Light emitting module including an element with variable light transmittance

Abstract

The present invention relates to a light emitting module (1) for an automotive vehicle, the light emitting module (1) comprising: - A light source (2), - a projection optical system (3) designed to project a light field (S) onto the ground; According to the present invention, the light emitting module further comprises an element having variable light transmittance disposed between the light source and the projection optics, said element having variable light transmittance comprising at least one first portion and at least one second portion, each of which has a different light transmittance such that the image areas formed by the first portion and the second portion, respectively, have the same luminous intensity.

Description

[Technical field]

[0001] The present invention relates to the field of lighting devices for motor vehicles. The present invention relates to a lighting module that is particularly suitable for performing auxiliary functions, and in particular to a lighting module that projects a light field onto the ground in the vicinity of the vehicle, in particular adjacent to the door. [Background technology]

[0002] To improve the user experience of a vehicle, lighting modules with illumination directed toward the ground are installed on the rearview mirror or on the side of the vehicle below the door jamb. These lighting modules are positioned to project light onto the ground, illuminating an area adjacent to the door. Generally, the illuminated area forms a light field and extends longitudinally along the vehicle's main axis.

[0003] Such lighting modules can be switched on before passengers and drivers enter the vehicle and / or before they prepare to exit the vehicle. As a result, passengers and drivers can see the ground conditions more clearly and can see if there are any uneven surfaces that could cause them to trip. The described lighting modules therefore improve user safety.

[0004] Additionally, the light-emitting module may include an additional element capable of projecting a pattern onto the ground. This pattern may be included in the light field or may itself form the light field. The projected pattern may be the vehicle manufacturer's insignia, logo, or aesthetic image. The element projected onto the ground may include information, for example, weather-related information.

[0005] The described lighting module can be connected to a control device, so that the lighting module is switched on when the user remotely starts the vehicle and remains on until the user enters the vehicle. Therefore, such lighting devices can be used to create a "hospitality scenario," thereby increasing the user's satisfaction with the vehicle.

[0006] However, such a light-emitting module has a drawback in that it forms a light irradiation field with non-uniform luminous intensity at all locations.

[0007] The described light-emitting module is often installed so as to project light along an axis inclined downward with respect to the horizontal such that the light irradiation field can extend longitudinally toward the rear of the vehicle. By making such a projection, the luminous intensity of the light irradiation field decreases when a person moves away from the light source.

[0008] This defect is prominent when the light-emitting module is installed at a low height, for example, under the door of a vehicle. In this case, the projection axis is further inclined and the projection angle is further decreased. As a result, the projected light is inclined. Consequently, the luminous intensity of the light irradiation field on the ground gradually decreases when a person moves away from the light-emitting module. In other words, the light irradiation field is divided into several regions having different luminous intensities. The region near the light-emitting module has a stronger intensity than the region far away from the device.

[0009] The smaller the projection angle, the more inclined the projection and the larger the ratio of the dark region, or the region with low luminous intensity.

[0010] Furthermore, the difference in the brightness of the light irradiation field is even more prominent when the light irradiation field is formed by a pattern. SUMMARY OF THE INVENTION

[0011] In view of this problem, one object of the present invention is to design a light-emitting module capable of projecting a light irradiation field with uniform luminous intensity onto the ground.

[0012] With this object in mind, the light-emitting module according to the present invention includes - a light source, and - a projection optical system designed to project a light irradiation field onto the ground. and includes.

[0013] According to the present invention, the light emitting module further includes an element having a variable light transmittance disposed between the light source and the projection optical system, and the element having the variable light transmittance is - a first part that receives light rays suitable for forming a first area of the light irradiation field, - a second part that receives light rays suitable for forming a second area located farther from the light source than the first area of the light irradiation field. It includes.

[0014] In addition, the first part has a light transmittance called the first light transmittance, which is lower than the light transmittance of the second part called the second light transmittance.

[0015] Furthermore, the first light transmittance and the second light transmittance are defined such that the luminous intensity of the first area is substantially equal to the luminous intensity of the second area.

[0016] In other words, the light transmittance changes inside the proposed element, and thus it is named "element having variable light transmittance". Specifically, the first part of the element having variable light transmittance is more opaque than the second part of the element. The first part allows less light to pass through than the second part. In addition, the opacity of the first part and the second part is defined such that the luminous intensity of the first area is reduced so as to reach the same luminous intensity as the second area.

[0017] Therefore, by incorporating the proposed light emitting module into the above-described light emitting device, the luminous intensities of two different areas of the light irradiation field become uniform despite the different positions with respect to the light source.

[0018] The light irradiation field thus obtained has the same luminous intensity over its entire range, thereby improving the quality of the light irradiation field and satisfying the observer, especially the user of the vehicle in which the light emitting module is installed.

[0019] In this specification, the projection optical system creates, at a distance (finite or infinite) that is very large (at least about 30 times, preferably about 100 times) compared to the size of the module, an actual image of a part of the module, such as the light source itself, or an intermediate image of the light source, and optionally an anamorphic image. This projection optical system can be composed of one or more reflectors, one or more lenses, one or more light guide plates, or further possible combinations thereof.

[0020] The light source can be a solid - state light source. The term "solid - state" refers to light emitted by solid - state electroluminescence, which converts electricity into light using semiconductors. Compared to incandescent lighting, semiconductor lighting generates visible light with less heat generation and less energy dissipation. Generally lightweight semiconductor electro - luminescent devices provide greater resistance to shock and vibration than fragile glass tubes / light bulbs and long, thin filament wires. Such devices are not affected by filament evaporation, which can improve the service life of the light - emitting device. Some examples of this type of lighting include semiconductor light - emitting diodes (LEDs), organic light - emitting diodes (OLEDs), or polymer light - emitting diodes (PLEDs) as light sources instead of electric filaments, plasmas, or gases.

[0021] The light - emitting module according to the present invention can optionally have one or more of the following features: - The light - emitting module includes a slide disposed between the light source and the projection optical system with a projected pattern, and in addition, an element having a variable light transmittance is disposed on the slide. - The slide includes a first surface facing the projection optical system and a second surface facing the light source. The first surface is disposed within the focal plane of the projection optical system and includes a pattern to be projected. This projected pattern is included in the light irradiation field, and thus the sharpness of the projected pattern provided by the slide is improved. As an example, the pattern can be a seal, a logo, or an image of an object, and the pattern can be made using a photolithography or laser engraving process. In this case, the light irradiation field consists of a plurality of elements, and these elements are distinguished from each other using different contrasts between the elements. - According to an exemplary embodiment, the slide is designed such that the light irradiation field is formed by the projected pattern. - According to an example, the slide includes a transparent support that allows all light rays reaching the slide to pass through without deviating from their path. - An element having a variable light transmittance is disposed on the first surface of the slide. Thus, the element having a variable light transmittance and the pattern are disposed on the same surface of the slide. Such a slide is manufactured in a short time and at low cost because the surface treatment is concentrated on one side. - An element having a variable light transmittance is disposed on the second surface of the slide. In other words, the element having a variable light transmittance and the pattern are disposed on two different surfaces of the slide. As a result, the quality of the light irradiation field is further improved. Since the element having a variable light transmittance is not disposed within the focal plane of the projection optical system, the components forming a part of this element appear blurred or even invisible within the light irradiation field, and the quality of the image projected onto the ground is guaranteed because only the projected pattern appears sharp. - According to an example, the light irradiation field consists of a projected image of the light source. In this case, the light emitting module is used to generate uniform light spots and enables illumination in the vicinity of the vehicle. - The element having a variable light transmittance has a variable thickness. As an example, this element is formed by a metal layer, particularly a layer made of chromium, and the light transmittance is inversely proportional to the thickness, i.e., the greater the thickness, the lower the transmittance. - the element with variable light transmittance is formed by a layer comprising a plurality of elementary units, called the layer with variable light transmittance, the elementary units being distributed in such a way that the density of the elementary units in a first portion is higher than the density of the elementary units in a second portion, in other words, said layer is made up of a plurality of portions with elementary units at different densities, thus taking inspiration from the technique of dithering in the field of printing to create almost opaque areas that let through part of the light rays in order to reduce the luminous intensity in desired areas, in particular in areas located near the light source; - in one exemplary embodiment, the layer with variable light transmittance comprises elementary units with a density that gradually varies within each portion, this gradual variation continuing from one portion to another, in other words, the layer with variable light transmittance comprises elementary units with a density that gradually varies throughout the layer, as an example, the layer with variable light transmittance has elementary units whose density exhibits a gradual variation in a given orientation (horizontal, vertical, diagonal) and in a given direction (from top to bottom or vice versa, from right to left or vice versa); - For example, in each part the basic units are evenly distributed and the basic units are spaced the same distance from each other; - The base unit is completely opaque, - The basic unit is made from metal, for example it can be made from chrome or aluminum, - The size of each basic unit is about a few micrometers, for example, about 3 micrometers. - The basic units are identical and are simple and practical to manufacture; - Layers with variable light transmittance are obtained using a photolithography process, a precise and flexible manufacturing method that can be adapted to various ways of dispersing the elementary units; - the element with variable light transmittance further comprises a transparent third part that receives light rays suitable for forming a third area of the light field located farthest from the light source, and when the element with variable light transmittance is composed of layers provided with basic units, the third part is not provided with basic units; - according to one example, the second part is located between the first and third parts, so that the opacity decreases from the first part to the third part, as a result of which the luminous intensity of the first area decreases to reach the luminous intensity of the third area, which is located furthest from the light source; - The light-emitting modules are positioned so that the projection axis of light from said modules is inclined downward relative to the horizontal and a light field is formed by the intersection of the light with the ground, where horizontal means an axis parallel to the ground surface on which the vehicle is located. The projection optics comprises a number of lenses, which are stacked one on top of the other, for example to form a block.

[0022] Another object of the invention relates to a lighting device for a motor vehicle, which comprises a lighting module according to the invention.

[0023] Optionally, the light emitting device is located under the vehicle door, particularly the front door.

[0024] In another example, the light emitting device is installed in the rearview mirror of a vehicle.

[0025] Further innovative features and advantages will become apparent from the following description, given by way of non-limiting indication with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0026] [Figure 1] 1 shows a side view of an automotive vehicle including a light emitting module according to an exemplary embodiment of the present invention. [Figure 2] 2 shows a cross-sectional view of the light-emitting module of FIG. [Diagram 3] 2 shows a schematic perspective view of a first face of a slide forming part of the light emitting module of FIG. 1; [Figure 4] 2 shows a schematic perspective view of a second face of a slide forming part of the light emitting module of FIG. 1; [Diagram 5] The rear view of the device of Figure 3 is shown with details A, B and C. [Figure 6]Fig. 3 and Fig. 4 show a cross-sectional view of the slide along the plane passing through line VI-VI shown therein.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring to these figures, particularly Fig. 1, the motor vehicle 10 includes a front door 11 and a rear door 13 on the left side shown. A lighting device including a light-emitting module 1 (not visible in Fig. 1) is installed in a door frame 12 located under the front door 11 and the rear door 13. In the example shown, the lighting device is located at the front end of the door frame 12 and is arranged to project a light irradiation field S extending parallel to the main axis P of the vehicle 10 onto the ground. The projection axis makes an angle α with the horizontal axis.

[0028] The lighting device functions as side means for illuminating the space located adjacent to the front and rear entrance doors.

[0029] Here, the light irradiation field S extends to the rear of the vehicle 10. In the prior art, the light irradiation field has a variable luminous intensity, and sometimes differences in luminous intensity are made in different visible areas of this light irradiation field, that is, areas that are darker than other areas can be distinguished.

[0030] Assuming that the lighting device includes a light-emitting module 1 manufactured according to the principle of the present invention, the light irradiation field S has a uniform luminous intensity over the entire range. In other words, the light irradiation field S is not divided into several areas having different luminous intensities, but here it consists of a single area having the same luminous intensity everywhere.

[0031] Therefore, the quality of the light irradiation field is improved. To achieve this, the lighting device includes a light-emitting module 1 schematically shown in Figs. 2 to 6.

[0032] In Fig. 2, the light-emitting module 1 includes a light source 2, a projection optical system 3, and a slide 5 disposed between the light source 2 and the projection optical system 3.

[0033] Here, the light source 2 is an LED (light-emitting diode). Other types of light sources are also conceivable. The light source 2 can include one or more LEDs. Here, a collimator 20 is disposed in front of the light source 2 in order to create light derived from parallel light rays directed toward the slide 5 and the projection optical system 3.

[0034] In the example shown, the projection optical system 3 has a focal plane F and is composed of a plurality of lenses 30 that are overlapped and stacked on one another. Here, there are four lenses.

[0035] Each of the lenses 30 includes a central portion 301 having a refractive surface and an outer ring portion 302 surrounding the central portion 301. The refractive surface is configured to project the light rays from the light source 2 while limiting or further removing optical aberrations such as distortion aberration.

[0036] The outer ring portion 302 is provided with engaging means suitable for interacting with complementary engaging means of the outer ring portions of adjacent lenses. As an example, the engaging means can include grooves or ribs.

[0037] To ensure that all of the lenses 30 are sufficiently held, the lenses 30 are installed in a lens holder (not shown in FIG. 2) that grasps both ends of the assembly. For this purpose, the lens holder includes the outer ring portion of the first lens of the assembly and the end portion that presses the last lens.

[0038] Here, the slide 5 is, as an example, a transparent plate 53 having a rectangular cross section. The slide 5 can be made of glass or plastic, for example, polyethylene terephthalate (PET). The slide 3 has a first surface 51 and a second surface 52. The slide is disposed in the light-emitting module 1 such that the first surface 51 faces the projection optical system 3 and the second surface 52 faces the light source 2. The first surface 51 is also known as the downstream surface, and the second surface 52 is also known as the upstream surface. The terms "upstream" and "downstream" are defined in the direction of light propagation within the light-emitting module 1.

[0039] As shown in FIG. 3, the pattern 510 is formed on the first surface 51 of the slide 5. The pattern 510 is projected onto the ground to form a light irradiation field S. In this example, the pattern 510 is the character "V".

[0040] The pattern 510 is obtained by a process of treating the surface of the first surface 51. This process is, for example, a photolithography process that creates a transparent region 510 and an opaque region 511 on the first surface 51. The opaque region 511 is covered with an opaque layer 513 (visible in FIG. 6) that does not allow light to pass through, specifically a layer of chromium oxide. The opaque layer 513 can be made of other materials, such as aluminum or silver. In the transparent region 510, the first surface 51 remains uncovered, that is, the first surface 51 is not covered with a material. Therefore, light rays can pass through the transparent region 510 and reach the projection optical system 3. Therefore, the transparent region forms the projected pattern 510. The first surface 51 is disposed within the focal plane F of the projection optical system 3 so that the image of the pattern is projected infinitely and becomes clear on the projection surface.

[0041] In another example, the transparent region can be covered by a transparent layer that allows all light rays reaching the transparent region to pass through.

[0042] FIGS. 4 and 5 show the second surface 52 of the slide 5. According to the present invention and this example, an element 4 having a variable light transmittance is disposed on the second surface 52. Here, the element 4 having a variable light transmittance extends within a region 520 surrounded by a circle P shown in FIG. 4. Since the region 520 is disposed opposite to the pattern 510 on the first surface 51, it is also known as the active region 520. In other words, the active region 520 receives light rays, and these light rays then reach the pattern 510.

[0043] The remaining portion of the second surface 52 that is not disposed opposite to the pattern 510 is known as the inactive region 525. An opaque coating layer is deposited on this inactive region 521 to prevent stray light rays that may reach the projection optical system 3 and be captured within the light irradiation field S. This opaque coating layer can be of the same type as the opaque layer 513 deposited on the first surface 51.

[0044] Here, the element with variable light transmittance is formed by a material layer 4 comprising a number of elementary units 400 spaced apart from one another.

[0045] The distance between one basic unit 400 and the adjacent unit can be varied within the material layer 4 .

[0046] As shown in FIG. 5, the material layer 4 includes elementary units at a density that decreases from top to bottom in FIG. 5, as indicated by the arrow F. For example, the density of elementary units decreases continuously from top to bottom. This decrease can be linear or nonlinear. In other words, the material layer 4 can be divided into multiple portions that are continuous with each other in the direction of extension of the material layer, as indicated here by the arrow F. Each portion can be very small and can include elementary units at a specified density. Any portion has elementary units at a higher density than the portion immediately below it.

[0047] Here, the material layer 4 extends partially within the active area 520 of the second side 52 of the slide 5. Here, the elementary units are arranged in a portion of the active area 520 in a decreasing density from top to bottom in this portion. The remaining part of the active area 520 is not provided with elementary units. This remaining part is also known as the area not covered by the material layer 4 and is indicated by 523 in Figures 4 and 5.

[0048] By way of example, the distribution of elementary units in the upper portion 41 of the material layer 4 is shown in the enlarged view designated "A" in Figure 5. The distribution of elementary units in the middle portion 42 of the material layer 4 is shown in the enlarged view designated "B" in Figure 5. Note that the density of elementary units is higher in the upper region 41 than in the middle region 42. Another enlarged view designated "C" in Figure 5 shows the distribution of elementary units in the lower portion 43, which gradually decreases in density down to the region 523 not covered by the material layer 4.

[0049] In another exemplary embodiment, the basic units can be arranged with variable density across the entire active region 520 of the second face 52. In this case, the region 523 is covered by the basic units with a lower density.

[0050] According to another exemplary embodiment, the basic units can be dispersed into several groups having a constant density, and the density varies from group to group. In this case, the arrangement of these groups relative to each other is determined by how the light-emitting module is mounted on a vehicle, for example, not tilted with respect to the ground, i.e., projected vertically. Additionally, dispersing into groups of basic units having a constant density may be particularly suitable for patterns of surfaces having contrasting luminance.

[0051] Returning to the illustrated example, in FIG. 6, it can be seen that the basic units 400 are of the same size, which enables the material layer 4 to have a constant thickness. Additionally, the material layer 4 having the same basic units is easy to manufacture.

[0052] The basic unit 400 is manufactured from an opaque material. Here, the basic unit 400 is made of a metal, such as chromium or aluminum. Optionally, the basic unit 400 can be made of the same material as the layer covering the inactive region 525.

[0053] Each basic unit, by being opaque itself, prevents the incoming light rays from passing through itself. In addition to the above, the basic unit 400 can be of a dark color, or even black.

[0054] The presence of the basic units 400 on the second face 52 of the slide reduces the amount of light rays that can reach the second face 52, pass through the slide body 53, and reach the first face 51. In other words, the basic unit 400 affects the transparency of the slide. The more basic units 400 there are, the more opaque the relevant part of the slide becomes. The opacity of this part is related to the density of the basic units 400 present thereon.

[0055] The layer 4 containing the above-described elementary units 400 is known as a layer with variable light transmittance because it modifies the opacity of the slide in a manner that varies across the second surface 52. The portion of the second surface 52 covered by the layer 4 has an opacity that varies in proportion to the density of the elementary units in this layer 4. The upper portion 521 of the active area 520 is more opaque than the middle portion 522 of the same area. Finally, the area 523 where no elementary units 400 are provided maintains its original transparency.

[0056] As described above, the slide 5 has a layer 4 with variable light transmittance, and is therefore positioned within the light-emitting module 1 so that the light rays reaching the upper portion 521 and the middle portion are suitable for forming a plurality of zones of the light field S near the light source. These zones are designated S1 and S2 in FIG. 1. At the same time, the light rays reaching the region 523 contribute to forming the zone of the light field farthest from the light source. This zone is designated S3 in FIG. 1.

[0057] As a result, the luminous intensity is the same throughout the light field S, because the amount of light rays forming the first and second zones S1 and S2 is reduced to the same extent as the amount of light rays forming the third zone S3. This reduction results from the presence of basic units 400 in portions 521 and 522 of the second surface 52, which prevents some of the light from passing through the slide 5.

[0058] The layer with variable light transmittance therefore makes it possible to improve the uneven distribution of the light field in the prior art, where the area closest to the light-emitting module and therefore the light source has a greater luminous intensity than the area located a little further from the light source. Thanks to the layer with variable light transmittance, the luminous intensity of the first area, which is more illuminated, is reduced to reach the same luminous intensity as the second area, which is located further from the light source and therefore less illuminated.

[0059] Needless to say, the present invention is not limited to the above-described examples. Various changes can be made to the described examples without departing from the scope of the present invention.

[0060] For example, the pattern formed on the first surface of the slide may be different. The number of portions of the layer having variable light transmittance, and thus the number of portions into which the second surface is divided, may be different. Other materials and other processes can also be considered for forming the layer having variable light transmittance.

Claims

1. - A light source (2), - A projection optical system (3) designed to project a light irradiation field (S) onto the ground, A light emitting module (1) for an automotive vehicle, comprising: The light emitting module further includes an element (4) having a variable light transmittance disposed between the light source and the projection optical system, and the element having the variable light transmittance is - A first portion (41) that receives light rays suitable for forming a first area (S1) of the light irradiation field, - A second portion (42) that receives light rays suitable for forming a second area (S2) of the light irradiation field located farther from the light source than the first area of the light irradiation field, Including: The first portion has a light transmittance called a first light transmittance, which is lower than the light transmittance of the second portion, called a second light transmittance, The first light transmittance and the second light transmittance are defined such that the luminous intensity of the first area is substantially equal to the luminous intensity of the second area, A light emitting module (1) including a slide (5) disposed between the light source (2) and the projection optical system (3) with a projected pattern, and the element having the variable light transmittance is disposed on the slide (5).

2. The slide (5) includes a first surface (51) facing the projection optical system (3) and a second surface (52) facing the light source (2). The first surface is disposed within the focal plane (F) of the projection optical system (3) and includes the projected pattern, and the projected pattern is included in or forms the light irradiation field (S). The light emitting module (1) according to claim 1.

3. The light emitting module (1) according to claim 2, wherein the element (4) having the variable light transmittance is disposed on the first surface (51) of the slide (5).

4. The light emitting module (1) according to claim 2, wherein the element (4) having the variable light transmittance is disposed on the second surface (52) of the slide (5). ​ ​ ​ ​ ​ - A second portion (42) that receives light rays suitable for forming a second region (S2) located farther from the light source than the first region of the light irradiation field. Including The first portion has a light transmittance called a first light transmittance, which is lower than the light transmittance of the second portion, called a second light transmittance. The first light transmittance and the second light transmittance are defined such that the light intensity of the first region is substantially equal to the light intensity of the second region. The element having a variable light transmittance is formed by a layer (4) including a plurality of basic units (400) known as a layer having a variable light transmittance. The basic units (400) are distributed such that the density (μ1) of the basic units of the first portion (41) is higher than the density (μ2) of the basic units of the second portion (42). Light emitting module (1).

6. The light emitting module (1) according to claim 5, wherein the basic unit (400) is completely opaque.

7. The light emitting module (1) according to claim 5, wherein the basic unit (400) is made of metal.

8. The light irradiation field consists of a projected image of the light source (2). The light emitting module (1) according to any one of claims 1 to 7.

9. The element having a variable light transmittance has a variable thickness. The light emitting module (1) according to any one of claims 1 to 7.

10. The element (4) having a variable light transmittance further includes a transparent third portion (43) that receives light rays suitable for forming a third region (S3) located farthest from the light source (2) of the light irradiation field. The light emitting module (1) according to any one of claims 1 to 7.

11. The light emitting module (1) according to claim 10, wherein the second portion (42) is located between the first portion (41) and the third portion (43).

12. The projection optical system (3) includes a plurality of lenses (30) that are overlapped and laminated with each other. The light emitting module (1) according to any one of claims 1 to 7.

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