribution and homogeneity, at pronounced Hot spot, Z-shape and cut-off ECE-R98 compliant coupled and distributed.

Since there are several individual beam paths, they must be coordinated so that the illumination edge sharpness in the required areas halves can be. One deliberately uses a bundle divergence to achieve a better width illumination and homogeneity.

The System is based on a mixed but contiguous 1D and 2D mapping or projection principle. It has a partial modular character, so that according to the superposition principle several primary partial lenses on common Secondary sub-lenses contribute to the basic distribution and the hot spot formation by individual Primary and secondary parts takes place.

The Basic distribution is over 1D projection implemented by upper and lower sub-beams. At the bottom Beam path becomes a two-fold image over a mirror and over a secondary lens höhenvertauscht realized. The upper and the lower beam path produce two overlapping oneself Illustrations.

The Z-shape and hot-spot formation is achieved through multiple 2D projection. Again, there are basically upper and lower beam paths, where in the lower also an image inversion via mirrors or dove prisms is made.

The Z-shape forming object environment is divided into segments in a Y-shape. Here are an upper, a lower vertical to be reflected, and a rest segment formed. The rest segment will be horizontal over one Mirror or a dove prism reversed and projected appropriately.

embodiments will be explained in more detail in the following description.

It shows

1a and b schematically a LED with condenser lens

2 Arrangement with primary lens

3 schematically the course of different light bundles

4 beam paths

5 Shifting the Z-shape wedge

6 : Construction of a headlamp with lens segments

7 Simply segmented secondary lenses

8th Embodiment with Dove prisms

A would be a narrow source in principle advantageous. However, some current high-power LEDs, which already has a luminous flux in the order of 50lm to 75lm and to deliver more than 125lm per LED in the near future, quite far-angular in their radiation. A spherical dome lens with a radius from e.g. 2.8mm is over the Chip placed. This sets the absolute light output higher, more difficult but the effective utilization of the light source aperture.

In 1a and b is a condenser lens CL, used. Since this lens CL can not geometrically and optically focus the lateral components, a total internal reflection reflector TIR-in 1 shown as a wire model - laterally built around the CL and merged with it. Thus, the combination of TIR reflector and refractive condenser CL collects much of the radiated LED light flux. Only Fresnel reflections and stray light reduce the optical efficiency.

The light flux is applied to a so-called primary lens PL as in 2 shown, directed.

The PL has the task to divide the bundle that strikes it and as a Z-shape-forming object to serve. This serves a wedge-shaped Structure ZK. At the same time changed the primary lens specifically the intensity distribution within the light beam emerging from it. These are a variety of lens segments PLS 1, PLS 2 ... available. She also manages the prerequisite for the generation of hot spots (Angular range of high light intensity Below the measuring line HV to ECE R98, or local area higher illuminance on the measuring wall 25m away) and the cut-off (area high edge contrast).

3 schematically shows the course of different light beams from the LED via the primary lens PL to the secondary lens SL.

Of the Z-Shape required by ECE R98 is generated near the HV point and the hotspot become.

in the bottom beam is the object to be imaged according to the image inversion principle imaged vertically with the help of a mirror SP or with dove prisms and then displayed two-dimensionally instead of one-dimensional. As a result, this means that both horizontal edges, as well tilted Z-shape edges are sharply imaged. Thus, the secondary lenses no cylindrical but two-dimensional imaging aspheres or others suitable optical surfaces. The segments of the secondary lens (SLS1, SLS2 ...) are assigned to at least one segment of the primary lens.

4 shows the optical paths OS and US. The PL is intended to efficiently couple the light coming from the CL into the secondary lens SL. It distributes the individual light bundles to corresponding subregions of the secondary lens, avoiding that light falls on the interfaces between these areas, so that scattered light can be efficiently avoided.

In order to use the luminous flux effectively, the Z-shape formation is accomplished not via absorbing or blocking diaphragms, but via optically refracting surfaces, which focus their light components on specially provided subregions of the secondary lens. Such a role is assumed in 3 the Y-shaped partial surface ZK between the two inner splitter surfaces in the primary lens.

In the secondary lens become more surfaces for the Z-shaped wedge provided. These are the middle SLS3 areas. The image of the Z-shape wedges ZK must be reversed horizontally, so that they are better contribute to the Z-shape can.

In the 5 you can see the main differences of a slightly modified primary lens. It is a shift of the Z-shape wedge ZK.

The associated secondary lenses are also modified. The optically active surfaces, ZK and SLS3 surfaces are decentered horizontally, so that the inclined Z-shape edges of the individual images overlap exactly. If now the two grayscale images illuminance distributions are superimposed on a measuring wall 25m away from the observer) a much more homogenous distribution results as in 7 shown.

Consequently you have now generated the Z-shape. You can do a variety of such provide double modules. It is also conceivable, everyone involved Modules easy to modify, so that in the end one still more homogeneous overlap can generate.

The next picture 6 Represents 6 hot-spot and Z-shape modules with reversing mirrors.

Around to ensure the breadth of illumination is either on a symbiotic arrangement but with TIR collectors resorted or on a radially fanned out Arrangement of individual modules.

There The structure only has to be one-dimensional, its vertical Extension be kept lower than that of a corresponding 2D hot spot and Z-shape structure. By the higher Efficiency of TIR and condenser based coupling is less LEDs off.

overlapped Now you have both distributions, the basic distribution and the hot-spot Z-shape distribution, results in a homogeneous overall distribution.

An exemplary arrangement can be as in 8th look like this. In this example, dove prisms DV are used as reverse optics.

Obviously the light distribution of this structure is uniform and despite multiple projection, Z-Shape, Hot-Spot and Cut-Off are clearly pronounced.

A Further improvement on the upper right side of the Z-Shapes can be achieved by dividing the basic distribution modules into two separate module groups be split, so that on the left side a lowered horizontal cut-off edge generated and on the right - one at about 1 ° to 2 ° raised Cut-off edge is generated. This can be the right cut-off edge the hot-spot and z-shape split seamlessly into that of the raised pass over the right basic distribution.

Not Lastly, the integration of the condenser lens with parts offers the primary lens at, in particular the primary lens wreath area, which redirects the TIR shares. The inner area of the primary lens can be provided in this case as an insert in the condenser lens.

Claims (4)

Low-beam headlamp having at least one light module, wherein the individual light module has at least one light source and at least one primary lens (PL) and the light source is a luminescence diode with condenser lens (CL), characterized in that the low beam headlamp has at least two secondary lenses (SL), the primary lenses ( PL) are optically downstream, that both the primary and the secondary lens has at least three lens segments, that a lens segment of the secondary lens (SL) at least one lens segment of the primary lens (PL) is associated, and that the Z-shape generation by more bundling Primary lens and secondary lens segments, which project an edge segment of the LED light beam cross section with a pronounced Z-shape to infinity, takes place. Dipped beam according to claim 1, since characterized in that the condenser lens (CL) and / or the primary lens (PL) has a Y-shaped segment (ZK). Dipped beam headlamp according to Claim 1, characterized that between primary and secondary lens a return mirror (SP) or primer (DV) the light beam cross-section light distributions on the secondary lens maps. Dipped beam headlamp according to Claim 1, characterized that a symbiotic use of the segments of the secondary lens by neighboring light bundles the primary lens he follows.