Light device for a vehicle comprising a light guide

Abstract

The invention relates to a light device (1) for a vehicle (2) comprising a light source (10) and a light guide (11) comprising a body (110), characterized in that said light guide (1) comprises: - a light input array (111) comprising first patterns (1110) formed as an integral part of said body (110), inclined at a first angle of inclination (α) and repeated periodically, - a light output array (112) comprising second patterns (1120) formed as an integral part of said body (110), inclined at a second angle of inclination (α') and repeated periodically in the same manner as the first patterns (1110), said first angle of inclination (α) and said second angle of inclination (α') being complementary with respect to 180°, in the same direction or in opposite directions, and in that said light source (10) is arranged facing said light input array (111).

Description

Vehicle lighting device comprising a light guide

[0001] The present invention relates to a lighting device for a vehicle. It also relates to a lighting assembly comprising such a lighting device. It finds a particular but non-limiting application in motor vehicles.

[0002] In the field of motor vehicles, a light device known to those skilled in the art comprises:- a light source configured to emit light rays,- a surface light guide comprising a body in the form of a light guide sheet configured to propagate said light rays emitted by the light source.

[0003] A disadvantage of this prior art is that the light guide sheet has a very thin thickness and the size of the light source is too large compared to the thickness of the light guide sheet. As a result, a large portion of the light rays emitted by the light source do not enter the light guide; only about 15% of the light generated by the light source is coupled with the surface light guide. The luminous efficiency of the surface light guide is thus low.

[0004] In this context, the present invention aims to provide a light device which makes it possible to solve the mentioned drawback.

[0005] For this purpose, the invention proposes a vehicle light device comprising a vehicle light device, said light device comprising:- a light source configured to emit light rays,- a light guide comprising a body configured to propagate said light rays emitted by said light source,According to the invention, said light guide further comprises:- a diffraction light input grating comprising a plurality of first optical patterns inclined so that for each first optical pattern, a first inclination angle is defined between a first inclined wall of said first optical pattern and a base of the light guide from which said first optical pattern projects, said first optical patterns being periodically repeated according to a first period and integral with said body of said light guide,- a diffraction light output grating comprising a plurality of second optical patterns inclined so that for each second optical pattern, a second angle of inclination is defined between a fourth inclined wall of said second optical pattern and a base of the light guide from which said second optical pattern projects, said fourth inclined wall being located on the same side as said first inclined wall, said second optical patterns being periodically repeated according to a second period equal to the first period and integral with said body of said light guide, said first angle of inclination and said second angle of inclination being complementary with respect to 180°, in the same direction or in the opposite direction.,

[0006] Finally, said light source is arranged opposite said light input array so that light rays enter said light input array.

[0007] Here, it can be understood from the above that in the diffraction light input grating, all the first optical patterns are inclined in the same way. The same first inclination angle is defined between each first optical pattern and the base. Similarly, in the diffraction light output grating, the second optical patterns are inclined in the same way with the same second inclination angle between each second optical pattern and the base. The first and second inclination angles have a complementary relationship, that is, the sum of the absolute value of the first inclination angle and the absolute value of the second inclination angle is equal to 180°.

[0008] According to non-limiting embodiments, said light device may further comprise one or more additional characteristics taken alone or in all technically possible combinations, among the following.

[0009] According to a non-limiting embodiment, said light input network and said light output network are arranged on the same surface of the light guide. This makes it possible to simplify the manufacturing process of the light device and to reduce the process time.

[0010] According to a non-limiting embodiment, said light input network and said light output network are arranged on different surfaces of the light guide. This allows different integration of the light input network and the light output network in the light device.

[0011] According to a non-limiting embodiment, said first optical patterns and said second optics protrude from a surface of the light guide. This allows for a simple manufacturing process.

[0012] According to a non-limiting embodiment, said first optical patterns and said second optics are recessed relative to a surface of the light guide. This makes it possible to have a more compact light device.

[0013] According to a non-limiting embodiment, said first optical patterns and said second optics are of the same size. This makes it possible to simplify the manufacturing process of the light device. This makes it possible to use only a single manufacturing mask by reversing the orientation of the mask when necessary.

[0014] According to a non-limiting embodiment, said first patterns and said second patterns have a cross-section in the shape of a parallelogram.

[0015] According to a non-limiting embodiment, said light device further comprises a light collimator arranged between said light source and said light guide so as to form a collimated light beam which arrives with normal incidence on said light input grating. This makes it possible to increase the luminous efficiency of the light device.

[0016] According to a non-limiting embodiment, said light device comprises a single light output network.

[0017] According to a non-limiting embodiment, said light source is monochromatic.

[0018] According to a non-limiting embodiment, said light guide is a surface light guide and said body is in the form of a light guide sheet. This makes it possible to extend over all or part of a flat or curved surface.

[0019] According to a non-limiting embodiment, the first optical patterns and the second optical patterns are of the same material as said body of said light guide. They thus have the same refractive index of light for a given wavelength. This allows the light to be diffracted and to be guided in the light guide.

[0020] According to a non-limiting embodiment, the first optical patterns and the second optical patterns are formed in the mass of said body of said light guide.

[0021] According to a non-limiting embodiment, the light device has a first direction and a second direction opposite to the first direction and parallel to the first direction, said first direction being transverse to the body of said light guide.

[0022] According to a non-limiting embodiment, the first optical patterns have a cross-section in the shape of a parallelogram in a plane parallel to the first direction and to the second direction.

[0023] According to a non-limiting embodiment, the second optical patterns have a cross-section in the shape of a parallelogram in a plane parallel to the first direction and to the second direction.

[0024] According to a non-limiting embodiment, the light guide has a thickness greater than or equal to 125 μm.

[0025] According to a non-limiting embodiment, the material of the light guide comprises a refractive index of light n' less than 1.8.

[0026] There is further provided a lighting assembly of a vehicle, characterized in that said lighting assembly comprises said light device according to one of the preceding characteristics.

[0027] According to a non-limiting embodiment, said light assembly is a front face or a rear face of a vehicle or a projector or a rear light of a vehicle. This makes it possible to create illuminated patterns.

[0028] According to a non-limiting embodiment, said light assembly is part of an element of the passenger compartment of said vehicle. According to non-limiting variant embodiments, the light assembly is part of the dashboard or a door of the vehicle. This makes it possible to illuminate certain parts of the dashboard or a door inside the passenger compartment of the vehicle.

[0029] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures:

[0030] is a schematic illustration of a light device according to a first alternative embodiment of a first non-limiting embodiment of the invention, the light device comprising a light source, a light guide with a body, a diffraction light input grating with first patterns, and a diffraction light output grating with second patterns,

[0031] is a zoom on the light input network of the light guide of the light device of the,

[0032] is a zoom on a light output network of the light guide of the light device of the,

[0033] is a schematic illustration of a light device according to a second alternative embodiment of a first non-limiting embodiment of the invention, the light device comprising a light source, a light guide with a body, a diffraction light input grating with first patterns, and a diffraction light output grating with second patterns,

[0034] is a zoom on the light input network of the light guide of the light device of the,

[0035] is a zoom on the light output network of the light guide of the light device of the,

[0036] is a schematic illustration of a light device according to a first alternative embodiment of a second non-limiting embodiment of the invention, the light device comprising a light source, a light guide with a body, a diffraction light input grating with first optical patterns, and a diffraction light output grating with second optical patterns,

[0037] is a schematic illustration of a light device according to a second alternative embodiment of a second non-limiting embodiment of the invention, the light device comprising a light source, a light guide with a body, a diffraction light input grating with first patterns, and a diffraction light output grating with second patterns,

[0038] is a schematic illustration of a top view of the body of the light device of the,

[0039] is a schematic illustration of a side view of the light device of the, said light device further comprising a light collimator disposed between said light source and said light guide according to a non-limiting embodiment,

[0040] is a schematic illustration of a non-limiting embodiment of a lighting assembly of a vehicle, said lighting assembly comprising a light device according to the,

[0041] is a 3D view of part of the light input network of the, and

[0042] is a 3D view of part of the light output network of the.

[0043] Identical elements, by structure or function, appearing in different figures retain, unless otherwise specified, the same references.

[0044] The light device 1 according to the invention is described with reference to Figures 1 to 13. In a non-limiting embodiment, the light device 1 is a light device of a vehicle 2 (illustrated in the). In a non-limiting embodiment, the vehicle 2 is a motor vehicle. By motor vehicle is meant any type of motorized vehicle. This embodiment is taken as a non-limiting example in the remainder of the description. In the remainder of the description, the vehicle 2 is thus otherwise called motor vehicle 2. In a non-limiting variant embodiment, the vehicle 2 is a thermal vehicle or an electric vehicle or a hybrid vehicle.

[0045] The light device 1 is part of a light assembly 3. In non-limiting embodiments, the light assembly 3 is a front face or a rear face of the motor vehicle 2 or a headlight or a rear light of the motor vehicle 2. In the non-limiting example of the, the light assembly 3 is the front face of the motor vehicle 2. In another non-limiting embodiment, the light assembly 3 is part of an element of the passenger compartment of the motor vehicle 2. In non-limiting variant embodiments, the light assembly 3 is part of the dashboard or a door of the motor vehicle 2. The non-limiting embodiment of the front face is taken as a non-limiting example in the remainder of the description.

[0046] As illustrated in Figures 1, 4, 7 and 8, the light device 1 comprises:- a light source 10, and- a light guide 11 comprising a body 110, a light input grating 111 by diffraction and a light output grating 112 by diffraction. The light input grating 111 by diffraction is otherwise called light input grating 111 or input diffraction grating 111 in the remainder of the description. Said light output grating 112 by diffraction is otherwise called light output grating 112 output diffraction grating 112 in the remainder of the description. The light input grating 111 and the light output grating 112 are 1D gratings.

[0047] As illustrated in Figures 1, 4, 7 and 8, the light device 1 has a first direction D (otherwise called the observation direction) and a second direction D' opposite the first direction D and parallel to the first direction D. The first direction D is transverse (otherwise called perpendicular) to the body 110 of the light guide 11. The first direction D corresponds to the direction in which an external observer can observe the light assembly 3 of the motor vehicle 2 comprising said light device 1. The light device 1 has a light emission direction which corresponds to the first direction D.

[0048] We will speak of forward direction or backward direction respectively for the first direction D and the second direction D'. In the non-limiting example illustrated in the figures, the directions D and D' are substantially parallel to the vehicle axis Ox (illustrated in the).

[0049] The light source 10 is configured to emit light rays R. It is arranged opposite said light input network 111 so that its light rays R which form a first light beam Fx enter the light input network 111.

[0050] In a non-limiting embodiment, the light source 10 is a semiconductor light source. In a non-limiting embodiment, the semiconductor light source is part of a light-emitting diode. By light-emitting diode, we mean any type of light-emitting diode, whether in non-limiting examples LEDs (“Light Emitting Diodes” in English), OLEDs (“Organic LEDs” in English), AMOLEDs (“Active-Matrix-Organic LEDs” in English), or FOLEDs (“Flexible OLEDs” in English).

[0051] In a non-limiting embodiment, the light source 10 is a monochromatic source. In non-limiting embodiments, it is a monochromatic source R (red), G (green) or B (blue). As a reminder, for a monochromatic source: - B: the wavelength of the light λ is 455 nanometers (nm), - G: the wavelength of the light λ is 535 nanometers, - R: the wavelength of the light λ is 621 nanometers.

[0052] Due to the monochromatic source, the first light beam Fx is monochromatic.

[0053] In a first non-limiting embodiment, the light guide 11 is a light guide in the form of a rod. In non-limiting embodiments, it is of round or square section.

[0054] In a second non-limiting embodiment, the light guide 11 is surface-based. A surface-based light guide is understood to mean an optical guiding element of which one of the dimensions is much smaller than the other two dimensions in space, for example smaller by one or more orders of magnitude. Here, the thickness of the light guide 11 is much smaller than its length and its width. In a non-limiting embodiment, the light guide 11 has a thickness of between 125 and 2000 micrometers. The light guide 11 is thus very thin. When the light guide 11 is surface-based, its body 110 is in the form of a light-guiding sheet. In a manner known to those skilled in the art, the light-guiding sheet comprises one or more regions with one or more light-emitting zones. In a non-limiting embodiment, the light-emitting zone(s) form all or part of a decoupling pattern (not shown).The decoupling pattern is thus illuminated by the light generated by the light source 10 which emerges from the light guide 11.

[0055] In a non-limiting embodiment, the light guide 11 is a flexible light guide. Flexible means that it can bend without being damaged or breaking. Since it is flexible, it can fit over flat or curved surfaces.

[0056] The light guide 11 is transparent. The term transparent indicates that the material of which it is composed allows visible light to pass through, at least partially, and in particular the light emitted by the light source 10.

[0057] In a non-limiting embodiment, the light guide 11 is made of polycarbonate (PC), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU), or polyethylene terephthalate (PET). Such materials make it possible to produce a transparent light guide 11.

[0058] The material of the light guide 11 comprises a refractive index of light n' less than 1.8. This makes it possible to correctly reflect and propagate the light generated by the light source 10 in the body 110 of the light guide 11.

[0059] The light guide 11 comprises a first surface 1.1 and a second surface 1.2 opposite the first surface 11.1.

[0060] The body 110 of the light guide 11 is configured to propagate the light rays R emitted by the light source 10.

[0061] In a non-limiting embodiment, the body 110 has a thickness e determined so as to avoid total reflection of the light in said body 110 to prevent the light from exiting through the light input network 111. In a non-limiting embodiment, the light guide 11 has a thickness e greater than or equal to 125 μm. In a non-limiting embodiment variant, the thickness e is equal to 500 μm. In this way, the light is diffracted in the body 110 with a diffraction angle θ of 45°.

[0062] The light input grating 111 and the light output grating 112 are surrounded by air of refractive index n =1.

[0063] As illustrated in Figures 2 and 5, the light input grating 111 comprises a plurality of first optical patterns 1110 which are diffractive optical patterns (otherwise called first patterns 1110) inclined at a first tilt angle α and periodically repeated at a first period T. The light input grating 111 makes it possible to diffract the light generated by the light source 10 and to control the direction in which the light will propagate in the body 110 of the light guide 11.

[0064] The light (namely the first light beam Fx) from the light source 10 is coupled to the light input grating 111. It is diffracted in the material of the light guide 11 by means of the light input grating 111, then when it encounters a wall of the light guide beyond the light input grating 111, it is reflected by reflection in the body 110 of the light guide 11 which achieves the guiding effect in said body 110. Thanks to the first patterns 1110, the light input grating 111 makes it possible to send the light into the body 110 of the light guide with a diffraction angle θ of 45°. This prevents the light from exiting through the light input grating 111.

[0065] As illustrated in Figures 2 and 5, the first optical patterns 1110 have a cross-section in the shape of a parallelogram in a plane parallel to the first direction D and to the second direction D'. In particular, the section is in the shape of an open parallelogram. In a non-limiting embodiment, the first optical patterns 1110 are parallelepipeds. For this purpose, the first optical patterns 1110 comprise a first wall 1110.2 and a second wall 1110.3. The first wall 1110.2 and the second wall 1110.3 are inclined. The second wall 1110.3 is parallel to the first wall 1110.2.

[0066] In a non-limiting embodiment, the first tilt angle α is between 30° and 45°. In a non-limiting embodiment, the first period T is between 400 nanometers and 600 nanometers.

[0067] Since the light input network 111 is a 1D network, its shape can be seen in a 3D view illustrated in the context of a non-limiting alternative embodiment illustrated in the.

[0068] As illustrated in Figures 3 and 6, the light output grating 112 comprises a plurality of second optical patterns 1120 which are diffractive optical patterns (otherwise called second patterns 1120) inclined at a second tilt angle α' and periodically repeated at a second period T'. The light which has propagated by reflection in the body 110 of the light guide 11 is output coupled with the light output grating 112 and emerges as a second light beam Fx' by said light output grating 112 in the first direction D. This makes it possible to illuminate the light assembly 3 of which the light device 1 is a part. The first light beam Fx being monochromatic, the second light beam Fx' is also monochromatic.

[0069] As illustrated in Figures 3 and 6, the second optical patterns 1120 have a cross-section in the shape of a parallelogram in a plane parallel to the first direction D and to the second direction D'. In particular, the section is in the shape of an open parallelogram. In a non-limiting embodiment, the second optical patterns 1120 are parallelepipeds. For this purpose, the second optical patterns 1120 comprise a third wall 1120.2 and a fourth wall 1120.3. The third wall 1120.2 and the fourth wall 1120.3 are inclined. The fourth wall 1120.3 is parallel to the third wall 1120.2.

[0070] Since the light output array 112 is a 1D array, its shape can be seen in a 3D view illustrated in the context of a non-limiting alternative embodiment illustrated in the.

[0071] In a first non-limiting embodiment illustrated in Figures 1 and 4, the second inclination angle α' is complementary to the first inclination angle α with respect to 180° and is in the same direction as the first inclination angle α. Thus, |α' |+|α|=180°.

[0072] In a second non-limiting embodiment illustrated in Figures 7 and 8, the second inclination angle α' is complementary to the first inclination angle α with respect to 180° and is in the opposite direction to the first inclination angle α. Thus, |α' |+ |α|=180°.

[0073] The first period T and the second period T' are functions of the wavelength λ of the light generated by the light source 10. We recall that the first period T = λ / (n'*sinα).

[0074] It is recalled that the wavelength λ = ct = c / f with t the time period, f the frequency and c the speed. The light which has a given wavelength λ arrives on a light input grating 110 which has a period T which is close to its time period t. Thus, it can enter into resonance with it and thus allows a coupling of the light with the light input grating 110. The first period T is very close to the time period t. In a non-limiting embodiment, the first period T is different from the time period t by 5% to 10%.

[0075] The second period T' is equal to the first period T. Thus, the light output grating 112 has the same periodicity as the light input grating 111. This facilitates the manufacturing process. The diffraction of the light at the output of the light guide 11 will thus also be very efficient since the second period T' is thus also very close to the time period t corresponding to the wavelength λ of the light generated by the light source 10. The first period T and the second period T' are of fixed values.

[0076] In a non-limiting embodiment illustrated in Figures 2 and 3, and 5 and 6, the first optical patterns 1110 and the second optical patterns 1120 are of the same size. Thus, they are of the same height h and the same width w, and distributed respectively according to the same period T, T'. This makes it possible to have a simpler manufacturing process than if they were of different sizes.

[0077] The width w is equal to the fill factor Ff divided by the period T or T'. The fill factor Ff is also called "Fill Factor" in English. We thus have Ff=w / T=w / T'.

[0078] Thus, in a non-limiting embodiment:- for λ=455nm, h= 459nm, w=138nm, α= 30°, T = 402nm, n'=1.6, Ff=0.513.- for λ=528nm, h= 298nm, w=285nm, α= 42°, T = 470nm, n'=1.59, Ff=0.4967. It should be noted that the value of 528nm corresponds to the wavelength of an LED light source used in the automotive field.- for λ=621nm, h=353nm, w=213nm, α= 44.2°, T = 556nm, n'=1.58, Ff=0.383.- for λ=631nm, h= 364nm, w=210nm, α = 45°, T = 565nm, n'=1.58, Ff=0.635.

[0079] Thus, the first optical patterns 1110 are defined by the first tilt angle α, the fill factor Ff, and the height h. Thus, in the same way, the second optical patterns 1110 are defined by the second tilt angle α', the fill factor Ff, and the height h.

[0080] The first optical patterns 1110 and the second optical patterns 1120 are integrally formed with the body 110 of said light guide 11. This simplifies manufacturing while increasing mechanical strength. By integrally formed, it is meant that they are of the same material as the body 110 of the light guide 11 or that they are formed in the mass of the body 110 of the light guide 11.

[0081] In a first embodiment illustrated in Figures 1 and 4, the light input network 111 and the light output network 112 are arranged on the same surface 11.1 of the light guide 11, namely on the same surface 11.1 of the body 110. In the non-limiting example illustrated, they are arranged on the first surface 11.1 which is turned towards the first direction D. Thus, the coupling of the light at the input of the light guide 11 with the light input network 111 takes place on the same side as the coupling of the light at the output of the light guide 11 with the light output network 112.

[0082] In this first non-limiting embodiment, |α'+α| = 180°. The first optical patterns 1110 are inclined in one direction and the second optical patterns 1120 are inclined in the other direction.

[0083] In a first non-limiting embodiment illustrated in the, the first optical patterns 1110 and the second optical patterns 1120 protrude relative to a surface, here the first surface 1.1 or also called the base 1.1, of the light guide 11. They thus form protrusions relative to the body 110 and originate from one of its faces, here the first surface 1.1. The first optical patterns 1110 and the second optical patterns 1120 have the same light refraction index. The first optical patterns 1110 and the second optical patterns 1120 are of the same material as the body 110. Thus, in a non-limiting example, if the body 110 is made of PC, the first optical patterns 1110 and the second patterns 1120 are also made of PC.

[0084] In this first non-limiting embodiment, as illustrated in the, the first tilt angle α is the angle between the surface of the light guide 11 on which the first optical patterns 1110 are arranged (here the first surface or the base 1.1) and the first inclined wall 1110.2 of a first optical pattern 1110, said first tilt angle α being defined in the counterclockwise direction. And, as illustrated in the, the second tilt angle α' is the angle between the surface of the light guide 11 on which they are arranged (here the first surface or the base 1.1) and the fourth inclined wall 1120.3 of a second optical pattern 1120, said second tilt angle α' being defined in the counterclockwise direction. The fourth inclined wall 1120.3 is located on the same side as the first inclined wall 1110.2. Here, in the illustrated example, the first and fourth inclined walls 1110.2 and 1120.3 are respectively the right wall of the first optical pattern 1110 and the right wall of the second optical pattern 1120. The terms “left” and “right” correspond respectively to the left and the right of the figures.

[0085] In this first non-limiting variant embodiment, in a non-limiting embodiment illustrated in 1a and 1a, the first optical patterns 1110 and the second optical patterns 1120 have a flat top. Their top is referenced respectively 1110.1 and 1120.1 in Figures 2 and 3. Furthermore, due to its parallelogram-shaped cross-section, the projection along the second direction D' of the first inclined wall 1110.2 of a first optical pattern 1110 onto a surface which is here the first surface 1.1 of the body 110 of the light guide 11 forms a first shadow zone z as illustrated in 1a. Likewise, due to its parallelogram-shaped cross-section, the projection along the second direction D' of the third inclined wall 1120.2 of a second optical pattern 1120 onto a surface which is here the first surface 1.1 of the body 110 of the light guide 11 forms a second shadow zone z' as illustrated in the.Thus, a shadow zone z, z' is defined by the projection of an inclined wall 1110.2, 1120.2 respectively of an optical pattern 1110, 1120 on a surface of the body 110 of the light guide 11 and which is hidden when an observer observes from the outside the light assembly 3 comprising the light device 1 with the light guide 11.

[0086] It will be noted that to produce these first optical patterns 1110 and second optical patterns 1120 in projection, in non-limiting embodiments, the following manufacturing methods can be used: - electron beam lithography called in English "e-beam lithography" after the deposition of a non-photoresist layer on the body 110 of the light guide 11, layer of the same material therefore of the same refractive index of light n' to make a photomask called in English "master", or - laser engraving called in English "etching" after the deposition of a non-photoresist layer on the body 110 of the light guide 11, layer of the same material therefore of the same refractive index of light n' to make the photomask.

[0087] We thus etch at nanometric scale directly in this non-photoresistive layer. Thus, for the photomask, we etch each first optical pattern 1110 and each second optical pattern 1120 one by one.

[0088] It will be noted that these two manufacturing methods make it possible in particular to produce the first optical patterns 1110 and the second optical patterns 1120 which have first shadow zones z and second shadow zones z'. Indeed, the electron beam or the laser beam can be oriented to form the first optical patterns 1110 and the second optical patterns 1120 with inclined walls whose vertical projections respectively create these first shadow zones z and second shadow zones z', unlike a conventional UV illumination method otherwise known in English as "grey scale lithography".

[0089] The light device 1 comprises only one light output network 112 arranged on the first surface 1.1 of the light guide 11.

[0090] In a second non-limiting variant embodiment illustrated in the, the first optical patterns 1110 and the second optical patterns 1120 are hollow relative to a surface, here the first surface 1.1, of the light guide 11. They thus form ribs in the body 110. They are hollowed out in the body 110. They are formed in the mass of the body 110 of the light guide 11. The first optical patterns 1110 and the second optical patterns 1120 are here less exposed to the environment which prevents them from being damaged.

[0091] In this second non-limiting variant embodiment, in a non-limiting embodiment illustrated in 1a and 1a, the first optical patterns 1110 and the second optical patterns 1120 have a flat base. Their base is thus referenced respectively 1110.1 and 1120.1 in Figures 5 and 6. Furthermore, due to its parallelogram-shaped cross-section, the projection along the second direction D' of the first inclined wall 1110.2 of a first optical pattern 1110 onto a surface which is here the base 1110.1 forms a first shadow zone z as illustrated in 1a. Likewise, due to its parallelogram-shaped cross-section, the projection along the second direction D' of the third inclined wall 1120.2 of a second optical pattern 1120 onto a surface which is here the base 1120.1 forms a second shadow zone z' as illustrated in the.

[0092] In this second non-limiting embodiment, as illustrated in the, the first tilt angle α is the angle between the base 1110.1 of a first optical pattern 1110 and its first inclined wall 1110.2, said first tilt angle α being defined in the counterclockwise direction. And, as illustrated in the, the second tilt angle α' is the angle between the base 1120.1 of a second optical pattern 1120 and its fourth inclined wall 1120.3, said second tilt angle α' being defined in the counterclockwise direction.

[0093] It will be noted that to produce these first optical patterns 1110 and second optical patterns 1120 in hollow form, in non-limiting embodiments, the following manufacturing methods can be used: - electron beam lithography called in English "e-beam lithography" to make a photomask called in English "master", - laser engraving called in English "etching" to make the photomask.

[0094] We thus dig at nanometric scale directly into the body 110 of the light guide 11. Thus, for the photomask, we dig each first optical pattern 1110 and each second optical pattern 1120 one by one.

[0095] It will be noted that these two manufacturing methods make it possible in particular to produce the first optical patterns 1110 and the second optical patterns 1120 which have first shadow zones z and second shadow zones z'. Indeed, the electron beam or the laser beam can be oriented to form the first optical patterns 1110 and the second optical patterns 1120 with inclined walls whose vertical projections respectively create these first shadow zones z and second shadow zones z', unlike a conventional UV illumination method otherwise known in English as "grey scale lithography".

[0096] In a second embodiment illustrated in Figures 7 and 8, the light input network 111 and said light output network 112 are arranged on different faces 11.1, 11.2 of the light guide 11. Thus, in the non-limiting example illustrated in Figures 7 and 8, the light input network 111 is arranged on the second surface 11.2 facing the second direction D' and the light output network 112 is arranged on the first surface 11.1 facing the first direction D. Thus, the coupling of the light entering the light guide 11 with the light input network 111 is done on the opposite side to the coupling of the light leaving the light guide 11 with the light output network 112.

[0097] In this second non-limiting embodiment, |α'|+|α|=180°. The complementarity relationship between the two inclination angles α and α is always respected even when the first optical patterns and the second optical patterns 1120 are inclined in the same direction. Indeed, the first optical patterns 1110 are inclined in one direction and the second optical patterns 1120 are inclined in the same direction.

[0098] In a first non-limiting embodiment illustrated in the, the first optical patterns 1110 and the second optical patterns 1120 protrude relative to a surface of the light guide 11. They thus form protrusions relative to the body 110 and originate from one of its faces. The first optical patterns 1110 and the second optical patterns 1120 are of the same material as the body 110.

[0099] In this first non-limiting variant embodiment, the first optical patterns 1110 protrude relative to the second surface 1.2 of the light guide 11, and the second optical patterns 1120 protrude relative to the first surface 1.1 of the light guide 11. Furthermore, due to its parallelogram-shaped cross-section, the projection along the first direction D of the first inclined wall 1110.2 of a first optical pattern 1110 onto a surface which is here the second surface 1.2 of the body 110 of the light guide 11 forms a first shadow zone z as illustrated in the. Likewise, due to its parallelogram-shaped cross-section, the projection along the second direction D' of the third inclined wall 1120.2 of a second optical pattern 1120 onto a surface which is here the first surface 1.1 of the body 110 of the light guide 11 forms a second shadow zone z' as illustrated in the.

[0100] In this first non-limiting embodiment, as illustrated in the, the first tilt angle α is the angle between the surface of the light guide 11 on which the first optical patterns 1110 are arranged (here the second surface 1.2) and the first inclined wall 1110.2 of a first optical pattern 1110, said first tilt angle α being defined in the counterclockwise direction. And, as illustrated in the, the second tilt angle α' is the angle between the surface of the light guide 11 on which the second optical patterns 1120 are arranged (here the first surface 1.1) and the fourth inclined wall 1120.3 of a second optical pattern 1120, said second tilt angle α' being defined in the clockwise direction. Note that you have to look at it upside down for this first variant of making it, namely by turning it vertically.

[0101] In this first non-limiting variant embodiment, the first optical patterns 1110 and the second optical patterns 1120 have a flat top respectively referenced 1110.1 and 1120.1 as illustrated respectively in Figures 2 and 3.

[0102] The light device 1 comprises only one light output network 112 arranged on the first surface 1.1 of the light guide 11.

[0103] In a second non-limiting variant embodiment illustrated in the, the first optical patterns 1110 and the second optical patterns 1120 are hollow relative to a surface of the light guide 11. They thus form ribs or slots in the body 110. They are hollowed out in the body 110. They are formed in the mass of the body 110 of the light guide 11.

[0104] In this second non-limiting variant embodiment, the first optical patterns 1110 are hollow relative to the second surface 1.2 of the light guide 11, and the second optical patterns 1120 are hollow relative to the first surface 1.1 of the light guide 11.

[0105] This second non-limiting embodiment variant may include the elements of a non-limiting embodiment illustrated in 1 and 1a. In 1 and 1a, the first optical patterns 1110 and the second optical patterns 1120 have a flat base. Their base is thus referenced respectively 1110.1 and 1120.1 in Figures 5 and 6. Furthermore, due to its parallelogram-shaped cross-section, the projection along the second direction D' of the first inclined wall 1110.2 of a first optical pattern 1110 onto a surface which is here the base 1110.1 forms a first shadow zone z as illustrated in 1a. Likewise, due to its parallelogram-shaped cross-section, the projection along the first direction D of the third inclined wall 1120.2 of a second optical pattern 1120 onto a surface which is here the base 1120.1 forms a second shadow zone z' as illustrated in the.

[0106] In this second non-limiting embodiment, as illustrated in the, the first inclination angle α is the angle between the base 1110.1 of a first optical pattern 1110 and its first inclined wall 1110.2, said first inclination angle α being defined in the counterclockwise direction. And, as illustrated in the, the second inclination angle α' is the angle between the base 1120.1 of a second optical pattern 1120 and its fourth inclined wall 1120.3, said second inclination angle α' being defined in the clockwise direction. It will be noted that it is necessary to look at the upside down for this second embodiment of the, namely by turning it vertically.

[0107] This is a top view of a light device 1 comprising a surface light guide 11 applied to the cases of figures 1, 4, 7 or 8. The light output network 112 can be seen next to the light input network 111 which is located in the center of the body 110 which is in the form of a light guide sheet in the case of a surface light guide 11.

[0108] In a non-limiting embodiment illustrated in the, the light device 1 further comprises a light collimator 12 arranged between the light source 10 and the light guide 11 so as to form a first collimated light beam Fx'' which arrives with a normal incidence on said light input grating 111. The light collimator 12 makes it possible to straighten the light rays R from the light source 10 so that they arrive at normal incidence on the light input grating 110 of the light guide 11. Consequently, this makes it possible to recover a plane light wave at the input of the light guide 11 which increases the luminous efficiency of the light guide 11.In non-limiting embodiments, the light collimator is an MLA collimator which is the acronym for “Matrix Lens Array” in English or a light collimator composed of vertical cavity laser diodes referenced VCSEL which is the acronym for “Vertical Cavity Surface Emitting Lasers” in English.

[0109] Of course, the description of the invention is not limited to the embodiments described above and to the field described above.

[0110] Thus, the invention described has in particular the following advantages: - it makes it possible to increase the efficiency of the light collection at the input of the light guide 11 and the efficiency of the light at the output of the light guide 11. Thus, according to the experiments, an input efficiency of up to substantially 94% is obtained, namely the light emitted by the light source 10 enters the light guide 11 at 94%; and an output efficiency of between 80% and up to substantially 95% is obtained, namely the light emerges between 80% and 95% from the light guide 11 compared to the light propagated in the light guide 11, - it makes it possible to reduce light losses and is thus to be more efficient than a light device which would comprise a surface light guide with a light guide sheet and folded light injection elements, known to those skilled in the art, to form a stack through which the light rays from the light source enter.Indeed, in the case of folded light injection elements and thus comprising a fold, the light rays from the light source which reach this fold are not reflected towards the light guide sheet, hence a loss in luminous efficiency, - it reduces the manufacturing process time by nanoimprint for replica parts of the photomask as well as their manufacturing cost compared to a solution which would use an additional photoresist material layer (material different from the light guide) to create a light input network and a light output network, an additional material layer which would subsequently be etched by ultraviolet to create the protuberances or ribs on the surface of the light guide, - it thus makes it possible to have a more efficient light device 1.

Claims

Light device (1) for a vehicle (2), said light device (1) comprising:- a light source (10) configured to emit light rays (R),- a light guide (11) comprising a body (110) configured to propagate said light rays (R) emitted by said light source (10),characterized in that said light guide (1) further comprises:- a light input grating (111) by diffraction comprising a plurality of first optical patterns (1110) inclined so that for each first optical pattern, a first inclination angle (α) is defined between a first inclined wall (1110.2) of said first optical pattern and a base (1.1; 1110.1) of the light guide from which the first optical pattern protrudes; , said first optical patterns (1110) being periodically repeated according to a first period (T) and integral with said body (110) of said light guide (11), - a light output grating (112) by diffraction comprising a plurality of second optical patterns (1120) inclined according to a second angle of inclination (α') so that for each second optical pattern, a second angle of inclination (α) is defined between a fourth inclined wall (1120.3) of said second optical pattern and a base (1.1; 1120.1) of the light guide from which the second optical pattern projects, said fourth inclined wall being located on the same side as said first inclined wall; said second optical patterns (1120) repeated periodically according to a second period (T') equal to the first period (T) and being integral with said body (110) of said light guide (11), said first inclination angle (α) and said second inclination angle (α') being complementary with respect to 180°, in the same direction or in the opposite direction, and in that said light source (10) is arranged opposite said light input network (111) so that the light rays (R) enter said light input network (111). A light device (1) according to claim 1, wherein said light input array (111) and said light output array (112) are arranged on a same surface (11.1) of the light guide (11). Light device (1) according to claim 1, wherein said light input array (111) and said light output array (112) are arranged on different surfaces (11.1, 11.2) of the light guide (11). Light device (1) according to any one of claims 1 to 3, wherein said first optical patterns (1110) and said second optics (1120) protrude from a surface (1.1, 1.2) of said light guide (11). Light device (1) according to any one of claims 1 to 3, wherein said first optical patterns (1110) and said second optics (1120) are recessed relative to a surface (1.1, 1.2) of said light guide (11). A light device (1) according to any preceding claim, wherein said first optical patterns (1110) and said second optics (1120) are of the same size. A light device (1) according to any preceding claim, wherein said first patterns (1110) and said second patterns (1120) have a parallelogram-shaped cross-section. A light device (1) according to any preceding claim, wherein said light device (1) further comprises a light collimator (12) disposed between said light source (10) and said light guide (11) so as to form a first collimated light beam (Fx'') which arrives with normal incidence on said light input array (111). A light device (1) according to any preceding claim, wherein said light device (1) comprises a single light output array (112). A light device (1) according to any preceding claim, wherein said light source (10) is monochromatic. A light device (1) according to any preceding claim, wherein said light guide (11) is a surface light guide and said body (110) is in the form of a light guide sheet. Light assembly (3) for a vehicle (2), characterized in that said light assembly (3) comprises said light device (1) according to any one of the preceding claims. Light assembly (3) according to claim 12, wherein said light assembly (3) is a front face or a rear face of a vehicle (2) or a headlight or a rear light of a vehicle (2). Lighting assembly (3) according to claim 12, wherein said lighting assembly (3) forms part of an element of the passenger compartment of said vehicle (2).

Images