Illumination – Supported by vehicle structure – Light modifier
Reexamination Certificate
1996-03-29
2001-02-13
Sember, Thomas M. (Department: 2875)
Illumination
Supported by vehicle structure
Light modifier
C362S297000, C362S346000
Reexamination Certificate
active
06186652
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general terms to motor vehicle headlamps, and more particularly to motor vehicle headlamp reflectors and a new method of making such a reflector. The term “headlamp” is used herein in a general sense, for any lamp of the vehicle used to illuminate the road or environment of the vehicle when the vehicle is moving.
BACKGROUND OF THE INVENTION
Reference is made first to a number of prior art patent specifications, in the name of the present Applicant or the Applicant in the French application from which priority is claimed in the present case. Notable among these prior art specifications are those of the French documents FR 2 536 502A, FR 2 536 503A, FR 2 583 139A, FR 2 599 120A, FR 2 599 121A, FR 2 600 024A, FR 2 602 305A, FR 2 602 306A, and FR 2 694 373A.
In the prior art represented variously by the above mentioned documents, a motor vehicle headlamp reflector is known which is capable, by cooperating with a generally cylindrical light source which emits light freely all around it, of generating a beam which is delimited by a straight cut-off line at the top or bottom of the beam. By judicious combination of this kind of surface, it is possible to make reflectors which emit beams satisfying various photometric criteria, and in particular, cruising beams and beams for penetrating fog.
It is also known, especially from the further French specifications (in the name of the same Applicant) FR 2 609 146A, FR 2 609 148A, FR 2 639 888A and FR 2 664 677A, to provide reflectors of a second type. In this second type the surfaces are so designed as to provide, as a general rule, the same type of cut-off, while offering beams which are of substantial width and are highly homogeneous. As a result, it is possible to have recourse to headlamp cover glasses which are smooth or only very slightly striated. Such cover glasses are advantageous, both from the optical point of view and from the aesthetic point of view, because the beam which is produced by the single reflector is able to have all the required qualities.
However, the design of that type of reflector does have certain limitations, and in particular it involves, generally, tackling the question of the width of the beam. Thus, with reflectors of the above mentioned second type, it is extended regions of the reflector that, in general, determine the width of the beam.
DISCUSSION OF THE INVENTION
An object of the present invention is to overcome this limitation, and to enable the design of reflectors giving automatic generation of cut-off, and more generally, the design of any type of reflector for a motor vehicle headlamp, to be made more flexible by enabling predetermined portions of the beam, well localised, to affect beam width without disturbing the remainder of the reflector.
Another object of the present invention is, by taking advantage of this increased flexibility of design, to provide reflectors that are capable of propagating beams which are more comfortable for drivers, and in particular, beams which are more homogeneous and better balanced as regards the factors of beam width and zone of light concentration along the axis of travel or close to that axis.
According to the invention in a first aspect, a method of making a motor vehicle headlamp reflector, is characterised in that it includes the steps consisting of:
(a) establishing a reflective base surface having a reference focus and adapted to give a predetermined distribution of the light emitted by a light source having a given geometry and a given position with respect to the said reference focus, mainly in the vertical direction,
(b) in at least one zone of the reflective surface, determining a line passing through all of the points that give the same predetermined horizontal deviation of a theoretical radiation propagated from the reference focus,
(c) modifying the said reflective base surface so as to put thereon, substantially along the said line, a striation (S) for horizontal diffusion of the light,
(d) making a mould in conformity with the said modified surface, and
(e) moulding the reflector using the said mould.
According to the invention in a second aspect, a method of making a motor vehicle headlamp reflector, is characterised in that it includes the steps consisting of:
(a) establishing a reflective base surface having a reference focus and adapted to give a predetermined distribution of the light emitted by a light source having a given geometry and a given position with respect to the said reference focus, mainly in the vertical direction,
(b) in at least one zone of the reflective surface, determining two lines passing through two sets of points that give, respectively, two horizontal deviations, which are constant and close to each other, of a theoretical radiation propagated from the reference focus,
(c) modifying the said reflective base surface so as to put thereon, in a band delimited by the said two lines, a striation for horizontal diffusion of the light,
(d) making a mould in conformity with the said modified surface, and
(e) moulding the reflector using the said mould.
In either or both of the methods according to the invention defined above, steps (b) and (c) are preferably repeated so as to put a plurality of striations on the reflective surface.
Preferably also, at least some of the striations are adjacent to each other.
According to the invention in a third aspect, a motor vehicle headlamp, of the type comprising a light source having a predetermined geometry, a reflector and a closure glass, is characterised in that the reflector includes at least one striation for the horizontal diffusion of the light, the striation projecting from, or being recessed into, a base surface and extending in a band which is delimited by two lines, with each of these lines, if traced on the said base surface, giving over its whole length an essentially constant horizontal deviation of the light propagated from a reference focus of the said base surface.
Further aspects, objects and advantages of the present invention will appear more clearly on a reading of the following detailed description of preferred embodiments of the invention, which are given by way of non-limiting example only and with reference to the accompanying drawings.
REFERENCES:
patent: 1572853 (1926-02-01), Balsillie
patent: 1621752 (1927-03-01), Raynolds
patent: 2108286 (1938-02-01), Godley
patent: 3511983 (1970-05-01), Dorman
patent: 4351018 (1982-09-01), Fratty
patent: 5577833 (1996-11-01), English et al.
patent: 2 054 815 (1981-02-01), None
French Search Report dated Jan. 19, 1996.
Morgan & Finnegan L.L.P.
Sember Thomas M.
Valeo Vision
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