Illumination – Supported by vehicle structure – Automobile
Reexamination Certificate
1999-07-23
2001-09-18
Cariaso, Alan (Department: 2875)
Illumination
Supported by vehicle structure
Automobile
C362S140000, C362S268000, C362S293000, C362S510000, C362S309000, C362S331000
Reexamination Certificate
active
06290378
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a lighting device for arrangement on the external or internal rear view mirror of a motor vehicle with a light source, the light rays of which emerge at a mirror housing opening and are deflected at a transparent light refraction element arranged in the beam path, the plate-like light refraction element having a surface structure, at least on one side, by means of which the light refraction element is divided into several light refraction zones.
BACKGROUND OF THE INVENTION
Lighting devices of this kind are incorporated into the external or internal rear view mirrors of motor vehicles and serve either to illuminate the interior or to illuminate the road surface in the entry region in front of the vehicle's doors. The light generated by the light source emerges at a mirror housing opening and radiates therefrom in beam form. The generated luminous intensity in the various regions of the field of illumination thus substantially depends on the distance between the region in question and the lighting device and on the angle of the incident light.
Since the installation location of the lighting device is predetermined by the positioning of the external or internal rear view mirror, in many cases the luminous intensity is distributed in the field of illumination in a manner which is not optimal. Far distant places in particular are only relatively poorly lit, for which reason a high illumination power is required. It is therefore known to arrange optical components in the path of the beam of the lighting device by means of which the distribution of the luminous intensity may be influenced. Fresnel lenses in particular have been proposed for this application because they are inexpensive to produce and are of compact size. Fresnel lenses are plate-like light refraction elements, of glass or plastic for example, which at least on one side have a surface structure by means of which the Fresnel lens is divided up into several light refraction zones. The light refraction zones correspond to circular ring-shaped lens sections which are pushed together stepwise in the plate plane so that the light refraction in a Fresnel lens approximately corresponds to the light refraction in a three-dimensional lens body.
It is a drawback to the use of the known centric Fresnel lenses that the light beam can only be scattered or collected depending on design, by the refraction at the Fresnel lens. This means that the light beam generated can be either widened or concentrated by the Fresnel lens.
A deflection of the light beam into a certain preferred direction cannot be achieved by the centric Fresnel lens as the light refraction zones are arranged circular-symmetrical to the optical center line.
SUMMARY AND OBJECTS OF THE INVENTION
The primary object of the present invention is to provide a generic lighting device, the light beam of which may be deflected into a preferred direction by light refraction in a light refraction element.
According to the invention a lighting device is provided for arrangement on the external or internal rear view mirror of a motor vehicle with a light source, the light rays of which emerge at a mirror housing opening and are deflected at a transparent light refraction element arranged in the beam path. The plate-like light refraction element has a surface structure, at least on one side, by means of which the light refraction element is divided into several light refraction zones a light refraction element which is designed in the manner of a Fresnel prism is arranged in the beam path of the lighting device. The light refraction element has a surface structure which divides it into a plurality of at least two light refraction zones, the light refraction zones preferably Corresponding to the prism zones of a three-dimensional prism body which are pushed together in stepwise manner.
It is known that a light beam is refracted in a prism body and deflected by a certain angular quantity. As a prism body requires a great deal of installation space and can only be produced at high cost, the prism zones of the prism body are pushed together in stepwise manner, so that a Fresnel prism with a plate-like structure according to the invention emerges. The optical effect of the Fresnel prism substantially corresponds to the effect of a prism body with spatial expansion, so that the Fresnel prism also brings about an angular deflection of an incident light beam. In the solution the light beam may be deflected into a preferred direction by the Fresnel prism by light refraction. The design and relative arrangement of the individual prism zones is arbitrary according to the invention and must be matched to the particular application. According to the invention a Fresnel prism is also conceivable which represents a combination of a centric Fresnel lens and a Fresnel prism, so as to be able to bundle or scatter the light beam at the same time as the deflection.
According to a preferred embodiment of the invention the prism zones are arranged in the Fresnel prism in a manner running linearly parallel to each other. Such Fresnel prisms may be produced inexpensively since the necessary plate contour may be cut or stamped out of a continuous material or may be produced by injection molding. Fresnel prisms with prism zones which run in arbitrarily curved manner are, of course, also conceivable.
If the lighting device is installed in an external rear view mirror, it is advantageous when the prism zones run substantially perpendicular to the longitudinal axis of the vehicle. In this case the individual prism zones should be formed in such a way that the light is refracted in the direction of the rear of the vehicle. By this arrangement it is possible to illuminate the entry region in front of the vehicle doors substantially completely without regions of the road surfaces which lie outside the entry region being illuminated unnecessarily. The light energy used is therefore optimally distributed over the desired field of illumination.
The light beam emerging at the underside of the external rear view mirror is deflected by the Fresnel prism in such a way, for example, that the front edge of the light cone impinges on the road surface in the region of the front edge of the door and the rear edge of the emerging light cone at the rear end of the entry region, in front of the rear wheel for example. In the solution the light cone is concentrated on the entry region by light refraction. If the light beam were not deflected it would propagate uniformly from the light source so that a large region in front of the entry region would be illuminated unnecessarily.
The prism zones of a regular Fresnel prism all have the same angle of refraction so that parallel incident light in all prism zones is deflected by the same angular quantity. According to the invention, Fresnel prisms may also be employed which have at least two prism zones with different angles of refraction. The achievement of this is that the light is deflected at the different prism zones at different angles so that according to the choice of the different angles of refraction the light beam may be collected or scattered in different spatial sectors.
If the lighting device is used in an external rear view mirror to illuminate the entry region, a light emergence surface virtually parallel to the road surface is produced because of the installation situation of the lighting device in the base region of the external mirror. The external mirror comprises an exterior mirror assembly including a housing within which is located a reflective element, which may be electrochromic or conventional (such as a chromium or titanium metal reflector coating on a glass substrate) and with the reflector preferably positionable by a manual or electrically actuated actuator, the actuator also located within the mirror assembly housing. The exterior mirror assembly further comprises a mount that attaches the housing to the side of the vehicle.
The mount may be a breakaway mount or a powerfold mount, as known in the rea
Buchalla Harald
Furst Peter
Polzer Herwig
Cariaso Alan
Donnelly Hohe GmbH & Co. KG
McGlew and Tuttle , P.C.
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