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Researchers Submit Patent Application, "Adaptive Lighting System for an Automobile Vehicle", for Approval

February 20, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Ravier, Jean-Paul (Saint Maur des Fosses, FR); Fleury, Benoist (Vincennes, FR); Boinet, Loic (Le Mesnil Esnard, FR), filed on July 26, 2013, was made available online on February 6, 2014.

No assignee for this patent application has been made.

News editors obtained the following quote from the background information supplied by the inventors: "The present invention concerns an adaptive lighting system for an automotive vehicle, such that the light beam emitted by such a lighting system

"is in compliance at all times with the regulations in force concerning automotive lighting,

"allows the driver of the vehicle to benefit from optimal conditions of visibility,

"does not dazzle other drivers driving on the same road, in the same direction or in the opposite direction.

"Given the large number of vehicles traveling on roads, it is necessary to provide drivers of said vehicles, in particular during night driving, lighting that is as best as possible adapted to the driving conditions in order to reduce the risk of accidents. In particular, it is important that the driver can have optimal vision of the road that stretches out in front of the driver as well as on the shoulders of said road, without, however, dazzling other drivers.

"Currently, all vehicles traveling on the road carry road illuminating equipment, used in case of insufficient visibility, e.g. evening, night-time or during bad weather. Classically, several types of lighting exist on modern automotive vehicles:

"a so-called 'high beam' lighting, produced by means of projectors that emit a light beam directed towards the horizon and that lights up the whole road scene over a long distance of about 200 meters.

"a so-called 'low beam' lighting, produced by means of low beam projectors, or dipped lights, that emit a beam of light delimited by an upper cut-off plane, inclined by about 1% with respect to the horizontal and descending, providing the driver with visibility over a distance on the order of 60 to 80 meters. This upper descending cut-off has the goal of preventing the dazzling of other users in the road scene stretching out in front of the vehicle or on the shoulders of the road.

"a so-called 'fog light', used in case of reduced visibility, produced by means of projectors that emit a short-range beam, on the order of 40 meters, limited upwards by a cut-off plane, very widely spread and comprising no mounting beam likely to give rise to undesirable phenomena with the fog droplets, and to allow the driver to appreciate the immediate environment thereof.

"The aforementioned projector devices, and more particularly those that are used as low beam lights, produce light beams that are perfectible when these projector devices are used in certain conditions. New functions have thus been recently devised, designated as elaborated, merged functions under the name of AFS (abbreviation for 'Advanced Frontlighting System') that proposes notably other types of beams. This is notably

"the so-called BL function (Bending Light for lighting up a bend), that can be decomposed into a so-called DBL function (Dynamic Bending Light for mobile lighting of a bend) and a so-called FBL function (Fixed Bending Light for fixed lighting of a bend). These functions for lighting up of a bend are used in case of traveling in a curved sense and are produced by means of projectors that emit a light beam, the horizontal orientation of which varies while the vehicle moves in a straight trajectory, so as to correctly light up the parts of the road that are destined to be reached by the vehicle and that are not found along the axis of the vehicle, but in the direction that it is on the point of taking, resulting from the angle given to the driving wheels of the vehicle by the driver thereof;

"the so-called Town Light function for lighting in town. This function produces the widening of a low beam type beam while slightly decreasing its range;

"the so-called Motorway Light function for lighting a highway, performing the highway function. This function produces an increase of the range of a low beam by concentrating the light flux of the low beam on the optical axis of the projector device considered;

"the so-called Overhead Light function for gantry lighting. This function produces a modification of a low beam so that signaling gantries situated above the road are lighted in a satisfying manner using the low beam lights;

"a so-called AWL function (Adverse Weather Light for bad weather light). This function produces a modification of a low beam so that the driver of a vehicle traveling in the opposite direction is not dazzled by the light of the projectors reflected off the wet road.

"Moreover, when the low beam is operating, the attitude of the vehicle can undergo more or less significant variations, due e.g. to its state of loading, its acceleration or its deceleration, that induce a variation of the inclination of the upper cut-off of the beam, having the result either of dazzling other drivers if the cut-off is raised too much, or of insufficiently lighting the road if the cut-off is lowered too much. It is then known to use a range corrector, controlled manually or automatically, to correct the orientation of the low beam projectors.

"Apart from road lighting, other types of lighting in which the beam of light is descending only offer reduced visibility at the front of the vehicle for the driver thereof. These types of lighting are often insufficient to allow the driver to see the whole of the road scene in order to be able to anticipate possible obstacles or potentially dangerous situations.

"To ease this inconvenience, projectors have recently been developed that supply light beams providing the driver of the vehicle equipped with these projectors with lighting comparable to that of road lighting, but in which dark zones are created in the directions in which it is not desirable to emit light, e.g. in directions in which vehicles have been detected, so as not to dazzle drivers.

"These light beams, known as 'Matrix Beam' or 'Pixel Lighting' depending upon the technology used, involve complex projector designs, and very fine adjustments in order to obtain the desired result, that is dark zones that are variable in size and in direction.

"On the other hand, a new tendency is to propose a lighting beam in which zones of the road scene containing notable details are lighted with a light intensity greater than that of the surroundings of these details, to attract more specially the attention of the driver of the vehicle to the latter.

"The Applicant has already proposed, in the document EP 1 442 927, a lighting procedure for a road scene by a vehicle projector, comprising the operations:

"detection of at least one person in the road scene,

"localization of the person in the road scene,

"creation, on a display, of a mask of the size and position corresponding to the person,

"lighting of the road scene through the display creating a shadow cast around the person,

"the person being detected by means of thermal detection and/or by a detection of movement, the lighting of the road through the display lighting only a zone of the road scene situated above a cut-off, the lighting of the road below the cut-off being performed by a low beam lighting.

"This process, while being effective, is perfectible, in the sense that the use of a liquid crystal display or a focal lens array display, being able to be modulated by electrical control, poses problems of thermal performance.

"The document WO 99/11968 is also known, concerning a device for lighting an automotive vehicle, comprising an area of electronically controlled micro-mirrors, lighted by a parallel ray light beam. Each micro-mirror can take two positions, an 'active' position in which it reflects light rays towards an optical imaging system, that projects these light rays into the road scene in front of the vehicle, and an 'inactive' position in which it reflects the light rays towards a light absorbing device. The micro-mirror unit modifies the distribution of the light rays to form different light beams. The light losses engendered by such a design are often very significant. Moreover, this device is very cumbersome.

"The document EP 2 063 170 is also known, concerning a lighting device for an automotive vehicle, equipped with a laser source the rays of which are sent by a scanning device onto a surface arranged at the focus of an optical projection system and composed of a plurality of phosphor elements. These phosphor elements re-emit white light that is projected by a lens to form a lighting beam on the road in front of the vehicle. The phosphor segments are arranged between the laser source and the projection lens, at the focus of this lens.

"Such a design presents numerous inconveniences. The fact of using phosphor elements in transmission, that is by illuminating them with a laser beam on one side and recovering the light emitted on the other side involves:

"on the one hand that the thickness of the phosphor must be thin: It results from this that the device presents the danger of a non-negligible possibility that a part of the laser beam directly crosses the thickness of the phosphor, is received by the lens and is therefore projected into the road scene in front of the vehicle. Depending upon the power and emission wavelength of the laser source, this could represent a real danger for the vision of living beings present in the road scene, and cause irreversible burns on their retina,

"on the other hand, that the phosphor is deposited on a transparent material. Normally the phosphor is deposited on polycarbonate or on glass that are known to be poor thermal conductors. But the power of the laser radiation necessary for producing an automotive lighting beam is quite high. Significant heating of the phosphor results from this, and therefore there is a significant decrease of the conversion yield thereof of the laser radiation into white light. On the other hand, the use of transparent substrates mentioned above leads to a decrease in the efficiency of the system due to unavoidable absorption phenomena of the material and to parasitic reflections through these optics. A part of the radiation is then reflected towards the radiation source, hence there is a supplementary loss of efficiency.

"In addition, the partition or the division of the phosphor surface into individual segments engenders a 'pixellization' or a fractioning of the light beam projected onto the road scene, that can degrade the precision required for obtaining an efficient adaptive lighting beam. In fact, the light beam projected to infinity by the lens is only composed of images of the phosphor elements situated in the focal plane of the lens. This light beam, e.g. received by a screen at a distance from the vehicle and perpendicular to the optical axis of the lens, is formed of bright or dark spots depending on whether elements of the phosphor are lighted or not by the laser radiation, the sizes of the spots being proportional to those of the elements of the phosphor.

"Such a design is therefore not suitable for forming a classic, regulation automotive lighting beam or fulfilling an AFS function that must respect the photometric values prescribed in precise parts of this beam.

"In addition, the bulk of a projector according to such a design, according to which the laser source, the scanning device, the segments of the phosphor and the lens are arranged one after the other, is relatively significant and it is not easy to install such a system in an automotive vehicle.

"What is needed, therefore, is an improved adaptive lighting system that overcomes one or more of the problems of the prior art."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "The present invention is in this context and has the objective of proposing an adaptive lighting system for an automotive vehicle, such that the light beam emitted by such a lighting system is simultaneously and at all times:

"in compliance with the regulations in force, and

"adapted to the instantaneous traffic conditions, taking into account: the configuration of the road on which the vehicle is traveling, the traffic parameters on this road, such as the density of traffic, the lighting of the road scene and in general all data external to the vehicle likely to be taken into account, the parameters specific to the vehicle, e.g. the speed of said vehicle, the amount of acceleration or deceleration of said vehicle, the distribution of the load inside this vehicle and in general all data inherent to the vehicle likely to be taken into account,

"to provide the driver of the vehicle with lighting of the road scene that is optimal at all times, that is which provides the driver with the best possible lighting of the road scene given all of the above driving conditions, without disturbing the drivers of other vehicles or pedestrians present in the road scene lit by the adaptive lighting system.

"With this goal, the present invention presents an adaptive lighting system for an automotive vehicle comprising:

"at least one primary light source emitting light radiation,

"a scanning system receiving the light radiation from the primary light source and spatially distributing it onto the surface of a wavelength conversion device,

"the wavelength conversion device receiving the light radiation from the at least one primary source and re-emitting white light radiation,

"an optical imaging system receiving the white light re-emitted by the wavelength conversion device and projecting this light in front of the vehicle to form a lighting beam, the wavelength conversion device being situated close to a focal plane of the optical imaging system,

"the scanning system and the optical imaging system being situated on the same side of the wavelength conversion device.

"According to the invention, the intensity of the white light radiation (B) emitted by the wavelength conversion device (20) is capable of being modulated between a minimum value and a maximum value, and the scanning is performed at variable speed.

"According to other features of the invention considered separately or in combination,

"the scanning is performed along equidistant lines;

"the scanning is performed along lines of variable separation;

"the surface of the wavelength conversion device is composed of phosphor;

"the phosphor is deposited on a substrate that is reflecting for the light radiation:

"the phosphor is deposited on a substrate chosen from good thermally conducting materials;

"the surface of the wavelength conversion device is composed of a continuous and homogeneous layer of phosphor;

"the intensity of the white light radiation emitted by the wavelength conversion device can be continuously modulated between a minimum value and a maximum value;

"the minimum value is zero;

"the scanning system receiving the light radiation from the primary light source is composed of two movable mirrors oscillating around orthogonal axes;

"the scanning system receiving the light radiation from the primary light source is composed of a single micro-mirror movable around two orthogonal axes;

"the scanning system and the primary light source are controlled by a control unit as a function of the desired photometry of the lighting beam;

"the intensity of the light radiation distributed over the surface of the wavelength conversion device by the scanning system is constant;

"the intensity of the light radiation distributed over the surface of the wavelength conversion device by the scanning system is variable between a minimum value and a maximum value;

"the minimum value is zero;

"the system includes at least two primary light sources emitting light radiation, a scanning system being associated with each primary light source to receive the light radiation from the associated primary light source and to distribute it spatially over the surface of the wavelength conversion device;

"the light radiation emitted by the primary light source is laser radiation;

"the laser radiation has a wavelength comprised between 400 nanometers and 500 nanometers;

"the laser radiation has a wavelength close to 450 nanometers or to 460 nanometers.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

"Other goals, features and advantages of the present invention will emerge clearly from the description that will now be given in a non-limiting example of an embodiment with reference to the attached drawings in which:

"FIG. 1 shows schematically the principle of operation of an adaptive lighting system according to the present invention;

"FIG. 2 shows schematically a variant of the principle of operation of an adaptive lighting system according to the present invention;

"FIG. 3 shows schematically a light pattern created on a phosphor lacquer equipping the adaptive lighting system of FIG. 1 or 2;

"FIG. 4 shows schematically the light beam emitted by the adaptive lighting system of FIG. 1 or 2 of which the phosphor plate emits the light pattern of FIG. 3;

"FIGS. 5, 6 and 7 show schematically examples of the scanning of the phosphor plate equipping the adaptive lighting system of FIGS. 1 and 2; and

"FIGS. 8 and 9 show schematically variants of the production of the adaptive lighting system of FIG. 1 or 2."

For additional information on this patent application, see: Ravier, Jean-Paul; Fleury, Benoist; Boinet, Loic. Adaptive Lighting System for an Automobile Vehicle. Filed July 26, 2013 and posted February 6, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4106&p=83&f=G&l=50&d=PG01&S1=20140130.PD.&OS=PD/20140130&RS=PD/20140130

Keywords for this news article include: Patents, Automobiles, Transportation.

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Source: Politics & Government Week


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