Illumination – Light source and modifier – Including reflector
Patent
1994-12-05
1997-07-15
Quach, Y My
Illumination
Light source and modifier
Including reflector
362298, 362304, 362346, F21V 704
Patent
active
056476647
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a lighting system for lighting fittings, projectors and enlarging apparatuses, which provides an intensive and uniform illumination of a given area at a given distance. It consists of a light source, an auxiliary mirror and the main mirror. Another part of the system is a raster lens, consisting of a net of individual converging lenses, which direct the light rays coming from the source into the required plane, where they create the light spot.
2. The Prior Art
There exist many lighting systems used above all as automobile headlights. These systems are usually made by a continuous parabolic reflector covered by a cover glass with diverging elements. The light source is a halogen bulb with two filaments; one is for distance light and the other one for lower beam with an internal diaphragm that allows limitation of the lower beam. In order to decrease the reflector's vertical size, the classical paraboloidal reflector was remodelled into the shape of a homofocal reflecting surface in such a way that this reflecting surface was divided into a system of discretely connected paraboloidal segments with the same optimized focal length. The need for another decrease of the headlight's size leads to a production of an ellipticdioptric system. Its reflector has a shape of a rotational or polyelliptic ellipsoid with three axes. In one of its focuses there is the filament of the bulb and in the second one there is a diaphragm. The planoconvex lens, situated in the second focus of the ellipse, directs the output light rays so that they are parallel with the optical axis of the system. This lens also projects the diaphragm into the luminous background of the roadway. This process defines distribution of the subdued beam illumination.
As there is only one filament in the bulb, this system can be used for lower beam only. Therefore one more lighting fitting of a similar or the same construction is necesarry for a distance light. The said lighting fitting has a very small height and it creates lower beam of a good intensity and homogenity with a sharp boundary between light cone and darkness. Another lighting fitting with an increased reach of lower beam illumination has a reflector of the type with a freely formed reflecting surface, which is continuous and closed in such a way that, without the influence of a covering glass, the reflector projects to the required space elementary filament of a single filament bulb. Even without the diaphragm, it makes a boundary between darkness and light. Light output capacity of such a system proportionally increases with the size of the reflector and it allows also using of its lower part, what increases the efficiency. Nevertheless, for a distance light an extra lighting fitting is needed. By the use of the conception with freely formed reflecting surface an improved projective elliptical dioptric system of the lighting fitting is achieved. The original ellipsoid is remodelled into a general surface with a higher amount of light beam in the non-diaphragmed part of the focal plane. The reflector is more open in its upper part and more closed in its lower part. The light ouput of such a system is much higher in comparison with the previous system.
Similar lighting systems can be used for different illuminating purposes, e.g. in the health service, as spotlights used in stomatology. These systems consist of a known type of planary lighting fittings using mostly as light sources a halogen bulb, and a cold reflecting concave mirror. Its reflecting part is arranged as raster mirror, which directs the light spot into the required plane.
The main disadvantage of present automobile lighting systems consists in their low luminous efficiency. Moving vehicles use the light beam, reflected by differently shaped mirrors, and the luminous flux coming out of light source straight ahead is not used and is therefore often shaded. Dazzling effect is another big disadvantage of such a lighting fittings, since almost all system
REFERENCES:
patent: 3488489 (1970-01-01), Jones
patent: 4035631 (1977-07-01), Day, Jr.
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