EP0648968A1 - Vehicle lamp for signalling employing a plurality of light sources and an intermediate optical plate - Google Patents

Abstract

A signalling light for a motor vehicle comprises a plurality of low-power light sources (10), a cover lens (40) arranged in front of the sources and an intermediate optical processing plate (30) arranged between the sources and the cover lens. According to the invention the intermediate plate comprises, on its face pointing towards the sources, ordered arrangements (31) for spreading the light flux and, on its face pointing towards the cover lens, arrangements (32) for concentrating light flux. The invention also provides for optical arrangements with two series of V-shaped grooves oriented transversely to each other so as to define four favoured deflection directions. Application to lights with light-emitting diodes. <IMAGE>

Description

The present invention relates generally to signaling lights for motor vehicles, and in particular to a signaling light for motor vehicle, of the type comprising a plurality of low-power light sources, a closing glass arranged in front of the sources and an intermediate plate comprising optical arrangements and arranged between the sources and the glass so as to obtain a desired photometry beam.

Conventionally, such an intermediate plate makes it possible to carry out optical work that is much more complex than the lens itself, the outer surface of which is imperatively smooth for regulatory reasons.

Thus, it is conventional to provide flux concentration elements such as Fresnel steps on the intermediate plate to the right of each source, and balls or the like for diffusing and spreading the flux on the inner face of the crystal.

Another known solution consists in providing the Fresnel steps on the inner face of the intermediate plate and the balls or the like on its outer face, in which case the glass is smooth on both of its faces.

However, in all cases, provision is first made to ensure a concentration of flux along the optical axis, and only downstream of this concentration, diffusion or spreading of the beam.

The present invention is based on the discovery that effective optical behavior could also be obtained by first spreading or diffusing the beams generated by the sources, then by exposing the spread or scattered flux to a concentration treatment.

Furthermore, a difficulty of signaling lights comprising a large number of low power sources such as light-emitting diodes lies in that that it is difficult to obtain with type of source beams having a strong illumination both in the axis and in a substantially inclined manner with respect to this axis, and in particular rear fog beams. Concretely, the approval of such a beam requires significant levels of illumination both in the axis and in four points corresponding to four directions offset angularly to the left, to the right, above and below the axis.

The present invention also aims to propose an original solution to meet these criteria with a multi-source light such as a light emitting diode light.

Thus, the present invention relates, according to a first aspect, to a signaling light for a motor vehicle, of the type comprising a plurality of low power light sources, a closing glass disposed in front of the sources and an intermediate optical processing plate disposed between the sources and the lens, characterized in that said intermediate plate comprises, on its face facing the sources, arrangements arranged for spreading light flux and on its face facing the lens, arrangements for concentrating light flux.

• lesdits aménagements de concentration de flux lumineux comprennent, au droit de chaque source, un jeu d'échelons de Fresnel focalisés au voisinage de ladite source.
• lesdits aménagements d'étalement de flux lumineux comprennent des éléments à surface sphérique ou des prismes.
• les prismes sont constitués par un réseau de sillons de profil en "V" orientés selon deux directions essentiellement transversales et délimitant des zones non déviatrices à faces parallèles, les sillons définissant quatre directions privilégiées de déviation de la lumière.
• le feu comprend en outre, entre la plaque intermédiaire et les sources lumineuses, une autre plaque intermédiaire dans laquelle sont formés, au droit des sources respectives, des renfoncements réfléchissants de récupération de flux.

Preferred, but not limiting, aspects of the fire according to the invention are as follows:

• said light flux concentration arrangements include, at the level of each source, a set of Fresnel steps focused in the vicinity of said source.
• said light flux spreading arrangements include elements with spherical surfaces or prisms.
• the prisms are formed by a network of grooves in a "V" profile oriented in two essentially transverse directions and delimiting non- deviators with parallel faces, the grooves defining four preferred directions of light deflection.
• the light further comprises, between the intermediate plate and the light sources, another intermediate plate in which are formed, in line with the respective sources, reflective recesses for flux recovery.

According to a second aspect, the invention provides a signaling light for a motor vehicle, of the type comprising a plurality of low-power light sources, and a transparent optical treatment plate disposed in front of the sources, characterized in that said treatment plate optic comprises on its face turned towards the sources prismatic arrangements ordered for spreading light flux constituted by a network of grooves of "V" profile oriented in two essentially transverse directions and delimiting non-deviating zones with parallel faces, the grooves defining four privileged directions of light deflection.

The optical treatment plate is constituted either by an intermediate plate extending between the glass and the sources, or by the fire glass, in which case an intermediate plate is further provided comprising optical arrangements for concentrating flux.

For a rear fog lamp, the grooves extend horizontally and vertically and the four preferred directions of deflection correspond substantially to the directions of four standardized points of approval of the fog beam generated.

In all the embodiments, the light sources preferably consist of light-emitting diodes.

• la figure 1 est une vue schématique en coupe verticale axiale d'une partie d'un feu de signalisation selon une première forme de réalisation de l'invention,
• la figure 2 est une vue en coupe verticale axiale d'une partie d'un élément selon une variante du feu de la figure 1,
• la figure 3 est une vue en coupe d'une partie d'un élément d'un feu selon une autre forme de réalisation de l'invention,
• la figure 4 est une vue en perspective de l'intérieur de l'élément de la figure 3,
• la figure 5 est une vue en coupe verticale axiale d'une partie d'un feu de signalisation équipé de l'élément des figures 3 et 4,
• la figure 6 est une vue en coupe verticale axiale d'une partie d'un feu équipé d'un élément analogue à celui des figures 3 et 4, et
• les figures 7 à 9 illustrent, par des courbes d'éclairement en candélas en fonction de l'angle d'émission, la photométrie de différents feux de signalisation réalisés selon l'invention.

Other aspects, objects and advantages of the present invention will become more apparent on reading the following detailed description of preferred embodiments of this, given by way of nonlimiting example and made with reference to the appended drawings, in which:

• FIG. 1 is a schematic view in axial vertical section of part of a signaling light according to a first embodiment of the invention,
• FIG. 2 is a view in axial vertical section of part of an element according to a variant of the light of FIG. 1,
• FIG. 3 is a sectional view of part of an element of a light according to another embodiment of the invention,
• FIG. 4 is a perspective view of the interior of the element in FIG. 3,
• FIG. 5 is a view in axial vertical section of part of a signaling light fitted with the element of FIGS. 3 and 4,
• FIG. 6 is a view in axial vertical section of part of a light fitted with an element similar to that of FIGS. 3 and 4, and
• Figures 7 to 9 illustrate, by candela illumination curves as a function of the emission angle, the photometry of different signaling lights produced according to the invention.

Referring first to Figure 1, there is shown a signal light which comprises a plurality of low power light sources, in this case light emitting diodes (LED) 10 of the "Brewster" type, comprising a housing 11 , a substantially hemispherical window 12 for light output, and connection lugs 13 for example for the welding of the component 10 on a printed circuit (not shown).

The light also comprises a framework and flow recovery plate 20 comprising, in line with each source 10, a re-entrant cone 21 the bottom of which has a circular opening of diameter substantially equal to that from the window 12 for light output from said source, and opening by another circular opening of larger diameter. The interior walls of the cone are metallized so as to recover the flux emitted in its direction by the LED. The various cones 21 are connected together by flat zones 22 in this case perpendicular to the general direction of light emission, denoted xx.

It will also be observed that the plate 20 makes it possible to obtain a signaling light in which the various sources, constituted by the LED 10, the cone 21 and the associated arrangements of the plate 30, are well individualized, in this case in the form of circles isolated from each other, in the illuminating surface of the lit fire.

The light also includes an optical plate 30 which comprises, at the opening of each cone 21, optical arrangements intended to concentrate and homogenize the light flux coming from the associated LED / cone assembly.

According to one aspect of the present invention, and surprisingly, provision is made for the concentration of flux concentration on the direction xx on the external surface of the plate 30, and for the spreading and homogenization arrangements on its internal surface, the conventional technique being the reverse.

In the present example, the flux concentration arrangements comprise in association with each cone 21 a converging lens with Fresnel rungs 32, concentric with the axis xx and focused in the vicinity of the window 11 of the associated source 10. And the arrangements spreading and homogenization include a series of concave tori 31, opposite the Fresnel steps.

The combination of these arrangements leads to an angular distribution of the flow which has a high value along the axis xx and which varies gradually as one moves away from this axis, this distribution varying of course as a function of the geometric parameters of the arrangements 31 and 32. More precisely, it has been found that by using balls or torus of radii and of steps calculated to generate a maximum deviation of the order of 7 to 30 °, we obtained (as we will see later) a regular rounding of the extremely narrow curve (light in the axis) obtained with a Fresnel lens alone.

In this embodiment, all the optical work being carried out by the optical plate 30, the lens or light for closing the light, designated by 40, is smooth on its two faces.

FIG. 2 illustrates an alternative embodiment of the optical plate 30, in which the arrangements 31 provided on the interior side of the plate 30 consist of convex balls, in particular spherical.

Of course, all kinds of arrangements 31 can be envisaged by those skilled in the art, depending on the photometry to be observed. They may in particular be balls, toroids, prisms, cylindrical or prismatic streaks, etc.

In addition, these arrangements 31 can be provided to ensure a different spreading of the light according to the horizontal (light distribution in azimuth) and according to the vertical (light distribution in elevation).

FIGS. 3 and 4 illustrate particular optical arrangements which, as will be seen below, can be provided either on the preferably internal face of an optical plate 30, or on the internal face of an external indicator 40 ( case illustrated in Figures 3 and 4).

According to this aspect of the invention, the optical arrangements consist of prismatic grooves 41 which separate from one another zones 42 with parallel faces and therefore not deviating. In basic embodiment, the profile of the indicator is the same horizontally and vertically, that is to say that horizontal and vertical grooves of the same profile separate areas with parallel faces 42 of square shape. The grooves 41 are in this case made up of two faces each making an angle denoted A with respect to the normal to the plane of the sight glass (FIG. 3). The width of the grooves is noted L, while the distance which separates them (side of the zones 42) is noted D.

Such optical arrangements are advantageously used in a rear fog light, whose photometric regulations impose minimum lighting to be observed along the optical axis xx, in two directions offset laterally on either side of the axis, and along two other directions shifted up and down on either side of the axis.

Indeed, the prismatic elements constituted by the two faces of each vertical groove define two preferred lateral deflection directions, for an incident radiation close to normal to the light 40, and it is easy to calculate the angle A so that the angle of these deviations corresponds to that of the measurement points of a rear fog beam.

Similarly, the orientation of the faces of the horizontal grooves is calculated so as to create two preferred deviation directions each corresponding to a measurement point vertically offset (above or below) relative to the x-x axis.

Thus, in the case of European standards which provide for two measurement points offset horizontally by + 10 ° and -10 °, respectively, and two other measurement points offset vertically by + 5 ° and -5 °, respectively, two prism angles Av and Ah respectively for the vertical and horizontal grooves, intended to favor the deviation, respectively vertically and horizontally according to the above-mentioned angles.

It is also understood that the ratio between the values of D and of L determines the proportion of the radiation subjected to deflection, and therefore makes it possible to favor the illumination at the measurement points offset at the expense of the measurement point along the x-x axis or vice versa.

Here again, different parameters can be used if necessary for the horizontal grooves (parameters Dh, Lh) and for the vertical grooves (parameters Dv, Lv).

Finally, it should be noted that the "filling" of the beam in the rhombus delimited by the aforementioned measurement points is carried out without having to make any additional arrangements, thanks to surface imperfections of the optical elements and to parasitic reflections.

FIG. 5 illustrates an embodiment of the invention, in which no cone plate 20 is provided, this in order to obtain, still with a series of LEDs 10, a continuous illuminating surface, that is to say say in which the various sources are not individualized.

The light of FIG. 5 is equipped with an indicator 40 as illustrated in FIGS. 3 and 4. Upstream of the indicator, there is provided, in addition to the LEDs 10, an optical plate 30 whose inner face is in the smooth species and the outer face of which comprises Fresnel steps 32, as in the case of FIG. 1.

Thus the LEDs 10 and the associated lenses 32 make it possible to apply to the internal face of the sight glass 40 a radiation relatively concentrated on the axis x-x, and the arrangements 41, 42 of the sight glass fulfill the role described above.

FIG. 6 illustrates another embodiment in which groove arrangements separating zones with parallel faces are provided not on the face inside of the sight glass 40, which is here entirely smooth on its two faces, but on the inside face of the optical plate 30. The grooves are indicated at 33 and delimit zones with parallel faces indicated at 34.

We find in this embodiment the characteristic of the embodiment of FIG. 1, according to which the spreading of the beam is carried out upstream of its concentration.

Figures 7 to 9 illustrate, by curves indicating the illumination obtained (in candela) as a function of the angular difference a (in degrees) laterally with respect to the optical axis xx, the horizontal light distribution obtained with a certain number signal lights designed according to the present invention.

FIG. 7 illustrates in solid lines (curve C1), for reference, the illumination obtained with a light-emitting diode 10 and an optical plate 30 whose inner face is smooth and whose outer face comprises Fresnel steps 32 .

The curve C2 (dashed) shows the distribution obtained with, on the inside face of the plate 30, spherical balls with a pitch of 2.5 mm and a radius of 4.2 mm (i.e. to say ensuring a maximum deviation of approximately 17 °. A good regularity of illumination is observed in a relatively wide range, extending beyond 10 ° on either side of the axis.

FIG. 8 illustrates the results obtained with a set of seventy diodes 10 all equipped with the same optical arrangements.

The curve C3 in solid lines shows the distribution obtained with a light produced according to FIG. 6, with grooves 30 calculated to generate a lateral deviation of ± 10 ° and occupying 44% of the surface of the element 30.

It is observed that the illuminations required at the measurement points at 0 °, + 10 ° and -10 ° are largely satisfied, the minimum illumination requested being represented by the hatched area.

Curve C4 (in dashed lines) illustrates the case where the optical plate 30 has on its outer face Fresnel steps and on its inner face spherical balls with a horizontal pitch of 4 mm, a vertical pitch of 2 , 4 mm and with a radius of 4 mm (embodiment of Figure 2). And curve C5 (in dashed lines) illustrates the case where the plate 30 is provided on its inner face with balls having the same pitch but a radius of 5 mm. The requirements for a rear fog lamp are again met.

Finally, FIG. 9 shows the curves obtained with two diodes equipped with optical arrangements according to FIG. 1 (toroids on the inner face of the optical plate 30).

Curve C6 (in solid lines) corresponds to tori with a horizontal pitch of 4 mm, a vertical pitch of 2.4 mm and a radius of 5 mm, while curve C7 (in dashed lines) corresponds to the case where the toroids have the same steps but a radius of 4 mm.

It is also observed in the case of FIGS. 8 and 9 that the angular distribution of the beam in the horizontal direction is very regular.

Of course, the present invention is not limited to the embodiments described and shown, but those skilled in the art will be able to make any variant or modification in accordance with his spirit.

Claims (8)

Signaling light for a motor vehicle, of the type comprising a plurality of light sources (10) of low power, a closing glass (40) disposed in front of the sources and an intermediate plate (30) for optical treatment disposed between the sources and the lens, characterized in that said intermediate plate comprises, on its face facing the sources, arranged arrangements (31; 33, 34) for spreading light flux and on its face facing the lens, arrangements (32) for concentrating flux luminous. Light according to claim 1, characterized in that said light flux concentration arrangements comprise, in line with each source (10), a set of Fresnel steps (32) focused in the vicinity of said source. Light according to claim 1 or 2, characterized in that said light flux spreading arrangements comprise elements with a spherical surface (31). Light according to claim 1 or 2, characterized in that said light flux spreading arrangements comprise prisms (33). Light according to claim 4, characterized in that the prisms are constituted by a network of grooves of "V" profile (33) oriented in two essentially transverse directions and delimiting non-deviating zones with parallel faces (34), the grooves defining four privileged directions of light deflection. Light according to claim 5, characterized in that it constitutes a rear fog light, in that the grooves (33) extend horizontally and vertically and in that the four preferred directions of deflection correspond substantially to the directions of four standard points of approval of the generated fog beam. Light according to one of claims 1 to 6, characterized in that it further comprises, between the intermediate plate (30) and the light sources, another intermediate plate (20) in which are formed, in line with the respective sources , reflective recesses (21) for flow recovery. Light according to one of the preceding claims, characterized in that the light sources (10) consist of light-emitting diodes.

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