LIGHTING DEVICE FOR MOTOR VEHICLES WITH LIGHT POWER MODULATION ACCORDING TO EXTERNAL LIGHT SIZE

Abstract

The invention relates to a light signaling device (4) for a motor vehicle (2), comprising a housing (8) with an opening; a lens (10) fixed to the housing (8) and closing the opening; a light module (12) disposed inside the housing (8); a light sensor (14) configured to modulate the luminous power of the light module (12) according to ambient lighting; and an optical device (16) configured to focus external light rays, incident on the lens (10) or parallel to said incident external light rays, onto the light sensor (14), along an axis of incidence (18) such that after reflection on said lens (10) said incident external light rays are oriented along the optical axis (6). (Figure to be published with the abbreviation: Figure 6)

Description

Title of the invention: LIGHT SIGNALING DEVICE FOR MOTOR VEHICLE WITH MO DULATION OF LIGHT POWER ACCORDING TO EXTERIOR BRIGHTNESS Technical field

[0001] The invention relates to the field of light signaling for motor vehicles. Prior art

[0002] The perception of a light signal emitted by a light device is dependent on the ambient brightness, more particularly on the ratio between the luminance of the light signal and the luminance of the ambient brightness reflected by the light device. Indeed, when the light device is located outside, the perception by an observer of the light signal of a given light intensity is very good when the ambient exterior brightness is low and becomes less good when the ambient exterior brightness is high, for example in broad daylight in sunny conditions. In order to make the light signal perceptible in all reasonably possible conditions, it is necessary to provide a high lighting power capable of producing a luminance greater than the luminance of the reflection of the ambient brightness.Therefore, under many operating conditions of the lighting device, the lighting power and resulting luminance is oversized.

[0003] Patent document FR 3 050 542 A1 relates to a "head-up" type display for a motor vehicle, comprising a light sensor and a display configured so that the brightness of the generated image is controlled as a function of the light intensity detected by the light sensor. A light guide is arranged directly in front of the light sensor, so as to collect light radiation coming from the front of the motor vehicle, passing through the windshield. The brightness of the generated image is controlled as a function of the detected external radiation and so as to increase the brightness of the image in the presence of intense external radiation and vice versa. This teaching is advantageous in that it optimizes the power consumption of the display. However, it is specific to a "head-up" type display; its solution is not compatible for a light signaling device, such as a rear light. Statement of the invention

[0004] The invention aims to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the invention aims to optimize the electrical consumption of a light signaling device, in particular for a motor vehicle.

[0005] The subject of the invention is a light signaling device for a motor vehicle, comprising: a housing with an opening; a glass fixed to the housing and closing the opening; a light module arranged inside the housing and capable of emitting through the glass one or more light signals along an optical axis of the light module; remarkable in that the light signaling device further comprises; at least one light sensor configured to modulate a light power of the light module as a function of external lighting; and an optical device configured to concentrate towards the at least one light sensor a beam of external light rays, incident on the glass or parallel to said incident external light rays, along an axis of incidence such that after reflection on said glass said beam of external light rays forms a reflected light beam comprising the optical axis.

[0006] Advantageously, the light module is a pictogram display.

[0007] The modulation of the luminous power of the light module as a function of the external lighting is such that the power in question increases with the external lighting and vice versa. The modulation in question is advantageously such that a ratio between the luminance of the light signal and the luminance of the beam of external rays reflected by the glass, in a preferred observation cone oriented along the optical axis does not fall below a predetermined level, preferably greater than or equal to 2, more preferably greater than or equal to 3.

[0008] According to an advantageous embodiment of the invention, the optical device is configured to concentrate towards the at least one light sensor the beam of external light rays forming a cone of incidence oriented on the axis of incidence such that after reflection on the glass the reflected light beam forms a cone of reflection comprising and / or oriented along the optical axis.

[0009] According to an advantageous embodiment of the invention, the reflection cone comprises an apex angle of between 30 and 60°.

[0010] According to an advantageous embodiment of the invention, the cone of incidence and / or the cone of reflection is arbitrary or circular.

[0011] According to an advantageous embodiment of the invention, when said light signaling device is in the mounting position on the motor vehicle, the reflected light beam extends vertically upwards and / or downwards relative to the optical axis, and / or horizontally on at least one side of the optical axis, over an angular range of between 10° and 40°, preferably between 10° and 30°.

[0012] According to an advantageous embodiment of the invention, the optical device comprises a lens centered on the axis of incidence.

[0013] According to an advantageous embodiment of the invention, the lens is convergent with a focus located between said lens and the at least one light sensor, preferably on the at least one light sensor.

[0014] According to an advantageous embodiment of the invention, the optical device comprises at least one light guide optically arranged directly in front of the at least one light sensor. Advantageously, the at least one light guide comprises an input face facing the lens and an output face facing the at least one light sensor. Advantageously, the at least one light guide is conical with a cross-section decreasing from the input face towards the output face. Advantageously, the at least one light guide comprises at least two of said light guides, arranged side by side.

[0015] According to an advantageous embodiment of the invention, the light signaling device comprises a cover optically arranged in front of the at least one light sensor and configured to restrict a measurement range of the at least one light sensor.

[0016] According to an advantageous embodiment of the invention, the at least one light sensor and the optical device are arranged inside the housing.

[0017] The measures of the invention are advantageous in that they make it possible to optimize the electrical consumption of the light signaling device, and this in a very precise manner by only providing for increasing the light intensity of the light module and therefore the luminance in the presence of incident external rays whose reflection reduces the contrast in the preferred observation sectors. These are in fact limited, so that selective detection of the incident external light rays following directions such that after reflection they propagate in the preferred observation sectors and are added to the light rays emitted by the light module, makes it possible to increase the light power and therefore the luminance only when this is useful.

[0018] The invention is particularly advantageous for a pictogram display whose perception, taking into account the diversity of pictograms likely to be displayed, selectively, requires significant contrast.

[0019] The light signaling device may be a rear light, a front light or any other light signaling device of a motor vehicle. Brief description of the drawings

[0020] [Fig.l] is a schematic side view of the rear part of a motor vehicle;

[0021] [Fig.2] is a schematic top view of the rear part of the motor vehicle of [Fig.l];

[0022] [Fig.3] is a schematic view in vertical section of a rear light according to the invention;

[0023] [Fig.4] is a detail view of [Fig.3], showing the outer light rays incidents on the lens;

[0024] [Fig.5] is a schematic horizontal sectional view of the rear light of [Fig.3].

[0025] [Fig.6] is a schematic perspective view of the rear light of Figures 3 and 5.

[0026] [Fig.7] is a view similar to [Fig.4] showing a different architecture of the optical device;

[0027] [Fig.7]] is a view similar to [Fig.7] showing a still different architecture of the optical device; Detailed description

[0028] In the following description, the notions of position such as "top", "bottom", "horizontal", "vertical", "front", "rear", etc. are to be understood when the light signaling device is in the normal mounting position on the motor vehicle, that is to say in the operational position, and also along a main direction of propagation of the light along the optical axis of the device in question. By optical axis, we mean a main axis of light emission and / or main or preferred observation of the light signaling device, this axis being preferentially parallel to the road when said light signaling device is mounted on the vehicle on said road.

[0029] Figures 1 and 2 are schematic side and top views of the rear part of a motor vehicle, more particularly of the rear lights of the vehicle in question.

[0030] In [Fig. 1], the motor vehicle 2 comprises, in a conventional and known manner, two rear lights 4, only one of which is visible. Each of the two rear lights comprises at least one, preferably several light signaling functions, such as in particular a so-called lantern or position light function, a direction indicator function, a stop function, a fog light function and / or a reversing light function. It may also comprise a pictogram display function, which may be provided by different technologies, such as in particular a backlit liquid crystal display, a microelectromechanical system commonly referred to as “MEMS” (acronym for “Microelectromechanical Systems”), a network of light sources of the light-emitting diode type, etc.The light signaling device, materialized by the rear light 4, comprises at least one light module (not visible) having an optical axis 6, corresponding to a main observation axis, which is parallel to a longitudinal axis of the motor vehicle 2. Taking into account its . relatively low position relative to the road, the rear light 4 presents in a vertical plane a vertical sector of projection of light image which is between an angle of -10° and +20° relative to the optical axis 4. This vertical sector is in reality a privileged observation sector of the rear light. The values ​​of -10° and +20° are given for information; they may depend on the height of the rear light on the motor vehicle.The asymmetry of the vertical observation sector, with respect to the optical axis 6, namely that the absolute value of the downward angle, in this case -10°, is smaller than the absolute value of the upward angle, in this case +20°, is due to the fact that the eyes of an observer in a higher following vehicle, such as a truck, may be located at a greater height with respect to the optical axis 6 than the eyes of another observer in a lower following vehicle, such as a sports car, or in a following vehicle approaching a road crest, located below the optical axis 6.

[0031] In [Fig. 2], the rear light 4 has in a horizontal plane a horizontal sector of projection of a luminous image which is between an angle of -30° and +30° relative to the optical axis 4. This sector is in reality a privileged horizontal sector of observation of the rear light, in particular by observers in following vehicles located on adjacent driving lanes, on either side of the driving lane of the vehicle 4. The values ​​of -30° and +30° are given for information purposes; they may depend in particular on the lateral position of the rear light on the motor vehicle.

[0032] [Fig. 2] also shows a light signaling device 4' arranged in a central rear position, as well as a light signaling device 4” arranged in a lateral position, the preferred observation sectors of which are represented in a horizontal plane relative to an optical axis 6' and 6”, respectively, or main observation axis. This may in particular be a display screen. The optical axis 6' of the light signaling device 4' is in this case parallel to the longitudinal axis of the vehicle and the optical axis 6” of the light signaling device 4” is transverse to the longitudinal axis of the vehicle, it being understood, however, that these optical axes may have other orientations, preferably included in a plane parallel to the road, in particular depending on the position of the light signaling device on the vehicle.

[0033] In view of Figures 1 and 2, it appears that the vertical and horizontal sectors of privileged observation of the rear light 4 and of the light signaling devices 4' and 4” are quite restricted and moreover correspond to a privileged observation cone. It is therefore in this privileged observation cone that it is particularly useful to achieve a sufficient luminance contrast, in particular in the presence of significant ambient brightness. This privileged observation cone is advantageously arbitrary in that its directing curve is not circular but rather oval or other Again.

[0034] Figures 3 to 6 detail a light signaling device, in this case a rear light 4, in accordance with the invention.

[0035] [Fig. 3] is a vertical sectional view of the rear light 4 of Figures 1 and 2.

[0036] The light signaling device 4 comprises a housing 8 with an opening, a glass 10 closing said opening, and a light module 12. The latter is in this case a pictogram display of the network or matrix type of light sources of the electroluminescence diode type, it being understood that other types of pictogram display, such as those mentioned above in relation to figures 1 and 2 are conceivable and also that other types of light module, also such as those mentioned above in relation to figures 1 and 2 are conceivable.

[0037] It can be observed that the glass 10 is inclined relative to the vertical, and in this case upwards and backwards (along the main direction of propagation of the rays along the optical axis). This inclination has the effect that external light rays incident on the glass and which are reflected there are likely to be in the preferred vertical observation sector and, therefore, to reduce the contrast of the light beam of the light module in the sector in question.

[0038] The light signaling device 4 further comprises a light sensor 14 and an optical device 16, in this case a lens, configured to collect and measure the light intensity of a beam of external light rays incident on the glass 10, along the axis of incidence 18. More particularly, the axis of incidence is a central axis of a vertical sector illustrated by two incident external rays, in broken lines, which after reflection on the glass 10, on the external face and / or the internal face, correspond to the beam of reflected rays, in continuous lines, located at -10° and +20° inclination relative to the optical axis 6 of the light module 12. In other words, the light sensor 14 and the optical device 16 are configured to collect the beam of external light rays which are likely to be perceived by an observer located in the preferred vertical observation sector.The light sensor 14 can thus measure the light intensity of these rays, from which the corresponding luminance can be deduced, namely in the preferred vertical observation sector.

[0039] The light signaling device 4 may further comprise a control unit 20 electrically connected to the light sensor 14 and to the light module 12, so as to modulate the light intensity of said light module as a function of the light intensity measured by the light sensor 14, and this so as to increase the light intensity of the light module 12 when the light intensity measured by the light sensor 14 increases. More specifically, the modulation may be such that the ratio between the luminance of the light beam produced by the light module 12 in the preferred vertical observation sector and the luminance of the external light rays reflected in the preferred vertical observation sector is constant or at least does not become less than a minimum value, said minimum value being greater than or equal to 2, preferably greater than or equal to 3.

[0040] Still with reference to [Fig. 3], the light signaling device 4 may further comprise a cover 22 arranged directly in front of the light sensor 14, i.e. between the light sensor 14 and the optical device 16. This cover makes it possible to limit the quantity of light reaching the light sensor 14, by blocking the incident external light rays which are outside the beam of incident external light rays whose reflection is located in the preferred vertical observation sector.

[0041] The optical device 16 is advantageously a converging lens, for example of the plano-convex type, with a focus located on or near the light sensor 14. This configuration makes it possible to converge on the light sensor 14 the incident external rays in a determined sector, in this case the sector centered on the axis of incidence 18. The cover 22 makes it possible to adjust the aperture of the sector in question measured by blocking the rays located outside the beam of incident external light rays, centered on the axis of incidence 18.

[0042] [Fig. 4] is a detail view of [Fig. 3], showing the external light rays incident on the optical device 16 and converging towards the light sensor 14. Two parallel incident external light rays can be observed, inclined to the left with respect to the axis of incidence 18 and represented by broken lines. These two rays are deflected by the optical device 16, in this case refracted by the optical device being a converging lens, so as to converge on the measuring face of the light sensor 14. Two parallel incident external light rays can also be observed, inclined to the right with respect to the axis of incidence 18 and represented by dotted lines. These two rays converge on the measuring face of the light sensor 14, however at a distance from the place of convergence of the other two parallel incident external light rays.The cover 22 thus makes it possible to delimit and therefore define the beam of incident external light rays whose light intensity is measured. The opening of the cover 22 can thus have a non-circular closed contour, thus defining a measured incident beam whose section is not necessarily circular.

[0043] [Fig.5] is a horizontal sectional view of the rear light 4 of Figures 1 and 2 and [Fig.3].

[0044] It can be observed that the glass 10 is inclined relative to a transverse direction perpendicular to the optical axis 6, and in this case towards the outside and the rear (following the main direction of propagation of the rays along the optical axis). This inclination has the effect that certain external light rays incident on the glass and which are reflected there are likely to be in the preferred horizontal observation sector and, therefore, to reduce the contrast of the light beam of the light module in the sector in question.

[0045] In [Fig.5], we can observe the vertical projection of the axis of incidence 18 mentioned above in relation to [Fig.3] showing its horizontal projection. The vertical projection of the axis of incidence 18 is inclined relative to the optical axis 6 due to the inclination of the glass relative to a transverse direction perpendicular to the optical axis 6, mentioned above. Indeed, it is observed that it is the external rays incident on the glass 10 located in the sector of incidence delimited by the two rays in broken lines whose reflections correspond to the rays in continuous lines delimiting the privileged horizontal observation sector, which are reflected in the privileged horizontal observation sector.

[0046] [Fig. 6] is a perspective view of the light signaling device of Figures 3 and 5.

[0047] A beam of incident external light rays, centered on the axis of incidence 18, is shown, as well as a beam of reflected external rays, including the optical axis 6. According to [Fig.l], the reflected beam is extended more upwards than downwards relative to the optical axis 6.

[0048] In [Fig.6], the x axis corresponds to the longitudinal axis of the motor vehicle, the y axis to the transverse axis, horizontal and perpendicular to the x axis, and the z axis corresponds to the vertical axis, perpendicular to the x and y axes.

[0049] It is understood that the beam of incident external light rays and the beam of reflected external rays are advantageously not circular so as to correspond to the preferred vertical observation sector and the preferred horizontal observation sector, as illustrated in FIGS. 1, 2, 3 and 5, taking into account their angle differences (the preferred vertical observation sector has an angle of 60° while the preferred horizontal observation sector has an angle of 30°). The beams in question may be configured to encompass the sectors in question. The beams in question may also be more complex non-circular shapes. For this purpose, the contour of the orifice of the cover 22 may be configured to allow only the incident external rays contained in a beam of non-circular contour to pass towards the light sensor 14.

[0050] Figures 7 and 8 are similar to [Fig.4], however showing somewhat different possible architectures of the optical device 16.

[0051] In [Fig.7], the optical device 16 comprises, as in the embodiment of the Figures 3 to 6, a converging lens 16.1; however, it additionally comprises a light guide 16.2 optically arranged between the output face of the converging lens 16.1 and the light sensor 14. The light guide 16.2 in question may have a generally conical profile, from its input face, adjacent to the cover 22, towards its output face, adjacent to the light sensor 14. Such a configuration is advantageous in that it makes it possible to reduce the size of the light sensor 14.

[0052] In [Fig.8], the optical device comprises several light guides 16.2 and 16.3 arranged side by side and a light sensor 14.1 and 14.2 for each light guide.

[0053] In the embodiment described above, the light sensor 14 and the optical device 16 are arranged in the housing 8 of the light signaling device 4. It is however conceivable to provide the light sensor 14 and the optical device 16 outside the housing 8 in question. They can in fact be housed in a specific housing, the external rays measured by the light sensor then being parallel to the external rays incident on the glass, as described above.

Claims

Claims

1. Light signaling device (4; 4'; 4”) for a motor vehicle (2), comprising: - a housing (8) with an opening; - a glass (10) fixed to the housing (8) and closing the opening; - a light module (12) arranged inside the housing (8) and capable of emitting through the glass (10) one or more light signals along an optical axis (6; 6'; 6”) of the light module (12); the light signaling device (4) further comprising: - at least one light sensor (14; 14.1, 14.2) configured to modulate a light power of the light module (12) as a function of external lighting; and - an optical device (16; 16.1, 16.2, 16.3) configured to concentrate towards the at least one light sensor (14) a beam of external light rays incident on the glass (10) or parallel to said incident external light rays, along an axis of incidence (18) such that after reflection on said glass (10) said external light rays form a reflected light beam oriented along the optical axis (6) characterized in that: - the optical device comprises a lens (16; 16.1) centered on the axis of incidence (18), in which the lens (16; 16.1) is convergent with a focus located between said lens (16; 16.1) and the at least one light sensor (14; 14.1, 14.2), preferably on the at least one light sensor (14), and in that the optical device comprises at least one light guide (16, 16.3) optically arranged directly in front of the at least one light sensor (14; 14.1, 14.2), and in that the light signaling device (4) comprises a cover (22) arranged optically in front of the at least one light sensor (14; 14.1, 14.2) and configured to restrict a measuring range of the at least one light sensor.

2. Light signaling device (4; 4'; 4”) according to claim 1, wherein the optical device (16) is configured to concentrate towards the at least one light sensor (14; 14.1, 14.2) the beam of external light rays in a cone of incidence oriented on the axis of incidence (18) such that after reflection on the glass (10) the beam reflected light forms a reflection cone comprising and / or oriented along the optical axis (6).

3. A light signaling device (4; 4'; 4”) according to claim 2, wherein the reflection cone comprises an apex angle of between 30 and 60°.

4. Light signaling device (4; 4'; 4”) according to one of claims 2 and 3, in which the cone of incidence and / or the cone of reflection is arbitrary or circular.

5. Light signaling device (4; 4'; 4”) according to one of claims 1 to 4, wherein, when said light signaling device (4) is in the mounting position on the motor vehicle (2), the reflected light beam extends vertically upwards and / or downwards relative to the optical axis (6; 6'; 6”), and / or horizontally on at least one side of the optical axis (6; 6'; 6”), over an angular range of between 10° and 40°, preferably between 10° and 30°.

6. Light signaling device (4; 4'; 4”) according to one of claims 1 to 5, wherein the light sensor (14) and the optical device (16) are arranged inside the housing (8).

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