Illumination – Supported by vehicle structure – Light modifier
Reexamination Certificate
1998-12-04
2001-05-15
Cariaso, Alan (Department: 2875)
Illumination
Supported by vehicle structure
Light modifier
C362S334000, C362S520000, C362S331000
Reexamination Certificate
active
06231221
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally concerned with indicating light units of motor vehicles and, more particularly, with a new method of manufacturing an indicating light unit having an illuminating area with a luminous intensity that can be accurately controlled. In particular, the indicator light unit has an illuminating area with a luminous intensity that is perceived as homogeneous by the eye of an observer over a substantial part thereof
BACKGROUND OF THE INVENTION
Document FR-A-2 614 969 describes an indicating light unit comprising a single light source, a light processing or flux recovery and distributor mechanism relatively close to and surrounding the bulb, and a generally flat glass or lens.
The flux recovery and distributor mechanism is designed to modify the homogeneous angular distribution of the light emitted by the bulb all around it into a homogeneous distribution of the light, in linear terms, along at least one direction of the lens.
The lens comprises optical members in the form of striations defining steps of a cylindrical Fresnel lens, for example, designed to redirect the light from the flux recovery and distributor mechanism towards the required signaling area, generally determined by regulations.
Accordingly, the above prior art indicating light unit has a more homogeneous distribution of the light leaving the lens than a light unit with no such flux recovery and distributor mechanism, because the areas of the lens closest to the bulb in a light unit without a flux recovery and distributor mechanism receive a significantly greater quantity of light per unit surface area than areas of the lens further from the bulb.
However, the indicating light unit according to FR-A-2 614 969 has the required homogeneity properties only if the lens is substantially flat. There is nothing in the above document to indicate or to suggest how to deal with the situation in which the lens is curved, which is more and more frequently required in modem motor vehicles.
What is more, it is apparent that the striations formed on the lens can have greatly varying light transmission coefficients, according to the deflection that they are required to provide.
This also contributes to the homogeneity of a prior art indicating light unit of the type with a flux recovery and distributor mechanism being less than perfect, despite the effect of the flux recovery and distributor mechanism.
DISCUSSION OF THE INVENTION
The present invention aims to mitigate the above limitations of the prior art and to provide an indicating light unit that can include a lens which can be highly curved and have optical deflector arrangements with significantly different transmission characteristics, although said lens has a homogeneity of illumination that can be accurately controlled. In particular, the illumination can be homogeneous over a wide range.
Accordingly, the present invention proposes a motor vehicle indicating light unit comprising a light source, an optical plate having optical arrangements adapted to redirect light from the region of the source so that it propagates with a mean direction generally parallel to a horizontal optical axis, and a flux recovery and distributor mechanism disposed between the source and the optical plate. The flux recovery and distributor mechanism is adapted to assure a given distribution of light onto the inside surface of the optical plate in at least a given direction, wherein the optical plate is curved and has optical arrangements having different light transmission coefficients. The flux recovery and distributor mechanism assures the given light distribution which allows for the different transmission coefficients to obtain an evolution of the illumination at the exit from the plate in the given direction that satisfies a predetermined law.
The optical arrangements advantageously have transmission coefficients that change stepwise in accordance with their position in the given direction. The light distribution imparted by the flux recovery and distributor mechanism also changes stepwise in the given direction.
In one particular embodiment, it is preferable in at least one area of the plate for the transmission coefficients of the optical arrangements to vary progressively, and for the given light distribution in the area to be adapted to compensate this progressive variation to assure an essentially constant level of illumination in the area.
In another aspect, the invention proposes a method of manufacturing a motor vehicle indicating light unit comprising a light source, a curved optical plate having first optical arrangements adapted to redirect light from the region of the source so that it propagates with a mean direction generally parallel to a horizontal optical axis, the first optical arrangements having different light transmission coefficients, and a flux collecting and distributing mechanism disposed between the source and the optical plate and having second optical arrangements adapted to assure a given distribution of light on the inside surface of the optical plate in at least one given direction. The method comprises the steps of:
establishing a law of evolution of the transmission coefficients of the optical arrangements in accordance with at least one of their coordinates on the plate;
establishing a required law of evolution of the illumination of the light unit as a function of the coordinate(s) on the plate;
establishing by combining said laws a relation between the orientation of a ray from the source impinging on the second optical arrangements and the at least one coordinate;
defining the geometry of the second optical arrangements as a function of the relation;
making a mold for the flux recovery and distributor mechanism using the geometry; and
molding the flux recovery and distributor mechanism using the mold.
The definition step advantageously consists of defining a successive plurality of second adjacent optical arrangements in accordance with laws of refraction and/or of total reflection.
The relation is preferably:
s=k
1(
s
)·
k
2(
s
)·&thgr;
where:
s is a curvilinear coordinate of the curved optical plate;
k1(s) is said law of evolution of the illumination;
k2(s) is said law of evolution of the transmission coefficients; and
&thgr; is an angle measured relative to a reference defining the orientation of a ray from the source.
Other aspects, aims and advantages of the present invention will become more apparent on reading the following detailed description of preferred embodiments of the invention given by way of example and with reference to the accompanying drawings.
REFERENCES:
patent: 4899261 (1990-02-01), Blusseau et al.
patent: 5287101 (1994-02-01), Serizawa
patent: 0 193 294 (1986-09-01), None
patent: 2 614 969 (1988-11-01), None
French Search Report dated Aug. 14, 1998 Patent Abstracts of Japan vol. 016, No. 051 (M-1209), Feb. 10, 1992 & JP 03 254004 A (Stanley Electric Co. Ltd), Nov. 13, 1991.
Godbillon Vincent
Montelymard Christian
Cariaso Alan
DelGizzi Ronald E.
Morgan & Finnegan , LLP
Valeo Vision
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