Flexible surface light guide for vehicle

Abstract

The invention relates to a flexible surface light guide (1) for a vehicle (3), comprising:-light injection elements (100) in a plurality of groups (10) and a light guide sheet (11), each group (10) being coupled to at least one light source (20). According to the invention, the light guide sheet (11) comprises a plurality of regions (110), at least one light emitting region (111) being incorporated into at least one region (110), the light guide sheet (11) being adjacent to the light injection element (100), each group (10) being configured to illuminate a region (110) in the light guide sheet (11). The length (Lg ') of the light injection elements (100) in one group (10) that irradiates the region (110) is different from the length of the light injection elements (100) in the other group (10) that irradiates the other region (110).

Description

[0001] The present invention relates to an optical waveguide for a vehicle. The present invention is particularly applicable to, but not limited to, motor vehicles.

[0002] Examples of optical waveguides known to those skilled in the art are shown in Figure 1 , and are provided with reference numeral 5. This optical waveguide 5 is used, for example, in decorative objects in order to illuminate these decorative objects, and comprises:

[0003] - a plurality of groups 50 of light injection elements 500, each group 50 being coupled to at least one light source 60,

[0004] - a light guide plate 51, which comprises a plurality of regions 510 and light-emitting regions 511 incorporated into the regions 510, the light guide plate 51 being adjacent to the light injection elements 500, and each group 50 being configured to illuminate a region 510 in the light guide plate 51.

[0005] Each group 50 is designed in the same way: the light injection elements 500 in the group 50 are adjacent to one another and have different lengths, the greater the distance from the light source 60, the longer the length. Moreover, the length of each light injection element 500 in the group 50 is the same as the length of another light injection element 500 in another group 50. The light injection elements 500 in the group 50 are folded and stacked in order to form a stack having ends. Thus, each light injection element 500 comprises a fold. The at least one light source 60 coupled to the group 50 is configured to emit light rays, which enter via the ends of the stack and can thus propagate in the light injection elements 500 until the light guide plate 51. As Figure 1 shows, the at least one light source 60 coupled to each group 500 is arranged on an electronic carrier 61. Thus, there are as many electronic carriers 61 as there are groups 50 of light injection elements 500. As Figure 1 shows, there are three groups 50 of light injection elements 500, and thus there are three electronic carriers 61. Two electronic carriers 61 are located between two groups 50. Each light source 60 has a luminous power of approximately 80 lumens.

[0006] A disadvantage of this prior art is that the light sources 60 used are too low in power for motor vehicle applications, and there is no space between the groups 50 of light injection elements 500 to arrange light sources with higher power (and thus larger), as well as suitable electronic carriers and suitable heat sinks (also larger) for dissipating the heat generated by these higher power light sources.

[0007] Against this background, the present invention aims to propose an optical waveguide that can overcome the above disadvantages.

[0008] To this end, the present invention proposes a flexible surface light guide for a vehicle, the light guide comprising:

[0009] - light injection elements grouped into a plurality of groups and a light guide plate, each group being coupled to at least one light source, characterized in that:

[0010] - the light guide plate includes a plurality of regions, at least one light emitting region being incorporated into at least one of the regions, the light guide plate being adjacent to the light injection elements, each group being configured to irradiate a region in the light guide plate,

[0011] and the length of the light injection elements in the group irradiating a region is different from the length of the light injection elements in other groups irradiating another region.

[0012] Thus, as will be seen in detail below, due to the fact that the length of each light injection element varies from group to group, at least one of the light sources coupled to the light injection elements can be positioned away from the light guide plate, such that the light sources are placed in a less restricted space and thus the position limitations are overcome. Thus, an electronic carrier large enough to accommodate all the light sources can be provided, as well as a heat sink sized to cool the remote light source or the group of light sources.

[0013] According to non-limiting embodiments, the light guide may also have one or more of the following additional features, individually or in any technically possible combination.

[0014] According to non-limiting embodiments, in the light injection elements of each group, the light injection elements are folded so as to form a stack having a thickness adapted to the emission surface of the light source, the stack having an entrance surface configured to receive the light emitted by the light source.

[0015] According to non-limiting embodiments, the dimensions of the light injection elements are determined such that when the light injection elements in each group in the group are folded, the entrance surfaces of the grouped light injection elements are at the same level.

[0016] In this way, the light sources arranged facing these entrance surfaces can be positioned substantially at the same level, which means that the installation of the entire system can be simplified. In particular, when the light injection elements grouped into a plurality of groups are arranged on the same side of the light guide plate, for simplicity, the light sources (since they are at the same level) can be mounted on the same printed circuit board. Moreover, since all the light sources are on the same carrier, a support surface can be provided such that: the support surface is larger than the support surface of each individual carrier of the light sources when the light sources are at different levels. The large support surface allows the heat sink to be associated with a high heat dissipation capacity, which avoids overheating of the light sources and allows these light sources to be used for a long time.

[0017] For example, the light guide plate extends in a first direction and a second direction, and these directions form the extension plane of the light guide plate. Regarding the light injection elements, in the unfolded state, they mainly extend in the first direction. To achieve the folded state, the light injection elements are folded in the second direction in the same manner. The dimension of the length of the light injection elements measured in the first direction is determined such that in the folded state, the entrance surfaces of the grouped light injection elements are at the same level, i.e., at the same position on the axis in the second direction. In addition, the entrance surfaces are positioned at different positions on the axis in the first direction.

[0018] According to a non - limiting embodiment, the mounting position of the light guide can be on the front of the vehicle, in which the extension plane of the light guide plate is perpendicular to the longitudinal axis of the vehicle. In this way, the entire surface of the light guide plate in the extension plane can be seen from the outside of the vehicle. The light guide plate has a plurality of regions, and each region is combined with a light - emitting region. These regions are arranged offset in the second direction, and the number of regions corresponds to the number of groups formed by the injection elements.

[0019] According to a non - limiting embodiment, the light guide is transparent.

[0020] According to a non - limiting embodiment, the at least one light - emitting region forms at least one pattern.

[0021] According to a non - limiting embodiment, the light injection elements in multiple groups are arranged on the same side of the light guide plate and thus form a first group of light injection elements.

[0022] According to a non - limiting embodiment, the light injection elements in multiple groups are arranged on the first side of the light guide plate and thus form a first group of light injection elements, wherein the light guide includes a second group identical to the first group, and the second group is arranged on the second side of the light guide plate opposite to the first side so as to be symmetric with respect to the first group relative to the light guide plate.

[0023] According to a non - limiting embodiment, the light source is coupled to at least one light collimator. This allows reducing the light loss of the light source and thus improving the efficiency of light propagation.

[0024] According to a non - limiting embodiment, a group of light sources coupled to a group is powered by a current different from that of other groups of light sources coupled to other groups. This allows creating animations.

[0025] In a non - limiting embodiment, the light source is a semiconductor light source.

[0026] According to a non - limiting embodiment, the light sources can be enabled independently of each other. This allows creating animations.

[0027] Moreover, a lighting device for a vehicle is proposed, characterized in that the lighting device comprises at least one light guide according to any one of the foregoing features, a plurality of light sources, and at least one heat sink.

[0028] According to non - limiting embodiments, the lighting device may further comprise one or more of the following additional features implemented separately or in any technically possible combination.

[0029] According to non - limiting embodiments, the light sources are arranged on the same electronic carrier.

[0030] According to non - limiting embodiments, the light sources are arranged on the same plane of the same electronic carrier.

[0031] According to non - limiting embodiments, each light source is arranged on a plane of the same electronic carrier that is different from the planes of the other light sources.

[0032] According to non - limiting embodiments, the lighting device comprises at least two superimposed light guides oriented in opposite directions to each other.

[0033] According to a non - limiting embodiment of the lighting device,

[0034] - In each group of light injection elements, the light injection elements are folded so as to form a stack having a thickness adapted to the emission surface of the light source, the stack having an inlet surface for receiving the light emitted by the corresponding light source,

[0035] - The dimensions of the light injection elements are determined such that when the light injection elements in each group are folded, the inlet surfaces are at the same level.

[0036] The invention and its various applications will be more clearly understood by reading the following description and studying the drawings:

[0037] Figure 1 is a schematic view of a light guide according to the prior art, the light guide comprising groups of light injection elements coupled to a light source and a light guiding sheet,

[0038] Figure 2 is a schematic view of a light guide of a vehicle according to a first embodiment variant of a non - limiting embodiment of the invention, the light guide comprising three groups of light injection elements coupled to a light source and a light guiding sheet comprising a region and at least one light emitting region, the three groups of injection elements being arranged on the same side of the light guiding sheet,

[0039] Figure 3 is a schematic view of a light guide of a vehicle according to a first embodiment variant of a non - limiting embodiment of the invention, the light guide comprising six groups of light injection elements coupled to a light source and a light guiding sheet comprising a region and at least one light emitting region, the six groups of injection elements being arranged on the same side of the light guiding sheet,​​​

[0040] Figure 4 is a schematic view of an optical waveguide of a vehicle according to a second exemplary variation of a non - limiting embodiment of the present invention. The optical waveguide includes six groups of light injection elements coupled to a light source and a light guide plate including a region and at least one light - emitting region. The six groups of injection elements are arranged on both sides of the light guide plate.

[0041] Figure 5 is according to Figure 2 、 Figure 3 、 Figure 4 or Figure 5 is an enlarged view of a part of the light injection elements of the optical waveguide.

[0042] Figure 6 is according to Figure 2 、 Figure 3 、 Figure 4 or Figure 5 is a front view of a stack of light injection elements within the same group of light injection elements of the optical waveguide.

[0043] Figure 7 shows the optical waveguide in Figure 2 according to a non - limiting embodiment, wherein the light injection elements are unfolded.

[0044] Figure 8 is of some light injection elements in a group of the optical waveguide according to Figure 2 、 Figure 3 、 Figure 4 or Figure 5 in a non - limiting embodiment, and is an enlarged perspective view.

[0045] Figure 9 is a schematic view of an optical waveguide in Figure 2 according to a first non - limiting embodiment of a pattern. The light guide plate includes three regions having three light - emitting regions forming a pattern.

[0046] Figure 10 is a schematic view of an optical waveguide in Figure 2 according to a second non - limiting embodiment of a pattern. The light guide plate includes three regions having three light - emitting regions forming three patterns.

[0047] Figure 11 is a schematic view of a lighting device of a vehicle according to a first exemplary variation of a first non - limiting embodiment of a lighting device. The lighting device includes Figure 2 the optical waveguide in

[0048] ​​​​​​​​​Figure 12 is according to a non - limiting embodiment Figure 11 a schematic representation of a light - emitting device in

[0049] Figure 13 is a schematic diagram of a light - emitting device of a vehicle according to a second embodiment variant of a first non - limiting embodiment of a light - emitting device, the light - emitting device including Figure 2 the light guide, light source, electronic carrier, and heat sink in

[0050] Figure 14 is a schematic diagram of a light - emitting device of a vehicle according to a second non - limiting embodiment of a light - emitting device, the light - emitting device including Figure 2 the light guide (the light guide includes two sets of grouped light injection elements arranged on both sides of the light - guiding sheet) in

[0051] Figure 15 is a schematic diagram of a light - emitting device of a vehicle according to a third non - limiting embodiment of a light - emitting device, the light - emitting device including two stacked Figure 14 light guides, light sources, four electronic carriers, and four heat sinks in

[0052] Unless otherwise specified, elements that are the same in structure or function and appear in different figures are denoted by the same reference numerals.

[0053] Reference Figures 2 to 15 describes the light guide 1 according to the present invention. The light guide 1 is a light guide for a vehicle 3. In a non - limiting embodiment, the vehicle 3 is a motor vehicle. A "motor vehicle" means any type of motorized vehicle. In the remainder of the specification, this embodiment is given as a non - limiting example. In the remainder of the specification, the vehicle 3 is thus also referred to as the motor vehicle 3. In a non - limiting embodiment variant, the vehicle 3 is an internal combustion engine vehicle or an electric vehicle.

[0054] The light guide 1 is sheet - shaped and flexible. Thus, it can be adapted to any type of flat or curved surface. The light - guiding sheet should be understood to mean an optical guiding element, one of whose dimensions is much smaller in space than the other two dimensions, for example, one or more orders of magnitude smaller. Here, the thickness e of the light guide 1 is much smaller than its length Lg and its width La. In a non - limiting embodiment, the light guide 1 has a thickness e between 10 micrometers and 1000 micrometers (shown in Figure 6 ). In a non - limiting embodiment variant, the thickness e is between 50 micrometers and 1000 micrometers. In a non - limiting example, the thickness e is 50 micrometers. Thus, the light guide 1 is very thin.

[0055] ​​​In a non - limiting embodiment, the light guide 1 is transparent. Thus, the light guide 1 is also referred to as the transparent film 1. Since the light guide is transparent, light can pass through it. Because the light guide 1 is transparent, when the light guide 1 is not lit, i.e., when it is not emitting light, a pattern (referred to as the manufacturer pattern) can be seen through the light guide 1, and this pattern (if provided in a motor vehicle) is incorporated into the front of the motor vehicle 3 or into the headlight or taillight. This also allows the color of the body of the motor vehicle 3 to be maintained when the light guide 1 is not lit. At night, in order to illuminate the manufacturer pattern, the light guide 1 includes a pattern 111 (described below), which can be the same as the manufacturer pattern and thus allows the manufacturer pattern to be illuminated.

[0056] Since the light guide 1 is sheet - like, flexible and transparent, the light guide is configured to be placed on the front of the motor vehicle 3 (as Figure 11 shown), or also placed on the headlight of the motor vehicle 3 (as Figure 13 shown) or the taillight (as Figure 12 shown). In a first non - limiting embodiment, the light guide 1 is bonded. In a variant of the first non - limiting embodiment, the surface on which the light guide 1 is placed (such as the outer lens of the front, the outer lens of the headlight, the outer lens of the taillight) includes an adhesive surface for bonding the light guide 1. In a second variant of the non - limiting embodiment, the back surface of the light guide 1 includes an adhesive surface and is bonded behind the decorative piece. In a third variant of the non - limiting embodiment, both surfaces of the light guide 1 are sticky. In a second non - limiting embodiment, the light guide 1 is not bonded but is held between the outer lens and the decorative piece.

[0057] In a non - limiting embodiment, the light guide 1 is made of polycarbonate (PC), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU) or polyethylene terephthalate (PET). Such materials allow the production of a transparent and flexible light guide 1.

[0058] As Figure 2 、 Figure 3 and Figure 4 shown, in a non - limiting embodiment, the light guide 1 extends along the axis z over its width La and along an axis y that is substantially perpendicular to the axis x over its length Lg. It should be noted that the width La and the length Lg can be equal.

[0059] As Figure 2 、 Figure 3 and Figure 4 shown, the light guide 1 includes:

[0060] - a plurality of light injection elements 100 grouped into groups 10, and

[0061] - a light guide sheet 11, which includes a plurality of regions 110.

[0062] The light guide 11 extends in a first direction y and a second direction z. In a non-limiting embodiment, in the deployed state, the light injection element 100 mainly extends in the first direction y. Thus, the dimension measured in this first direction y is considered to be the length Lg' of the light injection element 100 as Figure 7 shown.

[0063] It should be noted that during the production process of the light guide 11, the light injection element 100 and the light guide 11 are made from a large sheet, which will be trimmed at one end in order to separate different light injection elements 100 along the Figure 7 shown axis y, and thus form different light injection elements 100 and light guides 11. Thus, the light injection element 100 remains attached to the light guide 11 at one of its ends 100.1.

[0064] The large sheet forming the light guide 11 and the light injection element 100 includes a flexible film and envelope layers arranged on both sides of the flexible film. A glue layer or adhesive layer is positioned between the flexible film and the envelope layers. The refractive index of the glue layer or adhesive layer is different from the refractive index of the flexible film in order to cause light rays to propagate in the flexible film by total internal reflection; thus, the name "light guide" is used to denote the assembly of the light guide sheet and the light injection element.

[0065] The group 10 and the light injection element 100 are described below.

[0066] In a non-limiting embodiment, the number of groups 10 is between two and twenty.

[0067] It should be noted that compared with Figure 2 , Figure 4 and Figure 14 which show ten light injection elements in each group, in the Figures 7 to 13 and Figure 15 shown examples, only eight light injection elements 100 are shown in each group 10.

[0068] Each group 10 is configured to irradiate an area 110 (described below) in the light guide 11.

[0069] The group 10 may include one or more light injection elements 100. In a non-limiting embodiment, the group includes between three and ten light injection elements 100. In a non-limiting variant embodiment, the group includes ten light injection elements 100. In the Figure 2 and Figure 4 non-limiting examples, the light guide 1 includes three groups 10, and each group includes ten light injection elements 100. In the Figure 3 non-limiting example, the light guide includes six groups 10, and each group includes five light injection elements 100. Compared withFigure 2 and Figure 4 Compared with the example of Figure 4 , the number of groups 10 has doubled, so the number of optical injection elements 100 per group 10 has been halved. For clarity, only one optical injection element 100 is provided with a reference numeral.

[0070] Each group 10 is coupled to at least one light source 20. The at least one light source 20 is configured to emit light rays R (shown in Figure 6 and Figure 8 ), and these light rays will propagate through total internal reflection in the optical injection elements 100 in group 10 to transfer light to the light guide plate 11 adjacent to the optical injection elements 100, and thus irradiate the area 110 of the light guide plate 11. In a non-limiting embodiment, each group 10 is coupled to a plurality of light sources 20. In another non-limiting embodiment, each group 10 is coupled to a single light source 20. In the following description and in the non-limiting examples of Figure 2 , Figure 3 and Figure 4 , the latter non-limiting embodiment is taken as a non-limiting example.

[0071] As shown in Figure 6 , the optical injection element 100 (also referred to as the coupling bar 100 or the light bar 100 or simply the bar 100) is configured to receive the light rays R emitted by the light source 20, and these light rays propagate in the optical injection element 100 and are totally internally reflected. The optical injection element 100 has a rectangular or square cross-section. The optical injection element 100 includes a length Lg' and a width La' (both shown in Figure 8 ) and a thickness e (shown in Figure 6 ). The thickness e of the optical injection element is the same as the thickness e of the light guide 1. The optical injection element 100 includes two ends 100.1, one of which is directly adjacent to and attached to the light guide plate 11, and the other end is configured to face the light source 20. The light rays R emitted by the light source 20 are incident via the end 100.1 and transmitted to the other end 100.1, and then transmitted towards the light guide plate 11. For clarity, only the end 100.1 of the optical injection element 1008 in one group 10 is provided with a reference numeral.

[0072] Figure 8 shows three groups 10 each having eight optical injection elements (denoted as 1001 to 1008). As shown in Figure 8 ​As shown, the light injection element 100 in group 10 is adjacent to at least one other light injection element 100 in the group 10. The light injection elements 100 (i.e., 1001 and 1008) at the ends of group 10 are adjacent to a single light injection element 100 in the group 100, while the so-called intermediate light injection elements 100 (i.e., 1002 to 1007) not arranged at the ends of the group 100 are adjacent to two other light injection elements 100 in the group 10.

[0073] As Figure 7 shown, the light injection elements 100 in the same group 10 extend along the axis y when unfolded and have different positions pj in the +z direction, where j = 1 to N and N is an integer. The farther the light injection element 100 is from the light source 20, the higher its position pj. Thus, as Figure 8 shown by way of non-limiting example, the light injection element 1008 has the position p8, while the light injection element 1001 has the position p1.

[0074] For example, when the light guide 1 is arranged on the front of the motor vehicle 2, the surface of the light injection element 100 is perpendicular to the axis x. It should be noted that the axis x corresponds to the vehicle axis Ox.

[0075] As Figure 5 shown, the light injection element 100 is composed of:

[0076] - A main part 100.2 that extends along the axis y, i.e., in the first direction of the light guide plate 11 described below, and

[0077] - An end part 100.3 that extends along the axis z, i.e., in the second direction of the light guide plate 11 described below. The end part 100.3 is connected to the light guide plate 11. These two parts 100.2 and 100.3 are separated by a folding part 100.4. The end part 100.3 extends after the folding part 100.4. In a non-limiting embodiment, the folding part 100.4 is a right-angle folding part. The length Lg' of the light injection element 100 is the sum of the dimensions of the main part 100.2 and the end part 100.3.

[0078] Figure 5 shows the end part 100.3, the main part 100.2, and the folding part 100.4 that separates the end part and the main part of the light injection element 100 in group 10. Figure 5 shows the end parts 100.3 of ten light injection elements 100 in group 10 and the light source 20 coupled to the group 110.

[0079] ​The optical injection elements 100 in the same group 10 have different lengths Lg'. For clarity, in Figure 8 , only the length Lg' of the optical injection element 1008 is provided with an attached drawing reference numeral. Moreover, the length Lg' of the optical injection element 100 in the group 10 is different from the lengths of the other optical injection elements 100 in the same group 10. This allows the optical injection elements to be folded such that their end portions 100.3 form a stack 103 having a flat inlet surface 103.1, as shown in Figure 6 . The end portion 100.3 of the optical injection element 100 extends after the folding portion 100.4. In a non-limiting embodiment, the folding portion 100.4 is a right-angle folding portion.

[0080] Thus, each optical injection element 100 includes a folding portion 100.4. The inlet surface 103.1 of the stack 103 is formed by one of the ends 100.1 of each of the optical injection elements 100 in the group 10, and these ends are the ends of the end portions 100.3 of the optical injection elements.

[0081] As shown in Figure 6 , in each group 10, the optical injection elements 100 are folded such that their end portions 100.3 form a stack 103 having a thickness E suitable for the emission surface of the light source 20. The thickness E is the sum of the thicknesses e of each optical injection element 100, and the end portions 100.3 of each optical injection element form the stack 103. The stack 103 has an inlet surface 103.1, which is formed by the ends of the end portions 100.3 of each of the optical injection elements 100 in the group 110 and is configured to receive the light emitted by the light source 20.

[0082] As shown in Figure 6 and Figure 8 , in a non-limiting embodiment, the light source 20 coupled to the group 10 is arranged to face the inlet surface 103.1 of the stack 103. The light rays R of the light source 20 are incident through this inlet surface 103.1 and thus propagate in the optical injection element 100. The light rays R are totally reflected inside the optical injection element 100 and redirected towards the light guide plate 11 via the folding portion 100.4.

[0083] It should be noted that the farther the group 10 is from the light source 20, the greater the length Lg' of the optical injection element 100. Thus, the farthest optical injection element 1008 has the maximum length Lg', while the nearest optical injection element 1001 has the minimum length Lg'. In this way, a flat inlet surface 103.1 of the stack 103 can be obtained.

[0084] The optical injection elements 100 in the same group 10 have the same width La'.

[0085] When there are multiple groups 110, for all groups 10, the optical injection elements 100 are arranged in the same manner, that is:

[0086] - The optical injection elements are adjacent to each other and are folded with folding portions 100.4 to form a stack 103 having its flat inlet surface 103.1.

[0087] - The farther the group 10 is from the light source 20, the greater the length Lg' of the optical injection element 100. Therefore, the length Lg' of the optical injection element 100 gradually increases in the direction away from the light source 20. Thus, the optical injection element 100 farthest from the light source 20 has the maximum length Lg', while the nearest optical injection element 100 has the minimum length Lg'. In this way, a flat inlet surface 103.1 of the stack 103 can be obtained. Therefore, the optical injection elements 100 in the same group 10 have different lengths Lg'.

[0088] The length Lg' of the optical injection element 100 in the group 10 that irradiates the region 110 is different from the length of the optical injection element 100 in other groups 10 that irradiate another region 110.

[0089] In particular, the length Lg' of the optical injection element 100 located at the position pj in the group 10 that irradiates the region 110 is different from the length of the optical injection element 100 located at the same corresponding position pj in another group that irradiates another region 110. This allows the light sources 20 coupled to each group 10 to be positioned remotely from the light guide 1 so that these light sources can be placed at a single given location and so that these light sources can be arranged on a single electronic carrier 21, as Figure 8 shown. Since there is only a single electronic carrier 21, the number of connectors can be reduced because a single connector is sufficient. By reducing the number of connectors, the number of associated electrical connection harnesses can be reduced to a single electrical connection harness. In a non-limiting embodiment, the electronic carrier 21 is a PCBA (printed circuit board assembly). In a non-limiting example, the light sources 20 thus located farther away are arranged such that the light guides 10 are spaced between 10 cm and 50 cm apart.

[0090] In the application to a motor vehicle 3, this allows the light sources 20 and the electronic carrier 21 to be placed remotely in a position with space behind the front or in a position with space behind the headlamp or taillight. Therefore, light sources 20 with high luminous power can be used, which are suitable for the application to the motor vehicle 3 and are thus larger than the light sources of the prior art. Therefore, heat sinks 22 can be used (in Figure 8As shown in [figure reference], the heat sink is suitable for dissipating the heat emitted by the high-power light source 20 without being restricted by space. In a non-limiting embodiment, the luminous flux of each light source 20 in the light source 20 is 400 lumens. In a non-limiting embodiment, in addition to the heat sink 22, a fan (not shown) can also be used to cool the light source 20.

[0091] It should be noted that since higher-power light sources 20 can be used, the light guide plate 11 (described below) having multiple regions 110 can have a large surface area and can thus efficiently irradiate different regions 110. Therefore, the light guide 1 can be used, for example, for the front, headlight, or taillight of a motor vehicle 3 that extends over a large area.

[0092] It should be noted that since the length Lg' of the light injection element 100 in the group 10 that irradiates the region 110 is different from the length of the light injection element 100 in other groups 10 that irradiate other regions 110, when the light injection element 100 is folded at its corresponding end portion 100.3, the position of the light injection elements in this group along the axis y (if these light injection elements are projected onto the axis y) can be different from the position of the light injection elements in other groups 10, while in the prior art, for all groups, the position of the light injection elements along the axis y is the same (if these light injection elements are projected onto the axis y). In the prior art, the entrance surfaces of the stack are aligned along the axis z but are at different levels on the axis z, while in the case of the described light guide 1, the entrance surface 103.1 of the stack 103 is aligned along the axis y and is at different positions on the axis y. In other words, the entrance surfaces 103.1 of the described light guides are laterally offset from each other.

[0093] In a non-limiting example where the light guide 1 includes three groups 10 Figure 2 , in a non-limiting embodiment, the length Lg' of the light injection element 100 included in the group 10 (also referred to as the third group 10) that is farthest from the light source 20 and irradiates the region 110 is different from the length of the light injection element 100 located at the same position pj in the group 10 (also referred to as the first group 10) that is closest to the light source 20 and irradiates another region 110. In other words, this set of light sources can be considered here as a reference point located towards the bottom of the drawing, and is generally on the side where the light injection elements point when folded in the folding direction. The group farthest from the reference point irradiates the region farthest from the reference point. Here, the length of each light injection element in the farthest group is greater than the length of the light injection element 100 located at the same position pj in the group 10 closer to the reference point.

[0094] In particular, as Figure 8As shown, the length Lg' of the strip 1001 at the position p1 in the third group 10 is greater than the length of the strip 1001 at the same position p1 in the first group 10, and the length Lg' of the strip 1008 at the position p8 in the third group 10 is greater than the length of the strip 1008 at the same position p8 in the first group 10. The same applies to the intermediate strips 1002 to 1007 located at the corresponding positions p2 to p7 respectively. Therefore, it can be determined that the entrance surfaces 103.1 of the stacks 103 of the two groups 10 are located at different positions along the axis y.

[0095] The length Lg' of the light injection elements 100 included in the intermediate group 10 (also referred to as the second group 10), which is located between the other two groups 10 and irradiates a region 110 different from the other two groups 10, is different from the length of the light injection elements 100 located at the same positions pj in the closest group 10. In particular, the length of the strip 1001 at the position p1 in the second group 10 is greater than the length of the strip 1001 at the same position p1 in the first group 10, and the length Lg' of the strip 1008 at the position p8 in the second group 10 is greater than the length of the strip 1008 at the same position p8 in the first group 10. The same applies to the intermediate strips 1002 to 1007 located at the corresponding positions p2 to p7 respectively. Therefore, it can be determined that the entrance surface 103.1 of the stack 103 is located at different positions of the two groups 10 along the axis y.

[0096] In a non-limiting embodiment, the thickness e of the light injection element 100 is about 50 μm (micrometers). In a non-limiting embodiment, the width La' of the light injection element 100 is between 1 mm and 20 mm. In a non-limiting embodiment, the length Lg' of the light injection element 100 is between 100 mm and 500 mm.

[0097] In a non-limiting embodiment, the width La' of the light injection elements 100 in the group 10 is different from the width of the light injection elements 100 in the other groups 10. This allows each group 10 to irradiate different areas of the region 110, and thus allows the use of different numbers and / or different sizes of light sources 20.

[0098] Now, the light guide plate 11 will be described below.

[0099] As Figure 2 、 Figure 3 and Figure 4 shown, the light guide plate 11 includes:

[0100] - A plurality of regions 110,

[0101] - At least one light emitting region 111 incorporated in at least one region 110.

[0102] Since the light guide 1 is sheet-shaped, flexible and transparent, the light guide sheet 11 is also sheet-shaped, flexible and transparent. Since the light guide sheet 11 is flexible, it can be flat or curved, depending on the position where the light guide sheet is placed and the mechanical stress applied thereto. In particular, it is suitable for the front of a motor vehicle 3 or a headlight or a taillight.

[0103] The light guide sheet 11 is adjacent to and attached to the light injection elements 100. Each region 110 is configured to be irradiated by the light injection elements 100 that form different groups 10. The different regions 110 are irradiated by the groups 10 of light injection elements 100 that have different sizes due to their different lengths Lg'.

[0104] The light guide sheet 11 further includes at least one light mixing region 112. The light leaving the light injection elements 100 that form the same group 10 will be mixed in the light mixing region 112, which allows the light emitting region 111 of the corresponding region 110 to be uniformly irradiated.

[0105] The region 110 includes the at least one light emitting region 111.

[0106] The light emitting region 111 is the region through which the light generated by the light rays R of the light source 20 of the group 10 passes and leaves the light guide sheet 11. In particular, in the non-limiting example considered, the light leaves towards the outside of the front of the motor vehicle 2 in the +x direction (i.e., substantially parallel to the vehicle axis Ox).

[0107] According to a non-limiting embodiment, the at least one light emitting region 111 forms at least one pattern (also referred to as pattern 111). In a non-limiting example, the pattern 111 has a size of 30×30 cm. In a non-limiting example, the pattern 111 is a logo or part of a logo. Thus, in this case, a light emitting logo is obtained. In a non-limiting embodiment, the pattern is formed by a microstructure. In a non-limiting example, such a microstructure can generally have an embossed or relief form where the light rays R are reflected. The microstructure is a nanostructure. In a non-limiting embodiment, the pattern 111 is the same as the above-mentioned manufacturer pattern. In this case, when the light guide 1 is placed on the front, the pattern 111 covers the manufacturer pattern. Thus, when one or more light sources 20 are enabled, the manufacturer pattern appears.

[0108] In Figure 9 and Figure 10 In a non-limiting example, the light guide sheet 11 includes three regions 110 and light emitting regions 111 respectively incorporated in the three regions 110.

[0109] Figure 9 ​Shows a first non - limiting example of an illuminated pattern as a logo. The first light - emitting region 111 forms the L of the logo here, the second light - emitting region 111 forms the O and G of the logo, and the third light - emitting region 111 forms the O of the logo here.

[0110] Figure 10 Shows a second non - limiting example of an illuminated pattern including a rhombus, a circle, and a square. The first light - emitting region 111 forms the rhombus, the second light - emitting region 111 forms the circle, and the third light - emitting region 111 forms the square.

[0111] The components of the light guide 1, the light source 20, the electronic carrier 21, and the heat sink 22 form Figures 11 to 15 the light - emitting device 2 shown.

[0112] Thus, the light - emitting device 2 includes:

[0113] - at least one of the above - mentioned light guides 1,

[0114] - a plurality of light sources 20, which are arranged on at least one same electronic carrier 21, and

[0115] - at least one heat sink 22.

[0116] The group 10 of the light guide 1 is coupled to one or more light sources 20. The assembly of the injection elements 100 of the group 10 and one or more associated light sources 20 is also referred to as the input coupler 13. Thus, the input coupler 13 is associated with each region 110 of the light - guiding sheet 11. For the sake of clarity, in Figures 11 to 13 only one input coupler 13 is provided with a reference numeral.

[0117] In a non - limiting embodiment, the light source 20 is a semiconductor light source. In a non - limiting embodiment, the semiconductor light source forms part of a light - emitting diode or a laser diode. "Light - emitting diode" refers to any type of light - emitting diode, by way of non - limiting examples, these light - emitting diodes include LED (light - emitting diode), OLED (organic LED), AMOLED (active - matrix organic LED), or FOLED (flexible OLED).

[0118] In a non - limiting embodiment, the light sources 20 can be enabled independently of each other. This allows each region 110 of the light - guiding sheet 10 to be illuminated independently of each other, and thus allows the creation of animations. Thus, in the example of Figure 9 , a light - emitting logo in the form of an animation can be created. Thus, in the example of Figure 10 , the rhombus, the circle, and the square can be illuminated alternately to create an animation.

[0119] ​According to an exemplary embodiment, the number of light sources 20 is adapted to the size (length Lg', width La', thickness e) of the light injection elements 100 in the group 10. Thus, the number of light sources 20 per group 10 may be the same, or the number of light sources 20 per group 10 may be different. Similarly, the size of the light sources 20 per group 10 may be different, or the size of the light sources 20 in all groups 10 may be the same. In a non-limiting example of the drawings, the number of light sources 20 per group 10 is the same, i.e., a single light source per group herein, and the light sources 20 have the same size. In a non-limiting example, the emission surface area of the light source 20 is 1 mm 2 . According to another exemplary embodiment, the number of light injection elements 100 is adapted to the number of light sources 20 needed to meet the desired brightness requirement.

[0120] Figure 11 , Figure 12 and Figure 13 show a first embodiment of the light-emitting device 1, in which:

[0121] - the light-emitting device 1 includes a single light guide 1,

[0122] - the light injection elements 100 in groups 10 of this light guide 1 are arranged on the same side of the light guide plate 11 and thus form a first group of light injection elements 100,

[0123] - the light sources 20 in all groups 10 are arranged on the same electronic carrier 21.

[0124] Since the light injection elements 100 in groups 10 are all arranged on the same side of the light guide plate 11, the corresponding light sources 20 are all arranged on the same side and thus can be placed on the same electronic carrier 21. Therefore, a single electronic carrier 21 is necessary. Therefore, a single heat sink 22 is used. Thus, in this first non-limiting embodiment, the light-emitting device 2 includes a single heat sink 22. Of course, multiple electronic carriers may also be provided.

[0125] In Figure 11 and Figure 12 the non-limiting example shown, there are three groups 10 and three light sources 20 respectively coupled to these three groups 10, and these three groups 10 are arranged on the same side 11.1 of the light guide plate 11. In a non-limiting example, the light guide plate 11 includes three regions 110. Each group 10 irradiates a different region 110.

[0126] In Figure 11In the first non - limiting variant embodiment of the first non - limiting embodiment shown, the light sources 20 are arranged on the same plane of the same electronic carrier 21. Thus, each light source 20 is located at the same distance d from the three inlet surfaces 103.1 of the three stacks 103 formed by the light injection elements 100 in the corresponding three groups 10.

[0127] Because there are light injection elements 100 in the groups 10 with different lengths Lg', there may be a risk of non - uniformity between the groups 10. In fact, the path taken by the light generated by the light rays R in the group 10 closest to the light source 20 is shorter than the path taken in the other two farther - away groups 10. Therefore, for the farthest group 10 where the light injection elements 100 are the longest, there may be an efficiency loss in light propagation. To maintain the efficiency of light propagation, in this non - limiting embodiment of the first variant, a set of light sources 20 coupled to a group 10 is powered by a current different from that of the other sets of light sources 20 coupled to the other groups 10. It should be reiterated that a set can include one or more light sources 20; in the current case, it includes only a single light source 20. Thus, in Figure 11 the non - limiting example shown, the light sources 20 of the group 10 are powered by a current different from that of the light sources 20 of the other groups 10. This means that each region 110 of the light guide plate has a specific current, herein denoted as i, i', i". The farther the group 10 is from the light source 20, the stronger the associated current i must be in order to maintain the efficiency of light propagation. Thus, the current i" is the strongest, while the current i is the weakest. In the non - limiting example, for the farthest group 10, the current i" is 260 mA, for the middle group, the current i' is 255 mA, and for the nearest group 10, the current i is 250 mA. Thus, the uniformity of global illumination on all regions 11 of the light guide plate 11 is ensured.

[0128] In Figure 12 the non - limiting embodiment of the variant of the first non - limiting embodiment shown, the light - emitting device 2 further includes at least one light collimator 23 coupled to the light source 20. The at least one light collimator 23 is arranged between the light source 20 and the above - mentioned stack 103. In particular, the at least one light collimator is arranged to face the inlet surface 103.1 of the stack 103. In the non - limiting embodiment, the light collimator 23 is an optical lens. As Figure 12As shown, the light-emitting device 2 includes three light collimators 23 of a light source 20 respectively coupled to light injection elements 100 grouped into three groups 10. Each light collimator 23 is arranged to face the stack 103, particularly the inlet surface 103.1 of the stack. When the light injection element 100 has a low thickness e (between 1 mm and 5 mm), the light collimator 23 allows reducing the light loss of the light source 20, thus improving the efficiency of light propagation. Moreover, the light collimator 23 serves as an intermediate member between the light source 20 and the inlet surface 103.1 of the stack 103. This makes it possible to avoid the light source 20 being too close to the inlet surface 103.1, as the light source being too close to the inlet surface may burn the inlet surface. Since the light source 20 is away from the light guide 11, there is room to add such a light collimator 23.

[0129] In Figure 13 a second non-limiting variant embodiment of this first non-limiting embodiment shown, each light source 20 is arranged on a different plane of the same electronic carrier 21 from the other light sources 20 and is powered by the same current i. The electronic carrier 21 thus includes steps, and each light source 20 is located on a different step. Thus, each light source 20 is located at a different distance (here d, d', d") from the three inlet surfaces 103.1 of the above three stacks 103. This allows maintaining the efficiency of light propagation. The light source 20 coupled to the group 10 furthest from the light source 20 is the light source arranged at the minimum distance d". The light source 20 coupled to the group 10 closest to the light source 20 is the light source arranged at the maximum distance d. In the non-limiting case of three light sources 20, in a non-limiting example, the light source 20 of the furthest group 10 is arranged at a distance d" of 0.4 mm (millimeters) from the inlet surface 103.1 of its corresponding stack 103. The light source 20 of the closest group 10 is arranged at a distance d of 0.5 mm from the inlet surface 103.1 of its corresponding stack 103. Finally, the light source 20 of the intermediate group 10 is arranged at a distance d' of 0.45 mm from the inlet surface 103.1 of its corresponding stack 103. Thus, the distances d, d', d" of the light source relative to the inlet surface 103.1 of the corresponding stack 103 are adjusted according to the length Lg' of the light injection element 100 so as to supply the same current i to the light source 20.

[0130] Figure 14 shows a second embodiment of the light-emitting device 1, in which:

[0131] - the light-emitting device 2 includes a single light guide 1,

[0132] ​- A plurality of light injection elements 100 forming a plurality of groups 10 are arranged on a first side 11.1 of the light guide 11 and thus form a first set of light injection elements 100, and a second set identical to the first set is arranged on a second side 11.2 of the light guide sheet 11 opposite to the first side 11.1 so as to be symmetrical with respect to the light guide sheet 11 to the first set.

[0133] - Light sources 20 coupled to the first set are arranged on the same first electronic carrier 21, and light sources 20 coupled to the second set are arranged on the same second electronic carrier 21 different from the first electronic carrier 21.

[0134] Thus, in a non-limiting example of Figure 14 , there are two sets of three groups 10: a first set of three groups 10 located on one side 11.1 of the light guide sheet 11, and a second set of three other groups 10 located on the other side 11.2 opposite to the first side 11.1. The light guide sheet 11 includes two light mixing regions 112, which are respectively opposite to each of the two sets of three groups 10. In a non-limiting example, the light guide sheet 11 includes three regions 110. Each group 10 in a set irradiates a region 110 different from another group 10 in the same set. The groups 10 in the first set irradiate regions that are the same as another group 10 in the second set.

[0135] This second non-limiting embodiment allows an increase in the irradiation of the region 110 because there is irradiation from both sides of the light guide sheet 11, rather than irradiation from one side as in the case of the first non-limiting embodiment. This also allows a reduction in the luminous power of the light sources 20 so as to have two smaller heat sinks 21, which are smaller in volume compared to the case of the first non-limiting embodiment, in which only a single heat sink 21 is provided in the non-limiting embodiment. In the non-limiting example shown, the number of light sources 20 is twice that in the first non-limiting embodiment because the number of groups 10 is twice that in the first non-limiting embodiment. The first non-limiting embodiment variant of the first non-limiting embodiment (light sources 20 are in the same plane) and the second non-limiting embodiment variant of the first non-limiting embodiment (light sources 20 are in different planes) can be applied to the second non-limiting embodiment individually or in combination.

[0136] Figure 15 shows a third embodiment of the light emitting device 1, in which the light emitting device 1 includes at least two stacked light guides 1 oriented in opposite directions to each other. In a non-limiting example of Figure 15 , the light emitting device 1 includes two as Figure 14 ​The light guide 1 described in the second embodiment, i.e., each of the two light guides includes two sets of light injection elements 100 of the group 10, and the two sets are respectively arranged on one side 11.1 and the other opposite side 11.2 of the light guide plate 11. The two light guides 1 are oriented in opposite directions because the entrance surfaces 103.1 of their stacks 103 are respectively arranged along the other two opposite sides 11.3 and 11.4. Thus, in Figure 15 , it is apparent that the two entrance surfaces 101.3 of the two stacks 103 of the first light guide 1 are arranged along the third side 11.3 of the light guide plate 11, while the two entrance surfaces 101.3 of the two stacks 103 of the second light guide 1 are arranged along the fourth side 11.4 of the light guide plate 11, and the fourth side 11.4 is opposite to the third side 11.3. In the non - restrictive example shown, the number of light sources 20 is twice that in the second non - restrictive embodiment; thus, there are four electronic carriers 21 and four heat sinks 22. The light guide plate 11 includes four light mixing regions 112, and the four light mixing regions are respectively opposite to each of the two sets of three groups 10 of each light guide 1. For the sake of clarity in the drawings, only a single light source 20 of each electronic carrier 21 is labeled with a reference numeral, and only the four entrance surfaces 101.3 are labeled with reference numerals. In the non - restrictive example, the light guide plate 11 includes three regions 110. Each region 110 is irradiated by four groups 10. In particular, each region 110 is irradiated by the groups 10 in the first set and the groups 10 in the second set of each light guide 11.

[0137] For example, this third non - restrictive embodiment allows the creation of an animation with two superimposed patterns. Thus, in the non - restrictive example, the two light guides 1 are arranged on the tail light (such as the rear position light) of a motor vehicle 3. In this case, the first light guide 1 may include a first light - emitting region 111 forming a first pattern, and the second light guide 1 may include a second light - emitting region 111 forming a second pattern superimposed on the first pattern. When the position light is lit, the light source 20 associated with the first light guide 1 is enabled, so the first pattern is irradiated, while the light source 20 associated with the second light guide 1 is disabled; thus, the second pattern is not irradiated. When the driver brakes, the light source 2 associated with the second light guide 1 is enabled, so the second pattern can also be irradiated, and if the two patterns are the same, it is thus irradiated superimposed on the first pattern. When the driver brakes, the light source 2 associated with the second light guide 1 is enabled, so the second pattern can also be irradiated and used as an additional supplement to the first pattern.

[0138] Of course, the description of the present invention is not limited to the above embodiments and the above fields. Therefore, the present invention can be applied to any application that requires a large light-emitting surface other than vehicle applications. Thus, in a third embodiment variant of the first non-limiting embodiment, the light source 20 can be arranged in the same plane of the electronic carrier 21, and the entrance surfaces 103.1 are offset from each other with respect to the axis x, rather than using the steps of the electronic carrier 21 to place the light sources in different planes or power the light sources 20 located in the same plane with different currents. The entrance surfaces will no longer be aligned along the axis x. Thus, along the axis x, the entrance surface 103.1 of the stack 103 of the group 10 furthest from the light source 20 will be closer than the other two, and the entrance surface 103.1 of the stack 103 of the group 10 closest to the light source 20 will be the furthest of the other two.

[0139] Therefore, the present invention as described particularly has the following advantages:

[0140] - The present invention allows the use of a flexible surface light guide 1 that is suitable for vehicle applications with a relatively large surface area to be illuminated.

[0141] - The present invention allows the use of a lighting device 2 having light sources 20 that have sufficient luminous power to illuminate the light guide sheet 11 of the light guide 1.

[0142] - Compared with the prior art, the present invention allows the reduction of the number of electronic carriers, so that when all the light sources 20 are located on the same side of the light guide sheet 11, only a single electronic carrier 21 is required, thereby allowing the reduction of the size, weight, and cost of the lighting device 2.

[0143] - By reducing the number of electronic carriers, the present invention allows the reduction of the number of associated connectors and the number of associated electrical connection harnesses, thereby allowing the reduction of the size, weight, and cost of the lighting device 2.

[0144] - By moving the light source 20 away from the light guide sheet 11, the present invention allows the light source 20 to be located in an unconstrained space where there is space, and thus allows the use of a light source 20 with a higher luminous power than the light sources of the prior art (if needed); the present invention also enables the possibility of placing one or more radiators 21 suitable for the size and luminous power of the light source 20 in the unconstrained space; therefore, the size of the radiator can be increased compared to the prior art.

[0145] - The present invention enables more efficient and stronger irradiation of the light guide sheet 11 and its regions 110.

[0146] - The present invention allows the increase of the light-emitting surface area, that is, the total surface area of the irradiated regions 110 of the light guide sheet 11, without reducing the irradiation efficiency.

[0147] - The present invention allows the use of luminous signs, which can be in animated form if desired.

Claims

1. A flexible surface light guide (1) for a vehicle (3), the light guide comprising: - Light injection elements (100) grouped into a plurality of groups (10) and a light guide sheet (11), each group (10) being coupled to at least one light source (20), characterized in that: - The light guide sheet (11) includes a plurality of regions (110), at least one light emitting region (111) being incorporated into at least one of the regions (110), the light guide sheet (11) being adjacent to the light injection elements (100), each group (10) being configured to irradiate the regions (110) in the light guide sheet (11), and the length (Lg') of the light injection elements (100) in the group (10) irradiating one region (110) is different from the length of the light injection elements (100) in other groups (10) irradiating another region (110).

2. The optical waveguide (1) according to claim 1, wherein, In the light injection elements (100) of each group (10), the light injection elements (100) are folded to form a stack (103) having a thickness (e) adapted to the emission surface (s1) of the light source (20), the stack (103) having an entrance surface (103.1) configured to receive light emitted by the light source (20).

3. The optical waveguide (1) according to claim 2, wherein, The dimensions of the light injection elements (100) are determined such that when the light injection elements in each of the groups are folded, the entrance surfaces (103.1) of the grouped light injection elements are at the same level.

4. The optical waveguide (1) according to any one of the preceding claims, wherein, The at least one light emitting region (111) forms at least one pattern.

5. The optical waveguide (1) according to any one of the preceding claims 1 to 4, wherein, The light injection elements (100) grouped into a plurality of groups (10) are arranged on the same side (11.1) of the light guide sheet (11) and thus form a first set of light injection elements (100).

6. The light guide (1) according to any one of the preceding claims 1 to 4, wherein, The light injection elements (100) grouped into a plurality of groups (10) are arranged on a first side (11.1) of the light guide sheet (11) and thus form a first set of light injection elements (100), and wherein the light guide (1) includes a second set identical to the first set, the second set being arranged on a second side (11.2) of the light guide sheet (11) opposite to the first side (11.1) so as to be symmetric with respect to the light guide sheet (11) with the first set.

7. A lighting device (2) for a vehicle (3), characterized in that, The lighting device includes at least one light guide (1) as claimed in any one of the preceding claims, a plurality of light sources (20) and at least one radiator (22).

8. The light-emitting device (2) according to claim 7, wherein, The light sources are arranged on the same electronic carrier (21).

9. The light-emitting device (2) according to claim 8, wherein, The light sources (20) are arranged in the same plane of the same electronic carrier (21).

10. The light-emitting device (2) according to claim 8, wherein, Each light source (20) is arranged in a plane of the same electronic carrier (21) different from that of the other light sources (20).

11. The light-emitting device (2) according to any one of claims 7 to 10, wherein, The lighting device (2) includes at least two superimposed light guides (1) oriented in opposite directions to each other.

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