Illumination – Supported by vehicle structure
Reexamination Certificate
2000-01-21
2001-08-28
O'Shea, Sandra (Department: 2875)
Illumination
Supported by vehicle structure
C362S512000, C362S539000, C362S282000, C362S293000
Reexamination Certificate
active
06280067
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related in general terms to motor vehicle lighting systems, such lighting systems including at least one running light, that is to say a light (for example a headlight) which is intended to be used at least when the vehicle is traveling.
BACKGROUND OF THE INVENTION
Conventionally, a motor vehicle has to be capable of emitting, selectively, a so-called dipped beam which is generally defined by a cut-off line so as to avoid dazzling the drivers of oncoming vehicles, and a so-called main beam for illuminating the road well ahead of the driver of the vehicle. These functions are provided by means of either one or two pairs of headlights.
The headlights are generally illuminated at night and extinguished in daylight. However, there is today a tendency to regard it as being desirable to have the headlights lit in daylight, not in order to illuminate the driver's field of vision, but rather in order to provide a strong signaling or indicating function, especially for warning pedestrians, but without any inconvenience or detriment to the observer.
This function is commonly referred to as that of a “day running light” or DRL, and is known at the present time in the context of headlights with filament lamps. In order to give the required reduced light intensity to headlight driving beams for use in daylight, such as to make them capable of fulfilling this latter function, it is also known to energise the filament lamps of such headlights at a lower voltage, which is typically only a few volts, than their nominal supply voltage which is usually about 13.5 volts.
In addition, when a headlight is used in daylight driving in its dipped mode, which may involve a reduction in the supply voltage of its filament lamp, then this daylight use becomes added to its night time use. The light is used in the dipped mode far more than in its main beam mode, having regard in particular to the substantial worldwide increase in road traffic. As a result, the lamps (or the filaments in the case of twin function lamps) which provide the dipped beam function will fail much sooner than those lamps or filaments which are dedicated to the main beam function, having regard to their useful life which is, by nature, limited.
In addition, in the case where dipped beam headlights of the elliptical type are used in daylight driving, these headlights being of a kind which is well known as emitting an extremely limited quantity of light above the cut-off line, it is found that the required daylight signaling function is not at all satisfactory. In particular, in full sunlight, an observer who is a few meters or tens of meters in front of the vehicle is in danger of not even being able to see that the headlights are lit at all.
In parallel with the foregoing, we see today development of headlights which no longer have filament lamps, but which are instead equipped with discharge lamps, the latter being well known for their excellent light output for a given consumption of electrical power.
However, it is not possible to operate these headlights in the DRL mode. In this connection, if the supply voltage to the discharge lamp is reduced, then firstly the arc will tend to be subject to unexpected and badly controlled extinction, and secondly the useful life of the lamps is considerably reduced. Moreover, if in order to overcome this limitation it is decided to make use of headlights with discharge lamps with their normal light intensity, it is then found that dipped-beam lights give very imperfect signaling. The latter is too strong below the cut-off line but too weak above it, while at the same time the main beam headlights provide generally excessive intensity which is strongly dazzling even in full daylight.
DISCUSSION OF THE INVENTION
Having regard to the various limitations of the present state of the art discussed above, an object of the present invention is to provide a running light (such as a headlight) which is able to produce both a beam for night driving and a beam for driving in daylight, both of which are satisfactory, the light having a discharge lamp as its light source.
A further object of the invention is to avoid wearing out the lamp too quickly, even though it is used in the dipped beam mode very much more than in the main beam mode.
According to the invention, a motor vehicle headlight, comprising a discharge lamp cooperating with a reflector in order to produce an emitted light beam for night driving which essentially has no cut-off line, is characterised in that the headlight includes a means for selectively diverting a fraction of the light intensity of the beam in such a way as to generate, with the same lamp supplied with power under the same conditions, a reduced beam intensity appropriate to signaling in daylight.
The means for diverting the light is preferably an absorbent element for absorbing some of the light. This absorbent element may for example be a solid attenuating plate; alternatively it may be in the form of an opaque light trap interposed in a part of the emitted light beam, or an opaque plate having at least one through hole to allow the light to pass through. Again, the absorbent element may be in the form of a diaphragm; it may have a multiplicity of small through holes; and/or it may be in grid form, consisting of a grille or grating.
The running light may be of the elliptical type, in which case, according to a preferred feature of the invention, the light further includes a lens having a focus in the vicinity of a light concentration zone in which light is concentrated by the reflector, while the absorbent element is selectively positioned in such a way as to interrupt at least part of the emitted light beam after the latter has been reflected by the reflector.
The absorbent element may have an external contour such that it is interposed over the whole of the emitted light beam after the latter is reflected by the reflector.
The absorbent element may have an external contour such that it is interposed on a predetermined portion of the light beam after the latter has been reflected by the reflector.
The absorbent element may be adapted to be placed selectively in a direction which is essentially transverse with respect to the beam after the latter has been reflected by the reflector, at a distance from the said light concentration zone.
The absorbent element may be adapted to be positioned selectively between the said light concentration zone and an input face of the lens.
The absorbent element may be mounted pivotally in the headlight, for pivoting movement between a working position, in which it is interposed on the emitted light beam, and a retracted position spaced away from the said emitted light beam, being responsive to a controlled drive means.
The running light may have a reflector which itself produces the emitted light beam, while the absorbent element is selectively positioned in such a way as to be interposed on at least part of the emitted light beam between the light source and the reflector.
The absorbent element may be disposed around the light source, being then mounted on a support which is capable of being displaced parallel to an axis of the lamp, the said support being responsive to a controlled drive means.
The light beam for night driving is preferably a main beam.
Further features, objects and advantages of the present invention will appear more clearly on a reading of the following detailed description of some preferred embodiments of the invention, which are given by way of non-limiting example only and with reference to the accompanying drawings.
REFERENCES:
patent: 4684819 (1987-08-01), Haag
patent: 4841199 (1989-06-01), Irie
patent: 5718505 (1998-02-01), Daumueller et al.
patent: 5899559 (1999-05-01), Lachmayer et al.
patent: 0 428 360 (1991-05-01), None
Morgan & Finnegan , LLP
O'Shea Sandra
Valeo Vision
Zeade Bertrand
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