Light module comprising light guide having light guide sheet for uniform light intensity display

Abstract

The present invention relates to a light module comprising: a light guide comprising a light guide sheet and a light incident component; and a light source arranged so as to impinge light into the entry surface of the at least one incidence assembly. The light guide sheet comprises a film (111) comprising a light extraction region with microstructures (113) capable of redirecting light incident into the light guide sheet towards the outside of the light module. The film includes a microstructure on a first face (701) and on a second face (702). For each of portions of the light extraction region at different distances from a light incident edge surface (114), a sum of densities of the microstructures on the first face and the second face is an incremental function of a distance between the portion and the incident edge surface.

Description

Technical Field

[0001] The present invention relates to the field of light-emitting modules in which an optical waveguide is used, and more particularly, to light-emitting modules in which a flexible optical waveguide is used. Background Art

[0002] Nowadays, it is common practice to perform light-emitting functions in various different types of devices and more particularly in motor vehicle devices for the purpose of providing illumination, signal indication information, achieving aesthetic customization or creating an atmosphere.

[0003] It is known practice to use a display such as an LCD.

[0004] However, this technology is not only expensive but also sensitive to environmental conditions such as temperature, humidity or UV radiation. Therefore, it is not suitable for many devices with uses that cause environmental conditions to change, which may be the case for devices used outdoors.

[0005] In addition, the aforementioned solution has the disadvantage of high energy consumption, and the larger the surface area of the device in which the light-emitting module is to be integrated, the higher the energy consumption.

[0006] It is known to use a light-emitting module with an optical waveguide, the optical waveguide including a light-guiding sheet incorporating a film, the film being flexible, guiding light therein, and depending on the microstructure formed in the film, the light being turned into a given light-emitting pattern. Light is incident into the incident edge of the film.

[0007] Regardless of the technique used to form the microstructure in the optical waveguide to produce the pattern, it is easier to produce the microstructure on the surface of the film rather than in the body of the film.

[0008] The region where the microstructure is produced is the light extraction region, and the region not including the microstructure is called the dark region. The corresponding arrangement and shape of the light extraction region and the dark region together form the light-emitting pattern of the optical waveguide.

[0009] In order to achieve the uniformity of light emission between the light extraction regions, it can be stipulated that the density of the microstructure in the light extraction region is changed according to the distance from the light incident edge of the film into which the light is incident.

[0010] However, the density of the microstructure in the light extraction region is limited by the maximum density. Such a maximum light emission density limits the size of the optical waveguide for which the uniformity of the light extraction region can be obtained. The size can be increased, but in this case, the light emission intensity of the optical waveguide must be limited, or the uniformity in terms of the light emission intensity is affected.

[0011] Therefore, there is a need to obtain a light-emitting module based on a light-guiding sheet for displaying a light-emitting pattern, the light-emitting pattern having good light emission uniformity between the illuminated regions of the light-emitting pattern and having a large size. Summary of the Invention

[0012] The present invention improves the situation.

[0013] A first aspect of the present invention relates to a light emitting module, comprising: A light guide, the light guide comprising: a sheet for guiding light, the light guiding sheet being configured to receive light via at least one light incident edge and deflect the light in a direction substantially normal to the light guiding sheet; and at least one incident assembly configured to receive light from an entrance surface and guide the light so as to inject them into the light incident edge of the light guiding sheet; A light source arranged to inject light into the entrance surface of the at least one incident assembly.

[0014] The light guiding sheet comprises a film, the film comprising at least one light extraction region, the light extraction region comprising microstructures capable of redirecting light incident on the light guiding sheet at least in a substantially normal direction. The film comprises microstructures on a first side and on a second side of the film. For each of the portions of the light extraction region having different respective distances from the light incident edge, the sum of the microstructure density on the first side and the microstructure density on the second side in the portion is an increasing function of the distance between the portion and the light incident edge of the light guiding sheet.

[0015] Increasing the microstructure density according to the distance from the light incident position allows a display with a uniform distribution of the luminous intensity per unit area to be formed on the light emitting module. Thus, the dynamic light extraction range is defined by the variation of the microstructure density as the distance from the light incident edge increases.

[0016] Forming microstructures on both sides of the film of the light guiding sheet makes it possible to extract light from the light guide over a longer distance while maintaining the uniformity of the distribution of the luminous intensity per unit area in the light extraction region. Thus, it is possible to produce larger light emitting modules. Alternatively, at equal dimensions, it is possible to extract more light from the light guide and thus increase the brightness in the light extraction region while allowing uniformity between the various parts of the light extraction region.

[0017] According to an embodiment, the portion of the light extraction region may face a given section of the light incident edge.

[0018] When such an incident assembly includes a plurality of incident elements capable of incident light on different and consecutive segments of the light incident edge, such segments may correspond to a set of incident positions of the incident elements of the incident assembly. Thus, a dynamic light extraction range is defined for each segment, which allows for good uniformity of the distribution of the light emission intensity between the respective parts of the at least one light extraction region.

[0019] According to an embodiment, the shape of the at least one light extraction region may form a light emission pattern of the light emitting module.

[0020] This makes it possible to display a large light emission pattern with good light intensity uniformity.

[0021] According to an embodiment, the film may further include at least one dark region having no microstructure, and the shape of the at least one dark region and the at least one light extraction region may together form a light emission pattern of the light emitting module.

[0022] Thus, it is possible to produce a large and complex light emission pattern with good light intensity uniformity.

[0023] According to an embodiment, the light guide sheet may be transparent, and for each part of the at least one light extraction region, the microstructure density may be less than the maximum density, the maximum microstructure density being determined such that when no light is incident by the light source, the microstructure is invisible. Here, the microstructure density may be the microstructure density on the first side or the microstructure density on the second side.

[0024] In other words, the maximum density here is a threshold value, above which at least some of the microstructures may be visible to the naked eye. It will be noted that there is also a saturation density related to technical feasibility, i.e., the limiting value feasible in a given microstructure formation technique. Thus, it is possible to produce a large transparent light emitting module with good light intensity uniformity.

[0025] According to an embodiment, for parts of the at least one light extraction region having different respective distances from the light incident edge, the microstructure density on the first side may be a first increasing function of the distance between the part and the light incident edge, the first increasing function may have the maximum microstructure density at least in the part farthest from the light incident edge, and the microstructure density on the second side is a second increasing function of the distance between the part and the light incident edge. Here, the maximum microstructure density is determined such that when no light is incident by the light source, the microstructure is invisible.

[0026] Additionally, the first increasing function is different from the second increasing function. In other words, from the incident edge to the part furthest from the edge, the microstructure density on the first side varies according to a mathematical function or according to a computational law, which is different from the mathematical function or computational law of the microstructure density on the second side (likewise varying from the incident edge and with the distance therefrom). By way of example, the microstructure density on the first side increases linearly as a function of the distance between the part and the light incident edge of the light guide sheet. On the other side, i.e., on the second side, the microstructure density can increase non-linearly (for example, hierarchically or according to a logarithmic law or an exponential law as a function of the distance between the part and the light incident edge of the light guide sheet).

[0027] Thus, it is possible to define a suitable arrangement of the microstructures on each of the two sides of the light guide sheet in order to meet various requirements such as the uniformity and the luminous power of the light guide. Thus, the proposed light guide can be parameterized as needed.

[0028] Additionally, the second increasing function has a maximum microstructure density which may be equal to the maximum microstructure density at least in the part furthest from the light incident edge.

[0029] Thus, by using two sides, the maximum microstructure density is doubled, which makes it possible to increase the size of the light emitting module or, for an equal size, to increase the amount of light extracted.

[0030] Additionally, the microstructure density on the second side may be zero in the part furthest from the light incident edge.

[0031] Thus, the dynamic light extraction range is mainly defined by the first side. Furthermore, since the part of the second side of the film on which the microstructures are formed is minimized, the manufacture of such a light emitting module is facilitated.

[0032] Additionally or as a variant, the first side may be oriented towards the outside of the light emitting module, and the second side may be oriented towards the inside of the light emitting module.

[0033] Thus, the side that mainly defines the dynamic extraction range is oriented towards the outside of the light emitting module, which maximizes the amount of light emitted towards the outside of the light emitting module. Thus, the efficiency associated with the light emitting module is improved.

[0034] According to an embodiment, the film may be made of polycarbonate PC, polymethyl methacrylate PMMA, thermoplastic polyurethane TPU, polyethylene terephthalate PET or silicone, and may have a thickness between 25 microns and 1000 microns, specifically between 50 microns and 1000 microns and for example between 200 microns and 500 microns.

[0035] This thus makes it possible to produce a flexible light guide sheet, which facilitates its integration into any type of device.

[0036] A second aspect of the invention relates to a motor vehicle device comprising a lighting module according to the previous claim. Description of the Drawings

[0037] Other features and advantages of the invention will become apparent upon studying the following detailed specification and the drawings, in which:

[0038] Figure 1 shows a cross-sectional view of an element of a light guide for a lighting module according to an embodiment of the invention;

[0039] Figure 2 shows a front view of an element of a light guide for a lighting module according to an embodiment of the invention;

[0040] Figure 3 shows a front view of an element of a light guide for a lighting module according to an embodiment of the invention;

[0041] Figure 4 shows a three-dimensional view of a light input assembly for a lighting module according to an embodiment of the invention;

[0042] Figure 5 shows a light-emitting pattern displayed on a light guide sheet of a lighting module according to an embodiment of the invention;

[0043] Figure 6 shows the microstructure density in a part of the light extraction area of a lighting module according to an embodiment of the invention;

[0044] Figure 7 shows multiple views of a light guide of a lighting module according to an embodiment of the invention;

[0045] Figure 8 shows multiple views of a light guide of a lighting module according to other embodiments of the invention. Detailed Description

[0046] The description focuses on the features that distinguish the external device and the lighting module from those known in the prior art. ​​​​​​​​

[0047] Figure 1 Elements of the light guide 105 of a light emitting module according to an embodiment of the present invention are shown.

[0048] The light guide 105 includes a light guiding sheet 110 which may be flexible, capable of receiving light through at least one light incident edge 114, and capable of turning the light in the Z direction substantially normal to the surface of the light guiding sheet, and the light guiding sheet thus extends in the Figure 1 X - Y plane in. A light guiding sheet means an optical element that guides light, and one of the spatial dimensions of the light guiding sheet is much smaller than the other two spatial dimensions, for example, one or more orders of magnitude smaller. As Figure 1 illustrated herein, the light guiding sheet 110 considered here has a thickness along the Z - axis that is at least two orders of magnitude smaller than its dimensions in the X - Y plane in which the light guiding sheet 110 extends.

[0049] The light guiding sheet 110 may include a film 111 at its core. The film 111 may be flexible. The film 111 includes a light incident edge 114. The film 111 is capable of guiding light in the entire X direction, and the film 111 includes a set of microstructures 113. The set of microstructures 113 is capable of turning the light guided into the film 111 out of the flexible light guiding sheet 110, and specifically turning it out in one or more directions substantially along the Z - axis.

[0050] The film 111 may be a substrate film made of polycarbonate PC, polymethyl methacrylate PMMA, thermoplastic polyurethane TPU, polyethylene terephthalate PET, silicone, or even glass. The film 111 may have a thickness between 12 microns and 1000 microns, and this thickness is the dimension along the Z - axis. More precisely, the thickness of the film 111 may be between 25 microns and 1000 microns, specifically between 50 microns and 1000 microns, and for example between 200 microns and 500 microns. As a variant, it is the light guiding sheet 110 that has a thickness between 200 microns and 1000 microns.

[0051] The aforementioned materials associated with the small thickness as described above make it possible to obtain a flexible and transparent film 111. For the composition of the film 111, other materials may be considered. However, according to the present invention, it is preferred to provide a deformable and transparent material.

[0052] A thin coating of the microstructures 113 may be produced on one of the sides of the film 111 or in the film 111. According to the present invention, the microstructures 113 are formed on both sides of the film, as will be better understood by reading Figure 5 and the following description and so on.

[0053] Microstructures are formed on the surface of the film and are distributed to produce a luminescent pattern. The luminescent pattern is obtained using a light extraction region (i.e., the region of film 111 that includes microstructures 113). The luminescent pattern may also include dark regions, i.e., regions of film 111 that do not include microstructures 113. The shapes and corresponding arrangements of the light extraction regions and the dark regions together form the luminescent pattern. As a variant, the luminescent pattern includes only one light extraction region of a given shape.

[0054] Microstructure 113 means a structure or irregularity in the flexible film having at least one dimension less than a few micrometers. For example, microstructure 113 may be about 50 micrometers in diameter and may be 1 or 2 micrometers in height. Thus, microstructures also cover nanostructures. Microstructures 113 of such dimensions make it possible to ensure that the flexible film 111 is highly transparent. Specifically, in practice, a transparency of about 97% can be obtained by using microstructure 113. As a variant, the light guide sheet may be translucent.

[0055] The microstructures are capable of redirecting light incident into the light guide in one or more directions different from the incident direction along the X-axis. Specifically, in a direction substantially parallel to the Z-axis, and specifically in a direction pointing outside the light emitting module 100, at least some of the redirected light rays are redirected. In fact, such microstructures are capable of redirecting the guided light rays in all directions of space in a Lambertian manner.

[0056] There is no restriction on the manner in which microstructures 113 are formed on the side of film 111. Microstructures 113 can be obtained by adding or subtracting material from the flexible film.

[0057] For example, the microstructures can be obtained by embossing by applying a roller having irregularities to mechanically print the microstructures on the surface of film 111. As a variant, microstructures 113 can be obtained by radiation (e.g., with UV rays) or by baking a polymer in contact with a mold, roller, or any other surface including irregularities capable of forming complementary-shaped microstructures.

[0058] As another variant, microstructures 113 are formed in positions where a flexible film coating made of a material having a low refractive index is removed from the flexible film, so as to form microstructures by removing material. In this case, the microstructures are pores or gaps. Optionally and in a complementary manner, additional (prismatic, reflective, diffractive, or diffusive) surface or body elements can be added in the pores or gaps to form microstructures 113.

[0059] The microstructures 113 can be obtained by treating the surface of the film 111, in which case they have the same material as the film 111 or correspond to the material where the film 111 is absent. Such treatment can be achieved by mechanical or laser scribing, laser ablation, sandblasting, exposure to radiation, chemical treatment, or any other treatment, making it possible to obtain irregularities in a controlled manner on the side of the film 111.

[0060] As a variant or in a complementary manner, the microstructures 113 are exogenous elements of a film added to the side of the film 111.

[0061] The coating of the microstructures 113 can specifically have a thickness of less than 20 microns along the Z-axis.

[0062] As detailed below, the density of the microstructures 113 can vary in the light extraction region according to their distance from the light incident edge 114.

[0063] "Pattern" means any predefined spatial distribution of the luminous intensity emitted by the lighting module. Specifically, two-dimensional or one-dimensional patterns are referred to here. Thus, the pattern can include a uniform distribution of light over the entire light guide sheet, in which case the light extraction region extends over the entire light guide sheet. The pattern can also include two-dimensional shapes or symbols obtained by the contrast between the light extraction region and the dark regions of the light guide sheet 110. The pattern can also include multiple shapes or symbols. Alternatively, the pattern covers a predefined spatial distribution of the luminous intensity that does not give rise to any general shape (e.g., a distribution resulting in a cloud of luminous points).

[0064] The flexible light guide sheet 110 can further include one or two optional protective layers 112.1 and 112.2 that allow the film 111 to be mechanically protected. In addition, at least one of the protective layers 112.1 and 112.2 can include a UV treatment, preferably the protective layer 112.1 through which the light redirected by the microstructures 113 is emitted can include a UV treatment, making it possible to protect the film from UV rays once the microstructures 113 have been produced. In the absence of such UV protection, specifically when exposed to sunlight, the pattern projected by the light guide sheet 110 may deteriorate over time.

[0065] By way of illustration only, in Figure 1 the spaced-apart film 111 and protective layers 112.1 and 112.2 have been shown. However, it will be understood that the protective layers 112.1 and 112.2 can be attached to the film 111 by lamination, specifically.

[0066] By virtue of the difference between the refractive index of the film 111 and the refractive index of the layer of glue or adhesive applied to at least one side of the flexible film, light propagates through the film 111 by total internal reflection.

[0067] The film 111 can be bonded to the protective layers 112.1 and 112.2 by an adhesive. Specifically, an adhesive layer is placed on both sides of the film between the film 111 and each of the protective layers 112.1 and 112.2 to cause the protective layers to adhere to the film 111.

[0068] The selected adhesive is transparent and has a refractive index different from and specifically less than that of the film, so as to allow total internal reflection in the film 111. For example, the adhesive can include silicone or acrylic. In other words, due to the difference in refractive index, when the light rays propagating through the film 111 encounter the interface between the film 111 and the adhesive layer at an incident angle less than the normal incidence, they experience total reflection. Therefore, the light guide sheet can guide light, for example, from the entrance area (here the incident edge 114) to the exit area through total internal reflection of light.

[0069] Since the light guide sheet 110 can be flexible, it does not necessarily lie in a plane but can be curved, depending on the position where it is placed and the mechanical constraints applied to it.

[0070] Figure 1 The light guide 105 illustrated in also includes an incident assembly 120. The incident assembly 120 includes a plurality of light incident elements described with reference to the following drawings. The assembly 120 is capable of distributing light to the light guide sheet 110 at various positions along the Y-axis along the light incident edge 114. At each position along the Y-axis, the light is incident in a direction substantially parallel to the X-axis.

[0071] The incident assembly 120 includes Figure 1 an entry surface 121 with a rectangular or square cross-section in. However, the assembly 120 can include an entry surface with a cross-section of different shapes.

[0072] In Figure 1 the illustrated incident assembly 120 has an exit surface 122 that extends in the Y direction and is placed facing the light incident edge 114. It will be understood by reading the description of the following drawings that the exit surface 122 and the light incident edge 114 are the same, and the flexible film 111 and the incident assembly 120 form a single component.

[0073] At one end of the incident assembly 120, the incident assembly 120 further includes an entry surface 121 that can receive light rays from a light source outside the light guide 105 (the light source is not shown in Figure 1 ), and the incident assembly 120 can longitudinally guide the light along the Y-axis while distributing it to the exit surface 122. The light distribution of the exit surface 122 will be better understood according to the description of the following drawings.

[0074] Figure 2 Shows the components of the light emitting module 100, which components include a light guide 105 and a light source 130, the light guide 105 having a component 120 consisting of incident elements and a flexible light guiding sheet 110.

[0075] Depending on the distribution of the microstructures 113, the light guiding sheet 110 or more precisely the film 111 may include a mixing zone 111.2 and a light emitting zone 111.1, the light emitting zone including at least one light extraction zone provided with microstructures 113 and optionally one or more dark zones in order to produce a light emitting pattern in the light emitting zone 111.1. The mixing zone 111.2 is placed upstream of the light emitting zone in the propagation direction of the light. The light emitting zone 111.1 is integrated into the region 1110.

[0076] In order to obtain better light emission uniformity, the light incident on the light guiding sheet 110 via the incident edge 114 is mixed in the mixing zone 111.2. Then, the light propagates into the light emitting zone 111.1, in which the light exits from the light guiding sheet 110 in the Z direction.

[0077] More generally, the mixing zone 111.2 is a zone of the flexible light guiding sheet that does not include the light emitting pattern emitted by the flexible light guiding sheet 110, and the mixing function of the zone 111.2 is optional.

[0078] The component 120 of the incident elements 120.1 is capable of incidenting the light rays generated by the source 130 towards the mixing zone 111.2 into the incident edge 114. Figure 2 A single incident component 120 is shown by way of illustration.

[0079] It will be noted that the light guide 105 may include a plurality of incident components 120 per incident edge 114, each incident component 120 being arranged at a given set of Y positions on the incident edge 114. Thus, each incident component 120 is configured to illuminate a different region 1110 in the light guiding sheet. A single incident component 120 per incident edge 114 will be considered by way of illustration below.

[0080] The component 120 includes a plurality of light incident elements 120.1. Specifically, the component 120 may include between three and ten incident elements 120.1. In Figure 2 a non-limiting example, the light guide 105 includes a component 120 having ten incident elements. For clarity, only two light incident elements 120.1 have been labeled with reference numerals.

[0081] The component 120 is coupled to at least one light source 130 such that the light rays R emitted by the light source are received by each of the light incident elements 121.

[0082] Assume that the light incident element 121 is obtained by cutting from the same material as the flexible film 111. The light ray R will propagate through the light incident element 120.1 by total internal reflection and deliver the light to a light guide sheet adjacent to and integral with the light incident element 120.1. Thus, the light will illuminate one or more light extraction regions of the light guide sheet 110.

[0083] Therefore, the superposition of the light incident elements 120.1 forming the assembly 120 can form coupling grating bars or grating bars configured to receive light rays generated by the light source 130 and propagate them into the light guide sheet 110. The assembly 120 may have a square or rectangular cross-section.

[0084] There is no restriction on the light source 130, and the light source 130 can be any light source technology. For example, the light source 130 can be an electroluminescent element mounted on a substrate 131, for example, an LED for example. In addition, a heat dissipation element 132 can be arranged below the substrate 131.

[0085] The light source 130 can be capable of generating light at wavelength intervals. Such intervals can be centered on visible colors in order to generate colored light, for example, blue, red or green light. As a variant, the light source 130 can emit light rays across the entire wavelength interval visible to the human eye in order to generate white light. The light source 130 can be controlled by a control element (not shown). As a variant, the light source 130 is not arranged to directly face the entry surface 121 of the incident element 120, but the light emitting module 100 further includes an optical fiber placed between the light source 130 and the incident assembly 120, which allows the light source 130 to be positioned away from the light guide 105.

[0086] Therefore, it is possible to incident light at various longitudinal positions along the Y-axis of the incident edge 114.

[0087] The light guide sheet 110 can have a width La along the Y-axis and a length Lg along the X-axis. The light guide 105 can be cut from a roll of the same material as the film 111 and the incident element 120. The roll extends along the X-axis and has the same width La as the light guide 105.

[0088] The reference sign (pj) indicates the incident position of index j. Each incident position of index j corresponds to an interval of the incident position along the Y-axis incident into the incident edge 114. j varies between 1 and N, and N is the number of light incident elements 120.1 in the incident assembly 120 (i.e., in the example considered so far N = 10).

[0089] Therefore, the light emitting module 100 includes a light guide 105 and a light source 130. The light guide 105 includes a flexible light guide sheet 110 and an incident assembly 120.

[0090] The component 120 and the light source 130 may be included in the non-visible portion 13 of the light-emitting module 100. Such a portion may be hidden, while in contrast, the light-emitting emission region 111.1 can be observed from the outside of the device including the light guide 105.

[0091] Figure 3 is illustrated Figure 2 of the light guide, in which the light incident element 120.1 of the incident component 120 is unfolded. In Figure 3 each incident element 120.1 has a corresponding length Lh and width W.

[0092] For Figure 3 clarity, only the length Lh and width W of the longest incident element 120 have been labeled with reference numerals. The length Lh of the other incident elements 120 is less than the length Lh of the longest incident element. In contrast, the width W of all the incident elements 120.1 may be equal.

[0093] By way of non-limiting example, the length Lh of the longest incident element 120.1 is between 100 millimeters and 500 millimeters. Similarly, the width W may be between 1 mm and 20 mm.

[0094] Figure 3 also indicates the folding position 300, at which each incident element 120.1 can be folded so that the incident elements 120.1 are superimposed to form the component 120. The corresponding length Lh of the incident element is determined based on the folding position and the corresponding Y position of the incident element such that their ends together form the incident surface 121.

[0095] Figure 4 illustrates a three-dimensional view of the component 120 and the light source 130 of the light-emitting module 100 according to an embodiment of the present invention.

[0096] As Figure 4 illustrated, each light incident element 120.1 has a thickness e. The thickness e corresponds to the thickness of the light guide 105 (i.e., the film 111). The light incident element 120.1 has two ends 120.10, as Figure 2 illustrated, one of the two ends 120.10 is integral with the light guide sheet 110, and as Figure 4 illustrated, the other of the two ends 120.10 can be placed facing the light source 130. The light rays emitted by the light source 130 enter through one end 120.10, which is referred to as the first end, and are transmitted to the other end 120.10, which is referred to as the second end, and then are transmitted to the light guide sheet 110 via the light incident edge 114, which coincides with the second end 120.10 of the incident element 120.1.

[0097] Note that during the manufacturing process of the light guide 105, the incident element 120.1 and the light guiding sheet 110 can be wound from a material engraved with a given pattern, and then cut with a blade or cutter to separate the light guide 105 from the rest of the roll, and to separate the various incident elements 120.1 along the X-axis, and thus form the various incident elements 120.1 before they are folded at the folding position 300.

[0098] Thus, the light incident element 120.1 remains attached to the light guiding sheet 110 at its second end 120.10.

[0099] The respective lengths Lh of the incident elements 120.1 are such that the first ends 120.10 facing the light source 130 coincide to form the incident surface 121 of the assembly.

[0100] The incident surface 121 thus has a thickness E equal to the sum of the thicknesses e of the incident elements 120.1.

[0101] Figure 5 The light guiding sheet 110 of the light guide of the light emitting module 100 according to an embodiment of the present invention is shown.

[0102] For simplicity, the incident assembly 120 is not shown in Figure 5 .

[0103] The light emitting pattern is formed by four light extraction regions 502.1, 502.2, 502.3, and 502.4 that include microstructures (not shown in Figure 5 ) and a dark region 504 that does not contain any microstructures. The dark region 504 and the light extraction regions 502.1, 502.2, 502.3, and 502.4 are complementary and together form the light emitting pattern in the light emitting emission region 111.1.

[0104] In Figure 5 , an incident position 501 incident on one of the light incident edges 114 has been shown. The incident position 501 corresponds to a position along the Y-axis, and a portion 503.1 of the first light extraction region 502.1, a portion 503.2 of the second light extraction region 502.2, a portion 503.3 of the third light extraction region 502.3, and a portion 503.4 of the fourth light extraction region 502.4 are positioned facing said position. Preferably, the incident position 501 is a segment 501 that includes an interval of Y positions. By way of example, this can be a matter of a set of Y positions of one of the incident elements 120.1 among the assemblies 120 corresponding to the incident elements 120.1.

[0105] No restrictions are imposed on each of portions 503.1 to 503.4, which can be any region having a size larger than the size of the microstructure, and preferably at least ten times larger than the size of the microstructure, so as to be able to determine the microstructure density therein.

[0106] Light rays incident at the incident position 501 and light rays that may be incident adjacent to the incident position 501 (i.e., light rays at two close Y positions) are guided through the light guide sheet 110, and the light rays are gradually extracted from the light guide sheet 110 by portion 503.1, then by portion 503.2, then by portion 503.3, and then by portion 503.4.

[0107] To make it possible for the luminous intensity in each of portions 503.1 to 503.4 to remain similar, and thus to allow a luminous pattern with a uniform luminous intensity to be achieved, the corresponding microstructure density within portions 503.1 to 503.4 can vary as Figure 6 illustrated.

[0108] Specifically, the microstructure density in a given portion of the light extraction region depends on the distance between the portion and the light incident edge 114.

[0109] Figure 6 is illustrated Figure 5 for the portions of the light extraction region illustrated.

[0110] As Figure 6 shown, the density of the microstructures 113 in a given portion varies positively (or is an increasing function) with the distance between the portion and the light incident edge 114. Specifically, the amount of light rays reaching portion 503.4 is less than the amount reaching portion 503.1. To compensate for this, the microstructure density in portion 503.4 is larger than that in portion 503.1.

[0111] No restrictions are imposed on the increasing function that correlates the distance from the light incident edge 114 with the density of the microstructures 113. Such a function depends on the desired brightness of the luminous pattern, the inherent characteristics of the light guide 110, and the light source 130.

[0112] In Figure 5 the example illustrated, the X positions of portions 503.1 to 503.4 are discontinuous. Specifically, portions 503.1 to 503.4 are separated by the dark regions 504 of the luminous pattern.

[0113] However, specifically, when the luminous pattern includes only a single light extraction region (and thus has no dark regions), when describing the variation in the density of the microstructures 113, portions of the single light extraction region with continuous positions can be considered. Such an example is used below to describe Figure 7 .

[0114] As explained in the introduction, the density of the microstructures 113 is limited, i.e., it is not possible to indefinitely increase the density of the microstructures 113 as a function of the distance from the light incident edge 113. Thus: If a uniform pattern is desired, the size of the light guide sheet is limited; Or the size of the light guide sheet is not limited, but the density of the microstructures saturates and the light emitting pattern no longer appears uniform. Specifically, the light emitting intensity of the portion of the light extraction region that exceeds the density saturation X position is lower than the light emitting intensity before saturation.

[0115] Figure 7 A side view, a top view, and a bottom view of the film 111 of the light guide sheet of the light emitting module according to an embodiment of the present invention are shown.

[0116] According to the present invention, the microstructures 113 are formed on both the top side portion 701 and the bottom side portion 702 of the light guide sheet 110.

[0117] Regardless of whether the microstructures 113 are formed on the top side portion 701 or on the bottom side portion 702, the microstructures 113 can deflect light outward from the top side portion 701 at least substantially in the direction of the Z axis, with the top side portion oriented towards the outside of the light emitting module 100.

[0118] Therefore, the amount of light extracted in each interval of the X position of the light guide sheet depends on the sum of the density of the microstructures on the top side portion 701 and the density of the microstructures 113 on the bottom side portion in the interval of the X position. Thus, marking the maximum density dmax of the microstructures 113 on a given surface, the sum of the densities in each interval of the X position can vary between 0 and 2*dmax, rather than between 0 and dmax as in the prior art.

[0119] For a given portion of the light extraction region, the sum of the density of the microstructures 113 on the top side portion 701 and the bottom side portion 702 is an increasing function of the distance between the light incident edge 114 and the portion. In other words, for any pair of facing portions of a given segment of the incident edge, the sum of the densities of the microstructures on the two sides of the portion closest to the incident edge is less than the same sum in the farthest portion.

[0120] Therefore, it is possible: Increase the amount of light extracted for a light guide sheet 110 of a given size while showing a light emitting pattern with a uniform light emitting intensity distribution; Increase the size of the light guide sheet 110 while showing a light emitting pattern with uniform brightness.

[0121] The maximum density dmax can correspond to a density at which the microstructure 113 is not visible thereunder when no light is incident on the light guide sheet 110. Such a maximum density is advantageous when using a transparent light guide sheet 110.

[0122] As a variant, the maximum density can correspond to a density at which the microstructures 113 come into contact with each other above a certain density. The maximum density can also be set by the manufacturing process of the light guide 105.

[0123] In Figure 7 's example, the density of the microstructures 113 on the top side increases with the distance from the light incident edge until it saturates for a certain X value (labeled X1). Beyond the saturation value X1, microstructures 113 can be formed on the bottom side 702 such that the sum of the densities on both sides continues to increase with the distance from the light incident edge. As a variant, as shown in Figure 7 , microstructures are formed on the bottom side starting from a value X2 greater than X1.

[0124] As in Figure 5 , the light extraction region can be divided into multiple parts. Regardless of the division of the parts used, the sum of the microstructure densities on the top side and the bottom side of a part is an increasing function of the distance of that part from the light incident edge 114. In other words, the farther a part is from the light incident edge 114, the greater the sum of the densities on its bottom side and top side.

[0125] As Figure 7 shows, the bottom side 701 includes microstructures only in the part farthest from the incident edge (i.e., in the part beyond X2). The part between X1 and X2 is the part where the microstructure density on the top side 701 is the greatest, but in this part, the bottom side still does not include any microstructures.

[0126] It will be noted that in Figure 7 , the sum of the microstructure densities increases continuously because a single extraction region without being interrupted by one or more dark regions is shown. However, the present invention is also applicable to light emitting patterns containing dark regions, and the increase in the microstructure density as a function of the distance from the light incident edge applies only to the parts of the light extraction region and not to the dark regions that do not contain microstructures.

[0127] Within the scope of the present invention, distributions of the microstructures 113 different from those shown in Figure 7 are conceivable.

[0128] For example, Figure 8 shows a side view, a top view, and a bottom view of the film 111 of the light guide sheet of a light emitting module according to an embodiment of the present invention, where the distribution of the microstructures 113 is different from the distribution shown in Figure 7 .

[0129] In Figure 8 the distribution, the microstructure density increases with the distance from the light incident edge 114 on the top side portion 701 and the bottom side portion 702. Therefore, the sum of the densities also increases with the distance from the light incident edge 114.

[0130] In Figure 8 the example of, regardless of the portion of the at least one light extraction region, the microstructure density on the top side portion 701 in a portion is a first increasing function of the distance of the portion from the light incident edge 114. Similarly, the microstructure density on the bottom side portion 702 in a portion is a second increasing function of the distance of the portion from the light incident edge. As Figure 8 shown in, the first function and the second function may be different. Therefore, the function corresponding to the sum of the densities of the microstructures on the top side portion 701 and the bottom side portion 702 is the sum of the first function and the second function, and the sum also increases.

[0131] The present invention is not limited to the embodiments described above by way of example, but extends to other variations.

Claims

1. A light-emitting module (100), comprising: A light guide (105), the light guide comprising: a light guide sheet (110) for guiding light, the light guide sheet being configured to receive light rays via at least one light incident edge (114) and reflect the light rays in a direction substantially normal to the light guide sheet; and at least one incident assembly (120), the at least one incident assembly being configured to receive light rays from an entry surface (121) and guide the light rays so as to incident them into the light incident edge of the light guide sheet; A light source (130), the light source being arranged to incident light rays into the entry surface of the at least one incident assembly; Wherein, the light guide sheet comprises a film (111), the film comprising at least one light extraction region (502.1, 502.4), the light extraction region comprising a microstructure (113), the microstructure being capable of redirecting the light incident into the flexible light guide sheet at least in the substantially normal direction; Wherein, the film comprises a microstructure on a first side (701) of the film and a microstructure on a second side (702) of the film; Wherein, for each part (503.1, 503.4) of the light extraction region having different respective distances from the light incident edge, the sum of the microstructure density on the first side in the part and the microstructure density on the second side in the part is an increasing function of the distance between the part and the light incident edge of the light guide sheet.

2. The light-emitting module according to claim 1, wherein the part (503.1; 503.4) of the light extraction region faces the same given section (501) of the light incident edge (114).

3. The light-emitting module according to claim 1 or 2, wherein The shape of the at least one light extraction region (502.1, 502.4) forms the light-emitting pattern of the light-emitting module (100).

4. The light-emitting module according to any one of the preceding claims, wherein, The film (111) further comprises at least one dark region (504) having no microstructure (113), and wherein the shape of the at least one dark region and the shape of the at least one light extraction region (502.1, 502.4) together form the light-emitting pattern of the light-emitting module.

5. The light guide sheet (110) of the light emitting module according to any one of the preceding claims is transparent, and wherein, For each part (503.1, 503.4) of the at least one light extraction region (502.1, 502.4), the microstructure density (113) on the first side (701) or the microstructure density on the second side (702) is less than or equal to a maximum density, the maximum microstructure density being determined such that the microstructure is invisible when there is no light incident through the light source.

6. The light-emitting module according to any one of the preceding claims, wherein, For the portions (503.1; 503.4) of the at least one light extraction region (502.1; 502.4) having different respective distances from the light incident edge (114), the microstructure density (113) on the first side (701) is a first increasing function of the distance between the portion and the light incident edge, wherein the first increasing function has a maximum microstructure density at least in the portion farthest from the light incident edge, and wherein the microstructure density (113) on the second side (702) is a second increasing function of the distance between the portion and the light incident edge, the maximum microstructure density being determined such that the microstructure is invisible when there is no light incident through the light source.

7. The light-emitting module according to the previous claim, wherein, The first increasing function is different from the second increasing function.

8. The light emitting module according to claim 6 or claim 7, wherein, The second increasing function has a maximum microstructure density at least in the portion farthest from the light incident edge.

9. The light emitting module according to claim 8, wherein, In portions (503.1; 503.4) of the light extraction region (111.1) other than the portion farthest from the light incident edge, the microstructure density (113) on the second side (702) is zero.

10. The light-emitting module according to one of claims 5 to 9, wherein, The first side (701) is oriented towards the outside of the light emitting module (100), and the second side (702) is oriented towards the inside of the light emitting module.

11. The light-emitting module according to any one of the preceding claims, wherein, The film (111) is made of polycarbonate PC, polymethyl methacrylate PMMA, thermoplastic polyurethane TPU, polyethylene terephthalate PET or silicone, and has a thickness between 50 micrometers and 1000 micrometers, and for example between 200 micrometers and 500 micrometers.

12. A motor vehicle device comprising a light emitting module (100) according to any one of the preceding claims.

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