EP4357666A1

EP4357666A1 - Automobile lamp

Info

Publication number: EP4357666A1
Application number: EP22202959.7A
Authority: EP
Inventors: Pavel Tucek; Milan Hradil; Tomás Kuchynka
Original assignee: Hella Autotechnik Nova sro
Current assignee: Hella Autotechnik Nova sro
Priority date: 2022-10-21
Filing date: 2022-10-21
Publication date: 2024-04-24

Abstract

An automobile lamp is provided, the lamp comprising a non-empty set of light sources (1), and a cover lens (2) wherein for each light source (1) from the set, the lamp further comprises a primary reflector (3) for narrowing a beam angle of light from the light source (1), and a secondary reflector (4) for reflecting light from the primary reflector (3) towards the cover lens (2) and out of the lamp. Each of the light sources (1) is thus provided with two individual reflectors for shaping and directing the light from this source. The cover lens (2) preferably comprises a diffractive structure.

Description

Technical field

The present invention relates to the field of automotive lighting. More specifically, it relates to a lamp for automobile, especially a headlight, using multiple reflectors for processing light from individual sources.

Background of the Invention

It is known in the state of the art to use reflectors in LED lamps for automobiles to reflect light from LED sources in a desired direction, to decrease divergence of the outputted beam of light etc. The known reflectors are however relatively large so they significantly increase size of the lamp or limit space for other components. Vehicle lamp with a reflector is described for example in document US10578267B2 .
It is also known in the state of the art to create cover elements for ceiling lights that comprise micro-optical diffractive structure for shaping, homogenizing, and directing light. Example of such a cover element is described in document GB2603775A .
It would therefore be advantageous to come up with a solution that would provide an automobile lamp with reflector system that could efficiently be used to process light from LED sources and would not require large amount of space.

Summary of the Invention

The shortcomings of the solutions known in the prior art are to some extent eliminated by an automobile lamp comprising a set of light sources and a cover lens. The set comprises at least one light source, preferably multiple light sources, e.g., at least five. The light sources are preferably LEDs. For each light source from the set, the lamp further comprises a primary reflector for narrowing a beam angle of light from the light source. The primary reflector therefore decreases divergence of the light beam produced by the light source. The beam angle is basically the apex angle of the cone of light from the light source, i.e., double the angle between the axis of the cone (which is optical axis of the source) and any edge of the cone connecting the apex with base of the cone. Preferably, the primary reflector is symmetrical with respect to the source optical axis. The primary reflector then makes the beam narrower but doesn't change its main direction. Part of the light can then pass through the primary reflector without being reflected by it.
For each light source from the set and thus for each primary reflector, the lamp further comprises a secondary reflector for reflecting light from the primary reflector (and possibly some light coming directly from the light source) towards the cover lens and out of the lamp. The secondary reflector is preferably shaped such that it produces light beam having more parallel rays, i.e., it further decreases divergence of the light between the primary reflector and secondary reflector. Each of the primary and secondary reflectors thus corresponds to a single light source from the set. The secondary reflectors can however be joined together for easier assembly of the lamp. It is also possible to join together the primary reflectors and/or to connect primary reflector(s) with secondary reflector(s).
Preferably, each primary reflector is made of reflective foil and has height less than 6 mm and diameter less than 10 mm. They can be shaped e.g., as circular paraboloids or parts thereof. Preferably, each primary reflector is placed on the same carrier as the respective light source. When viewed from side, i.e., perpendicularly to the emission direction of the light source (i.e., axis of the emitted light beam), the light source is preferably within 3 mm from the primary reflector, more preferably within 0.5 mm from the primary reflector.
Using two subsequent reflectors individually for each light source, where the primary reflector pre-processes the light beam by making it narrower, enables the secondary reflector to be relatively small, e.g., having width and/or height less then or equal to 2 cm. Standard reflectors used in lamps known in the state of the art are used without pre-processing of the light, which means they process wide beams, about 120° for standard LEDs, and thus have to be larger. The whole lamp thus has to be larger or can only contain smaller number of components and thus have fewer functions. Width and height are dimensions of the reflector which are perpendicular to the direction in which light leaves the secondary reflector, i.e., these dimensions are standardly visible on the lamp, and they limit space for other illumination components. The present invention is also significantly cheaper to make than lamps using lens optical systems.
Using primary reflectors - individual microreflectors for each light source, followed by secondary reflectors thus enables using standard, relatively cheap, LEDs to create high quality illumination assembly with relatively low costs and small dimensions. For example, a PCB (or other carrier) with a row of LEDs can be provided with small primary reflectors, attached directly to the PCB, and with secondary reflectors, thus forming an assembly having dimensions (when viewed from the illumination direction) of less than 20 mm X (length of the row of LEDs + less than 20 mm). The depth of this assembly, i.e., the dimension measured along the illumination direction, into which the light is reflected from secondary reflectors, can be e.g., less than 30 mm. The depth is however generally not as limiting as the other two (visible) dimensions, so it can be larger for many applications without complicating the construction of the lamp. The present invention thus provides a reflector illumination assembly which takes up less space without limiting efficiency of illumination, deteriorating lamp design, or significantly worsening any illumination parameters such as homogeneity, intensity, or formation of glares.
All the primary reflectors preferably have the same shape and size. All the secondary reflectors can have the same shape and size, but some can also be different, e.g., when adapted for re-reflecting light blocked by a shield, as described below. Primary reflectors are preferably substantially conical or paraboloidal, with axis coinciding with the optical axis of corresponding light source. The primary reflector preferably surrounds the optical axis of the light source in all directions perpendicular to the optical axis along part of the axis' length, i.e., the primary reflector forms a tunnel or passage through which the light beam from the source passes while being narrowed. The secondary reflectors than adjust direction of the light and preferably also improve homogeneity of the complete light beam from all the light sources from the set and/or decrease its divergence.
The cover lens preferably comprises a diffractive structure for homogenizing light passing out of the lamp through the cover lens. This structure preferably comprises microoptical elements, e.g., micro lens, smaller than e.g., 1 mm or 0.5 mm or even than 0.1 mm. Apart from improving homogeneity, this structure can also change direction of the outputted light, e.g., to prevent blinding oncoming drivers. The final shape and direction of the light outputted from the lamp can thus be affected by the primary reflectors, the secondary reflectors and also by the diffractive structure. The diffractive structure can be formed into the cover lens material, e.g., during its forming, but it can also be provided additionally, e.g., by attaching a structured foil to one of the surfaces of the cover lens.
Each primary reflector is advantageously adapted to from the beam and narrow the beam angle of the light from corresponding light source to less than 50°, preferably less than 40°, more preferably to less than 35°. I.e., the reflector can preferably make the angle at least two times smaller, preferably at least three times smaller. Light beams with this dispersion can then be reflected by relatively small secondary reflectors, e.g., smaller than 20x20 mm (width x height), without significant light losses or creation of glares.
The automobile lamp preferably further comprises a shield for creating a cut-off line, wherein the shield has its back surface adapted to reflect light back to at least one secondary reflector. A cut-off line is useful e.g., for using the lamp for low-beam applications. The reflection of light back to the secondary reflector(s) means, that the light blocked by the shield is not absorbed inside of the lamp, but is used for illumination. The shield can be adapted by having its back surface angled with respect to the light, so that the light is reflected towards the reflector(s) with orientation that allows it to be further processed, and also by having a reflective surface treatment. For example, the shield can have a metallic coating or can be made from reflective material. The shield can be movable in order to adjust position of the cut-off line or selectively provide illumination without the cut-off line (e.g., for high-beam applications).
Each primary reflector is advantageously made from a reflective foil. The foil can be e.g., shaped by vacuum forming from any foil that can be used for vacuum forming, e.g., 10 µm thick. The foil can be made reflective by a metallic coating, e.g., aluminum or TiO2, preferably after the forming. The foil as a material for the primary reflector(s) is preferable because it is relatively cheap, and the resulting reflector is light and thus can be easily attached to the light source or to its close proximity.
Each primary reflector can have its length, width, and height less than or equal to 10 mm, i.e., it can fit into a cube with side of 10 mm. Reflectors with these dimensions are generally called micro reflectors. Preferably, at least the height of the primary reflector(s) is less than or equal to 8 mm, more preferably less than or equal to 6 mm. The height, i.e., the dimension measured along the optical axis of the light source and/or geometrical axis of the primary reflector, is usually the most important dimension for the total size of the whole light source(s) + reflectors assembly, since it delimits the smallest distance between the secondary reflector and the light source. The length and width of the primary reflector are preferably the same since the reflector preferably has circular cross section along the optical axis.
Distance between each light source from the set of light sources and corresponding primary reflector can be less than 3 mm. It is preferable to have this distance as small as possible. Most preferably, the distance is substantially zero when viewed from direction perpendicular to the source optical axis. For example, the reflector can at least partially surround the light source, e.g., a LED can be attached to a carrier, such as a PCB, and the reflector can then also be attached to the same carrier and the LED is thus inside of the primary reflector. The amount of light that can be utilized by the reflector is thus maximized and the total size of the reflector assembly is decreased.
Each secondary reflector can have width and/or height of less than or equal to 20 mm, preferably 15 mm. The width can approximately correspond to distance between adjacent light sources. The secondary reflector(s) can have paraboloid shape, but preferably have a freeform shape, with individual points or areas of the reflector being individually adapted to reflect impacting light towards the cover lens, preferably parallel to the output illumination direction (e.g., substantially horizontally and towards the front of the vehicle when the lamp is (a part of) a headlight). Such a freeform shape can enable utilization of more light than a completely paraboloidal shape. The secondary reflector(s) can for example be made by injection molding, preferably all the secondary reflectors at once as a single piece. The functional surface of the reflectors can then be e.g., coated by a reflective material.
The distance between each primary reflector and the corresponding secondary reflector can be less than 10 mm, preferably is less than 5 mm, more preferably than 2 mm. This distance can be measured along the optical axis of the light sources, e.g., it can extend parallelly to the height of the reflectors.
The automobile lamp preferably further comprises a secondary light source adapted to illuminate the cover lens with a smaller intensity than the set of light sources and adapted to illuminate the cover lens at least part of the time when the light sources from the set are turned off. The lamp can thus emit a larger amount of light when the set of light sources is on and a smaller amount when the set is turned off and the secondary light source is on. The cover lens thus does not appear to be completely dark when the light sources from the set are off. This is especially advantageous for example when switching between different light modules during travel, e.g., when switching from high-beam lights (the lamp of the invention) to dipped lights (different lamp or module). This switching can normally significantly change the appearance of the vehicle, since only its lamps are visible in the dark, which might lead to a confusion regarding how many different vehicles are approaching as the vehicle completely changes appearance when switching between light modules. With this secondary illumination, the appearance of the vehicle stays substantially the same, only the brightness of the lamp is adjusted. The secondary illumination can also be useful e.g., when presenting a new vehicle, since the vehicle is preferably presented with lights on, but the light sources from the set can be too bright and would blind the onlookers.
The secondary illumination is preferably combined with the diffractive structure on the cover lens, so that the cover lens can appear homogenously lit even with only a small number of secondary light sources.
Preferably, each light source from the set has a carrier, such as a printed circuit board, to which the light source is attached, wherein the corresponding primary reflector is also attached to the carrier. Gluing can be used for attaching the primary reflector(s), especially if they are made from foil and are thus very light.
Preferably, each primary reflector comprises optical microstructures. These microstructures can be designed e.g., by a computer modeling software for a particular function, e.g., limiting divergence, or they can be randomly shaped for providing light dispersion. Size of elements forming the structure can e.g., be smaller than 0.1 mm. Microstructures can be formed e.g., during forming of the primary reflectors, e.g., they can be created by shape of the form used for the reflectors.

Description of drawings

A summary of the invention is further described by means of exemplary embodiments thereof, which are described with reference to the accompanying drawings, in which:

Fig 1.: Shows a schematic side view of the main optical components of the automobile lamp of the invention, namely a light source, a primary reflector, a secondary reflector and a cover lens.
Fig 2.: Shows a perspective view of optical components, wherein all the secondary reflectors are made from a single piece of material.

Exemplary Embodiments of the Invention

The invention will be further described by means of exemplary embodiments with reference to the respective drawings. The subject of the invention is an automobile lamp containing a set of light sources 1, especially LEDs, a cover lens 2 and two reflectors for each light source 1 from the set. A primary reflector 3, placed closer to the source, is adapted to decrease divergence of the light beam produced by the given light source 1, i.e., is adapted to make the beam narrower. A secondary reflector 4, placed farther from the given light source 1, is adapted to direct the narrowed light coming from the primary reflector 3, and potentially also in part directly from the light source 1, towards the cover lens 2 and then out of the lamp. The primary reflector 3 thus makes it possible to use a smaller secondary reflector 4, which could not efficiently reflect non-narrowed beams, and as a result, the two reflectors together can take up less space than what would be needed for a single reflector providing similar light processing function.
The lamp can be for example a headlight or a module of a headlight, e.g., module for high-beam and low-beam lighting. The lamp can also be a taillight, illuminated grill mask, daytime running light etc. In some embodiments, it can be an interior lamp; preferably however, it is an exterior automobile lamp. The lamp can further comprise a frame, holding other components of the lamp together and/or facilitating attachment of the lamp to the automobile. It can also comprise other electronical components, e.g., wiring, sensors, actuators, additional light sources 1 etc., other optical elements, such as lightguides or lens, other mechanical components etc. The cover lens 2 can be the outermost optical element of the lamp, but it can also be followed by another clear cover element, e.g., common for the whole headlight when the lamp is a module inside the headlight.
In the exemplary embodiment, depicted in figs. 1 and 2, the primary reflector 3 is oriented approximately perpendicularly to the secondary reflector 4. For example, they can be oriented with angle from 70 to 110 degrees, i.e., the main direction into which the primary reflector 3 sends light and the main direction in which the reflected light beam from the secondary reflector 4 is sent have this angle between them. The relative angle of the two reflectors for any given light source 1 from the set can however generally by arbitrary, depending on construction of the rest of the lamp.
The primary reflector(s) 3 is preferably made of foil having a light-reflection surface treatment on at least one of its sides, which is to form the inner side of the reflector. For example, it can be pressed or vacuum-formed into the desired shape, e.g., parabolical shape, wherein the reflector has height of 3-10 mm preferably 3-6 mm and has diameter on the end further from the light source 1 of 5-10 mm. The height is the dimension measured in the direction of the light beam outputted by the light source 1 (optical axis of the light source 1). The diameter, i.e., the length and width of the reflector, is then measured in two directions perpendicular to each other and the height. The surface treatment can be e.g., made by vacuum evaporation of aluminum or TiO2. TiO2 is preferable since it has better reflectiveness, however it can be more expensive than aluminum layer. Alternatively to the parabolical/paraboloid shape of the primary reflector 3, any other shape can be chosen by a skilled person. For example, a freeform primary reflector 3 can be advantageous for some applications, e.g., if the light beam needs to be not only narrowed but also sent to a different direction.
The primary reflectors 3 can be provided with microstructures, e.g., facets with orientation configured for forming the light beam passing through the reflector, e.g., for limiting divergence, changing direction of the light beam, decreasing inhomogeneities, etc. Size of the microstructures can be e.g., up to 0.1 mm or up to 0.05 mm.
For typical LEDs, the beam angle is about 120°. The primary reflector 3 is preferably shaped such that after passing through the reflector, the beam angle is less than 50°, preferably less than 40°, preferably less then 35°. The smaller the beam angle, the smaller can then be the secondary reflector 4 without increasing light losses. The secondary reflector 4 can have parabolical shape. Preferably, it is a freeform reflector, e.g., designed by a computer simulation for specific lamp construction (e.g., according to the choice of the light source 1, shape of primary reflector 3, design of the output lens, size of the lamp, purpose of the lamp etc.). The height and/or width of each secondary reflector 4 is advantageously less than or equal to 20 mm. Preferably the dimension having this size is at least the one measured perpendicularly to the direction in which the light leaves the lamp and perpendicularly to direction towards adjacent secondary reflector(s) 4. For example in a headlight, the set of light sources 1 might be a row of LEDs arranged from left to right, the direction of the light outputted by the lamp is parallel to the longitudinal axis of the automobile, and the height of the secondary reflector(s) 4 is then measured vertically and is preferably max 20 mm. If the light sources 1 are arranged in a column, the width of the secondary reflector(s) 4, measured from left to right, is the dimension having max 20 mm.
Each primary reflector 3 is preferably attached (e.g., glued or attached via mechanical fixtures) as close to corresponding light source 1 as possible, e.g., the reflector can be attached to a printed circuit board carrying the LED light source 1. The LED can the partially or completely be located inside the reflector. Preferably, the primary reflector 3 for each light source 1 from the set is located within 5 mm from the secondary reflector, more preferably within 2 mm. The primary reflector(s) 3 can even partially be located inside the secondary reflector(s) 4. Distance between each light source 1 from the set of light sources 1 and a corresponding primary reflector 3 is preferably less than 3 mm, more preferably than 1 mm. This distance can be measured along the optical axis of the light source 1.
The secondary reflector 4 can e.g., be made by injection molding, e.g., from PMMA or polycarbonate, and then provided with a reflective surface treatment. In some embodiments, the primary reflector 3 can also be made by a different method such as injection molding or machining.
The light sources 1 from the set of light sources 1 are preferably arranged in an array, e.g., in a row. All the secondary reflectors 4 can then be made from one piece in order to simplify assembly of the lamp. The light sources 1 can e.g., be on a common carrier, such as a printed circuit board. Preferably, each light source 1 and its primary reflector 3 and secondary reflector 4 are sized and arranged such that when viewed from the direction in which the light is outputted from the lamp (i.e., direction from the back of the vehicle to the front for a standard headlight), they together have width smaller than 20 mm, preferably then 15 mm and height smaller than 20 mm, preferably then 15 mm or even than 10 mm.
The lamp can comprise a shield for creating a cut-off line, e.g., the cut-off line preventing blinding of other (oncoming) drivers when using low-beam lights. The shield can be positioned between some secondary reflector(s) 4 and the cover lens 2. The shield is preferably constructed such that the light it blocks gets reflected back to the secondary reflector(s) 4 and thus can be subsequently reflected again and sent towards the cover lens 2 and used for illumination. If freeform reflectors are used, the part of the secondary reflector(s) 4 receiving the light blocked by the shield, is adapted by its shape and orientation to reflect this light towards the cover lens 2, e.g., substantially parallelly to the rest of the light reflected by the secondary reflector(s) 4. This reflection of light by the shield can be achieved by orienting the shield, or at least its back surface facing the secondary reflector(s) 4, at a non-perpendicular angle with respect to direction from the secondary light source(s) 1 to the cover lens 2. The shield can also have a reflective surface treatment on the back surface. Preferably, the shield is movable, e.g., by an electromotor, for switching between modes with and without the cut-off line, e.g., between high-beam and low-beam lights.
The cover lens 2 can have a diffractive structure one its inner and/or outer surface for homogenizing the light passing therethrough. This structure can be e.g., engraved in the surface, can be injection-molded together with the lens etc. The structure can be formed from individual micro-lens elements, e.g., grooves, protrusions, depressions, mutually angled surfaces, etc. smaller than 1 mm, preferably than 0.1 mm. These elements are preferably designed firstly to homogenize the light and secondly to direct the light. This directing can e.g., be adapted to prevent blinding oncoming drivers by angling the outputted light towards the road.
The lamp preferably comprises at least on secondary light source for illuminating the cover lens 2 when the light sources 1 from the set of light sources 1 are turned off. The intensity of illumination by the secondary light source is smaller, e.g., less than third, preferably less than fifth, more preferably less than tenth, of the intensity of illumination by the set of light sources 1. This secondary light source is adapted, e.g., is controlled by a lamp controller unit or by an automobile main computer, to be turned on when the set of light sources 1 is turned off. Preferably, the lamp is a headlight or a part of a headlight, wherein the secondary light source is on when the set of light sources 1 is off and some other light source is on. The other light source can be for example a dipped beam light module, while the set of light sources 1 provides a high beam and/or low beam function(s). Therefore, the cover lens 2 can provide intensive illumination when the set of light sources 1 is on, and when the light sources 1 from the set are off, the cover lens 2 is not completely dark but is still slightly illuminated, at least when some other light such as dipped beam is on.
The secondary light source can illuminate the cover lens 2 directly or it can be provided with an additional optical element such as lens or reflector. For example, the secondary light source can by provided with a primary reflector 3 and secondary reflector 4, similarly to the light sources 1 from the set. The secondary light source can in some embodiments be one or several of the light sources 1 from the set, controllable separately from the rest.
In the preferred exemplary embodiment, the lamp is a high and/or low beam lamp of a headlight. The set of light sources 1 comprises a row of multiple LEDs, e.g., at least 5 or at least 10 LEDs, arranged from left to right in a substantially horizontal line in equal distances from each other. The primary reflectors 3 are made from foil with reflective coating and each primary reflector 3 is located around the corresponding LED. All the primary reflectors 3 have the same size and shape. The secondary reflectors 4 are all joined together, e.g., made from one piece. Each secondary reflector 4 is located directly below the corresponding primary reflector 3 and the LED. The beam angle of the light heading towards the secondary reflector 4 is less then 40°. The primary reflectors 3 have diameter at the end farther from the LED of 8 mm, height of the primary reflectors 3 is 4 to 5 mm. The height of the optical assembly of the set of light sources 1, the primary reflectors 3 and the secondary reflectors 4 is less then 20, preferably than 15, mm. The cover lens 2 is provided with diffractive structure which homogenizes the light and is provided with at least one secondary light source for the secondary illumination when the light sources 1 from the set are turned off. A shield can be provided in front of some of the secondary reflectors 4 to reflect portion of the light back and to create a cut-off line.

List of reference numbers

1: - light source
2: - cover lens
3: - primary reflector
4: - secondary reflector

Claims

Automobile lamp comprising a non-empty set of light sources (1), and a cover lens (2) characterized in that for each light source (1) from the set, the lamp comprises a primary reflector (3) for narrowing a beam angle of light from the light source (1), and a secondary reflector (4) for reflecting light from the primary reflector (3) towards the cover lens (2) and out of the lamp.
The automobile lamp according to claim 1, wherein the cover lens (2) comprises a diffractive structure for homogenizing light passing out of the lamp through the cover lens (2).
The automobile lamp according to any of the previous claims, wherein each primary reflector (3) is adapted to narrow and form the beam angle of the light to less than 50°.
The automobile lamp according to any of the previous claims, wherein it further comprises a shield for creating a cut-off line, wherein the shield has its back surface adapted to reflect light back to at least one secondary reflector (4).
The automobile lamp according to any of the previous claims, wherein each primary reflector (3) is made from a reflective foil.
The automobile lamp according to any of the previous claims, wherein each primary reflector (3) has its length, width, and height less than or equal to 10 mm.
The automobile lamp according to any of the previous claims, wherein distance between each light source (1) from the set and corresponding primary reflector (3) is less than 3 mm.
The automobile lamp according to any of the previous claims, wherein each secondary reflector (4) has width and/or height of less than or equal to 20 mm.
The automobile lamp according to any of the previous claims, wherein distance between each primary reflector (3) and the corresponding secondary reflector (4) is less than 10 mm.
The automobile lamp according to any of the previous claims, wherein it further comprises a secondary light source (1) adapted to illuminate the cover lens (2) with a smaller intensity than the set of light sources (1) and adapted to illuminate the cover lens (2) when the light sources (1) from the set are turned off.
The automobile lamp according to any of the previous claims, wherein each light source (1) from the set has a carrier, to which the light source (1) is attached, wherein the corresponding primary reflector (3) is also attached to the carrier.
The automobile lamp according to any of the previous claims, wherein each primary reflector (3) comprises optical microstructures.