The invention relates to a lighting module for a motor vehicle headlight comprising at least one light source and optical elements for forming at least one light pattern.
Light modules of this type are already known. Such light modules are capable of producing a lighting light beam, for example a high beam, divided into light patterns forming pixels that can be switched off selectively. That makes it possible for example to light the road and its environment optimally while avoiding dazzling the users of the road.
Such light modules are called “pixel beam” light modules. It is for example possible to divide the overall light beam into a matrix of pixels or even into vertical bands.
Some, so-called overlapping, light patterns, that make up the pixel light beam light, for a lower first part, the road in proximity to the vehicle and, for an upper second part, above the road.
When an overlapping light pattern is switched off selectively, a shadow zone is created on the road. This shadow zone is delimited transversely by the vertical edges of the two adjacent overlapping light patterns that are switched on.
However, each overlapping light pattern is delimited by vertical edges which are substantially sharp over all their height. The result thereof is that the lower part of said adjacent overlapping light patterns delimits the shadow zone by boundaries which appear sharply on the road surface. These sharp boundaries draw the attention of the driver thus reducing his or her vigilance, even causing confusion.
The invention proposes a lighting module for a motor vehicle headlight comprising at least one light source and optical elements for forming at least one light pattern, characterized in that each light pattern is divided into an upper portion and a lower portion which are lit simultaneously and inseparably, the upper portion being delimited transversely by two vertical edges for each of which the light intensity decreases according to a first determined gradient and the lower portion being delimited transversely by two vertical edges for each of which the light intensity decreases according to a second determined gradient lower than said first determined gradient.
With the gradient of the vertical edges of the upper portion being higher than the gradient of the vertical edges of the lower portion, said vertical edges will be qualified, in relation to one another, as “sharp”, for those of the upper portion, and as “fuzzy”, for those of the lower portion.
This makes it possible to avoid having the attention of the driver being drawn by the contrast line forming the boundary between the zone of the surface of the road lit by the bottom of the light pattern and the zone of the surface of the road remaining in shadow, while making it possible to light a precise zone on the road and above the road which is delimited by sharp vertical edges. This is particularly useful for pixel beams or segmented beams producing high beam or low beam functions. In a nonlimiting manner, the invention is for example applicable to:
According to other features of the invention:
The invention relates also to a motor vehicle headlight comprising at least one lighting module produced according to the teachings of the invention.
Other features and advantages of the invention will become apparent on reading the following detailed description, for an understanding of which reference will be made to the attached drawings in which:
Hereinafter in the description, the following orientations will be adopted: longitudinal, directed from back to front in the direction of movement of the vehicle, vertical, directed from bottom to top according to an orientation orthogonal to the road, and transverse, directed from a left side to a right side of the road, these being indicated by the trihedron “L, V, T” in the figures. These orientations are also understood when the elements are installed in a lighting device which is itself installed in position of operation on the vehicle.
Hereinafter in the description, elements that have an identical structure or similar functions will be denoted by the same references.
It will be understood that the invention can be applied to light beams fulfilling other functions as has already been explained in the preamble to this description.
For the purposes of the description, a vertical transverse screen 16 has been arranged at a determined longitudinal distance in front of the vehicle 10. The screen 16 is, here, arranged 25 m from the vehicle.
On the screen 16, a transverse axis “H” and a vertical axis “V” have been plotted that intersect at the axis “A” of emission of the pixel light beam 14. The axes “H” and “V” are graduated in degrees of aperture of the light beam. The horizontal axis “H” divides the screen 16 into an upper part and a lower part. The parts of the pixel light beam 14 which light the lower part of the screen 16 are intended to light the surface of the road in front of and in proximity to the vehicle, whereas the parts of the pixel light beam 14 which light the upper part of the screen 16 are intended to light above the road.
In the example represented in
The invention specifically relates to the formation of the light patterns 18 of the lower row which overlap the horizontal axis “H” of the screen 16.
The fourth light pattern 18 starting from the left is switched off selectively to form a shadow zone 20. All the light patterns 18 here overlap the horizontal axis “H”. Each light pattern 18 lights over a field width less than or equal to 20°, for example a field width less than or equal to 15° or to 10°.
At least one of the light patterns 18 is produced by a lighting module 19 of the motor vehicle headlight 12 comprising at least one light source and optical elements. Such a lighting module 19 will be described in more detail hereinbelow. Each light pattern 18 is projected in a fixed direction relative to the motor vehicle.
The headlight 12 mainly comprises a housing (not represented) which is closed by an outer lens (not represented) through which the pixel light beam is projected. The headlight 12 thus encloses at least the lighting module 19.
Since the light patterns 18 are identical, just one of these light patterns 18 will be described with reference to
Each light pattern 18 is divided into an upper portion 18A and a lower portion 18B which are lit simultaneously and inseparably. Thus, it is not possible to light only the upper portion 18A nor is it possible to light only the lower portion 18B. More particularly, the upper portion 18A and the lower portion 18B are delimited by a transverse line which here runs through the optical axis “A” and which corresponds here to the line “H” of the screen. Thus, the upper portion 18A of the light pattern 18 lights above the road, whereas the lower portion 18B lights the surface of the road in front of and in proximity to the vehicle 10, for example between 5 m and 50 m.
The upper portion 18A is delimited transversely by two so-called sharp vertical edges 20A, 20B, for each of which the light intensity decreases according to a first determined gradient “G1”.
The lower portion 18B is delimited transversely by two so-called fuzzy vertical edges 22A, 22B, for each of which the light intensity decreases according to a second determined gradient “G2”, lower than said first determined gradient “G1”.
The terms “fuzzy” and “sharp” are used relatively. Thus, a sharp first edge will be “sharper” than a fuzzy second edge, that is to say that the gradient of intensity of the sharp edge will be greater than that of the fuzzy edge, and, conversely, the fuzzy second edge will be “fuzzier” than the sharp first edge, that is to say that the gradient of intensity of the fuzzy edge will be lesser than that of the sharp edge.
The first determined gradient “G1” of light intensity of the so-called sharp transverse edge 20A has been calculated along a transverse line “L1” running through the axis “H”. The first determined gradient “G1” is, here, equal to approximately 0.35. Generally, the first determined gradient “G1” is greater than 0.13, preferably greater than 0.30. This corresponds to a rapid reduction of the intensity when the vertical edge 20A is crossed along the line “L1”.
The second determined gradient “G2” of light intensity of the so-called fuzzy transverse edge 22A has been calculated along a transverse line “L2” arranged below the axis “H”. The second determined gradient “G2” is, here, equal to approximately 0.11. Generally, the second determined gradient “G2” is less than 0.2, preferably less than 0.13. This corresponds to a slower reduction of the light intensity when the vertical edge 22A is crossed along the line “L2” compared to the reduction of intensity along the line “L1”.
More specifically, in the present application, the gradient is obtained in the manner described hereinbelow.
Along the line “L1” or “L2”, for any point of a segment extending on either side of the lateral edge for which the gradient is to be measured, the following is calculated:
G(α)=log(I(α+0.05°))−log(I(α−0.05°))
in which α is the angle according to the axis “H” of said point of the segment traveled and I is the intensity of the light beam for the angle considered.
The first or second gradient “G1”, “G2” corresponds to the maximum value of G(α) obtained over the segment corresponding to the lateral edge considered.
Thus, when one of the light patterns 18 is switched off, as is illustrated in
In a first embodiment of the light pattern 18 represented in
However, because the lower portion 18B is delimited by so-called fuzzy vertical edges 22A, 22B, it lights a surface that is transversely more extensive than the upper portion 18A.
According to a second embodiment of the light pattern 18, at least one so-called fuzzy vertical edge 22A, 22B of the lower portion 18B is offset transversely relative to the corresponding so-called sharp vertical edge 20A, 20B of the upper portion 18A. In this case, the top end of said offset fuzzy vertical edge 22A, 22B is linked to the bottom end of said sharp vertical edge by a so-called sharp horizontal edge 24A, 24B. The so-called sharp horizontal edge 24A, 24B here coincides with the axis “H” so as not to be perceptible by the driver.
Thus, according to a first variant of this second embodiment illustrated in
According to a second variant of this second embodiment illustrated in
According to a third variant of this second embodiment of the light pattern 18 illustrated in
There now follows a description of a lighting module 19 capable of producing at least some of the light patterns forming the pixel light beam 14, as is represented in
The lighting module 19 is designed to form several transversely aligned light patterns 18. Said light patterns 18 are contiguous, even overlap, transversely, in order to form a pixel light beam 14 lighting uniformly when all the light patterns 18 are switched on.
Each light pattern 18 is capable of being controlled independently to participate in the formation of the pixel light beam 14 producing a determined lighting function, for example a high beam.
The lighting module 19 comprises a primary optical element 26 associated with a plurality of light sources 28, each of which is associated with a light pattern 18.
Each light source 28 is, for example, a light-emitting diode belonging to a matrix of light-emitting diodes. The light sources 28 are, here, aligned transversely.
The primary optical element 26 comprises a plurality of light guides 30 which form a transverse row. Each light guide 30 extends overall longitudinally from a rear input face 32 for the light emitted by an associated light source 28 to a front light output face 34.
In a preferred embodiment, each light guide 30 is associated with one of the light sources 28. According to a variant, each light guide 30 is associated with several of the light sources 28.
The input faces 32 are in one and the same vertical transverse plane parallel to the plane of the light-emitting diodes 28. The output faces 34 are also arranged in one and the same transverse vertical plane. A transverse space is reserved between two adjacent light guides 30 to allow the guiding of the light rays by total internal reflection on the lateral faces of the light guides 30.
Each light guide 30 has a transverse cross section of rectangular form. Each light guide 30 thus has two vertical lateral faces 35 and two top and bottom faces.
The primary optical element 26 also comprises a front lens 36. The front lens 36 is delimited longitudinally to the front by a face 38 for forming the light patterns 18 and to the rear with a transverse vertical face which coincides with the plane of the output faces 34 of the light guides 30.
The front lens 36 is, here, produced materially in a single piece with the light guides 30. Thus, the light guides 30 emerge directly in the front lens 36. The light rays outgoing from the output faces 34 of the light guides are thus propagated without being deflected to the output face 38 of the front lens 36.
The lighting module 19 also comprises a front end projection lens 39, represented in
According to a first embodiment of the lighting module 19, an upper portion of each lateral face 35 of each light guide 30 is linked to the lateral faces 35 of the adjacent light guides 30 via a transverse bridge 40 produced materially and in a single piece with the light guides. Each bridge 40 extends longitudinally from the plane of the input faces 32 to the plane of the output faces 34, here to the front lens 36. Each bridge 40 is arranged transversely coinciding with the upper portion 34B of the output face of the light guides 30. Furthermore, all the bridges 40 are delimited by a bottom face 41 and by a top face 43. The top face 43 is arranged in the same plane as the top faces of the light guides 30. The bottom faces 41 are arranged in a common horizontal plane.
In this configuration, the upper parts of the light guides 30 thus linked by the bridges 40 form a single light forming layer which extends transversely over the entire row of the light guides 30 and which has a single output face 34B extending transversely all along the row of light guides 30. Only a lower part of the lateral faces 35 of the light guides remains free, as is represented in
In the embodiment of
According to a variant of the invention that is not represented, the thickness of the bridges varies as a function of their position along the primary optical element.
To illustrate the operation of the lighting module 19,
As is represented in
As is illustrated in
The forming layer formed by the bridges 40 makes it possible to obtain a light pattern 18 in the form of an inverted “T” as represented in
In a variant of the invention that is not represented, when the horizontal faces of the bridges are fairly wide, in particular wider than what is represented in
In the example represented in
According to a second embodiment of the lighting module 19 which is represented in
The light spreading means are for example formed by diffraction or refraction structures produced in relief on a portion of the output face 38. The diffraction or refraction structures are for example conformed as cushions 44.
This second embodiment makes it possible to obtain light patterns of a form similar to that represented in
As a variant, the spreading means are formed by a graining of the corresponding parts of the output face.
According to another variant, the diffraction or refraction structures are formed by striations, undulations, prisms or any other form suitable for producing the light spreading function.
A third embodiment is also provided, not represented, in which the primary element comprises a structure with light-forming layers, as in the first embodiment, of which the output face comprises light spreading means, as in the second embodiment. The third embodiment of the invention thus combines the features of the first and second embodiments of the invention.
Number | Date | Country | Kind |
---|---|---|---|
17 59636 | Oct 2017 | FR | national |