The invention relates to a headlamp for motor vehicles having a dipped light beam of increased illumination intensity above the edge of the cut-off areas in the space where vertical traffic signs occur most frequently.

CH-A-366806 discloses a headlamp for motor vehicles comprising a reflector, a refractor and a light source placed in the reflector. The refractor is provided with a zone of spread elements located below the upper edge of the reflector.

Headlamp models disclosed up to now have a relatively low illumination intensity above the edge of the cut-off areas for illuminating vertical traffic signs, particularly in the area 2 to 4 degrees above the horizontal line and 8 degrees to the left and to the right of the vertical line. A consequence of this is a relatively low brightness level of vertical traffic signs if they are illuminated by such headlamps. Consequently, both the probability that the driver will perceive the vertical traffic signals, and the speed of his perception are lower.

This disadvantage is removed in the headlamp according to the invention as set out in Claim 1. In a preferred embodiment, the refractory elements are vertical strip flutes and at least in part of the zone of the refracting elements, their profile is of wedge shape horizontally and the refracting angle basis is at the side of the central line of the road surface. Thereby, a part of the light beam of the dipped light beam which was originally directed below the cut-off area edge is moved upwardly so that it does not overlap the trajectory of the eye of the driver passing by in the opposite direction. The vertical lenses then enlarge the light beam laterally so that the whole geometric area of the possible traffic signs occurrence is covered, whereby, the horizontal wedges direct the beam partially to the central line of the road surface, where the traffic signals are diverted by a greater angle away from the headlamp central line. Thereby, a minimal headlamp illumination intensity in the direction to the traffic signals of 0.1 to 0.2 Cd is created. This illumination intensity then ensures the necessary brightness level of their surface and thereby also the necessary speed and probability of signal perception in case of vertical traffic signals.

An example of the headlamp according to the invention will be described below, with reference to the accompanying drawings, in which:

• Figure 1 is a headlamp reflector in the light beam direction view "P";
• Figure 2 shows a headlamp in the vertical section A-A;
• Figure 3 shows the horizontal section B-B through the zone of diffusion elements; and
• Figure 4 is a vertical section C-C through the zone of refractor spread elements.

Figure 1 shows a refractor 2 in the light beam direction view "P", a reflector 1 and a light source 3. Below the upper edge 11 of the reflector 1, the refractor 2 is provided on one side or on both sides of the vertical y with a zone 21 of diffusion or spread elements 22 at a distance W from the vertical y which is given by$$\text{W = (0.3 to 1.2) . p}$$    where p is polar vector of the reflecting surface profile of the reflector 1 that extends from the focus F perpendicularly to the axis x of the reflector 1, whereby, for the parabolic or the elliptic profile of the reflecting surface of the reflector 1, p is a parameter of the parabola or the ellipse.

This distance value W determines the size and slope of the elementary representation of the light source 3, whereby the required vertical dimension of the zonal light beam is obtained.

The reflective surface of reflector 1 can be general or in the form of a paraboloid or ellipsoid of rotation with the axis of revolution x, where p is a parameter of the creating curve. This reflector 1 in the form of a paraboloid or ellipsoid axially symmetrically integrates the light flow from the light source 3 into a slightly covergent light beam.

The surface of the zone 21 of the spread elements 22 determines the illumination intensity of the zonal light beam and is determined by the width S and the height H:$$\text{S = (0.1 to 0.6) . p}$$$$\text{H = (0.05 to 0.3) . p}$$

Figure 2 shows reflector 1, light source 3 and refractor 2 with a zone 21 of the spread elements 22 under the upper edge 11 of the reflector 1. The spread elements extend vertically in the form of a wedge shape with the basis of the wedge at an upper side and the apex of the wedge below, and having a refracting angle Θ_2V where:$${\text{Θ}}_{\text{2V}}\text{= 5° to 18°}$$

Above the zone 21 of the spread elements 22, the refractor 2 is provided with a zone 23 of the spread elements 24 that extend vertically in the form of a wedge shape with the basis of the wedge at the bottom side and the apex of the wedge above, and having a refracting angle Θ_3V where:$${\text{Θ}}_{\text{3V}}{\text{= (0.05 to 1.0) . Θ}}_{\text{2V}}$$

The light spread step at the transition of zones 21 and 23 of the spread elements 22, 24 is decreased by the difference in basis height of the refraction angles Θ_2V, Θ _3V and also the light beam that passes through the zones 23 of the spread elements 24 is directed down to the road surface. Thereby, the level of dazzling illumination in the space of the eye trajectory of the driver passing by in the opposite direction is decreased.

Figure 3 shows the horizontal section B-B through zone 21 of the spread elements 22 of radius R of width T that is:$$\text{T = (0.2 to 1.2) . R}$$

This profile of the spread elements 22 in the form of vertical strip flutes enlarges the side-zonal light beam that covers the area of probable occurrence of traffic signs. A part of the traffic signals at the side of the central road surface line is angularly more declined from the axle x of the reflector 1. Therefore, at least in a part of the zone 21, the spread elements 22 extend horizontally in the form of a wedge shape with the basis of the wedge at the side of the road surface central line and the apex of the wedge at the side away from the road surface central line, and having refracting angle Θ_2H where:$${\text{Θ}}_{\text{2H}}\text{= 0.2° to 16°}$$ at the side of the road surface central line.

This arrangement improves the visibility of vertical traffic signals even when riding through a bend. The driver's optical vision is also improved.