Illumination – Supported by vehicle structure – Projection-type headlamp
Reexamination Certificate
1998-12-21
2001-11-06
O'Shea, Sandra (Department: 2875)
Illumination
Supported by vehicle structure
Projection-type headlamp
C362S507000, C362S538000, C362S512000, C362S513000, C362S464000, C362S465000
Reexamination Certificate
active
06312147
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a headlight for vehicle in accordance with a projection principle.
Headlights of the above mentioned general type are known in the art. One of such headlights is disclosed for example in the German patent document DE 40 02 576 A1. The headlights serves for selectively producing a low beam or a high beam. The headlight has a light source and a reflector for reflecting the light emitted by the light source. A lens is arranged in a beam course of the reflector and a shade device is arranged between the reflector and the lens. The shade device is changeable between a first condition for the operational position of the headlight for the low beam, and a second condition for the operational position for the high beam. The shade device screens in the first condition a part of the light reflected by the reflector and produces a bright-dark limit of the low beam bundle exiting the headlight. In the second condition the shade device shades at least a small part of the light reflected by the reflector. The change of the shade device between its first and second condition can be performed by its movement or the shade device can have at least locally a changeable light permeability, so that the light permeability in the first condition of the shade device is low and in the second condition is high.
The above described known headlight has the disadvantage that it can be optimal either for producing the low beam or for producing the high beam. However, no design is possible for optimal production of both light functions, since the requirements for them are partially contradictory. If the headlight is optimal for the production of the low beam, with the shade device in the first condition, then in the operational position for the high beam with the shade device in the second condition no efficient high beam is produced, since the high beam bundle exiting the headlight can be produced with very low maximum illumination intensities. If to the contrary the headlight is designed so that in its operational condition for high beam with the shade device in its second condition an efficient high beam bundle with its maximum illumination intensities is emitted, then the shade device in its first condition for the operational position of the headlight for low beam must be arranged so that a greater part of light reflected by the reflector is shades, since otherwise the low beam can be produced with impermissibly high illumination intensities. With the arrangement of the shade device required for this in the first condition, moreover substantial image forming error by the lens occurs, such as color edge or over radiation which jointly negatively affects the quality of the low beam bundle. Moreover, the headlight in the operational condition for the low beam is adjusted so that the bright-dark limit assumes the prescribed position, but in the operational position for the high beam the regions with the maximum illumination intensities are located too high.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a headlight for a vehicle which avoids the disadvantages of the prior art.
In keeping with these objects and with others which become apparent hereinafter, one feature of present invention resides, briefly stated in a headlight for a vehicle in accordance with the projection principle in which a further shade device is arranged offset in direction of the optical axis of the first shade device and is changeable between at least a first condition and at least a second condition wherein the further shade device in its first condition screens a part of the light reflected by the reflector and passing on the first shade device in its first condition, in order to reduce maximum illumination intensity values produced by the light bundle exiting the headlight in its first operational condition, and the further shade device in its second condition screens only a small part of the light reflected by the reflector.
When the headlight is designed in accordance with the present invention, the production of the bright-dark limit in the first operational condition of the headlight is performed by the first shade device in its first condition and the position of the regions with maximum illumination intensity values can be selected as required for the light bundle emitted by the reflector in the second operational condition, without taking into consideration of the low maximum illumination intensity values which are permitted from the light bundle emitted in the first operational position of the headlight, which are maintained by the second shade device by screening of a part of the light produced with the maximum illumination intensity value.
In accordance with a further feature of the present invention, the further shade device is arranged after the first shade device is considered in a light outlet direction. This provides the advantage that the bright-dark limit is produced by the further shade device without being influenced by the first shade device.
In accordance with still another feature of the present invention the further shade device is curved in direction of an optical axis preferably concavely. This has the advantage that during shading with a further shade device, a homogenous transition is produced.
In still another embodiment of the invention, the further device is formed so that in the first condition the light which passes on the first shade device and illuminating the opposite traffic side in front of the vehicle is screened in a greater part than the light passing on the first shade device which illuminations the traffic light itself in front of the vehicle. This provides an improved illumination of a traffic side in front of the vehicle.
Finally, in accordance with still another feature of the present invention, the shade devices are coupled with one another and together are movable between the first and second conditions. This provides for a simple construction of the headlight, since both shade devices can move with a single adjusting element.
The novel features which are considered as characteristic for the present invention are setforth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 5161875 (1992-11-01), Sekiguchi et al.
patent: 5339226 (1994-08-01), Ishikawa
patent: 40 02 576 A1 (1991-08-01), None
Negron Ismael
O'Shea Sandra
Robert & Bosch GmbH
Striker Michael J.
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