FR3055979A1 - CHARACTERISTICS OF PIXELISE LIGHT BEAM - Google Patents

Abstract

The invention relates in particular to a light device (7) of a motor vehicle (1) comprising a pixelated light source and an optical system arranged to project a pixelated light beam (10) emitted by the pixelated light source, the projection of the light beam pixelated on the road including an image (9) having a contrast between 1.5 and 4, a resolution between 0.025 ° and 0.75 °, and / or a sharpness between 0.075 ° and 0.2. The invention provides a projection of a pixelated light beam by an illuminated device of an improved motor vehicle.

Description

FIELD OF THE INVENTION

The invention relates to the field of projection of a pixelated light beam by a light device of a motor vehicle.

BACKGROUND

The projection of a light beam by a motor vehicle light device conventionally makes it possible to illuminate the road with global lighting and thus to increase visibility in the event of darkness, for example at night. This allows safe driving of the vehicle.

Recent developments in the field of these light devices make it possible to produce a pixelated light beam to achieve this lighting. With such a light beam, the light device can also perform localized lighting functions, for example projecting a pattern onto the scene. Such functions are known in the field of adaptive lighting. For example, glare-free lighting is known, consisting for example of darkening an area corresponding to a vehicle coming from the front so as not to dazzle this other user. There are also known lighting aids driving, for example consisting in over-intensifying the markings on the ground or road signs so that they are more visible to the driver and / or projecting onto the road one or more pieces of information visible to the driver. .

In this context, there is a need to improve the projection of a pixelated light beam by a light device of a motor vehicle.

SUMMARY OF THE INVENTION

For this, a method of projecting a pixelated light beam by a motor vehicle light device is proposed, as well as a motor vehicle light device configured to execute the method.

The light device comprises a pixelated light source and an optical system arranged for the projection of a pixelated light beam emitted by the pixelated light source. The projection of the pixelated light beam on the road includes an image. The image has a contrast between 1.5 and 4, a resolution between 0.025 ° and 0.75 °, and / or a sharpness between 0.075 ° and 0.2 °. The light device is therefore able to project onto the road an image which has any combination of at least one of these characteristics.

Such a device improves the projection of a pixelated light beam by a light device of a motor vehicle.

The device is part of the technologies for projecting a pixelated light beam. Such a light beam allows, thanks to its pixelated character, to project one or more patterns when desired.

An image projected onto the road contains a pattern visible to the naked eye, for example intended for the driver and / or other users. An image can thus be used to transmit information to the person who sees the image. This information can be driving assistance information, for example intended for the driver. An image thus improves comfort and / or security.

The light device makes it possible to project an image of particularly good quality. Indeed, the contrast, resolution and / or sharpness properties respected by the light device allow good visibility of the image in a road context. The light device can thus transmit detailed and precise information efficiently, which further improves comfort and / or safety.

According to different embodiments, any combination of at least one of the following characteristics can be implemented:

the contrast of the image is substantially constant;

the pixelated light beam projects on at least part of the road an overall lighting corresponding to an increasing light intensity as a function of the distance from the light device, the image corresponding to a multiplication of the light intensity corresponding to the lighting global by a predetermined constant; the predetermined constant is between 2.5 and 5;

the pixelated light beam darkens a pattern outline of the image;

the sharpness has a decreasing value as a function of the distance of the image from the light device;

the sharpness is between 0.075 ° and 0.125 ° when the distance of the image from the light device is of the order of 50 meters; the sharpness is between 0.15 ° and 0.2 ° when the distance of the image from the light device is of the order of 10 meters; the light source is formed by a matrix of individual light sources which extend in the same plane; and / or the individual light sources each have a size of 40 micrometers for a focal length of 45 millimeters and a resolution of 0.05 °.

The method can comprise the projection onto the road of one or more such image (s), for example at one or more instant (s).

A computer program is also provided which includes program code instructions for executing the method. The method is executed when the program is executed by a projection control unit on a scene of a pixelated light beam by a land vehicle light device as above comprising the control unit coupled to the light source

Such a control unit is also proposed. The control unit includes a processor associated with a memory that has saved the program.

BRIEF DESCRIPTION OF THE FIGURES

Different embodiments of the invention will now be described, by way of non-limiting examples, with reference to the appended drawings in which:

FIGs 1-4 illustrate examples of image properties obtained by the light device;

FIG. 5 shows a schematic example of a light module comprising a pixelated light source;

FIG. 6 shows a schematic example of a light device used to produce a pixelated light beam; and

FIG. 7 shows a schematic example of the projection of a pixelated light beam by a vehicle.

DETAILED DESCRIPTION

The motor vehicle can be any type of land vehicle, for example an automobile (car), a motorcycle, or a truck. The vehicle can be equipped with one or more front headlamp (s) and / or one or more rear headlamp (s). One or more of the front and / or rear headlights may each include one or more light device (s) each configured to project a pixelated light beam. The projection of a pixelated light beam is of particular interest when carried out by a front headlight light device.

For a given light device, the projection can be done on a stage. The scene or "road scene" is the environment of the vehicle capable of being illuminated by the light device.

The light device can perform a global lighting function on at least part of the stage. The part of the scene thus lit by the overall lighting can correspond to a driving field of vision, made visible or more visible to the driver in order to facilitate or allow him to drive. The overall lighting can thus be, for example, a high beam function or a low beam function. The global lighting can be regulatory, that is to say it can meet a national or community regulation setting a photometric grid to be respected. The regulation can for example be the regulation ECE R98, R112, R113 or R123.

The overall lighting can correspond to a distribution of light intensity values on the source of the pixelated light beam corresponding to a globally regular distribution of lighting reference values on the scene. This is called “nominal” light intensity and “nominal” lighting values. These nominal light intensity values can in known manner vary according to a set of one or more parameters global to the driving environment. When the light device performs only the overall lighting function and performs it perfectly, the illumination is such that the nominal light intensity values are effectively distributed (the nominal value being zero for a part of the scene that is not lit). The global lighting can be achieved by the pixelated light beam and / or by another light beam.

A pixelated light beam is in known manner a light beam subdivided into elementary light sub-beams called "pixels". The subdivision can be any, for example forming a grid having a dimension in azimuth and a dimension in depth (or distance) relative to the position of the vehicle. Each pixel is individually controllable by the light device to a extent allowing at least one pattern to be projected onto the scene. A pattern is a localized area of the scene for which the value of the light intensity deviates from the nominal value and creates a localized contrast in the scene. A pattern can be distinguished or not distinguishable with the naked eye. The light device can thus control the projection of one or more motif (s) at one or more instant (s) and / or at one or more location (s) on the scene. The light device can for example alternate between phases where only the global lighting function is performed and phases where a pattern is projected in addition to the global lighting function.

Each pixel of the pixelated light beam is projected onto a corresponding area of the scene, also called a “pixel”. The light device can individually control the light intensity of the source of each pixel of the pixelated light beam, thereby individually controlling the illumination of each pixel in the scene. The light device can divide the scene into more than 10 pixels, more than 50 pixels, or, for a projection implementing advanced functions, more than 500 pixels (for example of the order of 1000 pixels or more than 1000 pixels). The pixelated light beam can for example darken one or more groups of one or more pixels, and / or over-illuminate one or more groups of one or more pixels with respect to a current light intensity value, for example the nominal value. A pixel darkening is a decrease at a given instant in the illumination in the pixel. It should therefore be noted that the darkening of a pixel does not necessarily imply stopping the lighting of the pixel. A pixel over-illumination is an increase at a given moment in the illumination in the pixel. The contrast of the pattern with respect to its periphery can therefore be positive or negative. The resolution of a pattern can be of the order of a pixel. The size of the pattern can be less than 25% or 10% of the total pixels of the scene.

The size of the pattern can be equal to or greater than one pixel. For a given pattern projected at a given time, one or more pixels of the scene - or equivalent of the light beam - correspond to the pattern. A distribution of one or more light intensity (s) respective to the pattern is thus associated with each pixel and forms the pattern. A method can therefore project the pattern into an area of the scene by providing the light device with a light intensity instruction which corresponds to the pattern, for each pixel concerned in the scene. The light intensity setpoint can be any data structure relating to the light intensity, for example a light intensity value to be applied for the center of the pixel, a spatial and / or temporal distribution of values to be applied for the same pixel. , and / or data indirectly linked to the light intensity and which can be translated into light intensity (such as, for example, data relating to the illumination in the pixel). When the set point is respected for all the pixels corresponding to the pattern, the pattern is fully projected onto the scene. Several patterns can be projected simultaneously, with or without spatial overlap. The case of spatial overlap can be handled anyway. For example, one pattern can take precedence over another. Alternatively, the light device can be configured to find a compromise in the illuminations to be applied to a pixel included in the overlap.

Projecting the pattern can improve a driving situation. A driving situation can correspond to a set of driving parameters, for example including environmental and / or architectural parameters relating to the road, system parameters of the vehicle and / or other vehicles, and / or parameters relating to the road condition. The improvement may consist of a projection of the pattern increasing the comfort and / or helping the driver of the vehicle projecting the pattern and / or other users (for example another driver of one or more other vehicle (s) and / or one or more pedestrians). Projecting the pattern can accomplish this improvement by performing one or more of the following functions: an information projection function created for the driver and / or other users, a highlighting or highlighting function of object (s) in the scene, and / or a function of not dazzling any person (for example of one or more other users). Such a pattern makes it easier to drive and / or increases safety, from the point of view of the transmitting vehicle and / or other vehicles in circulation at the time when the pattern is projected.

A pattern can have the function of avoiding the glare of another user or of the driver by darkening an area of the scene corresponding to this other user and / or to a reflective panel. Thanks to this, the light device can for example operate continuously in high beam, the light device ensuring darkening as soon as another vehicle comes from the front. This ensures high driving comfort and visibility and therefore increases safety.

A pattern can form an image projected on the ground, for example on the road. An image is a pattern that is visible, that is to say, distinguishable, for example by the driver and / or other users. The image can have one or more of the following functions: over-intensify ground markings (for example lines and / or arrows, for example by over-illumination so as to allow their contrast and therefore their visibility to be increased ); highlight a side of the road taken by the vehicle; create a representation bounding the route (for example when a marking is absent); create a marking corresponding to the size of the vehicle (which makes it possible to identify the trajectory of the vehicle - by possibly integrating the steering wheel angle - thus forming an equivalent at the front of the reversing cameras); and / or display one or more pieces of information of any type offering assistance to the driver (for example concerning safety, dangers, or even data related to driving, such as speed or direction).

The pattern can correspond, for example, to a localized area that is more lit than the rest of the scene around, and / or to a localized area that is less lit than the rest of the scene around or not at all lit. If the localized area is on the road itself, the pattern can correspond to a localized lit area. This allows the driver to continue to see the road even in the area and thus maintains driving safety. If the motif is for the attention of the driver of the vehicle, the motif may correspond to a localized area which is more illuminated than the rest of the scene. This allows greater visibility for the driver. Also, an outline of the pattern can be darkened. This further increases the contrast and therefore the visibility of the pattern. The pattern can for example form an image projected on the road for the attention of the driver of the vehicle. In this case, a positive contrast of the pattern with respect to its periphery allows a particularly good visualization. In another example, the pattern may correspond to another vehicle (automobile or not), for example coming from the front. In this case, the pattern can correspond to the location occupied by this other vehicle in the scene. Darkening implying a negative contrast of the pattern with respect to its circumference makes it possible not to dazzle this other user and thus to secure the road. Similarly, the pattern may correspond to the location occupied by a panel or other reflecting object. A darkening of this panel avoids reflections and therefore the glare of the driver and / or other users.

The device can be configured to be able to understand the projection of an image containing information intended for the driver in an image projection zone located on the ground at a distance from the vehicle of the order of ten meters. The image projection area can for example be in front of the vehicle. This area is particularly well suited for image projection, in particular for image projection containing driving assistance information, because it is particularly visible to the driver while allowing him to continue to see the road.

The illumination of the image projection area can be constant and / or strictly less than a regulatory limit, for example between 20 lux and 50 lux, for example of the order of 30 lux. This makes it possible to display an image containing information for the driver by over-illumination in relation to a light background that is less lit (but still lit, so as to ensure good safety), that is to say by positive contrast, while respecting the regulatory limit and therefore avoiding dazzling the driver or other users. The illumination of the image can be between 30 lux and 150 lux. The levels of illumination mentioned make it possible to distinguish the information projected on a light background.

A pixelated light beam can be projected by a light device comprising a pixelated light source. The light source may be able to cooperate with an optical system (integrated into the device or not) arranged to project onto the road a pixelated light beam emitted by the pixelated light source. The method may include projecting the pixelated light beam with such a light device. The same pixelated light source can emit the overall lighting and the image. A pixelated light source is a light source divided into several units of individually controllable light sources. Each pixel emitted by the pixelated light source, and therefore each light source unit, can correspond to one pixel of the projected pixelized light beam. Thus, the light intensity of each pixel of the pixelated light source and therefore the illumination of each pixel of the scene can be controlled individually. The pixelated light source can have more than 1000 pixels. The light device can thus project patterns in high resolution.

The pixelated light source may include a matrix of light source units. The matrix can include a multitude of pixels in a plane. In the case of a light source comprising a matrix of pixels and cooperating with an optical system, the optical system may have a focusing area coincident with the plane of the pixel matrix, that is to say coincident with the pixelated light source.

The pixelated light source can be of the DMD (English acronym for “Digital Mirror Device”) type where the rotation modulation of micro-mirrors makes it possible to obtain a desired light intensity in a given direction. The pixelated light source can be of the LCD type (acronym for “Liquid Crystal Displays”) comprising a surface light source in front of which liquid crystals are placed. The movement of liquid crystals can allow or prohibit the passage of light and thus form a pixelated light beam. The pixelated light source can be of the laser type sending a beam of light rays to a scanning system which distributes it over the surface of a wavelength conversion device, such as a plate comprising a phosphor.

The pixelated light source can be an electroluminescent source. An electroluminescent source is a solid-state light source which comprises at least one electroluminescent element. Examples of the light emitting element include the light emitting diode (LED), the organic light emitting diode (OLED), or the polymeric light emitting diode or PLED (English acronym for "Polymer Light-Emitting Diode"). The pixelated light source can be a semiconductor light source. Each electroluminescent element or group of electroluminescent elements can form a pixel and can emit light when its or their material is supplied with electricity. The electroluminescent elements may each be semiconductor, that is to say that they each comprise at least one semiconductor material. The light-emitting elements can be predominantly made of semiconductor material. We can therefore speak of a light pixel when an electroluminescent element or group of electroluminescent elements forming a pixel of the pixelated light source emits light. The electroluminescent elements can be located on the same substrate, for example deposited on the substrate or obtained by growth and extend from the substrate. The substrate can be predominantly made of semiconductor material. The substrate may include one or more other materials, for example non-semiconductors.

The pixelated light source may be a monolithic semiconductor electroluminescent. The source can for example be a monolithic matrix of pixels. The light source can for example be a monolithic array of LEDs (translation of the English term "monolithic array of LEDs"). A monolithic matrix comprises at least 50 electroluminescent elements located on the same substrate (for example on the same face of the substrate), for example more than 100, 1000 or thousands. The substrate may include sapphire and / or silicon. The pixels of the monolithic matrix can be separated from each other by lines (called “lanes” in English) or streets (called “streets” in English). The monolithic matrix can therefore form a grid of pixels. A monolithic source is a source with a high density of pixels. The pixel density can be greater than or equal to 400 pixels per square centimeter (cm ² ). In other words, the distance between the center of a first pixel and the center of a second pixel near the first may be equal to or less than 500 micrometers (pm). This distance is also called "pixel pitch" in English.

In a first configuration, corresponding in particular to the case of a monolithic matrix of LEDs, each of the electroluminescent elements of the matrix may be electrically independent of the others and may or may not emit light independently of the other elements of the matrix. Each electroluminescent element can thus form a pixel. Such a light source achieves a relatively simple high resolution.

In a second configuration, the electroluminescent elements have a general form of "rods", for example of submillimetric dimensions. The rods can each extend orthogonally to the substrate, have a generally cylindrical shape, in particular of polygonal section, have a diameter between 0.5 pm and 2.0 pm, preferably 1 pm, have a height between 1 pm and 10 pm, preferably 8 pm , and / or have a luminance of at least 60 Cd / mm ² , preferably at least 80 Cd / mm ² . The distance between two immediately adjacent rods can be between 3 μm and 10 μm and / or constant or variable. The rods can be arranged to emit light rays along the rod (that is to say along a direction perpendicular to a majority plane of extension of the substrate) and at the end thereof. The semiconductor material may include silicon. The electroluminescent elements are distributed in different light emission zones which can be activated selectively, each pixel thus being formed by a zone which can be activated selectively. Such a pixelated light source has advantages of size and lifespan, and of achieving very high resolutions.

The pixelated light source can be coupled to a light emission control unit of the pixelated light source. The control unit can thus control (control) the generation (for example the emission) and / or the projection of a pixelated light beam by the light device. The control unit can be integrated into the lighting device. The control unit can be mounted on the light source, the assembly thus forming a light module. The control unit can comprise a processor (or CPU acronym from the English “Central Processing Unit”, literally “central processing unit”) which is coupled with a memory on which is stored a computer program which comprises instructions allowing the processor to perform steps generating signals allowing the control of the light source so as to execute the method. The control unit can thus for example individually control the light emission of each pixel of a pixelated light source.

The control unit can form an electronic device capable of controlling electroluminescent elements. The control unit can be an integrated circuit. An integrated circuit, also called an electronic chip, is an electronic component reproducing one or more electronic functions and can integrate several types of basic electronic components, for example in a reduced volume (i.e. on a small plate). This makes the circuit easy to implement. The integrated circuit can for example be an ASIC or an ASSP. An ASIC (acronym for "Application-Specific Integrated Circuit") is an integrated circuit developed for at least one specific application (that is to say for a client). An ASIC is therefore a specialized integrated circuit (micro-electronics). In general, it brings together a large number of unique or tailor-made functionalities. An ASSP (acronym for “Application Specifies Standard Product”) is an integrated electronic circuit (microelectronics) grouping together a large number of functions to satisfy a generally standardized application. An ASIC is designed for a more specific (specific) need than an ASSP. The supply of electricity to the electroluminescent source, and therefore to the electroluminescent elements is carried out via the electronic device, itself supplied with electricity using for example using at least one connector connecting it to a source of electricity. The electronic device then supplies the electroluminescent elements with electricity. The electronic device is thus able to control the electroluminescent elements.

The properties of an image projected on the road which can be ensured by the configuration of the light device so as to improve the visibility of the image are now discussed. The image has one or more of the properties discussed, for example all of these properties. The image can be projected in a projection area located anywhere on the road, for example in an area between 3 and 15 meters in front of the vehicle. The configuration of the light device, however, also allows it to project onto the road at 50 meters a relatively sharp image therefore visible and / or at sufficient resolution to carry details.

The image may have a contrast between 1.5 and 4.

The contrast corresponds to the following formula:

(LMAX-LMIN) / LMIN where LMAX corresponds to the maximum luminance in the image and LMIN corresponds to the minimum luminance in the image. LMAX can correspond to the luminance of the motif of the image (respectively of the periphery of the motif) and LMIN can correspond to the luminance of the periphery of the motif (respectively of the motif of the image). We speak of positive contrast when LMAX corresponds to the luminance of the pattern of the image, which is therefore more illuminated than its periphery and thus made particularly visible.

The contrast can be adapted to the function of the image. For example, the contrast can be above a predetermined threshold when the image aims to over-intensify an existing degraded marking (because it is too old or tainted by tire marks) or to create help information. driving, in particular textual and / or symbolic information. Observations have shown that the image becomes particularly visible and effective when the contrast of the image in the scene reaches a value greater than 1.5 or 2 and / or less than 4. In particular, in the case of a contrast positive, the level of light intensity corresponding to the interior of the image (and therefore of ground illumination) can be 2.5 times to 5 times higher than the level of light intensity (and therefore of ground illumination) ) corresponding to the outside of the image. Negative contrast may also apply.

The image contrast can be constant. Constant contrast of the image means that the contrast experiences substantially no local variations along the contours of the image pattern. This allows good visual comfort, the visibility of the image being uniform. The light intensity corresponding to the outside of the image may vary. Thus, the light intensity corresponding to the interior of the pattern of the image can itself vary, to ensure a locally constant contrast at the contours of the pattern.

In particular, the pixelated light beam can project onto at least part of the road an overall illumination corresponding to an increasing light intensity as a function of the distance from the light device. This part of the road can be the area beyond 15 meters. An area between 3 and 15 meters can correspond to a constant light intensity, to form a light background allowing the image to be clearly distinguished according to the principles explained above. With the exception of such zones corresponding to a constant light intensity, even in the absence of an image, the light intensity produced by the light device can vary spatially. Indeed, the illumination on the ground of a local area decreases as a function of the distance from the light device according to the law: E = I / cf, where E is the illumination of the local area, I the Light intensity the part of the source of the pixelated light beam corresponding to the local area, and d the distance from the light device in the local area. The light device can then increase the intensity in directions that hit the ground at distances that go away. This principle is illustrated by FIG. 1 which shows the application of the above formula for two local areas 201 and 202 different from route 203. This makes it possible to have a substantially constant illumination or which does not decrease too much as a function of the distance.

In the presence of an image, this principle can remain valid. Therefore, the image can be formed simply by multiplying the light intensity corresponding to the overall scaling (that is to say, the nominal light intensity value) by a predetermined constant. The result of (a multiplication can be achieved by any means. For example, the control unit applies a filter consisting in effectively calculating the multiplication. The predetermined constant can correspond to the desired contrast. The predetermined constant can for example be between 2 , 5 to 5 to ensure a contrast between 1.5 and 4.

FIG. 2 shows this principle with a contrast of 4 for an Image 205 displaying an arrow pattern 207 projected on the route 203, The figure also represents the depth profile (or “vertical”) of light intensity 220, corresponding to the axis 225, and the transverse (or “horizontal”) profile 210 of light intensity, corresponding to the axis 215. It can be seen in the figure that the vertical profile of light intensity 220 can be modified but while retaining the increase in Intensity to maintain a lighting on the ground which does not decrease too much. It is then noted that the image 205 obtained visually retains a constant contrast. By multiplying the Luminous Intensity by a constant value, the luminous device thus ensures in a simple way a uniform contrast on the whole of the image and sufficient to make the Image visible by the driver without however bringing discomfort.

In the presence of a positive contrast, the light device can darken an outline 208 of the image pattern. This makes the pattern even more visible. To achieve darkening, the light device can limit the levels of lighting in areas adjacent to the pattern, for example by having a low level of lighting in the field, or by having a variable level of lighting which decreases progressively until the image (for example progressive enough not to create a lack of homogeneity). This is illustrated in FIG. 3 which shows a horizontal intensity profile 212 different from the profile 210 of FIG. 2 in that a darkening corresponding to a drop in localized light intensity 209 is carried out for the areas near the contours 208 of the pattern of the image.

The image may have a resolution between 0.025 ° and 0.75 °.

The resolution can be defined as the distance between the centers of two contiguous pixels, horizontal and / or vertical. A resolution between 0.025 ° to 0.75 ° allows a fine and / or detailed image. This allows for example the display of an image of size equal to 1/5 of the width of the road at 50 meters from the light device. The light device is therefore suitable for projecting a visible image at 50 meters.

The projected image is produced by projecting pixels. To make the image visible, each pixel center can be distant by an angular distance of between 0.025 ° and 0.75 °, for example 0.05 °. The spatial frequency thus obtained is sufficient for details on the ground to be sufficiently visible to the driver. An image (for example the image 205 of the arrow in FIG. 2) can have a characteristic angular size of the order of 0.5 °. 100 pixels (10 x 10) are then used to project the image.

The image may have a sharpness between 0.075 ° and 0.2 °, for example greater than 0.075 ° or 0.1 ° and / or less than 0.15 ° or 0.2 °.

The sharpness corresponds to the angular spacing, in a variation of intensity corresponding to a segment of an image, between the point at 10% of the variation and the point at 90% of the variation. In other words, the sharpness can be described by the angular deviation which characterizes a variation of intensity between 10% and 90% of the total variation. FIG. 4 illustrates this difference 402 for a light intensity profile 410.

Sharpness between 0.075 ° and 0.2 ° allows good visibility of the image while ensuring good homogeneity of the lighting. Pixels may not be visible. The image remains visible and the pattern shown remains recognizable.

The sharpness can have a decreasing value depending on the distance of the image from the light device. The value can be decreasing as a function of the overall distance of the image from the light device. Within an image, the sharpness can be substantially fixed, or again decreasing as a function of the distance from the light device.

The sharpness can depend on the field of vision and more particularly on the projection distance of the image. When the image is projected at 50 meters, the sharpness can be between 0.075 ° and 0.125 °, for example of the order of 0.1 °. With an image at 10 meters, the sharpness can be content to be between 0.15 ° and 0.2 °. Profile 410 of FIG. 4 is therefore well suited for a distance of the image even high, for example even greater than 10 meters or of the order of 25 meters.

The light device can achieve such image properties, for example with a pixelated light source taking the form of a monolithic electroluminescent source, for example a monolithic matrix of pixels.

The pixelated source can be of suitable size. The size of the light source can be linked to the required field of vision. The light source can be divided into a multitude of pixels which can light up individually. The pixelated light source can then be placed in the focus of an optical system. When a pixel lights up, the associated beam area lights up.

The expected resolution can therefore be related to the size of each pixel. For a focal length of the optical system of 45mm, and for a resolution of 0.05 °, the pixels can each have a size of the order of 40 micrometers (pm).

The intensity distribution (and in particular the contrast of the image) can be ensured by controlling the luminance emitted by the pixel. This same luminance can itself be determined by the average current density which crosses the pixel, for example by variation of the peak current density, or by variation of the on / off ratio of pulse width modulation PWM ("Puise Width Modulation ”or PWM in English).

The sharpness can be determined by combining the sharpness of the source itself (luminance profile) and that of the optical system.

The optical system can be optimized so as to adjust the sharpness of the images projected at a short distance, for example at a distance of the order of 10 meters (between 4 and 10 °) and those projected at 50 meters (approximately 1 °).

Examples of the method and of the light device are now discussed with reference to the figures.

FIG. 5 shows a schematic example of a light module comprising a pixelated light source. The light device can include such a light module. The light module 100 comprises the high density monolithic electroluminescent source 120, a printed circuit or PCB 140 (from the English “Printed Circuit Board”) which supports the source 120 and a control unit 190 which controls the electroluminescent elements of the source luminous monolithic 120. Any support other than a PCB can be envisaged. The control unit 190 can be at any other location, even outside the light module 100. The control unit 190 is represented in the form of an ASIC, but other types of control unit can implement the functions of the light module.

FIG. 6 shows a schematic example of a light device used to produce a pixelated light beam. The light device 200 comprises a pixelated light source 12. The light source 12 is in the form of a matrix of pixelated light sources. This matrix includes a multitude of pixels P located in a plane n which extends in two directions (y, z). The pixels P can have different sizes or the same size. The pixels P can be aligned horizontally along the y axis and / or vertically along the z axis. In this example, a first group of pixels G1 of the matrix is intended to project global lighting and a second group of pixels G2 is intended to form a pattern, an arrow in the example, for example to indicate a turn to the driver. Each pixel P can be controlled individually, consequently the light intensity and the illumination can be controlled in all or nothing or in a linear fashion. The light source 12 is associated with an optical system 14 for projecting light onto the stage. The optical system 14 has a focal area coincident with the π plane of the pixel matrix.

FIG. 7 shows a schematic example of projection of a pixelated light beam by a vehicle, seen in perspective. The motor vehicle 1 is provided with two projectors 4, one or each of which may include at least one light device 7 configured to each project a pixelated light beam 10 onto a scene 5 located in front of the vehicle 1. The pixelated light beam 10 is in the example configured to form a global lighting 6. The global lighting 6 can be regulatory. The pixelated light beam 10 is also configured to form the pattern 9. The illumination of the pattern 9 is also regulatory. In the example, it is higher than the illumination of the first portion 9 around it, which makes it visible by positive contrast. The motif 9 is in the example an image containing textual and symbolic information for driving assistance. Image 9 relates in particular to the speed of the vehicle. The light device 7 can alternatively project signaling information or even guidance information for the driver of the vehicle 1. The device 7 can also in other examples project all kinds of patterns, project patterns outside the first portion 6, and / or project patterns by negative contrast. In other examples, the overall lighting may not be shared in this way.

Claims (14)

1. Light device (7) of a motor vehicle (1) comprising a pixelated light source (12, 120) and an optical system (14) arranged to project a pixelated light beam (10) emitted by the pixelated light source, the projection of the pixelated light beam on the road (203) including an image (9, 205) having a contrast between 1.5 and 4, a resolution between 0.025 ° and 0.75 °, and / or a sharpness between 0.075 ° and 0.2 °. 2. A luminous device according to claim 1, in which the contrast of the image is substantially constant. 3. A light device according to claim 2, in which the pixelated light beam projects on at least part of the road an overall lighting (6) corresponding to an increasing light intensity as a function of the distance from the light device, the image corresponding to a multiplication of the light intensity corresponding to the overall lighting by a predetermined constant. 4. Luminous device according to claim 3, in which the predetermined constant is between 2.5 and 5. 5. Light device according to any one of claims 1 to 4, in which the pixelated light beam darkens an outline (208) of the image pattern. 6. Luminous device according to any one of claims 1 to 5, in which the sharpness has a decreasing value as a function of the distance of the image from the luminous device. 7. Light device according to claim 6, wherein the sharpness is between 0.075 ° and 0.125 ° when the distance of the image from the light device is of the order of 50 meters. 8. A light device according to claim 6 or 7, wherein the sharpness is between 0.15 ° and 0.2 ° when the distance of the image from the light device is of the order of 10 meters. 9. A light device according to claim 8, wherein the light source (12) is formed by a matrix of individual light sources which extend in the same plane (π). 10. The light device according to claim 9, wherein the individual light sources each have a size of 40 micrometers for a focal length of 45 millimeters and a resolution of 0.05 °. 11. Land vehicle light projector (4) comprising a light device according to any one of claims 1 to 10. 12. A method of projecting a pixelated light beam by a land vehicle light device according to any one of claims 1 to 10. 13. Computer program comprising program code instructions for the execution of the method according to claim 12 when said program is executed by a projection control unit on a scene of a pixelated light beam by a vehicle light device (4) terrestrial comprising a pixelated light source (12, 120) and the control unit (190) coupled to the light source. 14. Control unit (190) comprising a processor associated with a memory having recorded the program according to claim 13. 1/3